My husband and I moved into a small 2 bedroom house a couple of years ago. The house has a central heat and air unit with vents that are in the ceiling. In the hall between the two bedrooms is an intake vent and we keep the filter changed. My husband is a smoker and smokes in the bedroom and he also passes gas. The system does a good job with keeping the odor out of the bedroom and you can't even tell that someone smokes in the house however, We have two finished rooms in the basement and one room has a return vent. Everything comes back through the return vent. So the basement room always has a stale smoke smell or gas smell. I don't know much about central units. Is this return even in the right place? If so then what can I do to filter this odor to keep it from returning to this room. The room smells bad and the odor gets into everything. Asking my husband to stop smoking or to stop passing gas in his sleep is not an option.

This is one of funny post.
Kick his butt outside.
By a lot of air freshner
By a huge stand alone air cleaner
Sorry but there is no cheap cure for the problem

I see what your talking about now hvac1000.

Look at he HEPA air filter and the single room filters.

Honeywell Air Cleaners |Your Home Expert | Electronic, Media, and HEPA air cleaners and Air Filters. - Honeywell Your Home Expert

Charcoal will remove odors. The HEPA filter will remove small particles.

You might try the filtered window filter here:

Air Cleaners and Purifiers

And place it on the return grill in his room.

Wow, This is strange, can you get the man some beano or something?