Completed Research

Evaluation of the Efficacy and Effectiveness of Silica and Noise Controls on Concrete-Cutting Tools (Completed – 2004-2009)

Dr. Woskie and research partner Susan Shepherd, ScD, worked with the Laborers Union and its New England Laborers Training Academy to evaluate ways to reduce silica and noise exposures when cutting reinforced concrete pipe with a gas-powered chop saw.

For the noise study, the researchers wanted to determine whether the blade design affected noise levels during gas saw operations. In tests with five different blades, the team found no difference in decibel levels during saw operation, and concluded that the saw’s very noisy two-stroke motor was the main noise source. The testing revealed that noise exposure differences among saw operators depended mainly on how fast the saw was running during the cutting. The researchers are currently studying how work practices can reduce noise exposures from these very noisy tools.

For silica dust control, the team found that using water is more effective than built-in dust control systems. The tests showed that using water during concrete cutting reduces respirable dust exposure by an average of 87 percent, but there was no statistical difference in dust concentrations for different water flow rates. The researchers are working on recommendations for using water spray pumps to achieve optimal dust control. By contrast, the dust exhaust systems did not reduce dust levels as effectively as wetting. Tests on one gas saw with a built-in dust exhaust system yielded average respirable dust levels that were about twice as high as the levels found during wetting.

The team also gathered information and insights from laborers and carpenters on jobsite activities and exposures, including silica, noise, organic solvents, and welding fumes. Researchers can use the data to link potential hazards with various tools and construction tasks.

A case study examining the incentives and barriers to the use of dust controls by a concrete contractor on a large building project was also completed and is in the publication process.

Original Project Abstract:

Although significant silica and noise exposures have been documented in construction in general, and concrete finishing and demolition in particular, few controls are evidence on typical construction sites. Reduction or elimination of exposures to silica and noise in construction requires the availability of controls that are technically proven in a controlled evaluation and regularly utilized. The objective of this project is to evaluate the efficacy of specific silica and noise controls in the controlled environment of a union apprenticeship-training center. The most efficacious controls will then be introduced into worksites where the barriers encountered during their implementation and ongoing use is examined.

This study proposes to evaluate the efficacy of a range of dust and noise controls used on small powered tools including portable concrete (chop) saws, walk behind concrete saws and jackhammers as well as heavy equipment such as pneumatic hammers (hoe-rams), pulverizers and rock crushers. The technical ability (efficacy) of silica and noise controls to reduce exposures will be measured under controlled conditions at the Operating Engineers and Laborers Training Centers . Case studies of implementation will collect qualitative and quantitative data on barriers to acceptance and continued use of these technical controls in a variety of construction settings.