Updated: May 7, 2019
Recently, the finding that increased likelihood of skin cancers is relative to sun exposure instilled a change in the general public as avoiding sun exposure and regular application of sunscreens. With regard to application of sunscreens, a few points have to be remembered to ensure the right technique is employed. What use would scribbling be if the right artistic patterns are not employed? So let's have a look at the correct technique for sunscreen application.
Sun Protection Factor
The idea of Sun Protection Factor or SPF has often been likened to a scale with regard to UV protectivity and duration of protection offered however this is not entirely so.
In theoretical terms, SPF is calculated as the amount of time required for a sunburn to occur after applying sunscreen divided by the time for a sunburn to occur without sunscreen. An SPF of 30 would relate to 30 times protection from UV exposure in terms of quota and duration of UV exposure. However, studies have shown other factors to have an impact such as the time of day, weather, type of skin, amount of sunscreen applied and technique employed.
In terms of percentage of UV rays blocked by adequate sunscreen use, the values are as follow
SPF 15 blocks 93% of UV-rays
SPF 30 blocks 97% of UV-rays
SPF 50 blocks 98% of UV-rays
SPF 70 blocks 98.3% of UV-rays
SPF 100 blocks 99% of UV-rays
As you can see, the difference is only marginal after SPF 30 but it is not at all marginal cost wise. This is why dermatologists usually recommend an SPF of 30 or 50 depending on the skin type, risk of sun exposure and amount of damage present.
Importance of Formulations
Sunscreens are available as creams, lotions and gels and these are not chosen according to fancy but depends on the skin type. The prime factor that predicts the appropriate formulation is oily or dry skin. In oily skin, gel or lotion formulations are ideal as they are oil-free and thus are not responsible for bouts of acne. In dry skin, cream formulations are ideal as they contain an oil phase and therefore produce a moisturizing effect.
Gel and Cream formulations have a longer stay-on period whereas lotions easily come off on rubbing or sweating. Novel sunscreens are on the horizon wherein the formulations ensure safe delivery of medicinal products to the cells to exert the photoprotective effect.
Method of Application
The technique of application differs with respect to the formulation and SPF. With respect to cream and gel formulations of an SPF of 30, the correct technique is to apply a pea sized volume of the sunscreen all over the face while in case of lotions a larger amount is necessary.
People often mistake sunscreens to be effective the moment they are applied though reality is that the medicaments contained in a sunscreen require approximately 15-30 minutes to bring about the photoprotective effect. Thus dermatologists would advice to apply sunscreens 20 - 30 minutes prior to stepping out.
Another misunderstanding is that sunscreens work all day long however this is not so. When tested in a chemical lab undertaking all precautions, possibly it may be true however when exposed to humidity, pollutants, winds, make-up products and other things that we are commonly in contact with, the sunscreen chemically wears down resulting in there being no protective effect at all. Studies have shown that sunscreens are effective for 2 hours after application and it is thus proper to reapply the sunscreen every 3-4 hours.
With all this detail about sunscreens, it has to be kept in mind that UV rays can pass through glass and are present even on cloudy days. Therefore it is always better to protect your skin from these harmful rays by using a sunscreen of your choice in the correct formulation whenever stepping out or vulnerable to long-term sun exposure through windows.
This information is brought to you by Specialized doctors in Al Arif Heart and Children Medical Center, Al Mujarrah, Sharjah, UAE. Keep yourselves fit as a fiddle.