Does being inside protect you from outdoor air pollution?

In this above plot, you can see PM2.5 on the inside of one of the homes in Arrowtown (the pink line), outdoor PM2.5 (the blue line) from the nearest ODIN to this house and and also the outdoor temperature (the green line) from the ODIN. PM2.5 levels raise both in and out when it gets colder.

This is because they start to light their fires. PM2.5 levels inside their homes are lower than PM2.5 outside overall, however, there are times when they are higher inside than outside.