Tag Archives: science

Breathing very dirty air may boost obesity risk

Beijing smog

Serious air pollution, like this smog over China’s capital city, may increase the risk of obesity.

Air pollution is bad for our lungs. It may not be great for our waistlines either, a new study in rats finds.

China’s capital city of Beijing has some of the worst air pollution in the world. On really bad days, its air can host more than 10 times as many tiny pollutant particles as the World Health Organization says is safe for human health. In a new study, rats breathed in this air. And those rodents gained more weight, and were unhealthier overall, than were rats breathing much cleaner air. The results suggest that exposure to air pollution can raise the risk of becoming extremely overweight.

And, adds Loren Wold, “It is highly likely that this is happening in humans.”

Wold works at Ohio State University in Columbus. There, he studies how air pollution affects the heart. He was not involved in the new study. But he says it agrees with many other studies that have suggested air pollution can affect metabolism, which is how the body breaks down food and uses it for fuel.

Polluted air contains particles of ash, dust and other chemicals. Sometimes these particles are so numerous that they create a thick, dense smog can cuts visibility.

Earlier experiments among 18-year olds in Southern California had linked heavier traffic with higher body mass index (a measure of overweight and obesity). Areas with heavy traffic also tend to have more of those pollutant particles. Another study found that when pregnant mice were exposed to exhaust from diesel engines, their pups grew up to be heavier. The pups also developed more inflammation in their brains.

In the new study, researchers tested how Beijing’s polluted air affects the health of pregnant rats.

Jim Zhang is an environmental scientist at Duke University in Durham, N.C. He and his co-workers put rats in two indoor chambers in Beijing. They piped polluted air from the city directly into one chamber. Air piped into the other chamber went through a filter. That filter removed almost all of the big pollution particles from the air and about two-thirds of the smaller ones. This made the air more like what people breathe in typical U.S. cities and suburbs, Zhang says.

All rats ate the same type and amount of food. But after 19 days, the pregnant rats breathing the heavily polluted air weighed more than the rats breathing the filtered air. They also had higher amounts of cholesterol — a waxy, fatlike substance — in their blood than did the rats breathing filtered air.

Those breathing the dirtier air had higher levels of inflammation. This is a sign of the body responding to tissue damage. These rats also had higher insulin resistance. This means their bodies weren’t responding as well to insulin, a hormone that helps with using sugar for energy. Insulin resistance can lead to diabetes, a dangerous health condition.

Taken together, the scientists say, these symptoms indicate the rats were developing metabolic syndrome. It’s a condition that puts the animals at risk of heart disease and diabetes.

During the experiment, the pregnant rats gave birth. Their pups stayed in the chambers with their mothers. And young rats that breathed in the polluted air were heavier than pups born to moms living in the cleaner air. Like their moms, the pups breathing very polluted air had more inflammation and insulin resistance.

The longer these pups breathed the dirty air, Zhang says, the more unhealthy they became. This suggests that breathing polluted air for a long time can lead to sickness, Zhang says.

It’s not yet clear exactly how air pollution affects rat metabolism. But it seems, Zhang says, to impair how the animals process fat and sugar. Pollution also increases signs of inflammation in the lungs, blood and fat. Zhang says this is probably what led to weight gain in the animals.

Wold says it might be possible to create medicines that reverse the negative health effects of air pollution. But these medicines will take time to develop.

Until then, Zhang and Wold say that paying attention to air pollution levels can help people manage their health risks. On days when pollution levels are high, they recommend that people stay indoors, if possible — or at least avoid tough outdoor exercise

Missing Y chromosome kept us apart from Neanderthals

The Y chromosome is a hindrance

Modern humans diverged from Neanderthals some 600,000 years ago – and a new study shows the Y chromosome might be what kept the two species separate.

It seems we were genetically incompatible with our ancient relatives – and male fetuses conceived through sex with Neanderthal males would have miscarried. We knew that some cross-breeding between us and Neanderthals happened more recently – around 100,000 to 60,000 years ago.

Neanderthal genes have been found in our genomes, on X chromosomes, and have been linked to traits such as skin colour, fertility and even depression and addiction. Now, an analysis of a Y chromosome from a 49,000-year-old male Neanderthal found in El Sidrón, Spain, suggests the chromosome has gone extinct seemingly without leaving any trace in modern humans.

This could simply be because it drifted out of the human gene pool or, as the new study suggests, it could be because genetic differences meant that hybrid offspring who had this chromosome were infertile – a genetic dead end.

Four gene mutations

Fernando Mendez of Stanford University, and his colleagues compared the Neanderthal Y chromosome with that of chimps, and ancient and modern humans.

They found mutations in four genes that could have prevented the passage of Y chromosome down the paternal line to the hybrid children.

“Some of these mutations could have played a role in the loss of Neanderthal Y chromosomes in human populations,” says Mendez.

For example, a mutation in one of the genes, KDM5D that plays a role in cancer suppression, has previously been linked to increased risk of miscarriages as it can elicit an immune response in pregnant mothers.

“That could be one reason why we don’t see Neanderthal Y chromosomes in modern human populations,” says Mark Pagel an evolutionary biologist at the University of Reading.

It could also be one factor keeping the two species as separate species.

The researchers also used the new DNA sequences to estimate the time when the most recent common ancestor of Neanderthal and modern human Y chromosomes existed. They came up with a figure of around 590,000 years ago, which agrees with other estimates for the split of the two groups.

 

Journal reference: The American Journal of Human Genetics, DOI: 10.1016/j.ajhg.2016.02.023

Protein discovery promises to improve mapping of brain tumors

One of the problems with removing brain tumors is ensuring no cancerous tissue remains so they do not regrow. Now, a new study promises to reduce this problem – scientists have discovered a way to highlight a protein on brain scans so the edges of a tumor can be seen more clearly.
mri scanner
Researchers have found a promising way to show the edges of brain tumors in MRI scans more clearly.

The study, which offers scientists the most complete picture of brain tumors yet, is the work of a team from the University of Oxford in the UK, and was presented on Monday at the National Cancer Research Institute (NCRI) Cancer Conference 2015, in Liverpool, UK.

The edges of a tumor contain the most invasive cancercells. For surgery or radiation therapy to succeed, doctors need good maps that show not only where the tumor sits in the brain, but also where its edges are – a clear delineation between cancerous and healthy tissue.

This is important not only in order to remove all the cancerous tissue, but also because the most invasive cells are at the edge of a tumor, as one of the researchers, Cancer Research UK scientist Nicola Sibson, a professor in the Institute for Radiation Oncology at Oxford, explains:

“If we can’t map the edge of the tumor, surgery and radiotherapy often fail to remove aggressive tumor cells – and the brain tumor can grow back.

Currently, on magnetic resonance imaging (MRI) scans, you can see where the brain tumor is, but its edges are blurred. This is because the MRI spots leaky blood vessels inside the tumor. But on the edges of the tumor, the blood vessels are intact, so they do not show as clearly on the scans.

Highlights edges of both primary and secondary brain tumors

Now, for the first time, Prof. Sibson and her team have discovered a useful protein inside the blood vessels at the invasive edge of brain tumors.

In tests on rats, they showed it is possible to use the protein to define the edges of both primary and secondary tumors on MRI scans.

The protein – called VCAM-1 – is released as part of an inflammatory response caused by the brain tumor. The researchers developed a special dye that recognizes and sticks to the protein. The dye highlights the protein – and thus the edges of the tumor – on MRI scans.

An added advantage, note the researchers, is that the protein is on the inside of the vessels, so the dye can access it from the bloodstream.

Prof. Sibson concludes:

“This research shows that we can improve imaging of brain tumors, which could help both surgeons and radiotherapists with more effective treatment.”

Every year, around 256,000 people worldwide are diagnosed with cancer in the brain or another part of the central nervous system. In the UK, where the study was conducted, this figure is around 9,700, or 27 people a day.

“Brain cancers continue to have very poor survival rates,” says Harpal Kumar, chief executive of Cancer Research UK, which co-funded the study with the Medical Research Council. Kumar adds:

“The holy grail would be to be able to completely remove brain tumors with the help of this new imaging technique – reducing recurrence of the disease and saving more lives.”

Scientists have developed an eye drop that can dissolve cataracts

Researchers in the US have developed a new drug that can be delivered directly into the eye via an eye dropper to shrink down and dissolve cataracts – the leading cause of blindness in humans.

While the effects have yet to be tested on humans, the team from the University of California, San Diego hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that’s currently available to cataract patients – painful and often prohibitively expensive surgery.

Researchers in the US have developed a new drug that can be delivered directly into the eye via an eye dropper to shrink down and dissolve cataracts – the leading cause of blindness in humans.

While the effects have yet to be tested on humans, the team from the University of California, San Diego hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that’s currently available to cataract patients – painful and often prohibitively expensive surgery.

Affecting tens of millions of people worldwide, cataracts cause the lens of the eye to become progressively cloudy, and when left untreated, can lead to total blindness. This occurs when the structure of the crystallin proteins that make up the lens in our eyes deteriorates, causing the damaged or disorganised proteins to clump and form a milky blue or brown layer. While cataracts cannot spread from one eye to the other, they can occur independently in both eyes.

Scientists aren’t entirely sure what cases cataracts, but most cases are related to age, with the US National Eye Institute reporting that by the age of 80, more than half of all Americans either have a cataract, or have had cataract surgery. While unpleasant, the surgical procedure to remove a cataract is very simple and safe, but many communities in developing countries and regional areas do not have access to the money or facilities to perform it, which means blindness is inevitable for the vast majority of patients.

According to the Fred Hollows Foundation, an estimated 32.4 million people around the world today are blind, and 90 percent of them live in developing countries. More than half of these cases were caused by cataracts, which means having an eye drop as an alternative to surgery would make an incredible difference.

The new drug is based on a naturally-occurring steroid called lanosterol. The idea to test the effectiveness of lanosterol on cataracts came to the researchers when they became aware of two children in China who had inherited a congenital form of cataract, which had never affected their parents. The researchers discovered that these siblings shared a mutation that stopped the production of lanosterol, which their parents lacked.

So if the parents were producing lanosterol and didn’t get cataracts, but their children weren’t producing lanosterol and did get cataracts, the researchers proposed that the steroid might halt the defective crystallin proteins from clumping together and forming cataracts in the non-congenital form of the disease.

They tested their lanosterol-based eye drops in three types of experiments. They worked with human lens in the lab and saw a decrease in cataract size. They then tested the effects on rabbits, and according to Hanae Armitage at Science Mag, after six days, all but two of their 13 patients had gone from having severe cataracts to mild cataracts or no cataracts at all. Finally, they tested the eye drops on dogs with naturally occurring cataracts. Just like the human lens in the lab and the rabbits, the dogs responded positively to the drug, with severe cataracts shrinking away to nothing, or almost nothing.

The results have been published in Nature.

“This is a really comprehensive and compelling paper – the strongest I’ve seen of its kind in a decade,” molecular biologist Jonathan King from the Massachusetts Institute of Technology (MIT) told Armitage. While not affiliated with this study, King has been involved in cataract research for the past 15 years. “They discovered the phenomena and then followed with all of the experiments that you should do – that’s as biologically relevant as you can get.”

The next step is for the researchers to figure out exactly how the lanosterol-based eye drops are eliciting this response from the cataract proteins, and to progress their research to human trials.

Citizen Scientists Discover Yellow “Space Balls”

Citizen scientists scanning images from NASA’s Spitzer Space Telescope, an orbiting infra-red observatory, recently stumbled upon a new class of curiosities that had gone largely unrecognized before: yellow balls.

“The volunteers started chatting about the yellow balls they kept seeing in the images of our galaxy, and this brought the features to our attention,” said Grace Wolf-Chase of the Adler Planetarium in Chicago.

splash

A new ScienceCast video examines “yellow balls” and their role in star formation. Play it

The Milky Way Project is one of many “citizen scientist” projects making up the Zooniverse website, which relies on crowdsourcing to help process scientific data.  For years, volunteers have been scanning Spitzer’s images of star-forming regions—places where clouds of gas and dust are collapsing to form clusters of young stars.  Professional astronomers don’t fully understand the process of star formation; much of the underlying physics remains a mystery. Citizen scientists have been helping by looking for clues.

Before the yellow balls popped up, volunteers had already noticed green bubbles with red centers, populating a landscape of swirling gas and dust. These bubbles are the result of massive newborn stars blowing out cavities in their surroundings. When the volunteers started reporting that they were finding objects in the shape of yellow balls, the Spitzer researchers took note.

Auroras Underfoot (signup)

The rounded features captured by the telescope, of course, are not actually yellow, red, or green—they just appear that way in the infrared, color-assigned images that the telescope sends to Earth. The false colors provide a way to humans to talk about infrared wavelengths of light their eyes cannot actually see.

“With prompting by the volunteers, we analyzed the yellow balls and figured out that they are a new way to detect the early stages of massive star formation,” said Charles Kerton of Iowa State University, Ames. “The simple question of ‘Hmm, what’s that?’ led us to this discovery.”

A thorough analysis by the team led to the conclusion that the yellow balls precede the green bubbles, representing a phase of star formation that takes place before the bubbles form.

“Basically, if you wind the clock backwards from the bubbles, you get the yellow balls,” said Kerton.

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An artist’s concept shows how “yellow balls” fit into the process of star formation.

Researchers think the green bubble rims are made largely of organic molecules called polycyclic aromatic hydrocarbons (PAHs). PAHs are abundant in the dense molecular clouds where stars coalesce. Blasts of radiation and winds from newborn stars push these PAHs into a spherical shells that look like green bubbles in Spitzer’s images. The red cores of the green bubbles are made of warm dust that has not yet been pushed away from the windy stars.

How do the yellow balls fit in?

“The yellow balls are a missing link,” says Wolf-Chase. They represent a transition “between very young embryonic stars buried in dense, dusty clouds and slightly older, newborn stars blowing the bubbles.”

Essentially, the yellow balls mark places where the PAHs (green) and the dust (red) have not yet separated. The superposition of green and red makes yellow.

So far, the volunteers have identified more than 900 of these compact, yellow features.  The multitude gives researchers plenty of chances to test their hypotheses and learn more about the way stars form.

Meanwhile, citizen scientists continue to scan Spitzer’s images for new finds. Green bubbles.  Red cores.  Yellow balls.  What’s next?  You could be the one who makes the next big discovery.  To get involved, go to zooniverse.org and click on “The Milky Way Project.”

Killer seals develop a taste for shark guts

THAT shark’s fate is sealed. A seal has been spotted turning ecological roles upside-down by killing and eating blue sharks. If this turnabout proves common, ecologists might need to reassess the role of seals in marine ecosystems.

Chris Fallows, a dive-boat operator in Cape Town, South Africa, was photographing 10 blue sharks underwater when a young male Cape fur seal arrived and chased and killed five of them, eating their intestines (African Journal of Marine Science, doi.org/268).

Ordinarily, seals and blue sharks, which are roughly the same size, both prey on much smaller fish, squid and other marine life. Several species of seal also feed on smaller sharks, and blue sharks have been seen pursuing – though not catching – fur seals.

Fallows’s observations are the first time anyone has seen seals preying on such large sharks, says Hugues Benoit of the Canadian Department of Fisheries and Oceans in Moncton, New Brunswick.

Seal attack <i>(Image: Chris Fallows)</i>

Benoit suspects this behaviour is more common than anyone realises. By chowing down on their competitors, seals could alter ocean food webs in unexpected ways, he says. If seals help hold down shark populations, for example, it could boost populations of smaller fish.

If so, fisheries biologists may need to take that into account in managing fish populations.

Future ruin: Can we design our way out of eco-crisis?

One Central Park in Sydney (Image: James D. Morgan/REX)

Event: Designs of the Year 2015, Design Museum, London

In friendly competition with Percy Bysshe Shelley, the poet Horace Smith once wrote a poem entitled Ozymandias. Shelley’s version is the one we remember, but Smith’s is compelling for another reason. He imagines a hunter traipsing through the ruins of a future London. Lighting upon a fragment of a monument, he “stops to guess/What powerful but unrecorded race/Once dwelt in that annihilated place”.

This year’s Designs of the Year competition has its monumental entries, but even the most grandiloquent of the 76 nominations at least tips its hat to the idea that the world will not sustain another great ruin, or may end up our next great ruin, unless we respond more cleverly to our environment.

Jean Nouvel’s One Central Park in Sydney, Australia, towers above its architectural competitors, literally. Clad in climbing plants by Patrick Blanc, the leading designer of vertical gardens, One Central’s overriding purpose seems to be to apologise for its very existence.

There is even a motorised heliostat mounted on a cantilever near the roof, to erase the building’s shadow. The arrangement looks terrifying in photographs, suggesting the 50-metre-high moon towers of the 19th century when towns experimented with civic lighting.

Giant pot plants

In Ho Chi Minh City, a project called House for Trees eschews apology for action, albeit of a most eccentric sort. Here, high-density living units double as gigantic containers for tropical trees. Come the rains, a sufficient number of these properties could reduce the risk of urban flooding. At least, so claim architects Vo Trong Nghia, although it sounds like special pleading to me – an alibi for the strange green dream they’re weaving, of wandering lost among giant plant pots.

(Image: PITCHAfrica)

Where rains are few, a more down to earth aesthetic holds sway.PITCHAfrica’s Waterbank Campus is a 10-acre school site in Laikipia, Kenya, where 4 acres of irrigated conservation agriculture are fed by 7 low-cost buildings, designed to collect and store what little precipitation there is.

PITCHAfrica’s vision extends beyond unassuming architecture to provide resources like clean water, food and sanitation on-site for its students, in the hope they will spread the word about how to manage scarce resources at home.

This vision, of an artificial “ecosystem capable of empowering and transforming communities”, is shared by a great many of the show’s “technical fix” entries. Take the Blue Diversion toilet. This project, led by the Swiss Federal Institute of Aquatic Science and Technology, and funded by the Bill & Melinda Gates Foundation, is an all-in-one sanitation, fertiliser, drinking-water and biogas solution. In this cheap, ugly, blue plastic toilet, nothing is wasted &ndahs; not even sunlight; there’s a small solar panel on its roof.

Sticking-plaster solution

Other ideas plug in to the smog and mess of cities, and try to make daily life a little more bearable. At the University of Engineering and Technology, Lima, Peru, researchers have invented a billboard that purifies the air in a five-block radius, scrubbing it clean of construction dust and 99 per cent of airborne bacteria – it would take 1200 trees to do the equivalent work, says the team.

Another entry, The Ocean Cleanup, designed by Erwin Zwart with Boyan Slat and Jan de Sonneville, tackles the plastic garbage circulating the world’s oceans. Why not string barriers over the waves to catch the plastic as it moves around? Having raised over U$2 million through crowdfunding, the organisation plans to construct and test large-scale pilot projects.

This is technical fixery at its purest. It doesn’t prevent the oceans being littered: it is an environmental sticking plaster, permitting us to pursue business as usual. But why should designers have to carry the whole world on their shoulders? Designs like these could be part of a broader, political solution. The Ocean Cleanup’s barriers would be a fitting monument for our descendants to puzzle over.

Better, of course, to avoid collapse entirely, but it won’t be simple. It is easier for designers to ameliorate or even disguise problems, rather than to address them head on. Two projects built around the food supply demonstrate this neatly.

Failed lemons

Disclosed (Image: Alexander Gowers)

Disclosed, by Marion Ferrec at the Royal College of Art, in collaboration with Kate Wakely, is a web-based consumer service that allows you to choose products according to your health needs and ethical preferences. Lacking vast wealth, leisure and self-absorption, I won’t be using it.

But neither am I entirely persuaded by Marcel’s humorous campaign for the French supermarket giant Intermarché – a series of beautifully photographed imperfect fruits and vegetables. The idea is to shift ridiculous-looking potatoes, hideous oranges and failed lemons onto the consumer, and thereby reduce food waste. But the campaign preserves and reinforces (by price offers) the very distinction between perfect and imperfect produce that caused the problem in the first place.

It is, frankly, next to impossible to imagine how we get from a wasteful here to a sustainable there – and for that reason alone, I think Alexandra Daisy Ginsberg’s design fiction Designing for the Sixth Extinction is the poster-child of this year’s competition. Ginsberg has anatomised the ultimate disruptive enterprise, in which “nature is totally industrialized for the benefit of society”.

Although her fictional synthetic creatures are deliciously creepy (especially the “biologically-powered mobile soil bioremediation device”) it is her business model of saving our civilisation at the expense of the natural world, while replacing it with something better, that fascinates.

If Ginsberg’s vision comes to pass, our descendants won’t be able to puzzle at our monuments. Our monuments will be everywhere, all around them, and inside them.

Oceans swallowed 13 million tonnes of plastic in 2010

Vast floating islands of plastic are just a drop in the ocean compared with what’s lurking deeper down. Between 5 and 13 million tonnes of plastic debris entered the marine environment in 2010 – and most of it is under water. What’s more, without improvements in the way we manage waste, it could be 10 times as much each year by 2025.

The visible plastic is just a small proportion of what's in the oceans <i>(Image: Pascal Kobeh/Naturepl.com)</i>

It has been 40 years since the first scientific reports of plastic pollution in the ocean, but we still have plenty to learn. For instance, the combined results from 24 oceanic expeditions published late last year concluded there may beperhaps 244,000 tonnes of floating plastic out there. This is puzzling, because conservative estimates suggest something like 9 million tonnes of plastic have entered the oceans since the 1970s.

Now we know there’s even more missing plastic than that. Jenna Jambeck at the University of Georgia, Athens, and her colleagues have looked at data on plastic use and disposal in 192 coastal countries. They calculate that between 4.8 and 12.7 million tonnes entered the world’s oceans in 2010 alone. This means the amount of plastic that has entered the ocean down the years might be 1000 times more than the mass of floating plastic that scientific surveys have measured.

Surprisingly, the 10 countries with the largest problem – many of which are in south-east Asia – generally have relatively low rates of plastic waste generation per person. For instance, in China – which tops the list with an estimate of up to 3.53 million tonnes of plastic marine debris a year – the average person generates about 1.1 kilograms of waste per day of which just 11 per cent is plastic. In the US – at 20 on the list – the average person generates more than twice as much waste. But the top offending countries also have high coastal populations and low rates of plastic recycling.

It’s an interesting study, says Marcus Eriksen of the Five Gyres Institute in Los Angeles, who led last year’s floating plastic study

– but some of the assumptions used to arrive at the new calculations could be quibbled with. “I believe the authors underestimate the amount of trash that is scavenged, burned and buried before it reaches the ocean,” he says. “I think there’s much less leaving land.”

Even so, there is clearly a huge mismatch between the plastic entering the ocean and the plastic we find there. “The disturbing conclusion is that much of the plastic entering the oceans is unaccounted for,” says Carlos Duarte at the King Abdullah University of Science and Technology in Saudi Arabia, who has also helped conduct surveys into the amount of plastic in the oceans.

Plastic smog

Where is the missing plastic? Perhaps it’s hiding in plain sight. “It’s important to understand that plastic shreds rapidly into microplastics that distribute widely into the most remote waters on the planet,” says Eriksen. “Of the 5.25 trillion particles of plastic we reported recently in PLoS One, 92 per cent are less than the size of a grain of rice.”

Such small particles spread throughout the water column, says Eriksen, also finding their way into sea-floor sediments and ice cores. That means we should stop thinking of plastic waste in terms of unsightly chunks of debris floating in vast oceanic garbage patches, and instead see it more as a pervasive “plastic smog” of tiny particles spread through the entire volume of ocean water.

“It’s not sensible to go to the ocean with nets to capture trash, but rather to focus on mitigation strategies on land,” says Eriksen.

Yet the amount of plastic entering the ocean is likely to keep rising in the years to come. Jambeck and her colleagues point out that 16 of the top 20 plastic producers they identified are middle-income countries, where strong economic growth will probably result in even more plastic use, but where the infrastructure to deal with the waste is still lacking.

But the solution isn’t to burden these developing countries with the cost of building effective waste management infrastructures, says Eriksen. Instead, we should require the plastics industry to rethink the way it designs its products – in particular, the industry should phase out plastic products designed for single use.

Change the way plastic is produced, says Eriksen, “and the plastic pollution issue would largely diminish”.

Suicide accounts for more than 40,000 deaths in the US each year, making it one of the top 10 leading causes of death in the country. While psychological factors such as stress, anxiety and depression are known drivers of suicide, a new study claims to have found evidence of a more surprising risk factor: exposure to air pollution.

The researchers, including Amanda Bakian, PhD, an assistant professor of psychiatry at the University of Utah in Salt Lake City, publish their findings in The American Journal of Epidemiology.

Smog over a city

This is not the first study to find a link between air pollution and increased risk of suicide. A 2010 studypublished in The American Journal of Psychiatry found people from over seven cities in South Korea were 9% more likely to commit suicide within 2 days of a rise in air pollution.

And last year, Bakian and colleagues conducted a study that found residents of Salt Lake County were more likely to commit suicide within 3 days of being exposed to increased levels of nitrogen oxide or high concentrations of fine particulate matter (PM 2.5) – particles in smoke and haze that are 2.5 micrometers in diameter or less.

They build on these findings with their latest study, which found middle-aged individuals and men are most at risk of suicide through exposure to air pollution.

Short-term air pollution exposure ‘increased suicide risk by up to 25%’

The team analyzed the records of 1,546 people in Salt Lake County who committed suicide between 2000 and 2010.

Consistent with their previous findings, the researchers calculated that individuals who were exposed to increased levels of nitrogen dioxide were 20% more likely to commit suicide in the following 3 days, while those exposed to higher concentrations of PM 2.5 were 5% more likely to take their own lives within the next 3 days.

Men were found to have an even higher risk of suicide following air pollution exposure; after exposure to increased levels of nitrogen dioxide and PM 2.5, their risk of committing suicide in the following 3 days was 25% and 5%, respectively.

For individuals aged 36-64, the researchers found that short-term exposure to high levels of nitrogen dioxide increased the risk of suicide by 20%, while short-term exposure to high concentrations of PM 2.5 was linked to a 7% increased suicide risk.

Commenting on their findings, Bakian says:

“As suicide risk was found to differ by age and gender, this suggests that vulnerability to suicide following air pollution exposure is not uniform across Salt Lake County residents and that some Salt Lake County residents are more vulnerable than others.

Our next step is to determine in more detail exactly what elements – such as genetic and sociodemographic factors – are responsible for increasing one’s vulnerability to suicide following air pollution exposure.”

The researchers stress that their findings do not indicate that short-term exposure to air pollution is a direct cause of suicide. Instead, they suggest that increased air pollution may merge with other factors that drive suicide risk.