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Over the last two decades, substantial studies have been conducted to assess the feasibility of a multi-pollutant strategy for managing air quality in the United States. Given the inherent complexity of multi-pollutant air quality challenges, including fine particulate matter (PM2.5), ozone (O3), and air toxics, this paper undertook a multi-pollutant analysis at both national and local levels. Our analysis incorporated O3 and PM2.5 concentrations, air toxics that increase the risk of cancer, environmental justice (EJ) data, emissions data, and monitoring data. Initially, we identified counties across the continental U.S. with heightened multi-pollutant exposures and EJ concerns. Subsequently, a case study within the Detroit metropolitan area was conducted, revealing a clear overlap between multi-pollutant and EJ issues, underscoring the disproportionate burden on disadvantaged communities. The analysis of detailed emissions data unveiled potential co-control benefits in this region. Lastly, employing a proximity analysis method, we assessed environmental issues surrounding points of interest such as monitoring sites and emissions sectors, in the Detroit metropolitan area. The results demonstrated that monitoring sites with the highest monitoring value, alongside top-ranked emissions sectors such as electric utilities, coke ovens, and iron and steel production, were likely to exhibit elevated air pollutant concentrations/risks and associated EJ concerns in their vicinity. [ABSTRACT FROM AUTHOR]

Amid the growing concerns about air toxics from pollution sources, much emphasis has been placed on their impacts on human health. However, there has been limited research conducted to assess the cumulative country-wide impact of air toxics on both terrestrial and aquatic ecosystems, as well as the complex interactions within food webs. Traditional approaches, including those of the United States Environmental Protection Agency (US EPA), lack versatility in addressing diverse emission sources and their distinct ecological repercussions. This study addresses these gaps by introducing the Ecological Health Assessment Methodology (EHAM), a novel approach that transcends traditional methods by enabling both comprehensive country-wide and detailed regional ecological risk assessments across terrestrial and aquatic ecosystems. EHAM also advances the field by developing new food-chain multipliers (magnification factors) for localized ecosystem food web models. Employing traditional ecological multimedia risk assessment of toxics' fate and transport techniques as its foundation, this study extends US EPA methodologies to a broader range of emission sources. The quantification of risk estimation employs the quotient method, which yields an ecological screening quotient (ESQ). Utilizing Kuwait as a case study for the application of this methodology, this study's findings for data from 2017 indicate a substantial ecological risk in Kuwait's coastal zone, with cumulative ESQ values reaching as high as 3.12 × 103 for carnivorous shorebirds, contrasted by negligible risks in the inland and production zones, where ESQ values for all groups are consistently below 1.0. By analyzing the toxicity reference value (TRV) against the expected daily exposure of receptors to air toxics, the proposed methodology provides valuable insights into the potential ecological risks and their subsequent impacts on ecological populations. The present contribution aims to deepen the understanding of the ecological health implications of air toxics and lay the foundation for informed, ecology-driven policymaking, underscoring the need for measures to mitigate these impacts. [ABSTRACT FROM AUTHOR]

In this study, we test the performance of a compact gas chromatograph with photoionization detector (GC-PID) and optimize the configuration to detect ambient (sub-ppb) levels of benzene, toluene, ethylbenzene, and xylene isomers (BTEX). The GC-PID system was designed to serve as a relatively inexpensive (~10 k USD) and field-deployable air toxic screening tool alternative to conventional benchtop GCs. The instrument uses ambient air as a carrier gas and consists of a Tenax-GR sorbent-based preconcentrator, a gas sample valve, two capillary columns, and a photoionization detector (PID) with a small footprint and low power requirement. The performance of the GC-PID has been evaluated in terms of system linearity and sensitivity in field conditions. The BTEX-GC system demonstrated the capacity to detect BTEX at levels as high as 500 ppb with a linear calibration range of 0-100 ppb. A detection limit lower than 1 ppb was found for all BTEX compounds with a sampling volume of 1 L. No significant drift in the instrument was observed. A time-varying calibration technique was established that requires minimal equipment for field operations and optimizes the sampling procedure for field measurements. With an analysis time of less than 15 min, the compact GC-PID is ideal for field deployment of background and polluted atmospheres for near-real time measurements of BTEX. The results highlight the application of the compact and easily deployable GC-PID for community monitoring and screening of air toxics.

POD diffusive samplers loaded with Carbopack X and Carbograph 5TD were exposed to certified calibration mixtures containing a total of 110 different ozone precursor and air toxic compounds. Constant sampling rates were identified for 39 ozone precursors and 33 air toxics. As 9 of these compounds were included in both mixtures, this meant a total of 63 different volatile and very volatile compounds were sampled using the POD with overall expanded uncertainties below 30 % for the sampling rate associated with the whole range of sampling times from 2 to 24 h.Carbograph 5TD exhibited superior performance for diffusive sampling of oxygenated and halogenated compounds in the air toxics mixture, while Carbopack X showed higher sampling efficiencies for aliphatic and aromatic hydrocarbons, as well as halogenated compounds derived from benzene and C2 carbon number hydrocarbons.A model has been developed and applied to estimate sampling rates, primarily for the more volatile and weakly adsorbed compounds, as a function of the collected amount of analyte and the exposure time. For an additional 9 ozone precursors on Carbopack X, and 11 air toxics on Carbograph 5TD, the expanded uncertainties of modelled sampling rates were reduced to below 30 % and have a significantly reduced uncertainty compared to those associated with an averaged sampling rate.The paper provides Freundlich’s isotherm parameters for the estimated (modelled) sampling rates and defines a pragmatic approach to their application. It does so by identifying the best sampling time to use for the expected exposure concentrations and associated analyte masses. This allows for expansion of the sampling concentration range from hundreds ng m−3 to mg m−3, while avoiding saturation of the adsorbent.Finally, field measurement comparisons of POD samplers, pumped tube samplers and online gas chromatography (GC), for sampling periods of 3 and 7 days in a semi-rural background area, showed no significant differences between reported concentrations.

Among air toxics, formaldehyde (HCHO) is an important contributor to urban cancer risk. Emissions of HCHO in the United States are systematically under-reported and may enhance atmospheric ozone and particulate matter, intensifying their impacts on human health. During the 2021 Michigan-Ontario Ozone Source Experiment (MOOSE), mobile real-time (~1 s frequency) measurements of ozone, nitrogen oxides, and organic compounds were conducted in an industrialized area in metropolitan Detroit. The measured concentrations were used to infer ground-level and elevated emissions of HCHO, CO, and NO from multiple sources at a fine scale (400 m horizontal resolution) based on the 4D variational data assimilation technique and the MicroFACT air quality model. Cumulative exposure to HCHO from multiple sources of both primary (directly emitted) and secondary (atmospherically formed) HCHO was then simulated assuming emissions inferred from inverse modeling. Model-inferred HCHO emissions from larger industrial facilities were greater than 1 US ton per year while corresponding emission ratios of HCHO to CO in combustion sources were roughly 2 to 5%. Moreover, simulated ambient HCHO concentrations depended significantly on wind direction relative to the largest sources. The model helped to explain the observed HCHO concentration gradient between monitoring stations at Dearborn and River Rouge in 2021. [ABSTRACT FROM AUTHOR]

Formaldehyde is a key Volatile Organic Compound (VOC) and ozone precursor that plays a vital role in the urban atmospheric radical budget on par with water vapor, ozone, and nitrous acid. In addition to modulating radical and ozone production, ambient formaldehyde has both carcinogenic and non-carcinogenic inhalation health effects. This study concludes that ambient formaldehyde in the Southeast Michigan (SEMI) ozone nonattainment area may be underestimated up to a factor of two or more by regional air quality models. The addition of plausible amounts of primary formaldehyde to the U.S. National Emissions Inventory based on estimated formaldehyde-to-CO emission ratios partially alleviates this modeling deficit and indicates the presence of formaldehyde concentrations above 5 ppb at a previously unsuspected location northeast of Detroit. Standard 24-h formaldehyde samples obtained during the Michigan-Ontario Ozone Source Experiment (MOOSE) verified the presence of high ambient formaldehyde concentrations at this location. Moreover, the addition of plausible amounts of primary formaldehyde to VOC emissions inventories may add more than 1 ppb of ozone to ambient air in the SEMI nonattainment area, where ozone design values exceeded the U.S. National Ambient Air Quality Standard (NAAQS) by 1–2 ppb for the 2018–2020 design value period. [ABSTRACT FROM AUTHOR]

Air toxics are an important category of air pollutants that are known to cause adverse health effects, including increased cancer risk. Regulatory efforts at federal, state, and local levels have aimed to decrease air toxics emissions over the past several decades. This study evaluated trends in air toxics cancer risks in Southern California using data from 1998 to 2018. We estimated air toxics cancer risk for each of four iterations of the South Coast Air Quality Management District’s Multiple Air Toxics Exposure Study, which included at least one year of measurements at 10 stations and air toxics modeling for each iteration. Cancer risks were calculated using the measured and modeled air toxics concentrations averaged over a one to two year period and multiplied by the corresponding cancer potency factor and combined exposure factor that accounted for multiple exposure pathways and children’s increased sensitivity to the health effects of air pollution. We examined temporal trends in overall air toxics cancer risks and evaluated changes in the air toxics species that contributed most to cancer risk in the region. Both measurement and modeling results show that air toxics cancer risk in Southern California decreased by more than 80% between 1998 and 2018, including a decrease of about 50% from 2012 to 2018. Diesel particulate matter was the main risk driver, followed by benzene, 1,3-butadiene, and formaldehyde. We found that more densely populated communities showed larger decreases than sparsely populated areas. The substantial decrease in air toxics levels over this 20-year period points to the success of air pollution policies aimed at addressing air toxics emissions and can inform future policy efforts to further reduce air toxics health impacts.

Amid the growing concerns about air toxics from pollution sources, much emphasis has been placed on their impacts on human health. However, there has been limited research conducted to assess the cumulative country-wide impact of air toxics on both terrestrial and aquatic ecosystems, as well as the complex interactions within food webs. Traditional approaches, including those of the United States Environmental Protection Agency (US EPA), lack versatility in addressing diverse emission sources and their distinct ecological repercussions. This study addresses these gaps by introducing the Ecological Health Assessment Methodology (EHAM), a novel approach that transcends traditional methods by enabling both comprehensive country-wide and detailed regional ecological risk assessments across terrestrial and aquatic ecosystems. EHAM also advances the field by developing new food-chain multipliers (magnification factors) for localized ecosystem food web models. Employing traditional ecological multimedia risk assessment of toxics’ fate and transport techniques as its foundation, this study extends US EPA methodologies to a broader range of emission sources. The quantification of risk estimation employs the quotient method, which yields an ecological screening quotient (ESQ). Utilizing Kuwait as a case study for the application of this methodology, this study’s findings for data from 2017 indicate a substantial ecological risk in Kuwait’s coastal zone, with cumulative ESQ values reaching as high as 3.12 × 103 for carnivorous shorebirds, contrasted by negligible risks in the inland and production zones, where ESQ values for all groups are consistently below 1.0. By analyzing the toxicity reference value (TRV) against the expected daily exposure of receptors to air toxics, the proposed methodology provides valuable insights into the potential ecological risks and their subsequent impacts on ecological populations. The present contribution aims to deepen the understanding of the ecological health implications of air toxics and lay the foundation for informed, ecology-driven policymaking, underscoring the need for measures to mitigate these impacts.

US Census Bureau data were matched to U.S. Environmental Protection Agency estimated cancer risks from airborne toxics from 2011 to 2019 to explore environmental inequality with nationwide census tract resolution. Spearman correlations showed modest associations between various socioeconomic status factors and estimated cancer risk. Multiple linear regression analyses show positive associations with increased estimated cancer risk ( p < 0.05) for high proportions of Blacks in suburban and rural areas. A positive relationship with estimated cancer risk was found for increasing proportions of Asians and Hispanics in nonurban areas. Urban tracts that suffer from the highest estimated cancer risks were concentrated among the communities with a population of higher proportion of minorities. While environmental inequality seems to have improved across the examined years for certain demographics with respect to estimated cancer risk from air toxics, equity is far from achieved, and future work in identifying the sources of environmental inequality could help in achieving a more just environment.

Heavy metal concentrations often vary at small spatial scales not captured by air monitoring networks, with implications for environmental justice in industrial‐adjacent communities. Pollutants measured in moss tissues are commonly used as a screening tool to guide use of more expensive resources, like air monitors. Such studies, however, rarely address environmental justice issues or involve the residents and other decision makers expected to utilize results. Here, we piloted a community science approach, engaging over 55 people from nine institutions, to map heavy metals using moss in two industrial‐adjacent neighborhoods. This area, long known for disproportionately poor air quality, health outcomes, and racial inequities, has only one monitor for heavy metals. Thus, an initial understanding of spatial patterns is critical for gauging whether, where, and how to invest further resources toward investigating heavy metals. Local youth‐led sampling of the moss Orthotrichum lyellii from trees across a 250 × 250 m sampling grid (n = 79) and generated data comparable to expert‐collected samples (n = 19). We mapped 21 chemical elements measured in moss, including 6 toxic "priority" metals: arsenic, cadmium, chromium, cobalt, lead, and nickel. Compared to other urban O. lyellii studies, local moss had substantially higher priority metals, especially arsenic and chromium, encouraging community members to investigate further. Potential hotspots of priority metals varied somewhat but tended to peak near the central industrial core where many possible emission sources, including legacy contamination and converge. Informed by these findings, community members successfully advocated regulators for a second study phase—a community‐directed air monitoring campaign to evaluate residents' exposure to heavy metals—as is needed to connect moss results back to the partnership's core goal of understanding drivers of health disparities. This follow‐up campaign will measure metals in the PM10 fraction owing to clues in the current study that airborne soil and dust may be locally important carriers of priority metals. Future work will address how our approach combining bioindicators and community science ultimately affects success addressing longstanding environmental justice concerns. For now, we illustrate the potential to co‐create new knowledge, to help catalyze and strategize next steps, in a complex air quality investigation. [ABSTRACT FROM AUTHOR]

Abstract Heavy metal concentrations often vary at small spatial scales not captured by air monitoring networks, with implications for environmental justice in industrial‐adjacent communities. Pollutants measured in moss tissues are commonly used as a screening tool to guide use of more expensive resources, like air monitors. Such studies, however, rarely address environmental justice issues or involve the residents and other decision makers expected to utilize results. Here, we piloted a community science approach, engaging over 55 people from nine institutions, to map heavy metals using moss in two industrial‐adjacent neighborhoods. This area, long known for disproportionately poor air quality, health outcomes, and racial inequities, has only one monitor for heavy metals. Thus, an initial understanding of spatial patterns is critical for gauging whether, where, and how to invest further resources toward investigating heavy metals. Local youth‐led sampling of the moss Orthotrichum lyellii from trees across a 250 × 250 m sampling grid (n = 79) and generated data comparable to expert‐collected samples (n = 19). We mapped 21 chemical elements measured in moss, including 6 toxic “priority” metals: arsenic, cadmium, chromium, cobalt, lead, and nickel. Compared to other urban O. lyellii studies, local moss had substantially higher priority metals, especially arsenic and chromium, encouraging community members to investigate further. Potential hotspots of priority metals varied somewhat but tended to peak near the central industrial core where many possible emission sources, including legacy contamination and converge. Informed by these findings, community members successfully advocated regulators for a second study phase—a community‐directed air monitoring campaign to evaluate residents' exposure to heavy metals—as is needed to connect moss results back to the partnership's core goal of understanding drivers of health disparities. This follow‐up campaign will measure metals in the PM10 fraction owing to clues in the current study that airborne soil and dust may be locally important carriers of priority metals. Future work will address how our approach combining bioindicators and community science ultimately affects success addressing longstanding environmental justice concerns. For now, we illustrate the potential to co‐create new knowledge, to help catalyze and strategize next steps, in a complex air quality investigation.

Among air toxics, formaldehyde (HCHO) is an important contributor to urban cancer risk. Emissions of HCHO in the United States are systematically under-reported and may enhance atmospheric ozone and particulate matter, intensifying their impacts on human health. During the 2021 Michigan-Ontario Ozone Source Experiment (MOOSE), mobile real-time (~1 s frequency) measurements of ozone, nitrogen oxides, and organic compounds were conducted in an industrialized area in metropolitan Detroit. The measured concentrations were used to infer ground-level and elevated emissions of HCHO, CO, and NO from multiple sources at a fine scale (400 m horizontal resolution) based on the 4D variational data assimilation technique and the MicroFACT air quality model. Cumulative exposure to HCHO from multiple sources of both primary (directly emitted) and secondary (atmospherically formed) HCHO was then simulated assuming emissions inferred from inverse modeling. Model-inferred HCHO emissions from larger industrial facilities were greater than 1 US ton per year while corresponding emission ratios of HCHO to CO in combustion sources were roughly 2 to 5%. Moreover, simulated ambient HCHO concentrations depended significantly on wind direction relative to the largest sources. The model helped to explain the observed HCHO concentration gradient between monitoring stations at Dearborn and River Rouge in 2021.

Volatile organic compounds (VOCs) emitted from industrial processes, which are major emission sources of air pollutants, could cause significant impacts on air quality. However, studies on the comprehensive analysis from sources contributing to the health risk perspective regarding ambient VOCs in industrial cities are limited. In this study, VOC samples were collected from 15 April 2018 to 19 October 2018 in Changzhi, a typical industrial city in northern China, and a total of 57 VOCs were measured for analysis. The average VOC concentrations were 54.4 µg·m−3, with the highest concentrations in autumn (58.4 µg·m−3). Ambient VOCs in spring, summer and autumn were all dominated by alkanes (66.8%), with contributions of 70.3%, 66.3% and 63.8%, respectively. The top five concentrations of total VOCs were isopentane (19.0%), ethane (9.5%), n-butane (8.1%), benzene (7.9%) and propane (5.2%), indicating that vehicle exhaust and coal combustion are the main sources of VOCs. Source apportionment by principal component analysis showed that vehicle exhaust (27.5%) and coal combustion (23.5%) were the main sources of VOCs in Changzhi, followed by industrial production (17.4%), solvent evaporation (13.5%), liquefied petroleum gas/natural gas leaking (9.5%), and biogenic emissions (8.7%). Sources of coal combustion and vehicle exhaust contributed more VOCs than industrial production. The carcinogenic risks of benzene (3.4 × 10−5) and ethylbenzene (2.2 × 10−6) were higher than the limit levels (1 × 10−6). Coal combustion contributed most (25.3%) to the carcinogenic risks because of its high VOC emissions. In an industrial city such as Changzhi, vehicle exhaust and coal combustion have become major sources of ambient air VOCs owing to the increasingly stringent industrial standards. Therefore, VOCs from vehicle exhaust and coal combustion also need to take into account mitigation measures for VOCs from the perspective of source contribution to health risk. [ABSTRACT FROM AUTHOR]

The importance of studying the health impacts of exposure mixtures is increasingly being recognized, but such research presents many methodological and interpretation difficulties. We used Bayesian g-computation to estimate effects of a simulated public health action on exposure mixtures and birth weights in Milwaukee, Wisconsin, in 2011–2013. We linked data from birth records with census-tract–level air toxics data from the Environmental Protection Agency's National Air Toxics Assessment model. We estimated the difference between observed and expected birth weights that theoretically would have followed a hypothetical intervention to reduce exposure to 6 airborne metals by decommissioning 3 coal-fired power plants in Milwaukee County prior to 2010. Using Bayesian g-computation, we estimated a 68-g (95% credible interval: 25, 135) increase in birth weight following this hypothetical intervention. This example demonstrates the utility of our approach for using observational data to evaluate and contrast possible public health actions. Additionally, Bayesian g-computation offers a flexible strategy for estimating the effects of highly correlated exposures, addressing statistical issues such as variance inflation, and addressing conceptual issues such as the lack of interpretability of independent effects. [ABSTRACT FROM AUTHOR]

Formaldehyde is a key Volatile Organic Compound (VOC) and ozone precursor that plays a vital role in the urban atmospheric radical budget on par with water vapor, ozone, and nitrous acid. In addition to modulating radical and ozone production, ambient formaldehyde has both carcinogenic and non-carcinogenic inhalation health effects. This study concludes that ambient formaldehyde in the Southeast Michigan (SEMI) ozone nonattainment area may be underestimated up to a factor of two or more by regional air quality models. The addition of plausible amounts of primary formaldehyde to the U.S. National Emissions Inventory based on estimated formaldehyde-to-CO emission ratios partially alleviates this modeling deficit and indicates the presence of formaldehyde concentrations above 5 ppb at a previously unsuspected location northeast of Detroit. Standard 24-h formaldehyde samples obtained during the Michigan-Ontario Ozone Source Experiment (MOOSE) verified the presence of high ambient formaldehyde concentrations at this location. Moreover, the addition of plausible amounts of primary formaldehyde to VOC emissions inventories may add more than 1 ppb of ozone to ambient air in the SEMI nonattainment area, where ozone design values exceeded the U.S. National Ambient Air Quality Standard (NAAQS) by 1–2 ppb for the 2018–2020 design value period.

Background: Production of shale gas in the United States (US) increased more than 10-fold from 2008 to 2021, yielding greater quantities of hydrocarbon feedstocks and incentivizing expansion of petrochemical facilities. Steam crackers (SCs) convert hydrocarbon feedstocks into ethylene and propylene (the building blocks of plastics), while releasing toxic chemicals and greenhouse gases (GHGs). Analyses of environmental health and justice impacts of SCs are limited. Methods: We described SC operations, locations, and emissions, and evaluated sociodemographic characteristics of populations residing near SCs to better understand potential public health hazards and inform future studies. We summarized and described industry-reported emissions from the US Environmental Protection Agency’s Toxic Release Inventory and GHG Reporting Program. We compared population characteristics of US Census block groups ⩽5 km and >5 km from a steam cracker-containing facility (SCF) within the same county. Results: We identified 32 SCFs across five US states, with most in Texas and Louisiana. Toxic chemicals with the greatest reported cumulative air emissions in 1987–2019 were: ethylene, propylene, hydrochloric acid, benzene, n-hexane, 1,3-butadiene, ammonia, toluene, vinyl acetate, and methanol. Reported total annual GHG emissions were 4% higher in 2019 versus 2010, with total GHG emissions of >650 million metric tons (carbon dioxide equivalents) in 2010–2019. We found that 752 465 people live in census block groups ⩽5 km from an SCF, regardless of county. Compared to block groups >5 km away within the same county, block groups closer to SCFs had statistically significantly lower median incomes ($54 843 vs $67 866) and more vacant housing (15% vs 11%), and higher proportions of residents who were non-Hispanic Black (31% vs 19%) and unemployed (8% vs 6%). Conclusion: SCs emit substantial amounts of GHGs and toxic chemicals in locations with historically disadvantaged populations. Future research could further evaluate the accuracy of reported emissions, conduct monitoring in proximate communities, and assess population-level health impacts.

There is a growing awareness of the health impacts of ethylene oxide (EtO) and its role as a carcinogenic and mutagenic air contaminant of concern. Given the need to better understand EtO emissions and associated health effects, it is imperative to overcome the significant challenges associated with EtO measurement in complex air matrices, such as combustion emissions. This work focused on addressing these challenges by evaluating the utility of widely used canister-based EtO ambient measurement approaches, EPA Methods TO-15 and TO-15A, to investigate the presence of EtO in heavy-duty diesel vehicle (HDDV) exhaust. Chassis dynamometer testing was performed on two HDDVs and emissions samples were collected and analyzed following TO-15/TO-15A. Initial testing utilizing TO-15 led to the identification of a diesel exhaust constituent, ethyl nitrite, that coeluted with EtO during analysis and contributed large positive bias. An optimized TO-15A analytical approach was developed and utilized to measure EtO in diesel exhaust from two HDDVs in additional dynamometer tests. Using this optimized approach, EtO was not detected in HDDV exhaust in these tests. This work highlights the importance of utilizing this optimized approach to accurately quantify EtO in mobile source exhaust and may also be needed for testing other combustion sources.

Purpose: Regional air quality models generate a high-resolution prediction of pollutant concentrations using sophisticated treatments of atmospheric fate and transport processes, speciation, and chemistry. By comparison, the multi-media box modeling underpinning the USEtox model is far simpler but allows for broad coverage of hazardous air pollutants. The purpose of the present article is to benchmark USEtox results via inhalation against a state-of-the-science regulatory model and investigate methodological areas that drive differences in results. Methods: The 2014 US National Air Toxics Assessment (NATA) used a linked dispersion-regional air quality model to evaluate human health risk from emissions of air toxics, a prescribed list of hazardous air pollutants that can cause cancer and severe human health effects. We compare the NATA results for human health risk from carcinogenic emissions to characterization factors generated by running the USEtox model on the same starting emissions inventory, namely, the US National Emissions Inventory (NEI), using the North American model parameterization. We have also decomposed characterization factors into intake fractions and effect factors. The separate comparison analysis allows us to trace the driving force for cancer risk differences. Statistical analysis is applied to determine the significance of pollutant characteristics in driving differences in results, including molecular weight, vapor pressure, octanol–water partitioning, compartment half-lives in air, and chemical composition. Results and discussion: Comparative analysis shows a good concordance for carcinogenic impacts between the two models, with a factor of ~10 difference. The difference in effect factors is ~1.4, which is within an expected range. However, intake fraction is the major cause of cancer risk divergence. Intake fractions in NATA tend to have large variations due to the high-resolution air dispersion model and including secondary pollutants. NATA and USEtox results have consistent levels of statistical significance across the pollutant characteristics evaluated, with the greatest level of significance (p < 0.05) for molecular weight and vapor pressure, which strongly influence atmospheric fate. Formaldehyde is the dominant contributor to the total burden of diseases with 5000 to 20,000 cases of cancer per year. Conclusions: It is critical to benchmark LCIA results against current state-of-the-science models in order to ensure that LCA results can be reliably used for decision support. The USEtox model was not designed to mimic the complexity of full-scale air quality modeling, but still manages to produce a relative scaling of carcinogenic impacts that is consistent with NATA. Further regionalization, calibration, or inclusion of additional chemical transformations within the USEtox model may yield further performance improvements. [ABSTRACT FROM AUTHOR]

BackgroundNumerous studies have linked criteria air pollutants with adverse birth outcomes, but there is less information on the importance of specific emission sources, such as traffic, and air toxics.ObjectivesWe used three exposure data sources to examine odds of term low birth weight (LBW) in Los Angeles, California, women when exposed to high levels of traffic-related air pollutants during pregnancy.MethodsWe identified term births during 1 June 2004 to 30 March 2006 to women residing within 5 miles of a South Coast Air Quality Management District (SCAQMD) Multiple Air Toxics Exposure Study (MATES III) monitoring station. Pregnancy period average exposures were estimated for air toxics, including polycyclic aromatic hydrocarbons (PAHs), source-specific particulate matter < 2.5 μm in aerodynamic diameter (PM2.5) based on a chemical mass balance model, criteria air pollutants from government monitoring data, and land use regression (LUR) model estimates of nitric oxide (NO), nitrogen dioxide (NO2) and nitrogen oxides (NOx). Associations between these metrics and odds of term LBW (< 2,500 g) were examined using logistic regression.ResultsOdds of term LBW increased approximately 5% per interquartile range increase in entire pregnancy exposures to several correlated traffic pollutants: LUR measures of NO, NO2, and NOx, elemental carbon, and PM2.5 from diesel and gasoline combustion and paved road dust (geological PM2.5).ConclusionsThese analyses provide additional evidence of the potential impact of traffic-related air pollution on fetal growth. Particles from traffic sources should be a focus of future studies.

Indentifying pollutants that pose a potential hazard indoors is an important first step to reducing risks. We reviewed key published studies reporting measurements of chemical pollutants in residences. Summary results were compiled and used to calculate representative mid-range and upper-bound concentrations relevant to chronic exposures for over 300 pollutants and peak concentrations relevant to acute exposures for a few episodic activity-associated pollutants. For the over 100 pollutants with available criterions, the measured concentrations are compared to available chronic and acute health-hazard standards and guidelines. Fifteen pollutants are identified as potential chronic or acute health hazards for many homes. A subset of pollutants are identified as priority chemical pollutants and suggestions are made for effectively reducing indoor concentrations.

So long as transaction costs are low, the creation of a tradeable permit to emit carbon should allow bargaining for emission rights among buyers and sellers, resulting in an efficient allocation of carbon emission rights. However, the trading of carbon credits may have socially unjust consequences. In this article, we explore some hitherto unrecognized disequities. One of these may be the creation of toxic hotspots as the trade of carbon may bring with it a transfer of air toxics, as well. We illustrate the argument by examining emissions from refineries participating in California’s cap-and-trade program. These considerations are a concern for the larger question of carbon mitigation as the global community strives to identify feasible, yet just, approaches to reducing greenhouse gas emissions. Contrary to the idea of alienable rights, the transfer of carbon affects people and place in ways not internalized by these market instruments.

Volatile organic compounds (VOCs) emitted from industrial processes, which are major emission sources of air pollutants, could cause significant impacts on air quality. However, studies on the comprehensive analysis from sources contributing to the health risk perspective regarding ambient VOCs in industrial cities are limited. In this study, VOC samples were collected from 15 April 2018 to 19 October 2018 in Changzhi, a typical industrial city in northern China, and a total of 57 VOCs were measured for analysis. The average VOC concentrations were 54.4 µg·m−3, with the highest concentrations in autumn (58.4 µg·m−3). Ambient VOCs in spring, summer and autumn were all dominated by alkanes (66.8%), with contributions of 70.3%, 66.3% and 63.8%, respectively. The top five concentrations of total VOCs were isopentane (19.0%), ethane (9.5%), n-butane (8.1%), benzene (7.9%) and propane (5.2%), indicating that vehicle exhaust and coal combustion are the main sources of VOCs. Source apportionment by principal component analysis showed that vehicle exhaust (27.5%) and coal combustion (23.5%) were the main sources of VOCs in Changzhi, followed by industrial production (17.4%), solvent evaporation (13.5%), liquefied petroleum gas/natural gas leaking (9.5%), and biogenic emissions (8.7%). Sources of coal combustion and vehicle exhaust contributed more VOCs than industrial production. The carcinogenic risks of benzene (3.4 × 10−5) and ethylbenzene (2.2 × 10−6) were higher than the limit levels (1 × 10−6). Coal combustion contributed most (25.3%) to the carcinogenic risks because of its high VOC emissions. In an industrial city such as Changzhi, vehicle exhaust and coal combustion have become major sources of ambient air VOCs owing to the increasingly stringent industrial standards. Therefore, VOCs from vehicle exhaust and coal combustion also need to take into account mitigation measures for VOCs from the perspective of source contribution to health risk.

Paddy-residue burning is associated with poor air quality in north-west India during October–November every year. However, till date a quantitative study of its contribution to ambient volatile organic compounds (VOCs) using highly time-resolved measurements within the region has been lacking. Several VOCs like benzene are carcinogenic and also fuel formation of secondary pollutants such as secondary organic aerosol (SOA) and ozone. Here, we undertake quantitative source-apportionment using a PMF source-receptor model on a high-quality in-situ measured dataset of 54 VOCs in Punjab, India, and validate the model results using source profiles. The contribution of the seven most dominant sources to the total VOC mass concentrations were: daytime photochemistry and biogenic VOCs (BVOCs) (26%), followed by solid-fuel usage and waste-disposal (18%), traffic (two-wheeler 14% and four-wheeler 10%), photochemically aged biomass burning (17%), industries and solvent usage (9%), and fresh paddy residue burning (6%). Ozone production potential was dominated by solid fuel usage and waste disposal (25%), followed by traffic (two-wheeler 11% and four-wheeler 12%), BVOCs and photooxidation products (21%), photochemically aged biomass burning (16%), industries & solvent usage (9%) and fresh paddy residue burning (6%). SOA production was dominated by traffic (two-wheeler 26% and four-wheeler 28%) followed by solid fuel usage and waste disposal (22%), photochemically aged biomass burning emissions (15%) with minor contribution from industries & solvents (6%), fresh paddy residue burning (2%) and photochemistry and biogenic VOCs (1%). Comparisons with global emission inventories REASv3.2.1 and EDGARv4.3.2, showed both overestimate the industry and solvent source. Further, EDGARv4.3.2 underestimated the traffic source whereas paddy residue burning emissions are absent in REASv3.2.1. Although the overall mass contribution of paddy-residue burning emissions isn't high, our results show that health-relevant compounds emitted directly and formed photochemically from biomass burning sources active at this time are majorly responsible for the unhealthy air. [Display omitted] • Quantification of VOC sources during paddy residue burning over Indo-Gangetic Plain. • Solid-fuel use & waste-disposal & traffic together contributed> 40% VOC mass burden. • Photo-chemical oxidation of biomass burning emissions large source of toxic VOCs. • Paddy-residue burning emissions had low mass concentration contribution. • REASv3.2.1 and EDGARv4.3.2 EIs overestimate industry and solvent source. [ABSTRACT FROM AUTHOR]

This study examines links between racial residential segregation and estimated ambient air toxics exposures and their associated cancer risks using modeled concentration estimates from the U.S. Environmental Protection Agency's National Air Toxics Assessment. We combined pollutant concentration estimates with potencies to calculate cancer risks by census tract for 309 metropolitan areas in the United States. This information was combined with socioeconomic status (SES) measures from the 1990 Census. Estimated cancer risks associated with ambient air toxics were highest in tracts located in metropolitan areas that were highly segregated. Disparities between racial/ethnic groups were also wider in more segregated metropolitan areas. Multivariate modeling showed that, after controlling for tract-level SES measures, increasing segregation amplified the cancer risks associated with ambient air toxics for all racial groups combined [highly segregated areas: relative cancer risk (RCR) = 1.04; 95% confidence interval (CI), 1.01-107; extremely segregated areas: RCR = 1.32; 95% CI, 1.28-1.36]. This segregation effect was strongest for Hispanics (highly segregated areas: RCR = 1.09; 95% CI, 1.01-1.17; extremely segregated areas: RCR = 1.74; 95% CI, 1.61-1.88) and weaker among whites (highly segregated areas: RCR = 1.04; 95% CI, 1.01-1.08; extremely segregated areas: RCR = 1.28; 95% CI, 1.24-1.33), African Americans (highly segregated areas: RCR = 1.09; 95% CI, 0.98-1.21; extremely segregated areas: RCR = 1.38; 95% CI, 1.24-1.53), and Asians (highly segregated areas: RCR = 1.10; 95% CI, 0.97-1.24; extremely segregated areas: RCR = 1.32; 95% CI, 1.16-1.51). Results suggest that disparities associated with ambient air toxics are affected by segregation and that these exposures may have health significance for populations across racial lines.

Recent legislation on both federal and state levels has placed the intersection between children’s health and environmental justice on the forefront of public policy debate. This study looks at the intersection of air quality, children’s health, and school performance in the context of environmental equity in California. Information from the U.S. EPA’s National Air Toxics Assessment (NATA) is used to calculate a respiratory hazard ratio for each of California’s census tracts. These ratios are then associated with a geo-coded database of the state's public schools, including school-level information on student demographics and the school's academic performance. We find that students of color are disproportionately located in schools with higher respiratory hazard ratios and also find a link between respiratory hazards and school performance, even after controlling for other factors that affect student performance. We conclude by recommending that state and community actors seek improvements in data collection, better filtration and ventilation in schools, the fuller incorporation of school-level health concerns, and the reduction of pollution at its various sources.

Environmental justice offers researchers new insights into the juncture of social inequality and public health and provides a framework for policy discussions on the impact of discrimination on the environmental health of diverse communities in the United States. Yet, causally linking the presence of potentially hazardous facilities or environmental pollution with adverse health effects is difficult, particularly in situations in which diverse populations are exposed to complex chemical mixtures. A community-academic research collaborative in southern California sought to address some of these methodological challenges by conducting environmental justice research that makes use of recent advances in air emissions inventories and air exposure modeling data. Results from several of our studies indicate that communities of color bear a disproportionate burden in the location of treatment, storage, and disposal facilities and Toxic Release Inventory facilities. Longitudinal analysis further suggests that facility siting in communities of color, not market-based "minority move-in," accounts for these disparities. The collaborative also investigated the health risk implications of outdoor air toxics exposures from mobile and stationary sources and found that race plays an explanatory role in predicting cancer risk distributions among populations in the region, even after controlling for other socioeconomic and demographic indicators. Although it is unclear whether study results from southern California can be meaningfully generalized to other regions in the United States, they do have implications for approaching future research in the realm of environmental justice. The authors propose a political economy and social inequality framework to guide future research that could better elucidate the origins of environmental inequality and reasons for its persistence.

In this study, we test the performance of a compact gas chromatograph with photoionization detector (GC-PID) and optimize the configuration to detect ambient (sub-ppb) levels of benzene, toluene, ethylbenzene, and xylene isomers (BTEX). The GC-PID system was designed to serve as a relatively inexpensive (~10 k USD) and field-deployable air toxic screening tool alternative to conventional benchtop GCs. The instrument uses ambient air as a carrier gas and consists of a Tenax-GR sorbent-based preconcentrator, a gas sample valve, two capillary columns, and a photoionization detector (PID) with a small footprint and low power requirement. The performance of the GC-PID has been evaluated in terms of system linearity and sensitivity in field conditions. The BTEX-GC system demonstrated the capacity to detect BTEX at levels as high as 500 ppb with a linear calibration range of 0–100 ppb. A detection limit lower than 1 ppb was found for all BTEX compounds with a sampling volume of 1 L. No significant drift in the instrument was observed. A time-varying calibration technique was established that requires minimal equipment for field operations and optimizes the sampling procedure for field measurements. With an analysis time of less than 15 min, the compact GC-PID is ideal for field deployment of background and polluted atmospheres for near-real time measurements of BTEX. The results highlight the application of the compact and easily deployable GC-PID for community monitoring and screening of air toxics.

Background: Previous research shows that environmental and social factors contribute to the development of attention-deficit/hyperactivity disorder (ADHD).Objective: To determine the relationship between early-life exposure to common ambient air pollutants (benzene, toluene, ethylbenzene, and xylene, also known as BTEX), household material hardship (a measure of socio-economic status), and ADHD-suggestive behaviours in kindergarten-age children.Methods: Pollutant exposure estimated from the 2002 National Air Toxics Assessment at each child's residential ZIP code at enrolment was linked to the Early Childhood Longitudinal Study Birth Cohort (n = 4650). Material hardship was assigned as a composite score of access to food, health care, and housing. Kindergarten teachers rated children's behaviours and activity in the classroom using a five-point Likert scale. Children with summary scores in the bottom decile were classified as displaying ADHD-suggestive behaviours. Logistic regression models were constructed to estimate the association between both BTEX exposure and material hardship on ADHD-suggestive behaviours.Results: The odds of displaying ADHD-suggestive behaviours were greater in children with combined high-level exposure to BTEX and in those experiencing material hardship (odds ratio 1.54, 95% confidence interval [CI] 1.12, 2.11, and OR 2.12, 95% CI 1.25, 3.59, respectively), adjusting for covariates. These associations were stronger when restricting the study population to urban areas. There was no evidence of interaction between early life BTEX exposure and material hardship, although the effects of BTEX exposure were slightly greater in magnitude among those with higher material hardship scores.Conclusions: Children exposed to air toxics, material hardship, or both early in life are more likely to display signs of ADHD-suggestive behaviours as assessed by their kindergarten teachers. The associations between exposures to air pollution and to socio-economic hardship were observed in all children but were particularly strong in those living in urban areas. [ABSTRACT FROM AUTHOR]

Occupational and toxicological studies have demonstrated adverse health effects from exposure to toxic air contaminants. Data on outdoor levels of toxic air contaminants have not been available for most communities in the United States, making it difficult to assess the potential for adverse human health effects from general population exposures. Emissions data from stationary and mobile sources are used in an atmospheric dispersion model to estimate outdoor concentrations of 148 toxic air contaminants for each of the 60,803 census tracts in the contiguous United States for 1990. Outdoor concentrations of air toxics were compared to previously defined benchmark concentrations for cancer and noncancer health effects. Benchmark concentrations are based on standard toxicological references and represent air toxic levels above which health risks may occur. The number of benchmark concentrations exceeded by modeled concentrations ranged from 8 to 32 per census tract, with a mean of 14. Estimated concentrations of benzene, formaldehyde, and 1,3-butadiene were greater than cancer benchmark concentrations in over 90% of the census tracts. Approximately 10% of all census tracts had estimated concentrations of one or more carcinogenic HAPs greater than a 1-in-10,000 risk level. Twenty-two pollutants with chronic toxicity benchmark concentrations had modeled concentrations in excess of these benchmarks, and approximately 200 census tracts had a modeled concentration 100 times the benchmark for at least one of these pollutants. This comprehensive assessment of air toxics concentrations across the United States indicates hazardous air pollutants may pose a potential public health problem.

Ethylene oxide (EtO) is an industrial gas that was recently reassessed to pose significant additional cancer risk at low ambient concentrations. The objective of this study is to evaluate the capabilities of existing and novel techniques to measure ambient EtO at concentrations relevant for assessing cancer risk. We present the first comparison of background ambient EtO measurements between the standard offline TO-15 techniques and two new cavity ringdown spectroscopy (CRDS) instruments, the Picarro G2920 Ethylene Oxide Gas Analyzer and the Entanglement Technologies AROMA-ETO, at a site in Atlanta, GA. Then, we analyzed background EtO measured at EPA NATTS sites across the US. Finally, we used TO-15 measurement data to assess EtO cancer risk at three near-source sites. We find that the TO-15 method has low precision for collocated samples (NME ranges from 24% to 63%), and measurements made with TO-15 pressurized samplers are biased 27% low compared to those from TO-15 passive samplers. Both CRDS methods are biased low compared to TO-15 methods (88% and 31% low bias for Picarro and AROMA, respectively), and TO-15 methods observe a seasonal peak during summer (June to September) whereas Picarro observes no seasonal trend. From our near-source assessment, we find only one site with notable elevation in cancer risk prior to EtO controls installation. Our results suggest that measurement techniques need further development to accurately assess near-source EtO cancer risk. Because different techniques measure distinct EtO trends, EtO cancer risk studies that rely on current measurement capabilities should subtract simultaneous background observations from near-source observations measured by the same method to account for these real or artificial background trends. [Display omitted] • Canister-based background ethylene oxide (EtO) measurements are imprecise. • Canister and cavity ringdown spectroscopic EtO measurements show little agreement. • Disagreement in measured EtO results in large differences in estimated cancer risk. • EtO emissions controls likely reduced cancer risk near one sterilization facility. [ABSTRACT FROM AUTHOR]

[Display omitted] POD diffusive samplers loaded with Carbopack X and Carbograph 5TD were exposed to certified calibration mixtures containing a total of 110 different ozone precursor and air toxic compounds. Constant sampling rates were identified for 39 ozone precursors and 33 air toxics. As 9 of these compounds were included in both mixtures, this meant a total of 63 different volatile and very volatile compounds were sampled using the POD with overall expanded uncertainties below 30 % for the sampling rate associated with the whole range of sampling times from 2 to 24 h. Carbograph 5TD exhibited superior performance for diffusive sampling of oxygenated and halogenated compounds in the air toxics mixture, while Carbopack X showed higher sampling efficiencies for aliphatic and aromatic hydrocarbons, as well as halogenated compounds derived from benzene and C 2 carbon number hydrocarbons. A model has been developed and applied to estimate sampling rates, primarily for the more volatile and weakly adsorbed compounds, as a function of the collected amount of analyte and the exposure time. For an additional 9 ozone precursors on Carbopack X, and 11 air toxics on Carbograph 5TD, the expanded uncertainties of modelled sampling rates were reduced to below 30 % and have a significantly reduced uncertainty compared to those associated with an averaged sampling rate. The paper provides Freundlich's isotherm parameters for the estimated (modelled) sampling rates and defines a pragmatic approach to their application. It does so by identifying the best sampling time to use for the expected exposure concentrations and associated analyte masses. This allows for expansion of the sampling concentration range from hundreds ng m−3 to mg m−3, while avoiding saturation of the adsorbent. Finally, field measurement comparisons of POD samplers, pumped tube samplers and online gas chromatography (GC), for sampling periods of 3 and 7 days in a semi-rural background area, showed no significant differences between reported concentrations. [ABSTRACT FROM AUTHOR]

Background: Exposure misclassification based solely on the address at cancer diagnosis has been widely recognized though not commonly assessed., Methods: We linked 1,015 mesothelioma cases diagnosed during 2011-2015 from the New York State Cancer Registry to inpatient claims and LexisNexis administrative data and constructed residential histories. Percentile ranking of exposure to ambient air toxics and socioeconomic status (SES) were based on the National Air Toxic Assessment and United States Census data, respectively. To facilitate comparisons over time, relative exposures (REs) were calculated by dividing the percentile ranking at individual census tract by the state-level average and subtracting one. We used generalized linear regression models to compare the RE in the past with that at cancer diagnosis, adjusting for patient-level characteristics., Results: Approximately 43.7% of patients had residential information available for up to 30 years, and 96.0% up to 5 years. The median number of unique places lived was 4 [interquartile range (IQR), 2-6]. The time-weighted-average RE from all addresses available had a median of -0.11 (IQR, -0.50 to 0.30) for air toxics and -0.28 (IQR, -0.65 to 0.25) for SES. RE associated with air toxics (but not SES) was significantly higher for earlier addresses than addresses at cancer diagnosis for the 5-year [annual increase =1.24%; 95% confidence interval (CI): 0.71-1.77%; n=974] and 30-year (annual increase =0.36%; 95% CI: 0.25-0.48%; n=444) look-back windows, respectively., Conclusions: Environmental exposure to non-asbestos air toxics among mesothelioma patients may be underestimated if based solely on the address at diagnosis. With geospatial data becoming more readily available, incorporating cancer patients' residential history would lead to reduced exposure misclassification and accurate health risk estimates., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-23-533/coif). All authors report that this work was supported in part by a grant from the National Cancer Institute (1R21CA235153). F.F.L. reports that the NYS Cancer Registry was supported in part by the Centers for Disease Control and Prevention’s National Program of Cancer Registries through cooperative agreement 6NU58DP006309 awarded to the New York State Department of Health and by Contract 75N91018D00005 (Task Order 75N91018F00001) from the National Cancer Institute, National Institutes of Health. The authors have no other conflicts of interest to declare., (2023 Journal of Thoracic Disease. All rights reserved.)

The range of particle sizes typically present in combustion flue gas complicates predictions of gas-particle mass transfer processes. This complexity is amplified within electrostatic precipitators where particle motion, abundance, and mass transfer characteristics are size dependent. The present study illustrates the utility of replacing explicit representations of particle size distributions in simulations of electrostatic precipitators with an equivalent loading of monodisperse aerosols of diameter chosen to reproduce the same gas-particle mass transfer characteristics. Computational times are reduced by an order of magnitude using this approach, facilitating future incorporation of multiple particle types or heterogeneous chemical kinetics. [ABSTRACT FROM AUTHOR]

This study represents an analysis of the effect of exposure to ambient ozone and toxic air releases on hospitalization for asthma among children in Harris County, Texas. Our study identified temporal and spatial variations in asthma hospitalization across the study region and explored the combined effect of exposure to ambient ozone and air toxics on asthma hospitalization. Asthma hospitalization hot spots and clusters were mostly not located on zip codes with reported high quantities of total air releases of chemical pollutants. There was no significant interaction between ambient ozone exposure and toxic air releases relative to asthma hospitalization. The major predictor of asthma hospitalization was season, with hospitalization rate per 10,000 people for asthma being highest in winter period when ozone levels are usually lowest. [ABSTRACT FROM AUTHOR]

Air toxics are airborne pollutants known or suspected to cause cancer or other serious health effects, including certain volatile organic compounds (VOCs), prioritized by the US Environmental Protection Agency (EPA). While several EPA-designated air toxics are monitored at a subset of Canadian National Air Pollution Surveillance (NAPS) sites, Canada has no specific 'air toxics' control priorities. Although pulp and paper (P&P) mills are major industrial emitters of air pollutants, few studies quantified the spectrum of air quality exposures. Moreover, most NAPS monitoring sites are in urban centers; in contrast, rural NAPS sites are sparse with few exposure risk records. The objective of this pilot study was to investigate prioritized air toxic ambient VOC concentrations using NAPS hourly emissions data from a rural Pictou, Nova Scotia Kraft P&P town to document concentration levels, and to determine whether these concentrations correlated with wind direction at the NAPS site (located southwest of the mill). Publicly accessible Environment and Climate Change Canada data (VOC concentrations [Granton NAPS ID: 31201] and local meteorological conditions [Caribou Point]) were examined using temporal (2006-2013) and spatial analytic methods. Results revealed several VOCs (1,3-butadiene, benzene, and carbon tetrachloride) routinely exceeded EPA air toxics-associated cancer risk thresholds. 1,3-Butadiene and tetrachloroethylene were significantly higher ( p < 0.05) when prevailing wind direction blew from the northeast and the mill towards the NAPS site. Conversely, when prevailing winds originated from the southwest towards the mill, higher median VOC air toxics concentrations at the NAPS site, except carbon tetrachloride, were not observed. Despite study limitations, this is one of few investigations documenting elevated concentrations of certain VOCs air toxics to be associated with P&P emissions in a community. Findings support the need for more research on the extent to which air toxics emissions exist in P&P towns and contribute to poor health in nearby communities. [ABSTRACT FROM AUTHOR]

With concern about levels of air pollutants in recent years in the Capital Region of Alberta, an investigation of ambient concentrations, sources and potential human health risk of hazardous air pollutants (HAPs) or air toxics was undertaken in the City of Edmonton over a 5-year period (2009–2013). Mean concentrations of individual HAPs in ambient air including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and trace metals ranged from 0.04 to 1.73 μg/m 3 , 0.01–0.54 ng/m 3 , and 0.05–3.58 ng/m 3 , respectively. Concentrations of benzene, naphthalene, benzo( a )pyrene (BaP), arsenic, manganese and nickel were far below respective annual Alberta Ambient Air Quality Objectives. Carcinogenic and non-carcinogenic risk of air toxics were also compared with risk levels recommended by regulatory agencies. Positive matrix factorization identified six air toxics sources with traffic as the dominant contributor to total HAPs (4.33 μg/m 3 , 42%), followed by background/secondary organic aerosol (SOA) (1.92 μg/m 3 , 25%), fossil fuel combustion (0.92 μg/m 3 , 11%). On high particulate air pollution event days, local traffic was identified as the major contributor to total HAPs compared to background/SOA and fossil fuel combustion. Carcinogenic risk values of traffic, background/SOA and metals industry emissions were above the USEPA acceptable level (1 × 10 −6 ), but below a tolerable risk (1 × 10 −4 ) and Alberta benchmark (1 × 10 −5 ). These findings offer useful preliminary information about current ambient air toxics levels, dominant sources and their potential risk to public health; and this information can support policy makers in the development of appropriate control strategies if required. [ABSTRACT FROM AUTHOR]

On 9 February 2014, embers from a nearby grass/shrub fire spotted into an unused part of the Hazelwood open-cut brown coal mine located in the Latrobe Valley of Victoria, Australia and started a fire that spread rapidly and extensively throughout the mine under strong south-westerly winds and burned over a period of 45 days. The close proximity of the town to the coal mine and the low buoyancy of the smoke plume led to the accumulation of dense smoke levels in the township of Morwell (population of 14,000) particularly under south-westerly winds. A maximum daily PM 2.5 concentration of 731 μg m −3 and 8-h CO concentration of 33 ppm were measured at Morwell South, the closest residential area located approximately 500 m from the mine. These concentrations were significantly higher than national air quality standards. Air quality monitoring undertaken in the Latrobe Valley showed that smoke from the Hazelwood mine fire affected a wide area, with particle air quality standards also exceeded in Traralgon (population of 25,000) located approximately 13 km from the mine. Pollutant levels were significantly elevated in February, decreased in March once the fire abated and then returned to background levels once the fire was declared safe at the end of March. While the smoke extent was of a similar order of magnitude to other major air pollution events worldwide, a closer look at emissions ratios showed that the open combustion of lignite brown coal in the Hazelwood mine was different to open combustion of biomass, including peat. It suggested that the dominant combustion process was char combustion. While particle and carbon monoxide monitoring started approximately 4 days after the fire commenced when smoke levels were very high, targeted monitoring of air toxics only began on 26 February (17 days after the fire) when smoke levels had subsided. Limited research on emission factors from open-cut coal mine fires make it difficult to assess the likely concentrations of air toxics emitted during the initial more intense period of the fire. [ABSTRACT FROM AUTHOR]

A sol-gel-based TiO2-coated photo-catalytic device was developed and demonstrated for field applications for controlling volatile organic compounds (VOCs) in three varying indoor environments: (i) laboratory using benzene (efficiency >99%), (ii) conference room of an industry producing organic solvents (mono, di, and tri chloro benzene) (efficiency >70%), and (iii) chemistry laboratory using multiple solvents/VOCs (efficiency >88%). The VOC degradation rate constant for coexisting multiple VOC was estimated to be 1.06/min/m2, which was about 34% less than that of benzene. A VOC mass balance model was developed to describe interaction between indoor air and kinetics of VOC degradation to estimate required extent of treatment for safe VOC concentration in the indoor air. Toxic intermediates of benzene that were adsorbed on the catalyst surface (solid phase) were identified and quantified with GC/GC-MS (gas chromatography-mass spectroscopy). Intermediates accounted for less than 5% of the total mass of benzene treated. The overall hazard index of the toxic intermediates released from regeneration of catalyst is estimated in the range 0.11-0.74, which is less than 1, and, thus, poses no significant risk to the occupants. [ABSTRACT FROM AUTHOR]

Hypertension is a leading risk factor for disease burden, with more than 200 million disability-adjusted life-years attributed to high blood pressure in 2015. While outdoor air pollution is associated with cardiovascular disease, the joint effect of exposure to air pollution from combustion products on hypertension has rarely been studied. We conducted a cross-sectional analysis to explore the association between combustion-related air pollution and hypertension. Census-tract levels of ambient concentrations of nine fossil-fuel and combustion-related air toxics (biphenyl, naphthalene, polycyclic organic matter, diesel emissions, 1,3-butadiene, acetaldehyde, benzene, acrolein, and formaldehyde) from the 2005 National Air Toxics Assessment database and NO 2 from 2005 monitoring data were linked to baseline residential addresses of 47,467 women in the Sister Study cohort. Hypertension at enrollment (2003–2009) was defined as high systolic (≥140 mm Hg) or diastolic (≥90 mm Hg) blood pressure or taking antihypertensive medication. We used log-binomial regression and quantile-based g-computation to estimate the individual and joint effects of fossil-fuel and combustion-related air pollution on hypertension. Comparing the highest to lowest quartiles, diesel emissions (prevalence ratio (PR) = 1.05, 95% confidence interval (CI) = 1.01,1.08), 1,3-butadiene (PR = 1.04, 95%CI = 1.00,1.07), acetaldehyde (PR = 1.08, 95%CI = 1.04,1.12), benzene (PR = 1.05, 95%CI = 1.02,1.08), formaldehyde (PR = 1.08, 95%CI = 1.04,1.11), and NO 2 (PR = 1.08, 95%CI = 1.05,1.12) were individually associated with higher prevalence of hypertension. The PR for the joint effect of increasing all ambient air toxics and NO 2 by one quartile was 1.02 (95%CI = 1.01,1.04). Associations varied by race/ethnicity, with stronger associations observed among women reporting races/ethnicities (Hispanic/Latina, non-Hispanic Black and other) other than non-Hispanic White. In conclusion, we found that air pollution from fossil fuel and combustion may be a risk factor for hypertension. [Display omitted] • This large-scale study considered combustion-related air pollution and hypertension. • Diesel emissions, VOCs and NO 2 were associated with higher risk of hypertension. • Associations varied by race/ethnicity and geographic region. • The air toxics/NO2 mixture was associated with hypertension. • The joint effect of the mixture was stronger among people other than non-Hispanic White. [ABSTRACT FROM AUTHOR]

The objective of this research was to determine if prenatal exposure to two common urban air pollutants, diesel and perchloroethylene, affects children's 3rd grade standardized test scores in mathematics and English language arts (ELA). Exposure estimates consisted of annual average ambient concentrations of diesel particulate matter and perchloroethylene obtained from the Environmental Protection Agency's 1996 National Air Toxics Assessment for the residential census tract at birth. Outcome data consisted of linked birth and educational records for 201,559 singleton, non-anomalous children born between 1994 and 1998 who attended New York City public schools. Quantile regression models were used to estimate the effects of these exposures on multiple points within the continuous distribution of standardized test scores. Modified Poisson regression models were used to calculate risk ratios (RR) and 95% confidence intervals (CI) of failing to meet curricula standards, an indicator derived from test scores. Models were adjusted for a number of maternal, neighborhood and childhood factors. Results showed that math scores were approximately 6% of a standard deviation lower for children exposed to the highest levels of both pollutants as compared to children with low levels of both pollutants. Children exposed to high levels of both pollutants also had the largest risk of failing to meet math test standards when compared to children with low levels of exposure to the pollutants (RR 1.10 95%CI 1.07,1.12 RR high perchloroethylene only 1.03 95%CI 1.00,1.06; RR high diesel PM only 1.02 95%CI 0.99,1.06). There was no association observed between exposure to the pollutants and failing to meet ELA standards. This study provides preliminary evidence of associations between prenatal exposure to urban air pollutants and lower academic outcomes. Additionally, these findings suggest that individual pollutants may additively impact health and point to the need to study the collective effects of air pollutant mixtures. Key Words: air toxics, academic outcomes, urban health, tetrachloroethylene, air pollutant mixtures [ABSTRACT FROM AUTHOR]

Background: Traffic exhaust, refineries and industrial facilities are major sources of air toxics identified by the U.S. Environmental Protection Agency (U.S. EPA) for their potential risk to human health. In utero and early life exposures to air toxics such as benzene and 1,3-butadiene, which are known leukemogens in adults, may play an etiologic role in childhood leukemia that comprises the majority of pediatric cancers. We conducted a population based case-control study to examine individual effects of benzene, 1,3-butadiene and polycyclic organic matter (POM) in ambient residential air on acute lymphocytic leukemia (ALL) diagnosed in children under age 5 years in Texas from 1995-2011.Methods: Texas Cancer Registry cases were linked to birth records and then were frequency matched by birth month and year to 10 population-based controls. Maternal and infant characteristics from birth certificates were abstracted to obtain information about potential confounders. Modelled estimates of benzene, 1,3-butadiene and POM exposures at the census tract level were assigned by linking geocoded maternal addresses from birth certificates to U.S. EPA National-Scale Air Toxics Assessment data for single and co-pollutant statistical analyses. Mixed-effects logistic regression models were applied to evaluate associations between air toxics and childhood leukemia.Results: In adjusted single pollutant models, odds of childhood leukemia among mothers with the highest ambient air exposures compared to those in the lowest quartile were 1.11 (95 % CI: 0.94-1.32) for POM, 1.17 (95 % CI: 0.98-1.39) for benzene and 1.29 (95 % CI: 1.08-1.52) for 1,3-butadiene. In co-pollutant models, odds ratios for childhood leukemia remained elevated for 1,3-butadiene but were close to the null value for benzene and POM.Conclusions: We observed positive associations between 1,3-butadiene and childhood leukemia in single and co-pollutant models whereas effect estimates from single pollutant models were diminished for benzene and POM in co-pollutant models. Early life exposure to 1,3-butadiene rather than benzene or POM appears to increase early childhood risk of acute lymphocytic leukemia. [ABSTRACT FROM AUTHOR]

Despite the modernization of computational techniques, atmospheric dispersion modeling remains a complicated task as it involves the use of large amounts of interrelated data with wide variability. The continuously growing list of regulated air pollutants also increases the difficulty of this task. To address these challenges, this study aimed to develop a screening procedure for a long-term exposure scenario by generating a site-specific lookup table of hourly averaged dispersion factors ( χ / Q ), which could be evaluated by downwind distance, direction, and effective plume height only. To allow for such simplification, the average plume rise was weighted with the frequency distribution of meteorological data so that the prediction of χ/Q could be decoupled from the meteorological data. To illustrate this procedure, 20 receptors around a high-tech complex in Taiwan were selected. Five consecutive years of hourly meteorological data were acquired to generate a lookup table of χ/Q , as well as two regression formulas of plume rise as functions of downwind distance, buoyancy flux, and stack height. To calculate the concentrations for the selected receptors, a six-step Excel algorithm was programmed with four years of emission records and 10 most critical toxics were screened out. A validation check using Industrial Source Complex (ISC3) model with the same meteorological and emission data showed an acceptable overestimate of 6.7% in the average concentration of 10 nearby receptors. The procedure proposed in this study allows practical and focused emission management for a large industrial complex and can therefore be integrated into an air quality decision-making system. [ABSTRACT FROM AUTHOR]

The Benzene and other Toxics Exposure (BEE-TEX) field study was an experimental campaign designed to demonstrate novel methods for measuring ambient concentrations of hazardous air pollutants (HAPs) in real time and to attribute these concentrations to quantified releases from specific emission points in industrial facilities while operating outside facility fence lines. BEE-TEX was conducted in February 2015 at three neighboring communities in the Houston Ship Channel of Texas, where a large number of petrochemical facilities are concentrated. The novel technologies deployed during BEE-TEX included: (1) tomographic remote sensing based on differential optical absorption spectroscopy; (2) real-time broadcasting of ambient air monitoring data over the World Wide Web; (3) real-time source attribution and quantification of HAP emissions based on either tomographic or mobile measurement platforms; and (4) the use of cultured human lung cells in vitro as portable indicators of HAP exposure. [ABSTRACT FROM AUTHOR]

Background: Autism spectrum disorders (ASD) constitute a major public health problem affecting one in 68 children. There is little understanding of the causes of ASD despite its serious social impact. Air pollution contains many toxicants known to have adverse effects on the fetus. We conducted a population based case-control study in southwestern Pennsylvania to estimate the association between ASD and 2005 US EPA modeled NATA (National Air Toxics Assessment) levels for 30 neurotoxicants.Methods: A total of 217 ASD cases born between 2005 and 2009 were recruited from local ASD diagnostic and treatment centers. There were two different control groups: 1) interviewed controls (N = 224) frequency matched by child's year of birth, sex and race with complete residential histories from prior to pregnancy through the child's second birthday, and 2) 5,007 controls generated from a random sample of birth certificates (BC controls) using residence at birth. We used logistic regression analysis comparing higher to first quartile of exposure to estimate odds ratios (ORs) and 95% confidence intervals (CI), adjusting for mother's age, education, race, smoking status, child's year of birth and sex.Results: Comparing fourth to first quartile exposures for all births, the adjusted OR for styrene was 2.04 (95% CI = 1.17-3.58, p = 0.013) for the interviewed case-control analysis and 1.61 (95% CI = 1.08-2.40, p = 0.018) for the BC analysis. In the BC comparison, chromium also exhibited an elevated OR of 1.60 (95% CI = 1.08-2.38, p = 0.020), which was similarly elevated in the interviewed analysis (OR = 1.52, 95% CI = 0.87-2.66). There were borderline significant ORs for the BC comparison for methylene chloride (OR = 1.41, 95% CI = 0.96-2.07, p = 0.082) and PAHs (OR = 1.44, 95% CI = 0.98-2.11, p = 0.064).Conclusions: Living in areas with higher levels of styrene and chromium during pregnancy was associated with increased risk of ASD, with borderline effects for PAHs and methylene chloride. These results are consistent with other studies. It is unclear, however, whether these chemicals are risk factors themselves or if they reflect the effect of a mixture of pollutants. Future work should include improved spatiotemporal estimates of exposure to air toxics, taking into account the dynamic movement of individuals during daily life. [ABSTRACT FROM AUTHOR]

Chemical absorption was employed for the harmless treatment of sulfuryl fluoride (SO2F2) in the simulated residual fumigant. SO2F2 was absorbed by sodium hydroxide (NaOH) solution in a packed column. Effects of spray density, gas flow rate, concentration of NaOH solution, and inlet SO2F2 volume concentration on SO2F2 removal efficiency were investigated at room temperature. It was found that SO2F2 could be removed completely when inlet SO2F2 volume concentration, spray density, gas flow rate, and NaOH concentration were 0.50%, 12 m3/(m2 · h), 0.12 m3/h, and 0.68 mol/L, respectively. According to the two-film theory, a mathematical model based on Onda correlations was developed to describe the removal efficiency of SO2F2. Comparison between the experimental data and the calculated data proved that the predictability of the proposed model was within the maximum deviation of 8.0%. Aqueous NaOH solution after absorption was analyzed. It was found that the SO2F2 was fixed and converted to NaF, NaSO3F, and Na2SO4. [ABSTRACT FROM AUTHOR]