Evaluation of AccuFIT 9000: A Novel Apparatus for Quantitative Fit Testing of Particulate Respirators

Various strategies developed for protecting frontline workers and the general public from the novel coronavirus, SARS-CoV-2, largely rely on respiratory protective devices (RPDs), especially considering recent evidence about the aerosol transmission route of COVID-19. Performance of an RPD primarily depends on how well the protective device fits the wearer. Therefore, quantitative fit testing of particulate respirators is crucial for achieving the intended protection level. Millions of fit tests are conducted every year using a US OSHA-accepted standard protocol involving a PortaCount® (TSI Inc., Shoreview, MN, USA) which measures a respirator fit factor. Recently, several alternative fit testing instruments have been developed and introduced to the market. Among them is an AccuFIT 9000 (Kanomax-Japan Inc., Suita-city, Osaka, Japan), which, like the PortaCount®, utilizes the condensation particle counting principle, but features an advanced saturation chamber design allowing for a longer residence time and greater flow stability. It is also claimed to have a more cost-efficient assembly than its predecessors. In this study, the novel AccuFIT apparatus was extensively evaluated against the PortaCount® (the reference instrument) using the traditional standard fit testing protocol and following the American National Standards Institute (ANSI) standard (Z88.10-2010 Annex A2). The evaluation was performed with three types of respirators, N95 filtering facepiece respirator (FFR), P100 FFR, and half-mask elastomeric facepiece, of different models and manufacturers donned on 25 subjects. The comparative testing and analysis showed that the AccuFIT 9000 is capable of identifying an inadequate fit of the tested respirators with a sensitivity 0.95 and specificity of 0.97, which meets the ANSI requirement of ≥0.95. The other ANSI requirements/recommendations were also met. It was concluded that the novel fit testing apparatus demonstrated an acceptable performance and, thus, can be successfully deployed for the quantitative respirator fit testing.