34% of fine dust came from China last summer

About 34 percent of fine dust pollution in Korea during early summer last year came from China, according to a joint scientific study on air quality conducted by Korean and U.S. agencies.

The results of the air quality field study by Korea’s National Institute of Environmental Research (NIER) and the U.S. National Aeronautics and Space Administration (NASA), conducted from May 2 to June 12, 2016, was released Wednesday.

In a press conference also attended by NASA researchers, Korea’s Ministry of Environment and NIER announced the results of the Korea U.S.-Air Quality (Korus-AQ) study.

The study found that 52 percent of particulate matter with a diameter of 2.5 micrometers or less (PM2.5), major air pollutants that are hazardous to health, detected in the atmosphere of Olympic Park in southern Seoul, was due to domestic factors and 48 percent to external factors.

Of these external sources, 34 percent came from China, of which 22 percent was attributed to Shandong, 7 percent to Beijing and 5 percent to Shanghai. Another 9 percent came from North Korea and the remaining 5 percent came from Japan, the Yellow Sea and Northeast China area. Over 70 percent of sulfur dioxide and 30 percent of nitrogen oxide and ammonia was from China, the study found.

“This study is not reflective of the yearly average,” said Kim Jeong-soo, director of NIER’s Transportation Pollution Research Center, “and also excludes periods of high levels of fine particulate matter in the atmosphere.”

According to local studies, China contributes 30 to 50 percent of particulate matter in Korea, and as much as 60 to 80 percent when there are high concentrations of fine dust in the atmosphere. The study showed serious levels of ozone pollution in Seoul and metropolitan areas.

It also found days when fine dust concentration contributed by domestic factors alone exceeded the World Health Organization’s recommended standard of 25 micrograms per cubic meter within a 24-hour period.

The Korus-AQ study was launched in 2013 through an agreement between NASA and Korea’s Environment Ministry, and it involved 580 Korean and international scientists.

BY KANG CHAN-SU, SARAH KIM [kim.sarah@joongang.co.kr]