The air quality index started at 213 at 5a.m. and soared above 300 -- meaning severely polluted -- since 11a.m.

By 1p.m., the index stood at 305, while at the same time, the density of PM2.5 was 255.2, more than 10 times the level considered safe by the World Health Organization.

《Air pollution in Shanghai 10 times WHO safe level》永久閱讀地址: http://www.jiazhineng.cn/yingyu/20245/