UVA and UVB radiation are the types of sun radiation that penetrate the
Earth's atmosphere and reaches the ground. These are the two types of
radiation that sunscreens protect against. (Photo: Diane Ursu)
Protecting yourself from the sun and sunscreens
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UV radiation and how to protect against it
- Is it really SPF 100?
- Is your sunscreen causing skin cancer?
- Choosing a safe and effective sunscreen
- How to protect yourself from the sun's rays
Every summer, Americans are advised to apply a liberal amount of sunscreen before heading outdoors for a day in the sun. The sun's rays contain UVA and UVB radiation that may contribute to skin cancer.
UV stands for ultraviolet light. This UV light travels to the earth in the form of waves, such as those of a lake or an ocean. UVA rays have long waves, whereas UVB has short waves. According to the Skin Cancer Foundation's article, "Understanding UVA and UVB," UVB radiation is more intense, but UVA radiation accounts for up to 95 percent of the radiation reaching the Earth's surface.
The difference between UVA and UVB radiation
The longer wavelength of UVA radiation allows it to penetrate the skin deeper than UVB radiation. UVA radiation causes tanning that is a response to protect the skin's cells from further damage. Repeated tanning can lead to skin wrinkling and aging.
UVB radiation causes skin reddening known as sunburn. The Skin Cancer Foundation warns, "Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 a.m. and 4 p.m. from April to October."
Choosing a sunscreen
The Skin Cancer Foundation advises using sunscreen with an SPF of 15 or higher. It should protect against both UVA and UVB radiation, so look for multi spectrum, broad spectrum, or UVA/UVB protection on the label.
Apply sunscreen to the skin 30 minutes before going outdoors. Reapply every two hours. It is best to stay in the shade when UVB rays are most intense and to cover up with clothing including sunglasses and a hat.
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