Development and evaluation of a particle-bound reactive oxygen species generator

Identifying the most important sources and variability of source impact for particulate matter is essential to assessing their health impacts. A central hypothetical mechanism of how particles affect human health involves the generation of reactive oxygen radicals at target sites in situ. These could be generated via activation of cells by cell–particle interactions and by oxidative species present in particulate matter. However, prior studies have shown that there are reactive oxygen species (ROS) associated with ambient respirable particles. In order to assess the health effects of particle-bound oxidative species, a generator was developed to produce ROS-bearing model particles and deliver known, reproducible, and stable exposures to these model particles that could be used in toxicological studies. The generator was found to be capable of providing a stable throughput of these particles with an average ROS generation capability of 6.5 nmol of equivalent H2O2/m3H2O2/m3 of (aerosol+ozone)(aerosol+ozone) flow sampled. The development, characterization, and evaluation of the ROS-bearing particle generator is described.