Tips for horse allergy sufferers? Wrapped hay? Hay disinfection? Dust-free flooring?

Hello, my dears, Unfortunately, my horse developed mild equine asthma this winter due to poor-quality hay. To keep things mild, I'm going to change his housing for the winter (he's currently in pasture and has no problems) and feed him himself. I have done a lot of research and am looking for experiences! Feeding: Since…