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Ten years ago, I asked my partner, Kelsey, if she would marry me. I did that, despite the fact that every living member of my family who had ever been married had also gotten divorced. Forever is a Long Time is a five-part series in which I talk to those relatives about why they got divorced and why they got married. You can listen to it now on CBC's Personally. This is a CBC Podcast.
Hi, I'm Dr. Brian Goldman. Welcome to The Dose. These days in Canada, summer means wildfire season, and with that comes smoke. On top of the usual air pollution, Canadian cities typically experience both during colder and warmer weather. So this week we are asking, how does poor air quality affect my health?
Hi, Chris. Welcome to The Dose. Hi, Brian. I hear that you ask volunteers to inhale harmful toxins and measure their reactions. How the heck does that work? Yeah, so in all seriousness, this is really why our lab is known worldwide, the Air Pollution Exposure Lab.
There's an area of science that needs to be filled between animal work and cellular work, which we can talk more about, and epidemiology, which is observational. We can also get into that. There's an area where we need to actually look at real people in front of us under controlled circumstances and see how they respond to air pollution. But of course, we do it in a very controlled and safe way.
And in that way, you're able to obtain objective measurements. These aren't subjective wild-arse guesses of how pollution affects people's health. You want to drill down to the cellular level and actually find out what it does, which is why we've come to you. But before we begin our conversation, can you give us a hi, my name is, tell us what you do and where you do it.
I'm Dr. Chris Carlston. I'm a professor of medicine at the University of British Columbia. I'm the head of the respiratory medicine division there. I run a lab that's called the Air Pollution Exposure Lab, whose mission really is to understand health effects of air pollution on the body, especially the lungs, and use that information to inform public health and protect people.
We hear that Canada's summer air quality is getting worse. I have no reason to doubt that. But how do we know? How do we measure objectively that that is the case?
Yeah, it is very objective because there are instruments all over the province and really over the world at this point in time. Funny enough, you can, if you kind of are looking for them or if you look on a map and know where they are, and these maps are easy to find now online, you'll look up, see buildings, see these funny instruments, these small towers, etc.,
again, spread throughout the province and the world. And they're measuring at a fine level of detail both the particles and the gases that are in air pollution.
There are weather reports and there's something called the Air Quality Health Index. What does that measure? Yeah, Air Quality Health Index is an interesting thing because it's really an innovation that started in Canada. So there's some understandable pride about that. And the Air Quality Health Index takes the different pollutants that we're concerned about and combines them into one number from 1 to 10 or really 11 if you consider the extreme numbers.
By doing that, it allows the community to see in a microsecond, if you just go to any website that follows the AQHI, what in your community or in other communities that you're traveling to today or even in some cases predicted into the future, what is that AQHI on that 1 to 10 or rarely 11 when it's again extreme scale, integrating the different pollutants and giving you a general sense of
of how polluted the air is and how worried we should be. So what does a number two mean, for instance, compared to, say, a five or a seven? One is good and 10 is bad, so to speak. And two is almost as good as it gets, as you can imagine, because one is the best. Two means really there's very little to be
concerned about, where we're generally happy, so to speak, to see a two. Five is a good number to talk about, Brian, because it is in the middle and it gets into this really important issue of who is at risk at a different or given level of air pollution. And in that middle range of the AQHI, that's where there's a lot of variability in how a given person will respond. Meaning
in that kind of five to seven range, a lot of people will not be bothered at all. It'll have very little risk and probably won't change their activity very much, where there are others who are
really at higher risk, who are susceptible. That's a word that's important in our understanding of who's at higher risk susceptibility. And those people have to be more careful. There is one more thing I'll say about this whole kind of concept of risk, which is that the AQHI and other similar type of instruments is really oriented to short-term risk. It's a bit of a problem
It's okay in the sense that most people are worried about short-term risk, and we tend to think that way, and it's understandable. You have a soccer match, you have a bard on the beach, etc. These events, we need to think, what are we going to do tomorrow and next week? But it doesn't capture very well the long-term risk.
Is there a number at which a good chunk of the population is going to notice that the air quality is poor? That's a really interesting question. It kind of prompts me to say there's some really basic things that we don't know. Probably we should. And I certainly can't give you a number. But a lot of it has to do, Brian, with visualization. And there's a kind of an interesting challenge there.
terms of what we see if you look out the window versus the risk. And so we typically look at PM 2.5. It's a bit of a technical thing, but we really have to briefly talk about it given its importance. PM refers to a particular matter. The 2.5 refers to microns, which are very small fractions of
A micron is one one-thousandth of a millimeter. Most people can understand a millimeter, but it's quite small. You can barely see it. 2.5 micron, you can't see it with the naked eye, but these are small particles that get deep in your lung and cause the damage that we know about.
When that measure of micrograms of PM 2.5 per cubic meter, again, a bit of a mouthful, but you take a cubic meter of air, so a box with a meter on each side, and you fill it up with particles, you can measure the micrograms of those particles of that size, PM 2.5. It sounds crazy, but it's critically important. We measure it all around the world on a minute-by-minute basis and
it over days and years. And all these things are used, all these averages are used to
decide if places are in compliance, if they get fined, if they lose funding from the government, etc. Is that important? Because the literature shows how that PM2.5 affects our lungs. Getting back to your question, we can see when the air quality deteriorates, say, above 50 micrograms per cubic meter. It depends on various factors, sun, rain, etc. But
we can see it at a level that's much higher than the safe levels. That's really my point. So when you said, will people notice? Well, people will not notice visually levels that are actually concerning.
They will notice in terms of smell and maybe just a general sense of poor air quality when the levels are much higher than we really want them to be. And that's a fundamental paradox about understanding air quality. Really, the only way you'll know if the air quality is poor is by looking online because it's
It's technically harmful far before we can see that. What are the typical pollutants in Canadian air? There's ozone. Ozone is what we call a secondary air pollutant. It means that it doesn't really come out
of engines or fires, but it is created when the primary pollutant, the stuff that comes right out of the engine or the fire or the fireplace, when that is subjected to ultraviolet light, basically sun and the general atmospheric processes, that's again, chemistry, that's a little complex, but over time, ozone forms, that's the second one.
nitrogen dioxide is a gas that's also problematic sulfur dioxide another gas that one's been
improving over time. Lead was a problem, not so much anymore. And there are others, but those are the main ones. We're going to take these one at a time. Let's start with people who have pre-existing conditions like heart disease, chronic obstructive pulmonary disease. How do these pollutants exacerbate those pre-existing conditions? There's a couple of really important concepts here, Brian, for the audience.
And one is that those individuals with those diseases you mentioned and others have less reserve. So the way I always think about this is that we're all affected on some level by pollution. But the more reserve we have, the farther we are away from actually being
feeling it and having bona fide health problems. And by reserve, what I mean is it's essentially a distance. It's sort of a physiologic or the body's operational distance between where it's at and where it's going to get into trouble. And if you have COPD, asthma, cardiac disease, etc., that distance between where you're at and where you get into trouble is smaller.
So less pollution can take you from that compromised position you're already in on a day-to-day basis, even without pollution, and kind of push you over the edge into problems. Whereas if I, thankfully, I'm lucky enough as far as I know not to have those conditions,
If I get lung inflammation, I might feel a little bit uncomfortable. I may or may not even notice it, but I'm far enough away from where we get into real trouble, breathing problems, needing to go to the emergency room, etc., that I can kind of get away with it, so to speak. Again, on the short term, we have to remember long term is different.
Whereas if I have COPD and I'm constantly a small margin away from breathing problems, or maybe I have breathing problems on a day-to-day basis anyway, and it's only a matter of how much worse they can get, then we just don't have that buffer. So I said reserve, you could call it buffer resiliency. There's
different words that kind of describe the same thing. But again, the distance between where you're at, the physiologic distance essentially from where you're at to where you get into trouble. That's one big concept. The other one is just that these individuals who have pre-existing disease are already prone to some of the processes that pollution causes. And one of the
terms is oxidative stress. And we always kind of have to talk about it, even though it's a mouthful. And that's essentially the effect of pollution on our cells. It's basically depletion
inflammation, but a particular kind of inflammation that our body responds to by antioxidants. Now, most people have heard of antioxidants. You can essentially buy them or supplement in your diet. So oxidative stress is what antioxidants are meant to fight and to protect us from. The problem is if you have COPD, et cetera, your level of antioxidants is already depleted
depleted or decreased by your day-to-day challenges of COPD, etc. So there again, you're sort of at a deficit, at a compromise. And then by getting this additional insult of pollution, you have that much more of a challenge dealing with it.
what patients will notice in that state, patients who have pre-existing asthma, chronic obstructive pulmonary disease, heart disease, heart failure, is that they might have increased shortness of breath or possibly chest pain with ordinary activities if they're out and about on a poor air quality day. That's right. We'll think about the breathing part of it, and then we can, it's basically similar for the cardiac or heart part of it. If
For the breathing part of it, of course, we breathe through these tubes. The lungs are a branching tree of tubes. If we are healthy, have wide open tubes that have a lot of room before they're so narrow that we'd feel it. So
Again, healthy individual, wide open tube, narrow it a little, doesn't really notice. Narrow it a little bit more, doesn't really notice. If you narrow it enough, you're going to feel it. The person with COPD or asthma starts every day with a somewhat narrowed tube because that's what asthma and COPD does, unfortunately. Depends on how severe, etc. But by definition, asthma and COPD are going to have some narrowing, some compromise of the breathing tubes. And
And so it's that much easier to get to the point where that tube is narrow enough that they feel it. And the same is effectively true for cardiac disease. Hey, I'm Reshma Sajani, founder of Girls Who Code and Moms First. I consider myself a pretty successful adult woman. So why is it that in midlife, as I'm about to turn 50, I feel so stuck?
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chronic obstructive pulmonary disease, heart disease, asthma, et cetera. How is air pollution associated with diseases that are beyond the lungs and the heart? Neurologic conditions like dementia, autism, ADHD, to name three. So this has really been the growing frontier of what we do in this science over the last couple of decades. And it's continuing to to
to be a really active area. The basic answer to your question, Brian, is that we used to think that the pollution comes into the lungs and it affects the lungs. And thankfully, that's it because the lungs are kind of a dead end when you go branch, branch, branch, branch. And incidentally, the lungs branch 26 times until they're at the end of the road, which is the so-called alveoli. These are tiny, tiny little sacs and there are millions of them.
But anyway, we thought that that was a self-contained kind of unit. So one of the big, big breakthroughs was that the particles that I mentioned before, they can actually go from those alveoli, those tiny sacs that are at the end of 26 divisions of the branching lung tree, and they can sneak essentially from those tiny sacs into the bloodstream. That was a revolutionary finding some years ago.
Once those particles are in the bloodstream, they then circulate around the body as the blood does. And now effectively they're on their way to affecting most any organ because of the way that our body circulates blood around the entire body. There are some other theories and some other pathways, as we call them, that's probably leading to the effects that you mentioned. But at least some particles are getting into the blood, circulating and causing problems. You might ask,
What are those other things you mentioned? Well, one is that it may not always be the particles that get across from the lung into the bloodstream, but sometimes the particles can create havoc in the lungs. This inflammation and oxidative stress that I mentioned before
The inflammation and oxidative stress can pass into the body through the bloodstream. Even if the particles get trapped, because most of them do, most particles don't actually make it into the blood. Just a small percentage do. But even without the particles doing their problem in the bloodstream, causing their harm in the bloodstream, inflammation itself can pass from the lungs into the blood and then cause problems there.
across the entire body. And by the way, I should mention, as time goes on, there's virtually no organ in the body that has been speared. And I think you might have mentioned dementia. So dementia is obviously a disease of the brain.
The brain was long thought to be the most protected organ in the body. And it may well be, relatively speaking, the most protected, but it is not sufficiently protected from air pollution. And there's emerging literature, including our own, describing this issue not only with dementia, but with Parkinson's disease, with Alzheimer's disease, etc.
You mentioned ADHD. The evidence is not quite as strong there, but these things are all being studied by Canadian researchers and others. Bit of a change in topic. How does air pollution in Canada change depending on where you live? There's sort of good news and bad news there. Away from urban population centers, traffic-related pollution generally gets better.
Depends a little bit on details. If you're working on a farm with a lot of tractors and diesel equipment, you might not be so lucky, even though in general, rural areas are better. The problem is wildfire smoke.
wildfire smoke sort of changes the equation dramatically because a lot of the fires are actually in the remote areas. And moreover, the wind will carry the products of wildfires far from their original source. So really, that's where the bad news comes in. No area really is spared anymore, no matter how remote of a community you are, depending again on the winds and the source of the fire. And we know now that
Close to 100%, somewhere in the 95% to 99% of the population worldwide, and certainly in the 90s of percentile even in Canada, is exposed on an average annual basis to air quality that is less than
than what the World Health Organization recommends. So that's been a really sobering thing, the massively high percentage of world population that is living day to day in quality that's not acceptable by a very reasonable World Health Organization standard.
So since you've mentioned wildfire smoke, what's in wildfire smoke in terms of pollutants? And how does that compare to the typical air pollutants that we experience when we're not in the midst of wildfire season? Yeah, it's a critical question. And lots of people are doing work on that. But the basic answer is that most of the same things, the particles and gases that I mentioned, are in both tractors.
traffic-related pollution or industry-related pollution and wildfire smoke. So fire smoke has lots and lots and lots of very small particles and not so, so much gas. It does have gases, but not as much, relatively speaking, as traffic. The second piece that I mentioned is also critically important, but a
I'm getting at what happens to fire smoke as it travels away from the source. As fire smoke moves away from the dramatic flames and the big black cloud of smoke to more distant places with the wind, and we know they can travel thousands of kilometers.
Over that period of time, which is days to weeks, that this fire smoke travels that far, it changes dramatically. And over those days to weeks, it goes from being pretty much just particles with a small amount of gas to having a lot more gases and a lot more toxic gases. I remember not too many days ago, Toronto, where we're recording this from, had the worst air quality on the planet.
Yeah, we've had it in Vancouver too. And Vancouver for... It's still considered one of the cleanest cities in the world, but it's got this big asterisk now where it didn't when I moved here 20 years ago. Fires were just kind of here and there and not nearly to this extent. And now it's...
It's completely routine that we have a big fire and not unusual that at least on one day of the year, every so often, every couple of years that we have the worst deer quality in the world. So yeah, it happens. And even though we aren't close to wildfire smoke or haven't been close to wildfire smoke in Toronto, there's been a lot of it in Northern Ontario as
And some of that has obviously traveled south. Yeah, Ontario is in rough shape right now. Honestly, I was looking and I'm kind of looking now at this real time map that's available. It's called firesmoke.ca. And you can see how much Ontario is suffering much more than B.C. I mean, B.C. at this very moment actually looks pretty darn good. And Ontario is, you know, it's a color coded map and it's dark.
Okay, so now it's time to talk about what we can do to minimize the risk. I guess the first question I want to ask you is how much should we be paying attention to measures like Air Quality Health Index? It kind of depends on your personality. Like, are you someone who's going to take action based on...
this kind of knowledge. Now, frankly, some people won't, and that's okay. That's a personal choice. Some people are really into taking action based on data that they can obtain. And, you know, they have three different types of watches gathering data. They've got tons of websites that they regularly check, you know, there's everything in between. But I do encourage people to get familiar with the Air Quality Health Index we talked about before.
As far as smoke, I mentioned firesmoke.ca. It's very intuitive. It's incredibly obvious what's going on. So there's lots of data sources. But then the bigger challenge, I guess, is what level of risk are we willing to accept?
And we have a whole project funded by the Canadian government that really works with communities to understand what level of risk are they willing to accept? To what extent can you minimize the risk of harm on those poor air quality days by going indoors and closing the windows? A lot, depending on the types of filtration systems. But basically the
whether it's an apartment complex or a commercial building, etc. The bigger and newer, the better the filters are likely to be, especially because there are now strict standards on new buildings in terms of the air filtration. The concern is a bit more in your kind of average, older Vancouver, other parts of Canada drawing. I said Vancouver because we tend to have leaky homes here. It's not so, so cold. So it's not as much of a
sort of imperative to make the homes really tight. So we have kind of notoriously leaky homes in this province. And so a lot of that pollution can get in.
In those cases, what is really effective, and again, thankfully, research has done a good job substantiating this, these tower air cleaners are often called ear purifiers. Those work really, really well. And I should tell the audience, I'm constantly writing prescriptions for an ear cleaner. You can't just have your insurance pay for it, but you can go pay for yourself and deduct it from your taxes. Do you ever recommend face masks?
I do now. So this kind of goes along with my own evolution. I used to sort of think that if we wore face masks, we're just ignoring the problem. And then everyone's just happily walking around with masks and pollution. And the reality is no one likes pollution. I don't think it's going to make anyone any happier about pollution.
We may be not so happy about a world where everyone's wearing face masks. We're kind of used to that now. And they work. And that's probably the most important part of my message here is that we now have increasing evidence that masks work.
They work a lot better if they're the so-called N95. So N95 masks work a lot better, especially if they fit well and don't have a beard getting in the way, etc. But even other masks, even surgical masks, they don't work great, but they're better than nothing. So with masks, I'm basically any are generally better than nothing, right?
N95 are really much better than sort of simpler masks. And again, we have to consider that this is part of the equation and not just pretend the problem doesn't exist. And just to pin you down, at what level of AQHI would you be recommending that people consider wearing masks? I think we should all consider it at eight and above, like no matter what your health condition is.
And I think anyone with the aforementioned conditions or age groups should consider it at five and above. Well, Dr. Chris Carlston, you've given us a lot to think about here. And that's the point, that people think about this a lot more than they have in the past, given the fact that air pollution is getting worse because of wildfire smoke issues.
and other sources of pollution. And I want to thank you for coming on to The Dose to talk about it. It's my pleasure. I think your program does a lot of good education. Keep it up. Dr. Chris Carlston is a professor of medicine at UBC and director of the Air Pollution Exposure Lab. Here's your Dose of Smart Advice. Air pollution comprises different toxins that include wildfire smoke. They enter the body through the lungs.
Harmful toxins that pollute the air include particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. Fine particulate matter can penetrate deep inside the lungs and, if they enter the bloodstream, can damage almost any organ in the body. Toxic particles cause damage by promoting inflammation, oxidative stress, immune system suppression, and by causing cancer as well as mutations in our DNA.
Children, the elderly and pregnant women are more susceptible to air pollution related diseases. Health problems can occur through both short and long term exposure to air pollutants. The levels and duration of exposure that are considered safe vary with the pollutant. In some cases though, there are no levels below which exposure can be considered risk free. Short term exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections and aggravated asthma.
Long-term exposure to fine particulate matter increases the risk of stroke, heart disease, chronic obstructive pulmonary disease, and cancer. There is some evidence that air pollution increases the risk of miscarriage and low birth weight infants. For people with pre-existing heart or lung disease, exposure to lower levels of air pollution increases the risk of harm. Wildfire smoke gets worse the farther you are from the source of the smoke.
While the concentration of particulate matter decreases, the concentration of toxic gases increases. The impact of exposure to air pollution may not be apparent for days, weeks, months or even years. But worldwide, air pollution causes or contributes to 9 million excess deaths per year. Stay indoors on days when the outdoor air quality is poor. Limit the number of trips you take outdoors and avoid outdoor exercise and other intense physical activity.
Masks are moderately effective at blocking exposure to particulate matter. The best kind of mask to use is a well-fitted N95 or KN95 mask. A HEPA filter or portable air filtration machine makes indoor air quality safer. If you have topics you'd like discussed or questions answered, our email address is thedoseatcbc.ca. If you liked this episode, please give us a rating and review wherever you get your podcasts.
This edition of The Dose was produced by Samir Chhabra, our senior producer is Colleen Ross. We're going to take a break for the summer, but be sure to check out our feed for compilations of some of our most popular Dose episodes. We'll be back after Labor Day with a whole new season. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health care provider. I'm Dr. Brian Goldman. Until your next dose. For more CBC Podcasts, go to cbc.ca slash podcasts.