Kitchen Table Medicine: The Naturopathic Management of Asthma
Recommends removing shoes to avoid bringing in pollen and pollutants. A blogger has testified to me before that this really does make a big difference.
This blog recommends that you adopt a shoes-off policy in your home, not just for family but also for guests and other visitors. Socks, slippers and bare feet are fine indoors, but not shoes. Just say NO to shoes in your house!