Vacuum Cleaners Discussions

Okay, so apparently with this machine (EL7024A), the HEPA cartridge serves as the pre-filter, as it is placed in front of the motor, and not in the exhaust. The air leaves the machine through a non-removable mesh grille that wraps around the back of the canister. Question: is there any form of filtration that will contain the carbon emissions? I was also considering the possibility that the Oxygen 3 uses a brushless motor, hence the lack of a visible exhaust filter. Also, how would you rate the Oxygen 3 against the Oxygen? Thanks, Keith