NEW DELHI: Beijing's air pollution made international news over the weekend when fine particulate matter (PM2.5) in the city air rose to an 'out-of-index' level of 755 mg/cu m. Pictures showed Beijing residents wearing masks amid advisories that they should stay indoors. Meanwhile, it was business as usual in Delhi on Monday when despite a clear windy day, the PM2.5 levels ranged from 130 to 565 mg/cu m.

According to World Health Organization, the safe level of PM2.5 is 20 mg/cu m. The Indian standard for this pollutant — that can cause respiratory illnesses and worsen heart ailments — is 60 mg/cu m.