Browsing by Author "Xiong, Ying"

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    Optimization of A Volatile Organic Compound (VOC) Control Strategy in Eight Cities of Western Canada by Multi-Effects Evaluation
    (2021-05-12) Xiong, Ying; Du, Ke; Olfert, Jason S; Osthoff, Hans D; Morton, Christopher; Li Simon;
    Volatile organic compounds (VOCs) in large urban environments are of great interest to the public and research communities, as they can contribute to ground-level ozone (O3) and secondary organic aerosol (SOA) formation and promote adverse health effects. To this end, this thesis investigates the spatiotemporal variations, O3 and SOA formation potentials (FP), and health risks of VOCs in western Canada based on a six-year (2013-2018) routinely monitored data collected by Environment and Climate Change Canada. Overall, the concentrations of VOCs showed significant spatial and temporal differences across western Canada. Industrial and traffic sites exhibited much higher concentrations than urban centers and background sites. Using a newly developed tiered source identification strategy, seven VOC sources were identified in western Canada. The OFP and SOAFP of the measured VOCs were then assessed; the dominant VOC sources (i.e., industrial-related emissions and vehicle exhausts) accounted for 71.8% and 77.0% of OFP and SOAFP, respectively. This finding suggests the need to control VOC emissions from these sources once O3 or fine particle exceeds their air quality standards. Moreover, regionally transported VOCs have greatly increased the VOC level and secondary pollutant formation in western Canada. To effectively alleviate secondary pollution problems, the implementation of joint pollution control measures has been suggested by the local authorities. Although chronic non-cancer risks associated with exposure to hazardous VOCs were essentially negligible, the integrated inhalation cancer risk (ICR) was estimated at 7.7×10-5 in western Canada, which indicates a 100% likelihood of exceeding the Health Canada acceptable risk level. The probability of developing cancer due to inhalation of hazardous VOCs increased 4-fold on polluted days relative to clean air days. From a risk management perspective, the concentrations of hazardous VOCs and associated sources need to undergo reductions of 78.3-91.0% and 3.0–69.2%, respectively. Taken together, results of multi-effects evaluation suggest that stringent control of VOCs sources, particularly traffic sources and industrial-related emissions, is an urgent priority in western Canada. The tiered source identification and multi-effects evaluation methodology developed in this thesis is a promising tool for optimizing VOC control strategies, which can be applied toward improved management of hazardous pollutants.