UFFI foam insulation in an old house (C) Daniel Friedman How to Remove & Avoid Formaldehyde Gas Hazards In buildings

  • FORMALDEHYDE GAS HAZARD REDUCTION - CONTENTS: How to get rid of indoor formaldehyde gas. How to avoid formaldehyde gas hazards indoors. List of sources of formaldehyde gas or odors in buildings. How to reduce formaldehyde exposure levels in a buildingrmaldehyde gas odors or hazards in buildings
  • POST a QUESTION or READ FAQs about reducing indoor formaldehyde gas levels

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Reduce formaldehyde hazards in buildings:

This article describes steps to reduce or eliminate exposure to formaldehyde gas in air or water indoors - how to remove formaldehyde gas and formaldehyde gas emitting building products.

We include scholarly research on methods for reduction of formaldehyde levels in buildings and in other systems.

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Suggestions for Reducing Exposure to Formaldehyde Indoors

Particle board with mold (C) Daniel Friedman

Our photo (left) shows bare particle board visible on the under-side of a game table. The yellow growth happens to be a mold infection.

If the bare particle board surface had been sealed with a clear sealant or a paint the moisture up-take of this particle board product would have been less friendly to mold growth and possibly to formaldehyde outgassing as well.

[Click to enlarge any image]

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.


Formaldehyde is a ubiquitous volatile organic compound (VOC) that occurs in nature and is widely used in building products, finishes, and furnishings because of its desirable properties and low cost. Nearly all products made with formaldehyde outgas to some extent, but only a few contribute significantly to indoor air problems.

The best way to limit exposure to formaldehyde is to avoid the use of bare pressed wood products made with urea-formaldehyde resins.

Also avoid cabinets, flooring, and furniture finished with acid- catalyzed urea formaldehyde coatings, which emit a very high level of formaldehyde when new. Individuals with formaldehyde sensitivity should take further steps to avoid permanent press draperies, wallpaper, and conventional paints, many of which use formaldehyde as a preservative.

The highest emitting products are typically medium- density fiberboard, particle board, interior hardwood plywoods, such as lauan, and prefinished interior plywood paneling. In addition to underlayments and decorative panels, these product are widely used in cabinets, countertops, shelving, and furniture.

Where possible, substitute solid wood, softwood plywood, or products certified as low emitters of formaldehyde. All exterior-grade plywood and pressed-wood products and all APA-stamped plywood panels use phenol-formaldehyde resins, which are more chemically stable than urea- formaldehyde and have negligible emissions. Homasote products are also free of formaldehyde and can be used as underlayment and sound insulation.

For cabinetwork, look for low-emitting substrates using phenol-formaldehyde or methylene diisocyanate (MDI) resin, such as SierraPine’s formaldehyde-free medium-density-fiberboard called Medite II. There are also many “low-formaldehyde” panel products developed to comply with U.S. Department of Housing and Urban Development (HUD) requirements for manufactured housing. While these generally have lower formaldehyde emissions than noncertified products, they may still have over three times the emissions of products made with phenolic or MDI resin.

Where panel products with urea-formaldehyde resins must be used, they should be covered or coated on as many surfaces as possible. Panels covered with an impermeable facing, such a vinyl or plastic laminate, have low emissions. Another option is to coat the panels with two or more coats of a water-resistant finish, such as polyurethane, lacquer, or alkyd paint. In general, unless a finish is visibly thick and an effective vapor barrier, it probably has little effect on formaldehyde emissions.

Controlling heat and humidity is also important, since hot, humid conditions significantly raise the level of formaldehyde emissions. Sensitive individuals should also launder permanent-press draperies before using and should avoid newly painted rooms for several days. Prior to use, any new furnishings or surfaces with formaldehyde-based materials should be allowed to air out for several days to several weeks in a well-ventilated space.

Generally, formaldehyde levels will drop off rapidly at first and eventually level off at very low levels. Monitoring of 40 new houses by Oak Ridge National Laboratory found that, after five years, nearly all houses, including those insulated with urea-formaldehyde (UF) foam insulation, had formaldehyde levels below 0.1 ppm.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Reader Question: Eliminating formaldehyde using Ammonia NH4 ?

My daughter purchased a used trailer that now apparently has a formaldehyde odor in it. It doesn’t bother her husband, but does irritate her nose and eyes. She ran across a homeopathic remedy to (apparently) “eliminate” the problem. It involves putting NH4 in the room.

The chemistry is shown at a homeopathic remedy website in an article titled "FORMALDEHYDE and its ANTAGONISTS" . The reactions seem reasonable, but this begs the question of the effectiveness of the treatment itself. What do you think about this? Your opinion is appreciated. Thanks in advance. - Eric

Reply: Best approach to indoor formaldehyde: find and remove the sources of irritating indoor chemicals

OPINION: A discussion I had some time ago with a theoretical phyisist included her observation that while, as a theoretician operating at the edge of human understanding of particle physics, she was reluctant to say that anything is impossible, including the "water memory" theory underpinning the very-dilute-is-more-effective principle of homeopathic remedies that dilute a substance with water until not a single molecule of the original substance remains in the treated water.

We recognize that some people report using and being very satisfied with homeopathic remedies for a wide range of complaints, notwithstanding the scientific challenges involved. But the same physicist pointed out that for that latter homeopathic theory to hold, many other scientific observations that are widely accepted, ranging from observations of the earth circling the sun to the operation of internal combustion engines, would have to be found false. So I'm uncertain about citing a homeopathy product marketing website as a source of a "cure" for formaldehyde odors.

Even if the chemistry theory of putting ammonia into indoor air to attack formaldhyde has a theoretical basis, the practical theory may be a bit thin, as we elaborate below.

The procedure described in the article wants you to place the item that is a formadehyde source in a location with an open bowl of lemon-scented ammonia. There is no evidence given in the article that the concentrations of airborne ammonia in a living room populated with formaldehyde outgassing carpets, furniture, cabinetry, would be adequate to have the desired reaction without also producing a dangerous indoor level of ammonia.

Still from a more practical and in our opinion more significant viewpoint, when dealing with most indoor contaminants, it makes the most sense to correct (remove) the source of the contaminant than to try to keep dealing with it by disguising or neutralizing it as it is generated in the indoor environment. Otherwise, as I see it, we permit a continuing source of noxious outgassing to continue and then keep trying to deal with the result.

Watch out: The article to which you refer argues that using ammonia to "get rid of" formaldehyde invoves chemistry in which ammonia reacts with formaldehyde to produce "... a harmless imine with a byproduct of water". Ammonia too is a chemical (or gas) to which exposure can be dangerous and harmful.

In your daughter's case, if moving to a different home is out of the question, then identifying the in-home products that are the primary sources of irritating formaldehyde outgassing would be in order. Often those are carpet padding and in some cases chipboard-based cabinets and furniture. It may be possible to make just a few changes that remove the primary sources of formaldehyde sufficiently that the home no longer bothers her.

Also in at least some products, outgassing diminishes from new products after weeks or months. So the passage time alone, allowing product outgassing to complete (rather than exposure to ammonia) might explain the improvement in formaldehyde levels in many cases.

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Reader Question: how do we test & what's the best way to get rid of formaldehyde outgassing from a Freight Liquidator's Laminate Flooring Job

7 March 2015 Californian said:

We just purchased a house with Lumber Liquidator flooring that was found by 60 minutes to contain formaldehyde level many times higher than the legal limit in the U.S. However, our installation is more than 2 years old. Do you think the outgas process of our floor is mostly done? We thought about replacing the flooring but the current floor was installed on top of a plywood subfloor. Now, what if the formaldehyde has transferred into the subfloor so if we re-install any kind of porous flooring (like carpet) then it would only allow the formaldehyde to rise through the new flooring into our living space? Is this a realistic possibility? What can we do to test the level of formaldehyde in the indoor air? And what's the best way to get rid of it?


Thanks for the interesting question, Californian.

I'm not sure I agree with your premise that a significant level of formaldehyde has transferred to the subflooring below your laminate flooring. I would not, without carefully-constructed testing, assume that the subfloor is a meaningful receiver of formaldehyde such that it would continue to offer an outgassing hazard from having had a laminate or engineered floor installed above it, nor would I assume, without proper testing, that the finish flooring in your home is hazardous.

Nor do we know that your particular floor was the specific Chinese-made product that has raised this formaldehyde concern.

While the article you cite reported unacceptably high levels of formaldehyde, I have not yet located specifics on exactly how the test was performed - so we don't have a clear idea of how well it represents the actual experience likely to be had by homeowners where laminate flooring was installed.

Before contemplating any costly action I would want to see the results of two carefully constructed tests of formaldehyde levels.

  1. A properly-conducted test of formaldehyde levels in your home at a fixed height above the floor (where people breathe), both in the laminate-floored room and in another more remote room in the home where other flooring products (including carpeting and excluding it too) are installed. That way we have an idea of whether or not occupants are being exposed to hazardous formaldehyde levels.
  2. A "worst case" formaldehyde test in your home, or in my parlance, "most aggressive" test of the flooring in the most-suspect room(s) in the home. This might be performed by collecting a sample under an enclosed cover right over the floor surface either over a specified interval.
Please see complete details including your question and a more exhaustive reply now found

Formaldehyde Removal & Formaldehyde Antagonists scholarly research articles

Note: The research articles we could find discussing formaldehyde antagonists did not share the viewpoint of the reader whose question was reported above.

Formaldehyde Article Series Contents


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