# Combating Pathogens Using Carbon-Fiber Ionizers (CFIs) for Air Purification: A Narrative Review
## 4 Discussion
### Air Ionization and Microorganisms--A Familiar Interplay?
Similarly, in a controlled experiment, [PERSON] et al. [63] successfully demonstrated the prevention of airborne transmission of influenza A virus between animals through the use of NAIs. A robust inhibitory effect on the viability of airborne bacteria, namely _Staphylococcus aureus_ and _Escherichia coli_, exposed to positive and negative ions was demonstrated by [PERSON] et al. [20]. Moreover, ion exposure reduced the viability of bacteria soaked in air filters, suggesting potential applications for air purification systems that incorporate ionization technology to prevent the spread of infections. Interestingly, [PERSON] et al. [37] indicated that the principal cause of bacterial inactivation was exposure to ozone generated during ionization rather than the direct effect of both positive and negative ions, which should be taken into account in every study concerning the assessment of ionizing devices on microorganisms [18]. It was noted that positive, negative, and bipolar combinations of air ions can all effectively remove bioaerosols from the air, although each functions at its own specific role and rate [4]. Air ionization is especially helpful when dealing with a high viral load in enclosed spaces, where degradation is sped up and filtration, along with removal, is more effective. Negative air ions target bacteria, molds, and viruses in indoor air. The effectiveness of removing particles depends on both the rate at which ions are emitted in a confined area and the volume of the space itself [79]. Recently, it has been revealed that while positive ions enforce their bactericidal effects through physical means, negative ions operate equally through physical and chemical mechanisms [22]. Consider that the process of sterilizing the air may forgo the need for particle removal, rendering the pathogen benign [71]. Traditional ionizers produce ozone, an unwanted byproduct, while newer models do not carry this risk [55]. Electrostatic removal by simulating corona discharge, hence ionizing the field, disinfecting, and eliminating any biological aerosols, was recommended as a public measure in large-scale public institutions [22]. Electrostatic precipitator methods serve two purposes simultaneously: the physical removal of pathogens and biological disinfection [80]. In ionized electric fields, particles acquire a charge and are drawn towards collection plates due to the Coulomb force, a process known as physical removal. Additionally, ions produced by corona discharge have the ability to deactivate bacteria and other microorganisms [30; 31]. Other researchers noted that treatment with negative air ions (NAIs) alone had no killing effect on any of the investigated bacterial species, exerting its effects through the strong interplay between ozone and NAIs [28]. Even bacterial aerosols like _E. coli_ were analyzed and found to be removed by UVD, but not UVA or UVC, whose disinfect properties were attributed to the generation of ozone [81]. In another study, seven bacterial species were introduced to both positive and negative air ions, and the primary mechanism of cell death among the bacteria studied was exposure to ozone, with electroporation due to NAIs playing only a secondary role. The authors even suggested that any bactericidal or therapeutic effects ascribed to negative air ions by previous researchers may perhaps be blown out of proportion [37; 76]. All in all, it seems that the vulnerability of bacterial strains to NAIs varies based on their strain type, physiological condition, and their proximity in relation to the source [82].