June 23, 2014 1:28 pm

Ask the Pros- Dr. Kris Gast

Posted in: Ask the Pros

Q: What does the term SPF mean?

A: SPF stands for the “Sun Protection Factor.” The SPF rating, mainly a measure of UVB protection, shows how long protection from the sun’s UVB rays lasts with an application.  The higher the SPF, the longer the protection will last.

For example, a sunscreen with an SPF of 15 will delay the onset of a sunburn in a person who would otherwise burn in 10 minutes to burn in 150 minutes. Therefore, an application of a SPF 15 sunscreen would allow a person to stay out in the sun 15 times longer.

However, many sunscreens do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma. Thus, people using sunscreens may be exposed to high UVA levels without realizing it. For the best protection, the use of broad-spectrum (UVA/UVB) sunscreen is recommended.


Q: What does UVA and UVB stand for in regards to sun exposure?

A: UV is short for ultraviolet, part of the sun’s light that is invisible to the human eye. UVA rays are those that penetrate the skin deeply and are responsible for tanning.  Causing skin cells to age, UVA rays give sun worshipers wrinkles.  Exposure to UVA rays in large doses can also cause skin cancer.  However, UVB rays are considered the more “dangerous” of the sun’s rays and are most commonly linked to skin cancer. UVB Rays are the rays you can blame when you get a sunburn. Unlike UVA rays, these rays aren’t always the same strength year round. They are more prevalent in the summer months; however, they are able to reflect off of water or snow.

Q: What kind of skin cancers are there?


A: The three major types of skin cancers are squamous cell, basal cell, and melanoma.  Squamous cell skin cancers, making up 20% of all skin cancers, tend to be on areas of sun-exposed skin, such as the face, eyes, lips, arms, and back of hands.  With over 1 million new cases diagnosed in the U.S. each year, basal cell carcinoma is the most common cancer in humans.  These cancers grow slowly and usually appear on the face and neck area.  Melanoma derives from special cells in the skin and can occur anywhere on the body.  Caught early, most melanomas can be cured with relatively minor surgery. However, melanoma can be more serious than the other forms of skin cancer, because it may spread (metastasize) to other parts of the body and cause serious illness and death.


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