Sunlight and skin damage

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DOCTOR’S CORNER

 

WINTER is gone and soon summer will be upon us.

It gets very hot during summer in Lesotho and we all have plans to enjoy the sun after such a dreadful winter, but there is also something about the “good” sun that we need to know about.

A bit of background first. The skin shields the rest of the body from the sun’s rays — a source of ultraviolet (UV) radiation that can damage cells.  Brief over-exposure causes sunburn.

With long-term exposure to sunlight, the skin’s uppermost layer (epidermis) thickens, and pigment-producing skin cells (melanocytes) increase the production of pigment (melanin), which gives the skin its colour.

Melanin, a naturally protective substance, absorbs the energy of ultraviolet rays and prevents the rays from penetrating deeper into the tissues.

Sensitivity to sunlight varies according to race, previous exposure and complexion, but everyone is vulnerable to some extent.

Because dark-skinned people have more melanin, they have more resistance to the sun’s harmful effects, which include sunburn, premature ageing of the skin and skin cancer.

Albinos have no melanin in their skin, can’t tan at all and burn severely with even a little sun exposure.

Unless albinos protect themselves from the sun, they develop skin cancer at an early age.

People with vitiligo have patches of skin that do not produce melanin and thus may also become severely sun-burnt.

Sunburn results from an over-exposure to ultraviolet B (UVB) rays. Depending on the type of skin pigment a person has, and the amount of sun exposure, the skin becomes red, swollen and painful one hour to one day after exposure.  Later blisters may form and skin may peel.

Some sun-burnt people develop a fever, chills and weakness and those with very bad sun-burns may even go into shock — low blood pressure, fainting and profound weakness.

The best and most obvious way to prevent sun damage is to stay out of strong, direct sunlight.

Clothing and ordinary window glass filter out virtually all damaging rays.

An interesting fact is that water is not a good filter: UVA and UVB rays can penetrate a foot of clear water.

Neither clouds nor fog is a good UV filter also — a person can get sun-burnt on a cloudy or foggy day!

Before exposure to strong, direct sunlight, a person should apply a sunscreen, an ointment or cream containing chemicals that protect the skin by filtering out UVA and UVB rays. Many sunscreens are either waterproof or water-resistant.

One common, effective type of sunscreen contains para-aminobenzoic acid (PABA).

Another type of sunscreen contains a chemical called benzophenone.

Many sunscreens contain both PABA and benzophenone and other chemicals — these combinations provide protection from a broader range of UV rays.

Other sunscreens contain physical barriers like zinc oxide or titanium dioxide — these thick, white ointments block sunlight from the skin and can be used on small sensitive areas, such as the nose and lips.

The first tingling or redness is a signal to get out of the sun quickly.

Cold tap water can soothe raw, hot areas. 

Sun-burnt skin begins healing by itself within days, but complete healing may take weeks.

Sun-burnt lower legs, particularly sun-burnt shins, tend to be particularly uncomfortable and slow to heal.

Sun-burnt skin makes a poor barrier against infection, and if infection develops, healing may be delayed.

After burnt skin peels, the newly exposed layers are thin and initially very sensitive to sunlight.

These areas remain extremely sensitive for several weeks.  The sun radiates energy of different wavelengths — for example, yellow light has a longer wavelength than blue light.

UV wavelengths are shorter than wavelengths of visible light and can damage living tissue.

Fortunately the ozone layer filters out the most damaging UV wavelengths, but some UV light, chiefly the A (UVA) and B (UVB) wavelength band, penetrate to the earth and cause skin damage.

More and more dangerous wavelengths are however reaching the earth because the filter is being destroyed by different chemicals, and therefore more damage to living tissues including the skin — eg the chemical reactions between the ozone layer and chlorofluorocarbons (chemicals in refrigerants and spray can propellants), which deplete the protective ozone layer, creating a thinner atmosphere with some holes.

Are tans healthy? No. Although a suntan is often considered an emblem of good health and an active, athletic life, tanning for its own sake is actually a health hazard.

Any exposure to UVA or UVB light can alter or damage the skin. Long-term exposure to natural sunlight or artificial sunlight in tanning parlours may cause long-term skin damage.

Quite simply, there’s no “safe tan”.

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