Firstly let’s look at some facts
Crystalline silica (silica) is found in sand, stone, concrete and mortar. It is also used to make a variety of products including composite stone used to fabricate kitchen and bathroom benchtops, bricks, tiles and some plastics. When workers cut, crush, drill, polish, saw or grind products that contain silica, dust particles are generated that are small enough to lodge deep in the lungs and cause illness or disease including silicosis.
What is crystalline silica?
Silica is silicon dioxide, a naturally occurring and widely abundant mineral that forms the major component of most rocks and soils. There are non-crystalline and crystalline forms of silicon dioxide. The most common type of crystalline silica is quartz (CAS 14808-60-7).
What is silica dust?
Silica dust is generated in workplace mechanical processes such as crushing, cutting, drilling, grinding, sawing or polishing of natural stone or man-made products that contain silica. Some dust particles can be so small that they are not visible; these are commonly referred to as respirable particles.
Respirable silica dust particles are small enough to penetrate deep into the lungs and can cause irreversible lung damage.
The non-crystalline or amorphous forms of silica do not cause this kind of lung damage.
One method of reducing respirable silica is to clean the air before the levels are deemed unsafe
The workplace exposure standard
The workplace exposure standard for respirable crystalline silica that must not be exceeded is 0.1 mg/m3 (eight hour time weighted average).
PCBUs should keep worker exposures to respirable silica dust vacuum as low as reasonably practicable. Air monitoring will need to be conducted If there is any doubt that the exposure standard is being exceeded or to find out if there is a risk to a worker’s health.
This exposure standard has been reviewed as a priority by Safe Work Australia as part of the review of the workplace exposure standards. The draft evaluation report and recommendations for respirable crystalline silica is available for public comment via our consultation platform, Engage.
How many changes per hour should I aim for?
We recommended that there are at least 6 air changes per hour to maintain breathing air standards. Very high dust loading due to poor dust control at the machine or tool would have to be considered and greater changes per minute would be recommended in this case
Disclaimer: Always use a air monitor for measure the silica levels to ensure it does not rise to unsafe levels. Do not reply on sight or smell to determine if silica is present. Using an Air Scrubber will improve the air quality but is not a guarantee that the air is safe.
Based on this, The AS1000 machine is capable of 1000 m3/hour so we divide this by 6 changes which leaves us with a capacity to maintain a room with 166 cubic meters of space.
How do I calculate the volume of a room?
To work out the cubic meters of a room multiply the Length x Width x Height in meters. for example a room 10m x 5m x 2.4m = 125m3 well within the requirements of general recommendations.
Work activities that may represent a high risk exposure
Silica is one of the most abundant minerals found in the earth’s crust and is used in many products across a variety of industries and workplaces. Crystalline silica is most dangerous to health when dust is generated, becomes airborne and is then inhaled by a worker.
Examples of work activities that can generate respirable silica dust particles include:
- during fabrication and installation of composite (engineered or manufactured) stone countertops
- excavation, earth moving and drilling plant operations
- clay and stone processing machine operations paving and surfacing
- mining, quarrying and mineral ore treating processes
- tunnelling
- construction labouring activities
- brick, concrete or stone cutting; especially using dry methods
- abrasive blasting (blasting agent must not contain greater than 1 per cent of crystalline silica)
- foundry casting
- angle grinding, jack hammering and chiselling of concrete or masonry
- hydraulic fracturing of gas and oil wells
- pottery making.
Credits: Worksafe Australia