Nov. 21 (UPI) -- South Korean climate experts said Thursday ultrafine dust from China has declined, a day after a joint research report on long-range transport pollution was released in Seoul.
According to the report that includes Chinese, Japanese and South Korean research, ultrafine dust known to cause respiratory problems persists in three major Korean cities: Seoul, Daejeon and Busan, Yonhap reported.
The study said 51 percent of pollutants originated from within Korea, 32 percent from China and the remaining 2 percent from Japan, with the rest originating from North Korea, Mongolia and Southeast Asia.
Kim Soon-tae, a professor of environment and safety engineering at Ajou University, said Thursday at a Seoul climate conference Chinese pollutants have declined since 2013, when the world's second-largest economy began tackling fine dust.
Within China, fine dust emissions declined by 50 percent since 2013. Chinese-origin pollutants fell by 30 percent in South Korea, Kim said, referring to simulation tests he conducted as part of his research.
Fine dust pollution resulting from local power plants and pollutants floating from China have been described as a disaster in Seoul; on Thursday Kim said South Korea must do more to tackle domestic pollutants.
The joint report on transnational pollution is under scrutiny by other analysts, however.
Jang Jae-yeon, a professor of preventive medicine at Ajou University who studies environmental pollution, said there may have been a "political compromise" between the South Korean and Chinese governments in arriving at the exact percentages stated in the joint summary, local news network MBC reported Thursday.
China and South Korea have been in environment-related negotiations, during which Beijing may have agreed to acknowledge at least 32 percent of ultrafine dust originated from China, Jang said.
Jang also said there were differences among the Chinese, Japanese and Korean findings about pollution origins, according to MBC.