There are 40 water sprinkling vehicles across the city to hydrate the roads and reduce dust, yet environmental scientists have indicated that this strategy by itself cannot lead to an improvement in air quality.
Checking other sources, including smoke-belching vehicles and polluting industries, is as important as preventing resuspension of dust. Even for dust suppression, watering roads is not the only solution, the scientists said.
On the first Sunday of the New Year, when thousands were outdoors, the air remained filthy.
The air quality bulletin, published by the Central Pollution Control Board at 4pm every day, showed that the air quality was “poor” in Calcutta and Howrah on Sunday. The bulletin states that in a city with multiple monitoring locations, the average value is used to indicate the air quality result. There are seven monitoring stations in Calcutta and five in Howrah.
A breakdown of the results revealed that at 2pm on Sunday, three monitoring stations in Calcutta, Bidhannagar, Jadavpur and Victoria reported “poor” air quality. Four stations in Howrah — Belur Math, Dasnagar, Ghusuri and Padmapukur — also reported “poor” air quality.
One station in Calcutta, Rabindra Bharati University (BT Road campus), reported “very poor” air quality.
The remaining stations reported “moderate” air quality, the best reading on Sunday, which is two levels below the best category in the National Air Quality Index.
The state PCB has 18 water sprinkling vehicles working in Calcutta, and the Kolkata Municipal Corporation has 22 more vehicles. PCB also runs 12 such vehicles in Howrah.
Kalyan Rudra, the chairperson of the state PCB, stated that water sprinkling was done to prevent the resuspension of dust as vehicles moved over roads. “The source apportionment study has shown that dust is the top contributor to the generation of PM 10 and also among the top sources of PM 2.5. We are also funding procurement of electric vehicles,” he said.
A KMC official said their water sprinklers ran along arterial roads such as JL Nehru Road, Central Avenue, and around Victoria, among other places. “They are run in two shifts, between 6am and 9am, and again between 8pm and 1am,” said a KMC official.
The air quality bulletin showed PM 2.5 was the “prominent pollutant” in both cities on Sunday.
Environmental scientists said that among the sources of PM 2.5 in Calcutta, dust was much behind the use of unclean fuel for cooking, pollution from vehicles and industries.
Medical professionals and environmental scientists have stated that it is imperative for authorities to focus on regulating sources of PM 2.5, as they pose a more significant health risk. These particulate matters, measuring 2.5 micrometers or smaller, have the capability to infiltrate the lungs and other organs.
“The focus has to be on controlling PM 2.5. The contribution of dust towards PM 2.5 is less than other sources. Waste burning, industries that use unclean fuel and tailpipe emissions have to be reduced to boost the air quality,” said Anumita Roy Chowdhury, executive director of New Delhi-based Centre for Science and Environment (CSE).
“The government should create such a public transport system that the number of cars is reduced, and people shift to using public transport. The focus should also be on shifting towards electric vehicles from diesel and petrol-powered vehicles,” she said.
Industries that are still using coal and gas to run their processes “should shift to electricity to cut down emissions,” she said.
A study by The Energy and Resources Institute (Teri), commissioned by the state pollution control board (PCB), to determine the sources of air pollution and their relative share found that cooking through coal or biomass contributed 29 per cent to generation of PM 2.5.
Industries contributed 21 per cent and tailpipe emissions from vehicles contributed 20 per cent to the formation of PM 2.5.
The contribution of dust to PM 2.5 was 12 per cent, but it was the top contributor (43 per cent) towards the generation of PM 10.