You've probably heard of UVA and UVB rays before, but do you know what these rays do? UV (or ultraviolet) light makes up 5 percent of the solar radiation we receive on Earth, and can be further broken down into three categories: UVA, UVB, and UVC. Of these rays, only UVA and UVB penetrate through Earth's atmospheric filter (and it's a good thing, because if UVC light were able to pass through, it would have devastating effects on our planet). UVA and UVB rays help sustain life on Earth, and are also the rays responsible for giving us a tan. These rays can also be replicated in indoor tanning equipment, which we'll talk more about later.
So, how do UVA and UVB work with our skin to create a tan?
The tanning process takes place in our skin's outermost layer: the epidermis. About 5 percent of the cells in your epidermis are special cells called melanocytes. When skin is exposed to UVB, melanocytes produce melanin – the pigment ultimately responsible for your tan. When that melanin absorbs UVA light, it oxidizes, or darkens, creating a suntan. When melanin is gradually built up in the skin, it creates a protective shield that protects against sunburn.
UVB is more intense than UVA, and while exposure to UVB is necessary to beginning and maintaining the tanning process, overexposure to this ray has the potential to result in a sunburn, which occurs when too much UV light exposure causes tiny blood vessels in your skin called capillaries swell or even burst. A sunburn is damaging to your skin and should be avoided at all costs. Thankfully, our skin has a natural barrier against sunburns: a suntan!
On a typical summer day, about 95 percent of the UV we receive outside is UVA, and the other 5 percent is UVB. These numbers are approximate and vary based on several factors including time of day, time of year, weather and altitude (but it should be noted that UVB levels fluctuate at a higher degree than UVA levels, which remain relatively unchanged throughout the year). This explains why you're more likely to get a sunburn at noon than you are at sunset.
Indoor tanning equipment is designed to replicate UVA and UVB produced by the sun in carefully controlled combinations. Unlike outdoor tanning, UV levels in indoor tanning equipment are generally fixed and do not change. This allows our trained staff to control your exposure and give you a great tan while minimizing the risk of sunburn, and ultimately increase your natural protection against a sunburn when you're outside and cannot control UV exposure!
Note: The above information has been adapted from the 2015 Smart Tan UV Tanning Certification Course.