UV and You
Sunshine and Safe Skin
by Buck Tilton
Blue as the sky, pungent
in odor, its name comes from the Greek for smell. Ozone, compared to other
gases (oxygen, nitrogen, carbon dioxide), is rare in our upper atmosphere.
Squashed down to sea level air pressure, all Earth's ozone would be Fig
Newton-filling thin... less than one-eighth inch. Most of it (about 90%)
ebbs and flows through the stratosphere, six to 25 miles above the ground.
But ozone's unique optical properties allow it to function as a shield,
keeping enough harmful ultraviolet (UV) radiation from reaching the ground
to make life as we know it possible. Even just a little too much UV radiation
and cells in human skin start to alter in unhealthy ways.
Sunshine strikes the Earth in rays of varying wavelengths. Long rays (infrared)
are unseen but felt as heat. Intermediate length rays are visible as light.
Shorter rays (ultraviolet) are also invisible and are further divided
into three groups:
A (UVA), beneficial in low doses but may increase the chance of cancer
in high doses
2) UVB, primarily responsible for sunburn and cancer
3) UVC, the shortest and most dangerous. UV rays contain enough energy
DNA in living skin
and eye cells. DNA controls your cells' ability to heal and reproduce.
Earth's ozone layer allows life to flourish by passing the longer, beneficial
wavelengths and effectively blocking almost all UVC, some UVB, and a little
According to NASA's ever-spinning satellites, the ozone layer's wavering
protection lays four to eight percent thinner over the entire earth than
it did ten years ago. A depletion of that magnitude could raise the chance
of skin cancer in North America as much as 15 percent. Some experts disagree.
NASA says Yes, Rush Limbaugh says No, but the point ends up being moot.
Skin cancer can be thought of as an outdoor syndrome,the result of periods
of intense overexposure to ultraviolet light even if the ozone was not
An estimated 32,000 U.S. citizens malignant melanoma, the vilest form
of skin cancer, and between 7000 and 9000 will die when the cancer metastasizes
(spreads) to other vital organs. That's a 300% rise in the last decade.
Melanoma occurs in the melanocytes, the cells of the skin that determine
skin color, and it occurs most often in people who are fair-skinned and
freckled, people who sunburn easily. The average age at which melanoma
strikes has been dropping dramatically. Ten years ago it was considered
unusual to find skin cancer in anyone under 40. This year fully one-fourth
of all melanomas will involve people in their 20s and 30s. Tragically,
children are the most susceptible, but the problem may not show up for
years. If caught early, malignant melanoma is virtually 100 percent curable.
Physicians recommend a monthly skin check for the symptomatic ABCDs of
A for Asymmetry:
One half of a mole or skin spot doesn't match the other half.
B for Border Irregularity: Ragged, notched, or blurred edges.
C for Color: Changes in color from black to brown to red, often with a
combination of colors. Blue and white may appear.
D for Diameter: Any mole or spot that grows to more than one-fourth inch,
about the size of the end of a pencil eraser.
is one of three common forms of skin cancer, but not the most common.
That distinction belongs to basal cell carcinoma, with about one half
million cases reported annually. Basal cells make up the base of the epidermis,
the outermost covering of the body. UV radiation can cause these cells
to reproduce too fast, producing a tumorous growth. Basal cell carcinoma
usually start as a slow-growing, small, shiny (or pearly) bump that becomes
an open sore taking longer than three weeks to heal. They often bleed,
crust over, and open to bleed again. The cancer may be an itchy or tender
reddish patch that comes and goes. Sometimes it's a pale splotch, like
a scar, and sometimes a circular growth with a raised border and depressed
center. Squamous cell carcinoma, the second most common skin cancer, accounts
for about 100,000 cases each year. Like the other forms, it appears most
often on the face, ears, hands and forearms. In the past 50 years, shoulders,
back and chests on men, and the lower legs of women, have become increasingly
popular sites for skin cancer due to deliberate exposure of those body
parts to UV radiation. Squamous cells make up most of the epidermis. When
they become cancerous, they may look like basal cell cancer, but the problem
can also appear as a wart that bleeds and crusts over, bleeds and crusts
over. Cancerous squamous cells grow faster and metastasize more frequently
than basal cell carcinoma.
Sun can damage skin in ways other than cancer. The earliest sign of skin
damage is sunburn. Sunburns that continue to worsen several days after
exposure may be a sun allergy. Sun allergies sometimes show up as severe
sunburns, and, less often, as a poison-ivy-like rash. Overexposure to
sunlight causes premature aging of the skin. But all of these problems
can be thought of as preparation for later episodes of skin cancer. According
to the Skin Cancer Foundation: The sun is the cause of at least 90
percent of skin cancers.
The danger of ultraviolet radiation is increased by reflection. Depending
on the angle of reflection, water can reflect up to 100 percent of UV
light. Angle of reflection is determined by the height of the sun above
the horizon. Early in the morning and late in the evening, with the sun
low in the sky, water may bounce only 10 percent of the UV rays back at
you. At noon, with the sun directly overhead, water absorbs most ultraviolet
light, and reflectivity drops to about five percent. But mid-morning and
mid-afternoon, with the sun at a 35-45 degree angle, water can reflect
all the UV rays striking its surface.
Sun-related skin problems, happily, are among the most preventable of
outdoor problems. Take cover . . . the first line of defense is worn.
Tight-weave clothing blocks a large amount of UV radiation, especially
if it stays reasonably dry. A full-brimmed hat will shade face and neck,
and a floppy brim breaks up UV better than a rigid brim. Sunscreens dramatically
reduce the chance of skin problems. Although most experts agree screens
with an SPF of 15 sufficiently protect most skin, recent studies show
that higher SPF numbers offer additional protection, especially in the
first few hours of exposure. Be sure your sunscreen guards against UVB
and UVA radiation. Sunscreens are maximally effective if smeared on when
skin is warm, and allowed to soak in for about a half-hour before extreme
exposure. If you're someone with a very susceptible skin-type, consider
completely blocking UV radiation with an opaque substance such as zinc
Ultraviolet A bombards the earth at an almost constant rate throughout
the day, but approximately 80 percent of UVB strikes between 10AM and
3PM. Try to minimize your exposure during those hours.
Some medications, combined with sunshine, decrease the time it takes for
UV light to damage skin: tetracyclines, antihistamines, sulfa drugs, diuretics,
some oral contraceptives. Consult your physician or pharmacist.
UV light damages eyes as well as skin. The conjunctiva can swell from
UV exposure, sun-induced cataracts can form from repeated exposure, and
direct UV will burn the retina. Wear sunglasses that absorb or reflect