title: Evaluation of cut-off saw exposure control methods for respirable dust and crystalline silica in roadway construction.
abstract: Dust reduction equipment adapted for single-person operation was evaluated for gas-powered, commercially available cut-off saws during concrete curb cutting. Cutting was performed without dust control and with two individual exposure control methods: wet suppression and local exhaust ventilation (LEV). The wet suppression system comprised a two-nozzle spray system and a 13.3-L hand-pressurized water supply system with an optimum mean flow rate of 0.83 L/min for 16 min of cutting. The LEV system consisted of a spring-loaded guard, an 18.9-L collection bag, and a centrifugal fan with an estimated exhaust rate of 91 ft(3)/min. Task-based, personal filter samples were obtained for four saw operators during cutting durations of 4 to 16 min on five job sites. Seventeen filter samples were collected without dust control, 14 with wet suppression, and 12 with LEV, yielding a geometric mean respirable dust concentration of 16.4 mg/m(3), 3.60 mg/m(3), and 4.40 mg/m(3), respectively. A dust reduction of 78.0% for wet suppression and 73.2% for LEV was observed vs. no dust control. A statistically significant difference (p < 0.001) was also revealed for wet suppression and LEV when compared with no dust control; however, a significant difference (p = 0.09) was not observed between wet suppression and LEV. Despite these significant dust reductions, workers are still projected to exceed the ACGIH 8-hr time-weighted average threshold limit value for quartz (0.025 mg/m(3)) in less than 1 hr of cutting for both dust control methods. Further research is still needed to improve dust reduction and portability of both control methods, but the current LEV system offers important advantages, including a drier, less slippery work area and year-round functionality in cold weather.
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, USA. bmiddaug@purdue.edu
authors.forename: Beauregard
authors.initials: B
authors.lastname: Middaugh
authors.forename: Bryan
authors.initials: B
authors.lastname: Hubbard
authors.forename: Neil
authors.initials: N
authors.lastname: Zimmerman
authors.forename: James
authors.initials: J
authors.lastname: McGlothlin
mesh_terms: D003252:Construction Materials / Q000032:analysis*; D004391:Dust / Q000032:analysis*; D006801:Humans; D019570:Inhalation Exposure / Q000517:prevention & control*; D016273:Occupational Exposure / Q000032:analysis / Q000517:prevention & control*; D011482:Protective Devices; D012822:Silicon Dioxide / Q000032:analysis*; D014691:Ventilation
chemical_list: D004391:Dust; D012822:Silicon Dioxide