BEIJING (AFP) - People in Beijing were warned to stay indoors as the Chinese capital was shrouded in yellow smog with pollution reaching dangerous levels.

"Under these polluted conditions, we propose that the majority of citizens reduce their time outdoors and avoid breathing this seriously polluted air," the Beijing Environmental Protection Bureau said in a warning posted on its website.

Beijing's air quality has been at the lowest level for the past two days with the air "seriously polluted," the bureau said.

Experts said the capital was experiencing a heat inversion, where warmer air in the atmosphere was keeping the colder ground air in place, making it difficult for the pollution to disperse, the bureau said.

Meanwhile warmer spring temperatures in the city also meant that work at construction sites has increased, further kicking up dust that is mixing with the ever-increasing auto pollution.

"Under this situation, the thickness of every kind of air pollution has clearly increased, especially breathable suspended particles, which have risen rather quickly," the bureau said.

Suspended particle levels were hovering around the dangerous level of 400 and 500 micrograms per cubic meter, it said.

According to satellite photos, the inversion was lingering over northern China's Hebei and Shanxi provinces and extending southward to the Yangtze river, the paper said.

During the past decade of China's economic boom, the nation has also produced some of the worlds most polluted cities, with Beijing's air quality regularly ranking among the worst in the country and world.

http://story.news.yahoo.com/news?tmpl=story&cid=1540&ncid=1540&e=6&u=/afp/20050406/sc_afp/chinaweatherpollution_050406135745

and there hosting the next olympics? they better clean up there air before that time or they're going to have athletes keeling over.