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The Occupational Safety and Health Administration requires employers to limit workers’
exposure to respirable crystalline silica on the job.
This is one of a series of videos showing dust control methods that OSHA specifies for many common
construction tasks in Table 1 of the Respirable Crystalline Silica standard for construction.
When used properly, these methods are effective in limiting workers’ exposure to respirable crystalline silica dust.
This video describes how to fully and properly use a commercially available shroud or cowling
and a dust collection system to control dust when using handheld or stand-mounted drills to create
holes in material containing crystalline silica.
Frequently, handheld drills use a rotary or percussion hammering action
to efficiently drill into masonry material, as shown in this video.
The controls shown in this video also apply when handheld drills are mounted in stands.
Using the drill with a commercially available shroud or cowling with a dust collection system
can control the dust created by drilling into materials containing crystalline silica.
Commercially produced shrouds and cowlings with dust collection systems
are readily available for use with handheld and stand-mounted drills.
To comply with Table 1, the dust collector must provide the air flow recommended by the tool manufacturer
and have a filter with 99 percent or greater efficiency along with a filter-cleaning mechanism.
Shrouds or cowlings surround the drill bit and attach to the vacuum dust collection system with a hose.
It’s important to correctly operate and maintain the dust collection system.
When the dust collection system is not working properly, dust is not effectively controlled.
With regular use, the shroud or cowling can become excessively worn,
vacuum hoses can become clogged,
filters can become overloaded,
and dust collection bags will fill up.
To help ensure the system is working correctly, the shroud or cowling must be intact and installed
according to the manufacturer’s instructions.
The drill must also be operated and maintained
in accordance with the manufacturer’s instructions to minimize dust emissions.
Instructions often specify the following:
The appropriate types of drill bits to use;
The recommended minimum air flow;
The maximum length of hose;
Procedures for checking equipment for wear or damage;
Reminders to make sure the hose connecting the tool to the vacuum is intact
and without kinks or tight bends that can reduce air flow and dust collection;
The procedure for emptying the waste container;
and a maintenance schedule.
Be sure used filters and dust collection bags are handled in a manner that will
minimize workers’ exposure to silica dust.
When cleaning dust and debris from drilled holes, workers must use a HEPA-filtered vacuum.
As long as the specified controls are fully and properly implemented with a shroud or cowling,
the drill operator, and workers who are assisting the drill operator, are not required to wear respirators.
Using a handheld or stand-mounted drill indoors or in an enclosed area
requires an exhaust method, such as a portable fan, as needed to minimize the accumulation of visible airborne dust.
Be sure that any exhaust method chosen moves airborne dust away from workers and does not to block an exit route.
Employers who fully and properly implement the dust control method specified by OSHA in Table 1
are not required to measure the tool operator’s exposure to respirable crystalline silica,
or the exposure of other workers assisting with the task.
The respirable crystalline silica standard for construction also includes additional requirements to protect
workers exposed to respirable crystalline silica.
Many of these requirements apply whether employers are using a dust control method
specified by OSHA in Table 1, or an alternative dust control method.
More information on the standard’s requirements to protect workers exposed to respirable crystalline silica,
including information on specified exposure control methods for other common construction tasks,
can be found at www(dot)osha(dot)gov(slash)silica.
For information about other OSHA health and safety standards,
see www(dot)osha(dot)gov or call OSHA at 1-800-321-OSHA.
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