Why should I wear sunscreen?
Sunscreen minimizes the short and long-term effects of the sun’s ultraviolet radiation on your skin. Ultraviolet (UV) radiation is responsible for a number of important skin problems including photoaging (wrinkling, brown spots, coarse skin) and an increased risk of skin cancers and pre-cancers. Sunscreen should be a part of a program of sun protection that includes sun protective clothing, staying in the shade, and avoiding outdoor activities at times of peak sun intensity (10 AM- 4 PM).
What are UVB and UVA rays?
Ultraviolet radiation that reaches the earth’s surface is composed mostly of 2 types of rays, UVA and UVB. Each of these interacts differently with the skin. UVA rays penetrate deeper into the skin and are responsible for causing photoaging of the skin which manifests as wrinkles, dark spots, and coarse skin. UVA rays can also lead to suppression of the immune system within the skin and an increased skin cancer risk. UVA rays are not blocked by glass so you may encounter them in your home or car. UVB rays penetrate the skin very superficially, but have more energy than UVA rays and consequently can burn the skin. UVB rays cause sunburn, contribute to photaging, and increase risk for skin cancers. They are blocked by glass. The United States Department of Health and Human Services has declared UV radiation from the sun and artificial sources (tanning beds, sun lamps) a known carcinogen.
When should I wear sunscreen?
Because the damage to skin from ultraviolet radiation is cumulative over your lifetime, the less total UV rays your skin encounters, the better it fares in terms of wrinkles, age spots, and skin cancer risk. Therefore it is best to wear sunscreen daily, applying it in the morning before you leave home. Even on cloudy days up to 80% of the sun’s UV radiation reaches the earth’s surface and your skin. One type of UV ray (UVA) passes through glass in your home, office, or car so that even if you are not outdoors you can be exposed to ultraviolet radiation.
What type of sunscreen provides the most protection for my skin?
The best sun protection is provided by agents that block all types of ultraviolet radiation. You should look for a product that has ingredients that shield the skin form both UVB and UVA types of rays. The SPF number is the best indicator of how well a sunscreen blocks UVB, and sunscreens with an SPF of 15 or more provide adequate protection when used appropriately. Unfortunately, it is currently much harder to assess the UVA blocking quality of sunscreens as there is no labeling to indicate the level of UVA blockage. The FDA has proposed changing this in 2010 to a system where UVA blockage is indicated by a star system where no stars is the least protection and 4 stars is the highest. In the absence of such a rating system, you can look for specific ingredients that block UVA such as Avobezone (Parsol1789), zinc oxide, titanium dioxide, and ecamsule (Mexoryl).
Is sunscreen with an SPF of 30 twice as protective as one with SPF of 15?
The way SPF levels are determined is such that the sun protection does not increase proportionally with the SPF number. A sunscreen with an SPF of 15 screens approximately 93% of UVB rays, whereas a sunscreen with an SPF of 30 screens about 97% of UVB rays. One does get more sun protection with a higher SPF product if it is applied appropriately, but once the SPF exceeds 30 there is very little incremental gain in protection with increasing numbers.
How much sunscreen should I use and when should I put it on?
You should apply sunscreen to all exposed areas of the skin 15-30 minutes prior to going outside. Coat the skin liberally and rub it in well. Most people apply only 25-50 % of the ideal amount of sunscreen. It should take about one ounce of sunscreen to cover all exposed areas properly. Reapplication every 2 hours or after swimming or perspiring is just as important as the original application. Even so-called “water resistant” sunscreens can lose their effectiveness after more than 40 minutes in the water.
I never sunburn. Do I need to wear sunscreen?
Yes. Even though the skin may not show immediate, visible signs of the sun’s influence via a burn, it is still suffering from the detrimental effects of ultraviolet radiation that increase skin cancer risk and lead to photoaging of the skin.
Will wearing sunscreen limit the amount of vitamin D I get?
One of the beneficial effects of ultraviolet radiation on the skin is its promotion of vitamin D production by the skin. Sunscreen use will decrease the skin’s production of vitamin D. Vitamin D levels can be measured by your physician. If you are found to have inadequate vitamin D, your physician can recommend ways to enhance it such as by increasing your dietary intake of vitamin D.