Delhi gasped for a breath this morning as the Air Quality Index (AQI) re-entered the “severe” category in several areas, shortly after the bursting of firecrackers across the National Capital Region on Diwali wiped out the improvement in air quality due to a spell of rain.

This morning, Delhi residents woke up to a choking smog cover that reduced visibility and intensified their struggle to breathe.

The l, which had slipped to “very poor” yesterday as smoke from firecrackers joined air pollution due to stubble burning in north India, has now deteriorated further, data from the Central Pollution Control Board (CPCB) showed.

While the air quality index in ITO was pegged at 430 at 6 AM, the AQI in Jahangirpuri was recorded at 428, according to the CPCB data.

The AQI in RK Puram was 417, while in Punjabi Bagh, it was 410.

An AQI between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”.

While an AQI level of 400-500 impacts healthy people and seriously impacts those with existing diseases, an AQI level of 301-400 causes respiratory illness on prolonged exposure.