Flea bombs and chickens?

[aklab]

Hey! I have a flea infestation in the crawlspace under my house -- not in the house. I'd like to use a few flea bombs/foggers under the house. My chicken coop is about 20 feet away from the house. Do you think that's far enough to avoid any of the fog blowing over and hurting them? Any measures I can take to minimize their exposure?

 

[aklab]

PS: I am aware of other treatments like diatomaceous earth. Currently I'm recovering from a back injury so crawling around spreading that isn't really an option.