10 Harley Street, London W1G 9PF
EMAIL: info@harleystdermatology.com
CALL: 0207 299 0392

Facts About Sunscreen

What is an SPF?

The Sun Protection Factor (SPF) displayed on the sunscreen label ranges from 2 to as high as 50 and above and refers to the product's ability to screen or block out the sun's harmful rays. For example, if you use a sunscreen with an SPF 15, you can be in the sun 15 times longer that you can without sunscreen before burning.

How do you select a sunscreen?

With so many brands of sunscreen available, selecting the right sunscreen can be difficult. These tips may help you in making your selection:

  • If you are fair-skinned and sunburn easily, you should select a sunscreen with a high SPF to provide additional protection. Using a cream, oil or lotion is a matter of personal choice, but keep in mind that most oils do not contain sufficient amounts of sunscreen. All sunscreens need to be reapplied, so follow the guidelines written on the sunscreen bottle. Gel sunscreens tend to sweat off and, therefore, need to be reapplied more frequently.
  • Choose a "broad-spectrum" sunscreen that protects against UVB and UVA radiation.
  • Look for a sunscreen that is "waterproof" or "water-resistant," especially if you participate in outdoor physical activity.

Is there a difference between "waterproof" and "water-resistant?"

How well the sunscreen stays on the skin after swimming, bathing or perspiring is just as important as the SPF level. A product is usually considered "water-resistant" if it maintains its SPF level after 40 minutes of water exposure. A product is usually considered "waterproof" if it maintains its SPF level following 80 minutes of exposure to water. If you participate in outdoor recreational activities including swimming, you may want to choose a waterproof sunscreen.

What is the difference between sunscreen and sunblock?

Sunscreens can be classified into two major types: chemical and physical. Chemical sunscreens contain special ingredients that act as filters and reduce ultraviolet radiation penetration to the skin. These sunscreens often are colourless and maintain a thin visible film on the skin. These sunscreens usually contain UVB absorbing chemicals and more recently contain UVA absorbers as well.

Physical Sunscreens, most often referred to as sunblocks, are products containing ingredients such a titanium dioxide and zinc oxide which physically block ultraviolet radiation (UVR). Sunblocks provide broad protection against both UVB and UVA light. There is sometimes a reluctance to use sunblocks, because they are often messy, visible and do not easily wash off. However, some new zinc oxide products are available in brightly coloured preparations. The amount of sun protection these sunblocks provide, while potentially high, cannot be quantified in the same manner as sunscreen SPFs. Physical sunscreen is recommended for individuals who have unusual sensitivity to UVR and/or are Skin Types I and II.

When should you use a sunscreen?

Sunscreens should be used daily if you are going to be in the sun for more than 20 minutes. Most people will receive this amount of sun exposure while performing routine activities. They can be applied under makeup. There are many cosmetic products available today that contain sunscreens for daily use because sun protection is the principal means of preventing skin cancer and premature ageing.

Since the sun's reflective powers are great – nearly 20% on sand and 80% on snow - don't reserve the use of these products for only sunny summer days. Even on a cloudy day, 80% of the sun's ultraviolet rays pass through the clouds. Skiers beware, ultraviolet radiation increases 4% for every 1,000-foot increase in altitude.

You should apply sunscreen to your dry skin 30 minutes BEFORE going outdoors. Pay particular attention to your face, ears, hands and arms. Apply sunscreen liberally using one ounce to completely cover your body. Be careful to cover exposed areas, a missed spot could mean a patchy, painful sunburn. Lips get sunburned too, so apply a lip balm that contains sunscreen with SPF 15 or higher. Sunscreens should be applied in the morning and reapplied after swimming or perspiring heavily. Remember, waterproof sunscreen begins losing effectiveness after 80 minutes in the water, so reapply sunscreen before this time, especially if you have towel-dried for maximum protection.