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Two-year study in Canada finds large trucks disproportionately contribute to higher levels of black carbon pollution

A two-year study led by researchers at the University of Toronto has found large trucks to be the greatest contributors to black carbon emissions close to major roadways. The study is published in the ACS journal Environmental Science & Technology.

The comprehensive study led by U of T Professor Greg Evans and collaborators at Environment and Climate Change Canada, and the Ontario Ministry of the Environment, Conservation and Parks, as well as the Metro Vancouver Regional District involved measuring vehicle emissions near roads in Vancouver and Toronto, including the 401, North America’s busiest stretch of highway.

The difference between emission levels across the sites was more correlated with the number of large trucks on the road rather than number of cars.

Researchers found that air pollution levels right beside a major trucking route within a city were close to levels seen beside Highway 401, despite the road carrying less than one-tenth of the vehicle traffic.

This was in part due to differences in wind and proximity to the road but, surprisingly, the number of vehicles didn’t make that much of a difference.

—Greg Evans

The data also revealed a significant drop in emissions on the 401 on the weekends, when personal vehicle traffic is still very high, but the volume of large truck traffic is low.

Research consistently links traffic emissions to negative effects on both the environment and human health. Black carbon—commonly called soot—is a marker for exposure to diesel exhaust which is known to have negative health effects.

Evans points out that modern trucks have made large improvements in their emissions—it’s the older diesel trucks that are the real culprits.

The study will be part of a larger report in December that will stress the importance of implementing long-term monitoring of traffic related air pollution in Canada, and indicating that targeting high-emitting vehicles such as old trucks can provide a path towards improving near-road air quality.


  • Jonathan M. Wang, Cheol-Heon Jeong, Nathan Hilker, Kerolyn K. Shairsingh, Robert M. Healy, Uwayemi Sofowote, Jerzy Debosz, Yushan Su, Michiyo McGaughey, Geoff Doerksen, Tony Munoz, Luc White, Dennis Herod, and Greg J. Evans (2018) “Near-Road Air Pollutant Measurements: Accounting for Inter-Site Variability Using Emission Factors” Environmental Science & Technology 52 (16), 9495-9504 doi: 10.1021/acs.est.8b01914



This raises the question:  how do fuels like DME and OMEs, which have no carbon-carbon bonds and burn almost without soot, change the health impacts of diesel exhaust?


Newer trucks have particle filters, so this is not a problem on those trucks. It seems easy to forget such simple facts. The tailpipe PM/PN level from new diesel trucks can be lower than from vehicles using so-called "clean fuels". Oftentimes, the level is also lower than in ambient air in densely populated cities.


I think most people figure this was the case.
It comes down to lowest cost while ignoring externalities.


Electrified trucks/buses (with batteries + FCs) will solve this problem at a competitive (total) cost by 2030 or so.

Meanwhile, improved exhaust filters on all old/new diesel trucks/buse/LVs should be compulsory. Builders/owners/users should be given a 5 year grace period to fully comply.


I would like to see a positive approach to replacing diesels with Trump offering incentives to trucking companies going all electric or hydrogen...Ha! Fat Chance! But, if we were led by a more progressive group of politicians, that would be a possibility.


The Energy Department under Obama did a lot of good work.
Tesla got their loan from them and paid it back ahead of schedule.

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