Pet dogs alter indoor air and may influence children's microbial exposure

Researchers at EPFL measured gases, particles and microbes from pet dogs in a controlled chamber and found large dogs at rest emit similar carbon dioxide and ammonia levels to adults while releasing two to four times more microorganisms during activity.

Researchers at the Swiss Federal Institute of Technology Lausanne (EPFL) measured how pet dogs affect indoor air in a controlled environmental chamber. The team tested groups of large dogs (including a Mastiff, a Tibetan Mastiff and a Newfoundland) and small dogs (Chihuahuas) to compare emissions and particle release. The study looked at gases, particles and microorganisms and observed how routine dog behaviours disperse those materials around a room. Results were reported alongside context from prior research on microbial diversity and children's immune development. Key findings: - A large dog at rest exhaled roughly the same amount of carbon dioxide as an adult human and produced similar quantities of ammonia, the study reported. - During testing, large dogs discharged two to four times more microorganisms than a human occupying the same space. - Common dog behaviours such as shaking, scratching and being stroked resuspended dust, pollen, plant debris and microbes from floors and furnishings. - Dogs carried biological material from outdoor spaces on their fur and paws and redistributed it indoors as they moved about. - Ozone reacting with skin and fur oils produced aldehydes and ketones; on average, dogs generated about 40% fewer of these ozone-reaction by-products than humans under the same conditions. Summary: The experiments indicate that pet dogs change the mix of gases, particles and microbes in a home and can increase the variety of everyday indoor microbes. Previous research is reported to link greater routine microbial diversity with effects on immune development in children, which may help explain why some children raised with animals develop fewer allergies. Undetermined at this time.