Be informed – What is SPF?

An SPF (sun protection factor) rating is an estimate of how effectively a sunscreen product reduces the time it takes your skin to burn. For example, if it normally takes about 10 minutes in the sun for you to burn, a product with an SPF of 15 extends that time to burn to 150 minutes. SPF 30? Approximately 300 minutes.

Related post: First aid for sunburns

Keep in mind two things about SPF:

  1. It is not a super accurate measurement of protection. Different people with different skin types burn at different rates.
  2. SPF measures protection from UVB rays only, not UVA rays.

UVB rays are responsible for short-term damage—a sunburn. UVA rays pass deeper into the skin, and are responsible for the aging effects of the sun.

More importantly, both UVA and UVB rays contribute to all types of skin cancer. In general, prolonged exposure to the sun, without burning, is associated with the more benign basal cell and squamous cancers. Frequent sunburns (and tanning beds!) are a risk factor for melanoma, the scariest skin cancer.

Related post: Tanning beds and skin cancer

Although sunscreen could and should be used year-round, we buy more sunscreen products in the summer months. And it’s a good time to stock up on your favorite product, because this is also when you’ll find the best sales.

Related post: The UV Index – health and fitness apps

But do you know what to look for when choosing a product? Do you understand what SPF means and which ingredients offer effective protection? If you aren’t reading labels, and are judging by brand, price or marketing claims alone, you might not be getting the best deal.

So what should you look for on a label?

Because protection from UVA rays is more difficult to measure, in June 2012, the FDA began new labeling regulations for sunscreen products. Now most sunscreens you see will have an SPF factor rating on the label as well as the term “broad spectrum.” Broad sprectrum means the product contains one or more ingredients that block UVA rays as well as UVB rays.

Here are two more things to keep in mind about SPF:

  1. Don’t pay more for higher SPF.
  2. Remember any sunscreen, no matter the SPF, still needs to be applied generously and frequently, at least every two hours, to be most effective.

Are higher SPFs better? Not really. An SPF 15 blocks about 94% of UVB rays; an SPF 45 about 98%. So any product with an SPF higher than 50 is pretty ridiculous.

Sunscreens contain either physical barriers such as zinc oxide and titanium dioxide, or chemical barriers such as oxybenzone and avobenzone.

Physical barriers

Zinc and titanium reflect away UV rays. They are traditionally associated with the heavy, white pastes used to protect noses, lips and ears from extreme sun, but new nano technology has created finer particles that blend onto the skin much better.

These sunscreens are good for those with sensitive skin since they are non irritating. One or the other is usually the active ingredient in any product labeled for babies or sensitive skin. Zinc and titanium are also very stable and don’t break down under sun exposure, making them more effective for a longer period of time.

Chemical barriers

Chemical sunscreens absorb UV rays and convert them to heat. They are unstable with sun exposure, therefore, and need to be reapplied frequently.

There are many chemical sunscreens and they are usually good for either UVB or UVA, so for broad spectrum protection more than one ingredient will be listed under active ingredients. Also, they are less stable than zinc and titanium, so are mixed together to be more stable.

Common chemical barriers are oxybenzone, avobenzone, octinoxate, oxtisalate, Mexoryl SX and Parsol 1789.

These chemicals can also be irritating to the skin, or cause allergies. I discovered a few years ago that I am allergic to oxybenzone and avobenzone. I spent two summers suffering from recurrent hives until I figured it out! Now I only use zinc or titanium based products.

When buying a sunscreen, I don’t care about brand names. I look for the ingredients I want and make sure it’s labeled broad spectrum with an SPF of 15-30. A larger bottle of less expensive sunscreen is best, in my opinion, because you need to apply at least a shot glass full every few hours for your best protection.

Zinc and titanium based sunscreens are often labeled for “sensitive skin” or for babies. Unfortunately, they usually cost a little more, and don’t come in the larger bottles—dang!

Keep your skin safe this summer but don’t break the bank buying expensive sunscreen products!


Frugal Nurse

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