Spike in air pollution has become a rule rather than an exception in West Bengal, with all cities barring Kolkata witnessing deteriorating air quality in 2024 compared to 2023, a new report showed.
Kolkata recorded a marginal decrease in air pollution but is still the second most polluted metro city in the country after Delhi and among the top two per cent of the world's cities with the worst air qualities, according to the report.
The study was carried out by IQAir, a Swiss air quality monitoring technology company. It was based on particulate matter (PM) 2.5 data collected from more than 40,000 air quality monitoring stations across 8,954 locations in 138 countries, territories and regions.
PM2.5 is one of the most potent, fine air pollutants that can penetrate the deep crevices of lungs and trigger a bevy of respiratory diseases, including the fatal ones.
The state’s twin industrial cities Durgapur and Asansol, located about 170 kilometres northwest of Kolkata, ranked 24th and 25th globally in terms of air pollution, the report showed. Both recorded poorer air quality in 2024 compared to 2023, the report stated.
While Durgapur is listed under both the Union government’s flagship National Clean Air Programme (NCAP) and Smart City programmes, Asansol is an NCAP city.
Huge investment still pollution surged
Four of the seven cities studied in West Bengal — Durgapur, Asansol, Barrackpore and Howrah — recorded PM2.5 values 10 times more than the World Health Organisation guideline of 5 microgrammes per cubic metre of air, the report showed. This is despite around Rs 120 crore invested to counter air pollution in these cities.
Durgapur led with 72.3 microgrammes and Asansol remained just behind with 72.2 microgrammes. Both the cities recorded substantial jumps from their respective pollution levels of 2023: Durgapur from 49.5 to 72.3 — a 46 per cent rise — and Asansol from 62.4 to 72.2 — around 16 per cent.
Barrackpore, a city in North 24 Parganas district where the air pollution was measured for the first time under the global project, recorded 58.4 microgrammes. Howrah’s annual average of PM 2.5 was 57.1 micrograms — a 10 per cent increase over 2023. The national limit is 40 microgrammes.
The highest PM2.5 value of 128.9 microgrammes in West Bengal during 2024 was recorded in December 2024 in Durgapur.
Siliguri and Haldia, despite having annual pollution levels below 40 microgrammes each, however, recorded higher values compared to 2023.
The state pollution control board accepted that the air quality trends in these cities were concerning. “We are trying our best but while the north westerly pollution load coming from Jharkhand side is mainly responsible for poor air quality in Durgapur and Asansol, Barrackpore, I feel, gets impacted by the pollution generated by the brickfields in the adjoining areas,” said Kalyan Rudra, chairperson of the state pollution control board. The unplanned nature of industries and minimum green cover in Howrah pushes up its pollution levels, it added.
Kolkata, whose PM2.5 levels exceeded the WHO guideline by nearly nine times, spent Rs 792 crore under NCAP in the last five years, out of the total released fund of Rs 960 crore.
“We could control Kolkata’s pollution to an extent using a range of actions, particularly sprinkling of water and reducing roadside emission by providing gas connection to several roadside eateries and cloth presser units,” claimed Rudra. “However, it will be difficult to reduce the city’s pollution beyond a point, as World Bank experts have pointed out, unless pollution within the regional airshed can be countered,” added Rudra.
Kolkata has long been holding the tag of the second most polluted metro city in India, despite having few industries and less vehicles than many others in the country.
“It is a fact that climatic and meteorological factors play a key role in worsening Kolkata’s air pollution status, as the city is in the tip of the Indo- Gangetic plains and gets affected by the pollution generated in the zone, like Delhi; but the inadequate policy implementation also contributes to the problem,” explained Anumita Roychoudhury, an air pollution expert from environmental think tank Centre for Science and Environment.
“Like the rest of the country, Kolkata has also been focusing on dust control; which is important but to substantially reduce pollution level, it needs to act as well to counter pollution from transport, waste burning and likewise; a multi sectoral approach,” added the expert.
“As observed through in-depth chemical characterisation, solid waste and biomass burning are the dominant sources over Kolkata. Such emissions are enhancing ammonia in air, which in turn helps form a huge amount of particulate matter. We need to target ammonia emission that is producing ultrafine particulate matter through a secondary process,” explained Abhijit Chatterjee, a scientist associated with the central government research organisation Bose Institute.