CHENNAI: Chennai largely avoided the worst of festival-linked smog this Bhogi. The Air Quality Index (AQI) was ‘moderate’ in 11 out of 15 zones in Chennai Corporation limits. Only four zones slipped into the ‘poor’ category as particulate matter (PM) levels surged sharply, according to the official data shared by the Tamil Nadu Pollution Control Board (TNPCB).
The TNPCB conducted 24-hour manually operated ambient air quality surveys in all Greater Chennai Corporation zones during the pre-Bhogi period (8 am January 10 to 8 am January 11) and on Bhogi day (8 am January 13 to 8 am January 14), monitoring PM10, PM2.5, SO2, NO2, etc., along with meteorological data.
TNPCB data show that during the pre-Bhogi period, AQI remained ‘satisfactory’ across all 15 zones, with values ranging from 52 (Alandur) to 89 (Perungudi). On Bhogi day, the AQI rose substantially in every zone, ranging from 140 (Thiruvotriyur) to 273 (Perungudi). While 11 zones were classified ‘moderate’, four zones – Tondiarpet (267), Royapuram (243), Valasaravakkam (207), and Perungudi (273) – slipped into the ‘poor’ category.
AQI in the range of 201 to 300 is considered ‘poor’ category.
This “controlled increase”, TNPCB said, was seen despite public awareness measures. However, the data indicate that the deterioration was not minor. The particulate pollution spike across the city meant no area was safe for the vulnerable population. PM10 rose from a pre-Bhogi range of 52-89 µg/m3 to 120-257 µg/m3 on Bhogi day. The highest PM10 was recorded in Tondiarpet (257 µg/m3) and Royapuram (247 µg/m3), both dense neighbourhoods with heavy traffic and localised waste burning vulnerability. PM2.5 increased from a pre-Bhogi range of 20-37 µg/m3 to 72-112 µg/m3 on Bhogi day. The highest PM2.5 was recorded at Perungudi (112 µg/m3) followed by Tondiarpet (110 µg/m3) and Royapuram (103 µg/m3).
The national standard for PM10 is 100 µg/m3 and 60 µg/m3 for PM2.5, which several zones breached on Bhogi day, reinforcing health concerns particularly for children, elderly and people with respiratory illness.
Meanwhile, other gaseous pollutants like SO2 and NO2 remained relatively low compared to particulate spikes. TNPCB said it conducted night patrolling from 9 pm on January 13 to 6 am on January 14 with the Greater Chennai Corporation and police to prevent burning of plastic waste, tyres and tubes, alongside radio and social media campaigns and outreach through NGOs and resident welfare associations.
Officials said there were slight disturbances in flight operations at Chennai International Airport during early morning hours on Wednesday due to poor visibility.