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What is sunscreen?
Sunscreen is a type of skin protective preparation that protects your skin from ultraviolet (UV) rays emitted by the sun. There are two types of rays: UVA and UVB. UVA rays are responsible for long term skin damage such as premature skin aging. UVB rays are responsible for sunburn.
What is SPF and what do the numbers mean?
SPF stands for sun protection factor which indicates the effectiveness of ...
the skin protective preparation against UVB rays. Introduced in 1962 are the numbers one notices accompanying the SPF. These numbers (ranging from 2 to 150) multiplied by the minutes to burn without sunscreen determine the maximum amount of time a person can be in the sun without getting burned.
SPF Number x Minutes to Burn Without Sunscreen = Maximum Sun Exposure Time
For example, if you typically burn within 20 minutes of sun exposure and you're using a sun protectant that reads 30 SPF, in theory you should be able to stay in the sun for 600 minutes without getting burned by the sun. Factors to consider that could vary your results are the amount of sunscreen you use, how your body actually reacts to the sun and other environmental factors such as wind & water exposure.
SPF also signifies how much UVB absorption takes place. One would believe that using an SPF 30 over SPF 15 would give the double the protection, right? Quite the contrary. Because the SPF number does not reflect protection at an exponential rate, that is a rapidly increasing rate, the FDA has capped SPF effectiveness to the number 30. In the example above, SPF 15 has a UVB absorption rate of 93.3% while SPF 30 has a UVB absorption rate of 96.7%, for a whopping 3.4% difference.
So what's with the high SPF numbers companies advertise? In theory, they will give you more protection, but the factors to consider listed above still play a major role in the effectiveness of these products.
How does one use sunscreen effectively?
Regardless of where you are headed or what you're doing for the day, it is recommended that you use sunscreen regularly and daily. Even on the cloudiest of days, the sun is out and your body will need to be protected from those UV rays. Apply a generous amount of sunscreen to dry skin 15 to 30 minutes prior to sun exposure. Don't forget your temples, ears, top of feet and back of neck, as these are frequently missed areas.
Know your sun limits. If you burn easily and often, apply sunscreen as needed. If you plan on partaking in water play or sweat a lot, make sure to reapply your sunscreen should you decide to dry off outdoors as most of your protection was washed away by the waves, in the pool, or by your sweat.
Look for sunscreens that not only advertise an SPF of 30+, but also list "Broad-Spectrum" which means it is formulated to not only combat UVB rays, but also protect your skin from UVA rays.
Always remember to use lip balm on your lips for sun protection (skin cancer comes in many forms is just not limited to your arms, legs, and face).
Are there any natural sunscreens?
Sure there are! Here is a list of 21 natural sunscreens on the market.
For more information regarding sunscreen, click here.
Additional Sources
Discovery Health "SPF Numbers"
Prevention & Care: Sunscreen
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