Since 2008, the number of deaths caused by air pollution have been reduced by thousands in the United States as a result of decreasing vehicle emissions, according to a new study led by Harvard T.H. Chan School of Public Health. The improvements are the result of federal air pollution regulations and technological innovations by car manufacturers.

However, although emissions caused by large trucks have been significantly reduced, passenger light-duty vehicles such as pickup trucks or SUVs continue to contribute to air pollution in metropolitan areas.

“Recent reductions in vehicle emissions have yielded major health benefits, even though only small progress has been made on reducing their climate impact,” said study first author Ernani Choma, a research fellow in Harvard T.H. Chan School’s Department of Environmental Health. “Our results indicate that to achieve further public health and climate gains, even more stringent policies will be required.”

By using recent national emissions data, Choma and his colleagues modeled four scenarios for emissions in 2017: the actual emissions and three alternative scenarios in which the level of emissions was the same as in 2014, 2011, and 2008. 

The researchers found that deaths attributable to air pollution associated with vehicle emissions dropped from 27,700 in 2008 to 19,800 in 2017. If vehicles were still emitting at 2008 levels, they would have caused 48,200 deaths in 2017 (a 74 percent increase from 2008 to 2017).

Although there was a significant progress in reducing emissions from heavy-duty trucks, less progress was done with passenger light-duty vehicles such as cars, SUVs, or pickup trucks. According to the scientists, emissions from these vehicles caused two-thirds of public health burden from transportation-related air pollution in 2017.

“If the trends of increased population density with an aging population, and a shift to larger passenger vehicles continue, emissions, especially in urban areas, will continue to become more harmful and it will be harder to achieve further public health gains by small incremental improvements in new vehicles,” said study senior author John Spengler, a professor of Environmental Health and Human Habitation at Harvard.

“Our study findings strengthen the case for policies at the municipal level that encourage electric vehicles while discouraging conventional gasoline vehicles and for making our cities more accessible for non-motorized transportation such as biking or walking.”

The study is published in the journal Proceedings of the National Academy of Sciences.

Reduced vehicle emissions have saved thousands of lives • Earth.com