PM2.5 blamed for worst of pollution

The average PM2.5 density in Shanghai last year was 55 micrograms per cubic meter, or almost 60 percent above the national standard, an industry expert said yesterday.

PM2.5 and ozone are the most serious pollutants in the city, Fu Qingyan, chief engineer at the Shanghai Environmental Monitoring Center, said during her lecture at the Shanghai Science and Technology Museum.

More than 70 percent of the polluted days recorded last year were due to PM2.5, the fine particles of less than 2.5 micrometers in diameter that pose a major risk to people's respiratory health, Fu said, adding that ozone accounted for about 26 percent of the total.

"Since 2006, Shanghai's annual PM2.5 density has fallen only very slightly. It is at its highest in winter and lowest in summer," she said.