Bioaerosol disinfection using electro-ozonizers integrated into duct systems for hospital indoor air purification, using Klebsiella pneumoniae as an airborne bacterial model

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In this work, an ozone gas stream is generated using PEM technology (MIKROZON® cell). Ozone is produced in an inert electrolyte through water oxidation, and then naturally transferred to a gaseous stream. The ozone quantity is regulated by adjusting the intensity to produce 0.02 mg min−1 at 0.05 A, 0.16 mg min−1 at 0.50 A, and 0.57 mg min−1 at 1.00 A. The effectiveness of the ozone gas stream is assessed in critical facilities such as hospitals for the inactivation of Klebsiella pneumoniae (K. pneumoniae) and the degradation of the blaKPC-11 gen in bioaerosols extracted from two scenarios: (1) bathrooms due to toilet flushing of urine or wastewater, and (2) other areas of hospitals, such as during emergencies when people’s saliva is atomized. An ozone mass flow of 0.57 mg min−1 was observed to alter the membrane permeability of K. pneumoniae cells, and as a result, blaKPC-11 removals of 1.27 and 0.93 logs are achieved for saliva and urine bioaerosols, respectively. Indeed, these treated air streams could be considered “acceptable” and “intermediate” for reintroduction into patient rooms to maintain thermal comfort, according to the standards set by the WHO expert group and the European Commission classification. The disinfection mechanisms of ozone are further studied, focusing on the competitive reactions that occur with the organic compounds present in the chemical composition of bioaerosols, with a significant impact on oligosaccharides.