Pollution Rides on the Wind: The Effects of Transboundary Air Pollution from China on Ambient Air Quality in South Korea

South Korea has suffered from high levels of air pollution in recent years. South Korea experiences sand storms originating from deserts in west China and Inner Mongolia every spring for over 2,000 years. Over the last decade, as the coal-based Chinese economy continues to grow explosively, air pollutants from industrial zones and coal-combusting power plants started blowing over on the prevailing westerly wind to the nearby countries, Korea and Japan. Further, the problem gets more severe when more fossil fuels are burned for winter heating in China. The Chinese government also acknowledges that a part of emissions generated in their mainland may travel long distances and affect air quality in neighboring countries, however, the level of contribution is still a subject of considerable debate. The long-range transport of air pollutants from China accounts for roughly 26-50% of annual contributions of PM_10 in Korea (Korean Government 2013, Li et al. 2014, Park and Han 2014). In this study, I attempt to econometrically identify the role of wind in the local air quality as a transport of air pollution. The regression models analyze the marginal effects of long-range transport and determines which specific wind directions have the greatest effects each season on South Korean ambient air quality. This paper uses two sets of panel data: daily average concentrations of PM_10 and weather monitoring data (precipitation, temperature, wind speed, and wind direction). The data are collected from seven metropolitan cities and nine provinces in South Korea for nine years (2006-2014). I find that westerly wind increases PM_10 concentrations in South Korea. The marginal effect of the westerlies on annual PM_10 is 0.883 μg/m^3 higher than the east wind, accounting for 3.38% with the annual mean wind speed. Seasonally, the effect of westerlies peaks in winter (8.13%) when more pollutants are generated in China, followed by summer (7.55%), spring (5.99%), and fall (3.21%). More specifically, the northwest (NW) wind has the greatest effects in summer (13.75%) and winter (11.11%) and is in the direction from Beijing to South Korea. Furthermore, the west-southwest (WSW) shows the largest impacts in spring (8.36%) and fall (7.71%), and southwest wind (SW) is the greatest year-round, accounting for 12.26% of the annual mean PM_10. These winds correspond to the direction from Shanghai to South Korea. This is important because it not only shows the effects of transboundary air pollution from China, but also informs us about the air pollutants’ likely main contributing sources, Beijing and Shanghai in China. Based on the results, the average effects of the transboundary air pollution are estimated to account for 7.71-13.75% of the mean PM_10 concentrations depending on season. This brings about a sharp contrast with that of previous studies that estimate the Chinese contribution on PM_10 in South Korea of approximately 26-50%.