Data Sources

All data on this site comes from three public providers, mirrored via oaq.notf.in.

Providers

CPCB cpcb: Central Pollution Control Board, Government of India, and State Pollution Control Boards. The authoritative source for regulatory air quality monitoring in India. ~580 stations across 250+ cities. cpcb.nic.in
Airnet airnet: Center for Study of Science, Technology and Policy (CSTEP). Dense low-cost sensor network, primarily in Bengaluru. cstep.in
Aurassure aurassure: Aurassure University Clean Air Network. University-hosted low-cost sensors. aurassure.com

How this site gets the data

A Cloudflare Worker performs the OAQ broker handshake once per day and caches the signature.
Every hour, the Worker fetches all_stations_latest.json for each of the three providers in a single bulk request.
Stations are normalized, CPCB AQI is computed from raw pollutants, and a merged snapshot is written to Cloudflare R2.
The static site is rebuilt from that snapshot — no client-side API calls, no API key in the browser.

Total upstream requests: ~80 per day. Well inside any reasonable rate limit.

Licensing

Upstream data is published as open air quality data, typically under CC BY 4.0. This site does not relicense the data; all original attribution and license terms apply to the upstream sources.

The site code is MIT-licensed.

Update cadence

Snapshot refresh: every hour on the 5-minute mark.
Station metadata (names, coordinates) refresh: daily at 02:00 IST.
Upstream CPCB data itself updates ~hourly, so polling faster would return identical data.