Air pollution is the cause of more than 1 million premature deaths per year in China, according to the World Health Organization. A new study suggests that future climate change may worsen air quality for more than 85% of China’s population, leading to an additional 20,000 deaths each year (Proc. Nat. Acad. Sci. U.S.A. 2019, DOI: 10.1073/pnas.1812881116). The study is the first of its kind to look specifically at how changes in weather patterns may affect environmental health in the world’s most populous country.
The research team pulled together climate, air quality, and epidemiological models. This allowed them to predict the effects of more frequent heat waves, heavy precipitation, and atmospheric stagnation events. During atmospheric stagnation, particulate matter—which is associated with health problems such as asthma and heart attacks—accumulates in the air due to low winds and light or no precipitation. Heat waves can boost ozone production. Both stagnation events and heat waves worsen air quality, while heavy rains, which wash particulate matter out of the air, improve it. The researchers found that while all three types of events are predicted to occur more frequently, the increase in deaths due to stagnation and heat waves is much higher than the decrease in deaths from heavy precipitation.
Dan Westervelt, an atmospheric scientist at Columbia University’s Lamont-Doherty Earth Observatory, says that breaking down the deaths between different extreme events is a “nice addition” to the existing literature on future air quality. However, he thinks the study may have been too conservative in its predictions. 20,000 additional premature deaths is “definitely an underestimate,” he says, noting that the study is based on a “middle-of-the-road” climate scenario that many climate scientists now believe is out of reach.
Hong acknowledges the limitations of this study. Future work, he says, could examine different climate scenarios and look at demographic shifts in the Chinese population.
Sally Ng, an atmospheric chemist and chemical engineer at Georgia Institute of Technology, says the study provides a “road for researchers from different communities to come together” to address what she sees as two of the most daunting environmental challenges of our time. “We often talk about climate change and air quality as separate issues,” Ng says. To protect people from the worst outcomes of climate change, she says, researchers will need to think about the ways the two can exacerbate each other.