CHENNAI: Among the four cities – Chennai, Tiruchy, Madurai and Thoothukudi – in Tamil Nadu that are covered under the National Clean Air Programme (NCAP), the capital city recorded a modest PM10 reduction, while Thoothukudi recorded the sharpest reduction in the seven year period between 2017-18 and 2024-25
According to the data presented by Ministry of Environment, Forest and Climate Change in the Lok Sabha, the average concentration of PM10 levels in Chennai dropped by 12.1 % from 66 µg/m3 in 2017-18 to 58 µg/m3 in 2024-25.
Thoothukudi, meanwhile, recorded a 54.5% reduction with the PM10 levels dropping from 123 µg/m3 in 2017-2018 to 56 µg/m in 2024-2025. The average concentration of PM10 levels in Madurai and Tiruchy dropped from 88 and 72 in 2017-18 to 57 and 61 in 2024-25 respectively.
Meanwhile, Chennai fared poorly in terms of drop in PM10 levels compared to other metropolitan cities like Mumbai (44%), Kolkata (37%), and even Delhi (15.8%). However, in terms of the actual average concentration of PM10 levels recorded, Chennai with 58 µg/m3, fared far better than Mumbai (90), Kolkata (92), and Delhi (203).
Although Chennai is now closer to the National Ambient Air Quality Standards (NAAQS) of 60 µg/m3, experts say the progress is incremental and insufficient given the scale of urbanisation, traffic, and construction activity.
“The figures may look acceptable on paper, but the health impact remains tangible. We continue to see rising respiratory cases in urban centres like Chennai,” a senior pulmonologist at the Rajiv Gandhi Government General Hospital told TNIE.
“From switching to electric buses to addressing unpaved roads, enforcing construction norms and emission compliance from industries, the city has to push harder,” said Dr S Vishvaja, doctor-turned-activist.
Under NCAP, the city developed a Clean Air Action Plan targeting key sources such as vehicular emissions, road and soil dust, construction activity, and industrial pollutants. The local body has also been directed to implement dust mitigation measures and enforce rules against open waste burning. Yet, enforcement has been patchy.
Kirti Vardhan Singh, Minister of State in the Union Environment Ministry, said nationally, 103 out of 130 cities covered under NCAP have recorded a decline in PM10 levels. However, many cities still exceed safe limits. The reply said that there are no conclusive data linking air pollution directly to mortality and multiple factors - such as socio-economic status, occupational exposure, and immunity -complicate the attribution of health impacts.