"Our Best Friends: How Dogs Alter Indoor Air Quality" Environmental Science & Technology
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.
Adapted from Environmental Science & Technology 2026, DOI: 10.1021/acs.est.5c13324
"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.
The authors acknowledge funding from the Swiss National Science Foundation and the Swiss Federal Technology Institute of Lausanne (École Polytechnique Fédérale de Lausanne). They also thank the dogs and their owners for their participation in the study.
