Experts say Delhi must shift from reactive responses like GRAP to proactive, data-driven and accountable policies. Drawing lessons from London’s congestion pricing and Beijing’s regional industrial controls, they stress targeting power plants, enforcing emission cuts and linking administrative accountability to results for achieving cleaner, healthier air by 2030.

Delhi-NCR saw improved air quality in early 2025 due to favourable weather. After Diwali, AQI surged, making Delhi the most polluted major city globally. Data from CPCB and IQAir highlighted drastic AQI increases, with residential and industrial areas worst hit. Can green crackers help?

From Oct 20 onward, ozone and CO disappeared from the AQI charts, replaced by particulate matter – tiny, hazardous particles that penetrate deep into the lungs.

Delhi’s air turned toxic after Diwali — while Central Pollution Control Board (CPCB) recorded an AQI of 351, IQAir logged a much higher figure of 1,121, highlighting a major difference in monitoring results.

Despite Delhi's severe "very poor" air quality, experts note the usual spike in pollution from farm fires in Punjab and Haryana has not yet happened. Its contribution has been minimal, peaking at just 2.6%, meaning the current smog is from local sources like vehicles and industry. This delay is attributed to floods disrupting the harvest and unfavourable wind patterns, pushing the expected surge in smoke to after October 28th.

The contribution of stubble burning in neighbouring Punjab and Haryana has remained negligible this season – below 1% on most days, and peaking at just 2.6%

Delhi AQI today: The analysis by the Decision Support System (DSS), which tracks pollution sources, showed that the mix of emissions affecting Delhi had shifted since Diwali on October 20.

Delhi's air pollution is a year-round menace, not merely a winter phenomenon. The city is trapped in a perfect storm of its own traffic, industry, and construction dust, which is then catastrophically exacerbated each autumn by agricultural burning in neighbouring states. The fundamental question remains whether India's capital can ever truly escape its toxic air and reclaim a healthy environment.

Source apportionment data from the Decision Support System (DSS) for air quality management shows that the mix of pollution sources impacting Delhi has changed since Diwali on October 20.

Both CPCB and IQAir follow different methods of calculating air quality index, resulting in different numbers.

During Diwali, Delhi’s pollution worsened significantly, with 36 out of 38 air quality monitoring centres falling into the ‘red zone’. Sunil Dahiya mentioned that the smoke from fireworks, combined with vehicle emissions and construction dust, made the air extremely unhealthy, affecting breathing for most residents.

Delhi’s air quality stayed in the “very poor” range two days after Diwali, with an AQI of 353. Data from the Decision Support System showed that over 36% of the pollution came from “unaccounted sources”, meaning emissions not clearly identified or tracked. Transport, industry, and waste burning also added to the problem. Sunil Dahiya from Envirocatalysts explained that these unaccounted sources likely include power plants, industries, and crop burning in nearby states, which are not properly captured in pollution records.

A reading of 351 qualifies as “very poor” – a category for which NCDC recommends “avoiding physical activity outdoors” and remaining indoors as far as possible

Stations at Jawaharlal Nehru Stadium, Nehru Nagar, Patparganj, and RK Puram each lost about eight hours of readings.

An analysis of CPCB and DPCC data by HT revealed that only nine stations – barely 23% of the city’s monitoring network – recorded continuous data

Several air quality monitoring stations in Delhi, including RK Puram, went offline for hours on Diwali night, leaving critical PM2.5 data missing during peak pollution hours. Experts said the data gaps skewed average readings and hindered analysis of pollution sources. Sunil Dahiya, founder of EnviroCatalysts, said missing data hampers understanding of pollution trends and called for improved data transparency and monitoring practices.

Several government-run open-access websites that publish real time monitoring of air quality were unavailable for several hours during peak firecracker time on Diwali day

Firecracker emissions contributed between 30% and 40% to Delhi’s pollution on Diwali, with PM2.5 levels spiking eightfold due to stagnant wind conditions. Experts said calm weather and poor dispersion worsened air quality overnight, pushing pollution levels 60–67 times above WHO’s safe limit. Data analysis by EnviroCatalysts revealed that PM2.5 levels on Diwali night have consistently surged 200–300% compared to pre-Diwali levels since 2021.

The report has revealed that a significant failure occurred as 30 of Delhi's 39 official air quality monitors were offline during the Diwali period, hiding the true scale of the pollution crisis from the public.