Characterizing the PM2.5-related health benefits of emission reductions for 17 industrial, area and mobile emission sectors across the U.S.

Background: Air pollution benefits assessments tend to be time and resource intensive. Reduced-form approaches offer computational efficiency, but may introduce uncertainty. Some reduced-form approaches apply simplified air quality models, which may not capture the complex non-linear chemistry governing the formation of certain pollutants such as PM2.5. Other approaches apply the results of sophisticated photochemical modeling, but characterize only a small number of source types in a limited geographic area. Methods: We apply CAMx source apportionment photochemical modeling, coupled with a PC-based human health benefits software program, to develop a suite of PM2.5 benefit per ton estimates. These per-ton estimates relate emission changes to health impacts and monetized benefits for 17 sectors across the continental U.S., including Electricity Generating Units (EGU), mobile, area and industrial point sources. Results: The benefit per ton of reducing directly emitted PM2.5 is about an order of magnitude larger than reducing emissions of PM2.5 precursor emissions. On a per-ton basis, the value of reducing directly emitted PM2.5 and PM2.5 precursors in 2005 ranges between approximately $1300 (2010$) for reducing a ton of NOx from Ocean-Going Vessels to about $450,000 (2010$) for reducing a ton of directly emitted PM2.5 from Iron and Steel facilities. The benefit per ton estimates for 2016 are generally higher than the 2005 estimates. The values estimated here are generally comparable with those generated using photochemical modeling, but larger than those calculated using simplified air quality models. Conclusions: Our approach characterizes well the per-ton benefits of reducing emissions from a broad array of 17 industrial point, EGU and mobile sectors, while our use of photochemical air quality modeling gives us greater confidence that we have accounted for the non-linear chemistry governing PM2.5 formation. The resulting benefit per-ton estimates thus represent a compromise between approaches that may simplify the treatment of PM2.5 air quality formation and those techniques that are based in photochemical modeling but account for only a small number of emission sources. Published by Elsevier Ltd.