Shanghai issued a smog alert yesterday, prompting authorities to activate the winter emergency measures for the fourth time yesterday.
The measures were introduced only last month. Forecasters said the air pollution would peak today in the afternoon but ease later in the day.
The Shanghai Meteorological Bureau sounded an alert for smog at 4:10pm yesterday, warning drivers of poor visibility. Those with respiratory diseases were advised to stay indoors or wear masks if they had to venture out.
Shanghai's Air Quality Index has been rising since Sunday night, and was listed as "moderately polluted" yesterday morning. But by 3pm, the index reached 208, surpassing the 200 threshold for "heavy pollution."
The index continued its upward trend with tiny PM2.5 particle being the major pollutant. The density of PM2.5 pollutants in Putuo and Yangpu districts reached 200 micrograms per cubic meter by 4pm — eight times the WHO recommended standard of 25 micrograms in a 24-hour period of time.
The Shanghai Environmental Monitoring Center said Shanghai's AQI would be between 240 and 260 — heavily polluted — from Monday evening to Tuesday morning. It would ease slightly by this afternoon, dropping between 140 and 160, or moderately polluted.
The city has struggled with pollution since the beginning of the week due to northwesterly winds and aided by a cold front. The density of the tiny polluting particles is expected to reach its peak today.
The Shanghai Environmental Protection Bureau ordered a halt on all outdoor work at construction sites within the Outer Ring Road at 9am yesterday. It also stopped construction work at night, and trucks carrying construction wastes were banned from entering the city.
The bureau said its enforcement teams would carry out checks across the city to implement the measures.
The environmental bureau said yesterday the winter emergency measures were more effective for implementation rather than the four-color air pollution warning system.
"The winter emergency measures were activated several times and have been very effective," said Zhou Jun, deputy director of the bureau's pollution control division.
Zhou said if proved successful, the bureau would consider implementing it for entire year.