The effect was studied of a CDPF(catalyzed diesel particulate filter) on the unregulated emissions of a diesel bus in the transit cycle: volatile organic compounds(VOCs)

particulate carbon components

particulate polycyclic aromatic hydrocarbons(PAHs) and their toxicity. The results show that the VOCs are reduced by 57.6% with the CDPF

the total carbon(TC) is reduced by 70.4%

and the PAHs are reduced by up to 91.1%. The CDPF shows higher reduction in low-ring PAHs

such as 3-ring and 4-ring PAHs

while it presents lower influence on higher ring PAHs. The CDPF can obviously reduce the toxicity equivalent of different benzene rings of PAHs

and it has no obvious effect on the ratio of the toxicity equivalent of different benzene rings of PAHs.