05/01/2026
How Pets in Your Home Affect Your Indoor Quality
A recent study published in Environmental Science & Technology by the American Chemical Society set out to measure just exactly what our beloved four-legged doggy friends contribute to indoor air quality (IAQ). What researchers found was that in some cases, pets can rival — and even exceed — the impact of the humans living in the home.
“Pets are part of our indoor environment,” said Dusan Licina, corresponding author of the study. “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.”
What The Study Had To Say
To better understand how pets affect IAQ, researchers compared two groups of dogs — four small dogs (chihuahuas) and three large dogs (including a Tibetan Mastiff, a Newfoundland, and an English Mastiff). The dogs were observed in separate, controlled environments alongside one owner each. All emissions were measured separately.
Here’s the story the results told.
Both small and large dogs released more airborne particulate matter than their human counterparts, with the smaller, more active dogs producing the most. Large dogs, on the other hand, emitted carbon dioxide (CO₂) and ammonia at levels comparable to humans — and at rates much higher than smaller dogs. They also released more bacteria and fungi into the air, much of which came from outside, effectively changing the “indoor microbial composition” in ways that humans don’t, according to ACS.
