In this article I want to take a look at the various different categories of sunglasses that are available in the market today. First of, I should state that the title of this article is a little misleading, not intentionally 🙂 I hasten to add, as the standards I will reference are applicable to sunglasses in general, not hiking ones specifically as I indicate in the title.
In many cases, the whole gambit of eye wear comes into play, so things like impact resistance and so on, not just sun protection can come into play in the ratings.
First off, I should state that there is currently no one universally accepted method to categorize sunglasses. There are a few different ones used, one in Europe, one in the US and one in Australia.
Some Personal Historical Context
My first encounter with this was on my trip to climb Mont Blanc. I had never really paid much attention to sunglasses before, I didn't really need anything too special for most of my hiking. I had a decent pair of sports sunglasses that did the trick whenever it was sunny. Going to Mont Blanc though, there was a new issue to consider. That issue was snow blindness.
For those who don't know, when you spend a lot of time on snowy mountains / glaciers at high altitudes, the UV that reflects off the snow can cause snow blindness. To prevent that, you need a certain strength of sunglasses to ensure you are protected.
This was new to me at the time, I bought a pair of category 3 sunglasses in preparation for the trip but as it turned out, after chatting with a guide in Chamonix, he recommended that although the category 3 would probably be OK, I would be better to get a category 4 pair (The highest level) just to be safe, which I of course did.
This was all new to me at the time so, aside from the obvious protection it would provide, it was good to learn about it. So, with the storytelling complete 🙂 let's take a closer look at this. I should add that while I have a pretty good idea about the differing standards, I can't claim to be a sunglasses expert so if I have missed anything or list something inaccurately, please do let me know in the comments. I want this to be a useful resource for people so want to ensure I have all the facts correct.
OK ... soooo ....
Probably the one I am most familiar with and one that is pretty easy to understand, is the European standard. This has has 5 categories which are required to be marked on the frame. These along with their related explanations are listed in the table below.
80%-100% transmission - for fashion, indoor use, or cloudy days
43%-80% transmission - low sun exposure
18%-43% transmission - medium sun exposure
8%-18% transmission - strong brightness, light reflected of water or snow
3%-8% transmission - intense sunshine for high mountains, glaciers; not for use when driving, road use
Sunglasses sold in the United States are regulated by the Food and Drug Administration. Sun (and safety) glasses have to conform to safety standard ANSI (American National Standards Institute) Z87.1. This standard also requires that certain ratings are indicated on the sunglasses. As mentioned, this also covers safety glasses as well, not just sunglasses. The ratings are listed below.
Impact: “Z87+” indicates high-velocity impact, and “Z87” alone means basic impact
D3 / D4
Splash and droplet: D3 for splash and droplet and D4 for dust
Welding plus the shade number
UV plus the scale number
Infrared Light plus the scale number
Visible Light Filter plus the scale number
Prescription on the front of the frame and both temples
Head Size - indicates products designed for smaller head sizes
For special lens tint
The Australian Standard is AS/NZS 1067:2003 for sunglasses and fashion spectacles. Similar to Europe, they utilize five ratings for transmittance, running from 0 to 4, with "0" providing some protection from UV radiation and sun glare, and "4" indicating a high level of protection. As an aside, Australia introduced the first national standard back in 1971. The categories are listed in the table below.
Fashion spectacles - not sunglasses, very low sunglare reduction, some UV protection
Fashion spectacles - not sunglasses, limited sunglare reduction, some UV protection, not suitable for driving at night
Sunglasses, medium sunglare reduction, good UV protection
Sunglasses, high sunglare reduction, good UV protection
Sunglasses - special purpose, very high sunglare reduction, good UV protection, must not be used for driving
What is Best to Use for Hiking?
I think for hiking, you should aim for a category 3 or 4 in Europe Australia and something with a high UV rating in US, 400 is a good number to aim for so 'UV 400'. You may not need this level of protection all the time but the way I see it, you might as well get the most you can in one pair of glasses and then you can use them in any conditions anywhere while out on the trail.
Granted, a higher UV rating might be too much for areas where you don't need as much protection, so having a category 3 and a category 4 pair can be useful so you're covered and comfortable wherever you hike. As mentioned, I have both and mainly use the category 3 pair but the category 4 ones are fine for my normal hiking too.
Remember, if unsure, it is always good to check in a store where they will likely only be too happy to help make the right choice for your needs.
So, that's it for now. As mentioned at the start, I am hoping this will be a useful resource for people and the information within comes from my personal experience as well as some research. However, things change and standards are always being updated. With that in mind, it can be a good idea to check the standard with the relevant government website for any updates, just Google the standard name and a .gov site link will likely pop up.
I should also add that it is possible that there is another widely used standard that I don't list here, for example, maybe one that is utilized in Asia. However, I am not aware of anything specific for Asian countries like Japan, China, etc. If I do come across any other ones, I will update this article with them.
Sunglasses for the trail are a good investment. Whether it be a hot Summers day on arid terrain with the sun splitting the sky, or a trek on an Alpine adventure over glaciers, you should always remember to protect your eyes appropriately. They're a highly sensitive part of your body and so need to be protected.
I hope you found this useful, please like and share if you did 🙂