A team of researchers from , and found that more than 30% of the ultra-fine dust (PM 2.5) in Korea, and 25% of PM 2.5 in Japan were from China.

This is the first time China has acknowledged the responsibility after years of rejection, according to South Korea’s Chosun Ilbo newspaper .

The Korea National Institute of Environmental Studies published the results of the research in a report signed by all three countries. The report, published on November 20 before the tripartite environment minister’s meeting on November 23, raised hopes of cross-border cooperation to combat harmful emissions.

But skeptics point out that the three countries made the figures by averaging all their own estimates for major cities, instead of independently examining them.

The object of analysis was three cities of Korea (Seoul, Busan and Daejeon), six cities of China (Beijing, Tianjin, Shanghai, Qingdao, Shenyang and Dalian) and three cities of Japan. Japan (Tokyo, Osaka and Fukuoka).

In addition, data from December to March, when the most severe toxic haze, was not included in the analysis.

According to the report, China was the source of 32.1% of ultra-fine dust in Korea in 2017, while 51.2% came from South Korea itself and 1.5% from Japan. The remaining 15.2% comes from Mongolia, and Southeast Asia.

In China, 91% of ultrafine dust is believed to come from the country itself, while South Korea accounts for 1.9% and Japan 0.8%.

In Japan, the report says 55.4% is self-made while 24.6% is from China and 8.2% from South Korea.