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This Is Your Brain on Pollution (Update)
00:47:24
As the Trump administration rolls back environmental regulations, we revisit a 2022 episode that explored the hidden cost of an invisible threat: air pollution.
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- [00:01]
Stephen Dubner
Freakonomics Radio is sponsored by Pacific Life Insurance. From Pinky Swears to I do, you make promises throughout your Life. For nearly 160 years, Pacific Life has been helping you keep them by protecting those who matter most. Pacific Life the Power of a Promise Ask a financial professional how Pacific Life can help you create a more confident financial future. Pacific Life Insurance Co. Omaha, Nebraska and in New York, Pacific Life Annuity, Phoenix, Arizona. Freakonomics Radio is sponsored by Mint Mobile. Unlimited talk text and data and fast, reliable coverage on the nation's largest 5G network. No catch to get your new wireless plan for just 15 bucks a month, go to mintmobile.com freak that's it. There's no catch. $45 upfront payment required, equivalent to $15 a month. New customers on first three month plan only speeds slower above 40 gigabytes on unlimited plan. Additional taxes, fees and restrictions apply. See Mint Mobile for details. Hey there, it's Stephen Dubner. We recently got an email from a listener who wondered if the recent wildfires in the southeastern United States were going to affect the final exam scores for high school and college students. Not because students were displaced by the fires, but because the wildfire smoke might have affected their brains. This listener had apparently heard an episode we made a few years ago called this Is yous Brain on pollution. So we've decided to replay that episode for you today with updated facts and figures. As for whether this year's test scores in the Southeast were affected, that sounds like an excellent research question for an enterprising investigator. If anyone out there decides to do that research, let us know. We're@radioreconomics.com as always, thanks for listening.
- [02:08]
Michael Greenstone
It's worse than cigarette smoking. It's worse than wars. It's worse than auto accidents.
- [02:17]
Stephen Dubner
Wow. What's worse than wars and car crashes and smoking? Here, I'll give you a hint. Imagine you are getting ready to leave your house for work or school, maybe to go for a run. There is some standard information that most of us seek out before leaving home. There's this.
- [02:34]
Andrea Linose
We've got partly Sunny skies, it's 85 south, winds at 14.
- [02:38]
Stephen Dubner
And there's this. We've got multiple accidents, stalled vehicles causing major delays. It makes sense to check the weather and traffic before leaving home. But there's information we don't usually check that could be just as important, if not more so. What if this is what you heard in the morning?
- [02:55]
Edson Severnini
The level of particulate matter in the air today is above the recommended World Health Organization guidelines.
- [03:01]
Stephen Dubner
Or even this. If your child has an important test today or you're giving a big presentation at work, you might want to consider rescheduling or even this the Supreme Court will be delaying oral arguments until next week because of a high particulate matter count in Washington, D.C. it's well established that air pollution has significant negative effects on the human body, and many places do require a public announcement when pollution levels are high. But is it possible that on a given day, high pollution can affect your brain, your cognitive abilities?
- [03:38]
Steve Levitt
So I can't say I've heard many more theories that would surprise me more if they were true.
- [03:42]
Stephen Dubner
Today on Freakonomics Radio, the this is your brain.
- [03:46]
Angela Duckworth
The top card is written in black, the bottom card is written in blue. So I'm gonna say yes.
- [03:53]
Stephen Dubner
And this is your brain on pollution.
- [03:56]
Steve Levitt
It's one of the hardest things I've ever done in my life.
- [04:01]
Stephen Dubner
My God, is pollution making us more stupider?
- [04:17]
Edson Severnini
This is Freakonomics Radio, the podcast that
- [04:20]
Stephen Dubner
explores the hidden side of everything, with
- [04:23]
Edson Severnini
your host Stephen Dubner.
- [04:32]
Stephen Dubner
Andrea Linoz is an economist at Deakin University in Australia.
- [04:37]
Andrea Linose
I'm an environmental economist, which means that I use data and the tools of economics to understand the causes of environmental problems and to think about policy solutions.
- [04:48]
Stephen Dubner
Air pollution is of course, a long standing environmental problem. Chemicals like ozone and carbon monoxide and also what's called particulate matter, or PM2.5
- [04:59]
Andrea Linose
tiny little particles in the air that are a diameter that is less than 2.5 micrometers, so it's more than 100 times thinner than a human hair. And those particles can come from natural sources like dust and smoke, but also from things like the combustion of fossil fuels. One of the most concerning forms of
- [05:19]
Stephen Dubner
air pollution, particulate matter, can be invisible. So unless it's really bad, you can't tell just by looking at the sky whether the air you're breathing is polluted. But the odds are that it is. The World Health organization estimates that 99% of people around the world sometimes breathe polluted air. The WHO has different guidelines for different pollutants. For particulate matter, anything above 5 micrograms per cubic meter on average over a year is considered polluted. The average across China is 35 micrograms. The average across the US is 9, still above the WHO threshold, but much better than it was just a few decades ago. Accordingly, our concern about pollution has been falling. In 1994, 58% of Americans said they had a great deal of concern about air pollution. Today that number is only 40%. Here is one of those 40%.
- [06:18]
Michael Greenstone
I think air pollution is the greatest single threat to human health on the planet.
- [06:22]
Stephen Dubner
Michael Greenstone is an economist at the University of Chicago, where he directs the Energy Policy Institute and co directs the Climate Impact Lab. He also spent a year in the Obama White House working on climate policy. One of his creations is called the Air Quality Life Index.
- [06:40]
Michael Greenstone
The Air Quality Life Index uses satellite data to say how much longer would people in any part of the world live if their area was brought into compliance for what air pollution should be?
- [06:51]
Stephen Dubner
So how does air pollution affect life expectancy?
- [06:54]
Michael Greenstone
The average person on the planet is living 2.2 years less than if where they lived complied with WHO standards.
- [07:03]
Stephen Dubner
Which is what leads Greenstone to say this.
- [07:06]
Michael Greenstone
It's worse than cigarette smoking. It's worse than wars. It's worse than auto accidents.
- [07:12]
Stephen Dubner
The World Health Organization estimates that roughly 7 million people die every year from exposure to fine particles in polluted air. That's at least double the number of people who died globally from COVID in 2020, and more than five times the number of people killed every year in car crashes. The more proximate causes of the pollution deaths include pneumonia, stroke and heart disease. The economic costs of pollution are also massive. One estimate puts it as high as $6 trillion a year, or about 5% of global GDP. Here again is Andrea Linose.
- [07:49]
Andrea Linose
The interest in economics is fundamentally about the productivity impacts. And so part of the reason we're interested in cognition is that if cognition affects productivity, then the costs of exposure to air pollution may be much, much larger than we had previously estimated.
- [08:07]
Stephen Dubner
In other words, we know that air pollution is dangerous to our physical health, as evidenced by millions of deaths around the world. And as Linose tells us, there are
- [08:18]
Andrea Linose
a number of papers that all point in the same direction, in that it does appear that there are cognitive impacts of exposure to high levels of air pollution.
- [08:29]
Stephen Dubner
So how significant are the cognitive impacts of air pollution? The US remember, is a relatively low pollution country, in part because of domestic policies like the Clean Air act, but also because we have offshored so much of our manufacturing and the pollution that goes with it. A study published in the journal Nature in 2007 found that more than 50% of China's air pollution at the time was associated with goods and services consumed outside the provinces where they were produced, and that 11% of Chinese air pollution deaths could be traced to goods and services used in the United States and Western Europe. So the US has had the luxury to worry less about the physiological effects of air pollution. But should we worry more about the cognitive effects before we answer that question, let's take a look back at how the US got to where it is.
- [09:26]
Michael Greenstone
So the Clean Air Act, I think, is one of the most beneficial pieces of legislation that was ever passed. Michael Greenstone, again, it was passed in 1970. It was President Nixon who signed the Clean Air act into law. It was amended several times, almost always on a bipartisan basis.
- [09:43]
Stephen Dubner
The Clean Air act essentially sets limits on the amount of pollution that can be released into the air via manufacturing, transportation, and so on. How effective has it been?
- [09:54]
Michael Greenstone
Everyone has probably seen pictures of Delhi today, and there were many parts of the United States that looked like that in the late 60s and early 1970s. But one of my favorite anecdotes from that period is that white collar workers in Gary, Indiana, as a regular matter of doing their job, brought a second shirt. And so these high levels of pollution that we're seeing in other parts of the world, they once exist in the United States. And the reason they don't exist in the United States anymore is largely due to the Cleaner Act.
- [10:24]
Stephen Dubner
There are many benefits of cleaner air, even beyond the obvious. A 2021 study in the journal Environmental Research Letters found that American crop yields are significantly higher than they were 20 years earlier, thanks to fewer pollutants in the air. But it also found that some pollutants, especially particulate matter, are still hurting crop yields.
- [10:44]
Michael Greenstone
The Central Valley in California remains pretty polluted. There's parts of the Midwest that remain pretty polluted. But relative to the WHO standard, the United States is very clean. The majority of the problem is concentrated in Asia, especially in India, Bangladesh, China, and in some parts of Sub Saharan Africa.
- [11:09]
Stephen Dubner
The primary factors that drive pollution in those Asian countries are power generation, home heating, transportation, and as I mentioned earlier, manufacturing, including a lot of manufacturing that used to be done in places like New York and Chicago and Los Angeles. So it's a bit rich for the US to criticize developing countries for their high pollution, especially since most of our environmental regulation came along after we built out our infrastructure in cities. Pollution is a natural byproduct of, of civilization building. And there's plenty of historical evidence. Blackened lungs in mummified tissue from Egypt, Peru and Great Britain point to wood fires from ancient homes. Complaints about air pollution date back at least to ancient Rome, when the smoky cloud hanging over the city was called infamous air and heavy heaven. But air pollution really took off with the invention of, of the steam engine and the Industrial Revolution. Starting In England, the UK today produces less than 3 million tons of coal a year, with the goal of getting to zero. At its peak in the early 1900s, they produced nearly 300 million tons a year. The UK burned so much coal that the natural ecosystem adjusted.
- [12:33]
Stefan Hiblick
There's a story of micro evolutionary biology which is about the peppered moth. I'm not sure if you've ever heard
- [12:39]
Stephen Dubner
about this, that is Stefan Hiblich, a German economist who teaches at the University of Toronto. As for the peppered moth, the peppered
- [12:48]
Stefan Hiblick
moth appears in the UK in two varieties, a darker and lighter variety. And it's well known that before the industrialization in the north of England, the lighter variety was the predominant species. And this was basically because it could hide on trees from predators. But then as cold smoke started turning trees darker, we see a rise in the instance of this darker version of the peppered moth.
- [13:12]
Stephen Dubner
So the darker version of the peppered moth was a byproduct of heavy air pollution, kind of like those white shirts worn by office workers in Gary, Indiana. For Hiblick and his fellow researchers, the moth would be a useful indicator in a much larger story about pollution. It's a story that involves geography, poverty and wind. A westerly wind to be precise.
- [13:38]
Stefan Hiblick
In cities in the Western hemisphere, winds blow from the west to the east. And you might observe that in a lot of these cities, east sides are more deprived.
- [13:47]
Stephen Dubner
Deprived meaning lower income. There are of course exceptions, but the general rule is that the east side of many cities in the Western hemisphere are poorer than the west side.
- [13:59]
Stefan Hiblick
We started wondering if this was driven by cold smoke during the industrialization and a sorting of poor people into the east side and rich people away from the east side. And we wanted to understand if this has long lasting effects.
- [14:13]
Stephen Dubner
If pollution could have an evolutionary effect on the color of a moth species, could it be that prevailing winds carrying coal smoke could change the demographics of a city? Hiblick and his co authors Alex True and Janos Zilberg began to Assemble data from 70 cities across England, starting before coal was heavily used as a fuel for industrialization and extending through its heyday. This was not a simple task and it required a fair amount of creativity. For instance, they hunted down the locations of industrial smokestacks.
- [14:49]
Stefan Hiblick
We started looking into historical maps and found out that Victorian cartographers were absolutely stunning in the level of detail that they drew into their maps. We found the exact location of industrial smokestacks within factory buildings.
- [15:05]
Stephen Dubner
These factories were the sites of steel production and other processes that burned massive amounts of coal.
- [15:11]
Stefan Hiblick
We basically found across all these 70 cities in England, we found about 5,000 chimney locations like the exact Geolocations, they were literally like a historical version of Google Maps.
- [15:24]
Stephen Dubner
The researchers also incorporated census data, like baptismal records, to get at the economic demographics of the English population. But what about pollution data? Victorian England may have had brilliant cartographers, but they didn't have monitors to measure particulate matter. This is where the peppered moth comes in handy. Using the geolocations of the old smokestacks to pinpoint the pollution source, the researchers used an algorithm to model how that coal smoke was carried eastward on the wind. And they confirmed the model's prediction by aligning it with the historical ratio of dark to light peppered moths in a given area, since there were more dark moths in high pollution areas. Clever. Yes. Hiblick and his co authors recently published their findings in a paper called east side Story. Historical Pollution and Persistent Neighborhood Sorting. What did they find?
- [16:23]
Stefan Hiblick
So after coal smoke came in, we see a resorting of poor households into the east side. We have data from 1817, which is before coal smoke was a main fuel for the industrialization. And we find that in 1817 the wind direction where coal smoke would blow to doesn't have an effect.
- [16:41]
Stephen Dubner
Meaning that in 1817, before heavy coal use, the east sides of cities were not systematically poorer than the west sides. Then they looked at the data from 1881. They chose that particular year because they had really good data.
- [16:57]
Stefan Hiblick
We had a census where we had all the names and addresses transcribed.
- [17:02]
Stephen Dubner
And because there was by now a lot of coal being burned, it's pretty
- [17:07]
Stefan Hiblick
much just before the heyday of the industrialization.
- [17:10]
Stephen Dubner
And what did they see in 1881?
- [17:13]
Stefan Hiblick
In 1881 we see a pronounced pattern where there's a much higher share of low skilled workers on the east side of the city.
- [17:20]
Stephen Dubner
What's your best evidence that this relationship is causal and not just a correlational finding?
- [17:25]
Stefan Hiblick
If you draw, let's say a small circle around a chimney, you would expect in general to have a higher instance of low skilled workers just because commuting at that time was walking and they have to live somewhere close. But even if you hold distance constant and draw a circle, you would then see that as you walked along the circle, once you get to the east, you will see that the instance of low skilled workers is in the range of 1 or 2 percentage points higher.
- [17:51]
Stephen Dubner
Are the low skilled workers low skilled because of the coal smoke, or are they living there because they're low skilled workers?
- [17:57]
Stefan Hiblick
I cannot tell for sure if it's because of the cold smoke. I think in the past it was mostly a sorting into Industries. From today's evidence, we know that there might be intergenerational effects and pollution might also have longer lasting effects that might affect cognitive capacities.
- [18:15]
Stephen Dubner
Longer lasting effects that might affect cognitive capacities, that is effects that outlast the original 19th century pollution. The idea is that children who grow up in those polluted areas suffer negative effects that lead to worse outcomes in education, health and income, even if they were to move away later. The UK, like the US began cracking down on air pollution in the mid 20th century. But here's the thing. Hiblick found that the effects of neighborhood sorting didn't go away.
- [18:49]
Stefan Hiblick
What we're seeing is that really polluted and really unpolluted neighborhoods, they are basically becoming even more extreme, either richer or poorer. What we're finding is that one standard deviation increase in pollution would lead in the past to about 15% higher share of low skilled workers in neighborhoods. And then today we would see that this would go up to 20%.
- [19:12]
Stephen Dubner
The likely explanation is a classic case of path dependence.
- [19:16]
Stefan Hiblick
You have the causes initially that the east side had these negative effects of pollution, poor people sorted there, and then the effects were cemented over time by additional investments. Right? Maybe you had the highway cutting off the east side from the west side, or you have poorer building structure as a result of that. You have a certain composition of residents, you have less funding for schools, you have less funding for other amenities. And this is then the strength noble effect. In our paper we find, for instance, that test scores in these east sides are lower and that crime instances are higher.
- [19:52]
Stephen Dubner
Okay, lower test scores and higher crime in the areas that have historically had high pollution. But again, how can you untangle cause from effect? Does pollution itself lower people's cognitive abilities or do people with lower cognitive abilities sort of into polluted areas? Lower cognitive abilities may mean lower incomes, which may mean fewer options when it comes to where you live. And how can you untangle this question in the face of snowball effects like school funding? This brings us back to Andrea Lanose.
- [20:28]
Andrea Linose
I had been reading the literature on the effects of air pollution on productivity, but also other behaviors, for example crime, and knowing that a leading hypothesis for those effects was really this cognitive impact. So there's a literature showing that the test scores of high school students is negatively impacted by exposure to particulate matter. But we didn't at that stage have much evidence for the cognitive effects in adults. And that makes sense because we don't regularly sit high school exams every year as adults.
- [21:04]
Stephen Dubner
There was one piece of evidence for the cognitive effects of pollution on Adults. And it came from a paper that analyzed baseball umpires.
- [21:13]
Andrea Linose
Yeah. Who said economics isn't fun?
- [21:15]
Stephen Dubner
This was research by James Arch Smith, Anthony Hayes and Sudhe Sabarian.
- [21:20]
Andrea Linose
They're able to compare quality of umpires decisions on days of high pollution exposure and low pollution exposure.
- [21:27]
Stephen Dubner
And they did find that umpires made more mistakes when they were in a place that had a high pollution level on that day.
- [21:35]
Andrea Linose
That's a really important paper. It demonstrates that there is an impact on performance of really highly skilled professionals. But it is a study of a group of individuals that are probably fairly similar doing one task, an important task, for one specific task.
- [21:51]
Stephen Dubner
What the Noahs wanted to see was the cognitive effect of pollution in a larger population across a diverse array of tasks.
- [22:00]
Andrea Linose
I had recently been exposed to some advertising by Lumosity and suddenly thought, wow. Well, there's a company that is claiming to test the cognitive ability of lots of adults across the United States, like Linoz.
- [22:15]
Stephen Dubner
You may know Lumosity's name from advertising. They've sponsored a lot of radio and podcasts, including ours, for a short time in 2014. Lumosity is a so called brain game app created by Lumos Labs, a company founded in 2005. It now claims more than 100 million users across nearly 200 countries. So lots of data.
- [22:39]
Andrea Linose
They have something called the Human Cognition Project where researchers can apply to either use their data or to use their platform to undertake other tests.
- [22:48]
Stephen Dubner
Lino's was able to get hold of data from more than 100,000 users across the US playing a variety of games over a three year period.
- [22:57]
Andrea Linose
So we have games that measure verbal ability, your attention, your flexibility, so how quickly you can shift from one cognitive task to another. Your memory, so this is your very short term working memory, your math ability, your speed, so speed of processing and then also problem solving.
- [23:15]
Stephen Dubner
There's a lot of controversy over whether Lumosity and similar products actually improve cognition. In fact, they paid a $2 million fine in 2016 for deceptive advertising. But that wasn't the question Linose was interested in. She and her research partner, the economist Edson Severnini, were looking at a different set of questions. They wanted to know whether day to day changes in air pollution in a particular place affected the scores of people who played games on Lumosity. The World Health Organization recommends that in a 24 hour period, particulate matter should be below 15 microgram per cubic meter. The EPA threshold is higher at 35. Particulate matter is just one of the many pollutants the EPA tracks across the US rolling up the total into a daily measure called the Air Quality Index, or aqi. Edson Severnini, as a researcher interested in air pollution, was already acutely aware of how much variation there can be day to day.
- [24:19]
Edson Severnini
I always go for my morning walk and I always check on my phone, what is the Air Quality Index for the day? If it's below 50, you are in a good or green color of the AQI. If it's between 50 and 100, it's yellow like the moderate pollution. And then above 100 is when I avoid leaving the house because that's where it starts getting a little bit unhealthy to be outside.
- [24:44]
Stephen Dubner
Severnini teaches at Boston College, but when we originally interviewed him for this episode, he was at Carnegie Mellon University, which is in Pittsburgh, which is historically one of the most polluted places in America. For decades, Pittsburgh was a cradle of coal, iron and steel production. When Charles Dickens visited in 1842, he wrote, Pittsburgh is like Birmingham in England. It certainly has a great quantity of smoke hanging over it. Like Gary, Indiana, Pittsburgh was a two shirt town. And it's still rated as the 16th worst US metro area for particle pollution. That said, not all parts of the Pittsburgh area have the same level of pollution on a given day. And the same goes for all the places that Severnini and Linose wanted to measure in their study.
- [25:30]
Edson Severnini
Pollution levels are not measured around us like attached to our bodies. So that would be the ideal experiment. You are breathing the air, you know exactly how much pollution you have in the air. It's not the case. And so that creates noise in the data, which would underestimate the relationship between cognitive function and pollution.
- [25:49]
Stephen Dubner
But they did find a way to address that problem.
- [25:52]
Edson Severnini
We used the wind direction that brings pollution from other locations and that makes a uniform level of pollution for all individuals in an area independently on whether they are close or slightly farther away from the monitor.
- [26:09]
Stephen Dubner
Severnini and Linoz ran their analysis across more than 4 million Lumosity gameplay observations and measured that against pollution data across the us. What'd they find?
- [26:23]
Andrea Linose
The headline result is that there is a cognitive impact for the working age population.
- [26:29]
Stephen Dubner
In other words, it's not just among test taking students.
- [26:34]
Andrea Linose
We're actually finding that the largest effects are for people under 50 and not
- [26:39]
Stephen Dubner
just for baseball umpires either.
- [26:41]
Andrea Linose
So this is an issue for the working age population and we expect that to have pretty significant productivity impacts. The second main result that I think is entirely novel is that it does seem to affect memory ability. And so if we think across occupations, if we think about sectors that rely more on memory ability. We expect to see the productivity impacts in those areas be more significant.
- [27:07]
Stephen Dubner
So what are we to make of this information? What kind of policy implications does it have? That's coming up after the break. And also hi Steven. Hey, Angie Levitt's here too. Hey Levitt.
- [27:22]
Steve Levitt
Hey, how you doing, Dumner?
- [27:23]
Stephen Dubner
I play some Lumosity games with my Freakonomics friends Angela Duckworth and Steve Levitt, who are not aware that this is about pollution levels in their respective cities. Because I want this to be truly cutthroat.
- [27:36]
Steve Levitt
This is the kind of thing I'm really good at. Like, I would honestly say this is my specialty.
- [27:41]
Angela Duckworth
I'm probably more competitive than IMU of.
- [27:44]
Stephen Dubner
And how would the climate change conversation be different if instead we were talking about pollution? I'm Stephen Dubner. This is Freakonomics Radio. We'll be right back. Freakonomics Radio is sponsored by Cash App. Is Bitcoin complicated or do people just think it is? For a long time it felt like something only tech experts or hardcore investors really understood. But what if getting started with Bitcoin didn't have to feel overwhelming? If you've been curious about Bitcoin but haven't made the jump yet, Cash App makes it easy. You can set up automatic purchases with zero fees or buy larger amounts also with zero fees. Start small or go bigger. It's designed to be simple. Either way, for a limited time, new customers can get $10 added to their balance. Just use code CASHAPP10 when you sign up. And don't forget this part. Send at least $5 to a friend in the first two weeks. Terms apply. Cash App is a financial services platform, not a bank. Banking services provided by Cash App's bank partners. Bitcoin services provided by Block Inc. Brand for additional information, see the Bitcoin disclosures at Cash App legalpodcast. Freakonomics Radio is Sponsored by Southern Co. The World and its energy needs are always changing. Southern Company's commitment to meeting this demand stays the same. That's because Southern Company believes energy is more than a utility. It's what powers possibilities. So they are looking ahead and investing $80 billion in infrastructure upgrades and are committed to fueling growth in ways that benefit all customers so that reliable and affordable energy is accessible for generations to come. Go to southerncompany.com to learn more. Building the Future of Energy. Freakonomics Radio is sponsored by Everpure Data is crucial to businesses, but managing it can create friction, risk and manual work. Everpure transforms static data into a living system intelligent, instantly accessible, secure, energy efficient and ready to perform. Plus, there is zero downtime for upgrades and maintenance. Whether your data is in the cloud, on premises, or at the edge, Everpure makes data management so simple it feels like second nature. Tame your data chaos with EverPure. Visit everpuredata.com to learn more. Angela Duckworth and Steve Leva, you're two of the smartest people I know, so I thought we could play some brain games today. Are you both feeling relatively sharp?
- [30:29]
Angela Duckworth
Are these the kind of games that one of us is going to win and the other two lose?
- [30:34]
Stephen Dubner
God, the two of you are made for each other. Because the first thing Levitt said before we started recording was something about what did you say, Levitt?
- [30:41]
Steve Levitt
I said it's no fun to play with Angie because she's been playing these games her whole life because she's a psychologist and I know zero about psychology. I'll just play these games all day long.
- [30:49]
Stephen Dubner
But Levitt, you play trivia. At least you love gaming.
- [30:52]
Steve Levitt
I do. You know, the problem for me is that one of the few things I have left is the belief that my brain still works. And if you take that from me, I'm going to be really upset.
- [31:02]
Stephen Dubner
Would you say there's any external factor that might contribute to a subpar performance today? Maybe you didn't sleep well last night. Do you want to just pre register your conditions?
- [31:13]
Steve Levitt
I never sleep well. I have way too many kids. That's my standing excuse, is that I haven't had a good night's sleep in about 18 years.
- [31:19]
Stephen Dubner
Angie, anything you want to register?
- [31:21]
Angela Duckworth
Well, as you know, I'm a pretty sleeper, but improbably I actually slept fine last night. Or uncharacteristically I should say. So there's that I was going to complain about the time of day, but then again, it's more or less the same time of day for all of us.
- [31:36]
Stephen Dubner
Yeah, we should say it is late in the day. It's a little after 5pm on the east coast and Levitt's in Chicago, so that's still end of the day.
- [31:43]
Angela Duckworth
So he's got a one hour advantage on this.
- [31:46]
Stephen Dubner
Can I say my air conditioning is broken and it's really hot?
- [31:50]
Angela Duckworth
Oh, okay, you win then.
- [31:53]
Stephen Dubner
In case you don't know, Steve Levitt is a professor emeritus of economics at the University of Chicago. He's also My Freakonomics co author and he hosts a few episodes of this show as well. Angela Duckworth is a psychologist at the University of Pennsylvania in Philadelphia. She's the author of the book Grit, and she and I used to host the no Stupid Questions podcast together. Anyway, the three of us set out to play three games as part of Lumosity's fit test. One game is said to measure mental flexibility. Another memory. And the third, called Train of Thought, purported to test our attention by having us guide different colored trains to their respectively colored destinations. If all that sounds super easy, well, you should try it.
- [32:43]
Steve Levitt
Okay, here we go.
- [32:50]
Angela Duckworth
This is so cute. I love trains.
- [32:52]
Steve Levitt
Oh my God, this is hard. This is one of the hardest things I've ever done in my life. Oh my God.
- [33:03]
Angela Duckworth
See, I got 13,500 points and I scored better than 70%.
- [33:08]
Steve Levitt
I don't even want to tell you guys how I did.
- [33:10]
Angela Duckworth
Come on, tell me how you did.
- [33:11]
Steve Levitt
I was 34 out of 39. 97%.
- [33:15]
Stephen Dubner
Wow, Levitt.
- [33:17]
Steve Levitt
I just said it was the hardest thing I'd ever done. I didn't say I was messing up.
- [33:20]
Angela Duckworth
97% Levitt. I'm really impressed. I wonder what strategy used to be.
- [33:28]
Stephen Dubner
97% wasn't Levitt's actual score. It was his percentile ranking for his age group. That's how Lumosity ranks you. After playing all three games, the results were in. Levitt was the clear champion with an average percentile rank of 92. Pretty impressive. Although I suspect Levitt may have logged in earlier under a pseudonymous to practice. He is sneaky like that and very competitive. On the other hand, he's also really smart, so I'm probably wrong. Angela, meanwhile, was very consistent across the three different tasks, but her average was lower. 71st percentile. For what it's worth, my scores were inconsistent. A high memory score, but really low attention, which probably has something to do with. Wait, I forgot what I was going to say. Anyway, my average was around the same as Angela's 72nd percentile. So, Angie, how do you feel about your performance on these games today?
- [34:29]
Angela Duckworth
Well, I'm pretty disappointed, Steven. I like to think of myself as better than a C minus brain, but maybe I'm, you know, less smart than I thought I was, at least on these games.
- [34:41]
Stephen Dubner
Levitt, how do you feel about your performance today?
- [34:43]
Steve Levitt
You know, I'm relieved because I have the self image that these stupid little games are my forte. I have to say, actually, at the particular moment when we were doing it, I felt great. I mean, I don't sleep as much as I would like to, but honestly, no, I felt very sharp today.
- [34:59]
Angela Duckworth
I cannot think of a single excuse for not doing well in These games.
- [35:03]
Stephen Dubner
I'm curious if either of you have ever thought about particulate matter pollution in the atmosphere as a potential contributing factor to cognitive ability.
- [35:12]
Angela Duckworth
What do you mean particulate matter in the atmosphere? No, I guess the answer is I haven't thought about that. I don't even know what you're talking
- [35:18]
Steve Levitt
about on a particular day, Dubner. You mean like how much is in the air today?
- [35:23]
Stephen Dubner
Yeah. So what would you say if I told you that a couple economists have analyzed lumosity gameplay just like we did in different places and found that, quote, even when air pollution is below EPA and World Health Organization quality guidelines, cognition is negatively affected across seven different cognitive domains. Furthermore, their identification relies only on short term changes in pollution exposure within an individual's play history. Would that surprise you?
- [35:56]
Angela Duckworth
I'm trying to process this, Levitt. What do you think?
- [35:59]
Steve Levitt
So I can't say. I've heard many more theories that would surprise me more if they were true. But what do I know about the world?
- [36:07]
Stephen Dubner
So let me read you some numbers. This paper finds negative cognitive effects at just 20 micrograms per cubic meter. Now here's what's interesting in the three cities where we are. I'm in New York, Angela's in Philadelphia, Levitt's in Chicago. On average, in 2019, for instance, New York was the lowest of those three at 7 micrograms per cubic meter. Philly is at 10.3 and Chicago was the worst at 12.8.
- [36:36]
Steve Levitt
How many particulates are there in Chicago today?
- [36:38]
Stephen Dubner
Okay, so I have some good news and some bad news. The good news is, Levitt, you are suffering very low particulate matter in Chicago today. As of today, Chicago only had 8.7 micrograms per cubic meter. Philadelphia and New York, we have very high levels today, as it turns out.
- [36:58]
Angela Duckworth
Do we?
- [36:58]
Stephen Dubner
Yeah. 23.4 in New York and 24.6 in Philadelphia.
- [37:03]
Angela Duckworth
Is there that much variation in particulate matter?
- [37:06]
Stephen Dubner
There is that much variation. Not only place to place, but day to day.
- [37:09]
Angela Duckworth
Wow, that's what's really interesting. The day to day part. I didn't realize that.
- [37:14]
Stephen Dubner
Levitt, earlier you said that you just felt incredibly sharp and focused when it came time to do the tasks. Do you think that had anything to do with the relatively low level of particulate matter in the air in Chicago?
- [37:27]
Steve Levitt
I wouldn't think so, but maybe I should start tracking it. I could, without knowledge of the particulates rate how I felt each day.
- [37:34]
Stephen Dubner
So you each sound relatively skeptical of the findings of this paper. Let me just ask for like a confidence level 0 to 10. Let's say that these findings are somewhere in the ballpark of useful and true.
- [37:45]
Angela Duckworth
I want to rate my own confidence in saying anything about somebody's findings before reading their paper. I would say that would be like a one.
- [37:51]
Stephen Dubner
Okay, fair enough. Levitt, do you want to speculate?
- [37:55]
Steve Levitt
I would say it feels like a one in terms of likelihood of being true. An if true a 10 in terms of importance.
- [38:03]
Stephen Dubner
Coming up after the break, just how bad is this cognitive impairment from air pollution?
- [38:09]
Michael Greenstone
We have probably been understating the losses from air pollution by about 50%.
- [38:14]
Stephen Dubner
You're listening to Freakonomics Radio. I'm Stephen Dubner. We'll be right back. Freakonomics Radio is sponsored by USPS in business, there's no room for guesswork. Every shipment matters. Every deadline accounts. That's why reliability is at the core of USPS Ground Advantage. Each package moves through a secure nationwide network tracked from dock to door with affordable upfront pricing and delivery you can depend on because knowing your logistics are handled lets you focus on everything else. Visit usps.comground advantage to start shipping with confidence. USPS Ground Advantage we mean business Business Freakonomics Radio is sponsored by LinkedIn ads ever invested in something that didn't live up to the hype? Marketers know that feeling. They optimize for the numbers that look great, like impressions, but then they don't see revenue. LinkedIn has a word for bullspend. Instead, you can get the highest ROAS of major ad networks with LinkedIn. Cut the bullspend, advertise on LinkedIn, spend $250 and get a $250 credit. Go to LinkedIn.com freakonomics Terms apply. Freakonomics Radio is sponsored by Rula. Therapy is one of those things some people talk themselves out of. They think it's too expensive or too overwhelming to figure out where to start. Rula is one way to make that first step feel a lot more doable. Offering accessible, affordable therapy that fits your needs. Sign up in just a few minutes and get matched with a therapist who fits what you're looking for. Need to talk to someone quickly? Appointments are often available as soon as the next day and with Insurance Co pays average around $15 per session. You also see estimated costs upfront, so there's a lot more clarity going on. And in terms of outcomes, 93% of rule of patients report symptoms improvement. Thinking about therapy Rula is a pretty simple way to take that first step. So turn off the talk track that's keeping you from progress and head to rula.com that's r u l a.com to find a therapist the easy way. So what is the likelihood that local real time pollution levels can impair cognitive function in the moment? It might help to know the mechanisms by which this could happen.
- [40:44]
Edson Severnini
I'm not a medical expert. What I'm going to say now is based on, you know, reviews of this
- [40:50]
Stephen Dubner
literature, that again is Boston College economist Edson Severnini.
- [40:55]
Edson Severnini
There are two ways where air pollution could impair cognition. One is that they go directly to the brain and then it affects the functioning of the neurons. But also they stimulate pro inflammatory, I think it's called cytokines. And so this is a more indirect route. But everybody who is doing research on this topic, they always see processes that are affected by pollution. Oxidative stress, inflammation, some neuron laws.
- [41:28]
Stephen Dubner
I should note that Angela, Steve and I played only a few games on one day. The data that Severnini and Linose analyzed was much more robust still. I asked whether our scores should be adjusted based on that day's pollution levels in our respective locations.
- [41:46]
Andrea Linose
The impact of this exposure to pollution would be to shift someone in that ranking by about six points.
- [41:53]
Edson Severnini
So if you were playing on a day that was above the threshold that we set and you were performing like in the 75th percentile on average, you would have been on the 80th percentile that day.
- [42:04]
Stephen Dubner
And that's just on average. So once you account for the local pollution levels in New York and Philadelphia that day, which were high, and Chicago which was low, Angela and I might be right up there with Levitt. Linose and Severnini's work was published last year in the Journal of the association of Environmental and Resource Economists. There is also research from the economists Michael Gilrayne and Angela Zhang, who looked at data from over 10,000 school districts in the US and found that each increase in particulate pollution led to decrease in student test scores. We asked Michael Greenstone, the pollution and policy veteran, what he thought of Linose and Severnini's findings. Now do keep in mind that Edson Severnini was actually a postdoc under Greenstone.
- [42:50]
Michael Greenstone
You know, it's a very well done paper. In a kind of artificial setting, long run meaning is a little bit hard to suss out. The more challenging thing is to find instances where there's long run variation. I think in both the health and in the cognition literatures, the holy grail is not to rely on studies that use either day to day or month to month, but to find a setting where there's a permanent difference in air pollution. It's much harder to come up with those examples. But that is, after all, what policy is trying to do. It's not trying to reduce pollution on Tuesday. It's trying to reduce pollution 365 days a year.
- [43:35]
Stephen Dubner
Greenstone thinks he may have found the Holy Grail.
- [43:38]
Michael Greenstone
About seven or eight years ago, I stumbled upon an example from China that seemed to mimic this kind of ideal, and that's something called the Huai River Winter Heating Policy. It dates back to when China was much less wealthy and there just weren't enough resources to provide winter heating for everybody. So they did something quite arbitrary and capricious. They drew a line across the middle of the country and that line followed the Huai River.
- [44:08]
Stephen Dubner
The Huai river, by the way, runs west, east, not north, south.
- [44:13]
Michael Greenstone
And they said, okay, if you live north of that line, where it's colder, we're going to install central heating systems and we're going to give you free coal. So that's in the north. In the south, the policy was, guys, you're out of luck. No heating.
- [44:29]
Stephen Dubner
So what Greenstone was looking at had nothing to do with whether people sorted themselves into neighborhoods on the east or west side of a city like Stefan Hiblick looked at in England. This had to do with comparing the health and educational outcomes of people living on the north side of the river, where people were warmer in the winter but exposed to a lot of coal smoke, and the south side, where you might have been colder but didn't have much coal smoke. And thanks to Chinese government policy, there was almost no migration from one side of the river to the other.
- [45:02]
Michael Greenstone
Migration was greatly limited. And I thought, wow, this is the thing I've been searching for.
- [45:08]
Stephen Dubner
Greenstone was able to analyze data that included roughly 40,000 people living in urban areas within a 5 degree latitude range north and south of the river. The first outcome he looked at was life expectancy.
- [45:22]
Michael Greenstone
If you were born just to the north of the river, those people, they were the intended beneficiary of this policy. On average, they're living about three years less than people born just to the south. And that was such a striking finding, at least to me, that I thought, wow, I hadn't realized quite how devastating air pollution was, even though I've been working on it.
- [45:44]
Stephen Dubner
In subsequent research, soon to be released, Greenstone looked at the educational outcome of kids born between 1975 and in 1982. Here he's trying to estimate the cognitive effects of coal pollution.
- [45:58]
Michael Greenstone
Children born just to the north of The Huai river completed almost one full year less of education than kids born just to the south. And not just that, we able to observe them as adults and on average they earned about 13% less than children born just to the south. I think this is the first large scale evidence on the impacts of long run early childhood exposure at the levels of concentrations that prevail in many parts of Asia and sub Saharan Africa.
- [46:32]
Stephen Dubner
So how bad is this news? Or maybe a better question to ask, just how damaging is the cognitive impact of air pollution?
- [46:41]
Michael Greenstone
We have probably been understating the losses from air pollution by about 50%.
- [46:47]
Stephen Dubner
But then some kind of good news
- [46:50]
Michael Greenstone
that would imply that the benefits of reducing air pollution are 50% larger than we realize and would justify more stringent environmental regulations.
- [46:58]
Stephen Dubner
High polluting countries, especially China, have been pushing hard to lower air pollution. As recently as 2013, the particulate matter level in Beijing was over 100 micrograms per cubic meter. Remember, the level over a 24 hour period recommended by the WHO is under 25. But by 2018, the average level in Beijing had fallen to just over 50. And it has continued to fall across the country.
- [47:27]
Michael Greenstone
And if you take my estimates literally, they imply that a child born in 2018 relative to a child born in 2013 will live 1.4 years longer.
- [47:40]
Stephen Dubner
Greenstone says China's trajectory is much more dramatic than ours.
- [47:45]
Michael Greenstone
The United States accomplished nothing like that so quickly after the Clean Air Act.
- [47:49]
Stephen Dubner
And as an economist who's done a lot of work on environmental policy, he's been disappointed with the US Government's approach to the broader issue of climate change.
- [47:59]
Michael Greenstone
The Clean Air act was really focused on reducing pollution locally in parts of the country where air pollution concentrations were very high. CO2 is a totally different ball of wax in the sense that it is a global pollutant. The impact of emitting a ton of CO2 in Fresno is exactly the same as emitting a ton in Bangor, Maine. I think the United States is an extraordinary outlier in the international arena in terms of its difficulty in recognizing and developing a coherent strategy for confronting climate change. The United States is the only country in the G7 that does not have a coordinated national climate policy, and that's striking.
- [48:42]
Stephen Dubner
We called Michael Greenstone to ask what he thinks about the state of environmental regulation under the Trump administration. He pointed us to a recent policy change whereby the Environmental Protection Agency will no longer consider the health benefits of reduced pollution in setting clean air regulations. Greenstone said the Trump administration has taken what I think will go down in the history books. As a dramatic step into the past. The consequences, he said, will be dirtier air for my children and myself and everyone else to breathe and more greenhouse gases that will increase the amount of climate change that the world has to confront. I've always wondered why the conversation about climate change hasn't been more of a conversation about pollution. I've also wondered if the climate change conversation might not have become so ideological if it were more about pollution. The evidence for pollution's impact, the long standing evidence about the physiological damage and what we've been hearing today about the cognitive damage. That evidence is so persuasive that it's hard to imagine any right minded human not wanting to fight that fight. It isn't just progressives or Democrats who want want clean air and water. Some of the strongest willed naturalists and preservationists have historically been politically conservative. No one wants their babies or grandparents breathing polluted air. Edson Severnini Again, I think making the
- [50:10]
Edson Severnini
argument that it affects people in their daily lives. You know, it could be their own productivity or their children's performance in school or or their children's performance in sports that they're playing outside. All of this should be really talked about more often when it comes to energy and environmental policy.
- [50:30]
Stephen Dubner
Talked about may be like the level
- [50:33]
Edson Severnini
of particulate matter in the air today is above the recommended World Health Organization guidelines. You know, it's a matter of making sure people understand the consequences because it is sometimes not feasible.
- [50:47]
Stephen Dubner
If your child has an important test today or you're giving a big presentation at work, you might want to consider rescheduling.
- [50:54]
Edson Severnini
You go for a walk and you don't see it.
- [50:57]
Stephen Dubner
Depollution the Supreme Court will be delaying oral arguments until next week because of a high particulate matter count in Washington, dc.
- [51:05]
Edson Severnini
But you know, in economics we always say like if you have a problem problem, you tackle that problem directly. It's much more efficient.
- [51:21]
Stephen Dubner
Thanks to Edson Severnini, Andrea Linose, Michael Greenstone and Stefan Hiblick for telling us about their research today. Thanks to Angela Duckworth and Steve Levitt for playing brain games with us. Most of all, thanks to you for listening. If you love Freakonomics Radio, please recommend it to someone you know. We appreciate your spreading the word. We will be back in a few days with a new episode. Until then, take care of yourself and if you can, someone else too. Freakonomics Radio is produced by Renbud Radio. Our email is radioreconomics.com youm can get the entire archive of Freakonomics Radio on any podcast app if you would like to to read a transcript or the show notes, you can find that@freakonomics.com this episode was produced by Zach Lipinski and updated by Dalvin Abuaji. It was mixed by Jeremy Johnston. The Freakonomics Radio Network staff also includes Augusta Chapman, Eleanor Osborne, Ellen Frankman, Elsa Hernandez, Gabriel Roth, Hilaria Montenacort, Jake Loomis, Mandy Gorenstein, Pete Madden and Teo Jacobs. Our theme song is Mr. Fortune by the Hitchhikers. Our composer is Luis Guerra. As always, thanks for listening.
- [52:41]
Steve Levitt
Oh my God, this is hard.
- [52:43]
Michael Greenstone
Whoops.
- [52:44]
Stephen Dubner
I already blew that one. I sent those people to their death.
- [52:48]
Angela Duckworth
Okay, now I feel like so dumb.
- [52:55]
Edson Severnini
The Freakonomics Radio Network the Hidden side of everything
- [53:01]
Stephen Dubner
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