Delhi, the capital city of India, is facing a severe air pollution crisis. The air quality index (AQI) has reached the ‘severe’ category, posing a serious threat to the health and well-being of the residents. To tackle this situation, the Delhi government has implemented the Graded Response Action Plan (GRAP), a series of measures that are activated when the pollution levels cross a certain threshold.
As part of the GRAP, the Delhi Transport Department has announced a ban on BS3 petrol and BS4 diesel vehicles in the National Capital Region (NCR). These vehicles are considered to be more polluting than the newer BS6 vehicles, which comply with the Bharat Stage 6 emission norms. The ban will be effective immediately and will remain in force until further notice.
Bharat Stage (BS) is a set of standards that regulate the emission of pollutants from vehicles. The higher the number, the stricter the standards. BS3 and BS4 vehicles were manufactured before April 2017 and April 2020, respectively. These vehicles emit higher levels of particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (HC) than BS6 vehicles.
According to a report by the Centre for Science and Environment (CSE), BS6 vehicles emit 89% less PM and 76% less NOx than BS4 vehicles. Similarly, BS4 vehicles emit 80% less PM and 31% less NOx than BS3 vehicles. These pollutants are responsible for causing respiratory and cardiovascular diseases, as well as cancer and premature death.
The ban on BS3 petrol and BS4 diesel vehicles will apply to light motor vehicles (LMVs) such as cars and two-wheelers. The only exceptions will be police vehicles, emergency services vehicles and enforcement vehicles. Anyone found to be violating the ban will be fined Rs 20,000, as per the provisions of Section 194 (1) of the Motor Vehicle Act, 1988.
The ban will be enforced by the Delhi Traffic Police, the Transport Department and the Environment Pollution (Prevention and Control) Authority (EPCA). The violators will be identified by checking their registration certificates, which mention the BS norms of the vehicles. The authorities will also use the e-challan system to issue fines and track the offenders.
The ban on BS3 petrol and BS4 diesel vehicles is part of the Stage III of the GRAP, which is triggered when the AQI reaches the ‘severe’ category, between 401 and 450.
The Stage III is in addition to the Stage I and Stage II of the GRAP, which are activated when the AQI is ‘poor’ (201-300) and ‘very poor’ (301-400), respectively. Stage I involves the ban on over-aged diesel and petrol vehicles, the mechanized sweeping of roads, the stoppage of garbage burning and the enforcement of dust control measures. Stage II involves the regulation of diesel generator sets, the increase in bus and metro services, the identification and rectification of pollution hotspots and the creation of public awareness campaigns.

If the AQI worsens further and crosses 450, the Stage IV of the GRAP will be implemented. This stage will involve the ban on entry of four-wheelers registered in other states, except for BS6, CNG and electric vehicles. It will also involve the implementation of the odd-even scheme, which allows only vehicles with odd or even number plates to ply on alternate days.
Delhi’s air pollution problem is a complex and multifaceted issue, which involves various factors such as stubble burning, construction activities, vehicular emissions, industrial pollutants and open waste burning. These sources contribute to the formation of a thick layer of smog, which reduces visibility and affects the respiratory system.
The situation is worsened by the specific weather conditions and geographical factors of Delhi. During winter, the wind speed drops, the temperature falls and the humidity increases, creating an inversion layer that traps the pollutants near the ground. Delhi is also surrounded by the Aravalli hills, which prevent the dispersion of the pollutants.
Delhi’s air pollution problem requires a concerted and multi-pronged approach, which involves the cooperation and coordination of various stakeholders such as the government, the industry, the civil society and the citizens. It also requires the adoption of short-term and long-term measures, which address the root causes and the effects of the pollution.
Some of the possible solutions include the promotion of clean and renewable energy sources, the improvement of public transport and non-motorized transport options, the enhancement of waste management and recycling systems, the implementation of strict emission standards and monitoring mechanisms, the development of green spaces and urban forests, and the sensitization and education of the public about the health and environmental impacts of air pollution.