There’s a way to avoid being harmed by mine dust including crystalline silica on the east coast and asbestos fibres on the west coast. Breathesafe director Nicholas Johnstone tells Safe to Work about the solution.
Workers’ protection against respirable dust particles can and should be likened to one’s experience driving down the streets in a Mercedes Benz or BMW. At least so, according to Breathesafe owner and director Nicholas Johnstone.
“If you go and buy a new luxury car,” says Johnstone, “it’ll come with pollen filters, and pollen filters are actually a low-grade high-efficiency particulate air (HEPA) filters. So when you’re driving around town, you don’t get exposed to pollen, hay fever, DPM (diesel particulate matter) or exhaust smells.
“You sit in your new car and you have some protection from these low-grade hazardous dusts and exhaust.”
But machine operators are in their cab for 10 to 12 hours a day, and what surrounds them is not low-grade hazardous dust and fume but silica, the same material that is killing the stone masons working with artificial stone used in kitchen benchtops.
Black lung – an umbrella term that covers quite a few different illnesses of the lungs including silicosis – is caused by respirable coal dust and respirable silica dust. The lung disease is triggered by the size of the dust particle and the silica contained in it, and may take 20 years to expose itself, Johnstone explains.
But most machines at best use a standard engine grade filter and not a HEPA filter inside the cab, and these standard filters only target larger dust that can damage the engine.
“At the end of the day, you can have an inch of dirt on the floor. But that inch of dirt on the floor isn’t really the dangerous dust,” says Johnstone.
“Original equipment manufacturers (OEMs) want to remove the big dust that you can see, but the problem is the small stuff you can’t see.”
According to Johnstone, the current limits for silica are based on outdated standards which are higher than most developed countries.
Australasian Faculty of Occupational and Environmental Medicine (AFOEM) and Royal Australasian College of Physicians (RACP) recommend time-weighted average of respirable dust exposure to be immediately reduced to 0.05mg/m3, with further research to adopt the 0.025mg/m3 level as per the recommendation of the American Conference of Governmental Industrial Hygienists (ACGIH).
“But instead of talking about 0.5mg/m3, we should be talking about 0.025mg/m3,” says Johnstone. “In essence, silica dust should be undetectable in the breathing zone.”
Breathesafe’s H13 grade HEPA internal filters can remove more than 99.97 percent of all dust particles bigger than 0.3 micron in diameter – those that can’t be seen by the human eye.
“That means we go from really not doing anything, to being as close as humanly possible to eliminating it completely from the breathing zone,” says Johnstone.
When standard engine grade filters are being used, the unseen respirable dust goes into them only for the operators to be exposed to that same dust again. After all, these standard filters are only capable of capturing the larger dust.
“If you investigate that mg/m3 measurement, then yes, technically the reading is below the limit if measured in mg/m3. But in reality, the operators are getting exposed to as much respirable dust as they were years ago,” reveals Johnstone, who has been involved in the management of dust for over 13 years.
“On the other hand, HEPA filters can get the air quality in that cab better than in your office, wherever you’re sitting right now.”
Johnstone, after crossing paths with workers who had recently been diagnosed with silicosis of the lungs in Central Queensland, can see an increase in lung diseases now that new technologies are being introduced to mine sites.
“There’s one thing that computers do not like: dust,” Johnstone says.
“When a computer fails, or a sensitive component keeps on failing because of dust and overheating, mining companies get a very large bill as some parts are over $100,000.
“So workers now have to clean these new sensitive components using brushes and/or compressed air, exposing a group of workers, electricians and trade assistants to extreme amounts of respirable dust that they’ve never been exposed to before.
“Keep in mind that the operator is also sitting in a cab less than four metres away in the same environment.”
Grasping close to zero exposure
It is not common sense to drive one’s Land Cruiser off road with the windows open.
The same goes for operating a machine in this hazardous environment.
“Whenever I get told there’s dust in the cab, I can have a look into the information from my controller and tell what the issue was,” Johnstone says.
Johnstone finds machine operators running their machine with the window or door open, generating this dust the majority of the time. But in reality, the cab can be kept “spotlessly clean” when drivers keep their windows and doors closed.
Giving almost zero exposure of respirable dust to mine operators is not unattainable, says Johnstone. He’s confident that many products in the market, including his company’s Inpress TL system, with HEPA filters can deliver this clean, high quality air.
Johnstone puts it simply: “All the mine sites talk about zero harm. Well, zero harm caused by silica can only be achieved by zero exposure to silica.
“The cost of the system is, however, in the next side of the equation. I’d say most [dual HEPA filtration systems with a pressure monitor] can be supplied and installed for as little as $5750 – it’s not a big-ticket item.
“There was a time over five years ago that [HEPA filters] were two to three times the cost they are now, but we have designed and manufactured a product that is so cost-effective it’s scary.”
Ongoing costs using a dual HEPA system with auto cabin pressure control usually work out to be the same cost as using OEM filters. This initial cost is recovered due to a dramatic reduction in air conditioning maintenance cost as soon as HEPA filters are installed.
“A lot of [lung diseases] are being blamed on people smoking, and obviously there were a lot of people in mining smoking once upon a time. But that’s over now – we are close to 10 years into a majority of workers not smoking,” Johnstone points out.
“In the next 10 years or so, there will be workers who have spent over 15 years on mine sites who have never smoked, and if we do not do anything about it, they will start getting sick from occupational lung disease.”
Johnstone says most mine workers move from site to site or even state to state throughout their career. But if they develop an occupational lung disease one day, they may not be covered by workers compensation because they have relocated.
“It’s heartbreaking, to be honest. We’re at the tip of the iceberg now. There are countless discussions and studies going on around the world, and they’re all coming up with the same conclusion all respirable dust is harmful,” admits Johnstone.
“There are people in the industry who seem to be of the opinion that it’s mining, it’s dusty, that’s just the way it is. Well, they are right. It is dusty. But it does not mean anyone needs to be exposed to it.”
This article also appears in the Jan–Mar edition of Safe to Work.