Siwan — AQI Trends
Year-over-year AQI trajectory for Siwan (2021–2024). Based on CPCB station data, 2016–present.
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Siwan — annual AQI 2021–2024
Year × month heatmap
Worst single days on record
- 2022-12-30Chitragupta Nagar (BSPCB)488
- 2022-12-31Chitragupta Nagar (BSPCB)469
- 2022-12-13Chitragupta Nagar (BSPCB)460
- 2022-11-30Chitragupta Nagar (BSPCB)460
- 2022-11-29Chitragupta Nagar (BSPCB)454
- 2022-01-21Chitragupta Nagar (BSPCB)452
- 2023-01-14Chitragupta Nagar (BSPCB)442
- 2022-12-20Chitragupta Nagar (BSPCB)440
- 2022-12-19Chitragupta Nagar (BSPCB)440
- 2022-11-28Chitragupta Nagar (BSPCB)439
What the numbers say
Overview
Siwan's AQI moved from 332 in 2021 to 148 in 2024 — a fall of 55.4% over 3 years. The long-run trend is improving, with a regression slope of -59.3 AQI points per year.
The data story
The worst recorded year in Siwan was 2021 at AQI 332, while the best was 2024 at AQI 148. The city has posted 39.300000000000004% of all measured days above AQI 200 (the Poor threshold), and its worst recorded single day hit 488 on 30 Dec 2022.
Why this pattern
The improving direction mirrors national NCAP (National Clean Air Programme) targets introduced in 2019, which aimed for a 20–30% PM reduction by 2024. Cleaner fuels, tighter vehicle standards, and the 2020 COVID lockdown year all show up in the yearly series. Sustained reduction past 2024 will depend on continued enforcement, industrial fuel switching, and controlling seasonal spikes from biomass burning and festivals.
What to do with this
For planners and residents, the trend matters as much as today's number. A worsening city needs aggressive source control and personal protection investments like indoor purifiers. An improving city rewards continued policy pressure but still requires caution during peak months. Use the live AQI page for day-to-day decisions and this chart for multi-year context. Year-over-year change of more than 10% in either direction is typically real signal, not noise.