https://www2.purpleair.com/products/list To me they seem like a company who sells products and their map is secondary. They even advertise their stuff on the map itself.

“PurpleAir is built on the ideal of sharing data and by doing this, empowering individuals to effect change. All public PurpleAir data is available to download under various licenses from private, not for profit use to educational and commercial use. The common element between these uses is to share attribution.” (https://community.purpleair.com/t/about-the-data-category/70) – Raws li qhov ntawd tej zaum 4/5 blocks yuav yog qhov tseeb. Tsis pom muaj trackers lossis tshaj tawm dab tsi ntawm lub vev xaib.