Delhi sees 'severe' air day after Diwali as cracker ban defied
New Delhi: Delhi's air quality went down to the "severe" category the day after Diwali as the Capital with impunity defied the firecracker ban imposed by the National Green Tribunal and again directed by the Delhi government. People celebrated the festival of lights from Friday onwards with firecrackers, which continued on Saturday and Sunday in several parts of the city.
Stubble burning put together with the pollution from firecrackers left the 24-hour average AQI at 435 at 4 pm, which was the worst on the day after Diwali in the last four years.
However, higher wind speed - up to 25 kilometers per hour - and light rainfall under the influence of a fresh Western Disturbance brought some relief.
The air quality had turned "severe" on Saturday evening with stubble burning accounting for 32 per cent of Delhi's PM2.5 pollution, but firecrackers emissions and calm winds made the situation even worse.
The levels of PM2.5, which is about three per cent the diameter of a human hair and can lead to premature deaths from heart and lung diseases, were 396 microgram per cubic meter ( g/m3) in Delhi-NCR at 6 am, above the emergency threshold of 300 g/m3. PM2.5 levels stood at 329 g/m3 at 7 pm. The safe limit is 60 g/m3.
PM10 level stood at 543 g/m3 at 6 am, above the emergency threshold of 500 g/m3, before it started decreasing. It was 441 g/m3 at 7 pm, according to Central Pollution Control Board (CPCB) data. PM10 levels below 100 g/m3 are considered safe in India.
According to the Graded Response Action Plan (GRAP), the air quality is considered in the "severe plus" or "emergency" category if PM2.5 and PM10 levels persist above 300 g/m3 and 500 g/m3 for more than 48 hours.
A large number of people burst crackers across the national capital and its suburbs on Saturday night, flouting the ban imposed by the National Green Tribunal.
The Ministry of Earth Sciences' air quality monitor, SAFAR, said the magnitude of PM2.5 suggests significant local additional emissions (probably firecracker related) on Saturday night combined with farm fire-related pollutant concentrations led to "such a scenario where hourly average concentrations touched more than 1000ug/m3 at midnight yesterday".
According to the India Meteorological Department, Delhi-NCR witnessed light rain on Sunday and higher wind speed under the influence of a fresh Western Disturbance which aided in the dispersion of pollutants.
Stubble fires have reduced to around 350 on Sunday compared to around 2,586 a day before. The share of farm fires in Delhi's PM2.5 was around 4 per cent on Sunday. The Air Quality Early Warning System for Delhi also said the situation is likely to improve significantly on Monday.
