Engineering Controls for Silica in Construction

Construction workers are potentially exposed to hazardous dust containing respirable crystalline silica (RCS) when using jackhammers to break concrete pavement. NIOSH found that such exposures could be reduced by using a water-spray attachment. This low-flow, water-spray control suppressed and reduced dust exposures by 70%–90%.^[2]

The following video shows a worker breaking concrete with a jackhammer without any dust controls. The bar on the right shows the worker’s respirable dust exposure, which is elevated. The units are milligrams of dust per cubic meter of air.

Jackhammer without Engineering Controls
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NIOSH is not aware at this time of off-the-shelf, commercially available retrofit kits or jackhammers that come with built-in water-spray units. However, it is relatively simple to build a water-spray control for a jackhammer using the diagram below and the parts and instructions in the following document ( pdf ). Plans for a simplified version are also available from a NIOSH partner.

Figure 1. Diagram of water-spray control used in NIOSH study.

The spray angle (the angle included between the sides of the cone formed by the water discharged by the nozzle) and the spray pattern are two critical design parameters required to match the performance of the tested device. The device tested used a solid-cone nozzle with an 80-degree spray angle. The third critical design parameter is the water flow rate. This spray used 350 milliliters (11.8 ounces) of water per minute for dust control. Higher water flow rates may not greatly improve dust control. Lower flow rates may not be as effective.

This following video shows the same worker using a jackhammer with a water spray control attached. The bar on the right shows that the worker’s respirable dust exposure is much lower when the water spray is used.

Jackhammer with Engineering Controls
To download, right click below
(rm 85 bytes)

For more information about dust controls for jackhammering see:

1. Brouwer DH, Spee T, Huijbers RF, Lurvink MWM, Fritjers ACP (2004). Effectiveness of dust control by atomisation of water sprays on handheld demolition and soil compacting equipment. Tijdschrift voor toegepaste Arbowetenschap 4:68-74.

2. Echt A, Seiber K, Jones E, Schill D, Lefkowitz, Sugar J, Hoffner K [2003]. Control of respirable dust and crystalline silica from breaking concrete with a jackhammer. Appl Occup Environ Hyg 18:491–495.

3. Echt A, Sieber K, Williams D, Cantrell A, Schill DP, Lefkowitz D, Sugar J, Hoffner K, NJ silica partnership (2004). In-depth survey report of a water spray device for suppressing respirable and crystalline silica dust from jackhammers at E.E. Cruz Company,South Plainfield, NJ, Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Report No. EPHB 282-11c-2.

4. Scharf A (1967). Preliminary report on reduction of airborne dust produced by pneumatic jackhammers. Am Ind Hyg Assoc J. 28:479-481.

5. Scharf A (1969). Control of airborne dust produced by pneumatic jackpicks. II. Am Ind Hyg Assoc J. 30:519-22.

6. Scharf A (1973). Control of airborne dust produced by pneumatic jackpicks with water attachments: report 3. Am Ind Hyg Assoc J. 34:48-53.

7. Scharf A (1973). Control of airborne dust produced by pneumatic jackpicks. Report IV. Calibration of water attachments. Am Ind Hyg Assoc J. 34:171-5.

8. Scharf A (1974). Airborne dust produced by pneumatic jackpick. V. Visible dust-steam clouds and concentrations. Am Ind Hyg Assoc J. 35:433-7.

9. Zalk D (2000). Exposure assessment strategy for the reduction of airborne silica during jackhammering activities. Orlando, FL: Presentation at AIHCE 2000.

Concrete Grinders

Cut-off Saws