Electromagnetic waves and radiation

Electromagnetic fields are present everywhere in our environment. There are natural sources, such as the earths magnetic field, but there are also manmade sources such as domestic appliances, TV, radio, microwave ovens and mobile phones.

One of the main characteristics of an electromagnetic field is its frequency. Electromagnetic fields of all frequencies make up the electromagnetic spectrum, which can be divided into two principal areas: ionising and non-ionising radiation.

Non-ionising radiation is the term given to the lower frequency end of the electromagnetic spectrum, this is because there is insufficient energy to cause changes at the molecular level to living matter. It includes static and power frequency fields, radiofrequencies, microwaves and infrared radiation. Microwaves, hairdryers, fridges, televisions, and all other electrical appliances all emit low levels of non-ionising radiation.

Ionising radiation on the other hand occurs in the very high frequencies region of the electromagnetic spectrum. It can pass through body tissues and cause damage at molecular level. Examples of this type of radiation are x-rays and gamma rays, which are regularly used in hospital treatments and ultraviolet light.

Page last reviewed 14 Apr 2008