November 9, 2017
Beyond violet is what Ultraviolet (UV) means in Latin – just beyond what our eyes can see on the violet side of the rainbow.
The sun is our main source of ultraviolet, with the more dangerous wavelengths of ultraviolet absorbed by the atmosphere, particularly the Ozone Layer. The sun has made life on earth possible, giving us food, energy and even joy when scientists discovered the medical phenomenon of winter depression related to the lack of sunlight. But one can have too much of a good thing. Ultraviolet is also responsible for tanning and sunburn, two things that cause us to develop skin cancer as it can cause direct DNA damage. Collagen and vitamin A are also not spared by UV, bringing aging to our skin. There are 3 main types of UV rays, UVA, UVB and UVC. Both UVA and UVB rays can damage skin and cause skin cancer but UVB rays are a more potent cause in at least some skin cancers. UVC don’t get through our atmosphere and are not normally a cause of skin cancer. While UVA rays don’t cause sunburn, they penetrate deeply into skin and cause wrinkles. The Environmental Protection Agency estimates that up to 90% of skin changes associated with aging are really caused by a lifetime’s exposure to UVA rays.
What a sunscreen does
A sunscreen’s basic function is to protect the skin from the sun’s harmful rays. Sunscreens work by reflecting, absorbing, and scattering both UVA and UVB radiation to provide protection against both. In other words, by using a sunscreen, you can protect the skin from premature aging and damage that may lead to skin cancer.
Filters, the active ingredients that provides protection in sunscreens comes in two forms, mineral and chemical, with the latter being more commonly used recently. Chemical sunscreens typically include a combination of two to six of the following filters: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Mineral sunscreens use zinc oxide and/or titanium dioxide as filters. It is also common to find sunscreen products combining mineral zinc oxide with chemical filters.
Mineral or Chemical?
Mineral sunscreens work by performing as a physical barrier on top of the skin to reflect harmful UV rays away from the skin, preventing them from making their way to the skin’s deeper layers. Chemical sunscreens actually absorb the UV rays. However, chemical sunscreens actually soak through the skin, allowing UVA rays to penetrate the skin’s deeper layers and wreak damage. In terms of the level of protection, chemical sunscreens are therefore inferior to mineral sunscreens. To add, the majority of chemical sunscreens provide only UVB protection but mineral sunscreens protect the skin against both harmful UVA and UVB rays, ie. Broad spectrum protection. This is why many sunscreen products combine both mineral filters with chemical filters. It is also noteworthy that, among the mineral filters, titanium dioxide does not protect against UVA rays as well as zinc oxide, and should be used along with zinc to provide best UVA and UVB defence.
Apart from offering a smaller spectrum of coverage, chemical sunscreens can have negative effects on the body. Laboratory studies indicate that some widely used chemical UV filters may mimic body hormones, causing hormonal disturbances and health problems related hormonal disruption. Some chemical filters in chemical sunscreens have also been found to be more likely to provoke allergic reactions in individuals with sensitive skin. Mineral sunscreens, on the other hand, tend to be less irritating to skin, and is recommended over chemical sunscreens for easily-inflamed or sensitive skin types.
The next time you shop for sun protection, be sure to look at the ingredients list. It is common for some brands to use the word “mineral” on their labels but actually contain a combination of mineral filters and the undesirable chemical filters.
5 Qualities that make a better sunscreen
Using your sunscreen effectively
Which SPF suits me?
Purchasing a better sunscreen is just the first step to ensure protection from UV damage. The next step is to use it properly. In order to get the most from your sunscreen, choose the most appropriate Sun Protection Factor (SPF) for your skin. SPF tells you how much longer you could expect to be exposed to UVB before burning compared to no sunscreen use. Someone with fair skin can stay in the sun 10 minutes before burning without sunscreen. Someone with dark skin can stay in the sun 20 minutes before burning without sunscreen. Any skin tone in between will take 15 minutes before burning without sunscreen. Therefore a sunscreen with SPF 20 will allow someone with fair skin to stay (20 X 10 = 200 minutes) in the sun before burning.
Generally speaking, a sunscreen with above SPF 15 should provide adequate protection as long as it is being used correctly. Sunscreens with SPF 50 or more offer a safety margin, since most people don’t apply sunscreens as heavily or as often as they should.
Just how much is enough?
The American Academy of Dermatology recommends applying one ounce (about a palm-full) to all exposed skin. It takes 20–30 minutes for sunscreen to be absorbed by the skin and it can be rubbed off very easily, so apply it at least half an hour before going out in the sun and don’t forget to reapply every two hours if staying out in the sun for more than an hour during the day. Re-apply immediately after swimming, excessive sweating, or if rubbed off by clothing or towelling even for products that are water resistant. Lastly, don’t forget SPF your lips too.
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