Redox characteristics of size-segregated PM from different public transport microenvironments in Hong Kong

Abstract

Exposure to airborne particulate matter (PM) has been associated with various adverse health effects, including severe pulmonary and cardiovascular effects. PM consists of different chemical components that vary with microenvironments in urban areas and pose challenges to assess personal exposure. In Hong Kong, more than 70% of the population commutes through roadway and railway public transport. This study aims to determine the oxidative potential and role of aerosol carbon and water-soluble metals in fine (d p < 2.5 μm) and coarse PM (2.5 <d p 0.70) and organic and elemental carbon (OCEC) (R > 0.85) for UG and AG routes. In addition, PM from UG and AG routes generated 3–4-fold (in PM2.5) and 40–50-fold (in coarse PM) less ROS compared to urban sites, suggesting PM in these public transport microenvironments may not be intrinsically redox active than in urban ambient, and water solubility of metals seems to have played an important role in it.