~ by Dr. Carol Bridges
One ounce is considered an appropriate amount to cover the exposed areas of the body properly. Be sure to apply a generous amount, paying close attention to the face, ears, hands, and arms. Don’t forget that your lips can get sunburned too, so apply lip balm that also contains sunscreen.
Sunscreen should be reapplied every two hours, or after swimming or perspiring heavily. Even “water resistant” sunscreens lose their effectiveness after an hour in the water. Sunscreen can also be rubbed off, so be sure to reapply it if you’ve dried off with a towel.
The American Academy of Dermatology suggests that everyone should wear sunscreen. You should wear it every day if you’re going to be in the sun more than 20 minutes. In fact, sunscreen used on a regular basis actually allows some repair of damaged skin.
Be sure to use a broad-spectrum sunscreen that screens both UVA and UVB rays. Avoid PABA, which only protects against UVA rays. Instead, look for these ingredients: benophenones, oxybenzone, titanium dioxide, zinc oxide, avobenzone, and ecamsule.
Sun Smarts: How to Protect Yourself.
Sunlight consists of two types of harmful rays: UVA rays and UVB rays. UVB rays are what burn you; they cause sunburn and skin cancer. UVA light penetrates deeper into the skin, but can contribute to skin cancer. Both UVA and UVB rays can cause suppression of the immune system, which can further increase your risk of skin cancer.