Frostbite And Can't Lower Humidity In Coop

[LawnOfficer]

Hi, we have 7 Red Star hens and lately 3 of them have frostbite on their combs, one pretty severe. We've been doing the Neosporin (non-pain reliever) treatment every day. I've read that high humidity in coops can cause this, but so far we haven't been able to reduce the coop's humidity. It's been running the same as the outdoor air, which has been around 70-80%.

Is there any way to lower the humidity inside the coop lower than outside air?

Dean