Contributions of regional air pollutant emissions to ozone and fine particulate matter-related mortalities in eastern U.S. urban areas

摘要

Ground-level ozone and fine particulate matter (PM_(2.5)) are associated with adverse human health effects such as lung structure dysfunction, inflammation and infection, asthma, and premature deaths. This study estimated contributions of emissions of anthropogenic nitrogen oxides (NO_x), volatile organic compounds (VOCs) and sulfur dioxides (SO_2) from four regions to summertime (i.e., June, July, and August) ozone and PM_(2.5)-related mortalities in seven major Metropolitan Statistical Areas (MSAs with more than 4 million people) in the eastern United States (U.S.). A photochemical transport model, Community Multi-scale Air Quality (CMAQ) with sensitivity analyses, was applied to quantify the contribution of the regional anthropogenic emissions to ambient ozone and PM_(2.5) concentrations in the seven MSAs. The results of the sensitivity analysis, along with estimates of concentration-response from published epi-demiologic studies, were used to estimate excess deaths associated with changes in ambient daily 8-h average ozone and daily PM_(2.5) concentrations during the summer of 2007. The results show that secondary PM_(2.5) (i.e., PM_(2.5) formed in the atmosphere) had larger effects on mortality (95% confidence interval (C.I.) ranged from 700 to 3854) than ambient ozone did (95% C.I. was 470-1353) in the seven MSAs. Emissions of anthropogenic NOx, VOCs and SO_2 from the northeastern U.S. could cause up to about 2500 ozone and PM_(2.5)-related deaths in the urban areas examined in this study. The results also show that the contributions of emissions from electrical generating units (EGUs) and anthropogenic non-EGU sources to ozone-related mortality in the MSAs were similar. However, emissions from EGUs had a more significant impact on PM_(2.5)-related deaths than anthropogenic emissions from non-EGUs sources did. Anthropogenic NO_x and VOCs emissions from the regions where the MSAs are located had the most significant contributions to ozone-related mortalities in the eastern U.S. urban areas. On the other hand, PM_(2.5)-related mortalities in the MSAs were more likely to be affected by precursors transported from other regions.