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Thursday, November 05, 2020
The burning question of Bonfire Night pollution
IMAGE: AN AIR FILTER BEFORE AND AFTER THE EXPERIMENT, SHOWING THE AMOUNT OF POLLUTING MATERIALS COLLECTED ON BONFIRE NIGHT 2017 view more
CREDIT: MICHAEL ADAMS
Bonfire Night celebrations contaminate our air with hugely elevated amounts of soot, scientists have found.
Researchers from the University of Leeds were monitoring air quality to determine whether soot created by fires and fireworks, known as black carbon, could help to create ice in clouds.
They found soot in the atmosphere around Guy Fawkes Night events was around 100 times its normal level.
Ice occurs naturally in clouds, but tiny particles of desert dust, soil dust, fungus and bacteria swept high into the air can cause supercooled water droplets in clouds to freeze around them. High concentrations of these ice-nucleating particles can cause clouds to freeze, potentially impacting the earth's climate.
The team carried out experiments on 5 November 2016 into the early hours of the following day, and in 2017 from November 4 and 5, filtering the air with samples taken hourly. Equipment was set up on the balcony of the School of Earth and Environment building, 15m from ground level and more than 0.5 km from any individual bonfires or firework displays, to give a representative view of the air quality across the city.
The filters were washed and the liquid subjected to different temperatures to replicate atmospheric conditions.
The researchers discovered black carbon produced on Bonfire Night did not act as ice nucleating particles - but they did not expect to see such high levels of the polluting matter in the atmosphere.
Black carbon particles are so small, they can penetrate deep into the lungs and cause irritation. Long term exposure can cause harmful effects on the heart and lungs and contributes to millions of deaths worldwide each year.
The paper, A major combustion aerosol event had a negligible impact on the atmospheric ice-nucleating particle population, has been published in Journal of Geophysical Research: Atmospheres today.
The research was funded by the European Research Council.
Lead author Michael Adams, Research Fellow in Atmospheric Ice Nucleation, said: "Our measurements showed that whilst pollution emitted on Bonfire Night shouldn't have any effect on whether clouds are liquid or ice, the elevated concentrations of soot and other pollutants in the atmosphere should be a warning to those with pre-existing health conditions, as the aerosol particles are in the size range where they can enter the lungs and cause problems."
Research supervisor Benjamin Murray, Professor of Atmospheric Science in Leeds' School of Earth and Environment, said: "Bonfire Night is a massive pollution event across the UK. People with existing health problems, such as heart and lung conditions, are at increased risk."
"The impact on clouds and climate was not clear. The good news is that Bonfire Night does not impact the formation of ice in supercooled cloud droplets. But, we know that BC causes climate warming in other ways.
"I was surprised to see levels of black carbon so persistently high for so long on multiple nights. It was striking how poor air quality was on Bonfire Night."
Weather conditions can affect how long the particles remain in the air. The team found the pollution was flushed out of the city within a few hours during the 2016 experiment, due to a brisk wind from the north.
But in 2017 the air was relatively still and the pollution lingered into the next day.
While providing insight into the levels of black carbon emitted on Bonfire Night, the team's discoveries have also contributed to the understanding of different sources of ice nucleating particles - a key research area in climate science.
Prof Murray said: "Clouds containing supercooled water and ice are first order importance for climate. Vast cloud systems made of a mixture of ice and water over the world's oceans buffer the warming effect of CO2.
"But the buffering capacity depends on how much ice is in them, which in turn depends on the concentration and distribution of ice nucleating particles.
"We found that aerosol particles emitted during the celebration are not as effective at nucleating ice as aerosol particle already present in the atmosphere.
"We conclude that aerosol particles emitted from combustion processes such as those observed on Bonfire Night are not an important source of ice nucleating particles."
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Further information
Picture:
An air filter before and after the experiment, showing the amount of polluting materials collected on Bonfire Night 2017
(Credit: Michael Adams)
For further details, contact University of Leeds press officer Lauren Ballinger at L.ballinger@leeds.ac.uk
University of Leeds
The University of Leeds is one of the largest higher education institutions in the UK, with more than 38,000 students from more than 150 different countries, and a member of the Russell Group of research-intensive universities. The University plays a significant role in the Turing, Rosalind Franklin and Royce Institutes.
We are a top ten university for research and impact power in the UK, according to the 2014 Research Excellence Framework, and are in the top 100 of the QS World University Rankings 2021.
The University was awarded a Gold rating by the Government's Teaching Excellence Framework in 2017, recognising its 'consistently outstanding' teaching and learning provision. Twenty-six of our academics have been awarded National Teaching Fellowships - more than any other institution in England, Northern Ireland and Wales - reflecting the excellence of our teaching.
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Analysis reveals high burden of musculoskeletal disorders across the globe
Musculoskeletal disorders--which affect muscles, tendons, ligaments, bones, and joints--can severely affect individuals' physical and mental health, and they're especially prevalent among aging adults. Although many researchers are studying these conditions and their rates in different regions of the world, no study to date has provided an overview of the burden of all musculoskeletal disorders. Investigators have now done so in Arthritis & Rheumatology, an official journal of the American College of Rheumatology.
For the analysis, researchers examined data from the Global Burden of Disease Study 2017, which assessed the extent of diseases and injuries across 21 regions and 195 countries and territories from 1990 to 2017. Musculoskeletal disorders included rheumatoid arthritis, osteoarthritis, low back pain, neck pain, gout, and related conditions.
The team found that there were approximately 1.3 billion prevalent cases and 121,300 deaths due to musculoskeletal disorders in 2017, as wells as 138.7 million disability-adjusted life years, or the number of years lost due to ill-health, disability, or early death. The burden of these diseases generally increased with age for both sexes, was more prevalent among females, and was higher in developed countries.
"Our study describes the enormous global burden of disability from musculoskeletal conditions in a single paper," said senior author Rachelle Buchbinder, MD, of the Cabrini Institute and Monash University, in Australia. "These conditions are under-recognized despite their enormous costs to individuals, the economy, and the health system. Also, there has been a lack of any significant decline in the burden from these conditions over time, which means that there is still insufficient emphasis on addressing the problem."
Dr. Buchbinder noted that policy makers must be made aware of the size of this growing problem, especially in light of rapidly aging populations around the world. "A global response is needed, and this should be integrated with other strategies that can address some of the modifiable and important risk factors of musculoskeletal disorders, including obesity, poor nutrition, smoking, and sedentary lifestyles," she said. "As well, there should be an emphasis on reducing low-value care for some of the most burdensome conditions such as low back pain and osteoarthritis that is contributing to the problem."
The authors also stressed the need for standardized methods for collecting data on the prevalence and impact of musculoskeletal disorders across the world.
Additional information
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Full Citation: "Prevalence deaths and disability adjusted life years (DALYs) due to musculoskeletal disorders for 195 countries and territories 1990-2017." Saeid Safiri, Ali-Asghar Kolahi, Marita Cross, Catherine Hill, Emma Smith, Kristin Carson-Chahhoud, Mohammad Ali Mansournia, Amir Almasi-Hashiani, Ahad Ashrafi-Asgarabad, Jay Kaufman, Mahdi Sepidarkish, Seyed Kazem Shakouri, Damian Hoy, Anthony D. Woolf, Lyn March, Gary Collins, and Rachelle Buchbinder, MD. Arthritis & Rheumatology; Published Online: November 5, 2020. (DOI: 10.1002/art.41571).
URL Upon Publication: http://doi.
Disclosures: The GBD 2017 Study was funded by Bill and Melinda Gates Foundation; however, the organization was not involved in any way in the preparation of the Arthritis & Rheumatology article. The report was supported by Shahid Beheshti University of Medical Sciences, Tehran, Iran (grant No 21740-4-7). Rachelle Buchbinder is supported by an Australian National Health and Medical Research Council (NHMRC) Senior Principal Research Fellowship. Marita Cross is supported by the Institute of Bone and Joint Research and the Global Alliance for Musculoskeletal Health.
Author Contact: media@monash.edu or +61 3 9903 4840
About the Journal
Arthritis & Rheumatology is an official journal of the American College of Rheumatology (ACR) and covers all aspects of inflammatory disease. The American College of Rheumatology (http://www.
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Researchers study strength-training gender gap, possible solutions
UNIVERSITY PARK, Pa. -- Strength training is an important part of any exercise routine, but some women may not be getting the recommended hours. New Penn State research discovered some of the barriers preventing women from strength training, as well as some solutions to overcoming those obstacles.
In a study of college students, researchers found that women were less likely than men to participate in muscle-strengthening activities and use weight areas in campus recreation facilities. But, the researchers also found that women were more likely to feel uncomfortable using campus recreation facilities -- and weight areas in particular.
Oliver Wilson, graduate student in kinesiology, said the study suggests that there are gender differences in both physical exercise habits and campus facility use. He added that there may be opportunities for school administrators, policy makers and others to help provide equal opportunities for everyone.
"Ideally, all students -- regardless of gender identity, race and ethnicity, sexual orientation, religion, and/or socio-economic status -- should participate in muscle-strengthening activities," Wilson said. "Implementation and enforcement of policies, facility design and equipment layout, supportive social environments, and other opportunities for students to build the skills and confidence to participate in muscle-strengthening activities are necessary to provide equitable opportunities for all."
According to the researchers, previous research has consistently found disparities in physical activity between men and women. Additionally, prior work has found certain areas of campus recreational facilities to be highly gendered spaces.
For example, the researchers said women may feel constrained from using the free weights section of some facilities due to a lack of knowledge or confidence, crowded spaces, or unsolicited advice from male peers.
Melissa Bopp, associate professor of kinesiology, said that because a person's college-age years are an important period for establishing good exercise habits, they wanted to investigate potential reasons and solutions for these disparities.
"It was important to ask these questions because we know that physical activity participation typically declines across students' time in college despite the access they may have to facilities," Bopp said. "It's important to understand why this decline happens before we can create strategies for promoting physical activity."
The researchers recruited 319 college students for the study. The participants were asked to complete a survey designed to measure physical activity and their use and comfort in using campus recreational facilities, as well as their reasons and potential solutions for feeling uncomfortable using the facilities.
According to Wilson, meaningful differences in physical activity behaviors, facility use, and comfort levels in using facilities between male and female students appeared once the data were analyzed.
"Women reported less muscle-strengthening activity, lower frequency of both weight use and informal sport participation, and higher frequency of cardio and group exercise participation," Wilson said. "Women also reported lower comfort using facilities in general -- as well as machine weights, free weights, and indoor running tracks -- compared to men."
The researchers found that the presence and behaviors of men, feeling like they don't know how to properly use the equipment, and feeling self-consciousness emerged as common themes women gave for not using weight equipment.
"It is uncomfortable using certain parts of the recreational facilities because it is often divided into mostly women using the cardio machines and men in the weight section," according to one anonymous participant quoted in the study. "So, even though I like using weights, it can be a little intimidating going into a room full of guys by myself to work out with weights."
The participants also provided potential solutions that could help them feel more comfortable participating in muscle strengthening activities. Themes included the addition of women's-only sections or hours, as well as implementing sexual harassment policies.
Bopp said the study -- recently published in the Journal of American College Health -- suggests that making campus recreational facilities more open and welcoming to all students may be key to ensuring equitable opportunities for all to get the exercise they need.
"I think that it's important to understand that despite the fact that we have wonderful resources for physical activity on our campus, they sometimes don't feel accessible to everyone," Bopp said. "Whether it's the culture or policies that need to be changed to create a welcoming environment remains to be seen, but it also informs us that physical activity behavior is complex -- just having a place to be active doesn't ensure exercise participation."
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David Guthrie, associated professor of education, and Crystal Colinear, undergraduate kinesiology student, also participated in this work.
ACA results in fewer low-income uninsured, but non-urgent ER visits haven't changed
Since the Affordable Care Act's (ACA) Medicaid expansion program went into effect 10 years ago, the U.S. has seen a larger reduction in the number of uninsured low-income, rural residents, compared to their urban contemporaries.
But the likelihood of repeated visits to emergency rooms for non-urgent reasons has not decreased.
That's what Washington State University's Bidisha Mandal discovered in a new paper published in the journal Applied Economic Perspectives and Policy.
"Using emergency departments for non-urgent care is often a sign that people don't have convenient access to doctors," said Mandal, a professor in WSU's School of Economic Sciences. "With more people having insurance under the ACA, demand has increased for doctors. Supply seems to have gone up in cities, but not in rural areas."
Non-urgent visits put an additional strain on emergency rooms, and cost more for patients as well, she said.
One potential reason that non-urgent emergency room visits haven't decreased with more insurance is that Medicaid reimbursements for doctors are lower than other insurances. Physicians don't have a monetary incentive to increase the number of low-income patients they see.
"I was surprised to see that low-income rural residents actually had more insurance gains than urban residents," Mandal said. "But providers just don't have enough incentive to accept new Medicaid patients."
Low-income people benefited from the ACA's Medicaid expansion, and the Supreme Court ruling that made the expansion optional for states allowed researchers to compare outcomes between states that accepted or rejected the expansion, Mandal said.
She also found that the number of annual checkups has increased for low-income people in rural areas. But those additional visits haven't led to fewer non-urgent ER visits.
Mandel hopes policymakers looking to improve the ACA will read papers like hers to see and fix weaknesses in the law.
"There are definite gaps in the ACA, and I hope this paper helps fill some of them," Mandal said. "Having access to proper medical care is really important for our entire population."
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Researchers urge healthcare providers to routinely ask patients about cannabis use
Discussing use with chronic pain patients who use opioids is especially important
Nurses and other healthcare providers should talk to patients about their cannabis use the same way they talk about other habits like smoking and drinking: routinely and without judgment.
That should happen, but too often doesn't, said Marian Wilson, registered nurse and associate professor at the Washington State University College of Nursing. She is the lead author on a paper published recently in the journal Pain Management Nursing about shared decision-making in talking about cannabis use.
"We want this paper to guide providers in how they can start opening up this conversation and normalizing it," Wilson said.
The shared decision-making model starts with either the patient or the provider bringing up the topic of cannabis use, then moving on to specifics about that patient's situation, benefits, and risks of cannabis use based on research and evidence, and finally formulating a plan.
"Central to patient-centered conversations is understanding the top priorities of patients," Wilson writes. "Researchers have suggested that clinicians should ask 'What matters to you?' as well as 'What is the matter?'"
Some studies have suggested cannabis use is beneficial to patients with chronic pain who are also using opioids, so many in that patient population are using cannabis or considering it, Wilson said. That's why it's especially important for providers working in pain management to discuss the subject, though patients may be reluctant to disclose cannabis use because they might have been penalized in the past.
Wilson says providers face real challenges in obtaining current, evidence-based information on the benefits and risks of cannabis use. The paper calls for the creation of a centralized, noncommercial, scientific repository of information, research, and best practices on cannabis use. Such a resource will become more important as cannabis legalization spreads nationwide.
"We want providers to ask people about their cannabis use and we want patients to feel comfortable talking about it, but right now many don't," Wilson said.
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For more information: "Shared Decision-Making for Patients Using Cannabis for Pain Symptom Management in the United States," Marian Wilson, PhD, MPH, RN-BC; Tracy Klein, PhD, FNP, ARNP, FAANP, FRE, FAAN; Ross J. Bindler, PharmD; Louise Kaplan, PhD, ARNP, FNP-BC, FAANP, FAAN, Pain Management Nursing.
Health care use drops during pandemic; switch to telemedicine creates disparities
Switch to telemedicine was not enough to offset reductions in in-person care
During the first two months of the pandemic lockdown, Americans dramatically reduced their use of preventive and elective health care, while increasing use of telemedicine -- but the switch was not enough to offset reductions in in-person care, according to a new study.
The analysis, one of the first to quantify the cuts in elective medical care experienced in March and April, found that the number of mammograms and colonoscopies -- diagnostic procedures that cannot be done via telehealth -- dropped by more than 65% during the period. Overall health care utilization declined by 23% in March and by 52% in April.
Smaller cuts in in-person care and lower rates of telemedicine use were observed among patients who reside in lower-income or predominately non-white zip codes. Researchers say the findings are another example of disparities in health care that have worsened during the coronavirus pandemic.
The study, published online by the journal JAMA Network Open, is based on medical records from more than 5 million Americans who have private health insurance.
"This adds detailed evidence to the anecdotal reports that Americans quit going to see the doctor when the pandemic shutdown started," said Christopher Whaley, the study's lead author and a policy researcher at RAND, a nonprofit research organization. "If important visits are only delayed for a few months, there will likely be no harm. But if patients do not get important screenings, there could be long-term negative health consequences."
Most studies about the change in medical care since the beginning of the pandemic shutdown have used information from a single health system or geographic market to observe changes in use of medical services.
The new study used insurance claims data from 2018 to 2020 from about 200 employers across all 50 states.
Researchers found that for March and April 2020, utilization of colonoscopy decreased by nearly 70% relative to rates observed in March and April 2019. Relative reductions for mammograms was 67% among women ages 46 to 64.
Blood sugar tests dropped by more than 50%, vaccines among children under age 2 dropped by 22% and angioplasty procedures dropped by nearly 17%. A small drop was seen in chemotherapy treatments. In addition, musculoskeletal surgery, cataract surgery and MRIs all dropped by 45% or more.
Use of prescription drugs for high cholesterol and diabetes saw small drops, while use of asthma medications increased by 11% over March and April.
During the same period, telemedicine visits skyrocketed, increasing by more than 4,000% in April 2020 as compared to April 2019. But the increase in telemedicine visits replaced only about 40% of the decline in medical office visits.
Researchers found that patients who resided in lower-income or predominately non-white zip codes had an increase in telehealth visits that was about a third lower than those who lived in the wealthiest neighborhoods.
"The extent to which access barriers to telemedicine contribute to lower rates of in-person care deferral, and thus increases in potential exposure to COVID-19, should be examined in future work," Whaley said.
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Support for the study was provided by the National Institute on Aging and the National Cancer Institute.
Other authors of the study are Megan F. Pera, Jennie Chang, Julia Velasco and Heather K. Hagg, all of Castlight Health, Jonathan Cantor of RAND, Neeraj Sood of USC, and Dena M. Bravata of Castlight Health and the Center for Primary Care and Outcomes Research at Stanford University.
RAND Health Care promotes healthier societies by improving health care systems in the United States and other countries.
Changes in health services use among commercially insured US populations during COVID-19 pandemic
What The Study Did: Researchers examined whether the first two months of the COVID-19 pandemic were associated with changes in non-COVID health care use among a large population of individuals with employer-sponsored insurance, specifically preventive services (e.g., pediatric vaccinations), elective services (e.g., orthopedic surgery) and nonelective services (e.g., labor and delivery care) in March and April 2020 compared with the same months in 2018 and 2019.
Authors: Christopher M. Whaley, Ph.D., of the RAND Corporation in Santa Monica, California, is the corresponding author.
To access the embargoed study: Visit our For The Media website at this link https:/
(doi:10.1001/jamanetworkopen.2020.24984)
Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
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Media advisory: The full study and commentary are linked to this news release.
Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time http://jamanetwork.
About JAMA Network Open: JAMA Network Open is the new online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.
Medicaid expansion linked to lower mortality rates for three major types of cancer
- Expansion of Medicaid eligibility under the Affordable Care Act is associated with decreased mortality for patients with newly diagnosed breast, lung, or colorectal cancer.
- The mortality improvement was due to earlier stage of diagnosis in states that have expanded Medicaid.
BOSTON - In states that have expanded Medicaid availability as part of the Affordable Care Act (ACA), mortality rates for three major forms of cancer are significantly lower than in states that have not expanded their Medicaid, a new study by researchers at Dana-Farber Cancer Institute, Brigham and Women's Hospital, and Harvard University shows.
Data from the study, published online today in JAMA Network Open, suggest that the improvement in mortality results from cancers being diagnosed at an earlier stage in states with Medicaid expansion. Early detection of cancer is often critical to successful treatment of the disease.
The ACA, passed in 2010, gave states the option of expanding eligibility for Medicaid - the government-funded health insurance program for low-income families and individuals - to nonelderly adults with incomes at or below 138% of the federal poverty level. Previous studies involving cancer patients have shown Medicaid expansion to be associated with fewer uninsured patients, increased screening, and stage of disease diagnosis. (Currently, 39 states have expanded Medicaid programs.)
"There has been little research into the impact of Medicaid expansion on cancer mortality [the time from initial cancer diagnosis to death]," says the lead author of the new study, Miranda Lam, MD, MBA, of Dana-Farber, Brigham and Women's Hospital, and Harvard T.H. Chan School of Public Health. "It's been thought that expansion might improve mortality by fostering earlier detection, earlier stage of diagnosis, and improved access to treatment. On the other hand, it could worsen mortality by creating an influx of newly covered patients that strains hospitals' resources."
For the study, researchers used the National Cancer Database to track 523,802 patients across the country who were newly diagnosed with breast, lung, or colorectal cancer from 2012 through 2015. They compared mortality rates for these patients in states that expanded their Medicaid programs and those that did not. (Twenty-four states and the District of Columbia expanded their programs on Jan. 1, 2014.)
"We found that Medicaid expansion was associated with a significant decrease in mortality compared to states without such expansion," Lam remarks. The expansion group had a 2% decline in hazard of death from the pre- to the post-expansion period. The non-expansion group, by contrast, showed no change in mortality.
If the 2% reduction was achieved in all states with expanded Medicaid, then among the approximately 69,000 patients diagnosed with cancer in those states, 1,384 lives would be saved yearly, researchers calculated.
The biggest difference between the two groups was in patients whose cancers hadn't reached a metastatic stage and are considered curable. When investigators adjusted for the stage at which cancers were diagnosed, improvements in mortality were no longer seen - whether between expansion and non-expansion states or between the pre-expansion and post-expansion period. This suggests that the decline in mortality associated with Medicaid expansion is a byproduct of diagnosing cancer at an earlier stage.
"Increased Medicaid coverage may remove barriers to accessing the healthcare system for screening and timely symptom evaluation, and that can translate into better outcomes for patients," Lam comments.
The investigators also found that the decrease in mortality in Medicaid-expansion states occurred across population groups. "We were reassured to find that patients living in areas of the lowest quartile of median household income showed a modest decrease in mortality after Medicaid expansion," Lam observes. "We also found that the mortality improvements occurred in both Black and white populations."
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The senior author of the study was Nancy Keating, MD, MPH, of Brigham and Women's and Harvard Medical School. Co-authors are Jessica Phelan, MS, and Ashish Jha, MD, MPH, of Harvard T.H. Chan School of Public Health; and John Orav, PhD, of Brigham and Women's and Harvard T.H. Chan School of Public Health.
The study was conducted with the support of a KL2 award from Harvard Catalyst | The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health Award KL2 TR002542).
About Dana-Farber Cancer Institute
Dana-Farber Cancer Institute is one of the world's leading centers of cancer research and treatment. Dana-Farber's mission is to reduce the burden of cancer through scientific inquiry, clinical care, education, community engagement, and advocacy. We provide the latest treatments in cancer for adults through Dana-Farber/Brigham and Women's Cancer Center and for children through Dana-Farber/Boston Children's Cancer and Blood Disorders Center. Dana-Farber is the only hospital nationwide with a top 10 U.S. News & World Report Best Cancer Hospital ranking in both adult and pediatric care.
As a global leader in oncology, Dana-Farber is dedicated to a unique and equal balance between cancer research and care, translating the results of discovery into new treatments for patients locally and around the world, offering more than 1,100 clinical trials.
Crystals reveal the danger of sleeping volcanoes
A new method shows that it's now possible to estimate the volume of magma stored below volcanoes providing essential information about the potential size of future eruptions
IMAGE: CATHODOLUMINESCENCE IMAGE OF ZIRCON CRYSTALS FROM NEVADO DE TOLUCA VOLCANO IN MEXICO view more
CREDIT: UNIGE/WEBER
Most active volcanoes on Earth are dormant, meaning that they have not erupted for hundreds or even thousands of years, and are normally not considered hazardous by the local population. A team of volcanologists from the University of Geneva (UNIGE), working in collaboration with the University of Heidelberg in Germany, has devised a technique that can predict the devastating potential of volcanoes. The scientists used zircon, a tiny crystal contained in volcanic rocks, to estimate the volume of magma that could be erupted once Nevado de Toluca volcano (Mexico) will wake up from its dormancy. Up to 350 km3 of magma --about four times the volume of water stored in Lake Geneva-- are currently lying below Nevado de Toluca and their eruption could bring devastation. The new technique, applicable to most types of volcano across the globe, is described in the scientific journal Nature Communications.
The largest volcanic eruptions in the last 100 years were sourced from volcanoes that do not erupt frequently and therefore fly under the "radar" of scientists. Yet today, 800 million people around the world live close to volcanoes and are potentially at risk. A determining factor for the dangerousness of volcanoes is the volume of eruptible magma stored in their bellies, as this is related to the magnitude of future eruptions. Unfortunately, this magma is stored at inaccessible depths of 6-10 km and cannot be directly measured.
Tiny watches with a thermometer
The UNIGE volcanologists used a new approach combining zircon geochronology and thermal modelling to determine the volume of potentially-eruptible magma present in the volcanic reservoirs. "Zircon is a small crystal found in rocks erupted by volcanoes, and it contains uranium and thorium", begins Gregor Weber, a postdoctoral fellow at UNIGE and co-author of the study. "The decay of these radioactive elements allows us to date when they crystallised. Additionally, zircon crystallises only in a specific temperature range. With these two parameters, we can determine how fast the magma is cooling below a volcano. Like a pot of water, the larger the pot, the more time it takes to cool it. We analysed the zircons erupted over the last 1.5 million years by Nevado de Toluca thus determining the evolution of temperature of the magma stored below the volcano over time. This information can be converted into a volume of magma using thermal modelling." This approach has a resolution two times higher than that of existing techniques.
Sleeping monster
The methodology in the study was applied to the Mexican volcano Nevado de Toluca, also called Xinantécatl, a representative example of a dormant volcano located in the vicinity of Mexico City. The results were used to determine the maximum possible size of a future eruption from this volcano, which with 350 km3 could have potentially devastating effect. "The system can quickly wake up if the deep magma supply starts again," warns Weber.
Guiding the radars
This finding is essential for assessing volcanic risk quantitatively. "Knowing the size of a volcanic reservoir is important to identify volcanoes that are most likely to produce a large magnitude eruption in the future. Our method is a new way to evaluate the candidates for such eruptions," explains Weber. This approach is applicable to most types of volcanoes, whether active or dormant, and provides valuable insights into which volcanic systems need to be monitored more closely.
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