You cannot really become ill from an airbrush tattoo. The risks are really nonexistent. With a permanent tattoo, however, the risks run high. You could end up with infections, irritations and illnesses. An airbrush tattoo cannot cause these irritations because your skin is not being penetrated with a needle.
With an airbrush tattoo you could always change your mind. If you do not like something you are not committed to it. It will wash off in a few days, a week at most. You could use an air brush tattoo to trial what you want to commit to and see if that is what you really want on your body for the