Concentrations, Sources, and Health Risks of Particulate Matter in Southeast US.: Current Status and Future Changes

Evaluation of long-term air quality trends and prediction of future air quality may help to design and demonstrate effectiveness of control strategies and guide future air quality management. As one of the six criteria air pollutants (CAPs) regulated by the US Environmental Protection Agency (EPA), particulate matter with aerodynamic diameter of 2.5 µm or less (PM2.5) is of great interests since it has adverse effects on human health, visibility and climate. This study aims to understand the current status and future changes in concentrations, sources, and health risks of PM2.5 in Southeast US. Firstly, observations were analyzed and simulation was conducted using the Community Multi-Scale Air Quality (CMAQ) model to show the historical trend from 2006 to 2015. Secondly, a statistical model was used to investigate the sources of PM2.5 in Baton Rouge based on observations as a case study. Thirdly, 16 PAHs in southeast US were simulated in four months in 2011 using modified CMAQ and compared with the levels in China and India. Lastly, the impacts of climate and emission changes on PM concentrations were examined. PM2.5 concentrations in the southeast US have been decreasing over the last decade to below 15 ug/m3 in most areas. Annual averaged PM2.5 was less than 10 ug/m3 by year 2014. Seven sources were identified, among which transportation and industrial activities were dominating in Baton Rouge, Louisiana. Atmospheric concentrations of PAHs were averaged at 0.2 ug/m3 with higher concentrations in urban and industrialized areas, eight sectors of PAHs were quantified and the incremental lifetime cancer risks (ILCR) and excess cancer cases were assessed based on national population data. The number of total excess cancer cases in the US is 5793 with a maximum of 492 in California. Analysis of air quality in future scenarios in 2050 of RCP 4.5/6.0/8.5 were grouped into three cases: No-Change-Case, Controlled-Case and Business-As-Usual-Case. Ambient PM2.5 and ozone concentrations are highly likely to increase in year 2050, as well as sulfur and nitrogen deposition. The effects from climate change and emission modifications revealed that both factors were contributing to the change of air quality in the future and emission change is more significant. Political control strategies on both climate change and emission control technologies will help to reduce air pollutant concentrations