Sizes of Particles

This link will show you how to register your sensor.

https://community.purpleair.com/t/sensor-wifi-and-registration/182

This link will lead you to the Purple Air nationwide map.

https://map.purpleair.com/air-quality-standards-us-epa-aqi?opt=%2F1%2Flp%2Fa10%2Fp604800%2FcC0#1/23.9/-30

what is AQI

TIME article (Get one in Every School)