Glycol vapor pathogen disinfection: a defensive technology for emerging biothreats.

Airborne transmission of respiratory pathogens has substantial societal and economic burdens during seasonal epidemics and pandemics. Therefore, there is a need for built environment interventions that prevent pathogen spread indoors. Glycol vapors were historically investigated as air disinfectants and have recently regained attention. Yet their mechanism of action, effectiveness across different environments, and safety remains incompletely defined. Here we describe historical and modern evidence on glycol vapor-mediated pathogen inactivation in the air. Experimental studies have shown rapid reductions in airborne microbial viability under controlled conditions. The data suggest that antimicrobial activity arises from humidity-dependent partitioning of glycol vapors into respiratory droplets, altering droplet chemistry and destabilizing pathogen structures. Indoor environment parameters including humidity, temperature, ventilation, and droplet lifetime were found to strongly influence efficacy. Translating findings from chamber studies into real-world indoor occupied spaces remains challenging. Here, we discuss how sensor-informed modeling and machine-learning approaches could support control of glycol vapor systems by integrating environmental measurements. Existing occupational exposure data from glycol-based theatrical fogs provides useful safety information, however further dedicated exposure studies are still needed. Overall, glycol vapors represent a plausible non-pharmaceutical airborne infection control strategy whose value depends on defining environmental operating conditions and safety limits for continuous deployment.