The consequences of air pollution are troubling policy makers and leaders around the globe, but what if premature deaths from poor air quality could be avoided?

A new study by Duke scientists showed that as many as 153 million premature deaths linked to air pollution could be prevented if countries sped up their timeline for reducing fossil fuel emissions. It was published March 19 in the journal “Nature Climate Change.”

“Since air pollution is something we understand very well and have extensive historical data on, we can say with relatively high certainty how many people will die in a given city under each scenario,” said Drew Shindell, professor of earth sciences at the Nicholas School of the Environment, in a press release. “Hopefully, this information will help policymakers and the public grasp the benefits of accelerating carbon reductions in the near term, in a way that really hits home.”

The research examined how many lives could be saved in 154 of the largest urban areas worldwide if governments agreed to cut emissions in the near future, instead of postponing them. They found that premature deaths would drop on every continent, especially in Asia and Africa.

“What this study really brings to light is that there are a lot of additional local impacts and benefits that can be achieved through climate policy,” said Karl Seltzer, a Ph.D. student in earth and ocean sciences who worked on the study.

To create the estimates, the team used computer simulations of future carbon emissions and pollutants like ozone and particulate matter, and tested three different scenarios. The first scenario showed the effects of accelerated emission reductions and almost no negative emissions during the rest of this century, while the second simulated the outcome of allowing slightly higher emissions in the short term but with enough overall reductions to limit global warming to 2°C by the end of the century. In the third test, short-term emissions were reduced even more sharply, limiting warming to 1.5°C in the remainder of the century.

The researchers then calculated how each of these scenarios would impact human health around the world by using models based on data about air-pollution related deaths.

The measurements showed that Kolkata, India and Delhi, India were the cities that would benefit the most from accelerated emissions cuts. About 4.4 million lives would be saved in Kolkata and up to four million would be saved in Delhi.

In addition, there were 13 cities in Asia or Africa that could see more than one million deaths avoided, and about 80 other cities in which at least 100,000 lives could be saved.

Moscow, Mexico City, Sao Paolo, Los Angeles, Puebla and New York could also each avoid between 320,000 and 120,000 premature deaths.

Seltzer explained that many climate goals now use the idea of “negative emissions,” which involves using technology to remove more carbon from the atmosphere than we emit. However, this doesn’t take into account the fact that harmful gases enter the environment alongside carbon, such as sulfur dioxide.

“There are lots of these externalities that aren’t really considered when you think about climate policies,” he said. “When you rely on this negative emissions technology, they’re not considering these co-emitted pollutants.”

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These results show the tangible importance of achieving climate goals and reducing global warming, which can often seem abstract, Seltzer noted.

“What this study really brings to light is that there are a lot of additional local impacts and benefits that can be achieved through climate policy,” he said.

The research also underscores how reducing emissions can save human lives. Air pollution is a major cause of cardiopulmonary diseases as well as heart attack, stroke and respiratory infection. Seltzer explained that about five million people around the world die from causes directly attributable to air pollution.

He added that about 100,000 of these deaths occur in the United States, which many might find surprising because the United States is often viewed as a country with relatively clean air.

“It’s one of the first studies that pulls it all together and says, 'What if we were to achieve some of these goals—not just to achieve a particular climate outcome—but to maximize benefits to human health?'” he said.