Explained: What GRAP Stage 4 means on the road as Delhi air quality slips into ‘severe’ zone

Under GRAP Stage 4, private vehicle movement is not completely prohibited, but restrictions vary based on fuel type and emission norms.

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New Delhi: Delhi has once again entered the ‘Severe’ air pollution category, prompting the Commission for Air Quality Management (CAQM) to implement Stage 4 measures under the Graded Response Action Plan (GRAP) across the National Capital Region.The curbs were triggered after the city’s Air Quality Index (AQI) crossed 400, prompting the strictest set of restrictions to limit vehicular emissions and industrial activity, according to a report by The Times of India.Under GRAP Stage 4, private vehicle movement is not completely prohibited, but restrictions vary based on fuel type and emission norms. Petrol vehicles compliant with BS-VI norms are allowed to operate, while BS-III petrol and BS-IV diesel vehicles are barred from plying in Delhi-NCR, except when deployed for essential services.Prohibited vehicles

Vehicles using cleaner fuels remain exempt from the ban. Electric vehicles, CNG-powered vehicles, and BS-VI-compliant models can continue to operate without additional restrictions. Public transport, taxis and app-based cab services are also permitted, provided they meet emission standards.Truck movement has been significantly tightened. BS-IV diesel trucks are not allowed to enter Delhi unless they are carrying essential goods or are engaged in essential services. CNG, LNG, electric and BS-VI diesel trucks are permitted. Delhi-registered heavy goods vehicles that are BS-IV diesel or older are also prohibited from plying unless specifically exempted.Authorities have stepped up enforcement to ensure compliance. Violations under GRAP Stage 4 can attract fines of up to ₹20,000 under the Motor Vehicles Act, and non-compliant vehicles may be impounded. Vehicles without a valid Pollution Under Control (PUC) certificate face penalties of up to ₹10,000.The Delhi Police and Transport Department have intensified on-ground checks, supported by digital monitoring systems, as the city grapples with worsening air quality and mounting health concerns.