851 Silica Dust Safety in Construction

Dry Control Methods

Stationary masonry and hand-held saws with VDC systems are commercially available and have the ability to capture a substantial amount of dust.

With these systems, a vacuum pulls dust from the cutting point through special fittings connected directly to the saw (fixed-blade saws) or, alternatively, through a dust collection device connected to the back of the saw. A dust collector mounted to the back of a saw requires a high exhaust airflow to ensure good dust capture between the saw blade and dust collector.

Drilling: Dry collection systems require an enclosure around the area where the drill stem enters the ground. The enclosure is made by hanging a rubber or cloth shroud from the underside of the drill deck. The enclosure is ducted to a dust collector that has a fan outside of the filter opposite the drill hole. The fan creates a negative pressure inside the enclosure capturing dust as it leaves the hole during drilling.

Rock drilling equipment should use enclosed positive-pressure cabs with air conditioning and filtered air supply to isolate the operator from the dust. Older cabs can be retrofitted with systems that filter, heat, and cool the air.

Grinding: Vacuum dust collection systems for grinders include a shroud, which surrounds the grinding wheel, hose, filters and a vacuum to pull air through the shroud. Many manufacturers offer grinders with dust collection options. Employers may also purchase equipment to retrofit grinders for vacuum dust collection.

Hammering: Vacuum dust collection systems are the primary way to control dust when using rotary hammers. The drill bit is surrounded by a shroud attached to a vacuum to collect dust and bits of concrete. VDCSs are available in a variety of designs and should include a dust collection device (shroud), vacuum, hose and filter(s).

Blasting: Crystalline silica, in the form of finely ground quartz sand as an abrasive blasting agent, is used to remove surface coatings prior to repainting or treating, a process that typically generates extremely high levels of airborne respirable crystalline silica. To minimize exposure during dry abrasive sand blasting, dust collection systems can be installed on the equipment. Also, the workspace may be enclosed, or ventilation hoods may be used.

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