Are diesel vehicle emissions in the Salt Lake Valley messing with our heads?
Almost half of the pollution trapped during Utah’s notorious inversions comes from trains, planes and automobiles. And while there are some legislative proposals to try to cut emissions, it’s not clear how much support they’ll have from lawmakers.
Even though Salt Lake City lags behind Western peers like Las Vegas or Denver when it comes to traffic, the metro sits at the confluence of two major interstates. That’s a lot of semi trucks rolling through, along with freight rails, an international airport and a booming population. There’s also the ongoing plan to establish a multi-modal cargo hub with the Utah Inland Port.
In short, there’s no shortage of diesel-powered vehicle traffic around town. The new wrinkle is research out of Canada that suggests traffic pollution is changing how our brains function.
Christopher Carlsten, director of the University of British Columbia’s Air Pollution Exposure Lab in Vancouver, said they exposed humans to diesel exhaust and then conducted MRIs of their brains. They found what they described as “altered brain network connectivity acutely induced by air pollution.”
“The brain is a complex space, but of course, the different parts of the brain need to communicate,” he said. “We can see this network or this set of connections, and we can see that after diesel exhaust, that network was different.”
Carlsten added that “the levels of traffic pollution used in their study are not far off levels in the Salt Lake Valley.”
This interview has been edited for length and clarity.
Pamela McCall: Why did you choose diesel for your study?
Christopher Carlsten: For major shipping and commercial traffic it’s still the dominant fuel. And those bigger vehicles — trucks, trains, ships, etc. — those are the ones that emit the majority of diesel exhaust, in particular, because the regulations on those engines are not as strict as they are for typical day-to-day consumer vehicles like you and I drive.
PM: What brain functions were impacted the most by diesel exhaust?
CC: We have some ideas based on some data that we have not yet published, and the one that stands out is what's called “reaction time.” This is a common test used in research of alcohol and other substances of concern. In our preliminary data, that reaction time is slower in those individuals after the exposure to diesel exhaust.
PM: Based on your research, what might be happening to our brains as we idle in our cars or simply take a walk?
CC: I believe that the levels that are seen in Utah, and other more polluted regions of the country, may very well mean they are experiencing some of the harms that we're seeing. And I think that goes back to the epidemiology literature in that levels — like real levels in Utah — are being seen over years to affect cognition in a number of studies.
PM: How worried should Utahns be about brain function when it relates to air pollution from traffic?
CC: One of the points that we like to make in our lab about this particular area of work is that it's just one layer amongst many about the harms of air pollution. So, I think they should be as worried as they were already because of what we know about air pollution and heart and lung disease. And so you might ask, well, then why does this matter? I think it matters because in public health, the issue of cognition in the aging society — we know that people are living longer and longer and that’s a bigger concern, a bigger burden on the system.
PM: Where do you think places like Utah are headed when it comes to brain health if we don't find a solution to air pollution?
CC: No one wants a loved one to be battling these cognitive challenges. To put money into renewable energy, etc., that we know at a systems level is probably, if not the primary, one of the most substantial ways to turn this around — I just think that is kind of a no brainer. I guess a bad pun in the context of this debate. But we have to do these high level government [policies] — whether you like it or not, it’s not going to happen on its own. So I support those kinds of efforts, particularly in the renewable energy space.