To understand what to look for in a sunscreen, we must first understand UV radiation and its different forms. Just about every sunscreen sold has some slightly different combination of active ingredients that act as filters. Each of these filters shields our skin from the different forms of UV radiation with varying degrees of efficiency. What’s a consumer to do? Educate themselves.
UV stands for ultraviolet and is a form of light energy. It's part of the solar spectrum and is harmful to us. It’s a proven carcinogen.
Sunlight is composed of visible light, infrared light, and ultraviolet (UV) light. The UV part is what we should be concerned with. If skin cancer isn’t enough to get you to wear sunscreen faithfully, the ugly things it can do to your skin should hopefully help.
There are three types of UV radiation, and each one covers a different range of the light spectrum:
UVA (320-400 nm)
UVB (280-320 nm)
UVC (100-280 nm)
We only need to be concerned with UVA & UVB. Luckily, the ozone layer keeps UVC from ever reaching us.
The “Aging Ray” (An easy way to remember this is to remember A stand for “aging.”) This part of the spectrum causes the most long-term damage to our skin.
UVA rays are the longest of the rays. They are therefore able to penetrate deeper into the skin. They penetrate all the way into the dermis (the layer of skin below the epidermis) and hypodermis (the layer of subcutaneous fat).
When UVA rays reach the collagen and elastin fibers found within your dermis, the fibers become dysfunctional and lose their shape, causing the scaffolding to collapse over time. This is why skin wrinkles and sags. UVA is responsible for lines, sagging, sunspots, melasma, and skin cancer.
Most people aren’t aware that UVA is present all the time, every day, rain or shine. Even on a very cloudy day, UVA rays are doing damage to your skin. In fact, 80% of it passes right through clouds!
So, you don’t only need sunscreen when you’re at the beach or in direct sunshine for a prolonged period. The sun doesn't even have to be visible for UVA rays to be present. If you can see without help from artificial light (a lamp or a flashlight), UVA rays are lurking.
The damage UVA inflicts cannot be seen immediately. The cumulative effects show up later.
UVA penetrates window glass. Even if you seldom leave home, you’re getting UVA exposure.
The “Burning Ray” (remember B for burning), UVB is the culprit anytime your skin burns.
UVB rays travel a shorter distance into the skin. They mostly inflict damage on the epidermis (the outermost layer of your skin) and gradually do a smaller amount of damage to the dermis too.
UVB is 1,000 times stronger than UVA. UVB is more cytotoxic and mutagenic than UVA radiation, which means it can modify your cell’s DNA. UVB is the primary cause of skin cancer.
UVB does not penetrate glass.
UVC
UVC radiation is absorbed by the ozone layer and doesn’t reach the ground. UVC radiation would kill us by cooking us to death!
What does SPF mean?
SPF is not a measure of protection per se. Instead, it indicates how long it will take for UVB rays to redden skin, as compared to how long skin would take to redden without a sunscreen.
For instance, someone using a sunscreen with an SPF of 15 will take 15 times longer to redden than without the sunscreen. An SPF 15 sunscreen screens 93 percent of the sun's UVB rays; SPF 30 screens about 97 percent; and SPF 50, 98 percent. Learn more about SPF here.
There are alarming consequences for failing to protect our skin. But, how do we know which sunscreen is best suited for the job?
Sunscreens typically contain several active ingredients (2-5 on average). These actives work in synergy to provide broader coverage than one ingredient can do alone, as well as add stability to the formula.
Don’t worry about learning all of them. Just pay attention to four key UVA-screening ingredients. Most sunscreen formulas offer reliable UVB protection, so your focus should be on UVA-protecting ingredients.
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Which UVA Active Ingredients Are Most Effective?
(These are the most effective UVA actives available in the U.S. at the time of this writing.)
Four ingredients protect within the UVA spectrum, but they offer different levels of defense:
1. Zinc Oxide
2. Titanium Dioxide
3. Avobenzone
4. Ecamsule (often listed by its trade name, Mexoryl SX, patented by L’Oréal)
Your sunscreen must contain at least one of these four ingredients. So, which do you choose?
First, decide whether you want a physical or chemical sunscreen. If your skin is sensitive, you may do better with a physical sunscreen. Try both types to see which you like better.
If You Think You'd Like a Physical Sunscreen:
When looking at Zinc Oxide or Titanium Dioxide, Zinc Oxide is the better choice. Many physical-only sunscreens are a combination of both filters.
• Zinc Oxide provides the most complete protection in the entire UVA spectrum (280-400 nm). It protects against both UVA-1 and UVA-2 rays.
• Titanium Dioxide provides good coverage for UVA-2 (320-340 nm) but is weaker and provides insufficient protection for UVA-1 (340-400 nm).
• Zinc Oxide by itself in a formula isn’t sufficient if high SPF is required. (Say you need high UVB protection because you’ll be in intense sunshine or burn easily). For this reason, Zinc Oxide is often combined with UVB filters, such as Octocrylene. But if you don’t expect to be under intense sun for an extended period, a Zinc sunscreen without an additional UVB filter is fine.
• You want a minimum of 5% Zinc Oxide in the formula but ideally 10-20%
Physical sunscreens technically do not need to be reapplied every two hours, unless you are sweating, swimming, or they get wiped off. They form a physical barrier over the skin. It’s a good idea to reapply anyway if you’re able since your skin produces oils that may compromise the protection. But since reapplication every two hours isn’t always realistic, it’s good to know and often a reason to choose a physical sunscreen over a chemical one.
If you don’t like the feel or look of the Zinc-based sunscreens, look into nano Zinc formulas. Some of the newer Zinc-based products are made with nano-sized particles of Zinc that do away with the white look many of them impart. Alternatively, there are several tinted Zinc-based sunscreens.
If You Choose to Try a Chemical Sunscreen:
• Avobenzone is an excellent UVA filter, but it’s very photo-unstable, meaning it gets degraded by light quickly. This is addressed by adding photo stabilizers like Octocrylene or encapsulating the ingredient into liposomes.
• Neutrogena’s patented Helioplex contains Avobenzone, Oxybenzone, and DEHN (diethylhexyl 2,6-naphthalatate). DEHN is an ingredient that stabilizes Avobenzone.
• Solastay (Ethylhexyl Methoxycrylene) is a photostabilizer for Avobenzone and Octinoxate.
• Ecamsule (Mexoryl SX) is limited to L’Oréal owned brands (e.g., La Roche Posay’s Anthelios SX line, Lancôme), as L’Oréal has the patent on this ingredient.
• La Roche Posay’s Anthelios SX contains Ecamsule, Avobenzone, and Octocrylene (to stabilize the Avobenzone).
Chemical sunscreens must be reapplied every two hours. They lose their ability to absorb UV rays after that time.
The 17 filters approved by the FDA and their effectiveness against both UVA and UVB rays. Take note of the UVA column. Only about 8 of these 17 are ever used.
Several decent sunscreens contain both physical and chemical filters. It’s not a bad idea to have both types of ingredients present in a formula to deflect rays and absorb those that don’t get deflected.
The best way to protect your skin is to read ingredients lists. It seems overwhelming at first, but it becomes second nature. You can also check the quite helpful EWG.org’s yearly guide to sunscreen, where they compile a list of the very best each year.
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The filters listed here will suffice for average UVA protection, but if you want to get serious about protecting your skin from UVA rays (say you struggle with melasma or are just diligent about caring for your skin), you’ll want to look into European or Asian sunscreens with high PPD or PA ratings. These are ratings in addition to the SPF rating that indicate the level of protection against UVA rays.
In Europe for example, they have options for UVA protection such as Mexoryl XL (patented by L’Oréal, an oil-soluble version of Mexoryl SX), Tinosorb S, and Tinosorb M. These filters provide a much higher level of protection against UVA rays than anything offered in the U.S. currently. Hopefully, the U.S. FDA will begin to approve some of these highly protective UVA filters for use in our country.
In addition to wearing sunscreen, the American Skin Cancer Society recommends wearing sunglasses, hats and protective clothing, as well as seeking shade whenever possible and avoiding the sun during peak hours. Since sunscreen only offers some protection from harmful UV rays, these additional measures will go a long way towards preserving the beauty and health of your skin.