Changing winds, China blamed as thick smog blankets Korea

Social Affairs

Published: 01 Nov. 2023, 19:04

Changing winds, China blamed as thick smog blankets Korea

Two people look down on the city of Osan in Gyeonggi from Bojeok Temple as thick fine dust engulfs the area on Tuesday. [NEWS1]

Fine dust is expected to continue blanketing Korea in the coming days, largely due to the recent smog engulfing Beijing.

The hourly average concentration of fine dust, specifically PM 2.5, in Eunpyeong District, northern Seoul, rose to as high as 40 micrograms per cubic meter, falling within the “bad” level (36 to 75 micrograms per cubic meter) as of 4 p.m. Wednesday, according to Seoul Metropolitan Government’s real-time air quality data.

“Fine dust concentrations have continuously risen in the last few days due to air stagnation,” said Yang Geum-hee, a research associate at the National Institute of Environmental Research, adding that more air pollutants will enter the country, particularly in the greater Seoul area, from overseas.

According to experts, high concentrations of fine dust are observed, especially during the fall season, as the west wind brings in air pollutants from China. This seasonal trend has been occurring for the past decade.

The monthly average concentration of fine dust in the past ten years showed that the figure began to surge entering the fall season.

According to the city government’s air quality data analyzed by the JoongAng Ilbo, the yearly average concentration of fine dust in November was 23.9 micrograms per cubic meter, around 43 percent higher than in October.

The figure was even higher than the yearly average concentration of 23.6 micrograms per cubic meter in April when the country is heavily affected by yellow dust. This trend is largely due to the changing directions of winds in the summer and fall, experts say.

During the summer, clear air blows in from the Pacific Ocean in the south, while air pollutants from China are brought into the country during the fall as the winds blow from the west or the northwest.

As the winter season approaches, the planetary boundary layer height, which allows mixing and dilution of air pollutants, becomes lower, causing less influx of fine dust to dilute.

“There is a great possibility that the fine dust concentration will be higher as the atmospheric capacity itself becomes smaller, even if the same amount of pollutants exist,” said Lee Dae-hyun, head of the National Institute of Environmental Research’s Air Quality Forecasting Center.

The average concentration of fine dust in Korea has been decreasing in the last three years since the pandemic. The figure dropped from 25 micrograms per cubic meter in 2019 to 18 micrograms per cubic meter in 2022.

However, the air quality has started to worsen this year.

The average concentration of fine dust from January to October this year is more than 10 percent higher compared to the same period last year.

Regions in northern China that have suffered from a high concentration of nitrogen dioxide in the past two weeks appear in red on a data image from the Copernicus Sentinel satellite. [EUROPEAN SPACE AGENCY]

According to the European Space Agency’s satellite data, China's average concentration of nitrogen dioxide surged rapidly in the last two weeks compared to a month ago.

China’s northern regions close to the Korean Peninsula, including Beijing, were in red, indicating a high concentration of nitrogen dioxides.

Nitrous dioxides are one of the critical pollutants that cause fine dust and are known to affect people’s cardiovascular systems significantly.

Smog has blanketed major cities in northern China lately, with local authorities issuing their second-highest pollution warning on Monday.

Beijing said it would implement traffic control measures if the highest air pollution warning is issued in the capital.

The AFP said smog, blamed on unfavorable weather conditions, will linger in the region until temperatures drop later this week, citing official forecasters.

BY CHON KWON-PIL, CHO JUNG-WOO [cho.jungwoo1@joongang.co.kr]