India’s capital, Delhi, has been suffering from poor air quality during certain periods every year. On 15 December 2025, the Air Quality Index (AQI) was recorded as high as 452. An AQI above 400 falls in the “severe” to “hazardous” category, indicating toxic air that can cause immediate irritation such as burning eyes, coughing and breathlessness, while also increasing the risk of respiratory infections and other health problems.
During the five-year period from 2020 to 2025, Delhi reported an average annual AQI of below 200, which is generally considered acceptable. However, in specific months each year, particularly during winter, AQI levels have repeatedly reached alarming levels above 450. Whenever Delhi’s AQI crosses 400, it becomes a subject of serious concern, as is the case again at present. There is a growing apprehension that such episodes may become a recurring, even permanent, feature in the coming years, as a definitive and sustainable solution to this grave problem is yet to be formulated and implemented.
As the capital of India, hosting embassies and consulates of over a hundred countries and having a population density of around 11,600 persons per square kilometre, Delhi’s persistently high AQI has also become a source of embarrassment for the country. Clearly, a lasting solution is urgently required.
A careful assessment suggests that while the Delhi government has taken several steps to address air pollution, many of these measures appear to be reactive rather than preventive. Typically, they are implemented as emergency responses during months when the AQI reaches alarming levels, as has happened again in the last quarter of 2025.
It is often argued that Delhi’s air quality deteriorates sharply in winter mainly due to stubble burning, a traditional practice used to clear paddy fields quickly for the next crop in neighbouring states such as Punjab, Haryana and Uttar Pradesh. The government has taken a number of measures to curb this practice, and in a statement to Parliament, the Union Environment Ministry claimed that Punjab and Haryana together reduced “fire incidents” by 90 per cent in 2025 compared to 2022. Some researchers, however, have questioned this figure, suggesting that the actual reduction in the land area burned was more gradual—around 30 per cent, from about 31,500 square kilometres in 2022 to roughly 19,700 square kilometres by November 2025.
Even allowing for such differences in estimates, it is evident that the incidence of stubble burning has declined substantially. Yet, despite this significant reduction, there has been no corresponding improvement in Delhi’s AQI. This raises serious questions about the relative contribution of stubble burning to the city’s extreme pollution levels.
Whenever the AQI in Delhi exceeds 400, the government adopts a multi-pronged approach, routinely introducing regulatory measures such as the Graded Response Action Plan (GRAP), restrictions on diesel generator sets, promotion of cleaner fuels in industries, a shift towards electric vehicles, CNG and BS-VI diesel in the transport sector, and stricter dust control measures at construction and demolition sites. However, as recent experience shows, these multiple interventions have not succeeded in bringing down the AQI to safe levels.
Several fundamental factors contribute to Delhi’s air pollution. The city is landlocked, and such cities are generally more prone to air pollution because they lack natural atmospheric ventilation and dispersion mechanisms, such as the sea and land breeze cycles and stronger winds that benefit coastal regions. Delhi’s location in the Indo-Gangetic Plain also exposes it to cross-border pollution from other parts of northern India, further compounding the problem. Winter meteorological conditions, including temperature inversions and calm winds, trap pollutants close to the surface, intensifying smog and sharply worsening air quality.
These structural and geographical factors are largely beyond the control of the Delhi government. Past experience indicates that, while several remedial measures have been introduced, they are insufficient by themselves to bring AQI levels down to acceptable limits. This situation suggests the need for a more unconventional and long-term approach.
Delhi’s population density is extremely high, but large-scale decongestion of population is impractical as a policy option. At present, the government tends to implement stringent measures only when pollution peaks, rather than maintaining them throughout the year, which reflects a fundamentally reactive approach. A more consistent and preventive strategy is required.
There is a case for permanently halting new construction activity in the city. Registration of new vehicles could be restricted, with stricter caps on the number of vehicles permitted on the roads. Efforts to eliminate stubble burning in neighbouring states should be intensified to achieve complete compliance. Government and private offices and commercial establishments should be encouraged to relocate outside Delhi and the National Capital Region, with no new establishments permitted within the city. Measures already introduced should be enforced on a permanent, year-round basis rather than as seasonal responses.
Given that the natural and geographical factors making Delhi pollution-prone are likely to persist indefinitely, the measures to combat air quality deterioration must also be permanent and continuous. In essence, Delhi may need to aim for a form of controlled stagnation in growth if it is to prevent air pollution from becoming an inescapable and permanent feature of life in the capital.
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*Trustee, Nandini Voice for the Deprived, Chennai
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