Shanghai's concentration of tiny, harmful PM 2.5 particles reached 602.5 micrograms per cubic meter Friday afternoon, an extremely hazardous level that was the highest since the city began recording such data last December. That compares with the World Health Organization's safety guideline of 25 micrograms.
The dirty air that has gripped Shanghai and its neighboring provinces for days is attributed to coal burning, car exhaust, factory pollution and weather patterns, and is a stark reminder that pollution is a serious challenge in China. Beijing, the capital, has seen extremely heavy smog several times over the past year. In the far northeastern city of Harbin, some monitoring sites reported PM 2.5 rates up to 1,000 micrograms per cubic meter in October, when the winter heating season kicked off.