With so many data layers on the PurpleAir Map, it can be difficult to determine which one to choose.
There are many air quality indexes (AQI) created by different national governments such as the USA, Canada, Australia, etc. You will find that the standards differ with the numerical scale used and the importance placed on each pollutant. PurpleAir does not make any recommendations on the appropriateness of these standards. Our users might be inclined to use the AQI created by their national government or they may choose an AQI that is simplest for them to understand. The default PurpleAir Map setting is the US EPA PM2.5 AQI. An explanation of these AQIs can be found in our Air Quality Index Layers article.
The World Health Organization (WHO) provides guidelines for global air quality, which can assist governments in creating air quality standards based on their own research. More information can be found in WHOs air quality guidelines.
An explanation of how to change your AQI data layer can be found in our Map Start-up Guide.