An educational tool to reduce risks of skin cancer and cataract

Everyone is exposed to ultraviolet (UV) radiation from the sun. Small amounts of UV radiation are beneficial to people, and play an essential role in the production of vitamin D. However, overexposure to UV radiation is responsible for two major public health problems: skin cancer and cataract.

UV radiation

Emissions from the sun include light, heat and UV radiation. UV radiation reaching the Earth's surface is largely composed of UVA with a small UVB component. UV radiation levels are influenced by:

• Sun elevation: the higher the sun in the sky, the higher the UV radiation level.
• Thus UV radiation levels vary with time of day and time of year.
• Latitude: the closer to equatorial regions, the higher the UV radiation levels.
• Cloud cover: UV radiation levels are highest under cloudless skies but even with cloud cover, they can be high.
• Altitude: at higher altitudes, a thinner atmosphere absorbs less UV radiation.Ozone: ozone absorbs some of the UV radiation that would otherwise reach the Earth's surface.
• Ground reflection: grass, soil and water reflect less than 10% of UV radiation; fresh snow reflects as much as 80%; dry beach sand about 15% and sea foam about 25%.

Sun elevation: the higher the sun in the sky, the higher the UV radiation level. Thus UV radiation levels vary with time of day and time of year.Latitude: the closer to equatorial regions, the higher the UV radiation levels.Cloud cover: UV radiation levels are highest under cloudless skies but even with cloud cover, they can be high. Altitude: at higher altitudes, a thinner atmosphere absorbs less UV radiation.Ozone: ozone absorbs some of the UV radiation that would otherwise reach the Earth's surface. Ground reflection: grass, soil and water reflect less than 10% of UV radiation; fresh snow reflects as much as 80%; dry beach sand about 15% and sea foam about 25%.

As UV radiation can neither be seen nor felt, it is important to provide a tool to raise awareness of the problem and alert people on a daily basis to take prompt, appropriate, protective action.