August 29, 2025 • 13 mins
Have you noticed especially hazy skies where you live over the last few summers? While many parts of the world are experiencing more frequent and intense wildfires, even places that are nowhere near the fires are being impacted by the smoke from fires hundreds or thousands of miles away. Wildfire smoke gets so high in the atmosphere, it can be blown across a continent in a matter of days. In this special bonus episode, we’re going to learn the how and why of wildfire smoke that drifts around the world. And we’ll talk a little bit about how to stay safe when air quality goes down. Our guests are Professor Joel Thornton of the University of Washington and Dr. Gregg Furie of Brigham and Women's Hospital in Boston.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Jane (00:20):
This is But Why
Public. I'm Jane Lindholm, andwe're back today with a quick
bonus episode in between regularones. It's a beautiful day here
in Vermont as I'm recordingthis. The sun is shining high up
in a bright blue sky, and fluffyclouds are floating by, and the
(00:40):
mountains in the distance arecrisp and dark against the
horizon. But I have to say,that's not how it's been for a
lot of the summer here in thenortheastern United States,
where But Why is based. The pastfew years have brought us an
atmospheric phenomenon that wedidn't really have all that much
experience with, until recently.Super hazy days where the sun
(01:04):
looks pink and the sky is ablanket of gray and you can't
even see the mountains. The hazeis caused by wildfire smoke that
has been blown into our regionfrom forest fires hundreds or
even thousands of miles away,often in Canada. Depending on
where you live in the world, youmight have experienced this
phenomenon recently, too. Backin 2020, we made a whole episode
(01:28):
about wildfires called "Whathappens to the forest after a
fire?" We'll link to thatepisode in the show notes. But
today's episode isn't about theforests or even the fires. We
wanted to pop in to help explainhow smoke can travel so far and
why so many communities aroundthe country and the world are
seeing these extra hazy dayslately. Plus, we'll talk a
(01:52):
little bit about how to staysafe and healthy if air quality
levels are an issue where youlive. But before we start, we do
want to say we know some of youlive much closer to forest
fires, and some of you have evenexperienced them. That can be
really hard and sometimes scary.Our episode from 2020 includes
conversations with some kidswho've told us a little bit
(02:13):
about what that's like. But fortoday's special episode, to help
us understand the way smoketravels, we called up Joel
Thornton, a professor ofatmospheric and climate science
at the University of Washington.
Dr. Joel Thornton (02:26):
So when forests are on fire, it's
injecting a lot of little tinyparticles into the air, and
those then can travel greatdistances and cover large parts
of the landscape. So when itlooks smoky or hazy, it's
because there are little, tinyparticles in the air that are
like, like grains of sand youmight find at the beach, but
(02:47):
even smaller, that are basicallyblocking the sun from getting to
our eyes.
Jane (02:53):
Professor Thornton says these particles are made of
many, many thousands ofdifferent molecules and
combinations of differentelements. But mostly they're
made of what scientists callcarbonaceous materials, little
particles of trees and leavesand other material that have
been burned by the fire and arelight enough to rise up into the
atmosphere.
Elliot (03:13):
My name is Elliot, and I'm seven years old, and I live
in Camas, Washington. How fardoes smoke travel?
Dr. Joel Thornton (03:21):
Yeah, it's kind of blows my mind every time
I think about it, how fast theair is moving. If I could hold
on to a little of pack of airfor a minute and let it go, that
packet could go around the earthin about two weeks. Fires in
Canada, for example, within justa few days, can be from the
western part of Canada all theway into the eastern part of the
(03:42):
United States, and fires inSiberia in eastern Russia or
pollution created in Beijing inChina, that can be blown across
the Pacific Ocean in the matterof a week or so and end up
impacting places in NorthAmerica.
Jane (03:56):
When Professor Thornton says fires can travel across the
continent in just a couple ofdays, he means the smoke
particles, not the firesthemselves. But why do these
smoke particles travel so farwhen smoke from your campfire or
your wood stove doesn't travelfar at all? The intense heat
from wildfires pushes smoke muchhigher into the atmosphere than
(04:19):
smoke from your campfire couldget. The smoke gets so high,
maybe as much as five milesabove the Earth, that it floats
into the jet stream. The jetstream is a band of strong air
current moving west to eastaround the world. So when soot
from wildfires gets up into thejet stream, it can get blown
across the continent in a matterof days. Plus, when wildfires
(04:43):
are burning, they're often verybig, and there's a lot of smoke
getting into the atmosphere, soit's much more noticeable than
smoke from a smaller fire would be.
Theo (04:53):
My name's Theo. I'm from Madison, Wisconsin. I'm three
years old. Why does so manysmoke in the air?
Jane (05:03):
There's more smoke in the air, primarily, because
wildfires are burning moreforests than they used to. But
why are fires getting moreintense?
Dr. Joel Thornton (05:12):
This is a really important question, and
one that many scientists aretrying to understand and study
right now is what is happeningto the frequency of wildfires,
the intensity? So in otherwords, when a fire starts, how
big does it get? How long doesit go on for? How are those
properties of fires changing?One of the big considerations
(05:34):
right now is that the Earth iswarming. The Earth's sort of
average weather is changing, andit's getting warmer. And warmer
air basically causes trees andthe ground to dry out faster. So
when it's warmer, the air justsort of sucks up the water from
these things. So like when weare in dry desert, our skin gets
(05:54):
really dry and, you know, we getthirsty because we're losing
water to the the atmosphere. Theatmosphere is very hungry for
water in these conditions, andso it takes up the water, and
that causes these materials justto be more ready to burn. So
then what starts those fires canbe natural. So a lightning storm
(06:15):
can happen, and lightning hitsthe tree, the tree catches on
fire, and if that forest isready to burn, and you know, so
drier than it normally would be,it will burn more intensely and
in over a bigger area. There'salso natural variations in the
weather. That's just sometimes aplace gets drier for a summer
(06:35):
than it typically does, andthat's not necessarily because
of climate change. And thenthere's also what we might call
management practices, and sowe've, humans have really
changed our relationship withforests and with land over time,
going back to when we startedclearing forests to make room
for farms and agriculture.That's been going on for really
(06:58):
thousands of years, but also ourcities have been expanding
outwards, so then there's bothchanges in how we interact with
the forest, but also changeswith how we've addressed
fighting wildfires and/ormanaging the forest to help
prevent wildfires.
Winston (07:14):
Hello. My name is Winston. I'm eight years old,
and I live in Kaawa, Hawaii. Whyis smoke a bad smell, but
firewood a good smell?
Dr. Joel Thornton (07:24):
Smell is a very complicated science. You
know, you'd be surprised at justhow one little difference in a
molecule might change the smellcompletely. Firewood that you're
using to sit in your fireplaceat home, maybe it's a specific
type of wood. It's probably verydry, whereas wildfires, there's
lots of things burning, thingslike the dirt is literally
(07:44):
burning in a wildfire. The deadleaves on the ground, somewhat
still living branches and treesare burning. And that's not what
you would normally put in yourfireplace. But I will say, if
smoke from firewood in yourfireplace or smoke from a
wildfire and both not good tobreathe. And you should, you
know, try to avoid breathingother kinds of smoke.
Jane (08:06):
Speaking of breathing, we're going to talk a little bit
about how we can stay safeduring wildfire smoke season.
Stay with us.
This is but why. I'm JaneLindholm. Before the break, we
learned about how smoke travelsin the air and can reach us,
even if we live far away from awildfire. Now we're going to
talk about how we can stay safeand healthy when the air feels
(08:28):
hazy and thick.
Dr. Gregg Furie (08:29):
My name is Gregg Furie. I am a primary care
doctor. I also have a job as themedical director for climate and
sustainability at Brigham andWomen's Hospital in Boston.
Jane (08:41):
We have some questions from kids about the health
effects of wildfire smoke.
Piper (08:45):
My name is Piper. I'm nine years old, and I live in
Camas, Washington. Why is it badto breathe in smoke in the air?
Dr. Gregg Furie (08:55):
That's a great question. In general, when we
talk about smoke, we're talkingabout something called
particulate matter pollution.
Jane (09:03):
That's those teeny, tiny particles in the air caused by
wildfires and things burning.That soot, or particulate matter
pollution, is what's going upinto the atmosphere and making
the air we breathe less clean.
Dr. Gregg Furie (09:16):
When people breathe in particulate matter
pollution, it can certainlyaffect the lungs, but in fact,
those really, really, reallysmall particles can get into the
body and then can go on toaffect essentially any part of
the body. And so that'sprimarily how people get exposed
to kind of the health effectsfrom from smoke is through
(09:38):
breathing it in.
Jane (09:39):
One of those health effects might be a tickle in
your throat.
Ava (09:42):
I'm Ava. I'm seven years old. I live in San Antonio,
Texas. Why does smoke make youcough?
Dr. Gregg Furie (09:50):
The main reason that people will kind of cough
when they're exposed to smoke isbecause they're caught, these
fine particles in the air causeinflammation in the lungs. So
that is your body appropriatelyresponding to these foreign
particles through a process ofinflammation, but that can often
(10:10):
trigger something like coughing.It can also trigger symptoms
like wheezing, a sense of yourchest feeling tight or shortness
of breath.
Jane (10:19):
Generally, hazy days aren't too much of a problem,
but there are people who aremore vulnerable or more affected
by polluted air who need to payextra special attention.
Dr. Gregg Furie (10:30):
People who have lung diseases like asthma, or
some adults who have somethingcalled chronic obstructive
pulmonary disease or COPD,people who have heart conditions
or health conditions that affecttheir blood vessels, people who
are very old or very young, andpregnant women tend to be the
groups that are at the highestrisk. And so, if someone is in
(10:54):
one of those groups, then theyshould know that they need to
take kind of extra precaution.
Jane (10:58):
One way to know if air quality in your region might be
a problem is just to look at thesky. You can often see smoke in
the air because the sun looksdifferent and the sky isn't
blue, even on a day when it'snot cloudy, and the buildings or
trees look a little like they'recovered in fog or haze. But
another way is to look atsomething online called the AQI,
(11:19):
the Air Quality Index. The USgovernment monitors air quality
and lets you know what it's likein your area by putting a number
on it. The Air Quality Indexranges from zero to 500. Zero is
very clean air and 500 is verypolluted air.
Dr. Gregg Furie (11:37):
Once the AQI or the air quality index goes above
100 but it's less than 300,people who are in some of the
more sensitive groups, thosepeople should be starting to
think about how they're going totake some precautions. Once the
air quality index is going to begoing over 300, then everybody
needs to be considering howthey're going to take some
(11:57):
precaution.
Jane (11:58):
You probably don't need to worry about the AQI. Your adults
can help you keep an eye on airquality in your region. They
often hear about that on theradio or TV, or on a weather app
on their computer or phone orwatch. And they can help let you
know if you need to slow down onyour outdoor activities or maybe
wear a mask that can filter outsome of that pollution. Some
(12:21):
people get special filters fortheir homes or the buildings
they work or go to school in,too. And Dr. Furie says it's
always good to check in withyour doctor if you're in one of
those sensitive groups, so youcan have a plan if the air
quality gets bad. Living withwildfire smoke is a new reality
for many of us, and your adultsmight be navigating it for the
(12:43):
first time, too. So maybe youcan make checking the Air
Quality Index together part ofyour routine during wildfire
season. Thanks to Professor JoelThornton and Dr. Gregg Furie for
helping us understand wildfiresmoke, how it travels and how it
affects us. As always, if youhave a question about anything,
have an adult record you askingit on a smartphone using an app
(13:06):
like voice memos or recorder,then have them email the file to
questions@butwykids.org. If youlike our show, please have your
adults help you give us a thumbsup or a review on whatever
podcast platform you use tolisten to us. It helps other
kids and families find us. ButWhy is produced by Melody
Bodette, Sarah Baik and me JaneLindholm at Vermont Public. Our
(13:29):
video producer is Joey Palumbo.Luke Reynolds wrote our theme
music and we're distributed byPRX. We'll be back next week
with an all new episode. Untilthen, stay curious.
This is But Why
Public. I'm Jane Lindholm, andwe're back today with a quick
bonus episode in between regularones. It's a beautiful day here
in Vermont as I'm recordingthis. The sun is shining high up
in a bright blue sky, and fluffyclouds are floating by, and the
(00:40):
mountains in the distance arecrisp and dark against the
horizon. But I have to say,that's not how it's been for a
lot of the summer here in thenortheastern United States,
where But Why is based. The pastfew years have brought us an
atmospheric phenomenon that wedidn't really have all that much
experience with, until recently.Super hazy days where the sun
(01:04):
looks pink and the sky is ablanket of gray and you can't
even see the mountains. The hazeis caused by wildfire smoke that
has been blown into our regionfrom forest fires hundreds or
even thousands of miles away,often in Canada. Depending on
where you live in the world, youmight have experienced this
phenomenon recently, too. Backin 2020, we made a whole episode
(01:28):
about wildfires called "Whathappens to the forest after a
fire?" We'll link to thatepisode in the show notes. But
today's episode isn't about theforests or even the fires. We
wanted to pop in to help explainhow smoke can travel so far and
why so many communities aroundthe country and the world are
seeing these extra hazy dayslately. Plus, we'll talk a
(01:52):
little bit about how to staysafe and healthy if air quality
levels are an issue where youlive. But before we start, we do
want to say we know some of youlive much closer to forest
fires, and some of you have evenexperienced them. That can be
really hard and sometimes scary.Our episode from 2020 includes
conversations with some kidswho've told us a little bit
(02:13):
about what that's like. But fortoday's special episode, to help
us understand the way smoketravels, we called up Joel
Thornton, a professor ofatmospheric and climate science
at the University of Washington.
Dr. Joel Thornton (02:26):
So when forests are on fire, it's
injecting a lot of little tinyparticles into the air, and
those then can travel greatdistances and cover large parts
of the landscape. So when itlooks smoky or hazy, it's
because there are little, tinyparticles in the air that are
like, like grains of sand youmight find at the beach, but
(02:47):
even smaller, that are basicallyblocking the sun from getting to
our eyes.
Jane (02:53):
Professor Thornton says these particles are made of
many, many thousands ofdifferent molecules and
combinations of differentelements. But mostly they're
made of what scientists callcarbonaceous materials, little
particles of trees and leavesand other material that have
been burned by the fire and arelight enough to rise up into the
atmosphere.
Elliot (03:13):
My name is Elliot, and I'm seven years old, and I live
in Camas, Washington. How fardoes smoke travel?
Dr. Joel Thornton (03:21):
Yeah, it's kind of blows my mind every time
I think about it, how fast theair is moving. If I could hold
on to a little of pack of airfor a minute and let it go, that
packet could go around the earthin about two weeks. Fires in
Canada, for example, within justa few days, can be from the
western part of Canada all theway into the eastern part of the
(03:42):
United States, and fires inSiberia in eastern Russia or
pollution created in Beijing inChina, that can be blown across
the Pacific Ocean in the matterof a week or so and end up
impacting places in NorthAmerica.
Jane (03:56):
When Professor Thornton says fires can travel across the
continent in just a couple ofdays, he means the smoke
particles, not the firesthemselves. But why do these
smoke particles travel so farwhen smoke from your campfire or
your wood stove doesn't travelfar at all? The intense heat
from wildfires pushes smoke muchhigher into the atmosphere than
(04:19):
smoke from your campfire couldget. The smoke gets so high,
maybe as much as five milesabove the Earth, that it floats
into the jet stream. The jetstream is a band of strong air
current moving west to eastaround the world. So when soot
from wildfires gets up into thejet stream, it can get blown
across the continent in a matterof days. Plus, when wildfires
(04:43):
are burning, they're often verybig, and there's a lot of smoke
getting into the atmosphere, soit's much more noticeable than
smoke from a smaller fire would be.
Theo (04:53):
My name's Theo. I'm from Madison, Wisconsin. I'm three
years old. Why does so manysmoke in the air?
Jane (05:03):
There's more smoke in the air, primarily, because
wildfires are burning moreforests than they used to. But
why are fires getting moreintense?
Dr. Joel Thornton (05:12):
This is a really important question, and
one that many scientists aretrying to understand and study
right now is what is happeningto the frequency of wildfires,
the intensity? So in otherwords, when a fire starts, how
big does it get? How long doesit go on for? How are those
properties of fires changing?One of the big considerations
(05:34):
right now is that the Earth iswarming. The Earth's sort of
average weather is changing, andit's getting warmer. And warmer
air basically causes trees andthe ground to dry out faster. So
when it's warmer, the air justsort of sucks up the water from
these things. So like when weare in dry desert, our skin gets
(05:54):
really dry and, you know, we getthirsty because we're losing
water to the the atmosphere. Theatmosphere is very hungry for
water in these conditions, andso it takes up the water, and
that causes these materials justto be more ready to burn. So
then what starts those fires canbe natural. So a lightning storm
(06:15):
can happen, and lightning hitsthe tree, the tree catches on
fire, and if that forest isready to burn, and you know, so
drier than it normally would be,it will burn more intensely and
in over a bigger area. There'salso natural variations in the
weather. That's just sometimes aplace gets drier for a summer
(06:35):
than it typically does, andthat's not necessarily because
of climate change. And thenthere's also what we might call
management practices, and sowe've, humans have really
changed our relationship withforests and with land over time,
going back to when we startedclearing forests to make room
for farms and agriculture.That's been going on for really
(06:58):
thousands of years, but also ourcities have been expanding
outwards, so then there's bothchanges in how we interact with
the forest, but also changeswith how we've addressed
fighting wildfires and/ormanaging the forest to help
prevent wildfires.
Winston (07:14):
Hello. My name is Winston. I'm eight years old,
and I live in Kaawa, Hawaii. Whyis smoke a bad smell, but
firewood a good smell?
Dr. Joel Thornton (07:24):
Smell is a very complicated science. You
know, you'd be surprised at justhow one little difference in a
molecule might change the smellcompletely. Firewood that you're
using to sit in your fireplaceat home, maybe it's a specific
type of wood. It's probably verydry, whereas wildfires, there's
lots of things burning, thingslike the dirt is literally
(07:44):
burning in a wildfire. The deadleaves on the ground, somewhat
still living branches and treesare burning. And that's not what
you would normally put in yourfireplace. But I will say, if
smoke from firewood in yourfireplace or smoke from a
wildfire and both not good tobreathe. And you should, you
know, try to avoid breathingother kinds of smoke.
Jane (08:06):
Speaking of breathing, we're going to talk a little bit
about how we can stay safeduring wildfire smoke season.
Stay with us.
This is but why. I'm JaneLindholm. Before the break, we
learned about how smoke travelsin the air and can reach us,
even if we live far away from awildfire. Now we're going to
talk about how we can stay safeand healthy when the air feels
(08:28):
hazy and thick.
Dr. Gregg Furie (08:29):
My name is Gregg Furie. I am a primary care
doctor. I also have a job as themedical director for climate and
sustainability at Brigham andWomen's Hospital in Boston.
Jane (08:41):
We have some questions from kids about the health
effects of wildfire smoke.
Piper (08:45):
My name is Piper. I'm nine years old, and I live in
Camas, Washington. Why is it badto breathe in smoke in the air?
Dr. Gregg Furie (08:55):
That's a great question. In general, when we
talk about smoke, we're talkingabout something called
particulate matter pollution.
Jane (09:03):
That's those teeny, tiny particles in the air caused by
wildfires and things burning.That soot, or particulate matter
pollution, is what's going upinto the atmosphere and making
the air we breathe less clean.
Dr. Gregg Furie (09:16):
When people breathe in particulate matter
pollution, it can certainlyaffect the lungs, but in fact,
those really, really, reallysmall particles can get into the
body and then can go on toaffect essentially any part of
the body. And so that'sprimarily how people get exposed
to kind of the health effectsfrom from smoke is through
(09:38):
breathing it in.
Jane (09:39):
One of those health effects might be a tickle in
your throat.
Ava (09:42):
I'm Ava. I'm seven years old. I live in San Antonio,
Texas. Why does smoke make youcough?
Dr. Gregg Furie (09:50):
The main reason that people will kind of cough
when they're exposed to smoke isbecause they're caught, these
fine particles in the air causeinflammation in the lungs. So
that is your body appropriatelyresponding to these foreign
particles through a process ofinflammation, but that can often
(10:10):
trigger something like coughing.It can also trigger symptoms
like wheezing, a sense of yourchest feeling tight or shortness
of breath.
Jane (10:19):
Generally, hazy days aren't too much of a problem,
but there are people who aremore vulnerable or more affected
by polluted air who need to payextra special attention.
Dr. Gregg Furie (10:30):
People who have lung diseases like asthma, or
some adults who have somethingcalled chronic obstructive
pulmonary disease or COPD,people who have heart conditions
or health conditions that affecttheir blood vessels, people who
are very old or very young, andpregnant women tend to be the
groups that are at the highestrisk. And so, if someone is in
(10:54):
one of those groups, then theyshould know that they need to
take kind of extra precaution.
Jane (10:58):
One way to know if air quality in your region might be
a problem is just to look at thesky. You can often see smoke in
the air because the sun looksdifferent and the sky isn't
blue, even on a day when it'snot cloudy, and the buildings or
trees look a little like they'recovered in fog or haze. But
another way is to look atsomething online called the AQI,
(11:19):
the Air Quality Index. The USgovernment monitors air quality
and lets you know what it's likein your area by putting a number
on it. The Air Quality Indexranges from zero to 500. Zero is
very clean air and 500 is verypolluted air.
Dr. Gregg Furie (11:37):
Once the AQI or the air quality index goes above
100 but it's less than 300,people who are in some of the
more sensitive groups, thosepeople should be starting to
think about how they're going totake some precautions. Once the
air quality index is going to begoing over 300, then everybody
needs to be considering howthey're going to take some
(11:57):
precaution.
Jane (11:58):
You probably don't need to worry about the AQI. Your adults
can help you keep an eye on airquality in your region. They
often hear about that on theradio or TV, or on a weather app
on their computer or phone orwatch. And they can help let you
know if you need to slow down onyour outdoor activities or maybe
wear a mask that can filter outsome of that pollution. Some
(12:21):
people get special filters fortheir homes or the buildings
they work or go to school in,too. And Dr. Furie says it's
always good to check in withyour doctor if you're in one of
those sensitive groups, so youcan have a plan if the air
quality gets bad. Living withwildfire smoke is a new reality
for many of us, and your adultsmight be navigating it for the
(12:43):
first time, too. So maybe youcan make checking the Air
Quality Index together part ofyour routine during wildfire
season. Thanks to Professor JoelThornton and Dr. Gregg Furie for
helping us understand wildfiresmoke, how it travels and how it
affects us. As always, if youhave a question about anything,
have an adult record you askingit on a smartphone using an app
(13:06):
like voice memos or recorder,then have them email the file to
questions@butwykids.org. If youlike our show, please have your
adults help you give us a thumbsup or a review on whatever
podcast platform you use tolisten to us. It helps other
kids and families find us. ButWhy is produced by Melody
Bodette, Sarah Baik and me JaneLindholm at Vermont Public. Our
(13:29):
video producer is Joey Palumbo.Luke Reynolds wrote our theme
music and we're distributed byPRX. We'll be back next week
with an all new episode. Untilthen, stay curious.
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