Tamil Nadu air quality poor after Diwali: Board

The Air Quality Index (AQI) for 12 hours observed from 6am on 24 October to 6 in the morning on 25 October found that the average value in Chennai ranged between 345 to 786 and the Air quality status was very poor. However, CPCB data for Chennai issued at 4pm showed that the AQI stood at 228.