The Seoul Metropolitan Government lifted an ultrafine dust warning Wednesday afternoon, 24 hours after it was issued, while the ultrafine dust advisory remained in effect for the country’s western regions, including the North and South Chungcheong and Jeolla provinces.

Following alarming levels of ultrafine dust in Korea, the Environment Ministry and metropolitan governments issued emergency fine dust reduction measures on Wednesday. The warning in Seoul was lifted after the level of particulate matter 2.5 micrometers or less in diameter fell to 34 micrograms per cubic meter at 2 p.m. 

Weather authorities forecast that rain accompanied by strong winds would wash away ultrafine dust across the country Thursday.

The Seoul Metropolitan Government banned running aged diesel vehicles registered before Dec. 31, 2005 that weigh over 2.5 tons from 6 a.m. to 9 p.m. Wednesday, the first time the city has done so. It also closed down 456 public parking lots and shortened operating hours of 12 air pollutant discharge facilities and 151 construction sites.

As part of measures to reduce the number of cars on roads, the city advised only vehicles with license plates that end with an odd number to be on the roads on Wednesday. Cars with license plates ending in even numbers are permitted on roads on even numbered dates when the measure is in effect. The measure is voluntary for regular drivers, but the ban is mandatory for civil servants.

Emergency pollution measures are issued by ministries and regional governments for the next day when the concentration level of PM 2.5 exceeds 50 micrograms per cubic meter.

Wednesday was the sixth time the emergency measures has gone into effect this year, the city government said.

The Environment Ministry also set an upper constraint of operation to 11 thermoelectric power plants in Incheon and the South Chungcheong and Gyeonggi provinces, putting a limit on the generation of electricity to 80 percent of the rated capacity from 6 a.m. to 9 p.m. on Wednesday.

The ministry expected a reduction of 1.1 million kilowatts of electricity for the day to produce a cut in the emissions of PM 2.5 by 2.3 tons, which is 3 percent of the overall emissions of coal power plants in one day.

The Environment Ministry has been running a pilot program for power plants since October and will officially implement it next year to deal with the air-quality problem.

According to Air Korea operated by Ministry of Environment and Korea Environment Corporation, levels of the ultrafine dust stayed at an alarming rate in the western part of the peninsula on Wednesday.

As of 4 p.m., the level of PM 2.5 recorded 36 micrograms per cubic meter in Seoul, 50 in Incheon, 77 in South Chungcheong Province, 72 in North Chungcheong Province and 93 in North Jeolla Province.

The figures are much higher than the daily average standard set by the World Health Organization, which is 25 micrograms per cubic meter.

PM 2.5 is produced by burning fossil fuels or biomass. Its increase in the air raises public health concerns, as it could cause respiratory diseases and other problems.

By Jo He-rim (herim@heraldcorp.com)