You are probably thinking you know all there is to know about sun exposure and sunburn, and that I am just trying to ruin your vacation by warning you of all the health damage the sun can cause. But I’d be remiss if I did not reinforce this important message. For the record, I too have spent much time on the beach, basking in the sun’s rays while trying to achieve that dark, golden tan. As a teenager, I coated myself in baby oil to speed the process. Little did I know that I was causing permanent damage to my skin that would reveal itself years later.

Sunburn is a radiation burn to the skin caused by overexposure to ultraviolet light, usually from the sun’s rays. Repeated exposure to UV radiation both tans and damages skin. Similar burns can be produced by overexposure to other sources of UV rays, including tanning lamps, tanning beds and even welding arcs.

The UV content of sunlight is greater at higher elevations because it is less filtered by clouds and haze. It is also stronger the closer you get to the equator. But reflected UV light from snow, sand, water and other reflective surfaces can burn you as severely as direct sunlight does. We all know from experience that you can get a sunburn on a cloudy day.

The two types of UV radiation that affect your skin are UVA and UVB. UVA penetrates the deeper levels of skin, can damage the immune system and may contribute to skin cancer. UVB causes sunburn and plays an considerable role in basal-cell and squamouscell skin cancers and, perhaps, melanoma. Research into the relationship between sunlight and malignant melanoma is ongoing.

In addition to cancer, repeated exposure to the sun can cause brown age spots, wrinkles, “leathery” and sagging skin, and premature cataracts.

The regular and correct use of sunscreens — those that offer protection from both UVA and UVB radiation — is key in preventing sunburn, sun damage and skin cancer. Shopping for sunscreens can be confusing, because sun protection factor, or SPF, ratings refer only to UVB protection. It’s important to check a sunscreen’s label to see whether the product is a broad-spectrum screen. Sunscreens with zinc oxide or titanium dioxide are among those products that protect against both UVA and UVB.

SPF ratings are based on the difference in the amount of time it would take a person wearing sunscreen to burn versus someone who is not. For example, if you normally burn in 20 minutes, a product with an SPF of 15 would allow you to stay out in the sun for 15 times 20 minutes, or five hours, without burning.

People often use sunscreens too sparingly. Most sunscreens call for liberal and frequent applications. (A liberal application is one ounce of sunscreen — the amount than can fit into a shot glass — to cover all exposed areas.) Timing is also important. To have the best effect, sunscreen should be applied 30 minutes beforehand.

Since exposing our eyes to the sun can lead to premature cataracts, they should be safeguarded, too. Big sunglasses like the ones worn by Jackie O are “in” again this year and offer good protection as long as they are 90 percent UV coated. Wraparound sunglasses, again fashionable this year, are another good alternative.

To limit exposure to the sun, take the following precautions:

Stay in shaded areas between 10 a.m. and 3 p.m.
Wear a hat — the bigger the better.
Always wear a cover-up and/or protective clothing.
Use a sunscreen with a high SPF (30 is ideal) and reapply it every two hours and/or upon emerging from the water.
Wear sunglasses with a UV protection factor of 90 percent.
Wear make-up or moisturizer that contains SPF protection.
Wear sunscreen daily, all year round.
And if all else fails and you end up with a sunburn:
Take a cool bath or shower.
Apply aloe vera lotion several times daily.
Leave blisters intact to hasten healing and prevent infection. If the blisters start weeping, apply an antibiotic ointment only to the open areas and cover with a sterile gauze bandage.
If needed, take an over-the-counter pain reliever.
If your sunburn starts to blister and you experience an immediate complication such as rash, itching or fever, see a doctor
If you experience heat exhaustion or heatstroke from overexposure to the sun, seek immediate medical attention.
If you can’t face summer without a tanned glow, try one of the many self-tanning products on the market. Many salons also offer self-tanners that are applied in the booth by a controlled spray. The duration of a self-tan varies from a few days to a few weeks.