Multiple air pollutants linked to asthma symptoms in children

Exposure to several combinations of toxic atmospheric pollutants may be triggering asthma symptoms among children, a recent analysis suggests.

The study, published in the journal Science of the Total Environment, showed that 25 different combinations of air pollutants were associated with asthma symptoms among 269 elementary school children diagnosed with asthma in Spokane, Washington. In line with previous research, the Washington State University-led study revealed a socioeconomic disparity -- with one group of children from a lower-income neighborhood exposed to more toxic combinations, a total of 13 of the 25 identified in this research.

"It's not just one pollutant that can be linked to asthma outcomes. This study examined the variety and combinations of air toxics that may be associated with asthma symptoms," said lead author Solmaz Amiri, a WSU researcher in the Elson S. Floyd College of Medicine.

While other studies have focused on a limited number of pollutants, Amiri and her colleagues used the data-crunching power of machine learning techniques to analyze the potential exposure effects of 109 air pollutants and their combinations on asthma outcomes.

The researchers drew on data collected and modeled by the Environmental Protection Agency on air toxics present in individual neighborhoods surrounding 10 Spokane elementary schools. They also accessed anonymized data from the elementary schools for reports of students diagnosed with asthma who experienced symptoms such as coughing, wheezing, difficulty breathing and the need to use an inhaler.

The study looked at asthma symptoms occurring in 2019 and 2020 in the six months before the pandemic lockdowns started in March 2020. The researchers then associated these data with air pollutant exposures that occurred within those six months and with two longer-term exposure periods of three years and five years prior to the asthma symptoms.

The researchers found that three specific pollutants were significantly associated with asthma symptoms across all three exposure periods.

The toxicants involved may have unfamiliar names -- 1,1,1 trichloroethane, 2-nitropropane and 2, 4, 6 trichlorophenol -- but they derive from commonly used materials. The first is a widely used solvent in industry but was formerly used in household cleaners and glues. The second is an additive to paints and other finishes, and the third is an anti-septic and anti-mildew agent that was banned in the 1980s but may still be found in some pesticides and preservatives made before then.

"Some of these air toxics were discontinued in the U.S., but they can still be found in materials that may be in storage or people have in their backyard or garage. Other air toxics still exist at least in the environment," said Amiri.

This study did not intend to pinpoint the source of any one air pollutant or the exact reason why one group of children from a lower-income neighborhood was highly exposed to air pollutants. However, proximity of known air pollution sources may play a role, Amiri said, such as living close to a highway with a lot of traffic or facilities that use solvents, such as paint producers or factories.

The finding of a likely socioeconomic disparity in air toxic exposures is consistent with previous research showing that children from lower-income areas, often indicated by schools with a higher percentage of students who qualify for free or reduced meals, are exposed to a wide variety of air pollutants in the neighborhoods where they live.

While the current study is limited to the mid-sized city of Spokane, Amiri noted that the findings align with another study in New York City which found similar air pollutants significantly associated with asthma outcomes.

"Both in Spokane and New York City, regardless of the setting -- how large or small the cities are -- these air toxics appear to be influencing asthma among children," she said.

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Green doesn't always mean clean: Cleaning products urgently need better regulation, researchers warn

Many cleaning products labelled as "green" emit just as many harmful chemicals as regular products, new research has revealed.

Researchers say there needs to be better regulation and more guidance for consumers about how safe cleaning products really are.

Potentially harmful

The study, published by The Royal Society of Chemistry in the journal Environmental Science: Processes & Impact, found that fragranced cleaning products can be potentially harmful for the air quality in people's homes.

Cleaning products emit a wide range of volatile organic compounds (VOCs), including some which are hazardous or can undergo chemical transformations to generate harmful secondary pollutants.

In recent years, "green" cleaners have become increasingly popular, with an implicit assumption that these are better for our health and the environment.

But the University of York research found this was not the case.

Secondary pollutants

As part of the study, the VOC composition of 10 regular and 13 green cleaners was examined by researchers.

Green cleaners generally emitted more monoterpenes than regular cleaners, resulting in increases in harmful secondary pollutant concentrations following use, such as formaldehyde and peroxyacyl nitrates.

The study found that the fragrance ingredients of these products were the source of the volatile monoterpenes.

As levels of these types of pollutants increase in the home, susceptible people can develop breathing problems or irritation of the eyes, nose, throat, or skin.

Repeated exposure to high concentrations of formaldehyde can possibly lead to cancer in some cases.

Misleading consumers

Ellen Harding-Smith, Environmental Chemistry researcher from the Department of Environment & Geography, said: "Our research found there is no strong evidence to suggest that clean green products are better for indoor air quality compared to regular products.

"In fact, there was very little difference. Many consumers are being misled by the marketing of these products and could be damaging the air quality in their homes as a result -- potentially putting their health at risk. For so many products on the supermarket shelves, green doesn't mean clean."

Compositional differences

The research was funded by the EPSRC and the project is called IMPeCCABLE.

It is a collaboration between the University of York's Department of Environment and Geography, the Department of Chemistry, and the Wolfson Atmospheric Chemistry Laboratory.

Miss Harding-Smith, who is PhD Candidate, added: "The study highlights potential compositional differences in the formulations of regular and green cleaners, for which there is currently very little information on in the available literature.

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Unlocking the power of molecular crystals: A possible solution to nuclear waste

In a world increasingly concerned about the environmental and geopolitical implications of fossil fuel usage, nuclear energy has resurfaced as a subject of great interest. Its ability to generate electricity at scale without greenhouse gas emissions holds promise as a sustainable clean energy source that could bridge society's transition away from fossil fuels to a net-zero future. However, nuclear power generation does produce radioactive waste. The safe management of nuclear waste remains a crucial challenge that must be addressed to gain public confidence in this transformative power solution.

Now, a team of University of Houston researchers has come up with an innovative solution for nuclear waste management: molecular crystals based on cyclotetrabenzil hydrazones. These crystals, which are based on a groundbreaking discovery made by the team in 2015, are capable of capturing iodine -- one of the most common radioactive fission products -- in aqueous and organic solutions, and on the interface between the two.

"This last point is particularly salient because iodine capture on interfaces could prevent the iodine from reaching and damaging the specialized paint coatings used in nuclear reactors and waste containment vessels," said Ognjen Miljanic, professor of chemistry and corresponding author of the paper detailing the breakthrough in Cell Reports Physical Science.

These crystals exhibit an astonishing iodine uptake capacity, rivaling that of porous metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), which were previously deemed the pinnacle of iodine capture materials.

Alexandra Robles, the first author of the study and a former doctoral student who based her dissertation on this research, was working with the crystals in Miljanic's lab when she made the discovery. Her interest in finding a solution for nuclear waste led Robles to investigate using crystals to capture iodine.

"She ended up capturing iodine on the interface between the organic and water layers, which is an understudied phenomenon," said Miljanic, who added that this exceptional feature provides a crucial advantage. "When the material is deposited between the organic and aqueous layer, it essentially stops the transfer of iodine from one layer to another."

Not only does this process preserve integrity of reactor coatings and enhance containment, but the captured iodine could also then be moved from one area to another. "The idea here is that you capture it at a place where it's difficult to manage, and then you release it at a place where it's easy to manage," Miljanic said.

The other benefit of this catch-and-release technology is that the crystals can be reused. "If the pollutant just sticks to the regent, the whole thing has to be thrown away," he said. "And that increases waste and economic loss."

Of course, all of these great potentials still need to be tested in practical applications, which has Miljanic thinking of the next steps.

Molecules, Crystals and Octopuses, Oh My!

Miljanic's team creates these tiny organic molecules containing only carbon, hydrogen and oxygen atoms using commercially available chemicals.

Each crystal is a ring-shaped structure with eight linear piece emanating from it, which has led the research team to nickname it "The Octopus."

"They are quite easy to make and can be produced at a large scale from relatively inexpensive materials without any special protective atmosphere," said Miljanic.

He estimated that he can currently produce these crystals at the cost of about $1 per gram in an academic lab. In an industrial setting, Miljanic believes the cost would drop significantly.

These hungry little crystals are very versatile and can capture more than iodine. Miljanic and his team have used some of them to capture carbon dioxide, which would be another great step toward a cleaner, more sustainable world. In addition, "The Octopus" molecules are closely related to those found in materials used to make lithium-ion batteries, which opens the door to other energy opportunities.

"This is a type of simple molecule that can do all sorts of different things depending on how we integrate it with the rest of any given system," Miljanic said. "So, we're pursuing all those applications as well."

He is excited by the multitude of potential offered by the crystals and looking forward to exploring practical applications. His next goal is to find a partner who will help the scientists explore different commercial aspects.

Read more at Science Daily

Legacy industrial contamination in the Arctic permafrost

Many of us picture the Arctic as largely untouched wilderness. But that has long-since ceased to be true for all of the continent. It is also home to oilfields and pipelines, mines and various other industrial activities. The corresponding facilities were built on a foundation once considered to be particularly stable and reliable: permafrost. This unique type of soil, which can be found in large expanses of the Northern Hemisphere, only thaws at the surface in summer. The remainder, extending up to hundreds of metres down, remains frozen year-round.

Accordingly, permafrost has not only been viewed as a solid platform for buildings and infrastructure. "Traditionally, it's also been considered a natural barrier that prevents the spread of pollutants," explains Moritz Langer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). "Consequently, industrial waste from defunct or active facilities was often simply left on-site, instead of investing the considerable effort and expense needed to remove it." As a result of the industrial expansion during the cold war, over the decades this led to micro-dumps full of toxic sludge from oil and gas exploration, stockpiles of mining debris, abandoned military installations, and lakes in which pollutants were intentionally poured. "In many cases, the assumption was that the permafrost would reliably and permanently seal off these toxic substances, which meant there was no need for costly disposal efforts," says Guido Grosse, who heads the AWI's Permafrost Research Section. "Today, this industrial legacy still lies buried in the permafrost or on its surface. The substances involved range from toxic diesel fuel to heavy metals and even radioactive waste."

But as climate change progresses, this "sleeping giant" could soon become an acute threat: since the permafrost regions are warming between twice as fast and four times as fast as the rest of the world, the frozen soil is increasingly thawing. When this happens, it changes the hydrology of the region in question, and the permafrost no longer provides an effective barrier. As a result, contaminants that have accumulated in the Arctic over decades can be released, spreading across larger regions.

In addition, thawing permafrost becomes more and more unstable, which can lead to further contamination. When the ground collapses, it can damage pipelines, chemical stockpiles and depots. Just how real this risk already is can be seen in a major incident from May 2020 near the industrial city Norilsk in northern Siberia: a destabilized storage tank released 17,000 metric tons of diesel, which polluted the surrounding rivers, lakes and tundra. According to Langer: "Incidents like this could easily become more frequent in the future."

In order to more accurately assess such risks, he and an international team of experts from Germany, the Netherlands and Norway took a closer look at industrial activities in the High North. To do so, they first analysed freely available data from the portal OpenStreetMap and from the Atlas of Population, Society and Economy in the Arctic. According to these sources, the Arctic permafrost regions contain ca. 4,500 industrial sites that either store or use potentially hazardous substances.

"But this alone didn't tell us what types of facilities they were, or how badly they could potentially pollute the environment," says Langer. More detailed information on contaminated sites is currently only available for North America, where roughly 40 percent of the global permafrost lies. The data from Canada and Alaska showed that, using the location and type of facility, it should be possible to accurately estimate where hazardous substances were most likely to be found.

For Alaska, the Contaminated Sites Program also offers insights into the respective types of contaminants. For example, roughly half of the contaminations listed can be attributed to fuels like diesel, kerosene and petrol. Mercury, lead and arsenic are also in the top 20 documented environmental pollutants. And the problem isn't limited to the legacy of past decades: although the number of newly registered contaminated sites in the northernmost state of the USA declined from ca. 90 in 1992 to 38 in 2019, the number of affected sites continues to rise.

There are no comparable databases for Siberia's extensive permafrost regions. "As such, our only option there was to analyse reports on environmental problems that were published in the Russian media or other freely accessible sources between 2000 and 2020," says Langer. "But the somewhat sparse information available indicates that industrial facilities and contaminated sites are also closely linked in Russia's permafrost regions."

Using computer models, the team calculated the occurrence of contaminated sites for the Arctic as a whole. According to the results, the 4,500 industrial facilities in the permafrost regions have most likely produced between 13,000 and 20,000 contaminated sites. 3,500 to 5,200 of them are located in regions where the permafrost is still stable, but will start to thaw before the end of the century. "But without more extensive data, these findings should be considered a rather conservative estimate," Langer emphasises. "The true scale of the problem could be even greater."

Making matters worse, the interest in pursuing commercial activities in the Arctic continues to grow. As a result, more and more industrial facilities are being constructed, which could also release toxic substances into nearby ecosystems. Further, this is happening at a time when removing such environmental hazards is getting harder and harder -- after all, doing so often requires vehicles and heavy gear, which can hardly be used on vulnerable tundra soils that are increasingly affected by thaw.

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Novel air filter captures wide variety of pollutants

An air filter made out of corn protein instead of petroleum products can concurrently capture small particulates as well as toxic chemicals like formaldehyde that current air filters can't.

The research could lead to better air purifiers, particularly in regions of the world that suffer from very poor air quality. Washington State University engineers report on the design and tests of materials for this bio-based filter in the journal Separation and Purification Technology.

"Particulate matter is not that challenging to filter but to simultaneously capture various kinds of chemical gas molecules, that's more significant," said Katie Zhong, professor in WSU's School of Mechanical and Materials Engineering and a corresponding author on the paper. "These protein-based air filtering materials should be very promising to capture multiple species of air pollutants."

Poor air quality is a factor in diseases such as asthma, heart disease and lung cancer. Commercial air purifiers remove tiny particles in soot, smoke or car exhaust, which could be inhaled directly into the lungs, but air pollution also often contains other hazardous gaseous molecules, such as carbon monoxide, formaldehyde and other volatile organic compounds.

With micron-sized pores, typical high efficiency particulate air filters, also known as HEPA filters, can capture the small particles but aren't able to capture gaseous molecules. They are most often made of petroleum products and glass, which leads to secondary pollution when old filters are thrown away, Zhong said.

The WSU researchers developed a more environmentally friendly air filter made from corn protein fibers that was able to simultaneously capture 99.5% of small particulate matter, similar to commercial HEPA filters, and 87% of formaldehyde, which is higher than specially designed air filters for those types of toxics.

The researchers chose corn to study because of its abundance as an agricultural product in the U.S. The corn protein is also hydrophobic, which means that the protein repels water and could work well in a moist environment such as in a mask.

The amino acids in the corn protein are known as functional groups. When exposed at the protein's surface, these functional groups act like multiple hands, grabbing the toxic chemical molecules. The researchers demonstrated this by exposing a functional group at the protein surface, where it grabbed formaldehyde. They theorize that further rearrangement of the proteins could develop a tentacle-like set of functional groups that could grab a variety of chemicals from the air.

"From the mechanism, it's very reasonable to expect that this protein-based air filter could capture more species of toxic chemical molecules," Zhong said.

The three-dimensional structure that they developed also offers more promise for a simple manufacturing method than thin films of proteins that the research team developed previously. They used a small amount of a chemical, polyvinyl alcohol, to glue the nanofibers together into a lightweight foam-like material.

"This work provides a new route to fabricating environmentally friendly and multi-functional air filters made from abundant natural biomass," Zhong said. "I believe this technology is very important for people's health and our environment, and it should be commercialized."

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Ceramics that breathe oxygen at lower temperatures help us breathe cleaner air

Although much of the discourse on reducing vehicle emissions centres on electric vehicles (EV), their sales remain low -- with EV vehicles accounting for a mere 1% of car purchases in Japan in 2021. Meanwhile, the European Union is expected to pass stricter emission standards in the near future. This makes improving the performance and functionality of exhaust gas purification catalysts in petrol or diesel-powered vehicles a critical component in the push towards carbon neutrality.

Nearly all petrol or diesel cars are equipped with catalytic converters that remove harmful hydrocarbons, carbon monoxide and nitrogen oxide and convert them into safer gases such as nitrogen, carbon dioxide and water vapor. The toxic gases flow through a honeycomb structure, coated with exhaust gas purifying catalysts.

Ceramics with an oxygen storage capacity (OSC) play a crucial role in the purification process. They help remove noxious gases and prevent the precious metals in catalytic converters from coarsening, which degrades their purification capabilities.

To improve their potential, however, a lower operating temperature is required. But scientists have struggled to achieve this since reducing the temperature to less than 500 ºC results in slower ion diffusion.

Now, a research group at Tohoku University's Graduate School of Engineering has developed a Cerium-Zirconium-based (Ce-Zr) oxide with excellent OSC at 400 ºC by controlling its crystal structure. The OSC at 400 ºC was higher than conventional materials by a factor of 13.5, even without precious metal catalysts.

"The key to our success was introducing a tiny amount of transition metals, such as iron, to the Ce-Zr-based oxides," said Professor Hitoshi Takamura, leader of the research group.

The 'transition metal doping' had two notable effects in the oxides. It accelerated the oxygen diffusion by easing the formation of oxygen vacancies and promoted cation ordering.

"Cation ordering tidies up the crystal structure and makes oxygen readily released," explained Takamura.

The iron doping reduced the cation-ordering temperature, which in turn enabled a larger surface area for the Ce-Zr-based oxides. This enhanced their durability and ability to purify toxic gases.

In the future, Takamura and his group hope to test the material by loading it with palladium on honeycomb supports.

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