When Is a House Too Tight?
When winter winds send a chill through the air, homeowners begin to look for ways to conserve energy and reduce drafts in their homes. If the house is too airtight, however, it can cause indoor air quality problems. There are lots of different factors to consider when examining indoor air problems, including the sources of pollutants, how the air enters the house, and the health issues that can affect your family. In this issue, we have provided some indicators of these factors and precautions you can take to reduce indoor air problems in your home this winter.

What Causes Indoor Air Problems?
Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in homes. Inadequate ventilation can increase indoor pollutant levels first by not bringing in enough outdoor air to dilute emissions from indoor sources, and second, by not carrying indoor air pollutants out of the home. High temperature and humidity levels can also increase concentrations of some pollutants.

Pollutant Sources
There are many sources of indoor air pollution in any home including:

• Combustion sources such as oil, gas, kerosene, coal, wood and tobacco products
• Building materials and furnishings such as deteriorated, asbestos-containing insulation, wet or damp carpet and cabinetry or furniture made of certain pressed wood products
• Products for household cleaning and maintenance, personal care or hobbies
• Central heating and cooling systems and humidifying devices
• Outdoor sources such as radon, pesticides and outdoor air pollution.

How Does Outdoor Air Enter a House?
Outdoor air enters and leaves a house by infiltration, natural ventilation and mechanical ventilation.

• Infiltration means that outdoor air comes into the house through openings around windows and doors, cracks and joints.
• Natural ventilation occurs when air comes through open windows and doors.
• Mechanical ventilation includes devices such as outdoor vented fans that remove air from a single room, and systems that use fans and ductwork to continuously remove indoor air and distribute filtered and conditioned outdoor air throughout the house.
• Air exchange rate is the rate at which outdoor air replaces indoor air. When the air exchange rate is low, pollutant levels increase.

Health Effects of Indoor Air Pollutants
Health effects from indoor air pollutants may occur immediately after exposure or even years later.

• Immediate effects include irritation of the eyes, nose and throat, headaches, dizziness and fatigue. These are usually short-term and treatable by removing the person from exposure to the pollutant.
• Symptoms of long-term health problem such as asthma, hypersensitivity to allergens and humidifier fever may a1show up soon after exposure to some indoor air pollutants.
• Long-term health effects that may show up years after exposure include respiratory diseases, heart disease and cancer.

If you have allergy sensitive residents in your household or people who are considered more "at-risk" such as the elderly, pregnant women, those with pre-existing medical conditions or small children, it is especially important to ensure that your home has proper ventilation, particularly during the winter months.

Precautions You Can Take to Reduce Indoor Air Problems

• Have the radon level in your house measured by a professional.
• Identify all possible sources of indoor pollution and eliminate as many sources as possible.
• Have all combustion sources checked by a professional.
• Limit smoking in your home.
• Consult your healthcare professional if you or a family member experience symptoms. Offer as much information as possible to that professional so they can help identify the source of the symptoms.
• Improve ventilation in your home by opening windows and doors, operating window or attic fans or making certain the vent control is open on window-unit air conditioners often enough to recycle the air in your home. Exhaust fans in the kitchen and bathroom also improve ventilation.
• Pay special attention to ventilation when involved in projects such as painting, paint-stripping, heating with kerosene heaters, cooking or working on hobbies that involve welding, soldering or sanding. Try to schedule hobby activities during a season when you can do some of the work outdoors.
• Consider the purchase of an air-cleaning device for your home.

Look for these tips and many more on www.AllAboutHome.com, brought to you by the cleaning experts at ServiceMaster Clean. To find your local residential cleaning expert chose the "Find an Expert" feature on AllAboutHome.com or call 1-888-SM CLEAN.