Why in News? 

CAQM invoked Stage-I of GRAP as Delhi’s AQI entered the ‘Poor’ category. 

• Framework to control air pollution in Delhi-NCR, formulated under M.C. Mehta vs Union of India (2016); implemented since 2017 by CAQM under MoEFCC. 

Stages of GRAP 

• Stage I – Poor (AQI 201–300): Road dust control, vehicle PUC checks. 
• Stage II – Very Poor (301–400): Limit diesel gensets, control hotspot emissions. 
• Stage III – Severe (401–450): Restrict vehicles, ban construction, online classes. 
• Stage IV – Severe+ (>450): Ban heavy vehicles, close schools, halt industries. 

CAQM 

• Statutory body under CAQM Act, 2021. 
• Jurisdiction: NCR + adjoining states (Punjab, Haryana, Rajasthan, UP). 
• Apex agency for air quality management, accountable to Parliament. 

Air Quality Index (AQI) 

• Launched by MoEFCC under Swachh Bharat Mission. 
• Tracks 8 pollutants (PM₁₀, PM₂.₅, NO₂, SO₂, CO, O₃, NH₃, and Pb); 6 categories (Good, Satisfactory, Moderately Polluted, Poor, Very Poor, and Severe). 
• Promotes public awareness via “One Number – One Colour – One Description.”