Assessing Respirator Protection Factor with Novel Personal Instruments

A quantitative fit test is performed using a bench-top instrument to assess the protection factor provided by a respirator when assigned to a worker. There are no wearable instruments on the market to measure protection factors while the respirator is in use.

The aim of this study is to evaluate two new, wearable, quantitative instruments, a dual-channel optical particle counter (DC OPC) and a dual-channel condensation particle counter (DC CPC). These instruments would enable in-situ, real-time measurement of respirator workplace protection factor. Respirator protection factors measured by the new instruments are compared to those measured with the TSI PortaCount®, the current gold standard. The instruments were tested on one test subject for three test aerosols (sodium chloride, incense, ambient) at target protection factors of 100, 300, and 1000 for sodium chloride and ambient, and 75 and 500 for incense.

Protection factors measured with the DC CPC agree with those measured with the gold standard whereas those from the DC OPC generally do not. Mean protection factors derived from the DC CPC are only statistically significantly different for mean values of a protection factor at ambient conditions for a target protection factor of 300 and 1000 and for incense at a target protection factor of 100.

The difference in protection factors derived from the DC CPC are not substantial in practice and may be explained by systematic uncertainty. In contrast, the DC OPC reports substantially larger and statistically significantly different mean protection factors for the sodium chloride aerosol for target protection factors of 100 and 300.