Effects of 222 nm Germicidal Ultraviolet Light on Aerosol and VOC Formation from Limonene

Abstract

Since the 1930s, germicidal ultraviolet (GUV) irradiation has been used indoors to prevent the transmission of airborne diseases, such as tuberculosis and measles. Recently, it has received renewed attention due to the COVID-19 pandemic. While GUV radiation has been shown to be effective in inactivating airborne bacteria and viruses, few studies on the impact of GUV on indoor air quality have been published. In this work, we evaluate the effects of GUV222 (GUV at 222 nm) on the chemistry of a common indoor volatile organic compound (VOC), limonene. We found that the production of O3 by the GUV222 lamps caused the formation of particulate matter (PM) and oxygenated volatile organic compounds (VOCs). We also found that the chemistry proceeds through the ozonolysis of limonene as well as the reaction with secondary OH, and that the presence of GUV light led to observable but small perturbations to this chemistry. Understanding the effects of GUV222 on indoor air quality is important in evaluating the safety of these devices.

Secondary Organic Aerosol Formation from the OH Oxidation of Phenol, Catechol, Styrene, Furfural, and Methyl Furfural

“…Only one of the included studies shown in Figure was done at intermediate humidity . Humidity can impact Y SOA , sometimes increasing and sometimes decreasing it, and other times having little impact. ,− Future studies should explore the effect of humidity on SOA from these systems.…”

Effects of Germicidal Far-UVC on Indoor Air Quality in an Office Setting

“…22 While ozone formation chemistry has been studied extensively for broad spectrum solar light in the outdoor context, 23,24 the effects of far-UVC indoors are less well-known. Recent numerical modeling 25,26 and laboratory [26][27][28][29][30] studies show that 222 nm far-UVC can increase ozone levels [25][26][27][28][29][30] and SOA formation. 25,26,30 The laboratory studies were mostly performed in reactor systems with low or no ventilation.…”

“…Recent numerical modeling 25,26 and laboratory [26][27][28][29][30] studies show that 222 nm far-UVC can increase ozone levels [25][26][27][28][29][30] and SOA formation. 25,26,30 The laboratory studies were mostly performed in reactor systems with low or no ventilation. These systems differ in important ways from an indoor office environment, which is ventilated and has various reactive surfaces which act as sinks for ozone.…”