According to a joint study conducted by South Korea, China and Japan, half of ultrafine dust (PM-2.5) in Korea was caused by domestic effects and 32 percent were from China.
The National Institute of Environmental Research (NIER) on Nov. 20 published a summary report of the "Long-range Transboundary air Pollutants research project (LTP) in Northeast Asia for policy-makers based on the research results of South Korea, China and Japan.
According to the report, Korea's self-contribution rate was 51 percent annually, China 91 percent, and Japan 55 percent after analyzing the causes of ultrafine dust at home and abroad in major cities such as Korea (Seoul, Daejeon, Busan), China (Beijing, Tianjin, Shanghai, Qingdao, Shenyang and Dalian) and Japan (Tokyo, Osaka, Fukuoka) using air quality model techniques in 2017.
In the case of Korea and Japan, slightly more than half of the ultrafine dust generated in Korea and Japan stems from domestic factors. In addition, most of the ultrafine dust in China has been caused by factors in China.
The impact of Chinese air pollutants such as sulfur oxides and fine dust on three Korean cities is estimated at 32 percent on average and 25 percent on Japan.
The impact of Korean air pollutants on China and Japan was calculated at 2 percent and 8 percent, respectively, while the impact of Japanese air pollutants on Korea and China was 2 percent and 1 percent, the report showed.
However, in case of being limited to the high concentration period of fine dust such as December to March, not the annual average, it has been found that the influence of external factors, especially those originating from China, will be expanded further.
The report is the first to be published by experts from South Korea, China and Japan since 2000 after jointly reviewing the research results. It was originally scheduled to be published last year, but the publication had been delayed due to different opinion from the Chinese side.
The report was released in February this year after Environment Minister Cho Myoung-rae and his Chinese counterpart Li Ganjie agreed to publish it before the Korea-China-Japan environment ministers' meeting slated for Nov. 23-24.
"It is meaningful that China has recognized the factors originating from China in the 30 percent range," said NIER President Jang Yoon-seok, adding, "This report will be a valuable scientific source for inter-country consultations to improve air quality in Northeast Asia."