The Effect of Leaded Gasoline on Infant Health: Evidence from NASCAR Fuel Transition.
Abstract: NASCAR-sanctioned races used leaded gasoline through 2006, generating concentrated bursts of airborne lead emissions around active racetracks. I study how these exposures affected infant health using detailed Texas birth records linked to race events at Texas Motor Speedway (TMS) in Fort Worth. Identification relies on within-TMS variation in distance, wind direction, race timing, and race-specific emissions among mothers living within 25 km of the same track. Pre-ban trimester-specific log emissions reduce birthweight, shorten gestation, and increase the probability of low birthweight. A post-ban placebo yields coefficients near zero, suggesting that the estimated effects are not driven by factors correlated with race activity. To translate intermittent race-day exposures into pregnancy-relevant blood lead burdens, I develop a pregnancy-specific physiologically based pharmacokinetic (PBPK) model that simulates daily maternal and fetal blood lead trajectories using each mother's race-event history. A one-standard-deviation increase in second-trimester PBPK blood lead reduces birthweight by approximately 73 grams. A significant post-2007 birthweight decline near a former Houston racetrack, unrelated to lead exposure, suggests the limitations of cross-track comparisons and highlights the importance of exploiting within-track variation. I then examine potential mechanisms and find that lead exposure increases gestational hypertension and shortens gestation, with both effects disappearing after the transition to unleaded fuel. These findings suggest that even relatively small and intermittent sources of airborne lead can have meaningful effects on infant health.
Abstract: NASCAR-sanctioned races used leaded gasoline through 2006, generating concentrated bursts of airborne lead emissions around active racetracks. I study how these exposures affected infant health using detailed Texas birth records linked to race events at Texas Motor Speedway (TMS) in Fort Worth. Identification relies on within-TMS variation in distance, wind direction, race timing, and race-specific emissions among mothers living within 25 km of the same track. Pre-ban trimester-specific log emissions reduce birthweight, shorten gestation, and increase the probability of low birthweight. A post-ban placebo yields coefficients near zero, suggesting that the estimated effects are not driven by factors correlated with race activity. To translate intermittent race-day exposures into pregnancy-relevant blood lead burdens, I develop a pregnancy-specific physiologically based pharmacokinetic (PBPK) model that simulates daily maternal and fetal blood lead trajectories using each mother's race-event history. A one-standard-deviation increase in second-trimester PBPK blood lead reduces birthweight by approximately 73 grams. A significant post-2007 birthweight decline near a former Houston racetrack, unrelated to lead exposure, suggests the limitations of cross-track comparisons and highlights the importance of exploiting within-track variation. I then examine potential mechanisms and find that lead exposure increases gestational hypertension and shortens gestation, with both effects disappearing after the transition to unleaded fuel. These findings suggest that even relatively small and intermittent sources of airborne lead can have meaningful effects on infant health.
Publications
An, Y., Chin, S. & Miller, R. Growing Old in Rural America: Measuring Late Life Health and Economic Well-being. The Journal of the Economics of Ageing, 100565.
Abstract: We estimate well-being among older rural Americans with an expected utility framework and simulations using longitudinal data spanning nearly 30 years from the Health and Retirement Study. At age sixty, we find mean rural consumption expenditures of $24,105, a retirement probability of 53%, and a remaining life expectancy of 20.3 years for the cohort born 1931-36. When adjusting life expectancy for living in poor health, we obtain an age sixty quality adjusted life expectancy (QALE) of only 15.4 years. Our welfare metric suggests well-being among rural residents who report loneliness is only about half that of the non-lonely rural residents—largely driven by substantial consumption and QALE gaps. We also document substantial regional variation in rural well-being. Moreover, we find that older rural Americans are generally falling further behind older urban Americans across birth cohorts. Most of this widening gap is driven by declining relative consumption and wealth as opposed to health.
Abstract: We estimate well-being among older rural Americans with an expected utility framework and simulations using longitudinal data spanning nearly 30 years from the Health and Retirement Study. At age sixty, we find mean rural consumption expenditures of $24,105, a retirement probability of 53%, and a remaining life expectancy of 20.3 years for the cohort born 1931-36. When adjusting life expectancy for living in poor health, we obtain an age sixty quality adjusted life expectancy (QALE) of only 15.4 years. Our welfare metric suggests well-being among rural residents who report loneliness is only about half that of the non-lonely rural residents—largely driven by substantial consumption and QALE gaps. We also document substantial regional variation in rural well-being. Moreover, we find that older rural Americans are generally falling further behind older urban Americans across birth cohorts. Most of this widening gap is driven by declining relative consumption and wealth as opposed to health.
Working Papers
An, Y., Komarek, T. & Miller, R. (2025). Population Aging, Regional Integration, and Economic Growth Across U.S. Counties.
Abstract: This paper examines how population aging has impacted economic growth across U.S. counties from 2000 to 2020, with a focus on spatial variation between metropolitan and non-metropolitan areas. Using an instrumental variables approach that leverages lagged age structure to address endogeneity concerns, we find that aging significantly reduces per capita GDP growth in non-metro counties but has smaller and often statistically insignificant effects in metro counties. Decomposing by industry reveals that aging tends to depress output in agriculture, construction, mining, manufacturing, and public-sector employment—particularly in rural areas—while raising output in sectors like healthcare and professional services. Importantly, we also find that the negative growth effects of aging are mitigated in counties with greater economic openness, measured by commuting inflows from surrounding areas. These results suggest that the local consequences of demographic aging depend not only on industrial structure, but also on regional integration and labor market connectivity. Our results underscore the need for targeted strategies to support sectoral adaptation and mitigate economic decline in aging rural regions.
Abstract: This paper examines how population aging has impacted economic growth across U.S. counties from 2000 to 2020, with a focus on spatial variation between metropolitan and non-metropolitan areas. Using an instrumental variables approach that leverages lagged age structure to address endogeneity concerns, we find that aging significantly reduces per capita GDP growth in non-metro counties but has smaller and often statistically insignificant effects in metro counties. Decomposing by industry reveals that aging tends to depress output in agriculture, construction, mining, manufacturing, and public-sector employment—particularly in rural areas—while raising output in sectors like healthcare and professional services. Importantly, we also find that the negative growth effects of aging are mitigated in counties with greater economic openness, measured by commuting inflows from surrounding areas. These results suggest that the local consequences of demographic aging depend not only on industrial structure, but also on regional integration and labor market connectivity. Our results underscore the need for targeted strategies to support sectoral adaptation and mitigate economic decline in aging rural regions.
Selected Works in Progress
When Football Comes to Town: Provider Decision-Making and Delivery Complications, with Sayorn Chin and Sammy Zahran.
Urban Heat Island and Health Outcomes, with Tim Komarek and Sayorn Chin.