Talking Headways Podcast: Community Severance by Road
This week on Talking Headways, Jaime Benevides and Marianthi-Anna Kioumourtzoglou of Brown University discuss their new paper showing how community severance by road infrastructure and traffic has led to more mental health-related hospital visits in New York City.
We talk about the role of roads cutting people off from social connections and how impacts of roads on mental health were separated out from air quality.
There are three ways of following the conversation: The audio player embedded below; a full transcript generated by artificial intelligence; and further down this page, a partial, human-edited transcript.
Jeff Wood: I think it’s so interesting that you all kind of lasered in on that specific idea of, like, traffic severance or transportation severance because you mentioned, the research and the findings are independent of the traffic-related air pollution, which has been shown to have impacts on things like Alzheimer’s and dementia and other brain health things.
I wonder what made you look past the air quality impacts and laser in on this specific thing that was the traffic and the connections that people are severed from.
Jamie Benavides: On one side, we have scientific evidence on space used in a way that benefits social cohesion and also exercise, and also that this green space benefits mental health as well. You know, like things like parks or green space. But we don’t have awareness or understanding of what happens on the other side of the range of how we use the space in the city, right?
Like, there is a lack of understanding of if we occupy all that open space with, again, huge volumes moving very fast of these machines, is that good or bad for our mental health? So yeah, it was, as Marianthi said, from my perspective at least, looking beyond air pollution and imagining if the city will have still the same levels of noise and air pollution but had another use of space, would it be more healthy or not?
Marianthi-Anna Kioumourtzoglou: Exactly. I think it was similar for me. I’ve been working on quantifying air pollution effects on adverse health outcomes, including depression, Alzheimer’s, all of the above. And I started getting a little bit antsy and frustrated that, okay, we’ve characterized this impact, but two things: One, and so what?
We don’t necessarily see the regulations following in the rate that I would have wanted to protect human health. And so how can we then figure out modifiable, intervenable pathways so communities can protect their residents? And the urban form is one such intervenable pathway. That’s part of it.
The other big part of it is, okay, as we are electrifying our fleet, I will keep saying that the cons of car dependency are not only noise and air pollution, it’s lack of physical activity, it’s lack of social cohesion and in-person social cohesion.
It’s very interesting. We were talking with a colleague of ours who’s from Texas, and Jaime and I both grew up in Europe in very dense, not car-oriented societies, or not so much at least, and our colleague from Texas was saying, “But it’s so easy. I get into my car, in 10 minutes I can go and see my brother. What are you talking about isolation?”
And so that’s a disconnect there because, okay, you are more connected to a family member, but you’re not necessarily connected to our neighbors. Neither of us lives in New York anymore, but we used to live [there] and I did not know any of my neighbors in the buildings I was living in. Maybe that’s on me. But, I think that’s a general trend, right? We don’t know our immediate community, and there’s so much work on the benefits of both physical activity. Even if I have to walk for five minutes to go get a bus, that’s five minutes more than, you know, garage door and driving, right, door to door.
If you have the plaza, as Jaime said, you go there, you interact with the people more. People check in on you. So that’s beyond just removing the air pollution from the equation. There are so many other benefits from reshaping our immediate environment outside of the house to help us build healthier lives that I think we haven’t looked as much, or at least in environmental epidemiology, other fields probably have, but as much into.
Jeff Wood: There was an interesting part of this as well, is like how you split out the air quality impact, which was like looking at black carbon data. And I’m curious about that data, like what that is and how that impacted the ability to split out the traffic impacts versus the air quality impacts.
Marianthi-Anna Kioumourtzoglou: So when we started talking, when Jaime came up with the idea of looking at community severance and mental health and came to me and said, “I want to do this,” and we had the hospitalization data for mental health, my main concern was exactly because of the very big literature on the air pollution impacts on mental health.
My concern was, okay, but if we publish this as is, everybody will just say, “Okay, then it’s just all through air pollution.” Obviously, what you’re capturing is air pollution, so we wanted to see, is it all air pollution, or if we could somehow block the air pollution effect, do we still see impacts? So we used black carbon predictions. Black carbon is a combustion byproduct that is usually associated with traffic in urban cores. And New York City has an amazing program, NYCAS, that has multiple rotating monitoring sites. The number of monitoring sites varies from year. I think it goes from 60-something to 100-something. But they rotate these, and they then integrate these with land use data and traffic data and all other kinds of data to build these pretty high resolution, 300 meter predicted annual surfaces for different pollutants. Black carbon is one of them. And so we then included black carbon in our model, hoping to block the path from community severance to mental health from air pollution. So we said, okay, if we compare now two communities to zip code levels that have the same air pollution, but different community severance, do we see differences in mental health outcomes?
And indeed, what we saw was, as expected, once we added air pollution into the model, our effect estimates attenuated a little bit, became somewhat smaller in magnitude. But importantly, they didn’t completely disappear, which does mean that, yes, air pollution explains some of the effects that we saw, but not everything.
So community severance doesn’t solely act through air pollution to induce the increased rates in mental health hospitalizations that we saw. And I keep saying mental health hospitalizations. We examined multiple causes, but our biggest finding was on schizophrenia hospitalizations, actually.
So it’s not all of it through air pollution, but there are some other pathways, we don’t know exactly how yet, that’s to be, you know, next studies, future studies, but that not through air pollution, that community severance results in higher rates for these mental health hospitalization rates.
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