When Is a Natural Disaster Good for Your Health?

Hurricanes. Wildfires. Earthquakes. Flooding. Natural disasters are a part of life. And with climate change, they’re probably going to keep getting worse. For a lot of people, disasters have meant having to leave their homes, either to avoid danger or to start over afterwards. And starting over can mean a lot of different things — moving to a new city, maybe finding a new job and new friends, and possibly even some unexpected changes in your health.

From the Freakonomics Radio Network, this is Freakonomics, M.D.

I’m Bapu Jena. I’m a medical doctor but I’m also an economist. And in each episode, I dissect an interesting question at the sweet spot between health and economics.

Today: how is our health affected by the place we live? Where are the greatest inequalities? And is there an approach to changing these inequalities that could actually work?

For someone who researches questions like this, a natural disaster can be an ideal scenario for a study because these disasters often force a lot of people to move all at once. I know that sounds strange — no one wants people to lose their homes. But when that happens, some insightful economists will want to seize the opportunity to learn something new. Tatyana Deryugina and David Molitor and are two such economists. Tatyana and David are colleagues at the Gies College of Business at the University of Illinois at Urbana-Champaign. They wanted to understand how where we live affects how long we live and they realized that natural disasters could help them do that. But they needed to pinpoint an event that was long enough ago that health effects would be noticeable, but recent enough to have reliable health records, and with a population large enough to be able to study.

REPORTER 1: August 30^th, 2005. And this is Nightline.

It wasn’t hard to find.

REPORTER 1: Tonight, what the city of New Orleans feared most may be coming to pass.

REPORTER 2: The scene is nothing short of apocalyptic.

RESIDENT 1: We want help. No food, no water, helicopters flying over our heads. It’s ridiculous.

David MOLITOR: Hurricane Katrina is one of the largest environmental catastrophes on record in the United States.

That’s the economist David Molitor.

MOLITOR: According to official estimates, the storm caused over $150 billion in damages. It killed nearly 2,000 individuals. And in addition, the storm displaced more than a million residents from their homes across the Gulf Coast region.

RESIDENT 2: I mean everything is just flooded. Everything. The whole city. This is like a city under siege.

I can still picture the images I saw on the news: A woman carrying bottles of water as she swam through oily floodwaters.

REPORTER 3: Today in some areas the water is now 20 feet deep.

Families stranded on rooftops.

Aaron BROWN: It’s now a race against time to find survivors. Where to take them is the problem.

The Superdome packed with 30,000 people who’d been evacuated from their homes.

But here’s the thing. Part of what made Hurricane Katrina so catastrophic was that New Orleans was already struggling when it came to health. Back in 2005, the year Katrina struck, Louisiana had the third lowest life expectancy of any U.S. state — 72.5 years, compared to 78 years for the U.S. overall.

So, what happened to the people who moved away because of Katrina and never came back?

Katrina displaced about half of the 500,000 people living in New Orleans before the storm and another 750,000 from across the Gulf Coast region. This was the single largest migration within the United States since the severe dust storms of the 1930s that forced an estimated 2.5 million families to flee the Great Plains. Katrina survivors were evacuated to Rhode Island, Ohio, California, Texas, Arkansas, and about 30 other states.

MOLITOR: Hurricane Katrina provides a natural experiment of how the regions to which people move shape their long-term health outcomes. Not only can we try to understand what was the long-term health impact of the disaster, but how did the destination regions shape those long-term health outcomes.

It’s a smart idea. Here we have this huge group of people who all left the same place at the same time and moved to different parts of the country. If we want to know whether the place we live affects our health, you couldn’t really ask for a better approach. It’s a very, very small silver lining to a nightmare situation.

David and Tatyana published their research in the American Economic Review in 2020. They focused on people in Medicare because that’s where they had the data — so, almost everyone who’s 65 years or older, along with people who have long-term disabilities. They identified people who were living in New Orleans before the hurricane and gathered data about their health, including their date of death for those who died in the years after the storm.

That’s a crucial piece of information because longevity is a really useful barometer for overall health. People who live a long time typically have fewer serious health problems throughout their lives.

The data included people who stayed or returned to New Orleans after the storm and those who moved away. All that information meant that the researchers could study how life expectancy changed for people who were living in New Orleans before the storm and moved right afterwards compared to what their mortality would have been if the storm had never happened.

In order to figure that out, first they looked at the mortality rate among all the storm survivors and compared them to several cities with similar income levels, population growth rates, and racial composition as New Orleans before Katrina — cities like Baltimore, Detroit, Birmingham, Alabama, and a few others.

By the way, by “mortality rate” I just mean the percentage of deaths in a given population, during a given time frame.

MOLITOR: The first thing that we found when you compare people living in New Orleans to these other, similar cities, leading up to the hurricane, the mortality rates of these two groups were moving in parallel.

In other words, before the storm, the mortality rate in New Orleans was about equal to that of those other, similar cities that I mentioned. That will become important in a moment.

But first, the annual number of deaths in New Orleans spiked in 2005, the year of the hurricane. That’s predictable. A lot of people died in the storm. But then, David and Tatyana saw something surprising in their data.

MOLITOR: Starting in 2006 and 2007, that initial spike in mortality among the New Orleans cohort disappeared. And in fact, the mortality rate dipped below the pre-hurricane trend in New Orleans, suggesting a mortality reduction.

There is a kind of rhyme or reason to this. If the hurricane led to the deaths of the people who were already the most vulnerable, then we’d expect the surviving population would, on average, be healthier and we’d expect that their mortality rates would be lower. But that possibility doesn’t explain all of what the researchers found in their analysis.

MOLITOR: So, what’s particularly surprising is if you take the people living in New Orleans before the hurricane, the probability that they survive for up to eight years after the hurricane, including the initial shock of the hurricane, is actually a mortality reduction, suggesting that the hurricane caused more people to be alive eight years after the storm than would have happened.

Now, those similar cities I mentioned a moment ago? For Tatyana and David, they were like a stand-in for New Orleans if Katrina had never happened. The researchers couldn’t directly compare the mortality rate between those who moved and those who stayed after the storm. There was so much going on in New Orleans — too many variables — that could have affected the health of people who stayed. But by comparing the mortality rate of Katrina survivors versus those in other cities, they could see something strange going on. Before Katrina, the mortality rates in New Orleans and those comparison cities were similar. But eight years later? The Katrina survivors were living longer.

To give you a sense of the actual gain: someone who was age 65 at the time of the hurricane could expect about an extra year of life because of the hurricane. I bet you didn’t see that coming! Who would have thought that people who survived Katrina would end up living a longer life?

But that finding was comparing all the Katrina survivors with the comparison cities. It wasn’t clear who was living longer. The movers who moved to other parts of the country? Or the stayers, who stayed behind in New Orleans? Or everyone? David and Tatyana looked into two possible explanations for the longer lifespan.

MOLITOR: The first is rebuilding. So, there was a lot of rebuilding in New Orleans. It could be that if you replace the old infrastructure with new organizations, new systems, new infrastructure, that those improvements could have led to health improvements, even among those who stayed in New Orleans. A second possibility is health improvements through relocating to places that are better for your health. Now, these two channels are not mutually exclusive. It could be that both of them matter.

David says there are some other possibilities as well. Maybe some of those who were evacuated moved in with family, which meant more attention to their health needs. Survivors may have become more resilient because of the storm, leading to better health. But to focus on the effect of place — in order to decipher who was living longer, the movers, the stayers, or both — the researchers focused on just two major factors: rebuilding and relocating.

MOLITOR: When we looked at people who chose to stay in New Orleans after the disaster, we don’t really see any change in their health outcomes, suggesting that at least in the very short run, this rebuilding process, which took years, does not appear to have led to these immediate health improvements.

So, it wasn’t the people who remained in New Orleans after Katrina who were living longer. Rebuilding the city didn’t impact mortality of those who stayed behind, at least in the eight years following the storm. That means, then, that the people who lived longer as a result of the storm were those that moved to different cities.

What about the people who left New Orleans? Were they all living longer? If not, who was? Well, they fell into two groups: some people moved to areas with longer average life expectancies, and some people moved to places with shorter ones.

MOLITOR: What we find is that the subsequent mortality is much lower among movers that move to relatively low mortality regions compared to those who moved to higher mortality regions. In fact, the relationship between the migrants’ own subsequent mortality and the mortality rate of the destination region is on average, nearly one to one.

So, if someone was living in New Orleans during the Hurricane and they moved to a place where people lived 5 percent longer, on average, than in New Orleans, that person ended up living about 5 percent longer than they would have if Katrina had never happened and they’d never moved. The study was a clever way to show that, when it comes to life expectancy and health, where we live really matters. And one of the surprising findings was about the age of the people who were affected by moving to a new place.

MOLITOR: One thing that was really interesting to us is this idea that does place matter later in life? Maybe it matters when you’re young, where do you grow up as you’re — as you’re growing, but by the time you’re in your sixties or your seventies, does place matter any more for your health once your health habits are mostly in place? Our study suggests that, actually, your health is still very responsive to where you live, even later in life

That finding underscores just how important place is when it comes to health. But why? Another study may offer a hint. Tatyana Deryugina, who worked with David on this study, also worked with economist Laura Kawano and Freakonomics’ own Steven Levitt on another analysis showing that the income of Hurricane Katrina survivors increased in the years after the storm compared to people in similar cities. Right after the storm, survivors were earning about $2,300 less than the average in those cities. But by 2013, that number reversed: survivors were earning about $2,300 more than their counterparts around the country. And the people who did best financially? You guessed it: they were the ones who moved away.

So, what’s going on? Why did moving have such a dramatic impact on the health and livelihood of Katrina survivors? To answer that, we need to look beyond New Orleans.

Several years ago, some researchers who study population health started looking at the average life expectancy at different stops along subway and bus routes in cities across America and abroad. It turned out to be an extremely powerful way to show how much worse health can be in one community compared to another, sometimes ones that are practically across the street from each other.

Don BERWICK: The first such map that I ever saw was of Glasgow, showing a difference approaching 30 years of life expectancy, depending on where the bus stop was.

That’s Don Berwick. Don began his career as a pediatrician and professor at Harvard. He actually started the health policy course that I teach Harvard undergrads more than 20 years ago. Don served as the administrator of the Centers for Medicare and Medicaid Services during the Obama administration. He even ran for governor of Massachusetts. Today, he’s President Emeritus and senior fellow with the Institute for Healthcare Improvement.

BERWICK: In London from the West End to East London, there’s a difference of 27 years in life expectancy when you go from six miles across that city. In the United States, it’s the same thing. If you board the subway train in New York City in midtown Manhattan, where the median income is $180- or $190,000 and most of the residents are white and few of the kids are on Medicaid, and you just travel three or four miles north to the south Bronx, where most of the people living are not white, and where half the kids are born into Medicaid, and where income is less than a third of what it is midtown Manhattan, at that subway stop in the south Bronx, your life expectancy is at least 10 years less. That’s losing about two and a half years of life for every mile you travel.

There’s another way to put these really stark numbers into perspective.

BERWICK: I once did a little calculation trying to compare it to statins. Statins are one of the most widely used medications in our country today. They’re regarded as a medical breakthrough to prevent heart attacks. There was a study in 2015 that estimated the most favorable outcomes for the use of statins, and it said that for a year on statins, in primary prevention, you gain about a day of life. Twenty years on statins, 20 days of life.

So, one of our most successful medical interventions? It may only change life expectancy by days for some people. Whereas geography?

BERWICK: It’s absolutely, and sadly, true that, with respect to health, place is destiny right now. It doesn’t have to be that way — that’s a matter of the policies and choices we make as a society — but right now where you live has a very strong impact on your health.

“Place is destiny” — that’s a striking phrase. But why? What is it exactly about where we live that has such an impact on our health? That’s coming up, after the break.

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Don Berwick, a physician and health-policy expert, has been telling us that when it comes to health, place is destiny. What does he mean by that? Why do people living in the Chicago Loop area live an average of 16 years longer than people in West Chicago?

BERWICK: I’ve frequently cited the immensely important work of Sir Michael Marmot, a world-class epidemiologist in London. And he sorts the causes into a pretty orderly list — things like early childhood experiences, the fairness and guarantees in an education system, conditions in the workplace, including minimum wage guarantees, elder care support so that people aren’t lonely in their aging years, and community infrastructures like food security and housing security and transportation and recreation. 

The categories that Don is outlining here are often referred to as “social determinants of health.” For economists, one of the big questions is whether you can really say that certain social factors are actually causing these health disparities. Let me give you an example. Are we sure that better education leads to better health, or is it just that healthier and wealthier people have more access to education?

We actually know the answer to that question. Lots of studies, by economists and others, have now shown that education does have a positive, causal impact on health. For example, some studies have used variation in the timing of compulsory-schooling laws across states to identify the effect of greater education on adult mortality. Others have compared long-term mortality differences between twins who differ in educational levels to suss out the impact of education versus family and genes. All of these studies are consistent with what we’ve seen in other countries, especially Scandinavian countries, that have made strong investments in their educational systems. But as Don points out, it’s not just education.

BERWICK: So, countries that appear to have a commitment to solidarity, mutuality, where people take care of each other, are countries that have higher health status. Once we are, as a community, committed to fairness and equity and inclusion, then the communities invest in the causal determinants of better health, like food security, housing security, early childhood supports, and so on.

As Don explains, the difference may also depend on how a country spends its healthcare dollars. You can see that when you compare the U.S. with other developed nations.

BERWICK: In most nations with much higher health status than we have, they spend about $2 for social supports for every $1 they spend on healthcare. It’s about a two-to-one ratio, that’s the norm. But in the U.S., instead of a two-to-one ratio of social support to healthcare, ours is 90 cents spent on social supports for every dollar in healthcare. In other words, less than half the investment. Now, one of the reasons has to do with the immense cost of healthcare in this country. So, we are by far the most expensive country per capita in health status. But yet when you look at the results, I think we rank about 40th in health, in longevity, about the same in infant mortality. Ratings show the U.S. often to be at the bottom of the list of the developed countries being studied. So, we’re pouring money into a health system that can’t produce health.

The federal government is starting to make more significant investments in early childhood education and housing security. And that’s crucial, Don says, because leaving the problem up to individual communities ignores the reality of how we got here in the first place. For one thing, the rising cost of healthcare has siphoned off money from state budgets that could have gone to social-support systems. But also, health inequality is a problem that has to be shouldered by all of us together because it stems from our nation’s history.

BERWICK: It has to do with the embedded inequities in the communities of the United States. This is the heritage of slavery and the persistence of racism and othering and the win-lose in this country has resulted in localities where white or black if you’re marginalized, for any reason, your outcomes in health, well-being, longevity, talent, the ability to exploit talent, are lower, they’re worse. We tolerate levels of inequality in this country that in a civil democracy ought to be absolutely unacceptable. And so, it’s no surprise to me that when people are able to move to places where their opportunities are greater, their health would improve.

This idea of being able to move to a place where opportunities are more plentiful has led to research that has already had some very meaningful results. Economists Raj Chetty and Nate Hendren at Harvard and John Friedman at Brown University have tackled this issue through a policy research effort called Opportunity Insights.

The Opportunity Insights team developed a program for people in neighborhoods where there’s typically not a lot of social mobility. They offered families help with identifying “high opportunity” neighborhoods to consider moving to, which they defined as areas where children from low-income families have gotten out of poverty. They helped resolve any credit history problems, found homes for rent, connected with landlords, and completed the rental paperwork. We all know how expensive it is to move, so, in this program, each family also received about $1,000 to help with moving expenses, including security deposits, using money from Public Housing Authorities reserved for just this purpose.

A total of 430 families in the Seattle area were included in the test program. The household income of these families, who lived in south Seattle, averaged about $19,000 per year. About half of these families served as the control group — they didn’t get help with moving, and the other half of the families did. When families got help moving, more than half moved to high-opportunity areas in north Seattle, while fewer than a fifth of the control-group families made that same move. One year after the study, almost all of the families were still at their new addresses, indicating that the move could hold for the long-term. The researchers estimated that, if the families who moved ended up staying in their new neighborhoods, the total lifetime income for their children who moved during very early childhood would increase by more than $200,000.

By the way, the program cost about $2,700 per family. That’s almost covered by the future increase in tax revenue that the economists project will come eventually from each of the high-earning children in these families.

Just to give you those results again: 54 percent of families who received basic help with navigating a move ended up relocating to high-opportunity neighborhoods, up from 14 percent of families who didn’t get that help. Raj Chetty, one of the researchers behind the program, called it, “the largest effect I’ve ever seen in a social science intervention.”

Moving vouchers aren’t a new idea, but recent research has shown that the benefits may be greater than people have realized in the past. But the real difference here was the support that people received, the hands-on help with navigating a system that is practically designed to keep out people with low credit scores, income, and education.

I think it’s helpful to know just how much moving can impact someone’s health and future. But this research — it’s also frustrating to think about. I mean, families shouldn’t have to uproot themselves to get a better shot at life. They shouldn’t have to change ZIP codes to live longer. Encouraging people to move — it feels more like a Band-Aid solution than a real one. It’s just that the bigger fix — creating a society where these divisions don’t even exist in the first place — well, that’s a lot harder. But Don Berwick and I agree that’s still got to be the goal. We can and should work toward that.

BERWICK: I want to live in a country which is fundamentally compassionate, in which when someone’s in trouble we use the tools we have to help them. I don’t think that that’s a naive approach because in fact, overall, all the boats would rise on the tide of compassion.

By the way, if you want to see how your ZIP code compares to others in terms of life expectancy, Opportunity Insights has created an amazing atlas of the entire country. It’s online at opportunityatlas.org. But if you visit the site, make sure to look not just at your own ZIP code. Look at those around yours too.

Anyway, I hope you enjoyed our discussion today. That’s it for Freakonomics, M.D. this week. You can find links to all the studies we mentioned at freakonomics.com.

As always, I’ve got to thank you for listening. It’d be great if you could give us a review on Apple Podcasts or wherever you’re listening. It does help new people discover the show.

And if you have any thoughts on the show, I’d love to hear from you. You can email me at bapu@freakonomics.com. That’s B A P U at freakonomics.com.

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Freakonomics, M.D. is part of the Freakonomics Radio Network, which also includes Freakonomics Radio, No Stupid Questions, and People I (Mostly) Admire. This show is produced by Stitcher and Renbud Radio. You can find us on Twitter and Instagram at @drbapupod. This episode was produced by Jessica Wapner and mixed by Eleanor Osborne. Original music composed by Luis Guerra. The supervising producer was Tracey Samuelson. Our staff also includes Alison Craiglow, Greg Rippin, Emma Tyrrell, Lyric Bowditch, Jacob Clemente and Stephen Dubner. If you like this show or any other show in the Freakonomics Radio Network, please recommend it to your family and friends. That’s the best way to support the podcasts you love. As always, thanks for listening.

BERWICK: We have great epidemiology, great research, and I wish we could take a breath and go back to the pursuit of health and wellbeing based on the facts, on science, in the truth, instead of myths about others.