Diwali Air Quality: 10-Year City Comparison

Fine particulate matter, PM2.5, is the pollutant CPCB and health researchers treat as the most direct driver of the AQI spike, because firecracker smoke is overwhelmingly fine soot and metal-salt particulate rather than larger dust. CPCB's own pre/post comparison for Delhi, reported by TheProint in October 2025, covers five consecutive years and shows the swing is neither small nor consistent in size:

• 2021: PM2.5 rose from 163.1 to 454.5 µg/m³, a jump of roughly 2.8x.
• 2022: 129.3 to 168 µg/m³, the smallest jump of the five years, roughly 1.3x.
• 2023: 92.9 to 319.7 µg/m³, a 3.4x jump, and the lowest pre-Diwali starting point of the run.
• 2024: 204 to 220 µg/m³, again a comparatively muted rise.
• 2025: 156.6 to 488 µg/m³, the highest post-Diwali reading of the five years and, per CPCB's own analysis, a 212% rise over the pre-Diwali baseline.

The pattern that matters more than any single year's number: post-Diwali PM2.5 has never dropped back to the pre-Diwali baseline within CPCB's reported 24-hour window, and in three of the five years (2021, 2023, 2025) it has more than tripled.

CPCB's National Ambient Air Quality Standards, notified in 2009, set India's own legal ceiling for PM2.5 at 60 µg/m³ averaged over 24 hours and 40 µg/m³ averaged annually, published directly on cpcb.nic.in. Put Delhi's post-Diwali PM2.5 readings next to that number and the scale becomes concrete rather than abstract: 2025's 488 µg/m³ reading is more than eight times the 24-hour limit; even 2022's comparatively muted 168 µg/m³ is nearly three times it. On the AQI scale CPCB itself publishes, 0–50 is "good," 301–400 is "very poor," and 401–500 is "severe," the band Delhi has landed in on Diwali night in most of the last five years.

What is the worst Delhi AQI has been on Diwali?

Among the years verified for this page, Delhi's highest reading is the roughly 680 peak recorded overnight after Diwali 2023, reported by Al Jazeera citing IQAir; the CPCB 24-hour average for that same day-after period was 407. Both figures place that Diwali in the "severe" or worse band on the Indian AQI scale.

Does Delhi's air quality always get worse on Diwali?

Yes, in every year covered by CPCB data reviewed here (2016–2025), Delhi's 24-hour AQI reading around Diwali has stayed at "very poor" (301–400) or crossed into "severe" (401+). The size of the spike varies significantly year to year (2023 was comparatively lower, at AQI 218), but the direction, air getting worse rather than better around the festival, has held every year.

How does Diwali air pollution in Delhi compare to Mumbai or Kolkata?

On the one night with a direct, verified same-day comparison (Diwali 2023), Delhi's post-Diwali AQI of 407 was roughly 2.5 times Mumbai's 157 and Kolkata's 154. Delhi-NCR's low winter wind speed and temperature inversion trap smoke close to the ground far more than Mumbai's coastal airflow or Kolkata's delta location, which is the main reason the same festival produces such different readings across cities.

Is the post-Diwali PM2.5 spike actually dangerous?

CPCB's own National Ambient Air Quality Standards cap safe PM2.5 exposure at 60 µg/m³ over 24 hours. Delhi's post-Diwali PM2.5 readings have exceeded that limit by wide margins in every year from 2021 to 2025 covered on this page, from roughly 3 times the limit (2022) to over 8 times the limit (2025). This page reports air-quality data only; for guidance on health effects and prevention, see our data page on Diwali firecracker injuries.

Is Diwali air quality getting better because of green crackers?

The data on this page does not show a consistent multi-year improvement. 2023 was a genuinely cleaner Diwali on both AQI and PM2.5 measures, but 2024 and 2025 both reversed that gain, and CPCB's own reporting attributes much of the year-to-year swing to wind speed and temperature inversion strength on the specific night, not firecracker volume alone. No source cited here shows the green-cracker mandate producing a steady downward AQI trend to date.

For lower-emission ways to mark the festival, read our eco-friendly Diwali guide or plan your evening against your own city's forecast with the AQI-safe Diwali planner. Browse the rest of our data & research hub for related figures.

Written by the buyonlinecrackers.com editorial team. Every figure above is drawn from a named CPCB bulletin or news report citing CPCB/IQAir data, cited individually above. Refreshed each Diwali season; last verified 2026.