SPF in its abbreviated form, sun protection factor is relevant and important factor especially now that the searing heat of the sun is beating on us, we who live at the belt of the globe which is the equator. SPF in its simplest term tells us how much protection it provides the person against solar rays of the sun, depending on how much melanin or the major skin pigment is deposited on the entire surface of the human body.

Sun rays maybe classified as UVA, UVB and UVC, which other books call UV alpha, UV beta and UV gamma respectively. UVA is the ageing type or the wrinkle forming sunray because of its ability to dry up the skin. UVB is the burning or the so-called penetrating solar ray, i.e., it is capable of passing thru the three layers of the skin- epidermis or outermost layer, dermis- middle and thickest layer and the subcutaneous layer or the tela subcutanea which is the fatty layer, which in very cold climes, serves as insulator of heat.

Our country, being equatorial in location, gets a lot of sunshine, which on the good side, provides us with natural vitamin D3 or cholecalciferol, when we have those early morning sunbaths. On the negative side, we are aware of the harmful effects of ultraviolet rays. Fortunately , high up in our atmosphere is the ozone layer, made of thick O3, which serves as filter of UVA and UVB, which greatly decreases the amount of solar rays reaching the surface of the Earth. The more harmful and destructive UVC or UV gamma are deflected or bounced back into ionosphere or the melanosphere, in short, very little amounts or none at all reach the planet. However, we all know that use of CFC or chlorofluorohydrocarbons- in air conditioners, aerosols, in chemical industries - has eroded some of the protective ceiling of the ozone layer.

Having said that, with the Filipino penchant for running to the beach or riverside for that much-refreshing cool dip in the scorching heat of summer, sunscreens and sunblocks become a must in their picnic bag. As a rule, the fairer the skin is, the higher is the SPF number, and conversely, the darker the skin, the lower is the SPF number. Most dermatologists suggest SPF 15 for majority of Filipinos, with obvious reference to our being member of the brown Malay race. Of course, the mestiso/mestiza needs a higher SPF number. What to do with the number? Multiply the SPF number with 10- number suggested for people with fair skin- so SPF 15 x 1O is 150, meaning the person has sun protection for 150 minutes. It must be emphasized however, that sunblocks and sunscreens must be re-applied every now and then, if the person decides to have more fun under the sun.

There are many choices of sunscreens s. Choose from non-allergenic, non-oily and non-fragrant varieties. Notwithstanding the supposed benefits of sunblocks, it would be prudent to avoid the sun from 10 a.m. to 3 p.m. - which admittedly is difficult to follow, especially for avid beachcombers and sun worshippers or those who want to flaunt their natural tan to envious neighbors and friends.

Enjoy the summer. Lest you forget. Drink a lot of water.

Next Week: Skin Cancer