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 man y 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. ...read more read less