Most air quality monitoring stations in Calcutta and Howrah reported poor, very poor and even severe air quality from late on Friday till early on Saturday, about 30 hours after Diwali, according to data available on the Central Pollution Control Board (CPCB) website.
Between Thursday evening and Friday night, firecrackers were burst indiscriminately and the air bore the maximum brunt of the pollutants released when the crackers were burst.
The air quality monitoring station at Rabindra Bharati University (RBU) on BT Road reported very poor air quality for a long time between 11pm on Friday and 4pm on Saturday. The air at Jadavpur had also turned very poor for a while around Friday midnight.
At Howrah’s Ghusuri, the air remained severe for a while around midnight.
According to the CPCB, severe air quality “affects healthy people and seriously impacts those with existing diseases”, very poor air can cause “respiratory illness on prolonged exposure” and poor air causes “breathing discomfort to most people on prolonged exposure”.
At Ghusuri, the air quality index (AQI) value touched 500 — the worst AQI value in the National Air Quality Index —between Friday midnight and Saturday 2am. The AQI value is arrived at after taking into account the concentration of various pollutants like PM 2.5 and PM 10.
Any AQI value above 400 means that the air quality was severe.
Metro has been reporting about the spike in air pollution during Kali Puja and Diwali owing to the pollutants released in air by the bursting of firecrackers.
The air quality recorded in most stations in Calcutta on the night of Kali Puja was worse than last year. The air quality index in the city soared well above 400 on Diwali midnight. The air quality in the city was poor on the night before Diwali. Poor is two grades less harmful than severe.
Kausik Chaudhuri, a pulmonologist with the Beleghata ID Hospital, said he had been receiving calls from patients who were complaining about breathing problems.
“I have had to prescribe inhalers to people with colds and coughs,” said Chaudhuri.
The air around most other monitoring stations in Calcutta and Howrah were poor and very poor from late on Friday to early Saturday. The air was poor in Ballygunge, Bidhannagar and Fort William in Calcutta. It was very poor in Puddapukur and Belur Math in Howrah.
In terms of concentration of pollutants in the air, the national safe standards had been breached on both Friday and Saturday.
According to data published by the state Pollution Control Board (PCB), the concentration of PM 2.5 was 75.54 microgram per cubic metre on Friday.
The permissible standard as per the CPCB is 60 microgram per cubic metre for a 24-hour average in industrial and residential areas.