Bloomington / Normal, IL

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What’s Your Sunscreen IQ?


Submitted by Doug Leone, MD, and Adrienne Schupbach, MD, Dermatology and Mohs Surgery Institute

Skin cancer is the most common form of cancer in the United States. The exposure to skin-damaging ultraviolet (UV) rays from the sun is the most common cause. Thankfully, skin cancer is largely preventable through a broad sun protection program which includes the use of sunscreen. Even people that diligently apply sunscreen every day may not know all the facts about sunscreen and how it works to protect your skin. Take this brief quiz and see how you do!


  1. A SPF 30 sunscreen offers twice as much protection as SPF 15.  
        o TRUE  o FALSE

  2. Sunscreen should be applied in a thin layer over all exposed parts of the body.  
        o TRUE  o FALSE

  3. You need to wear sunscreen on a cloudy day.  
        o TRUE  o FALSE

  4. You only need to worry about protection from UVB rays.   
        o TRUE  o FALSE

  5. When using a water-resistant sunscreen, you can safely stay in the water for 80 minutes.  
        o TRUE  o FALSE

  6. Darker-skinned people don’t need sunscreen.  
        o TRUE  o FALSE

  7. Sunscreen should be applied about 30 minutes before you go out in the sun.  
        o TRUE  o FALSE

  8. The recommended sunscreen ingredients are titanium dioxide and zinc oxide.  
        o TRUE  o FALSE

  9. Sunscreen is the best way to protect the skin from the harmful rays of the sun.  
        o TRUE  o FALSE


  1.  FALSE. While this seems logical, that isn’t how SPF works. SPF stands for Sun Protection Factor. SPF 15 blocks about 94 percent of the UVB rays, and SPF 30 blocks about 98 percent. SPF above 50 offers negligible additional protection. Even an SPF of 100 does not block 100 percent of the harmful rays.
  2. FALSE. Most people do not apply enough sunscreen. It should be slathered on and rubbed in. A general recommendation is that an average size person needs at least a shot glass size amount to adequately cover exposed skin.
  3. TRUE. 80 percent of the sun’s rays will pass through clouds. Be especially careful if it is a cloudy day and you are around sand, water, or snow.
  4. FALSE. The sun emits both UVA and UVB rays. UVA rays penetrate the skin on a deeper level and are the most dangerous in terms of causing skin damage, wrinkles, and premature aging. UVB rays damage the surface of the skin and cause sunburn. Both types of UV rays may cause skin cancer. All sunscreens are “broad spectrum,” which means they offer protection against both types of light. The SPF rating refers primarily to protection from UVB rays, so it can be difficult to know how much protection you are getting from UVA rays.
  5. TRUE. However, remember that there is no such thing as a waterproof sunscreen. 80 minutes is the longest that you should go before re-applying. Re-apply more often if getting in and out of water, after toweling off, or when sweating.
  6. FALSE. It’s true that fair-skinned people are more susceptible to burning. However, basal cell carcinoma is the most common type of skin cancer and it affects people of all races and skin tones. Even if your skin doesn’t burn, it is still being exposed to harmful, cancer-causing rays from the sun.
  7. TRUE. You need to allow time for the product to dry and interact with the skin for it to be most effective.
  8. TRUE. Titanium dioxide and Zinc oxide are the only ingredients that work by physically blocking the sun’s rays from the skin. For this reason, they are recommended for babies over six months old and young children. All other sunscreen ingredients are chemical blockers that work by penetrating the skin. While such chemical ingredients are safe, since they do penetrate the skin, some people prefer to avoid them.
  9. FALSE. Sunscreen is one important part of an overall strategy to protect your skin from the sun. It’s important to also stay out of the sun in the middle part of the day, wear a hat and sunglasses, and be sure to have a routine skin examination with a dermatologist to detect any possible sign of skin cancer in the earliest stages.

For more information, you may contact the Dermatology and Mohs Surgery Institute at 309-451-DERM (3376) or Dr. Leone and Dr. Schupbach, both residents of Bloomington, are board-certified dermatologists, specializing in medical and cosmetic dermatology, including the treatment of skin cancer, moles, acne, rashes, warts, and all skin disorders.

Dr. Leone is one of the few Mohs-trained surgeons in the area. Their practice is located at 3024 E. Empire St. 2nd floor, in the Advocate BroMenn outpatient center.