I understand that, as I sometimes have a few of them running in parallel. The “Smoggie” has a smaller fan, see datasheet attached. For the A3 it might be possible to increase the sending interval and use powersave. With this setup, the unit will do the measurements, then go to sleep (including the fan) for the amount of time you define. Would this work?

The FAN has a dual purpose:
– it pushes air through a narrow path inside the PM sensor
– it pushes air across all sensitive elements

While an open case (A3 Stevenson shield) can take advantage of the natural air convection, wind, or general air movement, the PM sensor will still need a controlled airflow.

So to make this work, the only option to lower noise is to reduce its frequency, using the sleep mode option.

On the other hand, the noise itself is ~35dB near the unit, quite low. If you have the A3 you can evaluate that yourself.