"Radiofrequency (or RF) Radiation" refers to electromagnetic fields with frequencies between 300 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. As well, the lower-frequency boundary of RF radiation is often extended to 10 kHz, or even to 3 kHz, in order to include emissions from commonly used devices.
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 10 kilohertz, 30 kilometre wavelength. Next is the RF/microwave region. This region extends to 300 gigahertz, 1 mm 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 half way 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, and diathermy applicators. See Table III, "Sources of RF/MW Radiation," for more examples.
This guideline gives advice on preventing overexposure to RF/MW radiation in the workplace and sets out Occupational Exposure Limits which are enforced in Ontario workplaces by the Ministry of Labour under the general duty clause (section 25(2)(h) of the Occupational Health and Safety Act). However, this guideline cannot cover all possible situations. The requirements set out in the Occupational Health and Safety Act must be complied with, and they should be referred to when this guideline is used.