Beijing is set to be hit by a dust storm today just 24 hours after being enveloped by smog, marking its second encounter with a combination of two different types of air pollution in less than two weeks.
Residents of the capital, who had been expecting smog to ease considerably with the spring fall in humidity levels, instead woke up to hazardous smog yesterday morning, with the US embassy air quality readings showing the level of PM2.5, respirable suspended particles, exceeding 300 micrograms per cubic metre.
The worst pollution occurred around noon with the index, published hourly on the embassy's Twitter feed, showing 410ppm at 2pm. More than 80 per cent of the Beijing municipal government's monitoring stations reported very unhealthy air quality indices of over 300.
Some residents who had removed their face masks in the afternoon to make breathing easier as a wind began to blow, very soon received a warning from the municipal weather authorities that dust and sand would arrive today with winds strong enough to blow off billboards.
Most of the dust and sand will have originated from the Gobi Desert in Inner Mongolia.
Visibility in some areas of the autonomous regions had begun to drop to below one kilometre by the time the warning was issued.
The Beijing government said yesterday's smog was caused by a low pressure weather system trapping air pollutants in the city. Today's dust storm is expected to disperse fine particles, but air quality could remain low due to an increase in larger particles, or PM10, the authorities said.
A similar situation occurred last Wednesday, pushing PM10 over 1,000ppm.
Bad air quality has prompted heated discussions among NPC members and CPPCC delegates, with calls for more legislation.