What Is the Difference Between UVA and UVB?


Quick Answer

UVA and UVB rays are different forms of ultraviolet radiation that are given off by the sun. UVA is a longer form of radiation than UVB. Both can cause premature skin aging, eye damage and skin cancers, and both of these rays can also suppress people’s immune systems and affect their ability to fight off disease.

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Full Answer

UVA rays account for approximately 95 percent of the UV radiation that reaches Earth’s surface from the sun. They are less intense than UVB rays and can penetrate through the clouds in the atmosphere. UVA rays can penetrate the skin deeper than UVB rays and can cause damage to multiple layers of the skin. UVB rays are the main cause of sunburns, as they damage the skin’s outermost layers. UVB rays also play a key role in the development of skin cancers. UVB rays vary in intensity, depending on the time of the day and year, whereas UVA rays have relatively the same intensity at all times. Tanning booths primarily utilize UVA rays. Over time, excessive exposure to UVA rays can cause skin cancers to form in the deep layers of a person’s skin. Due to the damage that UVA and UVB rays can cause, doctors suggest wearing sunscreen at all times when outdoors and avoiding tanning booths.

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