Sun Protection in Belize
The sun just doesn't seem stronger in the tropics - it is! And sun protection is vitally important - especially for children and young adults.
Fortunately, sun protection can be obtained in a number of different ways - clothing, chemical sunscreens (and sunblocks), and simply staying out of the sun. For most people (including children), a combination of all three works best in the tropics.
General Sun Facts
Ultraviolet Radiation (UVR): The sun produces ultraviolet radiation (UVR) that gives us light to see, warmth, and fuel for the growth of plants.
- UVR has 3 different bands - UVA, UVB and UVC. Very little UVC reaches the earth's atmosphere. UVB is the strongest band and causes most sunburns. UVA is weaker than UVB, but about 100 times more UVA than UVB rays reach the earth's surface, meaning UVA protection is still important.
- Skin cancers, cataracts and 90% of visible aging (wrinkles) are caused primarily by UVB and UVA rays. Sunburn is caused primarily by UVB rays.
- The risk of skin cancer is believed to double for people who receive just one or two severe sunburns during childhood. In fact, researchers believe that 80-90% of the skin damage that causes wrinkles and skin cancer is received before the age of 18.
- Sunburn shows damage to the skin caused by UVB rays. However, just because the skins shows no visible signs of a burn does not mean it is not being damaged by the sun.
SPF Ratings: The SPF (or sun protection factor) measures the amount of sun protection provided against UVB rays ONLY. SPF does NOT measure the amount of protection provided against UVA rays. The SPF rating indicates how much longer it takes to get a sunburn using the sunscreen than it would without using the sunscreen. For example, an SPF rating of "2" means it takes twice as long to get a sunburn, a rating of 10 means it takes 10 times as long.
- A tan only provides about the same amount of sun protection as a sunscreen of 3 SPF.
Skin Types: Skin is divided into 6 types for sun protection purposes. The Skin Types are:
- Type 1: Always burns, never tans (fair skin, light-eyes, freckles)
- Type 2: Usually burns, tans with difficulty
- Type 3: Sometimes burns, sometimes tans
- Type 4: Burns minimally, always tans
- Type 5: Rarely burns, tans profusely
- Type 6: Never burns, deeply tans (dark skin, dark eyes)
The Ozone Layer: Ozone is the gas that filters UVB rays from the atmosphere (ozone does not filter UVA rays). The size of the ozone layer (and the protection it provides from UVB) varies based on the time of day, location, season and altitude.
- The ozone layer is at its thinnest in the tropics (UVR levels are 1,000 times higher at the equator than at the North or South Poles).
- The ozone layer is also thinner during the summer and fall, and from 10 a.m. to 2 p.m.
- Sand increases the intensity of UVRs by reflecting back most of the UVRs that reach the earth's surface - intensity can be increased by as much as 80%.
- Surprisingly, water reflects very little UVR and cloud cover reduces UVR that reaches the earth's surface - but the amount of protection is determined by the density of the cloud cover.
- The ozone layer provides much less protection from UVR at high altitudes
Sun Protection Methods
Clothing: As with sunscreens, sun protection from UVB rays provided by clothing and fabrics is expressed in terms of an SPF rating.
Research on clothing and UVR protection has found that:
- One hundred percent (100%) polyester has the highest SPF of all fabrics, providing 2 to 3 times more sun protection that any other fabric.
- Darker colored clothing has a much higher SPF than light colored clothing (black clothing provides 5 times more protection than white clothing - a white T-shirt has only a 5 SPF rating).
- Knits have a higher SPF than woven fabrics, and nylon spandex knits have a very high SPF, regardless of color.
- The heavier the weight of the fabric, the higher its SPF. A double layer of fabric almost doubles the SPF of clothing. This is true regardless of fabric type (the same for cotton, silk and polyester, for example).
- More tightly woven fabrics help reduce UVR transmission to the skin, but not as effectivley as heavier-weight fabrics.
- Wet fabrics INCREASE the amount of UVR that reaches the skin - by as much as one-third.
What does this all mean for clothing in the tropics?
- In very hot weather, wear loose fitting, tightly woven clothing. The folds of loose fitting clothing provides sort of a "double layer" of fabric, thereby doubling the SPF of the clothing. The tight weave helps reduce UVR transmission when it's too hot for more effective heavier-weight fabrics.
- When snorkeling or swimming for long periods, wear a dark-colored t-shirt for extra sun protection. Not only does a light-colored t-shirt offer limited SPF protection, the fact that it's wet INCREASES the UVR that reaches the skin, rather than DECREASING it. Bicycle shorts are also not a bad idea when snorkeling.
- Put on dry clothes (or at least cover-up) after swimming and snorkeling.
- Wear a cover-up on the beach since UVR rays are intensified by the sand.
Sunscreens and Sunblocks
Important: Never use sunscreens of any kind on babies not yet 6 months old. Test sunscreens for allergic reactions in children by applying the sunscreen to a patch of skin. Baby oil does NOT contain sunscreen.
Sunscreens are either "organic" or "inorganic" (inorganic sunscreens are also called "physical" sunscreens). "Organic" does NOT mean the sunscreens are naturally produced. Rather, an "organic" sunscreen is one which is composed of carbon and hydrogen (among other things).
Organic sunscreens are absorbed into the skin to some extent. PABA (para amino benzoic acid) is the most famous sunscreen because of the allergic reaction it causes in so many people. Many people are also allergic to the common organic sunscreen Benzophenone (Oxybenzone).
Most organic sunscreens block only UVB rays. For UVB protection, SPF 15 is adequate for most skin types since an SPF 15 sunscreen blocks 95% of UVB rays while an SPF 30 sunscreen stops only about 2% more (97%).
Inorganic or physical suncreens are really microscopic solid pieces of sunscreen - the most common being zinc oxide and titanium dioxide. Most physical sunscreens are now microfine and with particles so small they cannot be seen (unlike the thick white paste of past lifeguard movie fame). Zinc oxide is generally considered very safe and causes very few allergic reactions.
Titanium dioxide blocks some UVA and zinc oxide blocks more UVR than any other single ingredient. No sunscreen will completely block UVA rays.
Tips on Choosing a Sunscreen:
- Don't rely simply on statements of "protection" against UVA since some researchers believe many of these sunscreens only offer an SPF of 3 or 4 for UVA rays, even if the SPF is much higher for UVB rays. Instead, look for a sunscreen labeled "broad spectrum" that contains zinc oxide and has a minimum SPF rating of 15.
- Apply sunscreen about 20 minutes before sun exposure to allow it time to "set up" on the skin. Reapply every two hours when swimming or sweating.
- Use at least 1 full ounce of sunscreen per adult per application (SPF ratings are based on this amount). Using a smaller amount of SPF 30 does NOT equal a greater amount of SPF 15!
- SPF Sunscreen Recommendations based on skin type:
- Type 1 (always burns, never tans): 30 SPF
- Type 2 (usually burns, tans with difficulty): 20 SPF
- Type 3 (sometimes burns, sometimes tans): 15-20 SPF
- Type 4 (burns minimally, always tans): 15 SPF
- Type 5 (rarely burns, tans profusely): 15 SPF
- Type 6 (never burns, deeply tans): 15 SPF
Other sunscreen tips:
- Pay special attention when applying sunscreen to your ears, nose, shoulders and tops of feet.
- When snorkeling, pay particular attention to the back of the calves and thighs.
Hats and Sunglasses
Hats: Hats should ideally have at least a 3" brim all the way around. Baseball caps or visors offer limited protection to the neck and ears. However, a baseball cap brim will shelter the eyes from about 50% of the sun's rays.
Sunglasses: Sunglasses are manufactured in accordance with ANSI (American National Standards Institute) standards and fall within the following 3 categories:
1. Cosmetic use: blocks at least 70% UVB, 60% UVA
2. General use: blocks 95% UVB, 60% UVA
3. Special Purpose Intense Sunlight: blocks 99% UVB, 98% UVA
For tropical use, try to find sunglasses rated "Special Purpose Intense Sunlight." Sunglasses should fit tightly to block UVR from the sides and have lenses large enough to cover the entire eye area, including eye lids.
Color is irrelevant in terms of UV ratings (UV coating is clear, and doesn't affect the color of the sunglasses).
Polarized sunglasses cut down glare, but don't block UV rays. Always look for the ANSI rating - even on polarized sunglasses.
At present, UV absorbing contact lenses do not have enough UV protection.
Structural Protection: Staying out of the Sun
- When possible, avoid the sun from 10 a.m to 2 p.m. when the ozone layer is weakest - and UVR the strongest.
- Avoiding the sun doesn't necessarily mean staying indoors, however. If on a boat, use the bimini top. Seek out shade on the beach (to avoid the intensification of UVR by the sun's reflection off the sand).
- Take a break and have lunch in a shady spot or in a restaurant
For more information, see The Importance of Sunscreen (Special thanks to Ms Rynder's youth group for this link.)