The human oxidation field

Abstract

Hydroxyl (OH) radicals are highly reactive species that can oxidize most pollutant gases. In this study, high concentrations of OH radicals were found when people were exposed to ozone in a climate-controlled chamber. OH concentrations calculated by two methods using measurements of total OH reactivity, speciated alkenes, and oxidation products were consistent with those obtained from a chemically explicit model. Key to establishing this human-induced oxidation field is 6-methyl-5-hepten-2-one (6-MHO), which forms when ozone reacts with the skin-oil squalene and subsequently generates OH efficiently through gas-phase reaction with ozone. A dynamic model was used to show the spatial extent of the human-generated OH oxidation field and its dependency on ozone influx through ventilation. This finding has implications for the oxidation, lifetime, and perception of chemicals indoors and, ultimately, human health.

Measurements of Hydroxyl Radical Concentrations during Indoor Cooking Events: Evidence of an Unmeasured Photolytic Source of Radicals

“…During this time, the bulk of the activity also moved from the kitchen into the living room, nearer to the OH instrument. A recent study has shown that under low O 3 conditions, the surfaces of skin and clothing can act as a radical sink . It is possible that this introduced new heterogeneity in VOC concentrations and radical sinks resulting in a greater loss of OH or any radical precursors nearer the instrument than can be accounted for by the measured VOC concentrations sampled from the kitchen.…”

“…A recent study has shown that under low O 3 conditions, the surfaces of skin and clothing can act as a radical sink. 41 It is possible that this introduced new heterogeneity in VOC concentrations and radical sinks resulting in a greater loss of OH or any radical precursors nearer the instrument than can be accounted for by the measured VOC concentrations sampled from the kitchen. After people left the house at 17:00, OH returned to its previous concentration of about 6 × 10 6 molecules/cm 3 likely due to the removal of radical sinks adjacent to the instruments.…”

Quantifying the impact of relative humidity on human exposure to gas phase squalene ozonolysis products

“…36,79 Furthermore, a recent study has shown that elevated OH concentrations may form from the ozonolysis of compounds emitted by people. 80 The consequence of these reactions and any potential relative humidity dependence should be investigated by further developing models.…”

The “atmosphere” of the human body

“…The "atmosphere" of the human body A human-occupied indoor space shares many similarities with Earth and its atmosphere Coralie Schoemaecker 1 and Nicola Carslaw 2 1 Université de Lille, CNRS, UMR 8522-PC2A-Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France 2 Department of Environment and Geography, University of York, York, UK.…”

“…Less is known about these re-actions on a smaller scale, such as how hu-man-emitted chemicals interact with indoor air. Zannoni et al (2) studied how the human body generates •OH, which may have implications for models such as those used for determining indoor air quality. Understanding the chemistry of indoor air is important as many people spend more time indoors than outdoors, and indoor air quality is a public health concern.…”