Q: How do I know which safety glasses protect from UV light and to what level?

This is a good question and one that causes confusion. Protection from UV light is important because we can’t see it and it damages our eyes. It is the same light that burns our skin. The EN European Regulations have a code EN170 which says the glasses have UV filtration but that is about it. As you can see from the image of the lens here, it first says 2C-1.2. That 2C means it is compliant with EN170. But what does that mean? Is that 100% UV or just some of it?

EN170 doesn’t go far enough to tell you this but generally EN170 means it will block UVA and UVB light. That is from 280nm to 300nm of light in terms of wavelength. See the chart below. But hold on! What about UVC. Well UVC is even more damaging to us but thankfully most UVC is filter out by the atmosphere so you do not get much reaching our eyes.

But I need more protection?

If you feel that you want more protection then or are working in artificial light that produces UVC rays then you’re not going to be protected by glasses even if they say they are EN170 compliant. However, there are some models that give additional protection. These two below for example will give UVC protection all the way down to 190nm. That is well into UVC territory. If using these glasses you must ensure that the light your are working with does not go below 190nm or to be safe, ideally not below 200nm.