2013 Progress Report: The Effect of Air Pollution Control on Life Expectancy in the United States: A Population-Based Analysis of Major Metropolitan Areas

EPA Grant Number: R834894
Title: The Effect of Air Pollution Control on Life Expectancy in the United States: A Population-Based Analysis of Major Metropolitan Areas
Investigators: Dominici, Francesca , Dockery, Douglas W. , Ezzati, Majid , Pope, Clive Arden
Institution: Harvard T.H. Chan School of Public Health , Brigham Young University , Imperial College , The Johns Hopkins University
Current Institution: Harvard T.H. Chan School of Public Health , Brigham Young University , Imperial College
EPA Project Officer: Ilacqua, Vito
Project Period: July 1, 2011 through June 30, 2013 (Extended to June 30, 2014)
Project Period Covered by this Report: July 1, 2012 through June 30,2013
Project Amount: $300,000
RFA: Exploring New Air Pollution Health Effects Links in Existing Datasets (2010) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air

Objective:

Over the past few decades, there have been substantial and measurable improvements in ambient air quality in the United States (US). There also have been improvements in population survival, primarily as a result of decline in cardiovascular disease (CVD) mortality, although the change in life expectancy has been highly variable across U.S. counties. Given the differential changes in air pollution and life expectancy, we propose to conduct analyses that will directly estimate the benefits of lower air pollution on survival, adjusting for temporal trends in other key predictors of mortality. The proposed study brings together an experienced multi-disciplinary team of investigators with the objective of determining quantitatively the impacts of trends in selected criteria pollutants on cause-specific mortality and life expectancy in a population-based study. Our specific aims are to:

A.1. Estimate the effects of trends in measured PM2.5 (fine PM or particulate matter with an aerodynamic diameter less than or equal to 2.5 mm), PM10 (inhalable PM or particulate matter with an aerodynamic diameter less than or equal to 10 mm), PM10-2.5 (coarse PM or particulate matter with an aerodynamic diameter greater than 2.5 mm and less than or equal to 10 mm), PM2.5 constituents, ozone, and sulfur dioxide (SO2) on cardiopulmonary mortality for the several hundred U.S. counties with measurement data between 1999 and 2008.

A.2. Estimate the resulting effects of changes in cardiopulmonary mortality associated with air pollution trends on life expectancy at birth in the same counties.

Given the potentially large costs of implementing policy efforts to reduce air pollution, there is a growing need for research that demonstrates the health improvements associated with these efforts. This proposed research will provide essential new knowledge on the nationwide health benefits of reducing air pollution. The results as well as the data sources and methods will be innovative and contribute to strengthening air pollution research.

Progress Summary:

In years 1 and 2, we have continued to make important contributions in the following areas.

Statistical Methods

  1. In year 1, we have developed statistical methods to adjust for measured and unmeasured confounding in air pollution studies (Wang et al., 2012 Biometrics). We have also developed methods for the analysis of large spatio-temporal data to estimate the association between long-term trends in PM2.5 and trends in mortality in the Medicare cohort (Greven et al., 2011, JASA). We have developed statistical methods for causal inference to assess the public health impact of air quality regulations (Zigler et al., 2012, Biostatistics).
  2. In year 2, we have further developed statistical methods for: (1) estimating spatially varying chronic effects of PM2.5 on mortality (Chung et al., submitted); (2) quantifying bias in the chronic effects of air pollution when ambient levels of air pollution are estimated at a desired spatial location by using covariates that can also be confounders of the exposure-response relationship (Cefalu et al., under review); and (3) for accounting for the uncertainty in the selection of confounders where the goal is to estimate chronic effects associated with simultaneous exposure to multiple pollutants.

Epidemiological Studies

  1. One of the most important papers for this year 1, in Correia et al., 2012, Epidemiology, which directly address Aims 1 and 2 of this grant for PM2.5. This paper has been accepted for publication in Epidemiology; Jonathan M. Samet also wrote a commentary and the paper has also been featured in the Science page of the New York Times. The abstract is below:

Abtract:  In recent years (2000 to 2007), ambient levels of fine particulate matter (PM2.5) have continued to decline as a result of interventions, but the decline has been at a slower rate than previous years (1980 to 2000). Whether these more recent and slower declines of PM2.5 levels continue to improve life expectancy and whether they benefit all populations equally is unknown. We assembled a dataset for 545 U.S. counties consisting of yearly county-specific average PM2.5, yearly county-specific life expectancy, and several potentially confounding variables measuring socioeconomic status, smoking prevalence and demographic characteristics for the years 2000 and 2007. We used regression models to estimate the association between reductions in PM2.5 and changes in life expectancy for the period 2000 to 2007. A decrease of 10 mg/m3 in the concentration of PM2.5 was associated with an increase in mean life expectancy of 0.35 years SD= 0.16 years, p = 0.033). This association was stronger in more urban and densely populated counties. Reductions in PM2.5 were associated with improvements in life expectancy for the period 2000 to 2007. Air pollution control in the last decade has continued to have a positive impact on public health.

  1. In year 2, we have extended the analysis described above to the PM2.5 chemical constituents. More specifically, we have almost completed the following manuscript:

“Dominici F, Wang Y, Lee U, Correia A, Dockery D, Ezzati M, Pope A. Chemical Composition of Fine Particulate Matter and Life Expectancy: An Analysis of 123 US Counties for the Period 2001 to 2007." We plan to submit this paper in the next 2-3 weeks; please see below the abstract.

Background: In previous work, we have provided evidence that a decline in fine particulate matter (PM2.5) during the period 2000 to 2007 was associated with increased life expectancy in 545 U.S. counties. In this paper, we evaluate which chemical constituents of PM2.5 are the main drivers of the observed association.

Methods: We estimated the association between changes in PM2.5 and in each of the seven major components of PM2.5 - Ammonium, Sulfate, Nitrate, Elemental Carbon Matter, Organic Carbon Matter, Sodium, and Silicon - and changes in life expectancy in 123 U.S. counties from 2001-2007. We fitted both single-pollutant and multi-pollutant linear models, controlling for possible confounding by socioeconomic, demographic, and smoking variables and stratified the analysis by urban and nonurban counties.

Results: Increases in life expectancy from 2001-2007 were generally more strongly associated with reductions in PM2.5 overall than with any specific component or constituent of PM2.5. Reductions in the components Ammonium, Sulfate, and Nitrate were associated with increased life expectancy, while reductions in Sodium were actually negatively associated with life expectancy while reductions in Sodium were negatively associated with life expectancy.

Conclusions: These results suggest that recent reductions in long-term exposure to Ammonium, Sulfate, Nitrate and associated pollutants have contributed to improved public health. Further research is needed to understand the relationship between Ammonium, Sulfate, Nitrate, associated air pollutants, their sources, and their health impacts.

In addition, we have published a large epidemiological study on the effect of county-wide smoking bans and long-term changes in hospital admissions for cardiovascular diseases (Barr et al., 2012). We have conducted another nationwide “pattern of care” study to investigate as to whether hospitalization for cardiovascular diseases (CVD), CVD-specific mortality, and use of CVD-specific in-hospital procedures have been changing over the last decade and across the U.S. in the last decade (Barr et al., 2012 AJE). We also have been invited to write an editorial for JAMA to describe challenges with the investigation of the public health benefits of air quality interventions, in this case, the Olympic Games in China.

Future Activities:

In the third year, we plan to continue to work on methodological development geared toward multiple pollutant analyses, methods for causal inference, and publish the papers that are in progress.


Journal Articles on this Report : 12 Displayed | Download in RIS Format

Other project views: All 43 publications 31 publications in selected types All 31 journal articles
Type Citation Project Document Sources
Journal Article Barr CD, Diez DM, Wang Y, Dominici F, Samet JM. Comprehensive smoking bans and acute myocardial infarction among Medicare enrollees in 387 US counties: 1999–2008. American Journal of Epidemiology 2012;176(7):642-648. R834894 (2012)
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  • Journal Article Bell ML, Zanobetti A, Dominici F. Evidence on vulnerability and susceptibility to health risks associated with short-term exposure to particulate matter: a systematic review and meta-analysis. American Journal of Epidemiology 2013;178(6):865-876. R834894 (2013)
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  • Journal Article Correia AW, Pope III CA, Dockery DW, Wang Y, Ezzati M, Dominici F. Effect of air pollution control on life expectancy in the United States: an analysis of 545 U.S. counties for the period 2000 to 2007. Epidemiology 2013;24(1):23-31. R834894 (2013)
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  • Journal Article Correia AW, Wang Y, Dominici F, Pope III CA, Dockery DW, Ezzati M. "Threshold findings" in an ecological study. Epidemiology 2013;24(4):628. R834894 (2013)
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  • Journal Article Dominici F, Mittleman MA. China’s air quality dilemma:reconciling economic growth with environmental protection. Journal of the American Medical Association 2012;307(19):2100-2102 (editorial). R834894 (2012)
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  • Journal Article Dominici F, Wang Y, Correia AW, Ezzati M, Pope IIII CA, Dockery DW. Chemical composition of fine particulate matter and life expectancy: in 95 US counties between 2002 and 2007. Epidemiology 2015;26(4):556-564. R834894 (2013)
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  • Journal Article Greven S, Dominici F, Zeger S. An approach to the estimation of chronic air pollution effects using spatio-temporal information. Journal of the American Statistical Association 2011;106(494):396-406. R834894 (2012)
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  • Journal Article Levy JI, Diez D, Dou Y, Barr CD, Dominici F. A meta-analysis and multisite time-series analysis of the differential toxicity of major fine particulate matter constituents. American Journal of Epidemiology 2012;175(11):1091-1099. R834894 (2012)
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  • Journal Article Wang C, Parmigiani G, Dominici F. Bayesian effect estimation accounting for adjustment uncertainty. Biometrics 2012;68(3):661-671. R834894 (2012)
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  • Journal Article Wang C, Parmigiani G, Dominici F. Rejoinder: Bayesian effect estimation accounting for adjustment uncertainty. Biometrics 2012;68(3):680-686. R834894 (2012)
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  • Journal Article Yeh RW, Normand S-LT, Wang Y, Barr CD, Dominici F. Geographic disparities in the incidence and outcomes of hospitalized myocardial infarction:does a rising tide lift all boats? Circulation: Cardiovascular Quality and Outcomes 2012;5(2):197-204. R834894 (2012)
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  • Journal Article Zigler CM, Dominici F, Wang Y. Estimating causal effects of air quality regulations using principal stratification for spatially correlated multivariate intermediate outcomes. Biostatistics 2012;13(2):289-302. R834894 (2012)
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  • Supplemental Keywords:

    Life expectancy, PM2.5, trends, confounding, air pollution

    Progress and Final Reports:

    Original Abstract
    2012 Progress Report
    Final Report