Can you get tan through a window?

I swear I’ve gotten tan through my car window, but a friend says this is impossible. Google search has turned up conflicting results, so what is the straight dope on this?

I totally believe it. I have been sunburned through a car window.

I don’t see why it wouldn’t be possible; I think you’re still being exposed to ultraviolet light radiation, right? Even if not directly.

Glass blocks UVB light but not UVA. So you can get burned.

Glass will block UVB radiation but not UVA unless it has been treated to do so (like in a car’s windshield sometimes).

So yes you can get tan through glass unless it’s been treated to block UVA radiation.

I used to have a loft with a big southern exposure window. I used to tan there all of the time. Quite possible.

Cecil wrote a article on this:

The answer is yes you can, but it aint easy.

Truck driver tan is a real thing.

28 years on the road. The left side of his face has obvious skin damage.

There was a thread on this recently.
The upshot was: standard window glass transmits about 50% of the nearest-UV portion of the spectrum. I don’t know how much total UVA energy is present in this small slice, but it’s probably less than 20%, so the SPF of a piece of glass is somewhere in the the SPF 5-10 range.

Cecil’s article is similar to the Myth Busters article my friend provided, which stated that it’s possible to get tanned or burned through a window, but highly unlikely. That is totally inconsistent with my experience however.

It’s possible that I’m just extra sun sensitive though…