NIOSH Recommends Controls for Reducing Silica Exposure When Cutting Fiber-cement Siding
A NIOSH publication released in June recommends controls for reducing construction workers’ exposures to hazardous dust containing silica when cutting fiber-cement siding. According to the agency, the use of fiber-cement siding in construction and renovation is rapidly increasing, and fiber-cement products can contain as much as 50 percent crystalline silica. Though there are relatively dust-free methods of cutting fiber-cement board, using a power saw is the quickest and most precise method for cutting board for siding, the publication notes. A 2013 field survey found that a worker’s uncontrolled exposure to respirable crystalline silica while cutting fiber-cement board resulted in an exposure of between 0.02 and 0.13 mg/m3, or up to 2.6 times the NIOSH recommended exposure limit of 0.05 mg/m3. A NIOSH-conducted study to develop practical engineering control recommendations for respirable crystalline silica from cutting fiber-cement siding found that workers’ exposures could be reduced by attaching a regular shop vacuum to a dust-collecting circular saw. According to NIOSH, the shop vacuum should have an air-flow rate of about 30 CFM or higher. The publication details further recommended controls regarding the local exhaust ventilation (LEV) system, circular saws and circular saw blades, work practices, and respirators.