SHANGHAI reported heavy air pollution on Thursday with tiny particle PM2.5 being the major pollutant, according to Shanghai Environmental Monitoring Center.

The air quality index has been rising since morning, and surpassed 200 — the threshold for heavy pollution — by 8am. The figure touched 236 two hours later. The density of PM2.5 in Huangpu and Hongkou districts were reported to be over 200 micrograms per cubic meter, eight times the World Health Organization’s recommended standard of 25 micrograms per cubic meter in a 24-hour period.

According to the environmental center, poor diffusion condition was the main cause of pollution. “The humidity, along with slow wind, created poor diffusion condition, meaning the pollutants discharged by local sources could not be dispersed easily,” Wang Qian, chief forecaster of the center told Shanghai Daily. “The weather in spring changes often, and short time pollution is normal for this season in Shanghai.”

Wang said the air quality on Thursday afternoon will be moderately polluted. The condition will improve later on Friday.

Source: Humidity, slow wind leads to heavy air pollution in Shanghai | Shanghai Daily