By Abbas Nazil
A new scientific study has revealed that dogs significantly influence indoor air quality by releasing gases, particles and microorganisms.
The study finds that dogs also triggering chemical reactions that generate additional pollutants within enclosed environments.
The research was led by the École Polytechnique Fédérale de Lausanne with contributions from the Max Planck Institute for Chemistry.
It provides the first detailed measurements of how pets affect indoor air composition, highlighting an often-overlooked source of pollution in homes.
Findings show that dogs emit levels of carbon dioxide comparable to humans, with larger breeds producing amounts similar to an adult at rest, while also releasing ammonia in slightly higher proportions due to their metabolism and diet.
Beyond gases, the study found that dogs play a major role in dispersing airborne particles such as dust, pollen, microbes and plant debris, especially when they move, scratch or are petted, creating bursts of indoor pollution that can exceed those generated by humans.
Researchers observed that larger dogs release two to four times more microorganisms into the air than people in the same space, contributing to a diverse mix of biological particles that may influence human health in complex ways.
The study also identified a key chemical process involving ozone, a common outdoor pollutant that enters indoor spaces, where it reacts with substances on skin and surfaces.
When humans pet dogs, skin oils are transferred onto the animals’ fur, allowing ozone to react and form new compounds such as aldehydes, ketones and ultrafine particles, which can pose potential health risks.
Although dogs were found to produce about 40 percent fewer ozone-related byproducts than humans, researchers say the interaction still represents an important and previously underestimated pathway in indoor air chemistry.
To obtain accurate results, experiments were conducted in a controlled environmental chamber designed to simulate a typical indoor setting while eliminating external influences, allowing scientists to isolate the specific effects of dogs on air quality.
The study involved both large and small dogs interacting with their human companions under monitored conditions, enabling researchers to track real-time changes in air composition during rest and activity.
Experts say the findings will improve models used to assess indoor pollution and could help guide future building design, ventilation strategies and public health recommendations.
While some microbial exposure linked to pets may benefit immune system development, particularly in children, scientists caution that the overall health impacts remain uncertain and require further investigation.
The researchers conclude that understanding how pets influence indoor environments is essential for creating healthier living spaces, especially as people spend increasing amounts of time indoors.
