Tanning through a window?

During my lunch, I sometimes sit in the windows of the skywalk. It's a quiet break from the noise and hustle and bustle of the lab. I enjoy people watching and have had quite a few conversations with people passing by. Strike that! Now that I think of it, I have only conversed with elderly men!?!?!!! Anyway, that's not the point of this blog entry! One of the main reasons I sit there is because I enjoy the warmth of the sun on my face. It is the perfect spot to bask in its glow, especially during the winter.

It is quite funny to me, but MANY people say, "Don't get sunburned!" as they pass by. I usually smile and give a little laugh, but I wish I could just say to them, "Believe me, if you could get sunburned through glass I would be as red as a lobster right now."

When they keep on walking, I truly wonder, 'Do they really think you can get sunburned through glass or are they just being polite and/or funny and trying to make small talk with the strange girl sitting in the window?'

Here are some of the answers I found:

From: http://www.theweatherprediction.com/habyhints/219/

A window acts like a sunscreen. It does not block all the UV radiation but it does block the most dangerous wavelengths of UV radiation. Glass absorbs short wavelength ultraviolet light, but it does pass 350 to 400 nanometer ultraviolets. While this longer wavelength ultraviolet is less harmful than the shorter wavelength variety, you can still tan or burn if you get enough exposure. You will burn much more quickly when driving with the windows down and exposed to the sun as compared to driving with the windows up and exposed to the sun.

From: http://answers.yahoo.com/question/index?qid=20080507082448AAmKxNq

It depends on the window... some windows are pure glass (although very few are), and some are treated or tinted (which will filter out more UV than non-treated windows).

Non-treated glass will filter out some UV light (compared to not having it there), so it will take longer to tan vs being outside in open sunlight... but not much more. UV treated glass will filter out much more light, but some small amount of UV light can still get through (very minimal... like it would take hours upon hours to get a tan).

Some people are surprised to find this out, but standard windows (like those in your home) are UV treated to minimize the UV-B rays, which your body uses to produce Vitamin D. That's one of a few reasons that many shut-ins who can't go outside are more likely to be depressed and may have more problems with their bones (because Vitamin D impacts the absorption of Calcium and has an impact on the mood).

So, I have to admit, I am surprised that some UV radiation can get through. I thought windows were a complete protection. I am still going to sit there because I have NOT gotten tan or sunburned in over a year of doing so. Everyone can attest that I GLOW white! ;)