The air inside our homes is often more polluted than the air outside, making proper ventilation essential.

Do’s & Don’ts

  • The air inside our homes is often dirtier than the air outside.

    With two to five times the concentrations of dangerous, airborne chemicals, gases, molds and other particulates. This makes proper ventilation essential, especially in newer air-tight, energy-efficient homes built to stop drafts and energy loss.

  • Consider a whole-home ventilation system properly designed for your home size and climate.

  • If you live in a more extreme climate that requires a lot of heating or cooling, consider an energy recovery ventilation system.

    These systems recapture the energy from your HVAC system before dirty air is expelled.

  • Ensure that you are minimizing sources of indoor air pollutants.

    In particular, choose products that are certified to be low in VOCs, don’t off-gas formaldehyde, don’t have added flame retardants or water-or stain-proof coatings, and aren’t made of PVC plastic.

  • Vent clothing dryers to outside the home, and clean the ducting every few months.

    This prevents the possibility of preservative chemicals leaching from wood and being taken up by plants.

  • Have your home professionally tested for radon.

    If levels are too high—2 to 4 picocuries per liter—consult a certified radon mitigation professional to design and install the appropriate ventilation system.

  • Ensure that gas, propane or wood stoves are properly vented to outside the home.

    Consider electric or gas stoves as a source of heat instead of wood-burning stoves, which can release smoke particles and VOCs.

  • Select the highest efficiency rated air filter that your heating and cooling system can accommodate.

    Filter pollen, mold spores, dust, dander and smoke particles out of your air. The American Lung Association recommends using filters rated MERV 10 or higher.

The Dirty Details

Many home cleaning products, building materials and furnishings release pollutants and chemicals into your home’s air, including: volatile organic compounds, or VOCs, that are linked to respiratory problems and other health impacts; formaldehyde, which is known to cause cancer; and hormone-disrupting and cancer-causing chemicals from flame retardants, PVC plastics and perfluorinated chemical coatings.

Additionally, insufficient airflow and humidity can create an ideal breeding ground for mold and dust mites, which can cause allergic reactions and exacerbate asthma symptoms.

Appliances like gas stoves, fireplaces or clothing dryers can release gases such as carbon monoxide, which can cause headache and dizziness, or can even be fatal at higher concentrations.

Radon, a naturally occurring radioactive gas that can seep from the ground into basements through foundation cracks, may also be a concern, as exposure is linked to lung cancer. Testing for radon, which is simple and inexpensive, is the only way to know if your home has a problem.

Types of Ventilation

You should use a home ventilation system appropriate for your climate, the humidity level in your home, and the degree to which your home is airtight.

There are three types of ventilation systems used in homes:

  • Natural ventilation, which is attained by simply opening windows and doors. It's the easiest, least expensive way to bring in fresh air, but it may not circulate air evenly where you need it most, and it is energy inefficient in extreme weather conditions.
  • Spot ventilation, which removes pollutants through exhaust fans in the kitchen or bathroom.
  • Whole-house ventilation, which exchanges air uniformly throughout the home, is recommended for well-sealed, energy-efficient homes. While adding a whole-house ventilation system can be expensive, using existing central heating and cooling ductwork can help lower the installation cost.

With any of these options, the placement of the exhaust and/or supply ventilation is critical to ensuring that air is ventilated in all parts of the home’s living space. Pay special attention to bedrooms and bathrooms where dirty and moist air tends to get trapped behind closed doors. A whole house exhaust fan should be centrally located and close to bedrooms –for example, in a hallway or stairwell. Bedroom doors should be kept open during the day, or have space between the bottom of the door and flooring to allow sufficient airflow. Work with a HVAC professional to design and install the appropriate ventilation system for your home and climate.

Each type of whole-home ventilation system has its pros and cons:

  • Exhaust ventilation is the least expensive to install and works well in cold climates. Exhaust ventilation uses a fan to push air out of the house through a central outlet. The disadvantage to this type of ventilation is that the fan can potentially draw moisture or pollutants from other parts of the house–like dust from the attic, or mold and radon from a crawl space–into the main living space.
  • Supply ventilation is similar to exhaust ventilation, except that the ventilation fan pulls outside air into the home. Fewer pollutants are introduced compared to exhaust ventilation, and the outside air entering the home can also be filtered.
  • Balanced ventilation systems are the best of both worlds, using exhaust and supply fans (or vents) to bring fresh air in and push old air out. There is less concern about pulling contaminants inside since fresh air is being drawn from outside—not attics or crawl spaces—and incoming air can be filtered. This system is suitable in all climates, but can be more expensive to install and operate.
  • An energy recovery ventilation system may be cost effective in areas with extreme winter or summer temperatures. Transferring the home’s heating or cooling from the exhausted air to the incoming air before it enters the house can recover about 70 to 80 percent of the energy. Although installation of this type of system can be expensive, costs can be minimized by sharing existing duct work.


  1. American Lung Association,Ventilation: How Buildings Breathe. Available at
  2. Brett C. Singer,Kitchen Ventilations Solutions to Indoor Air Quality Hazards from Cooking. Lawrence Berkeley National Laboratory, 2013. Available at
  3. U.S. Department of Energy, Ventilation. Available at
  4. U.S. Department of Energy, Whole-House Ventilation: Improved Control of Air Quality.2002. Available at
  5. U.S. Environmental Protection Agency, Improving Indoor Air Quality. Available at
  6. U.S. Environmental Protection Agency, Radon Resources for Home Buyers and Sellers. Available

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