Tree removals and pruning are common arboricultural operations. But not everyone engaged in these operations might fit the title of arborist. At least not who we think of as arborists.
Ground workers, landscapers and site-preparation contractors are all workers who may be engaged in arboriculture – managing trees outside of agricultural and forestry settings. This is a key point, as these allied professionals must still follow our safety standards while conducting arboricultural operations. The excuse “I am not an arborist” is not valid. When these workers perform arboricultural operations for pay, usually tree removal and pruning in urban settings, they are arborists.
About 143 fatalities occurred during arboricultural operations in 2020. (The incidents were during the year 2020, and the fatality data comes from multiple sources, including Occupational Safety and Health Administration (OSHA) fatality investigation summaries, hospital emergency-department visitations and utility incident reports, among others. The various data sources were cross-referenced to avoid duplications.)
They happened in 141 separate incidents, work-place events that led to injury or illness, either fatal or nonfatal. There is no universally accepted definition of the terms “incident” or “accident.” OSHA prefers that the word incident rather than accident be used for investigations. OSHA also considers events that had the potential to do harm, what we often call near-misses, as incidents, but these are excluded in this article since data is lacking.
Two events resulted in a pair of fatalities. We also say “about” 143, as the exact number is unknown. There are always fatalities where the occupation is misidentified, and the details of the fatal incident are also unknown. Other fatalities are missing from reporting systems, as the death was not identified as work related.
Most of these fatal incidents, about 72%, involved workers we call arborists, workers employed by tree companies performing residential/commercial tree pruning and removals. These fatalities were mostly among the smaller operations, companies with 10 or fewer employees, though companies of every size had fatal incidents.
Another 4.2% of the fatalities involved arborists performing line-clearance tree-pruning and -removal operations. So about three out of four arboricultural-operation incidents involved arborists engaged in tree work – either residential/commercial or line-clearance – as their profession. The remaining fatal incidents during arboricultural operations were to landscapers or ground workers (19.9%) and a smaller number to workers doing site preparation on building sites (3.9%).
What all had in common was that the worker was engaged in pruning or tree removal when they died. But that was about their only similarity. While the average age was 42 years old, the range extended from as young as 18 or 19 to as old as 72. Some had worked with trees for decades, others for only weeks or even days. While we have reduced these individuals to statistics, we should not lose sight of the fact that they were people and their loss impacted the lives of others around them.
Bring on the Z
No one had to be lost. None of these incidents fit the definition of an accident, an event that was unplanned and unavoidable. True, our events are unplanned. No one comes to work planning to be injured or killed. But our events are avoidable. One means of avoiding events is to follow the American National Standard Z133 for Arboricultural Operations – Safety Requirements, usually called simply the Z133 or the Z.
The Z is a body of consensus standards developed by our peers. If you glance at pages v to vi of the current Z, you will find a list of members and the organizations they represent. Some are at-large members representing workers in the field, while others represent tree companies or equipment manufacturers. Still others represent trade associations or governments. They come together, remotely or in-person, several times a year over a five-year period to review and update the safety requirements for our industry.
The Z is peppered with two terms in particular: “shall” – which means the numbered subsection paragraph is a mandatory requirement – and “should” – which means it is a recommendation. While “shall” means it must be followed, there are a few exceptions in very limited situations. While the Z standard lacks enforcement, sections have been adopted by federal and state-plan OSHA bodies, and they may be considered in citations – another good reason to follow them.
The Z is a long document, 74 pages consisting of eight sections, 43 subsections, 404 numbered paragraphs within these subsections and 10 annexes. It is a dull read, as standards usually are, a publication more likely to be used as a reference than for general reading. This means it might not be read until after an incident, perhaps before meeting with OSHA or lawyers. It would be better to become familiar with the standard now, as adhering to its requirements may prevent an incident from occurring. Better to know and follow the Z, rather than be reminded afterward of what you should have done.
Still, it is a tough read, so here are the subsections, in bold text, that may have prevented the most common fatal incidents during the past year. This does not mean they were the only factors or that the other Z subsections do not need to be read or followed. Think of this as a condensed version.
Contact with an Object or Equipment: 42% of fatal incidents
The most frequent fatal-contact incident during arboricultural operations was being struck by a falling tree during manual tree felling. This is a high-risk activity that we sometimes approach too causally. After all, the tree will fall. The trick is it must land in a precise location. Problems begin when it does not.
The Z has a subsection, 8.6 Tree Removal, within “Section 8 – Work Procedures,” that pertains to felling trees. A factor in the fatal struck-by of chain-saw operators was ignoring 8.6.5. This addresses the planned retreat/escape path when piecing down tree parts or manual tree felling. Most fatalities occur within 10 feet of the base of the tree, and a chain-saw operator can be 20 feet away by the time the tree hits the ground if they move immediately after the felling cuts are completed. Chain-saw operators who stand to admire their felling skills rather than walking along their retreat path sometimes pay for this error with their lives.
Ground workers were not exempt from fatal struck-by incidents. A causal factor in most of these incidents was ignoring 8.6.4. This covers the minimum distances non-involved and involved workers shall be positioned from the tree during removal. Only one person may remain closer than 1.5 times the height of the tree being felled, the chain-saw operator. Some ground workers were just standing by the chain-saw operator and were struck by the tree or debris as it fell. A few died while trying to push over a tree that already had the notch and back-cut completed but was not falling. An equipment operator pushing over a tree also was killed.
Another struck-by hazard during arboricultural operations is a falling cut branch. The Z covers this hazard within “Section 8 – Work Procedures” under two subsections, 8.3 Pruning and Trimming and 8.5 Rigging. The failure to follow 8.3.2, establishing communication among the arborists aloft and other workers on the ground, is one of the common reasons for a falling branch’s trajectory intersecting the path of a ground worker.
The Z requirement is a command and response, not just a command. One incident mentions that the ground worker on the two-person crew ignored the warning that the branch was falling. Calling out as the branch begins to fall is a threat, not a warning.
There is similar language for communication in 8.5.10 and 8.6.11 under Rigging. There are two other requirements under Rigging that also were factors in incidents when they were not followed. The first, 8.5.15, requires that ground workers handling rigging lines not be underneath moving or suspended loads. It is not unusual to see a ground worker tending a line while beneath the load – unfortunately, in one of these cases, with tragic results. The other, 8.6.15, requires workers to position themselves above or to the side of the piece being rigged and out of the path of movement. Three climbers became struck-by fatalities when rigged loads swung back on them.
Brush chippers are a common sight during arboricultural operations. “Section 8 – Work Procedures” has requirements for chipping within subsection 8.7 Brush Removal and Chipping. The hazards of feeding brush improperly and being partially or completely pulled through a chipper are well known. Placing hands or feet beyond the plane of the infeed hopper or pushing wood in with feet is prohibited under 8.7.8. An incident type that is increasing in number and proportion of chipper fatalities is a worker being struck by (or caught in) ropes and winch lines. Ropes must be kept clear of the chipping area (8.7.5). Winch lines must not pass beyond the plane of the infeed hopper (8.7.16).
These are not all the fatal contact incidents. We also had workers struck and killed by chain saws. Climbers also were fatally crushed under the weight of a collapsing palm skirt.
Falls: 31% of fatal incidents
Falls were the leading cause of fatal incidents during arboricultural operations in 2020. This is not too surprising; the trees we prune or dismantle are generally tall, so falls are a common hazard. The arborists who experienced the most fall fatalities were climbers, and they accounted for about two-thirds of all fall-related deaths.
The Z has a subsection, 8.1 Climbing Procedures, within “Section 8 – Work Procedures,” that pertains to climbing. An underlying cause for many fatal falls was failure to follow 8.1.15, which requires a visual inspection of the branch selected as an anchor point. This was either ignored or inadequately performed, as the failure of the anchor branch for the climbing line was frequently identified as a causal factor in a fall. “Rotted” or “decayed” were terms often used in incident reports to describe the failed branch.
A factor identified in other incidents was the climber disconnecting from their climbing system while aloft. This was done either to isolate the climbing line or switch climbing systems. Unfortunately, the fatal slip happened while they were unsecured. This is a violation of 8.1.6, which requires the climber to be secured once their feet leave the ground until they return to earth.
Climbers also fell because they cut through their single means of being secure. A climber severed the flip line with a chain saw in one fall incident; others cut their lanyards. Subsection 6.3.6 requires that a climber operating a chain saw aloft use two means of attachment, with one always being a climbing line and the other either a climbing line, lanyard or flip line.
Finally, climbers fell not from the tree, but with the tree. Either the tree failed at the base, usually during rigging, or the part of the trunk the climber was attached to failed. Observing 8.5.1 within the Rigging subsection – inspecting the tree for defects that might not withstand the forces and strains of rigging – may have prevented these falls.
Aerial-lift operators also suffered fatal falls. The Z has a subsection 5.2 Aerial Devices within “Section 5 – Safe Use of Vehicles, Mobile, and Towed Equipment Used in Arboriculture” that covers the safe operation of aerial devices. Most falls involved the operators falling from the bucket. These fall incidents may have been survivable if subsection 5.2.7.1 was followed. This is the requirement that fall protection be worn and adjusted according to the manufacturer’s specifications.
Wearing fall protection in an aerial device is like wearing seat belts in a car. You only need it when something goes wrong. You might go years or a lifetime and never need the seat belt. Likewise, you might go your entire career and never tumble out of the bucket. But if you do, a properly adjusted fall-arrest harness can save your life.
A factor in fatal falls of aerial-lift operators is the failure to wear, or attach, fall protection. When a falling branch (or tree, in one instance) struck the boom, jostling the bucket, there was nothing to restrain the operator in the bucket or arrest the fall if they were catapulted out. But fall protection only works if it is attached and adjusted. In one incident, the operator was wearing it improperly – the leg straps were not buckled – and, while the fall from the bucket was arrested, the operator suffered fatal injuries.
There were also some fatal falls from ladders. These were often workers in our allied professions. They were usually pruning from the ladder, and the worker lost balance when a branch whipped back. These incidents may have been avoided had 8.1.7 been observed – arborists may not work from a ladder unless secured.
We have not covered all the fatal falls. There are always fatal falls from rooftops and aerial-lift cab protectors.
Exposure to Harmful Substances or Environment: 15% of fatal incidents
This event category covers a number of hazards such as temperature exposure, but the one that results in the most fatalities during arboricultural operations is contact with electric current. The Z covers this hazard under “Section 4 – Electrical Hazards.”
The contact was mostly indirect in about three-fourths of the electrical incidents. The arborist, usually a climber but sometimes a lift operator, did not touch the energized conductor. Something they were holding touched the conductor – usually a metal pole saw or the branch they had just cut. The Z requirements for minimum approach distance (MAD) for a climber’s conductive equipment is made clear in 4.1.7. The MAD for arborists not qualified by training or experience is 10 feet for electrical conductors with a nominal voltage (phase-to-phase) of 50 kV or less. This requirement too often is ignored. Climbers push metal pole saws into conductors every year, and the contact often results in an electrocution.
A green branch, just cut, also can be very conductive, and arborists are too casual in their handling of these branches. The Z does not specifically address this hazard. There is no paragraph that states explicitly that cut branches may not touch conductors. There is the caution under 4.1.4 (c) that woody parts of trees – foliage (including palm fronds) and branches – are conductive. Treat cut branches with the same caution as a conductive tool.
Direct contact with an energized conductor, when the person touched the conductor, mostly involved aerial-lift operators. The operator was not between two phase wires, as frequently shown on warning labels attached to the boom. Instead, the operator touched a phase wire and the neutral at the same time. The neutral caught on the lip of the bucket and the operator touched the phase wire – back of the head – and the neutral. The operator was too close. Aerial lifts, and their operators, also are subject to MAD under 4.1.13.
While they account for fewer incidents, ground workers also were electrocuted by touching an aerial lift that was in contact with an energized conductor, or in one instance, a chipper connected to a truck that was in contact with a conductor. This hazard is addressed under 4.1.14, which dictates that ground workers must move away and remain clear of aerial devices and any attached equipment if the lift is within MAD.
Conclusion
We have not covered all the fatal incidents that occurred during arboricultural operations in 2020 but have touched on nearly 90% of them. Adhering to one or more of the 20 subsection paragraphs identified by the bolded numbers in this article may have prevented many of these fatalities. Another factor would be following everything under “Section 3 – General Safety Requirements” all the time, every job; no matter what arboricultural operation is being performed, it applies and must be followed.
John Ball, Ph.D., BCMA, CTSP, A-NREMT (Advanced – National Registry of Emergency Medical Technicians), is professor of forestry at South Dakota State University and a Board Certified Master Arborist.
Timothy M. Walsh, CTSP, is director of corporate safety with The Davey Tree Expert Company, a 49-year TCIA member company headquartered in Kent, Ohio.
This article was based on John Ball’s and Travis Vickerson’s presentation on the same subject during TCI EXPO ’21 in Indianapolis, Indiana.
