Don't forget to apply the sunscreens under sheer clothing, especially if likely to get wet, as the sun's rays can penetrate. Use a sunscreen stick or lip balm for vulnerable areas such as the lips, scalp, nose and ears. If you have sunscreen left over from last year, it's probably OK to use it if it hasn't been in direct sunlight or heat. The rule of thumb is that you will need about 1 oz per application to appropriately cover your skin. Beware of reflected light .
Sunlight is reflected off sand, cement, and snow.
Even on cloudy days, eighty percent of the sun's radiation still reaches the ground. Altitude and latitude are important factors. Also, the closer you are to the equator, the stronger the sun's rays. Watch for raised growths, itchy patches, non healing sores, changes in moles or new colored areas. One very bad, blistering sunburn during childhood can double the risk of developing melanoma, the most serious of all skin cancers.