Solution Summary: Add-on Wet Dust Suppression Systems for Jackhammers
Breaking concrete with jackhammers, also known as pavement breakers, generates a large amount of dust which may contain high levels of crystalline silica and creates a hazard for everyone in the vicinity. Water spray controls to reduce airborne dust and silica during jackhammering are not commercially available at this time but can be constructed from readily available parts. These controls consist of a water tank and pump, an electrical power supply, a water hose to the jackhammer, and a spray nozzle mounted on the jackhammer.
The New Jersey Laborers’ Health and Safety Fund provides a parts list with suppliers, costs and instructions for constructing a water spray dust control for less than $400. The water spray control uses a 12 volt direct current (DC) pump attached to a 26 gallon (98.4 liter) water tank to supply water to the spray nozzle through a 3/8-inch hose. The instructions indicate that the tank can be mounted to the hand truck specified in the parts list, a truck or trailer. Each minute approximately 11.8 ounces (350 milliliters) of water passes through the nozzle, which is mounted to the body of the jackhammer and aimed at the bit. Field tests have shown that the 300 amp, 12 volt power supply will power the pump for an entire shift.
Silica dust exposure may cause silicosis or lung scarring with prolonged exposure. Silicosis is an incurable, sometimes fatal, disease. The NIOSH Recommended Exposure Limit (REL) is 0.05 mg/m3 as time-weighted average concentration for up to a 10-hour workday during a 40-hour workweek. Silica has also been associated with lung cancer.
How Risks are Reduced:
The water spray nozzle is located on the body of the jackhammer and aimed toward the bit, the site of dust generation. When dust and silica particles are sprayed with water mist they combine and, due to their increased weight, settle to the ground. These systems control dust and silica near the source, reducing concentrations in the worker's breathing zone and his or her exposure.
The NIOSH Workplace Solution titled Water Spray Control of Hazardous Dust When Breaking Concrete with a Jackhammer, summarizes study findings previously documented in a NIOSH in-depth survey report and a peer reviewed journal article. This Workplace Solution indicates that a similar “low-flow, water-spray control reduced dust exposures by 70%–90%” and “the results of the NIOSH study showed that the control devices may reduce exposure to dust for jackhammer operators and other workers near the work area.” While silica exposures during use of the water spray control were below the OSHA Permissible Exposure Limit (PEL) and reduced significantly compared to no dust control, they still approached or exceeded NIOSH Recommended Exposure Limits (RELs) and ACGIH Threshold Limit Values (TLVs). In spite of of significant reductions in silica exposure while using water spray controls, a respirator may still be necessary to reduce silica exposures to less than the REL and TLV when breaking concrete with a jackhammer.
Effects on Productivity:
Water spray dust control systems can have either positive or negative effects on productivity. Wet dust suppression systems reduce the amount of dust produced and eliminate large amounts of airborne dust, consequently, they provide a cleaner, more efficient means of breaking concrete.
Improved visibility can improve quality and productivity. Dust suppression may reduce work site and worker cleanup times. Dust suppression avoids exposing other workers, members of the public, adjacent property, cars and building occupants, which can be associated with increased liability or time consuming disputes. Improved worker comfort is a result of reduced airborne dust which may in turn result in less fatigue for the worker and greater productivity. In some cases, particularly where jackhammer use is intermittent, using a water spray dust control may be adequate to reduce the need to wear a respirator, and the need for an employer respiratory protection program.
Jackhammers frequently generate sound levels that are greater than 90 decibels, the OSHA Permissible Exposure Limit (PEL), and hazardous. Hearing protection must be worn when using jackhammers unless an industrial hygienist has conducted noise monitoring and indicated that hearing protection is not required.
As is the case with any construction equipment, users should follow manufacturer safety recommendations and comply with any applicable local, state or federal regulations. Many cities have ordinances that restrict work practices that generate visible dust as a public nuisance. This may assist compliance with such ordinances.
How to Make Your Very Own Jackhammer Spray Dust Control
While not commercially available, instructions for constructing a water dust control for use with a jackhammer are found in the document titled How to Make Your Very Own Jackhammer Spray Dust Control by Ken Hoffner, CIH, CSP - NJ Laborers’ Health and Safety Fund http://www.njlaborers.org/sites/all/themes/liuna/files/jackhammer.pdf