Evaluation of the Effect of Particle Size and Particle Sensing Instruments on the Measurement of Mask Protection Factors

摘要

The current method used by the U.S. military to assess mask performance uses a polydisperse corn oil aerosol of 0.4 to 0.6 micron mass median aerodynamic diameter as a simulant challenge atmosphere. Data are presently lacking regarding the effect of particle size and aerosol sensing instruments on the measured protection factor (PF). Data are also lacking regarding the correlation of PFs measured using an insert aerosol challenge, such as the corn oil, with PFs measured using either a biological aerosol or vapor challenge. The objectives of this task were (1) to evaluate the effect of aerosol detection instruments and aerosol size on measured protection factor, (2) to assess whether inert aerosols are suitable for predicting respirator performance against surrogate biological aerosols, and (3) to assess whether an inert aerosol is a good indicator of respirator performance that is challenged with a vapor. The foremost finding in this study is that the corn oil/photometer test method is a good indicator of PFs that would be experienced by masks challenged with either similar sized aerosols or inert vapors. In addition, use of the corn oil/photometer method used to measure PFs is a conservative estimator of PFs that would be measured against a bioaerosol challenge with a particle size greater than 1 micron.