Overview: Technologies based on the use of low concentrations of gaseous or ionized hydrogen peroxide have been employed in hospitals to reduce surface pathogen contamination risk and improve surface sanitation since at least 2014. Their use has expanded to US military installations, restaurants, sports arenas, and other facilities. Some trade names of this type of technology include Dry Hydrogen Peroxide and Ionized Hydro-Peroxide. The technologies use proprietary processes to generate hydrogen peroxide molecules or ions in the air at low concentrations, similar to a photocatalytic oxidizer (PCO). Unlike PCO devices that create many types of hydrogen and oxygen ions, these technologies generate hydrogen peroxide molecules specifically, and release them into the air. High-concentration liquid hydrogen peroxide has also been used in some schools for surface sanitation, distributed as a vapor from backpack sprayer systems, but can’t be used in occupied spaces, and is not considered here as a potential air purification application.
Removes, Dilutes, or Inactivates Pollutants: These technologies are claimed to reduce airborne particulates, volatile organic compounds (VOCs), and pathogens, based on lab studies under idealized conditions. However, real-world application involves potentially concerning partial chemical reactions and slower reaction rates than these idealized lab results. Thus, SEDAC has not yet seen conclusive evidence of the efficacy of these devices for airborne contaminant removal in practical applications in buildings. These systems are designed to provide continuous pathogen inactivation on surfaces in spaces supporting regular manual cleaning activities, which has been supported by academic research studies published in the American Journal of Infection Control.[1],[2] A July 2021 study focused specifically on COVID reduction from surfaces found that 120 minutes of exposure reduced the infectivity of SARS-CoV-2 by 98.7%,[3] although there was little impact on infectivity before that 120-minute mark, and airborne impacts were not measured.
Harmful Byproducts: The hydrogen peroxide produced by these technologies is not hazardous on its own as concentrations produced are below the OSHA safe exposure limit of 1 part per million (ppm). However, concerns exist around partial chemical reactions with airborne VOCs and other pollutants, which can potentially create more harmful byproducts like formaldehyde, nitrogen dioxide, and carbon monoxide[4] in practical operation. These partial reactions need further study for air cleaning applications.
Added Energy: An example device uses a 21W UV-A lamp and small fan to generate and distribute ions. Reports on design room size applications are sparse, but a USO application serves 22,000 sf with 10 units, so an estimate of 1 device for every 2,000 sf seems reasonable. Likely one device per classroom and multiple devices in larger spaces like gyms and auditoriums would achieve design hydrogen peroxide concentrations for microbial reductions.
Install Cost: In-room units for one example product were reported to cost around $2,500 to $3,000 each.[6] Units designed for air handler applications will also require some labor to install in the unit, though modification of the existing HVAC system shouldn’t be necessary in most cases.
Looking beyond the Pandemic: Indoor air quality professionals recommend using proven technologies such as fresh air ventilation, high-MERV or HEPA filtration, and UVGI to control indoor air quality. While the use of low-concentration gaseous or ionized hydrogen peroxide is effective as a supplement for surface cleaning applications, SEDAC has not yet seen conclusive peer-reviewed research on its use as an air cleaning device. SEDAC does not recommend the use of this technology to replace or reduce proper ventilation of outdoor and filtered air in spaces as a way of reducing airborne transmission risk.
[1] https://www.ajicjournal.org/article/S0196-6553(20)30810-5/fulltext
[2] https://www.ajicjournal.org/action/showPdf?pii=S0196-6553%2821%2900136-X%20
[3] https://www.ajicjournal.org/article/S0196-6553(21)00467-3/fulltext
[4] https://www.epa.gov/sites/default/files/2018-07/documents/residential_air_cleaners_-_a_technical_summary_3rd_edition.pdf
[6] https://www.ksby.com/news/local-news/paso-robles-school-district-purchases-equipment-to-protect-against-covid-19
