Higher sun protection factor (SPF) = better protection?

Sun protection factor (SPF) indicates how long one may stay in the sun without burning from UVB light, simply just multiplying the time you would normally burn in the sun without protection by the SPF of your product. For instance, 20 minutes produce redness on a light skinned individual. If he/she uses a product of SPF 15, then he/she can stay 15 x 20 = 300 minutes or 5 hours in the sun without burning. Individual with fairer skin normally requires products with higher SPF in order for them to get equal protection with those having medium or dark skin. Refer recommended SPF for different skin type.

So, how SPF of a product is determined? This can be achieved by applying the sunscreen to the skin of a volunteer and measuring how long it takes before sunburn occurs when exposed to an artificial sunlight source. Therefore, the product results will vary on different individuals.

But why only certain products provide UV protection while some others do not? The key ingredient in a sunscreen is either an organic chemical compound that absorbs UV light (such as oxybenzone) or an opaque material that reflects light (such as titanium oxide, zinc oxide), or a combination of both. The method of applying is also vital in order to get full protection. Contrary to the common advice that sunscreen should be reapplied every 2-3 hours, research has shown that the best protection is achieved by application 15-30 minutes before exposure, followed by one reapplication 15-30 minutes after the sun exposure begins. Further reapplication is only necessary after activities such as swimming, sweating, and rubbing.

Many of us have a wrong concept that sunscreen products with higher SPF give better protection to our skin and prevent it from further darkening, as compared to those with lower SPF. In fact, SPF over 30 does not provide significantly better protection. Also, bear in mind that tanning still occur with enough sun exposure. In addition, it does not protect us from UVA light which causes skin ageing as well as increases the risk of malignant melanoma, the most dangerous form of skin cancer. At the moment, there is no recognised standard rating available for the assessment of UVA filters.

As a summary, the best way to protect skin is a combination of staying in the shade when the sun is at its strongest, using clothing to cover up and SPF 15+ sunscreen. Sunscreen should not be used in isolation or as a way of staying in the sun for longer.