What Does UV400 Mean? Sunglasses UV Protection Explained

Look at the tag on almost any pair of sunglasses and you'll see "UV400" or "100% UV protection". It's the most important line on the label, and the most misunderstood. Here's what it means in plain English.

What UV light is

Ultraviolet (UV) light is the part of sunlight you can't see. It's measured in nanometres (nm), and two kinds reach the ground:

• UVB (about 280 to 315 nm) is the one that burns your skin. It's strongest in the middle of the day and in summer.
• UVA (about 315 to 400 nm) goes deeper and is around all year, even on cloudy days.

A third kind, UVC, is absorbed by the atmosphere and doesn't reach us.

What UV400 means

A UV400 lens blocks light with wavelengths up to 400 nm. UVA and UVB both sit below 400 nm, so a UV400 lens blocks both of them. That's why "UV400" and "100% UV protection" mean the same thing on a label.

Dark lenses are not the same as UV protection

How dark a lens is has nothing to do with how much UV it blocks. A cheap pair with very dark lenses and no UV filter can be worse than wearing nothing at all, because dark lenses make your pupils open wider and let more UV into your eyes. A lighter lens with UV400 protection is much safer than a dark lens without it.

Polarisation is a separate feature too. Polarised lenses reduce glare, but they only protect against UV if they also have a UV filter. Read more about polarised lenses.

Why it matters so much in South Africa

South Africa gets a lot of UV. On clear summer days, the UV index on the Highveld, including Johannesburg and Pretoria, often reaches 11 or higher, which is classed as extreme. Coastal cities like Cape Town and Durban regularly reach very high levels too. A few things push your exposure up even further:

• Altitude. UV gets stronger the higher you go, and much of the country sits well above sea level.
• Reflection. Sand, water and light-coloured paving bounce UV back up towards your eyes.
• Cloud. Thin cloud lets a lot of UV through, so an overcast day can still burn.

Long-term UV exposure is linked to eye problems such as cataracts, so protecting your eyes is a habit worth starting early.

How to check your sunglasses

• Look for "UV400" or "100% UVA/UVB protection" on the label, the product page or the inside of the arm.
• Be wary of unbranded pairs that make no UV claim at all.
• Replace pairs with badly scratched or damaged lenses. Here are 5 signs it's time.

Ombrox and UV protection

Every Ombrox pair has polarised lenses, and styles like Noir, Aurora, Horizon and Summit are rated for 100% UV protection. Shop the range.