Study Says More Protection Needed for Manual Concrete Grinding
Evaluating the equipment, engineering controls, and grinding methods currently used for manual concrete surface grinding, a study published in JOEH says current methods to control dust aren't sufficiently protective.
Methods currently used to protect workers who manually grind concrete surfaces from dust exposures are not sufficient, a paper published in the December issue of the Journal of Occupational and Environmental Hygiene concludes. Its authors measured silica dust exposure of a volunteer, an experienced grinder who was wearing a powered air-purifying respirator and other PPE, as he ground nine concrete slabs inside a field laboratory equipped with an industrial fan.
The eight authors work at the University of Toledo Department of Public Health & Preventive Medicine (Toledo, Ohio) and CPWR, the Center for Construction Research and Training (Silver Spring, Md.), and this research was funded by NIOSH. They tested how well various types of ventilation worked at capturing the dust produced by methods currently used for manual concrete surface grinding and concluded the resulting dust exposures, if lasting for a full eight-hour day, exceeded ACGIH's recommended silica dust exposure criterion of 0.025 mg/m3.
"This strongly suggests the need for further refinement in the engineering control options and additional administrative controls or the use of respirators," the authors concluded. They said workers should wear air-purifying respirators with protection of at least 10 when using a grinder equipped with local exhaust ventilation; with protection of at least 100 with wet grinding; and 200 (e.g., PAPRs) with uncontrolled grinding.
"There is an urgent need for uniform guidelines for the manufacture and selection of equipment appropriate for manual concrete grinding, the assembly of retrofitted dust control apparatuses, and the maintenance of hand-held angle grinders and the accessories that are commonly used for concrete grinding," they wrote. The paper cites a Bureau of Labor Statistics report that more than 201,730 workers in the United States in 2008 were engaged in concrete grinding using hand and/or power tools.