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Urea-Formaldehyde Insulation and Formaldehyde
Formaldehyde is a chemical gas used extensively in the manufacture of many products including building materials and chemical preservatives. Formaldehyde gas has no color but in high quantities, its smell is pungent and can be toxic or irritating. In construction, harmful levels of formaldehyde gas are most likely to be found in a foam product called urea-formaldehyde foam insulation (UFFI).

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UFI was used as an effective insulation product in many homes until the 1980’s when the presence of high levels of formaldehyde gas was determined to be a health hazard.

Common Sources

Formaldehyde is a common chemical and a by-product of combustion. It can be found in its natural state both in the human body and in the air. Often it is found in a water solution as a preservative or disinfectant; it is also present in tobacco smoke, vehicle exhaust, and fireplace, furnace, and wood stove fumes.

Most formaldehyde in a home is likely to come from urea-formaldehyde foam insulation (UFFI). Developed during the 1950’s as an efficient insulator, UFFI is usually mixed on-site during a home’s construction and injected into the wall where it can "cure" and become an insulating agent. In the past, sometimes a small excess of formaldehyde was added to ensure complete curing of the UFFI substance, but this is generally regarded as unsafe. After a short period during which small levels of formaldehyde will escape from the walls, the UFFI is usually quite safe unless it is not well sealed or it becomes wet and/or exposed, in which case it may begin to release harmful levels of formaldehyde gas into a home’s air supply. Because of potential harmful release of formaldehyde, UFFI is not in common use today and is banned in many places.

Other sources of formaldehyde in a home can include:

  • New carpets, which may trap formaldehyde emitted from other sources and release it when temperature and humidity change
  • New plywood, particleboard, waferboard, etc, where formaldehyde is used as an adhesive
  • Gas stoves and kerosene heaters

Formaldehyde in the atmosphere of a home, even in levels that are negligible or not harmful, can still devalue a home slightly if proper measures are not taken to control the release of this substance into the air. Also, formaldehyde release from any substance already containing it (such as UFFI) is directly related to its temperature. This means that release of the gas will increase as the substance’s temperature increases, and release will decrease as the substance’s temperature decreases.

Health Effects

Under most normal conditions, even with some formaldehyde release into a home, no adverse affects will be noted from elevated formaldehyde levels. However, sensitivity to formaldehyde varies from person to person, and there are several symptoms that can be attributed to formaldehyde exposure, including:

  • Eye irritation
  • Nose and throat irritation
  • Skin irritation
  • Cough
  • Nausea
  • Dizziness
  • Headache
  • Difficulty breathing
  • Asthma attacks in persons already suffering from the condition
  • Fatigue

Prolonged exposure to exceptionally high formaldehyde levels has also been known to cause cancer in lab animals, and may have a similar effect on humans. However, typical elevated levels are usually much lower than the levels known to cause cancer in animal subjects.


If you suspect that there may be excess levels of formaldehyde in your home, then you should have it tested to determine if there is a significant health threat. Home test kits are available but they are not accurate and can yield misleading results.

For an accurate measurement of formaldehyde levels in your home, you should hire a trained professional to do the testing. Professionals will usually:

  • Test for the presence of formaldehyde vapors
  • Determine the source of such vapors, if any are present
  • Determine the best procedure for removing of the source if levels are dangerous

Trained professionals can correctly interpret the test results and accurately determine the source of excess formaldehyde in your home. For instance, the formaldehyde may not come from urea-formaldehyde foam insulation in your home, but instead from sources such as fresh paint, new furniture, or other new pressed-wood products. In addition, since formaldehyde levels can decline over time, the professionals may determine that no serious action is necessary for remediation of formaldehyde exposure.


If formaldehyde in your home is an irritation or problem, there are some steps you can take to reduce your exposure to it and to help prevent more formaldehyde from escaping into the air.

  • Reducing exposure to formaldehyde:
      • Avoid the use of products that are known to release formaldehyde or that have been tested and determined as a possible source
      • Use pressed wood products that are labeled "exterior-grade" (they emit lower levels of formaldehyde)
      • Increase ventilation in your home
      • Remove the source of the formaldehyde from your home.
  • Controlling formaldehyde release and levels:
      • Maintain moderate temperature
      • Reduce humidity levels through the use of proper ventilation and/or a dehumidifier
      • Seal the surfaces of products containing formaldehyde with an approved laminating or coating product.

In the case of formaldehyde fumes emanating from UFFI, the most common procedure is to seal off the outlet of the vapors. This can be done by sealing the cracks and applying several coats of vapor barrier paint (effective for sealing at least half of the vapors and usually lasts for two years), and then putting up mylar or vinyl wallpaper. Aluminum foil is also an effective barrier against formaldehyde vapors. UFFI can be removed completely from walls and replaced with a different form of insulation, but the procedure can be costly and is often unfeasible. If high formaldehyde levels are caused by urea-foam formaldehyde insulation, you should consult a professional about the best methods of sealing and controlling any leakage or release of formaldehyde in your home.

NOTE: Although treatment of a surface with strong ammonia can temporarily reduce formaldehyde levels, ammonia can be toxic and is very dangerous. This procedure is strongly discouraged, since ammonia presents its own serious hazards.

Exposure Guidelines

Normal formaldehyde levels in both outdoor and indoor air are generally under 0.3 ppm (parts per million). Since formaldehyde is naturally present in the air, these levels can be affected by anything from proximity to a large city to the presence of formaldehyde-containing products. Formaldehyde levels are generally considered to be "elevated" when they exceed 0.3 ppm, but for persons who are extremely sensitive to the gas, levels over 0.1 ppm may be enough to cause irritation.

For more information about formaldehyde in the home, formaldehyde testing, and formaldehyde health concerns contact the Environmental Protection Agency (EPA) and the Department of Housing and Urban Development (HUD).

EPA online at:

HUD online at:


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