Silica dust and silicosis is a serious issue for building, construction, quarry and tunnel workers. It’s crucial to know how to protect your long term health when working with dust in industry.

Recently, a visiting black lung specialist expressed alarm that at-risk Australian construction and tunnel workers may not be being tested for silicosis. Silicosis is an incurable and often deadly lung disease caused by breathing in crystalline silica.

What Experts Say

“Silica is actually a lung carcinogen. And it causes renal disease, it causes other auto-immune diseases like rheumatoid arthritis and other things, so silica exposure is a huge problem,” said Dr Cohen.

Speaking at a parliamentary enquiry into the re-emergence of black lung disease in Queensland mines, Dr Cohen, who is a professor at the University of Illinois Black Lung Centre of Excellence, expressed concern about silica.

The new (2020) exposure limit has been lowered for silica from 0.1 milligram per metre cubed to 50 micrograms, or 0.05 milligrams per metre cubed, because of the horrendous diseases that occur from silica,” Dr Cohen told the ABC.

However Dr Cohen, speaking with 4BC radio, said the enquiry heard that some Australian workers may be exposed to 0.6 milligrams – six times the Australian and  American limit.

“[Those workers] should really be in a medical surveillance program getting regular chest x-rays and also getting lung function testing,” he said.

He also cited testimony from the enquiry that a large number of workers are exposed to up to six times the legal limit of silica. In spite of this, they are working in tunnels without proper ventilation or respiratory equipment.

Similarly, Dr Cohen said construction workers are high risk for silica exposure.

“These workers are digging foundations but they are also working with concrete: they’re drilling into concrete, they’re jack hammering concrete and they’re cutting it, and that dust that’s generated from those activities is high in silica,” he said.

Exposure and Symptoms

Dr Cohen told 4BC that unless there is a massive intensive exposure to silica dust or silica flour, the greatest danger comes from prolonged exposure over a number of years.

“If it’s intense exposure maybe less than five years, but lesser exposures, 10 years.”

“People develop shortness of breath and cough, they develop an inability to exercise and do things as they used to,” he said. He also added the contributing cause of lung cancer.

Minimising Risk:

As per the hierarchy of control, Dr Cohen said engineering controls are more effective than PPE at minimising silica exposure risk.

Therefore, “One of the most important things is engineering controls to keep the dust levels down… you want water sprays – water to keep that dust down. Ventilation, suction ventilation to suck up and collect the dust.”

Conversely, he suggests “if you can’t control it with those engineering controls, the workers have to be fitted with proper masks,” he said.

Appropriate PPE for silica exposure:

Indeed, ProChoice Safety Gear, Product Development Manager, Brad Rodgers explains what the proper masks are. When dealing with silica dust – if using a conventional respirator – then either a particulate respirator must be used (P1, P2 or P3 filtering respirator) or an air supplied respirator.

In this case, he cited Worksafe Queensland’s guide to managing workplace silica exposure.

To illustrate, “Respirator filters for particles are graded in terms of their performance in removing particles from air to be inhaled. P1 filters have the lowest performance, and P3 filters the highest,” the guide states.

Furthermore, in choosing the respirator with adequate performance, there are two parameters which have to be matched. Notably, these are the:

• required minimum protection factor (RMPF)
• class of respiratory protection.

RMPF = Observed Dust Concentration / Workplace Exposure Standard

Examples in determining the level of respiratory protection needed. (Source: Worksafe Queensland)

Examples of the protection factors of respirators for silica dusts. (Source: Worksafe Queensland)

Lastly, “If the user cannot fit the mask correctly and ensure a suitable facial seal they run the risk of exposure to the airborne contaminant,” Rodgers said. Additionally, Rodgers explained that fit testing a respiratory protection mask is also critical, as per the Australian Standard AS/NZS1715:2009 .