Chris Yip 0:01 Welcome to Coffee with Chris Yip, the official podcast of the Faculty of Applied Science and Engineering at the University of Toronto. I'm Chris Yip, the Dean here at U of T Engineering. In each episode, I'll be sitting down for coffee with someone from our amazing global community to talk about what they're working on, and how it places us at the heart of bold solutions to design a better world. In this first season, I want to zoom in on "the why?" finding out what drives the curiosity and passion of our extraordinary community. Once you understand that, I hope you'll start to see what makes this place so special, and that you'll be inspired to make, innovate and create along with us. If you want a breath of fresh air, which is better? Going outside or staying inside? The answer is; depends on where you live, what the weather's like, when your house was built, and even the time of day, and if you're like me a little bit of an allergy sufferer, the season. Today on Coffee with Chris Yip, I'll be chatting with two professors from our Department of Civil and Mineral Engineering, who are experts in tracking air quality, but from very different perspectives. Professor Marianne Hatzopoulou studies how urban air pollution varies over space and time in order to help us design cleaner, healthier cities. Professor Jeffrey Siegel studies indoor air quality using mathematical tools to model our exposure to chemical substances often found in residential and commercial buildings. Together, they'll help us understand the best way to get that breath of fresh air. Marianne, Jeff, welcome to the podcast. How are you today? Jeffrey Siegel 1:38 Doing great. Marianne Hatzopoulou 1:38 Thank you. Chris Yip 1:39 Cool. Well, great, thanks. It's terrific to get in touch today and just catch up on things and get your sense of the air we breathe, as it were. I'm going to jump back a little bit in time. Marianne, I am just going to start with you. I know you did your undergrad in physics, and then you went on to engineering, in particular environmental civil engineering. Maybe can you tell us a little bit about how you did that transition from physics into engineering? Marianne Hatzopoulou 2:04 Yeah, it's interesting. I did my undergrad in physics. I did research in my final year in plasma so I've always been interested in gases. That's when I joined engineering for my master's. I was still very interested in the atmosphere and gases in emissions. So that sort of continued on and for my master's degree, I did mostly air pollution work very much related to traffic to transportation, trying to link combustion with emissions. And so then the move to the PhD was sort of natural. I wanted to learn more about transportation, which I didn't know much about. That's sort of the common thread. Chris Yip 2:45 Interesting to see how folks take a background in a - call it a pure science, right? Like physics and in plasma, and then moving on into a very much an applied science, right? And then Jeff, you also started in engineering though, right? And then went off into mechanical. Maybe give us a little bit of a background on how your undergrad informed where you're headed, or where you are today. Jeffrey Siegel 3:09 Sure. So I did a general engineering degree from my undergrad and one of my first summer jobs was at a place called the Grassroots Alliance for a Solar Pennsylvania that was doing energy efficiency retrofits and research in row houses in Philadelphia. And from that, I kind of grew to a love of buildings. And then that kind of transition to some work after I graduated, and mostly in the energy space. And then I went through my master's still doing energy conservation, especially residential energy conservation type work, and then realized that there was lots of people studying energy in buildings, but very few people studying the air inside of buildings. Somewhere in the beginning of my PhD, I kind of transitioned to the indoor air quality side and the rest is kind of history. I study what's going on in the air and buildings and frankly, it's really just a way to kind of study and understand buildings and how we use them. Chris Yip 4:13 We're going to delve a little bit deeper into the current context for sure. But maybe start from a very broad perspective. Talking about air quality, I guess the question is really, what are the actual pollutants we're talking about? To me, a current springtime pollutant would be in fact pollen because that really aggravates me and at least there's a little bit of a remedy to that. But from your context, what are the differences outdoor versus indoor? Maybe I'll start with the outdoor environment first and Marianne. Marianne Hatzopoulou 4:43 If you are in a big city like Toronto, the largest source of air pollution is going to be traffic. If it's not traffic, it's going to be industrial air pollution, power plants industries, but then also small shops, and gas stations, and restaurants. And so a lot of the pollution is either combustion related or it's evaporative so you get a lot of evaporation of different substances. And those will vary across multiple environments. You're also impacted, even if there's no source of pollution in Toronto, you're also affected by transboundary, air pollution, right? Everything that comes from the American Midwest and Upper New York State, right? You have very little control over those sources but they create this sort of background in cities, on top of which then you overlay this local contribution. Chris Yip 5:36 We can't really control very much what happens in other countries but it does eventually land somehow on us. Marianne Hatzopoulou 5:43 Absolutely. And we also send a lot of other things to other places as well. Chris Yip 5:49 Jeff, from the indoor context. Jeffrey Siegel 5:52 Yeah, so absolutely. So take everything Maryann just said, and understand that that all comes indoors. And most of our exposure happens indoors, because we spend 90% of our time inside of buildings. So you get a moderation effect, kind of a transformation of some of those outdoor pollutants as they come indoors. And then you overlay that with indoor sources, cooking, cleaning, smoking, all kinds of things. It's this kind of huge laundry list. And so those add to the exposures combined with those from outdoor air pollution. And then there's another piece that Marianne said that's a nice kind of parallel here. That is what's happening in your neighbors', particularly if you live attached in an apartment building and an attached house, what they're doing also influences your exposure. So indoor air is the same kind of concept of shared air. Chris Yip 6:43 What sort of health issues come up? I mean, people think of the normal ones but in your context, how big of a public health issue are we looking at? Jeffrey Siegel 6:53 It's a really good question, it's going to have kind of a complicated answer. There are kind of two broad categories of health effects. The ones that we think about the most are the chronic health effects, and exposure to air pollution generally, indoor air pollution specifically, is one of the global leading causes of sickness and death. Now a lot of that arises from the combustion of solid fuels for cooking and heating. That's still done in a lot of the world but there's a whole host of things that accumulate and affect almost all of the systems within our body. And then the other broad category are the acute effects. And you mentioned allergies, that's one example of an acute effect. And then there's the other ones that we get from kind of short term exposures. And the part that makes it really complicated is, of course, we're all different individuals. And we also all have different exposures to this shared air. Chris Yip 7:47 Marianne, from the outdoor perspective. Marianne Hatzopoulou 7:49 Yeah, Jeff was talking about global air pollution; there's a study called the global burden of disease that ranks the different risk factors for mortality. I always like to show that in my air pollution course, because even in the Canadian context, air quality is number 11, or 12, of all the risk factors for mortality. What comes before? Smoking and obesity and all of that, but being number 10, or 12, is not very good. So even at the low levels that we think you know, are low enough that characterize Canadian cities, outdoor air pollution is still associated with a significant number of illness and mortality. Health Canada often quantifies the amount of mortality related to air pollution and that number is larger than the number of people who die from traffic accidents. And then there's then this whole range of illness, chronic illness, cardiovascular, respiratory, cancer, risk, etc. Chris Yip 8:51 And in a sense, they're all triggered, right? We got to breathe all the time. It's not always possible to get to an area where there isn't exposure to some of these pollutants, for instance, right? Marianne Hatzopoulou 9:03 Exactly and that's why air pollution from an epidemiological point of view is so significant because you can't hide from it. Chris Yip 9:11 Jeff, in that context are there things that people should look out for in an indoor environment. Jeffrey Siegel 9:17 One of the interesting things about the indoor environment is that so much of it is related to our own behavior. So some of it like outdoor air pollution, it's kind of where we live, but there's a lot that people can do in their home to reduce the risk. So for most of us, assuming that we don't smoke, our number one indoor risk is associated with cooking. So having a good rangehood fan and actually using it tops the list of things to improve. Number two is really paying attention to sources. I'm always surprised when I read a paper or you come across some field data in it, I learn about new sources all the time. Just to make it concrete, we just published a paper looking at essential oil diffusers. And if you don't know what they are, they're a little ultrasonic humidifier that you put some water in and some essential oil and you get a pleasant scent. And they're enormous particle generators, but on a mass basis kind of not far off the mass of particles produced by a lit cigarette. And of course, they're very different composition. And I'm not making an association with the health effects but it's a perfect example of a source that, I didn't even know existed and we came across it entirely by accident. And it's this huge source. And so, doing some education about what are common sources, cleaning, both the act of cleaning and the products that they use is another common source, the list goes on but those are kind of the big ones. Chris Yip 10:47 Obviously, when we're cooking, we can we can smell them, in a sense, right? So if you've got oil burning on your stove, you smell it pretty quickly, or something caught in your element. In the measurements you're doing in your research, what are you measuring? Marianne Hatzopoulou 11:01 Well it's driven by multiple things. There are markers, markers for traffic related air pollution, this is what engines generate and we should be tracking that. If you're concerned about a specific source, you're going to go and look at that signature and decide how and where to measure. I think a lot though, of what we measure and how we measure it in outdoor air has been also driven by technology. We measure it because we can. We call them new pollutants. They're new, because like ultra fine particles, right? So particles that are less than 100 nanometers in diameter. They've always been there but suddenly, now we have the technology to measure them. They're not regulated, because we don't even know what a safe level is. Government doesn't monitor them on a routine basis, because it's still very expensive. But now we have technology and so we started diving into this so it's a very dynamic environment. Jeffrey Siegel 11:56 Yeah, I mean, exact same factors and I'd add one to Marianne's list and that's cost. The indoor environment, the rooms we're all sitting in right now, if we could take a perfect measurement and capture all the gases and all the particles that are in this space, first of all, we would see things that are not really that well described. And second of all, we would see this very unique signature; your office looks different from your home looks different from your bedroom. And so largely, we're governed by what we can measure, what we can afford to measure, as well as what we know to be important. Chris Yip 12:34 My understanding some of the challenges with air pollutant and particular particles or particular materials, your ability, your body's ability to filter that out, and whether they get pulled deep into the lung, for instance, and that's where I think Marianne, you mentioned particles on sort of a 100 nanometers scale. Maybe for our listeners to get a sense, like how - is that big? Is that small? Marianne Hatzopoulou 12:55 In terms of toxicological effects, there are valid theories that ultra fine particles are able to enter through the bloodstream, so make it through your nose, make it through your lungs, enter through the bloodstream and interact at the intracellular level. And this is why they are of concern. Jeffrey Siegel 13:15 To give a sense of scale here, part of the reason why I love studying particles is that there is this enormous range of interest, probably five or six orders of magnitude in an indoor environment that we care about. Certainly, we care about those very small particles that can go deep into our system, but also those very large particles, they nominally get kind of filtered out, as you said, in our in our upper airways. But still, the mucus carries them into our body and so in an indoor environment, those big particles are highly enriched with organic material, flame retardants, plasticizers, other semi volatile compounds, and then they get carried into our body and can have systemic effects on other organs. Both this big size range indicates where they occur, but then also the composition. Chris Yip 14:04 Let me quickly maybe ask each of you to give us a capsule summary of some of your recent projects and their findings. And Jeff, I'll turn to you. Jeffrey Siegel 14:14 First, an example. I care a lot about filters and filtration to reduce exposure to indoor particles. So we have a field study that finished a couple of years ago, although we're still kind of mining the data, just looking at how filters performed in Toronto houses. And we found so many interesting things just by measuring particle concentrations over a year and 20 houses. If I could summarize what's interesting to me is that the context really determined whether a filter works so the very same filter performed really differently in different houses because of a whole bunch of contextual factors. How much did the furnace run? How much air went through the filter when it did run? How well was the filter sealed into the slot? The fundamental issue is, well how well does the filter work? And then that leads to all these kind of practical issues of what can we do to make filters operate better. Chris Yip 15:13 Speaking to someone who's in a house that currently doesn't actually have forced air, and it relies on radiators, and windows that sort of open with lots of ventilation in a sense, I don't have filters in my house. So how would how would that research actually be helpful for people in different generations of houses? Jeffrey Siegel 15:32 It turns out that even most Canadian homes that have forced air systems, the system just doesn't run that much. With Marianne Touchie, a different Marianne in the department, we published a paper a few years ago that looked at data from about 7000 homes across North America and the average runtime, how often the fan in the furnace air conditioner ran, was less than 20%. So over 80% of the time, air isn't even going through the filter. But I would say that a lot of our findings would apply the exact same way to portable filters. And many people, especially with heightened concern about COVID are using things like portable HEPA filters, and all the same rules and findings apply, you can have the very same filter that performs very differently in one space versus another space. Chris Yip 16:26 Marianne, I know you have a very cool project. It's unfortunate you're on an audio podcasts because it's an awesome thing to look at but maybe can you tell us a little bit about your urban scanner project? Marianne Hatzopoulou 16:37 Yeah. It's been a while in the making. This has been really a long term project, which I'm really happy, we're able to have technology that we can test right now. So urban scanner is this idea of doing mobile air quality monitoring. The idea is not new. It's been around for a decade maybe. I've been doing a lot of mobile studies, on bikes, and on foot and on all sorts of media but the idea here is, we're equipping this vehicle with air quality sensors, other high grade instruments, but at the same time, a 360 degree camera, so it acts sort of like a Google Street View but we don't have all the other cameras that the Google Street View vehicle has. But you know, good idea of what's going on around the road, there was a lidar, there's a ultrasonic anemometer, so there's a wind anemometer as well. And so as the as the vehicle is driving, it's collecting air quality, but it's also collecting data about all these features of the urban environment. You can choose to extract them, or you can choose to just use the image of the street corner as this way to predict everything that's going on in terms of activity in terms of emissions and air pollution. And so we're collecting a lot of data in the city of Toronto with that single vehicle, we're still piloting, we're still testing the technology. The idea is, how can we use that to start spatially interpolating? How can we generate maps for different pollutants across different cities, identify hotspots and eventually use those to validate some of our models? Where we can do some scenario building, scenario testing. What if we started developing transit-oriented development? Everyone lives in the next 50 years close to a transit stop and nobody relocates to the suburbs, what would our city look like? And so if we have a good understanding of what the base case looks like, we can start making projections. Chris Yip 18:34 It very much in a sense of helping us develop a more resilient infrastructure and a safer infrastructure, in a sense, right? And understanding the dynamics of the built environment, and in particular, how it changes over the season, right? Marianne Hatzopoulou 18:48 Yeah, absolutely. Because, again, outdoor air quality is not your effect on outdoor air quality, the way you drive, the way you move, where you live, where you work, all these decisions don't necessarily impact you. We have a lot of great data that show people living in the suburbs enjoy really good air quality, but it's their driving across the city that is actually impacting air quality in areas where you have primarily people who bike and who take transit. We have good evidence of this kind of - it's an injustice, but not in the sense of sociodemographic or social deprivation in the traditional sense, right? Those who generate the pollution are less exposed to it and those who don't generate it are disproportionately exposed to it. It becomes really a collective effort. It's policy, it's regulation, it's all of our actions that can drive change. Chris Yip 19:43 It sounds like a terrific project and so right now you have one vehicle driving around the city and collecting data. This is a project that seems to be a perfect vehicle to - sorry to use a pun (laughing) - a perfect vehicle to link in a fleet of vehicles coming in around the city. Marianne Hatzopoulou 20:00 Yeah, absolutely. With just one vehicle, it's really difficult to make all of these interpolations. The idea is we take these devices, and we just give them to Uber drivers or fleet operators to Canada Post to people who are doing all sorts of delivery, and then they become the sensors themselves. Chris Yip 20:20 So it's a little bit of almost like a citizen science project in a sense. They become the collection for you, in a sense, right? Take advantage of all the vehicles going around. Jeff, it's unfortunate we're talking about COVID all the time but I know that you've certainly been in the media talking a lot about COVID, and good ventilation, and that sort of sense. Maybe can you summarize a little bit about some of your findings in that context? Jeffrey Siegel 20:45 Yes. So the COVID story has been a really interesting story, predominantly because people don't care that much about indoor air. And then, we kind of had a step change in March or so where people cared a lot about air. And it's kind of grown and grown and grown. And I think it's unclear what the future is going to bring. I hope it's not a step change down again. But I think that the biggest thing we've learned in the context of infectious disease transmission is just how important decisions that people make in the building and about the building are. We've known for hundreds of years how important ventilation is to reducing the spread of infectious disease. Turns out that's really important for COVID too. We've known that respiratory droplets are important for the spread of this and other respiratory viruses so things like filtration can make a difference. But I think that for me, a lot of the interesting stories have been all of the personal stories I've come across along the way. So think about all the people I talked to early on in the pandemic, I think I talked to half of the dentist in Toronto who were thinking about reopening their practice and how to do it safely. And I get these calls from people opening sports facilities, doing all kinds of other interesting things. And it's really interesting for me to see the kind of concerns people have, and then also just kind of how much willingness there can be to address the issue. Chris Yip 22:22 It's interesting that it's taken something like the pandemic or COVID to actually trigger this, but you sort of think that annually, you've got the flu going around, you've got other things going around, indoor air quality is, as we said before, it's one of these things you may take for granted, in a sense, right? Jeffrey Siegel 22:39 Yeah, and I think we've talked a lot about the similarity between indoor and outdoor air but there are some really important differences too and number one is regulation. I know that not everything is regulated in outdoor air, but nothing is regulated in indoor air and it never will be regulated. The idea of telling people that you're going to regulate the era in their private dwelling is off the table. Where we have to look to the future is not at things like regulation around the indoor environment, but much more around issues like public education and that ties back to COVID. I think that when people are receptive to hearing information, you can actually get change. Chris Yip 23:20 So I want to wrap up with what are the some of the best things that we could do, either individually or collectively, in terms of your infrastructure or for those of us to improve air quality going forward? Jeffrey Siegel 23:31 Okay, so I think that there may be three themes. The first theme is around equity. As Maryann said, we're all exposed to different air pollution. And some of that is within our control and some of that is not. And so I think as a society, we really have to look at some of the health disparities that arise because of exposures to air pollution, and deploy resources, be they regulation, physical resources, health resources to address the problem where it's most serious. Number two issue is around information. Because you can't see, I mean, polluted air looks more or less the same as clean air. And so because people can't see it, you need to be able to visualize it, provide information and provide a framework by which they can say, "Oh, if I do something, this makes my air better." And then the third theme, I think, is really around innovation and innovative solutions. We've known literally for hundreds of years, that indoor air quality is an issue yet I'm continually surprised people come up with new approaches to make things better and to address particular problems. And so I think we really need to think about how can we do really transformative things to make our buildings safer? Marianne Hatzopoulou 24:54 Yeah, I'll pick up on that. I like those three elements equity, personal behavior and innovation. I'll start with innovation. For sure, we need to drive innovation so we can build better, greener technology. We want to support alternative fuels, alternative vehicles. Will technology save us? No. Chances are, it won't on its own because we also have to alter our behavior. Talking about transportation, how we choose where to live, where to work, what kind of mode of transportation, and then you've got this really cross cutting issue of equity that is super important. You know, everybody's talking about electric vehicles right now. Who's going to own them? Is it going to be people who are already mobility poor, who live further away from the bus line and from the rail line and have very old car that is very polluting? Or is it just people who already have access to a lot? There are huge equity issues associated with how we deploy new technologies. What is the uptake of these new technologies? And that's just regulation. This is policy. This is not industry. This is not individuals. This is policy and the role of government. Chris Yip 26:13 Yeah, that's a terrific point and terrific insights. I think it was a great way to kind of encapsulate that. Something that we're all obviously very dependent on is the air we breathe and we started off by talking about the indoor versus outdoor but then you really sort of brought to bear the fact that everything we do impacts on such a global scale. And there are so many factors which come into play into something which is seems so basic. Terrific to have spent time chatting with you today to really get your your deep insights into this super important topic. Thank you. Marianne Hatzopoulou 26:47 Thank you. Jeffrey Siegel 26:47 Thanks. Chris Yip 26:49 Thanks again for listening to Coffee with Chris Yip. If you want to catch up on past episodes, or make sure that you don't miss the next one, please subscribe. We're on SoundCloud, Apple Podcasts, Spotify, and more. Just look for Coffee with Chris Yip. You can also check out @UofTEngineering on Twitter, Facebook, Instagram and LinkedIn for more stories about how our community is building a better world. And finally, if you've been inspired to join us, we'd love to welcome you. Whether you're thinking of taking a degree or working with us on a research project, you can find us online and engineering.utoronto.ca. Or you can visit our beautiful campus in Toronto, Ontario, Canada. I hope I can join you for coffee soon.