so why does chinese drywall · pdf filethe degradation of marine organisms plus the formative...

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So Why Does So Why Does Chinese Drywall Smell? Chinese Drywall Smell?

Copyright© 2010 Gary Rosen, Ph.D.

By Gary Rosen, Ph.D.www.Chinese-Drywall.org

1-04-2010


Chinese Drywall Does NOT Smell Like Chinese Drywall Does NOT Smell Like Rotten EggsRotten Eggs

Measured levels of Hydrogen Sulfide (H2S) in homes according to the US CPSC are very low – only a few parts per billion.This is below, or at most, at the lower limit of what can be detected by the human nose so it is not contributing, or is not contributing much, to the Chinese Drywall smell.And besides, H2S smells like rotten eggs which is NOT what Chinese drywall homes smell like.So what gases coming from Chinese drywall make homes smell the way they do if not H2S?


CPSC July Report CPSC July Report

On page 2 of the CPSC July 2009 Chinese Drywall report they reference an academic research paper that studied Chinese drywall off-gassing.This research, done by German scientists, was paid for by Knauf Germany for the stated purpose of understanding where the odors in the Knauf Tianjin drywall came from (either manufacturing or raw mined material) so as to avoid such problem odors in the future.


German Research PaperGerman Research Paper

A. Burdack-Freitag et al. Institute for Building Physics,

Valley, Germany.

Identification of Odor-Active Organic Sulfur Compounds in

Gypsum Products

Published in the Wiley InterScience Journal

Clean 2009, 37 (6), 459–465


KnaufKnauf TianjinTianjin

Knauf Germany in 2006 hired German researchers to find out what was causing the Knauf Tianjindrywall to smell.According to the CPSC, the samples used in the German research study were identified as coming from the LuNeng mine in ShanDong China.In 2009 the results of the research were published.

Shandong the location of the LuNenggypsum mine is located on the East

Coast of China just South of the Tianjin province where Knauf Tianjin

is located


Page 2 CPSC Report 7Page 2 CPSC Report 7--99--09 09

According to the CPSC,Knauf Tianjin drywall

appears to be the most prevalent problem

Chinese drywall found in US homes.


Presentation Overview Presentation Overview

In this presentation we will review the German research study as to why Chinese drywall smells the way it does. This study has important implications as to: –Understanding the source of Chinese drywall

odor and why it can vary from production run to production run.

–Methods for testing Chinese drywall. –As well as health impact of Chinese drywall.


Gypsum Formation Gypsum Formation

This, peer reviewed, scientific paper starts out by describing how Natural Gypsum is formed.Natural Gypsum deposits are mainly formed by precipitation of minerals as a result of seawater evaporation in various geological eras when the Earth's surface was dominated by water and marine animals.


Gypsum Material Not UniformGypsum Material Not Uniform

The paper then explains that as a result of how the gypsum deposits are formed the composition of gypsum will differ from location to location.According to the report: Typical natural gypsum constituents are lime, marl, clay, bitumen, carbon, pure sulfur or mineral salts and degraded dead marine organisms.The degradation of marine organisms plus the formative conditions results in the gypsum containing numerous organic compounds.


Odor InvestigationOdor Investigation

The goal of the German scientists was to characterize smelly gases beyond the known gases (such as the inorganic sulfur gases H2S and CS2) which meant looking for sulfur containing organic gases.Such sulfur-containing organic gases, as a class of gases, are known to be especially smelly and have a detectable odor at very low concentrations making them difficult to measure.


Quantifying Released GasesQuantifying Released Gases

The German study was based on quantifying the release of organic sulfur gases under laboratory conditions.They were not taking air samples from homes.On the right is shown the “headspace” gas measurement equipment the Germans used to measure the quantityof gas emitted from pieces of gypsum in the lab. The CPSC calls such studies “chamber” studies.


Odor Levels of Released Gases Odor Levels of Released Gases

Once the amounts of the released gases were measured, odor levels of these gases were then measured using a technique developed by food and perfume chemists. On the right is a diagram of the method used to measure the odor levels.


A Challenging TaskA Challenging Task

Highly odorous gases (malodorous gases) can be released by problem drywall at very low levels yet still have a perceptible smell to the human nose.Measuring these very low level gases can be a challenge as often the gases are closely related to one another and difficult to distinguish under typical lab testing environments. It helps when attempting to measure low levels of such gases if you alreadyknow what to look for.


Measuring Odorous Gases from Raw Measuring Odorous Gases from Raw MaterialMaterial

For this study the German researchers obtained – in their words “disgusting-smelling semi-processed raw material” from the LuNeng mine in China from which the Knauf Tianjin drywall was made.Because the raw gypsum released high levels of smelly gases, it was easier for these scientists to determine the types of gases released than from the processed materials. Once they knew what to look for, they were able to more easily measure the much lower levels of odorous gases released by the actual Knauf Tianjin drywall. Pretty smart!

Trucks taking Chinese drywall to the docks for shipment to the U.S.


German Lab Study ResultsGerman Lab Study Results

While the drywall released many organic gases, the researchers were focusing on especially smelly gases which means sulfur containing organic gases.They were able to the identify 8 odor-active sulfur containing organic compounds released by the drywall and also found in high concentrations in the original mined materials.This was in addition to the smelly inorganic H2S and CS2 gases that were already known to be present.

Chinese ship being loaded with drywall for shipment to the U.S.


German Lab Study Results German Lab Study Results

The eight sulfur-containing organic compounds contributing to the off-odor of Chinese drywall were identified as:

2-(ethylthio)-propane, methyl ethyl disulfide, butyl ethyl sulfide, ethyl isopropyl disulfide, diisopropyl disulfide, isobutyl isopropyl disulfide, diethylthiophene, and ethyl isopentyl disulfide


Implications for Occupant Health Implications for Occupant Health

These results from the German lab studies have important implications.– Why – because these organic compounds have high odor

levels but are not corrosive nor irritating (at least to the same degree as the inorganic gases H2S and CS2.)

These malodorous yet non-irritating gases may account for the reason why some homes with

Chinese drywall smell but do not irritate occupants.


Potential Problems from Potential Problems from Lab StudiesLab Studies

There are several potential problems with lab studies of drywall:–Results differ from lab to lab because

procedures and equipment differ.– In lab testing, the temperature and humidity

are typically set high which increases the rate of off-gassing so that drywall can then be checked quickly and inexpensively for emitted gases.

–Given enough temperature and humidity, off-gassing is measurable from ALL drywall (even top quality US drywall) to some extent.


Potential Problems from Potential Problems from Lab StudiesLab Studies

The Nov 20, 2009 CPSC 51 Home Study page 120 found that there is limited correlation between lab (chamber) testing and in-home testing. According to the study, the types of gases found and the levels of these gases found when pieces of Chinese drywall were tested under lab conditions do not resemble the types and quantity of gases found inside of homes.


WRONG Interpretations WRONG Interpretations from Lab Studiesfrom Lab Studies

Even though a certain brand of drywall does not smell, does not corrode copper and does not damage the AC coils, some inexperienced environmental consultants are claiming it is defective because testing under lab conditionsfinds some off gassing.All drywall off-gasses to some extent under such conditions.

Note that the State of Florida DOH guidelines do not recognize drywall meeting these criteria as defective.


Lab Studies vs. Air SamplingLab Studies vs. Air Sampling

Summary & Summary & Conclusions Conclusions



So what do all these lab tests actually tell us about the real world? From a certain perspective they may mean nothing because lab studies (also called Chamber testing or Headspace testing) in no way measure the levels of such gases found inside homes.To measure the levels of emitted gases inside a home or office one must perform air sampling.

Example of stainless steel container used for air sampling..

Lab Studies Lab Studies ≠≠ Real WorldReal World


As a result of how the gypsum deposits are formed, the composition of gypsum will differ from location to location.It can be assumed based on the differences in mine composition that problem drywall may differ from batch to batch with some runs more problematic than others. And some runs most likely will not be so problematic or perhaps not at all problematic.

Gypsum Composition Varies Gypsum Composition Varies


This quality variation of natural mined gypsum may account for the reason that there are so few actual complaint homes (only several thousand) compared to the potential number of problem homes based on the 7 million sheets of Chinese drywall imported.Much of the so-called problem imported drywall may actually be NO PROBLEM.Note: 7 million sheets of imported Chinese drywall will yield at least 30,000 Chinese drywall homes which is far more than the few thousand complaint homes.

Is Much of the Problem Drywall Is Much of the Problem Drywall Actually NO PROBLEM?Actually NO PROBLEM?


The rate of gas release is highly dependent on the temperature and humidity of the test environment.This will be the case for both lab studies and air sampling inside of homes.We need test standards for lab testing Chinese drywall so that results from different labs or different environmental consultants can be compared.

No Test StandardsNo Test Standards


Conclusions Conclusions

All brands of drywall will release some level of gases under lab conditions. According to recent CPSC research, lab testing pieces of drywall removed from a home’s walls in no way indicates either the types of gases or the quantity of gases to be found in actual homes.Lab testing that finds elevated gas released from drywall is NOT SUFFICIENT for determining that the home’s living environment has problems.

Lab Testing Does NOT Lab Testing Does NOT Indicate InIndicate In--Home Gas LevelsHome Gas Levels


As mentioned earlier, measured levels of Hydrogen Sulfide (H2S) in homes according to the US CPSC are very low –only a few parts per billion.If this is the case, then Chinese drywall odor MUST BE caused by other sources which according to the German research paper would be organic sulfur gases.

If H2S Levels in Homes Are If H2S Levels in Homes Are Really Close to ZeroReally Close to Zero


Conclusions Conclusions

These organic sulfur gases found to be released by Chinese drywall are characterized by having:–A very high odor level, and –Are neither corrosive nor irritating. This may account for the reason why some homes with Chinese drywall smell but do not irritate occupants.

Organic Sulfur Gases are Organic Sulfur Gases are NonNon--Irritating Irritating


Conclusions Conclusions Health Implications Health Implications

If … homes smell due to very low levels of non-irritant organic sulfur gases and

not from high levels of potentially irritating or harmful inorganic sulfur

gases like H2S and CS2, then likely there is negligible (or even no) occupant

irritation from Chinese drywall.


Conclusions Conclusions No Health Problems from No Health Problems from Sulfur Gases?Sulfur Gases?

There is limited science to substantiate the CPSC

conclusion of NO HEALTH PROBLEMS based on their not being able to measure elevated levels of sulfur

gases in homes.



AppendixAppendix

How Do The German How Do The German Scientist’s Results Scientist’s Results

Compare with the US Compare with the US Government Studies?Government Studies?


Conclusions Conclusions US Study US Study TabCTabC p424 p424

US study on Gas Emissions from Chinese drywall shows massive release of H2S, CS2, and COS and

not much else whereas the German studies (p 16 of this presentation) find 8 sulfur-containing organic compounds

(not H2S, CS2 or COS) contributing to off-odor.


The EPA (TABC) study shows massive off-gassing of H2S, CS2 and COS from Chinese drywall.But only trace amounts of a few organic sulfur gases are found.There is no attempt to explain why there are such large differences between their results and the German studies.

No ExplanationNo Explanation


The Government DOES attempt to explain why such very high levels of H2S, CS2 and COS are found being released by the drywall but not found in the indoor air of homes.Their hypothesis is that these gasses disappear once released by the drywall.They DO NOT address the fact that just about everyone else besides them routinely find these gases in the indoor air.

Gases Disappear? Gases Disappear?


What other reason could there be for the Government study finding H2S, CS2 and COS being off-gassed by the drywall but NOT found in the indoor air besides the gases completely disappear? –We believe, that the government’s indoor air

sampling collection and/or measurement procedures don’t work properly and underestimate the levels of these gases.

– The clear Tedlar bags they use for indoor air sampling are not appropriate for the collection of very low levels of light-sensitive unstable gases like H2S.

Wrong Collection BagsWrong Collection Bags


Our testing shows sulfur gases are measurable in homes but much higher in wall cavities. We have no doubt that sulfur gases dissipate to some degree once inside of homes but they do not disappear.We believe that the Government sampling procedures have low sensitivity but they should be able to detect sulfur gases when in higher concentrations in wall cavities.

Gases Dissipate But Do Not Gases Dissipate But Do Not DisappearDisappear


The Government testing protocol (Page 269 TabC) actually stated that air sample controls be taken from wall cavities. But this was NOT done.

Did Not Follow ProtocolDid Not Follow Protocol


Had the Government followed their own testing protocol to test wall cavities as well as indoor air, they would have seen:– High levels of sulfur gases are released by the

drywall as indicated by high levels of copper corrosion inside of wall cavities.

– Gas levels inside of homes are reduced but not eliminated.

– Gas levels inside of homes are highest near wall openings such as electrical plates.

NOT that sulfur gases completely disappear.

Gases Do NOT Completely Gases Do NOT Completely DisappearDisappear


The Government studies on indoor air levels of H2S, CS2, and COS had other missing or faulty controls besides not sampling wall cavities.The levels of the gasses they were looking for were down to parts per billion (ppb).But the control to see if the collection bags and instrumentation were working correctly was done at parts per million(ppm) – at a 1000 times higher level.

Other Missing or Faulty Other Missing or Faulty Controls Controls


Checking equipment calibration at parts per million and then using the

equipment to test gas levels 1000 times lower makes

NO SENSE.

Seemingly no thought was given to whether the equipment or procedures were adequate for testing low levels of

sulfur gases.

Other Missing ControlsOther Missing Controls


All of these problems cast doubt on the Government’s findings and their conclusion of No Health or Irritation Problems.This conclusion may in fact be true but the Science is not there yet to support it. More work with proper controls needs to be done.

What Does This Say About What Does This Say About Occupant Health?Occupant Health?

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