Delhi smog exceeds 60 times WHO limit

India's capital switched schools to online classes Monday until further notice as worsening toxic smog surged past 60 times the World Health Organization's recommended daily maximum.

Levels of PM2.5 pollutants -- dangerous cancer-causing microparticles that enter the bloodstream through the lungs -- peaked at 907 micrograms per cubic metre on Monday morning, according to IQAir pollution monitors, with a reading above 15 in a 24-hour period considered unhealthy by the WHO.

Individual monitoring stations noted even higher levels -- one recorded PM2.5 pollutants at 980, 65 times the WHO maximum.

Dense grey and acrid smog smothered the city, with IQAir listing conditions as "hazardous"