CHENNAI: Though widespread showers due to northeast monsoon helped disperse pollutants on Deepavali day, air quality in parts of Chennai turned ‘very poor’ on Monday, according to data released by the Tamil Nadu Pollution Control Board (TNPCB).
The TNPCB surveyed 39 air quality and 34 noise monitoring stations across the state. In Chennai, the Air Quality Index (AQI) on Deepavali day (measured from 6am on October 20 to 6am on October 21) ranged from 190 (Moderate) in Besant Nagar to 332 (Very Poor) in Valasaravakkam, according to the board’s manual monitoring data. Nungambakkam has also recorded AQI of 326, falling in the very poor category.
Other central and suburban zones such as T Nagar, Tiruvottiyur, Triplicane and Sowcarpet also saw spikes and recorded ‘poor’ AQI, breaching the national ambient standards.
The elevated levels were largely attributed to the short but intense firecracker window between 6-7 am and 7-8 pm, coupled with low wind speeds overnight.
Meteorologists, however, noted that the timely rains during the festival period prevented a severe build-up of pollutants.
“Rain-induced washout helped to limit the spike, particularly over coastal and northern parts of Chennai,” a senior IMD official said. “Without precipitation, PM2.5 levels would have easily crossed the hazardous levels,” the official said.
Industrial zones record higher AQI
Outside Chennai, AQI levels showed a mixed trend. Coimbatore, Madurai, Cuddalore, Nagapattinam and Salem recorded AQI values in the moderate to poor range (180-260), while industrial zones such as Thoothukudi saw higher readings, clocking 268 AQI, largely due to calm post-rain conditions and localised cracker use.
Noise monitoring data, collected between 6pm and midnight on Deepavali day, also showed widespread exceedances of national noise standards. In Chennai, Besant Nagar recorded the lowest noise level at 62.8 dB(A), while Tiruvottiyur topped the chart at 88.4 dB(A), well above the 55 dB(A) residential limit. In districts, the peak levels ranged from 80 to 90 dB(A) in residential and mixed zones.
