Graded Response Action Plan
GRAP, the Graded Response Action Plan, is the list of steps Delhi and the National Capital Region take as the air gets worse.
It has four stages tied to the Air Quality Index (AQI): Stage I when the AQI is 201 to 300 (“poor”), Stage II at 301 to 400 (“very poor”), Stage III at 401 to 450 (“severe”) and Stage IV above 450 (“severe+”). Each stage adds curbs on top of the ones before it, from dust control and limits on diesel generators at Stage I to stopping most construction and many vehicles at the higher stages.
The Commission for Air Quality Management (CAQM) decides when a stage starts and when it is lifted, usually after looking at the day’s AQI and the forecast.