Large dogs release two to four times more airborne microbes than humans‎

Unseen but all around us, the air we breathe in enclosed spaces is crucial to our health and well-being. Indoor air is not simply outdoor air that has been run through a filter: it has its own chemical makeup and a unique combination of particles, gases and microorganisms. Because indoor air has many sources of its own, concentrations of many pollutants can be as high as—or higher than—outdoor levels, especially during everyday activities like cooking or cleaning.