Smoke from wildfires raging across Canada have shrouded much of the Northeastern United States in a thick orange haze. Plumes of wildland fire smoke don't just hoist hot embers into the air—they also carry life.
Pyroaerobiology, a new field of science with a badass name, seeks to understand how colonies of bacteria, fungi, archaea, and viruses are swept up in smoke. These organisms float off into distant lands thousands of miles away, altering the microbial composition of the ecosystem. Microbes floating in this smoke can also impact the weather, seeding the ice crystals that form clouds. There's also been evidence to suggest these microbiotic zoos could potentially contain allergens that could be harmful to humans.
Leda Kobziar of the University of Idaho knows a whole lot about pyroaerobiology because she invented it. Kobziar and her team use drones to capture the microbial samples swirling in clouds of smoke emitted from prescribed burns, so they can better understand what gets picked up in the plume.
Our climate is changing, and so is our relationship with wildland fire. These conflagrations are becoming more frequent, lasting longer, and are growing increasingly more devastating. Scientists like Kobziar are racing to understand how our environment—and humans—adapt to the influx of these foreign organisms.
Popular Mechanics spoke with Kobziar at the American Geophysical Union Fall Meeting in San Francisco to learn more about the burgeoning field of science and unravel the impacts these wafted microbes have on the world.
Note: This interview has been edited for concision and clarity.
Popular Mechanics: How did you stumble upon this line of work?
Leda Kobziar: I became curious about smoke after I learned that bacteria were being added to snow-making machines—believe it or not—because they act as powerful ice nucleators, which means they can be the nuclei for ice crystals, [spawning snowflakes] at higher temperatures than you would otherwise find.
Ski mountains all around the world use these bacteria and add them to their snow-making machines. I started to think about smoke in the same way. I just wondered if there were any living bacteria in the smoke and if it was perhaps responsible for some of the really interesting clouds that wildland fires create.
PM: What types of microbes do we see in wildfire smoke?
LK: We are seeing hundreds of different types of microbes, so it's kind of hard to characterize all of them. We're seeing fungi and we're seeing bacteria and we're seeing archaea. We haven't looked at viruses yet, but I'm imagining that there are probably some in there, too.
Some of these are organisms that you would typically find in ambient air, but they're highly concentrated, so we see a lot more of them than we would find in ambient air conditions. Others are organisms that are not typically found in ambient air. So there are things that grow deep in the soil or grow in the insides of plants and not things that would generally be aerosolized just by wind.
PM: How do these microbes get swept up in wildland fire smoke? How does the population of microbes differ in smoke emitted from a forest fire, a grassland fire, or one that has ignited in a home?
LK: That's something we're really interested in characterizing. What we would expect to see is that the organisms that we see in smoke are going to be related to the organisms that we see in the source material. There are different types of microbes that live in different environments.
Because fires burn in different ways given different ecosystems like, as you mentioned, grassland versus a forest. Depending on what's burning and depending on what is originally in that forest that's burning, that's going to have an impact on what we see in the smoke.
At this point in time, we have pretty much a whole world to examine to understand that relationship. There's a deep, deep area of potential for discovering the relationship between the forest and what we see in the smoke that has yet to be investigated.
PM: What happens when microbes disperse to faraway lands?
LK: Once deposited, viable microbes can have a wide array of impacts on the surfaces where they land. For example, they can interact with existing microbial communities and therefore transfer genetic information, compete with or form symbiotic relationships with various types of organisms, or otherwise change community composition and dynamics. Microbes affect every aspect of an ecosystem’s functioning.
Since smoke has likely been transporting microbes for millions of years, understanding this mechanism of transport can help us understand microbial biogeography and evolutionary diversity.
JL: Could you talk about some of the potential risks associated with these traveling microbes?
LK: We have seen organisms that are common allergens for human respiratory system. So, it may be that in just more concentrated form that we're seeing in the smoke that it could cause some allergic disturbance to the respiratory system. Organisms that cause disease in plants (like crop pathogens), animals, or humans may also be transported and enter into sensitive populations through deposition or inhalation. This is one area of our findings that is ripe for additional investigation.
PM: Are there any benefits?
LK: There's just as much possibility that the movement of these organisms through the smoke has a beneficial impact. Some microbes called "endophytes" can increase plant growth and yield and some even act as antibiotics against plant pathogens, thereby assisting their host species.
We've seen a lot of bacteria that act as nitrogen fixers. Of course, nitrogen is the building block of all protein and everything that exists on earth. We wouldn't have anything if it weren't for these bacteria, and we've seen these bacteria being transported.
Spreading these bacteria could have a positive impact on the ecosystems in which they land, but those downstream impacts are things that we haven't yet addressed specifically. So we have good reason to believe the impacts are broad and far reaching, and that's going to be work that we do in the future.
PM: What's a typical day in the field like?
LK: It starts with conducting ambient sampling. We clear out the landing space, the [drone] pilots run their safety checks, and then we fly up into the air and hover above the vegetation that we're going to be igniting a couple of hours later. We always want to conduct an ambient sampling prior to any ignition, so that we know we're sampling clean air.
We take our DGI Matrice 600 pro UAS system and load up our sampling devices onto that system in a lightweight aluminum framework that we've built. That includes our compensating vacuum pump that can compensate for changes in air pressure.
Then we attach impactors, small sampling devices about three centimeters across, which have a mesh filter on them so that they can block out large particles. We pump air through the impactor and everything that gets pulled into it impacts onto a filter. We sample for anywhere between five to 10 minutes.
When we come back down, we quickly close the orifice of the impactors to make sure they remain sterile. We remove the device to record the data and take it into our homemade sterile chamber—a glove-box-like mobile lab that we created. We use sterile methods to remove the filters, put them into cryovials, and then put them on ice so we can conduct DNA analysis later when we trek out of the field.
PM: Do you need special training to do this work?
LK: The field work involves being trained—entry-level wildland fire training, which is called type 2 training. We all have experience with fire, so that gives us the opportunity to get up close and personal with these sampling sites, where most other scientists wouldn't be able to gain access to these sampling opportunities.
PM: What is the most surprising aspect of your research?
LK: I think the most surprising aspect of the research is how diverse the communities are that we're seeing aerosolized in the smoke. We thought that there might just be a handful of extremophiles—organisms that survive really harsh conditions. But it runs from organisms that are very sensitive to heat to organisms that aren't sensitive to heat at all. The number of species that we're seeing is really striking and the fact that most of them are living, I think, has been really surprising for us.
PM: What sorts of impacts might these microbes have on weather and climate?
LK: The fact that we found a significantly higher number of ice nucleators in the smoke than in ambient conditions does suggest that smoke can have an effect on atmospheric processes, that it is uniquely highly efficient at ice nucleation as well.
This is something that hasn't been taken into consideration in any of our [computer] models that address the global impact that smoke has on the atmosphere. We know that smoke can act as a direct radiative forcing agent, which means it has impact on the amount of heat energy that's either absorbed, redirected, or trapped by aerosols in the atmosphere. It could also affect the creation of clouds, which obviously has a really big impact on global patterns of weather.
It's not necessarily that the influence of smoke is increasing or decreasing in the world. It's just that we have never taken it into consideration before. We recognize there are biological organisms in the air all the time—they're a pretty significant thing we should include in future models if we really want to understand the impact of smoke on the atmosphere.
PM: What's the most pressing question in your field?
LK: That's probably the hardest question because there are so many exciting different directions for this research to go in. Right now, I'm most interested in two fundamental questions I think we need to answer: How long do these microbes stay alive? And how far do they travel?
We first have to understand that mechanism. Every question after that is related to the impacts that they have.
From there, I'd really like to understand what potential health impacts these microbes could have—especially on firefighters who are working in direct proximity to wildfire smoke. Even if these things don't get transported very far, they could be having an impact on the personnel who risk their lives already to work with wildland fire. That's really important to me, too.
