Ultra-Low Concentrations of Triethylene Glycol, Hydrogen Peroxide and Ozone and Their Combinations Exert Additive Biocidal Effect on A Real Indoor Environment Microbiota

Monitoring and control of the microbiota present in indoor air bioaerosols has gained much interest since the COVID19 pandemic because indoor air has been shown to be an important pathway for the spread of pathogens. For this reason, it is necessary to develop strategies to mitigate airborne transmission of diseases. This work addresses the infection control in indoor air by studying the application of biocides in aerosol or gaseous forms with the aim of reducing “in-situ” the breathable airborne microbiota. The objective of this work has been to test the biocidal potential of not toxic and ultra-low concentrations of hydrogen peroxide (≤ 1 ppm), ozone (≤ 0.2 ppm) and triethylene glycol. They were tested individually and in combinations, in a real indoor environment. Decomposition of hydrogen peroxide and ozone in air were identified by electronic paramagnetic resonance spectroscopy. The biocidal capacity of these compounds and their combinations were analysed by measuring population of commercial sporulated bacteria, airborne microbiota and the microbiota present on surfaces. Nebulization of triethylene glycol have shown fungicidal activity and combination with ozone enhanced bactericidal capacity. Finally, three compounds combination resulted in airborne reduction of 93.8 and 100 % of bacterial and fungi population, respectively.