It may not be a surprise to you when I say that ultraviolet (UV) radiation is responsible for 90% of the symptoms of premature aging, including wrinkles. And you’ve probably heard that applying sunscreen is absolutely essential to keeping your skin healthy and youthful. But before you go to your local store to purchase SPF 100 sunscreen, here are a few tips that will help you use sunscreen successfully and choose one that is truly effective at blocking harmful rays.
Know What You’re Blocking: UVA Vs. UVB
The sun produces two main forms of radiation that can damage the skin: UVA and UVB. Both types of radiation can cause wrinkles by breaking down collagen, which inhibits the skin’s natural repair process, causing the skin to loose its youthful elasticity.
- UVB damages the epidermis, the outermost layer of skin, and is responsible for sunburns; however, UVB does not travel through glass and its intensity varies depending on the season and time of day.
- UVA, on the other hand, penetrates glass easily and reaches deeper into the skin; the intensity of UVA is much more constant than UVB and does not vary throughout the year.
Sunblock Vs. Sunscreen
Sunblock physically blocks UV radiation while sunscreen absorbs UV radiation. The difference might seem minimal, but it can make a large difference. Sunblocks typically should have chemicals like titanium dioxide and zinc oxide (look for a 3-7% concentration or higher) which reflect light and prevent UV rays from entering the skin. Zinc oxide has bee used for some time, but people often turn away from it since it is opaque and cosmetically unappealing. Titanium dioxide might be a better choice since it can be more transparent and provides very effective protection. Another benefit of sunblock is that it does not need to be reapplied every few hours.
Sunscreen, alternatively, needs to be applied about every two hours and even more often if you are swimming or sweating a lot. Sunscreen protects your skin from UVA, UVB or both types of radiation, but the chemicals in sunscreen tend to break down under UV radiation, necessitating reapplication. Sunscreen can also be much more transparent than sunblock and will allow some UV rays though, so you are more likely to tan. If you are looking to buy a sunscreen, look for the chemicals: Avobenzone (Parsol 1789); and mexoryl / ecamsule /helioplex.
The Truth About SPF
SPF, or Sun Protection Factor, measures only the UVB absorption for sunscreen. The SPF number is a measure of how long it will take you to burn; for example, SPF 15 will delay your burning 15x the normal amount of time it would take you skin to burn without sunscreen. There are various SPF numbers, but a helpful way to think about their effectiveness is to look at how much radiation they block:
- SPF 15 blocks 92% of UV rays
- SPF 30 blocks 97% of UV rays
- SPF 30+ will still block about 97% of UV rays, but greatly increase the amount of time you can spend in the sun and have a larger margin of error if you do not apply enough sunscreen initially.
Applying It Properly
Most people do not apply enough sunscreen. Generally, 1 oz., or 2 tablespoons, is the amount an adult needs for full body coverage, but it is better to put more on than to follow a set amount.
Additionally, you should wait 15-30 minutes before going out into the sun since the sunscreen needs to be absorbed by your skin.
Understanding how sunscreen and sunblock work is the fist step toward preventing wrinkles; following them is the second step. I will be posting more tips soon to help you use sunscreen properly during these summer months. I recommend all of these tips to my skin care patients. I tell them that following these simple tips can keep them from becoming my Washington DC facelift patients instead.
Check back soon for more sunscreen tips, and in the meantime, let me know if you have any questions about protecting your skin from harmful UV rays.