Wireless cellular antennas installed on the rooftops of some University buildings emit electromagnetic energy via radio waves, also known as radiofrequencies.
Responsibilities
Environmental Health & Safety (EH&S) provides safety information for University personnel who work in or near University locations where wireless cellular antennas are installed.
UW personnel working in an area where an antenna is installed are required to follow the general safe work practices described on this webpage and in the site-specific focus sheet (listed below).
General safe work practices
Take the following precautions when working near a source of electromagnetic energy:
- Prior to working on the rooftop of any building, notify UW Facilities (or your facility manager) and EH&S Radiation Safety of the location where you will be working and the work you are performing.
- All workers who will have access to rooftops where wireless cellular antennas are located must complete Radiofrequency Safety Awareness Training provided by EH&S.
- Review site-specific safety information (below) and identify the hazard area before starting work on rooftops or near antennas.
- Assume that all antennas are active.
- Do not touch the external surfaces of radiating antennas (due to potential shock and burns).
- Follow the instructions on all posted signs on the rooftop.
- Do not stand directly in front of the antennas.
- Avoid areas of exposure to radiofrequency energy (as indicated by posted signs) if possible.
- If your work requires you to be in a hazard area in front of a transmitter, please contact EH&S Radiation Safety for additional safety discussion. Additional safety measures may include
- Wearing a personal monitor to continuously monitor the exposure limits to radiofrequency energy; and
- Requesting downtime on the equipment during the period of work, if necessary. Coordination for downtime is required; please provide as much advance notice as possible.
- Personnel with implanted medical devices, such as pacemakers, should consult with their healthcare provider and identify themselves to their supervisor prior to working in the vicinity of the radiofrequency-emitting equipment.
- Only authorized personnel may access the communication towers.
Additional safe work practices for specific sites are listed below.
Site-specific information
EH&S created a focus sheet for each wireless cellular antenna site based on the RadioFrequency Emission Survey Measurements Report provided by the wireless carrier or network operator (or consultants working on their behalf) when each antenna was installed.
Each focus sheet contains the following information:
- Site name and address
- Types of antennas and the network provider(s)
- Electromagnetic energy measured at accessible locations
- A map of the site and location of antennas/transmitters
- Area of safe and hazard zones
- Signage, barriers, and hazard controls
- Additional safe work procedures, including the requirement for use of RF personal monitor
4545 Building, University District
BB Tower, UW Medical Center – Montlake
Chemistry Building, Seattle campus
Mary Gates Hall, Seattle campus
Mechanical Engineering Building, Seattle campus
Patricia Steele Building, Harborview Medical Center
Training
EH&S provides Radiofrequency Safety Awareness Training upon request. Contact Radiation Safety to schedule a training session.
Radiofrequency signs
The table shows required signage in areas where radiofrequencies are emitted. Refer to the Radiofrequency Safety Exposure Categorization Guide and the Exposure Limits section for detailed information on the Federal Communication Commission's (FCC's) maximum permissible exposure limits for both the general public and occupational workers.
| HAZARD CATEGORY | SIGNAGE COLOR/TYPE | DEFINITION |
|---|---|---|
| No restrictions or special safety practices are required. | No signage. Antenna owner information will be noted on the access door. | Area where radiofrequency energy is too weak to cause exposures greater than general public limit |
|
Controlled areas with barriers and/or signage are required. General public access is not allowed |
Blue Notice (required) |
Area where radiofrequency energy could potentially be greater than general public limit but less than occupational worker limit |
| The area is restricted to trained workers only. | Yellow CAUTION (required) |
Area where radiofrequency energy could potentially be greater than occupational worker limit but less than five times the occupational worker limit |
|
No entry is allowed prior to lockout/tagout of the transmitter. Special training and controls are required prior to entry. |
Red WARNING (required) |
Area where radiofrequency energy could potentially be greater than five times the occupational worker limit |
Frequently asked questions
Wireless cellular antennas send out electromagnetic energy (non-ionizing radiation) in the form of radio waves (also known as radiofrequencies) carrying information.
Wireless phone networks operate by sending radio signals to and from cell phones using antennas placed in strategic locations. These antennas can both transmit and receive radiofrequencies in a specific surrounding area, much like other two-way radio signals.
When electromagnetic energy reaches an object, some of the energy carried by the waves is deposited in the object. This can lead to the object heating up. If the amount of energy is too high, it can cause harmful effects to people and animals. As with all forms of electromagnetic energy, the power rapidly decreases as you increase your distance from the source (i.e., the antenna).
Wireless cellular antennas are usually arranged in groups, with one antenna in each group used to transmit signals, and the other antenna(s) are used to receive signals from mobile devices. The antennas use frequencies ranging from 100 kilohertz (kHz) to 300 gigahertz (GHz) to send and receive signals.
The total radiofrequency power from each transmitting antenna depends on the number of radio channels (or transmitters) and the power of each transmitter. The wireless carrier measures the actual radiofrequency energy emitted by each antenna after the installation is completed. The measurements are provided to the University and appear in the site-specific information.
Signs warn of potential hazard in an area where radiofrequencies are being emitted. Refer to the Radiofrequency Signs section of this page for a description of the required signage posted in areas where antennas are located. Always follow the guidance indicated on the sign.
Barriers prevent physical access to an area where a hazard exists. Barriers can include locked doors, stanchions, demarcations, gates, alarms, and other means.
Controls are methods to reduce or eliminate a hazard, which can include avoiding hazard zones, reducing the time spent, or using a RF personal monitor to continuously monitor the exposure limits while working near wireless cellular antennas. If work must occur in a hazard area, it may be possible to shut down the antenna temporarily.
Talk with your supervisor or EH&S Radiation Safety with questions about barriers and controls when working near wireless cellular antennas.
The Federal Communication Commission (FCC) adopted maximum permissible exposure limits for safe exposure to the radiofrequency energy produced by transmitters/antennas, including those installed at University locations. The FCC has two types of limits:
- Occupational limits for workers; and
- Limits for the general public.
These exposure limits are based on thresholds for known adverse effects or at which harmful biological effects may occur, and the values for Maximum Permissible Exposure (MPE) recommended for electric and magnetic field strength and power density in both documents are based on this level. The threshold level is a Specific Absorption Rate (SAR) value for the whole body of 4 watts per kilogram (4 W/kg).
Occupational exposure limits
Occupational exposure limits apply to situations in which persons are exposed because of their employment and in which persons who are exposed have been made fully aware of the potential for exposure and can exercise control over their exposure.
Occupational exposure limits also apply where exposure is of a transient nature because of incidental passage through a location where exposure levels may be above public limits (refer to the section below) if the exposed person has been made fully aware of the potential for exposure and can exercise control over their exposure by leaving the area or by some other appropriate means.
UW personnel who have completed the EH&S Radiofrequency Safety Awareness Training fall under the occupational exposure limits.
Radiofrequency emissions could exceed desirable levels on the rooftop where an antenna is mounted; however, this is only likely to be encountered very close to, and directly in front of, an antenna. UW personnel working on a rooftop where an antenna is installed are required to follow the Safe Work Procedures described above to avoid exposure in excess of the limits.
Individuals living or working within the building are not at risk of overexposure.
General public exposure limits
General public exposure limits apply to situations in which the public may be exposed, or in which persons who are exposed because of their employment may not be made fully aware of the potential for exposure or cannot exercise control over their exposure. Members of the public would always be considered under this category when exposure is not employment-related.
Read about the FCC’s limits on human exposure to radiofrequency fields in their Guidelines for Cellular Antenna Sites.
All installations of wireless cellular antenna/telecommunication services at University of Washington locations must be carried out according to the FCC guidelines. The guidelines require the wireless carrier to submit a Non-Ionizing Electromagnetic Radiation Report and a Radio Frequency Emission Survey Measurements Report as part of the approval process with UW Environmental Health & Safety.
The Non-Ionizing Electromagnetic Radiation Report must be submitted for all new antenna installations and for upgrades of existing sites before an antenna is installed. The report provides estimates based on the maximum predicted levels of radiofrequency energy or a calculated maximum level of exposure to radiofrequency energy at certain identified locations and compares it against the exposure limits set by the FCC. The values of radiofrequency energy provided in the report are intended to be maximum levels that can almost never be exceeded when the antenna is operating. The calculations assume, for example, that all the planned transmitters are installed and are all operating at maximum power.
The Non-Ionizing Electromagnetic Radiation Report contains safety recommendations for the proposed installation at the site and these calculations can be adjusted to ensure protection at all times for all people (including UW workers and general public).
The Radio Frequency Emission Survey Measurements Report is produced after the wireless antenna is installed. The report verifies the accuracy of the antenna placement and technical specifications. It measures the actual radiofrequency energy emitted at the antenna site and compares it to the FCC’s limits for public and occupational exposures. Measurements around the antennas have shown actual values of radiofrequency energy are usually less than what was estimated prior to installation by factors of 10 to 1000 or even more. The values of RF energy indoors will typically be even lower as walls, windows and roofs absorb or reflect the energy.
The Radio Frequency Emission Survey Measurements Report for each site is available by contacting the EH&S Radiation Safety Office or 206.543.0463.