Air pollution level spikes as cloud descends on city

Shanghai's PM 2.5 density readings jumped early Monday before improving later in the day, according to the Shanghai Environmental Monitoring Center.

PM 2.5 levels spiked due to the fog that descended on the city Monday morning, said Duan Yusen, an engineer from the monitoring center. Wet and stagnant air can more easily absorb pollutants from coal burning plants and vehicle emissions.

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.

Shanghai's PM 2.5 levels started climbing at 8 am and peaked around 3 pm. Density levels at half of the city's 10 monitoring sites hit 300 micrograms per cubic meter. It was the highest at the station in Jing'an district, which rose to 313.4 micrograms per cubic meter.

The local government advised on its official microblog Monday afternoon that people with heart or respiratory conditions avoid outdoor activity.

The citywide PM 2.5 level plunged after 4 pm when the wind picked up and changed direction, according to the monitoring center. By 8 pm, it had fallen to 62 micrograms per cubic meter.

The local government classifies an average daily reading below 75 as "good." The average 24-hour reading as of 8 pm Monday was 88.1 micrograms per cubic meter.

The monitoring center predicted Monday that a blast of cold air would help the air quality improve Tuesday.

The local meteorological bureau forecast partly cloudy skies Wednesday with a high temperature of 22 C and a low of 15 C. The temperature will rise by 2 C to 3 C from Thursday to Saturday, with light rain in some parts of the city, said Zhang Ruiyi, a senior official from the Shanghai Meteorological Bureau.