Climate Change and Aging Population Could Quadruple Ozone-Related Deaths in China.

Climate change will likely worsen ozone pollution in already heavily polluted areas, leading to increased ozone-related health burdens and deaths, especially among the elderly. China, which is the world’s largest greenhouse-gas emitter and has a rapidly aging population, has been making progress in reducing particle pollution in recent years, but ozone pollution has been getting worse.

A new study co-authored by a School of Public Health researcher estimates that projected changes in climate, emissions, population size, and population aging could nearly quadruple ozone-related deaths in China.

The study, published in PLOS Medicine, estimates the annual number of ozone-related deaths in China could nearly quadruple by the 2050s under the worst-case climate change scenario, with 78,560 more deaths each year than the current rate. However, in a best-case scenario of emission reduction, China’s annual ozone-related death rate could be 24 percent lower in the 2050s than today.

“Aggressive action to solve the climate crisis now can pay huge health dividends in the future,” says Patrick Kinney, Beverly A. Brown Professor for the Improvement of Urban Health and the study’s senior author.

The researchers used data from April 2013 through October 2015 on ambient ozone observations, population change projections, and baseline mortality rates in 104 cities across China, accounting for approximately 13 percent of the total population of the country. They then used a global chemistry-climate model and recently available ambient ozone monitoring data to estimate future changes in ozone-related deaths from 2013–2015 to 2053–2055 under different climate and population change scenarios.

In the climate change scenario known as RCP 4.5 by climate scientists, global greenhouse gas emissions peak around 2040, then begin to decline. Using this scenario in their model, the researchers saw a 24-percent decrease in annual ozone-related deaths in China by the 2050s.

Factoring in seasonal differences in ozone health effects, as well as season-specific changes in ozone concentrations, the researchers saw a net yearly increase of 22.3 percent in ozone-related mortality under the higher-emission scenario known as RCP 8.5.

Finally, when they considered that the proportion of the Chinese population at or over 65 years old is expected to increase from 8 percent in 2010 to 24-33 percent in 2050, the researchers estimated ozone-related mortality under RCP 8.5 would increase by 110 to 363 percent, or 23,838 to 78,560 total additional deaths, by the 2050s.

Kinney notes that a key factor in these increased mortality rates will be the extended smog season in China’s urban areas. “Climate change will push the smog season beyond just summer, with potentially serious consequences for human health,” he says.

The study’s lead author is Kai Chen of the Helmholtz Institute in Munich. The other co-authors are: Arlene M. Fiore of Columbia University; Renjie Chen and Haidong Kan of Fudan University in Shanghai; Leiwen Jiang of Shanghai University and of the US National Center for Atmospheric Research; Bryan Jones of Baruch College; Alexandra Schneider and Annette Peters of Helmholtz Zentrum München in Neuherberg, Germany; and Jun Bi of Nanjing University.

—Michelle Samuels