UV is a form of energy produced by the sun. The sun produces different types of energy:

• Visible light – which we can see as sunlight.
• Infrared radiation – which we feel as heat.
• UV radiation – which we cannot see or feel.

UV radiation is often confused with infrared radiation. The temperature, however, does not affect UV radiation levels. UV radiation can be just as high on a cool or even cold day as it is on a hot one, especially if skies are clear. Thick cloud provides a good filter, but UV radiation can penetrate thin cloud cover. And while UV radiation is higher in summer than in winter, it is still present every day of the year.

There are three types of UV radiation, categorised by wavelength: UVA, UVB and UVC.

• UVA can cause sunburn, DNA (cell) damage in the skin and skin cancer.
• UVB causes skin damage and skin cancer. Ozone stops most UVB from reaching the earth’s surface, about 15% is transmitted.
• UVC is the most dangerous type of UV. Ozone in the atmosphere absorbs all UVC and it does not reach the earth’s surface.

UV levels are affected by a number of factors including geographic location, altitude, time of day, time of year and cloud cover. This means that UV levels are higher in some parts of Australia than others even on the same day.