Does it have any effect on tanning skin?
There was a question on the Straight dope main page recently discussing this although it wasn’t Cecil who answered. Do a search for it.
Although I felt the answer had some mis-information in it about the ability of certain wavelengths to penetrate glass, it was a reasonable answer.
Summarized: Yes, glass blocks most of UV light. The longer wavelengths (near blue light) get through better than the shorter wavelengths. The shorter ones are the ones that burn your skin so it should be very difficult to sunburn through glass. The part about the answer on the SD main page was saying the light that causes tanning do get through. I’m not convinced that you can really say one wavelength causes burning and another causes tanning, and the longer wavelengths that do get through are still greatly attenuated so my thought is that it should be difficult to tan through glass also.
Welcome to the SDMB, Headcoat.
Cecil’s column: Can you tan through glass?
Oh, and as an afterthought, this thread from Comments on Cecil’s Columns:
Re: tanning and burning through glass