Peater Piper
Member
- Joined
- Mar 18, 2016
- Messages
- 817
I'm unable to find one study I previously read where they measured UV rays in a location where the sky was visible overhead, but a wall was providing shade. UVA rays were reduced in the shade far more than UVB rays, presumably because UVB is more prone to scattering when hitting aerosols. In short, vitamin D synthesis would have been nearly as high as in direct sunlight, and UVA exposure would have been reduced. I did find this study, which shows vitamin D synthesis is possible in a number of shaded scenarios: Vitamin D effective ultraviolet wavelengths due to scattering in shade - PubMedAlways the studies are about direct sun exposure, and never about indirect sun exposure.