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Characterization and Control of Nanoparticle Emission during 3D Printing

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Abstract

This study aimed to evaluate particle emission characteristics and to evaluate several control methods used to reduce particle emissions during three-dimensional (3D) printing. Experiments for particle characterization were conducted to measure particle number concentrations, emission rates, morphology, and chemical compositions under manufacturer-recommended and consistent-temperature conditions with seven different thermoplastic materials in an exposure chamber. Eight different combinations of the different control methods were tested, including an enclosure, an extruder suction fan, an enclosure ventilation fan, and several types of filter media. We classified the thermoplastic materials as high emitter (>10¹¹ #/min), medium emitters (10⁹ #/min −10¹¹ #/min), and low emitters (<10⁹ #/min) based on nanoparticle emissions. The nanoparticle emission rate was at least 1 order of magnitude higher for all seven filaments at the higher consistent extruder temperature than at the lower manufacturer-recommended temperature. Among the eight control methods tested, the enclosure with a high-efficiency particulate air (HEPA) filter had the highest removal effectiveness (99.95%) of nanoparticles. Our recommendations for reducing particle emissions include applying a low temperature, using low-emitting materials, and instituting control measures like using an enclosure around the printer in conjunction with an appropriate filter (e.g., HEPA filter) during 3D printing.

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... However, not all facets of 3D printing are devoid of challenges. International literature raises alarm bells about potential risks related to inhaled nanoparticles (Chan et al. 2020;Runstrom Eden et al. 2022;Zhang et al. 2018;Kwon et al. 2017;Stefaniak et al. 2017) and volatile organic compounds (VOCs) (Zhang et al. 2018;Stefaniak et al. 2017; Mohammadian and Nasirzadeh 2021;Floyd et al. 2017), and other chemicals. These risks are even more pronounced when users employ 3D pens, where the pollutants' emissions occur close to the breathing zone (Sigloch et al. 2020). ...
... Previous investigations and reports have frequently utilized controlled chamber setups to measure the release of nanoparticles during 3D printing processes, as documented in prior studies (Kwon et al. 2017;Byrley et al. 2019;Gu et al. 2019). While these chamber setups have provided valuable insights, they can potentially concentrate emitted pollutants. ...
... In our recent measurements of nanoparticle emissions from ABS and PLA filaments, our findings align with those of Stephens et al. (2013), Kwon et al. (2017), and García and Pola (2022). Specifically, their studies revealed that the emission rate of nanoparticles from ABS filaments was around 10 times higher than that of PLA filaments. ...
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This study investigates nanoparticle emission during 3D printing processes, assessing various filament materials’ impact on air quality. Commonly used 3D printers, including both filament and resin-based types, were examined. The study’s scope encompasses diverse filament materials like ABS (acrylonitrile butadiene styrene), PLA (polylactic acid), PETG (polyethylene terephthalate glycol), ASA (acrylonitrile styrene acrylate), TPU (thermoplastic polyurethane), PP (polypropylene), nylon, and wood-based variants, alongside three types of resins. The research delves into the relationship between the type of material and nanoparticle emissions, emphasizing temperature’s pivotal role. Measurement instruments were employed for nanoparticle quantification, including an engine exhaust particle sizer spectrometer, condensation particle counter, and nanozen dust counters. Notably, results reveal substantial variations in nanoparticle emissions among different filament materials, with ASA, TPU, PP, and ABS showing considerably elevated emission levels and characteristic particle size distribution patterns. The findings prompt practical recommendations for reducing nanoparticle exposure, emphasizing printer confinement, material selection, and adequate ventilation. This study offers insights into potential health risks associated with 3D printing emissions and provides a basis for adopting preventive measures.
... FFF 3D printers are widely used in workplaces, residential and educational settings (Bharti and Singh, 2017), due to their low cost, flexibility, and ease of operation. Commonly used filaments are thermoplastics like acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and nylon, with various additives and composites (Bharti and Singh, 2017;Zhang et al., 2017;Kwon et al., 2017). Studies have shown that consumer FFF 3D printers emit high levels of particles, especially ultrafine particles (UFP, diameter <100 nm) (Zhang et al., 2017;Yi et al., 2016;Chýlek et al., 2021;Floyd et al., 2017;Azimi et al., 2016;Kim et al., 2015). ...
... Studies have shown that consumer FFF 3D printers emit high levels of particles, especially ultrafine particles (UFP, diameter <100 nm) (Zhang et al., 2017;Yi et al., 2016;Chýlek et al., 2021;Floyd et al., 2017;Azimi et al., 2016;Kim et al., 2015). Elemental analysis of emitted particles showed the predominant elements were carbon and oxygen (Kwon et al., 2017;Zisook et al., 2020;Steinle, 2016;Zontek et al., 2017;Zhu et al., 2020;Rao et al., 2017), which were associated with the polymer materials; other non-metal elements included sulfur and chlorine (Zisook et al., 2020;Zontek et al., 2017;Rao et al., 2017;Stefaniak et al., 2017a;Youn et al., 2019). Trace amount of metals and metalloids, refer to as metals hereafter, have also been detected; common ones included aluminum (Al), iron (Fe), zinc (Zn), chromium (Cr), copper (Cu), sodium (Na), calcium (Ca), magnesium (Mg), and manganese (Mn) (Zontek et al., 2017;Stefaniak et al., 2017a;Stefaniak et al., 2021). ...
... Metal-based additives, in the form of inorganic or organic compounds, are commonly used in plastics, functioning as inert fillers, pigments, stabilizers, antioxidants, lubricants, and flame retardants (Turner and Filella, 2021;Tedla et al., 2022). Although metal-based additives are not expected to migrate from the material matrix to the environment (Turner and Filella, 2021), thermoplastic filaments are heated to temperatures between 190 and 270 °C (Zhang et al., 2017;Kwon et al., 2017) which could lead to decomposition/ transformation of metal additives and their unintentional release. Metal powder or (nano)particles (nanoparticles (NPs) < 100 nm in size) are also added to polymer filaments to create metal composite filaments (Tedla et al., 2022), which provide printed parts with enhanced mechanical strength and metallic finish. ...
Article
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Material extrusion 3D printing has been widely used in industrial, educational and residential environments, while its exposure health impacts have not been well understood. High levels of ultrafine particles are found being emitted from 3D printing and could pose a hazard when inhaled. However, metals that potentially transfer from filament additives to emitted particles could also add to the exposure hazard, which have not been well characterized for their emissions. This study analyzed metal (and metalloid) compositions of raw filaments and in the emitted particles during printing; studied filaments included pure polymer filaments with metal additives and composite filaments with and without metal powder. Our chamber study found that crustal metals tended to have higher partitioning factors from filaments to emitted particles; silicon was the most abundant element in emitted particles and had the highest yield per filament mass. However, bronze and stainless-steel powder added in composite filaments were less likely to transfer from filament to particle. For some cases, boron, arsenic, manganese, and lead were only detected in particles, which indicated external sources, such as the printers themselves. Heavy metals with health concerns were also detected in emitted particles, while their estimated exposure concentrations in indoor air were below air quality standards and occupational regulations. However, total particle exposure concentrations estimated for indoor environments could exceed ambient air fine particulate standards.
... The specifics on the gray liquid feedstock or the brand name of the feedstock were not reported in their article. An example of some of the techniques involved in the characterization studies is in Figure 1, which shows the experimental setup of a 3D (Feygin and Hsieh 1991) printer machine with fans (Kwon et al. 2017). The figure presents the types of filaments used by Kwon et al. (2017) along with multiple control methods (enclosure, suction fan, exhaust fan, and filter media), and particle sampling methods (for particle count, concentration and size distribution). ...
... An example of some of the techniques involved in the characterization studies is in Figure 1, which shows the experimental setup of a 3D (Feygin and Hsieh 1991) printer machine with fans (Kwon et al. 2017). The figure presents the types of filaments used by Kwon et al. (2017) along with multiple control methods (enclosure, suction fan, exhaust fan, and filter media), and particle sampling methods (for particle count, concentration and size distribution). Most of these experiments were conducted in an enclosed room with a controlled environment, mimicking a home or office setting. ...
... Table 2 Figure 1. Key aspects of a typical particulate characterization study (Kwon et al. 2017). Reprinted from Kwon et al. (2017). ...
Article
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As additive manufacturing (AM) has become an evolving discipline in many industries, including manufacturing, medical, and aerospace, it becomes important to identify the risk coming from human exposure to particulates and Volatile Organic Compounds (VOCs) in AM which can lead to serious and chronic health issues. To address this issue, this article first provides a summary of previously reported particulate and VOCs characterization studies during AM processes, including equipment, environmental setups, variables studied, and instrumentation reported in the literature. We then reported a synopsis of the nature of the exposure, characteristics of the emitted particulates and VOCs, and associated health risks for different AM settings in a systematic manner. The key factors contributing to the harmful emissions include the use of toxic material compounds, high operating temperature, manual handling of hazardous materials, and limitations of the underlying printing technology among others. For that matter, we have outlined potential pathways to control hazardous exposure. Our recommendations include adopting safer operational practices, developing regulatory frameworks for facilities and equipment manufacturers, and seeking better technologies that minimize harmful emissions. Our aim is to benefit early-stage researchers, regulators, and industry practitioners in understanding and advancing knowledge of health hazards, safer practices, and technologies in AM.
... Väisänen et al. (2022) noted a LEV control for an MJ machine and 6 articles evaluated ventilation controls for ME-type FFF 3-D printers. Of these six articles, three evaluated LEV at or near to the extruder nozzle (Dunn et al. 2020;Kwon et al. 2017;Viitanen et al. 2021), one evaluated the efficacy of a room LEV system (Zontek, Scotto, and Hollenbeck 2021), one evaluated the efficacy of an air purifier equipped with different particulate and gas combination filters positioned near a printer , and one evaluated room GEV (Secondo et al. 2020). Väisänen et al. (2022) measured particles, VOCs, and carbonyls emitted from an MJ printer. ...
... The removal of individual carbonyls ranged from 35.3% (formaldehyde, black) to 75.0% (acetone and propionaldehyde, black; 2-butanone, multi). Kwon et al. (2017) studied multiple retrofit control options to reduce ultrafine particle (UFP; d < 100 nm) emissions from a ME-type FFF 3-D printer. Among the options was a suction fan (speed of 6000 revolutions per min, flow rate of 2.7 × 10 -4 m 3 /s, and face velocity of 0.2 m/s) with activated carbon filter placed horizontally in front of the extruder. ...
... The ineffectiveness was attributed to the suction fan placement only to the front rather than surrounding the extruder nozzle, which created turbulent flow around the extruder nozzle, with a low flow rate of suction. Several other control options from the study by Kwon et al. (2017) are described in the ventilated enclosure section below. In a study by Dunn et al. (2020) the detachable Smart Extruder of a MakerBot Replicator+ (MEtype FFF 3-D printer) was removed and the existing plastic cover that supplied cooling air to the extruder from three directions and replaced with a NIOSH-designed ventilated extruder head capture hood that supplied cooling air in only one direction and captured emissions in a high efficiency particulate air (HEPA) filter through an exhaust port (1.6 L/s). ...
Article
Additive manufacturing (AM) refers to several types of processes that join materials to build objects, often layer-by-layer, from a computer-aided design file. Many AM processes release potentially hazardous particles and gases during printing and associated tasks. There is limited understanding of the efficacy of controls including elimination, substitution, administrative, and personal protective technologies to reduce or remove emissions, which is an impediment to implementation of risk mitigation strategies. The Medline, Embase, Environmental Science Collection, CINAHL, Scopus, and Web of Science databases and other resources were used to identify 42 articles that met the inclusion criteria for this review. Key findings were as follows: 1) engineering controls for material extrusion-type fused filament fabrication (FFF) 3-D printers and material jetting printers that included local exhaust ventilation generally exhibited higher efficacy to decrease particle and gas levels compared with isolation alone, and 2) engineering controls for particle emissions from FFF 3-D printers displayed higher efficacy for ultrafine particles compared with fine particles and in test chambers compared with real-world settings. Critical knowledge gaps identified included a need for data: 1) on efficacy of controls for all AM process types, 2) better understanding approaches to control particles over a range of sizes and gas-phase emissions, 3) obtained using a standardized collection approach to facilitate inter-comparison of study results, 4) approaches that go beyond the inhalation exposure pathway to include controls to minimize dermal exposures, and 5) to evaluate not just the engineering tier, but also the prevention-through-design and other tiers of the hierarchy of controls.
... Their findings indicate the emissions are similar in composition when compared to those produced by material extrusion (ME) 3D printers, but this was not confirmed by using the produced filaments in a 3D printer. Principally, a thermal extruder can produce a wide range of emissions, mainly chemical species including volatile organic compounds (VOCs), ultrafine particles (UFPs), and to a smaller extent, fine (PM 2.5 ) and coarse (PM 10 ) particles (Kim et al. 2015a, Azimi et al. 2016Stabile et al. 2017;Steinle 2016;Yi et al. 2016;Floyd et al. 2017;Kwon et al. 2017;Mendes et al. 2017;Rao et al. 2017;Stefaniak et al. 2017Stefaniak et al. , 2021Vance et al. 2017;Byrley et al. 2019Byrley et al. , 2020Du Preez et al. 2018;Davis et al. 2019;V€ ais€ anen et al. 2019, 2021aJeon et al. 2020). These emissions can induce adverse health impacts in humans after exposure, including respiratory symptoms, depression of the central nervous system, irritation, inflammation or sensitization, and they may exacerbate preexisting health conditions, e.g., asthma (WHO 1995(WHO , 2006Van Kampen et al. 2000;Pope and Dockery 2006;Wolkoff et al. 2006;Mossman et al. 2007;Sarigiannis et al. 2011;Weschler 2011;Shahnaz et al. 2012;Klaasen et al. 2013;Rohr 2013;House et al. 2017;Chan et al. 2018). ...
... VOCs and particles originated from BC processing, and especially their small-scale production has not previously been investigated thoroughly from a safety perspective and the impacts of the introduction of bio-content on emission compositions are not previously discussed in the AM field. Although BC filaments have occasionally been used in ME printer emission studies as a subsidiary material (Azimi et al. 2016;Stabile et al. 2017;Kwon et al. 2017;Vance et al. 2017;V€ ais€ anen et al. 2019;Jeon et al. 2020), they have not been a central material of interest and the postulated terpene emissions have not been previously targeted. This study aims to fill in the remaining data gaps. ...
... 3D printers are identified as significant UFP emitters, but the obtained concentration levels were far below a proposed lightweight UFP exposure reference value of 4 Â 10 4 #/cm 3 given for manufactured nanomaterials (Van Broekhuizen et al. 2012), the only available reference as no authoritative OELs exist. PLA and BC feedstocks have been recorded to emit UFPs with an aerodynamic diameter of 20 nm and above mainly in 5 Â 10 2 -5 Â 10 4 #/cm 3 concentration levels when 200-220 C temperatures are used (Kim et al. 2015a;Yi et al. 2016;Azimi et al. 2016;Floyd et al. 2017;Kwon et al. 2017;Mendes et al. 2017;Vance et al. 2017;Du Preez et al. 2018;V€ ais€ anen et al. 2019, 2021aByrley et al. 2019;Jeon et al. 2020). These concentration ranges represent calculated ERs of ca. 10 8 -10 11 #/min (Kwon et al. 2017;Vance et al. 2017;Byrley et al. 2019;Jeon et al. 2020). ...
Article
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Biocomposites (BCs) can be used as substitutes for unsustainable polymers in 3D printing, but their safety demands additional investigation as biological fillers may produce altered emissions during thermal processing. Commercial filament extruders can be used to produce custom feedstocks, but they are another source for airborne contaminants and demand further research. These knowledge gaps are targeted in this study. Volatile organic compound (VOC), carbonyl compound, ultrafine particle (UFP), and fine (PM2.5) and coarse (PM10) particle air concentrations were measured in this study as a filament extruder and a 3D printer were operated under office environment using one PLA and four PLA-based BC feedstocks. Estimates of emission rates (ERs) for total VOCs (TVOC) and UFPs were also calculated. VOCs were analyzed with a GC-MS system, carbonyls were analyzed with an LC-MS/MS system, whereas real-time particle concentrations were monitored with continuously operating instruments. VOC concentrations were low throughout the experiment; TVOC ranged between 34-63 µg/m3 during filament extrusion and 41-56 µg/m3 during 3D printing, which represent calculated TVOC ERs of 2.6‒3.6 × 102 and 2.9‒3.6 × 102 µg/min. Corresponding cumulative carbonyls ranged between 60-91 and 190-253 µg/m3. Lactide and miscellaneous acids and alcohols were the dominant VOCs, while acetone, 2-butanone, and formaldehyde were the dominant carbonyls. Terpenes contributed for ca. 20-40% of TVOC during BC processing. The average UFP levels produced by the filament extruder were 0.85 × 102-1.05 × 103 #/cm3, while the 3D printer generated 6.05 × 102-2.09 × 103 #/cm3 particle levels. Corresponding particle ERs were 5.3 × 108-6.6 × 109 and 3.8 × 109-1.3 × 1010 #/min. PM2.5 and PM10 particles were produced in the following average quantities; PM2.5 levels ranged between 0.2-2.2 µg/m3, while PM10 levels were between 5-20 µg/m3 for all materials. The main difference between the pure PLA and BC feedstock emissions were terpenes, present during all BC extrusion processes. BCs are similar emission sources as pure plastics based on our findings, and a filament extruder produces contaminants at comparable or slightly lower levels in comparison to 3D printers.
... Summarizing from previous emission studies, 3,4,[6][7][8][9][10][11][12][13][14]16,17,19,22,24,25,29,30,32,34 the particle emission from FFF-3D printing mainly varies as a function of: (1) the filament type, ...
... The choice of a filament has been pointed out to influence the particle emission by up to several orders of magnitude. 3,4,[6][7][8][9][10][11][12][13][14]16,17,22,24,25,29,30,32,34 Further investigations suggested that color, 10 metal 14,16,25,34 and wood 14,16,25 additives affect the particle emission level. Seeger et al. 22 assumed that the particle emission is specific for an individual filament product rather than for its basic polymer and a ranking of emissions by the filament's basic polymer types seems not expedient. ...
... Printer equipment, e.g., fans, dust protection and built-in filters, may also have an influence on the exposure to released particles. 10,12 Relevant customizable parameters are inter alia the operating temperatures of extruder 6,7,[12][13][14]17,22,24,25,30 ...
Article
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The diversity of fused filament fabrication (FFF) filaments continues to grow rapidly as the popularity of FFF-3D desktop printers for the use as home fabrication devices has been greatly increased in the past decade. Potential harmful emissions and associated health risks when operating indoors have induced many emission studies. However, the lack of standardization of measurements impeded an objectifiable comparison of research findings. Therefore, we designed a chamber-based standard method, i.e., the strand printing method (SPM), which provides a standardized printing procedure and quantifies systematically the particle emission released from individual FFF-3D filaments under controlled conditions. Forty-four marketable filament products were tested. The total number of emitted particles (TP) varied by approximately four orders of magnitude (109 ≤ TP ≤ 1013 ), indicating that origin of polymers, manufacturer-specific additives, and undeclared impurities have a strong influence. Our results suggest that TP characterizes an individual filament product and particle emissions cannot be categorized by the polymer type (e.g., PLA or ABS) alone. The user's choice of a filament product is therefore decisive for the exposure to released particles during operation. Thus, choosing a filament product awarded for low emissions seems to be an easily achievable preemptive measure to prevent health hazards.
... 40,59,60 On the other hand, the rates of emission of PM 2.5 (particles per minute) produced from different types of printing materials are different. 43,57,61 For example, Kwon et al. showed that rates of emission of PM 2.5 from various printing materials under manufacturerrecommended and consistent-temperature conditions could be classified into high, medium, and low levels, and a difference of 3 orders of magnitude between high and low levels was obtained. This suggested that significantly different pollution can be caused by different printing materials used. ...
... This suggested that significantly different pollution can be caused by different printing materials used. 57 In spite of a number of studies of the characteristics of PM 2.5 emission from 3D printing, the limitations and research gaps remain. Only a limited number of manufacturers and models of printers and a few printing materials have been characterized for particle emissions to date. ...
... 76,77 Installing proper filters in the enclosure ventilation of the 3D printer is an effective way to reduce the levels of printer-emitted PM 2.5 and VOCs. 52,57,78 Improving the air conditioning (HVAC) system is a key solution for indoor air quality. In addition, because of the difference in potential emission sources and pollution during various 3D printing processes, targeted prevention strategies are required. ...
... In recent reports, printing with ABS filament was demonstrated to result in 3 to 4 times higher emissions than printing with PLA, which was attributed to the higher extruder temperatures applied for melting ABS filament [11,14]. Several studies have found that greater amounts of smaller particles (less than <100 nm diameter) are emitted from ABS filaments compared with PLA [20][21][22]. Other studies have investigated the effects of filament color on PM emission and major differences have been noted and attributed to the different additives and pigments used [14,23]. ...
... The sampling interval was 90 s. The OPS sensor was placed 1 m directly across from the printer nozzle head, which was in line with the ISO 16000-1 recommendation [21]. Unless otherwise specified, all PM emission A Cair sensor (NuWave, Ireland) was used as a low-cost home IAQ sensor to track PM emissions. ...
... These differences in PM emissions stem from different additives and pigments in the different colored materials. The observations here are consistent with previous studies performed in closed chamber settings [17,21,30]. For example, Stefaniak et al. [31] reported that the number-based emission rates varied by a factor of up to nine when comparing printing of black and white PLA filament materials. ...
Article
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Consumer-level 3D printers are becoming increasingly prevalent in home settings. However, research shows that printing with these desktop 3D printers can impact indoor air quality (IAQ). This study examined particulate matter (PM) emissions generated by 3D printers in an indoor domestic setting. Print filament type, brand, and color were investigated and shown to all have significant impacts on the PM emission profiles over time. For example, emission rates were observed to vary by up to 150-fold, depending on the brand of a specific filament being used. Various printer settings (e.g., fan speed, infill density, extruder temperature) were also investigated. This study identifies that high levels of PM are triggered by the filament heating process and that accessible, user-controlled print settings can be used to modulate the PM emission from the 3D printing process. Considering these findings, a low-cost home IAQ sensor was evaluated as a potential means to enable a home user to monitor PM emissions from their 3D printing activities. This sensing approach was demonstrated to detect the timepoint where the onset of PM emission from a 3D print occurs. Therefore, these low-cost sensors could serve to inform the user when PM levels in the home become elevated significantly on account of this activity and furthermore, can indicate the time at which PM levels return to baseline after the printing process and/or after adding ventilation. By deploying such sensors at home, domestic users of 3D printers can assess the impact of filament type, color, and brand that they utilize on PM emissions, as well as be informed of how their selected print settings can impact their PM exposure levels.
... Recently, three-dimensional (3D) printing has become an emerging and booming industry in Taiwan. Unlike traditional manufacturing, 3D printing has many advantages, such as reducing material costs, simplifying the production process, customizing small-scale production, reducing material use, and improving efficiency (Kwon et al. 2017). According to the American Society for Testing and Materials (ASTM), 3D printing is a material bonding process. ...
... Commonly used filaments for 3D printing include polymers (thermoplastic), such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polyethylene terephthalate glycol, with different composites and additives (Zhang et al. 2023). Previous research has shown that a printer using ABS filaments has a much higher PM emission rate than a printer using polylactic acid (PLA) feedstock, particularly ultrafine particles (UFPs) with an aerodynamic diameter less than 100 nm (Stephens et al. 2013;Azimi et al. 2016;Kwon et al. 2017;Zhang et al. 2019). ...
... In practice, the extrusion temperature is above the melting point or the glass transition temperature for crystalline or amorphous polymers, respectively. Thus, thermal degradation and formation of ultrafine particles (UFP; particle diameter of 100 nm or less) occur which are generally released indoors during a 3D printing process (Stephens et al., 2013;Kim et al., 2015;Deng et al., 2016;Yi et al., 2016;Azimi et al., 2016;McDonnell et al., 2016;Steinle, 2016;Mendes et al., 2017;Floyd et al., 2017;Kwon et al., 2017;Stabile et al., 2017;Vance et al., 2017;Zhang et al., 2017;Seeger et al., 2018;Gu et al., 2019;Poikkimäki et al., 2019;Beisser et al., 2020;Jeon et al., 2020;Katz et al., 2020;Secondo et al., 2020;Dunn et al., 2020;Sittichompoo et al., 2020;Alberts et al., 2021;Viitanen et al., 2021;Dobrzyńska et al., 2021;Chýlek et al., 2021;Bernatikova et al., 2021;Stefaniak et al., 2021;Manoj et al., 2021;Tang and Seeger, 2022;Romanowski et al., 2022;Saliakas et al., 2022). These findings raised the awareness, as UFP exposure has been reported to increase the risk of adverse health effects (Oberdörster et al., 1995(Oberdörster et al., , 2004(Oberdörster et al., , 2005Hong and Jee, 2020;Schraufnagel, 2020). ...
... Studies have shown that overheating of the feedstock is one of the main emission factors as degradation of thermoplastics is temperature driven. Increasing the extruder temperature for a given filament generally enhances the particle emission as stated in many studies (Azimi et al., 2016;Deng et al., 2016;Mendes et al., 2017;Kwon et al., 2017;Stabile et al., 2017;Zhang et al., 2017;Seeger et al., 2018;Gu et al., 2019;Jeon et al., 2020;Poikkimäki et al., 2019;Tang and Seeger, 2022). Our previously published results suggest that even a temperature increase by only 5 • C elevates the particle emission level (Tang and Seeger, 2022), hence the temperature setting is a crucial parameter for the investigation and intercomparison of emission data. ...
Article
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Fused filament fabrication (FFF) is a material extrusion-based technique often used in desktop 3D printers. Polymeric filaments are melted and are extruded through a heated nozzle to form a 3D object in layers. The extruder temperature is therefore a key parameter for a successful print job but also one of the main emission driving factors as harmful pollutants (e.g., ultrafine particles) are formed by thermal polymer degradation. The awareness of potential health risks has increased the number of emission studies in the past years. However, studies usually refer their calculated emission data to the printer set extruder temperature for comparison purposes. In this study, we used a thermocouple and an infrared camera to measure the actual extruder temperature and found significant temperature deviations to the displayed set temperature among printer models. Our result shows that printing the same filament feedstocks with three different printer models and with identical printer set temperature resulted in a variation in particle emission of around two orders of magnitude. A temperature adjustment has reduced the variation to approx. one order of magnitude. Thus, it is necessary to refer the measured emission data to the actual extruder temperature as it poses a more accurate comparison parameter for evaluation of the indoor air quality in user scenarios or for health risk assessments.
... Their relatively low price (from around 140 euros) means that they are present in many companies, homes and even nursery schools; with them, it is possible to produce prototypes of unique designs at a meagre cost; in addition, there are already models of games, figures or pieces that can be download for free from the Internet and print them with 3D printers. However, they are not all advantages; with 3D printing, a series of emerging risks are associated, such as exposure to nanoparticles and volatile organic compounds (VOCs) [1][2][3]. The most investigated materials are poly lactic acid (PLA) and acrylonitrile butadiene styrene (ABS) since they were the most used; however, many compounds and other printing technologies are entering the market strongly, such as 3D resin printers. ...
... In the same way, Kwon et al. [1] detailed a maximum concentration of 54,000 nanoparticles/cm 3 in ABS and 1326 nanoparticles/cm 3 in PLA filament printing at the temperature recommended by the manufacturer, increasing the emission of nanoparticles at higher temperatures, very similar results than García-González and Lopez-Pola [7]. ...
Chapter
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Nowadays, it is possible to find 3D printers everywhere, at homes, schools, work offices, etcetera. 3D printing is an additive manufacturing process that is increasingly gaining popularity, and it can create functional parts with a wide variety of shapes and sizes. But on the other hand, there are health risks associated with 3D printers, like nanoparticles and volatile organic compounds (VOCs), which are important to know to improve health and safety and avoid diseases such as asthma, allergic rhinitis and chronic obstructive pulmonary disease, among others. This chapter analyses techniques for sampling the nanoparticles and VOCs exposure during 3D printing and a health effects review, giving tools to evaluate the risks and recommendations to avoid or minimise these risks using engineering controls like extraction systems or good ventilation.
... 18 A few studies reporting protective measures to control the emissions of 3D printers in controlled chamber conditions have been published. 19, 20 Gu et al. studied commercial filter cover equipped with a fan connected to HEPA and an active carbon filters and air purifier with two different types of filters. The filter cover reduced the particle number concentration 93% and the air purifier 74%-90%. ...
... When less efficient particle filters were in use, the removal effectiveness varied between 76% and 96%, and the removal effectiveness for enclosure without a ventilation was reported to be 74%. 19 Stefaniak et al. evaluated a custom-built ventilated enclosure at industrial 3D printing facility and found 99.7% reduction in particle number concentration. 27 In addition, Azimi et al. modeled the 95% removal efficiencies of an enclosure with gas and particle filtration. ...
Article
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Material extrusion (ME) desktop 3D printing is known to strongly emit nanoparticles (NP), and the need for risk management has been recognized widely. Four different engineering control measures were studied in real-life office conditions by means of online NP measurements and indoor aerosol modeling. The studied engineering control measures were general ventilation, local exhaust ventilation (LEV), retrofitted enclosure, and retrofitted enclosure with LEV. Efficiency between different control measures was compared based on particle number and surface area (SA) concentrations from which SA concentration was found to be more reliable. The study found out that for regular or long-time use of ME desktop 3D printers, the general ventilation is not sufficient control measure for NP emissions. Also, the LEV with canopy hood attached above the 3D printer did not control the emission remarkably and successful position of the hood in relation to the nozzle was found challenging. Retrofitted enclosure attached to the LEV reduced the NP emissions 96% based on SA concentration. Retrofitted enclosure is nearly as efficient as enclosure attached to the LEV (reduction of 89% based on SA concentration) but may be considered more practical solution than enclosure with LEV.
... It has been reported that emissions from FFF-3D printing could induce toxicological effects and are potentially harmful (Farcas et al. 2022;Farcas et al. 2019;Stefaniak et al. 2017;Zhang et al. 2019). Previous studies have shown that mainly ultrafine particles (UFP, d P � 100 nm) are released during printing activities (Alberts et al. 2021;Azimi et al. 2016;Beisser et al. 2020;Bernatikova et al. 2021;Ch� ylek et al. 2021;Deng et al. 2016;Dobrzy� nska et al. 2021;Dunn et al. 2020;Floyd, Wang, and Regens 2017;Gu et al. 2019;Jeon et al. 2020;Katz et al. 2020;Kim et al. 2015;Kwon et al. 2017;Manoj et al. 2021;McDonnell et al. 2016;Mendes et al. 2017;Poikkim€ aki et al. 2019;Romanowski et al. 2022;Saliakas et al. 2022;Secondo et al. 2020;Seeger et al. 2018;Sittichompoo et al. 2020;Stabile et al. 2017;Stefaniak et al. 2021;Steinle 2016;Stephens et al. 2013;Tang and Seeger 2022;Tang, Seeger, and R€ ollig 2023;Vance et al. 2017;Viitanen et al. 2021;Yi et al. 2016;Zhang et al. 2017). Ultrafine particles can cause more severe inflammation and oxidative stress compared to larger particles due to greater reactive surface area per given mass (Duffin et al. 2007;Farcas et al. 2019;Oberd€ orster 2000). ...
Article
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The emission of ultrafine particles from small desktop Fused Filament Fabrication (FFF) 3D printers has been frequently investigated in the past years. However, the vast majority of FFF emission and exposure studies have not considered the possible occurrence of particles below the typical detection limit of Condensation Particle Counters and could have systematically underestimated the total particle emission as well as the related exposure risks. Therefore, we comparatively measured particle number concentrations and size distributions of sub-4 nm particles with two commercially available diethylene glycol-based instruments – the TSI 3757 Nano Enhancer and the Airmodus A10 Particle Size Magnifier. Both instruments were evaluated for their suitability of measuring FFF-3D printing emissions in the sub-4 nm size range while operated as a particle counter or as a particle size spectrometer. For particle counting, both instruments match best when the Airmodus system was adjusted to a cut-off of 1.5 nm. For size spectroscopy, both instruments show limitations due to either the fast dynamics or rather low levels of particle emissions from FFF-3D printing in this range. The effects are discussed in detail in this article. The findings could be used to implement sub-4 nm particle measurement in future emission or exposure studies, but also for the development of standard test protocols for FFF-3D printing emissions.
... The utilization of low processing temperatures and low-emitting materials as well as establishing control measures, such as employing an enclosure surrounding the printer in conjunction with an appropriate filter, are ways to reduce polluting emissions during 3D printing [118]. ...
Article
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The fused deposition modeling (FDM) process, an extrusion-based 3D printing technology, enables the manufacture of complex geometrical elements. This technology employs diverse materials, including thermoplastic polymers and composites as well as recycled resins to encourage sustainable growth. FDM is used in a variety of industrial fields, including automotive, biomedical, and textiles, as a rapid prototyping method to reduce costs and shorten production time, or to develop items with detailed designs and high precision. The main phases of this technology include the feeding of solid filament into a molten chamber, capillary flow of a non-Newtonian fluid through a nozzle, layer deposition on the support base, and layer-to-layer adhesion. The viscoelastic properties of processed materials are essential in each of the FDM steps: (i) predicting the printability of the melted material during FDM extrusion and ensuring a continuous flow across the nozzle; (ii) controlling the deposition process of the molten filament on the print bed and avoiding fast material leakage and loss of precision in the molded part; and (iii) ensuring layer adhesion in the subsequent consolidation phase. Regarding this framework, this work aimed to collect knowledge on FDM extrusion and on different types of rheological properties in order to forecast the performance of thermoplastics.
... The above studies used systems that simulated the contamination of nanoparticles in an airflow. Other studies evaluated the collection of real emissions, such as emissions during 3D printing [211], waste incinerators [212], chassis dynamometers and on a road [213], heavy-duty diesel engines operating with fuels with sulfur levels relevant to marine operation [214], and hygroscopic aerosols emitted from e-cigarette and heated tobacco products [215][216][217][218][219][220]. Emissions of biological materials, such as viruses and bacteria, are also the focus of several studies that verified the efficiency of filter media used in personal protective equipment [221][222][223][224]. Numerical research was carried out in several studies, but the focus on the development of models and theoretical investigations occurred only in some studies [225][226][227][228][229]. Several authors have developed and suggested methodologies for filtration tests involving the collection of nanoparticles [230][231][232][233]. Table 2 summarizes several works related to the study of filters for collecting nanoparticles. ...
Article
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The growing increase in emissions of ultrafine particles or nanoparticles by industries and urban centers has become worrisome due to the potential adverse health effects when inhaled. Particles in this size range have greater ease of pulmonary penetration, being able to access the bloodstream and deposit in other regions of the body. Thus, the development and optimization of equipment and processes aimed at the removal of aerosols of nanoparticles have been gaining importance in this current scenario. Among the equipment commonly used, electrostatic precipitators and filters stand out as being versatile and consolidated processes in the literature. This review explores and analyzes the theoretical bases of these two processes in the collection of such small particles in addition to providing a general overview of the development of technologies and studies on these topics.
... Recent research has indicated a need for greater understanding the chemical composition of 3D printing aerosol emissions and their health hazards [17][18][19][20][21][22][23][24][25][26][27]. Steinle [16] measured the ultrafine aerosols (UFAs) and volatile organic compounds (VOCs) from printing with ABS and PLA filaments in two different workplace environments and found that the emissions corresponded primarily to volatile droplets, which were found as amorphous particles collected on TEM grids. ...
Article
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Fused filament fabrication is a 3D printing technique that has gained widespread use from homes to schools to workplaces. Thermoplastic filaments, such as acrylonitrile–butadiene–styrene (ABS) and polylactic acid (PLA), are extruded at temperatures near their respective glass transition temperature or melting point, respectively. Little has been reported on the inorganic elemental composition and concentrations present in these materials or the methods available for extracting that information. Because inorganic constituents may be included in the aerosolized particulates emitted during the printing process, identifying elements that could be present and at what specific concentrations is critical. The objective of the current research is to determine the range of metals present in thermoplastic filaments along with their relative abundance and chemical speciation as a function of polymer type, manufacturer, and color. A variety of filaments from select manufacturers were digested using a range of techniques to determine the optimal conditions for metal extraction from ABS and PLA polymers. The extraction potential for each method was quantified using by ICP-MS analysis. When possible, further characterization of the chemical composition of the filaments was investigated using X-ray Absorption spectroscopy to determine chemical speciation of the metal. Optimal digestion conditions were established using a high temperature, high pressure microwave-assisted acid digestion method to produce the most complete and repeatable extraction results. The composition and abundance of metals in the filaments varied greatly as a function of polymer, manufacturer, and color. Potential elements of concern present in the filaments at elevated concentration included that could pose a respiratory risk included Si, Al, Ti, Cu, Zn, and Sn. XAS analysis revealed a mixture of metal oxides, mineral, and organometallic compounds were present in the filaments that were being used to increase opaqueness impart color (dyes), polymeric catalysts, and flame retardants. This work shows that a variety of metals are present in the starting materials used for 3D printing and depending on their partitioning into 3D printed products and byproducts as well as the exposure route, may pose a health risk which merits further investigation.
... Another safety hazard that additive manufacturing has is the harmful emissions that are produced in the 3D printing process. Research has been done regarding reducing emissions in the additive manufacturing process, and one tactic that has been found to reduce the emissions is to use a high-efficiency filter in an enclosed, well-ventilated indoor environment that could help alleviate this safety concern (Kwon et al., 2017). ...
... Another safety hazard that additive manufacturing has is the harmful emissions that are produced in the 3D printing process. Research has been done regarding reducing emissions in the additive manufacturing process, and one tactic that has been found to reduce the emissions is to use a high-efficiency filter in an enclosed, well-ventilated indoor environment that could help alleviate this safety concern (Kwon et al., 2017). ...
... An accelerating expansion and evolution of fused filament fabrication (FFF), a three-dimensional (3-D) printing process, is occurring across industries. Considerable evidence [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] shows that the FFF 3-D printing process releases a significant number of nanoparticles (NPs; diameter <100 nm) that can deposit deep in the lower respiratory tract and may cause adverse respiratory effects. The FFF 3-D printing process also releases various volatile organic compounds (VOCs) during printing, which might pose serious risk concerns to human health as they are known irritants, carcinogens, odorants, and reprotoxins. ...
Article
This study investigated the inhalation toxicity of the emissions from 3-D printing with acrylonitrile butadiene styrene (ABS) filament using an air-liquid interface (ALI) in vitro model. Primary normal human-derived bronchial epithelial cells (NHBEs) were exposed to ABS filament emissions in an ALI for 4 hours. The mean and mode diameters of ABS emitted particles in the medium were 175 ± 24 and 153 ± 15 nm, respectively. The average particle deposition per surface area of the epithelium was 2.29 × 10 ⁷ ± 1.47 × 10 ⁷ particle/cm ² , equivalent to an estimated average particle mass of 0.144 ± 0.042 μg/cm ² . Results showed exposure of NHBEs to ABS emissions did not significantly affect epithelium integrity, ciliation, mucus production, nor induce cytotoxicity. At 24 hours after the exposure, significant increases in the pro-inflammatory markers IL-12p70, IL-13, IL-15, IFN-γ, TNF-α, IL-17A, VEGF, MCP-1, and MIP-1α were noted in the basolateral cell culture medium of ABS-exposed cells compared to non-exposed chamber control cells. Results obtained from this study correspond with those from our previous in vivo studies, indicating that the increase in inflammatory mediators occur without associated membrane damage. The combination of the exposure chamber and the ALI-based model is promising for assessing 3-D printer emission-induced toxicity.
... For ME it has been established that printing emissions vary with many factors, which can affect comparisons of research results. These include printing temperatures, filament material, infill, colour of filament, filament brand, printer brand, printing rate, and printing time (Stephens et al., 2013;Kim et al., 2015;Azimi et al., 2016;Deng et al., 2016;Steinle, 2016;Yi et al., 2016;Floyd et al., 2017;Kwon et al., 2017;Mendes et al., 2017;Stabile et al., 2017;Stefaniak et al., 2017bStefaniak et al., , 2018Vance et al., 2017;Wojtyła et al., 2017;Zhang et al., 2017;Zontek et al., 2017;Cheng et al., 2018;Du Preez, 2018;Seeger et al., 2018;Davis et al., 2019;Gu et al., 2019;Potter et al., 2019;Zhang et al., 2019;Jeon et al., 2020;Park et al., 2020). Moreover, post-processing during ME in the form of heating metal up to insert in the printed object was a considerable source for exposure to small particles. ...
Article
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3D printing, a type of additive manufacturing (AM), is a rapidly expanding field. Some adverse health effects have been associated with exposure to printing emissions, which makes occupational exposure studies important. There is a lack of exposure studies, particularly from printing methods other than material extrusion (ME). The presented study aimed to evaluate measurement methods for exposure assessment in AM environments and to measure exposure and emissions from four different printing methods [powder bed fusion (PBF), material extrusion (ME), material jetting (MJ), and vat photopolymerization] in industry. Structured exposure diaries and volatile organic compound (VOC) sensors were used over a 5-day working week. Personal and stationary VOC samples and real-time particle measurements were taken for 1 day per facility. Personal inhalable and respirable dust samples were taken during PBF and MJ AM. The use of structured exposure diaries in combination with measurement data revealed that comparatively little time is spent on actual printing and the main exposure comes from post-processing tasks. VOC and particle instruments that log for a longer period are a useful tool as they facilitate the identification of work tasks with high emissions, highlight the importance of ventilation and give a more gathered view of variations in exposure. No alarming levels of VOCs or dust were detected during print nor post-processing in these facilities as adequate preventive measures were installed. As there are a few studies reporting negative health effects, it is still important to keep the exposure as low as reasonable.
... (Table 2), which were higher than the values of 10 8 −10 11 no./min reported in the literature. 10,18,22,42 The TVOC ER for HIPS calculated in the current study was 0.34−3.44 mg/min (Table 2), which was higher than the values of 0.015−0.047 ...
Article
Material extrusion-type fused filament fabrication (FFF) 3-D printing is a valuable tool for education. During FFF 3-D printing, thermal degradation of the polymer releases small particles and chemicals, many of which are hazardous to human health. In this study, particle and chemical emissions from 10 different filaments made from virgin (never printed) and recycled polymers were used to print the same object at the polymer manufacturer’s recommended nozzle temperature (“normal”) and at a temperature higher than recommended (“hot”) to simulate the real-world scenarios of a person intentionally or unknowingly printing on a machine with a changed setting. Emissions were evaluated in a college teaching laboratory using standard sampling and analytical methods. From mobility sizer measurements, particle number-based emission rates were 81 times higher; the proportion of ultrafine particles (diameter <100 nm) were 4% higher, and median particle sizes were a factor of 2 smaller for hot-temperature prints compared with normal-temperature prints (all p-values <0.05). There was no difference in emission characteristics between recycled and virgin acrylonitrile butadiene styrene and polylactic acid polymer filaments. Reducing contaminant release from FFF 3-D printers in educational settings can be achieved using the hierarchy of controls: (1) elimination/substitution (e.g., training students on principles of prevention-through-design, limiting the use of higher emitting polymer when possible); (2) engineering controls (e.g., using local exhaust ventilation to directly remove contaminants at the printer or isolating the printer from students); (3) administrative controls such as password protecting printer settings and establishing and enforcing adherence to a standard operating procedure based on a proper risk assessment for the setup and use (e.g., limiting the use of temperatures higher than those specified for the filaments used); and (4) maintenance of printers.
... Lower infill height and higher infill density resulted in fewer particle emissions (Cheng et al. 2018). Kwon et al. (2017) suggested that FFF 3D printing at a low temperature with a low-emitting filament and ventilation control can reduce particle emissions. ...
Article
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The application of Fused Filament Fabrication (FFF) 3D printing for offices, educational institutions, and small prototyping businesses has recently attracted increased attention. Thermal-fused filaments could emit potentially hazardous atmospheric particulate matter (PM) and volatile organic compounds (VOCs). This study evaluated the particle and VOCs emission characteristics of an FFF 3D printer with lignocellulose/polylactic acid (PLA) filament to reduce emissions. The PM2.5, PM0.2-10, and VOCs emission behaviors of the FFF 3D printer with a lignocellulose/PLA filament were investigated in a test chamber under different printing conditions. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was applied to analyze the formation of VOCs from lignocellulose/PLA filaments. Analysis indicated that particle formation dominated the heating process, whereas VOCs were mainly released during the printing process. The results further showed that printing at higher relative humidity and high filament feeding temperatures triggered higher VOCs emissions. In addition, high humidity facilitated particle agglomeration and reduced PM concentration. Printing at higher filament feeding temperatures also resulted in high particle emissions. Finally, Py-GC/MS analysis determined the decomposition products of the lignocellulose/PLA filament corresponding to the main ingredients of VOCs.
... The most common hazard associated was inhalation exposure, followed by dermal exposure [16,24]. The studies also showed that control measures as enclosures with air extraction reduce effectively the emissions [16,18,25,26,27]. To the best of our knowledge, we have not found a systematic research studying the emissions and exposures of 3D printers, combining printing and plasma stages, and using PEOT/PBT doped with nanofillers. ...
Article
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The EU-project FAST (GA 685825) has developed a 3D printer machine prototype for the manufacture of bone implants (scaffolds), by merging masterbatches of biodegradable polymer poly(ethylene oxide)terephthalate/poly(butylene terephthalate) [PEOT/PBT] doped with nanofillers [reduced graphene oxide (rGO), hydroxyapatite (HA) and magnesium aluminium hydroxide ciprofloxacin hydrotalcite (LDH-CFX)], and atmospheric plasma technology. This paper focus on the safe design strategies identified by FAST to address the risk to health resulting from the potential airborne emission of nano-objects and their aggregates and agglomerates (NOAAs) by the 3D printer prototype, which might result in occupational exposures by inhalation. The work also includes measurements of airborne emissions and occupational exposures carried out during the verification stage of the prototype design. Nanofillers particles (rGO, n-HA, LDH-CFX) were not observed, neither at source nor in the working area, suggesting no release of free nanofillers to the air one they have been embedded in the polymer masterbatch. Additionally, the exposure in the workplace was far below the selected Occupational Exposure Levels (OELs), for total particle number concentration (PNC), dust, elemental carbon (EC) and volatile organic compounds (VOCs). The results showed that, when working with the current prototype in normal operation (for its intended use) and with controls enabled [enclosure with the doors closed and Local Exhaust Ventilation (LEV) activated], the emission from the machine and the worker’s exposure to NOAAs are well controlled.
... The pre-and post-processing stages of MEX printing were 104 unlikely to contribute to emissions due to the use of solid filaments. In order to assess the 105 effectiveness of an enclosure during printing (Kwon et al., 2017), emissions from an 106 industrial-grade MEX printer (Fortus 450mc) in the 3D printing laboratory was also 107 examined, as shown in Figure 1(b). 108 For PBF, both polymer and metal powder-based printers were investigated. ...
Article
Purpose This study aims to examine on-site particle concentration levels due to emissions from a wide spectrum of additive manufacturing techniques, including polymer-based material extrusion, metal and polymer-based powder bed fusion, directed energy deposition and ink-based material jetting. Design/methodology/approach Particle concentrations in the operating environments of users were measured using a combination of particle sizers including the TSI 3910 Nano SMPS (10–420 nm) and the TSI 3330 optical particle sizer (0.3–10 µm). Also, fumes from a MEX printer during printing were directly captured using laser imaging method. Findings The number and mass concentration of submicron particles emitted from a desktop open-type MEX printer for acrylonitrile-butadiene-styrene and polyvinyl alcohol approached and significantly exceeded the nanoparticle reference limits, respectively. Through laser imaging, fumes were observed to originate from the printer nozzle and from newly deposited layers of the desktop MEX printer. On the other hand, caution should be taken in the pre-processing of metal and polymer powder. Specifically, one to ten micrometers of particles were observed during the sieving, loading and cleaning of powder, with transient mass concentrations ranging between 150 and 9,000 µg/m ³ that significantly exceeded the threshold level suggested for indoor air quality. Originality/value Preliminary investigation into possible exposures to particle emissions from different 3D printing processes was done, which is useful for the sustainable development of the 3D printing industry. In addition, automatic processes that enable “closed powder cycle” or “powder free handling” should be adopted to prevent users from unnecessary particle exposure.
... More stringent adherence to the manufacturer's recommendations can result in a reduction in airborne particle counts; the nanoparticle emission factor is at least one order of magnitude higher for all fibers tested at a higher constant extruder temperature than at the lower temperature recommended by the manufacturer [43]. Long-term use of the printer also led to higher emission factors (factor 2 with PLA and factor 4 with ABS (Acrylonitrile butadiene styrene), measured after seven months of sporadic use) [44]. ...
Article
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Technological and material issues in 3D printing technologies should take into account sustainable development, use of materials, energy, emitted particles, and waste. The aim of this paper is to investigate whether the sustainability of 3D printing processes can be supported by computational intelligence (CI) and artificial intelligence (AI) based solutions. We present a new AI-based software to evaluate the amount of pollution generated by 3D printing systems. We input the values: printing technology, material, print weight, etc., and the expected results (risk assessment) and determine if and what precautions should be taken. The study uses a self-learning program that will improve as more data are entered. This program does not replace but complements previously used 3D printing metrics and software.
... Emissions from filaments used in fused filament fabrication (FFF), the most common form of 3D printing, can be organized into two distinct categories: aerosolized particulate matter (PM) and gas-phase compounds. PM from 3D printers has been detected across a wide range of sizes (Stephens et al., 2013;Azimi et al., 2016;Steinle 2016;Stabile et al., 2017;Vance et al., 2017;Zhang et al., 2019), including nano-sized emissions (less than 100 nm) (Kim et al., 2015;Deng et al., 2016;Kwon et al., 2017;Zhang et al., 2017). PM poses a health risk based on both its size and ability to adsorb organic compounds. ...
Article
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A collection of six commercially available, 3D printer filaments were analyzed with respect to their gas-phase emissions, specifically volatile organic compounds (VOCs), during simulated fused filament fabrication (FFF). Filaments were chosen because they were advertised to contain metal particles or carbon nanotubes. During experimentation, some were found to contain other non-advertised additives that greatly influenced gas-phase emissions. Three polylactic acid (PLA) filaments containing either copper, bronze, or stainless steel particles were studied along in addition to three carbon nanotube (CNT) filaments made from PLA, acrylonitrile-butadiene-styrene (ABS), and polycarbonate (PC). The metal-additive PLA filaments were found to emit primarily lactide, acetaldehyde, and 1-chlorododecane. The presence of metal particles in the PLA is a possible cause of the increased total emissions, which were higher than any other PLA filament reported in the literature. In addition, the filament with stainless steel particles had a threefold increase in total VOCs compared to the copper and bronze particles. Two of three CNT-containing filaments emitted compounds that have not been reported before for PLA and PC. A comparison between certain emitted VOCs and their suggested maximum inhalation limits shows that printing as little as 20 g of certain filaments in a small, unventilated room can subject the user to hazardous concentrations of multiple toxic VOCs with carcinogenic properties (e.g., acetaldehyde, 1,4-dioxane, and bis(2-ethylhexyl) phthalate). The use of certain additives, whether advertised or not, should be reevaluated due to their effects on VOC emissions during 3D printing.
... Box plots of particle number (a) emission rates and (b) yields by scale of machine for desktop-scale FFF 3-D printers (3DP),[6][7][8][9][10][11][12][13][14][15][17][18][19]33 industrial-scale FFF machines (IS),3 and LFAM machines (current study). A label without a box plot indicates that no data are available. ...
Article
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The literature on emissions during material extrusion additive manufacturing with 3-D printers is expanding; however, there is a paucity of data for large-format additive manufacturing (LFAM) machines that can extrude high-melt-temperature polymers. Emissions from two LFAM machines were monitored during extrusion of six polymers: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), high-melt-temperature polysulfone (PSU), poly(ether sulfone) (PESU), polyphenylene sulfide (PPS), and Ultem (poly(ether imide)). Particle number, total volatile organic compound (TVOC), carbon monoxide (CO), and carbon dioxide (CO2) concentrations were monitored in real-time. Particle emission rate values (no./min) were as follows: ABS (1.7 × 10¹¹ to 7.7 × 10¹³), PC (5.2 × 10¹¹ to 3.6 × 10¹³), Ultem (5.7 × 10¹² to 3.1 × 10¹³), PPS (4.6 × 10¹¹ to 6.2 × 10¹²), PSU (1.5 × 10¹² to 3.4 × 10¹³), and PESU (2.0 to 5.0 × 10¹³). For print jobs where the mass of extruded polymer was known, particle yield values (g–1 extruded) were as follows: ABS (4.5 × 10⁸ to 2.9 × 10¹¹), PC (1.0 × 10⁹ to 1.7 × 10¹¹), PSU (5.1 × 10⁹ to 1.2 × 10¹¹), and PESU (0.8 × 10¹¹ to 1.7 × 10¹¹). TVOC emission yields ranged from 0.005 mg/g extruded (PESU) to 0.7 mg/g extruded (ABS). The use of wall-mounted exhaust ventilation fans was insufficient to completely remove airborne particulate and TVOC from the print room. Real-time CO monitoring was not a useful marker of particulate and TVOC emission profiles for Ultem, PPS, or PSU. Average CO2 and particle concentrations were moderately correlated (rs = 0.76) for PC polymer. Extrusion of ABS, PC, and four high-melt-temperature polymers by LFAM machines released particulate and TVOC at levels that could warrant consideration of engineering controls. LFAM particle emission yields for some polymers were similar to those of common desktop-scale 3-D printers.
... Unfortunately, some researchers also identified rarer, but occurring, spindleshaped particles. That shape of the particles additionally facilitates the penetration of mucous membranes and blood vessels, which translates into an increase in the penetration of certain substances into the body [29,30]. The humidity of both the material and the air at the place of manufacture is not without significance for the process. ...
Article
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Additive manufacturing in recent years has become one of the fastest growing technologies.The increasing availability of 3D printing devices means that every year more and moredevices of this type are found in the homes of ordinary people. Unfortunately, air pollution isformed during the process. Their main types include Ultra Fine Particles (UFP) and VolatileCompounds (VOC). In the event of air flow restriction, these substances can accumulate inthe room and then enter the organisms of people staying there. The article presents themain substances that have been identified in various studies available in literature. Healthaspects and potential threats related to inhalation of substances contained in dusts and gasesgenerated during the process are shown, taking into account the division into individual typesof printing materials. The article also presents the differences between the research resultsfor 3d printing from individual plastics among different authors and describes possible causesof discrepancies.
... These emerging use cases have the potential to place 3D printers and their operators in small, poorly ventilated rooms where proper use of personal protective equipment (PPE) may not be emphasized and safety requirements may be difficult to enforce Larson and Liverman 2011;MakersEmpire 2020). In addition, cohorts of new users may not be informed of the potential adverse health risks resulting from exposure to fused filament fabrication (FFF) 3D printer emissions which may contain particulate matter (PM) in concentrations exceeding 300,000 particles/cm 3 (Byrley et al. 2019;Kwon et al. 2017;Mendes et al. 2017;Stefaniak et al. 2019;Stephens et al. 2013;Wojityla, Klama, and Bara 2017;Zhou et al. 2015), even when common polymer filaments, such as acrylonitrile butadiene styrene (ABS) are used without additives such as dyes or fillers. Consumers have limited awareness of the exposure potential presented by consumer-grade 3D printers, many of which lack controls to prevent exposures to ultrafine particles (UFPs), i.e., those with diameters <100 nm, sometimes called PM 0.1 or aerosolized nanoparticles (NP). ...
Article
Fused filament fabrication (FFF) 3D printers are increasingly used in industrial, academic, military, and residential sectors, yet their emissions and associated user exposure scenarios are not fully described. Characterization of potential user exposure and environmental releases requires robust investigation. During operation, common FFF 3D printers emit varying amounts of ultrafine particles (UFPs) depending upon feedstock material and operation procedures. Volatile organic compounds associated with these emissions exhibit distinct odors; however, the UFP portion is largely imperceptible by humans. This investigation presents straightforward computational modeling as well as experimental validation to provide actionable insights for the proactive design of lower exposure spaces where 3D printers may be used. Specifically, data suggest that forced clean airflows may create lower exposure spaces, and that computational modeling might be employed to predict these spaces with reasonable accuracy to assist with room design. The configuration and positioning of room air ventilation diffusers may be a key factor in identifying lower exposure spaces. A workflow of measuring emissions during a printing process in an ANSI/CAN/UL 2904 environmental chamber was used to provide data for computational fluid dynamics (CFD) modeling of a 6 m2 room. Measurements of the particle concentrations in a Class 1000 clean room of identical geometry were found to pass the Hanna test for agreement between model and experimental data, validating the findings.
... The particle analyzer simply counts the frequency of detected nanoparticles; it does not distinguish between nanoparticles resulting from the generated aerosol and residual nanoparticles resulting from stray particulates shed from the shell. FFF processes generate aerosol emissions mainly occurring during the initial heating of the nozzle but also through the duration of the printing [40][41][42][43]. These particles, as well as loose residual powder from PBF respirators, could potentially adhere to the respirator shells and shed during testing. ...
Article
The COVID-19 pandemic has disrupted the supply chain for personal protective equipment (PPE) for medical professionals, including N95-type respiratory protective masks. To address this shortage, many have looked to the agility and accessibility of additive manufacturing (AM) systems to provide a democratized, decentralized solution to producing respirators with equivalent protection for last-resort measures. However, there are concerns about the viability and safety in deploying this localized download, print, and wear strategy due to a lack of commensurate quality assurance processes. Many open-source respirator designs for AM indicate that they do not provide N95-equivalent protection (filtering 95% of SARS-CoV-2 particles) because they have either not passed aerosol generation tests or not been tested. Few studies have quantified particle transmission through respirator designs outside of the filter medium. This is concerning because several polymer-based AM processes produce porous parts, and inherent process variation between printers and materials also threaten the integrity of tolerances and seals within the printed respirator assembly. No study has isolated these failure mechanisms specifically for respirators. The goal of this paper is to measure particle transmission through printed respirators of different designs, materials, and AM processes. The authors compare the performance of printed respirators to N95 respirators and cloth masks. Respirators in this study printed using desktop- and industrial-scale fused filament fabrication processes and industrial-scale powder bed fusion processes were not sufficiently reliable for widespread distribution and local production of N95-type respiratory protection. Even while assuming a perfect seal between the respirator and the user’s face, although a few respirators provided >90% efficiency at the 100−300 nm particle range, almost all printed respirators provided <60% filtration efficiency. Post-processing procedures including cleaning, sealing surfaces, and reinforcing the filter cap seal generally improved performance, but the printed respirators showed similar performance to various cloth masks. The authors further explore the process-driven aspects leading to low filtration efficiency. Although the design/printer/material combination dictates the AM respirator performance, the identified failure modes originate from system-level constraints and are therefore generalizable across multiple AM processes. Quantifying the limitations of AM in producing N95-type respiratory protective masks advances understanding of AM systems toward the development of better part and machine designs to meet the needs of reliable, functional, end-use parts.
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We estimated the inhaled and deposited dose in humans using the International Commission on Radiological Protection (ICRP) and multiple-path particle dosimetry (MPPD) models following exposure to humidifier disinfectant containing polyhexamethylene guanidine (PHMG). The disinfectant has caused at least 1,810 deaths, with an odds ratio of lung injury of 47.3 (95% confidence interval: 6.1–369.7), because of its application in Korea. In this study, the Oxy product, which is regarded as the causative agent of most lung diseases, was sprayed into a cleanroom at normal (6.5 ppm in solution) and worst case (65 ppm in solution) dilutions; the airborne aerosol was monitored with direct reading instruments. Areas of deposition were divided into the head airway, tracheobronchial, and alveolar regions. Four dose scenarios were considered in this study: adults and children in both daily average and sleep conditions. Most PHMG aerosols were smaller than PM1 (96%). Number-based concentration analysis showed that <100 nm nanoparticles comprised 81% and 69% of the aerosol when the 6.5 and 65 ppm solutions were used, respectively. In all scenarios, the number-based deposited dose increased in the order of alveolar, tracheobronchial, and head airway regions; the mass-based deposited dose increased in the order of the head airway, alveolar, and tracheobronchial regions. The deposited dose per unit body weight was higher in children than in adults in terms of both number- and mass-based concentrations. When the humidifier was sprayed, the highest number-based concentration was found at a particle size of 15.4 nm; the highest deposition fraction or dose by PM1 was observed in the pulmonary and head airways in both models.
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Exposure science has developed alongside epidemiology and toxicology as a field that aims to describe qualitatively and, in particular, quantitatively the contact of an individual or a population group with a chemical, physical, and biological stressor. Therefore, this chapter describes the basics of the exposure assessment process, its procedure and helpful sources to find data on human exposure factors like the US EPA Exposure Factors Handbook. Overall, the exposome is understood as the comprehensive—cumulative—description of the lifelong exposure history of individuals to changing exogenous and endogenous influences. In addition, the inclusion of human biomonitoring in exposure assessment and the importance of textiles as a source of indoor air pollution expands our scientific knowledge. Indispensable for understanding the health effects is the behavior of volatile and semi-volatile organic compounds, as well as particulate matter in the lungs. Many exposure and risk assessment strategies take their starting point from the exposure of sedimented dust indoors and its uptake through, e.g., hand-to-mouth contact. Nevertheless, some critical points like sampling conditions, type of analytical method, intake rates, bioaccessibility, and bioavailability have to be taken into account. In addition, special important exposure situations such as the use of printers, open fires indoors, as well as the exposure inside aircraft cabins are presented.
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This chapter provides a brief overview of emerging materials that either have the potential to be or have already been identified as problematic for the environment. The growing population, estimated to be \approx 10 billion people by the year 2050, will create asymmetric pressure on available resources, leading to the need for novel materials to drive technological advancement and alleviate the burden on natural resources. Development and implementation of new materials and technologies driven by necessity may exacerbate environmental contamination as these new materials are rushed into use without forethought into their environmental impacts. In this chapter, various aspects of 3D printing, nanocomposites, electronic waste (E-waste), biomaterials, cellulosic materials, volatile organic compounds (VOC), microplastics, and antibiotics have been discussed in terms of their current or potential environmental relevance. For example, Ag- and TiO2_2-nanoparticles (NPs) have potential for antibacterial, and UV protection applications, respectively, and are used in textiles, medical devices, dental fillings, etc. However, these NPs can pose a threat if released into the environment, which may occur through leaching mechanisms or through textile laundering. The annual global E-waste production is projected to increase to 74.7 Mt by the year 2030, thus increasing the potential for environmental contamination unless efficient recovery and remediation technologies are developed. Photovoltaic panels (PVs) are one such example that have emerged as significant E-waste contaminants. These devices have only recently been classified as E-waste by the European Commission, and their volumes are anticipated to increase rapidly. During pyrolysis processes (combustion, biomass conversion, etc.), a significant quantity of VOCs such as benzene, toluene, and phenol are expected to be released and pose both carcinogenic and noncarcinogenic health hazards to the workforce, neighboring general population, and environment. Furthermore, the tracking and detection of increased antibiotic resistance, and accumulation of microplastics leading to organic and metallic pollutants will be highlighted. One major environmental contaminant relevant in today’s society, per- and polyfluoroalkyl substances (PFAS), will not be discussed in this chapter as this topic is discussed in two separate chapters in the book. Material types, pros and cons, and modes of release into the environment will be discussed. The topics reviewed in this chapter will support parallel research on environmental impacts of next-generation materials as new technologies are developed and implemented in society.
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Recently, three-dimensional (3D) printing has attracted attention as a new manufacturing technology. However, there is lack of data and regulations regarding the emissions of ultrafine particles from 3D printers. Therefore, we investigated particle emissions from a 3D printer using a chamber system. The test system was improved by installing a developed mixer for accurate measurement. Without a mixer, the particle concentration was unstable depending on the sampling point; however, reliable data with good uniformity were obtained by installing a mixer. Using the test system with a mixer, we investigated particle emissions from a 3D printer during operation. Filaments made each of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) were used as the printing material. The effects of nozzle temperature and printing time were investigated. Compared to the effect of the printing time, the nozzle temperature had greater impact on the particle emissions. The dominant particle size for the emissions from a 3D printer is less than 10 nm, and the particle concentration decreased with increasing particle size.
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Three-dimensional (3D) printing is an additive manufacturing process that increases in application and consumer popularity. Studies with 3D printers have shown that the printing process releases particles and volatile organic compounds (VOCs). This review looked at 50 studies that analyzed the most commonly used printing process in consumer 3D printers, the material extrusion or so-called fused filament fabrication (FFF) method and summarizes the most important results. Although the reviewed studies often used different methods, general assumptions can be drawn: Higher printing temperature resulted in higher emissions, styrene was the main VOC emitted during printing with ABS, the size of released particles was in the nano range and filaments with additives could pose a higher risk due to the possible release of e.g., carbon nanotubes (CNTs). In vivo and in vitro studies showed toxic effects. Thus, we recommend: printing in a separated and ventilated room, using the lowest possible print temperature and be cautious with filaments containing particulate additives.
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Direct reading instruments (DRIs) for aerosols have been used in industrial hygiene practice for many years, but their potential has not been fully realized by many occupational health and safety professionals. Although some DRIs quantify other metrics, this article will primarily focus on DRIs that measure aerosol number, size, or mass. This review addresses three applications of aerosol DRIs that occupational health and safety professionals can use to discern, characterize, and document exposure conditions and resolve aerosol related problems in the workplace. The most common application of aerosol DRIs is the evaluation of engineering controls. Examples are provided for many types of workplaces and situations including construction, agriculture, mining, conventional manufacturing, advanced manufacturing (nanoparticle technology and additive manufacturing) and non-industrial sites. Aerosol DRIs can help identify the effectiveness of existing controls and as needed, develop new strategies to reduce potential aerosol exposures. Aerosol concentration mapping (ACM) using DRI data can focus attention on emission sources in the workplace, spatially illustrate the effectiveness of controls and constructively convey concerns to management and workers. Examples and good practices of ACM are included. Video Exposure Monitoring (VEM) is another useful technique in which video photography is synced with the concentration output of an aerosol DRI. This combination allows the occupational health and safety professional to see what tasks, environmental situations and/or worker actions contribute to the aerosol concentration and potential exposure. VEM can help identify factors responsible for temporal variations in concentration. VEM can assist training, engage workers, convince managers about necessary remedial actions and provide for continuous improvement of the workplace environment. Although using DRIs for control evaluation, ACM and VEM can be time-consuming, the resulting information can provide useful data to prompt needed action by employers and employees. Other barriers to adoption include privacy and security issues in some worksites. This review seeks to provide information so occupational health and safety professionals can better understand and effectively use these powerful applications of aerosol DRIs.
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Nanoplastics are emerging contaminants of concern for living organisms and ecosystems, yet nanoplastics are difficult to extract and analyse. Once released into the environment, the fate and behavior of nanoplastics are controlled by physical, chemical, and biological factors. Here, we review nanoplastics weathering, aggregation, biofouling, and bioavailability. Nanoplastics adsorb and transport metals and organic contaminants. Ingestion of nanoplastics by aquatic organims such as microbes, algae, invertebrates, and fish, induces toxicological effects on organism growth, behavior, and reproduction.
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3D fused deposition modeling (FDM) printing has been extensively applied in various building environments. However, particles are unintentionally emitted during the printing and potentially caused adverse health effects to users. To comprehend these emitted particles, this review summarized the background information, formation mechanisms, measurement methods, characterization and emission control methods based on over 100 literatures published from 2015 to 2022. Although discrepancies of the data amongst the literatures were seen, in general, ABS filaments emitted the highest particle concentration with the largest particle size while PLA generated least particles with the smallest size. The median emission rates in the print of ABS, PLA and other filaments (average of 20 other filaments) were 2.2 × 10¹⁰, 6.0 × 10⁸ and 3.9 × 10⁹ particles/min, respectively. The first quartile percentile and median geometric mean diameter (GMD) were 28.0 and 35.0 nm for ABS, 23.8 and 29.2 nm for PLA and 24.9 and 31.8 nm for the average of other filaments. Filaments with metal additives emitted smaller particles than the non-additive ones. Extra attentions should be paid as the particles from 3D FDM printing are with high concentration and very small sizes, which have a high deposition rate in alveoli. Effective control methods include modifying chemical composition, avoiding printing filaments higher than the recommended temperature, choosing reasonable low infill density and height, applying local ventilation with an enclosure and filters (particles can be removed more than 90%) and adjusting environment humidity if possible.
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Fused deposition modeling (FDM) printers dominate the consumer market because of their low cost and high efficiency, resulting in a market growth rate of 40% annually. However, undesired emission of nanoparticles during the printing is accompanied, which can cause adverse health effects. It is very desirable to quantify these nanoparticles. However, the size and concentration (or size distribution) of these nanoparticles change dynamically due to ongoing nucleation, condensation and coagulation. These mechanisms are sensitively affected by printing and environmental conditions and an accurate size distribution of the emitted nanoparticles can only be obtained by a rigorous experimental design. This study designed a sampler to reduce the influences from sampling and environmental conditions and to help accurately characterize the instantaneous emitted nanoparticles. By the sampler, the emissions from six different filaments, including an original poly-lactic acid (PLA-O), a carbon-fiber-filled PLA (PLA-C), an iron-additive PLA (PLA-Fe), an original white acrylonitrile butadiene styrene (ABS-W), a florescent ABS (ABS-F) and a glow-in-dark ABS (ABS-G) filament were characterized and compared. The results showed that the sampler method detected the particle emissions earlier than traditional methods, which have a majority size less than 20 nm. The ABS-W had the highest emission rate of 4.3 × 10¹⁰ #/g which was about one order of magnitude higher than that of ABS-F, ABS-G and PLA-Fe (∼10⁹ #/g) and three orders of magnitude higher than PLA-O and PLA-C filaments (∼10⁷ #/g). A new metric, dynamic emission index (DEI), was proposed to characterize the dynamic changes of emitted nanoparticles during the printing. With the DEI, one can clearly identify the emission intensity for different sizes of particles along the printing time for different filaments and take required precautions if needed.
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A three-dimensional (3D) printing pen is a popular writing instrument that uses a heated nozzle, and is similar to a 3D-printer. Processing thermoplastic filaments with a 3D-pen can emit ultrafine particles (UFPs). 3D-pen education sessions were held with “∏”-shaped partitions for the prevention of coronavirus disease (COVID-19). This study aimed to characterize UFP emissions from two types of 3D-pens and evaluate the influence of “∏”-shaped partitions on UFP exposure. Measurements of UFP emission rates and the size distribution of particles emitted from 3D-pens were conducted in a chamber (2.5 m³). The partition's influence on UFP exposure was evaluated with and without a “∏”-shaped partition on a desk. A scanning mobility particle sizer (SMPS) and an optical particle spectrometer (OPS) were used to measure the particle number concentration (PNC) and size distribution. For both 3D-pen A and B, the average emission rates were statistically significantly highest for acrylonitrile butadiene styrene (ABS) filament (8.4 × 10⁶ [3.4] particles/min and 1.1 × 10⁶ [1.8] particles/min), followed by polylactic acid (PLA) (2.8 × 10⁵ [1.5] particles/min and 4.8 × 10⁴ [1.8] particles/min) and polycaprolactone (PCL) filaments (1.4 × 10⁴ [2.8] particles/min and 2.0 × 10⁴ [2.8] particles/min). For all filaments, particles in the Aitken mode (30–100 nm) accounted for the highest proportion. In 3D-pen A, PNCs were higher with the partition than without it for ABS (1.2 × 10⁶ [1.15] particles/cm³ vs. 1.4 × 10⁵ [1.29] particles/cm³) and PLA (6.2 × 10⁵ [1.38] particles/cm³ vs. 8.9 × 10⁴ [1.12] particles/cm³), whereas for 3D-pen B, they were higher with the partition for ABS (9.6 × 10⁵ [1.13] particles/cm³ vs. 4.9 × 10⁵ [1.22] particles/cm³) only. With the partition installed, PNCs decreased to the background level after the operation ended, whereas it took 2–6 min without the partition. However, the mass concentrations of PLA and PCL with 3D-pen A were not statistically significantly different with respect to the partition status. The use of 3D-pens with a partition can lead to high UFP exposure. Therefore, guidelines are required for the safe use of 3D-pens and partitions.
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The paper shows own study on a hand exoskeleton described from environmental point of view: starting from constraints caused by patient-tailored therapy and healthy/disordered human biomechanics through possible problems associated with material engineering (mechanical properties, biocompatibility, etc.) and their compensation by exoskeleton’ designers to material and technological limitations associated with recycling. The purpose of this article is to investigate how current opportunities in this area are being used, including reverse engineering as a part of the concept of the disabled person’s hand exoskeleton. There is no doubt that more research is needed for a more complete understanding
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Additive manufacturing, enabling rapid prototyping and so-called on-demand production, has become a common method of creating parts or whole devices. On a 3D printer, real objects are produced layer by layer, thus creating extraordinary possibilities as to the number of applications for this type of devices. The opportunities offered by this technique seem to be pushing new boundaries when it comes to both the use of 3D printing in practice and new materials from which the 3D objects can be printed. However, the question arises whether, at the same time, this solution is safe enough to be used without limitations, wherever and by everyone. According to the scientific reports, three-dimensional printing can pose a threat to the user, not only in terms of physical or mechanical hazards, but also through the potential emissions of chemical substances and fine particles. Thus, the presented publication collects information on the additive manufacturing, different techniques, and ways of printing with application of diverse raw materials. It presents an overview of the last 5 years’ publications focusing on 3D printing, especially regarding the potential chemical and particle emission resulting from the use of such printers in both the working environment and private spaces.
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Fused filament fabrication (FFF) is one of the most widely used 3D printing/additive manufacturing (AM) techniques. Due to the wide adoption of the technique, concern about the environmental impact of FFF is one of the major concerns of users. Increasing demand and use of technologies have resulted in a significant increase in worldwide sales of AM machines, especially FFF machines, due to advantages to users. Failure to identify and address the issues related to life cycle analysis (LCA) of FFF might have a significant impact on the environment in the future. In this chapter, the LCA of FFF is analyzed, compared, and critically reviewed. The chapters presents the LCA of AM in general and later further discussion is made specifically on FFF. There are different types of AM processes which can be classified into several categories. Therefore comparison of the LCA of FFF with other different types of AM is discussed in detail. Based on this study, it can be concluded that FFF consumes higher energy compared with stereolithography and laser sintering. Ultrafine particles emission during FFF is also found to be higher, especially when ABS is used in FFF compared with polylactic acid materials. As FFF is relatively new compared to the traditional manufacturing process, the study serves as a foundation and reference for wide adoption of the FFF process and its impact on the environment.
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This chapter discusses indoor air quality (IAQ) in nonindustrial buildings. Historically, the concept of IAQ has included viewpoints that the introduction of outdoor air, via passive and mechanical ventilation, is required both to prevent the buildup of contaminants and the associated adverse health effects, as well as to provide for comfort of occupants. It has been observed that airborne contagious diseases and malodor are more prominent in crowded spaces with insufficient ventilation and poor or nonexistent control of contaminant sources. The International Building Code (IBC), the International Residential Code (IRC), the International Mechanical Code (IMC), and the American Society of Heating, Refrigeration and Air‐Conditioning Engineers (ASHRAE) Standards 62.1 and 62.2 recommend approaches to the control of contaminant sources and the provision of outdoor air ventilation to lower the risk of occupant dissatisfaction and diseases. The varied approaches that can be used during IAQ evaluations reflect the multitude of different problems that can occur in buildings. In developing countries, higher morbidity and mortality have multifactorial causes, with contaminated food, water, and air as major risk factors. The chapter focuses on IAQ evaluation protocols and various guidelines.
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Printing devices are known to emit chemicals into the indoor atmosphere. Understanding factors that influence release of chemical contaminants from printers is necessary to develop effective exposure assessment and control strategies. In this study, a desktop fused deposition modeling (FDM) 3-D printer using acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) filaments and two monochrome laser printers were evaluated in a 0.5 m³ chamber. During printing, chamber air was monitored for vapors using a real-time photoionization detector (results expressed as isobutylene equivalents) to measure total volatile organic compound (TVOC) concentrations, evacuated canisters to identify specific VOCs by off-line gas chromatography-mass spectrometry (GC-MS) analysis, and liquid bubblers to identify carbonyl compounds by GC-MS. Airborne particles were collected on filters for off-line analysis using scanning electron microscopy with an energy dispersive x-ray detector to identify elemental constituents. For 3-D printing, TVOC emission rates were influenced by a printer malfunction, filament type, and to a lesser extent, by filament color; however, rates were not influenced by the number of printer nozzles used or the manufacturer's provided cover. TVOC emission rates were significantly lower for the 3-D printer (49 to 3552 µg h⁻¹) compared to the laser printers (5782 to 7735 µg h⁻¹). A total of 14 VOCs were identified during 3-D printing that were not present during laser printing. 3-D printed objects continued to off-gas styrene, indicating potential for continued exposure after the print job is completed. Carbonyl reaction products were likely formed from emissions of the 3-D printer, including 4-oxopentanal. Ultrafine particles generated by the 3-D printer using ABS and a laser printer contained chromium. Consideration of the factors that influenced the release of chemical contaminants (including known and suspected asthmagens such as styrene and 4-oxopentanal) from a FDM 3-D printer should be made when designing exposure assessment and control strategies.
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3-D printing is an additive manufacturing process involving the injection of melted thermoplastic polymers, which are then laid down in layers to achieve a pre-designed shape. The heated deposition process raises concerns of potential aerosol and volatile organic compounds (VOC) emission and exposure. The decreasing cost of desktop 3-D printers has made the use of 3-D printers more acceptable in non-industrial workplaces lacking sufficient ventilation. Meanwhile, little is known about the characteristics of 3-D printing fume emission. The objective of this study was to characterize aerosols and VOC emissions generated from various filaments used with a low-cost 3-D printer in an environmental testing chamber. A pre-designed object was printed in 1.25 hours using eight types of filaments. A scanning mobility particle sizer and an aerodynamic particle sizer were employed to measure the particle size distribution in sub-half-micron fraction (<0.5 µm) and super-half-micron fraction (0.5-20 µm), respectively. VOC concentration was monitored real-time by a photoionization detector and sampled with a tri-sorbent thermal desorption tube, and analyzed by thermal desorption gas chromatography mass spectrometry (TD-GC/MS). Results showed high levels of fume particles emission rate (1.0 × 10(7) to 1.2 × 10(10) #/min) in the sub-half-micron range with mode sizes of 41-83 nm. Particle concentrations peaked during the heat-up and solid layer printing periods. Total VOC concentration in the chamber followed a first-order buildup, with predominant VOC species in the chamber were breakdown and reaction products of the filaments, such as styrene from ABS filaments. These findings and exposure scenario estimation suggest that although the VOC concentrations were much lower than occupational exposure limits, particles with size less than micron might be a concern for users of low-cost 3-D printers due to high respirablity, especially if used in settings without proper guidance and engineering control.
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3D printers are currently widely available and very popular among the general public. However, the use of these devices may pose health risks to users, attributable to air-quality issues arising from gaseous and particulate emissions in particular. We characterized emissions from a low-end 3D printer based on material extrusion, using the most common polymers: acrylonitrile-butadiene-styrene (ABS) and polylactic acid (PLA). Measurements were carried out in an emission chamber and a conventional room. Particle emission rates were obtained by direct measurement and modeling, whereas the influence of extrusion temperature was also evaluated. ABS was the material with the highest aerosol emission rate. The nanoparticle emission ranged from 3.7·108 to 1.4·109 particles per second (# s−1) in chamber measurements and from 2.0·109 to 4.0·109 # s−1in room measurements, when the recommended extruder temperature was used. Printing with PLA emitted nanoparticles at the rate of 1.0·107 # s−1 inside the chamber and negligible emissions in room experiments. Emission rates were observed to depend strongly on extruder temperature. The particles’ mean size ranged from 7.8 to 10.5 nanometers (nm). We also detected a significant emission rate of particles of 1 to 3 nm in size during all printing events. The amounts of volatile organic and other gaseous compounds were only traceable and are not expected to pose health risks. Our study suggests that measures preventing human exposure to high nanoparticle concentrations should be adopted when using low-end 3D printers.
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Novel engineered nanoparticles (NPs), nanomaterial (NM) products and composites, are continually emerging worldwide. Many potential benefits are expected from their commercial applications; however, these benefits should always be balanced against risks. Potential toxic effects of NM exposure have been highlighted, but, as there is a lack of understanding about potential interactions of nanomaterials (NMs) with biological systems, these side effects are often ignored. NPs are able to translocate to the bloodstream, cross body membrane barriers effectively, and affect organs and tissues at cellular and molecular levels. NPs may pass the blood-brain barrier (BBB) and gain access to the brain. The interactions of NPs with biological milieu and resulted toxic effects are significantly associated with their small size distribution, large surface area to mass ratio (SA/MR), and surface characteristics. NMs are able to cross tissue and cell membranes, enter into cellular compartments, and cause cellular injury as well as toxicity. The extremely large SA/MR of NPs is also available to undergo reactions. An increased surface area of the identical chemical will increase surface reactivity, adsorption properties, and potential toxicity. This review explores biological pathways of NPs, their toxic potential, and underlying mechanisms responsible for such toxic effects. The necessity of toxicological risk assessment to human health should be emphasised as an integral part of NM design and manufacture.
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Multiple studies have been dedicated to particle emissions from three dimensional printer (3D printer). They collectively have shown that 3D printers will emit significant ultrafine particles during their printing processes. An important step forward is to investigate the printing process in detail and help reducing emissions. This study investigates particle emissions from two filaments of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) according to four steps (loading, heating, printing, and unloading) during the 3D printing process in constraint of product quality assessment. The results show that ABS filament triggers at least times higher particle emissions than PLA filament (ABS-printed product presents higher quality with higher nozzle temperature (240 °C); however, higher nozzle temperature triggers substantially higher particle emission. This study further identifies that the particle emissions are mostly triggered by the heating process rather than the printing process. It indicates that filament undergoes decomposition during the heating period after being loading into the extruder. As for product quality in terms of surface roughness and production deformation, ABS is not compatible to fast neither printing speed nor low nozzle temperature; the PLA filament exhibits significant tolerance to temperature and feed rate changes. An optimization, which is externally heating up both the extruder and platform before the filament is loaded, shows that pre-heating reduces particle emissions by 75% for ABS filament when compared with the conventional procedure.
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Desktop three-dimensional (3D) printers are becoming commonplace in business offices, public libraries, university labs and classrooms, and even private homes; however, these settings are generally not designed for exposure control. Prior experience with a variety of office equipment devices such as laser printers that emit ultrafine particles (UFP) suggests the need to characterize 3D printer emissions to enable reliable risk assessment. The aim of this study was to examine factors that influence particulate emissions from 3D printers and characterize their physical properties to inform risk assessment. Emissions were evaluated in a 0.5-m3 chamber and in a small room (32.7 m3) using real-time instrumentation to measure particle number, size distribution, mass, and surface area. Factors evaluated included filament composition and color, as well as the manufacturer-provided printer emissions control technologies while printing an object. Filament type significantly influenced emissions, with acrylonitrile butadiene styrene (ABS) emitting larger particles than polylactic acid (PLA), which may have been the result of agglomeration. Geometric mean particle sizes and total particle (TP) number and mass emissions differed significantly among colors of a given filament type. Use of a cover on the printer reduced TP emissions by a factor of 2. Lung deposition calculations indicated a threefold higher PLA particle deposition in alveoli compared to ABS. Desktop 3D printers emit high levels of UFP, which are released into indoor environments where adequate ventilation may not be present to control emissions. Emissions in nonindustrial settings need to be reduced through the use of a hierarchy of controls, beginning with device design, followed by engineering controls (ventilation) and administrative controls such as choice of filament composition and color.
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Poor indoor air quality (IAQ) caused many problems for human; those problems can be classified into health problems which reduce the efficiency and output especially in workplaces. For example, health problems, like asthma and pulmonary inflammation, lead to low attendance level which affect the output. The main purpose of this paper is to review scientific literature on air filtration system effectiveness in improving indoor Air Quality (IAQ). These studies include topics such as: Chemical, biological, gases, particle and bacteria. Indoor air pollution emitted by occupants, equipment, furniture and building are also included. Portable air cleaning, filtration system and ventilation methods application in HVAC system, recent research relating filtration type and ventilation used in laboratory environments and the large space applications are also reviewed. The scope of studies investigated includes appropriate air filter technology and the compatibility between cost, the health problems, energy consumption and its relationship with filter pressure drop. Future studies are suggested to focus on cleaners and air filtration, ventilation and energy consumption in office buildings.
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3D printing, more professionally called additive manufacturing (AM) is a manufacturing technology (process) revolutionizing the world manufacturing industry. AM is a standard term adopted by the ASTM International Committee to include comprehensively methods that build 3D objects layer-by-layer using computer driven technology. It is completely different approach than traditional methods of subtracting materials from a larger work piece (for example, cutting or grinding) or conventional forming methods (for example, casting, pressing, injecting molding). Initially, 3D printing technology was developed as rapid prototyping, which enables users to create physical prototypes early in the design cycle so that flaws can be detected and corrected before they become costly. Furthermore, functional performances are optimized thereby making a product go to the market early through an iterative process of prototyping, testing, and analysis. Manufacturers started using this technology for production of finished goods due to advancement in the technology and discovery of new materials. Often, terms such as direct digital manufacturing, rapid manufacturing and solid freeform fabrication are of used to describe AM processes due to its additive technique. 3D computer data or stereolithography (STL) files drive all the processes, which contain information on the geometry of the object. This file (STL) can be obtained from 3D CAD software, medical scan data (for example, CT, MRI), or from existing objects using a point or laser scanners. The STL file breaks down the geometrical representation of the object into a simple mesh, which is manipulated into a suitable build orientation before it is converted into discrete 2D layers used by the machine. 3D printers use different types of additive manufacturing technologies, but they all share one core approach in common—they create a three dimensional object by building it successively layer by layer, until the entire object is completed. This technology continues to grow and capture the attention of many. Increasingly, companies from aerospace, motor sports, medical, dental, and consumer product industries are using additive processes to manufacture high-value parts in comparatively low volumes. Medicine will forever be changed as new bio printer actually print human tissues for bone and organ transplant. Aerospace is changing as well; most of the engineers prefer producing airplane parts with 3D printing due to the lightweight of the fabricated parts. Auto industry is not left out as well, major auto industries like Ford, Toyota, and general motors have improved the way they manufacture their parts with this technology. The objective of this paper is to have a comprehensive review of three-dimensional and micro three-dimensional printing technologies, competitors, and their available products. This paper also encompasses a characterization of MakerBot replicator desktop 3D printer (5th generation). The paper is organized as follows: Section 2 discusses different technologies in three-dimensional printing; Section 3 discusses the major competitors in 3D printing technology; Section 4 reviews different areas of applications; Section 5 discusses 3D micro printing technologies, and Section 6 discusses the major competitors in 3D micro printing technologies. Section 7 discusses the Characterization of MakerBot replicator, and Section 8 is the conclusion.
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It is getting more popular to use desktop 3D printers either at homes or offices, which may emit a large amount of particles when in use. This work aims to obtain accurate size-resolved particle emission rates from both single and two desktop 3D printers in a ten–thousand-level clean room, with acrylonitrile butadiene styrene (ABS) for the feedstock. Particle concentrations were measured at three different spots in the clean room. We found that the major size of particles produced by the 3D printers is less than 10μm (PM10). The further it is from the printer, the higher the particle concentrations are. Moreover, the smaller the size of particles, the higher the concentration of particles, with the size ranged from 0.25μm to 0.28μm corresponding to the highest concentration. The maximum value of particle concentration is around 2.5×104/L for single printer and 4×104/L for two printers.
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NanoParticles (NPs) skin absorption is a wide issue, which needs to be better understood. The attempt of this review is to summarize the scientific evidence concerning open questions, i.e.: the role of NPs intrinsic characteristics (size, shape, charge, surface properties), the penetration of NPs through the intact or impaired skin barrier, the penetration pathways which should be considered and the role of NPs interaction in physiological media. The outcomes suggest that one main difference should be made between metal and non-metal NPs. Both kinds have a secondary NPs size which is given after interaction in physiological media, and allows a size-dependent skin penetration: NPs ⩽ 4 nm can penetrate and permeate intact skin, NPs size between 4-20 nm can potentially permeate intact and damaged skin, NPs size between 21-45 nm can penetrate and permeate only damaged skin, NPs size > 45 nm cannot penetrate nor permeate the skin. Other aspects play an important role, mostly for metal NPs, i.e. dissolution in physiological media, which can cause local and systemic effects, the sensitizing or toxic potential and the tendency to create aggregates. This paper suggests a decision tree to evaluate the potential risk for consumers and workers exposed to NPs. Copyright © 2015. Published by Elsevier Inc.
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Pulmonary inflammation, especially persistent inflammation, has been found to play a key role in respiratory disorders induced by nanoparticles in animal models. In inhalation studies and instillation studies of nanomaterials, persistent inflammation is composed of neutrophils and alveolar macrophages, and its pathogenesis is related to chemokines such as the cytokine-induced neutrophil chemoattractant (CINC) family and macrophage inflammatory protein-1 α and oxidant stress-related genes such as heme oxygenase-1 (HO-1). DNA damages occur chemically or physically by nanomaterials. Chemical and physical damage are associated with point mutation by free radicals and double strand brake, respectively. The failure of DNA repair and accumulation of mutations might occur when inflammation is prolonged, and finally normal cells could become malignant. These free radicals can not only damage cells but also induce signaling molecules containing immunoreaction. Nanoparticles and asbestos also induce the production of free radicals. In allergic responses, nanoparticles act as Th2 adjuvants to activate Th2 immune responses such as activation of eosinophil and induction of IgE. Taken together, the presence of persistent inflammation may contribute to the pathogenesis of a variety of diseases induced by nanomaterials.
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The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. However, we are not aware of any data on particle emissions from commercially available desktop 3D printers. Therefore, we report on measurements of size-resolved and total ultrafine particle (UFP) concentrations resulting from the operation of two types of commercially available desktop 3D printers inside a commercial office space. We also estimate size-resolved (11.5 nm-116 nm) and total UFP (<100 nm) emission rates and compare them to emission rates from other desktop devices and indoor activities known to emit fine and ultrafine particles. Estimates of emission rates of total UFPs were large, ranging from ˜2.0 × 1010 # min-1 for a 3D printer utilizing a polylactic acid (PLA) feedstock to ˜1.9 × 1011 # min-1 for the same type of 3D printer utilizing a higher temperature acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because most of these devices are currently sold as standalone devices without any exhaust ventilation or filtration accessories, results herein suggest caution should be used when operating in inadequately ventilated or unfiltered indoor environments. Additionally, these results suggest that more controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers.
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Additive manufacturing processes take the information from a computer-aided design (CAD) file that is later converted to a stereolithography (STL) file. In this process the drawing made in the CAD software is approximated by triangles and sliced containing the information of each layer that is going to be printed. There is a discussion of the relevant additive manufacturing processes and their applications. The aerospace industry employs them because of the possibility of manufacturing lighter structures to reduce weight. Additive manufacturing is transforming the practice of medicine, and making work easier for architects. In 2004, the Society of Manufacturing Engineers did a classification of the various technologies and there are at least four additional significant technologies in 2012. Studies are reviewed which were about the strength of products made in additive manufacturing processes. However there is still a lot of work and research to be accomplished before additive manufacturing technologies become standard in the manufacturing industry because not every commonly-used manufacturing material can be handled. The accuracy needs improvement to eliminate the necessity of a finishing process. The continuous and increasing growth experienced since the early days and the successful results up to the present time allow for optimism that additive manufacturing has a significant place in the future of manufacturing.
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The increasing use of nanoparticles in medicine has raised concerns over their ability to gain access to privileged sites in the body. Here, we show that cobalt-chromium nanoparticles (29.5 +/- 6.3 nm in diameter) can damage human fibroblast cells across an intact cellular barrier without having to cross the barrier. The damage is mediated by a novel mechanism involving transmission of purine nucleotides (such as ATP) and intercellular signalling within the barrier through connexin gap junctions or hemichannels and pannexin channels. The outcome, which includes DNA damage without significant cell death, is different from that observed in cells subjected to direct exposure to nanoparticles. Our results suggest the importance of indirect effects when evaluating the safety of nanoparticles. The potential damage to tissues located behind cellular barriers needs to be considered when using nanoparticles for targeting diseased states.
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Tuberculosis (TB) is a public health problem that may pose substantial risks to health care workers and others. TB infection occurs by inhalation of airborne bacteria emitted by persons with active disease. We experimentally evaluated the effectiveness of in-room air filtration systems, specifically portable air filters (PAFs) and ceiling-mounted air filters (CMAFs), in conjunction with dilution ventilation, for controlling TB exposure in high-risk settings. For each experiment, a test aerosol was continuously generated and released into a full-sized room. With the in-room air filter and room ventilation system operating, time-averaged airborne particle concentrations were measured at several points. The effectiveness of in-room air filtration plus ventilation was determined by comparing particle concentrations with and without device operation. The four PAFs and three CMAFs we evaluated reduced room-average particle concentrations, typically by 30% to 90%, relative to a baseline scenario with two air-changes per hour of ventilation (outside air) only. Increasing the rate of air flow recirculating through the filter and/or air flow from the ventilation did not always increase effectiveness. Concentrations were generally higher near the emission source than elsewhere in the room. Both the air flow configuration of the filter and its placement within the room were important, influencing room air flow patterns and the spatial distribution of concentrations. Air filters containing efficient, but non-high efficiency particulate air (HEPA) filter media were as effective as air filters containing HEPA filter media.
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The knowledge of exposure to the airborne particle emitted from 3D printing activities is becoming a crucial issue due to the relevant spreading of such devices in recent years. To this end, a low-cost desktop 3D printer based on fused deposition modeling principle was used. Particle number, alveolar-deposited surface area and mass concentrations were measured continuously during printing processes in order to evaluate particle emission rates and factors. Particle number distribution measurements were also performed to characterize the size of the emitted particles. Ten different materials and different extrusion temperatures were considered in the survey. Results showed that all the materials investigated emit particles in the ultrafine range (with a mode in the 10-30 nm range), whereas no emission of super-micron particles was detected for all the materials under investigation. The emission was affected strongly by the extrusion temperature. In fact, the emission rates increase as the extrusion temperature raises. Emission rates up to 1×10(12) particles min(-1) were calculated. Such high emission rates were estimated to cause large alveolar surface area dose in workers when 3D activities run. In fact, a 40-min long 3D printing was found to cause doses up to 200 mm(2) . This article is protected by copyright. All rights reserved.
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Most desktop 3D printers designed for the consumer market utilize a plastic filament extrusion and deposition process to fabricate solid objects. Previous research has shown that the operation of extrusion-based desktop 3D printers can emit large numbers of ultrafine particles (UFPs: particles less than 100 nm) and some hazardous volatile organic compounds (VOCs), although very few filament and printer combinations have been tested to date. Here we quantify emissions of UFPs and speciated VOCs from five commercially available desktop 3D printers utilizing up to nine different filaments using controlled experiments in a test chamber. Median estimates of time-varying UFP emission rates ranged from ~108 to ~1011 #/min across all tested combinations, varying primarily by filament material and, to a lesser extent, bed temperature. The individual VOCs emitted in the largest quantities included caprolactam from nylon-based and imitation wood and brick filaments (ranging from ~2 to ~180 μg/min), styrene from acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS) filaments (~10 to ~110 μg/min), and lactide from polylactic acid (PLA) filaments (~4 to ~5 μg/min). Results from a screening analysis of the potential exposures to these products in a typical small office environment suggest caution should be used when operating many of the printer and filament combinations in enclosed or poorly ventilated spaces or without the aid of a combined gas and particle filtration system.
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Emissions from a desktop 3D printer based on fused deposition modeling (FDM) technology were measured in a test chamber and indoor air was monitored in office settings. Ultrafine aerosol (UFA) emissions were higher while printing a standard object with polylactic acid (PLA) than with acrylonitrile butadiene styrene (ABS) polymer (2.1 × 10⁹ vs. 2.4 × 10⁸ particles/min). Prolonged use of the printer led to higher emission rates (factor 2 with PLA and 4 with ABS, measured after seven months of occasional use). UFA consisted mainly of volatile droplets, and some small (100–300 nm diameter) iron containing and soot-like particles were found. Emissions of inhalable and respirable dust were below the limit of detection (LOD) when measured gravimetrically, and only slightly higher than background when measured with an aerosol spectrometer. Emissions of volatile organic compounds (VOC) were in the range of 10 µg/min. Styrene accounted for more than 50% of total VOC emitted when printing with ABS; for PLA, methyl methacrylate (MMA, 37% of TVOC) was detected as the predominant compound. Two polycyclic aromatic hydrocarbons (PAH), fluoranthene and pyrene, were observed in very low amounts. All other analyzed PAH, as well as inorganic gases and metal emissions except iron (Fe) and zinc (Zn), were below the LOD or did not differ from background without printing. A single 3D print (165 min) in a large, well-ventilated office did not significantly increase the UFA and VOC concentrations, whereas these were readily detectable in a small, unventilated room, with UFA concentrations increasing by 2,000 particles/cm³ and MMA reaching a peak of 21 µg/m³ and still being detectable in the room even 20 hr after printing.
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This study evaluated the emissions characteristics of hazardous material during fused deposition modeling type 3D printing. Particulate and gaseous materials were measured before, during, and after 3D printing in an exposure chamber. One ABS and two PLA (PLA1 and PLA2) cartridges were tested three times. For online monitoring, a scanning mobility particle sizer, light scattering instrument, and total volatile organic compound (TVOC) monitor were employed and a polycarbonate filter and various adsorbent tubes were used for offline sampling. The particle concentration of 3D printing using ABS material was 33-38 times higher than when PLA materials were used. Most particles were nanosize (<100 nm) during ABS (96%) and PLA1 (98%) use, but only 12% were nanosize for PLA2. The emissions rates were 1.61  1010 ea/min and 1.67  1011 ea/g cartridge with the ABS cartridge and 4.27-4.89 108 ea/min and 3.77-3.91x109 ea/g cartridge with the PLA cartridge. TVOCs were also emitted when the ABS was used (GM; 155 ppb, GSD; 3.4), but not when the PLA cartridges were used. Our results suggest that more research and sophisticated control methods, including the use of less harmful materials, blocking emitted containments, and using filters or adsorbents, should be implemented.
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Air cleaning is broadly applied to reduce contaminant concentrations in many buildings. Although diverse in underlying technology, mode of application, target contaminants, and effectiveness, there are also commonalities in the framework for understanding their primary impact (i.e., concentration reductions) and secondary impacts (e.g., energy use, byproduct production). Furthermore, both primary and secondary impacts are moderated by the specific indoor context in which an air cleaner is used. This paper explores the dynamics of removal efficiency in a variety of air cleaners and combines efficiency and flow rate to put air cleaning in the context of real indoor environments. This allows for the direct comparison to other indoor pollutant loss mechanisms (ventilation and deposition) and further suggests that effective air cleaner use is context- and contaminant-specific. The concentration reduction impacts of air cleaning need to be contrasted with the secondary consequences that arise from the use of air cleaners. This paper emphasizes two important secondary consequences: energy use of the air cleaning process and primary and secondary emissions from air cleaners. The paper also identifies current research challenges and areas for large leaps in our understanding of the role of air cleaners in improving indoor environmental quality. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Article
The field of nanotechnology currently is undergoing a dramatic expansion in material science research and development. Most of the research efforts have been focused on applications; the implications (i.e., health and environmental effects) research has lagged behind. The success of nanotechnology will require assurances that the products being developed are safe from an environmental, health, and safety (EHS) standpoint. In this regard, it has been previously reported in pulmonary toxicity studies that lung exposures to ultrafine or nanoparticles (defined herein as particle size <100 nm in one dimension) produce enhanced adverse inflammatory responses when compared to larger particles of similar composition. Surface properties (particularly particle surface area) and free radical generation, resulting from the interactions of particles with cells may play important roles in nanoparticle toxicity. This brief review identifies some of the key factors for studying EHS risks and hazard effects related to nanoparticle exposures. Health and environmental risk evaluations are products of hazard and exposure assessments. The key factors for discussion herein include the importance of particle characterization studies; development of a nanomaterial risk framework; as well as corresponding hypothesis-driven, mechanistically-oriented investigations, concomitant with base set hazard studies which clearly demonstrate that particle size is only a single (and perhaps minor) factor in influencing the safety of nanomaterials.
Article
Recent epidemiological studies have shown an association between increased particulate urban air pollution and adverse health effects on susceptible parts of the population, in particular the elderly with pre-existing respiratory and cardiovascular diseases. Urban particles consist of three modes: ultrafine particles, accumulation mode particles (which together form the fine particle mode) and coarse mode particles. Ultrafine particles (those of < 0.1 micron diameter) contribute very little to the overall mass, but are very high in number, which in episodic events can reach several hundred thousand/cm3 in the urban air. The hypothesis that ultrafine particles are causally involved in adverse responses seen in sensitive humans is based on several studies summarized in this brief review. Studies on rodents demonstrate that ultrafine particles administered to the lung cause a greater inflammatory response than do larger particles, per given mass. Surface properties (surface chemistry) appear to play an important role in ultrafine particle toxicity. Contributing to the effects of ultrafine particles is their very high size-specific deposition when inhaled as singlet ultrafine particles rather than as aggregated particles. It appears also that ultrafine particles, after deposition in the lung, largely escape alveolar macrophage surveillance and gain access to the pulmonary interstitium. Inhaled low doses of carbonaceous ultrafine particles can cause mild pulmonary inflammation in rodents after exposure for 6 h. Old age and a compromised/sensitized respiratory tract in rodents can increase their susceptibility to the inflammatory effects of ultrafine particles significantly, and it appears that the aged organism is at a higher risk of oxidative stress induced lung injury from these particles, compared with the young organism. Results also show that ultrafine particle effects can be significantly enhanced by a gaseous co-pollutant such as ozone. The studies performed so far support the ultrafine particle hypothesis. Additional studies are necessary to evaluate mechanistic pathways of responses.
Article
Studies into the effects of ultrafine particles in the lung have shown adverse effects considered to be due in part to the particle size. Air pollution particles (PM(10)) are associated with exacerbations of respiratory disease and deaths from cardiovascular causes in epidemiological studies and the ultrafine fraction of PM(10) has been hypothesized to play an important role. The aim of the present study was to investigate proinflammatory responses to various sizes of polystyrene particles as a simple model of particles of varying size including ultrafine. In the animal model, we demonstrated that there was a significantly greater neutrophil influx into the rat lung after instillation of 64-nm polystyrene particles compared with 202- and 535-nm particles and this was mirrored in other parameters of lung inflammation, such as increased protein and lactate dehydrogenase in bronchoalveolar lavage. When surface area instilled was plotted against inflammation, these two variables were directly proportional and the line passed through zero. This suggests that surface area drives inflammation in the short term and that ultrafine particles cause a greater inflammatory response because of the greater surface area they possess. In vitro, we measured the changes in intracellular calcium concentration in mono mac 6 cells in view of the potential role of calcium as a signaling molecule. Calcium changes after particle exposure may be important in leading to proinflammatory gene expression such as chemokines. We demonstrated that only ultrafine polystyrene particles induced a significant increase in cytosolic calcium ion concentration. Experiments using dichlorofluorescin diacetate demonstrated greater oxidant activity of the ultrafine particles, which may explain their activity in these assays. There were significant increases in IL-8 gene expression in A549 epithelial cells after treatment with the ultrafine particles but not particles of other sizes. These findings suggest that ultrafine particles composed of low-toxicity material such as polystyrene have proinflammatory activity as a consequence of their large surface area. This supports a role for such particles in the adverse health effects of PM(10).
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