Delhi Air Pollution Centre Action: BS-III petrol and BS-IV diesel four-wheelers will be immediately banned in Delhi and Gurugram, Faridabad, Ghaziabad and Gautam Buddh Nagar if the AQI crosses the 400-mark. The CAQM, a statutory body formed under an Act in 2021, amended the GRAP in 2022 to ensure proactive implementation of anti-air pollution steps based on forecasts up to three days in advance.