Pollution levels in TN exceed national standards; Chennai’s AQI readings worst

CHENNAI: The Tamil Nadu Pollution Control Board (TNPCB) has reported that air and noise pollution levels across the State exceeded national standards during this year’s Deepavali, with Chennai’s air quality readings falling to ‘poor’ to ‘very poor’ levels.

According to the official survey report, the highest Air Quality Index (AQI) in the city was recorded at Valasaravakkam – 332 (very poor), while Besant Nagar posted the lowest at 190 (moderate). Other locations including Perungudi (297), Kodungaiyur (312) and Velachery (275) also remained in the ‘poor’ to ‘very poor’ categories.

According to the National Air Monitoring Programme’s AQI scale, air quality is categorised as follows: 0 to 50 is ‘good,’ 51 to 100 is ‘satisfactory,’ 101 to 200 is ‘moderate,’ 201 to 300 is ‘poor,’ 301 to 400 is ‘very poor,’ and 401 to 450 is ‘severe.’

In the ‘poor’ category, most people may experience breathing discomfort with prolonged exposure. The ‘moderate’ air quality can cause breathing issues for individuals with lung diseases, asthma, and heart conditions, according to health guidelines for AQI categories.

Across TN, the 24-hour survey conducted from 6 am on October 20 to 6 am on October 21 covered 39 air quality and 34 noise monitoring stations in major districts including Coimbatore, Madurai, Tirunelveli, Salem, Tirupur, Cuddalore, Thanjavur, Kanniyakumari, Chengalpattu, and Vellore.

The highest AQI was observed in Tirupur (336), followed closely by Valasaravakkam (332) and Thoothukudi (321). Relatively moderate levels were seen in Kanniyakumari (146) and Dindigul (178).

The TNPCB noted that air and noise levels exceeded national standards despite the State government’s restriction allowing fireworks only between 6-7 am and 7-8 pm on Deepavali day.

Chennai on the Deepavali day experienced thick smog with motorists struggling to manoeuver where visibility fell below 50 metres. The smog persisted well into the morning with even underground Metro stations and trains were shrouded in haze.

According to real-time CPCB monitors, the AQI in Velachery touched 401 late Monday, while Perungudi and Chengalpattu also breached the 330 mark, among the worst in the past three years. In comparison, last year’s Deepavali AQI in Chennai was 287 at Valasaravakkam and 365 in 2023, indicating that this year’s spike marks one of the worst in recent years.

The TNPCB said both air quality and noise readings exceeded permissible limits under the National Ambient Air Quality Standards (NAAQS). Noise monitoring between 6 pm and midnight showed Tiruvottiyur as the loudest location at 88.4 dB (A), while Besant Nagar remained lowest at 62.8 dB (A) – both were above safe thresholds.

State-wide, noise levels surged in almost every urban district. Madurai (85.1 dB), Tirupur (86.8 dB), Thanjavur (84.2 dB) and Coimbatore (82.6 dB) all crossed the daytime residential limit of 55 dB and night limit of 45 dB.