Yes, the issue is the cabin air filter. The simple paper pollen filters don't do anything against NO2 - we measure the same values inside and outside. Most fi

Yes, the issue is the cabin air filter. The simple paper pollen filters don't do anything against NO2 - we measure the same values inside and outside. Most filters with active charcoal will reduce the NO2 concentration a lot. It is recommended to replace them after 1-2 years or a certain distance, but we don't have numbers on this - still, it is clear the filters degrade after a while.