UV Radiation
Spending time outdoors does wonders for the body and mind but our sun has a shady side.
Ultraviolet radiation (UV radiation) is part of sunlight.
When UV rays reach the surface of the skin, our skin’s melanocytes (the cells that produce our skins pigment) react and produce melanin to protect itself. This is otherwise known as a suntan.
Overexposure to UV radiation from the sun or artificial sources is a major contributor to Australia’s high incidence of skin cancer. It can also lead to a painful sunburn, premature aging of the skin, wrinkles, spots and dry and leathery textured skin.
There are three types of UV rays, UVA, UVB and UVC.
UVA has a relatively consistent intensity all year round. These rays penetrate the skin deeper than UVB and contribute to the skin aging prematurely, wrinkles, and sunburn and skin cancer.
UVB rays are stronger than UVA and their intensity increases during the summer months, at higher altitudes and the closer you are to the equator. UVB exposure can cause cataracts, premature skin aging and is the most common cause of sunburning. Long-term exposure can cause skin cancer and even alter your immune system.
UVC rays are the strongest rays and the most dangerous, however the ozone layer filters these rays and they do not reach the Earths surface.
What factors affect UV levels?
There are a number of factors that affect the levels of UV radiation and considerably increase the risk of sunburn and skin damage.
Time of year
UV radiation can be up to 10 times more in summer than in winter when the sun is higher with less atmosphere to pass through. At this time of year you can get sunburn in as little as 15 minutes on a fine January day. September through to April is the highest risk period for Australians.
Time of day
At least 60% of the days UV radiation occurs when the sun is high in the sky in the middle of the day between 10am and 2pm or 11am and 3pm during daylight saving.
Where you live
Areas closer to the equator have higher UV exposure. This means Australia has higher levels of UV radiation compared to North American or Europe.
Cloud cover
On lightly overcast days UV levels can be similar to those on a clear day as UV rays can penetrate the clouds. UV radiation intensity is reduced when there is heavy cloud cover and when there are scattered clouds, UV radiation rises and falls as the clouds pass in front of the sun. It is important to remember however, that even on a cloudy day, you can get sunburn.
UV is independent of temperature
A cooler temperature doesn’t mean you can’t get sunburn. UV rays don’t cause the temperature to be high or low, infrared rays from the sun are responsible for this as they heat up the earth.
Altitude
At higher altitudes UV exposure is greater because the air is cleaner and thinner and less UV rays are filtered out. For example, UV rays can be up to 30% higher at an altitude of around 2,000 metres than at sea level.
Reflective surfaces
Some surfaces reflect large amounts of UV rays. Water surfaces can reflect an extra 5%, concrete can reflect up to 85% and snow can reflect up to 95% of the suns rays! This is on top of what you are already receiving from direct sunlight!
Ozone levels
Some UV radiation is absorbed by the ozone layer. Ozone levels fluctuate from day to day and seasonally and the depletion of the ozone layer also contributes to the amount of UV being filtered through.
Artificial uv radiation by solariums
There has been recent research, which leaves little doubt that UV radiation emitted by solariums can contribute to a person’s risk of developing skin cancer. The Cancer Council of Australia strongly recommends people do not use solariums because they add to their UV radiation exposure.
Facts
Sun facts
- even on a cloudy day you can get sunburn. As much as 80% of the suns rays can penetrate fog, mist or light cloud cover.
- you can get sunburn even in the water. Water surfaces can reflect an extra 5% of the sun’s rays back at you. This is on top of what you are already receiving!
- snow reflects the sun like a mirror, reflecting up to 95% of its rays.
- dry surface can also reflect the sun. Concrete can reflect up to 85% of the sun’s rays.
- research shows as little as one severe sunburn in childhood increases the child’s risk of melanoma or other skin cancers later in life.
UV facts
- UV rays are most intense when the sun is high in the sky, between 11am and 3pm during daylight saving time (between 10am and 2pm all other times of the year).
- UV rays are at their most intense during the summer however, it is important to remember that UV reaches the earth everyday, even in winter, and precautions should be taken all year round.
- At higher altitudes UV exposure is greater because the air is thinner and cleaner.
- Areas around the equator have higher UV exposure.