Hear my idea:

First we pollute the air enough to be almost unbreathable (as a side gig, we get to burn oil, coal steel...)

Then we make special facilities to filter said pollution from air before said air enters the house.

Then we sell these house for a premium with grade AAA+++ the best air quality ever.

Now, what to do with the defective filters?

Put in a house with grade B+ air quality.

Grade C will be the houses that get the air that was exhausted from AAA+++ and B+ (after being breathed a few times and with no filtering).

Grade F is the good old coal air that the people who can't pay will have to breath as they work in the coal burning facilities.