Delhi's air remains in 'severe' zone

12 out of 17 days in Nov have been severe or close to severe (AQI of 390-plus), and IMD predicts no relief till Nov 21, when wind speeds may pick up

The air quality index (AQI) in the Capital remained in the severe category, at 405, on Friday making it the 12th of the 17 days this month when people in city have had to breathe in pollution at severe or near-severe (AQI 390-plus) levels. However, the pollution levels started to ease in the evening due to favourable weather conditions.

The factors causing the crisis remained more or less the same: calm winds, low temperatures and smoke from farm fires, which combined to form a blanket of haze that appeared to thin late on Friday afternoon, when the wind direction changed and began to remove some of the effects from farm fires.

"Visibility was down to around 300 metres at Safdarjung at 7am and around 500 metres at Palam, but we saw a significant improvement during the day, when the wind direction changed. The wind direction, which had been northwesterly till 12 pm, then became easterly and by 4 pm, visibility had improved to around 3,000 metres, the highest we have seen since the spell of rain seen last week," said Kuldeep Srivastava, a scientist at IMD.