Fig 1. An overview of the three-step methodology.

Step 1: Household material coupons were tested for filtration efficiency and pressure drop at a flow velocity of 9 cm/s using dried, charge conditioned aerosols (Table 1). Step 2: Select materials were tested against wet water droplets at very high velocities (~ 481 cm/s and 1700 cm/s) (Fig 2). Step 3: a large volume (0.1 mL) of artificial saliva was deposited on the material surface to investigate the permeability of multilayered DIY coupons (Table 2). SMPS: Scanning Mobility Particle Sizer; CPC: Condensation Particle Counter; APS: Aerodynamic Particle Sizer; DIY coupons: Do-It-Yourself i.e. household material coupons.