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Final Report: Quasi-Experimental Evidence on How Airborne Particulates Affect Human Health
EPA Grant Number: R829402C004Subproject: this is subproject number 004 , established and managed by the Center Director under grant R829402
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Center for Integrating Statistical and Environmental Science
Center Director: Stein, Michael
Title: Quasi-Experimental Evidence on How Airborne Particulates Affect Human Health
Investigators: Greenstone, Michael , Chay, Kenneth , Neidell, Matthew
Institution: University of California - Berkeley , University of Chicago
EPA Project Officer: Jones, Brandon
Project Period: March 12, 2002 through March 11, 2007
RFA: Environmental Statistics Center (2001)
Research Category: Ecological Indicators/Assessment/Restoration , Environmental Statistics
Description:
Objective:This project attempted to improve estimates of the effect of air quality, such as particulate matter, ozone, and carbon monoxide, on human health by using quasi-experimental techniques. Although much prior research documents a statistical association between pollution concentrations and health outcomes, the reliability of the evidence has been seriously questioned. For example, since air pollution is not randomly assigned across locations, previous studies may not be adequately controlling for a number of potential confounding determinants of health. Furthermore, the effects of pollution on the health of children, especially infants, are often overlooked since scientific evidence is scant. Children may suffer disproportionately from comparable levels of pollution than adults because of their developing biological systems, so understanding the impact of pollution on children’s health is essential for public policy. The quasi-experimental techniques used in these projects aimed to identify exogenous variation in air quality that is uncorrelated with confounding factors that affect health in an effort to provide more reliable estimates of the impact of air quality on the health of adults and children.
This project supported one postdoctoral research associate, Matthew Neidell, from September 2002 - July 2004. He is now an assistant professor at Columbia University in the Department of Health Policy and Management at the Mailman School of Public Health. Michael Greenstone has resigned his faculty position at the University of Chicago and is currently the 3M Professor of Economics at the MIT Department of Economics. Kenneth Chay is a professor of Economics at Brown University.
Summary/Accomplishments (Outputs/Outcomes):- The Clean Air Act of 1970 and adult mortality
- Air pollution, health, and socio-economic status: the effect of outdoor air quality on childhood Asthma
- Air pollution and infant health: what can we learn from California’s recent experience?
- Information, avoidance behavior, and health: the effect of ozone on asthma hospitalizations
- Air pollution, avoidance behavior, and health: evidence from the port of Los Angeles
Overview: Previous research has established an association between air pollution and adult mortality. However, studies utilizing short-term fluctuations in pollution may detect mortality changes among the already ill or dying, while prospective cohort studies, which utilize geographic differences in long-run pollution levels, may suffer from severe omitted variable bias. This study utilizes the long-run reduction in total suspended particulates pollution induced by the Clean Air Act of 1970, which mandated aggressive regulation of local polluters in heavily polluted counties.
We found in the first year after the implementation of the Clean Air Act, total suspended particulate concentrations declined significantly more in nonattainment counties than in attainment ones. However, there was little systematic association between nonattainment status and changes in adult and elderly mortality rates. The results imply that the regulation-induced reduction in TSPs was not associated with improvements in adult or elderly mortality. Although this design is likely to reduce the misspecification associated with time series and cross-sectional regressions, we found differences between nonattainment and attainment counties in their pre-regulation mortality rates and trends that may undermine the design’s validity
Investigator(s): Kenneth Chay, Michael Greenstone, and Carlos Dobkin (faculty at University of Santa Cruz, Department of Economics)
Project Status: Published in Journal of Risk and Uncertainty
Overview: This paper estimated the effect of air pollution on child hospitalizations for asthma using naturally occurring seasonal variations in pollution within zip codes. Of the pollutants considered, carbon monoxide (CO) had a significant effect on asthma for children ages 1–18: if 1998 pollution levels were at their 1992 levels, there would have been a 5–14% increase in asthma admissions. Also, households respond to information about pollution with avoidance behavior, suggesting it is important to account for these endogenous responses when measuring the effect of pollution on health. Finally, the effect of pollution was greater for children of lower socio-economic status (SES), indicating that pollution is one potential mechanism by which SES affects health.
Investigator(s): Matthew Neidell
Project Status: Published in Journal of Health Economics
Overview: We examined the impact of air pollution on infant death in California over the 1990s. Our work offered several innovations: first, most previous studies examined populations subject to far greater levels of pollution. Second, many studies examined a single pollutant in isolation. We examined three criteria pollutants in a common framework. Third, we used rich individual-level data and pollution measured at the weekly level. Our most novel finding was a significant effect of CO on infant mortality: we find that reductions in carbon monoxide over the 1990s saved approximately 1000 infant lives in California.
Investigator(s): Matthew Neidell
Project Status: Published in Quarterly Journal of Economics
Overview: This paper assessed whether behavioral responses to information about risk impact estimates of the relationship between ozone and asthma hospitalizations in Southern California. To assess whether individuals respond to information, we examined the effect of smog alerts, an important piece of information about ozone levels, on daily attendance at two major outdoor facilities. Using a regression discontinuity design that exploited the deterministic selection rule used for issuing smog alerts, evidence indicates significant decreases in time spent outside in response to smog alerts. To assess whether these responses impact estimates of the relationship between ozone and health, we estimated models that use the arguably exogenous daily variation in ozone levels within small geographic areas and within each year-month. Regression estimates of the effect of ozone for children and the elderly (two groups specifically targeted by air quality information) that account for avoidance behavior are significantly larger than estimates that do not. These results are consistent with the hypothesis that individuals take substantial action to reduce exposure to risk; estimates that ignore these actions are severely biased.
Investigator(s): Matthew Neidell and Janet Currie (faculty at Columbia University, Department of Economics)
Project Status: Forthcoming in Journal of Human Resources
Overview: Estimating the relationship between ambient air pollution and health is complicated by the fact that pollution exposure is endogenously determined if individuals make choices to maximize their well-being. Individuals may sort into neighborhoods based on the level of air quality or respond to ambient pollution level by protecting themselves, so that simple correlations between health and pollution are biased estimates of the true effect. This project attempted to isolate the causal short run effects of pollution on health in Southern California. To allow for responses to pollution, we controlled for all publicly provided information about pollution. To account for the endogeneity of ambient pollution levels, we used boat arrivals and departures into the two major ports of Los Angeles as an instrumental variable for ozone levels. Most of these boats travel from great distances and emit unusually high level of nitrogen oxides, a precursor to ozone, so the influx of pollution due to port activity is arguably uncorrelated with factors related to health. Moreover, the arrivals and departures are not included in the pollution forecasts provided by local governmental agencies, so there is little opportunity for people to respond to pollution coming from the port. Using this identification strategy in a model with zip code fixed effects, we looked at the effect of ozone on hospitalizations for asthma in children, adults, and the elderly.
Investigator(s): Matthew Neidell and Enrico Moretti (faculty at University of California at Berkeley, Department of Economics)
Project Status: Paper under journal review.
Contributions to understanding of environmental problems
The primary objective of air quality policies around the world is to protect human health. Given the substantial abatement costs to industry from improving air quality, successful interventions require reliable estimates of the benefits from improvements in environmental quality. This project attempted to improve the measurement of the benefits from improved environmental quality through the use of quasi-experimental techniques that aim to identify exogenous variation (sources of variation independent of any other factors that might affect health outcomes) in air quality. The successful application of the quasi-experimental approach on the health of children and adults offers the promise of providing a deeper understanding of the world in which we live. Moreover, evidence based on credible empirical research can foster the identification of efficient environmental policies, a critical aim for environmental agencies.
Journal Articles on this Report: 3 Displayed | Download in RIS Format
| Other subproject views: | All 8 publications | 8 publications in selected types | All 3 journal articles |
| Other center views: | All 102 publications | 59 publications in selected types | All 37 journal articles |
| Type | Citation | ||
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Chay K, Dobkin C, Greenstone M. The Clean Air Act of 1970 and adult mortality. Journal of Risk and Uncertainty 2003;27(3):279-300. |
R829402C004 (2002) R829402C004 (Final) |
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Currie J, Neidell M. Air pollution and infant health: what can we learn from California’s recent experience? The Quarterly Journal of Economics 2005;120(3):1003-1030. |
R829402C004 (Final) |
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Neidell MJ. Air pollution, health, and socio-economic status: the effect of outdoor air quality on childhood asthma. Journal of Health Economics 2004;23(6):1209-1236. |
R829402C004 (Final) |
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, Ecosystem Protection/Environmental Exposure & Risk, Economic, Social, & Behavioral Science Research Program, Air, Geographic Area, Scientific Discipline, Health, RFA, Ecosystem/Assessment/Indicators, Engineering, Chemistry, & Physics, Air Quality, exploratory research environmental biology, Risk Assessments, decision-making, Environmental Statistics, Great Lakes, Health Risk Assessment, Ecological Risk Assessment, Economics & Decision Making, Ecological Indicators, Environmental Engineering, Ecological Effects - Human Health, EPA Region, particulate matter, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Monitoring/Modeling, Environmental Monitoring, risk assessment, trend monitoring, ozone , chemical transport models, particulate, risk management, stochastic models, statistical methodology, ecological risk, ecosystem health, chemical transport, environmental health effects, aersol particles, human health risk, monitoring, policy making, statistical models, air quality models, human health effects, particulates, regulations, statistical methods, Region 5, ambient particle health effects, air pollution, data analysis, ecosystem assessment, environmental risks, water, chemical transport modeling, airborne particulate matter, ecological models, ecological effects, ecological health, human exposure
Progress and Final Reports:
2002 Progress Report
Original Abstract
Main Center Abstract and Reports:
R829402 Center for Integrating Statistical and Environmental Science
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R829402C001 Detection of a Recovery in Stratospheric and Total Ozone
R829402C002 Integrating Numerical Models and Monitoring Data
R829402C003 Air Quality and Reported Asthma Incidence in Illinois
R829402C004 Quasi-Experimental Evidence on How Airborne Particulates Affect Human Health
R829402C005 Model Choice Stochasticity, and Ecological Complexity
R829402C006 Statistical Approaches to Detection and Downscaling of Climate Variability and Change