After the inferno: Understanding the domino effect of wildfires
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Ignite your curiosity with the following pieces highlighting thirteen key areas impacted by the cascading risks of wildfires. Our Preventionweb editors have carefully curated the following articles and publications to spark discussions on systemic risk. These selections include pieces from researchers who are blazing the trail, news from affected regions, and firsthand accounts from those working on the front lines. Discover how the aftermath of wildfires extends far beyond the visible devastation and affects the following topic areas, prompting us to rethink our approaches to prevention and resilience.
1. Water quality
When wildfires swept through the hills near Santa Cruz, California, in 2020, they released toxic chemicals into the water supplies of at least two communities. One sample found benzene, a carcinogen, at 40 times the state’s drinking water standard.
In a new study, we heated plastic water pipes commonly used in buildings and water systems to test how they would respond to nearby fires.
The results, released Dec. 14, show how easily wildfires could trigger widespread drinking water contamination. They also show the risks when only part of a building catches fire, and the rest remains in use. In some of our tests, heat exposure caused more than 100 chemicals to leach from the damaged plastics.”
2. Indoor air quality
When wildfire smoke turns the air brown and hazy, you might think about heading indoors with the windows closed, running an air purifier or even wearing a mask. These are all good strategies to reduce exposure to the particles in wildfire smoke, but smoky air is also filled with potentially harmful gases. Those gases can get into buildings and remain in the walls and floors for weeks.
Getting rid of these gases isn’t as simple as turning on an air purifier or opening a window on a clear day.
In a new study published in the journal Science Advances, colleagues and I tracked the life of these gases in a home exposed to wildfire smoke. We also found that the best way to get rid of the risk is among the simplest: start cleaning.
3. Outdoor air quality
Smoke from more than 200 wildfires burning across Canada has been turning skies hazy in North American cities far from the flames. We asked Chris Migliaccio, a toxicologist at the University of Montana who studies the impact of wildfire smoke on human health, about the health risks people can face when smoke blows in from distant wildfires.
If you have ever been around a campfire and got a blast of smoke in your face, you probably had some irritation. With exposure to wildfire smoke, you might get some irritation in the nose and throat and maybe some inflammation. If you’re healthy, your body for the most part will be able to handle it.
As with a lot of things, the dose makes the poison – almost anything can be harmful at a certain dose.
Researchers have found that there seems to be a higher level of oxidation, so oxidants and free radicals are being generated the longer smoke is in the air. The specific health effects aren’t yet clear, but there’s some indication that more exposure leads to greater health effects.
The supposition is that more free radicals are generated the longer smoke is exposed to UV light, so there’s a greater potential for health harm. A lot of that, again, comes down to dose.
4. The ozone layer
Aerosol particles can both spread and absorb sunlight, which can have cooling or warming effects on the climate. They also affect cloud formation since water does not condense by itself, it needs particles in order to form cloud droplets. That, in turn, affects the Earth’s radiation balance.
In lower layers of air in the troposphere, clouds form around particles, which means that they soon fall as precipitation. That does not happen in the stratosphere, where no precipitation forms. Instead, the particles follow air currents and can be spread globally within that layer.
After the Australian fires in 2019 and 2020, the concentration of ozone in the Southern Hemisphere fell and ozone holes formed outside the polar region. If the fires were to occur in the Northern Hemisphere, the damaging effects of reduced protection from dangerous UV radiation would have consequences for billions of people, as well as animal and plant life, including vital agricultural production.
5. ENSO
The 2019-2020 bushfire season was devastating. Vast areas of pristine forest burned, many for the first time in memory. By some estimates, a billion native animals died up and down Australia’s east coast. Dozens of people died.
While Sydney’s skies are blue again, Australia’s Black Summer has kept scientists around the globe busy. The sheer size of these megafires produced startling effects. Recently, researchers found the huge volumes of smoke ate away at our protective ozone layer.
Now, new research by American scientists suggests the Black Summer fires were massive enough to influence the El Niño Southern Oscillation cycle. It’s one of the most important drivers of unusual weather over the entire globe – and one which Australians know intimately.
The three successive years of La Niña we just had? They could have been made more likely by the Black Summer fires. The reason, strangely enough, is the smoke.
6. Physical health
A team of researchers led by Professor Jay Horvat and Dr Henry Gomez have developed a world-first platform to define the impact of exposure to landscape fire smoke on the heart and lungs.
The researchers found that short and long-term exposure to landscape fire smoke particulate matter (bushfire smoke) increased the hyperresponsiveness of airways and induced steroid insensitivity in experimental asthma.
They also found that short-term exposure to bushfire smoke decreased cardiac function and this is associated the expression of gene changes relating to oxidative stress and cardiovascular pathologies.
“Professor Horvat explains, “Millions of people in Australia were exposed to unprecedented levels of particulate matter from landscape fires. This was associated with large increases in people having respiratory and cardiovascular symptoms. People with asthma experienced worsened disease symptoms and had an increased needed to seek medical help as a result of exposure to particulate matter generated by the fires. Furthermore, the number heart attacks almost doubled in regional locations during the 2019/2020 black summer period”.
7. Chemicals
People returning to what remains of the beachside town of Lahaina, Hawaii, and other Maui communities after one of the nation’s deadliest wildfire disasters face more dangers, beyond the 2,200 buildings destroyed or damaged and dozens of lives lost. The fires also left lingering health risks for humans and wildlife.
When fires spread through communities, as we’ve seen more often in recent years, they burn structures that contain treated wood, plastics, paints and hazardous household wastes. They can burn vehicles and melt plastic water pipes. All of these items release toxic gases and particles.
Many airborne pollutants fall to the ground, and when debris or dust is stirred up, hazardous particles can enter the air, where people can easily breathe them in.
“Chemicals like benzene, lead, asbestos and polycyclic aromatic hydrocarbons, or PAHs, are common in ash, runoff and sometimes water systems after fires.
Exposure to high levels of chemicals can sometimes cause immediate harm, such as nausea, vomiting, dizziness, rashes and respiratory issues. For these reasons it is critical to protect people, especially children and people with health conditions, from exposure.”
8. Children
Bushfire smoke is harmful to our health. Tiny particles of ash can lodge deep in the lungs.
Exposure to this type of smoke may worsen existing conditions such as asthma, and induce a range of health effects from irritation of the eyes, nose and throat to changes in the cardiovascular system.
Public health recommendations during smoke events tend to provide general advice, and don’t often include advice specifically geared at children. But children are not just little adults. They are uniquely vulnerable to environmental hazards such as bushfire smoke for a number of reasons.
Meanwhile, children’s behaviour and habits may expose them to more environmental toxins than adults. For example, they tend to do more physical activity and spend more time outdoors. Higher levels of physical activity lead to more air inhaled per kilogram of body weight.”
9. Pregnant women
Smoke covered large swathes of Australia during the catastrophic summer fires of 2019-2020. You could see the plumes from space. Over 20% of Australia’s forests went up in smoke and flame.
As the fires spread, smoke covered towns and cities. Millions of people were suddenly confronted with bad air. Many had children. Many were pregnant. All worried about what the smoke might mean for their child.
Our new book explores the worries and desperation of people who were pregnant or parenting during the unprecedented fires over the 2019–2020 summer. We drew on in-depth stories from 25 mothers (and sometimes their partners).
10. Migrant workers
Wildfires continue to burn across Canada, destroying hundreds of structures and displacing thousands of people. However, while many have been able to evacuate and receive help, migrant workers have been coping with the effects of the fires with relatively little support. Temporary migrant workers in the Global North are already highly vulnerable to abuse in the workplace and hazardous working conditions. That vulnerability is often drastically increased in times of crisis.
Studies have revealed how crises like COVID-19 impact migrant workers around the world, including in Canada and the United States. Our research team has found that migrants have also been significantly affected by the recent wildfires in British Columbia’s Okanagan.
11. Mental health
Scientists and clinicians have long suspected a link between wildfires and a decline in mental health. A new study of prescription records supports the association, showing that large wildfires appear to exacerbate preexisting mental health conditions.
The research, published Feb. 26 in JAMA Open Network, involved analysis of psychotropic prescription data to analyze mental health trends near 25 large California wildfires over an eight-year span. Researchers found a statistically significant increase in prescriptions for certain psychoactive drugs in the six weeks after fires, each of which burned at least 25,000 acres in the nation’s most populous state.
“This research adds a significant amount of evidence that there is a really substantial mental health impact related to wildfire in our communities,” said lead author Zack Wettstein, a UW Medicine emergency medicine doctor.
12. Livestock
New research in the Journal of Dairy Science® examines effects of wildfire smoke on dairy cattle, including reduced milk production. Increasing frequency and size of wildfires in the United States over the past several decades affect everything from human life and health to air quality, biodiversity, and land use. The US dairy industry is not exempt from these effects. The Western states, where wildfires are especially prevalent, are home to more than two million dairy cows that produce more than 25% of the nation’s milk. A new report in the Journal of Dairy Science® examines how dairy cattle in the Western United States may be affected by unique air pollutants from wildfire smoke.
13. Landslides
Severe wildfires strip away plant cover and reduce the soil’s ability to hold water. A new study develops a model to better understand landslide risk following a burn.
“After the record-breaking 2020 wildfire season in California, the charred landscapes throughout the state faced elevated risks of landslides and other postfire hazards. Wildfires burn away the plant canopy and leaf litter on the ground, leaving behind soil stripped of much of its capacity to absorb moisture. As a result, even unassuming rains pose a risk for substantial surface runoff in the state’s mountainous terrain.”
In a new study, Thomas et al. combined satellite data and hydrologic modeling to develop a predictive framework for landslides. The framework uses inputs, including vegetation reflectance and soil texture, among others, and physics-based simulation of water infiltration into the soil to simulate the hydrologic triggering conditions for landslides. The output offers thresholds to monitor the probability of landslides in the years after a burn.
Keep up with the latest findings about wildfires here.
Stay tuned to PreventionWeb as our editors continue to collect the latest research and news about wildfires.