Category: Wildfires

What’s in wildfire smoke? A toxicologist explains the health risks and which masks can help

Wildfires filled Seattle with smoke in September 2020. Lindsey Wasson/Getty Images

by Luke Montrose (Boise State University)

Fire and health officials began issuing warnings about wildfire smoke several weeks earlier than normal this year. With almost the entire U.S. West in drought, signs already pointed to a long, dangerous fire season ahead.

Smoke is now turning the sky hazy across a large swath of the country as dozens of large fires burn, and a lot of people are wondering what’s in the air they’re breathing.

As an environmental toxicologist, I study the effects of wildfire smoke and how they differ from other sources of air pollution. We know that breathing wildfire smoke can be harmful. Less clear is what the worsening wildfire landscape will mean for public health in the future, but research is raising red flags.

In parts of the West, wildfire smoke now makes up nearly half the air pollution measured annually. A new study by the California Air Resources Board found another threat: high levels of lead and other metals turned up in smoke from the 2018 Camp Fire, which destroyed the town of Paradise. The findings suggest smoke from fires that reach communities could be even more dangerous than originally thought because of the building materials that burn.

Map of showing smoke across the entire country
NOAA’s smoke forecast based on where fires were burning on July 15, 2021. NOAA

Here’s a closer look at what makes up wildfire smoke and what you can do to protect yourself and your family.

What’s in wildfire smoke?

What exactly is in a wildfire’s smoke depends on a few key things: what’s burning – grass, brush or trees; the temperature – is it flaming or just smoldering; and the distance between the person breathing the smoke and the fire producing it.

The distance affects the ability of smoke to “age,” meaning to be acted upon by the Sun and other chemicals in the air as it travels. Aging can make it more toxic. Importantly, large particles like what most people think of as ash do not typically travel that far from the fire, but small particles, or aerosols, can travel across continents.

Smoke from wildfires contains thousands of individual compounds, including carbon monoxide, volatile organic compounds, carbon dioxide, hydrocarbons and nitrogen oxides. The most prevalent pollutant by mass is particulate matter less than 2.5 micrometers in diameter, roughly 50 times smaller than a grain of sand. Its prevalence is one reason health authorities issue air quality warnings using PM 2.5 as the metric.

The new study on smoke from the 2018 Camp Fire found dangerous levels of lead in smoke blowing downwind as the fire burned through Paradise, California. The metals, which have been linked to health harms including high blood pressure and developmental effects in children with long-term exposure, traveled more than 150 miles on the wind, with concentrations 50 times above average in some areas.

What does that smoke do to human bodies?

There is another reason PM2.5 is used to make health recommendations: It defines the cutoff for particles that can travel deep into the lungs and cause the most damage.

The human body is equipped with natural defense mechanisms against particles bigger than PM2.5. As I tell my students, if you have ever coughed up phlegm or blown your nose after being around a campfire and discovered black or brown mucus in the tissue, you have witnessed these mechanisms firsthand.

The really small particles bypass these defenses and disturb the air sacs where oxygen crosses over into the blood. Fortunately, we have specialized immune cells present called macrophages. It’s their job to seek out foreign material and remove or destroy it. However, studies have shown that repeated exposure to elevated levels of wood smoke can suppress macrophages, leading to increases in lung inflammation.

Dose, frequency and duration are important when it comes to smoke exposure. Short-term exposure can irritate the eyes and throat. Long-term exposure to wildfire smoke over days or weeks, or breathing in heavy smoke, can raise the risk of lung damage and may also contribute to cardiovascular problems. Considering that it is the macrophage’s job to remove foreign material – including smoke particles and pathogens – it is reasonable to make a connection between smoke exposure and risk of viral infection.

Recent evidence suggests that long-term exposure to PM2.5 may make the coronavirus more deadly. A nationwide study found that even a small increase in PM2.5 from one U.S. county to the next was associated with a large increase in the death rate from COVID-19.

What can you do to stay healthy?

Here’s the advice I would give just about anyone downwind from a wildfire.

Stay informed about air quality by identifying local resources for air quality alerts, information about active fires and recommendations for better health practices.

If possible, avoid being outside or doing strenuous activity, like running or cycling, when there is an air quality warning for your area.

Dark smoke over tree tops looks menacing
Wildfire smoke pours over palm trees lining a street in Azusa, California, on Aug. 13, 2020. AP Images/Marcio Jose Sanchez

Be aware that not all face masks protect against smoke particles. Most cloth masks will not capture small wood smoke particles. That requires an N95 mask that fits and is worn properly. Without a proper fit, N95s do not work as well.

Establish a clean space. Some communities in western states have offered “clean spaces” programs that help people take refuge in buildings with clean air and air conditioning. However, during the pandemic, being in an enclosed space with others can create other health risks. At home, a person can create clean and cool spaces using a window air conditioner and a portable air purifier.

The Environmental Protection Agency also advises people to avoid anything that contributes to indoor air pollutants. That includes vacuuming that can stir up pollutants, as well as burning candles, firing up gas stoves and smoking.

This is an update to a story originally published on Aug. 20, 2020.

Luke Montrose, Assistant Professor of Community and Environmental Health, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Western fires are burning higher in the mountains at unprecedented rates in a clear sign of climate change

Heat and dryness are leaving high mountain areas more vulnerable to forest fires.

by Mojtaba Sadegh (Boise State University); John Abatzoglou (University of California, Merced) and Mohammad Reza Alizadeh (McGill University)

The Western U.S. appears headed for another dangerous fire season, and a new study shows that even high mountain areas once considered too wet to burn are at increasing risk as the climate warms.

Nearly two-thirds of the U.S. West is in severe to exceptional drought right now, including large parts of the Rocky Mountains, Cascades and Sierra Nevada. The situation is so severe that the Colorado River basin is on the verge of its first official water shortage declaration, and forecasts suggest another hot, dry summer is on the way.

Warm and dry conditions like these are a recipe for wildfire disaster.

In a new study, published May 24, 2021 in Proceedings of the National Academy of Sciences, our team of fire and climate scientists and engineers found that forest fires are now reaching higher, normally wetter elevations. And they are burning there at rates unprecedented in recent fire history.

While some people focus on historical fire suppression and other forest management practices as reasons for the West’s worsening fire problem, these high-elevation forests have had little human intervention. The results provide a clear indication that climate change is enabling these normally wet forests to burn.

As wildfires creep higher up mountains, another tenth of the West’s forest area is now at risk, according to our study. That creates new hazards for mountain communities, with impacts on downstream water supplies and the plants and wildlife that call these forests home.

Map showing how high-elevation forest fires advanced uphill.
Forest fires advanced to higher elevations as the climate dried from 1984 to 2017. Every 200 meters equals 656 feet. Mojtaba Sadegh, CC BY-ND

Rising fire risk in the high mountains

In the new study, we analyzed records of all fires larger than 1,000 acres (405 hectares) in the mountainous regions of the contiguous Western U.S. between 1984 and 2017.

The amount of land that burned increased across all elevations during that period, but the largest increase occurred above 8,200 feet (2,500 meters). To put that elevation into perspective, Denver – the mile-high city – sits at 5,280 feet, and Aspen, Colorado, is at 8,000 feet. These high-elevation areas are largely remote mountains and forests with some small communities and ski areas.

The area burning above 8,200 feet more than tripled in 2001-2017 compared with 1984-2000.

Fire lights up a ridge behind a farm.
One of Colorado’s largest wildfires, 2020’s East Troublesome Fire, crossed the Continental Divide and was burning at elevations around 9,000 feet in October, when snow normally would have been falling. AP Photo/David Zalubowski

Our results show that climate warming has diminished the high-elevation flammability barrier – the point where forests historically were too wet to burn regularly because the snow normally lingered well into summer and started falling again early in the fall. Fires advanced about 826 feet (252 meters) uphill in the Western mountains over those three decades.

The Cameron Peak Fire in Colorado in 2020 was the state’s largest fire in its history, burning over 208,000 acres (84,200 hectares) and is a prime example of a high-elevation forest fire. The fire burned in forests extending to 12,000 feet (3,650 meters) and reached the upper tree line of the Rocky Mountains.

We found that rising temperatures in the past 34 years have helped to extend the fire territory in the West to an additional 31,470 square miles (81,500 square kilometers) of high-elevation forests. That means a staggering 11% of all Western U.S. forests – an area similar in size to South Carolina – are susceptible to fire now that weren’t three decades ago.

Can’t blame fire suppression here

In lower-elevation forests, several factors contribute to fire activity, including the presence of more people in wildland areas and a history of fire suppression.

In the early 1900s, Congress commissioned the U.S. Forest Service to manage forest fires, which resulted in a focus on suppressing fires – a policy that continued through the 1970s. This caused flammable underbrush that would normally be cleared out by occasional natural blazes to accumulate. The increase in biomass in many lower elevation forests across the West has been associated with increases in high-severity fires and megafires. At the same time, climate warming has dried out forests in the Western U.S., making them more prone to large fires.

Illustration of two mountains showing fires higher, less snow and more dead trees
On average, fires have spread 826 feet (252 meters) higher into the mountains in recent decades, exposing an additional 31,400 square miles (81,500 square kilometers) of forests to fire. Mojtaba Sadegh, CC BY-ND

By focusing on high-elevation fires, in areas with little history of fire suppression, we can more clearly see the influence of climate change.

Most high-elevation forests haven’t been subjected to much fire suppression, logging or other human activities, and because trees at these high elevations are in wetter forests, they historically have long return intervals between fires, typically a century or more. Yet they experienced the highest rate of increase in fire activity in the past 34 years. We found that the increase is strongly correlated with the observed warming (view graph).

High mountain fires create new problems

High-elevation fires have implications for natural and human systems.

High mountains are natural water towers that normally provide a sustained source of water to millions of people in dry summer months in the Western U.S. The scars that wildfires leave behind – known as burn scars – affect how much snow can accumulate at high elevations. This can influence the timing, quality and quantity of water that reaches reservoirs and rivers downstream.

High-elevation fires also remove standing trees that act as anchor points that normally stabilize the snowpack, raising the risk of avalanches.

The loss of tree canopy also exposes mountain streams to the Sun, increasing water temperatures in the cold headwater streams. Increasing stream temperatures can harm fish and the larger wildlife and predators that rely on them.

Climate change is increasing fire risk in many regions across the globe, and studies show that this trend will continue as the planet warms. The increase in fires in the high mountains is another warning to the U.S. West and elsewhere of the risks ahead as the climate changes.

Mojtaba Sadegh, Assistant Professor of Civil Engineering, Boise State University; John Abatzoglou, Associate Professor of Engineering, University of California, Merced, and Mohammad Reza Alizadeh, Ph.D. Student in Engineering, McGill University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Another dangerous fire season is looming in the Western U.S., and the drought-stricken region is headed for a water crisis

Dry conditions across the West follow a hot, dry year of record-setting wildfires in 2020. Communities were left with scenes like this, from California’s Creek Fire. Amir Aghakouchak/University of California Irvine

by Mojtaba Sadegh (Boise State University), Amir AghaKouchak (University of California, Irvine), and John Abatzoglou (University of California, Merced)

Just about every indicator of drought is flashing red across the western U.S. after a dry winter and warm early spring. The snowpack is at less than half of normal in much of the region. Reservoirs are being drawn down, river levels are dropping and soils are drying out.

It’s only May, and states are already considering water use restrictions to make the supply last longer. California’s governor declared a drought emergency in 41 of 58 counties. In Utah, irrigation water providers are increasing fines for overuse. Some Idaho ranchers are talking about selling off livestock because rivers and reservoirs they rely on are dangerously low and irrigation demand for farms is only just beginning.

Scientists are also closely watching the impact that the rapid warming and drying is having on trees, worried that water stress could lead to widespread tree deaths. Dead and drying vegetation means more fuel for what is already expected to be another dangerous fire season.

U.S. Interior Secretary Deb Haaland and Agriculture Secretary Tom Vilsack told reporters on May 13, 2021, that federal fire officials had warned them to prepare for an extremely active fire year. “We used to call it fire season, but wildland fires now extend throughout the entire year, burning hotter and growing more catastrophic in drier conditions due to climate change,” Vilsack said.

As climate scientists, we track these changes. Right now, about 84% of the western U.S. is under some level of drought, and there is no sign of relief.

Color-coded map showing drought
The U.S. Drought Monitor for mid-May shows nearly half of the West in severe or extreme drought. National Drought Mitigation Center/USDA/NOAA

The many faces of drought

Several types of drought are converging in the West this year, and all are at or near record levels.

When too little rain and snow falls, it’s known as meteorological drought. In April, precipitation across large parts of the West was less than 10% of normal, and the lack of rain continued into May.

Rivers, lakes, streams and groundwater can get into what’s known as hydrological drought when their water levels fall. Many states are now warning about low streamflow after a winter with less-than-normal snowfall and warm spring temperatures speeding up melting. The U.S. Bureau of Reclamation announced it would cut off water to a canal serving farms in the Klamath Project on the Oregon-California border because of low water supplies. It also warned that Lake Mead, a giant Colorado River reservoir that provides water for millions of people, is on pace to fall to levels in June that could trigger the first federal water shortage declaration, with water use restrictions across the region.

Dwindling soil moisture leads to another problem, known as agricultural drought. The average soil moisture levels in the western U.S. in April were at or near their lowest levels in over 120 years of observations.

Four US maps showing drought levels of precipitation, vapor pressure deficit, evapotranspiration and streamflow
Four signs of drought. Climate Toolbox

These factors can all drive ecosystems beyond their thresholds – into a condition called ecological drought – and the results can be dangerous and costly. Fish hatcheries in Northern California have started trucking their salmon to the Pacific Ocean, rather than releasing them into rivers, because the river water is expected to be at historic low levels and too warm for young salmon to tolerate.

Snow drought

One of the West’s biggest water problems this year is the low snowpack.

The western U.S. is critically dependent on winter snow slowly melting in the mountains and providing a steady supply of water during the dry summer months. But the amount of water in snowpack is on the decline here and across much of the world as global temperatures rise.

Several states are already seeing how that can play out. Federal scientists in Utah warned in early May that more water from the snowpack is sinking into the dry ground where it fell this year, rather than running off to supply streams and rivers. With the state’s snowpack at 52% of normal, streamflows are expected to be well below normal through the summer, with some places at less than 20%.

Map of western U.S. showing many areas with low snowpack
Snowpack is typically measured by the amount of water it holds, known as snow water equivalent. National Resource Conservation Service

Anthropogenic drought

It’s important to understand that drought today isn’t only about nature.

More people are moving into the U.S. West, increasing demand for water and irrigated farmland. And global warming – driven by human activities like the burning of fossil fuels – is now fueling more widespread and intense droughts in the region. These two factors act as additional straws pulling water from an already scarce resource.

As demand for water has increased, the West is pumping out more groundwater for irrigation and other needs. Centuries-old groundwater reserves in aquifers can provide resilience against droughts if they are used sustainably. But groundwater reserves recharge slowly, and the West is seeing a decline in those resources, mostly because water use for agriculture outpaces their recharge. Water levels in some wells have dropped at a rate of 6.5 feet (2 meters) per year.

The result is that these regions are less able to manage droughts when nature does bring hot, dry conditions.

Fish pour out of a pipe into a bay.
California fish hatcheries have started trucking their salmon to the Pacific Ocean because the rivers they are usually released into are too low and warm. AP Photo/Rich Podroncelli

Rising global temperatures also play several roles in drought. They influence whether precipitation falls as snow or rain, how quickly snow melts and, importantly, how quickly the land, trees and vegetation dry out.

Extreme heat and droughts can intensify one another. Solar radiation causes water to evaporate, drying the soil and air. With less moisture, the soil and air then heat up, which dries the soil even more. The result is extremely dry trees and grasses that can quickly burn when fires break out, and also thirstier soils that demand more irrigation.

Alarmingly, the trigger for the drying and warming cycle has been changing. In the 1930s, lack of precipitation used to trigger this cycle, but excess heat has initiated the process in recent decades. As global warming increases temperatures, soil moisture evaporates earlier and at larger rates, drying out soils and triggering the warming and drying cycle.

Fire warnings ahead

Hot, dry conditions in the West last year fueled a record-breaking wildfire season that included the largest fires on record in Colorado and California.

As drought persists, the chance of large, disastrous fires increases. The seasonal outlook of warmer and drier-than-normal conditions for summer and fire season outlooks by federal agencies suggest another tough, long fire year is ahead.

This article was updated with a statement from Secretaries Deb Haaland and Tom Vilsack.

Mojtaba Sadegh, Assistant Professor of Civil Engineering, Boise State University; Amir AghaKouchak, Associate Professor of Civil & Environmental Engineering, University of California, Irvine, and John Abatzoglou, Associate Professor of Engineering, University of California, Merced

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Northern forest fires could accelerate climate change

Read the full story from Boston University.

New research shows that the global models used to project how Earth’s climate will change in the future underestimate the impact of forest fires and drying climate on forests’ ability to capture and store atmospheric carbon.

As extreme fires transform Alaska’s boreal forest, deciduous trees put a brake on carbon loss and how fast the forest burns

A helicopter drops water on a forest fire in Alaska. Michael Risinger/U.S. Army National Guard, CC BY

by Jill Johnstone (University of Saskatchewan); Heather Dawn Alexander (Auburn University) Michelle C. Mack (Northern Arizona University) and Xanthe Walker (Northern Arizona University)

Fire is a hot topic these days, particularly when it comes to the boreal forest, the vast expanse of trees that stretches across Alaska, Canada and other cold northern regions. Large fires have been burning more frequently and severely in these remote landscapes, driven by longer seasons of hot, dry weather and more lightning strikes as the climate warms.

As forests burn, they release organic carbon that has accumulated in tree trunks, leaves and roots and in soils. This sets up a potentially dangerous climate feedback loop: More fires release more carbon from the land, which further exacerbates global warming, which means more hot, dry weather that can fuel more fire activity.

It’s enough to keep scientists like ourselves awake at night. However, new results from our research team published in the journal Science on April 15, 2021, suggest there may be a natural brake on the system.

We found that when black spruce forests that had recently burned in interior Alaska began regrowing, more aspen and birch trees were mixed in with the spruce. In fact, broadleaf deciduous trees like these were becoming the dominant species.

This has two important effects when it comes to climate change and wildfires: The deciduous trees store more carbon, and they don’t burn as quickly or a severely as dry, resinous black spruces and their needles do.

The result is that these changing forests could mitigate the fire-climate feedback loop, and maybe even reverse it – at least for now.

A river runs through a forest of yellow broadleaf trees with spruce mixed in.
Deciduous forests have been taking over historic black spruce forests in Alaska after severe fires. Paxson Woelber/Flickr, CC BY

Deciduous trees take over

When severe fires in black spruce forests burn deep into the soil organic layer, more carbon is lost during the blaze. But something else happens as well: Instead of spruce trees regrowing after these severe fires, they are often replaced by deciduous broadleaf trees that make up for that carbon loss when they regrow.

Severely burned black spruce stands, or groups of trees, lose the most carbon during a fire, but once these forests transition to aspen and birch, they store carbon at a rate that is four times faster than in similarly aged black spruce stands. By 50 years, they have compensated for fire-driven carbon losses.

By the time deciduous forests are 100 years old, the typical interval between burns in this region, carbon pools are 1.6 times larger than in black spruce forests, according to our calculations. The net effect is an increase in stored carbon that more than compensates for the increased carbon lost during the previous fire (see the data in a graph).

Illustration of forests and carbon storage above and below ground
Deciduous forests store more carbon above ground, while spruce forests store more in the soil. Victor O. Leshyk, Center for Ecosystem Science and Society, Northern Arizona University

Most of the carbon stored in deciduous stands is in the trees’ biomass above ground – woody trunks and branches – not in soils like in spruce stands. This is because trees like birch and aspen grow much more rapidly than spruce and are more effective at cycling nutrients and sequestering carbon in wood.

15 years of changing forests

Our research began over 15 years ago, when an intense fire season in 2004 burned a record 6.7 million acres across Alaska.

We suspected then that the worsening fires carried the fingerprint of contemporary climate change, and we wondered what it might mean for patterns of forest recovery.

Map showing boreal forest regions
Boreal forests stretch across Alaska and Canada, Europe and Russia. Wikimedia/Mark Baldwin-Smith, CC BY

After the fires, we established a broad network of research sites in burned black spruce forests across the region. In each, we measured the amount of carbon in the ecosystems as they recovered.

We discovered that recent fires had burned deeper into the soil, disrupting the relatively shallow burn patterns that had allowed black spruce to dominate the landscape. The severe burning resulted from the warmer climate and consequently drier, more flammable fuels. Once deciduous seedlings become established after a fire, they quickly dominate the forest canopy.

It is still too early to know how widespread these changes may be, but recent estimates from remote sensing suggest that deciduous forests could replace conifer forests at a rate as high as 5% per decade, mostly due to fire (see the data in a graph).

Putting all those pieces together, we now understand that such rapid shifts in forest composition and their effects on carbon storage patterns could shape the long-term feedback loops between boreal forests and the Earth’s atmosphere.

Less flammable trees, but that may not last

There’s more to the story about the potential for deciduous trees to mitigate fire and climate feedbacks in the boreal forest.

Importantly, wildfire studies indicate deciduous broadleaf forests often burn less easily when a fire ignites, and fires in deciduous forests are more easily put out by rainfall or human efforts. Although not immune to fire, aspen stands burn more slowly and less severely than black spruce stands, which have dry, resinous and highly flammable fuels.

The result is that more deciduous stands across boreal forests are likely to translate into smaller, less severe fires.

View of a burning forest from a helicopter with a soldier sitting in the open helicopter door
Alaska fires are much harder to control in the rugged, remote landscape, and often left to burn. Sherman Hogue/U.S. Army, CC BY

However, we do not know how long deciduous forests’ lower flammability will persist as the climate warms. There likely is a threshold at which even resistant trees will readily burn. Other ecological changes as the forests transform could also influence their long-term carbon storage.

The ability of deciduous forests to slow climate warming will depend on both the local landscape and the choices people make about their carbon emissions. For the time being, it is welcome news that natural shifts in forest ecosystems have the potential to be important players in bolstering the resilience of the Earth system to climate warming.

This article was updated to change the illustration credit.

Jill Johnstone, Adjunct Professor of Biology, University of Saskatchewan; Heather Dawn Alexander, Assistant Professor of Forest Ecology, Auburn University; Michelle C. Mack, Professor of Ecosystem Ecology, Northern Arizona University, and Xanthe Walker, Assistant Research Professor, Northern Arizona University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Wildfire smoke to blame for up to half of soot pollution in parts of western US: research

Read the full story at The Hill.

Wildfire smoke has resulted in as much as half of the soot pollution in parts of the western U.S., according to a study that was published on Tuesday. 

Researchers determined that more than half of the concentrations of the pollutant in some areas came from wildfires in recent years and that their smoke made up 25 percent of soot pollution across the entire U.S.

Using satellite-based fire and smoke data, the researchers also determined that pollution from fires had increased substantially over the course of a decade. 

The amount of area burned by wildfires has been rising, and other studies have linked the increase, at least in part, to climate change. 

California’s Ancient Redwoods Face New Challenge From Wildfires And Warming Climate

Read the full story from NPR.

Big Basin — and big swaths of California — are still recovering from historic wildfires that ravaged the state this year, displacing tens of thousands of people and wildlife, burning more than 4 million acres and killing at least 33 people. They also ripped across groves of giant, coastal, old-growth redwoods here in the Santa Cruz Mountains. And while these trees are incredibly resilient, there’s concern that even they may find it harder to rebound amid the mounting impacts of climate change.

Want to Fight the Zombie Fire Apocalypse? Weaponize Math

Read the full story in Wired.

Peat fires smolder in the ground for months, suddenly emerging as surface wildfires. New simulations reveal their strange life, death, and reanimation.

How Much Longer Will Insurers Cover Wildfire Loss Near You?

Read the full SEJ TipSheet.

As thousands of structures burn in this year’s West Coast fires, insurers are increasingly reluctant to cover homes in the wildland-urban interface.

California Bars Insurers From Dropping Policies in Wildfire Areas

Read the full story in the New York Times.

The new one-year freeze is a sign of the growing financial burden caused by climate change.

%d bloggers like this: