Choosing the right one
For extended periods out of doors always make sure you choose a sunscreen with an SPF (sun protection factor) of 30+. Further it must offer broad spectrum protection – effective against UVA and UVB – and be fragrance free. Water resistance is also a vital factor. Look for sunscreens which are water resistant for two to four hours.
Where sunscreen properties are built into cosmetic products such as moisturisers, lipsticks and lip balms, this is known as a secondary sunscreen. These normally offer SPF levels of 10 - 15. They give useful UV protection for short periods out of doors but are no substitute for the protective qualities of a primary 30+ sunscreen for prolonged outdoor activities.
Sunscreens come in a variety of forms; creams, matte creams, lotions, milks, gels, roll-ons and spray mists. Gels, milks and lotions are particularly appropriate for people with oily skin. Women may favour matte creams which have a consistency similar to foundation. Spray-ons and mists are often preferred by outdoor workers and people playing outdoor sports as they leave no residue on the hands.
The average skin starts to burn and incur damage after 10 minutes continuous exposure to high intensity UV radiation. For some, skin damage occurs sooner, for some later, but experience shows that 10 minutes is a sound average figure. Thus the skin's natural protection is effective against UV radiation on average for 10 minutes. The SPF number indicates how much longer protection a sunscreen offers expressed as a multiple of the average natural skin protection period. Thus a sunscreen with an SPF of 30 theoretically offers 30 times the average natural skin protection which is 300 minutes. However sunlight may alter the active sunscreen ingredients so that they lose their effectiveness. Therefore it is advisable to reapply every two hours.
It is difficult to provide an accurate and universal guide for re-application. People with pale or Celtic type skins need to reapply an SPF 30 at considerably less intervals than 300 minutes. And of course sunscreens should always be applied immediately after bathing or after a period of perspiration. Some sunscreens claim SPF 30+ which indicates their sun protection level is above 30. This could be 31 or 60, however 30+ is the maximum they can claim under Australia’s regulations.
Application and usage
The level of SPF protection offered by a sunscreen can only be gained by applying it in sufficient volume.
Full body coverage demands around 35mls of sunscreen to achieve effective all-over UV protection. If a lower volume of sunscreen is applied this will lower the actual Sun Protection Factor achieved. In most cases cosmetic products are applied in volumes lower than sunscreens. Thus the SPF actually achieved is less than the potential claimed for the secondary sunscreens. As the maximum potential for secondary sunscreens is normally in the SPF 10 - 15 range it is often the case that people are getting much less protection than they think they are.
The distribution strategy for this requires on dab (teaspoonful) of sunscreen to be applied to seven body points and then spread around the following areas
- Face, ears front and back of neck
- left shoulder and arm
- right shoulder and arm
- left leg
- right leg
Sunscreens should be applied lavishly and not worked into the skin if it is to meet the label claims. They should be applied to clean, dry skin around fifteen minutes before sun exposure, and to be really on the safe side, should be applied every two hours.