# UV rays through glass

**URL:** <https://boards.straightdope.com/t/uv-rays-through-glass/113093>\
**Category:** Factual Questions\
**Created:** [June 9, 2002, 12:17pm UTC](https://boards.straightdope.com/t/uv-rays-through-glass/113093 "2002-06-09T12:17:01Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![istara](https://avatars.discourse-cdn.com/v4/letter/i/e79b87/32.png) [@istara](https://boards.straightdope.com/u/istara)\
**Post date:** [June 9, 2002, 12:17pm UTC](https://boards.straightdope.com/t/uv-rays-through-glass/113093/1 "2002-06-09T12:17:01Z")

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Just a quick query about ultra-violet-rays-through-glass.

I had understood that one couldn’t “burn” through a window, because (normal) glass filtered out the UV rays. Likewise through a plastic window.

However when you buy sunglasses, more expensive ones come with UVA/UVB filter stickers, highlighting their greater protection.

So what comes through glass and what doesn’t come through glass, what is actually damaging or not, and why would you need a special type of glass or plastic for your sunshades to block UV?

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**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\
**Post date:** [June 9, 2002, 12:23pm UTC](https://boards.straightdope.com/t/uv-rays-through-glass/113093/2 "2002-06-09T12:23:29Z")

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from [http://www.sciencenet.org.uk/database/Physics/9812/p01347d.html](http://www.sciencenet.org.uk/database/Physics/9812/p01347d.html)

```
"Normal glass (as used in windows) is transparent to UV radiation up to a wavelength of about 330nm (or UV-A light). The transparency is quite high so almost all UV-A light will pass through glass. Beyond 330nm (UV-B and UV-C) almost 100% is stopped. "

```

note that UV-A is still dangerous!

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**Author:** ![manhattan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manhattan/32/7_2.png) [@manhattan](https://boards.straightdope.com/u/manhattan)\
**Post date:** [June 9, 2002, 7:07pm UTC](https://boards.straightdope.com/t/uv-rays-through-glass/113093/3 "2002-06-09T19:07:12Z")

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**Cecil Adams** on [which UV does and does not pass through glass](http://www.straightdope.com/classics/a1_163b.html) .