The quality of air you breathe in your home may be robbing you of good health. Modern energy-efficient homes, by virtue of their airtight design, often trap chemical vapors from furniture, carpets, and building adhesives. Condensation from air ducts, houseplant soil, and sink areas can produce harmful mold, fungus, yeast and bacteria. Many respiratory, eye, ear, nose and throat complaints appear in doctors' waiting rooms because of overexposure to foul household air. Changes of seasons often shift populations of these microbial species as growing conditions fluctuate.