May 16 , 2005
by Laura Dolson
By now, you probably think you know what there is to know about the dangers of sun and sun protection. But did you know ?
Types of Ultraviolet Rays/Types of Skin Cancer
Ultraviolet rays are the damaging rays that come to us from the sun. Although sunlight has some good effects (such as producing vitamin D), ultraviolet rays cause some damage at even small doses. There are essentially two kinds of ultraviolet rays that make it to the earth's surface. We can think of them as two bandwidths, or ranges of wavelengths. (You will notice that the two wavelength ranges shade are continuous - both kinds really cause all kinds of damage. We are talking about "primary responsibility"):
Ultraviolet B (UVB) Radiation - 290-320 nanometers - This type of radiation is responsible for most sunburn, and the two most common types of skin cancer - basal and squamous cell cancers.
Ultraviolet A (UVA) Radiation - 320-400 nanometers - This type of radiation is responsible for the less-common, but more-deadly type of skin cancer: malignant melanoma. It penetrates deeper into the skin and is more able to break down connective tissue as well. It also varies less over the course of the day and year than UVB light. Also, unlike UVB, window glass does not protect against UVA light.
Both Types - cause other skin damage (premature aging and wrinkling, easy bruising), eye damage (including cataracts) and decreased immune function.
Clouds - Clouds only screen out some of the ultraviolet radiation the sun produces. A light cloud layer can let up to 80% of the UV light through, and even heavy clouds let some through.
Snow, Sand, and Water - reflect the sun's rays, intensifying their effects.
Tanning Salons - Don't believe them if they tell you that tanning beds won't damage your skin. They contain lots of UVA light.
How Can We Avoid Sun Damage?
First Line of Defense - Stay Indoors During Peak Hours
We've all heard it - the hours between 10 and 3 are the most dangerous for sun exposure. This is especially true for UVB light, although UVA light also peaks at this time. A rule of thumb is to stay out of the sun when your shadow is shorter than you are.
The UV Index Can Give You More Info - (Plug in your town or zip code)
Second Line of Defense - Protective Clothing
The Australians have learned a valuable lesson about protective clothing, and it has helped them to reduce the worst skin cancer rates in the world. Protective clothing is essential. This is the best way to avoid UVA rays when outside. However, regular clothing only blocks out some rays. The best clothing for sun protection:
Covers You - Wear loose-fitting long sleeves and pants, and hats
that shade your neck as well as your face.
Third Line of Defense - Sunscreen
You may be surprised to see sunscreen listed third. This is for three reasons:
Sunscreen can give a false sense of security. - People who use sunscreen
may stay in the sun longer. This is not the idea of sunscreen, which
is just to protect you while you are in the sun. No sunscreen gives
Also, check the expiration date! I just found a bottle in our house which expired over two years ago. Needless to say, I threw it away.
Question for Discussion: Why do teens use sunscreen less? What would help you to use sunscreen more consistently?
Bonus Link: Pictures of my friend's mom when in treatment for skin cancer (warning, the pictures are pretty graphic)