Ultrafine dust density soars to 'very bad' level in greater Seoul

SEOUL. KAZINFORM The greater Seoul area was blanketed by extraordinarily heavy concentrations of locally generated ultrafine particles on Friday, but its air quality will return to normal over the weekend due to rainfall, a state monitoring agency said.

According to the state-run National Institute of Environmental Research, the hourly average density of ultrafine particles smaller than 2.5 micrometers in diameter, known as PM 2.5, soared to 95 micrograms per cubic meter as of 10 a.m. The PM 2.5 level reached a peak of 115 micrograms per cubic meter in Seoul on Friday morning, the institute noted, Yonhap reports.

The hourly average PM 2.5 concentrations also reached 87 micrograms in Gyeonggi Province that surrounds Seoul and 78 micrograms in Incheon, 40 kilometers west of the capital, as of 10 a.m., it said.

The weather authorities here categorize concentrations of PM 2.5 between zero and 15 micrograms as «good,» between 16 and 35 as «normal,» between 36 and 75 as «bad» and more than 76 as «very bad.»

The central and southern regions also posted bad levels of PM 2.5, with 61 micrograms in North Chungcheong Province, 55 micrograms in Sejong, 46 micrograms in Daejeon, 51 micrograms in Daegu and 42 micrograms in Gwangju, it said.

The density of fine dust particles smaller than 10 micrometers in diameter, known as PM 10, also surged to bad levels in the capital area, with 128 micrograms per cubic meter in Seoul, 125 micrograms in Gyeonggi and 117 micrograms in Incheon as of 10 a.m.

The institute forecast that the density of ultrafine and fine particles will remain at bad to very bad levels in the central region, including Seoul, throughout the day, as locally generated air pollutants accumulate due to stagnant atmospheric conditions.

But the central region's air quality will return to normal beginning Saturday afternoon due to atmospheric diffusion and rainfall, it said.