Real-Time Laboratory Measurements of VOC Emissions, Removal Rates, and Byproduct Formation from Consumer-Grade Oxidation-Based Air Cleaners

Abstract

Levels of volatile organic compounds (VOCs) in the indoor environment can be decreased by the use of "air cleaners", devices that remove VOCs by sorption and/or oxidative degradation. However, efficacies of these technologies for removing VOCs tend to be poorly constrained, as does the formation of oxidation byproducts. Here, we examine the influence of several oxidation-based air cleaners, specifically ones marketed as consumer-grade products, on the amounts and composition of VOCs. Experiments were conducted in an environmental chamber, with a suite of real-time analytical instruments to measure direct emissions, VOC removal efficacies (by the addition of either limonene and toluene), and byproduct formation. We find that the air cleaners themselves can be a source of organic gases, that removal efficacy can be exceedingly variable, and that VOC loss is primarily driven by physical removal in some cleaners. When oxidative degradation of VOCs was observed, it was accompanied by the formation of a range of oxidation byproducts, including formaldehyde and other oxygenates. These results indicate that some consumer-grade portable air cleaners can be ineffective in removing VOCs and that the air delivered may contain a range of organic compounds, due to direct emission and/or byproduct formation.

Model Evaluation of Secondary Chemistry due to Disinfection of Indoor Air with Germicidal Ultraviolet Lamps

“…Very few studies on this topic have been conducted with state-of-the-art measurements or models. Recently, air cleaning devices based on chemistry induced by UV light (photocatalysis and OH generation, but not GUV), often also marketed as suitable for air disinfection, have been experimentally shown to produce significant amounts of OVOCs and SOA. , …”

“…Recently, air cleaning devices based on chemistry induced by UV light (photocatalysis and OH generation, but not GUV), often also marketed as suitable for air disinfection, have been experimentally shown to produce significant amounts of OVOCs and SOA. 31,32 Despite the potential of GUV to cause secondary chemistry, to our knowledge this topic has not been studied in detail to date. Some studies of GUV inactivation effectiveness have included measurements of ozone, to assess whether any was generated.…”

Wildfires Increase Concentrations of Hazardous Air Pollutants in Downwind Communities

“…83 Studies have found variable VOC removal rates, depending on cleaning technology 84 with some technologies adding to the pollution by emitting oxygenated hydrocarbon byproducts. 85 As area burned and the frequency of large wildfires continues to increase along with the probability of these fires entering the WUI, [3][4][5]18 it will become even more important to understand the capabilities of exposure reduction and mitigation options in reducing HAPs exposures.…”

Model Evaluation of Secondary Chemistry due to Disinfection of Indoor Air with Germicidal Ultraviolet Lamps

“…Recently, air cleaning devices based on chemistry induced by UV light (photocatalysis and OH generation, but not GUV), often also marketed as suitable for air disinfection, have been experimentally shown to produce significant amounts of OVOCs and SOA. 27,28 Despite the potential of GUV to cause secondary chemistry, to our knowledge this topic has not been studied in detail to date. Some studies of germicidal UV inactivation effectiveness have included measurements of ozone, to assess whether any was generated.…”

“…Recently, air cleaning devices based on chemistry induced by UV light (photocatalysis and OH generation, but not GUV), often also marketed as suitable for air disinfection, have been experimentally shown to produce significant amounts of OVOCs and SOA. 27,28…”