Choose a sunscreen with broad spectrum protection. All SPF products protect against UVB rays, which are the main cause of sunburn and skin cancers. But UVA rays also contribute to skin cancer and premature aging. Only products that pass a certain test can be labeled “broad spectrum” and display this UVA logo to indicate that they also protect against UVA rays. For areas of skin unable to be protected by clothing, sunscreen should be used as indicated in the instructions. Application should be made liberally to all uncovered areas, 15 - 30 minutes before sun exposure, with reapplication according to the instructions as directed. For greatest efficacy, use a high sun protection factor (SPF) sunscreen, preferably of 30 or more, also providing high levels of UVA protection.