An update: last night the next cloud of dust rained down over the Berlin/Brandenburg area. Peak values at 4am from the official stations:
At the location of my sensors the expected values should be close to PM2.5 = 57µg/m^3 and PM10 = 71µg/m^3
Here is the data from the airrohr sensor (SDS011 & SPS30)
And here is an SDS011 in the NAM enclosure (with heating)
Humidity plot for the same time (SHT35 with SF2 cap and the best BME280 I could find)
I feel this is a really good result and could be an interesting sidenote in the discussion that @Denis and @irukard have in another thread.
Note, that I do not know which SDS011 is currently build into the NAM. I tried several but they are all from end of 2020.