Silica dust is 20 times more toxic than coal dust.
"Black Lung Study Finds Biggest Cluster Ever of Fatal Coal Miners disease in the US"
In the US there is a disturbing trend for coal mine workers with 416 new cases of complicated black lung from 2013 to 2016. The report goes on to identify silica as a "potent lung irritant". Silica in the lung causes the body's immune system to respond. However, the substance is unbreakable as it is not bacterial or viral. This causes cells to die and leads to inflammation which damages the surrounding lung tissue. The lungs continue to be damaged overtime by this sequence eventually depriving the victim of air.
"Tyrone Buckton never spent a day underground - Coal miners death after silicosis diagnosis a warning on dangerous dust levels"
The report from the ABC says that Tyrone Buckton never spent a day underground and was diagnosed with silicosis last October.
What is silica dust?
Crystalline silica is found in rock, stone, and sand. It’s one of the most common elements on the earth’s crust. It’s a class 1 carcinogen when it is airborne typically by mechanical processes such as blasting, crushing, conveying, excavating, quarrying, etc.
Silica Dust and cancer
Silica dust is 100 times smaller than a grain of sand, it’s invisible. You would not be aware that you are inhaling these tiny particles which can remain airborne for days. Once in the lung silica particles can lead to cancer, silicosis (irreversible stiffening of the lungs), chronic obstructive pulmonary disease and kidney disease.
- Particles below 10-microns are easily inhaled into the lungs.
- Particles below 5-micron can get permanently lodged in the lungs thus increasing cancer rates amongst workers at greatest risk: miners, construction workers, farmers, and engineers.
In Australia, the mandatory limit for silica dust is 0.1 mg/m³ over an eight-hour day. This is an outdated prevention of cancer and silicosis as there is no safe level of silica exposure. The American Conference of Governmental Industrial Hygienists endorses their threshold limit be 0.025mg/m³ and the new OSHA rule limit is 0.05 mg/m³.
What is the best practice?
Every aspect must be a conduit to "prevention" for mine and quarry sites with the following key areas:
- Workers need to be aware of airborne hazards
- All controls should be aimed at containment and/or removal of the generated dust at source (PPE is the last resort).
- Drills should have dust extraction systems with collectors fitted.
- Loaders and trucks should have well-maintained air conditioning systems pressurised with HEPA filtration.
- Any practice of operating with doors or windows open must be avoided.
- Keep door and window seals in good order.
- Cabins of loaders and trucks should be cleaned regularly by HEPA vacuum to avoid constant disturbance of any accumulated dust.
- Roadways should be watered constantly during dry periods.
- Suppressants can be useful in some cases. In-ground sprays can be used in some cases.
- Ensure that vehicle exhausts do not point down at the road surface.
- The crushing plant should be operated from enclosed cabins that have adequate air-conditioning and HEPA filtration system fitted and pressurised.
- Remove dust build up (which arises from shoes, etc.) from cabin regularly and preferably daily by means of a HEPA vacuum.
- All transfer points should be fitted with dust boxes and ideally filter type extraction systems.
- Screens should be enclosed in either a clad structure or by rubber dust covers.
- Any onboard enclosure such as electrical cabinets should have HEPA filtration & pressurisation systems to avoid dust contamination in the first place.
"As we do not know a safe limit. We must aim to eliminate all exposure".