Erika: [00:00:00] Welcome to the ATS Breathe Easy podcast, here live at the American Thoracic Society meeting in Orlando, Florida. I'm your host, Erika Moseson, a pulmonary critical care doctor in Portland, Oregon, and the host of the Air Health, Our Health podcast. We are here today to talk about clean air policy in cities and how it can improve health.
So please, won't you guys introduce yourselves?
Emilia: Thanks, Erika. My name is Emilia Simeonova, and I am a professor at the Johns Hopkins Carey Business School. I, uh, do a lot of research in economics and health economics, including environmental health.
James: I'm James Scales. I'm a senior research fellow at Queen Mary University in London.
Uh, by training, I'm a physiologist, um, and my work is in air pollution exposure studies. So I take people with asthma, children, expose them to air pollution, monitor their health effects.
Erika: Excellent. Well, we are actually gonna start with you because we're here today to talk about a session that you're chairing later today about three cities and the choices they've made that may have actually impacted health by [00:01:00] reducing air pollution.
James: Um, yeah. So it's a symposium on clean air zones. Clean air zones comes in different forms. You have congestion zones such as Stockholms and New Yorks, which the presenters will talk about, where cars have to pay a fee to enter. The theory behind it is paying a fee is not pleasant, less cars go into that area, therefore less cars, less pollution, improves health.
We'll then have a talk from Helen Wood. She talks about London's clean air zones, which are slightly different. They- the aim is to improve the, the, the vehicle fleet in that area. So you, if your car doesn't meet certain regulations, you pay a fine. Um, in London, that's about 10% of the transport through London pays a fine, and the aim, the sort of theory behind that is improve vehicle fleet, reduce emissions, and then improved health responses and effects that way.
Um, so yes, we're going to get a cross-section of the first [00:02:00] congestion zone presented by Emilia in Stockholm, the world's largest one now in London and then, yes, the newest and most possibly controversial one in New York at the moment.
Erika: Absolutely. Well, do you want to tell us about, um, your research in Stockholm and the health effects that we're seeing?
Emilia: Absolutely. So, um, my, my... The Stockholm Congestion Pricing Zone is the earliest from the experiments that we're gonna talk about here, and I think it's, um, it's, um, it's, it's unique in many ways. Um, well, first of all, it's in a city that nobody would think is very polluted. So, um, you would think, well, we probably shouldn't be finding anything there because it's already a very low pollution sort of, um, lots of parks, very environmentally friendly.
But we do find, uh, strong effects not only on, um, pollution, but in particular on children's severe asthma attacks [00:03:00] because of the Stockholm Congestion Pricing Zone. One of the, uh, themes that I also like to emphasize about that is that as a- Together with some of the other, like the New York congestion pricing zones, for example, um, the main idea behind the Stockholm CPZ was not to improve health.
M- maybe because people just didn't think there was anything to improve. So the idea was just to reduce traffic and to reduce wait times, to reduce congestion. Um, there was some, um, attention given to pollution, but nobody really took the next step into, oh, that might improve air quality to, to an extent that it's going to be impactful on children's health.
And so, uh, one of the, um, important takeaways from, from, from our work, I think, is that there's downstream effects from these policies that hinge on health and are really big that nobody's really thinking about. And so the more we think and the more experiments like this we have, the more research we [00:04:00] do, the more we found out, find out about perhaps even our, um, you know, uh, regulations about what con- what we consider clean enough that may need to be altered.
Erika: Absolutely. What other health effects did they see in the other city studies?
James: It, it's, to a certain degree, it's been whichever direction you've thrown y- thrown your net, you've found something to a degree. Um, a lot of the challenge is data availability, what data is available. Um, we've seen redu- reductions in hospital admissions, emergency hosp- uh, hospital admissions. Um, London, uh, the talk later presents improved lung growth in children in central London compared to a control group.
And you also see the second- we're seeing, starting to see some secondary level behavioral changes of increased physical activity, uh, increased green, green space use and things like that, that just come from being in a nicer [00:05:00] environment because possibly, possibly because of, uh, reduced traffic, reduced risk of noise and
Erika: all of that sort of stuff.
Absolutely. Well, I think it highlights a lot of, um, what we know about air pollution, that the lower you go, you keep finding the benefits and, you know, especially for kids in these vulnerable developmental windows. So you mentioned that this wasn't the intent of the policies, but in all of these situations it was a natural experiment, right?
How did researchers kind of jump on that and, and know to take advantage of these natural experiments, and how do they, how do they design that or capture that?
Emilia: I, I can start. Go for it. Just to, to, to, to backtrack a bit and comment a bit on, on, on what James brought up. Um, it's incredibly important that we have more data, um, and track what is happening.
So, and, and data on several fronts. Um, obviously we track, um, congestion, we track cars because, you know, we, we, we charge them so we [00:06:00] know that they, they go, they go less. But also tracking pollution, um, at the right level, the right geographic level is very important because we wanna know what's going on inside the zone rather than everywhere around.
So if you have a monitor which is, you know, 10 kilometers from the central city, then that monitor's picking up everything, um, together. So it's important to set up the infrastructure so you can actually measure properly what's going on. I think that's one of the challenges with New York as well, right?
Mm-hmm. Um, uh, we had some of this challenge in, in Stockholm, but also it's, it's, it's very important to be able to track how children's health progresses, anybody's health progresses, and that's a particularly big challenge in the US where we literally cannot track people across... And for good reasons, but maybe we should consider, you know, um, building the infrastructure a little bit, at least city-wise, to be able to, to see what, what is happening and to properly ev- evaluate these, uh, these [00:07:00] programs.
The natural experiment part is very important, because many times people will argue that, uh, well- People or children, they have these bad pulmonary health outcomes simply because they are in bad health. And they, people who live in some areas have a lot of issues. One of them is bad health, and that has nothing to do with pollution because pollution levels are so low already, they're below the thresholds.
This is some sort of correlation that we're measuring, um, that's driven by just people being ... having a low stock of health is what we will say in economics. So then you need something that will completely externally change the, the, the pollution environment with- without regard to who lives where and what their underlying health stock is, and then you measure what happens to people in, in, in that, um, after you have done that.
So that's a natural experiment, what we call, right? And then obviously you need to take into account things like [00:08:00] migration and so on. People have studied these as well. But natural experiments are the gold standard, and they're very hard to do if you don't have data. Uh, so you need to be able to track people over time, the same people, and you need to s- be able to see are they moving out, are they moving in, who's doing what, so that you can identify the effect on the correct set of treated people, um, and then evaluate it, uh, appropriately.
So in, in, in Sweden we are able to do that. In the US not so much. I think in London they were able to do it as well.
James: Yeah. So to, uh, fill out the London bit, you know, epidemiologists will tell me that there's very complicated ways of, in analyzing data sort of post-hoc. You could do interrupted time series, and there's very clever ways that you can evaluate policy.
But the ... when you don't have the data, one fairly obvious way is to collect that data yourself, and that's what CHILL did in what I think is quite a tidy and clean way. It is an experimental s- [00:09:00] study in the traditional sense. There were two arms. There was the intervention, and there's the control group, and there's a baseline measure before the intervention, and that's quite tricky to get in these natural experiments because you've s- got to persuade a funder to fund your work before the intervention has happened.
And n- we know how politics works. That intervention hasn't happened until it's been signed on the dotted line and it's been confirmed. So you've gotta g- get ... You've gotta persuade ... A funder's got to be flexible and confident enough to fund a research group upfront to collect data that doesn't at that very specific moment, doesn't really have any experimental value beyond a cohort, on the hope that over the five, six, seven years of follow-up, a study, a natural experiment grows out of that initial cohort.
so Yeah. Uh, just a, a sl- a slight nod maybe to the funder, which is not, not so- not, not something I'd normally do. Yeah.
Erika: But just kind of sounds like preparation is, is the-
James: Yeah. So yeah, the, uh, uh, as Amelia said, we need [00:10:00] the, the monitoring and things, and London does have that monitoring. Okay. But then the funder support-
Erika: Yeah
James: was invaluable up front.
Erika: And you mentioned, you know, effects like, you know, decreased asthma attacks, decreased hospitalizations. Um, you know, part of that in terms of being ready is the data is so clear about how bad particulate matter is and air pollution is for the health of children and all of us, and our vulnerable patients.
So it seems like, um, were these health effects and the magnitudes of the falls expected by all the, the people involved in the research, based on previous data? Or was there some- anything surprising?
James: we were, yeah, we were surprised by the magnitude of improvement that we saw. So take it back a little bit.
The story of London's congestion zones are we initially had a congestion zone back in, ooh, don't quote me, but probably 2008. Failed miserably. The aim was to reduce traffic flow, um, improve speed. Didn't happen. Uh, it happened at the same time that they put a particular type of bus on the fleet [00:11:00] to try and reduce particulate matter pollution.
They built, um, a diesel particulate filter in such a way that it increased NO2 pollution. So during the congestion zone, pollution went up. Health effects, well, we didn't monitor them, but- ... didn't improve, let's say it probably. Um, in mitigation of that, the, London has had to try and reduce NO2 pollution, which is a s- makes London and UK slightly u- a, a slight unique challenge sometimes.
There was then the initial low emission zone based on the same principle of improved vehicle fleet, and there was no im- we saw no improvement at all there. It improved air quality I think by about 20%, off the top of my head, PM reduced by about 20%, um, but no improved health response. And we think that was probably because it targeted only heavy goods vehicles and only a fraction of the city.
We then went into the utra- ultra-low emission zone. Started, as we evaluated that, [00:12:00] we would, we knew that reducing air quality alone doesn't necessarily produce a measurable health response, um, particularly for lung function growth. Um, so af- the, the, uh, after, at the end of the CHIL study, after five years, we saw, um, an improved, uh, accelerated lung growth to catch, for the intervention cohort to catch up from s- stunted lung growth initially to equivalent to the control group at the end of the intervention.
I think, I think we were all slightly shocked by that. I think the catch-up i- was, off the top of my head, was in the region of about 60 mil of FEV1, which is a fairly substantial growth increase, um, over four years. So yeah, we were surprised. And part- and i- we've been surprised by the conf- the, the triangulating founders, to see the, see the story across the increase in physical activity, the increase in mental health, uh, h- mental health and cognitive scores.
We've seen it across whichever direction we've looked at [00:13:00] as well. So probably the cle- the clarity of the message has surprised us. Yeah.
Erika: So what advice do you have for other, you know, cities or health workers in those cities who are looking to help their own communities get the win-win of decreased traffic, which we all hate, uh, decreased pollution, and improved health now that you've seen it unfold?
Emilia: Um, I think the takeaway is, is that, We were also surprised by what we saw in Stockholm, by the way, um, and it was much bigger than we anticipated. Um, so one takeaway is, is, is lower is always better. Less is better. Uh, less is more. And, uh, and I think that, um, you know, I, I do understand there is a, a very rational and, and justifiable, in many cases, opposition to clean air zones, congestion pricing zones.
Um, one thing that, um, uh, would- I would advise [00:14:00] anyone to do would be just to educate, educate, educate. Um, uh, including, um, the health effects, which people, um, regularly underestimate and don't even e- don't even include in the, in the discussion. Some of it is because you can challenge a lot of the research With not so good reasons, but you can.
But there is now some, some studies that are very well done, and there is nothing you can, you can really say. The results are there. Less is more. Um, but educate people about that, the public, the politicians, the policymakers. Uh, the, if, if you include the savings, uh, from, uh, from health improvements, uh, the, the math, you know, the cost-benefit analysis just it's, it's out of the, of the ballpark.
It's completely, you hit it out of the park. So, um, include that. Talk about that, you know? And, a- a- and, and, and, and educate people. Um, have, show them examples from elsewhere. Um, and, uh, and, [00:15:00] and, and people are smart. They will, they will realize that's a good thing. But also make sure you do it equitably.
Erika: Yeah, absolutely. That's very important. Like, when you're talking about lung growth in kids, I mean, that's the cost avoided of a lifetime of potential disease. Exactly. Mm. And, you know, we all love our kids in our communities. We all want them to breathe clean air and enjoy parks. So hopefully the local human connection can make it more viable.
Yeah.
James: Yeah, absolutely. I would say, uh, the, the message to policymakers we've seen the, the, the relative lack of success from London's low emission zone and then the relative success of the U- ultra low emission zone shows that interventions need to be bold and they need to be ambitious. It's small area interventions don't create that drop in air pollution.
You need to hit the whole vehicle fleet, everything going through the city, and you need to make sure it covers the whole city. Um, Emilia was telling me the other day that one of the strengths of Stockholm is that the, with [00:16:00] the city being basically an island- Island, yeah ... all the entrances exits are, are, uh, are c- are covered by the zone, and it has a real impact on the whole city.
And then the same, uh, with, uh, the same with the way the ULEZ was structured, it impacts the whole of the City of London. I, I must admit, I, I look at the likes of New York, and you sort of wonder, will people find other ways around it? Are we going to just displace that air qual- air pollution, um, or are we gonna reduce it?
Probably a bit too early to tell, I guess. Um, so that's the message point to policymakers. To researchers, I'd say it's really important that we monitor these things. We don't know if they work or not unless we measure before and after. Um, and then we can then provide the evidence to the policymakers to be bolder and be stronger in the future.
Erika: Absolutely. Well, I wanna thank you both for this incredible science that you've done that's helping us understand much better about, uh, how to make our, uh, patients and communities, um, safer and [00:17:00] healthier. So thank you, and I'm sure your session this afternoon is gonna be incredible.
Emilia: Looking forward to it.
James: Me too.
Emilia: Thank you, Erika.
Erika: Yeah. Thank you for joining us on another ATS Breathe Easy podcast.