The situation had begun to worsen on Diwali day itself. At around 4 pm in the evening November 4, Delhi had an Air Quality Index (AQI) of 382. The CPCB’s Central Control Room recorded Particulate Matter (PM)2.5 levels in Delhi-NCR to be 309 microgram per cubic metre (µg / m³) at 11.30 pm November 4. PM10 levels were recorded to be 500 µg / m³ at 3.30 am. Here, commuters drive on National Highway 24 near Sarai Kale Khan, Delhi.