00:02:15.740Good. So today we're going to be talking about environmental pollution and all things related
00:02:21.040to that. So before we do, I think it might be helpful for you to first explain to the listener,
00:02:26.200what exactly do we mean by environmental pollution? And also why does that even belong
00:02:31.860in a conversation around longevity? I mean, look, I think at a literal level,
00:02:36.840environmental pollution is the introduction of harmful substances or harmful forms of energy,
00:02:42.240which we'll talk about into the environment. And I think the word harmful is doing a lot of work
00:02:47.480there. We're not just talking about something being unnatural, man-made, or detectable. That
00:02:52.360wouldn't kind of rise to the level that we're talking about. We're talking about an exposure
00:02:56.400that can negatively affect a living system. And I'm going to just pause it for the moment that
00:03:02.140we are the system of interest for the purpose of this podcast. So the obvious examples, which we
00:03:07.280will discuss, are things like air pollution, but also things like water pollution, soil
00:03:11.680contamination. But other things that we're going to touch on are forms of pollution that can refer
00:03:16.860to forms of energy or sensory disruption, such as noise and artificial light. Now, we already did an
00:03:22.880AMA on chemical pollutants like microplastics, PFAS, phthalates, and we'll obviously link to
00:03:29.760that for folks so they can go back and hear that. So I'm not going to obviously repeat that stuff.
00:03:33.800Instead, I want to focus more on the physical environment and the exposures that people
00:03:38.080encounter every day in their life. And I think the big ones here is basically the air that you're
00:03:43.440breathing, the noise you're hearing, the light that you're exposed to, and the electromagnetic
00:03:47.620fields around us. Again, the reason I'm not covering water and even soil right now is a lot
00:03:53.720of that was captured through microplastics, PFAS, and phthalates, which is generally the vehicle
00:03:58.800through which those travel. Okay. Then to your second question, why does this belong in the
00:04:03.680discussion around longevity, well, it really comes down to, again, the definition of what harmful is.
00:04:08.920And some of these exposures are clearly linked to things that we care about, right? Cardiovascular
00:04:14.280disease, respiratory disease, cancer, sleep disruptions, even cognitive effects, and outright
00:04:19.840mortality. Again, air pollution is probably the clearest example of this. If you've ever been to
00:04:24.920a city with very heavy air pollution or somewhere during a wildfire event, you don't need a
00:04:29.980randomized trial to explain to you that breathing there is horrible. And the epidemiology will very
00:04:35.380quickly demonstrate that even over a short period of time. But I think the more interesting question
00:04:40.000is what happens well below the obvious threshold. And I think that's the area where most people,
00:04:46.360myself included, are interested to understand this. I don't need to know what happens when
00:04:51.200you live next to Chernobyl and there's a disaster, or like I said, when there's a wildfire in your
00:04:56.120in your neighborhood. But what about living near a highway? What about cooking indoors with poor
00:05:00.460ventilation or sleeping in a noisy urban environment? Those aren't really producing
00:05:05.680obvious symptoms in any moment. But the question that I think we want to explore today is could
00:05:11.400those be leading to any chronic and cumulative effects? So a few days of imperfect air probably
00:05:18.080doesn't matter much. The question we want to understand is what's the area under the curve
00:05:23.160over years and decades implying for disease risk and mortality. And then I guess the final point
00:05:30.380I would make as to why this is interesting is that unlike exercise or nutrition or other
00:05:36.300more readily modifiable behaviors, these exposures aren't always fully under our control.
00:05:43.220Obviously, you can choose in some cases where you live, but this is far less under our control,
00:05:47.800I think, than some of the things we normally talk about in this podcast.
00:05:50.580But the flip side of that is that the goal is, you know, can't be to wipe out all possible exposures because that would, you know, mean sealing yourself into a, you know, hermetically closed bubble. It's rather, I think, to understand which exposures matter most, which ones are overstated, and then where practical interventions can meaningfully reduce risk.
00:06:12.580So if I were to sum all that up, I would say at the end of this podcast, I would hope that
00:06:17.220you as a listener understand the 80-20 principle of what you need to do, where I think 20%
00:06:23.240of the work is going to get you 80% of the benefit.
00:06:27.200And this is an interesting topic where it's a bit polarizing, right?
00:06:31.020So on one end, you have a group of people who are seemingly entirely unconcerned about
00:06:38.380And on the other, you have people who potentially treat any quote-unquote unnatural exposure as
00:06:43.980extremely dangerous. So what is it about this topic that you think creates such disagreement
00:06:49.860and polarization on those two sides? Well, I mean, I have lots of thoughts on that,
00:06:56.400but I would also argue that I don't want you to imply, Nick, or I don't want anyone to think
00:07:01.760that you're implying that that's the only area of health where we see polarizing points of view,
00:07:06.640right? I think almost everything we seem to talk about on this podcast can be looked at through
00:07:11.820that lens, right? Cholesterol or, you know, whatever else. But for the purpose of getting
00:07:16.480off my soapbox, I think a big part of the problem is that the idea, the term, the concept, the field
00:07:23.900of pollution is very broad. So I think when one person hears it, they might think about smog that
00:07:29.860affects their breathing. Another person thinks about how urban glow might disrupt migratory
00:07:35.280birds. Someone else is convinced that cell towers are making them sick. But when you put all of
00:07:40.720those exposures in the same bucket, it becomes pretty hard to separate signal from noise.
00:07:47.140So if you see enough outlandish marketing for expensive devices to protect you from your
00:07:54.160phone's radiation, it's easy to wonder whether there's a whole house air filter that should also
00:08:00.720be part of your armamentarium. I think on top of that, what makes it hard for people to evaluate
00:08:07.900this is that these exposures are essentially invisible, obviously with the exception of light.
00:08:13.760They accumulate very slowly and they can take years or decades for the health effects to become
00:08:19.400apparent. And so the challenge of that from a scientific perspective is it makes the evidentiary
00:08:25.200standards inherently harder to interpret than for things where the signal is really clear.
00:08:34.580For example, smoking and cancer, which we've talked about, is one of the best examples of
00:08:38.740epidemiology being able to very quickly disentangle signal from noise, exposure from disease.
00:08:45.020So I don't think there's one thing, Nick, that explains this. I think it's just basically all
00:08:49.740of those things rolled together and potentially some things I haven't even thought of.
00:08:52.960And on this, what do we know about why environmental exposures can be so difficult
00:09:01.080to study rigorously to give us much clearer answers around these questions?
00:09:07.120Again, I think there are several reasons. I sort of alluded to one earlier, but I think we can get
00:09:12.220even more thoughtful on that, which is it's almost impossible to study these exposures in humans the
00:09:19.140way we study drugs. Again, we think back to the principles of what makes studying drugs so
00:09:25.360straightforward, even though it's by no means easy, is that you can't randomize groups. The
00:09:31.540interventions are usually complicated. There's ethical concerns that go to it. So just consider
00:09:35.880you couldn't do a randomized group of having one group of people breathe polluted air for 20 years
00:09:43.400next to a freeway, and then another group of people be randomized to move and live as shepherds
00:09:49.560in parts of Ireland or Scotland near the freshest air possible, and then compare the outcomes after
00:09:54.62020 years. Again, you can find those groups of people and compare them, but that's not an
00:09:59.720experiment, right? Because you haven't randomized them. So you can't possibly measure all the
00:10:05.660nuances. To do an experiment, you have to take a group of people and separate them randomly into
00:10:12.440those different groups. So again, it's the very nature of doing that that's very difficult.
00:10:18.900And so because you can't do the randomized experiment, you end up doing the thing that
00:10:22.380I described, which is you do the observational version of that, which is you find people that
00:10:26.780are naturally in these settings, so-called natural experiments, and we try to understand
00:10:33.780what's happening there. But of course, the challenge with that is unlike smoking, the
00:10:39.580signal or the, to use it more technical term, the hazard ratio is so small. Again, when you
00:10:46.600compared smokers to non-smokers, not in a randomized fashion. So admittedly, a smoker
00:10:51.740might've been more likely to do things that were unhealthy. The hazard ratios were greater than 10.
00:10:57.740So we're talking about more than 1000% difference between the risk of getting cancer and not getting
00:11:04.800cancer if you're a smoker versus a non-smoker. That's not subtle. You don't actually need
00:11:10.000statistics to help you understand that. But if the difference between, in the natural observed
00:11:15.580experiment, if the difference between one group and the other is 30%, which would be a hazard
00:11:20.520ratio of 1.3, that's not within the ability for epidemiology to interpret and apply causality.
00:11:28.300I think another issue really is this idea of exposure measurement. So if I want to study
00:11:36.060something like a genetic marker or the phenotype of some known genetic marker like LP little a,
00:11:41.740I can measure it once. I mean, I can measure your LP little a level and I can be relatively
00:11:47.820confident that the exposure that you have to that lipoprotein is stable over time.
00:11:52.680But environmental exposures aren't necessarily like that. Your exposure depends on where you
00:11:57.360live, where you work, how you commute, whether you exercise inside versus outside, how well your
00:12:02.600home is ventilated. And then of course, how do those patterns change over time? So when a scientist
00:12:08.480or a statistician or an epidemiologist is given access to a zip code or a neighborhood level
00:12:14.480estimate, it's better than nothing. But based on everything I just said, I think you realize
00:12:19.720actually there's way too much noise and heterogeneity in this data for me to really
00:12:25.400understand it. Another issue is that these exposures rarely travel alone. So it's true,
00:12:32.080of course, if you live near a highway, you may have more particulate matter, more nitrogen
00:12:36.340dioxide, more noise, more nighttime light, and other exposures all at once. So even if one could
00:12:42.940demonstrate, notwithstanding the limitations I've stated above, that all of these things are
00:12:49.120leading to worse health outcomes, how do you disentangle the causality of each one? What if
00:12:55.080all of the negative health outcomes are coming from one of those things and the others are all
00:12:58.920irrelevant interlopers. We don't know. And then I think finally, the flip side of that
00:13:03.860last point is that many of these outcomes are actually multifactorial. So if someone
00:13:08.440develops hypertension or has a heart attack, air pollution or noise pollution may have contributed,
00:13:14.160but we also know that their genetics contributed, diet contributed, sleep contributed,
00:13:18.400exercise or lack thereof, smoking, all these things contributed. And it's not to say that the
00:13:24.340toxin didn't impact those things, and that those things then impacted the disease. So
00:13:29.220it becomes very difficult to study this rigorously, which is probably why we're talking about it.
00:13:35.280Given all those complexities, before we start jumping into specific questions around air
00:13:40.360pollution, noise pollution, light, EMF, 5G, is there anything you want people to think about?
00:13:47.760Is there any context you want to provide before we get into those details?
00:13:51.160Yeah. I think before we get into specifics, and we certainly will, I do want to reframe or maybe
00:13:59.900provide context. I want to establish where I think environmental exposure fits into the broader
00:14:07.040hierarchy of health. I don't want to minimize these exposures. They are real. But for most
00:14:12.300people, for most of you listening, they sit well, well below the fundamental things that you have
00:14:21.620control over that impact your health. Sleep, exercise, nutrition, things that flow from these
00:14:28.240things, blood pressure, lipids, metabolic health. I'm sure that we can all come up with an example
00:14:35.160of somebody for whom environmental exposure supersedes all of those in magnitude of impact.
00:14:43.000But that is going to be a very, very rare exception. Now, all of us have a finite amount
00:14:50.380of time, money, and mental energy to spend on our health. So we really want to be thoughtful
00:14:57.220about making sure we prioritize around the highest yield levers and that we put our time,
00:15:04.000energy and money into those things first. So unfortunately, I come across people more often
00:15:10.060than I care to admit who aren't really exercising, who are sleeping like five hours a night, but
00:15:15.220they've explained to me that they have a $2,000 air filter in their home. And I just think that
00:15:21.720that's a complete inversion of priorities. Now, for someone who has everything dialed in
00:15:27.540and they happen to live in an area where air pollution is demonstrably higher than it should
00:15:34.200be, that $2,000 air purifier might be a remarkable use of resources. So when we talk about specific
00:15:42.140exposures through this episode, I think the practical questions we should keep in mind is
00:15:46.140how strong is the evidence? How large and serious are the effects? And then can we actually do
00:15:52.240something about it without upending our lives? And that last point I think matters a lot.
00:15:56.700The goal is not to eliminate every possible exposure. That is metaphysically impossible,
00:16:03.460and that needs to be understood. It is to identify exposures that are meaningful,
00:16:08.540reasonably modifiable, and worth addressing with a small number of low burden but high return
00:16:14.680interventions. Perfect. So with that said, let's jump into first category of air pollution.
00:16:21.460So I think it'd be helpful here to just first state exactly what we're talking about when we say air pollution and more importantly, which pollutants matter most for people to think about.
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