The water resistance test is done in a lab, where the test subjects place their arm (with sunscreen applied to it) in a pool for either 40 or 80 minutes and the sun protection factor is tested before and after the arm was put in the water. an SPF 30 sunscreen (blocking 97% of UVB rays) needs to block UVA rays with the equivalent power of an SPF 10 (blocking around 89%). To pass, a sunscreen has to block at least 1/3 of the labelled SPF, e.g. So, when a sunscreen is tested to confirm broad spectrum protection (meaning that it provides appropriate protection against UVA) the protection is measured as a relation against its SPF. To make things even more confusing, the UVA test is related to the UVB / SPF test. All sunscreens from Suntribe offer broad spectrum protection and protect you against UVA rays, but definitely not all sunscreens do, so look out! If your sunscreen carries a label reading “broad spectrum” on it or you find a circle stating “UVA”, it means the sunscreen blocks an “appropriate amount” of UVA rays as defined by the regulating authorities. So how do you know if your sunscreen also blocks UVA rays? The answer is called broad spectrum protection. You can read more about UVA, UVB and UVC rays in our blog article about Why Daily Sun Protection is Important.Īs we just learned, the SPF only refers to the degree of protection from UVB. Therefore, it is hard to know whether you have been exposed to a risky amount of UVA rays. Unlike UVB rays, UVA rays are sneaky in the way that they do not make you tanned. Not good! Therefore it’s important to put on sunscreen if you’re planning on spending time in the sun. To put it simply, exposure to them can cause cancer by damaging the proteins that repair your DNA. Research shows UVA rays can lead to the creation of harmful free radicals in the skin. These rays reach the deepest layer of the skin called the “Dermis”. UVA rays have the longest wavelength and travel through the atmosphere almost uninterrupted. UVB rays affect the top layer of your skin. They are responsible for tanning your skin but too much exposure to them can lead to sunburn and consequently, skin cancer. UVB & UVB rays on the other hand do reach the surface, and that’s why you need sunscreen! UVB rays are only blocked in part by the atmosphere. UVC rays are absorbed by the ozone layer, so you don’t have to worry about them. UVB, UVA and UVC rays are all part of the ultraviolet light that travel towards earth from the sun.
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