Showing posts sorted by date for query SILICA. Sort by relevance Show all posts
Showing posts sorted by date for query SILICA. Sort by relevance Show all posts

Sunday, March 08, 2026

 

Scientists unveil universal aging mechanism in glassy materials



Chinese Academy of Sciences Headquarters





"Glass" has a unique and distinct meaning in physics—one that refers not just to the transparent material we associate with window glass. Instead, it refers to any system that looks solid but is not in true equilibrium and continues to change extremely slowly over time. Examples include window glass, plastics, metallic glasses, spin glasses (i.e., magnetic systems), and even some biological and computational systems.

When a liquid is cooled very quickly—a process called quenching—it doesn't have time to organize into a crystal but becomes stuck in a disordered state far from equilibrium. Its properties—like stiffness and structure—slowly evolve through a process called "aging."

Now, a research team from the Institute of Theoretical Physics of the Chinese Academy of Sciences has proposed a new theoretical framework for understanding the universal aging behavior of glassy materials.

The study reveals a fundamental mechanism that governs how glasses—from simple spin systems to complex network glasses such as amorphous silica—slowly evolve over time.

To understand the aging process, the researchers developed a generalized trap model (GTM) grounded in the material's energy landscape: a multidimensional map of all possible configurations and the energy barriers that separate them. According to the GTM, aging is driven by activated hopping across these energy barriers. A universal distribution of barrier heights, incorporating crucial finite-size corrections, governs the system's slow, nonequilibrium dynamics.

The theory predicts that during nonequilibrium aging, the system undergoes "weak ergodicity breaking" at a temperature higher than the conventional glass transition temperature. In statistical physics, "ergodic" refers to a system that explores all possible configurations consistent with its energy. In contrast, the term "ergodicity breaking" refers to an equilibrium system becoming trapped in a subset of possible states, unable to explore all configurations. Weak ergodicity breaking occurs in nonequilibrium systems and describes a system that continues to evolve but remains correlated with its initial configuration even after prolonged aging.

By applying the GTM to four distinct models, including the random energy model (a spin glass), the Weeks-Chandler-Andersen model (a simple atomic glass), and amorphous silica (a network glass), the researchers demonstrated that glass aging behavior follows universal mathematical laws. A key finding is that the logarithmic decay of the two-time correlation function, a hallmark of aging, is directly linked to the finite size of "activation clusters," or groups of particles that rearrange together during the aging process.

In the Weeks-Chandler-Andersen model, this insight allowed the researchers to extract a static length scale from the nonequilibrium dynamics, extending its observable growth range from a mere factor of two to three to a full order of magnitude. This provides strong supporting evidence for the random first-order transition (RFOT) theory, a leading theory of the glass transition.

This work provides a unified phase diagram that describes both ergodic and weakly non-ergodic phases in spin and structural glasses, offering a powerful tool for understanding these ubiquitous yet complex materials. These findings have implications not only for materials science but also for other complex systems, such as protein dynamics and even the training of deep learning algorithms, where similar slow relaxation processes are observed.

Sunday, February 22, 2026

Stop Tyrant Trump’s Lawless Attack on the Regulations Keeping Us Safe

Trump deserves Impeachment and Removal from Office. Congress should act now, before more Americans die, get sick, or are injured from the destruction of long-established, critical protections.


US President Donald Trump speaks alongside coal and energy workers during an executive order signing ceremony in the East Room of the White House on April 8, 2025 in Washington, DC.
(Photo by Anna Moneymaker/Getty Images)

Ralph Nader
Feb 21, 2026
Common Dreams


“Deregulation” is an antiseptic word loved by the giant corporations that rule the people. In reality, health and safety “deregulation” spells death, injury, and disease for the American people of all ages and backgrounds. This is especially so with the deranged dictates from the Tyrant Trump, who is happily beholden to his corporate paymasters, who are making him richer by the day.

President Donald Trump’s mindless deregulation mania got underway in January 2025 with his illegal shutting down of the US Agency for International Development (USAID), which has saved lives in poor countries—by providing food, water, medicine, etc.—for a pittance. USAID spends less in a year than the Pentagon spends in a week. International aid groups predict that the ongoing cuts could lead to 9.4 million preventable deaths occurring in poor countries by 2030 unless the vicious and cruel, unlawful Trumpian shutdown is reversed.

It turns out Trump was just warming up for his illegal violence against innocent American families in both blue and red states. He has abolished requirements for the auto industry to limit its emissions and maintain fuel efficiencies. The result: more disease-bearing gases and particulates into the lungs of Americans, including the most vulnerable—children and people suffering from respiratory diseases.

Trump wants to roll back the regulations that would require auto company fleets to average 50 miles per gallon by 2031. In 2024, the US Department of Transportation’s National Highway Traffic Safety Administration said its proposed vehicle fuel economy standards would save Americans more than $23 billion in fuel costs while reducing pollution.

Rather than faithfully execute federal laws, and ensure the well-being of the people, Dictator Donald is using his position and time in the White House to enrich himself and to get his name on anything he can get away with.

Month after month, Trump is illegally reducing or shutting down lifesaving programs without the required congressional approval. One of his major targets is the US Environmental Protection Agency (EPA). This month, his puppet EPA head, Lee Zeldin, celebrated the elimination of lethal greenhouse gases from the EPA’s regulatory controls. Zeldin and Trump are in effect telling Americans, “Let them breathe toxic air.” Plus, more climate catastrophes.

Smothering wind and solar projects while boosting the omnicidal polluting oil, gas, and coal production is another way Trump is exposing people to sickening gases and particulates. A corporate cynic once joked, “No problem, you can always refuse to inhale.”

Trump’s treachery toward coal miners, whom he praises, is shocking. He cut the funds for free testing of coal miners’ lungs, often afflicted with the deadly black lung diseases that have taken hundreds of thousands of coal miners’ lives over the past century and a half. We worked to pass the Federal Coal Mine Health and Safety Act of 1969, to control the levels of coal dust causing this disease, but Trump is unraveling it by cutting law enforcement. The Trump administration says it is “reconsidering” the long-awaited proposed silica control regulations. More unnecessary delay. In 2024, Politico reported that “Mine Safety and Health Administration projects that the final rule will avert up to 1,067 deaths and 3,746 silica-related illnesses.”

In his mass firings of federal civil servants, Trump has included the ranks of federal safety inspectors for meat and poultry plants (USDA), for occupational health and safety (OSHA), and specialized areas like you would never imagine—such as nuclear security. Tyrant Trump worsened the potential danger for workers and communities by firing most of the inspectors general—again illegally—who are the powerful watchdogs over federal departments and agencies. Many inspector general positions are still vacant.

In terms of short and long-run perils, Trump’s attacks on scientific research and discovery to reduce or prevent diseases would be enough to give him the grisly record for knowingly letting Americans die. The assault on vaccines, including for contagious diseases, is staggering, led by RFK, Jr., the secretary of Health and Human Services.

RFK, Jr. becomes more extreme by the day. His actions go way beyond any legitimate skepticism of the drug companies. He is going along with officials in states like Florida who are about to ban children’s vaccine mandates, even for polio, measles, and whooping cough. He has severely slashed, without congressional authority, budgets for basic and applied science programs underway at universities and other public institutions. His salvos are resulting in the reduction of families getting their children vaccinated, who, if contagious, could infect their classmates. The so-called powerful medical societies have not risen to their optimal level of resistance to what is fast coming, a green light for epidemics—starting with the resurgence of measles now underway in places like South Carolina.

The crazed Menace-in-Chief wanted to abolish the Federal Emergency Management Agency (FEMA) and its rescue responses to hyper-hurricanes, floods, and giant wildfires. He recklessly says the states can handle the carnage from such disasters. The real reason is that he doesn’t want to be held responsible for failing to properly respond to such disasters. Remember the criticism of George W. Bush’s response to Katrina?

Again, with Trump, it is all about him, feeding his insatiable MONSTROUS EGO, rather than saving American lives. Recently, tragic events have forced him to reconsider. He is bringing back some of the experts and rescuers he fired from FEMA earlier last year.

Rather than faithfully execute federal laws, and ensure the well-being of the people, Dictator Donald is using his position and time in the White House to enrich himself and to get his name on anything he can get away with—the John F. Kennedy Center for the Performing Arts, the US Institute of Peace, the US Treasury Department’s relief checks during Covid-19, the federal investment accounts, special visas, and a discount drug program. (See the February 16, 2026, article in the New York Times by Peter Baker titled, A Superman, Jedi and Pope).

Chronically lying; threatening violence against his opponents and people abroad; slandering anyone he feels like via the compliant mass media, including journalists and editors; and generally wrecking America as a serial law violator, Trump deserves to be told, “YOU’RE FIRED.” (This was his favorite TV show catchphrase). Trump deserves Impeachment and Removal from Office. Congress should act now, before more Americans die, get sick, or are injured from the destruction of long-established, critical protections under both Republican and Democratic administrations.



Saturday, February 21, 2026

We Can Move Beyond the Capitalist Model and Save the Climate – Here Are the First Three Steps

Source: The Guardian

We have an urgent responsibility. Our existing economic system is incapable of addressing the social and ecological crises we face in the 21st century. When we look around we see an extraordinary paradox. On the one hand, we have access to remarkable new technologies and a collective capacity to produce more food, more stuff than we need or that the planet can afford. Yet at the same time, millions of people suffer in conditions of severe deprivation.

What explains this paradox? Capitalism. By capitalism we do not mean markets, trade and entrepreneurship, which have been around for thousands of years before the rise of capitalism. By capitalism we mean something very odd and very specific: an economic systemthat boils down to a dictatorship run by the tiny minority who control capital – the big banks, the major corporations and the 1% who own the majority of investible assets. Even if we live in a democracy and have a choice in our political system, our choices never seem to change the economic system. Capitalists are the ones who determine what to produce, how to use our labour and who gets to benefit. The rest of us – the people who are actually doing the production – do not get a say.

And for capital, the purpose of production is not primarily to meet human needs or to achieve social progress, much less to deliver on any ecological goals. The purpose is to maximise and accumulate profit. That is the overriding objective. This is the capitalist law of value. And to maximise profits, capital requires perpetual growth – ever increasing aggregate production, regardless of whether it is necessary or harmful.

So we end up with irrational forms of production as a result: we get massive production of things such as SUVs, mansions and fast fashion, because these things are highly profitable to capital, but chronic underproduction of obviously necessary things like affordable housing and public transit, because these are much less profitable to capital, or not profitable at all.

Similarly with energy. Renewables are already much cheaper than fossil fuels. Alas, fossil fuels are up to three times as profitable. Thus capital forces governments to link electricity prices to the price of the most expensive liquified natural gas, not of cheap solar energy. Similarly, building and maintaining motorways is many times more lucrative for private contractors, car manufacturers and oil companies than a modern network of superfast, safe public railways. So capitalists continue to push our governments to subsidise fossil fuels and road building, even while the world burns.

Since Donald Trump’s election, many major investment firms have enthusiastically abandoned their climate commitments, which had, in favour of the common good, restrained their profitability. This should be a clarifying moment for all of us: capitalism cares about our species’ prospects as much as a wolf cares about a lamb’s.

So here we are: trapped in capitalism’s set of priorities, which are inimical to humanity’s. Human ingenuity has bequeathed us splendid technologies and capacities. But, like a cruel divinity, capital not only prevents us from using them for our collective good, but in fact coerces us to deploy them towards our collective doom.

The system also locks us into never-ending cycles of imperialist violence. Capital accumulation in advanced economies relies on massive inputs of cheap labour and nature from the global south. To maintain this arrangement, capital uses every tool at its disposal – debt, sanctions, coups and even outright military invasion to keep southern economies subordinate.

The solution is staring us in the face. We urgently need to overcome the capitalist law of value and democratise our economy, so that we can organise production around urgent social and ecological priorities. After all, we are the producers of the goods, the services, the technologies. It is our labour and our planet’s resources that are at stake. And so we must claim the right to decide what is produced, how, and for what purpose.

How can this be done? There are three necessary conditions for the transformation of our economy from a dead-end dictatorship into a functioning and ecologically sound democratic one.

The first condition is a new financial architecture that penalises destructive private “investments” and enables public finance for public purposes. At the heart of this architecture we need a new public investment bank that, in association with the central banks, converts available liquidity into the types of investment consistent with common, sustainable prosperity.

The second condition is the extensive use of deliberative democracy to decide sectoral, regional and national goals (eg regarding the growth or even winding down of different outputs) towards which the new public finance tools will be aimed.

And the third condition is a Great Corporate Reform Act for the purpose of democratising corporations, favouring and promoting the formation of companies run along the lines of one employee, one share, one vote.

We live in a shadow of the world we could create. A world in which we shall be able to avert an almost certain ecological collapse, rather than waiting around for capitalism to push us beyond the point of no return. A world where the abolition of economic insecurity, precarity, poverty, unemployment and indignity is possible, while we lead meaningful lives within planetary boundaries. This is not a distant dream. It is a tangible prospect.

Jason Hickel is professor at the Autonomous University of Barcelona and a visiting senior fellow at the London Schoool of Economics.

Yanis Varoufakis is the leader of MeRA25, a former finance minister of Greece and author of Technofeudalism: What Killed Capitalism

Source: Resilience

Humanity has missed the mark. Humanity has failed.

As COP30 got underway, this was the media’s take on the UN Secretary-General’s announcement that 1.5 degrees of global warming has now been locked in. We should be rolling our eyes at such proclamations. Once again, humanity takes the blame for the impotence of corporate-led summits.

The truth is that humanity includes billions of land-based people who have not yet been pushed into resource-intensive cities and consumer lifestyles. Humanity includes hundreds of thousands of people who – like you, perhaps – have been taking active steps to reduce their ecological footprint, while lobbying for meaningful government policy change. Why should humanity take the blame for the blind, top-down policy frameworks that, above all, treat ecocide and climate breakdown as a ‘carbon market’ – as an opportunity to grow corporate bottom lines?

Ever since Al Gore stood up on his soapbox, we’ve had the finger pointed at our individual behavior. Meanwhile, global corporations were needlessly transporting goods across the world, contributing to massive increases in emissions and mountains of plastic waste.

‘Free trade’ treaties were giving them the right to direct whole societies down the consumerist path; the right to target children with the message: ‘if you want to be loved and respected, you’ve got to have the latest smartphone, the coolest shoes’.

Humanity was never the issue. Corporate rule was.  

And there’s no two ways about it – COP is ruled by global corporations. Funding comes from chemical giants like Bayer, tech giants like IBM, and mining corporations like Anglo American. As such, there is no talk of real, commonsense solutions like decentralizing economies, limiting the barrage of consumer messaging, preventing built-in obsolescence, or regulating the most polluting industries. Emissions from redundant trade – at the very heart of the resource-guzzling global economy – has never been so much as mentioned during the negotiations.

The COPs have consistently ensured that billions of dollars get sunk into false but lucrative solutions. Ostensibly to monitor carbon, technologies like A.I. and Internet of Things are being rolled out, with enormous demand for rare earth minerals and severe implications for freedom and surveillance. Carbon markets are commodifying land and water and biodiversity and turning them into financial assets to be traded.

As our colleague, Dr. Camila Moreno, who has attended all the COPs, has summarized:

“This is not a meeting about climate. This is where you can see, most clearly, where the future of capitalism is going.”

Do you speak ‘carbonese’? 

Under the vague framing of ‘net-zero’, giant carbon capture plants have been built to supposedly combine air carbon with plastic trash under enormous temperatures and inject it into bedrock. And, perhaps even worse, the much-hyped ‘green transition’ has plastered what should be productive, biodiverse land and coastlines with solar panels, wind turbines, and biomass monocultures.

In the face of all this, humanity is not about to declare failure and give up. Things might be getting bad already – fires, floods, storms – but around the world at the grassroots, people are taking action.

And, come what may, what action makes most sense? Local food. Hands-on ecosystem regeneration. Strengthening community and the local economy. 

And raising awareness about the fact that governments don’t have our back.

So, where the UN, the COPs and global corporations have failed, humanity is the solution. Let’s make visible the quiet revolution that’s occurring from the bottom up as communities express their care for others and the living world.

Renewables – saviour or curse?

We must look squarely at the call for a renewable energy. It’s not an easy topic to address. For decades, Local Futures has been part of the call for a small-scale, decentralized renewable energy installations to meet real human needs. Back in the 70s, the environmental movement had clarity about this.

But over the last 3 decades, the global ‘green transition’ has emerged. In rhetoric, it’s about plugging the global economy into a different, greener power source. In reality, it’s about growing the global economy’s already outrageous and wasteful energy demands by throwing more mega-industrial technologies into the mix.

How can environmentalists support the plastering of land with solar panels made from silica mined by consuming entire Indonesian islands? How can they support the conversion of ever more mountains and valleys to vast landscapes of towering pylons built in concrete, plastic, steel and balsa wood from the Amazon – turbines with a life span of less than 20 years destined to pile up in landfills?

How can they support the scouring of the seabed for manganese, and the mining of copper, nickel, rare earths, lithium and cobalt – all of which the International Energy Agency says will require extraction increases of around 400% by 2040 in order to keep up with A.I., digital and renewable infrastructure demands?

We do need some renewables. But the ‘transition’ must be radically reframed. We must not start by asking “how do we transition the current global economy to renewable energy” – that proposition is a death sentence. We must start by asking “what are our real human energy needs, and how do we meet them in the wisest way possible?” In other words, what are the needs of thriving local economies.

A.I. – for climate? Or for corporate profit? 

The global economy’s demand for resources and energy is entirely about fueling technologies that have nothing to do with real human needs and everything to do with expanding corporate wealth and power. The A.I. industry is Exhibit A.

A.I.’s cheerful front end – the chatbot that answers a question, the app that writes your email – hides a vast infrastructure of energy-intensive data centers and mineral-intensive manufacturing – all expanding at breakneck speed. In some US states, data centers are already using more than 10% of all electricity, and analysts project that AI will push global data-center power demand up by more than 150% this decade. Google and Microsoft have both reported near 50% increases in their total emissions, due solely to the aggressive buildout of data-center infrastructure to support A.I.

Then there is the water. These facilities need vast quantities of fresh, clean water to stop their servers from overheating. Microsoft has admitted that nearly half of its water use now occurs in regions already facing water scarcity. In Spain, where drought conditions are worsening and desertification covers three-quarters of the country, Amazon’s new AI data centers have approval to draw over 750,000 cubic meters of drinking water a year. South Korea’s planned mega-cluster of semiconductor factories will demand more than half of Seoul’s daily water use, alongside vast amounts of electricity, toxic chemicals, and land for waste disposal. Similar stories are emerging from Chile, the US Southwest, and parts of India.

AI is not a climate tool at all. It is the next frontier in global corporate expansion – a new reason to build pipelines, power stations, transmission corridors, mega-mines, and surveillance infrastructures. Framed as “efficiency” or “net-zero”, it locks us ever deeper into the top-down model where entire regions are sacrificed so that a handful of companies can extract wealth from data, attention and public resources.

All this stands in stark contrast to the quiet, grounded solutions emerging from below. True climate action doesn’t require vast data centers, billions of liters of water, or mineral-intensive hardware. It requires shorter distances, stronger communities, healthy soils, local food webs, and diverse, place-based economies that reduce demand at the source.

A.I.’s expanding empire is a reminder of what happens when we allow the global economy to chase technological fixes instead of human-scale wisdom.

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Thursday, February 19, 2026

Laser-etched glass can store data for millennia, Microsoft says


By AFP
February 18, 2026


Cooling vents on data centres in Virginia. Researchers hope that storing data on glass will save energy - Copyright AFP/File ANDREW CABALLERO-REYNOLDS
Frédéric Bourigault and Daniel Lawler

Thousands of years from now, what will remain of our digital era?

The ever-growing vastness of human knowledge is no longer stored in libraries, but on hard drives that struggle to last decades, let alone millennia.

However, information written into glass by lasers could allow data to be preserved for more than 10,000 years, Microsoft announced in a study on Wednesday.

Since 2019, Microsoft’s Silica project has been trying to encode data on glass plates, in a throwback to the early days of photography, when negatives were also stored on glass.

The system uses silica glass, a common material that is resistant to changes in temperature, moisture and electromagnetic interference.

These are all problems for energy-hungry data centres, which use fast-degrading hard drives and magnetic tapes that require backing up every few years.

In the journal Nature, Microsoft’s research arm said Silica was the first glass storage technology that had been demonstrated to be reliable for writing, reading and decoding data.

However, experts not involved in the project warned that this new tech still faces numerous challenges.

– How to write inside glass –

First, bits of data are turned into symbols, which correspond to three-dimensional pixels called voxels.

A high-powered laser pulse then inscribes these minuscule voxels into square glass plates that are roughly the size of a CD.

“The symbols are written layer by layer, from the bottom up, to fill the full thickness of the glass,” the study explained.

To read the data requires a special microscope that can see each layer, then decode the information using an algorithm powered by artificial intelligence.

The Microsoft researchers estimated that the glass could survive for more than 10,000 years at a blistering 290 degrees Celsius, which suggests the data could last even longer at room temperature.

However, the researchers did not look into what happened when the glass was deliberately smashed — or corroded by chemicals.

Unlike data centres, the glass does not require a climate-controlled environment, which would save energy.

Another advantage is that the glass plates cannot be hacked or otherwise altered.

The Microsoft researchers emphasised that future storage is important because the amount of data being produced by humanity is now doubling roughly every three years.

– ‘Carry the torch ‘ –

One of the glass plates holds the equivalent of “about two million printed books or 5,000 ultra-high-definition 4K films”, according to Feng Chen and Bo Wu, researchers at Shandong University in China not involved in the study.

In a separate Nature article, the pair warned there were more challenges ahead, including finding a way to write the data faster, to mass produce the plates and to ensure people can easily access and read the information.

However, they praised Silica for creating a “viable solution for preserving the records of human civilisation”.

“If implemented at scale, it could represent a milestone in the history of knowledge storage, akin to oracle bones, medieval parchment or the modern hard drive,” they said.

“One day, a single piece of glass might carry the torch of human culture and knowledge across millennia.”

Sunday, February 15, 2026

 

Drones equipped with cost-effective sensors can help to monitor air quality more effectively



Study in Indian megacity Delhi highlights the importance of vertical measurements




Leibniz Institute for Tropospheric Research (TROPOS)

drone 

image: 

The drone with the payloads PM-LCS, AE-51 micro-Aethalometer, and meteorological sensors.

view more 

Credit: Ajit Ahlawat, TU Delft / TROPOS





New Delhi/ Delft/ Leipzig. Cost-effective sensors on drones may be an effective tool for better investigating the lowest layers of the atmosphere. If ground-based air quality measurements were supplemented by such drone measurements, air quality models, strategies to combat air pollution could be improved. This is the conclusion of an international research team from a field study in the Indian metropolitan region of Delhi, which showed that particulate matter (PM) concentrations depend heavily on height above ground level. For example, at a height of 100 meters, PM2.5 concentrations were up to 60 percent higher than at ground level. The results suggest that current model simulations significantly underestimate PM2.5 concentrations during morning smog phases, the researchers write in the journal Nature npj Clean Air.

Researchers from India, the Netherlands, Germany, China, Greece, Great Britain, Thailand, Czechia, and Cyprus participated in the study in Delhi. It was coordinated by Asst. Prof. Ajit Ahlawat from the Leibniz Institute for Tropospheric Research (TROPOS), who now conducts research at TU Delft. With over 30 million people, the metropolitan area around India's capital New Delhi is one of the largest and most densely populated megacities in the world. Air pollution there is also among the highest in the world. Particularly in winter smog, particulate matter concentrations reach extremely hazardous levels.

 

Heavy smog often prevails in northern India, especially after the monsoon and in winter. For this reason, a series of ground-based measurements have recently been carried out to better understand the causes and mechanisms of air pollution. Most studies conducted in India are based either on satellite observations from space or on ground-based measurements. In contrast, there is hardly any data available from the lowest layers of the atmosphere. However, the vertical distribution of air pollutants and meteorological conditions up to an altitude of about one kilometre are of great importance because they have a decisive influence on how high the concentration of pollutants in the air can become.

 

In recent years, significant advances have been made in both drone (uncrewed aerial vehicle/UAV) technology and cost-effective particulate matter sensors. Mass production and miniaturization offer new possibilities, which were tested by researchers in a field trial in March 2021 at the Indian Institute of Technology (IIT) Delhi and compared with standard measurements from stationary measuring devices. To this end, the research team equipped and modified a drone from the Indian start-up BotLab Dynamics with low-cost fine PM sensors: "A significant development was the construction of a custom-made vertical aerosol inlet, which was positioned about 30 centimetres above the drone's rotor blades. This enabled us to take measurements that were as accurate as possible, which is otherwise a major problem with drones, whose rotor blades cause significant air turbulence, “reports Prof. Ajit Ahlawat. “Another challenge was the high humidity, a meteorological factor that is not particularly rare in this region. Since air sampling and analysis are difficult under such conditions, a custom-designed silica gel dehumidifier was installed to ensure reliable results.” This enabled the researchers to investigate vertical fluctuations in air pollutant concentrations at different altitudes and at different times of day. The focus was on hazy and non-hazy morning hours in Delhi in order to find out more about the causes of smog.

 

Organic substances dominated during the day, while inorganic substances such as nitrate and chloride increased significantly at night. This trend indicates an increased contribution, which is likely due to the combustion of biomass and waste as well as industrial emissions during the evening and night hours. Nitrate and ammonium were strongest in the early morning, suggesting their condensation into the aerosol phase under humid and cold conditions. As the boundary layer height increased after sunrise, dilution effects led to a rapid decrease in chloride mass concentration. NOx levels peaked around 9:00 p.m. local time, caused by vehicle and industrial emissions trapped under a stable boundary layer. In contrast, fine particulate matter (PM2.5) rose steadily from around 80 micrograms per cubic meter at 6:00 p.m. local time to around 150 micrograms per cubic meter at 8:00 a.m. local time, underscoring the role of fresh primary emissions and secondary aerosol formation during smog formation. An example illustrates how much PM concentrations can vary depending on altitude: on March 18, the PM2.5 concentration rose by a remarkable 60 percent with increasing altitude, reaching around 160 micrograms per cubic meter at higher elevations compared to around 100 micrograms per cubic meter at ground level. The morning inversion had obviously caused the pollutants to accumulate particularly strongly in the lower boundary layer. Relative humidity was above 80% at night, which promotes the formation of secondary aerosols and the growth of particles through water absorption. This was also highlighted by the proxy indicator e.g. PM ratio used during the study. When the temperature rose above 30°C in the morning, the relative humidity fell below 40% and the haze dissipated.

 

The accumulation of pollutants and high humidity at night are the main reasons for the formation of ground-level smog layers in Delhi. The rapid dissipation of haze after sunrise is facilitated by the expansion of the boundary layer, reduced relative humidity, and increased photochemical oxidation. These findings underscore the need for emission control measures targeting nocturnal sources and humidity-driven secondary aerosol processes, as well as their understanding, particularly in vertical columns, in order to reduce smog in Delhi.

 

Another important finding of the study emerged from a comparison of the measurements with the WRF-Chem model, which is frequently used worldwide to predict air quality: the results indicate that current model simulations significantly underestimate PM2.5 concentrations during morning smog phases. ‘This may be due to the dry bias of the model, which limits its ability to simulate aerosol hygroscopic growth at high humidity values’ explains Prof. Mira Pöhlker from TROPOS and the University of Leipzig. 

These deviations are greatest when there is heavy haze. It also shows that high-resolution vertical measurements are important for validating air quality models in the lower boundary layer and for improving urban air quality predictions,’ explains Prof. Sagnik Dey from Indian Institute of Technology, Delhi.

 

The team believes that the study is an important step towards integrating cost-effective particulate matter sensors into existing air monitoring systems and closing observation gaps in the lower boundary layer. ‘By directly quantifying the interactions between relative humidity and particulate matter, as well as model deviations under real smog conditions, our results pave the way for next-generation air quality models that consider aerosol chemistry and dynamic boundary layer coupling,’ emphasises Ajit Ahlawat. These innovations are crucial not only for improving predictions and public health measures in megacities such as Delhi, but also for developing global strategies to mitigate air pollution in rapidly urbanising regions and its climate impacts. Tilo Arnhold

The drone carrying the payload hovering at high altitude.

Credit

Rohit K. Choudhary (University of Delhi)

The drone hovering at high altitude with a smoggy/hazy background in the backdrop.

Credit

Ajit Ahlawat, TU Delft / TROPOS