Chennai vs Siwan
Side-by-side air quality comparison between Chennai and Siwan.
Live AQI from Open-Meteo CAMS (~45 km global model, updated hourly). Multi-year history from CPCB station data via aqinow.co pipeline (2016–2024, station-level daily records).
AQI Comparison
Pollutant-level comparison (PM2.5, PM10, O3, NO2, SO2, CO)▾
| Pollutant | Chennai | Siwan |
|---|---|---|
| PM2.5(µg/m³) | 11.70 | 114.60 |
| PM10(µg/m³) | 13.10 | 125.70 |
| NO₂(µg/m³) | 14.20 | 44.50 |
| SO₂(µg/m³) | 10.10 | 15.40 |
| O₃(µg/m³) | 56.00 | 54.00 |
| CO(µg/m³) | 308.00 | 761.00 |
CPCB Multi-Year History (2016–2024)
Summary
Overview
In 2024, Chennai averaged an AQI of 68 while Siwan averaged 148 — a 80-point (118%) gap, with Siwan the more polluted and Chennai the cleaner of the two. On 491 days when both cities reported, Chennai was cleaner on 388 of them; the average daily gap was 108 AQI points.
Seasonality & days
Chennai peaks in December, while Siwan peaks in January. Chennai logged 0% Severe days and 57.5% Good-or-Satisfactory days; Siwan was 5.2% Severe and 17.7% Good-or-Satisfactory. Longest clean-air streaks: Chennai 53 days, Siwan 13 days.
Year-over-year progress
Chennai has improved by 25 AQI points (26.9%) from 2017 to 2024; Siwan has improved by 184 AQI points (55.4%) over the same window. The worst recorded day for Chennai reached AQI 391 at Kodungaiyur (TNPCB) on 2021-05-14; Siwan hit AQI 488 at Chitragupta Nagar (BSPCB) on 2022-12-30.
Station-level disparity
Chennai spans 9 CPCB stations with a 27-point spread (min 63, max 90); Siwan spans 1 stations with a 0-point spread (min 197, max 197).
Verdict
🏆 Chennai has better air quality with an AQI of 20 compared to Siwan's 282. That's a significant difference of 262 points.