Learn the Facts: The Ins & Outs of Sunblock, Sunscreen and SPF Protection. - Page

  • Posted on: Jun 24 2012
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The Ins & Outs of SPF protection

It is the season for  increased outdoor activity and your skin needs protection from the sun-that much is simple. However, knowing the ins and outs of SPF and the difference between physical and chemical sunblocks is more complicated. With a range of SPF products and sunblocks from $5 to $45 per 6 oz., it is important to be informed.

How does sunblock work?

Sunblock absorbs and/or reflects UVA and UVB rays therefore protecting your skin from damage. All sunblocks are given a Sun Protection Factor (SPF) rating which indicates how long a sunblock remains effective on the skin.

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What Is SPF?

SPF – or Sun Protection Factor – is a measure of a sunscreen’s ability to prevent UVB from damaging the skin. If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer – about five hours.

This number is often misinterpreted by the consumer. A higher SPF does not mean you can stay protected in the sun the entire day without re-applying.  The FDA has proposed a cap at SPF 30, with everything above that being 30+. Above SPF30, the percentage of UVB absorbed and overall protection of the skin increases only slightly, but people may misinterpret these higher SPF numbers as a higher level of protection or even a guarantee of all-day protection.

The American Association of Dermatology (AAD) recommends that a “broad spectrum” sunblock with an SPF of at least 30 that is applied daily to all sun exposed areas, then reapplied every two hours.

What is “broad spectrum” protection?

Every day the sun emits UVA and UVB rays that can lead to sunburns, premature skin aging and eventual skin cancers. Even on cloudy days up to 80% of UV rays can pass through the clouds according to the AAD. Broad Spectrum coverage protects against both UVA and UVB rays.

Why is there such a range of prices in Sunblocks and Sunscreens?

There are two categories of ingredients of sunblock- chemical and physical agents. Chemical agents work by absorbing the energy of UV radiation before it affects your skin. Physical agents reflect UV radiation before it reaches your skin.

There are two physical sun-blocking ingredients that are proven to be extremely effective- zinc oxide and titanium dioxide. Both provide broad spectrum UVA and UVB protection and are gentle enough for everyday use. Sunblocks containing these ingredients are more effective than chemical sunscreens, are generally more expensive, and are especially useful for individuals with sensitive skin as they rarely cause skin irritation.

Most chemical sunscreens are composed of several active ingredients which each block a narrow region of the UV spectrum, with no single chemical ingredient blocking the entire UV spectrum. These chemical sunscreens are often less effective than those containing physical sun-blocking ingredients, are more affordable, but can cause irritation to the skin.

Here is a quick guide to keep you safe in the sun.

Sun Protection Facts:

  • Repeated exposure to UVA and UVB rays causes damage to the cells of the epidermis resulting in the production of wrinkles, age spots and actual skin cancers.
  • Cumulative sun damage leads to the loss of subcutaneous fat causing the skin to lose tone and sag.
  • Physical Sun blocks (Zinc Oxide & Titanium Dioxide) provide broad spectrum protection blocking both UVA and UVB rays and are gentle enough for daily use.
  • Chemical Sunscreens are combinations of many active ingredients with no single chemical ingredient blocking the entire UV spectrum (unlike physical sun blocks)
  • Sunblocks are only effective if you use them appropriately.
  • Apply 15-20 minutes before sun exposure to allow a protective film to develop.
  • Re-apply every 2 hours or after excessive sweating or swimming
  • Use enough sunscreen to generously coat all exposed skin.
  • Try to avoid sun exposure between10 a.m. to 3 p.m., the strongest sun of the day.
  • Seek shade when your shadow is shorter than you are.
  • Protect your skin by wearing long sleeves, pants, a wide-brimmed hat, and sunglasses whenever possible.
  • Check your cities UV index to determine your risk.

To your skin health,

Dr. Richard Asarch, MD



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