Chennai stood out for its severe pollution surge during Deepavali

lluminating the sky with colourful firecrackers being burst during Deepavali festival celebrations in Chennai City
| Photo Credit: JOTHI RAMALINGAM B

Many Indian cities, including Chennai, Hyderabad, and Ahmedabad, recorded their highest PM₁₀levels of the year around Deepavali, but Chennai stood out for two reasons. First, unlike some other cities that experience consistently high pollution levels, Chennai’s PM₁₀ concentrations spiked only around Deepavali. Second, the city’s peak PM10 level around Deepavali was the second highest in the country.

The chart below shows hourly PM₁₀ levels recorded between January 1 and October 22, 2025, across select cities.

Both the darker red shades and larger circles represent higher PM₁₀levels. Hourly PM₁₀levels crossed the 900-mark in Chennai and Ahmedabad around Deepavali, closely followed by 830 in Noida, 790 in Hyderabad, and 846 in Delhi.

Only one measuring station in a prime residential area in each city was considered. While Ahmedabad recorded the highest levels of pollution this year around Deepavali, it has experienced high levels of pollution throughout the year unlike Chennai. Hyderabad also saw a sharp Deepavali spike, though its peak levels remained lower than Chennai’s.

The chart below shows hourly levels of NH₃, NO, NO₂, SO₂, and PM10 and PM_2.5. recorded in Velachery, Chennai. All these pollutants showed sharp spikes during Deepavali hours. NOₓ (NO + NO₂) and SO₂ levels reached their annual peaks, while both PM₁₀and PM_2.5 also recorded their highest levels of the year. In the graph, red dots indicate Deepavali days in 2025.

Such sharp spikes in air pollutants were seen this Deepavali mainly in Chennai and Hyderabad. However, due to persistent rain, pollution in Chennai dropped sharply soon after peaking.