CONTROL OF SILICA DUST IN CONSTRUCTION 

Crushing Machines

Using crushing machines at construction sites to reduce the size of large rocks, 

concrete, or construction rubble can generate respirable crystalline silica dust. 

When inhaled, the small particles of silica can irreversibly damage the lungs. This 

fact sheet describes dust controls that can be used to minimize the amount of 

airborne dust when using crushing machines as listed in Table 1 of the Respirable 

Crystalline Silica Standard for Construction 29 CFR 1926.1153. 

Engineering Control Method: Wet Methods AND Operator Isolation

The use of water sprays or mists for dust 

suppression at the points where dust is 

generated (e.g., hoppers, conveyers, sieves/

sizing or vibrating components, and discharge 

points) can control dust exposures when 

operating crushers. In addition, operator 

isolation through the use of a remote control 

station or ventilated booth that provides fresh, 

climate-controlled air to the operator must also 

be used to control exposure when operating 

crushers at construction sites.

Photo courtesy of Screen Machine Industries

Crushing machine being loaded with construction 

debris by an excavator.

Wet Methods

Wet spray methods can greatly reduce the silica 

exposure levels of operators and laborers who 

work near crushers, tending the equipment, 

removing jammed material from hoppers, 

picking debris out of the material stream, and 

performing other tasks.

The crusher must be operated and maintained in 

accordance with the manufacturer’s instructions to 

minimize dust emissions. Make sure to:

• Locate nozzles upstream of dust 

generation points.

• Position nozzles to thoroughly wet the 

material.

• Ensure the volume and size of droplets is 

adequate to sufficiently wet the material 

(optimal droplet size is between 10 and 150 μm).

• Ensure nozzles provide complete water 

coverage but are not so far that the water is 

carried away by wind.

Operator Isolation

Operator isolation for crushing machines 

includes using either an enclosed booth or a 

remote control station. Operators using crushing 

machines with enclosed cabs can limit their 

silica exposure by staying inside the cab during 

crushing operations. The enclosed cab must:

• Be well-sealed and well-ventilated using 

positive pressure.

• Have door jambs, window grooves, power-line 

entries and other joints that work properly and 

are tightly sealed.

• Have heating and air conditioning so that 

operators can keep windows and doors closed.

• Use an intake air filter with a minimum 

MERV-16 rating (at least 95 percent in the 

0.3-10.0 μm range).

FactSheet
• Be kept free from settled dust by regular 

cleaning and maintenance to prevent dust from 

become airborne inside the enclosed booth.

An alternative method for operator isolation is to 

use a remote control station located a sufficient 

distance upwind to limit exposure to silica 

containing dust. 

Respiratory Protection

When properly used, water sprays with either 

ventilated booths or remote control stations 

can in most cases effectively limit exposure to 

airborne dust. Therefore, Table 1 in the silica 

standard for construction does not require use 

of respiratory protection when using crushers 

at construction sites when the machines are 

equipped with water sprays along with either 

control booths or remote controls stations.

Additional Information

For more information, visit www.osha.gov/silica

and see the OSHA Fact Sheet on the Crystalline 

Silica Rule for Construction, and the Small Entity 

Compliance Guide for the Respirable Crystalline 

Silica Standard for Construction.

OSHA can provide compliance assistance 

through a variety of programs, including 

technical assistance about effective safety and 

health programs, workplace consultations, 

and training and education. OSHA’s On-Site 

Consultation Program offers free, confidential 

occupational safety and health services 

to small and medium-sized businesses in 

all states and several territories across the 

country, with priority given to high-hazard 

worksites. On-Site consultation services are 

separate from enforcement and do not result 

in penalties or citations. To locate the OSHA 

On-Site Consultation Program nearest you, 

visit www.osha.gov/consultation.

Workers’ Rights

Workers have the right to:

• Working conditions that do not pose a risk of 

serious harm.

• Receive information and training (in a 

language and vocabulary the worker 

understands) about workplace hazards, 

methods to prevent them, and the OSHA 

standards that apply to their workplace.

• Review records of work-related injuries and 

illnesses.

• File a complaint asking OSHA to inspect their 

workplace if they believe there is a serious 

hazard or that their employer is not following 

OSHA’s rules. OSHA will keep all identities 

confidential.

• Exercise their rights under the law without 

retaliation, including reporting an injury or 

raising health and safety concerns with their 

employer or OSHA. If a worker has been 

retaliated against for using their rights, they 

must file a complaint with OSHA as soon as 

possible, but no later than 30 days.

For additional information, see OSHA’s Workers 

page.

How to Contact OSHA

Under the Occupational Safety and Health Act 

of 1970, employers are responsible for providing 

safe and healthful workplaces for their employees. 

OSHA’s role is to ensure these conditions for 

America’s working men and women by setting 

and enforcing standards, and providing training, 

education and assistance. For more information, 

visit www.osha.gov or call OSHA at 1-800-321-

OSHA (6742), TTY 1-877-889-5627.

DSG FS-3935 12/2017

This is one in a series of informational fact sheets highlighting OSHA programs, policies or 

standards. It does not impose any new compliance requirements. For a comprehensive list of 

compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal 

Regulations. This information will be made available to sensory-impaired individuals upon request. 

The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.