They may seem innocuous enough, those small planes used for weekend getaways, flight training, small freight deliveries, and other civilian purposes. But collectively, the more than167,000 piston-engine aircraft that comprise the majority of the U.S. general aviation (GA) fleet may pose a significant health threat. That’s because these vehicles, which rely on leaded fuel to operate safely, constitute the nation’s largest remaining source of lead emissions. Those exposed to low levels of lead, especially children, have been shown to suffer neurological and cognitive impairment, including IQ loss.
Unlike commercial airliners, which do not use leaded fuel, and automobiles, which went all-unleaded by 1995, piston-driven GA aircraft account for about half of anthropogenic lead emissions in U.S. skies. But just how much of an impact is this airborne lead having on the nation’s public health and economy? To answer that question, a team of MIT researchers has conducted the first assessment of the nationwide annual costs of IQ losses that can be attributed to aviation lead emissions.
The team found that each year, these IQ losses result in about $1 billion in damages from lifetime earnings reductions, with an additional $0.5 billion in economy-wide losses due to decreases in labor productivity. Its findings appear in the journal Environmental Science and Technology.
“Regulations have brought about a dramatic reduction in lead exposure for the U.S. population over time, but childhood lead exposure is associated with decreased academic achievement and IQ loss even at low blood lead levels,” says Philip Wolfe, a postdoc in the MIT Laboratory for Aviation and the Environment, and lead author of the paper. “This study not only provides an estimate of the costs of these effects, but also is the first to look at how these damages have feedback loops in the economy. It shows that emissions today will continue to have an impact for decades.”
To obtain their results, the researchers developed an inventory of general aviation emissions across the continental U.S., and modeled its impact on atmospheric lead concentrations using the Community Multi-Scale Air Quality Model (CMAQ). Based on these GA-specific contributions to overall atmospheric lead levels, they quantified associated IQ deficits nationwide and their annual economic impacts. They estimated annual losses in lifetime earnings potential using earnings data from the U.S. Department of Labor’s Bureau of Labor Statistics, and annual losses in labor productivity using a Joint Program computational general equilibrium model called USREP, which models the U.S. economy.
Efforts to curb leaded emissions from GA aircraft have been underway for at least a decade. Petitioned by the environmental nonprofit group Friends of the Earth (FoE) in 2006 to address the problem of leaded emissions from GA aircraft, the Environmental Protection Agency proposed limiting such emissions in 2010, but has yet to issue a ruling. The FoE claims that 70 percent of GA planes could switch to unleaded fuel without retrofitting. Toward that end, the Federal Aviation Administration aims to certify and distribute an unleaded replacement fuel by 2018.
This research was supported by the MIT Center for Environmental Health Sciences with funding from the National Institutes of Health.
Story image: Collectively, piston-engine aircraft like this Cessna SR-22T constitute the nation’s largest remaining source of lead emissions- Image courtesy: Travis Air Force Base/Flickr
Noelle Eckley Selin's research focuses on using atmospheric chemistry modeling to inform decision-making strategies on air pollution, climate change and toxic substances including mercury and persistent organic pollutants. She has also published articles and book chapters on the interactions between science and policy in international environmental negotiations, in particular focusing on global efforts to regulate hazardous chemicals and persistent organic pollutants. Prior to joining the MIT faculty in 2010, Selin spent two years as a postdoctoral associate and research scientist with the MIT Joint Program on the Science and Policy of Global Change. She received her PhD in 2007 from Harvard University in Earth and Planetary Sciences. Previously, she was a research associate with the Initiative on Science and Technology for Sustainability at Harvard’s Kennedy School of Government, a visiting Fulbright fellow at the European Environment Agency in Copenhagen, Denmark, and worked on chemicals issues at the U.S. Environmental Protection Agency.