But the truth is there is no such thing as a “healthy” suntan.  That change in your natural skin color is, in fact, a response to injury by the sun's ultraviolet rays - in other words, that glowing tan actually reflects a degree of skin damage.

Ultraviolet rays are an invisible form of radiation.  There are three types of ultraviolet rays - ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC); all three types are damaging to the skin.  However, UVC is absorbed by the ozone layer and does not reach the earth's surface.  UVB is also absorbed by the ozone, although some rays do reach the earth's surface; they penetrate less deeply into the skin.  Of most concern is UVA, because it penetrates past the top layer of the skin and causes damage to the deep tissues.  Excessive exposure to UV rays is the most important environmental factor in developing skin cancer; it can also be associated with premature skin aging, undesirable changes in skin texture, cataracts, and age-related macular degeneration.

Skin can be classified as being one of 6 types, depending on an individual's susceptibility to burning:

Everyone - regardless of race or ethnicity - is at risk for skin damage as a result of excessive sun exposure.  However, those with skin types I and II are at the highest risk.  Certain diseases (such as lupus) and medications (such as antibiotics and antihistamines) can make a person more sensitive to sun exposure.

You can do several things to protect yourself from skin cancer.  First, avoid outdoor activities between the hours between 10am and 4pm, when the sun's rays are strongest.  Keep your eye on the UV Index, a daily forecast of UV intensity issued by The National Weather Service that predicts exposure levels on a 0 to 10+ scale.  The level of danger calculated is for a person with Type II skin.

The choice of sunscreen is also important: In order for a sunscreen to be truly effective it must protect skin from both UVB rays, which cause sunburn, and UVA rays, which cause long-term damage.

Sunscreen comes in a variety of forms - lotions, gels, sprays, oils. Regardless of type, be sure to select one that blocks both UVA and UVB rays, has a high SPF (at least 15), and is photostable when exposed to UV light.  Avobenzone - a chemical that absorbs both UVA and UVB - has been available for several years and, when combined with titanium dioxide, is considered to be a very effective broad-spectrum sunscreen.  Ecamsule, approved by the FDA in July 2006, is a sunscreen additive that has been available in Canada and Europe since 1993.  It is the only chemical known to block all UVA rays; it also provides some UVB protection as well.  Ecamsule alone can protect the skin from sunburn, but must be combined with other sunscreen agents in order to get an official SPF rating.

But choosing the right sunscreen isn't enough - you must still follow the manufacturer's directions regarding reapplication, or you may not be getting the protection that you think you're getting.  In addition, apply sunscreen using sufficient amounts - at least a tablespoon or more.  Make sure you cover all of your skin - including lips, ears, feet, hands, bald spots, and the back of your neck.

Finally, keep in mind that using sunscreen doesn't mean it's safe to spend more time in the sun, especially when the UV Index is forecasted to be high.  In fact, there is no evidence that sunscreens protect you from malignant melanoma - the most dangerous form of skin cancer.  To give yourself the best protection, seek shade and wear protective clothing - a wide-brimmed hat, long-sleeved shirt, long pants, and wraparound sunglasses that provide 100% UV ray protection.