Hundreds of millions of people suffer as wildfire smoke fills cities. New science reveals what is in that smoke, from heavy metals to exotic chemicals – leading to brain damage and early death. Toxic smoke: analysis and interviews with experts in this special edition of Radio Ecoshock.
Listen to or download this Radio Ecoshock show in CD Quality or Lo-Fi (14 MB)
Heat, smoke and drowning rains spread across the world again last week. On August 7, Phoenix Arizona set a new August record of 118 degrees F., 47.7 C. Turkey experienced a record-breaking heatwave, with temperatures reaching 50.5 degrees Celsius (122.9 degrees Fahrenheit) in Silopi, a town in the southeast. This surpasses the previous national record of 49.5 degrees Celsius set in August 2023, according to Reuters. The extreme heat led to wildfires and forced evacuations in some regions, with firefighters battling blazes for days. Cyprus fires resulted in a new record for highest annual cumulative wildfire emissions in two days. Greece was burning again.
Tourists hoping to escape the heat in Northern Finland were in for a surprise. Even in Lapland temperatures were above 30 degrees C, 86 F. for 22 straight days, and with tropical nights! There was no escaping the heat in all Scandinavia.
Also last week, Japan suffered through its hottest day on record, with the mercury reaching 41.8 C [107 F]. Hospitals filled up with heat victims.
In Korea, The Guardian reports “Overnight temperatures in Seoul stayed above 25C [77 F] for 22 consecutive days in July, meteorological officials said – the longest period since modern weather records were first kept in 1907.”
According to YaleClimateConnections, 4 billion people experienced a whole extra month of extreme heat in the past year and that is the direct result of human-caused climate change.
4 billion people experienced a whole extra month of extreme heat in the past year
California is also burning again, with serious fires around Santa Barbara and up the coast. The Canyon Fire exploded over 5,000 acres overnight. In Arizona, at the North Rim of the The Dragon Bravo fire burned more than 133,000 acres, becoming the largest in the country, and still out of control as we go to air.
According to the EU Copernicus eye-in-the-sky satellite service “In July, wildfires in Arizona emitted a total of around 1.5 megatonnes of carbon emissions, the highest level for the month in the CAMS record. Meanwhile, wildfire emissions in New Mexico were the third highest on record for July, only surpassed by the years 2011 and 2003.”
“The UK recorded its highest annual total wildfire emissions, following large wildfires in northern Scotland at the end of June.” [Copernicus Atmosphere Monitoring Service (CAMS) August 4 2025]
Meanwhile, France has it’s largest wildfire since 1949 burning 16,000 hectares of forest – an area one-and-a-half times the size of Paris. The French Prime Minister called it “a catastrophe on an unprecedented scale”, and blamed global warming.
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TOO CLOSE TO HOME
As I nervously sent out last week’s show, worried about wildfire, this happened: a massive bolt of light and noise, like a stun grenade. This was the closest lightning strike in my long life. It shook the windows and walls. It shook me. The temperature dropped 20 degrees Fahrenheit – 11 Celsius – in minutes. As I looked out, another orange bolt struck the hillside directly across from our home. It instantly started a grass and brush fire – a circle of bright flames expanding on all sides. Minutes later we heard a big diesel fire engine start up in our volunteer fire hall.
Then it got stranger. We live in a so-called “pocket-desert” in southern British Columbia. We get lightning, but it is almost always dry lightning with no rain. In fact, our Province was hit by over 40,000 lightning strikes in that two day period. But this time, a miracle happened. The dark cloud burst open and heavy rain put out the fire that threatened us with evacuation and maybe even losing our home.
It makes an impression. It makes me even more dedicated to the climate fight and this show.
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DON’T BREATH
This year in South East B.C. we also got away with almost no wildfire smoke, even as Canada heads into another record-smashing year for wildfires. Millions of Canadians are smoked out. In Fort Mac in Northern Alberta it was almost dark at Noon and totally toxic. On the air quality scale where up to 50 is good, and 100 signals danger, Jeff Masters reports the The AQI hit 2242: 10x higher than the “hazardous” level.
In the show you hear a short clip from the Weather Network about Fort Mac air (or lack of it).
There were 747 wildfires in Canada in the first week of August. This is now the third most extreme Canadian fire year on record according to the Copernicus Atmosphere Monitoring Service. 2025 is catching up on the disaster year of 2023. “Since the start of the year, the cumulative total estimated emissions for Canada is 180 megatonnes of carbon; already making it one of the top three extreme wildfire years in the 23 years of the CAMS Global Fire Assimilation System records“.
The Provinces of Manitoba and Saskatchewan declared emergencies, with thousands evacuated on short notice from northern communities. Smelly clouds drifted all the way through to Eastern Canada and across the Atlantic. Canadian Atlantic Provinces of Newfoundland and Nova Scotia also declared fire emergencies, as fires and evacuations sprung up even there. No one was allowed to go in the woods.
American media blames Canada for dangerous smoke from the U.S. Mid-West to the East Coast. Chicago and New York were among the most polluted cities in the world for a few days. But people continued to work and play outside, unaware of the risk to their health, now and in the future.
MEDIA DISCOUNTS THE RISK
Most media warnings say people with certain health conditions and infants need to be cautious during wildfire smoke events. As usual, mainstream media is discounting the real risks. Absolutely everyone is at risk when breathing wildfire smoke. During smoke, athletes and musclemen can and do drop dead from heart attacks or strokes. Everyone may add to their cancer-risk burden of heavy metals and other toxic materials – even from so-called “natural” fires in Canada’s far north. Tiny particles in wildfire smoke can cross the blood barrier and is known for brain damage, including increasing the risk of dementia.
We still don’t know the true toll of wildfire smoke. Doctors often leave those details out of death certificates, noting “heart attack” as the cause of death, for example. It Is hard to know the long-term toll, especially as the greatest harms come to people at the bottom of the social order, like outdoor farm workers, and people in developing countries where no records are kept, no studies done, and little media coverage. I will pass on the numbers I managed to find and the sources.
PROTECT YOURSELF
Self-protection is possible for many of us. First, stay inside. Yes, smoke will penetrate almost any building but amounts will be much less. Then, if you can, put up a second layer of defense: install a portable HEPA filter and keep it where you or loved ones are. These filters are very effective at protecting your lungs, organs and brain.
If you must go outside, wear an N95 mask. They work. If traveling by bicycle or motorcycle, you need specialized breathing filters as you scoop more from the air. Protect your eyes as well.
WHAT MICRO-PARTICLES LOOK LIKE
We have to picture tiny micro-particles to fully understand their nature. There are almost countless different compositions forming tiny particles from wildfires. Place on a human hair, with a microscope, you might be able to see them as blackish dots. We imagine them as flattish flecks but they are not. Picture instead an traveling asteroid with bulges and holes. It accumulates other ultrafine particles from toxic chemicals to heavy metals or bacteria. It is this combination that can go from our lungs into the blood stream, and even by nose into the brain. That is what PM2.5 and it’s smaller cousins represents.
All this comes as super fires burn in many countries, and extreme heat waves set up the rest.
WHAT IS IN THAT WILDFIRE SMOKE?
According to new science published April 2025, wildfire smoke can contain:
carbon monoxide (CO),
nitrogen oxides (NOx),
sulfur oxides (SOx),
methane (CH4),
non-methane organic compounds (NMOC),
lead (Pb), and
ozone (O3)
– all emitted directly from the fires. In the atmosphere, chemical interaction with wildfire smoke leads to further toxins like Peroxyacetyl Nitrate (PAN), and secondary organic aerosols (SOA).
They left out mercury, which can rise up in wildfire smoke from industrial sites and forest floors. Mercury causes Minamata disease, numbing of limbs and death, as well as heritable birth defects.
RAISING RADIATION
The scientists also left out radiation. Fires burning from former nuclear accidents, like Chernobyl or Fukushima, release more radioactive materials (cancer causing) even decades after a fire. This was a concern in 2010 when wildfires around Chernobyl lunched more radiation into the air. Fortunately that did not reach Europe. Some of the radioactive particles from four nuclear reactors that blew up in Fukushima Japan landed in the United States all the way to Pennsylvania. These can then be carried up again in a forest fire.
Radioactivity can also be raised with fire smoke from improperly stored nuclear sites, and possibly if an operating or moth-balled nuclear power plant is burned over. Still, overall, this is a rare risk compared to the guaranteed threat of negative health impacts of breathing in heavy wildfire smoke.
WILDFIRE HEALTH IMPACTS
MICHAEL BRAUER
What is all this wildfire smoke doing to our health? I play a selection from his speech. Dr. Michael Brauer speaking on health impacts and personal protection during smoke events. I recorded Michael in Vancouver at American Academy for the Advancement of Science meeting February 19, 2012. His experience at University of British Columbia is still what we need to know now about wildfire smoke.
This interview was originally broadcast in the show “Fire! In A Crowded World” Posted on April 19, 2012.
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SMOKE IN THE BRAIN
In the leading science journal PNAS, Lynne Peeples wrote the article “How air pollution threatens brain health”. She describes how tiny particles from wildfire smoke reach our brains. Quote:
“Metal-toting particles that reach the brain can directly damage neurons. Both the particles themselves and their toxic hitchhikers can also cause widespread harm by dysregulating the activation of microglia, the immune cells in the brain. Microglia may mistake the intruders for pathogens, releasing chemicals to try to kill them. Those chemicals can accumulate and trigger inflammation. And chronic inflammation in the brain has been implicated in neurodegeneration
Particles may also afflict the brain via the bloodstream. Research shows that small particles can slip through the plasma membrane of alveoli—the tiny air sacs in the lungs—and get picked up by capillaries. The particles are then distributed around the body in the blood. Although some of these particles may eventually breach the blood–brain barrier, a pollutant need not enter the brain to cause trouble there. The immune system can react to particles in the lung or bloodstream, too, triggering widespread inflammation that affects the brain.”
That was from Lynne Peeples in PNAS June 3, 2020.
So when experts say get and use a HEPA filter for your home or work space, avoid outside smoke, and use an N95 mask if you can’t – believe them. Please, protect your brain from wildfire smoke. You may think better and longer.
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WILDFIRE SMOKE AND DEMENTIA
Dr. JOAN CASEY
Let’s take the case of wildfire smoke and dementia. One can lead to the other. In fact, Dr. Joan Casey found breathing wildfire smoke increases risk of dementia by 18%. Dr. Joan Casey is an Environmental Epidemiologist and Associate Professor at the University of Washington. Here are key selections on brain health and fire smoke, from our interview first broadcast on December 11th, 2024.
Dr. Joan Casey reports breathing wildfire smoke increases risk of dementia by 18%. As record wildfire years pile up, yes, climate change can drive you mad. Protect your brain!
Listen to or download the original 29 minute interview with Joan Casey in CD Quality or Lo-Fi
AS THE BOREAL BURNS
9 REASONS WHY LISTENERS IN AMERICA, EUROPE OR RUSSIA SHOULD CARE
In the USA and Canada, in Europe, Russia or wherever you are, you need to pay attention to fires in the great Boreal forests ringing the north of this planet. This is the other Amazon, the other big hinge in the carbon system and your future climate – even in Australia. The media never pulls this together. Here are nine very serious reasons why you need to care about the Boreal Forest.
1. HEALTH
* As we heard, wildfire smoke invades parts of the continent with serious health impacts, deadly for some. Microscopic smoke particles or PM2.5 from wildfires is 3 to 10 times more toxic per unit than PM2.5 from common urban sources. Wildfire smoke intensifies risks for asthma, lung function decline, and cardiovascular events, especially in children, the elderly, and people with preexisting health conditions.
Check out this new science paper: “Impacts of wildfire smoke aerosols on radiation, clouds, precipitation, climate, and air quality” led by Rahele Barjeste Vaezi and published in April 2025.
They find:
“Wildfires release toxic gases, encompassing carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), methane (CH4), non-methane organic compounds (NMOC), lead (Pb), and ozone (O3) emitted directly from the fires (Jaffe et al., 2020; Durán et al., 2014; Reisen et al., 2015; Badarinath et al., 2007), as well as Peroxyacetyl Nitrate (PAN), secondary organic aerosols (SOA), and oxygenated NMOC [an organic carbon compound] – which are formed in the atmosphere as a result of chemical interactions with primary pollutants (Durán et al., 2014; Singh et al., 2012).”
2. SMOKE AND CLOUDS
Smoke from wildfires also influences cloud formation across the continent. Recent satellite missions (e.g., EarthCARE, 2025) have visually tracked massive smoke plumes from Canadian wildfires reaching high altitudes (up to 17 kilometers or ten miles high. The smoke mingles with atmospheric moisture, enabling the formation of cirrus (ice) clouds and influencing lower-level water clouds thousands of kilometers from the source.
EarthCARE is Earth Cloud, Aerosol and Radiation Explorer launched by the European Space Agency in May 2024. The satellite and science are a joint venture between ESA and JAXA (Japan Aerospace Exploration Agency).
At the same time, wildfire smoke is helping hiding true levels of warming. We discovered that with Ecoshock guest Edward Blanchard-Wrigglesworth. He was part of a NASA science team monitoring polar ice.
Edward and I started with a concrete case. In June 2023 skies over New York City turned orange during the day. According to a peer-reviewed publication from Rutgers, smoke from mass wildfires in Canada cooled New York by 3 degrees Celsius, over five Fahrenheit. That a good example of the cooling in this new study.
The paper title say a lot. The title is “Increasing boreal fires reduce future global warming and sea ice loss”.
The Abstract says:
“…we find that increasing boreal emissions reduce global warming by 12% and Arctic warming by 38%, reducing the loss of sea ice. Tropical precipitation shifts southward as a result of the hemispheric difference in boreal aerosol forcing and subsequent temperature response.”
The clouds formed with tiny particles in wildfire smoke may reflect more sunlight, cooling while they last, and may suppress rainfall.
3. CHANGE IN ALBEDO
There may be a change in reflectivity of deforested ground (either positive or negative)(there are both, but overall the wildfire change in reflectivity is judged to be small by scientist Rahele Vaezi.
4. PEOPLE AND ANIMALS ARE HURT
People and animals live in the Boreal forest. Their lives and livelihoods have been affected. First Nations people in the Canada’s northern prairies were evacuated, some at the last minute by military cargo planes. All hotel rooms in Winnipeg were quickly filled, leaving other in arena-type beds or travel to another province. Not everyone can afford any of that. Some evacuees are frightened or worried. Being chased out of your life home by roaring fire is traumatic. Countless animals die in fires, while other starve afterward.
5. GIGATONS MORE WARMING CARBON INTO THE ATMOSPHERE FROM FIRES
Massive amounts of new carbon is emitted into the air, making the burning Boreal emissions equal to adding another large industrial country. In 2023, Canadian wildfires were the fourth largest greenhouse gas source in the world. In a paper called “Carbon emissions from the 2023 Canadian wildfires” Brendan Byrne, and his colleagues said: quote
“We find that the magnitude of the carbon emissions is 647 TgC (570–727 TgC), comparable to the annual fossil fuel emissions of large nations, with only India, China and the USA releasing more carbon per year.“
That was published in Nature August 2024. It is free, Open Access, look it up.
By the way, at “TgC” is a teragram of carbon, equal to one million tonnes. This is the same as one megaton.
6. FIRE STIMULATES METHANE RELEASE
Methane is a powerful greenhouse gas, considered a driver in almost a third of warming since pre-industrial times. More methane is released by the fire process. Permafrost is exposed, which then releases CO2 and methane for years. even decades after the fire. Boreal forest fires emit substantial amounts of methane directly into the atmosphere, primarily through smoldering combustion of organic matter. This is especially true in systems rich in peat or organic soils, where smoldering releases more methane compared to flaming combustion.
Large, intense fires – like those in recent years – lead to notable spikes in atmospheric methane during the fire event itself. Again, methane release does not end when the flames are extinguished, but may continue for years after severe fires.
7. CROP PRODUCTIVITY?
Wildfire smoke may reduce crop productivity – thousands of miles away as smoke is transported. However, the science about that is scarce and not clear.
8. MORE BOREAL FIRES IN SCANDINAVIA AND RUSSIA
None of this includes impacts from Wildfires in Boreal forest in Scandinavia and Russia. The impacts there may be similar. Are there differences?
9. WILDFIRE COMES ON TOP OF HEAVY LOGGING OF THE BOREAL
Major loss of forests due to fires comes ON TOP OF industrial clear-cutting of Boreal forest by multinational corporations for things like tissue and toilet paper.
Reliable figures for area burned by fire and area logged each year in Russia are not available but both are large, with all the problems considered above.
However, the area in Canada burned by wildfires in 2023 was roughly 20 to 26 times greater than the typical area of forest harvested each year (about 700,000 hectares annually). The 2023 total area burned was between 15 million and 18.5 million hectares. – more than double the previous record and many times the historical average.
The 2025 wildfire season in Canada has been another severe one, with a cumulative area of approximately 6.5 million hectares burned as of early August. It is becoming another in a series of worst fire years on record. Again, less than a million hectares was logged, according to industry reported figures. 700,000 hectares is equivalent to 7,000 square kilometers or 2,700 square miles. A forest area more than half the size of England is removed from the Canadian Boreal forest every year. There will be multiple consequences for that, some feeding into planetary changes.
The Amazon and the great Boreal Forest both help regulate the climate of the world. Both are being eaten away by combined logging and fire. Already both great forests are changing from carbon sinks to capture our pollution, to carbon sources, adding to climate change. They have limits, and tipping points, beyond which they do not recover. We don’t know where those tipping points there and cannot afford to find out the hard way.
Save the Boreal. Support non-profit Boreal campaign groups like Greenpeace and the David Suzuki Foundation. Let others know you care, and they should too – to protect a livable Earth. Thank you for your attention to this matter.
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And Now for Something completely different…
WHAT IS THE LARGEST AMPLIFIER OF WARMING?
ANOTHER CLIMATE FEED-BACK: THE LATENT HEAT ENGINE
When water vapor condenses to ice or rain in the atmosphere, it releases energy or heat. If the atmosphere can hold more water vapor as the world warms, is there an increase in the transfer of energy from the ocean to the atmosphere? Does that warm the world even more?
With global warming, the atmosphere’s capacity to hold water vapor increases about 7% more for every degree Celsius of warming. At 1.5 degrees C warming now, the atmosphere can hold 10% more water vapor than in pre-industrial times. This leads oceans to evaporate more water, transferring more latent heat from the ocean to the air. So, the energy flow from ocean (via evaporation) to the atmosphere (via condensation and precipitation) intensifies. This amplifies the “latent heat engine” of the planet, making storms potentially more powerful and increasing heat release into the atmosphere.
Water vapor feedback is recognized by the IPCC as the largest single contributor to amplifying global warming. Water vapor amplifies the warming that is initiated by other greenhouse gases, more than doubling the rise in temperature that would occur from CO2 alone.
When that vapor condenses in the atmosphere, the energy is released as heat, warming the surrounding air. This process is one of the main ways energy is moved from the ocean to the atmosphere and powers weather systems. But it does not add extra heat to the Earth system – it redistributes existing heat. This redistribution is central to Earth’s climate system. It moves heat from regions where evaporation occurs (often tropical oceans) to where condensation occurs (clouds and precipitation, sometimes at distant locations or higher altitudes). It does not constitute a net gain or loss of energy for the planetary system as a whole.
The transfer of heat from ocean to atmosphere is not a cause of warming, but an amplification of warming driven by other greenhouse gases like carbon dioxide and methane.
We inhabit an amazing system which the best of our brains are beginning to understand. We desperately need pop-up climate schools, Earth learning sessions at work and in the church. All humans need to understand how “weather disasters” increase, why, and what we must do to put the brakes on climate change.
Then we try to live up to our legacy and obligation to following generations. We may fail at first, or often, but try, try, again.
Our time is up – for this week. I’m Alex Smith. Thank you for listening and caring about our world.
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