NE China remains shrouded in smog

Days of heavy smog have made face masks coveted merchandise in Harbin, capital of Heilongjiang province. The notice on the window of this pharmacy in Harbin reads, "All face masks sold out." Hao Bing / For China Daily

Heavy smog and haze continued to envelop Northeast China for a third straight day on Tuesday.

By 4 pm, almost all monitoring stations in Heilongjiang, Jilin and Liaoning provinces reported readings above 200 for PM2.5 — airborne particles measuring less than 2.5 microns in diameter — indicating severe pollution, according to the China National Environmental Monitoring Center. The PM2.5 level deemed safe by the World Health Organization is about 25.

The air pollution level in Jilin city reached the top level of 500 in the afternoon.

Changchun, the capital city of Jilin province, was covered in thick fog with a visibility of less than 50 meters, forcing Changchun Longjia International Airport to cancel all flights, and most expressways were closed, the city's meteorological bureau said.

Smog and haze shrouded seven major cities in Liaoning province on Tuesday afternoon. Some local governments upgraded the official warnings for the smog twice within a day, from yellow to orange, then to red, with visibility in some areas being reduced to less than 50 meters.

In Heilongjiang, all expressways and the local Harbin Taiping International Airport remained closed on Tuesday. Visibility was less than 20 meters in some areas.

Air pollution levels in Harbin, capital city of Heilongjiang and the host of a popular annual ice festival, improved a little from Monday.

Classes in Harbin's senior high schools resumed, but kindergartens and primary and junior high schools remained closed.

Environmental experts pointed to three major causes of the pollution — coal-burning for the heating season; farmers' burning crop stalks after the autumn harvest; and unfavorable weather.

"Special meteorological conditions of fog caused by a sudden temperature change between day and night, which is typical for this season, play a vital part in this time's pollution," said Wang Yuesi, a researcher from the Institute of Atmospheric Physics under the Chinese Academy of Sciences.

Wang said the fog combined with large coal consumption and the burning of crop stalks lead to the smog.

Chai Fahe, deputy head of the Chinese Research Academy of Environmental Sciences, said local governments in the area that includes Hebei province and the municipalities of Beijing and Tianjin should be well prepared for possible smog and haze as the heating season in this area draws near.

Also on Tuesday, the Environmental Protection Ministry released air quality data from 74 cities from July to September, which shows air quality slightly improved compared with the previous quarter.

The number of days reaching national air-quality standard grew from 57 to 64, it said.

The Beijing-Tianjin-Hebei cluster remained the most polluted area, as it has always been, accounting for eight places in a list of the top 10 worst polluted cities nationwide.