Chemical and toxicological characteristics and historical trends of size-fractioned particulate matter from traffic-related emissions in Los Angeles

2018-08-15Air pollution is a major environmental risk to health. A 2013 assessment by World Health Organization (WHO) concluded that outdoor air pollution is carcinogenic to humans, with the particulate matter (PM) component of air pollution most closely associated with increased cancer incidence, especially lung cancer. In Global Burden of Disease 2013 report, air pollution accounts for 5.5 million deaths placing air pollution as the fifth important risk factor disease burden globally. This mortality is due to exposure to small particulate matter of 2.5 microns or less in diameter (PM₂.₅), which cause cardiovascular and respiratory disease, and cancers. Despite substantial epidemiological evidence linking PM pollution with adverse health effects in humans, inherent uncertainties remain regarding the responsible physical and chemical properties of the ambient aerosols for posing the greatest health risks, and what pathophysiological mechanisms are accountable and what air quality regulation should be adopted to curtail these health risks. Furthermore, reducing outdoor air pollution also reduces emissions of CO₂ and short-lived climate pollutants such as black carbon particles and methane, thus contributing to the near- and long-term mitigation of climate change. ❧ My motivation is therefore addressing these issues using innovative methodologies coupled with advanced mathematical and statistical modeling techniques to identify and quantify major sources of air pollution and define their contribution to the overall PM toxicity. This information is indeed essential in promulgation of control strategies to tackle pollution sources in order to minimize population exposure to hazardous air pollutants. My research provides insight on combustion-generated particulate matters and how they compare to other sources of particles in Los Angeles (LA) basin in terms of posing greatest health risks along with investigating the effectiveness of the implemented stringent regulations in the LA basin on vehicular emissions since 2007. I have provided detailed and robust experimental and modeling methodologies in understanding the chemical composition and oxidative potential (i.e. the ability of PM to cause oxidative stress and inflammation in cells) of these particles. This information is vital for scientists in addressing the associations between pollutant sources and physico-chemical characteristics of the produced particles in ambient air as well as the impact of engine and fuel reformulations on the generated particles thereby making it possible to further implement more effective source-specific regulations. It is important to note that since 2004, the South Coast Air Basin in California has been designated as a non-attainment area which makes these efforts more important