From the standpoint of COVID-19, there are many opportunities for nanotechnology-based solutions to increase the efficiency and safety of air filter and mask devices. Some specific opportunities include (i) improving particle capture and retention characteristics, particularly, in the 300 nm diameter size range; (ii) reducing the effects of exhaled humid air on particle redistribution; (iii) rapid inactivation of membrane-bound microbes including enveloped viruses upon capture; and (iv) thin, high-efficiency filtration media for personal masks that are able to be reused repeatedly without loss of efficiency (e.g., novel electrospun nanofibers). In this context, recent findings exploring the performance of several fabrics commonly used in cloth masks, alone or in combination, suggest that the combined mechanical and electrostatic effect observed in hybrids enabled enhanced performance with a filtration efficiency >80 and >90% for particle sizes <300 and >300 nm, respectively.205