The skies over the national capital were a smoky grey on Tuesday, 29 October as the sun struggled to shine through the haze with the air quality deteriorating and slipping into the "severe" category in the city and the adjoining areas.
At 8 pm, the city's overall air quality index was 414 -- worse than Monday's AQI of 397 at 8 pm, according to the Central Pollution Control Board.
Twenty-six of the 37 air quality monitoring stations in the capital recorded AQI's in the "severe" category.
Anand Vihar was the most polluted area in the capital with an AQI of 464 and Wazirpur following with an AQI of 430.
Other areas of the city were no better.
Pollution levels in the satellite towns of Ghaziabad (465), Greater Noida (440), and Noida (450) were worse.
An AQI between 0-50 is considered “good”, 51-100 “satisfactory”, 101-200 “moderate”, 201-300 “poor”, 301-400 “very poor”, and 401-500 “severe”. Above 500 is “severe-plus emergency” category.
According to the Ministry of Earth Sciences' air quality monitor SAFAR, the levels of PM2.5 — tiny particulate matter less than 2.5 microns that can enter deep into the lungs — reached 740 in Delhi University, 12 times higher than the 0-60 considered "good".
Delhi's air quality took a hit after Diwali night due to a combination of firecracker emissions, stubble burning and unfavourable meteorological conditions.
Since then, pollution levels have been oscillating between the lower end and the higher end of the “very poor” category.
On Diwali night, a large number of revellers brazenly flouted the Supreme Court-enforced two-hour limit for bursting crackers.
The Supreme Court had also ordered that only green firecrackers, which cause 30 per cent less pollution, can be manufactured and sold, but a DPCC official said a large number of illegal crackers were burst on Diwali.
The Arvind Kejriwal government had organised a mega laser show in an effort to dissuade people from bursting crackers.
SAFAR said an increase in the wind speed will help disperse pollutants and the pollution levels are expected to come down.
However, officials at the Indian Meteorological Department said a significant increase in the wind speed is unlikely over the next two days and similar conditions are expected to prevail.
They said the visibility levels dropped from 1,200 metres to 800 metres due to the haze at the Safdarjung Observatory.
Mahesh Palawat, a senior scientist at Skymet Weather, a private forecaster said, "Slow wind speed (5 to 7 kilometres per hour) allowed the pollutants to accumulate in the region. The wind speed will increase to 10-15 kmph on Wednesday, leading a marginal improvement in air quality." "People burst firecrackers on Tuesday, the day after Diwali, too. In addition, Punjab and Haryana have recorded a spurt in stubble burning. Unfavourable meteorological conditions are making the things worse," he added.
The AQI takes into account five chief pollutants - particulate matter with a diameter less than 10 micrometres (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO).
The higher the AQI value, the greater the level of air pollution and the greater the health concern.
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