Delhi schools to resume classes from November 20 after GRAP IV curbs lifted
The Centre's Graded Response Action Plan (GRAP) for Delhi-NCR categorises actions to control pollution into four stages: Stage I -- Poor (AQI 201-300), Stage II -- Very Poor (AQI 301-400), Stage III -- Severe (AQI 401-450) and Stage IV -- Severe Plus (AQI above 450).