• With the Air Quality Index (AQI) entering into the ‘severe plus’ category choking the national capital, the Supreme Court directed all Delhi-NCR states to immediately set up teams to strictly enforce anti-pollution GRAP-4 restrictions.

• Delhi’s AQI was recorded at 484 at 8am on November 18, the worst this season. The AQI in certain areas also breached the 500 mark.

• The Supreme Court asserted that it is the constitutional duty of all states to ensure all citizens live in a pollution-free environment.

• Implementation of stage 4 of GRAP will continue even if AQI level drops below 450.

• It also faulted the Commission for Air Quality Management (CAQM) for delaying the implementation of Graded Response Action Plan (GRAP) and said it followed a wrong approach.

What is the Air Quality Index (AQI)?

• The Air Quality Index (AQI) is a tool used by government agencies to monitor and convey air pollution levels and their potential health risks to the public. 

• Higher AQI values indicate greater pollution and more significant health concerns. The index is derived from the concentration of key air pollutants over a specific timeframe and is divided into categories, each associated with a health advisory:

• 0–50: Good

• 51–100: Satisfactory

• 101–200: Moderate

• 201–300: Poor

• 301–400: Very Poor

• 401–450: Severe

• Above 450: Severe+

What is GRAP?

• The Graded Response Action Plan (GRAP) is a structured framework created to address air pollution in the Delhi-NCR region. Designed as an emergency response mechanism, it activates when air quality deteriorates to certain thresholds.

Who implements GRAP?

• The Commission for Air Quality Management (CAQM) in NCR and adjoining areas oversees GRAP's execution, working in coordination with the Ministry of Environment, Forest and Climate Change (MoEFCC) and other local authorities.

Stages of GRAP

GRAP is segmented into four stages, each aligned with the AQI levels, with specific measures tailored to combat escalating pollution:

Stage I: Poor (AQI: 201–300)

• Enforce regulations on older diesel and petrol vehicles.

• Daily mechanical sweeping and water sprinkling of roads.

Stage II: Very Poor (AQI: 301–400)

• Control diesel generator usage.

• Target pollution hotspots for mitigation efforts.

Stage III: Severe (AQI: 401–450)

• Restrict certain vehicles in designated zones.

• Consider online classes for school children.

Stage IV: Severe+ (AQI > 450)

• Ban truck entry into Delhi.

• Halt construction activities at public project sites.

• Restrict non-essential business operations.

(The author is a trainer for Civil Services aspirants.)