Human vibration: addressing a less spoken about hazard

Australian Institute of Occupational Hygienists experts reveal what mining companies can do to mitigate human vibration exposure and reduce back injuries while their employees operate on the bumpy ground of mine sites.

Human vibration exposure has been one of the top five health hazards at mine sites for more than a decade, both by the number of workers harmed and worker compensation figures.

Despite this, a laser focus on dust and lung diseases has left vibration exposure in its current state for the past five years.

An Australian Institute of Occupational Hygienists (AIOH) member for 17 years, Dustin Bennett says prior to this, the mining sector leapt forward in its management of human vibration exposure.

This was signified by major mining companies dedicating control programs to tackling vibration and noise on mine sites.

They had identified the risks, effective controls and best practice for each of their sites, leading to investment in new mobile plant and a host of other controls.

This had pushed the industry forward in its management of vibration exposure, which is now considered a standard industry practice nationally. But without additional engineering controls, workers have been left to their devices in dealing with the health hazard.

In 2009, Australia’s Attorney-General’s Department released a report that acknowledged the link between occupational exposure to hazardous levels and vibration.

It was associated with adverse health outcomes such as white finger, carpal tunnel syndrome, musculoskeletal disorders and neurological disorders, with two main types of vibration being hand-arm vibration and whole-body vibration.

Approximately 24 per cent of Australian workers were exposed to vibration in their workplace, with this figure skewed more towards younger workers than older workers.

In addition, workers expressed that such exposure was mostly associated with roles such as machinery operators and drivers, among others. Only 27 per cent of them said they had received training in this space.

By 2015, Safe Work Australia reported that a total of 5260 workers had submitted compensation claims for injuries attributed to vibration exposure over the past 14 years.

AIOH member Vasos Alexandrou concurs with Bennett, saying that the mining sector has not acted in its maximum capacity to protect workers from vibration.

“We’ve been involved with some mine sites and industries where they’re proactively paying attention to noise and vibration, but many of them haven’t emphasised on these issues or are doing the bare minimum for checklist purposes,” Alexandrou, who has been completing various occupational assessments of the mining industry for 14 years, says.

“Speaking from my experience, coal mining presents the highest vibration exposure, for the simple reason that they have to dig deeper into harder material to access good-quality coal.”

Bennett adds that underground workers are also typically more exposed to seated vibration than their open cut counterparts due to the ground conditions and mobile plant designs.

To date, engineering controls are still considered the best control for vibration exposure. New mobile plant generally do a better job at attenuating vibration than ageing plant, according to Bennett.

He says advancements in vehicle suspension and cabin mounts (chassis to cabin) have been an important control to attenuate the transmission of vibration to the worker.

This ensures that certain vibrations and frequencies are mitigated before they reach the operator.

“The best bang for buck is to control vibration to the worker right from the original equipment manufacturer’s (OEM’s) design phase,” Bennett says.

“There can be more done to influence OEMs to bring new controls to the latest plants. This is the most valuable thing that the mining sector can do to mitigate operators’ vibration exposure: to urge OEMs to accelerate development of new controls.”

Such a proposal stems from the difficulty in measuring the level and type of vibration exposure, which depend on ground conditions right through to an operator’s individual characteristics and driving style, and therefore coming up with a simple control that covers all.

But what mining companies have done well is ensure that roads are graded, potholes are covered, and employees are placed in shift rotations to limit their exposure to tasks with high levels of vibration, according to Alexandrou.

Such tasks include the operation of ground engaging plants, such as excavators, graders, loaders and most particularly bulldozers.

Bennett says that the measurement of vibration levels at the seat can help evaluate the time that needs to be allocated to high-risk tasks so that workers remain within the exposure guideline.

Regardless, operators should understand how to set up their seats correctly.

“A common example that leads to injury is when a heavier person, who weighs 120 kilograms doesn’t adjust the seat-spring mechanism after handing over from a light person who weighs, say, 60 kilograms,” Bennett says.

“That heavier operator then runs over a rock that causes the seat to ‘bottom out’ and hit the bump stop, leading to a lower back pain caused by shocks and jolts. This is a tangible and instantaneous injury that miners often focus on.

“One of the best things for mining companies to do is to teach employees how to adjust their seats to their individual characteristics. Not only to prevent shocks and jolts, but reduce long-term vibration exposure.”

Although the case of vibration exposure puts the onus on companies to limit hazardous vibration exposure for their employees, workers have a power to manage their vibration exposure level.

While mining companies should monitor such exposure on a daily basis due to ever-changing working and ground conditions, Alexandrou says it is also important for plant operators and drivers to understand the effect of their driving technique on the smoothness of a vehicle operation.

“Just when car passengers and vehicle won’t be too happy when a driver accelerates or decelerates harshly while driving down a public road, so should plant operators take care, especially when they’re driving heavy vehicles for 10 hours a day for 50 per cent of the year during their seven-day on, seven-day off roster,” he says.

Regular monitoring of vibration levels under varying conditions will assist in identifying and understanding vibration exposure to working personnel.

From here, administrative and engineering controls can be reviewed with a view to minimising vibration exposure and levels.

This article will appear in the Mar-Apr issue of Safe to Work.

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