Reducing Silica and Dust Exposures in Construction During Use of Powered Concrete-Cutting Hand Tools: Efficacy of Local Exhaust Ventilation on Hammer Drills

Abstract

Concrete cutting in construction is a major source of exposure to respirable crystalline silica. To reduce exposures, local exhaust ventilation (LEV) may be integrated into the hand tools used in concrete cutting. Volunteers from the New England Laborers Training Center participated in a field study focused on the use of LEV on concrete-cutting hammer drills. A randomized block design field experiment employing four workers measured the efficacy of four hood-vacuum source combinations compared with no LEV in reducing dust and silica exposures. Using four-stage personal cascade impactors (Marple 294) to measure dust exposure, a total of 18 personal samples were collected. Reductions of over 80% in all three biologically relevant size fractions of dust (inhalable, thoracic, and respirable) were obtained by using any combination of hood and vacuum source. This study found that respirable dust concentrations were reduced from 3.77 mg/m³ to a range of 0.242 to 0.370 mg/m³; thoracic dust concentrations from 12.5 mg/m³ to a range of 0.774 to 1.23 mg/m³; and inhalable dust concentration from 47.2 mg/m³ to a range of 2.13 to 6.09 mg/m³. Silica concentrations were reduced from 0.308 mg/m³ to a range of 0.006 to 0.028 mg/m³ in the respirable size fraction, from 0.821 mg/m³ to a range of 0.043 to 0.090 mg/m³ in the thoracic size fraction, and from 2.71 mg/m³ to a range of 0.124 to 0.403 mg/m³ in the inhalable size fraction. Reductions in dust concentrations while using the four LEV systems were not statistically significantly different from each other.

Keywords:

• construction
• local exhaust ventilation
• silica

ACKNOWLEDGMENTS

The authors thank the New England Laborers Training Academy who participated in the sampling, and the students and staff who assisted in data collection and analysis, including SangWooTak and Rebecca Gore. The authors are grateful to Pam Susi and Jim Platner from CPWR – The Center for Construction Research and Training for their assistance and support.

This study was supported by grants CCU317202 and 1U54OH008307 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.