> They DO NOT reduce emission of particulate matter. Well not exactly. Depending on the type of filter the collect particulate matter and when they have collec

> They DO NOT reduce emission of particulate matter. Well not exactly. Depending on the type of filter the collect particulate matter and when they have collected enough to need a regeneration process they use passive heat (because driving on the highway make the filter heat up) or the actively heat the filter to then burn up most of this particulate matter. It is like self cleaning ovens that get hot enough to nearly burn all what is in them. So about 5% of the particulate matter isn't being able to be filtered out that way. Either because the particles are to small for the filter to initially block them. Or because the regeneration leaves them as a kind of residue. Also not everything can be "burned up" so that these filters have a limited lifetime of somewhat below 200.000 kilometers. I know, I glossed over lot's of important details, but at least be assured, that not all filtered particulate matter is being released in the countryside.