Yeah, it's obviously not fool proof and I wouldn't personally trust my life or my family's life to it, but you are "safer" outside than inside. Although I don't think there has been any serious study of how much the risk is reduced by being outside. But, as buzd suggested that's probably only true when people aren't close together at things like rally or concert. Once you get close together, there is not time or space for the virus to be killed by the UV or for the virus to dissipate in the air.