The Effect of Local Exhaust Ventilation Controls on Dust Exposures During Concrete Cutting and Grinding Activities

Abstract

This study assessed the effectiveness of commercially available local exhaust ventilation (LEV) systems for controlling respirable dust and crystalline silica exposures during concrete cutting and grinding activities. Work activities were performed by union-sponsored apprentices and included tuck-point grinding, surface grinding, paver block and brick cutting (masonry saw), and concrete block cutting (hand-held saw). In a randomized block design, implemented under controlled field conditions, three ventilation rates (0, 30, and 75 cfm) were tested for each tool. Each ventilation treatment was replicated three times in random order for a total of nine 15-min work sessions per study subject. With the exception of the hand-held saw, the use of LEV resulted in a significant (p < 0.05) reduction in respirable dust exposure. Mean exposure levels for the 75 cfm treatments were less than that of the 30 cfm treatments; however, differences between these two treatments were only significant for paver block cutting (p < 0.01). Although exposure reduction was significant (70-90% at the low ventilation rate and 80-95% reduction at the high ventilation rate), personal respirable dust [corrected] exposures remained very high: 1.4-2.8 x PEL (permissible exposure limit) at the low ventilation rate and 0.9-1.7 x PEL at the high ventilation rate. Exposure levels found under actual field conditions would likely be lower due to the intermittent nature of most job tasks. Despite incomplete control LEV has merit, as it would reduce the risk of workers developing disease, allow workers to use a lower level of respiratory protection, protect workers during short duration work episodes reduce exposure to nearby workers, and reduce clean-up associated dust exposures.

Occupational demands and health effects for bricklayers and construction supervisors: A systematic review

“…Various measurement methods were used to quantify the exposure to dust, such as self-reports [Carlsten et al, 2007], observations by an industrial hygienist [Methner, 2000], and direct measurements at work [Freeman and Grossman, 1995;Linch et al, 1998;Croteau et al, 2002;Flanagan, 2003;Rappaport et al, 2003;Yereb, 2003].…”

“…During cutting of brick and block without dust control, concentrations ranging from 2.35 to 125 mg/m 3 were measured [Croteau et al, 2002;Flanagan, 2003;Yereb, 2003], depending on the type of material (brick or block) and type of saw used. When using ventilation or wet cutting, concentrations ranging from 0.3 to 13.12 mg/m 3 were measured [Croteau et al, 2002;Yereb, 2003].…”

Efficiency of a Tool-mounted Local Exhaust Ventilation System for Controlling Dust Exposure during Metal Grinding Operations

“…The calibration factor of the dust monitor was 4.45 × 10 -3 mg/m 3 /cpm (n=5, S.D.=0.95 × 10 -3 ). Since sampling periods of a short duration are commonly used in engineering control and exposure assessment studies 3,4) , air sampling was carried out only during actual grinding time (3 min) in the PVC chamber. In order to protect the air sampler from the grinding spatters, a distance of 40 cm was maintained between the grinding wheel and the sampling point (Fig.…”

Engineering Control Technologies to Reduce Occupational Silica Exposures in Masonry Cutting and Tuckpointing

“…27 Thorpe et al 21 described silica exposure reductions of at least 90% for cutting concrete slabs with cut-off saws using water to suppress dust and cutting concrete slabs with a grinder using local exhaust ventilation (LEV). Croteau et al 28 examined the use of LEV for reducing exposures from several construction tasks, including tuckpointing and block cutting, with exposure reductions ranging from 80% to 95% at the higher of two ventilation rates tested. The study presented in this article evaluated the use of water and/or LEV to control respirable silica exposures associated with cutting block and brick, and with use of tuckpointing grinders.…”

“…In previous studies of similar tools and tasks, the manufacturer modified the equipment upon request 20 or the investigators used aftermarket controls and vacuums. [27][28][29] The manufacturers of the equipment used in our study designed the controls to be purchased as off-the-shelf, commercially available products that include the tool with the shroud and vacuum (LEV) or water suppression system (wet methods) as part of the package.…”