Recent fine dust pollution in Seoul caused primarily by domestic pollution

Posted on : 2018-01-21 13:28 KST Modified on : 2019-10-19 20:29 KST
The findings contradict the popular view that the particulate matter originated in China
Citizens wearing masks to protect themselves from fine dust walk under a sign advising of an air quality emergency at Gwanghwamun Station in Seoul on Jan. 15. (by Baek So-ah
Citizens wearing masks to protect themselves from fine dust walk under a sign advising of an air quality emergency at Gwanghwamun Station in Seoul on Jan. 15. (by Baek So-ah

Analysts at South Korea’s National Institute of Environmental Research (NIER) have tentatively concluded that the high-density particulate matter, also known as fine dust, that blanketed the capital region between Jan. 16 and 18 was more influenced by domestic factors than foreign factors. This contradicts the widespread view that high-density fine dust originates in China.

After the year’s first emergency measures to reduce fine dust in the Seoul region were taken on Jan. 15, the fine dust density got even worse, triggering warnings about PM2.5 levels in the area on Jan. 16 and 17. The fine dust began to dissipate on the afternoon of Jan. 18.

When asked about the contribution rates of domestic and foreign factors on the recent density of fine dust around Seoul, a NIER spokesperson said, “While I cannot provide the details of our short-term analytical data, there was not a single day between Jan. 16 and 18 when foreign factors predominated. The foreign impact was greater on Jan. 15, but the domestic impact was greater on Jan. 16 and 17 because of air stagnation. On Jan. 18, there was an influx of yellow dust, but in our analysis domestic and foreign factors had a similar impact on the capital region.”

Until now, reports have said that foreign factors are responsible for 30-50% of fine dust in South Korea at normal levels and 60-80% during high density. These figures were included in a document published by the government in June 2016 about special measures for controlling fine dust, and they have been used as the main grounds for challenging the efficacy of policies aimed at reducing domestic fine dust. But one limitation of this analysis of contribution rates is that it was based on emissions data through 2014 and thus did not reflect the outcome of fine dust curtailment policies that have been implemented in South Korea and other countries since that time.

“In the past, foreign factors were greater when fine dust was at a high density and domestic factors were greater at other times. But from the end of last year until recently, these patterns seem to have been changing, with the domestic impact being similar to or even greater than the foreign impact even during times of high density. I think this calls for a causal analysis,” a NIER spokesperson said.

Setting weather factors aside, a change in the domestic and foreign contribution levels for fine dust can be brought about by emissions of nitrogen oxide and volatile organic compounds, which combine with particulate matter in the atmosphere to produce secondary particulate matter. Since the domestic and foreign contribution rates are relative to each other, the domestic contribution rate could rise even when domestic fine dust curtailment efforts succeed at reducing atmospheric pollutant efforts, if emission reductions are even greater overseas.

Over the past five years, China has made a strong push for reducing fine dust based on an action plan for preventing atmospheric pollution drawn up by its State Council in 2013. These measures were so strict that they banned coal heaters in school classrooms, leading the media to condemn this as an inhumane practice. As a result, China’s atmospheric pollution has continued to decline. According to an environmental status report published by China’s Ministry of Environmental Protection, the average density of ultrafine particulate matter in 74 major Chinese cities (including the capital region, which includes Beijing, Tianjin and Hebei) was 50 ㎍/㎥, which was 31% lower than the 72 ㎍/㎥ recorded in 2013, when the action plan was put into effect.

By Kim Jeong-su, senior staff writer

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