Do air purifiers work?

I have had serious chest problems, reoccurring chest infections, I'm taking lungwort daily (what even is this?!) and thought an air purifier would help? What do people think? Is it worth it? So far it just sounds like I've got a fan on all night. Any other suggestions gladly welcomed to help with a terribly weak chest! (Asthma assessments came back no asthma) TIA