Too Sanitary?

DH keeps bugging me and I totally wish he would knock it off. He's been looking at air filters for his car and then he starts talking about getting a thing for the house to keep the dust and other icky things in the air down. I don't mind at all but sometimes i wonder that if you over purify everything that you may become vulnerable to a lot more than before because of the lack of exposure. The dust and stuff is bad though and with hardwood floors it just lfies around all over the place.