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(a) Size-dependent filtration efficiency and (b) pressure drop of accessible household media tested as single- and double-layer 47 mm punches measured in a filter-holder-based system. (Face velocity: 4.2 cm s−1, punch: 47 mm, aerosol: 0.3 M NaCl, NTOT: 2 × 106 #/cm3, RH: 32–35%, and scan-time: 1 min (scanning mobility particle sizer (SMPS)).
