We have cold air returns in most rooms of the house. Interestingly, not the kitchen.
I have two Goldens that keep me company most days. They belong to a neighbor. It is a mutually beneficial situation.
However, middle and I both have asthma and assorted people have dog allergies. And I did not want dog dander pulled into the duct work of the house.
So our heating/air conditioning guys came and put filters on the three cold air returns that are exposed to dogs. We keep all the bedroom doors in the house shut when the dogs are here.
The cold air returns (with filter added) are in the living room, top of stairs, my sewing room. So these are in the “main” areas of the house.
Purpose of filter - to keep dog hair out of the duct work. The dog is only in the kitchen, hall, living room.
When the service man came to clean/check air conditioner, this past week, he took out the filters and had me wash them with the hose in the kitchen sink. Then he put them back. Interestingly, the cold air duct at the top of the stairs, is always the dirtiest, it must pull from downstairs kitchen. We do not have a cold air return in the kitchen/hall.
We are going to do the same thing in the late fall when he comes to check the furnace.
And we have two tower filters in my bedroom. And two tower filters in the other downstairs bedroom. There is also one in the living room. These are good quality tower filters from Target with permanent/washable filters.