We examine the impact of air pollution on infant death in California over the 1990s. Our work offers several innovations: First, many previous studies examine populations subject to far greater levels of pollution. In contrast, the experience of California in the 1990s is clearly relevant to current debates over the regulation of pollution. Second, many studies examine a few routinely monitored pollutants in isolation, generally because of data limitations. We examine four "criteria" pollutants in a common framework. Third, we develop an identification strategy based on within zip code variation in pollution levels that controls for potentially important unobserved characteristics of high pollution areas. Fourth, we use rich individual-level data to investigate effects of pollution on infant mortality, fetal deaths, low birth weight and prematurity in a common framework. We find that the reductions in carbon monoxide (CO) and particulates (PM10) over the 1990s in California saved over 1,000 infant lives. However, we find little consistent evidence of pollution effects on fetal deaths, low birth weight or short gestation. Pollution abatement is often justified as something that will promote health: Yet there is still much to be learned about the specific health effects. The EPA did not include infant mortality in the primary quantitative benefit analysis of the 1990 Clean Air Act Amendments in 1999 (U.S. EPA 1999) because the weight of the scientific evidence linking infant health to air pollution was viewed as insufficient.1 This paper addresses this issue by examining the impact of air pollution on infant death in California over the 1990s. Infants are of interest for two reasons. First, policy makers and the public are highly motivated to protect these most vulnerable members of society. Second, in the case of infant death the link between cause and effect is immediate, whereas for adults, diseases today may reflect pollution exposure that occurred many years ago.2 Our work offers several innovations over the existing literature. First, many previous studies examine populations subject to greater levels of pollution, either because they lived 1 As of May 12, 2003, the EPA's Scientific Advisory Board was debating whether to include an analysis of infant health effects in its 2003 report to Congress on the benefits of the Clean Air Act. However, they had determined that "[these] estimates are not meant to be additive to the primary estimates of mortality" (U.S. EPA, 2003, page 6-13). 2 California's experience is also of special interest, since under the Clean Air Act of 1970, it is the only state allowed to set automobile emission standards at a level higher than the federal standard. Other states may adopt California's 3 4 further in the past or in some more heavily polluted place. In contrast, the experience of California in the 1990s is clearly relevant to the contemporary debate over pollution levels in the United States. JanetSecond, many studies examine a few routinely monitored pollutants in isol...

We examine the impact of three "criteria" air pollutants on infant health in New Jersey in the 1990s by combining information about mother's residential location from birth certificates with information from air quality monitors. Our work offers three important innovations: First, we use the exact addresses of mothers to select those closest to air monitors to improve the accuracy of air quality exposure. Second, we include maternal fixed effects to control for unobserved characteristics of mothers. Third, we examine interactions of air pollution with smoking and other risk factors for poor infant health outcomes. We find consistently negative effects of exposure to carbon monoxide, both during and after birth, with effects considerably larger for smokers and older mothers. Since automobiles are the main source of carbon monoxide emissions, our results have important implications for regulation of automobile emissions.The primary goal of pollution abatement is to protect human health, but there is still much debate about the specific health effects. This paper addresses this issue by examining the impact of air pollution on infant health in New Jersey over the 1990s. Policy makers and the public are highly motivated to protect these most vulnerable members of society. There is increasing evidence of long-term effects of poor infant health on future outcomes; for example, low birth weight has been linked to future health problems and lower educational attainment (see Currie (2008) for a summary of this research). Studying infants also overcomes several empirical challenges because, unlike adult diseases that may reflect pollution exposure that occurred many years ago, the link between cause and effect is more immediate.Our analysis improves upon much of the previous research by improving the assignment of pollution exposure from air quality monitors to individuals. Most observational analyses that assess the impact of air pollution on health assign exposure to pollution by either approximating the individual's location as the centroid of a geographic area or computing average pollution levels within the geographic area. In our data we know the exact addresses of mothers, enabling us to improve on the assignment of pollution exposure.Despite this improvement in pollution measurement, we must still confront the problem that air pollution is not randomly assigned, making potential confounding a major concern. Since air quality is capitalized into housing prices (Chay and Greenstone, 2003) families with higher incomes or preferences for cleaner air are likely to sort into locations with better air quality, and failure to account for this will lead to overestimates of the effects of pollution. Alternatively, pollution levels are higher in urban areas where there are often more educated individuals with better access to health care, which can cause underestimates of the effects of * We are grateful for funding under NIH grant R21 HD055613-01. All opinions and any errors are our own. We would also like to thank

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In this paper we estimate the impacts of climate change on the allocation of time using econometric models that exploit plausibly exogenous variation in daily temperature over time within counties. We find large reductions in U.S. labor supply in industries with high exposure to climate and similarly large decreases in time allocated to outdoor leisure. We also find suggestive evidence of short-run adaptation through temporal substitutions and acclimatization. Given the industrial composition of the US, the net impacts on total employment are likely to be small, but significant changes in leisure time as well as large scale redistributions of income may be consequential. In developing countries, where the industrial base is more typically concentrated in climate-exposed industries and baseline temperatures are already warmer, employment impacts may be considerably larger.

This paper examines the effect of air pollution on child hospitalizations for asthma using a unique zip code level panel data set. The effect of pollution is identified using naturally occurring seasonal variations in pollution within zip codes. I also improve on past work by analyzing how the effect of pollution varies by age, by including measures of avoidance behavior, and by allowing the effect to vary by socioeconomic status (SES). Of the pollutants considered, carbon monoxide has a significant effect on asthma hospitalizations among children ages 1 to 18. To assess the importance of these findings, I analyze California's Low-Emission Vehicle II standards and find that nearly 15-20% of the costs from this policy are recovered in asthma hospitalizations for children alone. In addition, households respond to information about pollution with avoidance behavior, especially high SES families, suggesting that it is important to account for these endogenous responses when measuring the causal effect of pollution on health. Finally, the net effect of pollution is greater for children of lower SES, indicating that pollution is one potential mechanism by which SES affects health.JEL Classifications: I12, J13, J15, Q25