Ultraviolet (UV) radiation
Overexposure to UV rays can cause skin cancer, premature skin aging and weakening of the immune system.
Ultraviolet radiation comes from natural sources (the sun) and artificial sources (tanning equipment, lasers, welding equipment and certain lamps).
Ultraviolet Radiation (UVR)
Some uses of UVR include:
- it can be used to kill germs
- it can treat various skin conditions
- it helps us form vitamin D in our bodies
But, as with all forms of radiation, there are risks involved with UVR.
Overexposure to UVR has been linked to the following negative health effects:
- sunburns
- premature skin aging
- skin cancer
- eye problems
- weakening of the immune system
It is important to protect yourself when exposed to either natural or artificial UVR.
There are three types of UVR:
Ultraviolet A (UVA) rays:
- penetrate deep into the skin, causing wrinkles and premature aging
- about 95% of UVA rays reach the earth’s surface
Ultraviolet B (UVB) rays:
- are the most damaging to our skin
- are the main cause of sunburns
- are much stronger than UVA rays
Ultraviolet C (UVC) rays (short-wave radiation):
- are filtered out by the atmosphere and do not reach the earth’s surface
Know the factors that affect UVR levels and learn to reduce your risk of sunburn and skin damage.
How much UVR reaches me?
You get more UVR when the sun’s rays are the strongest. The amount of UVR that reaches you depends on these factors:
Seasons
- The amount of UVR changes from day to day. It is strongest in spring and summer, declines in fall and is lowest in winter.
Time of day
- UVR is strongest when the sun is higher in the sky. The sun is strongest in the sky at midday and skin burns fastest during these hours.
How long you’re in the sun
- The longer you spend in the sun, the more UVR you receive.
Position on the earth
- UVR is strongest at the equator and weakens toward the North and South poles.
Cloud cover
- UVR levels are highest under cloudless skies.
- Light cloud cover and a breeze can make you feel cooler, but do not block UVR from reaching the earth.
Altitude
- UVR levels are much higher on a mountaintop than at sea level. Higher altitudes filter out much less UVR because the air is clearer and thinner.
Ozone
- Ozone absorbs some of the UVR that would otherwise reach the earth’s surface. The amount of ozone (ozone layer) affects the amount of UV that reaches the earth.
Land cover
- Seeking shelter from structures and trees can reduce exposure to UV rays by up to 50% or more.
Reflected UVR
- Water, sand, concrete and snow can reflect the sun’s rays onto the skin. Reflected UV rays increases your UVR exposure. Surfaces can reflect UVR even in shaded areas.
UV Index
Environment Canada created the UV Index to let Canadians know how strong the sun’s UV rays are each day. It is a system that helps people understand what sun protective actions are recommended, based on the strength of the sun’s rays. The higher the UV Index number, the stronger the sun’s rays and the greater the need to take precautions.
When the daily UV index is 3 or higher, it can be found on The Weather Network’s website and on the Government of Canada’s website. Most daily newspapers, and television and radio weather forecasts also report the UV Index.
Remember, you can reduce your exposure to UVR in many ways:
- reduce sun exposure
- seek shade
- cover up with clothing
- wear a wide-brimmed hat
- apply sunscreen labelled “broad spectrum” and “water resistant” with a SPF 30 or higher
- wear close fitting/wrap-around sunglasses (Government of Canada) with UV 400 or 100% UV protection, any time of day, all year round
- avoid artificial tanning
For more information, contact Public Health Sudbury & Districts at 705.522.9200 (toll-free 1.866.522.9200).
Sources:
Canadian Centre for Occupational Health and Safety. (2020) Ultraviolet Radiation. Retrieved from https://www.ccohs.ca/oshanswers/phys_agents/ultravioletradiation.html
on July 22, 2020.
Health Canada (2017). Guidelines for Tanning Equipment Owners, Operators and Users. Retrieved from https://www.canada.ca/en/health-canada/services/publications/health-risks-safety/2017-guidelines-tanning-salon-owners-operators-users.html#a20 on August 27, 2020.
Government of Canada. Health Canada (2019). Ultraviolet Radiation. Retrieved from https://www.canada.ca/en/health-canada/services/health-risks-safety/radiation/types-sources/ultraviolet.html on July 22, 2020.
World Health Organization (n.d.). Ultraviolet radiation. Retrieved from https://www.who.int/health-topics/ultraviolet-radiation#tab=tab_1 on July 22, 2020.
This item was last modified on June 2, 2022