DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Summary

Construction workers are exposed to hazardous dust when 

grinding or cutting mortar or cement from between the bricks of 

old buildings. The National Institute for Occupational Safety and 

Health (NIOSH) found that exposures could be reduced using 

tool-mounted local exhaust ventilation and work practices.

Figure 1. Uncontrolled mortar removal generating hazardous exposure to dust.

Control of Hazardous Dust During 

Tuckpointing

Description of

Exposure

Workers who use grinders to remove 

deteriorated mortar between bricks 

(tuckpointing) may be exposed to 

crystalline silica at concentrations 

up to 100 times the NIOSH recommended exposure limit (REL) of 

50 μg/m3

 [Shields 1999]. Breathing 

dust that contains silica can lead to 

the development of silicosis, a deadly lung disease. In addition, exposure 

to crystalline silica has been linked to 

lung cancer, kidney disease, reduced 

lung function, and other disorders 

[NIOSH 2002]. No effective treatment exists for silicosis, but it can 

be prevented by controlling workers’ 

exposure to dust containing crystalline silica. 

As brick buildings get older, the mortar between the bricks starts to fall 

apart and needs to be replaced to prevent water intrusion into the building. Before replacing the mortar, 1⁄2 

to 3⁄4 inch of the old mortar is removed by using a grinder. The grinder breaks up the mortar and turns it 

into airborne dust that may contain 

crystalline silica. The crystalline silica dust released during tuckpointing operations is very hard to control 

(Figure 1). The dust may be carried 

throughout the workplace. When 

workers use compressed air to clean 

their clothes, tools, and equipment, 

even more dust is added to the air.

Controls

NIOSH has identified control measures to reduce worker exposure to 

hazardous dust during tuckpointing. 

Studies [Heitbrink and Collingwood 

2005; Collingwood and Heitbrink 

2007] show how an industrial vacuum 
Figure 2. Keep the tool flat and positioned so that the 

dust from grinding is blown into the exhaust hose.

cleaner attached via a flexible hose to a shroud that partially encloses the grinding disk can reduce silica dust by 

5 to 20 times during tuckpointing when compared with 

studies in which no dust controls were used.

Additional studies are needed to improve the design 

and effectiveness of this control. However, the interim guidelines below can be used to reduce exposure to 

workers who are tuckpointing and others near the work 

area. In addition, equipment maintenance and worker 

training should be part of a comprehensive silica control 

program. 

Vacuum Cleaners

The choice of a vacuum cleaner depends on the task. 

The vacuum cleaner should draw at least 10 amps if it 

is to be used as part of a ventilated grinder system. Although a minimum air-flow rate of about 65 cubic feet 

per minute (cfm) provides adequate air flow, the objective is to provide an air flow of 80 cfm to achieve effective dust control. A vacuum cleaner with a cyclonic preseparator (cyclone) should be used to keep debris 

off the final filters. This will enable the vacuum cleaner to maintain an adequate airflow, which will facilitate dust capture and transport [Heitbrink and Bennett 

2006]. Thus, it is very important to monitor the airflow rate. A vacuum cleaner equipped with a pressure 

gauge allows the worker to determine whether the airflow rate is too low to be effective. If the vacuum cleaner does not have a pressure gauge, workers can monitor 

the air flow by checking to see if a dust plume is escaping from around the shroud. The final filter should be 

a high-efficiency particulate air (HEPA) filter to reduce 

the chance of releasing dust containing crystalline silica 

from the vacuum into the worksite.

Hose

A 2-inch diameter hose with a smooth interior and a 

length of no more than 15 feet provides adequate air 

flow to capture and transport the mortar dust. The air 

flow provided by smaller diameter hoses (e.g., 1.5 inch) 

was far less than that provided by 2-inch diameter hoses. The hose should have as few elbows or turns as possible.

Shroud and Grinder

The exhaust shroud can be purchased separately or as 

a unit with the vacuum cleaner and hose. The shroud 

should totally enclose the spaces around the exhaust entry point for the hose. The shroud should have an entry 

point for the hose of 2 inches to match the diameter 

of the hose. Some tuckpointing grinders come with an 

attached shroud (e.g., Dust Director, Bosch Tuckpoint 

Grinder Model 1775E).

Work Practices

 Keep the exhaust entry point flat against the surface 

(Figure 2). 

 Shake the hose as needed to loosen the settled dust 

and prevent the hose from clogging.

 Make sure no dust is escaping from the shroud.

— If dust is escaping, turn off the unit and clean or 

change the filter as recommended by the manufacturer.

— Try to dislodge the build-up on the filter by moving or shaking the vacum cleaner, or turning the 

motor off and on a few times. Build-up on the 

filters slows down the air flow through the system and reduces dust capture.

— Use a cyclonic pre-separator to keep the filter 

clean. 

 Work against the rotation of the blade. The tool must 

be flat and positioned so that the dust from grinding is 

blown into the exhaust hose (Figure 3).

 Change vacuum cleaner bags before they leak, break, 

or cause too much resistance to air flow. Use appropriate personal protective equipment (PPE) such as a respirator when changing vacuum cleaner bags or filters.

 Put the vacuum cleaner below the work level to keep 

dust from falling out of the hose.
Figure 3. Diagram of mortar removal.

Respirators

When tuckpointing in poorly ventilated areas such as 

in corners or inside buildings, workers and employers 

should be aware that there is an increased risk of exposure to high concentrations of hazardous dust. Also, 

there is the potential for increased exposure to hazardous dust when tuckpointing on surfaces that are in poor 

condition. 

The dust control cited in this report may greatly reduce 

worker exposure to hazardous dust; however, respirators 

are still necessary to reduce exposure to crystalline silica 

below the NIOSH REL of 50μg/m3

. It may be possible 

to use less restrictive respirators since the amount of hazardous dust has been decreased by the control. Exposure 

monitoring is necessary to determine what type of respirator is needed. Employers should follow the Occupational Safety and Health Administration (OSHA) Respiratory Protection Standard (29 CFR 1910.134) (www.osha.

gov/SLTC/etools/respiratory/index.html).

Equipment Manufacturers

Equipment manufacturers should consider the recommendations in this report when developing new grinders or controls.

Acknowledgments

The principal contributors to this publication were William 

Heitbrink of the University of Iowa and Scott Collingwood 

from the University of Utah. John Whalen, under a contract with the U.S. Public Health Service, Division of 

Federal Occupational Health, served as lead writer/

editor. 

References

Collingwood S, Heitbrink WA [2007]. Field evaluation 

of an engineering control for respirable crystalline silica exposures during mortar removal. J Occup Environ 

Hyg 4:875–887.

Heitbrink WA, Bennett J [2006]. A numerical and experimental investigation of crystalline silica exposure control 

during tuck pointing. J Occup Environ Hyg 3:366–378.

Heitbrink WA, Collingwood S [2005]. Protecting tuckpointing workers from silica dust: draft recommendations for a ventilated grinder. Silver Spring, MD: The 

Center to Protect Workers’ Rights. Available at: www.

cdc.gov/elcosh/docs/d0600/d000683/d000683.html]. 

NIOSH [2002]. NIOSH hazard review: health effects 

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

Human Services, Public Health Service, Centers for 

Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 2002–129.

Shields C [1999]. Massive respirable silica exposures in 

tuck pointing (power grinding). Presented at the 1999 

American Industrial Hygiene Conference and Exposition, Toronto, Ontario, Canada. Roundtable 246. 
For More Information

For a monthly update on news at NIOSH, subscribe to 

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

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.

Control of Hazardous Dust During Tuckpointing

DHHS (NIOSH) Publication No. 2008—126

(Supersedes 2000–113)

NIOSH has previously published recommendations to help 

protect workers from exposure to crystalline silica dust during construction activities.

NIOSH [1996]. NIOSH Alert: request for assistance in preventing silicosis and deaths in construction workers. Cincinnati, OH: U.S. Department of Health and Human Services, 

Public Health Service, Centers for Disease Control and Prevention, DHHS (NIOSH) Publication No. 96–112.

Additional information about silica hazards and controls is 

available on the NIOSH Web site at www.cdc.gov/niosh/

topics/silica/default.html. 

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

Safer • Healthier • PeopleTM September 2008

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

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Cincinnati, OH 45226–1998

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