Are there any nontoxic, non-offgassing replacement windows available? Also, how does one identify nontoxic sheetrock in stores?

Asked by jean roper
Newton Highlands, MA


David Edwards PhD

Answered by David Edwards PhD

Santa Clara, CA

EarthBound Homes

June 6, 2010

Replacement windows and indoor air quality

Windows are generally not considered a threat to indoor air quality from offgassing.

The fact that the majority of replacement windows are made of or are clad in vinyl does have serious environmental consequences, as the manufacture and eventual destruction of vinyl at the end of its lifecycle results in the production of the potent environmental and bioaccumulative poison dioxin. Fortunately, during the usable lifespan of vinyl, it shows very little degradation and subsequent offgassing, and so poses little health risk -- which is why it is used in windows.

Most other components used in windows are wood of one sort or another, and then the cladding materials, usually aluminum, fiberglass, or just paint, none of which has much effect on indoor air quality because cladding is located on the exterior of the building. Wood does offgas, but it is largely water and some natural, plant-based, aqueous (water-based) solutions and generally not harmful to human health.

There is potential offgassing -- or really, leaking gas -- from the infills of inert-gas-filled windows, but this is when the seal leaks and the window fails and should not be considered a normal condition of insulated windows.

The facts about harmful drywall

As far as the toxic drywall is concerned, you have a bit of a mixed blessing.

The vast majority of the toxic drywall came from just a few manufacturers in China that used mined gypsum as raw material for wallboard; this drywall was produced in 2005, 2006 and 2007.

The “toxic drywall” was characterized by the strong evolution of sulfur dioxide, which gave it a rotten-egg smell and was the major cause of the corrosion that destroyed the homes' electrical systems, air conditioners and other metal appliances and fixtures.

While there have been many complaints about negative health effects to people living in homes with Chinese drywall, the real physiological effects of the “toxic drywall” have not been conclusively proven, especially considering that the major sulfur-based components are not present in concentrations high enough to be the root cause of all of the symptoms people were complaining about.

It is quite possible that, while the corrosion of the metal is a real effect of sulfur dioxide exposure, the plethora of health-related claims are more a psychosomatic reaction and less of a biochemical or physiological effect.

To give you some perspective, this is a dose-response chart showing that with increasing concentrations of sulfur dioxide, you get different physiological effects.

  • 0.0047 parts per million: 50% of humans can detect the "rotten egg" odor of hydrogen sulfide
  • 10-20 ppm: eye irritation
  • 50-100 ppm: eye damage
  • 150-250 ppm: paralysis of the olfactory nerve after a few inhalations, leading to loss of the sense of smell
  • 320-530 ppm: pulmonary edema; possible death
  • 530-1000 ppm: strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing
  • 800 ppm: lethal concentration for 50% of humans for 5 minutes exposure
  • Over 1000 ppm: immediate collapse with loss of breathing, even after a single breath of the gas

According to a testing agency, Environ, that was paid by one of the main home builders involved in the litigation over Chinese drywall, over 30 homes with Chinese drywall were tested for sulfur dioxide levels. The concentrations of sulfur dioxide in these homes averaged 5 ppb (parts per billion, one-thousandfold less than ppm or parts per million, which is what is listed in the biological effects chart above).

Because Lennar, the builder and defendant in many of the lawsuits, paid for these tests, we should view the results with some skepticism, but these levels are 100 to 1000 times less than the levels we can expect to cause typical sulfur dioxide exposure symptoms and other health effects that homeowners are claiming are caused by the Chinese drywall.

The real problems that eventually penetrated 37 states, but were mainly localized to just five states -- Florida, Virginia, Mississippi, Louisiana and Alabama -- have largely been mitigated for new construction. Most of these manufacturers have “miraculously” stopped making toxic drywall, though they claim not to know the cause of the toxicity in the first place and have done nothing to change the manufacturing process, and so can still claim that they didn’t do anything wrong.

The Consumer Product Safety Commission (CPSC) identified the ten top manufacturers of the toxic drywall, listed here:

  1. Knauf Plasterboard (Tianjin) Co. Ltd., China (2005)
  2. Taian Taishan Plasterboard Co. Ltd., China (2006)
  3. Shandong Taihe Dongxin Co., China (2005)
  4. Knauf Plasterboard (Tianjin) Co. Ltd., China (2006)
  5. Taian Taishan Plasterboard Co. Ltd., China (2006)
  6. Taian Taishan Plasterboard Co. Ltd., China (2006)
  7. Shandong Chenxiang GBM Co. Ltd. (C&K Gypsum Board), China (2006)
  8. Beijing New Building Materials (BNBM), China (2009)
  9. Taian Taishan Plasterboard Co. Ltd., China (2009)
  10. Shandong Taihe Dongxin Co., China (2009)

Notice that there are no North American manufacturers on this list. Also notice the dates after the names. These dates identify the year that the toxic drywall was produced by these plants. Subsequent analysis has shown that many of the worst offenders are now producing drywall with sulfur dioxide levels at or near North American manufacturers' levels. No reasons have been given for the sudden change in the makeup of the Chinese drywall.

If you feel like saving a few bucks by buying the Chinese drywall and taking your chances, that is up to you, but this seems like a great time to help reinforce our economy, reduce our trade deficits and get a safer product by buying (North) American drywall.

To date, there have been no tests showing any North American-manufactured drywall has posed life risk or property damage, though there have been over 2,000 complaints from homeowners in the US who claim, despite the lack of evidence, that they are the victims of homes built with toxic US-made drywall. Their claims have been tested by the CPSC, but only very low levels of sulfur dioxide were found in North American-manufactured drywall-- and there was no evidence of toxicity. The CPSC has deemed North American drywall safe.

We recommend Pabco and USB. The latter has the greatest recycled content of any wallboard manufacturer in North America.


For more information:

For more on choosing replacement windows, you should read "Should I choose vinyl or non-vinyl replacement windows?" by Susan Davis.

For more on choosing safe drywall, you should read "Is there a drywall alternative that's safe for our new baby's nursery?" by Nick Cope.

Tagged In: home air quality, energy efficient window, drywall, pvc safety

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