SEOUL • South Korea's President Moon Jae-in has ordered the government to take extraordinary measures to fight fine dust pollution that has choked the country for days and was expected to hit record levels yesterday.

Seven major cities including Seoul recorded all-time high concentrations of particulate matter smaller than 2.5 micrometres (PM2.5) in the atmosphere as of 7pm, said the National Institute of Environmental Research (Nier).

Classified as a first-degree carcinogen by the World Health Organisation, PM2.5 particles penetrate deep into the human respiratory system and can trigger a variety of illnesses.

South Korea classifies levels of PM2.5 above 35 micrograms per cu m (mcg/m3) as "bad" and above 75mcg/m3 as "very bad".

President Moon, following an urgent briefing by Environment Minister Cho Myung-rae, called for inter-agency mitigation efforts, including the installation of high-capacity air purifiers in more daycare centres and schools.

Meanwhile, 12 cities and provinces are set to impose emergency measures for the sixth consecutive day today. The measures allow the authorities to ban old diesel cars from the streets and restrict the operation of coal power plants and other emissions facilities.

They can also recommend the temporary closure of schools or reduction of class hours and ask businesses to allow their employees to work flexible hours or from home.

Large areas of South Korea have periodically been enveloped by fine dust in recent years.

The problem has been blamed on both pollution blowing in from neighbouring China as well as local coal and diesel consumption.

Earlier yesterday, officials said the government was moving to designate fine dust concentrations as a disaster as part of its countermeasures to the worsening air pollution problem.

The density of PM2.5 is forecast to stay high today due to lack of wind. The air is likely to clear up somewhat tomorrow before worsening again over the weekend, Nier said.

KOREA HERALD/ASIA NEWS NETWORK