Comparison uses the same unified current-value service as the Global Map, city pages and Air Quality Near Me. Where a current OpenAQ monitoring observation is available, it is used; otherwise the current Open-Meteo / CAMS model value is used. Different national AQI systems should not be treated as numerically identical.

With thanks to OpenAQ: AirQualityIndex.org gratefully acknowledges OpenAQ for making its API available and for supporting access to a broad global network of air-quality monitoring locations.