Large dogs emit carbon dioxide and ammonia at rates similar to humans

FacebookXLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

These adorable furry scientists (small on the left; big on the right) accompanied their owners to have their impact on indoor air quality measured.

view more 

Credit: Adapted from Environmental Science & Technology 2026, DOI: 10.1021/acs.est.5c13324

Dogs come in all shapes and sizes: from giant fluffy Newfoundlands to tiny short-haired Chihuahuas. And many furry companions like to spend their days inside near their humans. An initial study published in ACS’ Environmental Science & Technology reports that dogs — both big and small — impact indoor air quality. The researchers found that small active dogs produced more airborne particles, but larger animals released more microbes into the air than people did.

“Pets are part of our indoor environment. By quantifying what dogs add to indoor air, we can build more realistic indoor air quality and exposure models and better inform ventilation strategies — without blaming pets or discouraging pet ownership,” says Dusan Licina, the corresponding author of the study.

Owning a dog has been shown to boost a person’s mental health, but the effect on overall physical health is less clear. To explore one aspect of this, Licina and colleagues wanted to see how these animals impact indoor air quality — an especially important issue for pet owners who spend most of their time inside. The researchers measured airborne pollutants, including gases, particulate matter and microbes, released from small and large dogs in a controlled lab environment and compared them to emissions from human owners.

The team compared a group of four small dogs (all Chihuahuas) to a group of three large dogs (a Tibetan Mastiff, a Newfoundland and an English Mastiff). Each group was tested separately with an owner in the room, whose emissions were also measured separately. Results showed that:

• Large dogs emitted carbon dioxide and ammonia at rates similar to humans and at substantially higher rates than small dogs.
• Both small and large dogs released more airborne particulate matter (1 nanometer wide to 10 micrometer wide) than the owners, with the small dogs producing the most, which the researchers say is likely because they were most active during the experiments.
• Big dogs released the most bacteria and fungi into the air, and many of these microorganisms originated from an outdoor environment, which changed the indoor microbial composition in ways that humans don’t.

These findings indicate that dogs, especially big dogs, could impact household air quality at a level similar to or more than humans. Licina adds that the results also suggest dogs act as mobile transport vectors, carrying and redistributing particles and microbes from other environments into indoor spaces. In the future, the researchers plan to study emissions from other indoor pets, such as cats, rabbits and rodents.

The authors say that it’s important to start including pet emissions when designing ventilation and air quality control systems for healthier indoor environments, “not just for humans, but for the animals that live alongside them,” as they conclude in their paper.

Many older adults improve over time

 

Aging in later life is often portrayed as a steady slide toward physical and cognitive decline. But a new study by scientists at Yale University suggests an alternate narrative — that older individuals can and do improve over time and their mindset toward aging plays a major part in their success.

Analyzing more than a decade of data from a large, nationally representative study of older Americans, lead author Becca R. Levy, a professor of social and behavioral sciences at the Yale School of Public Health (YSPH), found that nearly half of adults aged 65 and older showed measurable improvement in cognitive function, physical function, or both, over time.

The improvements were not limited to a small group of exceptional individuals and, notably, were linked to a powerful but often overlooked factor: how people think about aging itself.

“Many people equate aging with an inevitable and continuous loss of physical and cognitive abilities,” said Levy, an international expert on psychosocial determinants of aging health. “What we found is that improvement in later life is not rare, it’s common, and it should be included in our understanding of the aging process.”

The findings are published in the journal Geriatrics.

For the study, the researchers followed more than 11,000 participants in the Health and Retirement Study, a federally supported longitudinal survey of older Americans. The research team tracked changes in cognition using a global performance assessment, and physical function using walking speed — often described by geriatricians as a “vital sign” because of its strong links to disability, hospitalization, and mortality.

Over a follow-up period of up to 12 years, 45% of participants improved in at least one of the two domains, according to the study. About 32% improved cognitively, 28% improved physically, and many experienced gains that exceeded thresholds considered clinically meaningful. When participants whose cognitive scores remained stable over that period (rather than declining) were included, more than half defied the stereotype of inevitable deterioration in cognition.

“What’s striking is that these gains disappear when you only look at averages,” said Levy, author of the book “Breaking the Age Code: How Your Beliefs About Aging Determine How Long & How Well You Live.” “If you average everyone together, you see decline. But when you look at individual trajectories, you uncover a very different story. A meaningful percentage of the older participants that we studied got better.”

The authors also examined potential reasons for why some people improve and some do not. They hypothesized that an important factor could be participants’ baseline age beliefs — or, specifically, whether they had assimilated more positive or more negative views about aging by the start of the study. In support of this hypothesis, they found that those with more positive age beliefs were significantly more likely to show improvements in both cognition and walking speed, even after accounting for factors such as age, sex, education, chronic disease, depression, and length of follow-up.

The findings build on Levy’s stereotype embodiment theory, which posits that age stereotypes absorbed from culture — through a range of domains including social media and advertisements — eventually become self-relevant and biologically consequential. Levy’s prior studies have found negative age beliefs predict poorer memory, slower walking speed, higher cardiovascular risk, and biomarkers associated with Alzheimer’s disease.

The current study shows that those who have assimilated more positive age beliefs often show improvement, Levy said.

“Our findings suggest there is often a reserve capacity for improvement in later life,” she said. “And because age beliefs are modifiable, this opens the door to interventions at both the individual and societal level.”

The improvements were not limited to people who started out with impairments. Even among participants who had normal cognitive or physical function at baseline, a substantial proportion improved over time. That challenges the assumption that later-life gains reflect only people getting better after being sick or rebounding from earlier setbacks, the authors said.

The authors hope their findings will reverse the popular perception that continuous decline is inevitable and encourage policy makers to increase their support for preventive care, rehabilitation, and other health-promoting programs for older persons that draw on their potential resilience.

Wearing a weighted vest to strengthen bones? Make sure you’re moving

 

It’s encouraging news for people trying to lose weight safely, especially older adults who want to drop pounds without losing bone or muscle mass. 

The study, “Does time spent upright moderate the influence of a weighted vest on change in bone mineral density during weight loss among older adults,” appears in the peer-reviewed journal Frontiers in Aging.

Weighted vests can provide an external load equal to the amount of weight lost. Replacing that weight by wearing a vest can: 

• Help the body prevent metabolic slowdown, assisting with weight-loss maintenance.

• Preserve muscle and bone, which is particularly important as we age. Losing bone and muscle increases the risk for fracture and disability.  

Researcher Jason Fanning, lead author of the study and associate professor of health and exercise science, analyzed data from Wake Forest University’s INVEST in Bone Health for this study. The randomized, controlled trial led by Wake Forest colleague Kristen Beavers looked at whether wearing a weighted vest could help preserve bone mineral density during one year of weight loss. Participants were divided into three groups, and the weighted vest group wore the vest at least eight hours each day. 

What Fanning found:

• Weighted vest plus weight loss group: More time spent standing or stepping yielded positive changes in bone mineral density.

• Weight loss alone group: Standing or stepping more often showed negative changes in bone mineral density.

• Weight loss plus resistance training group: Time spent upright didn’t influence bone mineral density.

The researchers believe that spending more time upright exposes the wearer to more weight from the vest, thus reaping more benefits. The positive changes in bone density in the weighted vest group were promising enough that the INVEST research team is designing a new study. It will explore whether encouraging people to move more often boosts a weighted vest’s effectiveness in preserving bone mass.

“If we're going to be putting vests on people, we need to train those people to be up and moving,” said Fanning, who also is a primary investigator in a current study looking at how movement affects pain from arthritis. “A vest can be a great tool. But, like any tool, it's not going to do the work for you." 

Ultra-processed foods in preschool years associated with behavioural difficulties in childhood

 

A team led by researchers at the University of Toronto has found an association between ultra-processed foods in early childhood, and behavioural and emotional development. 

Specifically, the team found that higher ultra-processed food consumption is linked to behavioural and emotional difficulties including anxiety, fearfulness, aggression or hyperactivity.

“The preschool years are critical for child development, and it’s also when children begin to establish dietary habits,” said Kozeta Miliku, principal investigator on the study and an assistant professor of nutritional sciences in U of T’s Temerty Faculty of Medicine.

“Our findings underscore the need for early-life interventions such as professional advice for parents and caregivers, as well as public health campaigns, nutrition standards for child-care providers and reformulation of some packaged foods,” Miliku said.

This study, published in JAMA Network Open, is the first to examine ultra-processed food consumption and standardized behavioural assessments in kids using detailed, prospective data. It is also one of the largest ever to look at behaviour and mental health in early childhood. 

Ultra-processed foods are industrial formulations made largely from refined ingredients and additives not typically used in home cooking. In Canada, they make up nearly half of preschoolers’ calorie intake.

The researchers drew information from the CHILD Cohort Study, a longitudinal, population-based study that recruited pregnant women between 2009 and 2012 and followed their children from before birth through to adolescence at four sites across Canada.

The researchers looked at dietary data from over 2,000 children aged three. Two years later, when the children were five, the team assessed the preschoolers’ scores with the validated Child Behavior Checklist, a widely used measure for emotional and behavioural wellbeing in children. 

The research team — which included first authors Meaghan Kavanagh (a postdoctoral fellow) and Zheng Hao Chen (a PhD student in Miliku’s lab) —  found that for every 10 per cent increase in calories from ultra-processed foods, children had higher scores on measures of internalizing behaviours (such as anxiety and fearfulness), externalizing behaviours (such as aggression and hyperactivity), and overall behavioural difficulties.

Higher scores indicate more reported behavioural challenges.

Certain categories of ultra-processed foods showed stronger associations, particularly sugar-sweetened beverages and artificially sweetened drinks. Ready-to-eat and ready-to-heat foods like French fries or macaroni and cheese were linked to higher scores.

In statistical models simulating dietary change, replacing 10 per cent of energy from ultra-processed foods with minimally processed foods, such as fruits, vegetables and other whole foods, was associated with lower behavioural scores.

Miliku, who is also a researcher at U of T’s Joannah & Brian Lawson Centre for Child Nutrition, said the findings indicate that making even a few changes can make a difference toward supporting healthier development.

“Our findings suggest that even modest shifts toward minimally processed foods, like whole fruits and vegetables, in early childhood may support healthier behavioural and emotional development,” she said.

Miliku’s interest in the topic was sparked by everyday observations as a parent.

“As a parent of a toddler, I started noting how often convenience foods appear in children’s diets, sometimes even in places we consider healthy environments,” she said. 

A growing body of evidence links ultra-processed foods to increased risks for obesity and cardiometabolic diseases in adults and children. Previous research has also suggested associations between these foods and adverse behaviour and mental health outcomes in adolescents and adults. 

“Parents are doing their best and not all families have access to single-ingredient foods, or the tools and time needed to incorporate them into their families' diets,” said Miliku. 

“Ultra-processed foods are widely available, affordable and convenient,” she added. “It is important to consider how we can gradually increase whole and minimally processed options when possible.”

Miliku said that even modest changes, such as adding a piece of fruit or swapping a sugary drink for water, may support children’s emotional and behavioural development over time. 

“The goal is to provide evidence that can help families make informed choices," she said.

This study was funded by the Canadian Institutes of Health Research and a Temerty Faculty of Medicine pathway grant.

---

Journal

JAMA Network Open

DOI

10.1001/jamanetworkopen.2026.0434 

Adults aged 75 or older should receive a protein subunit Respiratory Syncytial Virus (RSV) vaccine

 

The American College of Physicians (ACP) issued updated vaccine practice points for physicians that advise adults aged 75 or older should receive a protein subunit Respiratory Syncytial Virus (RSV) vaccine and those aged 60-74 at increased risk for severe RSV may consider receiving the protein subunit RSV vaccine. “Respiratory Syncytial Virus Vaccines in Adults Who Are Not Pregnant or Immunocompromised: Rapid Practice Points from the American College of Physicians” is published in Annals of Internal Medicine.  

 

Annually in the US, an estimated 170,000 adults aged 50 or older will be hospitalized and 14,000 deaths will occur due to RSV. Most adults infected by RSV have mild upper respiratory tract infections, but it can also cause life threatening lower respiratory tract infections. Among adults, severe RSV infection is more likely in those aged 75 or older, living in a long-term care facility or with a comorbid condition such as chronic kidney, liver, or lung disease, cardiovascular disease, hematologic conditions (such as sickle cell disease), diabetes, obesity, or a combination of these conditions. Unlike other respiratory virus vaccines that are administered annually, such as influenza, an RSV vaccine is administered only once, and the need for repeat vaccination is being studied.

 

The ACP Population Health and Medical Science Committee (PHMSC) developed the RSV practice points based on a rapid review by the ACP Center for Evidence Reviews. They addressed the efficacy, comparative effectiveness, and harms of RSV vaccines in adults aged 18 or older who were not pregnant or immunocompromised. 

 

The PHMSC considered evidence on benefits (all-cause mortality, reduced RSV-related hospitalization or severe illness) and harms (such as Guillain-Barré syndrome) and concluded that the benefits of the protein subunit vaccines outweigh the harms in adults aged 75 years or older. The benefits, such as prevention of hospitalization, are lower in adults aged 60-74 years compared to those 75 years or older but with the same harms.

Music may not boost focus or mood during exercis

 

Music is commonly used during exercise and is often assumed to improve focus, mood, or mental performance. A new systematic review and meta-analysis led by researchers at the Centre of Excellence in Music, Mind, Body and Brain at the University of Jyväskylä examined whether these assumptions are supported by experimental evidence.

The review analysed ten studies that tested the effects of music on executive functions (such as attention and inhibitory control) and on affective responses (positive or negative feelings) during short bouts of exercise. Across studies, the results showed no consistent effects of music on cognitive or emotional outcomes.

Rather than finding clear benefits, the researchers observed that results varied widely depending on the context or exercise setting. In particular, analyses suggested that music tended to show smaller or negligible effects during higher-intensity exercise and among older participant samples. Any apparent effects were inconsistent across studies and did not reliably generalise.

Specifically, they found that the effects of music were not stable or universal. Instead, outcomes appeared to differ based on factors such as how hard participants were exercising, who the participants were, and how the studies were designed.

“Music is often treated as a one-size-fits-all tool for improving exercise experiences, but when we looked carefully at the evidence, the effects were somewhat inconsistent. What seems to matter is the situation, how intense the exercise is, who is exercising, and how outcomes are measured. Without that context, broad claims about music’s benefits during exercise are not always supported.” Dr. Andrew Danso, leader of the study.

Overall, the review highlights the need for more rigorous and consistent study designs to clarify when music may, or may not influence cognitive and emotional responses during exercise.

Early birds, getting more physical activity, linked to lower risk of ALS

 Highlights:

• Amyotrophic lateral sclerosis (ALS) is a rare, progressive disease characterized by the degeneration of nerve cells in the brain and the spinal cord.
• The study does not show cause and effect; it only shows an association.
• A new study of half a million people compared early birds who are more productive in the morning to night owls who are more productive later in the day.
• It found being an early bird was associated with a 20% lower risk of ALS when compared to being a night owl.
• The study also looked at physical activity and found being more physically active was associated with a 26% lower risk of ALS compared to being less active.
• While more research is needed, researchers say promoting healthy lifestyle behaviors may represent a potential strategy for reducing the risk of ALS.

Being an early bird, also called a morning person, and being more physically active are associated with lower risks of amyotrophic lateral sclerosis (ALS), according to a preliminary study released February 25, 2026, that will be presented at the American Academy of Neurology’s 78th Annual Meeting taking place April 18-22, 2026, in Chicago and online.

The study does not prove cause and effect between these behaviors and the risk of ALS; it only shows an association.

ALS is a rare, progressive disease characterized by the degeneration of nerve cells in the brain and the spinal cord. People with ALS lose the ability to initiate and control muscle movement, which often leads to total paralysis and death. The average life span after diagnosis is two to five years.

“Previous research suggests better sleep and more physical activity may reduce the risk of some neurodegenerative diseases, but results for ALS have been mixed,” said study author Hongfu Li, MD, PhD, of Zhejiang University in Hangzhou, China. “Our study found a sleep schedule that better matches daylight hours and more physical activity were related to a lower risk of ALS.”

The study included over 500,000 people with an average age of 57. Participants were followed for an average of 14 years, during which 675 people, or 0.14%, developed ALS.

Participants completed questionnaires at the start of the study about their sleep habits and physical activity.

For sleep, researchers determined chronotypes for all participants. Chronotype is a person’s natural preference for when they are most alert and most sleepy. It is part of the circadian rhythm, the 24-hour sleep-wake cycle.

Researchers looked at two chronotypes. Morning chronotype, or early birds, was defined as people who preferred earlier bedtimes and wake times and reported peak productivity earlier in the day. Evening chronotype, or night owls, was defined as people who preferred later bedtimes and wake times and reported peak productivity later in the day.

Of participants, 277,620 were classified as early birds and 166,361 as night owls. Of early birds, 350 developed ALS. Of night owls, 237 developed ALS. Another 58,298 were excluded because their chronotype could not be determined.

After adjusting for factors such as age, sex and body mass index, researchers found being an early bird was associated with a 20% reduced risk of ALS compared to being a night owl.

Researchers also looked at sleep duration and found those who had between six and eight hours of sleep per night had a lower risk of ALS compared to those who had more or less sleep.

Researchers also found that greater physical activity was associated with a 26% lower risk of ALS.

They used metabolic equivalents (METs) to quantify energy expenditure. For each physical activity, METs were multiplied by the frequency and duration to obtain a physical activity score of MET-minutes per week. Vigorous activities such as running and cycling were assigned 8.0 METs, moderate-intensity activities like carrying light loads and household activities were assigned 4.0 METs, and lower-intensity activities such as walking were assigned 3.3 METs. The average physical activity level for participants was 2,645 METs-minutes per week.

Researchers found that among those who had more physical activity, 600 MET-minutes or more per week, 386 of 314,170 people developed ALS. Among those who had less, 107 of 70,946 people developed ALS.

After similar adjustments, 600 MET-minutes or more per week was associated with a 26% lower risk of ALS.

“While more research is needed to further explore these associations, promoting healthy lifestyle behaviors may represent a potential strategy for reducing the risk of ALS,” said Li.

A limitation of the study was that 95% of participants were white people, so the results may not be the same for other populations