There is evidence that some non-ionising radiations cause unwanted effects on the human body. For example the nervous system can be affected causing feelings of nausea and dis-orientation, harmful heating of body tissue can occur, and optical radiations can burn skin and damage the eyes.

• In the lower frequency range (300Hz to 1MHz) induction currents may interfere with the functioning of the central nervous system.
• In the intermediate frequency range (100KHz to 10GHz) the absorption of electromagnetic energy generates heat.
• At the upper frequency range (10GHz to 300GHz) heating of superficial tissues is possible.
• From optical radiations (infra-red, visible light and ultra-violet) there can be the harmful consequences of heating of tissues and of damage to the eyes.

The nature, extent and physiological importance of biological effects from non-ionising radiations exposure is complex and depends on factors such as the energy of incident radiation (which determines the penetration depth), the power density of a field or beam, source emission characteristics, duration of exposure, environmental conditions and the spatial orientation and biological characteristics of the irradiated tissue (e.g. molecular composition, blood flow, pigmentation, functional importance, etc.).

Apart from the optical region, non-ionising radiations are not perceived by any of the human senses unless the intensity is so great that it is felt as heat. Therefore in workplace situations where there is potential for non-ionising radiations to be generated, protection measures must be in place to prevent against unsuspected exposure. A risk assessment must be carried out to anticipate where a hazard might exist and to identify controls.