How To Improve Interior Air Quality

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has generated the following list of actions homeowners can take to achieve good indoor air quality:

Fossil fuel–fired water heaters and furnaces should use sealed combustion or be power-vented. When natural-draft appliances are used, they should be properly vented and be outside the occupiable space.
Vent bathrooms, kitchens, toilets, and laundry rooms directly outdoors. Use energy-efficient and quiet fans.
Avoid locating furnaces, air conditioners, and ductwork in garages or other spaces where they could draw contaminants into the house. Install an automatic door closer on any door from the house to the garage. To reduce airborne contaminant transport, apply weatherstripping around door edges. If ducts must pass through a garage or other potentially polluted space, seal the ducts well to avoid entrainment of polluted air.
Properly vent fireplaces, wood stoves, and other hearth products; use tight doors and outdoor air intakes for these products when possible.
Put a particle filter or air cleaner in your air-handling system to keep dirt out of the air and off your ductwork and heating and cooling components. Regularly maintain it or replace it as needed.