Disposable e-cigarettes more toxic than traditional cigarettes

High levels of lead, other hazardous metals found in e-cigarettes popular with teens

University of California - Davis

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UC Davis Ph.D. candidate Mark Salazar, left, holds a disposable vape pod in the lab with Brett Poulin, a UC Davis assistant professor of environmental toxicology.

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Credit: Kat Kerlin, UC Davis

They may look like travel shampoo bottles and smell like bubblegum, but after a few hundred puffs, some disposable, electronic cigarettes and vape pods release higher amounts of toxic metals than older e-cigarettes and traditional cigarettes, according to a study from the University of California, Davis. For example, one of the disposable e-cigarettes studied released more lead during a day’s use than nearly 20 packs of traditional cigarettes.

The study, published June 25 in the journal ACS Central Science, noted that although most disposable e-cigarettes are illegal in the United States, they remain widely available. Most consumers of disposable e-cigarettes are teens or young adults, who are also highly susceptible to lead exposure. Inhaling certain metals can increase a person’s risk of cancer, respiratory disease and nerve damage.

“Our study highlights the hidden risk of these new and popular disposable electronic cigarettes — with hazardous levels of neurotoxic lead and carcinogenic nickel and antimony — which stresses the need for urgency in enforcement,” said senior author Brett Poulin, an assistant professor in the UC Davis Department of Environmental Toxicology. “These risks are not just worse than other e-cigarettes but worse in some cases than traditional cigarettes.” 

‘What are you smoking?’

First author Mark Salazar, a Ph.D. candidate in Poulin’s lab, first saw a disposable vape pod when he was visiting a friend. The pods are self-contained cartridges that hold a battery, e-liquid and heating coil. Salazar was curious: What, exactly, was his friend smoking? He brought the pod back to the lab at UC Davis and tested its vapor for metal concentrations.

“When I first saw the lead concentrations, they were so high I thought our instrument was broken,” Salazar said. “That sparked us into looking further into these disposables.”

The scientists analyzed the metal and metalloids inside seven types of disposable devices from three of the most popular brands. Using an instrument to activate the disposable e-cigarettes and heat the internal liquid, they created between 500 and 1,500 puffs for each device. They found:

• Some devices emitted surprisingly high concentrations of elements in the vapor, including antimony and lead.
• Levels of chromium, nickel and antimony increased as the number of puffs increased.
• Most of the disposable e-cigarettes tested released markedly higher amounts of metals and metalloids into vapors than earlier, refillable vapes.

The scientists then took apart the devices to trace the sources of the metals.

“We found that these disposable devices have toxins already present in the e-liquid, or they’re leaching quite extensively from their components into e-liquids and ultimately transferred to the smoke,” Salazar said. 

Leaded bronze alloy components in some devices leached nickel and lead to the e-liquid. Nickel was also released from heating coils, and antimony was present in unused e-liquids at high levels, both of which increase the risk of cancer.

Understudied health risks

The researchers also assessed the health risk for daily users. Vapors from three of the devices had nickel levels and two devices had antimony levels that exceeded cancer risk limits. Vapors from four of the devices had nickel and lead emissions that surpassed health-risk thresholds for illnesses besides cancer, such as neurological damage and respiratory diseases.

While the researchers tested only three of the nearly 100 disposable e-cigarette brands on the market, they say this initial work prompts concern given the popularity of disposable e-cigarettes, especially among adolescents.

The market is also outpacing science. Few studies of the relatively new devices are available, leaving consumers and regulators largely uninformed. The work underscores the need to enforce regulations around illegal e-cigarettes while continuing research to reveal the extent of the problem and its public health implications.

The study’s coauthors include Lalima Saini, Tran Nguyen, Kent Pinkerton, Amy Madi and Austin Cole of UC Davis.

The research was supported with funding from the UC Tobacco-Related Disease Research Program, the National Institute of Environmental Health Sciences T32 training program, and the University of California Agricultural Experiment Station.

  

Ph.D. candidate Mark Salazar holds a disposable vape pod in the lab at UC Davis, where he found high levels of metals, including lead, in the devices especially popular with teens.

Ph.D. candidate Mark Salazar, left, holds a disposable vape pod in the lab at UC Davis, where he found high levels of metals, including lead, in the devices especially popular with teens.

Mark Salazar of UC Davis opens a disposable e-cigarette, or vape pod, to show its internal components, including a metal coil battery and e-liquid. These components were found in some devices to leach hazardous metals into the inhaled vapor. 

Credit

Kat Kerlin/UC Davis

Journal

ACS Central Science

DOI

10.1021/acscentsci.5c00641 

Method of Research

Observational study

Article Title

Elevated toxic element emissions from popular disposable e-cigarettes: sources, life cycle, and health risks

Article Publication Date

25-Jun-2025

Metals found in disposable e-cigarette vapor could pose health risks

American Chemical Society

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Brightly colored inexpensive and disposable electronic cigarettes and vapes continue to gain popularity. These devices turn flavored nicotine-containing liquid into a vapor that people inhale over hundreds or thousands of puffs — commonly called vaping. Researchers report in ACS Central Science that after a few hundred puffs, some disposable vaping devices released higher amounts of metals and metalloids than older refillable e-cigarettes and traditional cigarettes, thereby raising a user’s risk of health problems.

“Our study highlights the hidden risk of these new and popular disposable electronic cigarettes — with hazardous levels of neurotoxic lead and carcinogenic nickel and antimony — which stresses the need for urgency in enforcement,” says Brett Poulin, the corresponding author of the study from the University of California, Davis.

Studies on early generations of refillable e-cigarettes (e.g., refillable pens, box mods and pods) found that their heating components could release metals such as chromium and nickel ions into the internal liquid that then becomes the vapor people breathe. Inhaling certain metals and metalloids is potentially harmful, increasing a person’s risk of cancer, respiratory disease and nerve damage.

Although marketing of most disposable e-cigarettes is not authorized by the U.S. Food and Drug Administration, the devices remain widely available. In the past few years, disposable e-cigarette sales have overtaken sales of older refillable vapes, but little is known about the elemental composition of vapors from the newer devices. So, Poulin and colleagues assessed popular disposable e-cigarette brands to evaluate the potential health risks they could pose to a user.

The researchers first identified the metal and metalloids inside seven disposable devices from three brands, comparing liquids with light and heavy levels of flavoring. The original unused liquids had low levels of ionic metals and metalloids, though some devices had surprisingly high levels of lead and antimony. The team traced the source of lead to leaded copper alloys used for non-heating components, which leach into the e-liquid. Antimony did not have a definable source.

Then they activated the disposable e-cigarettes, which heated the internal liquid and created between 500 and 1,500 puffs for each device. Analyses of the vapors determined that:

• The levels of ionic metals and metalloids including chromium, nickel, and antimony increased as the number of puffs increased, whereas concentrations of ionic zinc, copper, and lead were elevated at the start, and each device had different emissions.
• Compared with previous studies, most of the tested disposable e-cigarettes released higher amounts of metals and metalloids into vapors than older refillable vapes.
• One of the disposable e-cigarettes studied released more lead during a day’s use than nearly 20 packs of traditional cigarettes.

The researchers next assessed the health risk faced by a daily user of these devices. For two of the disposable vapes, the team collected toxicity information for chromium and antimony, substances that have non-toxic and carcinogenic forms. Only the non-toxic form of chromium, Cr(III), was present, but a mixture was observed between the less toxic form of antimony, Sb(V), and the carcinogenic form, Sb(III), in the vapors. However, nickel levels in vapors from three devices and Sb(III) levels in vapors from two devices exceeded cancer risk limits. The vapors from four of the devices had nickel and lead emissions that surpassed health risk thresholds for diseases other than cancer.

The researchers tested only three of the nearly 100 disposable e-cigarette brands available on store shelves. They say the results are concerning because of the current popularity and extensive use of disposable e-cigarette products, especially among adolescents and young adults.

The authors acknowledge support from the University of California Tobacco-Related Disease Research Program, the National Institute of Environmental Health Sciences T32 training program, and the California Agricultural Experiment Station.

The paper’s abstract will be available on June 25 at 8 a.m. Eastern time here: http://pubs.acs.org/doi/abs/10.1021/acscentsci.5c00641

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The American Chemical Society (ACS) is a nonprofit organization founded in 1876 and chartered by the U.S. Congress. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

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Journal

ACS Central Science

DOI

10.1021/acscentsci.5c00641 

Article Title

“Elevated Toxic Element Emissions from Popular Disposable E‑Cigarettes: Sources, Life Cycle, and Health Risks”

Article Publication Date

25-Jun-2025

AI models identify personality traits from written texts

Opening the “black box” of algorithms

University of Barcelona

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From left to right, experts Daniel Ortiz, David Saeteros and David Gallardo, at the University of Barcelona.

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Credit: UNIVERSITY OF BARCELONA

A research team at the University of Barcelona has shown how artificial intelligence (AI) models can detect personality traits from written texts, and for the first time has managed to analyse in detail how these systems make decisions. These results, published in the journal PLOs One, open up new perspectives for understanding how personality manifests itself in natural language and also how more transparent and reliable automatic detection tools can be built.

The paper is signed by three UB experts: David Saeteros and David Gallardo-Pujol, researcher and director, respectively, of the Individual Differences Lab Research Group (IDLab) of the Faculty of Psychology and the Institute of Neurosciences (UBneuro), and Daniel Ortiz Martínez, researcher at the Faculty of Mathematics and Computer Science.

Opening the “black box” of algorithms

The study has analysed how two advanced AI models, BERT and RoBERTa, process text data to detect personality characteristics following two main psychological frameworks: the Big Five personality trait system (openness to experience, responsibility, extraversion, agreeableness and emotional stability) and the Myers-Briggs Type Indicator (MBTI), an instrument that classifies people along the dimensions of extrovert-introvert, sensory-intuitive, thinking-feeling and thinking-feeling. “In psychology, there is a prevalent model of personality and other less validated models, which we use to understand and measure individual differences in behaviour, emotions and thinking”, the researchers explain about these two psychological frameworks.

The texts analysed in the study were obtained from two databases fed with questionnaires from both models (Big Five and MBTI), which had previously been classified according to the presence of indicators of the different personality traits and types that comprise them. Subsequently, researchers have used explainable AI techniques to observe the AI models and see which language patterns influence the identification of personality traits in these writings. “Explainability techniques allow us to ‘open the black box’ of algorithms, which ensures that predictions are based on psychologically relevant signals and not on artefacts in the data”, note the authors.

Specifically, they used a technique called integrated gradients, which allows them to identify exactly which words or phrases contribute to the prediction of a specific personality trait.

“This methodology has allowed us to visualize and quantify the importance of various linguistic elements in the model’s predictions”, they say. For example, they have observed that words such as hate, which would traditionally be associated with negative traits, can appear in contexts that actually reflect kindness (“I hate to see others suffer”). “Without understanding how the model interprets these words in context, we may draw the wrong conclusions”, they stress.

This approach guarantees the scientific validity of the performance of AI models, as it allows “verifying whether the models align with established psychological theories and also provides a solid basis for continuous improvement by ensuring that they are based on linguistic patterns that are genuinely related to the psychological constructs they are intended to measure”, he adds.

The limitations of the MBTI model

The study also highlighted the limitations of the MBTI model compared to the Big Five one, which shows a stronger basis for both automated personality analysis and classical psychometric analysis. “Despite being widely used in computer science and some applied fields of psychology, the MBTI model has serious limitations for automatic personality assessment, as our results indicate that the models tend to rely more on artefacts than on real patterns”, they note.

Applications of automatic personality detection

The use of automatic personality detection techniques with AI models can have a major impact on the field of personality psychology. “With these methods, psychologists will identify linguistic patterns associated with different personality traits that, with traditional methods, might go unnoticed. This can lead to more natural and less intrusive assessment methods, especially valuable for the study of large populations”, the researchers note.

In the clinical field, the authors point out that they can help in “initial assessment and follow-up of patients by focusing attention on changes in language or verbal expression as indicators of important psychological elements for therapy”. They also point out that they can play an important role in other areas: in personnel selection, in educational personalization, in social research — it would facilitate the analysis of large volumes of textual data — or in the development of virtual assistants and conversational agents, as it would help to create more natural and adapted interactions. “It is important to stress that all such applications should be based on scientifically sound models and incorporate the explainability techniques we have explored, to ensure ethical and transparent use”, they add.

Despite the potential, researchers believe that these models will not replace traditional personality tests in the short term, but will complement them and offer an additional and deeper perspective. “We see an evolution towards a multimodal approach, where traditional assessments are combined with natural language analysis, digital behaviour and other data sources to get a more complete picture of personality”, they note.

This integrative approach will, according to the researchers, build on the strengths of each methodology, providing a “richer and more nuanced view of the human personality”. In this sense, AI models can be “especially useful in contexts where traditional data collection is difficult or when large volumes of information need to be analysed efficiently”, they add.

Validating research in other contexts

The next steps in this study include extending the analysis to other text types, platforms, languages and cultures to confirm whether the patterns identified are consistent across different contexts. The researchers want to explore the application of these techniques to other psychological constructs beyond personality, such as emotional states or attitudes.

Researchers are also working to integrate multimodal data into these analyses — combining text with other forms of expression, such as voice or non-verbal behaviour, and using technologies such as automatic audio transcription (Whisper.ai) — as well as their application in real-life contexts. The team wants to “collaborate with clinicians and human resources professionals to evaluate the effectiveness of these tools in real-world settings, ensuring that they have a positive and ethical impact”, they conclude.
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Journal

PLOS One

DOI

10.1371/journal.pone.0323096 

Method of Research

Computational simulation/modeling

Subject of Research

People

Article Title

Text speaks louder: Insights into personality from natural language processing

Article Publication Date

18-Jun-2025

 

Spotting bad batteries before they malfunction

Drexel University researchers report noninvasive ultrasound battery diagnostics technique

Drexel University

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A recent uptick in battery-related fires has drawn attention to the challenge of identifying defects that can cause these catastrophic malfunctions, but are rarely obvious to the naked eye. In hopes of preventing the dangerous glitches that can cause batteries to overheat and catch fire, researchers from Drexel University have developed a standard testing process to give manufacturers a better look at the internal workings of batteries.

In a paper recently published in the journal Electrochimica Acta, the group presented methods for using ultrasound to monitor the electrochemical and mechanical functions of a battery — which would immediately reveal any damage or flaws that could lead to overheating and even cause “thermal runaway.”

“While lithium-ion batteries have been studied for nearly half a century and commercialized for over 30 years, we have only recently developed tools that can see inside with high resolution” said Wes Chang, PhD, an assistant professor and primary investigator of the Battery Dynamics Lab in Drexel’s College of Engineering, who supervised the project. “In particular, ultrasound has been adapted from other fields, such as geophysics and biomedical sciences, for battery diagnostics only in the past decade. Because it is such a new technique in the battery and electric vehicle industries, there is a need to teach battery engineers how it works and why it is useful.”

The team’s recent work strives to do this, by demonstrating a low-cost, accessible benchtop ultrasonic tool that it hopes can be easily implemented and used by battery engineers, including those who work at automotive companies producing electric vehicles.

According to a Consumer Affairs report individuals use three to four electronic devices powered by batteries each day — from laptops, phones and tablets, to power tools and electric transit, like bikes and scooters — a number that has doubled in the last five years. The rush to supply batteries for all of these devices has created a market for products that can be produced cheaper and faster. This is a concern, according to Chang, because it may allow low-quality cells to enter the market.

“While the vast majority of lithium-ion batteries today are high performing and safe, defects are bound to exist when thousands of cells are used within electric vehicles and there are millions of electric vehicles being produced every year,” Chang said.

The current safety and quality control processes for manufactured batteries rely heavily on visual inspection and performance testing of select battery cells after they come off the line. Manufactured batteries may also be X-rayed to generate a high-resolution interior image, but this is slow and expensive.

Manufacturers are required to follow these inspection and testing protocols, but with the scale at which batteries are being used, even a small design or manufacturing flaw that is missed can lead to a massive batch of defective batteries making their way into market.

By contrast, the method proposed by the Drexel team uses acoustic imaging — ultrasound — which is faster and less expensive than X-rays and can provide complementary information about the mechanical properties of the battery. Chang’s group reported using scanning acoustic microscopy technology to send low-energy sound waves through a commercial pouch cell battery.

Without affecting its internal operations or affecting its performance, the speed of the waves is altered as it passes through the various materials inside a battery. This allows researchers to get a complete, detailed and quick look at the chemical changes within battery materials as it is being used.

“By observing how the sound wave has changed upon interacting with the sample, we can deduce a number of structural and mechanical features,” they wrote in the report.

The process can help to detect structural defects or damage that could cause an electrical short, material deficiencies or imbalances that could hamper performance, as well as indicators that problems are likely to occur. One substance the scan is particularly good at detecting is gas, which is important because the presence of gas inside a battery is an indication of dry areas that could cause the cell to fail while it is being used.

The sensitivity of ultrasound makes it useful not just for detecting defects in manufacturing, but also for gauging how new battery chemistries fail in research and development labs. As part of the research, Chang’s group worked with research partners at SES AI, a lithium metal battery startup company. Deploying the testing platform at SES AI’s research and development site gave the engineers instantaneous access to data during the design and testing process which allowed them to make adjustments and corrections more quickly.

In addition to reporting their process for the ultrasound testing method, the team also developed open-source software to run the instrument and produce a rapid analysis of the resulting data.

“We hope that by lowering the barrier to entry, ultrasonic testing can become a routine part of battery research and development,” Chang said. “Battery scientists want to build better batteries, not develop new tools. We provide a user interface that is easy-to-use with regular software updates. This adds to the existing collection of tools that battery scientists have on hand for measuring and diagnosing next-generation battery performance.”

The group plans to continue improving the technology so that it can more easily scan battery electrodes, as well as cells, and produce more detailed three-dimensional images rather than the currently limited two-dimensional scans to better detect defects.

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Journal

Electrochimica Acta

DOI

10.1016/j.electacta.2025.146012 

Method of Research

Experimental study

Article Title

Design of a low-cost ultrasonic testing instrument for battery metrology

Article Publication Date

24-Jun-2025

 

Gone with the glaciers: Researchers track unprecedented ice loss

From the Canadian Rockies to the Swiss Alps, the acceleration of glacial melt is “falling off a cliff” due to warm, dry conditions and the phenomenon of glacial darkening.

Hakai Institute

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A study published today in Geophysical Research Letters reveals that glaciers in western Canada, the United States, and Switzerland lost around 12 percent of their ice between 2001 and 2024. A 2021 study in Nature showed that glacial melt doubled between 2010 and 2019 compared with the first decade of the twenty-first century. This new paper builds on that research, says lead author Brian Menounos, and shows that in the years since, glacial melt continued at an alarming pace.

“Over the last four years, glaciers lost twice as much ice compared to the previous decade,” says Menounos, a professor at the University of Northern British Columbia and a chief scientist at the Hakai Institute. “Glacial melt is just falling off a cliff.”

Warm, dry conditions were a major cause of loss across the study areas, as were impurities from the environment that led to glacial darkening and accelerated melt. In Switzerland, the main cause of darkening was dust blown north from the Sahara Desert; in North America, it was ash, or black carbon, from wildfires.

The research combined extensive aerial surveys with ground-based observations of three glaciers in western Canada, four glaciers in the US Pacific Northwest, and 20 glaciers in Switzerland, all of which are important for culture, tourism, and cool fresh water—and all of which are melting rapidly.

Snow and ice, when not obscured by dark particles, reflect back energy from the sun in a process known as the albedo effect. To dig deeper into the North American story, Menounos and his collaborators used satellite imagery and reanalysis data to look at declines in albedo. They found that albedo dropped in 2021, 2023, and 2024, but the biggest declines occurred in 2023—the worst wildfire season in Canadian history. 

“2023 was the year of record, no question,” Menounos says. 

In contrast to reflective white snow, a glacier covered in black carbon will absorb more radiation from the sun. This heats up glaciers and accelerates melting. At Haig Glacier in Canada’s Rocky Mountains, glacial darkening was responsible for nearly 40 percent of the melting between 2022 and 2023, the researchers found. Yet despite such evidence, physical processes like the albedo effect aren’t currently incorporated into climate predictions for glacier loss, so these masses of ice could be melting faster than we realize.

“If we’re thinking, Well, we have 50 years before the glaciers are gone, it could actually be 30,” Menounos says. “So we really need better models going forward.”

In the areas covered by this study, the impact of glacier loss on sea level rise is small, but a longer-term decline in glacial runoff could impact human and aquatic ecosystems, especially in times of drought, Menounos adds. 

In the shorter term, increased melting raises the risk of geohazards like outburst floods from newly formed glacier lakes. All of this poses questions around how communities should respond as well as plan for a future with less ice.

“Society needs to be asking what are the implications of ice loss going forward,” Menounos says. “We need to start preparing for a time when glaciers are gone from western Canada and the United States.”
 

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Contact

Brian Menounos
Professor, University of Northern British Columbia
Chief Scientist, Hakai Institute Airborne Coastal Observatory
(250) 960-6266 (office)
brian.menounos@unbc.ca

 

Media Kit

Download the media kit that includes this press release, the newly published paper, and photos with captions. 

About the Paper

“Glaciers in Western Canada‐conterminous US and Switzerland experience unprecedented mass loss over the last four years (2021–2024)” was published in Geophysical Research Letters in June 2025.

Menounos, B., Huss, M., Marshall, S., Ednie, M., Florentine, C., & Hartl, L. (2025). Glaciers in Western Canada‐conterminous US and Switzerland experience unprecedented mass loss over the last four years (2021–2024). Geophysical Research Letters, 52, e2025GL115235. 

https://doi.org/10.1029/2025GL115235
 

About the Partners

University of Northern British Columbia

The University of Northern British Columbia (UNBC) is a dynamic, research-intensive university that is consistently ranked among Canada’s best small universities. Offering excellent undergraduate and graduate learning experiences and research opportunities, UNBC conducts research that advances knowledge and contributes to the economic, social, and environmental well-being of the communities it serves. UNBC’s Department of Geography, Earth and Environmental Sciences is an innovative hub for exploring the complex interactions between people and the planet through integrative, experiential, and research-driven learning. Learn more at www.unbc.ca.

Hakai Institute

The Hakai Institute, part of the Tula Foundation, is a British Columbia–based scientific institution dedicated to advancing science on the coastal margin. Hakai pursues its mission from ice fields to oceans, leveraging its ecological observatories and other strategic locations on the province’s coast. The Hakai Institute partners with universities, NGOs, First Nations, government agencies, businesses, and local communities to move the needle on advancing long-term coastal research. Learn more at www.hakai.org.

Tula Foundation

The Tula Foundation is a British Columbia–based organization that harnesses science and technology to tackle urgent global issues. Tula takes a comprehensive approach to these challenges, from coastal biodiversity and public health to data management and mobilization. Along with rural healthcare in Guatemala, Tula’s work drives pivotal action for coastal conservation and ocean research in British Columbia and beyond. Learn more at www.tula.org.

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Journal

Geophysical Research Letters

DOI

10.1029/2025GL115235 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Glaciers in Western Canada‐Conterminous US and Switzerland Experience Unprecedented Mass Loss Over the Last Four Years (2021–2024)

Article Publication Date

25-Jun-2025