What does the SPF number stand for?
SPF stands for Sun Protection Factor. The number of SPF is determined by measuring how quickly it takes a subject to get burnt by UV rays without sunscreen. Then, testers redo the test with sunscreen. The “with sunscreen” number is divided by the “without sunscreen” number, which determines the SPF. The equation boils down to:
Minutes to burn without sunscreen x SPF number = maximum sun exposure time
So, for example, if you use a sunscreen with an SPF 15, you can be in the sun 15 times longer that you could without sunscreen before burning. If this is too much math for you, just stick with a sunscreen that has a minimum of SPF 30 and reapply it every 2 hours. Remember that SPF number sunscreens over 50 can give you a false sense of protection--they still need to be reapplied frequently in order to be effective.
What’s the difference between UVA and UVB rays? UVA rays are less likely to cause sunburn, but they penetrate your skin more deeply. These rays can go through windows, lightweight clothing and windshields. Prolonged exposure to UVA rays damages the collagen and elastin in your skin which causes wrinkles. UVB rays are responsible for tanning and sunburn. They also cause skin cancer. What you need to know is that both UVA and UVB rays can be extremely damaging to your skin. You need a sunscreen that protects you from BOTH of types of rays. [POPSUGAR Fitness]
What does “broad spectrum” mean?
If a sunscreen is labeled “broad spectrum” it means that it protects against both UVA and UVB rays (check out the previous slide to learn the difference). Not all products protect against both types of rays. Since UVA and UVB are dangerous in different ways, it is very important to use a broad spectrum sunscreen, like MD Solar Sciences Mineral Creme Broad Spectrum ($30).
Is there a difference between sunscreen and sunblock?
Yes, but both are effective forms of sun protection. The main difference is that sunscreens are chemical and contain special ingredients that act as filters and reduce ultraviolet radiation penetration to the skin. These are often colorless and create a thin invisible film on the skin. Sunblocks are physical sun protection and contain ingredients such as titanium dioxide and zinc oxide which physically block ultraviolet radiation. Basically:
Sunscreen = Colorless
Sunblock = Opaque
When should I apply sunscreen & how often should I reapply?Sunscreen should be applied to dry skin 15-30 minutes before going outside. Reapplication is extremely important. In order for the sunscreen to be effective, you should reapply it about every 2 hours or after swimming or sweating heavily.
There are so many different types of sunscreen: which type is best? Sunscreens come in a ton of different forms: lotions, creams, sprays, gels and wax sticks. The type of sunscreen you choose is mostly a matter of personal preference. Just make sure the type you use offers broad spectrum protection and is “water resistant” or “water proof.”(The FDA considers a product "water-resistant" if it maintains its SPF level after 40 minutes of water exposure. A product is considered "waterproof" if it maintains its SPF level following 80 minutes of water exposure.)
How long does it take to get a sunburn?
This answer depends entirely on who’s asking it. It also depends on the time of day. It takes about 10 minutes for a person with fair to light skin to get sunburned, while it takes 20 minutes for a person with tan to dark skin to get burned. But if you are outside between the hours of 10am and 4pm, you’ll burn faster because the sun's rays are stronger between those hours. Your age and diet can also be factors. As a safe bet, always wear sunscreen if you plan on being in the sun for more than a few minutes.
My makeup has SPF, is that enough?
Makeup does not provide enough coverage, especially because most people apply their foundation sparingly. Plus, if you use a regular non-SPF moisturizer on your face and then apply a foundation with an SPF over it, the sunscreen in the makeup has a difficult time penetrating through the moisturizer and it won’t be as effective. Try using a moisturizer with sunscreen and then applying your foundation with SPF.