Chemical Characterization of Indoor Air Pollutants: Implications to Consumer and Occupational Health
Creators: Guo, Xinyang
Publisher: name: University of Alberta Library
Year: 2024

<p>Humans living in the contemporary societies find the majority of their time spent indoors, promoting awareness regarding indoor air quality over the past decades. The indoor environment has gained significant complicity due to an increasing variety of<br>
inhalable products consumed in our daily lives. Many indoor chemistry processes have not been fully characterized; hence chemical pollutants produced from these processes are under-discovered. In particular, our exposure to air pollutants in residential and occupational settings could be vastly different from the typical indoor environment. This is because chemicals involved in these scenarios are product- and occupation-dependent. One can receive immense exposure to specific chemicals that are uncommon in normal settings. However, very limited research has been done to investigate chemical pollutants involved in consumer and occupational settings. At the same time, it is always challenging to conduct representative studies on this topic due to the high diversity of indoor environments. Hence, fundamental studies on indoor chemistry processes are needed to address this problem. </p>

<p>The goal of this thesis is to provide chemical insight into possible indoor pollutants and to reveal chemical processes behind the scenes. In Chapter 2, I demonstrated the impact on indoor air quality from the use of artificial fog machines. I reported a significant production of chemically rich ultrafine particulate matter generated from artificial fog. In addition, I discovered an accumulation of toxic carbonyl compounds in artificial fog, including formaldehyde and glycolaldehyde, using the 2,4-dinitrophenyl hydrazine derivatization method. I reported that the oxidative degradation of glycols in the fog juice during storage could give rise to carbonyl formation. Finally, I proposed that autoxidation was likely the primary process during the degradation of glycols.</p>

<p>In Chapter 3, I implemented a systematic investigation of the oxidation of glycols according to discoveries made in Chapter 2. I investigated the oxidative degradation of common glycols, including triethylene glycol, diethylene glycol, propylene glycol, glycerol, and commercial e-cigarette juice. All glycols could accumulate carbonyl products during prolonged storage, with triethylene glycol exhibiting the most rapid formation of carbonyls. I further determined time-resolved total peroxide concentrations in different glycols using iodometry, this result is strong evidence to support the autoxidation hypothesis. In addition, I evaluated parameters that could affect the formation rate of glycols, in terms of water mixing ratio, air exposure, and the addition of antioxidants. This project has emphasized that proper storage protocols on glycol-containing consumer products are required to mitigate human exposure to toxic carbonyls.</p>

<p>In Chapter 4, I applied the derivatization with p-toluenesulfonyl chloride to determine oxidation products from nicotine, during the storage of nicotine-containing e-cigarette juice. I discovered numerous amine-containing alkaloid compounds in aged e-cigarette juice, including nornicotine and an amino-peroxide compound. I further confirmed that the formation of these compounds includes radical-initiated oxidation by performing an artificial photooxidation experiment. Finally, I monitored the formation of alkaloid compounds from a set of fresh commercial e-cigarette juices under typical storage conditions and discovered a rapid formation of these alkaloid compounds within a week. Therefore, e-cigarette consumers should be aware of the degradation of their e-cigarette juice to avoid exposure to numerous unknown alkaloids.</p>

<p>In Chapter 5, I performed a field project to reveal the indoor chemistry of a commercial poultry facility. With the aid of the p-toluenesulfonyl chloride derivatization used in Chapter 4, I characterized numerous airborne nitrogenous compounds in the facility and discovered an interesting chemical partition among litter, air, and dust. The detection of these nitrogenous chemicals has addressed the potential source of ammonia pollution, which is a known, persistent environmental problem in animal husbandry industries. In addition, we found a strong correlation among particles, chemicals, and animal activities. An interesting diurnal variation of particles and chemicals in the farm was also discovered. This study have strong implications for animal productivity and the occupational health of farmers.</p>

<p>Overall, this thesis has reported novel observations for the study of chemical processes involved in the indoor environment. Information provided by this thesis can fundamentally explain the formation of indoor air pollutants under certain consumer and occupational settings. Ultimately, further clinical studies can use results from this thesis to address potential adverse health effects due to the consumption of contaminated inhalable products and/or exposure to indoor environments polluted by such products.</p>