When NASCAR Comes To Town: The Health Impacts of Acute Lead Exposure

Monday, June 24, 2019: 8:45 AM
Taylor - Mezzanine Level (Marriott Wardman Park Hotel)

Presenter: Alex Hollingsworth

Co-Author: Ivan Rudik

Discussant: Jonathan Ketcham

Lead is well known to cause harm in humans and health organizations have stated that there is no known safe blood lead level. In response to health concerns, there have been major efforts since 1970 to phase lead out of gasoline and household paint. Since these efforts began, airborne lead concentrations and blood lead levels have dramatically decreased. Despite these efforts, the phaseout of lead from gasoline in the United States remains incomplete; leaded gasoline is still legally permitted for off-road use in specific industries including, aviation, boating, farming, and automotive racing. We exploit these industry specific exemptions to leaded gasoline prohibition to estimate the relationship between the use of leaded gasoline and airborne lead pollution, lead soil deposition, blood lead levels, cognitive performance, and mortality. Specifically, we exploit a natural experiment where both the NASCAR and ARCA racing series switched from leaded to unleaded gasoline in 2007.

Automotive races are an ideal setting to study lead emissions because of the large amount of lead emitted (a standard NASCAR race of twenty-thousand race miles may emit twice the average airport’s annual lead emissions) and because races continued in the same locations after the removal of lead. Thus our difference-in-differences research design allows us to isolate the impact of lead from the impact of other pollutants and other social determinants of health. We find that (i) ambient airborne lead concentrations increase immediately after a NASCAR race, (ii) counties with leaded NASCAR races have higher rates of child lead poisoning, (iii) student cohorts exposed to more leaded NASCAR miles in their lifetime have lower standardized test scores, and (iv) county-years with leaded NASCAR races have higher rates of elderly mortality.

Our findings are not driven by changes in other pollutants likely emitted by automotive races or the time period included in the analysis. We add further credibility to our estimates by examining the effect of racing series that do not use leaded fuel and finding no effect. Our work makes several contributions to the literature. First, we directly link outcomes to leaded miles driven instead of a proxy for lead exposure. Second are able to separately identifying the effect of lead from other correlated pollutants. Third, we use the same quasi-experiment to estimate the impact of lead emissions on each link in emission-outcome chain (air pollution, soil deposition, blood-accumulation, and health outcomes). This consistency helps with internal validity and comparability since all findings use the same underlying identifying variation. Fourth, our research setting demonstrates both acute and chronic effects of acute exposure when ambient pollution levels are low. That is, our results are informative about the costs of allowing leaded gasoline to remain in a small number of industries and of the shape of the marginal damage curve near the origin. Finally, we contribute to estimating a lower bound on the social cost of leaded gasoline.