Fine dust reached "bad" levels across Korea on Friday afternoon, prompting dismayed reactions from residents.
The poor air quality was caused by fine dust that blew in from abroad on Thursday, combined with domestically generated particles that became trapped due to stagnant atmospheric conditions. Ultrafine dust (PM2.5) concentrations between 36 and 75 micrograms per cubic meter are classified as "bad," while levels of 76 micrograms or higher are rated "very bad."
Southern regions may see fine dust levels drop to moderate during the daytime, but concentrations are expected to return to "bad" levels in the evening as atmospheric stagnation resumes.
Air quality is forecast to remain poor on Saturday. Daejeon, Sejong, North Chungcheong Province, the Honam region, Busan, Daegu, South Gyeongsang Province, and Jeju will continue to experience bad fine dust levels on the 17th. The Seoul metropolitan area and South Chungcheong Province will maintain bad levels through the morning, while western Gangwon Province, Ulsan, and North Gyeongsang Province will see such conditions persist until early afternoon. Air quality is expected to gradually improve in the afternoon as atmospheric stagnation eases.
According to the National Air Quality Forecast Center, there is a 50 percent probability that average ultrafine dust concentrations this winter will be higher than last year, with a 30 percent chance of similar levels. The probability of lower concentrations compared to previous winters is only 20 percent. Winter typically brings worse fine dust conditions due to poor atmospheric dispersion and reduced precipitation.
Meanwhile, more than half of Korea's winter ultrafine dust originates from China, according to research. A recent report from the National Institute of Environmental Research's "International Joint Air Quality Investigation" found that 55 percent of domestic ultrafine dust came from China, while 29 percent was generated domestically.