Every other Friday, the Outside/In team answers a listener question about the natural world. This week's question comes from Zach in Minneapolis, MN.
"I’ve read that constant sound from highways can lead to cognitive issues. I worry that I’m dooming my two young daughters to issues growing up next to this highway."
Producer Felix Poon hit the road to find answers.
Transcript
This has been lightly edited for clarity.
Felix Poon: If you live next to a highway, you’re in good company. About 17% of people in the US live close to a highway or busy road. In some parts of the country that figure doubles, like in California where it’s closer to 40%. Living next to a highway can be noisy.
Erica Walker: I used to live in a community where every time a car would pass over this bump on the highway it would be like this: kuh-dunk, kuh-dunk, kuh-dunk.
Felix Poon: This is Erica Walker. She’s an Assistant Professor of Epidemiology and runs the Community Noise Lab at Brown University. And Erica says there are a bunch of potential health impacts from chronic exposure to noise — like higher rates of depression and anxiety, heart disease, diabetes, and even dementia. The common denominator of these conditions is that noise can be stressful, and when you’re stressed —
Erica Walker: Cortisol is one of the hormones released when your body is getting into a fight or flight response.
Felix Poon: Erica has been measuring cortisol across different communities in a pretty unique way. I think it’s cool, even if it may sound a little gross.
Erica Walker: We are actually taking biological samples of their fingernails.
Felix Poon: You heard that right. Fingernails. It turns out that your nails act like little storage tanks for stress hormones released in your body. And even though many of the study’s participants told Erica that they’re not all that bothered by noise —
Erica Walker: Their nails tell a different story.
Felix Poon: The story that Erica found was that the fingernails from people in rural areas had less cortisol in them than the fingernails from people in urban areas. While she’s not sure yet if the difference is because of the noise, or because of other factors like income or race, the link between noise and stress is backed by other studies. And when it comes to kids, noisy environments have been linked to more difficulty paying attention, slower cognitive development, and mental health issues. Not all noise is made equal, however. Some researchers found that intermittent noises, like honking trucks for example, are worse than, say, the steady hum of a highway. So what are we to do about all this noise? Short of moving out of the neighborhood and going somewhere quieter — and let’s be real, a lot of people can’t afford that — Erica has some ideas, from getting a pair of earplugs, to installing soundproof windows, to what she does in her own home.
Erica Walker: I have a masking system, and a masking system is basically a noise — kind of like white noise — that you blast into your home that diffuses the noise from outside. So you can get masking systems for as cheap as $30, to fancy sophisticated ones that you install into your HVAC system.
Felix Poon: But this is still an individual approach to a systemic problem. Erica says something you can do at the community level is petition your department of transportation to install sound walls along highways, which don’t just reduce noise, they also reduce air pollution. And, going forward, she says we should be more thoughtful about how we plan future development. So, as we’re building more housing, more roads, and more data centers, we need to take noise pollution seriously. Which is why, when I asked Erica what advice we should give for our listener Zach?
Erica Walker: Zach should quit his day job and become a an urban planner and direct our cities to be planned better.
Felix Poon: Erica reminded me that kids are resilient, but whatever you end up doing, good luck to you Zach!
If you’d like to submit a question to the Outside/In team, you can record it as a voice memo on your smartphone and send it to outsidein@nhpr.org. You can also leave a message on our hotline, 1-844-GO-OTTER.
