Health Risks
FOR HEAVY EQUIPMENT OPERATORS

by Nadine Marks, B.Sc. (P.T.) Project Coordinator, CSAO

Unique risk factors

Heavy equipment operators are exposed to risk factors considerably different from those in other construction trades. Prolonged sitting, whole body vibration, and the repetitive operation of controls are major risk factors for work-related musculoskeletal disorders (WMDs) among operators.

Injuries

Workplace Safety and Insurance Board (WSIB) injury reports show that the average number of lost-time injuries (LTIs) for operators in the period 1994-1996 was 102 per year. Based on total injuries reported, 29% were to the back, 12% to the shoulder or arm, and 9% to the ankle. Back injuries to equipment operators are higher than the industry average for construction (25%). The majority of the back injuries (43%) were caused by overexertion, followed by slips and falls (22.5%). Most of the back injuries occurred while lifting (42%), followed by operating equipment (26%) and dismounting (14%).

Other research reveals that the most common work-related symptoms reported among operating engineers include shoulder problems, low back pain, stomach disorders, general fatigue, and irritability. These are caused by

• work position
• whole-body vibration (WBV)
• segmental vibration
• visual work
• environmental factors such as weather, diesel fuel exhaust, and noise
• psychological stress.

Work Position

Heavy equipment operators are required to sit for extended periods of time. Sitting exerts almost twice the pressure through the back that standing does. Sitting flattens out the small of the back. This increases pressure on the spinal discs and limits their ability to absorb vibration. In addition, back muscles tire, become stiff, and start to hurt when the back is in one position for any length of time.

During extended sitting, ligaments in the back stretch and slacken. Even after you stand up, they remain stretched and slack for a while and cannot properly support the low back. For this reason, lifting immediately after prolonged sitting increases the risk of back injury.

Other causes can also contribute to injury in the heavy equipment operator. Back and neck muscles must work continuously to hold the head in position, especially in the presence of vibration. This exertion can lead to sore tired muscles and muscle strain.

The repetitive operation of equipment controls also entails risks. Holding a foot pedal down over a long period of time may cause stiffness and spasm in the legs and low back. Operating hand controls may result in a repetitive strain disorder of the arm with shoulder or elbow tendinitis. Additionally, in colder weather operators may experience arthritic symptoms in the hands and/or Raynaud's syndrome. This syndrome is called "white finger disease" because constriction of the blood vessels causes whitening of the fingers as well as pain or numbness.

Posture is Important

Recommendations

• Maintaining proper posture is important to good back health. Backrests are designed to support the natural curves in your spine, especially the low back lumbar curve. A backrest (lumbar support) will improve the seat's shape and your own posture. The right backrest for you will depend on your build and the size and shape of the equipment seat. If a back support is not available, a rolled-up towel placed in the small of your back can help.
  
• Don't drive with your wallet in your back pocket. The wallet may put your spine out of alignment and exert pressure on your sciatic nerve, which can lead to back and leg pain.
  
• Maintaining good sitting posture is important. But sitting is still hard on your back and requires frequent changes of position. Try to get out of your vehicle for a couple of minutes every hour or two and gently stretch backwards. Ideally, the back of your seat should be tilted at 110 degrees from your legs to reduce disc pressure and relax back muscles.
  
• Avoid lifting immediately after driving. The first two to three minutes after you exit your vehicle is a high-risk time for injury. Your muscles are tired; your ligaments are stretched and unable to support your spine properly; your spinal discs are at risk of injury. Give yourself a couple of minutes to stretch and rest before trying to lift anything heavy. A standing back bend, slow and easy, will help reduce the stress on your spine from sitting.
  
• Avoid jumping down from your vehicle. The impact of jumping puts additional stress and shock on your spine. Over the years this can result in low back injury. Jumping down from vehicles may also cause knee and ankle injuries. Always face your vehicle when dismounting and maintain 3-point contact. Remember that 14% of back injuries to heavy equipment operators are caused by improper dismounting from the vehicle.
  
• If possible, adjust your seat and steering wheel so that you can use the pedals and still keep your low back in contact with the seat back.
  
• When driving for long periods, shift position occasionally to give your back a change of position.
  
• Before entering or exiting the cab, slide the seat back. This will give you more room and prevent the need to twist. Try to keep your back straight and avoid twisting when getting in and out. Bend at your hips and knees rather than at your back.

Consider these ergonomic points:

• Frequently used controls should be in the most favourable position for reaching and grasping. Displays should be located so that they can be read accurately from a normal operating position.
• Armrests should be available to help reduce postural stress to the back and should fold up out of the way at the operator's discretion.
• Cabs should be equipped with adjustable seating that provides good lumbar support. Seating material should be suitable to vehicle type. Ideally, an air suspension system with individual weight adjustments is best.

Three Sources of Vibration

Whole Body Vibration

Whole body vibration (WBV) is a form of mechanical vibration transmitted through a supporting surface to the body. Heavy equipment vibration is transmitted through the seat of the vehicle to the operator's spine.

Operators are subjected to various sources of vibration:

• low-frequency vibration caused by tires and terrain
• high-frequency vibration from engine and transmission
• shock from running into potholes or obstacles.

Long-term exposure to whole body vibration may cause low back disorders such as disc herniations, may accelerate degenerative changes in the spine, and may lead to problems with the urogenital and gastrointestinal systems (abdominal pain and nausea). WBV has also been shown to affect the cardiovascular system (increased heart rate and blood pressure).

Because of these health concerns, the International Standards Organization (ISO) has developed a standard providing numerical limits for exposure to WBV. But even when vibration levels are within ISO standards, other factors may influence operator exposure, such as how well the machine is maintained, the type of terrain travelled, seat design, and vibration from other equipment.

Additionally, operators are often required to drive backwards or look from one side of their vehicle, forcing them to adopt a twisted posture. This is considered a risk factor for the development of back and neck disorders. When a vehicle hits an unexpected pothole or bump, the operator's muscles may not have time to contract properly to protect against neck and back injuries. In fact, 12% of back injuries to operators are due to shocks or jolts sustained while driving.

Poor ergonomic design of cabs, seats, and controls can also affect the operator's musculoskeletal health.

Recommendations

• Maintain equipment in sound working order. A good suspension system and correct tire pressure will help to reduce vibration.
• Use specially designed cushions with vibration-reducing material.
• Take extra care and reduce travel speed over rough terrain (shale or rock).
• If possible, tilt your seat a notch or two every 30 minutes. This alters the direction of vibration through your body and helps reduce its effects.
• Try to get out of your vehicle every one to two hours for a few minutes to give your body a break from vibration.

Segmental Vibration

Segmental vibration is transmitted through the hands and arms and is known to cause specific health effects such as Raynaud's syndrome (white finger disease). Construction workers are exposed to segmental vibration when using equipment such as grinders, jackhammers, and power tools. Heavy equipment operators are exposed to segmental vibration when they operate controls.

Equipment operators may report symptoms of Raynaud's syndrome or arthritis in their hands, especially in colder weather.

Recommendations

• Wear gloves to keep your hands warm in cold weather.
• Take breaks when possible and stretch your fingers and hands.
• Equipment controls should have vibration-reducing material built into the grips.

Visual Work

Operators must not only operate equipment but also keep an eye on site activity at all times. They have to monitor their changing environment and watch for overhead powerlines, underground utilities, obstacles, site traffic, signallers, and workers on foot. As a result, eye strain and fatigue can become an occupational hazard.

In addition, poor visibility from the cab, reduced visibility in rainy or winter conditions, and glaring sunlight on bright days can contribute to eye strain.

Recommendations

• When possible, take breaks and give your eyes a rest.
• Ensure that there's an adequate number of defogging vents in the cab and that they're located in the correct position to prevent side and back windows from fogging up.
• Keep windshield wiper blades in good working condition.
• If reflection or glare makes displays difficult to read, use shields or filters.

Improved Cabs Reduce Risks

ENVIRONMENTAL FACTORS

Weather

Equipment operators must work in all kinds of weather. In summer they may have to contend with heat in cabs that aren't air-conditioned. In winter, ice and snow can make mounting or dismounting from equipment hazardous and lead to slips and falls. Controls and grips may also be cold and contribute to Raynaud's syndrome or arthritic conditions of the hand.

Recommendations

• Cabs should be equipped with adequate air-conditioning in summer and heat in winter.
• Allow extra time in winter to clean ice and snow from equipment.
• Take it slow and easy when getting in or out of equipment in winter. Always maintain 3-point contact and face the vehicle to avoid slips and falls.

Noise

Operators are exposed daily to high levels of noise from heavy equipment. Research has demonstrated that excessive exposure to noise in the workplace may induce hearing loss. Noise exposures on Ontario construction sites are not regulated. But the industrial regulations stipulate a maximum of 90 dBA exposure for eight hours.

A CSAO study concluded that operators in equipment with no cabs or with open doors may be exposed to levels exceeding 90 dBA for an 8-hour period. Bulldozer operators in the study had the highest average exposure at 102.4 dBA.

Recommendations

• Cabs of heavy equipment should be enclosed to reduce noise and air-conditioned to allow operators to keep doors closed.
• Periodic maintenance should be carried out to reduce noise caused by equipment that is not well tuned or working properly.
• Hearing protection programs, including training in the proper use of plugs and muffs, should be implemented.

Diesel Exhaust

The chronic effects of diesel exhaust exposure can include lung function disorders and lung cancer. Studies have reported an excess risk of lung cancer in heavy equipment operators, attributed in part to soot particles and constituents such as benzene in diesel fuel exhaust.

Recommendations

• Ensure that the equipment is in good working condition and properly maintained. Pay particular attention to the exhaust pipe and check for any leaks in the system.
• Further research should be conducted to determine levels of diesel exhaust exposure among equipment operators.

Psychological Stress

Heavy equipment operators are exposed to psychological stress from the physical conditions already described: the size and power of the equipment they operate, changing site conditions that require constant monitoring, exposure to hazards such as vibration and noise, prolonged sitting, and the repetitive operation of hand and foot controls.

Additionally, they may work for 4 or 5 hour stretches in virtual isolation, responding only to signals from co-workers. Operators may work 10 or 12 hour shifts during the construction season. Fatigue can be a significant factor in their overall psychological well-being.

Recommendations

• Employers and supervisors should 1) be aware of the physical and psychological stress under which equipment operators must often work and 2) understand the controls and practices that can help to reduce stress.
• Ergonomic improvements in cab design can help to reduce musculoskeletal hazards and some of the psychological stress that goes along with them.
• Operators should be encouraged to do a pre-work warm-up and take enough stretch breaks to reduce their exposure to vibration and prolonged sitting.
• Exercise programs and active forms of recreation to keep fit can improve mental attitude and reduce the risk of musculoskeletal injury.

Conclusions

Strategies to reduce work-related health problems among heavy equipment operators should include the following:

• in-depth evaluations of vehicle designs to determine possible improvements
• in-depth evaluation of work practices to identify safer, healthier approaches
• implementing sound ergonomic procedures
• training workers in how to prevent musculoskeletal injury
• focusing attention on the psychological aspects of operating heavy equipment in the unique construction environment.

Through their coordinated efforts, contractors, equipment manufacturers, suppliers, unions and workers can help to reduce and control the occupational hazards affecting heavy equipment operators.

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