The National Roofing Contractors Association (NRCA) and United Union of Roofers, Waterproofers and Allied Workers (UURWAW) are issuing this Safety Alert to increase awareness among roofing workers of possible radiofrequency (RF) hazards. Most buildings contain rooftop components designed to provide for the comfort of the building occupants and efficient operation of processes taking place within the building. Examples include HVAC units, electrical boxes, skylights, solar collectors, water tanks, smoke vents and material storage tanks. Some components are shrouded or hidden by decorative elements such as fences or ornamental panels to improve building aesthetics. One such component most workers on a roof may be oblivious to and which poses serious and possibly immediate danger to workers is a telecommunications transmitter that emits RF radiation or energy.
According to the Federal Communications Commission (FCC), radio waves and microwaves emitted by transmitting antennae are one form of electromagnetic energy. RF is invisible energy in the electromagnetic spectrum, and exposure to it can be harmful to people. The exposure’s harm will vary according to power levels, length of exposure time and distance from the source. Sources of RF energy on a rooftop often are not obvious and usually are not properly marked or defined as danger zones by warning signs. In many cases, for aesthetic reasons, transmitters or antennae are hidden by building elements that can obscure their presence yet not reduce the risk of serious harm to unsuspecting workers.
Here are some examples:
The FCC notes high levels of RF may heat biological tissue and increase body temperature. These so-called “thermal effects” result from the body’s inability to dissipate heat buildup quickly enough to avoid tissue damage. The National Institute for Occupational Safety and Health (NIOSH) states thermal effects may produce “potentially damaging” changes to cell tissue as a result of the temperature increase. At lower levels of RF exposure insufficient to produce thermal effects, the American Academy of Environmental Medicine reports studies indicate “significant harmful biological effects” may occur from nonthermal RF exposures. Scientific literature reports nervous system and immune system dysfunction, cancer, kidney damage and neurological effects, according to the organization.
There is less concern for exposures to the general public than for workplace locations such as rooftops where worker proximity to transmitters, along with longer exposure duration, can more readily occur. And though the full extent of the biological effects of RF exposures is not known, NIOSH believes there is sufficient evidence to be concerned about occupational human exposures. Ultimately, the FCC is charged with evaluating the effects of RF exposures and determining exposure limits.
NRCA and UURWAW recommend the following precautions be taken to minimize RF exposures:
- A roofing contractor must ask a building owner or facility manager whether RF transmitters are present and, if so, their specific locations. The information should be provided in the form of a written map or drawing.
- Through the building owner or facility manager, a roofing contractor must ask the FCC licensee of the transmitter whether the equipment may be shut down or barrier devices installed for the duration of the roofing work. RF-blocking personal protective equipment is available that may be useful, such as eyewear and clothing that protects the wearer from RF radiation.
- If the equipment can be shut down or shielded, written verification from the licensee of the dates and times the transmitter will be shut down or a shielding device put in place must be obtained and lockout/tag out procedures considered.
- If the transmitter must be removed and reinstalled to perform roofing work, a roofing contractor must inform the licensee so employees of the licensee can perform the removal and reinstallation.
- Roofing workers must be trained to recognize RF transmitters; They also must be told the hazards of working in areas where transmitters have not been shut down, symptoms of RF exposure, and the importance of heeding warning signs or restricted access areas and the fact warning signs and restricted access areas may not always be present.