Oregon State University study maps noise pollution in Portland

Excess noise has been linked to a number of health concerns, including cardiovascular disease, high blood pressure and sleep disorders. But noise pollution hasn’t been well studied in the U.S., due in part to a lack of federal oversight. The Environmental Protection Agency established its Office of Noise Control and Abatement in the 1970s, but the office has remained unfunded since the early 1980s.

A new study from Oregon State University aims to better understand noise pollution in Portland. Researchers found that many of the city’s neighborhoods have noise levels that are likely unhealthy.

Matt Bozigar is an environmental epidemiologist and an assistant professor in OSU’s college of health. He joins us with more details.

Note: The following transcript was transcribed digitally and validated for accuracy, readability and formatting by an OPB volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. Excess noise has been linked to a number of serious health concerns. But according to researchers at Oregon State University, it remains understudied compared to other environmental hazards. Matt Bozigar wants to change that. He is an environmental epidemiologist and assistant professor in OSU’s College of Health. He recently mapped noise levels across several Portland neighborhoods, and he joins us now. It’s great to have you back on the show.

Matt Bozigar: Thanks, great to be back.

Miller: Why study noise levels?

Bozigar: I think this is a very underappreciated factor of our common environment, the places we live and frequent every day. It’s in many ways been, for that reason, termed the “forgotten pollutant.” When we think about noise and health we’re interested in not only auditory health, like hearing and hearing damage from very loud noises, but also the more longer term, chronic exposures to lower levels of noise, because those have demonstrable long-term health impacts.

Along those lines, we are finding more and more in the research community that noise can disrupt sleep and it can cause stress responses. And both those factors are risk factors for many chronic diseases. We’re talking things like cognitive impairment, mental health disorders, high blood pressure, cardiovascular disease, metabolic disorders and even things like adverse pregnancy outcomes.

Miller: I can imagine someone saying, “my neighbor’s leaf blower is annoying, but I don’t think it’s affecting my health,” or “I grew up in in a big city with with subways and sirens all the time, and I’m used to things being loud” and “I don’t love it, but it’s not that big a deal.” Your contention is that we are, as a population, underestimating the health impacts of noise?

Bozigar: To put it simply, yes. But it’s a little bit more complicated than that, right? Noise is actually defined as either unwanted or harmful sound. That’s the only thing that differentiates it from just the sounds that we hear as humans. Biologically, the human ear, when sound is heard, the nerve impulses and the connection to the brain to process those signals to put those together so that we hear a sound that we recognize, that happens very, very fast.

So [hearing] is actually the sense that we rely on for our fight or flight responses – what are you gonna do, fight or run, type of response. And that’s much faster than sight sensory signaling in terms of brain speed. So, given that that sound and hearing is actually important for fight or flight responses, it’s not necessarily a stretch of the imagination to see how it can initiate a stress response.

But the really insidious thing about noise is that, whether or not it’s unwanted, it can be harming your health regardless of whether or not you think it’s annoying or if you even notice it. For example, when a very loud noise disrupts your sleep, you might go from some sort of sleep stage to being awake. That caused an arousal, that caused an awakening. But maybe what you’re less aware of is some of the not quite as loud sounds that are still potentially causing microarousals, or changes in your sleep stage from something deeper to something lighter, or a near awakening. And most of those, if not all, you are not conscious of. So noise can be impacting your sleep and stress levels, whether you know it or not.

Miller: I want to turn to your study. It has been billed as one of the first of its kind in the U.S. So what sets this study apart?

Bozigar: So most of the research on noise health has been done in Europe, European settings in European cities. And quite frankly they’re much further along and they’ve generated the main body of evidence on this topic. The U.S. has lagged. In this country, a lot of the attitudes that we have towards noise currently reflect the lack of federal oversight of this issue and recognition of it as a pollutant.

For example, the Noise Abatement Act started in the ‘70s and maybe ended in the ‘80s – it didn’t last too long. That was our federal oversight mechanism. We kind of lost that piece of it, and along with that, a lot of the research started to fall off because we’re no longer interested, at that time, in pursuing the health effects of noise. We’ve got lots of other problems, other environmental pollutants like lead and air pollution, unsafe water. We kind of shifted our priorities a bit there. And the research just hasn’t really caught up with that.

So long story short, what we really wanted to do in this study was measure noise on a citywide scale, systematically and at very high quality. And that’s what really separates our study from other studies in the U.S. We were able to measure noise happening at night. Our monitors were out for almost a week in the different measuring sites that we chose. Those sites were chosen based on trying to capture every unique sound profile in the city, that’s the systematic piece. And then we use very high quality, cutting-edge microphones in our sound level meters. These are equipment, because they’re now digital, they’re able to condense all that technology into a much smaller package, something that’s both cheaper and smaller that we can feasibly mount, which we did on some of the city poles around Portland. So that’s what really separates our study.

Miller: What kinds of patterns did you find when you analyzed the data that came in?

Bozigar: We’re still analyzing some of the data. We have a very rich data set now and that’s one of the benefits. But one of the things that we find was evidence of an environmental injustice, that people living in a lower socioeconomic status neighborhood tended to be exposed to higher levels of noise. And the same kind of relationship we found was for higher noise exposures in more racio-ethnically diverse communities as well. So these are some of the same communities in the city of Portland, and similar communities across the U.S. and elsewhere, that tend to experience the burden of many environmental stressors. Noise is just another one that we’re actually seeing these communities also face.

And then we also found really interesting patterns in noise profiles based on where people lived. So we found that noise levels on the busiest streets were high but relatively consistent over time. One of the things we’re interested in in terms of health is the pulsing nature of noise or what we would call the intermittency in the field. And we found that on main roads, the noise was less intermittent but at a higher level. But a block or two off the main road, we found that the noise was actually the most intermittent of any of the other types of physical locations, though at somewhat moderated volume.

Miller: Do you know, or is there good research to tell us which one is worse for us? Say, a slightly louder but relatively constant level of noise, or one that’s variable and at maybe surprising intervals there are bursts?

Bozigar: That is a burning question in our field. Right now, I think that’s where we want to take the next steps of the research, because we don’t have a clear answer about that. So that’s on the front burner now in terms of research.

Miller: Were you able to record what was making noise? Or simply the decibel level, how loud everything was?

Bozigar: The main objective was to measure that decibel level, the intensity, if you will, the sound pressure level – these are all synonyms. So not an audio signal. But we did take audio and video snippets at each site, to allow us to have a kind of a more complete picture. And in a machine learning framework and artificial intelligence framework, we’ve been able to analyze those data together in whole to determine the top five sources at each site. And this was work led by Dr. Andy Larkin here at OSU. And we did find that the majority of the sites, the main source was road or vehicle-related traffic. That really dominated across most of the sites. Occasionally we’ve got some other things in there, like the leaf blower that you mentioned, stuff like yard equipment, people, construction noise, music, things like that as well. But those analyses are as of yet unpublished. So that will be coming.

Miller: I have to say, when I looked at the map of noise levels that you published along with this study, it really just looked like a roadmap. The colors were different than the standard maps of the city of Portland that I’ve seen, but it looked, in most ways, like the maps I’ve already seen where this is where you drive.

Bozigar: Right. So first of all, that’s a preliminary map, we’ll be publishing an updated version of that in the coming months. But yeah, when you’re zoomed out at the whole city scale, it’s not that interesting, right? It does look like just the roads. It’s also the industrial areas, you look more closely at that.

I think the patterns really emerge when you zoom in. Because this preliminary map that we developed is quite granular, it’s actually a 10-meter resolution. So we’re looking within blocks and behind buildings, we can see some of the microenvironment variation in the noise happening in these areas. You do have to zoom in. And I think in the future, our collaborators at the Multnomah County Health Department will provide a tool where citizens and residents of the city can go in and publicly look at the areas that interest them and see these patterns on a smaller scale.

Miller: If they do that, maybe you would say when they do that, what do you hope policymakers will do with your study?

Bozigar: The main driver of that discussion is going to be, in my opinion, the health side of things. As the research on on the health effects of noise picks up and we start to see more clearer exposure response patterns – like lower exposures you’re having less health effects, higher exposures you have more and these are the types of noise – that’s gonna really give weight to that conversation, to be able to say we do have to do something about this now, what do we do?

But it’s a first step, right? It’s the first step for us in research. It’s a first step for the public to just increase their awareness of this topic. And to think about noise a little bit more carefully, as you move through your daily space and how it might affect you.

Miller: I was just thinking, as you were saying it … If you had done this work 10 years ago, before the city of Portland changed the speed limit in non-highway areas and non-priority street areas, I would love to see if that made a difference in volume. But more broadly, if you were building a community or retrofitting a community with an ear towards lessening noise or noise pollution, what kinds of things would you consider?

Bozigar: Oh yeah, great question. So again, we look to Europe for inspiration for what we could do. In public health, we think about primary, secondary and tertiary prevention strategies. Primary would be at the source, so the source of the noise in this case. Primary exposure reduction in terms of noise would involve either quieter engines, maybe quieter pavements, maybe lower speed limits, those types of things, maybe policies that could address the vehicles generating the noise. That’s primary prevention.

Secondary prevention would be something that you would try to use to block the noise, coming between the source of the noise and what we would say is a receiver of the noise. So that could be something like a sound wall or barrier. That’s why we put up sound walls along the major freeways in the Portland area and elsewhere. That’s one option. If you’re thinking about a community, building materials, you should examine those for their auditory insulation or lack thereof. So you make decisions about that.

And then tertiary prevention, the last line of defense could be something like, maybe you wear earplugs at night. Or maybe you use a white noise machine. Though even the evidence about the health benefits of that is not fully known yet. But you would want to think about primary, secondary and tertiary prevention when building a new community.

Miller: Matt, thanks very much.

Bozigar: Thank you.

Miller: Matt Bozigar is an environmental epidemiologist and an assistant professor in Oregon State University’s College of Health.

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