DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Summary

Construction workers may be 

exposed to hazardous dust containing crystalline silica during 

site preparation when drilling 

systems are used. The National 

Institute for Occupational Safety 

and Health (NIOSH) found that 

drill dust could be decreased by 

using wet or dry dust reduction 

engineering controls, enclosed 

cabs, and implementing a dust 

control program.

Reducing Hazardous Dust Exposure 

When Rock Drilling During Construction

Description of

Exposure

Breathing dust that contains crystalline silica can lead to silicosis, a deadly 

lung disease. No effective treatment 

exists for silicosis, but it can be prevented by controlling workers’ exposures to dust containing crystalline silica. Exposure to crystalline silica has 

also been linked to lung cancer, kidney disease, reduced lung function, 

and other disorders [NIOSH 2002]. 

Many tasks in construction may generate dust containing crystalline silica: 

grinding or cutting concrete, tuckpointing masonry, using a jackhammer to break concrete, or when using 

drilling systems during construction. 

Rock drilling before blasting for highway construction may generate a large 

amount of dust containing crystalline silica. Also, rock drilling for other reasons during construction such 

as site preparation, pipeline installation, or water well drilling may generate hazardous dust (see Figure 1). 

Acute and accelerated cases of silicosis have been reported in rock drillers [NIOSH 1992]. NIOSH [1996] 

noted that a drill operator working 

at a building site where no dust controls were used was exposed to 16 

times the NIOSH recommended exposure level (REL). 

NIOSH Studies and 

Controls

NIOSH has conducted studies in the 

construction and mining industries 

where rock drilling is done. Engineering controls and work practices identified in these studies help prevent 

Figure 1. Rock drilling without appropriate dust control.
silicosis by keeping dust containing crystalline silica out 

of the air workers may breathe (see Figure 2). NIOSH 

recommends that the same controls and work practices, 

described below, be used in construction activities where 

rock drilling may generate silica dust.

Under federal occupational safety and health regulations, 

employers have the responsibility for implementing engineering controls and administrative controls, providing 

personal protective equipment, and providing safety and 

health training for employees. 

Site set-up

 Develop a site-specific safety and health plan. The plan 

should include guidance for recognizing when silica dust 

may be generated and describe strategies to control or 

eliminate dust. Include engineering controls, personal 

protective equipment, and work practices.

 During rock drilling operations, use wet or dry control systems to control dust. Wet systems are efficient 

but may freeze in the winter. Caution is advised when 

using wet systems in the presence of electrical energy sources. When purchasing equipment, look for dust 

controls. Always use the dust control system and keep 

it well maintained. Do not use equipment if the dust 

control system is not working properly.

 Establish a documented maintenance program for the 

dust control systems mentioned below. Dry systems 

require careful maintenance of the drill deck shroud. 

When changing filters, the use of respirators by workers may be appropriate.

 Take safety precautions to minimize the presence of 

workers near rock drilling. Also, use warning signs and 

barriers to separate workers, pedestrians, and vehicles 

from rock drilling equipment.

 Provide training to rock drillers and assistants in the 

use of controls and work procedures.

 During rock drilling, perform air monitoring of respirable crystalline silica exposures to make sure engineering controls are working and to determine whether workers need respiratory protection.

Engineering Controls

 Wet drilling systems pump water through the drill 

stem to prevent dust from being released into the 

air. The drill operator controls the flow using a control valve. Some drills are equipped with a flow meter. 

Raising the water flow will improve dust capture, but 

too much water will cause operational problems [Organiscak et al. 2003]. 

Figure 2. Dry dust control system working correctly.
 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 negative pressure inside the enclosure capturing dust as it 

leaves the hole during drilling. The dust is removed in 

the collector [Organiscak et al. 2003]. 

 When feasible, use rock drilling equipment with 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.

Personal Hygiene, Protective 

Clothing, and Work Practices

 Wash hands and face before eating, drinking, or smoking. 

Do not eat, drink, or use tobacco products in the work 

area where construction activities are being performed.

 Change into disposable or washable work clothes at 

the worksite. If possible, shower and change into clean 

clothes before leaving the worksite to avoid contaminating cars, homes, and other work areas. If it is not 

possible to shower or change into clean clothes, use a 

vacuum with a high-efficiency filter to remove dust 

from clothes. An effective method to remove dust 

from clothing involves a booth under negative pressure that uses an air spray manifold to blow dust from 

clothing [Pollock et al. 2006]. Do not use a compressed air hose to remove dust from clothing.

 Park cars where they will not be contaminated with 

silica dust.

 Remove dust from equipment using a water hose rather 

than compressed air. 

Respiratory Protection

 Use respiratory protection when needed. The controls 

cited in this report may greatly reduce worker exposure to dust; however, respirators may still be necessary to reduce exposure to crystalline silica below the 

NIOSH REL of 50μg/m3

. 

 Follow the Occupational Safety and Health Administration (OSHA) Respiratory Protection Standard (29 CFR*

*Code of Federal Regulations. See CFR in References.

1910.134) www.osha.gov/SLTC/etools/respiratory/

index.html). The provisions of the program include 

procedures for selection, medical evaluation, fit testing, training, use and care of respirators. 

Acknowledgments

The principal contributors to this publication were John 

Organiscak, Andrew Cecala, and Steven Page of the 

Pittsburgh Research Laboratory, National Institute for 

Occupational Safety and Health. John Whalen under a 

contract with the U.S. Public Health Service, Division of 

Federal Occupational Health served as writer/editor. 

References

CFR. Code of Federal regulations. Washington, DC: U.S. 

Government Printing Office, Office of the Federal Register.

NIOSH [1992]. NIOSH Alert: Preventing silicosis and 

death in rock drillers. Cincinnati, OH: U.S. Department of Helath and Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 1992–107.

NIOSH [1996]. NIOSH Alert: Preventing silicosis and 

deaths in construction workers. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 1996–112. 

NIOSH [2002]. NIOSH Hazard Review: Health effects 

of occupational exposure to respirable crystalline silica. Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, DHHS (NIOSH) Publication No. 2002–129. 

Organiscak JA, Page SJ, Cecala AB, Kissell FN [2003]. 

Surface mine dust control. In: Kissell FN, ed. Handbook of Dust Control in Mining. Pittsburgh, PA: U.S. 

Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, Information Circular 9465, pp 73–82.

Pollock DE, Cecala AB, Zimmer JA, O’Brien AD, Howell JL [2006]. A new method to clean dust from soiled 

work clothes. In: Mutmansky JM, Ramani RV eds. Proceedings of the 11th U.S./North American Mine Ventilation Symposium (University Park, PA, June 5–7, 2006). 

London: Taylor & Francis Group, pp. 197–201.
DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

4676 Columbia Parkway

Cincinnati, OH 45226–1998

Official Business

Penalty for Private Use $300

For More Information

The information in this document is based on NIOSH field 

studies. More information about silica hazards and controls 

is available on the NIOSH Web site at http://www.cdc.gov/

niosh/topics/silica/default.html. 

To receive copies of the NIOSH field study reports that 

formed the basis of this document or to obtain information 

about other occupational safety and health topics, contact 

NIOSH at 

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348  E-mail: cdcinfo@cdc.gov

or visit the NIOSH Web site at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting http://www.cdc.gov/niosh/eNews.

Mention of any company or product does not constitute endorsement by NIOSH. In addition, citations to Web sites external to NIOSH do not constitute NIOSH endorsement of 

the sponsoring organizations or their programs or products. 

Furthermore, NIOSH is not responsible for the content of 

these Web sites.

This document is in the public domain and may be 

freely copied or reprinted. NIOSH encourages all 

readers of the Workplace Solutions to make them 

available to all interested employers and workers.

As part of the Centers for Disease Control and Prevention, 

NIOSH is the Federal agency responsible for conducting research and making recommendations to prevent work-related 

illness and injuries. All Workplace Solutions are based on research studies that show how worker exposures to hazardous 

agents or activities can be significantly reduced.

Reducing Hazardous Dust Exposure When Rock 

Drilling During Construction

DHHS (NIOSH) Publication No. 2009–124

safer • healthier • people April 2009 tm