750 Introduction to Industrial Hygiene

Physical Hazards

Physical hazards that employees in the workplace face include excessive levels of ionizing and nonionizing electromagnetic radiation, noise, vibration, illumination, and temperature.

Ionizing Radiation

Radiation beyond the ultraviolet range falls within the ionizing radiation range that has enough energy to remove tightly bounded electron charges from atoms, thus creating ions. We take advantage of its properties to generate electric power, to kill cancer cells, and in many manufacturing processes.

There are three main kinds of ionizing radiation:

• Alpha particles, which include two protons and two neutrons
• Beta particles, which are essentially electrons
• Gamma and x-rays, which are pure energy (photons)

In occupations where there is exposure to ionizing radiation, time, distance, and shielding are important tools in ensuring worker safety.

• Time: Danger from radiation increases with the amount of time one is exposed to it; hence, the shorter the time of exposure the smaller the radiation danger.
• Distance: Distance also is a valuable tool in controlling exposure to both ionizing and non-ionizing radiation. Radiation levels from some sources can be estimated by comparing the squares of the distances between the worker and the source. For example, at a reference point of 10 feet from a source, the radiation is 1/100 of the intensity at 1 foot from the source.
• Shielding: The greater the protective shielding mass between a radioactive source and the worker, the lower the radiation exposure.

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