I don't think the misting itself will cause an RI. It is more the environment being damp, and wet at all times and never drying out. We have these animals confined to small areas and even though they are ventilated, there are still mold and bacteria that can be produced if given the right elements. How often and how long are you misting? Is your chameleon is screen or glass? Does you cage have a chance to dry out, especially at night?