Health effects of partially oxidized soot

摘要

Control technologies for diesel particulate emission such as continuously regenerating particle traps and oxidative catalysts oxidize soot particles to either reduce or remove them from exhaust. However, this gives rise to the possibility of exposure to partially oxidized soot with a modified size and surface composition, which has implications on diesel exhaust associated health effects. To investigate the health effects of partially oxidized soot we used a downward flow non-premixed methane air flame as a stable source of soot. A sample from the post flame region was mixed with ozone in a reaction chamber with a 15 minute residence time to partially oxidize the soot surface. The partially oxidized soot is characterized by measurement of the particle size distribution with a TSI scanning mobility particle sizer and particle morphology is assessed with transmission electron microscopy. Particles are collected on a filter, resuspended in growth medium, and exposed to human bronchial lung cells; cell viability is measured with an XTT assay. Oxidized soot resulted in a greater toxicity to the cells when compared to unoxidized soot.