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Numerous scientific upgrades to the representation of secondary organic aerosol (SOA) are incorporated into the Community Multiscale Air Quality (CMAQ) modeling system. Additions include several recently identified SOA precursors: benzene, isoprene, and sesquiterpenes; and pathways: in-cloud oxidation of glyoxal and methylglyoxal, particle-phase oligomerization, and acid enhancement of isoprene SOA. NOx-dependent aromatic SOA yields are also added along with new empirical measurements of the enthalpies of vaporization and organic mass-to-carbon ratios. For the first time, these SOA precursors, pathways and empirical parameters are included simultaneously in an air quality model for an annual simulation spanning the continental U.S. Comparisons of CMAQ-modeled secondary organic carbon (OCsec) with semiempirical estimates screened from 165 routine monitoring sites across the U.S. indicate the new SOA module substantially improves model performance. The most notable improvement occurs in the central and southeastern U.S. where the regionally averaged temporal correlations (r) between modeled and semiempirical OCsec increase from -0.5 to 0.8 and -0.3 to 0.8, respectively, when the new SOA module is employed. Wintertime OCsec results improve in all regions of the continental U.S. and the seasonal and regional patterns of biogenic SOA are better represented. [ABSTRACT FROM AUTHOR]

The article discusses the cohort study conducted by the Health Effects if Arsenic Longitudinal Study (HEALS) on the all-cause and chronic disease mortalities due to arsenic exposure from drinking water in Bangladesh. It notes that more than 20% of deaths could be attributed to well arsenic concentrations greater than 10.0 micrograms/liter. The study indicates that out of 35-77 million inhabitants who have been drinking contaminated well water in the country, 55% consumed amounts greater than 50 micrograms/liter. It mentions that chronic exposure through drinking water was associated with increase in mortality rate, and solutions and resources are needed to mitigate the resulting health effect on the mortality rate.

This paper is Part II in a pair of papers that examines the results of the Community Multiscale Air Quality (CMAQ) model version 4.5 (v4.5) and discusses the potential explanations for the model performance characteristics seen. The focus of this paper is on fine particulate matter (PM2.5) and its chemical composition. Improvements made to the dry deposition velocity and cloud treatment in CMAQ v4.5 addressing compensating errors in 36-km simulations improved particulate sulfate (SO4 2−) predictions. Large overpredictions of particulate nitrate (NO3 −) and ammonium (NH4 +) in the fall are likely due to a gross overestimation of seasonal ammonia (NH3) emissions. Carbonaceous aerosol concentrations are substantially underpredicted during the late spring and summer months, most likely due, in part, to a lack of some secondary organic aerosol (SOA) formation pathways in the model. Comparisons of CMAQ PM2.5 predictions with observed PM2.5 mass show mixed seasonal performance. Spring and summer show the best overall performance, while performance in the winter and fall is relatively poor, with significant overpredictions of total PM2.5 mass in those seasons. The model biases in PM2.5 mass cannot be explained by summing the model biases for the major inorganic ions plus carbon. Errors in the prediction of other unspeciated PM2.5 (PMOther) are largely to blame for the errors in total PM2.5 mass predictions, and efforts are underway to identify the cause of these errors. [Copyright &y& Elsevier]

Recent studies have focused on the chemistry of tropospheric halogen species which are able to deplete tropospheric ozone (O 3). In this study, the effect of bromine and iodine chemistry on tropospheric O 3 within the annual cycle in Asia-Pacific is investigated using the CMAQ model with the newly embedded bromine and iodine chemistry and a blended and customized emission inventory considering marine halogen emission. Results indicate that the vertical profiles of bromine and iodine species show distinct features over land/ocean and daytime/nighttime, related to natural and anthropogenic emission distributions and photochemical reactions. The halogen-mediated O 3 loss has a strong seasonal cycle, and reaches a maximum of −15.9 ppbv (−44.3%) over the ocean and −13.4 ppbv (−38.9%) over continental Asia among the four seasons. Changes in solar radiation, dominant wind direction, and nearshore chlorophyll-a accumulation all contribute to these seasonal differences. Based on the distances to the nearest coastline, the onshore and offshore features of tropospheric O 3 loss caused by bromine and iodine chemistry are studied. Across a coastline-centric 400-km-wide belt from onshore to offshore, averaged maximum gradient of O 3 loss reaches 1.1 ppbv/100 km at surface level, while planetary boundary layer (PBL) column mean of O 3 loss is more moderate, being approximately 0.7 ppbv/100 km. Relative high halogen can be found over Tibetan Plateau (TP) and the largest O 3 loss (approximately 4–5 ppbv) in the PBL can be found between the western boundary of the domain and the TP. Halogens originating from marine sources can potentially affect O 3 concentration transported from the stratosphere over the TP region. As part of efforts to improve our understanding of the effect of bromine and iodine chemistry on tropospheric O 3 , we call for more models and monitoring studies on halogen chemistry and be considered further in air pollution prevention and control policy. • The vertical profiles of bromine and iodine species show distinct features over land/ocean and daytime/nighttime. • The halogen-mediated O 3 loss reaches a maximum of −15.9 ppbv (−44.3%) over ocean and −13.4 ppbv (−38.9%) over continental Asia. • Across a coastline-centric 400-km-wide belt, averaged maximum gradient of O 3 loss reaches 1.1 ppbv/100 km at surface level. • The horizontal advection of free tropospheric air from nearshore western boundary may contribute to the O 3 loss over the TP. [ABSTRACT FROM AUTHOR]

Marine biogenic dimethyl sulfide (DMS) is an important natural source of sulfur in the atmosphere, which may play an important role in air quality. In this study, the WRF-CMAQ model is employed to assess the impact of DMS on the atmospheric environment at the regional scale of eastern coastal China and urban scale of Shanghai in 2017. A national scale database of DMS concentration in seawater is established based on the historical DMS measurements in the Yellow Sea, the Bohai Sea and the East China Sea in different seasons during 2009~2017. Results indicate that the sea-to-air emission flux of DMS varies greatly in different seasons, with the highest in summer, followed by spring and autumn, and the lowest in winter. The annual DMS emissions from the Yellow Sea, the Bohai Sea and the East China Sea are 0.008, 0.059, and 0.15 Tg S a−1, respectively. At the regional scale, DMS emissions increase atmospheric sulfur dioxide (SO2) and sulfate ( SO 4 2 − ) concentrations over the East China seas by a maximum of 8% in summer and a minimum of 2% in winter, respectively. At the urban scale, the addition of DMS emissions increase the SO2 and SO 4 2 − levels by 2% and 5%, respectively, and reduce ozone (O3) in the air of Shanghai by 1.5%~2.5%. DMS emissions increase fine-mode ammonium particle concentration distribution by 4% and 5%, and fine-mode nss- SO 4 2 − concentration distributions by 4% and 9% in the urban and marine air, respectively. Our results indicate that although anthropogenic sources are still the dominant contributor of atmospheric sulfur burden in China, biogenic DMS emissions source cannot be ignored. [ABSTRACT FROM AUTHOR]

A correction is presented to the article, "A missense variant in FTCD is associated with arsenic metabolism and toxicity phenotypes in Bangladesh" which was published in a 2019 issue of the periodical.

Background: Cardiovascular mortality has risen 30 fold in South Asia yet there is little data on how socioeconomic status (SES) contributes to the rising cardiovascular disease (CVD) burden. In Bangladesh, CVD accounts for the majority of non-communicable mortality. The purpose of this study was to determine the role of SES on subclinical atherosclerosis measured as carotid intima media thickness (cIMT) in a rural Bangladesh population. Methods: cIMT was measured in 1022 participants (average age 46, 40% male) randomly selected from the Health Effects of Arsenic Longitudinal Study (HEALS), a population-based prospective cohort study based in rural Bangladesh. SES was measured with survey data as occupation type, land ownership, educational attainment, and television ownership. We assessed the association between each of these SES indicators and cIMT adjusting for potential confounders. Results: Over half of the participants received formal education (53%) and under half owned land (48%) and a television (44%). Women were primarily homemakers (95%) and men worked as factory workers (24%), laborers (18%), or in business (55%). In univariate analysis, those owning greater than one acre of land (p = 0.03), owning a television (p =0.02), or laborers and business owners when compared to factory workers had higher levels of cIMT (p<0.01). Educational attainment was not an independent predictor of cIMT (p = 0.7). In multivariate analysis after adjustment for potential confounders, men employed in the business sector had a 26.7 μm (95% CI 6.7 - 46.9, p < 0.01) significantly greater level of cIMT when compared to factory workers. The association was strongest in older men (50.8 μm, 95% CI 9.0 - 92.6, ≥50 years old compared to younger men (19.4 μm, 95% CI -2.0 - 40.9, <50 years old). Other SES indicators were not predictors of cIMT after multivariate adjustment. Conclusion: Working in the business sector was positively associated with subclinical atherosclerosis after adjustment for confounders. This finding is consistent with evidence from other developing nations suggesting that certain SES factors are independent predictors of CVD. [ABSTRACT FROM AUTHOR]

The article reports on a study conducted to find the connection between arsenic exposure and mortality from cardiovascular disease. As stated, there is a dose-response relation between arsenic exposure and mortality from cardiovascular disease which is further enhanced by cigarette smoking. The study found that arsenic exposure through drinking water also increased the risk of cardiovascular system diseases.