Researchers say that recent reductions in vehicle emissions have saved thousands of lives and hundreds of billions of dollars in the United States.

Researchers at Harvard University who study the environment and public health have studied the impact of reduced vehicle emissions for more than a decade. They found that the death toll dropped from 27,700 in 2008 to 19,800 in 2017, and the economic benefits of reducing emissions totaled US$270 billion.

In a study published on Wednesday in the Proceedings of the National Academy of Sciences, the researchers also concluded that if vehicles continue to emit 2008 air pollution levels throughout the period, the total number of deaths in 2017 will be 2.4 times higher .

Studies have shown that due to stricter supervision of fossil fuel companies and automakers, light vehicles such as cars, pickup trucks and SUVs are mainly responsible for reducing the health burden.

But the researchers found that these benefits are limited by population growth and aging, as well as by drivers buying larger cars and driving more.

“Despite significant progress in reducing emissions, this offsetting effect of population and large vehicles still exists,” said Ernani Choma, an environmental health researcher at Harvard University and lead author of the study. “Therefore, if we do not formulate stricter policies, it will be difficult to make substantive progress.”

According to experts who are not affiliated with the research team, although there have been previous studies on the health benefits and economic impact of emission reductions, this study more accurately describes how emissions affect public health.

Sumil Thakrar, an air quality researcher at the University of Minnesota, said: “Good environmental policies have greatly reduced traffic emissions in the past decade.” “But it is difficult to understand the benefits of these emission controls well. , Because it needs to keep track of many other moving parts. And I think the author did a great job.”

The study also looked at the climate benefits of curbing air pollution from vehicles, but found that these benefits only accounted for 3% to 19% of the overall economic benefits.

Susan Anenberg, associate professor of environmental and occupational health and global health at George Washington University, said this is because most of the ways the United States reduces traffic emissions are aimed at curbing air pollution, not climate change.

“Catalytic converters, diesel particulate filters, they are removing pollutants from (the environment), but they have no effect on (carbon dioxide),” she said.

This is one of the reasons why Qiao Ma and his colleagues recommend stricter policies to curb emissions. He said another reason is that if the upward trend in population and vehicle size and usage continues, the policies that create health benefits highlighted in the study will not be as effective in the future.

He said: “If we look forward to 2030, nothing will change, you will only see a slight drop in the number of deaths caused by car exhaust. “So this is the case for stricter policies.”