Surface and Bulk chemistry relevant to atmospheric aerosol systems that impact the air quality, climate and health

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The overall impact of atmospheric aerosol systems on air quality, climate and human and ecological health remains uncertain due to their highly complex physicochemical properties. New policies and models used by regulators at the national and international levels need to be based on experimental data that account for aerosol aging. The term `aging' refers to the processes that change aerosol properties in the atmosphere, which can be as long as two weeks. These processes can take place at the surface of the particles/droplets or within the condensed phase. The extent and rates of these reactions are influenced by water content and chemical composition. The reactivity of metals and organics in these systems produce reactive oxygen species that can change the optical properties, chemical composition, and hence, ice/cloud nucleation efficiency. Also, aerosol particles can transmit airborne diseases and cause damage to the respiratory organs upon inhalation. Guided by recent results from field measurements and needs for improving aerosol representation in atmospheric chemistry models, this renewal application for my NSERC DG will support lab experiments and field measurements that have hypothesis- and discovery-based aspects that address current gaps in knowledge pertaining to the interplay of aerosol physical properties, chemical reactivity, and biological content. Our long term objective is to improve the parameterization of multicomponent aerosol systems in climate and pollutant transport models and influence climate action plans at the city and regional levels through carefully-designed experiments and strategically-planned field campaigns. The short term objectives fall into three main themes: (HYPOTHESIS-BASED THEME 1) Efficiency of iron dissolution and metal-catalyzed new particle formation in model two-phase aerosol systems, (DISCOVERY-BASED THEME 2) Size-dependent collection and analysis of aerosol particles in Kitchener, ON, and (DISCOVERY-BASED THEME 3) Chemistry of microdroplets from fine particulate matter (PM) extracts. Results will be significant and impactful in the field of atmospheric aerosol chemistry as they will provide mechanistic details on transition metal-containing multicomponent aerosol reactivity and physical properties currently missing in models. The results will also inform local city, regional governments, and school boards of chemical and biological activity of fine PM near and inside schools to influence new initiatives on outdoor activity programs, efficiency of ventilation systems in schools, curriculum and living lab devolvement for school kids aimed at increasing awareness of air quality and health impacts of fine PM.