By Margaret Hennessy, MD, pediatrician at Wheaton Franciscan Medical Group in Racine.
Summer is here and many of us are getting ready to get out in the summer sun. You may not realize it, but sunlight is actually radiation energy from the sun. It breaks down into ultraviolet A (UVA) and ultraviolet B (UVB) rays.
UVA rays (or long-wave rays) make up about 95% of the sun rays. It causes a tan but also ages the skin. UVA rays have this effect because they travel deep into the inner layer of the skin, called the dermis, and causes skin damage. UVA rays are constant throughout the day and the year. Tanning beds use mostly UVA, but all tanning beds do leak some UVB.
On the other hand, UVB rays cause sun burn. They travel only to the outer layer of the skin, or the epidermis. They occur mostly in the spring and summer months in Wisconsin and present year-round in southern states. UVB rays trigger the skin, along with the liver and kidney, to make Vitamin D. Both UVA and UVB rays cause skin changes that lead to skin cancer. You need protection from both types of rays. The best protection is to avoid excessive sun exposure. Here are some tips to do that:
- Watch the “burning hours," which are 10 am to 4 pm.
- Try to cover up with lightweight cotton clothes when you can and use umbrellas and hats.
- Use sunscreen under thin clothes and light-colored clothes. Children with darker skin may be less sensitive to the sun, but they are still at risk for sunburn and need protection too.
It's important to be extra careful with children. Sunburns earlier in life can lead to higher risk of skin cancer. It is estimated that 80 percent of sun exposure occurs before age 18 years. Overexposure to sun is the main cause for skin cancer. Sun exposure to the eyes can lead to cataracts. You and your children should wear sunglasses that provide 99 percent UV protection.
Babies under age 6 months should be out of the direct sunlight. Take advantage of tree shade, stroller canopies and sun umbrellas. But remember that water, sand and snow can all reflect sunlight. Sunburns can happen more rapidly when they are near. If you can not avoid sun exposure from them, then apply on small areas of the body such as face and back of hands.
Rules of sunscreen
Use a sunscreen that says “broad spectrum coverage” i.e. protects against UVA and UVB. For UVB protection, pick a sun screen that is SPF 15 or higher. Most kid products are SPF 45 or higher. Remember SPF rating only refers to UVB protection. SPF means sun protection factor. SPF= amount of time in sun to burn with sunscreen/amount of time in sun to burn without sunscreen. It does not specify the amount of time that you can spend in the sun without burning.
Everyone responds differently to the sun, so SPF is a relative measure of protection. For UVA protection there is a new rating system from the FDA-one star is low UVA protection, 2 stars is medium, 3 stars is high, and 4 stars is the highest protection available without a prescription.
- Apply 15-30 minutes before going outside so it has time to penetrate the skin. Reapply every 2 hours while in the sun. May need to apply every 30 minutes if the skin gets wet from sweating or swimming.
- Be generous with the dose of sunscreen. Adults should use 1-2 oz. (2-4 tablespoons) at a time.
- Use even on cloudy days — UVA rays can still get through the clouds. Clouds only block 20-40% of the rays.
- Avoid combination products that also contain bug repellent.
- Don’t forget ears, noses, lips and tops of feet. These areas may need more intense protection. Consider using the zinc oxide here.
- Follow expiration dates on the bottles as sunscreen does degrade over time. Store in a cool place. Cars in the summertime can get very hot so do not keep sunscreen there for a long time.
Here is an interesting note about the amount of sunscreen that you need to use to be effective: if you use only a quarter of the recommended amount of a product with SPF15, then the actual protection that your body sees is a SPF of only 1, i.e. no protection. If you used an SPF of 80 then you would only get SPF of 3 in the same example. Denim has a SPF of 1700.