Vein: A blood vessel that carries blood that is low in oxygen content from the body back t... See the entire definition of Vein Viral: Of or pertaining to a virus.
This means that breathing low concentrations of freon from a leaking refrigerator or air conditioner over a long period of time is unlikely to have a cumulative effect, and thus few, if any, long term health effects.
Most Air Conditioning Companies use either electronic leak scanners or a flourescent dye system, which pinpoints freon leaks with a dye. When the temperature outside is extremely cold, my outdoor Heat Pump makes strange noises and I see smoke rising from the unit.