I asked about this in the NorCal thread last week, and consensus seemed to be that there's not much we can do. I haven't checked the Bay Area thread, but maybe it's come up there...? I've been misting their run occasionally, and I hose their coop out regularly (it's plastic), but I have no idea if that actually does much to help. I've been replacing their water more frequently (ash and gross stuff gets on it quickly). I also haven't let my kids in to interact with them, as it tends to get the chickens excited - I'd rather they stayed mellow and relaxed. (Most of the day, they lay low in the dust baths they've dug out. I figure the air is probably best down there, anyway.) I feel pretty helpless to make things better for them, but I am thankful we're safe. Good luck!