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Penetration (P0.3) of samples before and after wearing for 0–8 h as a function of areal density (basis weight). Filter tests were conducted after the first (San = 1) and second (San = 2) heat sanitization treatments. A linear fit of the logarithm of the average particle penetration Log(P) over areal density for unworn media (San = 1) is shown to illustrate the expected trend.
