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Preventing Wood Chipper Fatalities

Posted on by Dawn Castillo, MPH; CAPT Cheryl F. Estill, PhD; and Robert Harrison, MD

 

Commercial Wood Chipper
Commercial Wood Chipper. Photo ©Thinkstock

Last week, a 19-year-old North Carolina teen was killed after being pulled feet first into a wood chipper (see news report).  It was his first day on the job.Self-feeding mobile wood chippers commonly used during tree trimming operations consist of a feed mechanism, knives mounted on a rotating chipper disc or drum, and a power plant. Tree branches and trunk sections fed manually into the machine’s infeed hopper are grabbed by the feed mechanism or chipper knives. The chipper disc or drum, rotating between 1,000 and 2,000 rpm, cuts and propels wood chips through the discharge spout usually into a chip truck. The housing containing the chipper disc or drum is sectioned and includes a removable hood that allows access to machine components for maintenance.

The hazards of working with wood chippers are well known and practical methods exist for preventing fatalities.  Links to various resources are provided below.  This is not a new problem.  How do we prevent another horrible tragedy?

In addition to the hazards of working with this dangerous machinery, we know that certain worker characteristics —such as being an immigrant/foreign-born worker, a worker under the age of 25, or an employee of a small business—can increase an individu­al’s risk for workplace injury or illness (see related blog). We also know that temporary workers face additional risks (see Addressing the Hazards of Temporary Employment). Employers need to have safety and health programs that ensure workers are appropriately trained and supervised before they work with hazardous equipment, such as wood chippers.

At 19, this young man was not prohibited from working with this dangerous piece of machinery. Unfortunately, work-related fatalities involving wood chippers have occurred among young people who are prohibited from this dangerous work because of their age as illustrated in the following case study from Youth@Work-Talking Safety Curriculum:

Terrell was a 15-year-old boy who found work with a landscape company when he moved to Maryland with his family. After only a week on the job, he was told to help grind up tree branches, using a motorized wood chipper. As he fed tree trimmings into the machine, Terrell got tangled in some large branches. The machine pulled him into the feed chute and killed him. A co-worker found his body soon after. He shouldn’t have been doing this work because of his age.

Safety Devices

Some chippers are equipped with safety devices to reduce the risk of being pulled into the chipper knives.

Feed control bars, bottom feed stop bars, panic bars, and emergency pull ropes are designed to stop or reverse the feed mechanism if a worker becomes caught. Feed tray extensions provide a physical barrier between the feed mechanism or chipper drum and the operator. Wooden push bars allow workers to feed short branches into the machine without placing their hands in the infeed area. See OSHA Safety Bulletin: Hazards of Wood Chippers.

Prevention

To protect workers from being caught by the chipper feed mechanism, employers should ensure the following:

  • All safety devices and controls, such as emergency shut-off devices, are tested and verified to be functioning properly before the chipper is used.
  • Workers are trained in safe work procedures, including operating wood chipper safety devices and safety controls. These procedures should be based on the manufacturer’s recommendations for each machine.
  • At least two workers are in close contact with each other when operating the chipper.
  • Workers wear close-fitting clothing, gloves without cuffs, trousers without cuffs, and skid-resistant foot wear. Clothing should be kept tucked in.
  • Workers’ hands and feet remain outside the infeed hopper.
  • Workers feed brush and limbs into the infeed hopper butt end first.
  • Workers feeding material are positioned at the side of the machine to allow quick operation of the emergency shut-off device and minimize risk of entanglement in branches. Because of differences among machines, the manufacturer’s operating manual should be consulted for guidance. Safe feeding of some disc-type chippers requires the worker to be on the right side.
  • Workers walk away once the feed mechanism has grabbed the material.
  • Workers lay short material on top of longer material that is feeding or use a longer branch to push it through the infeed hopper.
  • Workers load small raked-up material such as twigs and leaves directly into the chip truck or in trash cans or bags instead of feeding it into the chipper.
  • Workers keep the area around the wood chipper free of tripping hazards.
  • Workers wear hard hats, eye protection, and hearing protection. 

Workers have also been killed when struck by flying hoods covering wood chipper discs or drums. Recommendations on how to prevent this hazard can be found at Hazard ID 8 – Injury Associated with Working Near or Operating Wood Chippers.

Help us spread these prevention recommendations and share your ideas on how we can prevent future tragedies in the comment section below. Do you have suggestions on how engineering controls can make wood chippers safer?

Dawn Castillo, MPH, is the Director of the NIOSH Division of Safety Research

CAPT Cheryl F. Estill, PhD is an Industrial Hygiene Supervisor in the NIOSH Division of Surveillance, Hazard Evaluation, and Field Studies and the Coordinator of the National Occupational Research Agenda (NORA) Services Sector Council.

Robert Harrison, MD, is a Professor of Medicine at UC San Francisco and Chief of the Occupational Health Surveillance and Evaluation Program at the California Department of Public Health. 

 

Many of the cases mentioned here were identified through the NIOSH-funded FATALITY ASSESSMENT AND CONTROL EVALUATION (FACE) PROGRAM. Investigations conducted through the FACE program allow the identification of factors that contribute to fatal work-related injuries. This information is used to develop comprehensive recommendations for preventing similar deaths.

For More Information

Posted on by Dawn Castillo, MPH; CAPT Cheryl F. Estill, PhD; and Robert Harrison, MD

7 comments on “Preventing Wood Chipper Fatalities”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    I work in safety and compliance for the trade association for commercial tree service companies, and I heartily endorse all the prevention measures listed above for hand fed brush chippers. I put particular emphasis on the need for hands-on training, close supervision of the newly trained employee until they demonstrate proficiency in safe chipper operation, and then regular observation/inspection of operators as well as fairly frequent “refresher” training to keep awareness high. Obviously this victim had absolutely no experience and no training. In our studies of chipper accidents we that 18% of all victims had been on the job less than 3 months, but that 29% had worked for 3 months to a year, and the rest, 53%, had at least a year’s experience. That suggests that operators become complacent with the deadly power of these machines and need frequent reminders. In experiments conducted at South Dakota State University using life-size “rescue dummies,” it was determined that a mechanical infeed chipper could amputate one’s hand in less than half a second, and that the entire dummy could go through the machine in as little as 1.2 seconds. So while a second employee in near proximity when the chipper is being operated is a good idea, it is not enough to prevent accidents. Proper, safe operation as detailed in the prevention steps above is really the key.

    Over a nine year period, more than 19 workers across
    the UK. were killed in accidents when using wood chippers and 08% of all victims had been on the job less than 3 months, in Uk theres so many man and van that provide this service and some times they dont have the experience needed

    I agree that it takes a certain level of maturity to be able to work with dangerous equipment. The high amount of safety precautions that must be observed when working with a wood chipper requires common sense that is not often found within teens. Although there are no regulations of age requirements to operate wood chippers, it may be a good idea for employers to be extra cautious of prospective employees machine operation capabilities and expertise.

    I’ve operated many types of machinery. The chipper is the most dangerous because it doesn’t require an operator. If you drive a car the car needs an operator to apply gas and brakes. Chippers run wide open hands free. There would be nearly ZERO chipper fatalities if someone had to manually push the button to feed and without that it stops. Remove the automated feeding, make it require an operator like every other piece of equipment.

    Safe tree removal processes
    In addition to the various pieces of safety gear tree removal professionals wear while on the job, they take precautions and follow strict regulations. The regulators outlines various tips for tree removal experts on how to stay safe, including they assume all power lines are energized and to contact the utility company about de-energizing or grounding the lines before the work starts. They also have other precautionary tips involving alertness and hazard assessments on their Quick Card page.

    Some of what keeps tree removal experts’ safe is they do not work during any sort of inclement weather. If there are winds, snow, hail or any other sort of weather that could put them in harm’s way, they will reschedule for a better day. This is because risk increases with bad weather. They also plan ahead before starting the job. They examine the site for any hazards, whether it’s weak limbs, broken branches, dead or rotting wood, poisonous insects or plants, or any other potential problems. They see where the power lines are, in case they’re within close proximity and need to have rope for directing the tree’s fall or should speak with the utility company. They also observe the tree for its size to assuage the best way to take it down, whether it’s small enough to cut with a chainsaw or needs to be scaled for cutting as a larger tree. They also wear their safety equipment at all times, which keeps them from getting hurt.

    During the tree removal process, professionals follow a procedure that gets the tree down in the safest way possible for them and the homeowner. They will estimate the felling zone, leaving plenty of room for the fall, cut a notch into the tree and place a wedge there on the falling side to help with direction. While cutting, they will be aware of any kickback limbs that could put them in danger of falling or injury. Then they will drop the tree using rope to guide it down into the yard, where no one is in danger of getting hurt as well as keeping the tree away from power lines to avoid electrocution or blackouts. They will remove limbs on the outside and then work in to keep it from being a problem when they will lift it later. If the limbs are not cut close to the tree, they could put out someone’s eye or cause other injuries to personnel. Then they will cut the tree down into smaller pieces and haul it away.

    Homeowners are seriously encouraged to not attempt this job alone with the risks involved. There are always tree removal professionals in the area who have the skills and safety training to perform the task for a good price. You can find a listing of tree removal experts in your area.

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