Those warming rays of the sun have a well-deserved Dr. Jekyll and Mr. Hyde reputation. While they generate vitamin D and make us feel great, they also cause skin damage with UV radiation. UV-A radiation prematurely ages skin and contributes to skin cancer. UV-B radiation creates the tans we love and burns we hate.
Our skin’s natural protection, melanin — associated with the amount of pigment in the skin — is not enough. So how can you enjoy the outdoors safely?
CHEMISTRY TO THE RESCUE
Certain chemicals applied to the skin can either filter out some UV rays, or completely block sun damage by reflecting UV away from the skin.
Sunscreens combine organic and inorganic chemicals that absorb UV radiation and release it as heat, allowing longer exposure before burning begins. How much longer is indicated by the Sun Protection Factor (SPF): a SPF of 5 allows you to remain in the sun five times as long as you could without it.
Note that SPF refers only to UV-B, not to UV-A. To ensure protection against UV-A, buy sunscreens that include specific agents against UV-A radiation. Sunblocks reflect the sun away from the skin by providing a barrier of inorganic particles, e.g., zinc oxide or titanium oxide. Sunblocks can be components of sunscreens as well as being used alone.
Many of the activities we most enjoy outdoors pose high risks of sun damage.
• Beach activities — sun plus a 25-percent added exposure from the reflective sand
• Water activities — water is highly reflective, and in shallow water, a sandy ocean bottom can add to the radiation intensity
• Snow activities — snow is a very reflective surface, creating a double burn from the sun and its reflection
Certain locations are more dangerous too.
• High altitudes where UV radiation is more intense than at sea level
• Low latitudes in tropical regions where rays do not have far to travel
• Ozone holes where the Earth lacks its protective filtering layer such as Australia, the skin cancer capital of the world.
To get the most from your sunscreens and sunblocks, remember to apply early, often and carefully.
• Research the layer of stratospheric ozone as found in the Southern Hemisphere, especially the “seasonal ozone hole.”
• How does the amount of pigment in our skin protect us from sun damage? Why are some individuals photosensitive?
• In what ways does our skin protect us?
• Ultraviolet Radiation
By Merry Morris