Explore the vast range of titles available.

Fine particulate air pollution (PM2.5; particulate matter 2.5 μm or less in diameter) is thought to contribute to acute respiratory morbidity in part through oxidative stress. To examine the association between PM2.5 oxidative burden and emergency room visits for respiratory illnesses. We conducted a case-crossover study in Ontario, Canada between 2004 and 2011, including 127,836 cases of asthma, 298,751 cases of chronic obstructive pulmonary disease, and more than 1.1 million cases of all respiratory illnesses. Daily air pollution data were collected from ground monitors, and city-level PM2.5 oxidative potential was measured on the basis of a synthetic respiratory tract lining fluid containing the antioxidants glutathione and ascorbate. Conditional logistic regression was used to estimate associations between air pollution concentrations and emergency room visits, adjusting for time-varying covariates. Three-day mean PM2.5 concentrations were consistently associated with emergency room visits for all respiratory illnesses. Among children (<9 yr), each interquartile change (5.92 μg/m(3)) in 3-day mean PM2.5 was associated with a 7.2% (95% confidence interval, 4.2-10) increased risk of emergency room visits for asthma. Glutathione-related oxidative potential modified the impact of PM2.5 on emergency room visits for respiratory illnesses (P = 0.001) but only at low concentrations (≤10 μg/m(3)). Between-city differences in ascorbate-related oxidative potential did not modify the impact of PM2.5 on respiratory outcomes. Between-city differences in glutathione-related oxidative potential may modify the impact of PM2.5 on acute respiratory illnesses at low PM2.5 concentrations. This may explain in part how small changes in ambient PM2.5 mass concentrations can contribute to acute respiratory morbidity in low-pollution environments.

Background Regional differences in the oxidative potential of fine particulate air pollution (PM 2.5 ) may modify its impact on the risk of myocardial infarction. Methods A case-crossover study was conducted in 16 cities in Ontario, Canada to evaluate the impact of regional PM 2.5 oxidative potential on the relationship between PM 2.5 and emergency room visits for myocardial infarction. Daily air pollution and meteorological data were collected between 2004 and 2011 from provincial monitoring sites and regional estimates of glutathione (OP GSH ) and ascorbate-related (OP AA ) oxidative potential were determined using an acellular assay based on a synthetic respiratory tract lining fluid. Exposure variables for the combined oxidant capacity of NO 2 and O 3 were also examined using their sum (O x ) and a weighted average (O x wt ) based on their redox potentials. Results In total, 30,101 cases of myocardial infarction were included in the analysis. For regions above the 90 th percentile of OP GSH each 5 μg/m 3 increase in same-day PM 2.5 was associated with a 7.9 % (95 % CI: 4.1, 12) increased risk of myocardial infarction whereas a 4.1 % (95 % CI: 0.26, 8.0) increase was observed in regions above the 75 th percentile and no association was observed below the 50 th percentile ( p -interaction = 0.026). A significant 3-way interaction was detected with the strongest associations between PM 2.5 and myocardial infarction occurring in areas with high regional OP GSH and high O x wt ( p -interaction < 0.001). Conclusions Regional PM 2.5 oxidative potential may modify the impact of PM 2.5 on the risk of myocardial infarction. The combined oxidant capacity of NO 2 and O 3 may magnify this effect.

BackgroundAmbient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial.ObjectiveTo evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits.MethodsWe conducted a case-crossover study of 78 255 COVID-19 ED visits in Alberta and Ontario, Canada between 1 March 2020 and 31 March 2021. Daily air pollution data (ie, fine particulate matter with diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO2) and ozone were assigned to individual case of COVID-19 in 10 km × 10 km grid resolution. Conditional logistic regression was used to estimate associations between air pollution and ED visits for COVID-19.ResultsCumulative ambient exposure over 0–3 days to PM2.5 (OR 1.010; 95% CI 1.004 to 1.015, per 6.2 µg/m3) and NO2 (OR 1.021; 95% CI 1.015 to 1.028, per 7.7 ppb) concentrations were associated with ED visits for COVID-19. We found that the association between PM2.5 and COVID-19 ED visits was stronger among those hospitalised following an ED visit, as a measure of disease severity, (OR 1.023; 95% CI 1.015 to 1.031) compared with those not hospitalised (OR 0.992; 95% CI 0.980 to 1.004) (p value for effect modification=0.04).ConclusionsWe found associations between short-term exposure to ambient air pollutants and COVID-19 ED visits. Exposure to air pollution may also lead to more severe COVID-19 disease.

Prenatal exposure to fine particulate matter air pollution with aerodynamic diameter ≤2.5 μm (PM ) has been associated with preterm delivery and low birth weight (LBW), but few studies have examined possible effect modification by oxidative potential. The aim of this study was to evaluate if regional differences in the oxidative potential of PM modify the relationship between PM and adverse birth outcomes. A retrospective cohort study was conducted using 196,171 singleton births that occurred in 31 cities in the province of Ontario, Canada, from 2006 to 2012. Daily air pollution data were collected from ground monitors, and city-level PM oxidative potential was measured. We used random-effects meta-analysis to combine the estimates of effect from regression models across cities on preterm birth, term LBW, and term birth weight and used meta-regression to evaluate the modifying effect of PM oxidative potential. An interquartile increase (2.6 μg/m ) in first-trimester PM was positively associated with term LBW among women in the highest quartile of glutathione (GSH)-related oxidative potential [odds ratio (OR)=1.28; 95% confidence interval (CI): 1.10, 1.48], but not the lowest quartile (OR=0.99; 95% CI: 0.87, 1.14; -interaction=0.03). PM on the day of delivery also was associated with preterm birth among women in the highest quartile of GSH-related oxidative potential [hazard ratio (HR)=1.02; 95% CI: 1.01, 1.04], but not the lowest quartile [HR=0.97; 95% CI: 0.95, 1.00; -interaction=0.04]. Between-city differences in ascorbate (AA)-related oxidative potential did not significantly modify associations with PM . Between-city differences in GSH-related oxidative potential may modify the impact of PM on the risk of term LBW and preterm birth. https://doi.org/10.1289/EHP2535.

AbstractBackgroundExposure to traffic-related air pollution (TRAP) is associated with increased incidence of several cardiopulmonary diseases. The elevated TRAP exposures of commuting environments can result in significant contributions to daily exposures.ObjectivesTo assess the personal TRAP exposures (UFPs, BC, PM2.5, and PM10) of the bus transit systems of Toronto, Ottawa, and Vancouver, Canada. Personal exposure models estimated the contribution of bus commuting to daily TRAP exposures. Associations between bus type and riding exposures and bus stop/station type and waiting exposures were estimated.ResultsBus commuting (4.6% of the day) contributed ~59%(SD = 15%), 60%(SD = 20%), and 57%(SD = 18%) of daily PM2.5-Ba and 70%(SD = 19%), 64%(SD = 15%), and 70%(SD = 15%) of daily PM2.5-Fe, in Toronto, Ottawa, and Vancouver, respectively. Enclosed bus stations were found to be hotspots of PM2.5 and BC. Buses with diesel particulate filters (DPFs) and hybrid diesel/electric propulsion were found to have significantly lower in-bus PM2.5, UFP, and BC relative to 1983–2003 diesel buses in each city with the exception of UFP in Vancouver.SignificancePersonal exposures for traffic-related air pollutants were assessed for three Canadian bus transit systems. In each system, bus commuting was estimated to contribute significantly toward daily exposures of fine-fraction Ba and Fe as well as BC. Exposures while riding were associated with bus type for several pollutants in each city. These associations suggest the use of hybrid diesel/electric buses equipped with diesel particulate filters have improved air quality for riders.

ObjectivesAccumulated evidence implies that night shift work may trigger liver dysfunction. Non-alcoholic fatty liver (NAFL) is suggested to be a necessary mediator in this process. This study aimed to examine the relationship between night shift work and elevated level of alanine transaminase (e-ALT) of workers and investigate the potential mediation effect of NAFL.MethodsThis study included all male workers from the baseline survey of a cohort of night shift workers. Information on demographics, lifestyle and lifetime working schedule was collected by face-to-face interview. Liver sonography was used to identify NAFL cases. Serum ALT level was detected by an automatic biochemical analyser. e-ALT was defined as ALT >40 U/L. Logistic regression models were used to evaluate ORs, and mediation analysis was employed to examine the mediation effect.ResultsAmong 4740 male workers, 39.5% were night shift workers. Night shift workers had an increased risk of e-ALT (OR, 1.19, 95% CI 1.00 to 1.42). With the increase in night shift years, the OR of e-ALT increased from 1.03 (95% CI 0.77 to 1.36) to 1.60 (95% CI 1.08 to 2.39) among workers without NAFL. A similar trend was not found among workers with NAFL. In addition, no significant mediation effect of NAFL in the association between night shift work and e-ALT was found.ConclusionsNight shift work is positively associated with abnormal liver function, in particular among workers without NAFL. Shift work involving circadian disruption is likely to exert a direct effect on liver dysfunction rather than rely on the mediation effect of NAFL.

Since torcetrapib, an inhibitor of cholesteryl ester transfer protein, markedly increases levels of high-density lipoprotein cholesterol and lowers levels of low-density lipoprotein cholesterol, in principle it might have a beneficial effect on atherosclerosis. However, in this clinical trial, torcetrapib had no beneficial effect on carotid atherosclerosis, as assessed by ultrasonographic measurement of carotid intima–media thickness. The reasons for this finding are unclear, but the drug did increase blood pressure slightly. In this clinical trial, torcetrapib had no beneficial effect on carotid atherosclerosis, as assessed by ultrasonographic measurement of carotid intima–media thickness.Published Online March 26, 2007 (DOI:10.1056/NEJMoa071359) Guidelines for the prevention and management of cardiovascular disease focus on reducing levels of low-density lipoprotein (LDL) cholesterol by means of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (collectively referred to as statins). 1 , 2 However, recent meta-analyses have shown that even with the most aggressive treatment, 3 , 4 these drugs reduce the risk of a major coronary event by only 30%. 5 This finding, combined with an estimation that mortality from cardiovascular causes will increase worldwide by 90% by the year 2020, as compared with that in 1990, 6 illustrates the need for new efficacious treatments. A review of four large, prospective epidemiologic studies . . .

The province of Alberta, Canada, is home to three oil sands regions which, combined, contain the third largest deposit of oil in the world. Of these, the Athabasca oil sands region is the largest. As part of Environment and Climate Change Canada's program in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring program, concentrations of trace elements in PM2. 5 (particulate matter smaller than 2.5 µm in diameter) were measured through two campaigns that involved different methodologies: a long-term filter campaign and a short-term intensive campaign. In the long-term campaign, 24 h filter samples were collected once every 6 days over a 2-year period (December 2010–November 2012) at three air monitoring stations in the regional municipality of Wood Buffalo. For the intensive campaign (August 2013), hourly measurements were made with an online instrument at one air monitoring station; daily filter samples were also collected. The hourly and 24 h filter data were analyzed individually using positive matrix factorization. Seven emission sources of PM2. 5 trace elements were thereby identified: two types of upgrader emissions, soil, haul road dust, biomass burning, and two sources of mixed origin. The upgrader emissions, soil, and haul road dust sources were identified through both the methodologies and both methodologies identified a mixed source, but these exhibited more differences than similarities. The second upgrader emissions and biomass burning sources were only resolved by the hourly and filter methodologies, respectively. The similarity of the receptor modeling results from the two methodologies provided reassurance as to the identity of the sources. Overall, much of the PM2. 5-related trace elements were found to be anthropogenic, or at least to be aerosolized through anthropogenic activities. These emissions may in part explain the previously reported higher levels of trace elements in snow, water, and biota samples collected near the oil sands operations.

Biomass burning organic aerosol (BBOA) can be emitted from natural forest fires and human activities such as agricultural burning and domestic energy generation. BBOA is strongly associated with atmospheric brown carbon (BrC) that absorbs near-ultraviolet and visible light, resulting in significant impacts on regional visibility degradation and radiative forcing. The mixing state of BBOA can play a critical role in the prediction of aerosol optical properties. In this work, single-particle measurements from a Soot-Particle Aerosol Mass Spectrometer coupled with a light scattering module (LS-SP-AMS) were performed to examine the mixing state of BBOA, refractory black carbon (rBC), and potassium (K, a tracer for biomass burning aerosol) in an air mass influenced by wildfire emissions transported from northern Québec to Toronto, representing aged biomass burning plumes. Cluster analysis of single-particle measurements identified five BBOA-related particle types. rBC accounted for 3–14 wt % of these particle types on average. Only one particle type exhibited a strong ion signal for K+, with mass spectra characterized by low molecular weight organic species. The remaining four particle types were classified based on the apparent molecular weight of the BBOA constituents. Two particle types were associated with low potassium content and significant amounts of high molecular weight (HMW) organic compounds. Our observations indicate non-uniform mixing of particles within a biomass burning plume in terms of molecular weight and illustrate that HMW BBOA can be a key contributor to low-volatility BrC observed in BBOA particles. The average mass absorption efficiency of low-volatility BBOA is about 0.8–1.1 m2 g−1 based on a theoretical closure calculation. Our estimates indicate that low-volatility BBOA contributes ∼ 33–44 % of thermo-processed particle absorption at 405 nm; and almost all of the BBOA absorption was associated with low-volatility organics.

Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is inferred from these values that dry deposition is the dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall and spring, possibly due to enhanced scavenging by mixed-phase clouds. Black carbon aerosol was the least efficiently deposited species to the snow.