Following the Deepavali celebrations, air pollution levels in Delhi surged alarmingly, highlighting a significant decline in air quality. Average concentrations of particulate matter (PM) 2.5 reached over 400 micrograms per cubic meter (μg/m3) in various locations, marking levels not observed since 2021.
On the actual day of Deepavali, nine out of 293 cities monitored by the Central Pollution Control Board (CPCB) reported an Air Quality Index (AQI) exceeding 300, categorized as “very poor.” The day after Deepavali, this number increased to 16 cities, predominantly in northern India and the Indo-Gangetic plains. The town of Dharuhera in Haryana recorded the worst AQI in the country at 462 on October 21.
According to an analysis conducted by the independent agency Climate Trends, there was a noticeable spike in PM 2.5 levels starting at 4 PM on Deepavali day. Levels rose dramatically from around 150 at 4 PM to nearly 650 by 11 PM. This surge coincided with the legally permissible timeframe for firecracker use (8 PM to 10 PM), as stipulated by a reprieve from the Supreme Court.
The court had permitted the use of only “green crackers,” which are supposed to generate at least 30% less smoke compared to traditional firecrackers. However, anecdotal evidence suggests widespread violations of these guidelines, as many reported difficulty in finding green crackers.
Critical factors influencing air quality include wind speeds and temperature during the festival night. This year, night temperatures ranged from 23 to 25 degrees Celsius, the warmest in five years. Despite this, low wind speeds impeded the dispersion of smoke and pollutants, leading to stagnant conditions.
The report from Climate Trends indicated a consistent correlation between high emissions from fireworks and low nighttime temperatures, which resulted in elevated PM 2.5 levels. The pronounced spikes in pollution following Deepavali suggest both persistent emissions and insufficient atmospheric dispersion. “The Diwali of 2025 was among the most polluted in recent years,” stated Palak Balyan, Research Lead at Climate Trends. “The data confirms that allowing firecrackers is not sustainable for maintaining air quality in the NCR region.”
Data from the CPCB shows an AQI of 358 (very poor) for Delhi on November 13, 2023, shortly after Deepavali. This figure is close to the 351 recorded at 4 PM this year. The highest AQI in recent times was 462 recorded on November 5, 2021. This year”s AQI during Deepavali was 345, slightly lower than the 382 recorded in 2021.
The CPCB is expected to release its annual report on air quality and noise pollution levels from Deepavali night and the following day later this week. The Environment Ministry has not provided any comments or analysis regarding the air quality in Delhi following the festival.
