Sounds like some mixed messages here on this thread but I've been using the hydrated lime in my coop for years and in my cattle barns even longer with no ill effect. I use it on the floor of my coop at every big cleanout prior to putting down the wood shavings (I use the deep shaving method) I don't put it on top because as an airborne dust, it can be a lung irritant. If you're using to to dry up the litter, you probably actually need more ventilation. I also use it to make whitewash which I use to paint the whole inside of the coop and all roosts. This has been my primary pest control for mites and lice as well as being a great coop disinfectant.