About AirQualityHub

AirQualityHub provides free, hourly air quality figures for 50 major cities worldwide, ranked by fine-particle (PM2.5) pollution, alongside a health guide, a PM2.5-to-AQI converter and explainers on pollution science.

What We Track

• PM2.5 — Fine particulate matter
• PM10 — Coarse particulate matter
• O3 — Ground-level ozone
• NO2 — Nitrogen dioxide
• SO2 — Sulfur dioxide
• CO — Carbon monoxide

Data Source

Current readings come from the Open-Meteo Air Quality API, which publishes hourly pollutant concentrations modelled by the Copernicus Atmosphere Monitoring Service (CAMS). Values are for each city-centre coordinate, in µg/m³, and the US AQI uses EPA breakpoints. Earlier versions of this site used OpenAQ station data until OpenAQ retired its v2 API.

Disclaimer

Data is cached for 15 minutes and model values can differ from nearby ground stations. Always refer to your local government agency for official health advisories and emergency alerts.