BITS Faculty Publications
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Item Numerical modeling of volatile organic compound emissions from ozone reactions with human-worn clothing in an aircraft cabin(Taylor & Francis, 2014-11) Rai, Aakash ChandVolatile organic compounds are indoor air pollutants with many adverse health effects for humans. Ozone reactions with human surfaces (skin, hair, and clothing) are an important source of volatile organic compounds in the indoor air, especially in aircraft cabins because of their typically high ozone concentrations and occupant densities. Therefore, it is important to study the ozone-initiated volatile organic compound emissions from ozone reactions with passengers in an aircraft cabin and assess their resulting exposure. This investigation developed empirical models for computing the emissions of several major volatile organic compounds, including acetone, 4-oxopentanal, nonanal, and decanal, from ozone reactions with human-worn clothing. The empirical models were used to compute the contributions of human surfaces to these volatile organic compounds in an aircraft cabin mockup under different environmental conditions. The computed results were then compared with the corresponding experimental data obtained in the mockup. The models can provide rough estimates of ozone-initiated volatile organic compound concentrations. The empirical models were integrated into a computational fluid dynamics analysis, and the results showed that the levels of ozone-initiated volatile organic compounds were significantly enhanced in the breathing zones of the passengers. Therefore, to accurately assess passenger exposure to volatile organic compounds, their concentrations in the breathing zones should be used.Item Numerical modeling of particle generation from ozone reactions with human-worn clothing in indoor environments(Elsevier, 2015-02) Rai, Aakash ChandOzone-terpene reactions are important sources of indoor ultrafine particles (UFPs), a potential health hazard for human beings. Humans themselves act as possible sites for ozone-initiated particle generation through reactions with squalene (a terpene) that is present in their skin, hair, and clothing. This investigation developed a numerical model to probe particle generation from ozone reactions with clothing worn by humans. The model was based on particle generation measured in an environmental chamber as well as physical formulations of particle nucleation, condensational growth, and deposition. In five out of the six test cases, the model was able to predict particle size distributions reasonably well. The failure in the remaining case demonstrated the fundamental limitations of nucleation models. The model that was developed was used to predict particle generation under various building and airliner cabin conditions. These predictions indicate that ozone reactions with human-worn clothing could be an important source of UFPs in densely occupied classrooms and airliner cabins. Those reactions could account for about 40% of the total UFPs measured on a Boeing 737-700 flight. The model predictions at this stage are indicative and should be improved further.