Bengaluru, Mumbai, Patna Lead Diesel Gen-Set Pollution Crisis in India
Study flags Bengaluru, Mumbai, Patna as top PM2.5 emitters from diesel generators.
A comprehensive study by the Center for Study of Science, Technology and Policy (CSTEP), released at the India Clean Air Summit 2025 on August 20, 2025, identifies Bengaluru Urban, Mumbai City, and Patna as the top contributors to PM2.5 emissions from diesel generator (DG) sets in India.
Titled Switch on, Smoke off: Reducing Emissions from Diesel Generator Sets, the report highlights that 14.7 lakh DG sets in 2022 emitted 42 gigagrams (Gg) of PM2.5, 23 Gg of black carbon, and 877 Gg of nitrogen oxides (NOx), with high concentrations in districts across Rajasthan, Uttar Pradesh, West Bengal, and Maharashtra, including Gautam Buddha Nagar and North 24 Parganas.
The study underscores the severe health risks posed by PM2.5, a fine particulate matter linked to respiratory and cardiovascular diseases, exacerbated by older or poorly maintained DG sets that often exceed Central Pollution Control Board (CPCB) emission standards.
With the DG set market projected to grow at an 8.8% compound annual growth rate by 2030, the report warns of escalating pollution unless mitigated. Urban areas with frequent power outages are particularly affected, as these “super-emitter” units release excessive pollutants, worsening air quality in cities like Ajmer, Alwar, Jodhpur, Bhopal, and Thane.
To address this crisis, the study proposes urgent measures: transitioning to solar photovoltaic systems with storage, adopting CPCB IV+ compliant DG sets, and shifting to natural gas-based generators, which could cut PM2.5 emissions by over 95%. However, challenges like high costs and limited gas pipeline networks hinder adoption.
The report advocates for a national scrappage policy to phase out outdated units, mandatory emission testing, and financial incentives for cleaner technologies, such as subsidies for rooftop solar and CPCB IV+ models, to ensure sustainable urban air quality improvements.
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