The Tamil Nadu Pollution Control Board will track noise levels across Chennai this Diwali using 60 stations spread over the city's 15 zones, according to reports. The stations are part of a noise-mapping study the board is running with IIT-Madras.

Four low-cost sensor stations were set up in each zone last year and recorded day and night noise from March to December 2025. The board has now extended the observation period by another year, bringing this year's festival within the study's scope. A board official said the high noise Chennai experiences during Diwali needs closer monitoring.

The board partnered with IIT-Madras in September 2024 to map noise in cities with over a million residents, with Chennai as the pilot. Coimbatore, Tiruchirappalli and Salem could get sensors next, after the Chennai study.

Environmentalists welcomed the extended monitoring but urged the board to publish readings from every station, so the public can see how noise varies across the city. G. Sundarrajan of Poovulagin Nanbargal also said the accuracy of the low-cost sensors needs attention.

Supreme Court rules limit festival firecracker noise to 125 decibels, and the board already runs air and noise surveys in Chennai before and on Deepavali day each year.