Pavement is everywhere in Phoenix. This ASU researcher says it's off-gassing chemicals in the heat

There is a lot of pavement around metro Phoenix, covering all kinds of surfaces — from roads and highways to basketball courts and sidewalks, to name just a few. And Ellie Fini says we need to be paying more attention to what that pavement is made of — and what it might be doing to our health.

Fini, with Arizona State University's School of Sustainable Engineering and the Built Environment, has been looking into pavement’s off-gassing — and what it means, both for us and for the pavement itself.

Full conversation

MARK BRODIE: Ellie, you’ve been doing research on the potential health dangers of the pavement we travel on. What are some of the health risks you’ve identified?

ELLIE FINI: When you think about urban surfaces, and not just pavement, think about how many surface area you have around you. So we are in our group we are looking at materials that are covering our surfaces, and how they evolve and change in heat and as environmental conditions changes.

So specifically on the roads, and we have 4 million miles of roads in America, we have different materials covering our road. That’s what it gives us such a smooth ride, which we love it when we drive our cars. But one thing that we have to pay attention is how these surfaces can or cannot change as environment is changing.

MARK BRODIE: And it seems as though one of the, if not the biggest, problem that you’re finding is chemicals and other materials sort of coming up from those surfaces and influencing our health, yeah?

ELLIE FINI: That’s a very good way of putting it, when and you can think of it as when you heat your food in microwave. When you get it out, you can smell it more than when it was in the fridge. So as you heat up material, there are molecules and scent, or you can call it aroma, that is coming out.

If you think about it, what are those aroma? How can you get to sense the smell? Those are molecules that are released or emitted from the material, the substance, whether is your food, or whether is your road and parking lot. So you can think of molecules and chemistry as material release, or we call it material off-gassing.

Arizona State University.

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MARK BRODIE: So what are these molecules that are coming out from road and other ground coverings, and what might they be doing to us?

ELLIE FINI: So every material has a very unique molecule that make because it has specific characteristics, so there are different molecules that make your car dashboard, that, it made your road and parking lot. So each of them have different molecules. So as such, molecules that are coming out of it when it’s hot is different.

So some of the roads that we have, for instance, in Phoenix, as the city gets hotter, they are releasing certain scent, aromas. So some of this chemistry could be as familiar as benzene molecules to other molecules that are more complex like benzothiophene, benzopyrene.

But how do they work, and and why they are there to begin with? They have very special roles in materials that we have in urban surfaces. That’s why we put them there. So their loss is actually a loss for the material itself. If we are losing the ingredients that are essential for roads, are we going to get shorter life, sooner crack appears, degradation?

That’s the question actually got me and my group today research, where we started to see how we can make our road last longer, and some of this could be material loss, just like our dehydration. So don’t let our roads dehydrate.

MARK BRODIE: Yeah, well, but ... as you say, it it seems like it’s kind of a balance here, right? Because you you want to have roads that are functional, right, that don’t have cracks and potholes and need to be replaced very frequently. But at the same time, in order to do that, you need to have some of these chemicals and other materials that could be dangerous for our health.

So it seems like you have to either balance OK, how much of those materials do we want in the road coverings, or is there something else that we could replace those chemicals with that would be safer for humans and also have the same benefits to the to the roads and freeways, right?

ELLIE FINI: You, you put it very perfectly right. So there are chemicals that we need them there. That’s why we we make it with, just like your paint on the wall. You need those ingredients. But what we don’t need is a loss of those ingredients. So the ingredient as complicated as they are, if they are needed, so be it. But we don’t them want them to lose during the heat and during the life of it.

So to answer to your question, some of those molecules or emerging solutions that are coming out could be the future of low emitting surfaces. Another way or another pathway could be looking at what are they really being lost specifically, not as a total lump sum. If you say my, my material loses 1 microgram, that’s one thing. Or you say, "My material is losing this specific molecule," and then we can look at consequences.

Right now, we are still at that stage that should we count them, how should we count them, and how should we measure it and so forth. So research are emerging and there are solutions that I’m hoping it will get into our street as low-emission solutions. Arizona State University, many university across the country are coming up with solutions that can get there, I guess it needs public demand and ask for it.

MARK BRODIE: Well, it seems like based on your research, one of the more promising solutions could be algae. Like, you could make road surfaces with with algae in it, is that right?

ELLIE FINI: So that could be one solution and by no means is limiting or saying this is the best or the only solution. But yes, so we actually, this is a more of a 16 years research that got us to a point that we can actually come up with a material that is low emitting and using some of this on our roads it could reduce the emission impact.

And by impact, I mean, we’re not maybe reducing the total mass loss by huge amount, but we’re reducing those species that are more impactful on human side.

MARK BRODIE: How big of an issue is this now and maybe could it be down the road? Like, how I guess maybe how urgent is the work you’re doing to try to figure out a way to have roads that are functional that don’t off-gas and emit things that are that are this dangerous for our bodies?

ELLIE FINI: Well, in terms of how much is needed, I believe we should start looking at surfaces that are not releasing, or they are not releasing a lot of molecules. And in my mind, because the the climate change, because the weather is getting hotter and especially in cities like Phoenix where we have significant portion of our cities covered, it is urgent.

And another aspects of it is if we don’t know what is getting released, how can we have a good air quality model? How can we predict what’s in our air? So counting and overlooking what is coming out is one problem. Second one is how can we mitigate those coming out?

MARK BRODIE: All right, Ellie Fini is with ASU’s School of Sustainable Engineering and the Built Environment.

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