Johns Hopkins All Children's Hospital

Sun Safety

One blistering sunburn during childhood or adolescence can double a person’s chance of developing skin cancer.

Harmful Effects of Too Much Sun Exposure

Twenty-five percent of lifetime sun exposure occurs before the age of 18 and 50 percent of children will have their first sunburn or suntan in the first two years of life no matter their skin tone.

Skin cancer is the most common form of cancer in the United States with melanoma being the most dangerous type. One blistering sunburn during childhood or adolescence can double a person’s chance of developing melanoma.

Sunscreen 101

There are two FDA approved types of sunscreen:

  • Chemical: absorbs UV radiation
  • Physical: blocks UV radiation and contains zinc oxide and titanium oxide

There are two types of UV rays—UVA and UVB. SPF measures a sunscreen’s ability to protect against sunburn, which is primarily due to UVB rays. SPF does not measure protection from UVA rays. Products labeled as broad-spectrum absorb both types of UV rays. Protection against both types is important because both can lead to skin cancer.

Choosing SPF

Higher SPF doesn't always mean better. The difference in UV protection between SPF 30 and SPF 50 is just 1 percent, so choose something in that range and stick with it.

  • Water Resistant Sunscreens: Maintain their SPF after 40 minutes of swimming or sweating
  • Very Water Resistant Sunscreens: Maintain their SPF after 80 minutes of swimming or sweating

Sunscreen Application Tips

Apply sunscreen 15 to 30 minutes before sun exposure.

  • Most people need about 1 ounce (or 6 teaspoons) of sunscreen to fully cover their body
  • Reapply sunscreen at least every two hours
  • Reapply sunscreen after swimming or after sweating

Choose sunscreens that say:

  • SPF 30 or higher
  • Broad-spectrum protection
  • Water resistant

Protect Yourself in 5 Ways from Skin Cancer

  1. Slip on sun protective clothing
  2. Slop on SPF 30 or higher sunscreen
  3. Slap on a wide brim hat
  4. Seek shade when possible
  5. Slide on sunglasses

Other Ways to Keep Your Skin Protected

Participating in outdoor activities is great. If you can, you should avoid the sun during peak hours, which are between 10 a.m. and 2 p.m. If you do spend time outdoors during peak hours, try to seek shade when possible.

Sun protective clothing includes a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses. Tanning beds are not safe. Tanning beds use UVA rays, which can be even more damaging than UVB rays.

Sand, water and snow can reflect up to 85 percent of sunlight so use extra caution. Remember that even if it is cloudy outside 80 percent of the sun’s rays still reach the Earth!

Still have questions? Come see us.

Our adolescent medicine team has special training to meet the unique needs of teens. We're here to help guide you and answer any questions you might have.

The information here is not intended to be nor should be used as a substitute for medical evaluation or treatment by a health care professional. This publication is for information purposes only and the reader assumes all associated risks.

Content experts: Maria Leszczynska, M.D., Joanne Alcin, M.D., and Jasmine Reese, M.D., M.P.H.


  1. American Academy of Dermatology. Sunscreen FAQs. Retrieved from “Sunscreen FAQs.”  American Academy of Dermatology.
  2. American Academy of Pediatrics. Sun Safety.
  3. Sophie J. Balk, the Council on Environmental Health Section on Dermatology. Ultraviolet Radiation: A Hazard to Children and Adolescents Pediatrics. Mar 2011, 127 (3) e791-e817; DOI: 10.1542/peds.2010-3502
  4. Melissa Long. Sun Exposure. Pediatrics in Review. Sept. 2017, 38 (9) 446-447; DOI: 10.1542/pir.2016-0233