Delhi air quality plummets to alarming levels every year in the winter. The air quality in the capital remains in the 'severe' category prompting the authorities to impose the third stage of GRAP.

GRAP stage 3 will come into force at 8am on Friday. The Delhi government announced that classes for primary schools will be shifted to online.

Every year, Delhi and northern states battle hazardous air during the winter months of October to January due to plummeting temperatures, smoke, dust, low wind speed, vehicular emissions and crop stubble burning. This time, experts say that the condition is likely to get worse in the coming days.