SPF = Sun Protection Factor
An SPF 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:
- It is not a super accurate measurement of protection. Different people with different skin types burn at different rates.
- 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.
Related post: What is the UV Index?
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 are dangerous to your health
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.
How to choose a sunscreen
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:
- Don’t pay more for higher SPF.
- 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.
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 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 usually come in the larger bottles.
UV protective clothing
Another option for sun protection is the expanding line of UV protective clothing. These hats, shirts and bodysuits have been used for some time on the beaches in Australia, and they are becoming more common in the US.
They use a “UPF” or ultraviolet protection factor rating rather than the usual SPF. The fabric is specially treated to block both UVB and UVA rays. A UPF rating of 15 means less than 10% of UV rays are transmitted through the fabric; a UPF rating of 50+ (the best) means less than 2.5% of the damaging rays are reaching your skin.
The clothing is expensive, but falling in price due to its increased popularity. Also, the UPF holds up under frequent laundering and use. Hand-me-downs!
Keep your skin safe this summer but don’t break the bank buying expensive sunscreen products!
Some recommended products: