I'm also observing an unusually high NO2 value, but I don't see a strong correlation to anything but O3. I don't have another sensor to verify against though, but the temperature or humidity don't seem to vary as much.

I'm now wondering if the air here really is that bad - or if the sensor is questionable?

Also meines Wissens nach sollten maximale Ausschläge auch noch auftreten, hast du das mal geprüft?