Physical Agents

Physical Agents are sources of energy that may cause injury or disease. Examples include Noise, Vibration, Optical Radiation and Electromagnetic Fields.


Noise means unwanted sound or loud discordant or disagreeable sound or sounds.

The effect of noise on hearing can be temporary or permanent. Temporary deafness is often experienced after leaving a noisy place. Although hearing recovers within a few hours, this should not be ignored as it is a sign that continued or regular exposure to such noise could cause permanent damage.

Hearing loss is usually gradual due to prolonged exposure to noise. it may only be when damage caused by noise over the years combines with normal hearing loss due to aging that people realise how deaf they have become. Hearing damage can also be caused immediately by sudden, extremely loud noises, though this is not common.

Exposure to noise may also cause tinnitus, which is a sensation of noises (such as ringing or buzzing) in the ears. This can occur in combination with hearing loss.

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Vibration means rapid movement to and fro or oscillating movement.

Mechanical vibrations at work can expose workers to hand-arm vibration (HAV) and or whole-body vibration (WBV).

HAV is caused by the use of work equipment and work processes that transmit vibration into the hands and arms of employees.

Long-term, regular exposure to HAV is known to lead to potentially permanent and debilitating health effects known as hand-arm vibration syndrome, such as vibration white finger and carpal tunnel syndrome.

WBV is caused by vibration transmitted through the seat or the feet by workplace machines and vehicles.

Regular, long-term exposure to high levels of WBV is linked to lower back pain.

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Optical Radiation

Optical radiation is another term for light, covering ultraviolet (UV) radiation, visible light and infrared radiation.

The greatest risk to health from optical radiation is probably posed by UV radiation from the sun. Exposure of the eyes to UV radiation can damage the cornea and produce pain and symptoms similar to that of sand in the eye. The effects on the skin range from redness, burning and accelerated ageing through to various types of skin cancer.

The second greatest risk to health from optical radiation is probably posed by the misuse of powerful lasers. High-power lasers can cause serious damage to the eye (including blindness) as well as producing skin burns.

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Electromagnetic Fields

Electromagnetic fields (EMFs) arise whenever electrical energy is used. So for example, EMFs arise in our home from electrical appliances in the kitchen, from work processes such as radiofrequency heating and drying and in the world at large from radio, TV and Telecoms broadcasting masts and security detection devices.

It has been known for a long time that exposure of people to high levels of EMFs can give rise to acute effects. The effects that can occur depend on the frequency of the radiation. At low frequencies the effects will be on the central nervous system of the body whilst at high frequencies, heating effects can occur leading to a rise in body temperature. In reality, these effects are extremely rare and will not occur in most day-to-day situations.

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