Seoul was affected by higher levels of harmful fine particles in the air than other metropolitan cities around the world last year, according to the Ministry of Environment.

The ministry said the average concentration of PM2.5 in the air, solid or liquid particles less than 2.5 micrometers in diameter ― one-thirtieth the width of a human hair ― was 25.2 micrograms per cubic meter last year. That level is almost twice that of New York City, which averaged 13.9.

The concentration levels in Paris, London, and Los Angeles were 17.9, 16, and 15, respectively.

Even though the 2012 figure for Seoul was lower than 28.8 in 2010 and 29.3 in 2011, it fell short of the World Health Organization’s yearly standard of 10 and the 25 threshold which Seoul plans to adopt in 2015.

Once particle pollution is inhaled, toxins can get into the lungs and the bloodstream to cause respiratory diseases, heart attacks and other diseases. Fine particles can infiltrate more deeply into the lungs and stay there longer than coarse particles such as PM10 (particulate matter smaller than 10 micrometers in diameter).

More than 30 days among 333 days measured in Seoul City last year surpassed the daily threshold of 50 micrograms per cubic meter.

An increase of 19.4 micrograms per cubic meter in the average level of PM2.5 causes an 18 percent increase in early mortality.

More than half of the 11 monitoring centers across Korea, including those in Incheon and Gyeonggi, had fine pollutant levels above 25 micrograms per cubic meter.

The highest level of fine particles was 107.7 in 2012, a decrease from 152.2 in 2011.

The monthly level of PM2.5 in Seoul City in January was 38, higher than 35 from a year earlier.

Research by national environment agencies from Korea, Japan and China showed that more than 30 percent of sulfur oxides and nitrogen oxides (NOx), the main toxins carried by the fine particles, came from China.

The ministry says, however, the pollutants from China and those emitted from factories and vehicles in Korea are both attributable to the high level of PM2.5.

“When the air is murky due to a high level of fine particles, people are advised to put on a mask or safety glasses, and shun outdoor activities,” said Hwang Seok-tae, a director of the ministry’s climate and air quality management division.

As more people are worried about the impact of fine particles on health, the ministry will complete a master plan to tackle issues caused by PM2.5 and start it this year.

The ministry pledges to reduce the levels of nitrogen oxides and sulfur oxides by more than 20 percent.

To that end the ministry will promote the use of a low-NOx burner and cars run by alternative energy.

A low-NOx burner used in a boiler to produce steam and electricity emits less pollutant than ones widely used.

The master plan will also include disclosing the information of the level of PM2.5 to the public and increasing monitoring facilities.

The ministry will seek more collaboration among neighboring nations in solving the environmental issues.

At a meeting among environment ministers from Korea, Japan and China next month, Korean Environment Minister Yoon Seong-kyu will suggest to his Chinese counterpart a joint research project on pollution issues, the ministry said.

By Kim Young-won  (wone0102@heraldcorp.com)