answer:Even on cloudy days, your skin can pick up UV outdoors…at least that’s what I’ve always been told. That’s why people say to wear sunscreen even when it is cloudy. Also, if you sit next to a window indoors, some of the rays even with high performance windows are getting through. I just recently read somewhere that it is possible to get skin cancer from sitting in an office next to a window every day without sunscreen on. Obviously other factors are involved, but the point is just that UV rays make it through windows. Not sure how much exposure you are getting in either scenario or how it compares to how much you need on a daily basis. I just try to spend as much time outdoors as possible. I would absolutely not want to sit under any kind of lamp, but that’s just me.