New Delhi: Air quality in the national capital oscillated between "severe" and "very poor" levels with pollutants rising exponentially and noise pollution peaking owing to incessant fireworks and bursting of crackers on Diwali night.
The intensity of air pollution on Diwali night was "less" compared to last year, presumably due to wind movement, as per Centre for Science and Environment (CSE). The Delhi government attributed the reduction to its anti-firecracker campaign.
System of Air Quality and Weather Forecasting and Research (SAFAR), which observed air quality of the "Diwali period" of last three days, said the city was "more polluted" than last year. It said the overall levels of PM 2.5 and PM 10 were 258 and 386 micrograms per cubic metre last night.
It identified Palam, Delhi University, Pitampura and Noida as the leading pollution spots in the city with corresponding PM 2.5 readings at 344, 275, 281 and 302 respectively.
SAFAR, a Ministry of Earth Sciences entity, said air quality in number of areas was "severe" which means the level of PM 2.5 and PM 10 were above 253, 421 micro gram per cubic metre. "Severe" is used to describe the highest level of pollution.
The "very poor" category is declared when PM 10 and PM 2.5 levels are between 351 and 420 and 211 to 252 micro gram per cubic metre.
As per the Delhi government, whose analysis was based on 'Ambient Air Quality' (outdoor air quality over long-term) data of six stations, maximum average values of sulphur dioxide, nitrogen dioxide and PM 2.5 were lower at these locations on this Diwali compared to their corresponding values on the occasion of Diwali in 2014.
The Delhi Pollution Control Committee (DPCC) stations are located at R K Puram, Mandir Marg, Punjabi Bagh, Civil Lines, Anand Vihar and IGI airport.
Delhi government attributed the reduction to people's positive response to its anti-firecrackers campaign, involving Chief Minister Arvind Kejriwal among others. CSE said it was due to comparatively less crackers and mild wind in some parts.
"The recorded wind speed during 2015 Diwali was 1.19 metre per second in contrast to 0.62 m/s in 2014 the wind speed in this Diwali had almost doubled," a CSE statement said.
But the NGO claimed that its exposure monitoring, essentially the level of pollution within breathing zone at the time crackers were burst, threw up figures showing "alarming levels of exposure".