You are here:
NAAQS Attainment and the PM2.5-Mortality Association
Citation:
Corrigan, A., M. Becker, W. Cascio, L. Neas, AND A. Rappold. NAAQS Attainment and the PM2.5-Mortality Association. HEI Meeting, Washington, DC, May 06 - 08, 2017.
Impact/Purpose:
This is an abstract for Health Effects Institute (HEI) annual meeting.
Description:
Background. Ambient air quality has been steadily improving since promulgation of National Ambient Air Quality Standards (NAAQS) by EPA in accordance with the Clean Air Act. In 1997, a standard for fine particulate matter (PM2.5) was promulgated for the first time. Although the impacts of this pollutant on health are well characterized, less is known whether the air pollution standards have resulted in improvements to public health. The objective of this study is to examine whether the attainment of the 1997 PM2.5 NAAQS improved cardiovascular mortality. Methods. We examined the impact of change in PM2.5 on change in cardiovascular mortality rate before and after 2005, when the 1997 standard designations were published (2000-2004 vs 2005-2010). We further examined how the association varied with respect to county-level NAAQS designations by stratifying in two ways: first, by the EPA Green Book status of attainment or nonattainment; second, by the county-level design values (DV) used for designation. We used linear regression and difference-in-difference models, adjusted for sociodemographic confounders. Results. Across the 619 U.S. counties with available PM2.5 data we observed a 1.21 µg/m3 mean decrease in the annual PM2.5 after 2005. Cardiovascular mortality rate, expressed as number of deaths/100,000 people, decreased by 63.1(95% CI 62.2, 64.1) in absolute terms after 2005 and by 1.10 (0.37, 1.82) for each 1 µg/m3 decrease in PM2.5. Nonattainment counties had twofold larger reduction in mean annual PM2.5 in nonattainment counties, 2.69 µg/m3, compared to attainment counties, 1.35 µg/m3. Nonattainment counties also had a greater absolute decrease in mortality rate, 63.7(62.2, 65.3), compared to attainment counties, 62.7(61.5, 64.0). However, per 1 µg/m3 decrease in PM2.5, nonattainment counties had a smaller change in mortality rate, 0.59(-0.54, 1.71), than attainment counties, 1.96(0.77, 3.15), though none of the differences were statistically significant. Similar results were observed when counties were stratified on the design values. Counties with DV greater than 15 µg/m3 experienced the greatest decrease in mean annual PM2.5 (3.09 µg/m3) and the largest improvement in the adjusted mean cardiovascular mortality, 64.5(62.5, 66.6), but the smallest decrease per 1 µg/m3 decrease in PM2.5 0.73(-0.57, 2.02). Conclusions. Our findings suggest that counties designated nonattainment had a greater drop in mean PM2.5, greater absolute drop in mean cardiovascular mortality rate, but smaller incremental change in mortality rate per 1 µg/m3 PM2.5 compared to counties in attainment. Additionally, the change in PM2.5 values after the implementation of the NAAQS was strongly correlated with the DVs used for designation. Taken together, the results suggest that there is a non-linear relationship between the change in PM2.5 and the change in cardiovascular mortality. This study contributes to the discussion on the significance of NAAQS and other EPA regulatory actions as they relate to changes air pollution and associated health concerns. Disclaimer: The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency (EPA).