Masters Thesis

The chemical changes of third-hand smoke in reactions with ozone, hydroxyl radicals and nitrogen dioxide

Second-hand tobacco smoke (SHS) consists of hundreds of toxins. Many of these toxins such as 1,3-Butadiene and Ethylene oxide are known to cause cancer. The health effects of SHS are well known; however, the effects of environmentally-aged sidestream smoke or remnants of SHS, which is termed third-hand smoke (THS) is an emerging area of interest that has yet to be fully evaluated. The organic compounds in THS can react with ozone and related atmospheric oxidants to form additional carcinogenic compounds. These hazardous carcinogens build up over time and can be inhaled, therefore potentially posing a greater risk than SHS alone. The purpose of this thesis is to determine the potential chemical markers that indicate the changes of THS when exposed to three atmospheric oxidants: ozone, hydroxyl (OH) radicals, and nitrogen dioxide (NO2). Samples of THS were generated by using the Teague-Enterprise 2 smoking machine. Samples of smoke particles and vapor were collected on Teflon filters and in Teflon bags, respectively. Selected samples were either exposed to ozone/oxygen mixtures generated by the commercial ozone generator, OH radical, or NO2. Changes in chemical composition were evaluated by using gas chromatography-mass spectrometry and proton- transfer-reaction mass spectrometry. The results indicated a significant increase in toxins such as formaldehyde when THS was reacting with ozone and an increase in acetaldehyde when reacting to hydroxyl radicals. These findings have an implication for health impacts such as the risk for cardiovascular disease, cancer, and heart disease. There were inconclusive results for NO2-treated THS.