On Diwali night, the city's PM2.5 level soared to 16 times the national safe limit, exposing lakhs of residents to hazardous air as crackers burst well beyond the Supreme Court's 8-10pm window.

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.

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.

On Diwali night, Gurgaon’s PM2.5 levels soared to 16 times the national limit as residents continued bursting crackers well past the Supreme Court’s permitted 8–10 pm window. The hourly concentration of PM2.5—a fine particulate pollutant linked to respiratory problems—rose sharply, with Sector 51 recording the highest at 949 micrograms per cubic metre around midnight. Despite restrictions, fireworks continued sporadically till 2 am in several neighbourhoods, including DLF phases, Sector 56, Palam Vihar, and Golf Course Extension. Residents complained that noise and smoke lingered for hours, reducing visibility. Officials said the city’s air quality remained in the ‘severe’ category for several days after Diwali.

Gurgaon is expected to witness dense haze following Diwali as weather conditions turn unfavourable for pollutant dispersion. According to the IMD, wind speeds will drop below 8 kmph, and calm conditions may trap smoke, causing AQI levels to deteriorate sharply after the festival.

Ground-level ozone has been the lead pollutant on 10 of the 17 days this October, according to the Central Pollution Control Board (CPCB). While October normally sees the highest ozone levels, this year’s concentration exceeded 90 micrograms per cubic metre on several days, making it the highest for October since 2020.

Scientists warn that even if green crackers reduce pollution by 30 %, the very large number of fireworks burst during Diwali in Delhi-NCR could cancel out that gain.

They argue the scale of use, weak enforcement, and mixing with conventional crackers limit any real benefit to air quality.

Ahead of a Supreme Court decision, people in Delhi are split on "green crackers". Some residents support the eco-friendly fireworks for Diwali, while others are against any firecrackers because of the city's poor air quality.

While "green crackers" are less toxic than regular fireworks, experts warn they will still pollute Delhi's air. Using them will add to the city's severe pollution and make it harder to breathe, especially during winter.

"Green crackers" are set to return for Diwali in Delhi, but their sale is waiting for a final decision from the Supreme Court. These special fireworks are known for causing about 30% less pollution compared to traditional ones.

After being offline for several months, all four air-quality monitoring stations in Gurgaon have now started recording data again and are connected to both state and central pollution dashboards.

Delhi’s air quality has worsened significantly in 2023-24, with PM2.5 and PM10 levels rising despite various government measures like PUC audits, mist sprayers and EV infrastructure. Experts stress that superficial fixes are inadequate, urging a comprehensive approach to reduce pollution at its source from transport, power and waste, advocating for systemic change and strict enforcement for breathable air.

The report highlights that traffic congestion and air pollution in Lucknow are reducing life expectancy, with private vehicle use and weak public transport being major reasons.