For sunscreen use:
 
  apply liberally 15 minutes before sun exposure 
   use a water resistant sunscreen if swimming or sweating 
    reapply at least every 2 hours 
    Sun Protection Measures. Spending time in the sun increases your risk of skin cancer and early skin aging. To decrease this risk, regularly use a sunscreen with a broad spectrum SPF of 15 or higher and other sun protection measures including:
    limit time in the sun, especially from 10 a.m. – 2 p.m. 
     wear long-sleeve shirts, pants, hats, and sunglasses 
     
   children under 6 months: Ask a doctor