SPF, UVA and UVB – what do they mean and why should I care?

The sun emits three types of ultraviolet (UV) rays:  A, B and C.  UVC waves are reflected back by the ozone layer and never get to earth, so only our astronauts need to worry about them.  UVB are short wave length rays responsible for most sunburn and they have been directly linked to various forms of skin cancer. UVB rays reach us in different strengths depending on the sun’s location and can be deflected by clouds. This is why you are more likely to get a sunburn in July than in January and n a sunny day than during a rain storm.

UVA are long wave length rays.  While less likely to cause sunburn, they penetrate the skin more deeply and promote wrinkling and leathering of the skin.  Recent studies have shown that UVA may also induce some forms of skin cancer.  UVA rays are the same strength year round and are not deflected by clouds.  Also note that there is no uniform measure of UVA absorption. There are broad-spectrum sunscreens that protect against both UVA and UVB radiation, but it is important to remember that the SPF rating does not predict UVA protection, only UVB.

So how can you protect yourself when going out on a hike or preparing for the next trail maintenance session?

• Select a broad spectrum sunscreen with an SPF of at least 15.
• Look for oxybenzone, sulisobenzone, avobenzone (Parsol 1789), ecamsule, titanium dioxide, mexoryl, or zinc oxide on the ingredient labels.
• Look for sunscreens that are water resistant. (Sunscreens can no longer be labeled "waterproof" because none are.)
• Apply sunscreen 15-30 minutes BEFORE you start working in the sun.
• Apply sunscreen frequently (every 2 hours) and liberally
• Wear tightly woven clothing and a hat with a wide brim.
• Consider purchasing some of the new sun protection clothing, especially a shirt.
• Avoid that time of day when the sun is strongest – 10 am to 4 pm.

So cover up and have fun, but most of all - let’s be careful out there.