To examine whether UV-treated or detergent-laundered respirators changed their chemistry, contact angles and FTIR spectra from those surfaces were examined (Figure 4B,C). Untreated PP media has C-H stretching (2906 cm−1), CH2/CH3 asymmetrical bending (around 2982 cm−1), and other carbon and hydrogen bonding (2835 to 2972 cm−1) peaks [47,48]. After UV irradiation, distinctive peaks were observed for: C-O-C (around 1058 cm−1) and O-H bending (around 1161 cm−1) [49,50]. The changed surface chemistry seemed to attribute to surface oxidation, but hardly affected the wettability and filtration performance after UV treatment. Solvent treatments with IPA, EtOH, and ClO− showed neither noxious residues nor distinctive hydrophilic bonding.