Development of an Advanced Respirator Fit Test Headform (Postprint)

Improved respirator test headforms are needed to measure the fit of N95 filtering facepiece respirators (FFRs) for protection studies against viable airborne particles. The objective of this study was to develop and evaluate a medium-size Static (i.e., non-moving, non-speaking) Advanced headform (StAH) for fit testing N95 FFRs. The StAH was developed based on the anthropometric dimensions of a digital headform reported by the National Institute for Occupational Safety and Health and has a silicone polymer skin with defined local tissue thicknesses. Quantitative fit tests were performed on seven N95 FFR models of various sizes and designs. Donnings were performed with and without a pre-test seal checking method. For each method, four replicate FFR samples were tested of each of the seven models with two donnings per replicate, resulting in a total of 56 tests per donning method. Each fit test was comprised of three one-minute exercises: Normal Breathing (NB, 11.2 liters per minute (lpm)), Deep Breathing (DB, 20.4 lpm), then NB again. A fit factor (FF) for each exercise and an overall test FF were obtained. Analysis of variance methods were used to identify statistical differences among FFs (analyzed as logarithms) for different FFR models, exercises, and donning methods. For each FFR model and for each donning method, the NB and DB FF data were not significantly different (p 0.05). Significant differences were seen in the overall exercise FF data for the two donning methods among all FFR models (pooled data) and in the overall exercise FF data for the two donning methods within certain models. A seal-checking method improved the frequency of obtaining overall exercise FFs 100. The FFR models, which are expected to achieve FFs 100 on human subjects, achieved FFs 100 on the StAH. Further research is needed to evaluate the correlation of FFR fit on the StAH to FFR fit on people. Published in Journal of Occupational and Environmental Hygiene, 11:2, 117-125, 2014.