AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Ozone-initiated Oxidation of Indoor Organics and its Potential Health Impact
Guang Zeng, Hai Pham, Vu Luong Duc, YONG LIU, University of Colorado Denver
Abstract Number: 56 Working Group: Indoor Aerosols
Abstract Indoor air pollution has emerged as major environmental risks and health concern. Many pervasive household chemicals such as detergents and pesticides can adhere to indoor surfaces for extended periods after application and undergo heterogeneous interaction with ozone, contributing to poor indoor air quality. Reaction mechanisms and products of interfacial ozone chemistry are often highly complex and not well understood. This could become even more complicated considering variations of temperature and relativity humidity indoors. In this work, we employed an environmental cell coupled to an ATR-IR spectrometer to investigate ozone interfacial chemistry with neem oil and squalene and roles of indoor temperature and relativity humidity. Neem oil is a major component for houseplant pesticide and squalene is a main composition of skin oil, both of which have been found indoors. In our study, reactive uptake of ozone and reaction products in both gas and condensed phases were determined using ATR-IR, GC-MS and LC-ToF-MS. In addition, changes in redox activity were evaluated by DTT chemical assay. Results show the heterogeneous oxidation reactions proceed via ozone addition to unsaturated C=C bond in the organics to form primary ozonides, followed by carbonyl oxide formation. This can further react with carboxylic group, if available, to yield highly oxygenated peroxide compounds. Overall ozone reactive uptake is nearly independent of indoor temperature and relativity humidity. In contrast, temperature and relativity humidity play more important roles in affecting reaction product formation. Results also reveal that redox activity of organics are significantly enhanced upon ozone exposure due to the formation of oxygenated species, and such enhancement is nearly linearly dependent on the exposure time.