期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2018
卷号：115
期号：20
页码：5099-5104
DOI：10.1073/pnas.1801191115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NO x ) and carbon monoxide (CO) for 2011–2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA’s NO x emission estimates could be explained by: ( i ) growing relative contributions of industrial, area, and off-road sources, ( ii ) decreasing relative contributions of on-road gasoline, and ( iii ) slower than expected decreases in on-road diesel emissions.
