New research from the Harvard T.H. Chan School of Public Health explains that fossil fuel pollution could be responsible for 1 in 5 adult deaths worldwide.
Discussions around the use of fossil fuels today mostly revolve around their environmental impact, as well they should. But the life around us isn’t the only one that has to bear the costs of our reliance on such substances — their use, a new paper reports, has a human cost as well.
According to the authors, pollution generated by the burning of fossil fuels was responsible for around 8 million premature deaths in 2018, roughly 20% of all adult deaths worldwide in that year. The most heavily polluted areas saw the lion’s share of these deaths.
Burn hard die young
Half of those premature deaths were recorded in China and India, with Bangladesh, Indonesia, Japan, and the United States making up the rest. The deadly effects of fossil fuel pollution come down to the tiny particles (PM, particulate matter) generated by the burning of oil, gas, and especially coal. In around six Asian nations, such pollution accounts for over one-quarter of all mortality, the team adds.
However, that also means that lowering our use of fossil fuels, or at least finding ways to keep air quality in check, can prevent all those excess deaths.
All in all, air pollution is responsible for reducing the average lifespan by 4.1 years in China, 3.9 years in India, 3.8 years in Pakistan, and around 8 months on average in Europe. This goes to show how hard air pollution impacts Asia compared to both more developed and less developed areas. The figures reported in this paper are almost double those of previous estimates.
Previous estimates of deaths related to fossil fuel pollution were based on satellite data and surface-level observations to determine concentrations of PM2.5, the most deadly kind of particulate matter. These estimates, most recently provided by World Health Organization through the Global Burden of Disease, puts this number at around 7 million, with around 4 million of those being caused by outdoor pollution.
One limitation of these previous studies, however, is that they cannot determine the origin of the particles in question — these could come from burning fossil fuel as well as dust or wildfires. To get a better idea of their origin (and thus, how much of the problem is caused by fossil fuels) the team used GEOS-Chem, a 3-D atmospheric chemistry model, to look at the Earth’s surface in 50-by-60-kilometer (30-by-36-mile) blocks.
“Rather than rely on averages spread across large regions, we wanted to map where the pollution is and where people live,” said lead author Karn Vohra, a graduate student at the University of Birmingham.
Next, they fed in data regarding carbon emissions from several key fields, as well as NASA simulations of air circulation. After they calculated PM2.5 levels for each block, they used a novel risk assessment model to estimate how much damage these would cause public health, leading to the reported figures. Among the most common effects of air pollution, the team lists coronary heart disease and stroke (around half), followed by lung diseases and non-communicable conditions such as diabetes and high blood pressure for most of the rest.
The paper is awaiting publication in the journal Environmental Letters and is currently available on Harvard’s page.
A seemingly humble and common device, the air conditioning is in fact the result of crafty engineering. It cleverly uses the laws of physics to move heat from one place to another — out of your house, usually. But as we’ll soon see, there’s no joking around with the laws of physics. It’s a complex topic, so let’s dive in and see how we bend physics to our will for our comfort and safety by squeezing and pumping some strange chemicals around in some pipes.
Keeping things cool isn’t useful just in social situations. In fact, a lot of what we consider to be the modern way of life is only possible because we’ve learned how to make hot things cold. Between 1998 and 2017, for example, more than 166,000 people died due to heatwaves, according to the WHO. Cold conditions seem to be the deadlier overall, as one study reported that between 2011 and 2018 “hypothermia made up 27.0% of all temperature injuries, but 94.0% of all deaths”.
Temperatures can pose a threat through more than just direct exposure. Improper refrigeration of items such as food or medicine can cause them to spoil, leading to financial losses or adverse health effects. Finally, much of our technology needs to be kept within certain temperature ranges to function properly — this includes your laptop, space telescopes, and nuclear reactors.
To understand how we’ve managed to get a grip on temperature control, let’s first start with the basics.
What is ‘temperature’?
Temperature is how we measure how much thermal energy something has. It’s closely related to, but not the same thing as, the concept of heat.
Now, if you had a powerful enough microscope and looked at an object that’s heating up, you would see its molecules or atoms vibrate ever more intensely. This motion, ultimately, is thermal energy. Just like a wind chime in motion produces louder sounds the more its parts collide, an object’s particles generate more thermal energy the more they move. This type of particle activity is known as Brownian motion.
What we perceive as ‘heat’ is a transfer of this energy. Concepts of ‘hot’ and ‘cold’ are only applicable in relation to something — for example, a cup of boiling tea is hotter than a cube of ice but much colder than the sun. In order for you to perceive an object as hot or cold there needs to be some way for that energy to transfer between the object and your body. If it has less energy it will draw some away from your body, and your brain tells you it’s cold. If it gives you energy, you perceive it as hot.
In general, all bodies exchange heat with those around them (in a physical sense, even the atmosphere, the planet, or the universe are bodies) as long as they are in thermal contact. This ultimately leads to heat being more or less equally distributed in a system — hence why we have the idiom of something being “room temperature”. It’s everything in the room, from the table to the air itself, sharing the same heat energy so they will all feel about the same temperature to us.
Broadly speaking, we measure thermal energy using two units of measurement: the British thermal unit (‘Btu’ or ‘B. Th. U.’), or the French thermal unit (the ‘calorie’). They both largely function the same way, describing how much energy is needed to heat up a certain quantity of water by a certain temperature. However, they differ in how they measure these. One Btu represents the thermal energy needed to raise the temperature of one pound of pure water by one degree F. The calorie uses that most unholy of constructs instead — the metric system, — and describes how much energy you need to heat up one kilogram of pure water by one degree C.
Okay, so quick recap. Temperature is a way to measure the internal energy of a body, and that energy manifests as movements on the molecular and atomic levels. What we feel as hot and cold is a flow of this energy from one body to another. In general, all bodies that come into contact try to equalize their internal heat levels.
Doing a hot take
Given that thermal energy has a corresponding, physical representation in the movement of particles, it stands to reason that if you can make them stop, you can cool down an object. The fundamental problem with this, however, is that heat is the residual form of energy in our universe. Every other type of energy eventually will degrade into thermal energy through physical work, but we can’t run the process in reverse and turn thermal energy into another type of energy directly.
The motions associated with thermal energies are chaotic, and carry extremely low levels of energy individually — making it impossible to ‘harvest’ it to do physical work (due to entropy). This is why mechanisms like steam engines use heat (a ‘flow of thermal energy’) instead.
Now, from what we’ve seen so far, it seems that the way to cool down a glass of water is to cool down a room, and the best way to do that is to cool down the planet. Needless to say, we’re doing the exact opposite today and yet still get our chilled beverages. We have two main ways of doing this: ventilation and refrigeration.
Ventilation is the simpler approach, and we’re not the only ones to do it. In essence, ventilation relies on heat imbalances between two physical bodies to move masses of a medium (usually air or water) around. Because thermal energy is represented by molecular movements, having a current of air go over an object will lower its temperature as these vibrations are transferred to air molecules and carried away. Ventilation is how your computer keeps cool, and it is a part of how air conditioners work, as well.
The main limitation of this process is that it stops working when the object reaches the same temperature as its environment. At that point, the transfer of heat can stop altogether, or change directions from the environment to the body itself, heating it up.
This being said, a flow of air can provide a cooling effect even when the medium becomes quite hot. That’s why the breeze is soothing even on a scorching hot day, and how termite nests keep cool even in the hottest conditions.
Refrigeration is more technically challenging, but it can be used to lower an object’s temperature below that of the ambient environment. The heat removed from this object must be dumped into an area with a higher temperature, meaning energy must be expended in the process (as it creates a physical imbalance). It is this process that allows your air conditioner to hold a certain temperature, your freezer to freeze, and so on. The secret behind this process lies in manipulating another physical parameter: volume.
Squeeze for hot, relax to cool
First, you need to know that refrigeration systems need a special medium, known as the refrigerating fluid or agent, to work. This agent will physically carry heat from one part of the system to another. The requirements for a good refrigerant are a low boiling point, a relatively low density in liquid form but a high one as a gas, and that it has a high heat of vaporization (it can absorb a lot of heat before turning into a gas).
The magic happening inside a refrigeration unit hinges on changing the pressure of this fluid along the refrigeration system. At one end of the system, a component known as the compressor squeezes the agent hard, lowering its volume. This step causes it to heat up rapidly (because it holds the same amount of thermal energy but in a smaller place — more collisions happen). Although it’s becoming compressed, the fact that it’s heating up keeps this fluid in a gas state. It’s important that the process does not result in the refrigerant becoming a liquid, since liquids can’t be compressed, and this would damage the system.
As it leaves the compressor, the refrigerant is a hot vapor, at roughly 120° to 140°F (48° to 60°C).
The high-pressured fluid is then allowed to exit the compressor and naturally flows to areas of the system where pressure is lower. The next component it flows into is called the condenser or outdoor coil. Here it is allowed to cool down by passing heat off to the environment. Because the agent coming into the coil is so hot it will still naturally pass off its thermal energy even when it’s hot outside. This is why the back of your fridge is always so hot, or why air conditioning units blow a current of hot air.
The fluid is kept pressurized in this component, but it’s still too hot to turn liquid. As it exits the coil, however, it is fed through an expansion valve. This component allows it to turn into a low-pressure liquid through a process known as flashing. If you’ve ever used a can of compressed air or a fire extinguisher, you’ll know that fluids become significantly colder when the pressure drops / they increase in volume. This is the step that actually cools the fluid down enough to be useful for refrigeration.
Now a liquid, it is fed through the evaporator. This takes the shape of pipes inside the fridge, for example. Being very cold at this point, it absorbs heat, essentially draining thermal energy from the surrounding environment and starts boiling. In an air conditioner, a fan blows air over the pipes or radiator containing this liquid to pump cold air into the room.
The fluid, now back in a gas form at roughly room temperature, is pumped back into the compressor and the cycle repeats.
When we sweat, water on our skin evaporates — it increases in volume — which makes it drain thermal energy from our bodies. This cools us down and makes our environment more humid.
The evaporator works in reverse. Water condenses on these cold surfaces, meaning it cedes its own thermal energy to become a liquid. This heats the refrigerant up and makes the environment very dry. Air conditioning systems are thus also able to dehumidify air in a room or to control humidity levels.
Refrigeration works because all the individual steps — compression, condensation, and evaporation — are forced to happen in different places, which shifts thermal energy around. So whenever you’re using your air conditioner at home, know that it’s not really ‘absorbing’ heat, it’s just taking it from inside and dumping it outside. Thus, fridges, freezers, and air conditioners are a great example of the First Law of Thermodynamics, that energy cannot be created or destroyed.
But it can, with some tricky engineering, be moved somewhere else to make us all more comfortable and safe.
Higher levels of air pollution seem to be damaging to our mental health, reports a new study from the Yale School of Public Health (YSPH).
The findings are based on six years’ worth of mental health outpatient visit data from two major hospitals in Nanjing, China. Nanjing is notorious for its high levels of air pollution, even for China (which has quite a lot of air pollution in general). After comparing the number of visits with records of particulate matter in suspension in the air every day, the authors report that visits were more numerous when air quality was especially poor.
Bad air, bad mindspace
“Here, we show that particulate matter is having these more general effects, not just on symptoms but also on service use,” says Assistant Professor Sarah Lowe, Ph.D., first author of the study.
The findings, says the team, showcase why we need further investments in mental services, especially as air pollution levels around the world are getting worse. More research is needed to understand how and why air quality influences mental health, they add, but now we know that it can influence how much use specialized services see.
Air pollution is the product of many components ranging from carbon monoxide in car exhaust to sulfur dioxide particles from industrial processes. This study focused on particulate matter (PM), tiny pieces of organic materials such as liquids or soil, which are known to pose a threat to human health. The main danger they pose comes down to their size, which allows PM to enter deep into the lungs. Once there, they can cause quite a lot of damage by ripping through lung tissue and entering the bloodstream.
The team believes that these particles can influence mental health after entering the bloodstream and reaching the brain.
“These tiny particles not only have effects on the lungs, the heart and the brain,” said YSPH Assistant Professor Kai Chen, Ph.D., senior author of the paper, “but they also have effects on other organs of your body.”
Levels of PM in Nanjing exceed the safety levels specified in China’s air-quality standards for around one in five days of the year, the team notes. As such, they expected the effect it has on psychological disorders would be reflected in an uptick of mental health visits to the city’s two hospitals.
They did see such an uptick, especially prevalent among men and older residents. This unequal distribution may come down to social and behavioral differences among people in Chinese society, but that’s just a hypothesis at this time; more data is needed to tell for sure.
What they were able to say for sure, however, is that days with worse air pollution saw more demand for outpatient mental health services. Whether one causes the other is still murky. For example, days with high levels of air pollution could limit people’s choices of activities (such as outdoor sporting events becoming unbearable or being postponed), leaving people free to come to their appointments. Alternatively, more air pollution could lead to more physical symptoms such as difficulty breathing, which would coax people into seeking mental health services in order to cope.
“There could be other reasons that we simply couldn’t explore with the data we had,” Lowe explained. “We don’t know that level of detail, and I think that would be a really interesting direction for future research,” she said.
The paper “Particulate matter pollution and risk of outpatient visits for psychological diseases in Nanjing, China” has been published in the journal Environmental Research.
NASA reports that crewmen aboard the International Space Station were woken up on Monday by ground crew — to fix an air leak.
The leak has been under investigation for several weeks now, the agency notes, but the rate of air loss seemed to increase on Monday, causing ground control to intervene. Despite this, the leak is in no way an immediate danger to the lives of the crew and has since been tracked to the Zvezda (“Star”), a module on the Russian side of the ISS that houses life support equipment and quarters for two crewmembers.
“Late Monday night, the Expedition 63 crew was awakened by flight controllers to continue troubleshooting a small leak on the International Space Station that appeared to grow in size,” NASA explained in a statement on Tuesday.
“Ground analysis of the modules tested overnight have isolated the leak location to the main work area of the Zvezda Service Module.”
The crew collected readings from various locations inside the station using an ultrasonic leak detector, closing hatches between modules one by one as they went. In the end, they managed to narrow the search down to the Zvezda module.
Throughout the night on Monday, the module was kept isolated and pressure measurements were performed remotely to identify the leak’s location. By morning, the checks were complete, and the crew re-opened the hatches between the US and Russian segments of the ISS and went back to their regular, space-faring lives.
This isn’t the first time astronauts aboard the ISS needed to contend with a leak. Back in 2018, a 2mm drill hole was discovered in the Russian Soyuz craft while it was docked to the station. This hole was patched with epoxy resin and tape. The cause, and whether this hole was caused by accident or with intent, has yet to be determined.
The current leak was likely caused by a mechanical or manufacturing defect.
“The size of the leak identified overnight has since been attributed to a temporary temperature change aboard the station with the overall rate of leak remaining unchanged,” NASA explains.
With the world getting hotter, finding energy-efficient ways to cool down is more important than ever. A team of researchers from the University of British Columbia, Princeton University, the University of California, Berkeley and the Singapore-ETH Centre plan to help us do just that with the ‘Cool Tube’.
Air conditioning can be a blessing in the hot summer months, but they also consume a lot of power. Added up on a city- or country-wide scale this translates to a huge drain on our grids and vast quantities of CO2 emissions. Air conditioning can also contribute to respiratory complications by keeping germs in suspension in the air (by keeping it in constant motion).
The team behind Cold Tube wanted to change how we manage our personal temperature during such times, and their approach doesn’t involve cooling or moving air at all.
Cool cooling ideas
“Air conditioners work by cooling down and dehumidifying the air around us—an expensive and not particularly environmentally friendly proposition,” explains co-lead author Adam Rysanek, assistant professor of environmental systems at UBC’s school of architecture and landscape architecture.
“The Cold Tube works by absorbing the heat directly emitted by radiation from a person without having to cool the air passing over their skin. This achieves a significant amount of energy savings.”
The system consists of a series of rectangular panels that can be fitted to walls or ceilings. These elements are kept cool by chilled water being circulated through them.
The idea behind the Cold Tube is that heat naturally radiates from hot surfaces to colder ones — that’s how heat from the Sun makes it to Earth. When you sit under or near one of these elements, your body heat will radiate towards it. The team describes this effect as similar to the sensation of cold air flowing over your body, even when ambient temperatures are high.
It’s not a new concept — in fact, it’s been in use in industrial settings for several decades now. What Cold Tube does differently, however, is to use a special coating that does away with the need to dehumidify air.
Humidity in the air condenses on cold surfaces, which can cause hygiene issues and damage surfaces and materials. The team developed an airtight, water-repellent membrane that encases their panels, and prevents condensation from forming (but still allows the system to function as intended).
The researchers tested their system in an outdoor setting in Singapore last year. The temperature outside during the test was 30 degrees Celsius (86 degrees Fahrenheit) on average. Yet, participants reported feeling ‘cool’ and ‘comfortable’ despite the heat, and the panels remained dry throughout the day.
“Because the Cold Tube can make people feel cool without dehumidifying the air around them, we can look towards shaving off up to 50 percent of typical air conditioning energy consumption in applicable spaces,” said Eric Teitelbaum, a senior engineer who oversaw the demonstration project while working at the Singapore-ETH Centre.
“This design is ready. It can obviously be used in many outdoor spaces—think open-air summer fairs, concerts, bus stops, and public markets. But the mission is to adapt the design for indoor spaces that would typically use central air conditioning.”
The system doesn’t rely on cooling air, like a traditional air conditioner, so it can even be used with an open window, or in open spaces. The team hopes that its low operating cost will make the Cold Tube an attractive option for both developed and developing countries. A commercially viable version of the system is expected for 2022.
The paper “Membrane-assisted radiant cooling for expanding thermal comfort zones globally without air conditioning” has been published in the journal PNAS.
We know that the speed of light seems to be the upper limit for how fast something can travel in the universe. But there’s a much lower speed limit that we’ve only recently (in the grand scheme of things) managed to overcome here on Earth: the speed of sound.
You’ve heard the term before, and you might even know its exact value or, more accurately, values.
But why exactly does sound have a ‘speed’? Is it the same everywhere? And what happens if you go over the limit? Well, one thing is for sure — sound won’t give you a fine for it. It will cause a mighty boom to mark the occasion, though, because going over the speed of sound isn’t an easy thing to pull off.
In Earth’s atmosphere, sound can travel at around 345 meters per second. Let’s take a look at why this limit exists, what says it should be this way, and just why things go boom when you blast through it. But first, let’s start at with the basics:
What is a sound wave
What we perceive as sound is actually motion. Sound is, fundamentally, a movement or vibration of particles, most commonly those in the atmosphere, where we do most of our talking and sound-making.
In very broad lines, any object in motion will come into contact with the particles in their environment. Let’s take talking as an example. When someone speaks, their lungs collide with and push out air that their vocal cords modulate to create certain sounds. This will push the air in their immediate vicinity, which will make its molecules collide with air molecules farther away, and so on, until the motion reaches the air particles next to you. They will then collide with your eardrums, which ‘translates’ it into the sensation of sound.
So from a physical point of view, sound behaves quite like waves do on a beach. Its volume is directed by how high the wave goes (amplitude) and its pitch is formed by how often these waves hit the shore (frequency). The farther a wave travels, the less energy it has (so the less pressure it can exert on new particles), which is why eventually sound dies out and we can’t hear something halfway around the world. More on sounds here.
The speed of sound is essentially the speed that these ‘acoustic waves’ can travel at through a substance. Leading us neatly to the role these substances (called “the medium”) play here.
Not all things are equal
The source of sound only plays a limited part in its propagation. Sound propagation is almost entirely dependent on the medium.
First off, this means that sound can’t propagate through void, as there is nothing to carry it. One handy example is that in space, nobody can hear you scream; but if you place your visor on another’s astronaut’s visor, they will. Secondly, a medium can’t carry sound unless it has some elasticity, although this is more of an academic point as every material is elastic to some degree. The corollary of this is that the more elastic our medium, the faster sound will travel through it.
Elasticity is the product of two traits: the ability to resist deformation (its ‘elastic modulus’ or rigidity) and how much you can alter it before it stops coming back to its original shape (its ‘elastic limit’ or flexibility). Steel and rubber are both very elastic, but the former is rigid while the later is flexible.
Density has a bit of a more complicated relationship to the speed of sound. Density is basically a measure of how much matter there is in a given space. On the one hand closely-packed, lightweight particles allow for higher speeds of sound as there’s less empty space they need to travel over to hit their neighbors. But if these particles are heavy and more spread apart, they will slow the sound down (as big, heavy particles are harder to move). Sound will also attenuate faster through this last type of material. In general, elastic properties tend to have more of an impact on the speed of sound than density.
A basic example involves hydrogen, oxygen, and iron. Hydrogen and oxygen have nearly the same elastic properties, but hydrogen is much less dense than oxygen. The speed of sound through hydrogen is 1,270 meters per second, but only 326 m/s through oxygen. Iron, although much denser than either of them, is also much more elastic. Sound traveling through an iron bar can reach up to 5,120 m/s.
One other thing to note here is that fluids only carry sound as compression waves (particles bumping into each other in the direction the wave is propagating. Solids carry it both as compression and shear waves (perpendicular to the direction of propagation). This is due to the fact that you can’t cut fluids with a knife (they have a shear modulus of 0). A fluid’s molecules can move too freely from one another for such motions to create such waves.
So far we’ve seen that sound has a maximum speed it can travel at, based on which material it is propagating through. By ‘travelling’, we mean particles bumping into their neighbors creating wave-like areas of pressure.
So what happens when something moves faster than the speed these particles can reach? Well, you get a sonic boom, of course.
Despite the name, sonic booms are more like sonic yelling. When an object is moving faster than sound can travel in its environment, it generates a thunder-like sound. Depending on how far away the source is, this boom is strong enough to damage structures and break windows.
An airplane moving faster than the speed of sound will compress the air in front of it, as this air can only move at the speed of sound. It can’t physically get out of the way fast enough. Eventually, all this compressed, moving air (which is, in essence, sound) is blasted away from the aircraft’s nose at Mach 1 (the speed of sound through air). If anyone is close enough to be reached by this blast of ultra-pressurized air, they hear the sonic boom.
Although it is perceived as an extremely loud burst of sound by a static observer, the sonic boom is a continuous phenomenon. As long as an object moves faster than sound, it will keep creating this area of ultra-compressed air, and leave a continuous boom in its wake. One nifty fact about sonic booms is that you can’t hear them coming — they move faster than sound, so you can only hear them after they’ve passed you.
Humans have only recently gone above the speed of sound, with the first supersonic flight recorded in 1947. Since then, such flights have been banned above dry land in the US and EU, in order to protect people and property (although they can still be carried out with proper authorization). Faster-than-sound travel, however, is still an alluring goal. One way to allow for supersonic speeds without blasting all the windows in the neighborhood is to travel through a vacuum or low-pressure air — a cornerstone idea of the Hyperloop.
Researchers are uncovering further evidence of the adverse health effects of air pollution.
Toxic metallic nanoparticles from such pollution can find their way into the mitochondria of our hearts, a new paper reports, with a negative impact on our health. Mitochondria provide the power that keeps our cells going; damaging them will thus damage our cells.
This effect was seen in the hearts of people living in polluted cities and could be an important cause of cardiac stress, the team adds.
Poor air, poor health
“It’s been known for a long time that people with high exposure to particulate air pollution experience increased levels and severity of heart disease,” says Professor Barbara Maher of Lancaster University, lead author of the paper. “We found these metal particles inside the heart of even a three-year-old.”
“It’s really urgent to reduce emissions of ultrafine particles from our vehicles and from industry before we give heart disease to the next generation, too,” she adds.
The team analyzed the hearts retrieved from two young people who had died in accidents and lived in the Mexico City area. Air pollution levels here often exceed health guidelines, the authors explain.
They found metallic nanoparticles associated with air pollution (such as iron and titanium-rich particles) inside damaged heart cells of a 26- and 3-year-old, randomly selected from 63 previously-investigated children and young adults.
Using high-resolution transmission electron microscopy and X-ray analysis, they found that mitochondria containing iron-rich nanoparticles were damaged, showing ruptured membranes or deformities. Such particles were associated with the development of heart disease, as they cause oxidative stress which chemically damages cells, even in very young tissues.
The team found “abundant presence of rounded, electron-dense nanoparticles, mostly ~15–40 nanometers, most frequently inside mitochondria”. They note that the presence of iron inside mitochondria can alter their chemical mechanism to produce highly reactant oxygen species which attack proteins.
The particles are “indistinguishable from the iron-rich nanoparticles so abundant and pervasive in urban and roadside air pollution”, the team notes.
The results show that such nanoparticles may jump-start heart disease in early life and cardiovascular illness later on. Air pollution can thus be responsible for the international “silent epidemic” of heart disease. It could also contribute to the high death rates from COVID-19 seen in areas with poor air quality.
Another point of concern is the magnetic properties of these particles. It’s possible that, should they build-up in the heart in large amounts, these will react to the magnetic fields produced by appliances and electronics. Exposure could cause cell damage and lead to heart dysfunction. People who work jobs that expose them to magnetic fields, such as welders or certain branches of engineering, could also be at risk.
The paper “Iron-rich air pollution nanoparticles: An unrecognized environmental risk factor for myocardial mitochondrial dysfunction and cardiac oxidative stress” has been published in the journal Environmental Research.
Some microbes can not only survive but also replicate in an atmosphere comprised entirely out of hydrogen. These important findings suggest that life might appear in a variety of extraplanetary environments that scientists previously discounted.
Life never ceases to surprise us
Billions of years ago, Earth had very small amounts of hydrogen in its primordial atmosphere, up to about 0.1%. The molecular hydrogen persisted in the atmosphere for hundreds of millions of years up to the Great Oxidation Event.
Today, what little hydrogen is produced is rapidly consumed by microorganisms, oxidized in the atmosphere, or lost to space.
Astrophysicists believe that many rocky exoplanets, super-Earth exoplanets (an extrasolar planet with a mass higher than Earth’s, but substantially below those of the Solar System’s ice giants), and even rogue rocky planets (planets outside a solar system) may have a hydrogen-abundant atmosphere under certain conditions.
Some examples of such planets include Trappist-1 d, e, f and g, and LHS 1132b.
Seeing as it seems likely that there are some hydrogen-dominated atmospheres beyond our solar system, and considering that such rocky planets are easier to detect than those with nitrogen or CO2-dominated atmospheres, researchers at MIT wanted to investigate the viability of life on such planets.
The research team conducted growth experiments in a bioreactor system on two species of microorganisms: Escherichia coli and the yeast Saccharomyces cerevisiae.
“We note that we chose a 100% H2 gas environment as a control. Actual atmospheres dominated by H2 will always have other gas components that are products of planetary geology or atmospheric photochemistry. Furthermore, rocky planets will have to be colder than Earth, have a more massive surface gravity than Earth and/or a replenishment mechanism to maintain an H2-dominated atmosphere,” the authors wrote in their study.
Remarkably, both organisms could reproduce normally in a 100% hydrogen atmosphere. However, they do so at slower rates than in oxygenated air.
E. coli reproduced two times slower, while the yeast was around 2.5 orders of magnitude slower. The authors argue that the lack of oxygen is responsible for the reduced rate of replication.
E. coli also synthesizes an impressive number of volatile molecules that can be detected on worlds light-years away from Earth.
“That such a simple organism as E. coli—and a single species at that—has a diverse enough metabolic machinery capable of producing a range of gases with useful spectral features is very promising for biosignature gas detection on exoplanets. While most of the gases are produced in small quantities on Earth there are exoplanet environments where the gases if produced in larger quantities could build up,” the authors wrote in their paper published today in the journal Nature Astronomy.
Trees and other plants can help slash pollution near factories and other sources by an average of 27%, a new study suggests.
Planting trees tends to be cheaper than implementing new technology. And, according to a new paper, they can be of great help in our efforts to curtail air pollution. The study shows that plants are a cheap but effective alternative to cleaning the air around industrial sites, roadways, powerplants, or drilling sites.
Plant a tree, get fresh air free
“The fact is that traditionally, especially as engineers, we don’t think about nature; we just focus on putting technology into everything,” said Bhavik Bakshi, lead author of the study and professor of chemical and biomolecular engineering at The Ohio State University.
“And so, one key finding is that we need to start looking at nature and learning from it and respecting it. There are win-win opportunities if we do — opportunities that are potentially cheaper and better environmentally.”
For the study, the team collected public data on air pollution and vegetation, on a county-by-county basis, for the continental 48 states. They analyzed the effect trees and other plants have on air pollution levels and then calculated the costs of adding extra plants and trees. In effect, they checked to see how able current vegetation levels are at mitigating air pollution, and then estimated the effect of increased plant presence on air pollution.
The team reports that for 75% of the counties that were included in this analysis, it was cheaper to use plants to mitigate air pollution instead of technological solutions (smokestack scrubbers for powerplants, for example). In several cases, the team explains that plants may actually be the better choice when combating pollution.
There is one area where the team found technology to be superior to plants at cleaning air pollution — industrial boilers. In the manufacturing industry, both ecosystem upgrades and technological solutions can perform the task, and both offer up cost-saving opportunities. However, because this sector is so broad and varied, it’s hard to find a one-size-fits-all solution. They should be implemented on a case-by-case basis while taking account of the particularities of each situation.
They found that adding trees or other plants could lower air pollution levels in both urban and rural areas as well, though the success rates varied depending on, among other factors, how much land was available to grow new plants and the current air quality.
“[The findings] suggest that even though vegetation cannot fully negate the impact of emissions at all times, policies encouraging ecosystems as control measures in addition to technological solutions may promote large investments in ecological restoration and provide several societal benefits.”
All in all, they estimate that restoring vegetation “to county-level average canopy cover” can reduce air pollution by an average of 27% across the investigated counties. The figure varies by county and region — for example, a county in Nevada would have a lower plant cover than a same country in Ohio, because the desert can support less vegetation. The analysis didn’t include ozone pollution because data on ozone emissions is lacking, the team explains. Furthermore, they didn’t consider whether certain species are better at cleaning air pollution, although Bakshi said it’s likely that the local species will have an effect on air quality.
“The thing that we are interested in is basically making sure that engineering contributes positively to sustainable development,” Bakshi said. “And one big reason why engineering has not done that is because engineering has kept nature outside of its system boundary.”
The paper “Nature-Based Solutions Can Compete with Technology for Mitigating Air Emissions Across the United States” has been published in the journal Environmental Science & Technology.
New research at Purdue University measures how much pollution in your office or home is due to you.
We influence our surroundings just by virtue of being alive — we take oxygen and pump out CO2, our skin sheds, our hairs fall out, our heat dissipates out. Factor in elements like deodorant, and we have a surprisingly significant effect on the areas we spend our time in, such as an office or home. But, to find out just how large this influence is, a team of engineers at Purdue University has been conducting one of the largest studies of its kind in the office spaces of a building rigged with thousands of sensors.
The house of noses
“If we want to provide better air quality for office workers to improve their productivity, it is important to first understand what’s in the air and what factors influence the emissions and removal of pollutants,” said Brandon Boor, an assistant professor of civil engineering with a courtesy appointment in environmental and ecological engineering.
The present study is the largest of its kind to date. The team used an office space rigged with thousands of sensors to identify all types of indoor air contaminants and recommend ways to control them through adjusting a building’s design and operation. The building is called the Living Labs at Purdue’s Ray W. Herrick Laboratories and uses an array of sensors to monitor the flow of indoor and outdoor air through the ventilation system over four open-plan office spaces. The team further added temperature sensors (embedded in each desk chair) to keep track of people’s activities throughout the day.
People and ventilation systems have shown the greatest impact on the chemistry of indoor air in such environments, they explain. This chemistry is dynamic and “changes throughout the day based on outdoor conditions, how the ventilation system operates and occupancy patterns in the office,” Boor said.
In collaboration with researchers at RJ Lee Group, Boor developed an instrument called a proton transfer reaction time-of-flight mass spectrometer — a mechanical ‘nose’. Using this device, they recorded levels of volatile compounds in human breath, such as isoprene, in real-time.
These compounds linger in the office even after people have left the room. They also see greater build-ups when a larger number of people uses the same room.
“Our preliminary results suggest that people are the dominant source of volatile organic compounds in a modern office environment,” Boor said. “We found levels of many compounds to be 10 to 20 times higher indoors than outdoors. If an office space is not properly ventilated, these volatile compounds may adversely affect worker health and productivity.”
Ozone (considered an outdoor pollutant) breaks down inside office areas as it interacts with indoor compounds and furnished surfaces. The team adds that ozone and compounds called monoterpenes (these are aromatic compounds, such as those released by peeling an orange) break down into particles as small as one-billionth of a meter. At such a tiny size, they could be toxic as they can get into — and clog — pulmonary alveoli, the sacs in the lungs where blood-atmosphere gas exchange takes place.
Chemicals emitted from self-care products such as deodorant, makeup, and hair spray may elevate pollution levels outdoors as they are vented outside by the ventilation system, the team adds.
The team will present its initial findings at the 2019 American Association for Aerosol Research Conference in Portland, Oregon, on Thursday 16th, as the poster “Spatiotemporal Mapping of Ultrafine Particles in Buildings with Low-Cost Sensing Networks”.
Air pollution is driving up the number of cases of emphysema, a condition in which destruction of lung tissue leads to wheezing, coughing and shortness of breath.
Image via Pixabay.
Dirty air just isn’t that good for you. New research led by the University of Washington, Columbia University, and the University at Buffalo comes to report on a new way that air pollution impacts your lungs. The study shows that long-term exposure to all major air pollutants — especially ozone pollution, which is increasing with climate change — is linked with higher incidence of emphysema, a condition in which destruction of lung tissue leads to wheezing, coughing and shortness of breath.
As bad as smoking
“We were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans, in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema,” said the study’s senior co-author, Dr. Joel Kaufman, UW professor of environmental and occupational health sciences and epidemiology in the School of Public Health.
Living in an area with 3 parts per billion (ppb) higher ambient ozone levels for 10 years is roughly the equivalent of smoking a pack of cigarettes a day for 29 years, the team found, and is associated with the increase in emphysema. They also determined that ozone levels in some major U.S. cities are increasing by 3 ppb due in part to climate change. The annual averages of ozone levels in study areas were between about 10 and 25 ppb.
The findings are based on data from the Multi-Ethnic Study of Atherosclerosis (MESA) Air and Lung studies, an 18-year-long research effort that involved over 7,000 people, detailing the types and levels of air pollution they encountered between 2000 and 2018 in six metropolitan regions across the U.S.: Chicago, Winston-Salem, N.C., Baltimore, Los Angeles, St. Paul, Minnesota, and New York.
The team assessed the levels of air pollution participants encountered by collecting detailed measurements of exposure over several years in the six metropolitan regions. They also took measurements at the homes of many of the participants.
While most of the airborne pollutants are in decline due to successful efforts to reduce them, ozone has been increasing, the team reports. Ground-level ozone is mostly produced when ultraviolet light reacts with pollutants from fossil fuels.
Emphysema levels were measured from over 15,000 CT (computer tomography) scans that identify holes in the small air sacs of the participants’ lungs and lung function tests, which measure the speed and amount of air breathed in and out.
“Rates of chronic lung disease in this country are going up and increasingly it is recognized that this disease occurs in nonsmokers,” said Kaufman, also a professor of internal medicine and a physician at UW School of Medicine.
“We really need to understand what’s causing chronic lung disease, and it appears that air pollution exposures that are common and hard to avoid might be a major contributor.”
The findings are especially important, the team writes, as ground-level ozone levels are rising. The level of emphysema seen on the CT scans “predicts hospitalization from and deaths due to chronic lung disease,” said Dr. R. Graham Barr, professor of medicine and epidemiology at Columbia University who led the MESA Lung study and is a senior author of the paper.
All in all, it’s important that we continue efforts to scrub away air pollution from our homes and cities. At the same time, the authors say we need a better understanding of the ways air pollution impact our lungs, and more research into how we can prevent the diseases it causes.
The paper “Association Between Long-term Exposure to Ambient Air Pollution and Change in Quantitatively Assessed Emphysema and Lung Function” has been published in the journal JAMA.
Climate heating will, unexpectedly, make your flights much bumpier in the future.
Image via Pixabay.
Researchers at the University of Reading report that the jet stream is becoming more turbulent in the upper atmosphere over the North Atlantic. Since satellites began observing it in 1979, they explain, jet stream shearing has increased by 15%.
Jet, streamed, sheared
“Over the last four decades, temperatures have risen most rapidly over the Arctic, whilst in the stratosphere — around 12 km above the surface — they have cooled,” says lead author Simon Lee, Ph.D. student in Meteorology at the University of Reading.
“This has created a tug-of-war effect, where surface temperature changes act to slow the jet down, while temperature changes higher up act to speed it up.”
Wind shear is the variation in wind velocity at right angles to the wind’s direction. It sounds pretty complex but, in essence, wind shearing is when bodies of air move perpendicular to the direction the wind is blowing, and generate a turning force.
Vertical wind shearing, the increase in wind speed at higher altitudes, is particularly dangerous as it createsclear-air (invisible) turbulence, potentially with enough force to throw passengers out of their seats.
Tens of thousands of planes encounter severe turbulence every year, causing hundreds of injuries — both from passengers and flight attendants. Overall, the estimated cost of clear-air turbulence for the global aviation sector is estimated to be around a billion dollars annually, through a combination of flight delays, injuries to cabin crew and passengers, and structural damage to aircraft.
The new study is the first one to show that, while man-made climate heating is closing the temperature difference gap between Earth’s poles and the equator at ground level, the opposite is happening at around 34,000 feet, a typical airplane cruising altitude.
Thejet stream, like all wind, is powered by these differences in temperature. Growing differences in high-altitude temperatures are strengthening the stream, driving an increase in turbulence-generating wind shear at cruising altitudes that has gone unnoticed up until now, the team reports. They also add that their findings support previous research at Reading indicating that human-induced climate change will make severe turbulence up to three times more common by 2050-80.
“Our study shows these opposing effects currently balance out, meaning the speed of the jet stream has not changed. However, we looked for the first time at the wind shear, where significant change has previously gone unnoticed,” Lee explains.
“This strengthens previous projections for increased clear-air turbulence, as we can see an increase in one of the driving forces has happened already.
He explains that the upper-level element of that “tug-of-war” mentioned earlier will eventually win out, and that the jet stream will accelerate. “This has serious implications for airlines, as passengers and crew would face a bigger risk of injury,” Lee adds. It’s also likely that this change in the jet stream will increase flight times from Europe towards the US and speed up flights in the other direction.
The study’s lead researcher, Professor Paul Williams from the University of Reading’s Department of Meteorology, first linked increased turbulence to climate change. Prof. Williams is currently collaborating with the aircraft industry to design the next generation of planes — one that is better fit for a warmer and bumpier airspace.
The paper “Increased shear in the North Atlantic upper-level jet stream over the past four decades” has been published in the journal Nature.
Cleaning up pollution won’t make climate change worse, according to new research.
Image via Pixabay.
A new study from the University of Reading comes to put to rest the concerns that reducing air pollution could amplify climate heating. This concern stems from the fact that pollution particles help clouds form water droplets (which makes the clouds thicker) so they reflect more incoming sunlight and drive temperatures down. While this mechanism is definitely valid, the team reports, pollution also causes several types of clouds to grow thinner, allowing more sunlight to pass through.
All in all, the authors conclude, pollution is unlikely to offset more than half the warming caused by greenhouse gases.
“Until now, it was assumed that thicker clouds form when water droplets condense around the particles in polluted air, delaying rainfall, and allowing clouds to reflect more sunlight back into space,” says Velle Toll, lead author of the study. “To test this, we studied satellite data from clouds near sources of pollution.”
The extent to which air pollution helps cool the Earth down wasn’t reliably known up to now. If this cooling is strong, then removing it would amplify climate heating; however, if its cooling effect is negligible, then clearing pollutants out of the air would be a net win for humanity at large.
The present study comes to address this lack in our understanding. The authors showed that air pollution affects different clouds in different ways, causing some to grow thicker while thinning others out. The findings suggest that current plans to curb global warming by moving to cleaner sources of energy may still work without leading to an unexpected extra source of heating.
“There was little change in average water content across all the polluted clouds we found, showing that pollution makes little difference overall to many types of clouds. Some clouds got thicker, but other areas thinned out,” Toll explains.
“This reduces a big area of uncertainty for future forecasts of the climate. Our study provides more evidence that cutting emissions of greenhouse gases and air pollution is a win-win situation for the health of people’s lungs and for preventing the worst impacts of climate change.”
For the study, the team looked at near-infrared satellite images of clouds formed across the world over areas with significant air pollution levels. Clouds that are affected by said pollution look ‘brighter’ in these images, which allowed the team to pinpoint them exactly.
Hundreds of such clouds, produced by tiny pollution particles from sources such as volcanoes, cities, ships, factories, and wildfires were included in the analysis. The researchers then compared the changes caused by pollution in these clouds to ones simulated by climate models, to see how reliable our predictions of future climates are.
All in all, they report, air pollution could offset just half of the warming caused by greenhouse gases at best. In other words, we’d get at least two times as much cooling if we scrubbed the atmosphere of both pollution and greenhouse gases — not to mention massive benefits to our health, asvirtually every person on Earthis exposed to ‘unsafe’ levels of air pollution.
“Our study provides assurances that polluted air has a limited ability to prevent the atmosphere from heating up, in addition to being bad for people’s health,” says Dr. Nicolas Bellouin, study co-author and a Working Group I lead author in the IPCC’s 6th Assessment Report.
“There is now one less excuse for us not to cut emissions of both air pollution and greenhouse gases, or we will continue to see temperature rises that put people and the natural world in danger. In any case, a small temperature rise resulting from cutting pollution is a price very much worth paying to prevent greater, long-term harm caused by greenhouse gases.”
The paper “Weak average liquid-cloud-water response to anthropogenic aerosols” has been published in the journal Nature.
New research shows how well-meaning environmental measures can backfire if they don’t take into account the wider picture.
Image credits Natalya Kollegova.
A new groundwater conservation policy in northwestern India is increasing air pollution in the already haze- and smog-filled area, new research reports. The problem is caused by how water-use policies require farmers to shift rice crops to later in the year, which in turn delays the harvests and results in the burning of agricultural residue in November — a month when breezes stagnate, leading to increased air pollution.
“This analysis shows that we need to think about sustainable agriculture from a systems perspective, because it’s not a single objective we’re managing for — it’s multidimensional, and solving one problem in isolation can exacerbate others,” said Andrew McDonald, associate professor of soil and crop sciences at the Cornell University, and a co-author of the paper.
India has quite a water problem. Being a (generally) pretty dry place, agriculture here relies heavily on groundwater resources — and they’re being rapidly depleted. First, authorities tried to convince farmers to plant less water-intensive crops than rice, but this failed due to a number of reasons (such as free electricity for irrigation, assured output markets, and minimum support price
guarantees for rice). So in March 2009, the government passed The Punjab Preservation of Subsoil Water Act and the Haryana Preservation of Subsoil Water Act, legislation that forced farmers to delay rice transplanting (basically rice sowing) after the onset of the monsoon season on June 10; this was later adjusted to after the 20th of June.
So far, so good — the team notes that these groundwater acts helped “significantly reduce” groundwater depletion in northwestern India. However, they’ve also inadvertently helped increase air pollution levels. The team analyzed their effect on the timing of farmers’ planting and harvesting crops, and burning crop residues. They also connected this information with meteorological and air pollution data.
The team explains that residue burning patterns shifted following the groundwater acts, declining within October but significantly increasing in the first three weeks of November. “With the advent of combine harvesting in the 1980s, [on-field] burning of rice residues became the method of choice for accelerating the turn-around time between crops to ensure timely wheat planting and maintenance of yield potential,” the team explains. The sowing date imposed by the groundwater acts leaves farmers very little time to clear out reside apart from burning before the wheat season begins.
“Before the acts, maximum occurrence was on 24 October at 490 fires per day. After implementation of the acts, this increased to 681 fires per day, peaking around 4 November,” they add.
“Groundwater act implementation is associated with a concentration of crop residue burning into a narrower window, later in the season, and with a peak intensity that is 39% higher.”
The team further notes that this date coincides with weaker winds compared to October, which favors the build-up of air pollution. Daily PM2.5 (atmospheric particulate matter with a diameter under 2.5 micrometers) in November rose 29% after the groundwater acts.
On one hand, northwest India needs to tackle groundwater depletion. On the other hand, air pollution claimed the lives of almost 1.1 million Indians in 2015, and costs 3% of the country’s gross domestic product, according to the study. The team suggests technology that would allow farmers to plant new seeds without burning rice residue as a possible solution. Alternatively, they recommend the use of shorter-duration rice varieties that offer flexibility in planting and harvesting dates.
The paper “Tradeoffs between groundwater conservation and air pollution from agricultural fires in northwest India” has been published in the journal Nature Sustainability.
Cool down your home and the climate at the same time.
Image credits Sławomir Kowalewski.
New research from the Karlsruhe Institute of Technology and the University of Toronto wants to put your air conditioning unit to work on fighting climate change. The idea is to outfit air conditioners — devices which move huge amounts of air per day — with carbon-capture technology and electrolyzers, which would turn the gas into fuel.
“Carbon capture equipment could come from a Swiss ‘direct air capture’ company called Climeworks, and the electrolyzers to convert carbon dioxide and water into hydrogen are available from Siemens, Hydrogenics or other companies,” said paper co-author Geoffrey Ozin for Scientific American.
Air-conditioner units are very energy-thirsty. As most of our energy today is derived from fossil fuels, this means that air conditioners can be linked to a sizeable quantity of greenhouse emissions. It’s estimated that, by the end of the century, we’ll be using enough energy on air conditioning to push the average global temperature up by half a degree. Which is pretty ironic.
The team’s idea is pretty simple — what if heating, ventilation, and air conditioning (or HVAC) systems could act as carbon sinks, instead of being net carbon contributors? Carbon-capture devices need to be able to move and process massive quantities of air in order to be effective. HVAC systems already do this, being able to move the entire volume of air in an average office building five to ten times every hour. So they’re ideally suited for one another. The authors propose “retrofitting air conditioning units as integrated, scalable, and renewable-powered devices capable of decentralized CO2 conversion and energy democratization.”
“It would be not that difficult technically to add a CO2 capture functionality to an A/C system,” the authors write, “and an integrated A/C-DAC unit is expected to show favourable economics.”
Modular attachments could be used to add CO2-scrubbing filters to pre-existing HVAC systems. After collection, that CO2 can be mixed with water to make, basically, fossil fuels. As Ozin told Scientific American, the required technology is commercially available today.
But, in order to see if it would also be effective, the team used a large office tower in Frankfurt, Germany, as a case study. HVAC systems installed on this building could capture enough CO2 to produce around 600,000 gallons of fuel in a year. They further estimate that installing similar systems on all the city’s buildings could generate in excess of 120 million gallons of (quite wittily-named) “crowd oil” per year.
“Renewable oil wells, a distributed social technology whereby people in homes, offices, and commercial buildings all around the world collectively harvest renewable electricity and heat and use air conditioning and ventilation systems to capture CO2 and H2O from ambient air, by chemical processes, into renewable synthetic oil — crowd oil — substituting for non-renewable fossil-based oil — a step towards a circular CO2 economy.”
Such an approach would still take a lot of work and polish before it could be implemented on any large scale. Among some of the problems is that it would, in effect, turn any HVAC-equipped system into a small, flammable oil refinery. The idea also drew criticism as it could potentially distract people from the actual goal — reducing emission levels.
“The preliminary analysis […] demonstrates the potential of capturing CO2 from air conditioning systems in buildings, for making a substantial amount of liquid hydrocarbon fuel,” the paper reads.
“While the analysis considers the CO2 reduction potential, carbon efficiency and overall energy efficiency, it does not touch on spatial, or economic metrics for the requisite systems. These have to be obtained from a full techno-economic and life cycle analysis of the entire system.”
The paper “Crowd oil not crude oil” has been published in the journal Nature Communications.
Traffic-associated pollution leads to roughly 4 million cases of asthma in children worldwide each year, a new study reports.
Image via Pixabay.
The team looked at 125 cities around the world, keeping track of the nitrogen oxide (NO2) levels in their air, and how it related to new pediatric cases of asthma. The study, based on data from 2010 to 2015, estimates that 4 million children worldwide develop asthma each year due to NO2, with 64% of these new cases occurring in urban areas.
The gas accounted for anywhere between 6% (Orlu, Nigeria) to 48% (Shanghai, China) of these cases, the authors report. Overall, NO2’s contribution to new cases of pediatric asthma exceeded 20% in 92 cities, they add, in both developed and emerging economies.
“Our findings suggest that millions of new cases of pediatric asthma could be prevented in cities around the world by reducing air pollution,” said Susan C. Anenberg, PhD, an associate professor of environmental and occupational health at Milken Institute SPH, and the study’s senior author.
“Improving access to cleaner forms of transportation, like electrified public transport and active commuting by cycling and walking, would not only bring down NO2 levels, but would also reduce asthma, enhance physical fitness, and cut greenhouse gas emissions.”
Asthma is a chronic disease that involves inflammation of the lung’s airways, making it hard (sometimes impossible) to breathe. It is estimated that 235 million people worldwide currently have asthma, varying in intensity from wheezing to life-threatening attacks. This study is the first to take a look at how traffic-related nitrogen dioxide fits into the asthma picture. The work relied on a method that takes into account high exposures to NO2 that occur near busy roads, Anenberg explains.
For the study, the team linked together global datasets of NO2 concentrations, population distributions, and asthma incidence rates with epidemiological evidence relating traffic-derived NO2 pollution with asthma development in kids. This wealth of data allowed the team to estimate how many new cases of pediatric asthma are attributable to NO2 pollution in the 194 countries and 125 major cities they studied.
Here are some key takeaways:
Roughly 4 million children developed asthma, each year, from 2010 to 2015 due to NO2 pollution (primarily from motor vehicle exhaust).
NO2 accounted for between 6% to 48% of pediatric asthma incidence. Its contribution exceeded 20% in 92 cities located in developed and emerging economies.
The ten highest NO2 contributions were estimated for eight cities in China (37 to 48% of pediatric asthma incidence) followed by Moscow, Russia and Seoul, South Korea, both at 40%.
In the US, the top-five most affected cities (as judged by percentage of pediatric asthma cases linked to polluted air) are Los Angeles, New York, Chicago, Las Vegas, and Milwaukee
China had the largest national health burden associated with air pollution at 760,000 cases of asthma per year, followed by India at 350,000, and the United States at 240,000.
In general, cities with high NO2 concentrations also had high levels of greenhouse gas emissions.
The World Health Organization (WHO) has set Air Quality Guidelines for NO2 and other air pollutants. For NO2, that guideline pins about 21 parts per billion for annual average levels as being safe. The researchers estimate that most children live in areas that conform to this guideline, but say that 92% of new pediatric asthma cases attributable to NO2 sprung up in areas that met the WHO guidelines.
“That finding suggests that the WHO guideline for NO2 may need to be re-evaluated to make sure it is sufficiently protective of children’s health,” said Pattanun Achakulwisut, PhD, lead author of the paper and a postdoctoral scientist at Milken Institute SPH.
The team, however, is confident that we can do better. Many of the solutions aimed at scrubbing cities of the greenhouse gases in their air would also reduce NO2 levels, thus helping prevent new cases of asthma.
The paper “Global, national, and urban burdens of paediatric asthma incidence attributable to ambient NO2 pollution: estimates from global datasets” has been published in The Lancet Planetary Health journal.
New research at the University of New Mexico is looking into how much particulate matter air pollution costs the US every year — and how best to tackle it.
Image via Pixabay.
Fine particulate matter (PM2.5) air pollution caused an estimated 107,000 premature deaths in 2011, the study reports. The authors say these deaths cost society at large around $886 billion, and than 57% of them were at least partially the result of pollution caused by energy consumption (i.e. transportation or electricity generation).
“The impact of particulate matter air pollution is enormous even in countries with relatively good air quality like the U.S.,” says University of New Mexico economics professor Andrew Goodkind.
“There is still substantial room for improvement to the public health from reducing emissions, even though we have dramatically improved our air quality over the last 40 years.”
PM2.5 are particles with a diameter of or under 2.5 micrometers. They’re exceedingly small, so small, in fact, that we can only see them under an electron microscope. You could string 30 such particles along and they would still be shorter than the diameter of a single one of your strands of hair. Not just invisible to the naked eye, these particles are also quite toxic. They often carry along microscopic amounts of solid or liquid leftovers of the chemical reactions that created the particles themselves — these residues can be quire hazardous to human health.
What makes PM2.5 really troublesome, however, is that they’re so tiny they don’t really decant from they air; they just float around for long stretches at a time. Because of this, they have a very high chance, compared to other pollutants, to make their way into your lungs and bloodstream.
However, the effect of PM2.5 on general health depends greatly on where they are emitted or released. So, Goodkind’s team set about understanding how geography plays a part in their effect.
The team developed a model for calculating location-specific damages due to primary PM2.5 and PM2.5 precursor emissions. Based on these models, the team can estimate the impact of PM2.5 emissions in any location throughout the US, they say. And that’s exactly what they did — they applied the modeling tool to the U.S. emissions inventory to understand how each economic sector contributes to reduced air quality.
They found that 33% of health damages associated with PM2.5 occur within 8 km of emission sources, but 25% occur more than 150 miles away. These results emphasize the importance of tracking both local and long-range impacts, which is another element of what the paper addresses.
“Sources in the same urban area, releasing the same quantity of emissions, can have orders of magnitude difference in their impacts on health,” Goodkind said. “Identifying those sources with the largest impacts can help improve our decision making about how to reduce pollution.”
The team hopes policymakers will use their results to decide how and where to prioritize pollution mitigation efforts. They also plan to expand on their research by focusing more directly on certain sectors of the economy where emission reductions have been limited.
“Coal-fired electricity generation has, rightly, received substantial attention, and emissions have dropped substantially, but many people do not realize that agriculture is the source of a significant share of emissions,” Goodkind concluded. “We are looking into how and where we grow crops and raise livestock, what inputs are used, and how we can improve the system to continue to produce the food we need but with fewer environmental and health impacts.”
The paper “Fine-scale damage estimates of particulate matter air pollution reveal opportunities for location-specific mitigation of emissions” has been published in the journal Proceedings of the National Academy of Sciences (PNAS).
New research is looking into how we can better protect sterile environments from airborne viruses.
Professor Herek Clack (left) and members of his team set up a lab-scale non-thermal plasma device that has previously been proven to achieve greater than 99% inactivation of an airborne viral surrogate, MS2 phage, a virus that infects E.coli bacteria at the Barton Farms family pig farm in Homer, MI. Image credits Robert Coelius / Michigan Engineering
Nonthermal plasmas — ionized, charged particles formed around electrical discharges such as sparks — are very, very good at rendering airborne viruses harmless, a new study reports. This approach could help us better keep environments such as surgery rooms clean of pathogens, the authors explain, and might even render the surgical mask obsolete.
“The most difficult disease transmission route to guard against is airborne because we have relatively little to protect us when we breathe,” said paper co-author Herek Clack, a research associate professor of civil and environmental engineering at the University of Michigan.
Exposure to nonthermal plasmas, however, could be just the guard we need. In their study, the team crafted a nonthermal plasma reactor which was able to remove 99.9% of a test virus the researchers pumped through. Best of all, the whole process only took a fraction of a second to complete. The vast majority of the virus sample was rendered harmless due to inactivation, the team notes, with a sliver of the bugs getting scrubbed out of the airstream thanks to good old fashioned filtration.
The reactor used in this study looks suspiciously like a piece of pipe — because it is. The real magic happens inside. The team packed borosilicate glass into a cylindrical-shaped bed, which they placed inside the reactor. Then, they pumped a model virus (one harmless to humans) inside the rig, forcing the virus to pass through the spaces between the beads. Then, they started the reactor.
“In those void spaces, you’re initiating sparks,” Clack said. “By passing through the packed bed, pathogens in the air stream are oxidized by unstable atoms called radicals.”
“What’s left is a virus that has diminished ability to infect cells.”
The team tracked the amount of viral genome present in the air coming out of the reactor to gauge how it went about neutralizing the pathogens. These measurements revealed that more than 99% of the air sterilizing effect was due to inactivating the virus that was present, with the remainder of the effect due to filtering the virus from the air stream.
This two pronged-attack that combines filtration with inactivation is likely much more efficient than currently-available air sterilization techniques, the team reports, such as the use of filtration orultraviolet light. That’s because these other approaches rely on a single sterilization method — masks, for example, only employ filtration. Even the use of ultraviolet irradiation falls short, they explain, as it can’t sterilize a volume of air as quickly, thoroughly, or compactly as the nonthermal plasma reactor.
“The results tell us that nonthermal plasma treatment is very effective at inactivating airborne viruses,” said Krista Wigginton, assistant professor of civil and environmental engineering, and a co-author of the study. “There are limited technologies for air disinfection, so this is an important finding.”
The team has started a second phase of testing its reactor. They installed it to the ventilation air streams at a livestock farm near Ann Arbor, where they hope the nonthermal plasma will prove its worth in stomping out contagious livestock diseases such as avian influenza. Fingers crossed!
The paper, “Inactivation of airborne viruses using a packed bed non-thermal plasma reactor,” has been published in the Journal of Physics D: Applied Physics.
Air pollution may take a more personal toll on us than we’d suspected: happiness.
Image via Pixabay.
China is notorious for the heavy pollution affecting its cities. It’s a product of the massive uptick in industrialization, coal use, and the number of cars China has seen in the last few decades. While definitely good from an economic point of view — the country can boast an annual economic growth rate of 8% — air pollution has become a major public concern in China, with significant effects on the quality of life in its urban areas.
This pollution may have a much more direct effect on the country’s urbanites than previously believed, according to a paper lead-authored by, Siqi Zheng, associate professor of Real Estate Development and Entrepreneurship Faculty Director at MIT Future City Lab. The study found a strong inverse correlation between air pollution levels and locals’ happiness.
“Pollution also has an emotional cost,” Zheng says. “People are unhappy, and that means they may make irrational decisions.”
“So we wanted to explore a broader range of effects of air pollution on people’s daily lives in highly polluted Chinese cities.”
Air pollution is a major concern around the world, especially in developing or developed countries. Just last year, the State of Global Air/2018 report — published by the non-profit Health Effects Institute — estimated that roughly 95% of the world’s population lives in areas with unsafe levels of outdoor air pollution (10 µg pollutants/square meter of air, as per the World Health Organization’s guidelines). Around 60% live in areas where air pollution exceeds even the WHO’s least-stringent air quality target of 35 µg/m3.
PM 2.5 levels across the world. Image credits Health Effects Institute / State of Global Air/2018.
Roughly one-third of the world, the report adds, also has to contend with unsafe levels of indoor air pollution. The main culprits were the burning of fossil fuels in cars, power plants, and factories (outdoor pollution) or for heating and cooking (indoor), respectively.
The problem is definitely global, but China does stand out in regards to bad air. The clouds of Chinese smog have made headlines again and again over the last few years, due to their striking appearance and cost in human lives. Combined with Prof. Zheng’s background — environmental economics, urban development, and real estate market, with a special focus on China — this made the country a perfect place to study the effect of air pollution on our emotional well-being.
The team used real-time data drawn from social media microblogging platform Sina Weibo (similar to Twitter) to track the happiness levels in 144 Chinese cities. Roughly 210 million geotagged tweets posted between March and November of 2014 were processed using a machine-algorithm the team developed to measure which emotions each post conveyed. The team explains that they opted for this method of measuring people’s happiness levels instead of using questionnaires (the more usual approach) because questionnaires tend to reflect individuals’ overall feelings of well-being; what they wanted was snapshots of the happiness people felt on particular days.
This data was pooled to generate a median value per day for each city (which the team calls the “expressed happiness index”, or EHI) ranging from 0 to 100, with 0 indicating a very negative mood and 100 a very positive one.
Air pollution (highlighted in yellow) definitely has a health cost, but it also seems to have a happiness cost, according to Prof. Zheng’s team. Image credits Health Effects Institute / State of Global Air/2018.
“Social media gives a real-time measure of people’s happiness levels and also provides a huge amount of data, across a lot of different cities,” Zheng says.
Zheng’s team also looked at daily readings of ultrafine particulate matter — or PM 2.5 — concentrations in urban areas recorded by China’s Ministry of Environmental Protection. Airborne particulate matter has become the primary pollutant in China’s cities in recent years, the authors note, with PM 2.5 particles being particularly hazardous to lung health.
Finally, the team put the two datasets together. They found a very solid negative correlation between pollution and happiness levels. As a whole, women seemed to be more sensitive to the effects of pollution than men, as were individuals with higher incomes. Interestingly, both people in the most polluted and cleanest of China’s cities were most affected by air pollution, the team writes. Their hypothesis is that people who are particularly concerned about air quality and their own health tend to move to cleaner cities — making the EHI of these urban centers particularly sensitive to pollution levels — while those in very dirty cities are more aware of the damage to their health from long-term exposure to pollutants.
Past research has shown that people are more likely to engage in impulsive and risky behavior that they may later regret on days with heavy pollution, possibly as a result of short-term depression and anxiety, according to Zheng. Air pollution also has a well-documented negative effect on health, cognitive performance, labor productivity, and educational outcomes, she adds.
Together with their own findings, Zheng believes such data showcases how important it is for politicians to respond to public demand for cleaner air and take measures to curb air pollution. People may move to cleaner cities, buildings, or green areas, buy protective equipment such as face masks and air purifiers, and spend less time outdoors, to avoid the effects of air pollution. Prof. Zheng plans to continue researching the impact of pollution on people’s behavior in the future.
The National Institute of Environmental Health Sciences has more details on types of air pollution and preventive measures here. There’s a growing body of evidence that houseplants help improve indoor quality by scrubbing various pollutants like allergy-irritating dust and volatile organic compounds.
The paper “Air pollution lowers Chinese urbanites” has been published in the journal Nature Human Behaviour.
Air pollution seems to increase the risk of developing neurodegenerative diseases, a new study reveals.
High air pollution in London. Image credits David Holt / Flickr.
Nobody likes dirty air — though most of us are breathing exactly that. Air pollution has been established as a risk factor for heart disease, stroke, and respiratory disease. Whether or not it has a part to play in neurodegenerative diseases such as dementia, however, remained unclear until now.
For the study, the team produced estimates of air and noise pollution levels across the Greater London area, which they used to assess potential links with new dementia diagnoses.
Data on the latter was obtained from anonymized patient health records of the Clinical Practice Research Datalink (CPRD), which has been collecting data from participating general practices across the UK since 1987. The team worked with the records of under 131,000 patients: those aged 50 to 79 (in 2004), who had not been diagnosed with dementia, and were registered at either one of 75 general practices located within the London orbital M25 motorway.
Based on each patient’s postcode, the team then estimated their annual exposure to air pollutants, especially nitrogen dioxide (NO2), fine particulate matter (PM2.5), and ozone (O3). The team also estimated each patient’s proximity to heavy traffic and exposure to road noise using modeling methods and on-site measurements.
The team tracked each patient’s health until they received a diagnosis of dementia, de-registered from their practice, or died — whichever came first. Over the study period, 2181 patients (1.7%) were diagnosed with dementia, including Alzheimer’s disease.
Those patients living in the top 20% areas by NO2 levels had a massive 40% higher risk of being diagnosed with dementia compared to those living in the bottom 20%. A similar increase in risk was observed for high levels of PM2.5. These links were consistent and couldn’t be explained by any other factors the team had access to, such as smoking or diabetes. However, when restricted to specific types of dementia, the association only held for patients diagnosed with Alzheimer’s disease.
Caution to the wise, however: this is an observational study and, as such, the findings cannot be used to establish a cause-effect relationship; the findings may also only be applicable to the London area. Many factors may be involved in the development of dementia, the exact cause of which is still not known, the researchers point out.
“Traffic related air pollution has been linked to poorer cognitive development in young children, and continued significant exposure may produce neuroinflammation and altered brain innate immune responses in early adulthood,” the authors conclude.
Still, even if air pollution had a relatively modest contribution to the development of neurodegenerative diseases, overall public health gains would be significant if we made an effort to limit both it and exposure to it.
The paper “Are noise and air pollution related to the incidence of dementia? A cohort study in London, England” has been published in the journal BMJ.