05.27.08
Sun Savvy Test
There are some misconceptions about sun protection and the role afforded by sunscreens that I think are important to clear up. Here’s a test to see how sun savvy you are:
Answer true or false:
1) An SPF of 45 gives me all-day protection
2) An SPF of 30 gives me all the protection I need
3) Mexoryl is the only way I can get UVA protection
4) If I am in Australia I need to stay out of the sun during certain hours
5) SPF protection is proportional
6) UVC rays are blocked by the ozone layer
7) Zinc oxide does not protect as well as micronized zinc oxide
Zinc oxide provides more protection than titanium dioxide
9) If I don’t care about getting wrinkles I don’t need to wear a sunscreen
10) You need a chemical sunscreen to get the best protection
1) False: SPF provides a rough estimate for the length of time you can stay in the sun without burning, but it depends on the individual’s burning time. Starting with a baseline of SPF 15 sun protective agents are double in concentration, so 15 to 30 is a doubled concentration while 15 to 45 triples it without providing much more protection (from about 93.3% protection in SPF 15 to 96.6% in SPF 30. If you are a “burner” you are better off applying SPF 15 every hour than SPF 30 every 2 hours.)
2) False: SPF ratings refer to amount of UVB protection only. Some sunscreens will say “full-spectrum UVB/UVB protection” but you need to look at the ingredients to make sure you are getting complete UVA protection.
3) False: Mexoryl is a chemical sunscreen that protects up to 380 nm. The UVA range is actually 320 to 400 nm.
4) True: The ozone layer is thinning in some places on the planet, and no sunscreen protects against UVC rays. UVC rays pose a very serious risk for skin damage in some areas, and your best bet is to wear clothing and stay in the shade, especially during peak burning hours.
5) False: SPF protection goes up incrementally as concentrations of active ingredients double. SPF 8 = 87% protection, SPF 15=93.3%, SPF 30=97.7%. SPF ratings beyond 30 are fairly meaningless.
6) False: this is a qualified false and borders on opinion on my part. Some scientists insist ozone absorbs all the UVC rays, while some suggest that in places where the ozone layer is thinning there might be a risk. I believe in erring on the side of caution. In any case, fair-skinned people should limit their amount of beach time during peak burning times no matter where they are—reflections from water (and snow) increase UVB and UVA exposure.
7) False: Zinc oxide in larger particles (100 microns and larger) provides better protection because it works by reflecting or scattering UVA/UVB rays. In addition, nanoparticles may be absorbed by the skin and even enter the bloodstream, and the repercussions there are unknown. But that’s another story.
True: Zinc oxide protects in the 280 to 400 nm range, so provides full-spectrum UVB/UVA protection. Titanium dioxide protects from 280 to 360 nm. Micronized versions probably provide less protection, but no studies have been done in this area.
9) False: Again, I kind of sit on the fence about this one. UVB rays have been linked to squamous cell and basal cell carcinomas, and most scientists accept that more than 90% of skin cancers are the result of sun exposure. However, no link has been established between deadly melanomas and sun exposure, so if you don’t care about wrinkles, sun spots, premature aging and possibly getting a basal cell lesion then fine, don’t wear sun screen. I have noticed that men more than women fall into this category (no, really?) and to them I just provide one cautionary note—if you’re bald wear a hat to prevent painful sunburn. And to avoid lesions on the most susceptible part of your face, your poor little nose, at the very least slap some zinc oxide on your schnozz while you’re at the beach or skiing.
10) False: chemical sunscreens may irritate skin at higher concentrations, and about 15% of the population will break out from a chemical ingredient in a sunscreen product. The following ingredients have been linked to increasing free radical generation upon exposure to UV:
• octocrylene
• octylmethoxycinnimate
• benzophenone-3
