Exhaust back pressure is not an issue at all on diesels because they all run big turbos.
As for your later point...I very much concur. I started masking (n95) during the pandemic, and haven't stopped. I have a... large number of health issues including several respiratory ones. Exhaust in general really is nasty stuff. I live in pretty quiet smallish (100k) town, and it can be bad enough around here with all the pollen, but I wasnt recently on a whirlwind trip through the north east that saw me visit the dense urban cores of DC, Philly, Manhattan, and Boston. The difference in odor on the occasions I'd take my mask off on the sidewalk were kinda shocking as someone not used to it.
Out of curiosity do you live in the Great Lakes basin? I moved from Indiana to the West Coast, and I am always shocked at how bad the air quality is when I go back, even in rural areas. During wild fire season I monitor AQI, and when I zoom out I always see that Indiana is just as bad as the smokiest days on the West Coast.
Something about the large, hardly noticeable depression traps bad air at a regional level. I wouldn’t move back for a myriad of reasons, but everyone is always surprised when I list air quality as one.
> Exhaust back pressure is not an issue at all on diesels because they all run big turbos.
Not sure what you're arguing here. Isn't it quite obvious that resistance in the exhaust system means that the engine has to do more work to push the exhaust gases out; work that otherwise could be used to turn the crankshaft. Now of course a lot of that extra energy is wasted in any case, particularly if there's nothing like a turbocharger to make use of it.
As for your later point...I very much concur. I started masking (n95) during the pandemic, and haven't stopped. I have a... large number of health issues including several respiratory ones. Exhaust in general really is nasty stuff. I live in pretty quiet smallish (100k) town, and it can be bad enough around here with all the pollen, but I wasnt recently on a whirlwind trip through the north east that saw me visit the dense urban cores of DC, Philly, Manhattan, and Boston. The difference in odor on the occasions I'd take my mask off on the sidewalk were kinda shocking as someone not used to it.