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Air change rate and concentration of formaldehyde in residential indoor air
Abstract
The purpose of this study was to investigate the relationship between air change rates and indoor concentrations of formaldehyde. Concentrations of formaldehyde and air change rates were measured in 96 homes in Québec City, Canada, in winter 2005. House characteristics such as heating systems or recent renovations were also documented. Formaldehyde concentrations were regressed to air change rates among the entire sample and among some sub-samples of homes, and predictive intervals were computed. The air change rate ensuring a formaldehyde concentration below Health Canada's guideline value of 50 μg m−3 in 95% of homes was 0.26 h−1 based on the entire sample, 0.34 h−1 in homes with recent off-gassing sources of formaldehyde, and 0.37 h−1 in homes heated mainly by electrical baseboard heaters. These results indicate that ventilation effectively decreases formaldehyde concentrations, but some categories of homes such as those with new off-gassing sources and homes heated by electrical baseboard heaters may require a higher air change rate to keep their formaldehyde levels within Health Canada's guidelines.
... In a study investigating 398 existing US homes, the mean indoor formaldehyde concentration was 21.6 µg/m 3 [12]. Two recent surveys conducted in Canada found formaldehyde concentrations (averaged over 24-h) exceeded the Health Canada residential indoor air quality 8-h exposure guideline of 50 µg/m 3 [13] in 16 out of 59 homes (27%) in Prince Edward Island [14], and in 11 out of 96 homes (11%) in Quebec City [15]. ...
... Based on formaldehyde emission factors, one study estimated that an air change rate (ACH) of 0.5 h −1 would maintain formaldehyde concentrations below 50 ppb in typical new North American houses [21]. A study in Canadian homes found that an ACH of 0.35 h −1 appears sufficient to ensure a formaldehyde concentration lower than the 50 µg/m 3 Health Canada guideline in most homes [15]. ...
... [8], where the mean indoor concentration was 43 µg/m 3 . They are also lower than the formaldehyde concentrations measured in studies from more than ten years ago, such as 32.2 µg/m 3 from 162 French homes [55] and about 30 µg/m 3 from 96 Canadian homes [15]. Possible reasons for the lower concentrations in this set of homes is that the sample homes were all built with lower-emitting materials and mechanical ventilation as required by California building regulations. ...
Recent studies have succeeded in relating emissions of various volatile organic compounds to material mass diffusion transfer using detailed empirical characteristics of each of the individual emitting materials. While significant, the resulting models are often scenario specific and/or require a host of individual component parameters to estimate emission rates. This study developed an approach to estimate aggregated emissions rates based on a wide number of field measurements. We used a multi-parameter regression model based on previous mass transfer models to predict formaldehyde emission rate for a whole dwelling using field-measured, time-resolved formaldehyde concentrations, air exchange rates, and indoor environmental parameters in 63 California single-family houses built between 2011 and 2017. The resulting model provides time-varying formaldehyde emission rates, normalized by floor area, for each study home, assuming a well-mixed mass balance transport model of the home, and a well-mixed layer transport model of indoor surfaces. The surface layer model asserts an equilibrium concentration within the surface layer of the emitted materials that is a function of temperature and RH; the dwelling ventilation rate serves as a surrogate for indoor concentration. We also developed a more generic emission model that is suitable for broad prediction of emission for a population of buildings. This model is also based on measurements aggregated from 27 homes from the same study. We showed that errors in predicting household formaldehyde concentrations using this approach were substantially less than those using a traditional constant emission rate model, despite requiring less unique building information.
... The overall mean air change rate was 0.2 h -1 ; half of the homes had ventilation rates below 7.5 L/s per person. Using the same dataset, Gilbert et al. estimated that the air change rate to ensure a formaldehyde concentration below Health Canada's guideline value of 50 μg/m 3 in 95% of homes were 0.26 h -1 , 0.34 h -1 and 0.37 h -1 for the entire sample, homes with recent off-gassing sources of formaldehyde and homes heated mainly by electrical baseboard heaters [82,83]. These studies are included in this review based on the assumption that the bedroom air change rates would be more or less similar to the whole dwelling air change rate. ...
... [80] unknown [75] unknown [79] unknown 1,4 [79] unknown 2, 4 [79] unknown 2, 5 [79] unknown 1, 3 [82] unknown 6 [82] unknown 7 [79] unknown 2, 3 [80] unknown [82] unknown 5 [81] unknown [76] MV [78] unknown measured in New Jersey [78] unknown measured in California [78] unknown 5 [78] unknown measured in Texas 1 -arithmetic mean 2 -geometric mean 3 -measured in single-family houses 4 -measured in apartment 5 -data from all dwellings 6 -homes heated mainly by electrical baseboard heaters (Health Canada 2005) 7 -homes with recent off-gassing sources of formaldehyde J o u r n a l P r e -p r o o f ...
... [80] unknown [75] unknown [79] unknown 1,4 [79] unknown 2, 4 [79] unknown 2, 5 [79] unknown 1, 3 [82] unknown 6 [82] unknown 7 [79] unknown 2, 3 [80] unknown [82] unknown 5 [81] unknown [76] MV [78] unknown measured in New Jersey [78] unknown measured in California [78] unknown 5 [78] unknown measured in Texas 1 -arithmetic mean 2 -geometric mean 3 -measured in single-family houses 4 -measured in apartment 5 -data from all dwellings 6 -homes heated mainly by electrical baseboard heaters (Health Canada 2005) 7 -homes with recent off-gassing sources of formaldehyde J o u r n a l P r e -p r o o f ...
Good sleep is essential for our health and daytime functioning; seven to nine hours of sleep each night are recommended for people age 18 to 64.(1,2) Noise, light, temperature and air quality affect our sleep. However, very few regulations address indoor air quality (IAQ) in bedrooms, and even fewer studies examine the relationship between sleep quality, ventilation and IAQ(3) This column reviews 10 studies reported in nine publications(4)(-1)(2) that examined whether providing clean air to a sleeping person will result in improved sleep quality. The column also provides information on the expected effects on sleep when bedroom ventilation and IAQ are inadequate.
... The results from our institution as well as research centres around the world, including China, Great Britain, Canada and Sweden, confirm the complex nature of the relationship between indoor environmental factors and irritants and allergic diseases [2,3,8,11]. Indoor air quality deserves special attention because it is present in the area where people spend the greater part of the day, and recent studies indicate that the concentration of toxic substances in indoor air often exceeds concentrations measured outdoors. ...
... ECAP results confirm that air quality is affected by building age, heating system type and indoor appliances used. Even though we did not perform measurements of concentrations of chemicals released from sources located in indoor areas, our results are consistent with the available literature [9,11,12]. ...
... Common building and finishing materials may contain harmful substances that may pose a risk to allergy sufferers, including formaldehyde and volatile organic compounds (VOCs) [2,3,5,8,9,[11][12][13]. ...
Introduction:
Structural materials and interior appliances are frequently mentioned as elements of modern buildings which may have an impact on the natural history of allergic diseases.
Aim:
We hypothesized that the building age, the type of the heating system and the use of various indoor appliances can influence the occurrence of allergic rhinitis (AR) and asthma.
Material and methods:
The study group comprised 18,617 individuals. The tool used in the study was the European Community Respiratory Health Survey (ECRHS) and the International Study of Asthma and Allergies in Childhood (ISAAC) study questionnaire, adapted to European conditions (Middle and Eastern Europe) and used as part of the study called "Implementation of a System for the Prevention and Early Detection of Allergic Diseases in Poland".
Results:
Questionnaire results indicated that people living in homes built in the years 1971-1990 had higher rates of allergic rhinitis (OR = 1.15025), which was correlated with clinical findings of increased occurrence of seasonal allergic rhinitis (OR = 1.60543). The leading factor contributing to the intensification of AR symptoms was the central heating (OR = 1.45358). As opposed to AR, people living in buildings with central heating less often declared asthma (OR = 0.8407). A clinical examination confirmed that central heating reduced the symptoms of moderate asthma (OR = 0.3524).
Conclusions:
Increasing building age and certain indoor heating methods are important risk factors for the occurrence of allergic rhinitis and asthma.
... Formaldehyde (HCHO), among indoor pollutants, is one of the biggest concerns due to its high inherent cancer risk, especially in residential environments [26][27][28], and abundance in closed spaces. Gilbert et al., 2008, found that air leakages effectively reduce the indoor formaldehyde concentration and are the primary solution for indoor formaldehyde removal [29]. It seems that formaldehyde pollution from indoor sources continues throughout the lifetime of residences [30]. ...
... Formaldehyde (HCHO), among indoor pollutants, is one of the biggest concerns due to its high inherent cancer risk, especially in residential environments [26][27][28], and abundance in closed spaces. Gilbert et al., 2008, found that air leakages effectively reduce the indoor formaldehyde concentration and are the primary solution for indoor formaldehyde removal [29]. It seems that formaldehyde pollution from indoor sources continues throughout the lifetime of residences [30]. ...
The contradiction of indoor air quality (IAQ) and energy conservation by isolating the indoor environment from the outdoor through airtightness is one of the challenges of the building sector.
The key issue is, what are the optimum airtightness limits that can ensure IAQ in naturally ventilated buildings, taking into account the paradoxical effect of house leakages on the infiltration of outdoor pollutants and accumulation of indoor-generated pollutants?
For this purpose, the effect of different levels of airtightness required in energy-compliant, low-energy, and very low-energy buildings on the concentration of two pollutants with outdoor and indoor origin, PM2.5 and formaldehyde, respectively, were studied.
This study used a multizone model, CONTAM(W), which was validated using measured data to study the distribution of selected pollutants in a typical relatively old dwelling, to investigate the situation in Iran. Subsequently, we conducted simulations based on different combinations of scenarios for airtightness, user behavior, source strength, and meteorological parameters.
The results showed that increasing the airtightness from the baseline scenario (ACH50 = 11.11/h) to 3, 1.5, and 0.75 in closed window conditions reduced the PM2.5 by 15%, 38%, and 58%, respectively, and elevated formaldehyde by 23%, 77%, and 169%, correspondingly.
Under normal outdoor PM2.5 pollution, indoor formaldehyde levels exceeded the permissible limit only in closed window conditions, and IAQ remained acceptable in other scenarios.
However, there is no indication that IAQ can be ensured by any degree of airtightness under severe outdoor air pollution, demanding specific solutions, such as those proposed in this work.
... Some researchers explored the relationship between temperature, humidity, and indoor concentration (or emission rate, or key emission parameters) [11]. Some other experimental studies showed that increasing air exchange rates and controlling the type of building materials used in home construction could decrease indoor formaldehyde concentrations in new homes [47,48]. The humidity (water It should be noted that this study just performed a preliminary experimental investigation on the reactions between ozone and vehicle cabin/furniture material. ...
... Some researchers explored the relationship between temperature, humidity, and indoor concentration (or emission rate, or key emission parameters) [11]. Some other experimental studies showed that increasing air exchange rates and controlling the type of building materials used in home construction could decrease indoor formaldehyde concentrations in new homes [47,48]. The humidity (water vapor) might also impact the fates of some reactions [49]. ...
Volatile organic compounds (VOCs) emitted from building and vehicle cabin materials seriously affect indoor and in-cabin air quality, as well as human health. Previous studies revealed that some VOCs from building materials could react with ozone to affect the concentration levels of the indoor environment, but seldom refers to vehicle cabin materials. In this study, we performed experimental investigation for two kinds of vehicle cabin materials (car carpet, sealing strip) and one furniture material (medium-density fiberboard) by conducting small-scale chamber tests under two different conditions, with ozone (about 110 μg/m³) and without ozone (about 10 μg/m³), to explore the effect of in-cabin chemistry on VOC emissions. We observed the VOC concentration changes in the two scenarios and found that ozone had a significant impact on the concentrations of aldehydes and ketones while having little impact on the concentrations of benzene series. We introduced a gain ratio to quantitatively reflect the concentration changes in the presence of ozone. The gain ratio for aldehydes and ketones is greater than one, while that for the benzene series is basically around one with a small fluctuation range. This study demonstrates that ozone can react with VOCs containing unsaturated carbon–carbon bonds or carbon–oxygen bonds emitted from varied materials to produce aldehydes and ketones, which will further reduce indoor and in-cabin air quality.
... In indoor domestic environments, formaldehyde concentrations may vary between 10 and 100 µg m −3 , which is 2 to 15 times higher than those found in outdoor air [6,8,15,16]. In June 2004, the International Agency for Research on Cancer (IARC) classified formaldehyde as a human carcinogen, like benzene [17]. ...
... It should also be noted that the gaseous formaldehyde concentrations obtained are typically those measured in indoor air, either in domestic (0-100 µg m −3 ) [6,8,13,15] or in professional environments (0-740 µg m −3 ) [22]. ...
This work aims at developing and validating under laboratory-controlled conditions a gas mixture generation device designed for easy on-site or laboratory calibration of analytical instruments dedicated to air monitoring, such as analysers or sensors. This portable device, which has been validated for formaldehyde, is compact and is based on the diffusion of liquid formaldehyde through a short microporous interface with an air stream to reach non-Henry equilibrium gas–liquid dynamics. The geometry of the temperature-controlled assembly has been optimised to allow easy change of the aqueous solution, keeping the microporous tube straight. The formaldehyde generator has been coupled to an on-line formaldehyde analyser to monitor the gas concentration generated as a function of the liquid formaldehyde concentration, the temperature, the air gas flow rate, and the microporous tube length. Our experimental results show that the generated gaseous formaldehyde concentration increase linearly between 10 and 1740 µg m⁻³ with that of the aqueous solution ranging between 0 and 200 mg L⁻¹ for all the gas flow rates studied, namely 25, 50 and 100 mL min⁻¹. The generated gas phase concentration also increases with increasing temperature according to Henry’s law and with increasing the gas–liquid contact time either by reducing the gas flow rate from 100 to 25 mL min⁻¹ or increasing the microporous tube length from 3.5 to 14 cm. Finally, the performances of this modular formaldehyde generator are compared and discussed with those reported in the scientific literature or commercialised by manufacturers. The technique developed here is the only one allowing to operate with a low flow rate such as 25 to 100 mL min⁻¹ while generating a wide range of concentrations (10–1000 µg m⁻³) with very good accuracy.
... In order to improve indoor air quality, various technologies have been made to remove HCHO, such as ventilation [8], physical adsorption [9,10], low-temperature plasma [11,12], photocatalysis [13][14][15][16], and catalytic oxidation [17][18][19][20][21]. Among them, catalytic oxidation at room temperature has a very promising application prospect. ...
... In addition, the redox cycles of Ni 3+ /Ni 2+ and Co 3+ /Co 2+ would help to improve oxygen absorption and transfer, which would generate more active oxidation sites [59,60], as indicated by Eqs. (7,8,9,10) (the M represents Ni and Co). ...
Catalytic oxidation of formaldehyde (HCHO) at ambient temperature is an effective method for indoor HCHO removal. In this study, Ni/Co-Layered double hydroxides (LDHs) with different molar ratios were successfully synthesized via a one-step hydrothermal method. Their structure and morphology were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET)-specific surface area, X-ray photoelectron spectroscopy (XPS), and H2 temperature-programmed reduction (H2-TPR), respectively. The catalytic activity results show that Ni/Co-LDHs with the Ni/Co ratio of 1:2 exhibited enhanced activity for HCHO decomposition. The removal efficiency of indoor HCHO was up to 99.7% at ambient temperature, and it remained highly stable without any obvious deactivation even after a reaction time of 800 min. The abundant hydroxyl groups were favorable for catalytic activity, which could not only enrich the adsorption of HCHO on the surface of catalysts, but also directly react with HCHO to obtain CO2 and H2O. Moreover, the redox cycles of Ni3+/Ni2+ and Co3+/Co2+ would provide more reactive oxygen species and therefore promote catalytic reaction. This work can provide a new insight into LDH-based catalysts for low-concentration HCHO removal in practical application.
... The ventilation rate also affects the indoor HCHO level. A previous study indicated that the level of HCHO decreases with an increase in the ventilation rate [53]. Additionally, Table 5 presents a comparison of the IAQ between this study and oversea studies. ...
... The concentrations of HCHO and bacteria in the indoor air were affected by the hours of air conditioner operation per day and the floor dampness, respectively. Previous studies have indicated mechanical ventilation usage reduces the air exchange rate [57], and Hun and his co-workers revealed that high indoor HCHO levels could be observed in buildings with a low air exchange rate [53]. Thus, indoor HCHO levels were higher in buildings with mechanical ventilation. ...
... However, in artificial boards and other decoration materials that use formaldehyde as the raw material, paraformaldehyde depolymerizes and continuously releases [4], which seriously pollutes the indoor environment. Methods to eliminate indoor formaldehyde pollution include ventilation [5], plant purification [6], adsorption [7,8], plasma purification [9], catalytic oxidation [10], etc. Among these, the ventilation and air exchange method is simple and feasible but has limitations in application scenarios due to the influence of the house layout and climatic conditions. ...
Formaldehyde is an important downstream chemical of syngas. Furniture and household products synthesized from formaldehyde will slowly decompose and release formaldehyde again during use, which seriously affects indoor air quality. In order to solve the indoor formaldehyde pollution problem, this paper took the catalytic oxidation of formaldehyde as the research object; prepared a series of low-cost, acid-treated manganese dioxide nanorod catalysts; and investigated the effect of the acid-treatment conditions on the catalysts’ activity. It was found that the MnNR-0.3ac-6h catalyst with 0.3 mol/L sulfuric acid for 6 h had the best activity. The conversion rate of formaldehyde reached 98% at 150 °C and 90% at 25 °C at room temperature. During the reaction time of 144 h, the conversion rate of formaldehyde was about 90%, and the catalyst maintained a high activity. It was found that acid treatment could increase the number of oxygen vacancies on the surface of the catalysts and promote the production of reactive oxygen species. The amount of surface reactive oxygen species of the MnNR-0.3ac-6h catalyst was about 13% higher than that of the catalyst without acid treatment.
... Contrary to previous studies, the mean ACH in the investigated building is much higher than the value recommended by the ASHRAE standard, i.e., 0.35 h −1 . The ACH was reported by (Rim et al. 2010) for a test house and (Gilbert et al. 2008) investigation on 96 houses in Quebec City as well as (Hou et al. 2019) study on 294 urban Chinese bedrooms showed average values lower than the ASHRAEE level. It could be attributed to high leakages of the building which did not meet the national energy standard requirements for airtightness and energy efficiency due to the cheapness of energy in Iran. ...
Undoubtedly, prolonged exposure to PM2.5 is a potential risk factor for mortality. However, the extent of people’s indoor exposure to ambient originated particles depends on their infiltration, which is a function of the meteorological parameters, air exchange rates (ACH), and structural characteristics of the building, including window airtightness.
Considering that about 60% of buildings in Tehran have not observed the energy-saving and window airtightness requirements, we investigated the real-time changes of indoor–outdoor PM2.5 concentrations, infiltration factor, and the effect of various meteorological parameters on indoor particle levels in an apartment, which was a typical example of relatively old buildings in Tehran with drafty windows, before and after sealing the window gaps.
The results confirmed that window status and building leakage could substantially modulate the effect of outdoor sources on indoor PM2.5. Airtightness resulted in a reduction of approximately 40% in ACH and 20% in I/O.
Indoor PM2.5 concentrations were strongly associated with outdoor levels, which explained 86 percent of indoor PM2.5 variations (R² = 0.86). Air tightening reduced the indoor and outdoor particle correlation by about 10% (R² = 0.77).
Indoor PM2.5 was dependent on the pressure difference and was negatively correlated with the relative humidity difference and temperature difference between outdoor and indoor environments. Nevertheless, the impact of meteorological parameters on indoor levels was overshadowed by the effect of the outdoor source.
Furthermore, the comparison of inverse distance weighting (IDW) interpolated PM 2.5 data of ambient fixed stations with outdoor measured PM 2.5 depicted that ambient stations’ data are not applicable as surrogates for exposure.
... HCHO contributed to 16 % and 10 % to the OVOC mixing ratio in the SoCAB and SJV, respectively. Primary sources of HCHO include automotive exhaust (Anderson et al., 1996), industrial emissions (Salthammer et al., 2010), biomass burning (Holzinger et al., 1999), and off-gassing from building materials (Gilbert et al., 2008;Liu et al., 2016). HCHO can also form from the photooxidation of VOCs, such as alkenes and BVOCs (Choi et al., 2010;Parrish et al., 2012). ...
Comprehensive aircraft measurements of volatile organic compounds (VOCs) covering the South Coast Air Basin (SoCAB) and San Joaquin Valley (SJV) of California were obtained in the summer of 2019. Combined with the CO, CH4, and NOx data, the total calculated gas-phase hydroxyl radical reactivity (cOHRTOTAL) was quantified to be 6.1 and 4.6 s-1 for the SoCAB and SJV, respectively. VOCs accounted for ∼ 60 %–70 % of the cOHRTOTAL in both basins. In particular, oxygenated VOCs (OVOCs) contributed >60 % of the cOHR of total VOCs (cOHRVOC) and the total observed VOC mixing ratio. Primary biogenic VOCs (BVOCs) represented a minor fraction (<2 %) of the total VOC mixing ratio but accounted for 21 % and 6 % of the cOHRVOC in the SoCAB and SJV, respectively. Furthermore, the contribution of BVOCs to the cOHRVOC increased with increasing cOHRVOC in the SoCAB, suggesting that BVOCs were important ozone precursors during high ozone episodes. Spatially, the trace gases were heterogeneously distributed in the SoCAB, with their mixing ratios and cOHR being significantly greater over the inland regions than the coast, while their levels were more evenly distributed in SJV. The results highlight that a better grasp of the emission rates and sources of OVOCs and BVOCs is essential for a predictive understanding of the ozone abundance and distribution in California.
... To date, various technologies have been developed to remove HCHO including ventilation (Gilbert et al. 2008), physical adsorption (Ye et al. 2017), chemical adsorption (Su et al. 2019b), plasma-assisted oxidation (Liang et al. 2010;Wan et al. 2011;Zhu et al. 2015), photocatalytic degradation (Li et al. 2018b;Liu et al. 2018;Yu et al. 2013;Zhang et al. 2017Zhang et al. , 2014, photoelectrocatalytic oxidation (Song et al. 2018), biological/botanical filtration (Dingle et al. 2000;Guieysse et al. 2008), and catalytic oxidation (Rochard et al. 2019;Su et al. 2019a;Wang et al. 2017;Yan et al. 2019;Yang et al. 2017). Among these strategies, photocatalytic oxidation is by far the most promising method owing to its high HCHO removal efficiency, energy-saving power, and mild reaction conditions (Yu et al. 2013). ...
Accelerating the interfacial charge transfer process (ICTS) of the catalysts can immensely improve the photocatalytic efficiency. Doping transition metal ions not only promote the ICTS, but also boost multielectron reduction reactions of oxygen. Herein, birnessite-type MnO2 have been modified by different transition metal ions (TM = Zn²⁺, Cu²⁺, and Fe³⁺) in this work. Post-doping, Fe-Birnessite was featured by the highest photocatalytic HCHO oxidation activity with 80 ppm of HCHO which presented complete removal of HCHO for 80 min, while K-, Cu-, and Zn-Birnessite took 105, 135, and 170 min, respectively. In detail, the photoexcited electrons were caught by Fe (III) and then generated Fe (II),which could continue to capture photoexcited electrons to produce Fe (I) under visible light; on the other hand, the Fe (I) could be oxidized by O2 to obtain Fe (II) and then recover to Fe (III). This process tremendously improved the ICTS.
... Aldehydes enter as raw materials or additives in many industrial activities including the manufacturing of building materials, flooring wallpaper, adhesives, and furniture (Zhang et al., 2020). Aldehydes are exchanged in the indoor and outdoor air; however, their indoor levels are generally more than that of outdoor levels (Gilbert et al., 2008). The indoor air aldehydes' pollution has a major public health concern due to the continued elevation in their indoor level and at the same time, general populations spend most of their time in indoor environments. ...
Aldehydes are highly reactive carbonyl compounds that are widespread in the nature. Aldehydes are broadly distributed in the indoor and outdoor environment sourced from the industrial, restaurant, and motor vehicular exhausts. Besides, aldehydes are thought to be a major cause of the photochemical smog in the air. Aldehydes are also present in rainwater and the surface water due to their washing away from the atmosphere owing to their high-water solubility. In addition, microbial or photochemical degradation of organic chemicals leads to the formation of aldehydes in the surface water. Furthermore, chlorination and ozonation sterilization of drinking water lead to aldehydes’ formation. On the other hand, aldehydes could be formed during cooking upon high-temperature frying and also could be sourced from cigarette smoke and/or other combustion operations. Besides, aldehydes are present in wine and vegetable oils, and they are formed as by-products during deterioration, maturing, or microbial fermentation of food. Human exposure to aldehydes from the environment or food could bring many adverse health effects either acute or chronic ones. Aldehydes are highly reactive with biological molecules; thus, they are considered highly toxic. The aldehydes’ biochemical modification could lead to the disruption of biological functions, and consequently, cause many diseases. Thus, aldehyde monitoring in the surrounding environmental and food samples is vital to control the toxic aldehydes’ possible health risk on humans. Aldehydes’ different sources in the environment, molecular toxicity mechanisms, possible effects on human health, and recently developed analytical methods for determination and control of aldehydes in environmental and food samples will be summarized in this chapter.
... 74 As products containing formaldehyde such as plywood, particleboard, carpets, and foam insulation are frequently used in indoors, many studies focus on the indoor level of this compound. 75 As shown in Figure 9, mean indoor formaldehyde levels reported are relatively low. However, high concentration peaks were reported in many studies. ...
Considering the alarming rise in the rate of asthma and respiratory diseases among school children, it is of great importance to investigate all probable causes. Outside of the home, children spend most of their time in school. Many studies have researched the indoor environmental quality of primary and secondary school buildings to determine the exposure of school children to indoor air pollution. However, studies of very young children in nurseries are scarce. Unlike at elementary schools or universities, children in nurseries are more vulnerable due to their physiology, inability to articulate discomfort and to adapt their behaviour to avoid exposures. This article reviews current studies on the indoor environment in nurseries. It summarizes air pollution levels and related environmental and behavioural factors in nurseries that have been reported in the literature. Additionally, exposure to indoor air pollution and related potential health outcomes are examined. This review concludes that indoor air pollution in nurseries often exceeds current guidelines, and designers and policymakers should be made aware of the impact on the health and wellbeing of children in nurseries. Proper interventions and guidelines should be considered to create a healthy indoor environment for nursery children.
Practical application: Previous IAQ assessments have mainly focused on indoor temperatures and CO 2 levels. Data on comprehensive monitoring (including PMs, NO 2 , O 3 and other pollutants) of indoor air quality of nurseries are scarce. Particularly in the UK, studies about indoor air quality in nurseries have not been founded. This paper categorized relevant articles according to the focus of the study, to provide evidence to a better understanding of current indoor air quality in nursery environments.
... 8,[28][29][30] Hence, registered concentration levels of formaldehyde in indoor air of houses in focus confirmed that the above-mentioned sources have been frequently pronounced in UAE houses. Moreover, previous studies 31, 32 have revealed a significant negative correlation between formaldehyde concentrations and air change per hour "ACH" of house. Consequently, highly recorded formaldehyde concentrations in UAE houses may result from a bad or infrequent aeration of such houses. ...
The maintenance of a good indoor air quality (IAQ) has been revealed highly required for ensuring comfort and respectable
health conditions for home’s residents. Nowadays, the main causes of the homes air quality degradation have been stated to be originated from
both indoor and outdoor sources such as gases and/or particles, where their health impacts have been showed to be more hazardous under
inadequate ventilation, high temperatures, and high humidity. In the light of the above, investigation of IAQ inside homes seems to be highly
recommended. Accordingly, the current research has been aimed to investigate the IAQ in 12 houses located in different parts from Abu Dhabi
in United Arab Emirates (UAE) through a regular monitoring of total suspended particles (TSPs), carbon monoxide (CO), carbon dioxide (CO2),
formaldehyde (CH2O), and volatile organic compound (VOC) concentrations and some meteorological parameters such as humidity and temperature in side door, kitchen, and bathroom of each selected house. Compared with international standards and with other measured concentrations exhibited in diverse studies around the world, recorded concentrations in different compartments of selected houses have been lower
than detection limits and standard values in the case of VOCs and in the case of CO, respectively, indicating that no health risk originates from
such pollutants, especially for residents without sensitive problems. On the contrary, registered CH2O and CO2 concentration levels have largely
exceeded standard values alerting residents about the potential impact of cooking, fuel combustion, hot water boilers, air conditioning systems,
smoking and may be using electronic cigarettes (vaping) while keeping windows and doors closed, causing a bad aeration. In the case of TSP,
recorded concentrations have never exceeded 100µg/m3 in all compartments of 40% of selected houses. However, in the case of houses “3”
and “5,” recorded concentrations have been higher than those recorded in houses from Slovakia, indicating the significant impact of outdoor
activities in UAE around these houses and to the non-negligible effect of dust event originating from Saharan advection.
... Yamamoto et al. reported residential air change rates in three major US metropolitan areas (Elizabeth, New Jersey; Houston, Texas; and Los Angeles County, California) [78]. A median air change rate, based on measurements using the PFT tracer gas method in each house, was 0. [82,83]. These studies are included in this review based on the assumption that the bedroom air change rates would be more or less similar to the whole dwelling air change rate. ...
Sleep is essential for our health and well-being. Some research suggests that air quality influences sleep quality in bedrooms, but the evidence is limited. Research, until now, has focused on how indoor air quality affects health, comfort, and cognitive performance during waking hours. Less information is available on the levels of indoor air quality and ventilation in bedrooms, as well as on their consequences for sleep quality and the next-day performance. This paper addresses the former by reviewing research published in peer-reviewed journals in this millennium. The bedroom ventilation has been chosen as a specific focus of this review paper, which also includes a review of selected international standards for bedroom ventilation. Arising out of this review based on a framework of comparison of field data with CO2 and ventilation benchmarks from widely adopted international standards, an attempt is made to generalize the level of bedroom ventilation that exists in practice in residential dwellings and apartments across different seasons and different parts of the world. Besides, based on a limited number of studies dealing with the impact of bedroom ventilation on sleep quality, an attempt is also made to associate the measured field data with a potential impact on sleep quality.
... Among them, formaldehyde is considered as a major indoor air pollutant due to its many emission sources such as construction materials, furniture, glues and paints, etc. [6,7]. As a result, European and French formaldehyde concentrations in indoor air typically vary between 10 µg m −3 and 100 µg m −3 [6,[8][9][10], much higher than those found in the corresponding outdoor environments, which are of the order of 1 µg m −3 to 10 µg m −3 in most cases [11]. Several studies have reported that formaldehyde is always present in indoor environments, such as in homes [7,12] or in schools [13,14]. ...
This paper describes a compact microfluidic analytical device in a closed-circuit developed for the detection of low airborne formaldehyde levels. The detection is based on the passive trapping of gaseous formaldehyde through a microporous tube into the acetylacetone solution, the derivative reaction of formaldehyde with acetylacetone to form 3,5-Diacetyl-1,4-dihydrolutidine (DDL) and the detection of DDL by fluorescence. The recirculation mode of the analytical device means that the concentration measurement is carried out by quantification of the signal increase in the liquid mixture over time, the instantaneous signal increase rate being proportional to the surrounding gaseous formaldehyde concentration. The response of this novel microdevice is found to be linear in the range 0–278 µg m⁻³. The reagent volume needed is flexible and depends on the desired analytical resolution time and the concentration of gaseous formaldehyde in the environment. Indeed, if either the gaseous concentration of formaldehyde is high or the reagent volume is low, the fluorescence signal of this recirculating liquid solution will increase very rapidly. Consequently, the sensitivity simultaneously depends on both the reagent volume and the temporal resolution. Considering a reagent volume of 6 mL, the hourly and daily detection limits are 2 and 0.08 µg m⁻³, respectively, while the reagent autonomy is more than 4 days the airborne formaldehyde concentration does not exceed 50 µg m⁻³ as it is usually the case in domestic or public indoor environments.
... Therefore, the concentration of formaldehyde in summer and autumn was higher, and it was lower in winter and spring, which was consistent with the results of Figures 2, 3 and 4. Some studies have also shown that indoor formaldehyde concentration was higher in summer, while it was lower in winter [38,39]. We can reduce formaldehyde concentration by reducing indoor temperature and humidity to reduce the damage to the human body [41,42]. ...
This study focused on measuring the pollution characteristics, the monthly and seasonal variation rule of formaldehyde in the teaching machine room of Guangxi Normal University from March 2016 to February 2018, and the correlation between formaldehyde concentration and temperature or humidity were also analyzed. The results indicated that seasonal and monthly variation rule of formaldehyde changed with temperature and humidity in the teaching machine room. The concentration of formaldehyde was higher in summer and autumn, while was lower in winter and spring. Further analysis indicated that there was a strongly positive correlation (R ² >0.87, R ² >0.85, R ² >0.81, p<0.01) between formaldehyde concentration and temperature, relative humidity or absolute humidity. It concluded that the formaldehyde concentration increased with the increase in the temperature and humidity. The maximum concentrations of formaldehyde in sitting breathing area and standing breathing area were 0.442mg/m ³ , 0.445mg/m ³ and 0.184mg/m ³ , 0.213mg/m ³ in July 2016, 2017, respectively. After eleven years, the formaldehyde in the teaching machine room was still seriously exceeded the standard (0.1mol/L), and decreased the temperature or humidity could effective alleviate the level of indoor formaldehyde concentration.
... Formaldehyde is a major pollutant of indoor air due to its multiple sources (materials, combustion, painting, etc.). Several studies [1][2][3][4] have shown that indoor formaldehyde concentrations are 2-15 times higher than those measured outdoors, and may vary typically between 10 to 100 µg/m 3 . Casset et al. have shown that formaldehyde is implicated in allergic diseases, particularly for asthmatic people [5]. ...
This paper describes a compact microfluidic analytical device developed for the detection of low airborne formaldehyde concentrations. This microdevice was based on a three-step analysis, i.e., the passive gaseous formaldehyde uptake using a microporous membrane into an acetylacetone solution, the derivatization with acetylacetone to form 3,5-diacetyl-1,4-dihydrolutidine, and the quantification of the latter using fluorescence detection. For a rapid and easier implementation, a cylindrical geometry of the microporous element was considered to perform laboratory-controlled experiments with known formaldehyde concentrations and to establish the proof of concept. This work reports the evaluation of the uptake performance according to the microporous tube length, the liquid flow rate inside the tube, the gas flow rate outside the tube, and the gaseous formaldehyde concentration. A 10.0 cm microporous tube combined with a gas flow rate of 250 NmL/min (normal milliliters per minute) and a liquid flow rate of 17 µL/min were found to be the optimized conditions. In these experimental conditions, the fluorescence signal increased linearly with the gaseous formaldehyde concentration in the range 0–118 µg/m3, with the detection limit being estimated as 0.13 µg/m3 when considering a signal-to-noise ratio of 3.
... It has been suggested that increasing ventilation rates for buildings (above ADF, 2010) for a period pre-or post-occupancy, when VOC emissions are likely to be at their highest, would assist in reducing occupant exposure [21]. Other authors have suggested the use of 'bakeout' procedures in conjunction with increased (forced) ventilation rates [97], where for a period up to a week (preferably pre-occupation), indoor temperatures are raised (varying between 30 and 40°C) to reduce the high level off-gassing phase [26,98,99]. Holøs et al. [26] carried out a review and meta-analysis of the influence of ventilation and bake-out and showed that the off-gassing phase of new or recently ventilated buildings follows a multi-exponential trend in terms of VOC decay, with a rapid decline in emissions during the first month (for some species) followed by a more gradual decrease, until a steady state is reached after at least two years and from some studies longer. ...
Poor indoor air quality, can cause a variety of adverse health effects. Pollutant exposure levels inside buildings are likely due to pollutants from both indoor and outdoor sources. Although there are many indoor airborne pollutants, the current review focusses on Volatile Organic Compounds (VOCs), and considers the current Total Volatile Organic Compounds (TVOC) standards alongside other guideline values, to control levels within the indoor environment. We reviewed the current scientific data showing the occurrence of various VOCs in buildings internationally, and the available toxicological reviews for the individual VOCs with potential for adverse health effects that require attention. We considered available health-based general population indoor guidelines for long and short-term exposure in respect of individual compounds, including acetaldehyde, α-pinene, d-limonene, formaldehyde, naphthalene, styrene, tetrachloroethylene, toluene and xylenes (mixture).
We conclude individual VOC guidelines are the most appropriate way forward and that TVOC can be used as an indicator for indoor air quality. This study highlights which compounds should be prioritised for monitoring purposes. Our findings inform discussions around the improvement of general population health, source control and the need to raise awareness of the potential impacts of pollutants in the home.
... (Sherman and Hodgson, 2004) proposed to set a threshold of 0.3 h -1 for existing houses and 0.5 h -1 for new ones. (Gilbert et al., 2008) showed that if we want 95% of the houses with a formaldehyde concentration below 50 µg.m -3 , ACR threshold must be 0.26 h -1 . ...
In future building regulations 2020, building performance is going to be extended to global performance, including indoor air quality (IAQ). In the energy performance (EP) field, successive regulations pushed for a "performance-based" approach, based on an energy consumption requirement at the design stage. Nevertheless, ventilation regulations throughout the world are still based on prescriptive approaches, setting airflows requirements. This thesis should develop a performance-based approach to insure that ventilation is designed to avoid risks for occupant’s health.Given the European context with the generalization of nearly zero energy buildings, envelope airtightness is often included in EP-calculations, frequently through single-zone models with uniform air leakage. Because more consideration is often given to EP than to IAQ issues, impact of several zones interconnected by unevenly distributed leaks, on the envelope and on internal partition walls, is a rarely investigated issue. We propose to study it in this thesis.Faced with this issue, we conducted an experimental study on multizone air leakages of 23 detached houses and developed an innovative database. The analysis of this database reveals that internal air leakage can become significant at door undercuts and that the type of building structure has a great influence. We proposed airleakage values and dispersion input data for multizone IAQ models. Then, through a multizone modelling of a low energy house case study, we quantified impacts of these airleakage distribution data on IAQ. We modelled CO2, humidity and formaldehyde with two type of ventilation (exhaust-only or balanced). We highlighted strong impacts and concluded that detailed airleakage distributions should be used in IAQ performance assessment methods.An extensive review work combined with complementary analysis allowed us to come up with the development of a performance-based approach for house ventilation to be used at the design stage in a regulatory calculation. We selected the use of five relevant IAQ performance indicators, based on CO2, formaldehyde and PM2.5 exposures, and RH-based indicators assessing both condensation and health risks. We proposed also pollutant emission data and occupancy schedules to be used. Lastly, we described the multizone modelling laws and assumptions to be used, the physical models and associated assumptions, and the boundary conditions.Importantly, we demonstrated that our proposed method was applicable, applying it to a low-energy house case study. We assumed being at the design stage of a house which should comply with a hypothetical regulation, requiring IAQ performance indicators and associated thresholds. We also demonstrated how such an approach could help at the design stage in key choices as the type of structure (regarding its impact on airleakage distributions), the type of ventilation system, the level of pollutant emissions. Indeed, in the case study studied case, only the balanced ventilation combined with low or medium-emission class of formaldehyde emissions allow to fulfill the IAQ requirements. We showed also that such an approach could help in the ventilation design, notably the distribution of the air inlets and/or outlets, or even the airflows, in order to secure the fulfillment of IAQ requirements.
... Cold or non-thermal plasma are not yet on the market (Luengas et al., 2015). These major technical issues also have limitations like high energy consumption and low removal efficiency (Gilbert et al., 2008;Mo et al., 2008). Biological degradation (Lu et al., 2012) and botanical air filtration are still under development, currently operating at low efficiency and with insufficient understanding of long-term safety (Wang et al., 2014;Luengas et al., 2015). ...
We varied face velocities and initial formaldehyde concentrations to investigate the formaldehyde removal performance of coconut shell activated carbon (AC) adsorptive filter media. AC surface were rather uneven, with coarse and small pores, and with amorphously formed irregular layer structures. C, O, Mg, P etc. were detected, which showed the existence of MgO in AC. The AC surface area was 1333.3304 m ² g –1 , and ketone-C=O bonds were successfully grafted onto the carbon. At any given face velocity, the experimental results indicate that the adsorption capacity increased and the breakthrough time decreased as the initial concentration increased. The breakthrough behavior of the AC adsorptive filter could henceforth be evaluated with confidence using the breakthrough curves predicted by the Yoon-Nelson model. Of the three kinetic models that were assessed, the experimental and calculated results show that the correlation coefficient and mean absolute performance error (MAPE) of the pseudo-second-order model generated the best approximation of the kinetic dynamics of the adsorption process—better than those of the pseudo-first-order model and intraparticle diffusion model. Both the intraparticle diffusion model and the membrane diffusion affected the overall rate of the adsorption process by more than one step. The equilibrium data of the AC adsorptive filter media was found to best fit the Langmuir model. The D-R equation predicted the equilibrium capacity of AC at a relative pressure of 0.151.
... 15, 16 Different fresh air intakes and air purifying approaches in the indoor environment tend to correspond to variations in the form of indoor formaldehyde concentrations. 17 For example, constant fresh air intake may correspond to a constant indoor formaldehyde concentration because the emission rate of formaldehyde from indoor sources (e.g., furniture) changes little for a given indoor air temperature and humidity, 18−20 especially when the indoor climate is controlled by air conditioning or space heating. In contrast, natural ventilation tends to correspond to fluctuating indoor formaldehyde concentrations because the fresh air intake varies. ...
Formaldehyde, an air pollutant in the indoor environment, may have severe effects on human health. The aim of this study is to compare the health effects caused by intermittent exposure to formaldehyde (based on real monitoring) to those caused by exposures at constant concentration. Health effects explored in this study including the oxidative stress, histopathological changes, inflammatory responses, etc. Mice were divided into 3 groups and exposed to intermittent concentration formaldehyde (0.8ppm for 12 hours and 0 ppm for another 12 hours), or constant concentration formaldehyde (0.4 ppm for 24 hours) or zero concentration formaldehyde (reference) per day for 7, 14 and 28 days. Following these exposures, bronchoalveolar lavage fluid (BALF), lung tissue and lung tissue homogenate were prepared to measure biomarkers of oxidative stress (ROS, MDA, GSH), histopathological changes, inflammatory responses (EOS, NEU, LYM, IL-4, IL-5, IL-13, IL-6, IL-17A, NF-κB, IL-1β) and apoptosis (caspase-3). Compared to the constant exposure, intermittent exposure to fluctuating formaldehyde concentrations resulted in more profound increases in numbers of inflammatory cells in the BALF, greater biological alterations including apoptosis. The findings imply that with the same average indoor formaldehyde concentrations over the same time, a ventilation strategy to avoid higher peak concentrations would lead to lower health risks.
... Two types of study are considered: those using field measurements and those modelling indoor pollutants. The former uses indoor measurements of concentrations of selected pollutants in order to identify common air quality issues and to relate them to a building's characteristics (Gilbert et al., 2008;Langer & Bekö, 2013;Langer et al., 2016). Some focus on sensitive groups of the population, showing the relationships between health outcomes and indoor variables (Chin et al., 2014;Singleton et al., 2017). ...
This paper describes a method to identify sets of archetypes that are statistically representative of the Chilean housing stock.
... The manufactures were forced to reduce levels of outgassing or off gassing (gradual release of formaldehyde from the parent material) in structural panel products, which include softwood plywood, OSB, and composite panels. However, there are numerous studies still reporting formaldehyde contamination of residential and non-residential indoor environments, especially in new homes, in which the air change rate necessary to maintain formaldehyde compliance is higher (Gilbert et al. 2008;Mantanis et al. 2007;Maruo et al. 2007;Offermann et al. 2007). Formaldehyde levels in the air below 0.1 ppm are considered safe (Oanh and Hung 2004;Kitek Kuzman and Kutnar 2014). ...
Because of the increasing emissions of various pollutants, rapidly growing energy demands, and possible global warming consequences, renewable and nature friendly construction materials are gaining importance. Climate change due to global warming, variations in oil prices and environmental threats have led to significant demand for the wood bio and bio-based products, where construction products represent a significant volume. Construction industry has significant environmental, social and economic impacts on the society. The wood buildings require much lower process energy and result in lower carbon emissions than the buildings of other materials such as brick, aluminium, steel and concrete. If a shift is made towards greater use of wood in buildings, the low fossil fuel requirement for manufacturing wood compared with other materials is much more significant in the long term than the carbon stored in the wood building products. To compare the environmental performance of a building in the whole life cycle, the carbon footprint of 15 insulation materials was calculated. The obtained values were compared to the actual effect of the respective thermal insulation. The transparency of the comparison was achieved by taking into account the specific weight of each material, as well as differences in their thermal conductivity (λ). Moreover, a study of environmental neutrality of different types of insulation materials is presented. For the thermal insulation materials with the lowest environmental impact, the environmental neutrality is reached in only 0.57 heating season and in 7.89 heating seasons for the insulation with the highest environmental impact.
... Obširen pregled študij je dokazal, da so koncentracije, izmerjene v analiziranih študijah, presegle predpisane ali priporočene mejne vrednosti, kar lahko pri izpostavljenih [Silva, 2013]. -Air change rate and concentration of formaldehyde in residential indoor air [Gilbert, 2008]. ...
The term sustainable development has been known since 1987 and means balancing four aspects of development: economic, environmental, social and health. These aspects should be equally represented in the design of sustainable buildings. The purpose of this article is to check on the case of single-family prefabricated house by Slovenian manufacturer, whether are all four aspects of sustainability are treated equally. To assess the sustainable aspects of construction we used a method developed by Mateja Dovjak and Aleš Krainer in 2013, which follows the basic morphology of engineering design. Assessment of sustainable aspects was made step by step: Step 1 - analysis of actual conditions, step 2 - defining sustainable indicators Step 3 - defining sustainable goals, and Step 4 - analysis and final evaluation. Based on the analysis of actual conditions we chose one house. After reviewing existing sources and literature, we found that the health aspect in the sustainability assessment is mainly excluded. The results of step 2 are defined indicators in building energy efficiency, the impact of construction products on the environment, the cost of heating and lighting, day lighting of the areas and the potential impact of construction products on health. For each criterion we determined limit values and measurable goals (step 3). The results of step 4 showed that not all four aspects of sustainable development are treated equally, because the environmental and economic aspects override health. With the aim of comprehensive assessment of the sustainability aspects of design, this study introduces the health aspect, its indicators and goals. The presented assessment can be used for the design of construction products and buildings, from the design to the waste and its re-use. In sustainable design multidisciplinary collaboration is crucial in all phases.
... Formaldehyde is a major pollutant of indoor air due to its multiple sources (materials, combustion, painting, etc.) [1]. Several studies [2][3][4] have shown that indoor Formaldehyde concentrations are 2 to 15 times higher than those measured outdoor, and may vary typically between 10 and 100 g m −3 . Casset et al. [5] have shown that Formaldehyde is implicated in allergic diseases, particularly for asthmatic people. ...
This paper reports on the development of a novel colorimetric analytical method based on microfluidic technologies for the detection of low airborne Formaldehyde concentrations, representative of those found in indoor air, i.e. 10–100 μg.m⁻³. The new analytical technique operates according to 4 distinct steps: 1) gas sampling, 2) gaseous Formaldehyde uptake into the aqueous solution using an annular gas/liquid flow at room temperature, 3) derivatization reaction with acetylacetone solution at 65 °C producing 3,5-Diacetyl-1,4-dihydrolutidine (DDL) and 4) colorimetric DDL detection with a liquid-core-waveguide.
... Indoor air pollutants include particulate matter, NO, O 3 , CO, HCHO, and many others. Among these, HCHO is typical example; it can cause sick building syndrome, and has been classified as a carcinogen by the US Environmental Protection Agency (Gilbert et al., 2005(Gilbert et al., , 2006(Gilbert et al., , 2008. ...
In this study, the effect of the catalyst pretreatment temperature, which is one of the more important factors in HCHO oxidation at room temperature over Pd catalysts, was examined. To evaluate the effect of the pretreatment temperature on the catalytic activity, Pd-supported catalysts were prepared at temperatures ranging from 673 to 1,073 K under a hydrogen atmosphere. The correlation between the pretreatment temperature and catalytic activity produced a volcano-shaped plot. X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, and CO chemisorption confirmed that the catalytic activity highly depended on the Pd size or dispersion.
... Several studies reported the indoor and outdoor concentrations of low molecular weight aldehydes and ketones (mainly FA, AA, and Ac) worldwide, including Brazil (e.g., Pal and Kim 2007, Pereira et al. 2004, Pal et al. 2008, Gilbert et al. 2008, Blondel and Plaisance 2011. However, there are relatively few studies of high molecular weight CC, including unsaturated, branched, and aromatic compounds (de Carvalho et al. 2008;Ochs et al, 2011Ochs et al, , 2015. ...
This study demonstrated, for the first time, Fe(III)/peroximonosulphate (PMS) could be an efficient advanced oxidation process (AOP) for wastewater treatment. Bisphenol A (BPA) was chosen as a model pollutant in the present study. Fe(III)-activated PMS system proved very effective to eliminate 92.18% of BPA (20 mg/L) for 30-min reaction time at 0.50 mM PMS, 1.5 g/L Fe(III), pH 7.0. The maximum degradation of BPA occurred at neutral pH, while it was suppressed at both strongly acidic and alkaline conditions. Organic and inorganic ions can interfere with system efficiency either positively or negatively, so their interaction was thoroughly investigated. Furthermore, the presence of organic acids also affected BPA degradation rate, especially the addition of 10 mM citric acid decreased the degradation rate from 92.18 to 66.08%. Radical scavenging experiments showed that SO4•– was the dominant reactive species in Fe(III)/PMS system. A total of 5 BPA intermediates were found by using LC/MS. A possible degradation pathway was proposed which underwent through bridge cleavage and hydroxylation processes. Acute toxicity of the BPA degradation products was assessed using Escherichia coli growth inhibition test. These findings proved to be promising and economical to deal with wastewater using iron mineral for the elimination of organic pollutants.
Graphical abstract
... This compound is associated with building construction materials, such as fibreboard, plywood, paints, insulation and wallboard (Bernstein et al. 2008). Associations of indoor relative humidity, temperature and air exchange rate with formaldehyde concentrations have been reported in the literature (Gilbert et al. 2008;Jo and Sohn 2009;Wolkof and Kjaergaard 2007 (2007) reviewed the influence of relative humidity on perceived IAQ, pointing out the direct effect of this parameter on formaldehyde concentrations. Figure 5 depicts the daily profiles of formaldehyde concentrations in both copy centres. ...
This study presents continuous measurements of size-segregated particulate matter, total volatile organic compounds, ozone, formaldehyde, comfort parameters (temperature and relative humidity), CO and CO2 at two copy centres (A and B) in Aveiro, Portugal. PM10 samples collected with low-volume samplers were used to determine the carbonaceous content (organic and elemental carbon) by a thermo-optical technique. Mean PM10 levels of 55.8 ± 7.50 μg m−3 and 51.3 ± 9.35 μg m−3 were obtained in copy centres A and B, respectively. The 24-h indoor PM10 concentration at both copy centres exceeded the protection limit established by the Portuguese legislation. Around 60 % of the PM10 were composed of particles with sizes below 2.5 μm. On average, organic carbon accounted for 27.6 % (copy centre A) and 18.6 % (copy centre B) of the PM10 mass indoors, whereas a lower mass fraction of 11.5 % was found for both outdoor spaces. The much higher indoor levels of organic carbon suggest significant contribution by indoor sources. The ozone level increased in both copy centres when the photocopiers started to work. Mean ozone levels (0.055 ± 0.005 and 0.048 ± 0.006 ppm in copy centres A and B, respectively) during business hours may exceed the standard recommended for workplaces (0.05 ppm), representing a cause of possible adverse health effects on employees. The indoor-to-outdoor ozone concentration ratios were greater than 1 in both centres, indicating an important contribution of indoor sources. Formaldehyde levels remained always below the World Health Organisation guideline for indoor air (0.1 mg m−3). Total concentrations of volatile organic compounds were also relatively low, in general ranging from around 190 to 300 ppb. The indoor-to-outdoor concentration ratios were in the range between 0.70 and 0.76. Results showed that operation of laser printers can lead to high particulate matter and ozone concentration indoors. Pollutants associated with printing equipment have potential to cause adverse health effects if exposures are sufficiently high. Precautions should be taken to minimise the risks of exposed workers.
Formaldehyde (FA) is a ubiquitous indoor air pollutant emitted from construction, consumer, and combustion-related products, and ozone-initiated reactions with reactive organic volatiles. The derivation of an indoor air quality guideline for FA by World Health Organization in 2010 did not find convincing evidence for bronchoconstriction-related reactions as detrimental lung function. Causal relationship between FA and asthma has since been advocated in meta-analyses of selected observational studies. In this review, findings from controlled human and animal exposure studies of the airways, data of FA retention in the respiratory tract, and observational studies of reported asthma applied in meta-analyses are analyzed together for coherence of direct association between FA and asthma. New information from both human and animal exposure studies are evaluated together with existing literature and assessed across findings from observational studies and associated meta-analyses thereof. Retention of FA in the upper airways is > 90% in agreement with mice exposure studies that only extreme FA concentrations can surpass trachea, travel to the lower airways, and cause mild bronchoconstriction. However, taken together, detrimental lung function effects in controlled human exposure studies have not been observed, even at FA concentrations up 4 ppm (5 mg/m³), and in agreement with controlled mice exposure studies. Typical indoor FA concentrations in public buildings and homes are far below a threshold for sensory irritation in the upper airways, based on controlled human exposure studies, to induce sensory-irritative sensitization nor inflammatory epithelial damage in the airways. Analysis of the observational heterogeneous studies applied in the meta-analyses suffers from several concomitant multifactorial co-exposures, which invalidates a direct association with asthma, thus the outcome of meta-analyses. The evidence of a direct causal relationship between FA and asthma is insufficient from an experimental viewpoint that includes retention data in the upper airways and controlled animal and human exposure studies. Taken together, a coherence of controlled experimental findings with individual observational studies and associated meta-analyses, which suffer from caveats, is absent. Further, lack of identified evidence of FA-IgE sensitization in both experimental studies and observational studies agrees with indoor FA concentrations far below threshold for sensory irritation. The assessment of experimental data with uncontrolled observational studies in meta-analyses is incompatible with a direct causal relationship between FA and asthma or exacerbation thereof due to lack of coherence and plausibility.
In the current highly industrialized living environment, air quality has become an increasing public health concern. Natural environments like forests have excellent air quality due to high concentrations of negative oxygen ions originating from low-voltage ionization, without harmful ozone. Traditional negative oxygen ion generators require high voltage for corona discharge to produce ions. However, high voltage can increase electron collisions and excitations, leading to more dissociation and recombination of oxygen molecules and consequently higher ozone production. To address the challenge of generating negative oxygen ions without accompanying ozone production, this study designed and constructed a low-voltage negative oxygen ion generator based on nanometer-tip carbon fiber electrodes. The advantage of this device lies in the high curvature radius of carbon fibers, which provides high local electric field strength. This allows for efficient production of negative oxygen ions at low operating voltages without generating ozone. Experiments demonstrated that the device can efficiently generate negative oxygen ions at a working voltage as low as 2.16 kV, 28% lower than the lowest voltage reported in similar studies. The purification device manufactured in this study had a total decay constant for PM2.5 purification of 0.8967 min⁻¹ within five minutes, compared to a natural decay constant of only 0.0438 min⁻¹, resulting in a calculated Clean Air Delivery Rate (CADR) of 0.1535 m³/min. Within half an hour, concentrations of PM2.5, PM1, PM10, formaldehyde, and TVOC were reduced by 99.09%, 99.40%, 99.37%, 94.39%, and 99.35%, respectively, demonstrating good decay constants and CADR. These findings confirm its effectiveness in improving indoor air quality, highlighting its significant application value in air purification.
Food additives have been used in food processing from time immemorial. Their applications in food are used to enhance certain qualities such as appearance, texture, flavour or extend the shelf life of foods as food preservation. Food preservatives have wide applications in food industry due to their ability to extend shelf life and hence boost food processors" income. In view of the advantages, there are enormous food preservatives in the market which have been used appropriately by food handlers while some have abused their uses by going out of the regulated acceptable dose or using the prohibited one. Among the preservatives that have been unscrupulously used is formaldehyde. This study, therefore, appraises the current use of formaldehyde, its health implications, and possible way out for its safe applications. Formaldehyde is a simple chemical compound derived from hydrogen, oxygen and carbon. Formaldehyde naturally occurs in varieties of food items, such as fruits, meats, fish, crustaceans and dried mushrooms. It has antimicrobial and antioxidant properties that can retard spoilage, uphold product quality and safety as well as extends the storage shelf life. Hence, it is permissible exclusively as additives in some sea foods such as fish, crayfish. The use of synthetic form: aldehyde, in food processing and storage must be under regulations to ensure the safety of consumers and end users of the product.
This study evaluated how acid treatment affects the ability of customized beads of activated carbon (BAC) to remove formaldehyde from air. Two different acids (hydrofluoric acid and sulfuric acid) were used to modify the surface of BAC prepared from a polymer material. The acid-modified BACs were further subjected to heat treatment. Physical and chemical characteristics of modified and unmodified BACs were investigated using nitrogen adsorption, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy. Formaldehyde removal was evaluated under both dry and moist conditions. From the results, acid treatment clearly improved the adsorption performance, especially under the moist condition. Qualitative and quantitative surface analyses were conducted, mainly to examine the amount of O-bonds after acid treatment and the formation of S–O or Cl–O on BAC.
Amaç: Mersin ili patoloji laboratuvarları çalışanlarında formaldehit maruziyeti ile bellek bozukluğu arasındaki ilişkinin değerlendirilmesi amaçlandı. Yöntem: Kesitsel tipteki bu çalışmanın verileri Mayıs-Eylül 2016 aylarında toplandı. Araştırmanın evrenini oluşturan altı kamu ve bir özel patoloji laboratuvarı çalışanlarının tamamı (n= 98) çalışmaya alındı. Formaldehit ortam ölçümü, yaka kartı ölçüm yöntemi ile belirlendi. Öğrenme ve bellek durumu ise işitsel sözel öğrenme testi kullanılarak değerlendirildi. İstatistiksel değerlendirmede, tanımlayıcı istatistikler, Kolmogorov-Smirnov testi, Mann Whitney U testi, Spearman ve Pearson Korelasyon analizi kullanıldı. Bulgular: Katılımcıların yaş ortalaması 40.06±9.09 yıl ve %63.3’ü kadındı. Çalışanların formaldehit ölçüm sonucu ortancası 0.030 ppm (0.004-4.400) idi. Formaldehit ölçüm sonuçları lokal havalandırması olanlarda, genel havalandırması olanlarda ve kamuda çalışanlarda daha düşüktü. Çalışanların öğrenme, kısa süreli bellek ve uzun süreli bellek puanları ile toplam formaldehit ölçüm sonucu, formaldehit maruz kalma süresi ve formaldehit maruziyet indeksi arasında korelasyon olmadığı belirlendi. Meslek grupları ayrı ayrı değerlendirildiğinde, patologların ve laboratuvar teknikerlerinin toplam formaldehit maruz kalma miktarı ile öğrenme puanları arasında negatif yönlü bir korelasyon olduğu belirlendi (r=-0.484, p= 0.009, r=-0.299, p= 0.049). Sonuç: Bu çalışmada patologlar ve laboratuvar teknikerlerinde formaldehit maruziyeti arttıkça öğrenmenin bozulduğu belirlenmiştir.
Formaldehyde is a known carcinogen and a major indoor air pollutant, which has led the authorities to regulate its levels in the air. To reduce indoor airborne concentrations, several strategies can be adopted, namely the reduction of emissions or the elimination of this pollutant by different depollution processes. Among them, adsorption on highly porous solid materials remains one of the most efficient strategy.
This study aims to provide experimental data on formaldehyde adsorption capacity over different microporous materials at realistic levels (∼164 ppb), being representative of the performance of the investigated materials in a real environment. For that purpose, gaseous formaldehyde breakthrough experiments were performed under laboratory-controlled conditions over several porous solids: focusing on cation-exchanged zeolites and metal-organic frameworks (MOFs). These materials were fully characterized in terms of textural and structural properties.
Cu-based MOFs acted as more promising HCHO adsorbents than zeolites, exhibiting at least one order of magnitude higher adsorption capacity under realistic indoor conditions. Among MOFs, SUM-102 (Strasbourg University Material) exhibited the highest surfacic adsorption capacity (0.52 μg HCHO m⁻²), yielding more than 1 kg HCHO adsorbed per m³sorbent being superior to the zeolite family by at least one order of magnitude.
The emissions of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) from indoor building and vehicle cabin materials can adversely affect human health. Many mechanistic models to predict the VOC/SVOC emission characteristics have been proposed. Nowadays, the main obstacle to accurate model prediction is the availability and reliability of the physical parameters used in the model, such as the initial emittable concentration, the diffusion coefficient, the partition coefficient, and the gas-phase SVOC concentration adjacent to the material surface. The purpose of this work is to review the existing methods for measuring the key parameters of VOCs/SVOCs from materials in both indoor and vehicular environments. The pros and cons of these methods are analyzed, and the available datasets found in the literature are summarized. Some methods can determine one single key parameter, while other methods can determine two or three key parameters simultaneously. The impacts of multiple factors (temperature, relative humidity, loading ratio, air change rate) on VOC/SVOC emission behaviors are discussed. The existing measurement methods span very large spatial and time scales: the spatial scale varies from micro to macro dimensions; and the time scale in chamber tests varies from several hours to one month for VOCs, and may even span years for SVOCs. Based on the key parameters, a pre-assessment approach for indoor and vehicular air quality is introduced in this review. The approach uses the key parameters for different material combinations to pre-assess the VOC/SVOC concentrations or human exposure levels during the design stage of buildings or vehicles, which can assist designers to select appropriate materials and achieve effective source control.
Comprehensive aircraft measurements of volatile organic compounds (VOCs) covering the South Coast Air Basin (SoCAB) and San Joaquin Valley (SJV) of California were obtained in the summer of 2019. Combined with the CO, CH4, and NOx data, the total measured gas-phase hydroxyl radical reactivity (OHRTOTAL) was quantified. VOCs accounted for ~60 %−70 % of the OHRTOTAL in both basins. In particular, oxygenated VOCs (OVOCs) contributed > 60 % of the OHR of total VOCs (OHRVOC) as well as the total observed VOC mixing ratio. Primary biogenic VOCs (BVOCs) represented a minor fraction (< 2 %) of the total VOC mixing ratio but accounted for 21 % and 6 % of the OHRVOC in the SoCAB and SJV, respectively. Furthermore, the contribution of BVOCs to the OHRVOC increased with increasing OHRVOC in the SoCAB, suggesting that BVOCs was important ozone precursors during high ozone episodes. Spatially, the trace gases were heterogeneously distributed in the SoCAB with their mixing ratios and OHR significantly greater over the inland regions than the coast, while their levels were more evenly distributed in the SJV. The results highlight that a better grasp of the emission rates and sources of OVOCs and BVOCs is essential for a predictive understanding of the ozone abundance and distribution in California.
Formaldehyde (HCHO) is one of the most infamous indoor pollutants that imposes a great threat to human health. Herein, we report the development of a high-performance Pt/Fe2O3 catalyst for HCHO oxidation employing a facet- and defect-engineering strategy, with special focus on the surface structure effect of α-Fe2O3 on the catalytic properties. A supported Pt nanocatalyst on hollow octadecahedral α-Fe2O3 with exclusively exposed {113} and {104} facets was prepared using a hydrothermal method followed by impregnation-reduction treatment. The high-index facets of α-Fe2O3 render the formation of abundant oxygen vacancies and an improved dispersion of Pt nanoparticles. This led to an increased Pt/O-vacancy coexistence in close proximity, which collaboratively promote the generation of active oxygen and surface OH species. As a consequence, the Pt/Fe2O3-HO catalyst exhibited impressively high and stable activity towards HCHO oxidation at room temperature, which was five-fold higher than that of the supported Pt catalyst on commercial α-Fe2O3.
Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants.
Whole house emission rates and indoor loss coefficients of formaldehyde and other volatile organic compounds (VOCs) were determined from continuous measurements inside a net-zero energy home at two different air change rates (ACH). By turning on and off the mechanical ventilation, it was demonstrated that formaldehyde concentrations reach steady-state much more quickly than other VOCs, consistent with a significant indoor loss rate attributed to surface uptake. The first-order loss coefficient for formaldehyde was 0.47 ± 0.06 hr-1 at 0.08 hr-1 ACH and 0.88 ± 0.22 hr-1 at 0.62 hr-1 ACH. Loss rates for other VOCs measured were not discernible with the exception of hexanoic acid. A factor of 5.5 increase in ACH increased the whole house emission rates of VOCs but by varying degrees (factors of 1.1 to 3.8), with formaldehyde displaying no significant change. The formaldehyde area specific emission rate (86 ± 8 μg m-2 hr-1) was insensitive to changes in ACH because its large indoor loss rate muted the impact of ventilation on indoor air concentrations. These results demonstrate that formaldehyde loss rates must be taken into account to correctly estimate whole house emission rates and that ventilation will not be as effective at reducing indoor formaldehyde concentrations as it is for other VOCs.
High time resolution monitoring of formaldehyde and other volatile organic compounds in the air of four homes in winter and summer revealed diel variation of VOC levels driven by infiltration and temperature dependent whole house emission rates. In unoccupied homes, these pollutants displayed a large diel concentration variation, with an afternoon maxima and early morning minima. VOC abundance lagged about 2 h behind changes in infiltration rates measured by a tracer release method, resulting in poor correlations between VOC concentration and air change rate. The data demonstrate that VOC abundance was not in steady state with respect to whole house emission rates. Formaldehyde and other VOCs displayed a positive correlation with indoor temperature in both winter and summer. Formaldehyde sensitivity to temperature ranged from 3.0 to 4.5 ppbv per °C, a useful metric for predicting the impact of heat waves and changing regional climate on indoor air quality. Gypsum wallboard used as radiant ceiling heating product in one home was identified as source of formaldehyde and potentially mercury.
Indoor air quality matters in regard of health risks of indoor exposure to particulates. Small particulates indoor are 3–8 times higher than outdoor (Heimlich 2008). The air quality indoor suffers. Industrial products such as building materials, paints, furniture, textiles, flooring, and electronics are off-gazing and in general incorporate toxic ingredients. The environmental and human toxicology quality is a key factor for a healthy living environment. Health risks of indoor exposure to particulates matter in regard to quality of industrial produced products. Wood will certainly stay as one of the leading and the most preferable construction material in the future due to its environmental, local availability, and aesthetic characteristics. Nowadays, using wood in architecture is very fashionable. Research and developments in wood production as well as in wood construction will strongly form the future of sustainable development practically in all parts of the planet Earth. Wood today is trendy, fashionable, and one of the most accessible materials and has an aesthetic view with a natural look and a visual attractiveness, together with the smell, sound, and touch; natural wood is perceived as luxurious. Development could be seen also in façades, inside and other surfaces of modern structures which are increasingly being used. Sustainable luxury products incorporate extraordinary aesthetics, handle, care, function and in addition, to be sustainable need to be safe for humans, society, and the environment. Resources and natural resources are scare and need to be protected in changing the design of the products we use according Cradle to Cradle® principle ‘Remaking the way we make things’ and ‘Towards a circular economy.’ For companies, this implies entrepreneurship to tackle the large impact in change of behavior, culture, marketing and business models in closing the loop, and taking the goods back from the user. The case study, Cradle to Cradle® (McDonough and Braungart 2002)—Parquet for Generations (Bauwerk Parkett 2017)—Respect Resources and Preservation for the Future, illustrates a successful lighthouse example from industry.
This paper presents the development of a novel colorimetric analytical method based on microfluidic technologies for the detection of airborne methanal concentrations requested by future recommendation in France. The working principle is based on two distinct steps : methanal uptake and reaction in an annular flow on the one hand and colorimetric (or fluorimetric) detection with liquid core waveguide on the other hand.
The uptake yield of gaseous methanal in aqueous solution is around 90% and the detection limit in gas phase is about 1.5 μg·m-3. These results are very promising and could still be improved in the near future.
During March 2013–December 2014, we conducted a field study in Shanghai, China. A total of 409 children's bedrooms had valid data for formaldehyde which was continuously measured for 24 h. The daily 24 h-averaged and night 6 h-averaged (00:00–06:00) concentrations were 21.5 μg/m3 and 22.2 μg/m3, respectively. Bedrooms with mechanical ventilation had lower formaldehyde concentrations than those with natural ventilation. In the multiple logistic regression analyses, compared to children in the first quartile of 24 h-averaged formaldehyde, children in fourth quartile had significantly lower odds of lifetime-ever food allergy (adjusted odds ratio (OR), 95% confidence interval (CI): 0.39, 0.16–0.97) and current rhinitis (0.39, 0.18–0.86), but children in the third quartile had significantly higher odd of current common cold (≥3 times) (2.42, 1.02–5.77). Among autumn-inspected children, formaldehyde exposure had significant associations with current common cold (≥3 times) (adjusted OR, 95%CI for 24 h-averaged: 4.88, 1.18–20.21 in increment of 11.7 μg/m3; for 6 h-averaged: 4.41, 1.07–18.19 in increment of 15.7 μg/m3). Significantly more families with case children used household mechanical ventilation and air cleaner than families with control children. Our results indicate that household formaldehyde exposure may increase the risk of childhood common cold. Since it is impossible that formaldehyde exposure in higher concentrations could decrease the risk of current rhinitis and other illnesses, we infer that those “negative” associations could be confounded by the potential behaviour changes for avoidance of household formaldehyde exposure among families with case children.
Using miniature perfluorocarbon tracer (PFT) sources and miniature passive samplers, both about the size of a cigarette, tests conducted in the laboratory and in a typical home successfully demonstrated the utility of the PFT kit as a means for implementing wide-scale infiltration measurements in homes. The PFT diffusion plug source, an elastomer containing a dissolved perfluorocarbon compound, was shown to emit vapors at the rate of about 0.1 to 5 nL/min, providing steady-state concentrations in a home of about 1 to 10 pL/L, i.e., parts per trillion by volume, when one source is deployed for each 300–500 ft2 (28–46 m2) of living space. The emission rate from the diffusion source was predictable, but its dependence on both temperature and time suggested the development of alternative approaches. One such alternative, a liquid PFT permeation source, had emission rates which could be tailored over the range 10–20 nL/min, were independent of age for as long as the liquid remained (∼ 5 yr), and had significantly lower temperature dependence. A number of passive adsorption tube samplers performed reproducibly and identically (to within ±2%–3%) in laboratory tests. Together with a programmable tracer sampler, the miniature diffusion sources and samplers were deployed in a typical home; six PFT sources were uniformly deployed, three on each level of a two-story house. Multiple location sampling, as well as sampling in rooms with and without a miniature source, demonstrated that even in a house without forced-air circulation, a well-mixed modeling approach is justified. Analyses of the tracer samplers were performed back in the laboratory with an automatic electron-capture gas-chromatography system. The effects of the inside/outside temperature differential, as well as that of an open fireplace compared with a wood-burning stove, on the measured air infiltration rates were clearly demonstrated. Comparisons of the PFT tracer method with that of the SF6 tracer decay approach showed the results of the two methods to be identical within experimental precision. With this miniature source and sampling tracer kit, infiltration rates in the range 0.2–5 air changes per hour can be measured over time-averaged periods of as little as 1 day up to several years.
Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.
Traditionally, houses in the US have been ventilated by passive infiltration in combination with active window opening. However in recent years, the construction quality of residential building envelopes has been improved to reduce infiltration, and the use of windows for ventilation also may have decreased due to a number of factors. Thus, there has been increased interest in engineered ventilation systems for residences. The amount of ventilation provided by an engineered system should be set to protect occupants from unhealthy or objectionable exposures to indoor pollutants, while minimizing energy costs for conditioning incoming air. Determining the correct ventilation rate is a complex task, as there are numerous pollutants of potential concern, each having poorly characterized emission rates, and poorly defined acceptable levels of exposure. One ubiquitous pollutant in residences is formaldehyde. The sources of formaldehyde in new houses are reasonably understood, and there is a large body of literature on human health effects. This report examines the use of formaldehyde as a means of determining ventilation rates and uses existing data on emission rates of formaldehyde in new houses to derive recommended levels. Based on current, widely accepted concentration guidelines for formaldehyde, the minimum and guideline ventilation rates for most new houses are 0.28 and 0.5 air changes per hour, respectively.
Three commercially available conversion varnish coating “systems” (stain, sealer, and topcoat) were selected for an initial scoping study. The total volatile content of the catalyzed varnishes, as determined by U.S. Environmental Protection Agency (EPA) Method 24, ranged from 64 to 73 weight%. Uncombined (free) formaldehyde concentrations, determined by a sodium sulfite titration method, ranged from 0.15 to 0.58 weight% of the uncatalyzed varnishes. Each sealer and topcoat was also analyzed by gas chromatography (EPA Method 311). The primary volatile organic constituents included methyl ethyl ketone (MEK), isobutanol, n-butanol, methyl isobutyl ketone (MIBK), toluene, ethylbenzene, the xylenes, and 1,2,4-trimethylbenzene.
Formaldehyde (HCHO) is a toxic air contaminant released indoors from pressed-wood materials and numerous consumer products. Formaldehyde emission data are needed for modeling of indoor personal exposures, health risks, and risk reduction measures. This study determined HCHO emission rates from 55 diverse materials and consumer products under two realistic chamber test conditions, using both time-integrated and continuous real-time measurements. Among dry products, relatively high emissions were found from bare pressed-wood materials made with urea-formaldehyde (UF) resins, and from new (unwashed) permanent press fabrics. UF materials with paper, vinyl, laminate, and other coatings showed HCHO emissions lower by about a factor of 10 than those from bare UF materials. Among wet products, an acid-cured floor finish showed the highest HCHO emissions, greatly exceeding those of any dry product even 24 h after application. Fingernail polish and hardener showed relatively high emission rates, and latex paint and wallpaper relatively low emission rates, but these products emit similar amounts of HCHO because of widely different surface areas of application. Acid-cured finishes, and personal activity patterns and exposures during application of wet products, are key areas for further study.
The results of measurements of indoor air formaldehyde concentrations in occupational and private residences are presented for the period 1986 to 1993, based on requests of persons who complained about irritations. In many cases, climatic parameters such as the air exchange rate, temperature and relative humidity were also monitored. Calculated mean values for temperature and humidity were 22°C and 45% respectively. The average air exchange rate was 0.36 h−1, which is well below a recommended guideline value of 0.8 h˜' and it was evident that the ventilation is clearly insufficient in many rooms. The average formaldehyde concentration was 119 μg/m −3 (252 data), which is only slightly below the German guideline value of 125 μg/m −3. In 31% of the cases this guideline was exceeded. As expected, a clear relation between formaldehyde concentrations and the air exchange rate was found. The highest levels result at AE≤0.8 h−1, but only a single value exceeds 125 μg/m −3 at AE≥0.8 h−1. The association of law ventilation rates with high formaldehyde levels is also evident from a comparison with theoretical data after normalization to AE=0.8 h−1, using the Hoetjer-equation. It was also observed that the calculated annual mean concentrations decreased from 1986 to 1993.
Conversion varnishes are two-component, acid-catalyzed varnishes that are commonly used to finish cabinets. They are valued for their water and stain resistance, as well as their appearance. They have been found, however, to contribute to indoor emissions of organic compounds. For this project, three commercially available conversion varnish systems were selected. A U.S. Environmental Protection Agency (EPA) Method 24 analysis was performed to determine total volatile content, and a sodium sulfite titration method was used to determine uncombined (free) formaldehyde content of the varnish components. The resin component was also analyzed by gas chromatography/mass spectroscopy (GC/MS) (EPA Method 311 with an MS detector) to identify individual organic compounds. Dynamic small chamber tests were then performed to identify and quantify emissions following application to coupons of typical kitchen cabinet wood substrates, during both curing and aging. Because conversion varnishes cure by chemical reaction, the compounds emitted during curing and aging are not necessarily the same as those in the formulation. Results of small chamber tests showed that the amount of formaldehyde emitted from these coatings was 2.3-8.1 times the amount of free formaldehyde applied in the coatings. A long-term test showed a formaldehyde emission rate of 0.17 mg/m2/hr after 115 days.
Four commercially available low-volatile organic compound (VOC) latex paints were evaluated as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that the VOC contents of all four paints tested were considerably lower than those of conventional latex paints. Low VOC emissions were confirmed by small chamber emission tests. However, significant emissions of several aldehydes, especially formaldehyde which is a hazardous air pollutant, were detected in emissions from two of the four paints. American Society for Testing and Materials (ASTM) methods were used to evaluate the hiding power, scrub resistance, washability, dry to touch and yellowness index. The results indicated that one of the four low-VOC paints tested showed performance equivalent or superior to that of a conventional latex paint used as control. It was concluded that low-VOC latex paint can be a viable option to replace conventional latex paints for prevention of indoor air pollution. However, paints marketed as "low-VOC" may still have significant emissions of some individual VOCs, and some may not have performance characteristics matching those of conventional latex paints.
This study was undertaken to determine the concentrations of formaldehyde, acetaldehyde, and acrolein in air samples taken in some Canadian houses and to determine the association between aldehyde levels and housing characteristics. Concentrations of formaldehyde, acetaldehyde, and acrolein were measured in 59 homes in Prince Edward Island, Canada, during the winter of 2002. Housing characteristics were documented through inspection and by interviews of occupants. Formaldehyde, acetaldehyde, and acrolein concentrations ranged from 5.5 to 87.5 microg/m(3) (median, 29.6 microg/m(3)), from 4.4 to 79.1 microg/m(3) (median, 18.9 microg/m(3)), and from 0.1 to 4.9 microg/m(3) (median, 0.9 microg/m(3)), respectively. Formaldehyde levels were elevated in homes built after 1970. Acetaldehyde and acrolein levels were elevated in homes inhabited by at least one smoker and in homes built 1970--1985 and were correlated with absolute humidity and carbon dioxide, two variables likely to be surrogates for lower air exchange rates. In conclusion, lower air exchange rates appear to be important determinants of formaldehyde, acetaldehyde, and acrolein levels in homes. These data also confirm that smoking is a significant source of acetaldehyde and acrolein and indoor air.
Unlabelled:
Indoor air organic compounds were continuously monitored during 3 years in new and older homes which were voluntarily selected throughout countries. The levels of volatile organic compounds (VOCs) in the new homes decreased markedly after 1 year, and steady emissions of VOCs were obtained in the initial months. Formaldehyde and a-pinene related to wooden materials need a longer flushing period than the other compounds in the new homes. The levels of the indoor air organic compounds in the older homes showed no significant fluctuation during the 3-year period. Decreases of the indoor-produced compounds in the new homes did not depend upon the ventilation systems. The results indicate that the indoor-produced compounds in the new homes will be more influenced by the aging decreases of emission source strengths than ventilation systems. The quantitative information on the trend of the indoor air organic compound levels will be useful for the risk assessment of indoor exposure to those compounds, and also for Japanese IAQ guidelines.
Practical implications:
The initial levels of VOCs in the new homes decreased dramatically and were close to the mean values for the older homes after one year. The results suggest that steady emissions of VOCs are obtained within initial months. However, formaldehyde and a-pinene did not follow the trend for VOCs, particularly in the wooden framed houses. The results tend to suggest that formaldehyde and a-pinene related to wooden materials will need more long a flushing period than other compounds in the new homes. Decreasing tendency of indoor air organic compound levels in the new homes did not appear to show any dependency upon the ventilation systems over the whole period. Absence of data for ventilation rates in the houses dose not permit interpretation of the relation between ventilation rates and indoor air organic compound levels with statistical certainty, but the results suggest that indoor air organic compound levels in the homes will be more influenced by emission source strengths than ventilation systems. The levels of indoor air organic compounds in the new homes are sufficiently decreased according to the ageing decreases of organic compounds when the home is ventilated with adequate quantities.
Concentrations of nitrogen dioxide and formaldehyde were determined in a study of 96 homes in Quebec City, Canada, between January and April 2005. In addition, relative humidity, temperature, and air change rates were measured in homes, and housing characteristics were documented through a questionnaire to occupants. Half of the homes had ventilation rates below 7.5 L/s person. Nitrogen dioxide (NO2) and formaldehyde concentrations ranged from 3.3 to 29.1 microg/m3 (geometric mean 8.3 microg/m3) and from 9.6 to 90.0 microg/m3 (geometric mean of 29.5 microg/m3), respectively. The housing characteristics documented in the study explained approximately half of the variance of NO2 and formaldehyde. NO2 concentrations in homes were positively correlated with air change rates (indicating a significant contribution of outdoor sources to indoor levels) and were significantly elevated in homes equipped with gas stoves and, to a lesser extent, in homes with gas heating systems. Formaldehyde concentrations were negatively correlated with air change rates and were significantly elevated in homes heated by electrical systems, in those with new wooden or melamine furniture purchased in the previous 12 months, and in those where painting or varnishing had been done in the sampled room in the previous 12 months. Results did not indicate any significant contribution of indoor combustion sources, including wood-burning appliances, to indoor levels of formaldehyde. These results suggest that formaldehyde concentrations in Quebec City homes are caused primarily by off-gassing, and that increasing air change rates in homes could reduce exposure to this compound. More generally, our findings confirm the influence of housing characteristics on indoor concentrations of NO2 and formaldehyde.
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