What is SPF? Sun Protection Factor (SPF) ranges from 2 to 50 and refers to the product’s ability to block the sun. For example, SPF 15 means you can be in the sun 15 times longer than you can without sunscreen. The reason I recommend the SPF level that I do is simply a matter of percentages.
Diagram of SPF against blocking percentage.
SPF 2 means that the sunblock will absorb 50% of UV radiation, while an SPF of 34 will absorb 97%.1 This is the reason I recommend SPF 35 or higher…because I want to block the majority of the UV radiation. This not only will prevent sunburns, but it will also prevent wrinkles, age spots, and as a result produce younger, healthier skin…thus the anti-aging effect.
All sunscreens are not created equal. Sunscreen can be made using a variety of ingredients…typically divided into two categories: chemical and physical blockers. As with most things in life, you get what you pay for. So how do we choose a sunscreen?
Things to look for:
- Broad-spectrum sunscreen that protects against UVB and UVA radiation.1
- Physical sunblocks containing micronized zinc oxide or titanium dioxide block both UVA and UVB radiation.
- UVB radiation is the primary cause of sunburns and skin cancer. PABA (para-aminobenzoic acid), PABA esters, salicylates, and cinnamates only protect against UVB radiation. SPF rating relates to the ability to block UVB not UVA radiation.1
- UVA radiation penetrate deeper into the skin and cause premature aging and wrinkling of the skin. Oxybensone, sulisobenzone, and Parsol 1789 (avobenzone) all block UVA radiation.1
- Waterproof sunscreens are important too, especially if you are sweating or doing a water activity.
Most of us remember the lifeguards from the 70’s and 80’s with a white nose.
Pic of lifeguard
That white color comes from zinc oxide…a physical UV blocker (i.e. sunblock). Titanium dioxide and zinc oxide are physical blockers because it physically blocks the UV rays. These are the best types of sunscreens because the block both UVA and UVB radiation. Since the era of hair bands, some of the more respected manufacturers, such as ZO Skin Health®, have refined the process of micronization of zinc oxide. This micronization has allowed them to combine the highly effective physical-blocking properties of zinc oxide into a product that can be smoothly applied without the caking.
The other type of UV blocker is chemical. Chemical sunscreens are typically colorless. When the radiation hits the molecule, the sunlight is filtered so less of it hits the skin. I recommend you read my blog on SPF for more details. They historically block UVB, but more recently, they absorb UVA as well.1
Diagram of physical vs. chemical sunscreen blocking
For more information about sunscreens, read my other blog on Sunscreen…REAL secret to anti-aging.
1Facts About Sunscreen, American Melanoma Foundation, www.Melanomafoundation.org, 2006.