Pollution: The Harmful Agents Impacting Your Health

illustration of a delivery truck driving through a polluted environment

Pollution has an effect on more than just the environment, and the impact on our health may be surprising. Experts from the University of Michigan School of Public Health discuss the particular effects that noise, air, and plastic pollution can have on our health.

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00:30 Host: We've come a long way in understanding pollution and advocating against it. Since the days of Woodsy Owl and the iconic give a hoot don't pollute slogan. 40 years ago When Woodsy was singing that tune pollution was basically thought of like this: What are we Pumping into the air and what do we dumping into the water? As our knowledge has advanced so has our research into how pollution, in all of its different forms, affects our bodies and our health. Today, we'll explore some types of pollution that weren't on Woodsy's radar: Plastics and noise as well as air pollution, and examine potential solutions to curb their effects. Hello and welcome to Population Healthy, a podcast from the University of Michigan School of Public Health, join us as we dig into important public health topics, stuff that affects the health of all of us at a population level, from the microscopic to the macroeconomic, the social to the environmental, from neighborhoods to cities, states to countries and around the world.

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01:40 Host: Noise is all around us, each and every day, researchers have learned that excessive noise can harm more than just your hearing. Rick Neitzel, Associate Professor of Environmental Health Sciences at the University of Michigan School of Public Health, invites you to listen closely, but not loudly to the wide-ranging health effects of noise pollution.

02:00 Rick Neitzel: If you think about your daily life, in fact, all of us are exposed to different types of noise pollution, all of the time. This would include things like buses and vehicles, things like airplanes and motorcycles, things like a noisy job, things like concerts, riding a snowmobile and also, increasingly, listening to music. Historically, most of us have thought of noise as really only damaging our hearing, and it absolutely does damage hearing.

02:26 RN: So the higher your noise levels, the more likely it is that you're gonna get a debilitating hearing loss and make no mistake. Hearing loss is absolutely a debilitating and very adverse condition, but it's far from the only one that noise causes. Over the past 20 years or so, we've learned about a number of other very serious impacts from noise. In fact more serious than hearing loss in some cases. You may not be aware but being exposed chronically or over long periods of time to noise from roadways and aircraft has been associated with an increased risk of heart attacks and an increased risk of high blood pressure or hypertension and an increased risk of cognitive impacts, particularly on children. There's a rich literature that says if you're a child and you're learning in a classroom that's noisy, you're gonna have worse educational outcomes than another very similar child in a quiet classroom.

03:18 RN: We also are starting to think that noise may be linked to things like depression and psychiatric conditions and potentially on things like a cognitive decline over time. So all of these are huge public health burdens and the link between noise and cardiovascular disease is especially important because we know heart attacks and other cardiovascular disease kill more Americans and other people around the world than any other condition. I did a study with some colleagues at Columbia University, that was based in Manhattan and we looked at about 4500 people who lived or worked in New York and we interviewed them and made some noise measurements trying to estimate what was each of these person's annual exposure to noise across all of the activities they do. And in fact, we found that nine out of 10 of the people in our study were over the recommended exposure limit for noise that the Environmental Protection Agency and the World Health Organization have put out, nine out of 10 people over that level. If you imagine another type of pollution something in the air, something in your water where we said, well, only nine out of 10 Americans are exposed. There would be a massive public outcry and rightfully so. But for noise, we have tolerated this in recent decades, perhaps viewing it as a by-product of modern society.

04:34 RN: In fact though, it is very harmful and to think about the vast majority of urban Americans having exposures that are too high is very concerning. Armed with studies like that researchers are now investigating noise in the environment using a number of novel approaches. Maybe of most interest recently, we have things like apps on smartphones that we can use to measure the noise around us. One of the major thrusts right now is mapping noise, trying to use statistical predictive models to estimate what a person's exposure to noise might be in their home from roadways, freeways, and major local roadways, but also things like airport noise or railroad noise. Another is trying to deploy sort of crowdsourced or citizen science noise measurements.

05:18 RN: And so this would be coming back to my comment about smartphones and apps, actually having people measure their own noise in the environment throughout their normal day and during whatever activities they do and then feeding that information into a central database, that we get analyzed. We recently launched a first of its kind study with Apple to look at music and sound exposures in America. Previously, we've really struggled trying to integrate different exposures, so trying to account for the fact that people have environmental exposures around them, but increasingly, they're also getting a lot of noise through their headphones and their earbuds, so it's very easy to measure environmental noise and we also have ways to measure noise through your headphones, but to do those both simultaneously is extremely challenging.

06:06 RN: However, in this study, we're going to be able to do both of those things and again, at a national level, so the outcome here is gonna be a first ever estimate of individual noise levels that we've measured on people over time, and this will really help us better understand the extent of the noise exposure problem in America. People will also be able to assess their hearing. So now, we will not only have estimates of exposure, but we can start to tie those to direct impacts on people's hearing. And again, we can ask questions like, is noise in the environment around you more or less harmful than the same amount of noise delivered as music through your headphones? Reducing the effects of noise on your health goes beyond controlling the volume button.

06:47 RN: There are examples of systematic changes that could provide a blueprint for national impact. Back in the 1960s and 1970s, people around America became quite annoyed with jet aircraft noise. This was a new phenomenon, back then, and as air traffic and air travel expanded the public got really annoyed to the point where the federal government turned to the airplane manufacturers and said these are too noisy, we don't care how you're gonna do it, but you will make these airplanes quieter or you will not fly them in the United States and lo and behold, the manufacturers reduced our noise levels between 1981 and today by 95%, that's a huge success story, and it gives a model where we could potentially quiet things like cars and wind turbines and all the other noise sources around us through policies.

07:39 RN: That's a long-term fix. We also need to think about what we as individuals can do and there's actually some good news here as well. So things like avoiding noise that you don't have to be exposed to in the first place, that's a great way to reduce your exposure. When you can't avoid noise using hearing protection, ear plugs, or ear muffs can be extremely effective. Also, things like simply manipulating your schedule, so you're avoiding noisy places at the wrong times. And finally, I wanna mention that there is this increasing exposure that we believe is happening with music. Back when I was a kid with a Sony Walkman I could listen to music for about 20 minutes before the battery died, and it couldn't get very loud, because I didn't have very good headphones. Today you can listen for a full day essentially at very high volumes with very high quality. And so we think that it's possible people are listening to more music at higher volumes and that's something that all of us absolutely have control over. So being aware of that exposure and trying to protect your ears wherever you can is something that all of us can easily do.

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08:48 Host: There's no doubt you've come into contact with plastic today. Plastic is omnipresent in our modern world. John Meeker, Professor of Environmental Health Sciences at the University of Michigan School Public Health, researches how microplastics can end up in our bodies.

09:03 John Meeker: Plastics are used in our everyday lives. Nobody really questions that they've really benefited society with a lot of the qualities they can bring, [09:11] ____, they're safer because of plastics. The way we can store food makes food safer for longer. So you could go on and on. There's just many, many benefits that are known with plastics. The problem is if you look at some of the charts and graphs out there on plastics production and disposal we're seeing an exponential increase ever since about World War II, where we're now up to about 500 million tons of plastics produced per year, and unfortunately, a lot of that does end up out in the environment which can have ecological consequences. There's also the direct impacts of plastics if they have certain chemical additives in them even as we're going about our day using the plastic item we might be exposing ourselves there as well. One of the fall-outs, from having all this plastic around is the issue of microplastics. What microplastics are they're defined as bits of plastic, they're less than 5 millimeters in diameter. 5 millimeters is actually quite large when are you talking about particles.

10:06 JM: These micro-plastics can go all the way down to nanometers in diameter or nanoplastics, so the size of the particle is gonna make a big difference in how it behaves in the environment, and also how it might behave in wildlife or humans. Microplastics are formed by different mechanisms. Some of them were actually produced that way. So if you think about some cosmetics that might have microbeads, that's microplastics. Those have since been banned in the US and some other places, luckily, but those were being produced as little tiny plastic balls to help exfoliate the skin. As far as human health effects we really don't know much at all yet. We're at the phase where we're now measuring it in the foods we eat, water we drink. It's being measured, so we know people are consuming it potentially then breathing it. Some studies have even measured it in air so then it becomes how it would be toxic to humans.

11:01 Host: Manufacturers have developed what seem like limitless uses for plastic. With so many applications and so many methods for producing plastic researchers are trying to understand which additives could impact our health.

11:13 JM: There's a long list of different types of additives, some of the big ones are class of chemicals called phthalates, one use they have, they're called a plasticizer. One of those applications was the polyvinyl, chloride PVC plastic. You know, you have like the rigid PVC in pipes and plumbing, things like that, but there's also the soft PVC. It's the same type of plastic but you can tell they're different physically, right? And what makes the one soft, like say, a shower curtain, if it's made out of PVC is the plasticizer, and in many cases, it is a phthalate. Back in the day, some shower curtains were measured to be as much as %40 or 50% phthalate by weight and it's not covalently bound to the plastic, so it's considered an additive which means it can leach out pretty easily so that results in it being present in indoor environments, in outdoor environments, in our food. Phthalates has several dozen specific chemicals within this class. And there are a couple of those that have been pretty well-studied, have been shown to impact various health outcomes, in both animal studies and in larger human studies as well. So those are starting to be phased out and replaced with either other phthalate chemicals or other chemicals that are like phthalates, hopefully in the long run, non-plastic, or a more sustainable type of approach for meeting those needs.

12:29 JM: In the US here, those chemicals and a few others have been banned from children's toys and other children's articles, which is great, but the thing is the health affects they might have might stem beyond childhood or children's health might be more sensitive when that child is in the womb, so there's no law against items pregnant women are coming into contact not containing these chemicals, so that's an area of concern.

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12:56 JM: With all this plastic being produced, imported, incorporated into products, who's responsible for it? A lot of this just gets pushed down to the consumer. You know, I put out my recycle bin, I have to cross my fingers and hope what I put in that bin is gonna actually be recycled. Turns out the likelihood of that can shift with different things going on overseas and in our country as far as infrastructure to actually be able to recycle that plastic, if it's the right type of plastic that's conducive to recycling. A lot of those questions, it's not really fair to put on the consumer, I think the producers and distributors of a lot of these plastics need to be held more accountable on the back end. Are they gonna take it back from us and try to do something with it, as a recycling effort or a reuse effort? So another thing with plastics, given that they're being produced in such an increasing rate is, that they stick around for a long time.

13:44 JM: The actual half-life isn't known and may very by different types of plastics, but it's thought to be hundreds of years that a plastic item is gonna be around, so it's gotta go somewhere. So that's another issue that we're dealing with. There are some things you can do to reduce your exposure likely. If you're using a plastic container with your food, you might not wanna microwave that plastic container to heat your food, put it in something else that won't leach chemicals would be a good idea. Some companies have taken it upon themselves to advertise as phthalate-free, Bisphenol A-free, so you can try to seek out products like that, which is good in a lot of cases, especially if it's being used for consumption, so water bottles, food containers, things like that. Something we wanna make sure is we're not waiting until we start seeing adverse human health effects and then say, "Oh, it was the microplastics." We wanna try to get out in front of this. So as a researcher, we're trying to think of methods to study this without having to wait until people are sick which as an epidemiologist, that's difficult, but maybe we can start by tracking trends of exposure, getting to know how to best measure exposure, you know.

14:45 JM: Are we measuring just the additive chemicals? Probably not. How do we measure how many microplastic particles somebody is exposed to? So trying to define some of these and try to figure out where those risks might be, I think is a big step we will need to take in the next couple of years.

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15:05 Host: In a similar fashion to microplastics, other particles in the air can show up in our bodies, and cause problems. Air pollution is known to affect our lungs. And even our brains and how we think. Sara Adar, Associate Professor of Epidemiology at the University of Michigan School of Public Health, researches the impact of air pollution on our health.

15:24 Sara Adar: Mostly we worry about the smallest particles, so ones that are smaller than the size of a human hair, they can get deep into our lungs. So it can cause a local inflammation in your lungs, that's one of the things that can happen. You can have harder time breathing, things like that. It can also stimulate the nerves in your lungs. So you may experience this, when you take a deep breath in of smoke, you know, you might have a big cough, that's the same mechanism. Those particles are sending signals to your brain that can then change the sympathetic and parasympathetic nervous system, which is basically the control of the stop and go of your body, the calm and relax versus the fight and flight response, and so that imbalance can change how your blood vessels are constricting, how fast your heart is beating things like that, and also the inflammation that starts in your lungs can actually go throughout your body and cause changes to the blood vessels and everything else that happens with inflammation. Finally, there's some pretty interesting research that shows that the very smallest particles can actually what's called translocate and get into your bloodstream and then really get anywhere throughout your body, even some can pass through the olfactory bulb in your nose and go straight up into your brain.

16:38 SA: And so that's a really exciting area of research these days on air pollution and cognition and dementia and older age. Part of that, again, is because there is this thought that it not only changes the blood vessels throughout your body, which obviously has important impacts for your brain, but also that it can even get straight up into your brain and wreak havoc locally.

16:58 Host: Adar studied air pollution caused by school buses. The research was focused not on the pedestrians outside the bus, but on the young passengers inside.

17:07 SA: The government had funded a lot of these programs to try and clean old buses, replace either really the old clunkers that were really dirty emission vehicles, or put new technologies on that could clean the air that was coming off of those buses. The study that we did, it was about four years, we tested close to 50 school buses before, during, and after they changed their clean air technologies and fuels. I think we went on something like 80 rides where we were monitoring the air inside the buses, and then simultaneously we were sampling about 200 kids, again, as they were riding those buses before they got changed out, during the change out, and after.

17:51 SA: And what was really exciting and interesting was that we found that changing out the oldest buses, those really old diesel buses with cleaner buses or buses with clean air technologies, we saw improvements not only in the air pollutions levels inside the cabin, but also we saw improvements in their lung health. And we saw that kids, especially, asthmatic kids were missing school less often when they were riding those school buses. The estimate that we came up with was that the switch from dirtier fuel to cleaner fuel resulted in 14 million fewer absenteeisms a year in the United States. And to me, that has a lot of public health benefits, not only for the health of the kids but those parents who would normally have to stay at home with a sick kid now can go to work. So there's economic benefit to that as well in a way that you know that your research is having an impact. Shortly after that research was published the local EPA which is the National Vehicle Emissions Lab and many of the people at EPA who are in charge of the air quality from traffic invited me to give a lecture there and present our results. After we spoke to them, they wound up renewing funding under this DERA program, which is the Diesel Emission Reduction Act. I looked it up, I think since 2012, the EPA now has put in about $28 million to replace dirty school buses or put in clean air technology on their vehicles. I think that's a huge public health benefit right there.

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19:24 SA: It's a very frequent question and an obvious question, right? What can I do to improve my exposures and my health? I was at a session one time in Tennessee about the Clean Power Plan and somebody once said we are all obligatory breathers, right? And it's true. So with air pollution, you really can't just stop breathing. That is not a choice for us. On the other hand, there's a few things that you can do. So there's been a nice research and we participated in it as well that shows putting in clean air purifiers in your home, for example, can help reduce exposures. The literature is a little bit more hit-and-miss, in terms of how important that is for health. We had a recent collaboration with some folks at the medical school and now a professor at Michigan State University looking at the use of air purifiers in senior citizens homes in the Detroit area who lived right in a highly industrial area and right near a lot of traffic and that study did show that putting in the air purifiers into their homes, both improved their exposures as well as their blood pressure levels during the times when there are purifiers in their homes.

20:32 SA: So using your purifiers as one method, I mean, I think on a population level, as individuals, we can try not to use our cars and things like that as much. Traffic is one of the main sources of air pollution in our nation. That's not true, for example, in India, where you have high levels due to household air pollution and crop burning and things like that, but in the United States, a lot of it is coming from traffic and so choosing to ride your bicycle or walk to work, or walk to do small errands, you know, actually, it makes a huge impact on your health, and not only because of the air pollution levels, but actually the physical activity turns out to be a huge benefit for your health. From an environmental side as well as a public health one replacing car trips with other active transit, I think, would be highly beneficial.

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21:29 Host: Thanks for listening to this episode of Population Healthy from the University of Michigan School of Public Health. We're glad you decided to join us, and we hope you learned something that will help improve your own health or make the world a healthier place. If you enjoyed the show, please subscribe or follow this podcast on iTunes, Apple Podcast, Google Play, Stitcher, Spotify or wherever you listen to podcast. Be sure to follow us at umichsph on Twitter, Instagram, and Facebook, so you can share your perspectives on the issues we discuss, learn more from Michigan Public Health experts and share episodes of the podcast with your friends on social media. You can also check out the show notes on our website. Publichealth.umich.edu/podcast for more resources about the topics discussed in today's episode. If you want to stay up to date with the latest research and expertise from Michigan Public Health, subscribe to our Population Healthy newsletter at publichealth.umich.edu/news/newsletter. We hope you join us for next week's episode, where we'll dig further into public health topics that affect all of us at a population level.

In This Episode

John MeekerJohn Meeker

Professor of Environmental Health Sciences and Associate Dean for Research at the University of Michigan School of Public Health

John Meeker’s work is wide-ranging, and focuses on defining sources, magnitudes and consequences of human exposure to environmental and occupational contaminants, as well as identifying and evaluating strategies to control harmful exposures. Much of his current research involves human exposure science and reproductive and developmental epidemiology studies of known or suspected endocrine disrupting chemicals, such as phthalates, BPA, pesticides, flame retardants, and others. Learn more.


Rick NeitzelRick Neitzel

Associate Professor of Environmental Health Sciences at the University of Michigan School of Public Health

Rick Neitzel is an exposure scientist whose research focuses on the characterization of exposures to noise, heavy metals and other ototoxins, psychosocial stressors, and injury risk factors, as well as a range of adverse health effects associated with these exposures. He is particularly interested in incorporating new methodologies and exposure sensing technologies into research, and also has a strong interest in translating his research findings into occupational and public health practice. Learn more.


Sara AdarSara Adar

Associate Professor of Epidemiology at the University of Michigan School of Public Health

Sara Adar’s research focuses on the human health effects of air pollution, with a growing interest in identifying intervention strategies reduce exposures and improve health. She has served as an expert panelist for the Environmental Protection Agency and World Health Organization, including participation in the development of the National Ambient Air Quality Standards for particulate matter and sulfur oxides.
Learn more.