Spring is Here: Get Out the Sunscreen

Spring is in the air, and a young man's fancy turns to... sunscreen. That's only if he wants to guard against melanoma, squamous cell carcinoma, wrinkles and sagging skin.

There is a lot of misunderstanding about sunscreen, which has not been helped by FDA regulations changing the way their effectiveness is tracked and labeled in recent years.

First, what is sunscreen protecting us from, exactly?

The spectrum of light sunlight which burns our skin and puts us at a higher risk for cancer is invisible, residing in the ultraviolet (UV) neighborhood. That neighborhood is parceled out into numerous sub-spectra, but it is the two with the shortest wavelengths, UVA and UVB, with which sunscreen concerns itself.

The SPF (sun protection factor) rating found on your sunscreen is a relative measure of how long a sunscreen will protect you from UVB rays. These are the ones that damage the epidermis and cause sunburn and erythema.

We all sort of know that a higher SPF rating is better than a low one, but what exactly does that SPF number measure? Short for “sun protection factor,” it is a measure of the fraction of ultraviolet rays that will reach your skin. But is a sunscreen with a SPF rating of 30 twice as good as the one rated 15?

No. SPF 15 filters about 93 percent of all UVB rays, whereas SPF 30 blocks out 97 percent. SPF 50 is an almost complete UVB block, at 98 percent. No sunscreen blocks out absolutely all UVB, and also that it takes small increases in the percentage blocking power to have relatively large effects against the level of harmful exposure.

But what about the UVA rays? These have a longer wavelength than the UVB, and they reach down into your skin's dermal layer. UVA rays are responsible for photoaging of the skin and some of the cancer risk.

The SPF rating on your sun screen only indicates the level of protection against UVB rays. To ensure you are also guarded against UVA beams, make sure that is labeled as “broad spectrum" protection. In Europe, “UVA” appearing in a circle on the label indicates protection against that part of the spectrum.

Remember that no sunscreen blocks out all UV, and all products need regular reapplication, at least every 2 hours. Sunscreen does not protect against all exposure to UV, and different environmental conditions affect the intensity of the radiation

Even with the use of sunscreen, our advice is to avoid going out into the high sun in summer around the middle of the day when UV intensity can be extreme.