Airwyn

Airwyn lets you monitor a single public PurpleAir sensor or US EPA (AirNow) sensor. You can get a notification with audible alert when air quality index (AQI) goes up or down. This can let you make important decisions for your safety and health -- like when to go inside, and when to open or close windows.
A map gives an overview of AQI in your neighborhood or over the entire world, and lets you pick a PurpleAir or US EPA sensor to monitor. A simple graph shows how the air quality has changed over the last few days for your chosen sensor.
AQI conversion formulas from US EPA, LRAPA, and AQandU are supported.