By Safety Management Group
If it seems as though towers are sprouting out of nearby fields, industrial parks, and neighborhoods with increasing frequency, it’s not your imagination. Communications companies and others have been scrambling to keep up with the exponential growth of cellular phones and other wireless devices.
Existing towers are also being used to serve multiple purposes. It’s not unusual to see antennas for multiple wireless phone carriers, wi-fi transmitters, cameras, and microwave dishes on a single tower. That means crews representing a wide variety of companies could have reason to climb the towers for installations and maintenance.
Few towers have any former of mechanical lift equipment, so workers typically have to climb hand-over-hand up ladder rungs or support structures for anywhere from 100 to 1,000 feet or more, while carrying equipment and tools.
Given the increased number of communications towers and the greater utility of existing towers, it comes as no surprise that the number of injuries and fatalities associated with them have been on the rise. In fact, the number has been increasing at a rate that motivated OSHA to step up recommendations for proper safety practices. At one recent conference, OSHA administrator David Michaels told attendees that workers on communications towers face a significantly higher rate of workplace deaths — reportedly 25 to 30 times the normal rate.
As you’d expect, falls are the biggest hazard, but they’re not the only one. Exposure to electricity and non-ionizing radiation also present hazards, as do chemicals used to clean and treat towers. In some cases, deaths and injuries were the result of structural failures.
RF exposure
Of the hazards, the most poorly understood is the potential for exposure to radio frequency (RF) radiation. That’s especially an issue with towers that include multiple types of antennas, each of them transmitting and/or receiving RF signals at different frequencies and intensities. Even if workers are not touching those antennas, they may be performing tasks in close enough proximity to be exposed to amounts of RF signals that exceed safe levels for exposure by humans. That’s why most towers have signs warning of RF exposure hazards.
The most immediate danger related to excessive RF exposure is its ability to heat biological tissue very quickly. Microwave ovens use the same principle to cook food in very short timeframes. Given that human skin and organs are made up of tissue, high levels of RF can quickly cause physical damage. While the body can protect itself by some degree by using blood flow to regulate temperatures and dissipate localized heat, the eyes and the testes lack those mechanisms, making them prone to heat damage.
There is also some speculation that long-term exposure to even low levels of RF radiation could lead to development of tumors and certain cancers. Although some animal tests have supported a connection, there hasn’t been any definitive scientific evidence that those working around RF radiation face a greater risk of cancer or tumors.
Performing work safely
As with so many aspects of workplace safety, effectively protecting workers begins with thorough planning and training. It may seem that climbing a tower isn’t all that different from climbing a ladder, but it actually requires specialized skills and physical agility that may not be readily apparent to workers until they find themselves in a dangerous situation.
Every worker who has reason to climb a tower should be certified based on the expectations of OSHA and/or the National Association of Tower Erectors (NATE), with regular updates to ensure continued proficiency and familiarity with new equipment and techniques.
Before any tower work begins, a competent person (based on OSHA standards) should develop a climb plan and perform a pre-climb inspection. The climb plan should address work permits, notification of carriers who use the tower’s antennas, arrangements to reduce RF emissions during the work, the climbing procedures that will be used, the soundness of all attachment points, lockout/tagout procedures for any hazards specific to the tower, and weather and other conditions that may affect workers. It’s important to keep in mind that weather conditions may be very different near the top of the tower than at ground level.
Communications towers vary in size, style, and structure, and some may not have been designed to facilitate climbing. For example, some older towers may lack anchorage points for fall protection devices or lifelines to which harnesses may be attached. It’s also possible that different elements of the tower’s structure may have very different load limitations. While all the metal components may look the same, one may be able to support a worker’s weight, and the next one may not. Any member that has an inadequate load limitation would not be a safe point to tie off a harness. It may be necessary to use other methods such as aerial lifts to ensure that workers can safely access task areas.
Protection from RF radiation
The climb plan should consider the RF transmissions of antennas on the tower and how much exposure workers may receive. Federal Communications Commission regulations set limits for the Maximum Personal Exposure (MPE) of RF radiation, and call upon employers to ensure that workers are not exposed to more than those limits.
If possible, the carriers should be notified so that they can either reduce or eliminate RF emissions when workers are present. Workers who will be exposed to RF radiation should wear special protective clothing and carry an RF personal monitor that will track exposure levels. If wearing such a monitor, the worker must have it positioned outside of protective clothing and leave it on while working. After all, RF radiation is invisible.
Also keep in mind that some workplace equipment, such as wire rope used on a hoist or a crane, can resonate with the frequency that is being transmitted and become an antenna, or may come in contact with electrical equipment.
Personal protective equipment
Workers who will climb towers must be equipped with personal protective equipment (PPE) that suited for their specific tasks. Depending upon the nature of their work, PPE may include a helmet, gloves, boots, safety glasses, and equipment such as safety harnesses and lanyards.
All PPE must be inspected before work begins, and any items that have any visible damage or have passed their safe-use dates must be replaced.
Fall protection
Because most deaths and injuries related to communications towers are the result of falls, particular attention should be focused on ensuring that workers have the right fall protection equipment and a complete understanding of how to use it properly. In most cases, fall protection technology is less appropriate than fall arrest gear such as shock-absorbing lanyards and lifeline systems.
With the variety of tower designs and materials, it’s particularly important that workers understand which places on the tower may be used as safe anchorages.
Common sense
Finally, both workers and supervisors should rely on common sense. For example, if weather conditions begin to deteriorate quickly, the worker should suspend the task and return to safety on the ground. If a planned anchorage appears to be below standards, the worker should locate a safer alternative. Whenever faced with choices, the wise choice is always the safest one.
