A summary of the three papers is here: http://media.utoronto.ca/media-releases/traffic-emissions-ma... They just set up some measurement tools by the side of the road and waited for cars to drive by. They didn't check the "tune" of each car or test whether any kind of tune-up would change anything.
So that's a pretty significant conclusion to draw without any hard data on the "tuned-ness" of a car.
I wonder how much could be attributed to old cars instead. That's something that would be easily measured by identifying the cars. But that may open a different can of worms if they determine people with the oldest cars are the biggest polluters* because it could be seen as an attack on the poor.
* Odds are the old cars are the biggest polluters.. less efficient to start with, more likely to be out of tune, more worn parts, etc. But I don't have any data to state that as a conclusion.
Thanks for your interest in our work! (Lead author on the ultrafine particle mapping paper).
The SOCAAR facility has operated at this roadside location since 2006 and is one of the largest air quality research lab in Canada.
Over the years, we have routinely seen peaks in CO2 as vehicles pass our monitoring station. However, when some vehicles pass, we also see NOx, black carbon or ultrafine particle peak(s).
While we have video footage of the road, it can be extremely difficult to link the measurements to a single passing vehicle. Identifying these vehicles and why their emissions are different from the rest of the vehicle fleet is where the research our heading.
I wonder how much could be attributed to old cars instead. That's something that would be easily measured by identifying the cars. But that may open a different can of worms if they determine people with the oldest cars are the biggest polluters* because it could be seen as an attack on the poor.
* Odds are the old cars are the biggest polluters.. less efficient to start with, more likely to be out of tune, more worn parts, etc. But I don't have any data to state that as a conclusion.