O’Donoghue Dermatology Blog

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Choosing the Right SPF Number for You

With so many sunscreen products on the market, choosing the right one for you may be difficult. This information will help you make an informed decision when choosing a sunscreen product.

The first thing to consider is how long you are going to be exposed to the sun. The longer you are in the sun or by a window, the higher the SPF number you should use. It is important to note that, normal glass blocks UVB rays, but allows damaging UVA rays through. Some modern windows block as much as 99.9% of UVA and UVB rays.

Sunscreen products are meant to be applied liberally and reapplied every couple of hours or after sweating or swimming. If you are not planning to use a liberal amount of sunscreen, opt for the higher SPF number than you normally would to ensure that you are getting as much of the protective ingredients as possible on your skin.

If you are going to be swimming or perspiring heavily, choose a sunscreen that is labeled as "water resistant" or "very water resistant" and reapply frequently, especially after toweling off. Keep in mind that no sunscreen can be "water proof", if you have a sunscreen product that is labeled as such; it was purchased before the new FDA labeling requirements went into effect in December of 2012 and it should not be trusted.

SPF stands for Sun Protection Factor and, if the word "factor" reminds you of math class, there is a reason for that. The SPF number is multiplied by the amount of time (in minutes) in which you typically burn when you are not wearing sunscreen to figure out how long it will take to burn with protection. If you typically burn within 20 minutes and you are using SPF 15, 20 min. x 15 SPF = 300 min. or 5 hours.

Very fair skin will typically burns within 20 minutes of sun exposure. Light to medium or olive skin usually burns within about 40 minutes. Medium to tan skin will typically tan before it burns, but it is still at risk of burning after about 60 minutes. Darker skin tans easily and is less likely to burn but, even though the effects of the sun are less evident, the damage is still occurring.

Individuals with very fair skin should use an SPF of 35 or more while exposed to the sun and additional protection like a hat is recommended when exposed to the sun for extended periods of time. Individuals with medium to tan skin should use products with an SPF of 25 or above and darker skin individuals should use an SPF of 20 or greater while out in the sun.

New FDA labeling requirements ensure that products do what they say they do, but the trick is in the proper application of the products. As previously stated, these products are intended to be lathered on. You should use about 1 ounce of sunscreen on your body and using half as much sunscreen does not give you half the protection. Using half as much sunscreen actually gives you the square root of the protection, half the recommended amount of SPF 70 will give you an SPF of about 8.4 not an SPF of 35.

It is not enough to apply a little bit of a high SPF product in the morning and keep going all day.

The benefits of vitamin D
New FDA Sunscreen Label Requirements


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Wednesday, 28 October 2020

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