Delhi's air quality slips into 'severe' category on Diwali; Mumbai's AQI at 170

An AQI of 418 means Delhi's air was in the CPCB's 'severe' category, which covers readings from 401 to 500. This indicates a much more polluted situation than Mumbai's AQI of 170, which falls within the 'moderate' range of 101 to 200. The distinction matters because higher AQI levels bring greater concern about exposure and stronger pollution-control action.

Ghazipur recorded 418, while several Delhi stations went even higher. Burari Crossing reached 441, and Vivek Vihar recorded 437. In Mumbai, the citywide reading was 170, although Kherwadi-Bandra East reached 264, classified as 'poor'. AQI is calculated from air-pollution measurements and translated into categories that make conditions easier to understand.

Delhi's reading shows that severe pollution was concentrated across many locations, not limited to one station. Mumbai also had haze, but its overall air remained much cleaner than Delhi's. The contrast highlights how local pollution sources and weather can produce sharply different conditions in major Indian cities.

Pollution was widespread across Delhi in the early hours after Diwali. Several monitoring stations recorded AQI readings above 400, placing them in the 'severe' category. Many other locations fell between 301 and 400, the 'very poor' range. This broad spread shows that poor air was not confined to one neighbourhood.

Burari Crossing recorded the highest reading at 441. Vivek Vihar followed at 437, with DTU at 434. North Campus of Delhi University and Jahangirpuri each recorded 433, while Rohini reached 430. Other severe readings included Ghazipur at 418, Mundka at 417, Punjabi Bagh at 409, NIH Narela at 407 and ITO at 407.

Several stations remained very poor, including CRRI Mathura Road at 396 and Aya Nagar at 386. Akshardham recorded 337, and Najafgarh 340. Data for IIT Delhi and Dwarka Sector 8 was unavailable, so the listed figures do not cover every station.

The article reports that Delhi's air deteriorated a day after Diwali celebrations. Hazy conditions and reduced visibility appeared across several parts of the capital, with smog particularly visible around Inderlok. The timing raised fresh concerns about post-festival pollution and its effect on the city's air.

The article does not provide a detailed source-by-source breakdown of the pollution. In general, fireworks can release fine particles and gases, while traffic, construction dust, industry and open waste burning can add more pollution. These sources can combine, especially when emissions rise over a short period. This broader explanation uses established air-pollution knowledge beyond the article's specific findings.

Delhi's monitoring data showed the result: Ghazipur reached 418, and Burari Crossing 441. The CAQM had already invoked GRAP Stage III before Diwali because forecasts indicated worsening conditions. Continued haze and high readings show why post-festival pollution can remain a serious problem even after celebrations end.

When AQI reaches the severe category, polluted air can affect daily life and public health. Established health guidance links severe pollution with irritation, breathing difficulty and worsening of existing heart or lung conditions, especially among children, older adults and people with respiratory illness. These specific effects are general knowledge; the article itself does not detail them.

The article documents immediate disruptions. Delhi experienced haze and reduced visibility, while Stage III GRAP measures included stricter vehicle restrictions, a halt to construction activities and hybrid learning arrangements for primary school students. Such steps reduce exposure and limit activities that can add more pollution.

At readings such as 418 in Ghazipur and 441 at Burari Crossing, people may face a more hazardous environment than during moderate or very poor conditions. The article shows that authorities act before conditions worsen further, using restrictions and enforcement. Continued monitoring and pollution-control measures become increasingly important when severe readings are widespread.

GRAP, or the Graded Response Action Plan, is a four-stage emergency framework managed by CAQM with CPCB and regional governments. Its restrictions become stricter as air quality worsens. Stage III applies when AQI reaches 401 to 450, the 'severe' range. It is designed to prevent pollution from deteriorating further through early, coordinated action.

Under Stage III, authorities introduce stricter vehicle restrictions, halt construction activities and arrange hybrid learning for primary school students. The plan covers Delhi and adjoining districts in Haryana, Uttar Pradesh and Rajasthan. It can be invoked using pollution and weather forecasts, before citywide AQI necessarily reaches severe levels.

CAQM invoked Stage III across Delhi-NCR on Friday, three days before Diwali. The action followed concerns about worsening pollution. The measures combine restrictions, enforcement and pollution-control work. If AQI exceeds 450, Stage IV applies, bringing restrictions on heavy goods vehicles and emergency measures aimed at traffic and industrial pollution.

Delhi's pollution becomes more dangerous when weather conditions limit the movement of air near the ground. Pollutants then remain concentrated where people live, travel and work instead of dispersing into the wider atmosphere. The article refers to meteorological forecasts from IMD and IITM when describing GRAP decisions, but it does not explain the detailed trapping mechanism.

In established atmospheric science, weak winds can reduce ventilation, while stable air can prevent polluted air from mixing upward. Temperature inversions can also leave cooler, polluted air beneath warmer air. Emissions from traffic, construction, industry, waste burning and fireworks may therefore accumulate near the surface rather than spread out.

This helps explain why the same emission sources can produce different AQI readings on different days. Delhi reported severe readings at stations including Burari Crossing, Vivek Vihar and Ghazipur. Forecast-based measures matter because authorities can impose restrictions before pollution becomes severe across the city, as happened with Stage III before Diwali.

Urban smog is generally a mixture of fine particulate matter, larger particles and gases such as nitrogen dioxide, sulfur dioxide, carbon monoxide and ozone. These pollutants can harm air quality in different ways. The article reports AQI readings but does not provide laboratory measurements identifying the exact pollutants present in Delhi's post-Diwali smog.

Fireworks can release fine particles and chemical gases. Vehicles emit exhaust, while construction creates dust that can become airborne. Industrial activity can add particles and gases, and open waste burning releases smoke and toxic compounds. When several sources operate together, the combined pollution load can push AQI upward. Weather conditions can further prevent dispersion.

Delhi's readings show the outcome: Burari Crossing reached 441, and several stations exceeded 400. GRAP therefore includes controls on dust, vehicles, construction, industry and open burning across its stages. Identifying the precise source mix requires monitoring data beyond the figures provided in this article.