SPF, UVB, UVA. These terms are usually associated with suntan lotions and thoughts of hot lazy days spent on a beach. We all know we should be applying some form of sun protection before we get on with our day. But how many of you apply an SPF moisturizer or SPF make up in the morning without giving a second thought to whether or not it’s actually giving you protection from the sun’s harmful rays? Do you actually know which SPF number is right for you?

A Little Knowledge Is A Powerful Defense About  SPF Moisturizers & Make-up

The spectrum of UV rays that pass through our ozone to reach our skin are UVA and UVB rays.

UVA rays are a longer wavelength ray and make up 95% of the UV spectrum. They are present all year long and can pass through cloud cover and windows. UVA overexposure won’t show up as a tan or burn, so we will not know in the short term if we have received too much UVA. The danger? UVA rays can significantly damage your collagen and elastin giving you wrinkles, skin laxity and a leathery appearance over time. UVA rays are also associated with the development of melanoma.

UVB rays make up 5% of the UV spectrum of rays that pass through our ozone and impact our skin. These short wave length rays are responsible for giving us freckles, tans and burns. The intensity of the UVB rays vary significantly with the seasons and the time of day. This explains why we don’t tend to burn on a cold, sunny November day. UVB rays significantly age the skin and are highly associated with the development of all skin cancers.

SPF (Sun Protection Factor): This is a determination of how protective a sunscreen is against harmful UVB rays. An SPF number itself is simply a laboratory measurement. The important thing to realize is that the amount you use – a liberal tablespoon of sunscreen applied to the face is what is able to give you this protection. If you put a scant layer of it on your skin, you will have a false sense of assurance, meaning that you are still being exposed to potential damaging rays. If you have an SPF of 15 in your moisturizer or in your makeup, be aware. In all likelihood, you don’t apply a tablespoon of it on your face, so you probably aren’t getting the protection you think you have. In addition, many skin products claiming to offer SPF protection do not cover for UVA rays and as mentioned earlier, UVA constitutes 95% of the harmful rays that impact your skin.

 How To Calculate Your SPF Needs

If you are fair-skinned and burn after 10 minutes of unprotected sun exposure, an SPF of 15 would give you 15X the duration of protection (10 X 15 = 150 minutes) at approximately 90-95% efficacy. But here’s where things get confusing. When the SPF number goes up, let’s use SPF 30 for example, you will not receive 10 X 30 = 300 minutes of protection. Its effectiveness is higher than 95% but the sunscreen still needs to be reapplied every 2 hours if you are sweating, swimming or staying in full sun. A higher SPF means greater efficacy only – you still need to apply it liberally and often or suffer the consequences of diminishing returns.

My thoughts are that most of us will do fine with an SPF in the range of 30 – 45. The secret lies in ensuring that it offers a broad-spectrum SPF that protects for both UVA as well as UVB rays such as this one that we recommend to patients at The vanVliet Clinic. To make sure that your products contain UVA coverage, look for titanium dioxide, zinc or iron oxides on the product’s ingredient list to know that you are protecting against the full spectrum of harmful UV rays. And don’t forget to reapply every 2 hours, no matter what the SPF number is. If you want further proof of the type of harm that can be done by tanning, read this article about identical twins Jeanne and Susan. In the meantime, pictures speak louder than words!