# Combating Pathogens Using Carbon-Fiber Ionizers (CFIs) for Air Purification: A Narrative Review
## 2 Material and Methods  
A literature search was performed using the electronic databases Google Scholar, PubMed(r), and the Cochrane organization. On 16 April 2024, a search was conducted on the Google Scholar search engine using the terms \"carbon-fiber ionizer AND pathogen\", which yielded 111 results. The search utilizing the same search syntax on the PubMed database on 24 May 2024 retrieved 0 results. The search on the Cochrane collaboration was performed on 24 May 2024 using the following search word: \"carbon-fiber ionizer AND pathogen\", \"carbon-fiber ionizer\", and \"carbon-fiber\", again yielding no results. Apart from the pertinent papers from the aforementioned search, additional relevant literature, found in the reference lists of several publications, was also utilized. The articles included in this review were published peer-reviewed articles in English concerning the application of the examined technology, which pertains to indoor environments as well. The major aim of the study was to evaluate carbon fiber ionization as a viable technique for mitigating pathogens in indoor settings. Unpublished manuscripts, books, doctoral dissertations, and publications in languages other than English were excluded from the literature analysis. The following data were taken into consideration: type of ions generated, ion microbicidal performance, pathogen characteristics (viruses, bacteria, or fungi), and ozone generation. The search methodology and types of data are further illustrated in Figure 1. The database search results are represented in Table 1 (Section 3), along with relevant information and the respective studies referenced. Figure 1: Search methodology and major data types used in the reference classification and evaluation. Major ionization outcomes are listed. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Microorganism** & **Outcome of Ionization \({}^{*}\)** & **Ion Type and Performance** & **Ozone Levels** & **References** \\ \hline Surrogates (particle sizes equivalent to pathogen dimensions) & Particle deposition & – ions better than bipolar ions & \(<\)5 ppb & [3] \\ \hline  & **Bacteria** & & & \\ \hline  & **S**_Stphylococcus epidermidis,_ & Microbial destruction \({}^{b}\) & + ions better than – ions & \(<\)10 ppb & [10] \\  & _Escherichia coli_ & (membrane disruption) & + ions & 21.8–26.0 ppb & [14] \\  & _Stphylococcus epidermidis,_ & Microbial destruction & – ions & 3.0–3.5 ppb & [15] \\  & _Escherichia coli_ & (membrane disruption) & + ions & 20.026 mg/10 & [15] \\  & _Escherichia coli_ & Microorganism inactivation & – ions & 3.0–3.5 ppb & [emission rate 0.026 mg/10] & [15] \\  & (see also viruses) & Antibacterial effect & Bipolar ions eliminate bacteria & \\  & & Cell contraction & Unipolar (+) activity not & \(<\)25 ppb & [16] \\  & & antibacterial & & \\  & _Stphylococcus epidermidis, Seratia_ & Microbial inactivation & – ions & 68 ppb \({}^{c}\) & [17] \\  & _Stphylococcus aureus, Escherichia coli,_ & Potent bactericidal effect & – and + air ions & \(-\)35 ppb & [18] \\  & _Stphylococcus_ & Microbial deposition & – ions better than + ions & Not measured & [19] \\  & _aurens_ & The increased viability & & & \\  & & On Per kil dishes (10^- CFU/mL). & &