PM2.5 in China and South Korea
Note: This figure illustrates the evolution of monthly average hourly PM2.5. The Northwest region in South Korea is defined as cities in South Korea that have more than or equal to 35% of frequency of trajectories coming from China.
Leaders have long thought that air pollution crossing lines from neighboring countries posed a significant challenge. But how much of a challenge and what to do about it has remained an open question. University of Chicago Harris Public Policy’s Koichiro Ito and his co-authors measured the toll of transboundary air pollution on people’s health. Specifically, they studied South Korea, which experiences strong westerly winds from China during the fall and winter in the Northwest part of the country. They found that these winds lead to significantly higher levels of pollution compared to southeast South Korea. Yet, the northwest and southeast experience similar pollution levels during the spring and summer—when there is far less westerly wind from China.
The researchers found that this pollution has a direct impact on people’s health in South Korea, leading to a 0.6 percent increase in mortality for every one microgram per cubic meter increase in transboundary particulate matter pollution (PM2.5 ). That translates to an additional 31.2 deaths for every million people annually. The youngest members of society—babies who are a year old or younger—are the most vulnerable, with the mortality rate increasing by 2.1 percent for every one microgram per cubic meter increase in transboundary particulate pollution from China.
After China began its “war on pollution” in 2014, which came with a series of strong clean air rules, pollution significantly declined nationwide. Ito and his coauthors found that China had a 14.07 microgram per cubic meter drop in particulate pollution and South Korea had a 9.63 microgram per cubic meter drop in transboundary particulate pollution from China from 2015 to 2019. This drop led to fewer deaths from transboundary air pollution—about 300 fewer deaths for every million people a year—which they calculate saved South Korea $2.62 billion per year.