Beijing once again choking under red alert smog

Beijing was choking under its second red alert for smog in two weeks Saturday as the polluted air enveloped the Chinese capital, forcing cars off the road.

The red alert, the most serious on a four-tier system, is in effect through Wednesday, and the smog could be worse than Dec. 7, when the first such alert was issued. The warning means authorities predict at least three consecutive days of severe smog.

During the period, vehicles will be allowed on the roads based on odd or even license plate numbers, according to Chinese media. Many schools are advised to suspend classes, with students encouraged to study at home.

Smog in Beijing, which frequently brings sickening, gray skies to the capital, often greatly exceeds the levels recommended by the World Health Organization. Levels of so-called PM2.5, the smallest and deadliest airborne particles, are forecast to surpass 500 this weekend — more than 20 times the level considered safe by the group.

The particles come from driving automobiles; burning trees, brush and yard waste; and smelting and processing of metals.

Air quality levels are measured on a scale that begins at 0, with levels under 50 considered healthy, said David Lang, chairman of the department of allergy and immunology at Cleveland Clinic, who visited China in October. Pollution levels in the U.S. rarely exceed 100, the level considered unhealthy.

Anything over 300 is considered hazardous. When smog levels exceed 300 in the U.S., the Environmental Protection Agency advises that "everyone should avoid any outdoor exertion and that people with respiratory or heart disease, the elderly, and children should remain indoors."

The heavy smog carries risks for everyone, but it can be especially harmful for people with heart disease or lung conditions such as asthma or emphysema, Lang said.

China's smog leads to 1.4 million premature deaths per year, or almost 4,000 per day, according to the Associated Press.

Contributing: Liz Szabo, Paste BN