New Delhi, Nov. 9 -- A day after Diwali celebrations, environmentalists have termed Delhi's deteriorating air quality a "public health emergency", warning that firecracker emissions have further aggravated an already severe pollution situation, with unfavourable meteorological conditions likely to keep pollutants trapped over the national capital for the next few days.

Residents of the national capital woke up to a thick blanket of smog, as air quality deteriorated to the 'severe' category at several monitoring stations, with the Air Quality Index (AQI) crossing 400 in multiple areas and visibility remaining poor during the early morning hours.

According to CPCB classification, an AQI between 0 and 50 is considered 'good', 51-100 'satis...