Over-exposure to certain types of electromagnetic radiation can be harmful.
The higher the frequency of the radiation, the more energy it carries and the more damage it is likely to cause to the body:
Ultraviolet radiation - UV - is found naturally in sunlight.
We cannot see or feel ultraviolet radiation, but our skin responds to UV exposure by turning darker over time.
This is called a sun tan.
This happens as our bodies attempt to reduce the amount of ultraviolet radiation reaching deeper skin tissues.
Darker skins absorb more ultraviolet light, so less ultraviolet radiation reaches the deeper tissues.
This is important, because prolonged exposure to ultraviolet radiation can cause skin cancer and damage to eyes.
It is sensible to wear high protection, UV blocking sunscreen on sunny days to avoid skin cancer.
Overexposure of our eyes to ultraviolet radiation can cause blindness, so we should also wear hats and sunglasses on sunny days.