Effective dust control systems on concrete dowel drilling machinery

ABSTRACT

Rotary-type percussion dowel drilling machines, which drill horizontal holes in concrete pavement, have been documented to produce respirable crystalline silica concentrations above recommended exposure criteria. This places operators at potential risk for developing health effects from exposure. United States manufacturers of these machines offer optional dust control systems. The effectiveness of the dust control systems to reduce respirable dust concentrations on two types of drilling machines was evaluated under controlled conditions with the machines operating inside large tent structures in an effort to eliminate secondary exposure sources not related to the dowel-drilling operation. Area air samples were collected at breathing zone height at three locations around each machine. Through equal numbers of sampling rounds with the control systems randomly selected to be on or off, the control systems were found to significantly reduce respirable dust concentrations from a geometric mean of 54 mg per cubic meter to 3.0 mg per cubic meter on one machine and 57 mg per cubic meter to 5.3 mg per cubic meter on the other machine. This research shows that the dust control systems can dramatically reduce respirable dust concentrations by over 90% under controlled conditions. However, these systems need to be evaluated under actual work conditions to determine their effectiveness in reducing worker exposures to crystalline silica below hazardous levels.

KEYWORDS:

• Concrete dowel drilling
• crystalline silica
• dust control systems
• respirable dust

Acknowledgments

The authors thank Ellen Galloway for her editorial assistance. The authors also thank Max Kiefer, NIOSH Western States Office, and Taekhee Lee, NIOSH Health Effects Laboratory Division, for their reviews of the manuscript. The authors appreciate the cooperation and assistance we received from Minnich Manufacturing, Inc. and E.Z. Drill, Inc. in carrying out this work.

Funding

This work was supported by a National Institute for Occupational Safety and Health project, Engineering control partnership for dowel-pin drills (CAN# 0927ZJHK). DISCLAIMER: The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Mention of product or company name does not constitute endorsement by the Centers for Disease Control and Prevention or NIOSH.