What does the asterisk (*) mean on some locations' AQI?

Whilst the world's coverage of ground-based air monitoring stations is continuing to grow, there are still large parts of the world which have no access to real-time, public air quality measurements.

As a means to begin filling some of these gaps, AirVisual provides some estimated AQI data for locations which are lacking ground-based measurements, to help guide actions to protect health. The AQI estimations are calculated based on satellite PM2.5 data.

On the AirVisual app and website we take care to clearly show which data is estimated, and which data comes from ground-based monitors, so that you are properly informed in your decisions to protect your health.
See examples of the "estimated AQI" label below: