Kosali Simon is a health economist and professor at Indiana University and member of the 2021 Tradeoffs Research Council. She studies health insurance and health policy.

We know pollution is bad for people’s health, but figuring out how big of an impact it has — compared to other environmental and social factors — can be difficult to tease out. Finding these answers is critical to addressing vexing social problems like racial and economic achievement gaps and health disparities that often start in childhood. 

A recent NBER working paper by Alex Hollingsworth, Mike Huang, Ivan J. Rudik and Nicholas J. Sanders took an especially creative approach to isolating the effects on children of a particularly toxic source of air pollution: leaded gasoline. Although the U.S. Environmental Protection Agency began phasing out leaded gasoline in 1975 and banned its sale to most consumers by 1996, many aircraft still use the fuel. Until 2007, NASCAR race cars did too. Shockingly, each NASCAR race deposited more than 10 kilograms of lead (about the amount one airport emits in a year) into the air of nearby neighborhoods, where it lingered long after fans left the track.

Hollingsworth and colleagues took advantage of NASCAR’s 2007 switch to unleaded fuel as a kind of “natural experiment” — a unique opportunity to analyze the impact of a policy change in the real world. Aside from the fuel switch, all other aspects of NASCAR car races (e.g. noise, crowds) stayed the same, getting us pretty close to an ideal lab experiment.

So how bad is lead? Looking at data from the state of Florida, the authors found kids attending schools within 50 miles of a NASCAR track had significantly lower standardized test scores. The cost of that cognitive harm, the authors estimated, was enough to reduce the average third grade child’s future lifetime earning potential by between $3,000 and $5,000 (in today’s value). Summed across all Florida third graders, the authors calculated total potential income losses of more than $300 million.

The authors also found evidence suggesting that nutrition policy, particularly the availability of calcium-rich foods, can mitigate this environmental harm. In areas where children had higher levels of milk consumption, the authors did not see the same link between lead exposure and test scores. Those neighborhoods least likely to have that nutritional protection, and thus more likely to suffer the long-term consequences of lead pollution, had larger shares of Black and low-income students.

One of the aspects of this paper I appreciate most is the attention paid to measurement. The authors were so invested in precisely estimating the amount of lead produced by each race that they dove deep into detailed NASCAR race data and even went to a local track and purchased some fuel themselves to analyze in a lab! 

Although the authors note further analyses could bolster their findings, this paper is already an important addition to an existing body of literature quantifying the health impacts of air and water pollution on child health, as well as elderly mortality and dementia. This paper also arrives at a pivotal time in public decision-making, as the Biden administration has promised to conduct a sweeping review of climate and pollution policies, including the National Ambient Air Quality Standards. Finally, the study reminds us as researchers that even when lab experiments are impossible, carefully constructed quasi-natural experiments can provide valuable evidence that informs policies as important as the air we breathe.