Quantification of Byproduct Formation from Portable Air Cleaners Using a Proposed Standard Test Method

Abstract

In response to the COVID-19 pandemic, air cleaning technologies were promoted as useful tools for disinfecting public spaces and combating airborne pathogen transmission. However, no standard method exists to assess the potentially harmful byproduct formation from air cleaners. Through a consensus standard development process, a draft standard test method to assess portable air cleaner performance was developed, and a suite of air cleaners employing seven different technologies was tested. The test method quantifies not only the removal efficiency of a challenge chemical suite and ultrafine particulate matter but also byproduct formation. Clean air delivery rates (CADRs) are used to quantify the chemical and particle removal efficiencies, and an emission rate framework is used to quantify the formation of formaldehyde, ozone, and other volatile organic compounds. We find that the tested photocatalytic oxidation and germicidal ultraviolet light (GUV) technologies produced the highest levels of aldehyde byproducts having emission rates of 202 and 243 μg h −1 , respectively. Additionally, GUV using two different wavelengths, 222 and 254 nm, both produced ultrafine particulate matter.

Ozone generation and chemistry from 222 nm germicidal ultraviolet light in a fragrant restroom

“…PTR-MS signals that were not calibrated for directly were converted to concentrations using a parameterization of the instrument sensitivity with the proton-transfer rate constant. 31–33…”

“…PTR-MS signals that were not calibrated for directly were converted to concentrations using a parameterization of the instrument sensitivity with the proton-transfer rate constant. [31][32][33] Terpenoids were an important source of gas-phase reactivity in the restroom. We provide an in-depth discussion of terpenoid quantication in the ESI.…”