This year's Bhogi recorded a slight increase in the pollution level as compared to that last year.
The smog due to burning of waste was marked in the early hours of Friday.
The average Respirable Suspended Particulate Matter (RSPM) level in the city, during the 24-hour period ending on 2 p.m. on Friday, was 129 microgram/cubic metre as against the 128 microgram/cubic metre recorded during the corresponding period last year. The permissible limit is 100 microgram/cubic metre.
Final figures on ambient air quality on Friday will be released on Saturday.
RSPM level was recorded the highest between 4 a.m. and 6 a.m. and the smog level rose to a considerable extent during the period, officials of the Tamil Nadu Pollution Control Board said. However, vehicular movements were not affected much during the day as the sunny sky markedly improved the visibility.
According to officials of the Meteorological Department, the below average minimum temperature augmented the mist and increased the smog concentration at the ground level.
An ambient air quality monitoring station each was set up in Anna Nagar, Vallalar Nagar, Triplicane, Besant Nagar, Mandaveli, Vyasarpadi, Kilpauk, Royapuram and T.Nagar to monitor the RSPM levels. Twenty vehicles of the city police and TNPCB made frequent checks throughout the day to prevent burning of waste.
Train services were not affected, according to Southern Railway officials.