Ozone reaction with clothing and its initiated VOC emissions in an environmental chamber

Abstract

Human health is adversely affected by ozone and the volatile organic compounds (VOCs) produced from its reactions in the indoor environment. Hence, it is important to characterize the ozone-initiated reactive chemistry under indoor conditions and study the influence of different factors on these reactions. This investigation studied the ozone reactions with clothing through a series of experiments conducted in an environmental chamber under various conditions. The study found that the ozone reactions with a soiled (human-worn) T-shirt consumed ozone and generated VOCs. The ozone removal rate and deposition velocity for the T-shirt increased with the increasing soiling level and air change rate, decreased at high ozone concentrations, and were relatively unaffected by the humidity. The deposition velocity for the soiled T-shirt ranged from 0.15 to 0.29 cm/s. The ozone-initiated VOC emissions included C6-C10 straight-chain saturated aldehydes, acetone, and 4-OPA (4-oxopentanal). The VOC emissions were generally higher at higher ozone, humidity, soiling of T-shirt, and air change rate. The total molar yield was approximately 0.5 in most cases, which means that for every two moles of ozone removed by the T-shirt surface, one mole of VOCs was produced.

Study of outdoor ozone penetration into buildings through ventilation and infiltration

“…Although the surface ozone reaction decreases the indoor ozone concentration, it can generate secondary byproducts such as volatile organic compounds (VOCs) and ultrafine particles that can be even more harmful than ozone itself [6,41,42]. According to Eq.…”

“…Occupants might be a significant part of ozone sink [41,42], and thus different density of occupants will pose uncertainties to the ozone surface removal rate and make the prediction of I/O ratio less accurate.…”

How do breath and skin emissions impact indoor air chemistry?

“…The skin surface was defined as 2 m 2 for an adult and 1 m 2 for a child . Although some of the skin surface will be covered by clothing, we assume that the rate of ozone deposition and secondary product formation is not significantly different to bare skin . This assumption appears to be reasonable given the good agreements between our model predictions and the measurements of Wisthaler and Weschler presented in Figure in the model validation section.…”

“…For instance, squalene (a non‐volatile triterpene) constitutes ~10% and the fatty acids approximately 25% of human skin lipids . Following reactions of such species with ozone, a wide range of secondary products can be formed, including aldehydes, ketones, acids, and secondary organic aerosols (SOA), some of which might be harmful to health …”

“…8 Following reactions of such species with ozone, a wide range of secondary products can be formed, including aldehydes, ketones, acids, and secondary organic aerosols (SOA), some of which might be harmful to health. 2,4,5,[9][10][11] The main products of the ozone-squalene reaction are 4-oxopentanal (4-OPA), 6-methyl-5-hepten-2-one (6-MHO), acetone, and geranyl acetone. 12 Additionally, following ozonolysis of unsaturated fatty acids, higher aldehydes can be formed, namely hexanal, heptanal, octanal, nonanal, decanal, dodecanal, and undecanal.…”