There’s a lot of information to take in when it comes to the details of protecting your skin in the sun. Everything from UV rays to understanding why no amount of sun tanning is safe plus skin care considerations play a role in determining the essentials of sun protection. Below are the most critical points everyone needs to be familiar with if their goal is to avoid sun damage. By avoiding sun damage, you’re not only preserving your skin’s health but also its appearance. Practicing good sun sense will result in fewer wrinkles, discolorations, and will help your skin resist developing the most insidious type of sun damage: skin cancer.

• There is no such thing as a safe tan, whether it is from the sun or a tanning booth. Even if you tan slowly without burning (what many people refer to as “developing a base tan”), the damage is hazardous to the health and long-term appearance of your skin.
  
  
• UVB radiation is the sun's burning ray and has an immediate, harmful impact on skin. Damage from UVB rays takes place within the very first minute (yes, 60 seconds) of walking outside.
  
  
• UVA rays are the sun's silent killers. You don't feel them but they are the primary cause of skin cancer, wrinkles, and a weakened immune system. (UVA rays penetrate through clear glass windows that do not have a UV coating.)
  
  
• Even on a cloudy or hazy day, the sun's rays are present and impacting the skin.
  
  
• Sitting in the shade or wearing a hat only protects against a portion of the sun's rays. Plus, other surrounding surfaces such as water, cement, and grass reflect the rays from the ground to your skin giving you a double whammy of exposure.
  
  
• Altitude is a sun enhancer: for every 1,000-foot increase in altitude, the sun's potency increases by 4%. Don’t forget the sunscreen when you’re skiing!
  
  
• According to the FDA, a product's SPF (sunscreen protection factor) number tells you how long you can stay in the sun before getting burned. If you can normally stay in the sun 15 minutes before you start turning pink, an SPF 15 product will let you stay in the sun for approximately 3 1/2 hours without burning. If you begin turning pink after 10 minutes, an SPF 15 will let you stay in the sun approximately 2 1/2 hours. The formula is 10 (minutes) x 15(SPF) = 150 (minutes), or 2 1/2 hours. If you're swimming or perspiring, you must wear a water-resistant sunscreen which provides 40 (labeled as “water-resistant”) to 80 (labeled as “very water resistant”) minutes of protection before you need to reapply it to maintain a sufficient level of protection.
  
  
• SPF is crucial, but it is only a measurement regarding sunburn (UVB) rays. It is dangerous for your skin to not have UVA protection and many sunscreens do not have ingredients that can provide true full-spectrum (both UVA and UVB) coverage. There are no numbers to tell you about protection from UVA radiation. For that protection you have to check the active ingredient list to see if either zinc oxide, titanium dioxide, avobenzone (which may also be listed as Parsol 1789 or butyl methoxydibenzoylmethane), Mexoryl SX, or Tinosorb (Tinosorb is only available in products sold outside the U.S.). If one of those isn't part of the active ingredient list (it doesn't count if it is just part of the regular or "other" ingredients) you are not applying adequate UVA protection and that is dangerous for your skin.
  
  
• Oxybenzone (also called benzophenone-3) is a UVA-absorbing sunscreen ingredient that sounds similar to avobenzone, but is not the same. There are several sunscreen ingredients approved for use in the United States for sunburn protection. While benzophenones and oxybenzone do provide some UVA protection, they are not as effective as titanium dioxide, zinc oxide, avobenzone, Mexoryl SX, or Tinosorb.
  
  
• For those of you who want more specifics about the issue of UVA vs. UVB protection: According to the Skin Therapy Letter published by the Division of Dermatology at the University of British Columbia (vol. 2, no. 5, 1997), "UVA [range is] 315-400 nanometers." According to the FDA, the UVB range is from 280 to 315. The range of protection for the following sunscreen ingredients is listed as "Padimate O, 290-315 nanometers; Benzophenones, 250-350 nanometers; Octyl methoxycinnamate (Octinoxate), 290-320 nanometers; Avobenzone, 320-400 nanometers; Oxybenzone 270 to 350 nanometers; Titanium dioxide, 290-700 nanometers; and Zinc oxide, 290-700 nanometers."
  
  
• Crunching the numbers: an SPF 2 blocks about 50% of UVB rays; an SPF 10 filters out about 85% of UVB rays; an SPF 15 stops about 95%; and an SPF 30 stops about 97%. An SPF that's higher than 30 does not provide any more UV protection, it just offers more time that you can stay in the sun without burning. Even if you choose to wear a higher SPF product, you still need to reapply after swimming or perspiring to ensure continued protection.
  
  
• Even if the SPF number on your sunscreen's label is an SPF 50, it still has limitations and can let approximately 3% of UV rays penetrate your skin, which explains why you still might get some color after prolonged exposure to the sun despite slathering sunscreen on your skin.
  
  
• As a general rule it is best to apply sunscreen at least 15 to 20 minutes before sun exposure. This gives the sunscreen time to absorb and to spread over and into the uppermost layers of skin.
  
  
• You must apply sunscreen liberally. A study published in the Archives of Dermatology (October 2002, pages m1319-1325) said "Sunscreen users are only applying 50 percent of the recommended amount, so they are only receiving 50 percent of the SPF protection." Because of this issue concerning liberal application, expensive sunscreens can be dangerous to your skin's health. After all, how likely are you to liberally apply a sunscreen from Lancome that costs $48 or, even more absurdly, a sunscreen from La Prairie that costs $170 for 1 ounce? Liberal, even application is critical to a sunscreen’s protective ability (Source: Lancet, August 2007, pages 528-537).
  
  
• If you are using AHA, BHA, Retin-A, Renova, Differin, or any topical pharmaceutical retinoid, it can make your skin more vulnerable to sun damage due to the surface exfoliation and changes (removing the top layer of sun-damaged skin) caused by using these products. This information does not impact those who are already diligent about using sunscreen, but if you are not being diligent, your skin is even more at risk for sun damage and sunburn, even with minimal sun exposure.
  
  
• If you are using more than one product that contains sunscreen, the two sunscreens do not add up to one SPF number. In other words, an SPF 8 and an SPF 15 do not add up to an SPF 23. Though you would get an increased SPF value for protection, there is no way of knowing what that increased protection would be. If you want to count on getting an SPF 30's worth of protection, then that is the number you should look for in one product.
  
  
• Getting sunburned is bad enough, but what you may not know is that sunburn continues to develop for 12 to 24 hours after the initial burn takes place! Treat a sunburn the way you would treat any other burn. Do not cover it with thick salves (thick moisturizers are the worst). These will trap the heat and cause more damage. Get the skin in contact with cool (not cold or icy) water or pure aloe vera immediately (do not put ice directly on the skin—that's too much cold and can cause a different kind of burn). Then keep applying the cool water or pure aloe vera on and off for several hours. You may also want to take an over-the-counter anti-inflammatory, such as aspirin, to reduce pain and swelling. If you are unsure what to take, consult your physician.
  
  
• If you have babies or small children, sunscreen protection should be of primary concern. Their delicate skin is even more sensitive to the sun's damaging energy. All sunscreen formulations that have an SPF are regulated closely by the FDA; the formulations don't differ in any way because of the age of the intended user. Of greater concern than the cute packaging on kids' products is that the formulation you choose contains one of these UVA-protecting ingredients: avobenzone, titanium dioxide, zinc oxide, Mexoryl SX, or Tinosorb. For more information on protecting small children from the sun, see our Baby Skin Care Section.
  
  
• If you are looking for a less irritating sunscreen for your kids or yourself, choose one that contains only pure titanium dioxide and/or zinc oxide as the active ingredient (Paula's Choice Pure Mineral Sunscreen is one option and there are other options available in drugstores and department stores). These non-chemical ingredients are definitely less irritating than other types of sunscreen agents.
  
  
• If you're determined to get a tan, the only safe way to do it is with self-tanning products such as Paula's Choice Almost the Real Thing Self-Tanning Gel or the many other options available at the drugstore, from Neutrogena to Coppertone. You can also go to self-tanning booths offered in many tanning parlors (such as Mystic Tan®) that spray a uniform layer of self-tanner from head to toe. The results can be very impressive, assuming you follow all the pre-spray directions.
  
  

Applying Sunscreen:
How Much, When, and Where?

Now that so many products contain sunscreen (foundation, concealers, moisturizers, and even face powders), the next question is, what about application? That’s a great question! The major issue for the use of any well-formulated sunscreen (SPF 15 or greater with UVA-protecting ingredients) is liberal application, as detailed above.

You may have seen recommendations that you should apply sunscreen 20 minutes before you go outside and then again 20 minutes later or whenever you get to where you are going. This is all about the issue of application. Because research has made it clear we aren’t wearing enough of the stuff, dermatologists have recommended these use options to get us to comply, and really put on enough to take great care of our skin.

Within your skin-care routine, exactly when does sunscreen get applied? If you are applying several skin-care products, ranging from toners to acne medications to moisturizers, the rule is that the last item you apply during the day is your sunscreen. If you apply sunscreen and then apply, say, your moisturizer or an anti-acne product, you could inadvertently be diluting or breaking down the effectiveness of the sunscreen you’ve just applied.

Any skin-care product, or even just water (and almost all moisturizers are more than 50% water), applied over a sunscreen reduces its effectiveness to one degree or another. This is why you have to reapply sunscreen after swimming or perspiring. If you use moisturizers, which are always lipid soluble, over your sunscreen these will break down the sunscreen via dilution or removal, and that is a serious problem. What about applying foundation (one that doesn’t contain sunscreen) over the sunscreen you’ve just applied? That depends on several more factors, such as how much you apply, how thick or oily it is, or what kind of sunscreen you are using. To eliminate any dilution and to add more protection, you can choose to wear a foundation during the day that contains sunscreen. Voila, no more worries.

What if your foundation is the product you’ve chosen for sun protection? Then the trick is to be sure you’ve applied it evenly and liberally. If you apply it too thinly or blend most of it off instead of using it full-depth, you would not get the amount of protection listed on the label.

I am concerned about the pressed powders with sunscreen. Although I don’t doubt the validity of these product’s SPF ratings, I worry that most women do not apply pressed-powder foundations liberally enough to get the amount of protection stated on the label. If you lightly dust the powder over the skin there is no way you will get the SPF protection the label indicates. You must be sure you apply the pressed powder in a manner that completely and evenly covers the face. I believe that pressed powders are an iffy way to get sun protection for the face, but they are a great way to touch up your makeup during the day and reapply more sunscreen at the same time.