Dogs & Indoor Air Quality: Study Reveals Impact on Particles & Microbes

Dog Companionship and Indoor Air Quality: A New Look at Microbes and Particles

The bond between humans and dogs is ancient and profound, but a new study from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland reveals a previously unquantified impact of our canine companions: their effect on indoor air quality. Researchers found a significant increase in both particles and microorganisms in environments where dogs are present, prompting a closer examination of the complex interplay between pet ownership and our breathing spaces. The study, conducted in a controlled environment in Friburgo, Germany, highlights how everyday dog behaviors contribute to changes in the air we breathe.

How the Study Was Conducted: A Controlled Environment

The research team utilized a highly controlled environmental chamber in Friburgo, Germany, to isolate the impact of dogs on air quality. The chamber maintained stable temperature and humidity, and featured constant air filtration. This allowed scientists to attribute any variations in air composition directly to the presence of the animals. The study involved both large and small dog breeds – including chihuahuas – with a total of three large dogs and four small dogs participating. Researchers monitored the air as the dogs moved and interacted within the chamber, recording fluctuations in particle and microorganism levels.

What the Researchers Found: Particles, Microorganisms, and Ozone

The study revealed that common canine activities – shaking, scratching, and even receiving affection – release particles into the air. These particles include dust, pollen, plant debris, and microorganisms. Every movement by the dogs triggered detectable spikes in air contamination. Notably, larger dogs were found to emit between two and four times more microorganisms than a human in the same space. This finding underscores the potential for dogs to significantly alter the microbial composition of indoor environments.

However, the research wasn’t solely focused on negative impacts. The study also found that dogs generate approximately 40% fewer ozone derivatives than humans. In people, ozone reacts with skin oils like squalene, producing chemical compounds such as aldehydes and ketones. While dogs don’t naturally produce squalene, it can transfer to their skin through contact with humans, leading to subsequent reactions with ozone. This suggests a potentially mitigating effect of dog ownership on certain types of indoor air pollution.

The Microbial Balance: Risks and Potential Benefits

The increased microbial diversity observed in the presence of dogs isn’t necessarily detrimental, according to Professor Dusan Licina, a researcher involved in the study. “This high level of microbial diversity isn’t necessarily subpar news. Some studies indicate that exposure to a variety of microbes can stimulate the development of the immune system, especially in children,” he noted. This suggests a potential benefit to early childhood immune development through exposure to the microbes carried by dogs. However, Professor Licina cautioned that the actual impact of these microorganisms on human health remains incompletely understood and can vary significantly from person to person.

Gases and Respiration: CO₂ and Ammonia Emissions

The study also examined the emission of gases like carbon dioxide (CO₂) and ammonia. Researchers found that dogs emit similar amounts of CO₂ and ammonia as humans. While dogs release proportionally more ammonia per unit of CO₂, they tend to spend more time at rest and breathe more slowly, resulting in comparable overall emissions. The researchers estimated that a large dog, such as a mastiff or Newfoundland, can produce as much CO₂ as an adult human at rest.

EPFL’s Broader Research Focus on Sustainability

This research on canine impact on air quality is part of a larger initiative at EPFL focused on sustainability. The university will host a day of sustainability-focused scientific activities and public events between March 5th and 7th, 2026, to assess current efforts and chart future steps for sustainability on campus and in research. EPFL, founded in 1969, is a leading science and technology university in Switzerland, dedicated to education, research, and innovation. As outlined in Wikipedia, EPFL’s origins trace back to the École d’ingénieurs de l’Université de Lausanne, and its modern campus is located in Écublens, Vaud.

What Remains Unclear and What Happens Next

While the EPFL study provides valuable insights, several questions remain. The long-term health effects of increased microbial exposure from dog ownership are still unclear. The study did not specify the types of microorganisms released by the dogs, nor did it investigate the potential for these microbes to trigger allergic reactions or exacerbate respiratory conditions in sensitive individuals. Further research is needed to determine the specific microbial profiles associated with dog ownership and their impact on human health.

The researchers plan to continue investigating the complex relationship between pets and indoor air quality, exploring potential mitigation strategies such as improved ventilation and air filtration systems. They also aim to examine the impact of different dog breeds and grooming practices on air particle and microorganism levels. The ultimate goal is to provide evidence-based recommendations for maintaining healthy indoor environments for both humans and their canine companions.

For more information on air quality and health, resources are available from organizations like the Environmental Protection Agency (EPA) and the World Health Organization (WHO). Understanding the factors that influence indoor air quality is crucial for protecting public health and creating healthier living spaces.