# Inactivation of airborne pathogen surrogates by triethylene glycol

## TL;DR

Aerosolized triethylene glycol (TEG) can safely and effectively inactivate airborne pathogens, offering a promising strategy for reducing the spread of infectious diseases.

## Contribution

This study demonstrates that TEG aerosolization is a safe and effective method for inactivating airborne pathogens and highlights the importance of using appropriate testing protocols and surrogates.

## Key findings

- Aerosolized TEG achieves 2 to 4.5 log reduction in airborne pathogens within 30–60 minutes at safe concentrations.
- Aerosolizing TEG and test organisms provides a more accurate measure of antimicrobial efficacy for indoor use.
- TEG is effective against a wide spectrum of viable airborne pathogens at concentrations below safety concerns.

## Abstract

The COVID-19 outbreak brought to the fore the importance of airborne transmission in spreading human infectious diseases and highlighted the need for sustainable mitigation strategies. Triethylene glycol (TEG) has been documented as having microbicidal capabilities and has been proposed as one such mitigation strategy. Aerosolized TEG exhibits antimicrobial activity against airborne microorganisms. Grignard Pure Technology was developed to safely aerosolize TEG for decontamination of enclosed spaces. Here, we show that this TEG formulation effectively inactivates airborne microorganisms, resulting in 2 to 4.5 net log reduction in concentration of viable bacteria, viruses, and mycobacteria within 30–60 min at TEG concentration (aerosol + vapor) of ~0.7 mg/m3, which is well within the range considered safe for humans. Our data also demonstrate that aerosolizing both the test organisms and the antimicrobial product provides a more accurate and relevant measure of the product’s efficacy for indoor usage than traditional surface—or solution—based disinfection assays. Accurate evaluation of antimicrobial efficacy is a crucial step in adopting novel interventions and tools to control airborne pathogens that pose a public health risk. Our findings argue that testing protocols must match the intended use of any intervention. Given the safety concerns of aerosolizing human pathogens for direct testing of airborne infectious burden, we also advance an approach for selecting suitable surrogate microorganisms based on their phenotypic and biophysical similarity to corresponding pathogenic species.

During the COVID-19 pandemic, personal protective equipment, social distancing, and even vaccinations proved sub-optimal in controlling the spread of COVID-19. Public health practice and the hierarchy of controls emphasize primary prevention, whereby the pathogen is removed or destroyed before exposure to the public. Triethylene glycol (TEG) has the potential to inactivate airborne pathogens and limit their spread. TEG is designated a “safer chemical” by the US EPA and has been used for decades in aerosol deodorizers and theatrical special effects. This study shows that aerosolized TEG is highly effective at eliminating a wide spectrum of viable airborne pathogen surrogates at concentrations well below the threshold of safety concern. Thus, it may afford significant protection against the transmission of infectious agents with pandemic potential.