Every year, Delhi grapples with hazardous pollution levels during the winter months, as its Air Quality Index (AQI) plummets to perilous depths. To address this pressing issue, the city has implemented the Graded Response Action Plan (GRAP), a comprehensive strategy activated when pollution levels reach specific thresholds.

Currently, Delhi is under the grip of Stage III of the GRAP, a critical measure aimed at mitigating the city's dangerous pollution levels. In this stage, the Delhi Transport Department has enforced a ban on BS3 petrol and BS4 diesel vehicles until further notice. These restrictions have been put in place as a response to the escalating pollution crisis, and they apply to the National Capital Region (NCR) region.

The decision to ban BS3 and BS4 vehicles aligns with the severity of the Air Quality Index, particularly when it falls into the 'severe' category, ranging from 401 to 450. Unfortunately, meteorological conditions and AQI forecasts offer little hope for immediate relief, necessitating the continuation of the ban until further notice.

Under this mandate, all Light Motor Vehicles (4-wheelers) within the National Capital Territory (NCT) of Delhi will be subject to this prohibition. Violators of this rule could face fines amounting to Rs 20,000, in accordance with Section 194(1) of the Motor Vehicle Act, 1988. Exceptions to this regulation will only be extended to police vehicles, those involved in emergency services, and vehicles designated for enforcement duties.

The Stage III of GRAP is an addition to the previously implemented Stage I and Stage II measures. Stage I is invoked when the AQI falls into the 'poor' category, ranging from 201 to 300, leading to the prohibition of older diesel and petrol vehicles. Stage II is activated when the AQI dips into the 'very poor' category, ranging from 301 to 400, and involves targeted actions to reduce air pollution at identified hotspots, such as regulating the operation of diesel generators during this period.

If the AQI continues to worsen, the government may be compelled to enact Stage IV of GRAP, triggered when the AQI surpasses 450 (Severe Plus). Under Stage IV, 4-wheelers registered in other states will be barred from entering Delhi, with exceptions only for BS6 vehicles, CNG vehicles, electric vehicles, and those used for transporting essential commodities.

However, banning BS3 and BS4 vehicles is just one piece of the complex puzzle that is Delhi's pollution problem. The city's poor air quality results from a combination of factors, including crop residue burning, construction activities, vehicle emissions, industrial pollutants, and open waste burning. Furthermore, specific weather conditions and geographical factors exacerbate the issue.

To genuinely address Delhi's air quality crisis, a comprehensive, multi-pronged approach is imperative. It will require meticulous planning and rigorous enforcement to yield the desired results. As it stands, achieving breathable air during Delhi's winters is a long-term goal that may take several years to realize.