While it is common knowledge that it is the ultraviolet portion of sunlight that causes sunburns, skin cancers and sun damage, most people may not realize that their sunscreen might not be blocking all the forms of ultraviolet light effectively, even if it has a high SPF number.
Let me explain. Ultraviolet light is divided into 3 main categories:
– ultraviolet A (320-400nm), which is mostly responsible for photo-aging and sun tans, but is also linked to skin cancer (UV-A)
– ultraviolet B (280-320nm), which is mostly responsible for sunburns and skin cancers (UV-B)
– ultraviolet C (<280nm), which we don’t worry about too much, as it is blocked by the ozone layer
In the past, sunscreens here in the U.S. were designed to focus on protecting you from UV-B. The classic “SPF” numbers, for example, are based on how well the sunscreen blocks UV-B – but not UV-A. This helped with preventing sunburns and reducing the risk of skin cancer….but it fell short on protecting you from photo-aging, with fine wrinkles, loss of skin elasticity, and pigmentation irregularities.
We’ve now understand that the ideal sunscreen should give total UV protection – with both UV-A and UV-B coverage. This has been shown in clinical studies to make a huge difference in protecting the skin. The American Academy of Dermatology now recommends that the amount of protection from UV-A and UV-B be equally weighted.
How do we protect against UV-A? Well, you can either use agents which block the rays, or agents that absorb the rays. The three most commonly used ingredients for UV-A protection are:
– Titanium Oxide or Zinc Oxide (physical blocking agents)
– Parsol 1789, also known as “avobenzone”
– Mexoryl SX and XL
The latter two are chemicals that filter the UV light. Look for these in your sunscreen’s ingredient list. If you don’t see any of these ingredients listed, then you probably are using an older formulation, and need to get a more up-to-date product with better protection.
Mexoryl seems to be an improvement over Parsol 1789, with more efficient UV-A coverage and better photostability. Mexoryl has been available in Canada and in Europe since the early 1990’s – but only was FDA approved here in the U.S. in 2006. It’s available in several products, such as the Anthelios line from La Roche-Posay or the Ombrelle line from L’Oreal. These are excellent, if somewhat pricey, products. They are widely available online.
Famous sun tanning myths:
“It’s a cloudy day – I don’t need sunscreen.”
“The SPF in my makeup/moisturizer will protect me from sun damage.”
“Once I apply sunscreen, I’m good for hours.”
“I can’t get skin cancer/photo-damage if I just use a tanning bed.”
“I need to get a good base tan before I go on vacation, so I don’t burn.”
Now, there are many good self-tanning products – so you can fake the sun-kissed look, without exposing yourself to the aging effects of tanning.