SPF measures sunscreen protection from UVB rays , the kind that cause sunburn and contribute to skin cancer. SPF does not measure how well a sunscreen will protect from UVA rays, which are also damaging and dangerous. Higher SPFs don't provide much more protection.
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If you buy something through a link on this page, we may earn a small commission. How this works. With such a wide range to choose from, how can we know which is the best option? Sun protection products are sold because they protect against cancer and other health conditions. The sunscreen innovation act SIA governs how this must be done.
I wish I had a short, simple answer to this question, but it is a little complicated. So I can walk you through a few important points that will make you more of a sun protection expert, too! Ultraviolet light is invisible to humans, because it has shorter wavelengths than the light we can see. Within the UV spectrum , there are two types of rays that can damage the DNA in your skin cells and lead to skin cancer. An SPF of 50 allows about 2 percent of those rays through. That may seem like a small difference until you realize that the SPF 30 is allowing 50 percent more UV radiation onto your skin. But , real life is not like a lab. In real life, products with very high SPFs often create a false sense of security. People who use them tend to stay out in the sun much longer.
SPF is a measure of how much solar energy UV radiation is required to produce sunburn on protected skin i. As the SPF value increases, sunburn protection increases. There is a popular misconception that SPF relates to time of solar exposure. For example, many consumers believe that, if they normally get sunburn in one hour, then an SPF 15 sunscreen allows them to stay in the sun 15 hours i. This is not true because SPF is not directly related to time of solar exposure but to amount of solar exposure. Although solar energy amount is related to solar exposure time, there are other factors that impact the amount of solar energy. For example, the intensity of the solar energy impacts the amount. The following exposures may result in the same amount of solar energy:. Generally, it takes less time to be exposed to the same amount of solar energy at midday compared to early morning or late evening because the sun is more intense at midday relative to the other times.