Air Purifiers

We live in a cozy suburban home with two domestic short hair cats, and two dogs,(a teacup chihuahua and a beagle/hound mix). The cats are strictly indoors and the dogs only go outside to potty and for walks. We keep all of our pets clean and they are all well taken care of but the shedding and pet dander are becoming a concern of mine because they are irritating my allergies a little. We regularly vacuum but seeing as it’s too cold outside to leave the windows open to help keep the house aired out I was wondering the best way to keep the air in the house and everything in it fresh from pet dander and odors. Are there any sprays or cleaners? And would an air purifier or something like that help?

My boyfriend has bad allergies and terrible asthama. My roommate has a dog and cat so I think it’s mostly pet dander that ends up bothering him in my room, even though i keep the door closed all day. Does anyone know of a good air purifier that is relatively cheap but good for asthama? I know i have to find one with HEPA, but I’m wanting to spend maximum 150. Thanks all!

I am wanting to purchase an air purifier for my apartment, which is approximately 700 square feet. I am wanting to eliminate light cigarette odor, pollen, dust, and perhaps pet dander in the future.

What should I look for when purchasing a purifier? Are their particular brands, features, styles, designs, etc, that I should look for?

Any product recommendations? I am looking for a price range of -0 (USD)

Thanks for the advice!