Independent measurements say cars are biggest culprit in Seoul’s air pollution

Posted on : 2017-06-28 16:07 KST Modified on : 2017-06-28 16:07 KST
Fine particle dust levels found to vary according to traffic levels on a weekdays and weekends
A participant in the “Out with Fine Dust!” project attaches a device to measure nitrogen dioxide and fine dust
A participant in the “Out with Fine Dust!” project attaches a device to measure nitrogen dioxide and fine dust

Fine dust from China? Yellow dust? Automobile exhaust? Coal-fired power plants?

The environmental group Green Korea United (GKU) recently joined forces with 130 citizens to independently measure Seoul’s air quality and determine the factors affecting it. Their findings showed automobiles to be the biggest culprits in atmospheric pollution - an apparent reflection of the particularly large number of cars traveling in the city.

On May 14-15, GKU joined citizens in setting up total suspended particle (TSP) and nitrogen dioxide concentration measurement kits at 105 locations near residential areas and analyzing the results. The TSP category includes all particles with a diameter of less than 100 micrometers (one-millionth of a meter); large TSP readings can be interpreted as signaling heavy fine dust concentrations. Nitrogen dioxide released during the combustion of fossil fuels combines with water vapor, ozone, and ammonia in the atmosphere to form fine dust. Both are major indicators for gauging air quality.

Findings from GKU’s “Out with Fine Dust!” project showed nitrogen dioxide readings to be higher for most measurement sites on Monday (May 15), a day with heavy vehicle traffic, than on Sunday (May 14), a holiday. The difference between weekend and weekday readings was highest in front of Exit 6 of Oksu Subway Station in the Seongdong district, where the Sunday measurement was 17 parts per billion (ppb) and the Monday measurement was 55.4 ppb. Seventeen parts per billion translates into 17 cubic meters of nitrogen oxide for every billion cubic meters of air.

The World Health Organization (WHO) recommended nitrogen dioxide threshold is 40 ppb. Large differences between weekend and weekday readings were found at the Gireum New Town bus stop in Seongbuk district (40.3 ppb on Sunday, 73.1 ppb on Monday) and Exit 4 of Songpa Subway Station (44.1 ppb on Sunday, 75.6 ppb on Monday). Both are sites with heavy vehicle traffic. Nitrogen dioxide is a toxic substance produced in large volumes with the combustion of fossil fuels like gasoline and can have a significant impact on respiratory diseases.

“Since Seoul doesn’t have many coal-fired power plants or factories, automobile exhaust has a dominant effect on nitrogen dioxide concentrations,” explained Daejeon University environmental engineering professor Kim Seong-tae, who took part in the study with GKU.

“More than anything, we will need to come up with ways of reducing automobile use if we want to reduce fine dust in the greater Seoul area,” Kim said.

TSP concentrations were found to be higher on weekends than weekdays, with a Sunday average of 203.1 micrograms per cubic meter and a Monday average of 87.7 ㎍/㎥. Kim explained that this appeared to be due to “heavy winds on Monday [May 15] causing dust to scatter.”

The study also showed differences between the readings gathered by citizens and the city’s official measurements. The average nitrogen dioxide reading calculated by citizens for May 14 was 19.3 ppb, compared to the city’s reading of 15 ppb. On May 15, the citizens found an average of 30.3 ppb, while the city gave a reading of 22 ppb. The difference appeared to be due to the citizens’ measurement devices being mostly positioned at heights of one to two meters above ground - similar to the height at which people breathe - while most of the city’s devices are positioned on tall buildings. Data on the city’s use of fine dust measuring devices showed the locations of fine dust measurement sites to be located on buildings measuring 10 meters or taller for 21 out of 25 districts.

“With the fine dust so bad, I have to keep taking allergy and rhinitis medication,” said Im Ok-soon, a 48-year-old apartment resident in the Yangcheon district who took part in the project with her daughter.

“In addition to more efforts by the public to use public transportation, the government needs medium- and long-term measures to deal with fine dust,” Im said.

GKU activist Bae Bo-ram said the project was designed “to help the public understand ideas for air quality improvement rather than just being vaguely worried about the quality of their air.”

Bae added that GKU plans to “expand the air quality measurement project to Gyeonggi Province and other parts of the greater Seoul area next year.”

By Hwang Keum-bi, staff reporter

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