Quote Originally Posted by kuri
bobbong, yes i actually have received many sunburns and tans with my windows rolled up all the way even with my sun room closed, my shoulders got burned.
You need to be in the sun for a prolonged period of time to get a suntan/burn through glass.
I found this article.
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QUESTION: At a recent summer party, someone asked if you can get a suntan or sunburn in a car with the windows up. We were evenly divided on the issue.

What's the answer?

ANSWER: In a way, you're all right. Most glass, in cars or houses, blocks the kind of sunlight, called ultraviolet B, or UVB, that causes sunburns, said Dr. Robert Stern, chief of dermatology at Boston's Beth Israel Deaconess Medical Center. So you're unlikely to get truly burned through the window.

But glass does let in ultraviolet A, or UVA, light, which can cause suntans, though very slowly.

And both UVA and UVB can cause skin cancer and skin aging, so you can be damaging your skin even through sunlight filtered through a window if you have long exposures, cautioned Dr. Thomas Ruenger, a dermatologist at Boston University School of Medicine. Exact thresholds for risky exposures have not been defined, but the longer the exposure (think truck drivers), the greater the risk.
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