Ambient Weather Support

With PM2.5 sensors, fog reflects the light, and can result in a higher reading.  This is characteristic to the inherent sensor design.

The condition occurs during rainy or foggy weather, where:

Outdoor Temperature – Dew point Temperature ≤  2º C (3.6 ºF)

Thus, when the air is nearly saturated, the data is invalid.

Do your best to mount the sensor in a well drained area which is less prone to moisture condensation if possible.

Product Manual
https://ambientweather.com/mwdownloads/download/link/id/478/

Product Page
https://www.ambientweather.com/ampm25.html