SmogRank / World / Asia / India / Tamil Nadu
Most polluted cities in Tamil Nadu, India
2 measured cities, last 30 days; 2 above the WHO 24-hour guideline. Worst: Chennai at 25.4 µg/m³, #167 in the world.
464 monitors in India haven't reported for more than two days. Cities that rely on them are missing from the 24-hour board and may drop from the longer ones; that isn't clean air, and they return when the data does.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
Cities coloured by their PM2.5 over the last 24 hours. Fires, smoke and ash: Oct 5, the newest UTC day mapped.
- 1Chennai 14%
- 2Naduvattamlast full day 30 Sept 0%
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Estimated: cities without a monitor
Tamil Nadu cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| Kallakurichi | ≈ 30 µg/m³ |
| Madurai | ≈ 18 µg/m³ |
| Tirunelveli | ≈ 15 µg/m³ |
| Tiruchirappalli | ≈ 21 µg/m³ |
| Tiruppur | ≈ 23 µg/m³ |
| Salem | ≈ 25 µg/m³ |
| Erode | ≈ 22 µg/m³ |
| Vellore | ≈ 33 µg/m³ |
| Ambattur | ≈ 32 µg/m³ |
| Thoothukudi | ≈ 15 µg/m³ |
| Avadi | ≈ 32 µg/m³ |
| Dindigul | ≈ 18 µg/m³ |
| Thanjavur | ≈ 22 µg/m³ |
| Rānipet | ≈ 33 µg/m³ |
| Tiruvottiyūr | ≈ 25 µg/m³ |
| Sivakasi | ≈ 16 µg/m³ |
| Karur | ≈ 18 µg/m³ |
| Pallāvaram | ≈ 27 µg/m³ |
| Ooty | ≈ 14 µg/m³ |
| Hosūr | ≈ 25 µg/m³ |
| Nāgercoil | ≈ 15 µg/m³ |
| Kanchipuram | ≈ 30 µg/m³ |
| Kumarapalayam | ≈ 24 µg/m³ |
| Kāraikkudi | ≈ 15 µg/m³ |
| Neyveli | ≈ 25 µg/m³ |
| Tambaram | ≈ 27 µg/m³ |
| Kumbakonam | ≈ 22 µg/m³ |
| Tiruvannamalai | ≈ 32 µg/m³ |
| Rajapalayam | ≈ 16 µg/m³ |
| Kurichchi | ≈ 20 µg/m³ |
| Madhavaram | ≈ 25 µg/m³ |
| Pudukkottai | ≈ 18 µg/m³ |
| Ambur | ≈ 30 µg/m³ |
| Nagapattinam | ≈ 15 µg/m³ |
| Villupuram | ≈ 26 µg/m³ |
| Kuniyamuttūr | ≈ 20 µg/m³ |
| Paramagudi | ≈ 17 µg/m³ |
| Tiruchengode | ≈ 23 µg/m³ |
| Vaniyambadi | ≈ 30 µg/m³ |
| Kovilpatti | ≈ 16 µg/m³ |
Bad-air episodes in Tamil Nadu
- Southern India, November 202511 to 14 November 2025, 4 days12 cities119 µg/m³peak, Neelankarai
- Southern India, 12 to 14 October 20253 days12 cities114 µg/m³peak, Chittoor
- Southern India, 7 to 8 October 20252 days9 cities97 µg/m³peak, Chittoor
- Tamil Nadu and Karnataka, India, August 202528 to 29 August 2025, 2 days9 cities171 µg/m³peak, Nagapattinam
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
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SmogRank, most polluted cities in Tamil Nadu, India, PM2.5, last 30 days to 6 Oct 2026, 23:00 UTC, smogrank.com/in/region/tamil-nadu?w=30d.
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Updated 2026-10-06 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.