Harvard Study Finds Lower Vehicle Emissions Cut Deaths by the Thousands, But More Work Ahead

In Harvard University's decade-long study of decreasing emissions' impact on public health, the Proceedings of the National Academy of Sciences found that if vehicles continued to emit 2008's level of air pollution up until 2017, deaths would have been 2.4 times higher. Deaths attributed in some way to air pollution dropped from 2008's 27,700 to 19,800 in 2017, but thousands of more lives lives could have been saved over the decade if emissions had dipped even further.

The study found that light-duty vehicles reducing emissions they create can be attributed to the lower death toll. Despite this encouraging sign, aging drivers and a steady increase in driving resulted in the potential benefits being diminished.

"Despite substantial progress in reducing emissions, you have this counteracting effect of population and larger vehicles," said the study's lead author Ernani Choma. "So it will be hard to achieve substantial progress if we don't enact more stringent policies."

This study could potentially be the clearest depiction yet of how carbon emissions affect public health. Air quality researcher Sumil Thakrar told the Associated Press that understanding the correlation between emissions and health is critical.

"Good environmental policy has drastically reduced transportation emissions over the past decade," said the University of Minnesota researcher. "But getting a good understanding of the benefits of those emissions controls is hard because it requires keeping track of a lot of other moving parts. And I think the authors do a remarkable job."

Cars on Freeway
A new study from Harvard finds that thousands of lives could have been saved over the past decade if vehicle emissions decreased. Above, cars make their way down the aging 110 freeway toward downtown Los Angeles, California, during the morning commute on April 22, 2021. Photo by Mario Tama/Getty Images

The study also looked at the climate benefits that resulted from curbing air pollution from vehicles, but found that those benefits only made up 3% to 19% of the overall economic gains.

That's because most approaches for reducing transportation emissions in the U.S. have been aimed at curbing air pollution, not climate change, said Susan Anenberg, associate professor of environmental and occupational and global health at George Washington University.

"Catalytic converters, diesel particulate filters, those are taking pollutants out of the (environment), but those aren't doing anything for (carbon dioxide)," she said.

That's one reason Choma and his colleagues recommend tougher policies to curb emissions. Another reason, he said, is that if the upward trends in population and vehicle size and use continue, the same policies that created the health benefits highlighted in the study won't be as effective in the future.

"If we look ahead to 2030 and nothing has changed, you're only going to see a modest drop" in deaths from vehicle emissions, he said. "So that's the case for more stringent policies."

The Associated Press contributed to this report.

Hollywood Freeway
According to a new report, researchers who study the environment and public health say thousands of lives and hundreds of billions of dollars have been saved in the United States by recent reductions in vehicle emissions. Above, traffic crawls along the Hollywood Freeway in Los Angeles, California, on Dec. 12, 2018. AP Photo/Damian Dovarganes, File