The degree to which temperature affects initial filter aerosol penetration and component melting was observed to be model specific (Figs 1 and 2) . The average initial penetration (n 5 3) for each N95 model is shown in Fig. 1 . Only three tested N95 FFR samples had filter aerosol penetrations .5% (therefore failed to maintain their expected filtration efficiency level of !95%). These three failing samples were one SN95-D (5.37% at 110°C) and two N95-C (5.18 and 5.37%, both at 120°C). Five of the SN95-D samples could not be analyzed following treatments of 100°C (one sample), 110°C (two samples), and 120°C (two samples) because their inner moisture barrier melted into the filtration media rendering those samples unsuitable for testing. For the three P100 FFR models, average initial filter aerosol pene-tration values for P100-G and P100-H exceeded 0.03% beginning at 100°C for P100-G and beginning at 90°C for P100-H (Fig. 2) . P100-I averaged an initial filter aerosol penetration value ,0.03% for all evaluated temperature increments with the exception of one 110°C temperature experiment. This unexpectedly high average result was due to a single test (%P 5 0.096).