How Does Sunscreen Work?

Our skin is sensitive to the effects of sunlight, which is strong enough to cause major changes in the skin condition. While many people think the sun only provides us simple light and warmth, the truth is much more complex. Sunlight contains different “types” of light and at least one of these can be quite harmful to the body.

All light is measured in wavelengths and sunlight is no different. It contains three distinct types of ultraviolet light – they have different wavelengths. In basic terms, these three have been divided into UV-A, UV-B and UV-C. The first has wavelengths longer than the other two.

Scientists have found that UV-A penetrates rather deeply into the human skin. UV-B and UV-C don’t penetrate as deeply, but UV-B is known to be the cause of sunburn, since it affects the outer layer of skin.

If we are going to spend an extended period of time in the sun we should protect our skin from the sun’s rays. Commercially available sunscreen provides some protection. These products are rated by SPF – Sun Protection Factor. The rating gives us some guidelines as to how much the lotion will limit the UV-B rays in sunlight. Higher SPF numbers mean that these rays won’t burn the skin as much as they would if we used no sunscreen or one with a much different SPF number.

Sunscreen products are made from various chemicals and organic ingredients, most of which are intended to block the sun or actually absorb some of the harmful rays. Putting a layer of the right type of sunscreen lotion on the skin is a good idea for anyone who will be exposed to sunlight for an extended period. In some sunscreen products, the manufacturer uses organic materials that actually absorb some of the UV-B rays before they get to the skin. This is known in the industry as the “filter” and “dispersal” capacity of the compounds.

Other chemicals used in sunscreen products actually block certain rays in sunlight, so the possibility of the skin absorbing UV rays is limited. That’s why people shopping for sunscreen products will encounter the term sun “block.” Zinc oxide is widely recognized as an effective blocker of UV rays in sunlight. This is the key ingredient in the thick, white lotions that you may see on the nose and other areas of the body when at the beach. Tests have shown that this chemical can, in some cases, completely reflect/block certain UV rays. It’s probably best to begin with a 15 SPF and go up, depending on how much protection you need.

Many sunscreen products are sold for the purpose of blocking or dispersing UV-B rays but are not intended to protect against the longer wavelengths of UV-A rays. For this protection a person needs a “full-spectrum” product that can protect against both UV-B rays and even UV-A rays.

When choosing sunscreen products, read the labels carefully to see what type of protection the item provides. Get a higher number if possible and re-apply ever two hours or so to maintain proper protection.

Written by Lucas Beaumont

Generalist. Wikipedia contributor. Elementary school teacher from Saskatchewan, Canada.

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