Beijing pollution soars but no red alert

Parts of China's capital Beijing suffered air pollution more than 20 times recommended levels on Tuesday, but authorities refrained from issuing the highest smog alert.

Counts of PM2.5 -- harmful microscopic particles that penetrate deep into the lungs -- reached 529, according to the US embassy, which issues independent readings.

The World Health Organization's recommended maximum exposure is 25 over a 24-hour period. China is often hit by heavy smog, mostly a result of coal burning.

China's state weather observatory issued a yellow alert -- the second highest in a four-tier warning system -- for smog in Beijing and other parts of north China, the official Xinhua news agency said.

The pollution will linger until Wednesday, it added.

Beijing issued its first red pollution alert -- reserved for when authorities forecast an air-quality index of above 300 for at least three consecutive days -- earlier this month.

The alert requires construction sites to halt work, while half the city's cars are banned from driving and schools are recommended to halt classes, among other disruptive measures.

Photo: An aerial view shows smoke billowing from chimneys of factories located near Beijing, amid heavy smog under a red alert for air pollution (Yahoo)