Reality Check: Invisible risks of radio frequency radiation, and the best strategies for protection

Editor’s Note: Welcome to our weekly Reality Check column where C-level executives and advisory firms from across the mobile industry share unique insights and experiences.
A few months ago, on the Discovery Channel, we saw the premier of “Hang Men,” chronicling the perils of tower climbers. This program holds the promise of raising awareness to the extreme dangers climbers face every day to keep our nation connected. While most of the show seems to be focused on climbing safety, it will also hopefully raise awareness on another very critical issue impacting the health and well-being of tower workers—the dangers present in high levels of radio frequency radiation.
Awareness of RF radiation risk finds itself in a similar place to concussion awareness in the NFL. Years ago, when there was a generalized sense that getting a concussion in football was “not good,” it was just considered part of the game and only minimal efforts were taken to reduce concussion injuries. Now, with aging players suffering very debilitating effects from repeated, undiagnosed concussions and the medical community endorsing the fact that concussions have the potential to be very damaging to player health, both the league and owners have come together to adopt new standards to mitigate the risk.
We are at a similar juncture with RF awareness. Since the late 1940s, the heating effect of microwave radiation has been well known. (It was in fact, first discovered by an engineer that had a candy bar melt in his pocket while working on radar set.) But, there was never a true appreciation for the level of damage a tower worker can receive when faced with overexposure to RF. Fortunately, that situation is starting to change.
OSHA taking notice
In November 2013, the Occupational Safety and Health Administration sent a letter to the communication tower industry, concerning the alarming increase in tower fatalities — 14 in all — in just a few short months. While all of these deaths were related to falls, OSHA is sharply increasing its investigations into safety and compliance issues across the board and requesting that compliance officers track a wide range of potential safety hazards. The following question comes directly from the letter:
“Ambient radio frequency: Was ambient RF present? Were employees wearing any measuring or warning devices to protect against ambient RF?”
The increasing focus on RF exposure is due to increased awareness of the health effects involved, including burns, shocks, eye damage and even mental impairment. RF radiation, while not cumulative in nature, still causes physical damage as the human body acts as an antenna, absorbing the energy. The rate of absorption depends on the height of the person near a transmitting device versus the frequency/wavelength emitted. The person’s position as it orients to the transmission field is also significant. Since most wireless systems have a vertical polarization, this unfortunately aligns well with a standing person, increasing absorption.
RF radiation: are you at risk?
When it comes to the danger of RF, it’s not just tower construction employees who are vulnerable. The RF threat is present anywhere an antenna is present, including antennas mounted on buildings and rooftops. The following employers should all consider their team at risk for high levels of RF exposure:
–Any municipality with code inspectors that go near antennas.
–Roofers, HVAC workers, construction workers and related contractors.
–Fire department and EMT workers that might need to deliver emergency services near an antenna.
–And, of course, telecommunications employees, including cell tower workers and related contractors.
Could RF radiation be responsible for accidental falls?
When considering RF, you need to think beyond a threat that’s visible to the naked eye, such as a burn. While the causes behind accidental tower falls come from a wide range of reasons, it’s hard to ignore the fact that two of the symptoms of high RF exposure are both visual and mental impairment. In recent cases, many of the falls documented a failure of the climber to properly tie off to a tower. Could feelings of fatigue or confusion have been at play here?
Another factor is that in certain cases, RF arcing has actually welded pelican safety hooks to the tower, rendering them useless. While it’s hard to determine RF radiation’s impact in a specific fall scenario, it’s definitely worth consideration.
Mitigating RF radiation risk
What levels constitute a serious risk? The National Council on Radiation Protection and Measurements, the Institute of Electrical and Electronics Engineers and the International Commission on Non-Ionizing Radiation Protection recommend an exposure less than 4 W/kg for the whole body. In the case of cellular and PCS cell site transmitters, the Federal Communications Commission’s RF exposure guidelines recommend a maximum permissible exposure level to the general public of approximately 580 microwatts per square centimeter. To provide context, the effective radiated power of the majority of cellular or PCS cell sites in urban and suburban areas is 100 watts per channel or less. An ERP of 100 watts corresponds to an actual radiated power of five to 10 watts, depending on the type of antenna used. In urban areas, cell sites commonly emit an ERP of 10 watts per channel or less.
While OSHA prefers engineered solutions to mitigate the risk of RF, an engineered solution is not always feasible. That’s why personal protection monitors are essential to safeguard employees against the very real dangers of RF radiation. Even though OSHA has not yet mandated the use of PPM devices to monitor employee exposure, all major telecommunications carriers now require these technologies as part of their safety and compliance plans.
What types of RF monitors work best?
If the PPM you’re wearing does not align with the polarization of the RF field being emitted, proper detection capability falls short. Microwave Vision Group believes that the best protection from RF comes through PPM units with both the highest sensitivity and greatest range of detection possible that can be worn comfortably by the user. We deploy PPM devices that are isotropic (tri-axial), to measure all three dimensions of the RF field for the user, versus single-axis units that measure only one dimension at a time. We also design our devices with an overload capacity of over 5,000%. This is to prevent monitors from burning up in high RF environments, and it’s also useful for incidental passage through high RF zones.
PPMs should be worn at all times, even if the antenna is thought to be powered down. The minimum safe distance from an antenna may also be further than you think. “Not only should it be required to wear a PPM monitor in the air, it should also be required on the ground,” stated Wade Sarver, a 25-year wireless veteran with Alcatel-Lucent. “I once brought a spectrum analyzer out to a tower site, and discovered that there is plenty of RF radiation at ground level. The minute you open up a fence and go inside, you should be wearing a PPM.”
RF and fall protection go hand-in-hand. The good news is that the industry is educating and training workers and Microwave Vision Group has made PPMs available in a cost effective manner, to meet the needs of the 21st Century worker. PPMs are one of the best methods to insulate your organization against emission-related liabilities. But an even better reason to use such equipment is to safeguard the health and well being of the dedicated individuals that put their lives at risk every day to protect our essential communications infrastructure.
Resources:
Memorandum from James G. Maddeux, Director, Directorate of Construction,Occupational Health and Safety Administration to regional administrators in regards to Protecting the Safety and Health of Communication Tower Workers, (November 8th, 2013)
Kelly Classic, Certified Medical Physicist, ”Radiofrequency (RF) Radiation,” Health Physics Society, (August 27, 2011), http://hps.org/hpspublications/articles/rfradiation.html
“Human Exposure to Radio Frequency Fields: Guidelines For Cellular and PCS Sites, ”Federal Communications Commission, http://www.fcc.gov/guides/human-exposure-rf-fields-guidelines-cellular-and-pcs-sites