Tag Archives: smoke

Australia’s wildfires created a ‘record-breaking’ smoke plume in the upper atmosphere

Australia’s bushfires set a record for the largest smoke cloud generated by a wildfire, a new paper reports. The plume was at least three times larger than any previously recorded one.

Image credits Terri Sharp.

Researchers at the University of Saskatchewan’s (USask) Institute of Space and Atmospheric Studies say that last winter’s Australian wildfires created a smoke cloud that pushed all the way to the stratosphere, some 35 kilometers above the surface, and reached incredible sizes. At its largest, it measured 1,000 kilometers across. The cloud remained intact for three months and traveled over 66,000 kilometers.

King smoke

“When I saw the satellite measurement of the smoke plume at 35 kilometres, it was jaw dropping. I never would have expected that,” said Adam Bourassa, professor of physics and engineering physics, who led the USask group which played a key role in analyzing NASA satellite data.

The fires seen in Australia this year were so devastating that the summer of 2020 has been nicknamed the “Black Summer“. It’s an apt name — the blazes claimed over 5.8 million hectares of forest in the continent’s southeast and bellowed massive amounts of smoke.

An international research team led by Sergey Khaykin from Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) in France. The findings, they hope, will help us better understand how wildfires interact with and affect our planet’s atmosphere.

“We’re seeing records broken in terms of the impact on the atmosphere from these fires,” said Bourassa. “Knowing that they’re likely to strike more frequently and with more intensity due to climate change, we could end up with a pretty dramatically changed atmosphere.”

Bourassa’s team has experience in a specific type of satellite measurement that can pick up on smoke in the upper layers of the atmosphere. He explains that wildfires such as those in Australia and Western Canada (in 2017, the world’s second-largest to date) got so big that they generated their own clouds, Pyrocumulonimbus, and their own thunderstorms.

These thunderstorms create powerful updrafts that propel smoke and air all the way to the stratosphere, which is higher than the altitudes that commercial jets typically fly at.

The team used a satellite-mounted device called a spectrometer to analyze the plumes. In essence, they measured how much sunlight was scattered (reflected) from the atmosphere back to the satellite, which gave them a detailed layer-by-layer look at the atmosphere.

One finding, that Bourassa calls “amazing” is that this smoke starts absorbing sunlight and heating up. When it gets hot enough, it starts “to rise in a swirling vortex ‘bubble’, and it just rose and rose higher and higher through the atmosphere.”

Another finding was that the smoke from Australia’s wildfires blocked sunlight from reaching the surface to an extent never seen before. The issue was compounded by the fact that the stratosphere is typically quite stable, meaning aerosol particles such as those in smoke can remain in suspension here for months on end, having a disproportionately-high effect on climate.

The paper “The 2019/20 Australian wildfires generated a persistent smoke-charged vortex rising up to 35 km altitude” has been published in the journal Communications Earth & Environment.

Suspension Bridge.

Wildfires in Africa keep the Amazon lush with fertilizing smoke

New research from the University of Miami’s Rosenstiel School of Marine shows that African wildfires supply the Amazon with vital nutrients.

Suspension Bridge.

Image via Pixabay.

The team reports that winds blow nutrient-rich aerosol (i.e. smoke) from Africa that keep the Amazon Basin fertile. These aerosols are estimated to deposit around one half of the phosphorus that plant life in the Basin consumes. In effect, this makes the African continent a key player in the Amazonian ecosystem.

Airmail nutrients

“It had been assumed that Saharan dust was the main fertilizer to the Amazon Basin and Tropical Atlantic Ocean by supplying phosphorus to both of these ecosystems,” says the study’s senior author Cassandra Gaston, an assistant professor in the Department of Atmospheric Sciences at UM’s Rosenstiel School.

“Our findings reveal that biomass burning emissions transported from Africa are potentially a more important source of phosphorus to these ecosystems than dust.”

Previous research has shown that dust blown over from the Sahara and other desert regions in Africa act as sources of nutrients for South America. The role of smoke in this, however, was still unknown.

Besides seeding the Amazonian Basin with phosphorus — enabling its wealth of biodiversity and productivity to sequester significant amounts of atmospheric carbon dioxide — the team also found that these aerosols fertilize the Tropical Atlantic and Southern oceans (TAO), sustaining the phytoplankton that is the basis of the marine ecosystem in the region.

The findings are based on measurements of windborne dust, phosphorus  and soluble phosphorus Amazon’s northeastern coast. The team also tracked winds from the African continent using satellite data.

Wind-borne dust wasn”t very rich in phosphorus. The team reports that it actually acts as the area’s main supply of low-solubility phosphorus (P) in February through April contributing around 5%. September through November, however, the team recorded high levels of soluble P originating from biomass fires in Southern Africa. This also coincided with the season when dust deposits are lower.

The team crosschecked their findings by identifying aerosols from Africa on high-soluble-P measurement days using satellite imagery. They also traced back all high-soluble-P aerosols in air masses that had passed over the Sahara and the Sahel where biomass burning was active.

The team says their findings offer a new perspective on biomass-burning emissions, which are considered primarily destructive in terms of air quality. While such events are known to promote new growth in their wake, it’s exciting to see how it can affect developments on a whole other continent.

It also helps explain how the Amazon Basin manages to retain its immense biodiversity and productivity despite heavy, year-round rainfall, which drains the soil of nutrients. It dentifies an important nutrient source for marine ecosystems in the region.

The paper “African biomass burning is a substantial source of phosphorus deposition to the Amazon, Tropical Atlantic Ocean, and Southern Ocean” has been published in the journal PNAS.

Credit: Pixabay.

Pleasant odors might help decrease cigarette cravings

Quitting smoking is daunting due to the intense cravings for nicotine. Some people go through multiple cessations only to relapse time and time again. According to new research, inhaling pleasant odors may be enough to temporarily reduce the urge to light a cigarette, suggesting it could be a useful addition to effective smoking cessation strategies.

Credit: Pixabay.

Credit: Pixabay.

In the United States, a much smaller percentage of the population smokes compared to 50 years ago. In absolute numbers, though, there are still about 40 million Americans who smoke. Cigarettes cause more than 480,000 premature deaths in the United States each year. Most adult smokers are not only aware of the risks they’re subjecting themselves to but would also like to quit. At least half of all smokers report having tried to quit in the past year, yet half of those who try relapse within two weeks.

For most smokers, the pressure of nicotine cravings is like a psychological bungee cord that yanks those who try to quit back towards their lighters. Although nicotine is not nearly as intensely rewarding as other drugs such as marijuana or opioids, it’s an extremely addictive substance. Like other drugs, it stimulates the release of dopamine in neurons that connect the nucleus accumbens with the prefrontal cortex, amygdala, hippocampus, and other brain regions. Each time a person takes a puff out of a cigarette, the brain reinforces this behavior. The amount of released dopamine isn’t great compared to other drugs, but nicotine makes up for it through repetition — a person who smokes a pack of cigarettes a day typically is exposed to roughly 250 hits of nicotine. Over months or years, that’s a lot of reinforced behavior, which makes it highly difficult afterward to unlearn the mildly rewarding behavior of lighting up a cigarette.

Long story short, nicotine cravings are high-wired in the smoker’s brain and are very difficult to control. But maybe taking a whip of a pleasant aroma might be enough to calm a smoker’s nerves, for a little while at least.

For their study, researchers at the University of Pittsburgh recruited 232 smokers, aged 18 to 55, who at the study’s onset were not trying to quit nor were they using any alternative nicotine delivery system, such as vaping or gum. The participants were asked not to smoke for at least eight hours before prior to the experiment and were told to bring a pack of their favorite cigarettes and a lighter with them.

Each participant was asked to smell and rate a number of different odors that are generally considered pleasant (i.e. apple, peppermint, lemon, vanilla, etc) as well as unpleasant ones, tobacco smoke, and a blank (no distinguishable odor). The participants were then asked to light a cigarette but not smoke it. After 10 seconds of holding the lighted cigarette in their hands, the participants had to rate their urge to smoke from a scale of 1 to 100 before extinguishing the cigarette.

The participants then inhaled a scent from a container that was either an odor they had rated as most pleasurable, the scent of tobacco, or blank. After taking one sniff, the participants had to again rate their urge to smoke. They continued to inhale the scent for the next five minutes, rating their urge to smoke every 60 seconds.

Not surprisingly, the participants rated the odor of tobacco smoke from their preferred brand of cigarettes with the highest cravings score (82.13%). However, when inhaling a pleasant odor, the average craving scores dropped significantly (19.3%), compared to smelling tobacco (11.7%) or the blank scent (11.2%).

“Despite disappointing relapse rates, there have been few new approaches to smoking cessation in general and to craving relief in particular,” said lead author Michael Sayette, of the University of Pittsburgh. “Using pleasant odors to disrupt smoking routines would offer a distinct and novel method for reducing cravings, and our results to this end are promising.”

The drop in nicotine craving lasts for as long as five minutes, which can be enough time for a smoker to decide against lighting a cigarette or leave from a high-risk situation. As to why a pleasant aroma might relieve cravings, the researchers believe that the scent may distract smokers by triggering memories associated with these cues. For instance, peppermint reminded one of the participants of childhood Christmas holidays. More research is needed to verify this hypothesis.

“Our research suggests that the use of pleasant odors shows promise for controlling nicotine cravings in individuals who are trying to quit smoking,” concluded Sayette.

The findings appeared in the Journal of Abnormal Psychology.

Smoked foods are more tasty, but also more unhealthy

Smoke can infuse foods with delightful, elegant flavors, but it can also add some unwanted carcinogens. To get rid of these intruders, researchers are taking a page from the auto industry.

Many people enjoy smoked foods — my personal favorite is smoked tea, Lapsang souchong. Image credits: Sjhan81 / Wikipedia.

I remember when I first came across a type of tea called Lapsang souchong — a unique variety of black tea, smoke-dried over pinewood fire. It was a spectacular aroma and it sent me on a smokey frenzy, chasing all the smoked foods I could find. Likewise, many people enjoy smokey flavors — whether it’s cheese, meat, or even whiskey — but not too many are aware of the downsides of the smoking process.

“The smoking process can cause carcinogens to form in foods. Not all smoked foods are dangerous, but we do know most can contain low levels of these substances, so we should try to remove them. If we could produce a smoke with fewer carcinogens, but that still has the same great taste, that would be ideal,” says Jane K. Parker, Ph.D., leader of the study.

With this in mind, Parker and her colleagues developed filters made from zeolites — microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts — remove as many carcinogenic polycyclic aromatic hydrocarbons (PAHs) from smoke as possible. This is a technique commonly used in the auto industry to reduce emissions.

“Zeolite filters, which are put in a tailpipe, have been used in the car industry to reduce environmental pollutants, but they haven’t been applied to food yet. We want to change that.”

The most efficient filter they designed eliminated 93% of carcinogens, but the problem of taste remained — did they also remove 93% of the smokey taste? In order to test this, researchers had a panel of expert tasters try out smoked tomato flakes, coconut oil and water using either filtered or unfiltered smoke. They found that the filtered smoked foods had a much more rounded and balanced flavor, tasting even better than the unfiltered ones.

This was a bit surprising, so Parker took to mass spectrometry to analyze the compounds in the two types of smoke, trying to figure out what caused the differences.

“The profiles showed that it was largely the higher molecular weight components that were being removed by the filter,” Parker says. “These chemicals may be the ones giving the foods a harsher flavor and aroma profile.”

So not only does the filter make things much healthier, it also makes them taste a bit better. So far, the study hasn’t been peer-reviewed but was presented at the 255th National Meeting & Exposition of the American Chemical Society.

Smoking one pack a day causes your lung cells’ DNA to mutate 150 times every year

Researchers have quantified the damage smoking does in different organs of the body for the first time and have also identified several different mechanisms by which tobacco smoke causes mutations to appear in DNA. The new study published by the Wellcome Trust Sanger Institute, the Los Alamos National Laboratory, and contributors, found that smokers show an average of 150 extra mutations per cell in their lungs for each year of smoking one pack a day.

Image credits Sasuka / Pixabay.

The study provides a clear and solid link between the number of cigarettes smoked over a person’s lifetime and the number of mutations in tumor DNA. The highest rates were seen in the organs and body parts which come into contact with smoke — particularly lungs — but other areas also showed damage from smoking. Tumors in these areas also contained smoking-associated mutations even if they don’t come into contact with smoke — helping to explain why smoking can cause multiple types of cancer in humans.

Cancer appears when a cell’s DNA becomes too different from its original state by accumulating mutations. The study provides the first comprehensive analysis of the genetic make-up of cancerous cells linked to smoking. The team studied over 5,000 tumors, comparing cancer cells from smokers to those of non-smokers (people who had never smoked were selected). They found that smoking left molecular “fingerprints” on DNA, called mutational signatures, and counted how many of these particular variations existed in different tumors. On average, they found, one-pack-a-day smokers developed 150 new mutations in each lung cell per year. And each one of these mutations could lead to cancer.

“Before now, we had a large body of epidemiological evidence linking smoking with cancer, but now we can actually observe and quantify the molecular changes in the DNA due to cigarette smoking,” said Dr Ludmil Alexandrov, first author from Los Alamos National Laboratory.

“With this study, we have found that people who smoke a pack a day develop an average of 150 extra mutations in their lungs every year, which explains why smokers have such a higher risk of developing lung cancer.”

While the exact number of mutations per lung cell will obviously vary from individual to individual, the study found it’s not only lung cancer smokers have to worry about. Larynx cells, for example, rake in an average of 97 mutations per year; for pharynx cells, an average of 39 mutations was recorded. Mouth cells, 23. Bladder, 18 mutations, and liver cells 6 mutations per year. While it was known that smoking increases the overall risk of cancer in other parts of the body than the respiratory system, we didn’t really understand why. The team revealed that different mechanisms determine mutations from tobacco smoke in different parts of the body.

“The results are a mixture of the expected and unexpected, and reveal a picture of direct and indirect effects,” said Prof David Phillips, co-author of the paper and Professor of Environmental Carcinogenesis at King’s College London.

“Mutations caused by direct DNA damage from carcinogens in tobacco were seen mainly in organs that come into direct contact with inhaled smoke. In contrast, other cells of the body suffered only indirect damage, as tobacco smoking seems to affect key mechanisms in these cells that in turn mutate DNA.”

Smoky business

Five distinct mechanisms of DNA damage were identified. The most widespread is a mutational signature found in all cancers — here, tobacco seems to accelerate a kind of cellular clock that mutates DNA prematurely.

“The genome of every cancer provides a kind of “archaeological record,” written in the DNA code itself, of the exposures that caused the mutations that lead to the cancer,” said Professor Sir Mike Stratton, joint lead author from the Wellcome Trust Sanger Institute.”

“Our research indicates that the way tobacco smoking causes cancer is more complex than we thought. Indeed, we do not fully understand the underlying causes of many types of cancer and there are other known causes, such as obesity, about which we understand little of the underlying mechanism. This study of smoking tells us that looking in the DNA of cancers can provide provocative new clues to how cancers develop and thus, potentially, how they can be prevented.”

Smoking has been epidemiologically linked with at least 17 different types of human cancer. There are roughly six million tobacco-associated fatalities every year, worldwide. The WHO predicts that, if current trends continue, we’ll see more than 1 billion tobacco-related deaths by the end of the century.

The full paper, “Mutational signatures associated with tobacco smoking in human cancer” has been published in the journal BioRxiv.


Modern humans lost some of their smoke-resistance genes and we don’t know why

Researchers peeking into our genetic code found that modern humans are less adept at handling smoke-borne toxins than the Neanderthals. We’re even worse at it than great apes, they add.

Smoke churning out of an US-issue green M18 grenade.
Image credits Lance Cpl. Jody Lee Smith / Released by the U.S. Marine Corps.

Modern human society can arguably trace its roots back to our mastery of fire. It not only let us prepare high-quality, energy-rich food, but provided protection against the cold, predators, and it underpinned early technology and industry.

But it’s not all rosy. Exposure to the toxic compounds released in smoke (such as like polycyclic aromatic hydrocarbons) can take a heavy toll on our bodies, increasing the risk for pneumonia as well as a host of other conditions and negatively impacting pregnancy development in women and sperm quality in males.

This double edge has sent researchers from the Leiden University and Wageningen University on a quest to find genetic markers for the use of fire in ancient humans.

It’s all about genes

Archeologists have quite a hard task in pinning the first use of fire, which has led to some pretty heated arguments in the past. Some argue that humans have been using it for as long as two million years, but most evidence found in Europe and the Near East suggest that we’ve learned to use fire somewhere around 350,000 years ago.

To bring new insight to this debate, the team looked at the biological adaptations of prehistoric and recent humans to toxic compounds in smoke. Since using fire involved heavy exposure to these compounds in breathed smoke and in cooked food, the team expected it to have an impact on the selection of human genes — specifically, that it would promote individuals who had a built-in resistance against them. They analyzed gene variants from Neanderthal, Denisovan, and prehistoric modern humans.

They tested single nucleotide variants in 19 genes that have been linked to increased risk of fertility and reproduction issues in tobacco smoke studies. These were compared to variants found in Neanderthal and Denisovan genetic material, and with DNA harvested from chimpanzees and gorillas as a control group — we’re closely related but they don’t use fire.

The results showed that Neanderthals and Denisonvans both had genetic variants which were better at handling smoke than we do. Surprisingly, even the apes had them — suggesting they were very old gene variants, inherited from a common ancestor.

Up in smoke

The less efficient variants were only observed from the earliest hunter-gatherers we have genetic information on, so from about 40,000 years ago up to the present. The team suspects the apes’ genes are involved in defending them from toxins in the plants they eat. Our own defenses apparently borrow heavily from those adaptations, being developed deep in our primate ancestry.

The findings show that our ancestors were well equipped to deal with smoke long before they made any fires for themselves. Somewhere along the line though, we traded these genes for their less efficient variants. Previous studies have discovered, however, that modern humans have developed a whole new set of mutations to help them cope with toxic smoke compounds, so maybe the genetic variants seen in Neanderthals and Denisovans didn’t have a big enough effect to apply selective pressure.

All of this will have to be answered by future research.

The full paper “Fire Usage and Ancient Hominin Detoxification Genes: Protective Ancestral Variants Dominate While Additional Derived Risk Variants Appear in Modern Humans” has been published in the journal PLOS ONE.

High-power lasers create ‘smoke rings’ that travel along the beam with the speed of light

The thin, gray ringlike objects are Spatiotemporal optical vortices (STOVs), 3D light structures that are time dynamic and travel along the central laser pulse. Credit: Howard Milchberg

If you ever shone a cheap laser onto a distant building then you surely noticed the ‘dot’ gets bigger the farther away your fire it. That’s because laser light will gradually expand its size in a cone-shape due to the wave nature of light while losing energy. A high-power laser is totally different, though. In the right conditions, it can act like its own lens to self-focus and create an ever tighter, intenser beam. Strangely enough, a group of researchers discovered that these high-power laser beams also generate swirls of optical energy that engulf the beam sort of like smoke rings. Like the laser beam, the swirls or vortices travel at the speed of light.

Smoke under our noses

The laser smoke rings were dubbed  “spatiotemporal optical vortices,” or STOVs, by the University of Maryland physicists. Given the right conditions, any powerful laser will create them, which makes it kind of odd we’re only now discovering them.

“Lasers have been researched for decades, but it turns out that STOVs were under our noses the whole time,” said Howard Milchberg, professor of physics and electrical and computer engineering at UMD and senior author of the paper published in Physical Review X.

“This is a robust, spontaneous feature that’s always there. This phenomenon underlies so much that’s been done in our field for the past 30-some years.”

There’s another type of optical vortices made by lasers called “orbital angular momentum” (OAM) vortices. Known for decades, OAM vortices are light energy that circles the beam around the direction of propagation much like water spins around a drain’s center of gravity.

Shown as cute pink rings are OAM vortices — 3-D laser light structures that rotate around a central beam, like water circles a drain. This property is exploited by high-resolution microscopy. Credit: Howard Milchberg

Unlike OAM vortices which are stationary, the optical smoke rings are time dynamic, meaning they move along the beam.

OAM vortices have proven very useful in certain optical applications like telecommunications or microscopes due to their ability to create small structures in the light itself. This way, you can control what gets illuminated and what doesn’t.Though there’s no immediate practical application to STOVs, the University of Maryland scientists are fascinated by their ability to manipulate particles moving near the speed of light. There’s still much to be done before we can unravel all of these optical smoke rings’ secrets.

“All the evidence we’ve seen suggests that STOVs are universal,” said Nihal Jhajj, a physics graduate student who conducted the research at the UMD Institute for Research in Electronics and Applied Physics (IREAP). “Now that we know what to look for, we think that looking at a high-intensity laser pulse propagating through a medium and not seeing STOVs would be a lot like looking at a river and not seeing eddies and currents.”


Gene mutation helped early humans cope with smoke infested caves, but not Neanderthals


Credit: Pixabay

Pennsylvania State University researchers claim they’ve uncovered a gene that helps humans cope with the toxicity of smoke. This gene wasn’t found in specimens belonging to Neanderthals or Denisovans, two other hominin species which were contemporary with homo sapiens for thousands of years before becoming extinct.

A smokey edge

The researchers posit that this mutation must have given humans an evolutionary edge against the two other species. Some 50,000 years ago, humans, Neanderthals and Denisovans lived mostly in caves where fires must have clouded everything in smoke.

When we eat grilled meat or inhale smoke, toxic byproducts like polycyclic aromatic hydrocarbons (PAHs) are absorbed by the body which cause DNA mutations, cancer or sudden death. Luckily, when PAHs enter the body enzymes are produced to break down the chemicals and flush them out. If there’s too much smoke, however, the body goes into enzyme production overdrive, which triggers the formation of a number of even more toxic byproducts — but not if you have a gene mutation in the aryl hydrocarbon receptor, found in the in the middle of the ligand-binding domain.

All modern humans have this mutation, but when the researchers led by Gary Perdew, the John T. and Paige S. Smith Professor in Agricultural Sciences, Penn State, sequenced the DNA of three Neanderthals and one Denisovian they couldn’t find any. Not having this mutation could have made all the difference — from a hundred to a thousand-fold more aryl hydrocarbon receptor ligand sensitivity.

“For Neandertals, inhaling smoke and eating charcoal-broiled meat, they would be exposed to multiple sources of polycyclic aromatic hydrocarbons, which are known to be carcinogens and lead to cell death at high concentrations,” said Perdew in a statement. “The evolutionary hypothesis is, if Neandertals were exposed to large amounts of these smoke-derived toxins, it could lead to respiratory problems, decreased reproductive capacity for women and increased susceptibility to respiratory viruses among preadolescents, while humans would exhibit decreased toxicity because they are more slowly metabolizing these compounds.”

The same tolerance also helped humans pick up some bad habits, like smoking tobacco, the researchers wrote in their paper published in Molecular Biology and Evolution

All hominids included in this study knew how to make fire. In fact, a previous study found Neanderthals were clever enough to use manganese dioxide — a substance commonly used in batteries today — to light their camps. The first hominid to use fire was likely Homo erectus, a species which regularly made use of the blaze to cook, fend off predators, provide warmth and possibly ritualistic purposes 1.9 million years ago. Any species which followed H. erectus must have learned to light and maintain fires as well.

“Cooking with fire could have allowed our ancestors to incorporate a broader range of foods in our diets, for example, by softening roots and tubers that might otherwise have been hard to chew,” Perry said. “Cooking could also help increase the digestibility of other foods, both in chewing time and reduced energetic investment in digestion.”

“Besides heating and cooking, humans used — and still use — fire for landscape burning and as part of hunting and gathering, and now as part of agriculture,” he added.

I would caution, however, readers that this is still a tentative hypothesis. After all, the researchers could only look at three Neanderthals and a Denisovan. A lot more DNA from more specimens should be sequenced before any definite conclusion can be made. Already, some critics aren’t convinced.

“Neanderthals were the ultimate cave-dwelling fire users. If there was some selective disadvantage against this, then they would have died out a long time before they did. But they were actually one of the more successful stories in human evolution and lasted a really long time compared to other hominids,” David Wright, an archaeologist at Seoul National University and the University of York, told The Guardian.

“That somehow Homo erectus and Neanderthals and dozens of other hominid species couldn’t handle sitting around a fire, it doesn’t make any sense to me,” he added. “The problem is it’s really difficult to test, because we can’t take a Neanderthal and sit them next to a fire to see how they react.”