Conversion Factor for PM2.5 AQI LEDs (Zen)

I have the Zen sensor for measuring my indoor air quality. My understanding is that the sensors overestimate PM2.5 and thus AQI values, especially at higher concentrations, and that is why the conversion factors exist.

So, when the AQI is roughly displayed via the color changing LEDs (i.e. green = good, yellow = moderate, etc.) is it using one of the conversion factors (e.g. “US EPA”) or is there no conversion factor applied (equivalent on the map of “Apply conversion: No”)?

Much appreciated


Hi @moeck602, the LEDs on PurpleAir devices display the US EPA PM2.5 AQI with no conversion factor applied. We hope to include a feature in the future to change the AQI scale and conversion factor it displays.


This would be so useful for users outside the US who have different AQ indices!