Could air pollution make your memory worse?

Summary

Short Wave – "Could air pollution make your memory worse?"

Date: June 16, 2026 | Hosts: Emily Kwong & Angela Zhang | Guest: Mary Louise Kelly

---

Episode Overview

This episode of Short Wave dives into new scientific findings on how air pollution affects brain health—particularly memory. Emily, Angela, and guest Mary Louise Kelly also explore unusual research topics: a massive whale graveyard discovered in the Indian Ocean and what ancient DNA in squirrel droppings can tell us about past ecosystems. As always, the conversation is lively, accessible, and sprinkled with humor.

---

Key Topics & Discussion Points

1. Air Pollution and Memory Loss

[03:46-06:25]

• Tiny Particles, Big Consequences
  Angela introduces a new study on ultrafine air pollution particles—smaller than the width of a human hair, commonly from wildfires and car exhaust.

  "They can also get directly to the brain through the blood." — Angela Zhang [03:52]

• The Study
  Researchers in California linked residential air pollution exposure to cognitive test results, focusing on semantic memory (how we store factual information).

  "The people who had been exposed to more pollution over the years had weaker semantic memory. So really that long-term pollution looked like it was aging the brain's memory ahead of schedule." — Catherine Conlon, Study Author [04:40]

• Semantic Memory Implications

  "When that's affected, we can think about how that's the kind of thing that might chip away at a person's independence or ability to have the quality of life that we would hope to have." — Catherine Conlon [05:07]

• Controlling for Variables
  The research accounted for differences in education and income but acknowledged the difficulty in isolating air pollution from other environmental factors like noise.

  "They can't say for sure that it's air pollution that is leading to worse memory." — Emily Kwong [05:22]

• Inequity and Research
  Black Americans were included because they face a higher risk of dementia and are more likely to live in polluted neighborhoods.

  "Including black Americans in research... means that solutions can hopefully reduce inequity." — Angela Zhang [05:38]

• What Can Individuals Do?

  • Check local air quality
  • Close windows and use air purifiers during poor air days
  • Avoid making indoor air worse (skip candles and gas stoves where possible)

  "It's a few less candles, a few less candles." — Emily Kwong [06:23]

---

2. Whale Graveyard Discovery

[06:25-08:44]

• What happens to dead whales? When whales die, their carcasses (called "Whale Falls") create nutrient-rich habitats in the deep sea, sustaining diverse ecosystems.

  "I'm picturing like a deep sea buffet for all these way deep down creatures." — Mary Louise Kelly [06:52]

• New Finding: An Ancient Whale Graveyard
  A Chinese research team discovered what may be the deepest and most extensive whale graveyard in the world (the Diamantina zone, Indian Ocean).

  • The fossil stretch is nearly 750 miles long, with some bones over five million years old.

  "These are bones that are shaped like chimneys or even giant cigars. And the oldest fossils were 5.3 million years old. It's pretty old. So old." — Angela Zhang [07:20]

• Current Whale Falls
  Five whale falls observed teeming with sea life, including microbes, squat lobsters, brittle stars, jellyfish, and even bone-eating worms (possibly new to science).

• Why the Indian Ocean?
  The seafloor shape and ocean currents likely funnel whale carcasses to this area.

  "The surface currents and the deep currents can funnel or concentrate those cutters on the sea floor." — Angela Zhang [08:06]

• Paleontological Excitement

  "The study reminded him of a trailer for the first in a series of epic movies and that he hopes there will be many more of these blockbusters to come." — Emily Kwong on paleontologist Stephen Godfrey's reaction [08:26]

---

3. Ancient Squirrel Droppings & Ice Age Insight

[08:44-11:14]

• Setting: The Pleistocene Epoch
  Transition from Ice Age to today; focus on the Yukon, Canada, and its Arctic ground squirrels.

• How Squirrel Poop Becomes an Archive
  The researchers realized the ground squirrels are "accidental Ice Age archivists":

  "They're kind of like accidental Ice Age archivists." — Tyler Murchie, study author [09:26]

  Squirrels hibernate for up to eight months and eat nearly anything—including larger animal remains—leaving behind droppings rich in environmental DNA (eDNA).

• What's in the Droppings?
  Scientists found DNA of ancient plants, woolly mammoths, extinct bison, horses, and birds—all preserved in layers of fossilized feces.

  "You might think that's nothing. But the kind of data you can get is just remarkable, with millions and millions of DNA fragments... that can paint a picture from something that you otherwise would have just thought nothing of passing by." — Tyler Murchie [10:45]

• Changing Attitudes Towards Animal Excrement in Science

  "In the past, researchers have sometimes dismissed animal excrement because they thought, well, it's only just going to show that animal's DNA." — Angela Zhang [10:27]

  This study proves it offers a much wider environmental picture.

• Memorable Banter

  "Who needs mountains, who needs sparkling streams when we can be looking at squirrel poop?" — Mary Louise Kelly [11:08]

---

Notable Quotes & Memorable Moments

• Emily, on scenting the show's diversity:

  "...stories on air, land and sea. You're listening to Shortwave, the science podcast from NPR." [01:35]

• Angela, on learning from the gross and unexpected:

  "You are what you eat or at least poop out what you eat and people may study it hundreds of years later." [01:30]

• Mary Louise, on squirrel poop’s surprising research power:

  "So we can study the DNA of woolly mammoths because of this ancient squirrel poop. I had no idea you could learn all that from animal droppings." [10:20]

---

Timestamps for Important Segments

• Air pollution & memory study: [03:46–06:25]
• Whale graveyard discovery: [06:25–08:44]
• Ice Age squirrel droppings: [08:44–11:14]
• Memorable scientific banter: [Throughout; see above]

---

Tone and Style

Conversational, witty, and inviting—balancing scientific rigor with humor and curiosity. Each topic is presented with relatable analogies (e.g., deep sea buffets, accidental archivists), making complex research approachable for all listeners.

---

In Summary

This episode connects cutting-edge memory research to daily life amid urban pollution, spotlights breathtaking oceanic discoveries, and reveals how humble squirrel droppings could rewrite our understanding of Ice Age ecosystems. Short Wave reminds listeners that big science can be found in everyday places—from the air we breathe to the ground (and poop) we walk past.

Transcript

[Commercial Announcer]

This message comes from US bank simplify how you do business with business Essentials, a powerful combination of no monthly maintenance fee, checking and card payment processing. Deposit products are offered by U.S. bank National association member FDIC.

[Emily Kwong]

You're listening to Short Wave from NPR. Hey, short waivers.

[Angela Zhang]

Emily Kwong here and Angela Zhang with

[Emily Kwong]

our bi weekly science news roundup featuring Mary Louise Kelly from All Things Considered.

[Mary Louise Kelly]

Hello. Hello. Good to be back.

[Emily Kwong]

Oh, thank you so much for joining us. We are going to start with something kind of serious today. I know, shocking because we're such clowns. But we're going to be talking about air pollution and health, specifically brain health. How are you feeling about your memory these days?

[Mary Louise Kelly]

I am great on things that happened years ago. I am not so great on where my car keys were left.

[Emily Kwong]

This morning is some conflict signs. Yeah, yeah, yeah, yeah. Memory is a complex thing and our brains are fragile instruments in that way. So we're gonna talk about that. And our second and third topics are about critters and what they can teach us about the world around them.

[Angela Zhang]

We're gonna dive deep to will graveyards and then we're gonna zoom in to ancient squirrel droppings. If you can believe that those words can even go together.

[Mary Louise Kelly]

I will come to believe them after you share share these two things I definitely did not have on my radar this year.

[Emily Kwong]

It is like it is such show and tell. Shortwave Roundup is like, here's some treasures that we harves.

[Angela Zhang]

Yeah, you know what they say? I mean, you know, you are what you eat or at least poop out

[Emily Kwong]

what you eat and people may study it hundreds of years later. So today on the show, we've got stories on air, land and sea. You're listening to Shortwave, the science podcast from npr.

[NPR Promo Announcer]

Support for NPR comes from IBM. On Smart Talks with IBM, host Malcolm Gladwell speaks with leaders who are pushing the boundaries of AI and technology in partnership with IBM.

[Malcolm Gladwell]

Hello. Hello. I'm Malcolm Gladwell, host of Smart Talks with IBM. I sat down with Alon Cohen, who leads research and development at ufc, to discuss the complexity of using technology to analyze fight data.

[Interviewee / Scientist]

With kick to the head, it makes contact with the outside of my arm, which I brought up. In our world, that's a blocked strike. Yeah, but teaching a computer what exactly that means and when and how, like when my arm is up, that's a block. When my arm is down and hits my shoulder, that's not. It's those nuances that proved incredibly difficult for machines to be able to handle for a very, very long time.

[Malcolm Gladwell]

That is until IBM entered the octagon.

[NPR Promo Announcer]

Listen to Smart talks with IBM wherever you get your podcasts.

[Commercial Announcer]

This message comes from Schwab. With the new Schwab Teen Investor account, teens can gain hands on investing experience. It's co owned by you and your teen so you can monitor the account while your teen learns how to invest and manage money. Learn [e-mail] this message comes from Edward Jones where they believe rich is more than caring about the latest and greatest. It's also about taking care of what gives your life meaning. That's why your dedicated financial advisor meets you where you are with personalized financial strategies that help protect what matters so you can preserve your progress while creating a path forward. The key to being rich is knowing what counts. Let's find your rich together. Edward Jones Member, SIPC

[Emily Kwong]

all right, Angela and Mary Louise, our host, we have got a lot to get into. What do you want to do first?

[Mary Louise Kelly]

Mary Louise let's do the air pollution and how it can affect your memory. Tell me more.

[Angela Zhang]

So the study I have for you today is about these really, really tiny particles of air pollution, like 30 times smaller than the width of a human hair. And these particles are released by wildfires and car exhaust, among other things. And they're bad for your heart and your lungs, and they can also get directly to the brain through the blood.

[Mary Louise Kelly]

That sounds awful. What, what do we know about how they affect, say, a person's memory though?

[NPR Promo Announcer]

Yeah.

[Emily Kwong]

So to study how air pollution affects the brain, researchers used a database containing information about Americans living in California. The researchers looked at how much air pollution someone may have experienced based on their home address and then looked at their cognitive test scores. And while we know pollution is bad for the brain in general, what the researchers found is that it also affected a specific type of memory.

[Catherine Conlon]

The people who had been exposed to more pollution over the years had weaker semantic memory. So really that long term pollution looked like it was aging the brain's memory ahead of schedule.

[Angela Zhang]

That's Catherine Conlon, a study author. She's a professor of epidemiology at the University of California, Davis. She told me that semantic memory is how your brain stores information. So like that New Delhi is the capital of India, or that 3, 2, 5.

[Catherine Conlon]

When that's effective, we can think about how that's the kind of thing that might chip away at a person's independence or ability to have the quality of life that we would hope to have.

[Mary Louise Kelly]

But how do they know it's air pollution and not some other factor in these people's lives.

[Emily Kwong]

The researchers did control for differences in education and income, but when it comes to geography, you're right. It is hard to separate air pollution from things like noise exposure, which could also influence brain health. They can't say for sure that it's air pollution that is leading to worse memory.

[Angela Zhang]

But including black Americans in research, which is what the study did, means that Solutions can hopefully reduce inequity, since they're almost twice as likely as white Americans to have dementia and they're more likely to live in polluted or redlined neighborhoods.

[Mary Louise Kelly]

Okay, so now we have this research. What do we do about it? Emily?

[Emily Kwong]

Well, it definitely gives policymakers and urban designers something to chew on, but in the meantime, there are things individuals can do.

[Angela Zhang]

Right now, Catherine said to quote, know your air by checking your local air quality on your weather app. And then during wildfires or smoggy days, keep your windows closed and buy or make your own air purifiers. And then lastly, don't make your indoor air worse. So skip the candles and gas stoves if you can.

[Mary Louise Kelly]

No, I love my candles.

[Emily Kwong]

It's a few less candles, a few less candles.

[Mary Louise Kelly]

Okay, let's turn to topic number two. From up in the air to under the sea, we are going to a whale graveyard. I'm trying to picture this, Emily.

[Emily Kwong]

Yeah, it's a really cool place. So when whales die, many fall to the bottom of the sea. And when they land, their carcasses become an energy rich habitat, drawing a wide variety of organisms from across the deep sea to feast. Scientists call these sight Whale Falls.

[Mary Louise Kelly]

Whale Falls because they are fallen whales. Now I'm picturing like a deep sea buffet for all these way deep down creatures.

[Emily Kwong]

Yeah. Who are used to just getting like snacks drifting down to the bottom. So it's really cool. And a research team in China may have found the deepest and most extensive whale graveyard in the world, located in the Diamantina zone in the Indian Ocean. The team published these findings in the journal Nature.

[Mary Louise Kelly]

And what does this whale graveyard actually look like?

[Angela Zhang]

Yeah. So you can picture a nearly 750 mile long stretch of whale fossils. These are bones that are shaped like chimneys or even giant cigars. And the oldest fossils were 5.3 million years old. It's pretty old. So old.

[Emily Kwong]

And during dives with a submersible, the team also discovered five of those whale falls. These five whale carcasses teeming with scavengers. The team saw a whole thicket of microbes, squat lobsters, brittle stars and jellyfish. And even species that may Be new to science. Like bone eating worms.

[Mary Louise Kelly]

Bone eating worms. Okay, Emily, Emily, you just said this is the Indian Ocean that we're in, right? Is there something specific about that, Angela, that so many whale carcasses end up in this particular part of the Indian Ocean?

[Angela Zhang]

One reason offered by the lead author, Xiaotongping, based at the Chinese Academy of Sciences, may have to do with the shape of the seafloor in this part of the world, or maybe even the currents that are around it. The surface currents and the deep currents can funnel or concentrate those cutters on the sea floor.

[Emily Kwong]

Biologists, by the way, are so excited about this finding because these ecosystems are incredibly unique. Stephen Godfrey, a paleontologist at the Calvert Marine Museum who was not a part of the paper, said the study reminded him of a trailer for the first in a series of epic movies and that he hopes there will be many more of these blockbusters to come.

[Mary Louise Kelly]

Here, here. Okay, that brings us to our last story. You mentioned prehistoric mysteries. You mentioned ancient squirrel poop.

[Angela Zhang]

Where is this?

[Mary Louise Kelly]

Where is this going, Angela?

[Angela Zhang]

All right, so we gotta go back in time to the Pleistocene Epoch. This is one of the most critical turning points in Earth's history, because starting around 12,000 years ago, Earth went from chaotic cycles, so ice warm cells, back to ice, to the Holocene, which is our current epoch.

[Emily Kwong]

And a study out this week in Nature Communications zooms in on the Yukon in northwestern Canada, where we find an unassuming critter, the Arctic ground squirrel. The study's lead author, Tyler Murchie, refers to them this way.

[Tyler Murchie]

They're kind of like accidental Ice Age archivists.

[Mary Louise Kelly]

Archivists? Why archivists?

[Emily Kwong]

Because they hibernate underground for about eight months of the year. And when hibernation ends, those squirrels are hungry.

[Malcolm Gladwell]

I just wake up like a zombie

[Tyler Murchie]

crawling out of the ground, you know,

[Angela Zhang]

and finding anything they could eat in the landscape. That's ancient DNA researcher Mikhail Winter Peterson. And what an image, right? He didn't work on this paper, but he says squirrels would have eaten really anything, plants, insects, and even the remains of animals bigger than them. So archiving their DNA, if you will, in their waste.

[Emily Kwong]

That's the archiving?

[Angela Zhang]

Yeah. And sure enough, you know, they found these groups of plants, and they also found DNA from woolly mammoths, an extinct form of bison, caribou, an extinct Yukon horse, and then even some birds, all, if you can believe it, in these squirrel droppings.

[Mary Louise Kelly]

So we can study the DNA of woolly mammoths because of this ancient squirrel poop. I had no idea you could learn all that from animal droppings.

[Angela Zhang]

I know. And funny you should say that because in the past, researchers have sometimes dismissed animal excrement because they thought, well, it's only just going to show that animal's DNA. Right.

[Emily Kwong]

But the fact that they learned so much about the environment at this time shows this could be a method for understanding Earth's history. Here's Tyler.

[Tyler Murchie]

So if you're out for a hike and you see, you know, some old poop, you might think that's nothing. But the kind of data you can get is just remarkable, with millions and millions of DNA fragments of all these organisms together that can paint a picture from something that you otherwise would have just thought nothing of passing by.

[Emily Kwong]

So, Mary Louise, I hope that gives you something to think about on your next hike when you look at the ground or step in it.

[Mary Louise Kelly]

Who needs mountains, who needs sparkling streams when we can be looking at squirrel poop?

[Angela Zhang]

Totally. And if you're not an outdoor person, maybe you can just stay inside and watch some Ice Age and come chat with us as a movie club.

[Interviewee / Scientist]

Wow.

[Angela Zhang]

Anyways, anyways, thank you for everybody.

[Emily Kwong]

I'm sure you want to come back on our show. Thanks for being here today.

[Mary Louise Kelly]

My total pleasure. Anytime.

[Angela Zhang]

You can hear more of Mary Louise Kelly on consider this NPR's afternoon podcast on what the news means for you.

[Emily Kwong]

And for more science stories just like this one, follow Short Wave on whatever app you're listening to.

[Angela Zhang]

This episode was produced by Rachel Carlson and Kai McNamee. It was edited by Rebecca Ramirez, Christopher Intagliota and William Troup.

[Emily Kwong]

Tyler Jones, Check the facts. Maggie Luthar and Josephine Nihonai were the audio engineers. I'm Emily Kwong.

[Angela Zhang]

And I'm Angela Zhang. Thanks for listening to Short Wave, the science podcast from npr.

[NPR Promo Announcer]

This message comes from Capella University. That spark you feel, that's your drive for more. Capella University's flexpath learning format lets you earn your degree at your pace without putting life on pause. Learn [e-mail] this message comes from St. Martin's Press, publishers of how to Try Again by Steve Kam. How to Try Again is a book about quitting unhealthy expectations and making changes that stick. How to Try Again is available wherever books are sold.