Aesthetic Medicine Specialist
The electromagnetic radiations of sunlight comprises of ultraviolet (UV-45%), visible (5%) and infrared (50%). UV radiations are classified into UVC, UVB UVA.
UVA radiations are further classified into UVA2 UVA1.
UVC rays are absorbed by the ozone layer hence do not reach the earth's surface. Out of the total rays reaching the earth's surface 95% are UVA rays and the rest are UVB rays.
UV exposure increases the tyrosinase activity and formation of new melanin and thus results in pigment darkening.UVB radiations penetrate into the epidermis. They can induce both acute as well as chronic effects.
Acute Effects- Erythema (redness), Edema (swelling), Pigment darkening
Chronic Effects- Immunosuppression and Photocarcinogenesis
UVA penetrates deeper into the epidermis. Exposure to UVA increases inflammation that leads to oxidative stress. Long term exposure to UVA causes skin ageing, wrinkling, sagging and immunosuppression. UVB radiations are called as burning rays whereas UVA are called as tanning rays.
Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, commonly from the sun. Common symptoms include red or reddish skin that is hot to the touch, pain, general fatigue, and mild dizziness. An excess of UV radiation can be life-threatening in extreme cases. Exposure of the skin to lesser amounts of UV radiation will often produce a suntan.
What is SPF?
Sunscreen protection factor, or SPF, was a concept created by Austrian scientist Franz Greiter. Pharmaceutical companies soon came up with lotions and creams to be used as effective photoprotection agents. SPF was given a numerical rating that tells us the degree of protection that is being provided by the sunscreen lotion.
How do sunscreens help?
Most sunscreens have a unique molecular structure that absorbs the high-energy ultraviolet (UV) rays and converts them to a less harmful energy level, thus preventing the harmful effect of the UV rays from penetrating the skin. Essentially, sunscreens are effective against either UVA (UV rays with a longer wavelength responsible for premature aging of the skin) alone, UVB (UV rays with a medium wavelength, associated with sunburn, cancer, and cataract formation) alone or both.
According a recently (2007) published article in the Indian Journal of Dermatology, Venereology, and Leprology, the ideal choice of sunscreens are those that effectively block both UVB and UVA rays, which is done with an SPF of 30 or greater. The ideal sunscreen, therefore, should have a high SPF rating and be non-toxic, water-resistant and, importantly, not too expensive!
Are sunscreens safe for children?
Yes. Not only are sunscreens safe for children over age 6 months, if used regularly in childhood they can prevent skin cancers from developing in later life. Recently, a researcher reported that if sunscreens were used regularly by children through the age of 18, there would be a 72% reduction in the cases of skin cancer later in life.
How should sunscreens be applied?
Sunscreens are very effective when used properly. Follow these guidelines to give yourself the most protection:
Apply the sunscreen at least 20 to 30 minutes before you go outdoors, whenever you will be exposed for 30 minutes or more.
Reapply sunscreen every 2 hours while you are outdoors, even if the product is labeled all-day. If you get wet or perspire heavily, reapply sunscreen more frequently.
Cover all exposed areas, including your ears, lips, face and back of your hands.
Don't skimp; apply a generous layer. Smooth it on rather than rub it in. A rule of thumb is that 45 ml (a shot glass) of sunscreen is needed to cover all exposed skin to attain the stated level of protection.
Women should apply sunscreens under makeup. If you wait to apply sunscreen until you hit the beach, you may already be perspiring, and moisture makes sunscreens less effective.
WHY SHOULD YOU WEAR SUNSCREEN ON CLOUDY DAYS?
Clouds filter out sunlight but not UV rays, the bad ones that cause aging and cancer. The Skin Cancer Foundation says that clouds block as little as 20% of UV rays — so on a cloudy day you're still getting up to 80% of the sun's harsh effects.
WHEN YOU'RE ESPECIALLY AT RISK
Some conditions make you extra-vulnerable to ultraviolet rays: snow and ice, lakes and other bodies of water, white sandy beaches, and even concrete. All of these surfaces can act as mirrors, bouncing the sun back at you and exposing you to more UV rays. Snow reflects up to 80% of UV rays, and sand reflects almost 20%. Sea foam reflects about 25%.