My grandmother raised chickens all her life, this was her only income. She never wore a mask. Neither did anyone else way back when. I've been around chickens all my life, and I don't wear a mask either. I, like my grandmother have a large walk in coop with excellent ventilation. She also taught me to keep a coop meticulously clean. She said we wouldn't want to live in tiny poop filled boxes, so don't keep your animals in those conditions either. Most sites state that this is a rare condition, so why worry? Keep everything clean, open and airy.Since I've been reading this other thread, does anyone who keeps house chickens ever worry about this? https://www.backyardchickens.com/th...ty-pneumonitis-bird-keepers-lung-flu.1352878/