You both make good points. I would be interested in knowing some examples of "valid" medical conditions for not wearing a mask.. As for the service animals, other than allergies how could they adversely affect other passengers? As for as exemptions for wearing mask I would want a doctor's note. I would also want the airline to run a test for coronavirus. People allergic to an animal could be moved as far as possible from the animal or the animal could be moved. I don't think moving a person without a mask would work unless the plane was lightly loaded and they could be moved much more than the 6 foot minimum. I also realize the air circulation system of the aircraft plays a role in this. I think we need to have Solomon make a judgement on this one.