Smog in Delhi: AQI turns ‘hazardous’ at 377 two days after Diwali, authorities enforce GRAP-2

Delhi woke up to a thick layer of toxic haze on Tuesday morning, as the city’s Air Quality Index (AQI) touched 377 — ‘hazardous’ levels — marking the worst post-Diwali morning in five years. According to the Central Pollution Control Board (CPCB), PM2.5 levels surged to 488 µg/m³, over three times the pre-festival average of 156.6 µg/m³, amid dense mist, high humidity, and almost stagnant winds that trapped pollutants near the surface.

A Climate Trends study analysing data from 2021 to 2025 found that Delhi’s air consistently worsens during Diwali night and the following morning, but this year’s spike was the steepest since 2021.

By Tuesday afternoon, four key locations — Dwarka (417), Wazirpur (423), Anand Vihar (404) and Ashok Vihar (404) — had entered the ‘severe’ pollution category, according to CPCB’s SAMEER app. The city’s 24-hour average AQI, reported at 4 pm, stood at 345 (‘very poor’), higher than Sunday’s 326.

Authorities have now enforced Stage II of the Graded Response Action Plan (GRAP) across Delhi-NCR, cautioning that air quality could worsen in the coming days. Forecasts from the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorology (IITM) suggest continued calm conditions, offering little relief.

Experts attributed the sharp rise in pollution to widespread firecracker use, low wind speeds below one metre per second, and temperature inversion that prevented dispersion. 

“The spike in PM2.5 levels is largely due to local firecracker emissions across Delhi. Wind speeds were extremely low, leaving no scope for dispersion,” S.K. Dhaka, professor at Rajdhani College, University of Delhi, told PTI, adding that stagnant weather conditions had effectively “locked the smoke in” through the night.

Dhaka added that even “so-called green firecrackers” had contributed to the particulate load, calling for stricter checks on their composition and quality.

Aarti Khosla, founder and director of Climate Trends, said the annual spike highlights gaps in enforcement and public awareness. “It is disheartening that after years of witnessing the harmful effects of burning firecrackers, we still repeat the same mistake,” she told PTI.

Amid the rising pollution levels, BJP leader Shehzad Poonawalla was seen wearing a gas mask while addressing the media in Delhi-NCR. Speaking to ANI, he criticised the Aam Aadmi Party (AAP) government, saying, “Delhi has become a gas chamber. AAP used to blame stubble burning in Punjab for that. Now, more than 6,000 cases of stubble burning have happened in Punjab, but they chose to stay silent on that. They blame Diwali, UP and Haryana for the rise in air pollution, but stay silent on Delhi’s internal issues. Whether it is pollution in the Yamuna River or the city’s air, AAP is responsible for all this.”

Morning visuals showed Akshardham and parts of central Delhi blanketed in haze, as the city recorded 24°C with 89% humidity and minimal wind movement. The Supreme Court had recently permitted the sale and bursting of green firecrackers in Delhi-NCR during limited hours on Diwali eve and the festival day.

According to the CPCB, an AQI between 0–50 is considered ‘good’, 51–100 ‘satisfactory’, 101–200 ‘moderate’, 201–300 ‘poor’, 301–400 ‘very poor’, and 401–500 ‘severe’.