The city of Beijing issued its first "red alert" for air quality on Tuesday lasting until noon, December 10th. It is the first such red alert issued by the government for a city with notoriously bad air quality. Some industrial activity will be curtailed and school cancelled. Citizens are advised to curtail outdoor activity. The pollution is less intense than last week when government officials kept the warning level at orange despite the level of particulates reaching 666 micrograms of PM 2.5 in Tiananmen Square [photo]. That is twenty-five times the World Health Organization's recommended levels. The smog is expected to peak Wednesday. Vehicular traffic is Beijing's main smog source because emissions levels are exceeded by about 10 or more of the city's traffic.