SEOUL, Feb. 4 (Yonhap) -- Seoul has seen a drastic increase in the monthly average level of ultra fine dust in January, compared with data recorded over the previous three years, data showed Monday.
The average level of ultrafine dust particles, smaller than 2.5 micrometers in diameter, was recorded at 38 micrograms per cubic meter in the capital city last month, according to the National Institute of Environmental Research, a think tank under the Ministry of Environment.
The figure marks the highest level since 2015, when the government began to track data on the country's ultrafine dust level.
In 2015, it stood at 25 micrograms per cubic meter, 27 micrograms per cubic meter in the following year and 32 micrograms per cubic meter both in 2017 and last year.
Ultrafine dust is considered more harmful than general fine dust particles as it is known to penetrate deeper into human organs, especially into the respiratory system.
As for the non-ultra fine dust, smaller than 10 micrometers in diameter, the average level came to 66 micrograms per cubic meter in Seoul, the highest since 2010.
The think tank cited the worst fine dust that enveloped the country last month, which prompted local metropolitan governments to issue advisories for three consecutive days for the first time ever.
On Jan. 14 alone, Seoul recorded a daily average ultrafine dust level of as high as 129 micrograms per cubic meter, the highest ever tallied. The second highest level is the 99 micrograms per cubic meter recorded on March 25, 2018.
Source: Yonhap News Agency