Firefighters may work on rooftops, where radiofrequency (RF) radiation emitting antennae are found.


Firefighters may be exposed to non-ionizing radiation, such as radiofrequency (RF) radiation, as a result of directional and omni-directional antennae found on rooftops. Rooftops can present areas of high RF radiation exposure because:

  • personnel may be on the same horizontal plane as the antenna, where the signal is the strongest
  • rooftops may have many different types of antennae, all transmitting at different power and frequencies
  • the signal strength of each antenna combines, creating a higher cumulative RF strength
  • a damaged coaxial cable may leak a concentrated RF signal

Actions for employers

Employers should:

  • make workers aware of the potential sources and hazards of RF radiation

Health hazards

The primary health concern is overheating and burns.

Recommended exposure limits and more information on health hazards can be found in the Ministry of Labour health and safety guideline Radiofrequency and microwave radiation in the workplace.

Common types of RF antennae

Directional antennae

These antennae send and receive RF radiation out in front of them. There is no RF energy behind them. Avoid walking or working in front of these.

A collection of round and long, box-shaped structures mounted on top of a tower.

Figure 1: Directional antennae on a tower.

Long box-shaped structures mounted on support poles.

Figure 2: Directional antennae on the roof of a building.

Omni-directional antennae

These antennae transmit a 360 degree signal. Avoid walking or working on the same plane as these.

Structures like vertical poles mounted on top of a round water tower.

Figure 3: Omni-directional antennae on a water tower.

Working safely around RF antennae

Consider the following:

  • conduct pre-planning activities to identify antenna locations, their type and power sources, safe distances, lock out procedures, and site contacts
  • identify radiation warning signs and follow any written precautions
  • assume antennae are live unless locked out
  • consider site conditions when setting up ladders or aerial devices, to avoid placing the ladder into or through the beam of RF transmission
  • ungrounded conductors such as ladders in the beam may present a shock hazard
  • do not look into the ends of open coaxial cable or remain close to visibly damaged cables, as there may be harmful concentrated RF signals
  • antennae may be found:
    • on urban rooftops
    • mounted on elevator penthouses
    • at the edge or over the side of building walls
    • disguised as or located within other objects such as flagpoles, steeples, trees or signs

Studies have shown that RF levels on the ground are thousands of times less than the Health Canada limits for safe exposure. In order to be exposed to levels at or above RF exposure limits, a worker would have to remain in the main transmitting beam at the height of the antenna and within a few feet from the antenna.

Applicable regulations and acts



For more information about radiation protection for workers, please call the Ministry of Labour Radiation Protection Service at 416-235-5922.

For more information about radiofrequency safety, read the Ministry of Labour Health and Safety Guideline: Radiofrequency and Microwave Radiation in the Workplace.

Read firefighter guidance notes