Test Chamber Simulation Studies Confirm Respirator Effectiveness for Airborne Coal Dust

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A number of personal injury claims asserted that NIOSH-approved respirators worn by coal miners were tested using silica dust and therefore were not effective for miners exposed to airborne coal dust. The NIOSH method evaluated the performance of air-purifying respirators according to Title 30, Part 11 of the Code of Federal Regulations. A law firm representing a respirator manufacturer retained RJ Lee Group to conduct studies using their client’s respirators to determine if the respirators were effective when exposed to airborne coal dust.

Our experts constructed a dust generation chamber similar to the NIOSH chamber to determine the overall efficacy of the respirator when exposed to airborne coal dust. The test chamber included mounted filtering face pieces and computer-operated breathing simulators. The equipment and protocol for running the coal dust tests followed those set forth in the Code of Federal Regulations (CFR): Title 30, Part 11, Subparts 11.140-4 (where coal dust was substituted for silica dust). We secured samples of bituminous coal from a mine of interest, ground and sieved the samples and injected the sieved coal dust into the simulation chamber.

The studies we conducted with coal dust confirmed the original findings of the NIOSH tests using silica dust indicating that the respirators were effective for use in coal mines. We confirmed our laboratory testing by conducting on-site coal mine studies and comparing the results.