REACTIVE OXYGEN SPECIES IN AMBIENT AEROSOLS

摘要

Reactive oxygen species, a term used to describe collectively the oxygen-containing reactive species such as free radicals and superoxides, originate from various sources and have different lifetimes in the atmosphere. For instance, particles in diesel emissions contain high concentrations of ROS, such as superoxide anions and highly reactive hydroxyl radicals (Sagai et al., 1993). Photochemical reactions in polluted air also produce ROS, such as H2O2, hydroxyl radical, and other reactive chemical species. ROS can exist in both gas and particulate phases. In the particulate phase, the ROS are mainly in the fine particle mode. Fine particles have a relatively high rate of deposition in the lower respiratory tract and, as a result, toxicants in these particles can be efficiently transferred to the lungs. This presentation will describe measurements of hydrogen peroxide and other reactive oxygen species in various size fractions of the Taipei aerosols. The factors affecting the concentration of ROS in particles will also be discussed.