More than 35 million single-family homes have been constructed since the late 1970s. Well-built and insulated to be extremely airtight to reduce energy consumption, these homes also can experience higher rates of indoor air quality problems.

Common pollutants from materials, people, activities and contents used to build the home, along with excess moisture, can create an unhealthy environment. They include:

• Excess Moisture - Too much moisture can contribute to allergy problems and structural damage by encouraging the growth of mold, mildew, bacteria, dust mites, dry rot and insects. Showers, cooking and people produce moisture on a daily basis.
• Common Household Chemicals and Pollutants
  • Cleaning supplies
  • Paints and solvents
  • Formaldehyde from furniture, carpet, and building materials
  • Pesticides
  • Volatile organic compounds
  • Odors
• Particles
  • Dust and dust mites
  • Pet dander
  • Pollen
  • Lead
  • Asbestos
  • Cooking by-products - grease and smoke
• Tobacco Smoke - A health risk to smokers and nonsmokers alike - children are especially at risk.
• Combustion Products - These are produced by fuel-burning heating equipment, gas water heaters, fireplaces, woodstoves, gas ranges and candles, and include but are not limited to:
  • Carbon monoxide
  • Carbon dioxide
  • NOx
  • Soot
  • Unburned fuel
  • Moisture
• Heat - Overheating in the attic from sun exposure. Ventilation systems and components are designed to:
  • Remove excess moisture to keep relative humidity levels between 30-60%
  • Remove airborne chemicals, particles, tobacco smoke and odors;
  • Help control combustion by-products; and
  • Control excess moisture and heat in attics.

These factors come together to enhance the comfort and indoor air quality of the home and to help keep the occupants breathing safely. A quality ventilation system also contributes to preserving the structural integrity of the home, reducing maintenance costs and adding to the home's value.