Capturing harmful mine dust with next-level solutions

A lot can happen in a few months. In the dust control world, mining companies have made significant strides towards creating a safer workplace for employees. Safe to Work speaks with Breathe-safe director Nick Johnstone about what’s next.

Governments, mining companies, and health authorities have started to ramp up their actions over the past 18 months to minimise workers’ exposure to respirable mine dust.

This action has culminated in a greater understanding, coupled with more accurate real-time dust level monitoring and testing of samples to identify what is contained in the dust and their respective fractions.

The various fractions must always be considered. Crystalline silica is just one of the well-known and harmful respirable mine dust. According to Nick Johnstone, director of air filtration provider Breathe-safe, several other unsafe particles can also enter the lungs.

“We all know about asbestos and diesel Particulate Matter (DPM) as they are another group one carcinogenic substances floating in the air,” Johnstone tells Safe to Work.

“Inhalable dust and DPM haven’t vanished. It’s just not the hot topic.

“As we move forward, we will see companies testing samples from many different locations around their site, as we now believe that the same base material can behave differently at different stages of the process. Testing the actual material captured at a specific location is the best way to get an accurate breakdown of the material.”

These different locations will show different concentrations of the various hazardous substances, including DPM, Johnstone continues.

“HEPA (high-efficiency particulate air) filters not only capture crystalline silica but DPM solids very well,” he says.

“They knock it out of the park by reducing DPM exposure by more than 99.97 per cent.”

Johnstone says within months of the Queensland Department of Natural Resources, Mines and Energy (DNRME) release of the Recognised Standard 20 (RS20) late last year, the sector’s biggest players were running air quality trials to test their ability to reach below the new limit of 0.05 milligrams per cubic metre.

He praises Australian mining companies for jumping into the initiative to provide better workers’ protection against respirable dust.

“The goal must be zero exposure as this is the only way to ensure zero harm,” Johnstone says, enthused.

“Our Dual INPRESS HEPA system exceeds the requirements listed in RS20. Our latest filter has been upgraded to H14. We have been auditing our systems with Nanozen personal dust monitors.

“One of the many benefits of using the dust count unit is that it has an in-built sample filter that you can analyse. Once analysed, you can choose to calibrate the personal dust monitor for your specific type of mine dust.

HEPA recirculation filter installed on a Hitachi EH5000 dump truck.


“A Queensland mining company has run a trial on its dozer fleet, and we are now installing our Breathe-safe INPRESS system to every one of its dozers. An efficient Dual HEPA filtration system is the way to meet the proposed 0.02 milligrams limit.”

According to Johnstone, mining companies are quickly reacting to this industry-wide change. But if it were not for COVID-19, they would’ve reacted even faster.

“I’m very, very confident that we can achieve more than what we’re already doing,” he says.

The type of masks primarily worn by frontline health workers to protect against COVID-19 is the N95 respirator. The name indicates its 95 per cent efficiency in catching airborne microbes when fitted correctly.

But exceeding that are HEPA H13 filters. They have a 99.97 per cent efficiency, theoretically providing a much higher level of protection and effectiveness in capturing coronavirus droplets. These filters are driving a lot of interest among Australian mining companies, Johnstone says.

“By installing HEPA filters to both the fresh air intake and recirculation air intake on a machine, you will provide a better protection factor than an N95 or P2 mask. Ideally, this is what you want to do,” he explains.

“I must note this will provide the best protection for airborne particles. I would recommend that you implement cleaning and sanitising of any surfaces in the equipment to prevent any possibility of virus transfer via contact.

“We have got machines that are achieving the proposed standard by Safe Work. Now that users understand the importance of a pressurised cabin using HEPA H13 filtered air, the two main drivers to fulfil the standard are a greater understanding of the importance of installing HEPA return air filters.

“When it comes to air quality, the HEPA return air filter gives you a great bang for your buck. Check out the National Institute for Occupational Safety and Health (NIOSH) studies. The second one is real-time particle counters to accurately access where the dust exposure is coming from. It comes down to addressing the spikes in dust exposure.”

For Johnstone, mining operators will see what’s causing most of the spike in workers’ dust exposure as they analyse the real-time data. This could tie in closely with a particular task that’s carried out in a specific area, at a certain time.

With more accurate and real-time testing available, mining operators can eliminate these instances of spikes, so that workers’ dust exposure can drop below even the originally proposed standard of 0.02 milligrams per cubic metre.

“If available, engineered solutions have been proven to reduce workers’ dust exposure to below the current limit. There would then be no reason for the industry not to drop to the originally proposed limit,” Johnstone says.

Further, the mining industry’s onset of autonomous operations will not eliminate the need for HEPA filtration systems in machines.

In the words of Johnstone, the technology installed in these machines is an absolute “state of the art.” But one thing about state-of-the-art machines is their vulnerability to breakdowns due to mine dust.

“We have been using the same grade filters to look after the electronics. As mining autonomy moves ahead, HEPA filters will still need to be installed to protect both the electronic heart of the machine and the heart and lungs of the operators and service personnel working on them,” he concludes.

This article also appears in the July issue of Safe to Work. 

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