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IARC: DIESEL ENGINE EXHAUST CARCINOGENIC

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... Recently, the International Agency for Research on Cancer (IARC) reclassified DEE as "carcinogenic to humans (Group 1)" based on sufficient evidence that exposure is associated with an increased risk for lung cancer [7,8]. The decision was based on a US National Cancer Institute (NCI) and National Institute for Occupational Safety and Health (NIOSH) study that showed exposure-response relationships between respirable elemental carbon exposures and lung cancer mortality in underground miners [8,9]. ...
... The decision was based on a US National Cancer Institute (NCI) and National Institute for Occupational Safety and Health (NIOSH) study that showed exposure-response relationships between respirable elemental carbon exposures and lung cancer mortality in underground miners [8,9]. The IARC also noted a positive association (limited evidence) with an increased risk of bladder cancer (Group 1) [7]. ...
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The purposes of this study were to determine the following: 1) the exposure levels of municipal household waste (MHW) workers to diesel particulate matter (DPM) using elemental carbon (EC), organic carbon (OC), total carbon (TC), black carbon (BC), and fine particulate matter (PM 2.5) as indicators; 2) the correlations among the indicators; 3) the optimal indicator for DPM; and 4) factors that influence personal exposure to DPM. A total of 72 workers in five MHW collection companies were assessed over a period of 7 days from June to September 2014. Respirable EC/OC samples were quantified using the thermal optical transmittance method. BC and PM 2.5 were measured using real-time monitors, an aethalometer and a laser photometer. All results were statistically analyzed for occupational and environmental variables to identify the exposure determinants of DPM. The geometric mean of EC, OC, TC, BC and PM 2.5 concentrations were 4.8, 39.6, 44.8, 9.1 and 62.0 μg/m3, respectively. EC concentrations were significantly correlated with the concentrations of OC, TC and BC, but not with those of PM 2.5. The exposures of the MHW collectors to EC, OC, and TC were higher than those of the drivers (p<0.05). Workers of trucks meeting Euro 3 emission standard had higher exposures to EC, OC, TC and PM 2.5 than those working on Euro 4 trucks (p<0.05). Multiple regression analysis revealed that the job task, European engine emission standard, and average driving speed were the most influential factors in determining worker exposure. We assessed MHW workers' exposure to DPM using parallel sampling of five possible indicators. Of these five indicators, EC was shown to be the most useful indicator of DPM exposure for MHW workers, and the job task, European emission standard, and average driving speed were the main determinants of EC exposure.
... The study of particulate matter is of increasing interest to the scientific community (epidemiologists, researchers…) and to decision makers, in particular to determine the impact of this pollutant on human health123. It is thus important to conduct the monitoring of this pollutant especially in densely inhabited regions, in order to take adequate measures (e.g. ...
... Several epidemiological studies indicate that lung cancer and other health effects are possibly associated with atmospheric particles [2,91011121314. In this sense, in June 2012, the International Agency for Research on Cancer (IARC) classified diesel engine exhaust as carcinogenic to humans (Group 1), based on sufficient evidence that this exposure is associated with an increased risk for lung cancer [3]. Natural sources are also a major cause for atmospheric particles15161718 . ...
Article
PM10 was monitored during 2008-2011 period at LUT and BON, two urban tropical stations close to each other at Saint-Pierre city, in Reunion Island (southwestern Indian Ocean). During the study period, notable PM10 concentrations are observed at BON close to the coasts. At LUT, a more inland site, the daily PM10 concentration range between 13 and 70 µg/m 3. Importantly, the limit value for the protection of the human health is systematically exceeded at BON while it is never exceeded at LUT. Also, the quality objective (QO: 30 µg/m 3 , on annual average) and the limit value for the human health protection (LV: 40 µg/m 3 , on annual average) are exceeded at BON each year during 2008-2011, while at LUT no regulatory values are exceeded. Nitrogen dioxide, an atmospheric tracer of anthropogenic activities was also monitored at LUT and BON. The mean diurnal NO 2 variation is of the same level and order of magnitude and exhibits a similar pattern at both stations suggesting that distinct sources influence the PM10 at LUT and at BON. Chemical analysis was performed on daily filters sampled in September-November 2011 at the two stations to determine the sea salt contribution on PM10 across Saint-Pierre city. It showed that the sea salt contribution to the PM10 is 55% at BON in September 2011. The sea salt particles are therefore the main cause for the exceedances of the regulatory values of PM10 recorded at BON. The results importantly suggest that the notable PM10 concentrations measured at this urban marine site might have some but minor impact on human health.
... Diesel engine exhaust (DEE) was classified as carcinogenic to humans (group 1) by the International Agency for Research on Cancer (IARC) in 2012. 1 The IARC also noted that large populations all over the world are exposed to DEE in daily life, either through their occupation or from ambient air. To date, evidence supporting the relationship between DEE exposure and lung cancer risk has been from studies on occupational-exposed workers, including miners, those working on the railroad, in docks and on tunnel construction, and professional drivers, etc. [2][3][4][5] In addition to the occupational exposure aforementioned, diesel engine testing workers in engine manufacturing factories are specifically exposed to high levels of DEE during working hours. ...
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Objectives: Diesel engine exhaust (DEE) is a ubiquitous environmental pollutant and is carcinogenic to humans. To seek early and sensitive biomarkers for prediction of adverse health effects, we analysed the components of DEE particles, and examined the genetic and oxidative damages in DEE-exposed workers. Methods: 101 male diesel engine testing workers who were constantly exposed to DEE and 106 matched controls were enrolled in the present study. The components of DEE were analysed, including fine particulate matter (PM2.5), element carbon (EC), nitrogen dioxide (NO2), sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs). Postshift urine samples were collected and analysed for 1-hydroxypyrene (1-OHP), an internal exposure marker for DEE. Levels of DNA strand breaks and oxidised purines, defined as formamidopyrimidine-DNA glycosylase (FPG) sites in leucocytes, were measured by medium throughput Comet assay. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was also used to determine the level of oxidative stress. Results: We found higher levels of PM2.5, EC, NO2, SO2 and PAHs in the diesel engine testing workshop and significantly higher urinary 1-OHP concentrations in exposed subjects (p<0.001). Compared with controls, the levels of parameters in normal Comet and FPG-Comet assay were all significantly higher in DEE-exposed workers (p<0.001), and in a dose-dependent and time-dependent manner. There were no significant differences between DEE-exposed workers and controls in regard to leucocyte FPG sensitive sites and urinary 8-OHdG levels. Conclusions: These findings suggest that DEE exposure mainly induces DNA damage, which might be used as an early biomarker for risk assessment of DEE exposure.
... The workers' calculated dose of NDs during the measurement day was 74 ng which is approximately 500 times smaller than the daily dose of submicrometer urban background particles. Recently, the International Agency for Research on Cancer (IARC) classified diesel engine exhaust particles [70] and outdoor air pollution [71] as carcinogenic to humans (Group 1). NDs have not been classified for carcinogenicity but they have been assumed to be less toxic than other carbon particles [72,73]. ...
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This study considers fundamental methods in occupational risk assessment of exposure to airborne engineered nanomaterials. We discuss characterization of particle emissions, exposure assessment, hazard assessment with in vitro studies, and risk range characterization using calculated inhaled doses and dose-response translated to humans from in vitro studies. Here, the methods were utilized to assess workers' risk range of inhalation exposure to nanodiamonds (NDs) during handling and sieving of ND powder. NDs were agglomerated to over 500 nm particles, and mean exposure levels of different work tasks varied from 0.24 to 4.96 mu g.m(-3) (0.08 to 0.74 cm(-3)). In vitro-experiments suggested that ND exposure may cause a risk for activation of inflammatory cascade. However, risk range characterization based on in vitro dose-response was not performed because accurate assessment of delivered (settled) dose on the cells was not possible. Comparison of ND exposure with common pollutants revealed that ND exposure was below 5 mu g.m(-3), which is one of the proposed exposure limits for diesel particulate matter, and the workers' calculated dose of NDs during the measurement day was 74 ng which corresponded to 0.02% of the modeled daily (24 h) dose of submicrometer urban air particles.
... that exposure is associated with an increased risk for lung cancer." [60,61], and diesel exposures have been connected with various types of cancer among long-haul truckers, such as occupational bladder cancer, lung cancer, prostate cancer, stomach cancer, and ovarian cancer among female drivers [62][63][64][65]. Although these risks are undeniable [65], U.S. policy-makers persist on questioning causal connections between diesel exposure and cancer, as well as the relationship between work-related economic pressures and demonstrated and reported occupational safety and health outcomes. ...
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Long-haul truck drivers in North America function in a work context marked by excess physical and psychological workload, erratic schedules, disrupted sleep patterns, extreme time pressures, and these factors' far-reaching consequences. These work-induced stressors are connected with excess risk for cardiometabolic disease, certain cancers, and musculoskeletal and sleep disorders, as well as highway crashes, which in turn exert enormous financial burdens on trucking and warehousing companies, governments and healthcare systems, along with working people within the sector. This article: 1) delineates the unique work environment of long-haul truckers, describing their work characteristics and duties; (2) discusses the health hazards of long-haul trucking that impact drivers, the general population, and trucking enterprises, examining how this work context induces, sustains, and exacerbates these hazards; and (3) proposes comprehensive, multi-level strategies with potential to protect and promote the health, safety, and well-being of truckers, while reducing adverse consequences for companies and highway safety.
... Diesel exhaust emissions (DEE) are a mixture of gaseous and particulate substances originating from unburned fuel, lubricant oil and combustion products [1] . The main constituents of diesel particulate matter (DPM) are elemental carbon (EC) and organic carbon diseases [5] and DEE has recently been confirmed as carcinogenic [6] which is why the health of underground workers is of concern. PAHs are ubiquitous environmental pollutants, which may be present both in the gaseous phase and adsorbed onto the surface of particles. ...
Article
Concentrations of diesel particulate matter and polycyclic aromatic hydrocarbons (PAHs) in platinum mine environments are likely to be higher than in ambient air due to the use of diesel machinery in confined environments. Airborne PAHs may be present in gaseous or particle phases each of which has different human health impacts due to their ultimate fate in the body. Here we report on the simultaneous sampling of both phases of airborne PAHs for the first time in underground platinum mines in South Africa, which was made possible by employing small, portable denuder sampling devices consisting of two polydimethylsiloxane (PDMS) multi-channel traps connected in series separated by a quartz fibre filter, which only require small, battery operated portable personal sampling pumps for air sampling. Thermal desorption coupled with comprehensive gas chromatography–mass spectrometry (TD–GC × GC–TofMS) was used to analyse denuder samples taken in three different platinum mines. The samples from a range of underground environments revealed that PAHs were predominantly found in the gas phase with naphthalene and mono-methylated naphthalene derivatives being detected at the highest concentrations ranging from 0.01 to 18 μg m−3. The particle bound PAHs were found in the highest concentrations at the idling load haul dump vehicle exhausts with a dominance of fluoranthene and pyrene. Particle associated PAH concentrations ranged from 0.47 to 260 ng m−3 and included benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene. This work highlights the need to characterise both phases in order to assess occupational exposure to PAHs in this challenging sampling environment.
... This share has reached 37% in 2012 (as calculated inTable 3 ). The negative influence of exposure to emissions from diesel power generators on human health has been shown previously (see for example [36]), and diesel engine exhaust has recently been classified as carcinogenic to humans [37]. ...
... Some studies have reported a link between diesel exhaust and multiple myeloma [38], yet others are null [39]. While it is established that diesel exhaust contains nitro-PAHs, which are mutagenic and carcinogenic in in vitro tests [40][41][42], the mechanisms that underlie the associations between occupational exposures and multiple myeloma are unclear. ...
Article
We examined lifestyle, occupation, medical history and medication use with multiple myeloma risk in a case-spouse study (481 patients, 351 spouses). Odds ratios (ORs) and 95% confidence intervals (CI) were calculated using logistic regression. Compared to spouse controls, cases were more likely to have a family history of multiple myeloma (OR: 2.8,95% CI:1.2,6.4) and smoked cigarettes (OR:1.7,95%CI:1.2,2.5), but less likely to have consumed alcohol (OR:0.6,95%CI:0.4,0.9). Nurse/health practitioners (OR:2.8,95%CI:1.3,6.2) and production workers (OR:3.7,95%CI:1.0,13.7) had significantly increased risks; and some occupations linked to diesel exhaust had elevated, but non-significant, risks. History of herpes simplex (OR:1.7,95%CI:1.2,2.4), shingles (OR:1.7,95%CI:1.1,2.7), sexually transmitted diseases (OR:2.0,95%CI:1.0,3.7), and medication allergies (OR:1.7,95%CI:1.2,2.4) were associated with higher risks. Use of angiotensin-converting enzyme inhibitors, anti-convulsants, antidepressants, statins, and diuretics were associated with reduced risks. Our results are consistent with previous population-based studies, and support the utility of patient databanks and spouse controls as a resource in epidemiologic research.
... Meanwhile, BC has the characteristics of porosity and small particle size (Ding et al., 2016). It can adsorb volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and other carcinogens (Yuan et al., 2019;Bi et al., 2019;Cui et al., 2020), and then affect human health through respiration (Straif, 2012;Cai, 2013;Zhao, 2014;Kuang et al., 2015). BC was likely to be the main component of the lung toxicity in atmospheric particles (Rosa et al., 2014). ...
Article
Black carbon (BC), an important component of atmospheric aerosols, has a great influence on regional and global radiation balance, climate and human health due to its small particle size, large specific surface area and radiation forcing. The long-term variation of atmospheric BC over China during 1980 - 2019 was investigated through MERRA-2 reanalysis data. MERRA-2 BC generally presented a good correlation (average R = 0.61) with 852 monthly samples from ground-based observations at 64 stations around China. In recent 40 years, the annual-averaged atmospheric BC concentration derived from MERRA-2 reanalysis data was 1.10±0.22 μg/m³, with an average annual growth rate of 1.52%. The monthly BC concentrations showed a "U"-shaped trend. Based on the Mann-Kendall trend analysis, the BC concentration can be roughly divided into three stages: (1) the “low value” stage with slow growth rate (1.68%) (1980 - 1999, 0.91±0.10 μg/m³), (2) the fluctuating “median value” stage with high growth rate (4.44%) (2000 - 2007, 1.28±0.13 μg/m³), and (3) the “high value” stage with slow downtrend (-0.87%) (2008 - 2019, 1.32±0.06 μg/m³). Peak times and multi-year average growth rates of BC concentration and emission were not synchronized. The spatial distribution, dividing by the Hu Line, a line dividing the population density and urbanization of China, formed three BC high-value areas in Sichuan Basin, Northern Henan area and Beijing-Tianjin-Hebei (BTH). The altitude where the concentration of BC increased fastest at an average annual growth rate of 3.47% during 1980-2019 was between 0 and 500 m. The growth rate of BC concentration was close to zero as the altitude increased. During the past 40 years, significant overall uptrends were detected in MERRA-2 BC concentration with Mann-Kendall trend analysis at pixel scale, especially during 1980 - 1999 and 2000 - 2007. This increasing trend was more obvious in the eastern Hu Line. Whereas, a downward trend was appeared in the plains and basins of southeast China during 2008 - 2019.
... For instance, according to Boman and Thynell [2] the average travel time to work in Nairobi is estimated at about an h in traffic, but could have since gone up. Ambient air pollution is closely related to the health of people [6,7]. Air pollution too, has impacts on other aspects of the economy such as agriculture, and contributes to greenhouse gas emissions. ...
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This paper presents a statistical analysis of air quality monitoring in Nairobi city, at three major roads and Industrial Area, a site closer to the main industrial activities. The study was carried out using different gas analyzers and samplers. From the statistical analysis it was found that, there were extremely high values of black carbon which went beyond the upper limit of the instruments (50,000 ŋg/m3) during the day on Ladhis Road. Nakumatt Junction site recorded extreme values of Black carbon (14,008 ŋg/m3) in the evening hours, while at Pangani Roundabout site, the diurnal mean value was extreme (14,446.5 ŋg/m3) for the period. None of the four sites exceeded the WHO 24 h limit for both PM10 (50 μg/m3) and PM2.5 (25 μg/m3). The 24 h mean values of PM10 in the three sites also did not exceed the ambient air quality tolerance Kenyan limit of 100 μg/Nm3 and 150 μg/Nm3 in industrial area. The diurnal mean of SO2 over the four sites was generally low with the highest amount of 1.08 ppb recorded at Pangani Roundabout. This amount is far much below the diurnal WHO and Kenyan limit of 10 ppb and 48 ppb respectively. The global background concentration of carbon monoxide ranges between 0.05-0.12 ppm. The mean 24 h amount of CO in all the sites was above the background concentration, with Pangani Roundabout recording the highest amount of 1.73 ppm. The eight h means for ozone in all the sites were below WHO limit of 51 ppb with the highest amount of 20.2 ppb recorded in industrial area.
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Lung cancer is one of the most common malignancies in the world. Its incidence and mortality rates are on the rise in Pakistan. However, epidemiological studies to identify common lung cancer determinants in the Pakistani population have been limited. In this study, data of 440 cases and 323 controls were collected from different hospitals in Peshawar and Islamabad, along with information about socio-demographic factors including age, sex and smoking. Univariate and multi-factorial analyses of socio-demographic factors in association with each other were also performed. Overall survival analysis highlighted that, out of 440 patients in the lung cancer dataset, 204 people were uncensored with a median survival time of 13 months (95% CI
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The aim of the present study was to assess atypical changes in urothelial cells among petroleum station workers. This is a case control study, investigating 300 participants by cytological methods. Of the 300 participants, 150 were cases (exposed to petroleum products) and 150 were controls (non-exposed). Full voided urine was obtained and was cytologically assessed. Cytological atypia was identified in nine (6%) out of the 150 cases and could not be identified in 141/150 (94%) of the cases, whereas, in the control group, cytological atypia was recognized in four (2.7%) of the 150 controls and could not be identified in 146/150 (97.3%). The risk associated with petroleum product exposure, the odds ratio (OR), and 95% confidence interval (CI) was 2.33 (0.7015–7.7378), P = 0.1673. Exposure of petroleum station workers to petroleum products increases the risk of urothelial atypical changes, which may progress to precancerous and cancerous changes.
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In 2012, the World Health Organization’s International Agency for Research on Cancer (IARC) reclassified diesel engine exhaust and related ambient air pollution to be carcinogenic and associated with increased mortality from lung cancer. This could have critical consequences for both public and occupational health in enclosed railway stations where ventilation is often inadequate. Recent policies encouraging a shift to public transport, along with increasing passenger and train numbers, have led to a variety of co-benefits, including improved health and well-being from increased walking and cycling. This paper considers the unintended consequences of a reduction of air quality in crowded enclosed railway stations and concludes with a number of possible interventions to ensure that public health is not affected, especially by air pollution from stationary diesel trains. Pollution from electric trains can also lead to poor air quality due to the production of metal-rich ultrafine particles from brake linings, friction between wheel and rail, and from overhead panto graphs. Current occupational health standards are not suitable for enclosed railway stations and need to be reconsidered in the light of the IARC findings. More measurements of the levels of particulates and nitrogen dioxide in enclosed railway stations need to be undertaken and published.
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We sought to evaluate the air quality implications of rail traffic at two sites in Washington State. Our goals were to quantify the exposure to diesel particulate matter (DPM) and airborne coal dust from current trains for residents living near the rail lines and to measure the DPM and black carbon emission factors (EFs). We chose two sites in Washington State, one at a residence along the rail lines in the city of Seattle and one near the town of Lyle in the Columbia River Gorge (CRG). At each site, we made measurements of size-segregated particulate matter (PM1, PM2.5 and PM10), CO2 and meteorology, and used a motion-activated camera to capture video of each train for identification. We measured an average DPM EF of 0.94 g/kg diesel fuel, with an uncertainty of 20%, based on PM1 and CO2 measurements from more than 450 diesel trains. We found no significant difference in the average DPM EFs measured at the two sites. Open coal trains have a significantly higher concentration of particles greater than 1 μm diameter, likely coal dust. Measurements of black carbon (BC) at the CRG site show a strong correlation with PM1 and give an average BC/DPM ratio of 52% from diesel rail emissions. Our measurements of PM2.5 show that living close to the rail lines significantly increases PM2.5 exposure. For the one month of measurements at the Seattle site, the average PM2.5 concentration was 6.8 μg/m3 higher near the rail lines compared to the average from several background locations. Because the excess PM2.5 exposure for residents living near the rail lines is likely to be linearly related to the diesel rail traffic density, a 50% increase in rail traffic may put these residents over the new U.S. National Ambient Air Quality Standards, an annual average of 12 μg/m3.
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In 2012, the World Health Organization’s International Agency for Research on Cancer (IARC) reclassified diesel engine exhaust and related ambient air pollution to be carcinogenic and associated with increased mortality from lung cancer. This could have critical consequences for both public and occupational health in enclosed railway stations where ventilation is often inadequate. Recent policies encouraging a shift to public transport, along with increasing passenger and train numbers, have led to a variety of co-benefits, including improved health and well-being from increased walking and cycling. This paper considers the unintended consequences of a reduction of air quality in crowded enclosed railway stations and concludes with a number of possible interventions to ensure that public health is not affected, especially by air pollution from stationary diesel trains. Pollution from electric trains can also lead to poor air quality due to the production of metal-rich ultrafine particles from brake linings, friction between wheel and rail, and from overhead pantographs. Current occupational health standards are not suitable for enclosed railway stations and need to be reconsidered in the light of the IARC findings. More measurements of the levels of particulates and nitrogen dioxide in enclosed railway stations need to be undertaken and published.
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Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Recent high ambient concentration episodes of air pollutants in European cities highlighted the dynamic nature of human exposure and the gaps in data and knowledge about exposure patterns. In order to support health impact assessment it is essential to develop a better understanding of individual exposure pathways in people's everyday lives by taking account of all environments in which people spend time. Here we describe the development, validation and results of an exposure method applied in a study conducted in Scotland.
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In the urban environment, atmospheric aerosols consist mainly of pollutants from anthropogenic sources. The majority of these originate from traffic and other combustion processes. A fraction of these pollutants will penetrate indoors via ventilation. However, indoor air concentrations are usually predominated by indoor sources due to the small amount of dilution air. In modern societies, people spend most of their time indoors. Thus, their exposure is controlled mainly by indoor concentrations from indoor sources. During the last decades, engineering of nanosized structures has created a new field of material science. Some of these materials have been shown to be potentially toxic to human health. The greatest potential for exposure to engineered nanomaterials (ENMs) occurs in the workplace during production and handling of ENMs. In an exposure assessment, both gaseous and particulate matter pollutants need to be considered. The toxicities of the particles usually depend on the source and age. With time, particle morphology and composition changes due to their tendency to undergo coagulation, condensation and evaporation. The PM exposure risk is related to source specific emissions, and thus, in risk assessment one needs to define source specific exposures. This thesis describes methods for source specific risk assessment of airborne particulate matter. It consists of studies related to workers ENM exposures during the synthesis of nanoparticles, packing of agglomerated TiO2 nanoparticles, and handling of nanodiamonds. Background particles were distinguished from the ENM concentrations by using different measurement techniques and indoor aerosol modelings. Risk characterization was performed by using a source specific exposure and calculated dose levels in units of particle number and mass. The exposure risk was estimated by using non-health based occupational exposure limits for ENMs. For the nanosized TiO2, the risk was also assessed from dose-biological responses which had been extrapolated from inhalation studies conducted in mice. The ENM exposure levels were compared with background particle concentrations in order to determine the relevant ENM exposure metrics and exposure scenarios.
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Energy generation by fossil fuels produces significant amount of pollutants. Among the most toxic of them, there are SO2 and particulate matter. The first is a toxic gas that is subjected to severe regulations, the second is only partially regulated since the most toxic fractions of particles, i.e. the ultrafine particles, are nor easily measured neither properly captured by conventional technologies available at commercial level. Electrification of water sprays provide a reliable way to improve both the SO2 mass transfer rates and the particle capture efficiency, thanks to the multiple effects of electric charges imposed on the sprayed droplets. In this paper, we report experimental findings on the use of electrified sprays of water to reduce SO2 and particulate matter form a model flue gas. Tests were performed both laboratory and pilot scale. The experiments are compared with the performances of the same spray operated without electrification. In the pilot scale unit, particle removal efficiency is negligible and SO2 removal is up to 97% with the uncharged spray, The use of induction charging and exposure to corona pre-charging allow achieving >93% reduction of particulate matter and to >99% SO2 reductions. Experiments at laboratory scale shed light on the mechanisms of particle and SO2 capture. In particular, the experimental results revealed that a stochastic scavenging model presented in our former works (data not shown) well described the particle capture and that for charged droplets, the absorption rate for SO2 improved by about 60% respect to uncharged droplets
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Particle bound black carbon (BC) has dominant anthropogenic origins from fossil fuel combustion and biomass burning sources. It is an important component of the light absorbing aerosols in the atmosphere, playing a role in the earth's radiative balance and climate change. While the mixing states of the BC largely determine the coating on the particles, knowledge of the size distribution of BC is key to the accurate modelling of their absorption of solar radiation. Also, BC is a major component of the diesel PM emissions, recently classified by World Health Organization as Class I carcinogen, and has been widely documented with association of a variety of adverse health effects. Their sizes also determine the fraction of lung deposition. Due to the limited information of the mixing state and size distribution of BC, there still exists large uncertainty of the role of BC in climate change modelling. This study presents a novel approach of the direct and continuous measurement of atmospheric BC size distribution and coating by tandem operation of a differential mobility analyzer and a modified aethalometer. A condensation particle counter was deployed concurrently with the aethalometer to determine the particle number size distribution. Particle coating on BC was further estimated. A wide range of particle sizes (15-700nm) was investigated to determine the BC mass size distribution in fresh diesel engine tailpipe emissions and different ambient environments including urban and roadside. The results showed the evolution of BC mixing state and size distribution from fresh engine emissions to the roadside and urban ambient environments. The results provide important references for climate modelling to better determine the effect of radiative forcing from urban aerosols.
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Context: Titanium dioxide (TiO₂) factory workers' source specific exposure and dose to airborne particles was studied extensively for particles between 5 nm and 10 μm in size. Objective: We defined TiO₂ industry workers' quantitative inhalation exposure levels during the packing of pigment TiO₂ (pTiO₂) and nanoscale TiO₂ (nTiO₂) material from concentrations measured at work area. Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A lung deposit model was used to calculate regional inhalation dose rates in units of particles min⁻¹ and μg min⁻¹ without use of respirators. Results: Workers' average exposure varied from 225 to 700 μg m⁻³ and from 1.15 × 10⁴ to 20.1 × 10⁴ cm⁻⁴. Over 90% of the particles were smaller than 100 nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO₂ and nTiO₂ agglomerates. The nTiO₂ exposure resulted in a calculated dose rate of 3.6 × 10⁶ min⁻¹ and 32 μg min⁻¹ where 70% of the particles and 85% of the mass was deposited in head airways. Conclusions: The recommended TiO₂ exposure limits in mass by NIOSH and in particle number by IFA were not exceeded. We recommend source-specific exposure assessment in order to evaluate the workers' risks. In nTiO₂ packing, mass concentration best describes the workers' exposure to nTiO₂ agglomerates. Minute dose rates enable the simulation of workers' risks in different exposure scenarios.
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