EMILY FENG, HOST:
Asphalt is all around us. It's in our roads, our roofs, and parking lots. And while there's been a lot of attention paid to its environmental impact, less is known about its effect on human health - until now. A new study shows that when asphalt is exposed to heat, it emits compounds that can be harmful to human health. Elham Fini is one of the researchers who looked into this problem and possible solutions. She's a professor of engineering at Arizona State University. Welcome.
ELHAM FINI: Thank you for having me.
FENG: Before we dive into your research, I want to set terms here. What is asphalt? What is it made out of?
FINI: That's a very good question. And I guess every one of our audience here - they have driven on roads that called blacktop or simply asphalt road. They basically made of stone aggregates, minerals that are binded together with a glue that looks black. It is petroleum-based material. When they get jet fuel, gasoline and other things out of crude oil, what is left is the glue-like material that is sold as asphalt binder.
FENG: So as part of your research, you and a group of colleagues looked into the impact of asphalt emissions on our health, especially when it's really hot outside. What are the actual chemicals that are being emitted, and what health effects have they been linked to?
FINI: Overall, when we looked at the chemistry or the molecules that are coming out, the blacktop itself has millions of molecule in it. Only some of them are more prone to leave. And among those, for instance, I mentioned benzene, benzotiophene, benzopyran. There are aromatics that you actually sense the smell. So the smell that people are familiar with - those are the molecules we are looking at. Among those, we looked at which one have more impact. And when I say impact, it's a umbrella of impacts. We have looked at several paper we publish on neurological and different health impacts. We are now looking at respiratory - acute respiratory effect. So the umbrella of impact are function of these molecules. Some are more impactful. Some are less.
FENG: The good thing is, engineers look for solutions, and you and other researchers have been looking into possible solutions to the harmful emissions from asphalt, and one of the more intriguing possible solutions is algae. Can you tell me more about that?
FINI: Yeah, that's actually part of a research that's been going on for quite some time and we're looking to cultivate algae in wastewater treatment facilities. So it's sort of a win-win solution, where we are helping wastewater treatment facilities with their operation while removing nutrient through algae and then convert algae to this solution, where algae - we found it's very effective to target select molecule. Algae has a very good functional group and chemistry around it where it coordinates with these specific molecules. And even though it doesn't reduce the total emission off of asphalt by more than 30-, 40%, it reduce its impact on human by hundredfold.
FENG: And what do you do with the algae? Is it painted onto the asphalt? Or is it mixed in? Like, if you're making a big pot of asphalt, you sprinkle in some dried algae? Like, how is it incorporated into the asphalt?
FINI: So we are working with industry to find out how to easy and the best way to apply it onto our roads, and we are planning to have a demonstration soon. But the first approach is to use as a thin coat or thin layer on the asphalt. And this material - it needs a carrier. We are using some granules that carry this adsorbent, and then the plant can simply mix it with the rest of their material. Well, we don't want to bury it deep down in the road or in the construction. We want it as high as possible so it has the most effect. So the top maybe 1 inch or 1 1/2 inch of the road would contain this adsorbent.
FENG: Thank you. That's Elham Fini, professor of engineering at Arizona State University.
FINI: Thank you for having me. Transcript provided by NPR, Copyright NPR.
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