November 14, 2017

Actions to significantly slow climate change would improve air quality in the United States, avoiding roughly 24,000 premature deaths associated with air pollution in the year 2050.

This is the main conclusion of new research from the University of North Carolina at Chapel Hill, published Nov. 14 in the journal Environmental Research Letters.

The study also had the novel finding that, of the health benefits that would result for U.S. residents following a reduction in greenhouse gas emissions, a significant portion would stem from emission reductions occurring outside the country.

Dr. Jason West

Dr. Jason West

This research was led by co-authors associated with the UNC Gillings School of Global Public Health, including Jason West, PhD, associate professor in the Department of Environmental Sciences and Engineering, and former doctoral student Yuqiang Zhang, PhD, now a postdoctoral researcher with the Environmental Protection Agency.

Using computer models, West, Zhang and colleagues simulated future air pollution both globally and in the U.S., comparing a scenario in which no action is taken to reduce global greenhouse gas emissions with one in which global greenhouse gas reductions significantly slow climate change. In doing so, they accounted for how shifts in greenhouse gas emissions would affect levels of other air pollutants.

“Taking action to reduce GHG emissions often shifts us away from highly polluting energy sources and toward sources that cause less air pollution,” West said. “For example, shifting from coal-fired power plants to renewable energy reduces emissions of both greenhouse gases and air pollutants that are important for health.”

The researchers then projected the reduction in premature deaths in the year 2050 that would result from improved air quality. Negative health effects caused by exposure to air pollution include premature deaths from heart attack, stroke, chronic obstructive pulmonary disease and lung cancer – all of which are linked with exposure to fine particulate matter in the air – as well as cardiopulmonary disease, which is linked with ozone exposure.

In their analysis, the investigators found that these avoided premature deaths in the U.S. would provide a monetized health benefit of between $137 per ton of carbon dioxide emissions reduced (at a high valuation) and $45 per ton (at a low valuation). These benefits would likely be greater than the cost of reducing greenhouse gas emissions, suggesting a justification for action in cost-benefit terms.

Additionally, the study authors used their computer models to separate out the health benefits that would come from greenhouse gas emission reductions within the U.S. and those that would result from reductions in other countries. They found that 15 percent of the total U.S. health benefits related to fine particulate matter reduction and 62 percent of the benefits related to ozone reduction actually would stem from emission reductions taking place in foreign nations.

“Since air pollution is mainly local, previous studies tended to focus on the health benefits of local or national greenhouse gas reductions,” West explained. “But air pollution can move beyond national and even continental borders. We found that when we included greenhouse gas reductions within foreign nations in our models, the health benefits to the U.S. were much greater.”

These study findings were released following current events in which the U.S. pulled out of the 2015 Paris Agreement on climate change, through which most nations worldwide pledged to reduce greenhouse gas emissions.

“We showed in this study that addressing climate change can bring tangible benefits for human health through improved air quality,” said West, “and that health benefits are even greater when the U.S. reduces its emissions concurrently with reductions in other nations.”


Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or

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