Sunscreen Basics
This week I wanted to touch on one of the basic needs of staying healthy through the summer and that is sunscreen. It is no secret that UV radiation has a direct correlation to skin cancer. There are many ways to avoid UV radiation and how far north or south you are also plays a role. One of the easiest ways to protect yourself is with sunscreen. This always begs the question, which one? There are a whole host of different products with different advertising all claiming that their product is superior. This can make it difficult to decide and lead many of us to standing in the aisle, holding two products reading their labels back and forth, not knowing what to look for and ultimately just guessing when you pick and hoping it's the right option. Disclaimer, I am not a dermatologist nor am I an expert in this region of science but I have gleaned a few things from other experts that will hopefully help us make more informed decisions.
There are three different types of UV radiation, UV A, UV B and UV C. They are separated by their different wavelengths. The primary two are UV A and UV B. UV A is responsible for what we know as age related sun changes in skin like skin sagging, and wrinkles. This partially comes from the ability of UV A to penetrate the skin deeper than UV B and affect collagen fibers in the skin. UV A is also associated with melanoma. UV B does not penetrate as deep into the skin and is more related to sunburn effects like redness of the skin, blistering, peeling as well as most forms of skin cancer. SPF stands for sun protection factor and only relates to UV B. It is a measure of how long it takes skin to get red. The number associated with the SPF is how many times longer it took skin to get red with that product. So if the time to red skin was 10 minutes, an SPF 15 would be 15 times longer or 150 minutes. Now SPF isn’t a linear scale, meaning more isn’t necessarily better. SPF 15 blocks about 93% of UV B, SPF 30 blocks about 96%, and SPF 50 blocks about 97%. So a higher SPF does block more UV B but not as much as most people think.
So on to sunscreen. There are two classes of sun screens, physical and chemical. This relates to the barrier that they provide. Physical sunscreens usually use zinc or titanium. These sunscreens have very, very, very small particles in them that create a physical barrier on the skin that reflects the UV radiation away. Chemical sunscreens apply a typically organic carbon based chemical that absorbs in the skin and then when the UV radiation hits it, absorbs the radiation, turns it into heat and disperses it across the skin providing protection. People with sensitive skin typically prefer a physical sunscreen. There have been some concerns about the hormonal disruption that some chemical sunscreens can cause. Although some people prefer chemical because they are thinner, and therefore even easier to apply and are more easily used in a spray-on form than a physical one is.
So now that we know that SPF is related to UV B, what do we look for if we also want to block UV A. There currently is no rating system for UV A, so I look for the words broad spectrum on the sunscreen. If it does not explicitly say that it is broad spectrum, it probably isn’t.
The rule of thumb that I like when shopping for sunscreen is to get a sunscreen that is a physical barrier that says broad spectrum in at least SPF 30. Apply it every two hours. Be cognizant to apply on your hands, face and upper chest even if you are wearing a shirt.
Hopefully this helps cut the amount of time you spend in the aisle, trying to make a decis
