Pollution Challenges of Kolkata and West Bengal: Between Crisis and Resilience
Kolkata, the cultural heart of India, is also a city locked in an environmental struggle. From the choking air of its winter months to the poisoned groundwater of its villages, and from overburdened landfills to the fragile mangroves of the Sundarbans, the challenges of pollution in Kolkata and West Bengal are deeply complex. Yet recent data reveals a mixed picture—one of both alarming risks and cautious progress.
Air Pollution: Gains That May Not Last
For decades, Kolkata has been branded one of India’s most polluted metros. Diesel taxis, outdated buses, and industrial clusters in Asansol, Durgapur, and Haldia have long pumped particulates into the air. But recent figures suggest a measure of improvement.
In winter 2024–25, the city recorded its lowest PM2.5 levels since 2019—73 µg/m³ in December and 77 µg/m³ in January—down from well over 130 µg/m³ just a few years ago (Times of India). Even more remarkably, July 2025 was one of the cleanest months on record, with over 80% of days classified as “Good” air quality, thanks largely to relentless monsoon showers washing the pollutants away (Times of India).
Long-term analysis shows Kolkata experienced 368 “Very Good” air days and 423 “Satisfactory” days between 2021 and 2025. Unlike Delhi, the city has not had a single “Severe” air day in the past four years. Under the National Clean Air Programme (NCAP), particulate matter (PM10) levels have also dropped by 37% compared to 2017–18.
Still, experts warn against complacency. Nearly a third of Kolkata’s particulate matter comes from secondary pollutantslike ammonium sulfate—formed through chemical reactions in the atmosphere—that current clean-air strategies often overlook (Times of India). And once the monsoon ends, road dust and waste burning are expected to resurface as critical triggers.
Water Pollution: A Crisis Beneath the Surface
While the city’s air shows tentative improvement, its water systems remain in deep peril.
The Hooghly River, a crucial artery for Kolkata, is heavily polluted by untreated sewage, jute mills, paper plants, and tanneries. But the graver danger lies underground. West Bengal sits on one of the largest arsenic-contaminated aquifers in the world.
Over 6 million people across 2,700 villages in nine districts are exposed to unsafe arsenic levels (The Diplomat). A 20-year scientific study found that 26 million residents of West Bengal are potentially at risk from arsenic concentrations above 10 µg/L—the WHO guideline—with about 4.2 million exposed to levels above 50 µg/L (ResearchGate).
The most severely affected districts—Nadia, Murshidabad, and North and South 24 Parganas—are now global case studies of groundwater poisoning. Arsenicosis, a condition caused by long-term exposure, continues to disfigure, disable, and kill quietly across rural Bengal.
The East Kolkata Wetlands: Nature’s Unsung Hero
Ironically, Kolkata’s salvation lies in its wetlands. Spread across 127 km², the East Kolkata Wetlands process around 1,000 million litres of wastewater daily, effectively recycling sewage into fishery ponds and agricultural fields. This natural system saves the city nearly ₹468 crores annually in treatment costs and provides livelihoods to more than 50,000 people. The wetlands also supply around a third of the city’s fish (Scroll).
Yet, they remain under siege. Between 1972 and 2011, 38.6 km² of wetlands were lost to urban encroachment, threatening not only biodiversity but also Kolkata’s most efficient climate buffer and carbon sink.
Soil, Waste, and Noise: The Everyday Burdens
The problems extend to the land beneath people’s feet. In Burdwan, excessive pesticide use degrades soil health, while Asansol’s mining belt struggles with coal ash and heavy-metal contamination. In Kolkata, the Dhapa landfill—a mountain of waste—continues to leak toxins into soil and groundwater.
Noise, too, is more than a nuisance. Kolkata is consistently ranked among India’s loudest cities, with constant honking, construction, and high-decibel festivals often pushing beyond legal limits. For citizens, the result is a cocktail of stress, hearing damage, and disrupted sleep.
Climate Pressures: The Sundarbans in Peril
No discussion of Bengal’s ecology is complete without the Sundarbans. The world’s largest mangrove forest and home to the Royal Bengal Tiger is being battered by rising seas, cyclones like Amphan and Remal, and salinity intrusion. For the millions who live here, climate change is not a debate but a lived crisis—bringing loss of farmland, migration, and livelihood collapse.
The Way Forward
The picture is daunting, but not hopeless. Kolkata and West Bengal have already shown that policy, science, and community action can yield results. Cleaner winters and falling PM levels point to the impact of the NCAP, stricter industrial controls, and vehicle retirement schemes.
The next step is expanding focus:
Address secondary pollutants in air.
Accelerate safe water access in arsenic-affected districts.
Protect the East Kolkata Wetlands as a living infrastructure.
Invest in modern waste segregation, recycling, and landfill alternatives.
Integrate climate-resilient planning into both Kolkata’s urban growth and Sundarbans’ fragile ecosystem.
Conclusion
The story of Kolkata and West Bengal is one of contrasts—progressive improvements in the skies above, catastrophic risks in the waters below, and fragile ecosystems holding the balance. The region stands at a critical crossroads. Whether it slides deeper into ecological collapse or emerges as a leader in sustainable urban and rural resilience depends on the choices made today.
