Year of Publication



Martin School of Public Policy and Administration

Date Available


Executive Summary

The Environmental Protection Agency (EPA) continuously monitors six criteria pollutants that are known to have impacts on public health and welfare. One of these pollutants, fine particulate matter, or PM2.5 (which includes particles that are smaller than 2.5 micrometers in diameter), is easily inhalable and can enter the lining of the lungs and the bloodstream, posing a great risk to human health. Standards for allowable concentrations of PM2.5 were amended in 1997, 2006, and again in 2012, becoming increasingly stringent each time. According to the EPA, health organizations, and other research studies, these particles can specifically contribute to aggravated asthma and other issues such as difficulty breathing or coughing, as well as heart disease and heart attacks, and can be especially dangerous for children, the elderly, and those already suffering from respiratory illnesses. I will examine what effect, if any, the 2006 PM2.5 standard change (which lowered the daily allowable concentration from 65 to 35μg/m3) had on these health issues, specifically chronic respiratory and cardiovascular disease mortality rates, by analyzing countylevel air pollution data, mortality data, and smoking and obesity data. I selected seven states in the southeastern U.S. (all part of the EPA’s Region 4) for the analysis, which includes a differencein- difference, fixed effects model to compare high-pollution level counties within these states to those counties that see lower levels of PM2.5 pollution annually. I hypothesize that there will be a small decrease in mortality rates for both health outcomes for high-percentile pollution counties (who are likely to be impacted by more stringent standard changes) relative to their lower-percentile pollution counterparts. After performing several analyses, I find that estimates for the effect vary between the two mortality rates in terms of direction (either a positive or negative effect) but generally only have an impact of 1 to 2 deaths per 100,000 of the population. While the majority of the results are statistically insignificant, the magnitudes are small enough to render them practically insignificant as well, as most counties included in this analysis have populations between 20,000 to 50,000. As there are limitations associated with the available data included (and not included) in this analysis, further, more comprehensive research over a longer time frame is recommended to fully ascertain the impact of PM2.5 standards on public health outcomes.


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