Controlling Dust from Concrete Saw Cutting

Abstract

Cutting concrete with gas-powered saws is ubiquitous in the construction industry and a source of exposure to respirable crystalline silica. Volunteers from the New England Laborers Training Center were recruited to participate in a field experiment examining dust reductions through the use of water, from a hose and from a sprayer, as a dust control. In four series of tests, reinforced concrete pipe was cut under both “dry” and “wet” control conditions. Overall, the geometric mean respirable dust concentration for “dry” cutting (14.396 mg/m³) exceeded both types of water-based controls by more than tenfold. Wet cutting reduced the respirable dust concentration by 85% compared with dry cutting when comparing tests paired by person and saw blade (n = 79 pairs). Using a respirable cyclone, a total of 178 samples were taken. Due to the high variability in dust exposure found in this and other studies of saw cutting, the data were examined for potential exposure determinants that contribute to that variability. Using mixed models, three fixed effects were statistically significant: control condition, worker experience, and location. A random effect for subject was included in the model to account for repeated measures. When each of the significant fixed effects was included with the random effect, it was apparent that inclusion of worker experience or location reduced the between-worker component of exposure variability, while inclusion of control condition (wet vs. dry) explained a large portion of the within-subject variability. Overall, the fixed effect variable for control condition explained the largest fraction of the total exposure variability.

Keywords:

• construction
• dust control
• mixed model
• silica

ACKNOWLEDGMENTS

The authors thank the New England Laborers Training Center staff, apprentices, and journeymen who participated in the sampling, and the staff and students who assisted in the data collection and analysis, particularly our statistician, Dr. Rebecca Gore. The authors are also grateful to Jim Platner of CPWR—The Center for Construction Research and Training—for his assistance and support in this work.

This study was supported by grants 1U54OH008307 and U60-OH009762 from the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention in cooperation with CPWR. The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of NIOSH.