The impact of clothing on ozone and squalene ozonolysis products in indoor environments

Abstract

Multiphase reactions of ozone with human skin oils impact indoor air quality by depleting ozone and forming semi-volatile organic compounds, which can be respiratory and skin irritants. Here we demonstrate the impact of clothing on indoor air composition and human exposure by integrating indoor chemistry modeling over a wide range of different spatial and temporal scales. Constrained by molecular dynamics simulations that provide key kinetic parameters, the kinetic model reproduces experimental measurements and predicts that squalene could persist in clothing for several hours to over a day depending on ozone concentrations. Soiled clothing protects skin from ozone exposure even with high concentrations, but can enhance concentrations of oxidation products to a ppb level depending on air exchange rates. Computational fluid dynamics simulations reveal that primary products have~1.6-2.0 times higher concentrations in the breathing zone than in bulk room air, while secondary products are distributed more uniformly throughout a room.

The atmospheric chemistry of indoor environments

“…96 Other recent studies have shown how soiled clothing protects us from gas-phase oxidants but can also enhance dermal exposure to chemical pollutants. 141,205,250,251 Residence time, light and oxidant levels. Also different from outdoors is the short, roughly hour-long residence time of indoor air, and the lower concentrations of gas-phase oxidants and light.…”

“…177,187,203 Recently, aspects of this complexity have been added into models of multiphase oxidation processes occurring in the indoor environment, such as the oxidation of unsaturated lipids in skin oil and the formation of associated carbonyls 204 and in soiled clothing. 205 Ozone also reacts heterogeneously with many other electronrich substrates, such as condensed-phase polycyclic aromatic hydrocarbons (PAHs) and nicotine. [206][207][208][209][210] These pollutants can arise from incomplete combustion processes, such as candle burning, cooking stove operation, and smoking.…”

“…A modeling consortium has been formed with a hierarchical approach to the development of indoor modeling, 4 an approach that is already providing insights into fundamental interactions of gases with building materials 152,260 and the heterogeneous chemistry that occurs when ozone interacts with within skin oils and clothing. 204,205 This approach is required because detailed processes at the molecular level can not be directly incorporated into models that capture air motions using computational uid dynamics. Condensed-phase molecular dynamics models can inform the fundamental chemistry that is incorporated into multilayer numerical models that capture both partitioning and reactive processes.…”

Indoor Surface Chemistry: Developing a Molecular Picture of Reactions on Indoor Interfaces

“…30,32,[52][53][54] Recent studies have focused on surface adsorption and oxidation chemistry of relevant OCs, including ozonolysis of an unsaturated triglyceride 55 and squalene. 56 Surface Chemistry of Nitrogen Oxides Including HONO Indoors It is well known that nitrogen oxides, NO and NO 2 , are present in indoor air from combustion processes, including cooking, and outdoor transport. 17 More recently, painted surfaces have been identified as a source of photochemically produced NO and NO 2 .…”

Effect of sensor position on the performance of CO2-based demand controlled ventilation

“…Based on the previous studies and recommendations regarding CFD validation process [32][33][34][35][36], we performed experiments in a full-scale environmental chamber and used the measurement data for validating the CFD model as described in the following sections. Figure 1).…”