Prof. Chan's major research interests include aerosol chemistry and air pollution. He focuses on source identification and chemical and physical characterization of atmospheric particulate matter (PM) and understanding the chemical pathways in the formation of secondary inorganic and organic PM. He uses a suite of aerosol instrumentation techniques, especially aerosol mass spectroscopy and single particle Raman spectroscopy, to provide in-situ characterization of PM, supplemented by offline characterization of filter samples. He was the Project Manager of the HKUST Air Quality Research Supersite for real-time characterization of ambient PM in Hong Kong 2009 to 2015. More recently, he has worked on primary emissions and the formation of secondary organic aerosols of cooking, traffic, biomass burning, and ship emissions, reactive uptake of organics, and heterogeneous reactions in the formation of secondary aerosols. His current research includes atmospheric aging of PM due photochemistry of particulate nitrate photolysis, photosensitization reactions, and chlorine chemistry. In addition, he aims to establish a real-time PM characterization network for understanding the PM chemical and physical characteristics of PM relevant to health and climate impacts to aid policymakers in making informed decisions on improving air quality and mitigating climate change impacts.