Have you had any luck with air purifiers?

I’m thinking of purchasing an air purifier to combat a possible mold allergy. Do you use an air purifier for a similar purpose?

When I start using a purifier, how long might it take for me to notice a difference? Should I put the purifier in the room with the mold or in the room where I spend 95% of my time? Should I leave it on all day and all night or just when I’m in the room?

Money is not really an issue. I’m desperate.

Thanks for the input!