THE IMPACT OF CHINA’S POLLUTION ON MORTALITY IN SOUTH KOREA

04 Dec 2019

Air pollution from China leads to excess mortality in South Korea, according to new research by Ruixue Jia and Hyejin Ku, published in the November 2019 issue of The Economic Journal

They estimate that had the air quality index (AQI) in China been lower by 12 points, South Korea would have experienced 2400 fewer deaths from respiratory and cardiovascular diseases over ten years in the 2000s.

This study establishes a clear causal link between pollution in China – transported to localities in South Korea by Asian dust – and respiratory and cardiovascular mortality rates in South Korea.

Establishing the link between China’s pollution and harmful effects in South Korea is challenging since it is not just China who pollutes but also other countries including South Korea.

Emission cycles in China and South Korea may also be correlated due to similar business cycles. Therefore, just because the observed air quality in Seoul deteriorates in periods when China is more polluted does not mean that the pollution must have originated from China.

To address this challenge, the authors exploit the phenomenon of Asian dust -- a meteorological event in which yellow dust clouds passing over China are carried eastward to South Korea by strong and stable westerly winds.

The key idea is that, unlike regular winds, the path of Asian dust can be more easily traced. As the incidence of Asian dust varies greatly over time and across localities in South Korea for reasons unrelated to local activities, this allows to isolate and quantify the pollution coming from China only. The authors implement this idea by examining how the mortality rates in a district exposed to Asian dust change with the AQI in China.

The authors’ conservative estimate shows that had the AQI in China been lower by 12 (one standard deviation in the sample), South Korea would have experienced 2400 fewer deaths from respiratory and cardiovascular diseases over ten years in the 2000s.

As this is an estimate of China’s pollution impact on South Korea that operates via Asian dust, a rare event occurring once a month on average, it is likely a lower bound of the overall effect of China’s pollution on South Korean mortality, as strong westerly winds – outside Asian dust episodes – are also capable of transporting Chinese pollution.  

In recent years, China has been pressured by the international community to reduce pollution. This study shows that the health benefits of cutting air pollution in China are not confined to the Chinese citizens but reach beyond country borders.

Is China’s Pollution the Culprit for the Choking of South Korea? Evidence from the Asian Dust’ by Ruixue Jia and Hyejin Ku is published in the November 2019 issue of The Economic Journal

Ruixue Jia

Associate Professor | School of Global Policy and Strategy, UCSD, USA | (858) 534-5969 | rxjia@ucsd.edu

Hyejin Ku

Lecturer | Department of Economics at University College London, UK | (020) 3549-5344 | h.ku@ucl.ac.uk