Evaluation of dust control technologies in construction tasks.
Seixas-NS; Camp-J; Flanagan-ME; Croteau-GA
NIOSH 2003 Feb; :1-34
Significantly elevated exposures to silica dust have been widely documented in construction activities, especially concrete cutting and grinding. Although application of water streams or spays to the cutting surface can substantially control exposures, many construction situations make the use of water infeasible. In order to evaluate the effectiveness of local exhaust ventilation (LEV) as an alternative approach to silica dust control in constructions, a series of three studies were done The study proceeded by first testing the effectiveness of LEV controls on four different types of tools in an experimental setting, then characterizing exposures occurring in eight common masonry activities in the field, and finally, considering the effectiveness of LEV on surface grinders used in field conditions. In each study, measurements were made with and without the use of LEV, and personal respirable dust and silica exposures were measured during the activity. Measurements were obtained with an inline respirable dust cyclone and filter, and with a direct reading instrument (pDR) allowing for the quantification of peak levels, and adjustment of the data for task-specific time periods. Very high silica concentrations were observed in field conditions. The overall geometric mean (GM) quartz concentration was 0.10 mg/m3 (GSD=4.88) for all samples, with 71 % exceeding the TLV. Activities with the highest (GM +/- GSD) exposures were surface grinding (0.63 +/- 4.12), tuckpoint grinding (0.22 +/- 1.94), and concrete demolition (0.10 +/- 2.60). In both controlled experimental conditions and field conditions, the use of LEV on several types of tools resulted in an over 90% reduction in dust concentrations. However, even after application of LEV, a significant portion of the dust concentrations exceeded relevant guidelines: 22% greater than the OSHA PEL, and 25% over the ACGIH TLV for respirable silica. The results of these studies clearly show the large degree of effectiveness of LEV applied to typical masonry cutting and grinding tasks. However, some tools (e.g., hand held power ('Quickee' saw) were not controlled by LEV, and even with effective control, some exposures continue to exceed recommended levels of silica exposure. In these conditions, it remains important for workers to participate in effective respiratory protection programs.
Silica-dusts; Ventilation-systems; Exhaust-systems; Respirable-dust; Quartz-dust; Respiratory-protection; Dust-inhalation; Dust-exposure; Dust-measurement; Construction-industry; Construction-materials; Control-technology
University of Washington, Department of Environmental Health, Box 357234, Seattle, WA 98195-7234
Final Grant Report
NTIS Accession No.
Research Tools and Approaches: Intervention Effectiveness Research
National Institute for Occupational Safety and Health
University of Washington, Seattle, Washington