After a cool rainy spring, at least in the northeast, summer has finally arrived, bringing promise of beach time, sailing, cycling and other outdoor activities.
As good as the sun is for the soul, it is hard on the skin. The sun’s UV (ultraviolet) rays age the skin, contribute to skin cancer and can cause painful burns. A good protective sunscreen lotion should be a key part of your outdoor gear.
There are 3 types of UV rays:
• UVA. These rays go into the skin more deeply than UVB rays. They play a major part in skin aging and wrinkling. They also contribute to the growth of skin cancer.
• UVB. These rays are the main cause of sunburn. They tend to damage the skin’s outer layers. These rays also play a key role in the growth of skin cancer.
• UVC. These rays do not reach our skin. The Earth’s atmosphere absorbs them before they reach the surface.
Sunscreens are labelled with their SPF – skin protective factor – a measure of how much of the UVB rays, the rays that cause sunburn, they block. An SPF of 30 blocks some 97% of these rays. Going above 30 adds very little additional protection.
Since it is the UVA rays that most contribute to skin cancer, you should look for a product labelled “Broad spectrum,” indicating protection against both UVA and UBV.
There are two main types of lotion – chemical-based and mineral-based. Chemical sunscreens absorb UV rays, while mineral sunscreens reflect them as well as absorbing them.
It has been found that the chemicals in sunscreens are absorbed and can be measured in the blood. To date, there is no evidence of harm, but this has only been studied recently. The zinc oxide and titanium dioxide in mineral sunscreens are not absorbed but can leave white residue on the skin, and this may discourage use. The best sunscreen is the one you will use!
The ingredients in sunscreen degrade when hot, so leaving the bottle in a hot car or beside you on the beach is not a good idea. Keeping the sunscreen bottle in your cooler is wise.
Despite claims to the contrary, very few sunscreens are “waterproof.” Water-resistant sunscreens will only work on wet skin for an hour or two and should be reapplied every 2 hours if you are sweaty and after you get out of the water if you swim.
Don’t forget to protect your ears, lips (with a sun-protective lip balm), feet and ankles and along clothing/swimsuit edges.
So…
Buy a broad-spectrum sunscreen with an SPF of 30 or higher, apply it liberally every 2 hours (sooner if you go in the water) and be sure to protect all exposed skin. Keep the bottle cool if possible. Do not forget the option of protection with a hat and light-colored clothing.
Edward Hoffer MD is Associate Professor of Medicine, part-time, at Harvard.
What Does The Doctor Say?
By Dr. Edward Hoffer