PM2.5 nearly doubles in Shanghai

The Bund is blanketed in smog yesterday as the PM2.5 density touched 140 micrograms per cubic meter, nearly double the acceptable limit, because of overcast sky and a weak air mass. (Zhou Pinglang)

Shanghai's PM2.5 density was nearly double the national limit Sunday as an overcast sky and a weak cold air mass from the north contributed to poor air quality.

The PM2.5 density peaked at about 140 micrograms per cubic meter at 6pm, nearly double the national limit of 75.

But Shanghai Meteorological Bureau forecasters said cloudy skies are expected to return today as a high pressure system moves into the city.

"The weather will get better on Monday," Wu Rui, a forecaster at the Shanghai Meteorological Bureau, said last night.

The bureau has predicted mostly pleasant conditions this week. Highs are expected to remain over 20 degrees Celsius and rise gradually to 23 degrees on Thursday.

However, a cold front bringing rain and strong winds will hit the city around the weekend.

From this month, the weather bureau will provide a new six-level forecast on how weather conditions will affect air pollution. The bureau will only include the forecast in its daily weather reports when the level reaches four or above. Level four means it will be "not easy" for weather conditions to disperse air pollutants, while level five means "hard" and level six "very hard."