Assuming simple conditions e.g. sunny, bright day (no clouds), sun is directly overhead, what becomes the effective UV index for someone who is outdoors under solid shade (e.g. sitting under a concrete roof on the patio outside, not under a tree/umbrella that leaks light through)?
I'm not looking for an exact answer since I would assume that it depends on many complicated things such as the type of ground/surface in the surrounding area and how far does the concrete extend beyond that person, etc..
Only reflected UV rays would hit you from the sides in that case, but an estimated how much?