Understanding UV Radiation and the UV Index

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Understanding UV Radiation and the UV Index
Find out what the current UV index forecast is in your area

Know Your UV – A,B,C’s:

The sun emits different kinds of light:

• the visible light you see,
• the infrared light you feel as heat,
• and invisible ultraviolet (UV) radiation.

It is the UV radiation part of light which affects our skin the most. It is important to know about the sun’s UV rays in order to know how to protect your skin and prevent skin cancer.

There are 3 types of UV rays:

UVA: A stands for Aging.
UVA radiation penetrates deep into the skin and is responsible for premature aging of the skin and skin cancer. Tanning beds can emit 2 to 5 times more UVA radiation than the sun.

UVB: B stands for Burning.
UVB radiation is stronger than UVA radiation. It mainly affects the outer layers of the skin, causing sunburns, premature aging of the skin, and skin cancer. These rays are strongest during the summer months – especially between 11 am and 4 pm.

UVC: UVC radiation is the strongest, most dangerous form of UV light. However, they are stopped by the earth’s atmosphere and do not reach earth’s surface.

Knowing your UV – ABC’s helps to understand why it is important to wear a broad-spectrum sunscreen

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The UV Index

The UV index is a measure of the intensity of the sun’s UVA and UVB rays. The higher the number, the stronger the sun’s rays, and the greater the risk for skin damage.

UV Index	Recommendations
0-3.9 Low*		Protection (i.e. sunscreen, sunglasses) is recommended for those in the sun for longer than one hour, especially over fresh snow.
4.0-6.9 Caution**		Limit time spent in the sun during the hours of 11:00 a.m. to 4:00 p.m. if possible
		Look for shaded areas to do outdoor activities (trees, umbrellas, awnings) whenever possible.
		Wear a hat with a wide brim or a flap that covers the back of the neck.
		Wear clothing to protect as much of your skin as possible.
		Put on protective sunglasses.
		Use a sunscreen with: SPF 15 or higher - UVA & UVB protection
7.0 – 8.9 *** High Caution		Burns and skin damage can occur quickly. Reducing the time spent in the sun is most important at these values. If you must be in the sun, follow the protection plan above.
9.0 & Up **** Extreme Caution

Average time for fair, unprotected skin to burn…
* Low 1 hour or longer
** Caution 30 minutes
*** High 20 minutes
**** Extreme 15 minutes

NOTE: UV Index chart developed by Toronto Public Health

Find out what the current UV index forecast is in your area:

Environment Canada ® www.ec.gc.ca/envhome.html
The Weather Network ® www.theweathernetwork.com

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