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1. Introduction

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.

"Radiofrequency (or RF) radiation" applies to electromagnetic fields with frequencies between 3 kHz and 300 MHz, while "Microwave (or MW) radiation" covers fields from 300 MHz to 300 GHz. Since they have similar characteristics, RF and MW radiation are usually treated together. The lower-frequency boundary of RF radiation is often extended to 3 kHz in order to include emissions from commonly used devices such as radio and television transmitters, computer network hubs, wireless internet (Wi-Fi) routers, Bluetooth devices, cordless telephones, cellular phones and their transmitting towers, and microwave ovens.

Figure 1: The Electromagnetic Spectrum

Electromagnetic Spectrum Diagram

The frequency of electromagnetic fields is measured in Hz (hertz), or cycles per second. 1 kHz (kilohertz) = 1000 cycles/second. 1MHz (megahertz) = 1 million cycles/second. 1 GHz (gigahertz) = 1000 million cycles/second.

Full description of Figure 1 (from left to right): The left side of the illustration shows the low frequency region. This region ends at 3 kilohertz, 100 kilometre wavelength. Next is the radio frequency and microwave region. This region extends to 300 gigahertz, 1 millimetre wavelength. The next regions to the right are defined as infrared, visible and ultraviolet. Each region has an increase in frequency and a decrease in wavelength that corresponds to the relationship between these two variables and the speed of light, which is a constant. At the far right of the illustration is the x and gamma ray region. The following regions are non-ionizing: low frequency, radio-frequency, microwave, infrared and visible. The non-ionizing/ionizing boundary occurs approximately halfway through the ultraviolet region. The ionizing region extends to the right through the x and gamma ray region.

RF radiation is produced by devices such as radio and TV transmitters, induction heaters and dielectric heaters (also known as RF sealers). MW radiation is produced by microwave ovens, parabolic (dish) antennas, radar devices, cellular phones, Wi-Fi routers, smart meters and diathermy applicators. See Table IV, "Sources of RF/MW Radiation," for more examples.

This guideline gives advice on preventing overexposure to RF/MW radiation in the workplace and recommends occupational exposure limits. The general duty clause 25(2)(h) of the Occupational Health and Safety Act (OHSA) requires employers to take every precaution reasonable in the circumstances for the protection of a worker. This includes the protection of workers from the hazards associated with RF/MW radiation. Clause 25(2)(a) of OHSA requires employers to “provide information, instruction and supervision to a worker to protect the health and safety of the worker”. Clause 25(2)(d) of OHSA requires the employer to “acquaint a worker or a person in authority over a worker with any hazard… in the handling, storage, use, disposal and transport of any…physical agent”, including RF/MW radiation. In addition, it should be noted that various sector regulations under the OHSA have requirements regarding the establishment of measures and procedures with respect to the hazards of physical agents present in the workplace and regarding the training of workers who may be exposed to physical agents in the workplace that may endanger the worker’s health or safety.

When enforcing the general duty clause, the Ontario Ministry of Labour’s Radiation Protection Service (“the Ministry”) may take this guideline into consideration. This guideline does not cover all possible situations.

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ISBN: 978-1-4606-7601-1 (HTML)

Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.

It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.

While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.