[mellow music on acoustic guitar]
TIM WATKINS: Hi, I'm Tim Watkins.
I make science history videos
with graduate students
from American University.
Here's the funny thing.
This time I'm partnering with....
EMME WATKINS: Hi, I'm Emme Watkins, and I'm a film student.
Tim and I have the same last name,
but we're not related as far as we know.
T WATKINS: Maybe 23rd cousins?
E WATKINS: At least! [laughs]
So, for this episode, we visited the Grand Canyon National Park.
In the 1970s, scientists figured out how to
measure visibility across a landscape.
T WATKINS: Air pollution was a big problem at that time,
so scientists had to understand the physics
of how light interacts with particles in the air.
And the Grand Canyon was a perfect place to do that
because of its epic views.
E WATKINS: We traveled to the park to see the canyon and learn
some history from one of the scientists who did this work.
We hope you enjoy the view!
♪♪♪
The Grand Canyon, one of the world's
greatest natural wonders.
Because it's my first time here, I needed some orientation.
So, I talked with Kylie Caesar.
She's a ranger in the park.
So, hi, Ranger Kiley.
CAESAR: Hi, Emme!
E WATKINS: Thank you for taking me out to the Grand Canyon.
CAESAR: Of course!
E WATKINS: I cannot believe we're here.
CAESAR: Of course. Welcome.
We are standing here on the South Rim of Grand Canyon.
We're looking all across this beautiful view,
about ten miles to get to the North Rim.
And then we're looking about one vertical mile of rock
all the way down to the bottom of the canyon
where the Colorado River is.
♪♪♪
My dad and my parents never really understood
why I wanted to be a geologist and why I was so concerned
with the natural environment.
And when I took my dad here for the first time,
when we walked up to this rim and we got to share
in that moment, we were both pretty silent for a bit.
And then he turned to me, and he said,
"Geology, huh? I get it."
E WATKINS: And I cannot imagine anyone being
disappointed with this view.
CAESAR: We've got a pretty clear, beautiful day
today where you can see all of the beautiful colors
of the rocks and interesting textures
of the temples and buttes.
But it's not always like that.
Sometimes we have smoke from forest fires
that cloud this view, or we get regional haze,
especially during the summertime.
I think when visitors come to places like
national parks, especially Grand Canyon,
they expect clean air and clear skies
and to be able to see this beautiful view.
♪♪♪
T WATKINS: Given expectations like that, Congress passed a law
in 1977 that required states and industries
to improve visibility by reducing air pollution.
Therefore, scientists had to learn how to measure visibility
based on the physics of light and particles.
That is, they had to put an objective number
on our subjective experience of a clear or hazy view.
♪♪♪
Dr. Bill Malm was one of the scientists who did that
right here in the Grand Canyon.
MALM: Well, we got, I got started personally got started
in 1972, and we used to sit on the edge of the canyon here,
and it'd get hazed up at times, and scratch our heads as to
where the stuff was coming from.
It could've been trans-, long-range transport
all the way from California.
It could, was it the power plants that were
right next to the Grand Canyon
on either end of the Grand Canyon?
Is it windblown dust?
We really didn't have an answer to those questions back in 1972.
♪♪♪
T WATKINS: Haze is the blocking and scattering of light
by pollution and other particles in the air.
As it travels to our eyes, light from the landscape
gets interrupted or deflected or mixed in
with light from other sources.
That means reduced visibility.
We cannot see as far, and we also cannot see as well.
We miss those crisp and beautiful details of color,
shading, and texture of the landscape.
♪♪♪
MALM: Think about driving a car in a snowstorm.
You see the snow as opposed to seeing the road.
Well, the same thing happens here.
You actually see the particles as opposed to seeing
the landscape feature that you're trying to look at.
T WATKINS: Tell me about the state of the science
at that time.
Did you know how to measure visibility in a way
that made sense in that legal framework?
MALM: Well, not at all.
And the amendment, actually, I think, put in
something on the order of $8 million over five years
to study those very problems.
T WATKINS: Studying those problems meant Bill
and his colleagues had to adapt or invent
a couple of key instruments.
An integrating nephelometer measures particle concentration
in a sample of air by recording how much
light is scattered by those particles.
Nephelometers at the time were not adequate for
studying visibility in nature, so Bill and his team
developed one that works with large and small particles
and under natural humidity levels.
They also developed a long-range transmissometer,
which allows you to measure the total loss of light due to
both scattering and blocking over vast distances.
Essentially, they beamed light from the bottom of the canyon,
measured it on the rim, and determined
how much light was lost because of haze.
MALM: And just looking at a light bulb with a telescope,
we were able to accurately measure the attenuation,
or the loss, of light as it moves through the atmosphere
to a high degree of accuracy.
And we built, I don't know, 10 or 15 of these things
and actually put them out in national parks
throughout the United States.
♪♪♪
T WATKINS: You collect all these data,
and others collect all these data.
Who uses that information and how?
MALM: So, as a result of all the work that we did and
others, we now have a rule, the Regional Haze Rule.
And the Regional Haze Rule requires states to review
the goal of increasing visibility,
reducing haze every ten years.
So, every ten years they review whether we're making progress
toward natural conditions.
But it's spectacular, and to be part of this whole thing,
and it's not just me by any means.
There are hundreds of people involved in this effort,
and my colleagues had a lot to do with making all this happen.
But it's pretty exciting.
To have a national visibility program
whose goal is to have clear days is pretty special.
E WATKINS: Today, the park has a modern
air quality monitoring system.
Webcams record images of the canyon every 15 minutes,
a nephelometer measures light-scattering
characteristics of air, and air samples are collected and sent
to a lab to figure out what chemicals make up the haze.
♪♪♪
MALM: And today there's well over 200 of these
monitoring sites adopted by EPA,
as well as the National Park Service,
and these sites are now across the whole globe.
They're in a number of countries:
Europe, Japan, Korea, Australia.
♪♪♪
E WATKINS: You can study light in airborne particles anywhere,
but doing so in a place like the Grand Canyon reminds us
about the broader value of science and of special places.
And that's something you cannot easily measure.
♪♪♪
RAPHAEL: I think it's incredible.
I've never really seen anything like this before.
And, you know, we're just kind of slowly
taking it all in right now, so. -Mmhmm.
AMY: I think he said we've seen so many pictures,
but nothing really can prepare you for the awe that you see
as soon as you walk up, the amazing colors of the canyon.
So, we're really excited to just see more.
IVAN: It's so wonderful, the view.
When you look the view, all the stress gone.
You feel amazing.
You feel like you are in the right place.
♪♪♪
T WATKINS: Well, Watkins, our time in the Grand Canyon
has come to an end. What did you think?
E WATKINS: I think it was just absolutely
breathtaking, Watkins.
-[laughs] I think my favorite view was
at Desert View Tower yesterday with Bill as
we looked down the whole canyon.
-Mmhmm. I think my favorite view was
probably right here at the Geology Museum.
-Yeah, this is a nice one.
So, let's give our audience one last view of the Grand Canyon
and let them enjoy it.
-Sounds good to me. Watkins out.
-All right, Watkins out.
♪♪♪