When wildfires roar through a forest and bulldozers dig into the earth to stop advancing flames, they can spin into the sky more than just clouds of dust and smoke, scientists say.
Those dark, billowing plumes of smoke that rise during the day from heat waves and sink into valleys as the night air cools can carry countless living microbes that can seep into our lungs or attach themselves to our skin and clothing, according to recently published research. in science. In some cases, researchers fear that airborne pathogens could make firefighters or wind dwellers sick.
“We were inspired to write this because we recognize that there are many trillions of microbes in smoke that are not really included in any understanding … of human health,” said Leda Kobziar, the University of Idaho’s scientific director on the subject. field of wildfires. “At the moment it is really unknown. The diversity of microbes we have found is really mind-boggling. “
As these recent firing seasons suggest, the need to understand what’s in wildfire smoke that we can’t help but breathe and how it can affect us has never been more pronounced, but scientists say we’re seriously behind.
Wildfires burned in more than 10.2 million acres of the United States in 2020, federal statistics show, including about 4.2 million acres in California, where a greater number of residents were exposed to smoke for longer periods than ever.
According to researchers, smoke from wildfire is now responsible for up to half of all particulate matter pollution in the western US. While there are many studies on the long-term effects of urban air pollution on human health and the short-term effects of wildfire smoke, little is known about the multitude of ways the latter can hurt us for a lifetime.
“In all fairness, we don’t really know what the long-term effects of wildfire smoke are because exposure to the community has never been long-term before,” said Dr. John Balmes, a professor of medicine at UC San Francisco and a California member. Air Resources Board.
But people – and Californians in particular – should be breathing more wildfire smoke in the future.
Scientists say the planet will continue to warm for decades to come, even if people suddenly act together to stop climate change. This warming and other factors are contributing to more and more devastating forest fires. The state’s forests, meanwhile, are struggling to adapt, and native plants are being supplanted by faster-burning invasive species.
Add to those trends a global pandemic affecting the respiratory system, and microbe-filled fire smoke every year could be viewed as a growing health risk, researchers say. They wonder whether microbes in the smoke from wildfires can make cancer patients more vulnerable to infections or whether children with asthma are more prone to developing pneumonia.
Scientists believe that some microbes survive and even multiply in wildfires, where heat scorches the soil and leaves a layer of carbon that protects microbes in the earth from intense heat. Others survive in the air because wildfire particles can absorb the sun’s otherwise deadly ultraviolet rays, the scientists said. And still other spores are likely to be spread by wind currents caused by fire.
Kobziar and co-author George Thompson III, an associate professor of medicine at UC Davis, said that until now, the link between microbes and wildfires has been anecdotal – such as bush firefighters’ tendency to get sick from Valley fever after work. in the event of an incident. The disease is contracted by inhaling spores of the fungus species Coccidioides.
“We have more questions than answers right now,” said Thompson. “Our lungs are exposed to pathogens every day that we don’t think about much. But [what] if we increase the number of microbes in it with fire? “
For example, in 2018, the Kern County Fire Department sought a $ 100,000 grant to get help reducing fuel breaks – which are disrupting the soil – because their firefighters would get sick after doing the job. Data shows that valley fever cases cause a spike on the province’s valley floor every fall, just as the fire season is underway in the surrounding hills.
“Aerosols, microbes, spores or fungal conidia … have the potential to travel hundreds of miles, depending on fire behavior and atmospheric conditions, and are eventually precipitated or inhaled by a fire,” Kobziar and Thompson wrote in their paper.
Still, it was difficult to determine which pathogens are found in the smoke of wildfires.
The National Oceanic and Atmospheric Administration, NASA and a team of chemists, physicists, biologists, and forest and fire ecologists from a number of universities have worked together for years to study wildfire smoke across the country, believing that no one will be immune for its effects in the future.
“As the climate changes, the temperature rises, as we build houses in places surrounded by human populations and housing expands into areas prone to fire, it’s a matter of time,” said Berry Lefero, manager of NASA’s Tropospheric. Composition. Program, including a DC-8 jet that circles the world and studies wildfire smoke, ozone and aerosols in the lower atmosphere.
Through the combined work of these researchers, scientists hope that one day the public and health professionals will be able to receive timely, accurate predictions about where wildfire smoke will go, what specific health risks it poses, and what humans do. on their path to be prepared to stay in. beyond standard advice.
To solve the mystery of what microbes are in the smoke and why, Kobziar and Thompson need to understand what kind of fuel is burning, such as grass, bush or tree; how much of it there was initially; how badly it had been burned (was it just scorched black or completely reduced to ashes or something in between?); and where the smoke came from.
Once those variables are determined, there’s the complicated task of actually capturing the smoke, which is certainly not uniform, Kobziar said.
In September, Kobziar, a former firefighter, used a drone to capture samples of the air over Idaho when it was inundated with smoke from fires in Eastern Washington and Oregon. She then placed the samples in a Petri dish, added some food that microbes like to eat, and waited to see what would happen.
“Even a few hundred miles from the source of the smoke, it was still significant,” said Kobziar. “We’re still trying to isolate all the things we’ve found.”
Tim Edwards, president of the Local 2881 fire union, which represents thousands in the California Department of Forestry and Fire Protection, hopes the scientists’ work can spur his own efforts to get gas masks for forest firefighters, as they usually rely only on face masks or bandanas – unlike their urban firefighting counterparts.
It’s not just the dust generated in a fire that makes the crew sick, Edwards said.
“Now, in a fierce fire, you have 1,000 houses on fire,” he said. “You burn the house, you don’t know what chemicals they have in that house, everything is on fire and it goes into your lungs.”
This story originally appeared in Los Angeles Times.
Originally published