“In July 2023, real-time Air Quality information is available for than 50,000 stations in 2000 major cities from 132 countries, thanks to the huge effort from the world EPAs (Environmental Protection Agencies). There are currently more than 50,000 known air quality monitoring stations in the world. In order to keep a high level on consistency, only stations with particulate matter (PM_2.5/PM₁₀) readings are published. The AQI standard for every single published station is based on the US EPA Instant-Cast standard. The data published on the World Air Quality Index is real-time and therefore unvalidated at the time of publication. However, in order to ensure high level of accuracy for each AQI figures, several machine learning processing solution are used. For instance, data consistency is verified, in real-time, with the neighbor stations, allowing to automatically detect defective monitoring stations, and remove them, if needed, from the map. The map below shows the location of the known monitoring stations (screen-shot from August 2018)…”