This moss right here is growing in the Duwamish Valley, the most polluted area in Seattle.
It might seem ordinary, but deep within its leaves, it's keeping a record of the pollution in the air,
from the trucks, trains, planes, cargo ships, and hundreds of industrial facilities that surround it.
It's a detailed record only surpassed by super expensive scientific equipment.
This is a story about an overlooked plant
with a secret superpower,
and the people using it to take control of the air they breathe.
So moss is a type of plant, but it's not like most plants.
Mosses evolved hundreds of millions of years ago long before the advent of trees or flowers.
And for the most part, they're still pretty low-tech plants.
They don't have roots or any major system to circulate water or nutrients.
Instead they get everything they need by absorbing it from the air, directly into their spongy cells.
When moss is absorbing nutrients, it's also absorbing everything else that's in the air.
So by sampling moss on a tree, and testing it in the lab,
you get a fingerprint of what's in the air in that specific place.
The moss is out there. The moss is watching.
And if you're interested in what the air quality has been like,
you can go out there and collect the moss, and you can get an idea of what that looks like.
This is Sarah Jovan. She's a Forest Service research ecologist who studies mosses and lichens —
which also have similar pollution detecting superpowers.
Her research started in the wilderness, using mosses and lichens
to learn about air pollution in our national parks and forests.
After several years, she had an idea that no one in the U.S. had ever tried on a large scale before:
to use moss to study air pollution in cities.
At the time, her home city of Portland was facing a common problem:
they only had one main air monitor for the whole city.
That stationary monitor was really great —
it could tell you exact levels of pollution in the air —
but it was really expensive!
That meant Portland couldn't afford enough monitors to track air pollution on a neighborhood level.
But Portland does have a lot of moss!
There's moss all over the place in this city! Like, we could collect almost anywhere we want to.
From a statistician's point of view, we could have a really badass design.
Sampling moss would be cheap too: a study with hundreds of samples across Portland
would cost about as much as a study with only one stationary air monitor.
While the moss can't tell you exactly how much pollution is in the air,
Sarah thought it could be the perfect screening tool.
It could help identify which neighborhoods have the worst air pollution,
and then an official air monitor could follow up to measure just how bad that air actually is.
I think we should check that tree and maybe one of these guys.
In 2013, Sarah and her team sampled moss from 346 trees around Portland,
and tested them for metal pollutants like lead, arsenic, and chromium.
And when they put all of those results on a map they, found a pollution hotspot!
Their moss samples revealed a residential neighborhood in Portland
that had much higher levels of cadmium and arsenic than the rest of the city.
And an official follow-up confirmed the source:
a local stained glass factory that used these metals to make glass colorful and clear.
Initially, for like a split second, we were like thrilled! We were like wow!
But then very quickly it turned into like...
New concerns about high levels of toxins.
Okay this is gonna upset livelihoods.
Cadmium and arsenic coming from the bullseye glass factory.
What does this mean for the people that are living there?
The whole system is inept and corrupt.
You see these maps, and they'd have this big red dot,
and people are like, "Am i going to die? What's happening?"
Filtrate or vacate!
The head of the state environmental agency resigned in March.
You're glad you revealed it, because now we have a chance to address and change it.
And a major overhaul for all companies which emit air toxics is also underway.
But we were pretty darn stressed out about it.
Their study had created a scandal. But the findings caught people's attention.
It led to new environmental laws, and more air monitors in the city.
And it also caught the attention of another community, 150 miles to the north.
The Duwamish Valley has been home to Seattle's heavy industry for more than a hundred years.
And in the middle of that industrial valley are two residential neighborhoods:
Georgetown and South Park.
The Duwamish Valley, it's an environmental injustice community.
This is Paulina López. She runs the Duwamish River Cleanup Coalition.
I moved to this neighborhood because I wanted to be for sure surrounded by people that look like me.
I'm from South America, and I have always prioritized
spaces that look like this neighborhood: families, river, and the diversity that exists within it.
Residents know pollution in the valley is a problem.
They face a lot of environmental health concerns, like asthma or heart disease.
We know who are the polluters, but we haven't been able to prove it.
To clean up the valley, they'd need a much more detailed picture of all the different sources of pollution.
And the cleanup coalition saw moss as a way to do that.
The Portland moss study had proved that scientists could use a simple plant to reveal big truths.
In Seattle, they wanted to take it a step further:
to see if the community could do the study themselves.
I see the moss study as like, "oh actually, we took matters into our own hands."
This is what we learned. Take it or leave it.
Sarah Jovan, along with partners from other agencies, universities, and non-profits,
helped train a group of local youth scientists,
who then went around south Seattle,
finding trees, and collecting the moss.
Their team wanted this project to be a model for other communities to use.
So they sent out trained scientists to also collect moss samples,
and double check the accuracy of the youth's work.
And it turned out, the youth did just as well as the scientists.
Who's to say — don't tell me when I told you this — but who's to say that you need a PhD
to see the trends, or to notice what what comes up in a study. Our youth did that.
When they got the pollution results back from the lab, and put their findings on a map,
they found what looked like a hot spot.
A cluster of samples with high levels of pollutants like arsenic and chromium.
It was very surprising what we were finding. Surprising, but also not surprising.
Everyone in the valley knew it was polluted. The moss provided block by block proof.
Because of the moss study, the regional air agency is starting an official follow-up on metals in the valley,
guided by the community.
That follow-up will show exactly how much of a risk these metals pose,
and could be the kind of hard evidence that could lead to real reforms.
I think that's really the golden ticket: connecting it all back to public health.
Now it's not just the northwest. Other cities could look to moss and lichen for answers too.
There are a lot of people out there, across the country, that have contacted me and want to do their own studies.
And they all have great reasons why they'd want to do it.
There are some limitations: for example too much pollution can kill moss and lichen,
which makes this study tricky in some cities.
Still, Sarah Jovan thinks a lot of cities could find some way to make it work.
And that could translate to more people breathing cleaner air.