From the June, 2008 issue of Scuba Diving Magazine. Headed for sunnier climes? Follow these seven tips for total sunburn protection on the dive boat.

On the dive boat or soaking up rays on shore, divers spend countless hours in the sun. And with the sun comes harmful ultraviolet radiation. Anyone involved in an outdoor activity risks the chance of skin damage that may one day lead to skin cancer, and divers in particular run a higher risk based on location. The tropics offer ideal water temperatures and crystal-clear visibility, but being so close to the equator comes with added risks.

The National Cancer Institute (NCI) says rates of melanoma are higher in areas that are closer to the equator or receive more sunlight. Thomas Fears, Ph.D., a scientist at NCI, says it's not unusual to see huge differences in sunlight intensity between locations. The amount of ultraviolet B (UVB) rays--the main cause of melanoma--received annually in Hawaii (at about 19 degrees north of the equator), for instance, is approximately 10 times the amount received in Alaska (at about 72 degrees north). The Institute concludes that a 10 percent increase in the average annual intensity is associated with a 19 percent increase in the individual's risk for melanoma in men and a 16 percent increase in women, at any age. "We are now seeing that not only length of sun exposure but also the intensity of the sun's rays can affect one's risk of melanoma," Fears says.

Melanoma is the most serious type of skin cancer, accounting for about 8,000 of the nearly 11,000 deaths due to skin cancer each year. UVB rays burn the upper layers of the skin, causing it to become red, blistery and swollen. Exposure to UVB radiation can also damage immune system cells located in the skin. These cells help ward off bacteria, and the National Cancer Institute says they may also help the body recognize and eliminate cancerous cells. So, not only does UVB exposure cause damage that can lead to skin cancer, but it also weakens one of the natural defenses against this cancer.

So how do you protect yourself? Sunscreen is great, but that's just the beginning. Whether you're on a dive boat or preparing for a shore dive, here are seven sun-safety tips for protecting your body from head to toe:

Avoid the sun between 10 a.m. and 4 p.m.

The middle of the day is when the sun's rays are the strongest, so seek the shadiest locations whenever possible. Sun-savvy divers often get to the dive boat early and stake out a spot for their gear under the boat's canopy so they have a place to get out of the sun during the midday hours. And keep in mind that although UV rays are most intense on sunny days, the National Cancer Institute says as much as 80 percent of the sun's rays can penetrate light clouds, mist and fog, so follow the same precautions despite the weather conditions.

Sunscreen, Sunscreen, Sunscreen

Applying sunscreen should be a normal part of your daily routine. A lotion containing a Sun Protection Factor (SPF) of 15 may suffice for everyday use, but when diving, special precautions must be taken to ensure maximum protection. Bruce Miller, a dermatologist board-certified by the Oregon Health and Science University, recommends the following sun-protection rules for divers:

• Regardless of your skin tone, wear the highest SPF possible, typically SPF 50 in the United States.


• It takes 20 to 30 minutes for sunscreen to be absorbed by the skin, and in that time, it can rub off easily, so apply the sunscreen at least 30 minutes before going in the water, and reapply every one to two hours.


• There's no such thing as too much, so apply a generous amount to any exposed skin--especially the less obvious places that aren't covered by your wetsuit: your face, ears, nose, neck, hands and feet. Use a nonstinging sunscreen to avoid irritating your eyes if you get water in your mask.


• Read labels thoroughly to make sure your sunscreen is labeled "waterproof," not just "water-resistant." While no sunscreen lasts forever, products labeled waterproof last at least 80 minutes in the water compared to the 40 minutes of protection provided by water-resistant products.


• A good sunscreen is both UVA- and UVB-protective.

Check the ingredients. Dr. Paul S. Auerbach, author of Medicine for the Outdoors, says there are certain ingredients you should look for when choosing a sunscreen. For total protection against ultraviolet and visible light, preparations can be composed of various mixtures of titanium dioxide, red petrolatum, talc, zinc oxide, kaolin, red ferric oxide (calamine) and ichthammol. A few of the top-rated sunscreens recommended by the Skin Cancer Foundation are Banana Boat Ultra Sunblock, Coppertone Oil Free Waterproof Sunblock and Hawaiian Tropic Protection Plus Sunblock--all are waterproof, oil-free, have a SPF of at least 30 and offer UVA/UVB protection. He also says to avoid substances, like baby oil, cocoa butter and mineral oil, that may increase the propensity to burn.

Researchers at Italy's Polytechnic University of the Marche recently discovered that chemical sunscreens contribute to coral bleaching, so it's a good idea to use dive-friendly products that are safe for both your body and the environment. Look for products free of chemical UV filters; the active ingredients in natural, coral-friendly sunscreens are usually physical UV filters like zinc oxide or titanium dioxide.

Get the right mix

Mixing sunscreens with other lotions or insect repellents can weaken the effectiveness of the sunscreen. Always apply the sunscreen first, and avoid combining your sunscreen with DEET-based insect repellents. Auerbach explains that DEET lowers the effectiveness of the sunscreen by a factor of about one-third. There are several sunscreen/insect repellent combinations on the market. Most have a low SPF, are not waterproof and contain DEET, but there are some that look promising. The bug-repellent sunscreen by BullFrog Mosquito Coast, for example, is a spray-on, nongreasy, waterproof sunscreen that's rated SPF 30 and it's DEET-free. If you're diving someplace with a lot of jellyfish or "sea lice" (planktonic jellyfish larvae), Auerbach recommends checking out Safe Sea Sunblock (nidaria.com), which is both a sunscreen and sting inhibitor.

Wear sun-protective clothing

It's a must for outdoor enthusiasts. Unlike sunscreen, the sun protection in the clothing won't wash off. Wetsuits provide full protection from the sun, but sitting around in the sun with a wetsuit on gets pretty warm. During surface intervals, wearing a rash guard or clothes from one of the newer sun-protective clothing lines, which claim to be "more lightweight and comfortable" than their predecessors, can provide highly effective UV protection.

When shopping for rash guards--or any other protective clothing--look for the UPF rating. Similar to the SPF rating system used for sunscreens, the Ultraviolet Protection Factor (UPF) is a rating system for measuring the UV protection provided by fabric. A good sun-protective garment should have a rating of at least UPF 50, which only allows 1/50th of the UV radiation falling on the surface of the garment to pass through it, or about 98 percent. Also keep the fabric's color and thickness in mind. Darker is better, and as the fabric stretches, it thins out and its UPF goes down, so thicker is better as well.

Protect the not-so-obvious areas

Auerbach says exposure to ultraviolet radiation from the sun can lead to "sunburn" of the cornea. Being out in the water is when you are at the most risk, as water alone can reflect 10 to 30 percent of UVB, depending on the time of day and location. The best way to avoid this is to wear sunglasses that cover a large area and include side shields, and more important, provide 100 percent UVA and UVB protection. Another safeguard from the sun is a hat. A wide-brimmed hat in particular shades your face, ears and neck from the sun, but even a simple baseball cap can at least protect your scalp and eyes. The sun can burn your lips too, so use a lip balm with built-in sunscreen like ChapStick's Ultra 30.

Stay out of the beds

There is an unsubstantiated myth that if you're fair-skinned, you should tan before you go to a tropical location in order to avoid getting burned. Tanning beds, on average, have more UVA rays relative to UVB than natural sunlight, and UVA is less cancer-causing than UVB. But beds may ultimately prove more dangerous than the sun because they can be used at the same intensity every day of the year, and people often expose their entire bodies at each session, which would be difficult to do outdoors. The American Academy of Dermatology says the result of regular tanning bed sessions can be premature aging (wrinkles, blotchiness and sagging skin), as well as a one-in-five chance of developing skin cancer.

Be Sun-Wise

The Environmental Protection Agency (EPA) publishes a daily UV Index for the U.S. that provides an estimate of the maximum potential hazard from UV for the next day depending on location. The index gives a general recommended action to take based on the UV category level from Minimal to Very High.

• For a UV Index reading of two or less--low danger from the sun's UV rays for the average person--the EPA recommends wearing sunglasses, covering up and wearing a sunscreen with a SPF of at least 15.


• A UV Index reading of three to five means moderate risk of harm from unprotected sun exposure. Recommendation: Take precautions, such as covering up, if you go outside, wear sunscreen and stay in the shade near midday when the sun is strongest.


• A UV Index reading of six to 10 means a high risk of harm from unprotected sun exposure. On these days, apply a sunscreen with a high SPF, wear a wide-brimmed hat and sunglasses to protect your eyes and reduce time in the sun.


• A UV Index reading of 11 or more means extreme risk of harm from unprotected sun exposure. If at all possible, stay indoors on days when the UV Index is Very High. Visit epa.gov/sunwise/uvindex.html.

Sun-Safety Jargon

Learn the lingo and get smart about protecting yourself from the sun's damaging rays.

• UVA & UVB: Two of the three types of invisible light rays (together with UVC) given off by the sun. UVC can't penetrate earth's protective ozone layer, but UVA and UVB can and do reach the surface of the planet. Because UVA is weaker than UVB, scientists long blamed UVB as the sole culprit in causing skin cancer, but recent research has also implicated UVA as a possible cause of skin cancer.


• SPF: Sun Protection Factor. The SPF numbers on a package can range from as low as 2 to as high as 60. This number is a multiplier that depends on the individual's sun sensitivity. For example, if your skin turns red in 10 minutes with no sunscreen, applying SPF 5 increases that duration by five times, meaning your skin will turn red in 50 minutes. Or with regular application of SPF 50, your skin will take 500 minutes (8 hours, 20 minutes) to burn.


• UPF: Ultraviolet Protection Factor. Similar to a SPF rating, UPF is a rating system specifically for sun-protective fabrics. For example: A fabric with UPF 50 only allows 1/50th of the UV radiation falling on the surface of the garment to pass through it.