WORKPLACE SOLUTIONS

From the National Institute for Occupational Safety and Health

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 silica when working in 

enclosed cabs during construction activities. The National Institute for Occupational Safety and Health (NIOSH) found 

that equipment operator exposure could be reduced by retrofitting air pressurization and filtration systems on existing cabs, 

using sweeping compounds on 

soiled floors, and implementing 

a dust control program.

Reducing Hazardous Dust in Enclosed 

Operator Cabs 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’ exposure 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 using mobile excavation equipment (e.g., drills, loaders, graders, dozers, and trucks). Operator cabs used in the construction 

industry are meant to protect the 

equipment operator from excessive 

dust and noise. When the equipment 

is new, the controls on the cab are 

normally able to reduce dust exposures to an acceptable level (see Figure 1). However, as the equipment 

ages, many components of the control systems deteriorate (e.g., seals) 

and may cause the operator to be exposed to hazardous levels of dust. A 

study on an older enclosed cab used 

at surface coal mine noted respirable 

dust in the cab almost 13 times the 

NIOSH recommended exposure level (REL) [Cecala et al. 2004].

NIOSH Studies

NIOSH has conducted studies of mining in the United States in cooperation with the Mine Safety and Health 

Administration (MSHA), mine operators, and equipment manufacturers 

to find the most cost-effective ways 

to reduce operator exposure to dust 

in enclosed cabs [NIOSH 2008]. Engineering controls and work practices identified in these studies relate 

directly to mobile excavation equipment used in the construction industry. Therefore, NIOSH recommends 

that the same controls and work 

practices be used in mobile equipment for heavy construction. 

Figure 1. Cab filtration and pressurization systems prevent dust from 

penetrating cabs.
The main sources of dust in an enclosed cab are from airborne dust at the worksite that leaks into a cab that is poorly sealed and from the material tracked into the cab by the 

operator. The two most important factors to achieve low 

dust concentrations in enclosed cabs were the use of an efficient air filtration system and an effectively sealed (tight) 

cab for positive inside cab pressurization.

Controls

NIOSH and its partners have developed recommendations to help protect workers from exposure to crystalline silica dust during construction activities [Cecala et al. 

2001; Cecala et al. 2005; NIOSH 1996; NIOSH 2001; 

NIOSH 2002]. The following guidelines for controlling 

hazardous dust when using enclosed cabs during construction activities are based on those recommendations.

Site Set-Up 

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

should recognize when silica dust may be generated 

and plan ahead to control or eliminate dust. Include 

engineering controls, personal protective equipment, 

and work practices.

 Establish a documented maintenance program. Ensure 

that holes and cracks in the body of the cab are patched 

and door seals and gaskets are replaced as needed. If 

an electrostatic filter is used on the filtering system, 

change it on a regular basis as recommended by the filter manufacturer. 

 Apply a gritless (i.e., without sand) natural-base 

sweeping compound on smooth enclosed cab floors to 

help bind up the dirt and soil tracked into the cab. The 

sweeping compound should be a natural-based type 

compound to reduce any operator irritation or allergic 

reaction to odors from petroleum-based oils and wax 

compounds. Before using any sweeping compound, review its Material Safety Data Sheet (MSDS) for hazardous ingredients and precautions.

 Provide training to enclosed cab operators in the use of 

controls and work procedures.

 During the use of the excavation equipment, perform 

periodic air monitoring of respirable crystalline silica 

exposures to make sure the engineering controls are 

working and to determine whether workers need respiratory protection.

 Minimize the number of workers on foot near mobile excavation equipment. Use barriers to separate 

workers, pedestrians, and vehicles from mobile excavation equipment. Ensure that mobile equipment 

is not operated on grades steeper than those specified 

by the equipment manufacturer.

Engineering Controls

 During construction activities, use water to reduce the 

amount of airborne dust generated or use a dust collection system if possible. 

 Use mobile 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 heat, cool, and filter 

the air (see Figure 2).

 Do not position heaters or air-conditioning vents on 

the floor. If needed, they should be positioned in a 

high area of the cab where they are less likely to pick 

up dust from the floor or operator’s clothing. It is best 

to configure a heating and air-conditioning unit into the 

clean air and pressurization system. 

 Use an efficient air filtration system (high-efficiency intake and recirculation filters) to capture dust that is generated by the operator or other sources inside the cab.

Personal Hygiene and Protective 

Clothing

 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 

Figure 2. Installation of a uni-directional cab filtration 

and pressurization system. The uni-directional system 

delivers all of the filtered air into the enclosed cab at the 

roof and pulls all the recirculated air from the cab floor 

into the main filtering unit to be re-cleaned.
clothes before leaving the worksite. 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.

 Park cars where they will not be contaminated with silica dust.

 Keep the cab doors and windows closed to keep the 

cab pressurized. The operator should remain in the enclosed cab whenever possible. 

 An operator’s clothing and boots should be kept as 

clean as possible.

 Do not remove dust from the enclosed cab by blowing with compressed air. Also, do not blow dust from 

clothing or skin with compressed air since this can resuspend the dust into a worker’s breathing area. 

 Practice good housekeeping. Equipment operators 

should clean the floors and walls on a periodic basis.

 If a sweeping compound is not used to clean the 

cab, do not use dry methods such as sweeping. Use 

a vacuum equipped with a high-efficiency filter or, 

if they do not create electrical or safety hazards, 

use wet methods to clean the cab.

Respiratory Protection

The dust control cited in this report may greatly reduce 

worker exposure to hazardous 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*

 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 Andrew Cecala and John Organiscak 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. 

*Code of Federal Regulations. See CFR in References

References

Cecala AB, Organiscak JA, Heitbrink WA [2001]. Dust 

underfoot: enclosed cab floor heaters can significantly increase operator’s respirable dust exposure. Rock 

Products 104(4):39–44.

Cecala AB, Organiscak JA, Heitbrink WA, Zimmer JA, 

Fisher T, Gresh RE, Ashley JD [2004]. Reducing enclosed cab drill operator’s respirable dust exposure at 

surface coal operation with a retrofitted filtration and 

pressurization system. SME Transactions 2003, Vol. 

314, Littleton, CO: Society for Mining, Metallurgy, 

and Exploration, pp. 31–36. 

Cecala AB, Organiscak JA, Zimmer JA, Heitbrink WA, 

Moyer ES, Schmitz M, Ahrenholtz E, Coppock CC, 

Andrews EH [2005]. Reducing enclosed cab drill oper- Reducing enclosed cab drill operator’s respirable dust exposure with effective filtration 

and pressurization techniques. J Occup Environ Hyg 

2(1):54–63.

CFR. Code of Federal requlations. Washington, DC: 

U.S. Government Printing Office, Office of the Federal Register.

NIOSH [1996]: NIOSH Alert: Preventing silicois 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. 96–112.

NIOSH [2001]. Sweeping compound application reduces dust from soiled floors within enclosed operator 

cabs. Pittsburgh, PA: U.S. Department of Health and 

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

Health, Technology News 487(1–2).

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. 

NIOSH [2008]. Improvements in mobile equipment 

cabs to reduce dust exposure. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute 

for Occupational Safety and Health (NIOSH) [www.

cdc.gov/niosh/nas/mining/intermediateoutcome6.

htm].
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

safer • healthier • peopletm April 2009

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 website at 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 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 Dust in Enclosed Operator Cabs During 

Construction

DHHS (NIOSH) Publication No. 2009–123