At the other air quality stations in the city, the AQI reading was in ‘poor’ category. According to Central Pollution Control Board (CPCB) data, Kolkata’s average AQI from December to January indicates a surge in air pollution levels.
Environmental scientists point out that uncontrolled burning of waste, construction dust, use of wood for cooking, vehicular exhaust fumes and meteorological conditions are among the major factors behind the surge.
There are seven ambient air quality stations in the city which monitor the air quality. According to the National Air Quality Index of CPCB, the AQI reading at 10 am Tuesday was 314 at Fort William, 306 at Ballygunge, 300 at Jadavpur, 285 at Victoria Memorial, 271 at Rabindra Sarobar, 254 at Rabindra Bharati University and 206 at Bidhannagar.
At 6 pm on Monday, the AQI reading was 321 at Fort William, 319 at Ballygunge, 317 at Jadavpur and 308 at Victoria Memorial. The AQI reading was in the ‘poor’ category at Rabindra Sarobar and Bidhannagar with PM2.5 staying at 285 and 233, respectively. Only the AQI at Rabindra Bharati University, was 179 which marks “moderate” air quality.
On November 13 at 10 am, the day after Diwali, the AQI reading was 284 at Victoria Memorial, 262 at Fort William, 234 at Ballygunge, 254 at Jadavpur, 234 at Rabindra Sarobar and 236 at Bidhannagar.
An AQI between 0 and 50 is considered ‘good’, 51 and 100 ‘satisfactory’, 101 and 200 ‘moderate’, 201 and 300 ‘poor’, 301 and 400 ‘very poor’, and 401 and 500 ‘severe’.
According to SwitchOn Foundation, a Kolkata-based environment conservation organisation, the average AQI in the city was below 200 till December 11 and over a month later had crossed 275 on January 14.
In its report, the organisation pointed out that over the week, Kolkata’s air quality has been ‘poor’ with an AQI ranging between 201 and 300, except on January 12 (195). On January 15, the peak average AQI was recorded at 271.
“Kolkata has been experiencing a rise in its AQI reading since Friday, surpassing the 250 AQI limit on both the 14th and 15th of January. Three regions in Kolkata have entered the “very poor” category, with Jadavpur registering AQI levels of 301 and 317 on January 14 and 15, Ballygunge recording 306 and 319 on the same dates, and Victoria Memorial reaching an AQI of 308 on January 15,” said the organisation in a report which analsysed the AQI data from the CPCB.
Speaking to The Indian Express, environmental scientist and activist at Cantonment Board – Government Of India, Dr Swati Chakraborty said the rampant use of wooden stoves, the burning of waste and vehicular exhaust were among the reasons for Kolkata’s worsening air quality.
“Vehicular emissions are one of the main reasons which contribute to this problem. There is also an increase of sulphur dioxide, carbon monoxide and nitrate oxide, due to the use of open chullahs (stoves) in several places especially in fairs and bus stands. Washing streets and sprinkling water routinely are key strategies to mitigate dust resuspension. However, it is not being done regularly which is another reason why local pollution is increasing,” said Chakraborty.
Environmentalist Naba Dutta said there is a “lack of effort” on the part of the West Bengal Pollution Control Board (WBPCB) to reduce air pollution. “The pollution control board is not serious about addressing the issue. Strict monitoring is required to curb the practice of burning wood, leaves and roadside refuse in the open. To address this issue, a strong waste management system is needed. Stringent monitoring of construction activities within the city is essential to control construction dust,” said Dutta.
WBPCB Chairman Kalyan Rudra, however, said the rise in Kolkata’s AQI was due to weather conditions such as overcast sky and low wind speed.
According to him, the planetary boundary layer was reduced because of the weather conditions, resulting in high concentration of air pollutants at a lower level. “This is not uncommon. The air quality worsens in such weather conditions. There was no special factor behind this rise in air pollution level,” Rudra had told The Indian Express on Monday.