Ohio is slowly adapting to requirement of Air Gaps on dishwashers. I can only speak for the some of the counties in southern ohio. I just moonlight over there but a supply house in clermont county told me that they have to supply air gaps as they are required.
Prevent Contamination. Proper protection shall be provided to prevent contamination of food, water, sterile goods, and similar materials by backflow of sewage. When necessary, the fixtures, device, or appliance shall be connected indirectly with the building drainage system.