LUCKNOW, Nov. 6 -- After two weeks of recording air quality in the 'satisfactory' and 'moderate' categories, Lucknow's air quality turned unhealthier than the post-Diwali levels. The city's air quality index (AQI) stood at 254 on Wednesday. On October 21, a day after Diwali, the AQI was 250.

Surprisingly, Lucknow's reading was higher than Delhi's and several NCR cities' levels on the day. As per the 4pm bulletin issued by the Central Pollution Control Board (CPCB), Delhi recorded an AQI of 202, while Ghaziabad's stood at 207, Gurugram's at 225, and Noida's at 215 - all within the 'poor' range.

According to the experts, the brief period of 'good' air post-monsoon was due to some rainfall activity after Diwali. All six AQI measuring stati...