The September 11th attacks: Air pollution pt. 2

Tiny Matters

On September 11, 2001, nearly 3,000 people died, many of whom were first responders. Today, World Trade Center first responders who are still alive are being diagnosed with illnesses like lung disease and cancer more often than the general population. Many scientists say the air pollution caused by the terrorist attack is to blame.

Transcript of this Episode

Sam Jones: On the morning of September 11, 2001, nineteen al-Qaeda terrorists hijacked four commercial airplanes—two left from Boston, one left from just outside DC, and the fourth left from Newark, New Jersey. The hijackers flew two of the planes into the Twin Towers of the World Trade Center, one plane into the Pentagon and the other, following a counterattack by passengers and crew members, crashed into a field in Pennsylvania.

Deboki Chakravarti: Nearly 3,000 people were killed that day, and that’s still the largest death toll from a foreign attack on American soil. Hundreds of first responders who ran to save people from the building and pull survivors from the rubble died. And many of the first responders who survived are battling illnesses like lung disease and different cancers that they seem to be getting at a much higher rate than the general population.

Sam: Welcome to Tiny Matters, I’m Sam Jones and I’m joined by my co-host Deboki Chakravarti. This is the second episode of our two episodes on air pollution.

The first one was episode 10, where we talked about what air pollution is—the different chemicals and particles in the air that we should care about not breathing in. We also covered the things that cause air pollution, and why it sticks around in some places more than others, and what that air quality score on your phone actually means. And we kicked things off with the deadly London Smog of 1952 and the major changes to environmental policy that came from it.

So I guess this is all to say that if you haven’t listened to episode 10 yet, we’d suggest you do before you listen to this episode.

Deboki: Today on the show, we’re mainly talking about health impacts of air pollution from the September 11th attacks and less about the pollution itself.

The scene at the Twin Towers that day was surreal. I was 10 at the time, I was watching it on TV, and I still really don’t know how to describe it. Even if you weren’t in New York City or the US, or even born at the time, you’ve likely seen the pictures of people caked in a thick dust—the airborne remnants of the destruction.

Sam: Exposure to that extreme amount of dust was almost instantaneous and had a major impact on the health of first responders, back then of course, but now years later they’re being diagnosed with diseases like cancer more often and at a younger age than people who weren’t exposed to the dust. And there are many scientists out there who have dedicated their careers to understanding why.
Deboki: Today, we’ll hear from two of them, who are both located in New York City. The first is medical oncologist William Oh.

William Oh: On 9/11, 2001, of course everyone remembers exactly what they were doing at that moment. I was working in Boston at a cancer center called the Dana Farber.

Deboki: William is now a professor of medicine at Mount Sinai and the Chief Medical Officer for Sema4, a company that uses artificial intelligence to create more personalized health care.

William: I thought it was an accident. I though some commuter airplane had crashed and had no idea—as many people did not—about the scale of the event. My whole family's from New York. In fact two of my brothers worked downtown near Wall Street. Luckily they were not so close that they were able to get out of Manhattan. I was also supposed to fly out for a meeting later that day, so the first person who called me was my sister-in-law. She called to make sure that I wasn't on one of the airplanes that left from Logan.

Boston is not a very big city and even New York City, when you look at these connections, it had just affected so many people's lives.

Sam: Some have estimated that over 400,000 people in Manhattan—including first responders of course, but also people who lived and worked there and kids who went to school there—all of those people were exposed to dust and smoke when the World Trade Center towers fell. And that toxic dust stayed for a few days, until it finally rained and was washed to the ground. I say “toxic” because it was filled with different compounds that are known or potential carcinogens.

Deboki: Carcinogens are things that cause cancer. Some of the best-known carcinogens are the chemicals found in cigarette smoke. We have a ton of data from many different people in many different environments over decades to be able to say “the chemicals found in cigarette smoke definitively cause cancer.” But William tells us that there are so many different potential carcinogens out there and that, because cancer often takes many, many years to develop, pinpointing the carcinogen or carcinogens that cause it is very difficult.

Sam: The air pollution on September 11th was different from most air pollution exposures because tons of these carcinogens were released into a very narrow geographic area all at once. These carcinogens came from the plane itself, in the jet fuel, for example—but also from the building. Building materials are often filled with things like asbestos and glass fibers and other particulate matter, and no one would have been exposed to if it weren’t for the attack.  

Deboki: In 2009, William relocated from Boston to New York City, and began his current position as chief of hematology and oncology at Mount Sinai. Not long after arriving there, William was seeing first responders who were receiving care through the World Trade Center Health Program, which provides free medical monitoring, treatment, mental health services, and benefits counseling for 9/11 responders and volunteers.

William: One patient in particular stood out. It was probably about a decade after the event. And he was only in his early thirties when he was exposed. And he was now in his early forties. And he told me a story about right after his exposure, he had to pee every 30 minutes for years. Now that happens in some men in their thirties, but that's more common as you get older because your prostate for example gets larger or you might get an infection, but it's pretty unusual.

There was something not right and it coincided exactly with his exposure. He was a police officer. Now, usually men in their early forties would not be screened for prostate cancer, but two things led us to screen him for prostate cancer. One is the exposure and the other was, you know, his really dramatic symptoms.

Sam: So they performed what’s called a PSA test or prostate-specific antigen test that looks for the antigen protein in the blood. They found this man’s levels were really high, which is a sign of cancerous tissue in the prostate. And a follow-up biopsy confirmed that it was cancer.

Fortunately, this man’s story has a happy ending. William told us his cancer treatment was successful and he ultimately moved away. But William felt strongly that this man’s case of prostate cancer was caused by his exposure to the dust on 9/11.
William: There was some exposure here that was not normal and may or may not have been associated with this particular patient's cancer, but we also knew some epidemiological data was coming out around the same time, which is prostate cancer was one of the cancers that was clearly elevated compared to matched controls. So that's the story that led us to look at this question more deeply.

Deboki: Years later, in 2019, William and his colleagues published a paper showing a link between 9/11 dust exposure and prostate cancer.  

Wiliam: So we did two things in our paper. We looked at cases and controls of men with prostate cancer who were exposed versus not exposed.

Deboki: They compared the expression of different genes between the groups and found that people exposed to the dust on 9/11 showed increased expression of genes involved in an immune system pathway that causes inflammation. Inflammation is one of your body’s defense mechanisms, and it can be really beneficial because it protects you from infections and injuries and even speeds up healing if you get a cut or bruise. But extended or excessive inflammation can cause more harm than good and has been linked to cancerous cell growth and tumors.

William: Then the second thing we did was we had some dust from our colleagues at NYU. They had the foresight to save some of this dust. And in a closed chamber experiment, exposing rats and looking at immediate effects and distant effects, what's remarkable to me about this is that in fact, those rats breathed this dust, it wasn't injected into their prostates. In fact, our colleagues weren't even interested in the prostate. They were not gonna look at it. Why would you look at the prostate? It's so far away from the lungs. And yet when we looked at the control animals compared to the exposed animals and we looked at their prostates, their prostates had quite a lot of inflammatory changes and immune changes.

Sam: And in these rats exposed to the dust from 9/11, William and his colleagues found that an immune pathway that was affected matched the one affected in the first responders with prostate cancer.

William: Now again, this doesn't prove that that pathway was the key one, because these are very complicated questions with a lot of exposures. But that is why I think this paper started to give us some insight into maybe a link as to how breathing in the dust might have led to inflammatory changes to the prostate that might have driven prostate cancer in a very specific way.

I think are three components that are really critical to this particular story. The first and foremost is that these men and women are heroes and they put themselves in harm's way to help find survivors and to help respond to this terrible tragedy. And we have an obligation to really help them as individual patients. The second piece is to understand why this environmental exposures might lead to prostate cancer. And this gets at something that's really important which is we don't really know what causes prostate cancer. In fact, we don't know what causes a lot of cancers.

Of course there are certain risk factors—we know you have to have a prostate, it seems to get more common as you get older, and it does run in some families, but the majority of risk seems to be environmental. But what does that mean? What in our environment impacts risk? Are there certain elements, for example, of the chemical exposures that might still be increasing the risk of some people getting prostate cancer or other cancers?

And the third reason is to understand how better to treat patients who get these cancers. It is our obligation to understand what happened to these particular men, but also to learn from this event so that we can identify better therapies for the future.
Sam: William says he’s optimistic that they will continue to learn more that will help these patients.

William: We have to keep using science to drive what we do for patients’ health. I think the message here is, better days to come with regard to understanding how environmental health impacts human health.

Deboki: Now let’s travel down Manhattan, about 4 miles south of Mount Sinai, to New York University’s School of Medicine, where Anna Nolan is a professor of environmental medicine.

Anna Nolan: I do recall walking to work that morning. It was a beautiful day. I came to work and we were doing our usual pulmonary fellow things like we were setting up for bronchoscopies and all sorts of things. And then we heard that a plane had hit the trade center. And then people were trying to rationalize, oh, maybe it was just an accident or maybe it was all sorts of other things that could have happened. And then we realized that the traffic had stopped on the highway, which we could see outside the window of the bronchoscopy suite.

And then we noticed that just at the point where the cars were starting at the extreme distance of my view that there were no cars, they were just ambulances. We finished up what we were doing and we came outta the room and we heard that another plane had hit the other tower. From there it was just, uh, the day kind of progressed and we're waiting for patients and to see what was gonna happen. And it just got worse and worse.

Sam: You might remember that William mentioned 9/11 first responders don’t seem to be getting lung cancer any more frequently than the general population, which is surprising and not fully understood. But just because they aren’t more likely to get lung cancer doesn’t mean their lung health wasn’t impacted.

Deboki: Anna told us that all of the chemicals that spewed from the fallen, burning building material and planes made the air quite acidic, severely irritating peoples’ eyes, mouths, throats and lungs, and that concentrations of particulates—those tiny pieces of things like soot floating in the air—were extremely high.

Anna: It's more typical of what would be found in a very brisk wildfire where you're close to the smoke and other particulates. So it was of that concentration for many, many hours, less like what you would be exposed to in your typical urban environment.

Sam: Anna and her colleagues were studying the lung function of 9/11 firefighters, and they noticed a huge range in what they were seeing.

Anna: We noticed that not all the patients were behaving the same way. Some firefighters lost lung function while others lost less. And there was another population that stayed healthy throughout all of this. And we were curious what other pathways might be important to this.

Sam: What they found was that different cardiovascular risk factors like being overweight, having high cholesterol, high glucose were linked to loss of lung function. So in other words, being exposed to particulate matter is bad for your lungs, but if you add in certain cardiovascular risk factors on top of that, the risk to your lungs is greater.

Why does knowing this matter? Because it can inform life-saving preventative care.

Anna: For the first responders and for individuals in general that might be exposed to high particulates, those that are close to wildfires or those that are deployed in areas where there are burn pits and other things, those individuals particularly have to pay attention to their other risk factors of disease specific to their vasculature. And it's not to say that they aren't already doing so, but that's just something that they can potentially treat early.

Deboki: Let’s say you’re a firefighter in California, a place where there are already a lot of wildfires and with climate change there will only be more. The risk to your lungs is already pretty high because of all that particulate matter you’re exposed to. And if you have, say, high cholesterol, your risk is even higher. You may not be able to limit your exposure to particulate matter but you can do things to lower your cholesterol.

Anna and her colleagues have now completed a clinical trial with 9/11 firefighters who were put on a specialized diet that was lower in calories but rich in what are considered healthy fats like olive oil and the ones in avocados and fish. The researchers found that these firefighters lost weight and that certain aspects of their lung function improved.

Sam: I think that that research really nicely ties in with what William said about how there are better days ahead when it comes to our understanding of how environmental health impacts human health. We have people like William and Anna who are studying the long term impact of this brief, extreme exposure, but then we also have experts like the ones we spoke with for episode 10 who are studying the impact of ongoing exposures. And the goal for every expert we spoke with is to learn things that can then influence policy or medicine or both and improve human health.

Deboki: That's some good stuff.

Sam: It is some good stuff.

Deboki: Okay. So I think it is time for our Tiny Show and Tell.

Sam: Absolutely.

Deboki: Sam, do you want to go first?

Sam: Sure. So I think that my tiny show and tell today is pretty relevant for today's episode, particularly what we learned from William. So scientists have recently unfrozen cells from rat testicles that have been frozen for over 23 years and they found that when they implanted those cells in mice, they actually started producing sperm. If adults are diagnosed with cancer, they can have sperm samples frozen before they go through chemotherapy, because chemotherapy it's used to kill cancer cells, but it's not very specific. So it's also going to kill other types of cells like the ones in the testicles that make sperm.

So if someone wants to maybe have kids through IVF one day they'll have their sperm frozen before they go through chemo. But for kids who are diagnosed with cancer, they haven't gone through puberty. So they're not producing sperm. So freezing sperm is not an option. So then there's always that concern that later on in life they'll want to have kids, but they will be infertile and they just won't be able to. So finding that—again this is in rats and mice—but finding that testicular cells that were frozen for over two decades will still produce sperm if they're implanted, if that translates in humans, that would be huge.

Actually some clinics have started removing and freezing tiny samples from kids who are about to undergo chemo, hoping that this will be the case that'll actually work. And there's at least one clinic, which is located in Belgium that has been approved to do the re-implantation surgery.

Deboki: Interesting. So did they save these cells for this experiment? Was this a 20-year long experiment?

Sam: So I don't think so. I wonder if the samples were saved more or less because there could be a variety of experiments they might want to do with them down the line. I know that people freeze samples on purpose to just kind of see how long they'll last, how long they can retrieve different proteins or do some form of genetic sequencing or whatever. So I don't know if this was kind of a thing where a bunch of samples were just frozen for whatever purpose in the future. But yeah, I mean, 23 years, that's a really long time for something to be in a deep freeze and then you re-implant it, and all of a sudden these mice are producing sperm. It's amazing.

Sam: Okay. Are you ready for your tiny show and tell?

Deboki: Yeah. yeah.

Sam: Okay, cool.

Deboki: Yeah. So today I want to talk about an experiment that hasn't happened yet, but that I'm really excited for. It is years to a decade away, but it's one of those things that knowing that people are working on this just makes me really, really happy. I am talking about the Mars sample return mission. So this is a collaboration between NASA and the European Space Agency, and the idea is basically we've already sent Perseverance to Mars and it is collecting these rock samples, which is already really wild, that there are people who are just like controlling this rover to get it to collect rocks, to do chemistry experiments on. Already my mind is blown by that.

But then we want to study those rocks. Well, not we, but the scientists. They want to see those rocks. They want to be able to work with them. So somehow we have to be able to get those rocks from Mars back to Earth and for some reason, my brain always kind of skips that step. I'm like, yeah, we got Mars rocks. Of course, we can just look at them, but no, we got to figure out how to actually bring them back here. So there's this whole plan in place that people are working on, where we're going to send a lander to Mars, that lander is going to then send out a rover to get the samples from Perseverance. Then it's going to load those samples into a rocket, get that rocket up into Mars' orbit and then that is going to somehow eventually get retrieved and sent back to Earth.

All of those pieces are already really incredible to me. If it all comes together, I think that's going to be the first rocket that we've launched off the surface of Mars. This whole thing it's supposed to involve two missions. The first one is planned for at least from the NASA website, it says the mid 2020s, I think is what…

Sam: Okay. Which is three years, two, three years away.

Deboki: Yeah. I forget when our next Mars launch window is, but I assume it would be probably for that. That's to get the samples off of the planet and into Mars' orbit. Then the second mission would be to actually get it from the orbit back to Earth. I think that's supposed to be 2030s. I don't know what the timelines of these actually are going to turn out to be. But I just, again, like I said, I love thinking about the fact that this is a thing people are working on and that somehow we're going to get Mars samples that we've collected to Earth. I just think that's so cool.

Yeah. It's a lot of anticipation.

Deboki: Yeah, yeah. Yeah.

Sam: Also because it's so far, I mean, so far in the future is all relative, but it is a long time. To just even think about how technology will improve, in a way it's kind of awesome that it's going to be 10 years. I mean, I would love if we could get them immediately and then get more rocks immediately. I wish it was an instantaneous thing because you could just be getting data all the time, but it is this thing where you're like what more can we learn? Because I feel like we are learning things about our universe, and about Mars, and the moon and apparently black holes as well. So I'm like, what else will we know by the time those samples arrive That means that we can learn even more cool stuff?

Deboki: Yeah. I love it because it's such a weird combination of things that are both so simple and then so technologically complicated. They're just collecting rocks, which is the thing that, I don't know if you did this, but I did this when I was little. You'd go to the playground. You'd just pick out the cool rocks, but they're doing this on such an incredibly advanced... They're doing this on another planet. That is so cool. Hopefully one of these days I'm going to get to read about some paper that came out where scientists are talking about martian rocks that they directly worked with that were collected from the rover.

Sam: How crazy will that be? I mean, for scientists who are able to I say touch those rocks, but they probably won't be able to even directly hold the rocks because they don't want to contaminate them.

Deboki: Yeah, delicate.

Sam: But just be in the presence of something that was on Mars and that took 10 years to show up. It's like don't screw those experiments up.

Deboki: Yeah. Yeah. One of my favorite stories from the moon missions is that they collected these lunar rock samples and then they were like, well, we got to make sure that this is safe. So they fed it to different animals, including cockroaches to make sure that there wasn't anything toxic in there. I think almost all the animals were fine that were exposed to it. But it's just one of those things where we're like, oh, we got the space rocks. What do we do now?

Sam: Giving us a lot to look forward to.

Deboki: So as always, we'll have links to these show and tell stories and websites and relevant materials in our episode description.

Sam: Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society. I’m your exec producer and host, and I’m joined by my co-host Deboki Chakravarti.

Deboki: This week’s script was written by Sam, edited by me, and fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design are by Michael Simonelli and our artwork was created by Derek Bressler.

Sam: A big thank you to William Oh and Anna Nolan for chatting with us for this episode.
Deboki: As always, if there are some tiny things that you think matter and that you’d love us to explore in an episode, shoot us an email at You can find me on twitter at okidoki_boki

Sam: And you can find me on twitter at samjscience. We’ll see you next time.


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