According to a release from the Tamil Nadu Pollution Control Board (TNPCB), the noise level had increased by 3.9 decibels compared to last year. Triplicane recorded 86.7 decibels, the highest across Chennai.

However, there was a decline in level of air pollution on Deepavali, which the TNPCB attributed to bursting of less aerial crackers and traffic movement. The Board had installed air and noise monitoring facilities at five locations — Sowcarpet, Triplicane, Ayanavaram, T.Nagar and Nungambakkam for Deepavali. The reading on Saturday showed a drop in level of sulphur dioxide at the locations to 18 microgram/cubic metre as against 21 microgram/cubic metre last year. The level of nitrogen oxides was 29 microgram/cubic metre whereas it was 37 microgram/cubic metre last year. The levels of SO2 and NOx were within the permissible limit of 80 microgram/cubic metre. The amount of respirable suspended particulate matter in the ambient air in Nungambakkam was 164 microgram/cubic metre and 251 microgram/cubic metre in Triplicane. The permissible limit is 100 microgram/cubic metre. Similarly, the level of total suspended particulate matter in the five locations was well above the permissible limit of 200 microgram/cubic metre.

The TNPCB had conducted the 24-hour ambient noise level and Ambient Air Quality Survey in the city before and on Deepavali day.