Sunscreen and Sun Protection

Sunlight is a very strong energy source. It transmits this energy by radiation containing waves of vastly varying wavelengths. Some of these wavelengths are in the visible spectrum i.e. sunlight as we commonly know it. The heat we feel is from the infrared part of this spectrum of wavelengths and warms us up. Some low frequency waves i.e. gamma rays fall in the radioactive spectrum and pass clear through living matter and are absorbed by the earth’s crust. Some waves are in the frequency range of radio stations and can distort radio reception at times.

Ultraviolet A+B+C light falls in the near-visible range, but we do not sense any heat when they touch our bodies. They have the ability to penetrate the outer protective layer of our skins and then release their energy, where it causes damage to the sensitive living skin cells. This in return causes an inflammatory reaction in the skin i.e. redness.

It is therefore clear that the heat we feel when on the beach, is not related to how much ultraviolet we’re receiving (think of the sunburn you got on a clear, cold day whilst snow skiing).Also, if you wait until you’re red before applying sunscreen means that the skin has already responded to cellular damage from the ultraviolet light.

Sunscreen Protective Factor (SPF) was arbitrarily chosen as an indication of how much longer it takes for the skin to turn red when using the sunscreen , i.e. with SPF
15 , it will take the skin 15 times longer to turn red as opposed to skin that has not been covered by that sunscreen. Remember that redness is an indication of damage already done! This makes a strong case for applying sunscreen before going out of doors (not waiting for heat or redness) and topping it up if sweating or water sports wash it off your skin.

It has been well documented that sunlight exposure also retards our skin’s immune response ( the safety mechanism that deals with abnormal cells in our bodies) for up to 5 days after exposure .This happens regardless of whether there was redness or not.
This effect is used to treat i.e. psoriasis , a skin condition caused by excessive T-cell immune activity in the skin and psoriasis sufferers usually notice some improvement in the summer time. However , this retarded immune response is not good at dealing with damaged skin cells or cancer cells and probably enhances their growth.

Sunscreen is a second best sun protection tool. Remember that Slipping into clothing and Slapping on a hat comes before Slopping on sunscreen.