Smog forecast to stay until Tuesday

The cloud of pollution that descended on Shanghai over the weekend will continue to loom until Tuesday, when a cold front is expected to sweep through the city, local environmental protection and weather authorities said Sunday.

Idle winds are expected to ensure the smog will remain in the city until Tuesday afternoon, according to the Shanghai Environmental Monitoring Center, which is affiliated with the Shanghai Environmental Protection Bureau.

Shanghai's Air Pollution Index (API) rose to 124 on Sunday from readings in the 60s on Friday. A reading of 124 denotes light air pollution.

"A high pressure system moving in from the north has brought a lot of pollutants into the Yangtze River Delta, causing pollution levels in many cities to exceed normal," said Li Juan, an engineer from the monitoring center.

These pollutants, some of which come from burning agricultural waste in rural areas, others from factory and vehicle emissions, undergo a chemical reaction in the air that generates sulfates and nitrates, which may jeopardize people's health, Li said.

Meanwhile, PM 2.5 levels spiked to about 280 micrograms per cubic meter at 9 am Sunday, up from below 80 on Saturday afternoon. PM 2.5, which stands for particulate matter smaller than 2.5 micrometers, is a closely watched type of air pollution because the small size of the particles allows them to penetrate deeply into the lungs, where they can contribute to asthma and cardiovascular disease.

As of 5 pm, Shanghai's average PM 2.5 reading over previous 24 hours hit 233 micrograms per cubic meter. The Ministry of Environmental Protection designated that a reading of 75 micrograms per cubic meter is considered "standard."

The Shanghai Environmental Monitoring Center issued a warning Sunday morning that advised residents with heart and respiratory diseases to stay indoors.

The local highway authority temporarily closed several toll gates on the S32, G15 and G60 highways in the suburbs from early Sunday morning until 9 am because the low visibility might cause traffic accidents.

Lower temperatures will accompany the cold front expected to arrive Tuesday. The low temperature will fall to 10 C in downtown Wednesday morning with intermittent showers, said Kong Chunyan, chief service officer of Shanghai Meteorological Bureau.