FINAL REPORT ON AN 

INDOOR ENVIRONMENTAL QUALITY ASSESSMENT OF 

RESIDENCES CONTAINING CHINESE DRYWALL 

Prepared For: 

Lori Saltzman, M.S. 

Director, Division of Health Sciences 

U. S. Consumer Product Safety Commission 

4330 East West Highway 

Bethesda, MD 20814 

Prepared By: 

Environmental Health & Engineering, Inc. 

117 Fourth Avenue 

Needham, MA 02494-2725 

January 28, 2010 

EH&E Report 16512 

This report was prepared for the Commission pursuant to contract CPSC-S-09-0027. It has not been 

reviewed or approved by, and may not necessarily reflect the views of, the Commission. 
Acknowledgments 

The results of this study were presented to members of the Interagency Task Force on 

November 9, 2009. Comments on the Draft Final Report on an Indoor Environmental 

Quality Assessment of Residences Containing Chinese Drywall, dated November 6, 

2009, were received from representatives of the following agencies: 

U.S. Consumer Product Safety Commission 

Centers for Disease Control and Prevention/Agency for Toxic Substances and 

Disease Registry 

U.S. Environmental Protection Agency 

U.S. Department of Housing and Urban Development 

National Institute of Standards and Testing 

Florida Department of Health 

Louisiana Department of Health and Hospitals 

We appreciate the reviewers’ insightful comments and constructive recommendations. 
TABLE OF CONTENTS 

1.0 EXECUTIVE SUMMARY ............................................................................................ 1

1.1 SYNOPSIS............................................................................................................ 1

1.2 INTRODUCTION AND OBJECTIVES................................................................... 2

1.3 METHODS ............................................................................................................ 4

1.4 RESULTS.............................................................................................................. 5

1.5 LIMITATIONS........................................................................................................ 7

2.0 INTRODUCTION......................................................................................................... 9

2.1 OVERVIEW AND OBJECTIVES ........................................................................... 9

2.2 BACKGROUND................................................................................................... 10

2.3 ORGANIZATION OF THE REPORT................................................................... 11

3.0 STUDY DESIGN ....................................................................................................... 13

3.1 OVERVIEW......................................................................................................... 13

3.2 STUDY POPULATION........................................................................................ 14

3.3 FIELD ACTIVITIES.............................................................................................. 17

3.4 SAMPLING SCHEDULE ..................................................................................... 19

4.0 SAMPLING AND ANALYTICAL METHODS ............................................................. 23

4.1 INTRODUCTION................................................................................................. 23

4.2 SOURCE DRYWALL MEASUREMENTS ........................................................... 23

4.3 AIR SAMPLING METHODS................................................................................ 24

4.4 AIR EXCHANGE RATE....................................................................................... 36

4.5 CORROSION ASSESSMENT............................................................................. 37

4.6 PROCEDURES FOR STATISTICAL ANALYSIS OF DATA ............................... 40

4.7 QUALITY ASSURANCE AND QUALITY CONTROL PROCEDURES................ 41

5.0 RESULTS.................................................................................................................. 61

5.1 SOURCE IDENTIFICATION ............................................................................... 61

5.2 INTEGRATED MEASURE OF EFFECT ............................................................. 65

5.3 AIR SAMPLING RESULTS ................................................................................. 75

6.0 DISCUSSION.......................................................................................................... 100

6.1 SUMMARY........................................................................................................ 100

6.2 SOURCE MARKERS ........................................................................................ 103

6.3 INDOOR AIR QUALITY..................................................................................... 108

6.4 CORROSION .................................................................................................... 112

6.5 HEALTH CONSIDERATIONS........................................................................... 115

6.6 COMPARISON TO CHAMBER STUDIES ........................................................ 119

6.7 LIMITATIONS.................................................................................................... 121

7.0 CONCLUSIONS...................................................................................................... 123

8.0 REFERENCES........................................................................................................ 125
TABLE OF CONTENTS (Continued) 

LIST OF APPENDICES 

Appendix A Summary Data Tables 

Appendix B Quality Assurance Project Plan 

LIST OF TABLES 

Table 3.1 Distribution of Ranking Classification of Complaint Homes 

Table 3.2 Summary of Basic Attributes for Case and Reference Homes by State 

Table 3.3 CPSC Study Core Assessment and Environmental Monitoring Parameters 

Table 3.4 General Schedule of Field Sampling and Inspection Activities Implemented 

as Part of the CPSC Study 

Table 4.1 Summary of Air Sampling Methods 

Table 4.2 Targeted Reduced Sulfur Gases and Laboratory Reporting Limits 

Table 4.3 Targeted Volatile Organic Compounds (VOCs) and Laboratory Reporting 

Limits 

Table 4.4 Targeted Aldehydes and Laboratory Reporting Limits 

Table 4.5 Summary of Target Parameters, Passive Air Sampling 

Table 4.6 Sampling Rates for Targeted Analytes for Passive Sampling 

Table 4.7 Passive Sampling, Targeted Analytes and Laboratory Reporting Limits 

Table 4.8 Targeted Organic and Inorganic Acids and Laboratory Reporting Limits 

Table 4.9 Quality Assurance and Quality Control Samples Collected During the 

Project 

Table 4.10 Calibration Procedures 

Table 4.11 Summary of Data Capture Efficiency for Air Samples 

Table 4.12 Summary of Detection Frequency for Air Sample Field and Shipping 

Blanks 

Table 4.13 Primary Estimate of Measurement Precision for Groups of Analytes in 

Indoor Air by Sampling Method 

Table 4.14 Primary Estimate of Measurement Precision for Specific Analytes in Indoor 

Air 

Table 4.15 Primary Estimate of Measurement Precision for XRF and FTIR 

Measurements 

Table 4.16 Coefficient of Variation, Inter-home Temperatures, Relative Humidity and 

Dew Point Temperature Measurements 

Table 5.1 2x2 Table Comparing CPSC Home Status and Objectively Measured 

Status Using FTIR/XRF 

Table 5.2 Major, Minor, and Trace Elemental Composition of Corrosion Coupons 

Analyzed by Energy Dispersive Spectroscopy 

Table 5.3 Corrosion Correlation Matrix 

Table 5.4 House Average Aldehyde (Active Sampler) Concentrations (μg/m3

) in 

Indoor Air by House Status 

Table 5.5 House Average Aldehyde (Passive Sampler) Concentrations (μg/m3

) in 

Indoor Air by House Status 

Table 5.6 House Average Concentrations (ppb) of Analytes Collected Using Passive 

Samplers 

Table 5.7 House Average VOC Concentrations (μg/m3

) in Indoor Air by House Status 
TABLE OF CONTENTS (Continued) 

LIST OF TABLES (Continued) 

Table 5.8 House Average Organic Acid Concentrations (ppb) in Indoor Air by House 

Status 

Table 5.9 Regression Model Results Showing Predictors of House Average Hydrogen 

Sulfide Concentrations (Natural log-transformed) in Indoor Air 

Table 5.10 Regression Model Results Showing Predictors of House Average Carbon 

Disulfide Concentrations (Natural log-transformed) in Indoor Air 

Table 5.11 Regression Model Results Showing Predictors of Silver Corrosion Rates at 

the AHU Air Register (Natural log-transformed) in Indoor Air 

Table 5.12 Regression Model Results Showing Predictors of Copper Corrosion Rates 

at the AHU Air Register (Natural log-transformed) in Indoor Air 

Table 5.13 Regression Model Results Showing Predictors of Silver Corrosion Rates at 

the AHU Air Register (Natural log-transformed) in Indoor Air 

Table 5.14 Regression Model Results Showing Predictors of Copper Corrosion Rates 

at the AHU Air Register (Natural log-transformed) in Indoor Air 

Table 5.15 Linear Mixed Effects Model Fixed Effects Results for Predictors of RoomSpecific Silver Corrosion Rates (Natural log-transformed) 

Table 5.16 Interaction Mode—Linear Mixed Effects Model Fixed Effects Results for 

Predictors of Room-Specific Silver Corrosion Rates (Natural logtransformed) 

Table 5.17 Linear Mixed Effects Model Fixed Effects Results for Predictors of RoomSpecific Copper Corrosion Rates (Natural log-transformed) 

Table 5.18 Regression Model Results Showing Predictors of House Average 

Formaldehyde levels (Natural log-transformed) in Indoor Air 

Table 6.1 Material Sensitivities to Atmospheric Corrodants 

LIST OF FIGURES 

Figure 2.1 Number and Percentage of Drywall Complaints Received as of September 

2009 

Figure 3.1 Locations of Participating Homes 

Figure 4.1 Example of Visual Corrosion Ratings, Electrical Ground Wire 

Figure 4.2 Comparison of Paired Sample and Duplicate Air Sample Measurements by 

Group 

Figure 4.3 Comparison of Paired Duplicate Air Sample Measurements for Selected 

Compounds 

Figure 4.4 Comparison of Paired Duplicate XRF Field and Laboratory Strontium 

Measurements 

Figure 4.5 Comparison of Paired Duplicate FTIR Laboratory Carbonate 

Measurements 

Figure 4.6 Comparison of Paired Duplicate Corrosion Rate Measurements for Copper 

and Silver Coupons 

Figure 5.1 Comparison of Cored Drywall Samples of Known Origin and Analyzed in a 

Laboratory Setting for Strontium Concentrations (ppm) Measured by XRF 

and Carbonate (Absorbance) Measured Using FTIR. See Figure for 

Legend of Sample Type 
TABLE OF CONTENTS (Continued) 

LIST OF FIGURES (Continued) 

Figure 5.2 Comparison of Cored Drywall Samples Obtained in the Field and Analyzed 

in a Laboratory Setting for Strontium Concentrations (ppm) Measured by 

XRF and Carbonate (Absorbance) Measured Using FTIR. White Circles 

Denote Points with Elevated Carbonate and Quartz and Identified as 

Containing Plaster (See Text for Explanation) 

Figure 5.3 Carbonate Levels Measured Using FTIR in Matched Samples of Plaster 

and Drywall and Core Material Alone in Drywall 

Figure 5.4 Photographs of Corrosion Coupons after Retrieval from One Noncomplaint Home (A) and Three Complaint Homes (B – D) 

Figure 5.5 Corrosion Rates at AHU Air Register for All 51 Homes, by Corrosion 

Species 

Figure 5.6 Corrosion Rates by Location within the Home and Outdoors 

Figure 5.7 Comparison of Corrosion Film Thickness by CPSC House Status 

Figure 5.8 Comparison of Corrosion Film Thickness by FTIR/XRF Marker 

Figure 5.9 Comparison of Mean Ground Wire Corrosion Rating by CPSC Home 

Status 

Figure 5.10 Comparison of Corrosion Film Thickness Across Study Regions 

Figure 5.11 Maximum Outdoor Temperature During the Sampling Period for Each 

Region 

Figure 5.12 Comparison of Corrosion Film Thickness by Formaldehyde Concentration 

Figure 5.13 Comparison of Corrosion Rates at the AHU Air Register by House 

Average Formaldehyde Concentration Measured Using 2-week Passive 

Monitors 

Figure 5.14a Comparison of Corrosion Rates at the AHU Air Register by House 

Average Hydrogen Sulfide Concentration Measured Using 2-week Passive 

Monitors 

Figure 5.14b Comparison of Corrosion Rates at the AHU Air Register by House 

Average Nitrogen Dioxide Concentration Measured Using 2-week Passive 

Monitors 

Figure 5.15 Boxplots of House Average Carbon Disulfide Concentrations by CPSC 

Home Status 

Figure 5.16 Comparison of Corrosion Film Thickness at the AHU Air Register by 

House Average Carbon Disulfide Concentration 

Figure 5.17 Comparison of Short-term, House Average Air Exchange Rates by CPSC 

House Status and FTIR/XRF Status 

Figure 5.18 Comparison of Corrosion Film Thickness at the AHU Air Register by Air 

Exchange Rate 

Figure 5.19 Boxplots of Indoor Temperature by CPSC Home Status 

Figure 5.20 Comparison of Dry Bulb Temperature and Dew Point to Silver and Copper 

Corrosion Rates 

Figure 5.21 House Average Hydrogen Sulfide Concentration (ppb) by a) CPSC House 

Status, and b) FTIR/XRF Marker 

Figure 5.22 Scatterplot Comparing House Average Hydrogen Sulfide Concentration 

(ppb) by Dew Point, Stratified by Drywall Type as Determined by 

FTIR/XRF Marker 
TABLE OF CONTENTS (Continued) 

LIST OF FIGURES (Continued) 

Figure 5.23 Boxplots of House Average Carbon Disulfide Concentrations by CPSC 

Home Status 

Figure 5.24 Comparison of Corrosion Film Thickness by FTIR/XRF Marker 

Figure 5.25 Scatterplot of House Average Silver Corrosion Rate by Indoor 

Formaldehyde Concentration, Stratified by the Presence or Absence of 

Hydrogen Sulfide 

Figure 5.26 Scatterplot Comparing House Average Formaldehyde Concentrations 

(μg/m3

) Across Temperature Ranges (°F) 

Figure 6.1 Comparison of Cored Drywall Samples of Known Origin and Analyzed in 

a Laboratory Setting for Strontium Concentrations (ppm) Measured by 

XRF and Carbonate (Absorbance) Measured Using FTIR 

Figure 6.2 Picture of One Wall from a Complaint Home (A) and Same Wall With 

Strontium Concentrations Measured Using XRF Through Paint (B) 

Demonstrating Two Different Drywall Boards in an Otherwise Uniformly 

Painted Wall 

Figure 6.3 Comparison of Strontium Concentrations of Co-located Samples 

Measured in the Field through Paint and/or Plaster, and samples 

measured of the Drywall Core in a Controlled Laboratory Setting 

Figure 6.4 Comparison of the Percent of Situ Samples >600 ppm Strontium and 

Home Status Determined Using the FTIR/XRF Marker 

Figure 6.5 Sulfur Dioxide (SO2) Concentrations inside Small-volume Chamber 

Studies Comparing Two Imported and One Domestic Drywall Sample 

under Varying Environmental Conditions 
TABLE OF CONTENTS (Continued) 

LIST OF ABBREVIATIONS AND ACRONYMS 

ACH air changes per hour 

Ag2S silver sulfide 

AgCl silver chloride 

AHU air handling unit 

ASTM American Society for Testing and Materials 

ASHRAE American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. 

ATSDR Agency for Toxic Substances and Disease Registry 

CDC Centers for Disease Control and Prevention 

CO2 carbon dioxide 

CPSC U. S. Consumer Product Safety Commission 

CS2 carbon disulfide 

CuO copper oxide 

Cu2S copper sulfide 

CV coefficient of variation 

DNPH 2,4-dinitrophenyl hydrazine 

DRIFTS diffuse reflectance infrared Fourier transform spectroscopy 

EDD electronic data delivery 

EDS energy dispersive spectroscopy 

EH&E Environmental Health & Engineering, Inc. 

EPA U.S. Environmental Protection Agency 

FOSC Field Operations Support Center 

FTIR Fourier transform infrared 

GC/MS gas chromatography/mass spectrometry 

GC/SCD gas chromatography method utilizing a sulfur chemiluminescence detector 

H2S hydrogen sulfide 

HF hydrogen fluoride 

HPLCUV high performance liquid chromatography coupled with an ultraviolet detector 

HVAC heating, ventilating, and air-conditioning 

IC ion chromatography 

LOD limit of detection 

ml/min milliliters per minute 

MRL minimum reporting limit 

NDIR non-dispersive infrared 

NIOSH National Institute for Occupational Safety and Health 

NO2 nitrogen dioxide 

O3 ozone 

OSHA U.S. Occupational Safety and Health Administration 

ppb parts per billion 

ppm parts per million 

QA/QC quality assurance, quality control 

QAPP quality assurance project plan 

ref referent group 

RfC reference concentration 

SEM scanning electron microscopy 

RMSE root mean square error 

SO2 sulfur dioxide 

VOC volatile organic compound 
TABLE OF CONTENTS (Continued) 

LIST OF ABBREVIATIONS AND ACRONYMS (Continued) 

XPS x-ray photoelectron spectroscopy 

XRF x-ray fluorescence 

μg/m3 micrograms per cubic meter 

°C degrees Celsius 

°F degrees Fahrenheit 
1.0 EXECUTIVE SUMMARY 

1.1 SYNOPSIS 

In late December 2008, the U.S. Consumer Product Safety Commission (CPSC) began 

to receive drywall related complaints from consumers with media reports identifying the 

potentially problematic drywall as “Chinese drywall.” The complaints were reported to 

include odors emanating from the drywall, corrosion of metal items inside the homes, 

and short-term health effects that were generally upper respiratory in nature. CPSC 

wanted to assess the environmental conditions that exist in representative complaint 

homes constructed with “Chinese drywall” and determine if those conditions could 

contribute to the health symptoms and material degradation being reported by some 

residents. 

Fifty-one homes in the Southeast U.S. were investigated in 2009 (41 complaint homes; 

10 non-complaint homes). Each home investigation included: 1) objective source 

characterization using Fourier transform infrared spectroscopy (FTIR) and x-ray 

fluorescence (XRF); 2) characterization of the indoor and outdoor environment including 

measurements of airborne compounds in multiple rooms using both short-term active 

sampling and two-week passive sampling (volatile organic compounds [VOCs], 

aldehydes, reduced sulfur gases, acids) as well as indicators of building performance 

(air exchange rate, temperature, dew point); and 3) assessment of corrosion potential in 

each home as determined by visual inspection and analysis of corrosion coupons 

consisting of silver and metal strips deployed during the two-week sampling period. 

Statistical analyses were performed to examine the relationship from source, to 

environment, to effect using the measured parameters. 

Results from this study indicate that the concentrations of strontium measured with XRF 

and carbonate ion (carbonate) using FTIR can be used in combination to reliably identify 

suspect drywall. Complaint homes were found to have significantly greater rates of 

copper and silver corrosion than non-complaint homes. Indoor air of complaint homes 

was more likely to contain low-level hydrogen sulfide compared to non-complaint homes. 

Moreover, hydrogen sulfide concentrations were positively associated with dew point, 

suggesting a possible interaction of the two that may be important for release or effects 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 1 of 128
of the gas. Hydrogen sulfide was also associated with both copper and silver corrosion. 

Formaldehyde concentrations were consistent between complaint and non-complaint 

homes, indicating they were related to sources inside the home and not the suspect 

drywall, and were also associated with corrosion in some rooms. There was suggestive 

evidence that the rate of silver corrosion associated with formaldehyde was dependent 

upon the presences of hydrogen sulfide, suggesting a potential synergistic effect with 

formaldehyde; it is unknown if the effect is due to formaldehyde itself or if formaldehyde 

is a surrogate for some other main effect (e.g., formic acid). All of the homes in the study 

had air exchange rates that are consistent with ”tight” homes and that may influence the 

relationships among hydrogen sulfide, formaldehyde, and other materials in the 

complaint homes. 

1.2 INTRODUCTION AND OBJECTIVES 

This document, entitled “Final Report on an Indoor Air Quality Assessment of 

Residences Containing Chinese Drywall,” was prepared on behalf of CPSC by 

Environmental Health & Engineering, Inc. (EH&E). This final report contains information 

and data that has been compiled by EH&E on 51 homes (41 complaint homes and 10 

non-complaint homes) evaluated as part of the overall study. All field work was 

completed between July 27 and September 30, 2009. 

This investigation was designed to identify critical parameters related to the potential for 

suspect imported Chinese drywall to adversely affect health and property by carefully 

examining the relationship between possible sources, environmental modifiers, and 

effects in homes. Although a variety of health concerns have been reported, this study 

was not intended to address this issue directly. The primary effect variable that has been 

utilized throughout this study is that of corrosion of metal surfaces. Corrosion of new 

metal surfaces is a direct and objective measure of a significant environmental outcome 

and serves as an integrated measurement that will directly account for the wide variety 

of corrosive gases that could be present in indoor environments. 

The specific aims of this study were to: 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 2 of 128
• Identify sensitive and specific markers of suspect imported Chinese drywall that 

could be used to positively identify potentially impacted homes. 

• Characterize the indoor and outdoor concentrations of various airborne compounds. 

These include reduced sulfur gases, sulfur dioxide, aldehydes, VOCs, inorganic 

acids, and organic acids of representative complaint and non-complaint homes. 

• Identify various building characteristics of subject homes, including: surface area of 

Chinese drywall, air exchange rates, temperature, indoor relative humidity, and dew 

point. 

• Evaluate the use of the rate of corrosion of metal objects in both complaint and noncomplaint homes as an integrated measure of effect consistent with the 

environmental parameters measured in the homes. 

• Examine relationships among drywall properties, building characteristics, 

constituents of indoor air, and rates of corrosion. 

• Evaluate measures that could potentially serve as indicators of respiratory and 

mucosal irritation. 

• Develop a meaningful and sensitive sampling protocol that could readily be deployed 

in the field for future studies. 

Although multiple studies have been performed by various federal and state agencies 

and several private entities, no consensus regarding the cause or resolution of the 

adverse environmental conditions found in homes containing Chinese drywall has been 

developed at this time. This is primarily due to the fact that emissions from Chinese 

drywall represent a complex, dynamic, unstable mixture of low-level contaminants. They 

are likely highly reactive and therefore may be rapidly scavenged from the air through 

the corrosion on metal surfaces, reactions with other compounds, or adsorption on 

various surfaces and therefore may not be present in ambient air for a long enough 

period of time to permit accurate characterization. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 3 of 128
1.3 METHODS 

This study was designed to be a detailed characterization of the indoor environment 

found in representative complaint homes that were selected by CPSC from their existing 

incident reporting database. This study also includes results from non-complaint 

residences that were recruited by CPSC to participate in this study based on their age of 

construction, proximity to complaint homes, and an understanding they were constructed 

without the use of Chinese drywall. 

The methods used to achieve the specific aims of this study are described in detail in the 

body of the report. The following section provides a brief overview for guidance in 

interpreting the results. 

• Markers of Chinese Drywall. Real-time measurements for strontium concentrations 

were made in the field using XRF to identify markers of imported Chinese drywall. 

Core sampling of drywall was also performed in each room of the subject homes and 

the samples returned to the laboratory for additional XRF analysis, as well as 

characterization using FTIR spectroscopy. 

• Characterization of Indoor and Outdoor Airborne Compounds. Active, short 

duration samples were collected for a number of indoor contaminants. These 

included reduced sulfur gases, aldehydes, VOCs, inorganic and organic acids. 

Additionally, in order to improve the limit of detection for many of the compounds of 

interest, as well as to utilize longer integration periods that are consistent with the 

period of exposure of the metal coupons, passive samplers were utilized to collect 

hydrogen sulfide, aldehydes, ozone, sulfur dioxide, nitrogen dioxide, and hydrofluoric 

acid over a two-week period. 

• Building Characteristics. Detailed mapping of the elemental composition of the 

drywall was performed using XRF throughout each study home. Air exchange rate 

measurements were collected using a standard tracer gas dilution procedure using 

carbon dioxide as the tracer gas. Temperature and indoor relative humidity were 

tracked over a two-week period utilizing continuous data logging sensors. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 4 of 128
• Characterization of Metal Corrosion. Pre-cleaned copper and silver coupons were 

placed in multiple locations in each home and were employed to determine the rate 

of corrosion at the subject homes over a two-week sampling period. Inspections of a 

variety of metal surfaces within each home were performed, and numerical rating 

criteria were implemented to characterize the amount of corrosion in each residence. 

• Examination of Relationships among Drywall Properties and Building 

Characteristics. Detailed statistical analysis was performed using correlation and 

regression analyses to identify factors and potential effect modifiers that could 

explain the corrosion effects found in the homes containing Chinese drywall 

compared to non-complaint homes. Statistical analysis included compiling 

descriptive statistics, scatter plots, and box plots. Bivariate statistical relationships 

were assessed using Spearman rank correlation and Wilcoxon rank sum tests. 

Generalized linear models were used for analysis of variance and multivariate 

regression, with linear mixed effects models used to account for within-home 

correlation in analyses that included multiple measures in a home (e.g., air samples 

taken at the same time in two rooms). 

1.4 RESULTS 

The results are described in detail in the body of this report. Key points are as follows. 

• The study found that the concentrations of strontium and carbonate ion (carbonate) 

determined in drywall can be used in combination to reliably characterize suspect 

imported drywall. Portable XRF and FTIR instruments were used to measure 

strontium and carbonate respectively in both samples of known origin, to effectively 

calibrate their response, and in the field to characterize samples of unknown origin. 

• Corrosion on metal surfaces was found to be significantly greater in the complaint 

houses than in the non-complaint houses. The corrosion effect was significant both 

when quantitative measures utilizing the corrosion coupons were used to measure 

the rate of corrosion, as well as when corrosion on ground wires found in the home 

was observed and rated by trained technicians. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 5 of 128
• The average air exchange rates measured in each home were similar for both the 

complaint and non-complaint homes. The air exchange rate study also showed that 

the houses in the sample were tightly sealed with short-term average air exchange 

rates ranging from 0.05 to 0.8 air changes per hour (ACH) with a median of 

0.19 ACH. This value is contrasted with the value of 0.4 ACH, which has been 

reported by many investigators (ASHRAE 2005) as the median of the current U.S. 

housing stock. These low air exchange rates may play an important role in the effect 

of gases and indoor environmental conditions on corrosion and possible exposures 

to indoor contaminants. 

• Hydrogen sulfide gas was found in the majority of complaint and in two noncomplaint homes as well as in some outdoor samples. The concentrations of 

hydrogen sulfide were significantly higher in complaint homes compared to noncomplaint homes 

• Hydrogen sulfide concentrations in air were associated with higher dew points for 

complaint homes. A positive association was observed between elevated dew points 

and hydrogen sulfide concentrations for homes with imported drywall. Hydrogen 

sulfide was present where the dew point reached typical room temperatures and 

condensation of water vapor would be expected. 

• Carbon disulfide concentrations varied between complaint and non-complaint 

homes, with median concentrations of 2.4 and 0.74 micrograms per cubic meter 

(μg/m3

) respectively. Statistical tests, while showing no difference, were limited by a 

reduced sample size for the carbon disulfide measurements. 

• Organic acids were detected in both complaint and non-complaint homes with no 

statistical difference observed between the two classifications of homes. 

• Hydrogen sulfide and formaldehyde concentrations in indoor air were associated with 

corrosion rates in the study homes. For silver, a potential interactive effect was seen 

with formaldehyde; the effect of formaldehyde on corrosion rates was dependent 

upon the presence of hydrogen sulfide. Formaldehyde may be a marker of some 

other factor associated with corrosion (e.g., formic acid). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 6 of 128
• Concentrations of aldehydes in the indoor air of both complaint and non-complaint 

homes did not differ significantly, but were generally greater than levels reported in 

the scientific literature for residences in various areas of the United States. These 

results may not be directly comparable for a number of reasons, chiefly related to the 

age of the homes from the various studies. However, when the data from this study’s 

houses are compared to data from recently constructed homes, the levels of 

formaldehyde and other aldehydes are comparable. This shows the importance of 

understanding the age of the home and other building characteristics when 

assessing the significance of some of these other compounds. 

1.5 LIMITATIONS 

This study was designed to characterize the air quality in homes that had health and/or 

corrosion complaints suspected to be associated with certain types of drywall. This 

“suspect” drywall is believed to originate and be imported from the People’s Republic of 

China. However, at this time there is insufficient evidence to support or refute the 

assertion that all Chinese-origin or imported drywall exhibits the health or corrosive 

characteristics reported in complaint homes. 

The intent of this sampling and analysis program was to elucidate the relationships 

between suspect drywall and environmental conditions existing in the home that could 

be characterized by use of objective measurements such as the rate of corrosion on 

metal surfaces. This study was designed as an in situ investigation in which the house 

was characterized in the “lived in” condition. (Certain exceptions to this “lived in” 

characterization, where the houses were unoccupied during the testing, were found to 

have a negligible impact on the primary findings.) So as to not possibly miss an 

important interaction effect, no attempt was made to restrict occupant activities, 

manipulate the mechanical systems or remove materials from the residence prior to, or 

during, sampling. 

The indoor environment of the complaint homes is complex, dynamic and in many ways 

challenging to characterize due to the low concentrations of the contaminants present 

and the highly reactive nature of many of the species of interest. It is also probable that 

there are important interactions between the materials emitted from the suspect drywall 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 7 of 128
and airborne compounds present in the indoor environment that may be associated with 

other sources, as well as specific home characteristics, that could cause, or be a 

significant contributor to, the complaints reported. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 8 of 128
2.0 INTRODUCTION 

2.1 OVERVIEW AND OBJECTIVES 

This report was prepared on behalf of CPSC by EH&E and describes an investigation of 

the relationship between indoor environmental quality and imported drywall in residential 

buildings. This study is one component of a multifaceted investigation being led by 

CPSC to evaluate the emissions from imported Chinese drywall. CPSC wanted to 

assess the environmental conditions that exist in representative homes constructed with 

this drywall and determine if those conditions could contribute to the health symptoms 

and material degradation being reported by some residents (CPSC 2009a). 

The objective of the in-home investigation was to characterize the indoor environment in 

representative complaint homes in detail, obtain air samples and other objective 

measurements that could be used for future risk assessments and examine homes for 

evidence of health stressors that could plausibly be related to drywall based on 

complaints and scientific information compiled by CPSC and EH&E. This was an 

exploratory study in which indoor environmental conditions for a sample of complaint 

homes were compared to conditions in a sample of non-complaint homes, and 

considered the context of normative values and relevant health benchmarks. The study 

design was not intended to compare homes individually but rather to compare two 

groups of homes (complaint versus non-complaint) under exposure conditions that 

would be considered typical under normal occupancy. Activities in this scope of work 

included the following elements: 

• Identify objective markers of imported drywall. 

• Measure reduced sulfur gases, sulfur dioxide, aldehydes, volatile organic 

compounds (VOCs), inorganic acids, and organic acids in indoor and outdoor air of 

representative complaint and non-complaint homes. 

• Ascertain building characteristics of test homes including surface area, air exchange 

rate, indoor temperature, and indoor relative humidity. 

• Determine the rate of corrosion for copper and silver objects in homes. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 9 of 128
• Examine relationships among drywall properties, building characteristics, 

constituents of indoor air, and rates of corrosion. 

• Evaluate measures that could potentially serve as indicators of respiratory and 

mucosal irritation. 

2.2 BACKGROUND 

In late December 2008, CPSC began to receive drywall related complaints from 

consumers (CPSC 2009c). The complaints are reported to include odors emanating from 

the drywall, corrosion of metal items inside the homes, and short-term health effects that 

were generally upper respiratory in nature. 

CPSC staff investigated four complaint homes in March 2009 and reported a noxious 

odor inside the homes, varying levels of corrosion in electrical outlets, circuit breakers, 

plumbing fixtures, and air-conditioning coils, and personally experienced respiratory 

irritation, headache, and eye irritation while inside the homes (CPSC 2009c). CPSC staff 

reported that the health symptoms dissipated after leaving the homes. 

Following the preliminary site visits, CPSC in conjunction with the U.S. Environmental 

Protection Agency (EPA), the Centers for Disease Control and Prevention (CDC), and 

the Agency for Toxic Substances and Disease Registry (ATSDR) initiated a multi-agency 

approach to investigate the drywall-related complaints. Information on the overall 

investigation and inter-agency coordination is available elsewhere (CPSC 2009a). 

As of September 2009, CPSC had received about 1,501 incident reports from 

24 states and the District of Columbia (CPSC 2009b). The majority of reports are from 

Florida, followed by Louisiana, Virginia, and other states (Figure 2.1). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 10 of 128
(Reproduced from CPSC 2009c) 

Figure 2.1 Number and Percentage of Drywall Complaints Received as of September 2009 

A number of reports related to imported drywall were completed by other groups prior to 

initiation of the CPSC in-home study. Results of an early in-home study in south Florida 

conducted on behalf of a supplier of building materials were released in 2006 (CTEH 

2007). In 2008, a study conducted on behalf of a homebuilder was released that 

examined levels of sulfide gases inside of homes reported to contain imported drywall 

(ENVIRON 2008). Also in 2008, investigators from a research center in Germany 

described their measurements of odorous emissions from drywall under laboratory 

conditions in a paper presented at a scientific conference (Burdack-Freitag et al. 2008). 

The State of Florida Department of Health and the EPA released results of preliminary 

sampling of drywall and copper materials in March and May 2009, respectively (EPA 

2009a; Unified Engineering Inc. 2009). Findings contained in these reports were 

considered in the design of the present study in addition to other information gathered by 

CPSC and various agencies. 

2.3 ORGANIZATION OF THE REPORT 

Following this introduction, the design of the in-home investigation is presented in 

Section 3. That section includes the specific aims of the study, basic information on the 

homes enrolled, schedule, and sampling plan. Section 4 contains details of the methods 

used to collect and analyze samples from the test homes as well as the quality 

assurance and quality control procedures implemented. Results of the field sampling 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 11 of 128
and laboratory analyses are summarized in Section 5 in the form of summary statistics 

for individual analytes in the test homes. Associations between constituents of indoor air 

and measures of corrosion as well as multivariate relationships among constituents of 

imported drywall, indoor air, and corrosion and other characteristics of the primary 

measurements are also provided in Section 5. A discussion of the study findings is 

presented in Section 6 including comparisons of results for complaint homes to 

corresponding levels observed in non-complaint homes. Finally, conclusions drawn from 

the in-home study are presented in Section 7. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 12 of 128
3.0 STUDY DESIGN

3.1 OVERVIEW 

As noted in Section 2, the objective of this investigation was to assess levels of a variety 

of environmental conditions in homes believed to be constructed with imported drywall 

based on criteria established by CPSC, henceforth referred to as complaint homes. The 

same methods were used to assess environmental conditions in a sample of noncomplaint homes also identified by CPSC. EH&E assessed environmental conditions of 

51 homes between July 27 and September 30, 2009, consisting of 41 complaint and 

10 non-complaint homes located in five states. 

Both integrated and discrete observations of environmental conditions were obtained 

from complaint and non-complaint homes, details of which are provided below. 

Integrated observations included two measures of corrosion: (i) rates of corrosion 

determined from copper and silver coupons exposed to indoor air in each home for two 

weeks and (ii) inspection and semi-quantitative rating of copper ground wires in 

accessible electrical outlets. Discrete measurements included short-term (grab sample 

to 4 hour average) and long-term (2 week) average concentrations of numerous organic 

and inorganic gases in indoor and outdoor air of participating homes. The elemental and 

mineral composition of drywall in homes was assessed in the field using non-destructive 

methods. Multiple bulk samples of drywall (including 400 square centimeters [cm2

] and 

1 cm2

 samples) were obtained from each home and returned to the laboratory for further 

analysis and archiving. To account for factors that could modify source-pathway-effect 

relationships, baseline physical and indoor air quality parameters were also determined 

for complaint and non-complaint homes including geographic coordinates, orientation, 

area, ventilation characteristics, air exchange rate, indoor temperature, and indoor 

relative humidity. All homes were evaluated under indoor environmental exposure 

conditions that were typical of those experienced by occupants. Potential indoor sources 

such as cleaning supplies, air fresheners, etc. were not removed from the home, 

although homeowners were requested to not use these products throughout the 

sampling period. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 13 of 128
Summary statistics generated from the field data and observations obtained from 

complaint homes were compared to corresponding measures obtained from a sample of 

non-complaint homes selected by CPSC. Relationships between rates of corrosion and 

discrete measures of organic and inorganic gases were explored using correlation 

analysis and other descriptive methods. Multivariate models were used to examine multifactorial relationships among the corrosion, indoor air quality, drywall composition, and 

housing characteristics information gathered from participating homes. 

3.2 STUDY POPULATION 

The study population was comprised of 51 residential buildings, primarily detached 

single-family residences in five states including 41 homes that submitted drywall related 

incident reports to CPSC between December 23, 2008, and June 5, 2009, (complaint) 

and 10 non-complaint homes selected from the same neighborhoods as complaint 

homes. CPSC recruited all homes into the study. 

3.2.1 Eligibility Criteria 

Potential target homes for the study were selected by CPSC based on specific criteria 

that considered geography and reports of health effects and corrosion. In terms of 

geography, homes were selected from communities in coastal Florida (Gulf and Atlantic 

coast) and coastal areas of Louisiana, Mississippi, Alabama, and Virginia as these 

states ranked high in complaint frequency in reports received by CPSC (CPSC 2009b). 

To select the complaint homes, CPSC used information gathered from incident reports 

to develop an ordinal scale for severity of a complaint. For this ranking system, homes 

were assigned a score from 0 to 7 based on the number of factors noted in the incident 

report. These factors included; 1) heating, ventilating, and air-conditioning (HVAC) 

corrosion, 2) plumbing corrosion, 3) wiring corrosion, 4) appliance failures/corrosion, 5) 

the presence of odor, 6) health issues, and 7) period of construction (between 2006 and 

2007). For example, an incident report that identified only the presence of odor would be 

assigned a ranking of 1, while a report that identified HVAC corrosion, plumbing 

corrosion, wiring corrosion, health effects, odor, and constructed between 2006 and 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 14 of 128
2007 would be assigned a ranking of 6. The distribution of ranking score for the 41 

complaint homes based on the CPSC criteria is provided in Table 3.1. 

Table 3.1 Distribution of Ranking Classification of Complaint Homes 

Ranking Classification 

2 3 4 5 6 7 

Number of Homes 1 7 6 8 11 8 

Ranking classification represents combination of the following number of factors 

• HVAC corrosion 

• plumbing corrosion 

• wiring corrosion 

• appliance failures/corrosion 

• presence of odor 

• health issues 

• period of construction between 2006 and 2007 

Non-complaint homes were located geographically proximate to complaint homes such 

that they would have similar ambient conditions to that of the complaint homes. These 

homes had no observed or reported corrosion and residents had not reported recent 

onset of health effects. The non-complaint homes had similar attributes to the complaint 

homes including the period of construction, style of home, and floor area. 

3.2.2 Home Locations 

As described in Section 3.2, the study evaluated 51 homes in five states including 

Florida, Louisiana, Mississippi, Alabama, and Virginia. Figure 3.1 provides a graphical 

representation of the locations of the study homes. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 15 of 128
Figure 3.1 Locations of Participating Homes 

3.2.3 Home Characteristics 

Selected descriptive characteristics of the participating homes are summarized by state 

and status in Table 3.2. Complaint and non-complaint homes were approximately 

3,000 square feet in size on average. Forty-six of the homes were single-family 

residences. The homes evaluated consisted of typical residential style construction 

including wood and or metal framing and concrete, brick, or wood exterior. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 16 of 128
Table 3.2 Summary of Basic Attributes for Case and Reference Homes by State

Region State Status 

Number of 

Homes 

Average 

Home Floor 

Area (ft2) 

Single 

Family 

Multi 

Family 

Florida East Florida Non-complaint 2 3,350 1 1 

Complaint 13 3,307 11 2 

Florida West Florida Non-complaint 3 2,183 3 0 

Complaint 10 2,439 10 0 

Gulf Coast Louisiana Non-complaint 2 7,258 2 0 

Complaint 8 3,141 8 0 

Gulf Coast Alabama Non-complaint 1 2,500 1 0 

Complaint 2 2,840 2 0 

Gulf Coast Mississippi Non-complaint 0 – – – 

Complaint 2 2,750 2 0 

Virginia Virginia Non-complaint 2 4,350 2 0 

Complaint 6 3,050 4 2 

ft2

 square feet 

3.3 FIELD ACTIVITIES 

3.3.1 Integrated Measures—Corrosion 

Objective measures of corrosion rates were obtained from copper and silver coupons 

placed at four locations within each home—the forced air supply register, the central 

living area, the master bedroom and a second bedroom—as well as at an outdoor 

location. The coupons were exposed to indoor air for two weeks and rates of corrosion 

were quantified from the thickness of the resulting corrosion layer. To complement the 

rates of corrosion determined from the coupons, evidence of existing corrosion in each 

home was obtained from an inspection of copper ground wires in accessible electrical 

outlets and other accessible metal objects such as air handlers and water pipes. The 

metal objects in these locations were inspected and the extent of corrosion was 

recorded on a 3 point ordinal scale. 

3.3.2 Discrete Measures—Gases in Indoor Air 

Discrete observations of organic and inorganic gases were obtained through active and 

passive sampling of indoor and outdoor air of complaint and non-complaint homes. 

Active air sampling involved collection of grab samples of whole air for subsequent 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 17 of 128
analysis of reduced sulfur gases and 2 to 4 hour time-integrated samples for aldehydes, 

inorganic acids, organic acids, and VOCs. Passive samplers for sulfur dioxide, 

aldehydes, hydrogen sulfide, ozone, nitrogen dioxide, and hydrofluoric acid were 

deployed for two weeks in each home. 

Contemporaneous samples for each active (including time-integrated and grab samples) 

and passive sampling system were obtained at three indoor locations in each home. 

These locations included the central living area, the master bedroom, and a second 

bedroom on the opposite side of the residence. An outdoor sampling location, free from 

interferences, i.e., away from roadways, exhausts, etc. was also selected for placement 

of samplers. 

A summary of the types of indoor air samples obtained from complaint and noncomplaint homes and the corresponding sampling durations is provided in Table 3.3. 

Table 3.3 CPSC Study Core Assessment and Environmental Monitoring Parameters 

Monitoring Parameter Sampling Duration 

Volatile organic compounds (active)* 120 minutes 

Aldehydes (active) 200 minutes 

Inorganic acids (active) 200 minutes 

Organic acids (active) 200 minutes 

Reduced sulfur gases Grab sample 

Sulfur dioxide (passive) 2 weeks 

Aldehydes (passive) 2 weeks 

Hydrogen sulfide (passive) 2 weeks 

Ozone (passive) 2 weeks 

Hydrofluoric acid (passive) 2 weeks 

Nitrogen dioxide (passive) 2 weeks 

CPSC U. S. Consumer Product Safety Commission 

* Volatile organic compound (VOC) sampling was not selected as a core measurement 

parameter and was conducted in a subset of the participating homes. VOC samples were 

collected in 31 of the 51 homes studied. 

3.3.3 Characterization of Drywall 

Another specific aim of this investigation was to evaluate various objective indicators of 

imported drywall that would be useful in characterizing homes. To identify objective 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 18 of 128
indicators, EH&E conducted a preliminary laboratory study in which selected elemental 

and mineral characteristics of imported drywall samples obtained from CPSC were 

contrasted with those of domestic drywall samples. Sensitive and specific methods of 

identifying imported drywall based upon elemental composition determined by x-ray 

fluorescence (XRF) and mineral composition determined by Fourier transform infrared 

spectroscopy (FTIR) spectroscopy were identified during this study. These methods 

were employed in the field to characterize the amount of imported and domestic drywall 

in complaint and non-complaint homes. At least one field measurement of elemental and 

mineral composition was obtained from each interior wall of complaint and noncomplaint homes. In addition to measurements made in the field, multiple bulk samples 

were obtained from each study home and returned to the EH&E facility in Needham, 

Massachusetts, for further characterization and archiving. 

3.3.4 Residential Characteristics 

To account for other factors that could influence source-pathway-effect relationships, 

physical attributes and indoor air quality parameters of the study homes were also 

obtained by field personnel. These factors included square footage, ventilation design, 

air exchange rate, temperature, and relative humidity. 

Temperature and relative humidity monitors were placed at two or three of the sampling 

locations (depending on the characteristics of the home) and were set to continuously 

log conditions over the course of the two week sampling period. 

Field personnel also conducted a visual inspection of the home and completed a 

baseline questionnaire, including an inspection to document general home construction 

related characteristics and the visual assessment of corrosion noted in Section 3.3.1. 

3.4 SAMPLING SCHEDULE 

The field activities in each home were completed during two site visits to the home. During 

the first site visit, field activities were implemented by a three person team (accompanied 

by a CPSC investigator) and were completed over the course of a nine to ten hour visit 

(8:00 a.m. to 5:00 p.m.) The second site visit occurred approximately two weeks after the 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 19 of 128
first, and field activities during the second visit were completed by a single field 

investigator. The sequence of activities completed in each home are described below and 

summarized in the daily activity schedule provided as Table 3.4. 

Table 3.4 General Schedule of Field Sampling and Inspection Activities Implemented as Part 

of the CPSC Study 

Day 1 

8:00 – 8:30 a.m. • Arrive at test home to unpack, setup and calibrate equipment. 

8:30 – 9:00 a.m. • Select three indoor and one outdoor air sampling locations 

• Set up and start continuous temperature and relative humidity monitors 

• Set up active air monitoring equipment for volatile organic compounds, 

aldehydes, organic and inorganic acids 

9:00 – 11:00 a.m. • Start active air sampling 

• Begin home inspection and questionnaire 

• Begin XRF wall survey 

11:00 a.m. – 

12:00 p.m. 

• End active air sampling 

• Begin bulk sampling of drywall from areas behind electrical outlet and 

switch plates 

• Set up and start continuous carbon dioxide monitors 

• Begin carbon dioxide release throughout the home (air exchange rate 

assessment) 

1:00 – 3:00 p.m. • Continue and complete home inspection activities and questionnaire 

• Continue and complete XRF wall survey 

• Continue and complete drywall bulk sampling of areas behind electrical 

outlet and switch plates 

3:00 – 4:00 p.m. • Set up and start passive air sampling equipment for sulfur dioxide, 

nitrogen dioxide, hydrogen fluoride, hydrogen sulfide, aldehydes, and 

ozone 

• Set up and expose silver and copper coupons 

4:00 – 5:00 p.m. • Collect reduced sulfur samples 

5:00 p.m. • Depart the test home 

Day 12 to 15 

Time varies • Collect passive air samplers 

• Collect temperature and relative humidity monitors 

• Collect silver and copper coupons 

XRF x-ray fluorescence 

Field personnel arrived at each subject home at approximately 8:00 a.m. and began the 

unpacking, set-up, and calibration of equipment. Once inside the home, the field 

personnel selected the indoor and outdoor locations where all active and passive 

environmental sampling and monitoring were to be conducted. Following the selection of 

the indoor sites, temperature and relative humidity monitors were placed at two or three 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 20 of 128
of the locations (depending on the characteristics of the home) and were set to 

continuously log conditions over the course of the two week monitoring period. 

At 9:00 a.m. active air sampling equipment was set up at the indoor locations and at the 

outdoor location to measure VOCs (implemented in a subset of homes), aldehydes, 

inorganic acids, and organic acids. VOC samplers were set up in two or three indoor 

locations with one duplicate, and at one outdoor location. One field blank was included 

for every ten samples. Similarly, aldehydes, inorganic acids, and organic acids were 

collected at three indoor locations with one duplicate and one field blank or shipping 

blank. The active air sampling systems were started at approximately 9:00 a.m. and 

sampled for approximately 200 minutes. While active air samples were being collected, 

field personnel began a survey of all walls in the home using a handheld XRF analyzer. 

During this time, field personnel also initiated the visual home inspection to document 

general home construction related characteristics and visual assessment for corrosion 

and completing the questionnaire. 

Once the active air sampling was completed, field personnel collected small bulk 

samples of drywall from behind the cover plates of light switches and electrical boxes. 

The number of bulk samples collected varied based on the size of the home. Generally 

twenty to twenty-five samples were collected in each home. In addition, at each of the 

light switch and electrical boxes where bulk samples were collected, field personnel 

documented the condition of the copper electrical ground in terms of the level of 

corrosion identified. The drywall at each of these light switches and electrical boxes was 

also scanned utilizing a handheld XRF analyzer. Following the completion of active air 

sampling, the home air exchange rate was evaluated by releasing carbon dioxide (CO2) 

throughout the home and monitoring the decay in CO2 concentration over time. CO2

monitors were placed at the three indoor sampling locations and continuously recorded 

the concentration of the gas over the test period. 

During the afternoon hours, field personnel continued with the XRF wall survey, the 

home inspection/questionnaire, and the bulk sampling. Once CO2 monitoring was 

completed, passive air sampling equipment for sulfur dioxide (SO2), nitrogen dioxide 

(NO2), hydrogen fluoride (HF), hydrogen sulfide (H2S), aldehydes, and ozone (O3) were 

set up and the passive air sampling program was started. Passive air samplers were 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 21 of 128
placed at the three indoor locations and one outdoor location. One duplicate and one 

field blank or shipping blank was obtained from each home. The passive air samplers 

were deployed for approximately two weeks. 

To measure the integrated rate of corrosion, copper/silver coupons were placed at the 

three indoor sampling locations, at one outdoor location, and at the outlet of a supply air 

register for the air conditioning unit serving the home. Finally, grab samples of whole air 

for analysis of reduced sulfur gases was initiated late in the day in order to ensure that 

samples were received by the laboratory within 24 hours of the sample collection time. 

Samples for reduced sulfur gas analysis were obtained from the three indoor locations, 

with one duplicate, and from one outdoor location. 

A single field investigator returned to the home approximately two weeks following the 

date of the initial survey to collect the passive air samplers, temperature and relative 

humidity monitors, and copper/silver coupons. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 22 of 128
4.0 SAMPLING AND ANALYTICAL METHODS 

4.1 INTRODUCTION 

EH&E conducted a series of measurements in each complaint and non-complaint home 

to assess multiple environmental parameters. The following sections describe the 

sampling and analytical procedures used to collect data in each home included in the 

study, the procedures used to analyze and process the data, and a general outline of the 

quality assurance, quality control (QA/QC) procedures implemented by EH&E. 

4.2 SOURCE DRYWALL MEASUREMENTS 

Material characteristics of representative sections of drywall from each complaint and 

non-complaint home were determined using x-ray fluorescence (XRF) and Fourier 

transform infrared (FTIR) spectrometry. As described below, the elemental composition 

analysis was conducted using XRF in the field at each home. More detailed analyses, 

using a combination of XRF and FTIR were subsequently obtained in the laboratory from 

the bulk samples of drywall collected and archived from each home. 

4.2.1 X-Ray Fluorescence (XRF) Analysis 

An XRF Spectrometer (Innov-X ALPHATM Handheld XRF, Innov-X Systems, Inc., 

Woburn, Massachusetts) provided on-site and laboratory metals analysis in this study. 

This device is a handheld portable XRF analyzer and was used to identify and quantify 

the elements in representative wall surfaces in each home as well as in the bulk samples 

collected from each home. 

At least one XRF measurement was obtained from each wall and ceiling surface in all of 

the homes included in the study. In-home measurements were taken through any wall 

coatings such as paint or plaster. The elemental scanning profile for each location was 

stored on the internal flash memory card of the XRF. The location of each measurement 

was marked on a floor plan and recorded in the master field log binder. Data files were 

downloaded daily and saved on a central file server. In addition, drywall bulk samples 

collected from each of the homes were scanned, analyzed and downloaded with the 

XRF software package in EH&E’s main facility. Between 10 and 49 (average 23) bulk 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 23 of 128
samples of drywall, depending on the size of the home, were collected from each test 

house and analyzed using XRF at EH&E’s facility. Analysis of the drywall samples 

removed from the home was conducted on the bulk material and not through paint or 

paper layers. 

4.2.2 Fourier Transform Infrared (FTIR) Analysis 

Bulk samples of drywall collected from the study homes were tested using FTIR at 

EH&E’s main facility. FTIR measurements were obtained using the A2 Technologies 

Exoscan instrument, a full scanning Fourier transform mid-infrared spectrometer, 

equipped with a Michelson interferometer and non-hydroscopic optics. The diffuse 

reflectance Exoscan was configured for porous and rough surfaced materials. It has an 

optical design that focuses an infrared light beam perpendicular to the sample surface 

resulting in diffusely scattered infrared light. This scattered infrared light interacts with 

the sample and is subsequently reflected back to the detector in the Exoscan. This 

diffuse reflectance configuration provides spectra for drywall analysis. The diffuse 

reflectance infrared Fourier transform spectroscopy (DRIFTS) technique has been 

widely accepted as a highly sensitive means of measuring inorganic compounds. DRIFT 

spectra of pure non-diluted minerals are different in appearance from more traditional 

FTIR spectra due to several very intense absorbance bands that appear as negative 

peaks (specular) and multiple weaker absorbance bands which are observed as positive 

peaks (diffuse). DRIFT technology was used in this study to obtain FTIR measurements. 

The representative drywall bulk samples collected from each of the homes, between 10 

and 49 (average 23) bulk drywall samples depending on the size of the home, were 

collected from each house and analyzed using FTIR. Each sample was scanned, 

analyzed, and the results downloaded with the A2 Technologies Microlab PC software 

package. 

4.3 AIR SAMPLING METHODS 

Air samples were collected in representative areas of each home and analyzed using 

standard reference methods. Table 4.1 summarizes the air sampling methods used, the 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 24 of 128
analytes or groups of analytes, and the analytical methods used throughout this study. A 

complete list of the specific analytes is described in Sections 4.3.1 through 4.3.6. 

Table 4.1 Summary of Air Sampling Methods

Analyte(s) 

Sampling 

Method Analytical Method 

Reference 

Method 

Report 

Section 

Reduced Sulfur 

Gases 

Whole air, grab, 

Tedlar bags 

GC/SCD ASTM D5504 4.3.1 

VOCs Whole air, 

SUMMA canister 

GC/MS EPA TO-15 4.3.2 

Aldehydes (active) Sorbent tube HPLC EPA TO-11A 4.3.3 

Passive Diffusion 

• Aldehydes 

• Hydrogen sulfide 

• Ozone 

• Sulfur dioxide* 

• Nitrogen dioxide* 

• Hydrofluoric acid* 

Radiello Diffusive 

Sampling System 

Various, see section 

4.3.4 

Various, see 

section 4.3.4 

4.3.4 

Inorganic acids Sorbent tube Ion chromatography NIOSH 7903 4.3.5 

Organic acids Sorbent tube Ion chromatography NIOSH 2011 4.3.5 

Temperature and 

relative humidity 

Real-time 

monitor 

Thermistor, thin-film 

capacitive sensor 

Manufacturer 4.3.6 

GC/SCD gas chromatography method utilizing a sulfur chemiluminescence detector 

ASTM American Society for Testing and Materials 

VOC volatile organic compound 

GC/MS gas chromatography/mass spectrometry 

EPA U.S. Environmental Protection Agency 

HPLC high performance liquid chromatography 

NIOSH National Institute for Occupational Safety and Health 

* Sulfur dioxide, nitrogen dioxide, and hydrofluoric acid collection and analysis performed using the 

same cartridge. 

4.3.1 Reduced Sulfur Gases 

Grab air samples were collected and analyzed for a suite of twenty reduced sulfur gases 

during the study. Whole air samples were collected into Tedlar Bags (Zefon 

International) using the SKC Vac-U-ChamberTM. The Vac-U-Chamber is a rigid box that 

allows air sampling bags to be filled directly (without sample air passing through a pump) 

from ambient atmospheres through use of negative pressure differentials; all surfaces 

that came in contact with sample air were constructed of stainless steel or Teflon tubing 

(SKC Cat. No. 231-940). The sampling pumps used to fill/evacuate the chambers were 

adjusted to a nominal flow rate of 1.0 liter per minute and each grab sample was 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 25 of 128
collected for approximately 30 – 45 seconds for a total volume of approximately 0.5 to 

0.75 liters for each sample. 

Air samples were collected at three indoor locations and one outdoor location per test 

house. In addition, one duplicate sample was collected per sample set at each home 

(the analytical laboratory was blinded to all sample designations including duplicate 

samples). Due to the reactive nature of many reduced sulfur gases, the reference 

method (American Society for Testing and Materials [ASTM] Method D5504) 

recommends that sample analysis occur within 24-hours of collection. To satisfy this 

requirement, the reduced sulfur samples were collected at each test home and shipped 

to the analytical laboratory via first priority overnight delivery. 

The reduced sulfur compound analysis was performed according to ASTM Method 

D5504 Standard Test Method for Determination of Sulfur Compounds in Natural Gas 

and Gaseous Fuels by Gas Chromatography and Chemiluminescence. ASTM D5504 is 

a gas chromatography method with a sulfur chemiluminescence detector (GC/SCD). The 

chemical analyses were conducted by Columbia Analytical Services, Inc., Simi Valley, 

California. Table 4.2 shows the reduced sulfur compound analytes and the laboratory 

reporting limits for each analyte. Statistical analysis of duplicate samples is further 

discussed in Section 4.7.9. 

Table 4.2 Targeted Reduced Sulfur Gases and Laboratory Reporting Limits

Compound CAS # Laboratory Reporting Limit (μg/m3

) 

2,5-Dimethylthiophene 638-02-8 23 

2-Ethylthiophene 872-55-9 23 

3-Methylthiophene 616-44-4 20 

n-Butyl Mercaptan 109-79-5 18 

Carbon Disulfide 75-15-0 7.8 

Carbonyl Sulfide 463-58-1 12 

Diethyl Disulfide 110-81-6 12 

Diethyl Sulfide 352-93-2 18 

Dimethyl Disulfide 624-92-0 9.6 

Dimethyl Sulfide 75-18-3 13 

Ethyl Mercaptan 75-08-1 13 

Ethyl Methyl Sulfide 624-89-5 16 

Hydrogen Sulfide 7783-06-4 7 

Isobutyl Mercaptan 513-44-0 18 

Isopropyl Mercaptan 75-33-2 16 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 26 of 128
Table 4.2 Continued

Compound CAS # Laboratory Reporting Limit (μg/m3

) 

Methyl Mercaptan 74-93-1 9.8 

n-Propyl Mercaptan 107-03-9 16 

Tetrahydrothiophene 110-01-0 18 

Thiophene 110-02-1 17 

tert-Butyl Mercaptan 75-66-1 18 

CAS# Chemical Abstract Service number 

μg/m3

 micrograms per cubic meter 

4.3.2 Volatile Organic Compounds 

Whole air samples for VOCs were collected with individually cleaned and certified 

SUMMA canisters obtained from Columbia Analytical Services, Inc. located in Simi 

Valley, California. Each flow controller used to fill the SUMMA canisters during sampling 

was also calibrated and conditioned by Columbia Analytical Services, Inc. prior to each 

use. Flow controllers were calibrated for two-hour sample durations. Canisters were 

protected from radiant heat as well as moisture prior to, during, and after sampling. 

In the homes selected for VOC sampling, SUMMA canister samples were collected at 

two to three indoor locations and at one outdoor location. A duplicate sample was 

collected for every 10 primary samples collected and sent to the analytical laboratory as 

a blinded sample. A minimum of one field blank sample was sent to the laboratory for 

analysis for every ten primary samples collected. These procedures were used to 

assess potential canister contamination during shipping, preparation or analysis of the 

samples. Statistical analysis of blank and duplicate samples is further discussed in 

Section 4.7.9. 

VOC samples were analyzed using gas chromatography/mass spectrometry (GC/MS). 

The analyses were performed according to EPA Method TO-15 from EPA’s Second 

Edition Compendium of Methods for the Determination of Toxic Organic Compounds in 

Ambient Air. Table 4.3 shows the specific VOCs and the laboratory reporting limits. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 27 of 128
Table 4.3 Targeted Volatile Organic Compounds (VOCs) and Laboratory Reporting Limits

Compound CAS # Laboratory Reporting Limits (μg/m3) 

1,1,1-Trichloroethane 71-55-6 0.12 – 0.62 

1,1,2,2-Tetrachloroethane 79-34-5 0.12 – 0.62 

1,1,2-Trichloroethane 79-00-5 0.12 – 0.62 

1,1,2-Trichlorotrifluoroethane 76-13-1 0.12 – 0.62 

1,1-Dichloroethane 75-34-3 0.12 – 0.62 

1,1-Dichloroethene 75-35-4 0.12 – 0.62 

1,2,4-Trichlorobenzene 120-82-1 0.12 – 3.1 

1,2,4-Trimethylbenzene 95-63-6 0.61 – 3.1 

1,2-Dibromo-3-chloropropane 96-12-8 0.61 – 3.1 

1,2-Dibromoethane 106-93-4 0.12 – 0.62 

1,2-Dichloro-1,1,2,2-tetrafluo 76-14-2 0.61 – 3.1 

1,2-Dichlorobenzene 95-50-1 0.12 – 0.62 

1,2-Dichloroethane 107-06-2 0.12 – 0.62 

1,2-Dichloropropane 78-87-5 0.12 – 0.62 

1,3,5-Trimethylbenzene 108-67-8 0.61 – 3.1 

1,3-Butadiene 106-99-0 0.12 – 0.62 

1,3-Dichlorobenzene 541-73-1 0.12 – 0.62 

1,4-Dichlorobenzene 106-46-7 0.12 – 0.62 

1,4-Dioxane 123-91-1 0.61 – 3.1 

2-Butanone (MEK) 78-93-3 0.61 – 3.1 

2-Hexanone 591-78-6 0.61 – 3.1 

2-Propanol (isopropyl alcohol) 67-63-0 0.61 – 3.1 

3-Chloro-1-propene (allyl chloride) 107-05-1 0.12 – 0.62 

4-Ethyltoluene 622-96-8 0.61 – 3.1 

4-Methyl-2-pentanone 108-10-1 0.61 – 3.1 

Acetone 67-64-1 6.1 – 31 

Acetonitrile 75-05-8 0.61 – 1.4 

Acrolein 107-02-8 0.61 – 3.1 

Acrylonitrile 107-13-1 0.61 – 3.1 

Benzene 71-43-2 0.12 – 0.62 

Benzyl chloride 100-44-7 0.12 – 0.62 

Bromodichloromethane 75-27-4 0.12 – 0.62 

Bromoform 75-25-2 0.61 – 3.1 

Bromomethane 74-83-9 0.12 – 0.62 

Carbon disulfide 75-15-0 0.61 – 3.1 

Carbon tetrachloride 56-23-5 0.12 – 0.62 

Chlorobenzene 108-90-7 0.12 – 0.62 

Chloroethane 75-00-3 0.12 – 0.62 

Chloroform 67-66-3 0.12 – 0.62 

Chloromethane 74-87-3 0.12 – 0.62 

Cumene 98-82-8 0.61 – 3.1 

Cyclohexane 110-82-7 0.61 – 3.1 

Dibromochloromethane 124-48-1 0.12 – 0.62 

Dichlorodifluoromethane (CFC 1) 75-71-8 0.61 – 3.1 

Ethanol 64-17-5 6.1 – 31 

Ethyl acetate 141-78-6 0.61 – 6.2 

Ethylbenzene 100-41-4 0.61 – 3.1 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 28 of 128
Table 4.3 Continued

Compound CAS # Laboratory Reporting Limits (μg/m3) 

Hexachlorobutadiene 87-68-3 0.12 – 3.1 

Methyl Methacrylate 80-62-6 0.61 – 6.2 

Methyl tert-Butyl Ether 1634-04-4 0.12 – 0.62 

Methylene Chloride 75-09-2 0.61 – 3.1 

Naphthalene 91-20-3 0.24 – 3.1 

Propene 115-07-1 0.61 – 3.1 

Styrene 100-42-5 0.61 – 3.1 

Tetrachloroethene 127-18-4 0.12 – 0.62 

Tetrahydrofuran (THF) 109-99-9 0.61 – 3.1 

Toluene 108-88-3 0.61 – 3.1 

Trichloroethene 79-01-6 0.12 – 0.62 

Trichlorofluoromethane 75-69-4 0.12 – 0.62 

Vinyl acetate 108-05-4 6.1 – 31 

Vinyl chloride 75-01-4 0.12 – 0.62 

alpha-Pinene 80-56-8 0.61 – 3.1 

cis-1,2-Dichloroethene 156-59-2 0.12 – 0.62 

cis-1,3-Dichloropropene 10061-01-5 0.61 – 3.1 

d-Limonene 5989-27-5 0.61 – 3.1 

m,p-Xylenes 179601-23- 0.61 – 3.1 

n-Butyl acetate 123-86-4 0.61 – 3.1 

n-Heptane 142-82-5 0.61 – 3.1 

n-Hexane 110-54-3 0.61 – 3.1 

n-Nonane 111-84-2 0.61 – 3.1 

n-Octane 111-65-9 0.61 – 3.1 

n-Propylbenzene 103-65-1 0.61 – 3.1 

o-Xylene 95-47-6 0.61 – 3.1 

trans-1,2-Dichloroethene 156-60-5 0.12 – 0.62 

trans-1,3-Dichloropropene 10061-02-6 0.61 – 3.1 

CAS# Chemical Abstract Service number 

μg/m3

 micrograms per cubic meter 

Acetonitrile was not determined during analysis for several VOC samples. 

4.3.3 Aldehydes (Active Air Sampling) 

Active air samples were collected and analyzed according to EPA Method TO-11A for 

aldehydes, including formaldehyde, using 2,4-dinitrophenylhydrazine (DNPH) coated 

sorbent tubes with a built-in ozone scrubber (SKC Cat. No. 226-120). Each tube was 

connected to a personal sampling pump adjusted to a nominal flow rate of 500 milliliters 

per minute (ml/min) that ran for approximately 200 minutes. Pump filters were inspected 

and batteries conditioned (i.e., charged) before each sampling period in order to reduce 

the possibility of faults during sampling. Pump flows were verified by a calibrated flow 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 29 of 128
meter (Bios Drycal, Drycal) at the start and end of the sampling period. The flow rates 

measured at the start and end of sampling were averaged in order to calculate the total 

volume of air sampled. Start and end flows used to calculate the sample volumes were 

within 2.6% on average. 

 

Active aldehyde samples were collected at three indoor locations and one outdoor 

location per study house. At one indoor station per house, duplicate samples for 

aldehyde analysis were collected. A minimum of one field and one shipping blank were 

collected and analyzed for every 10 primary samples collected. All aldehyde samplers 

were refrigerated before and after sample collection. Duplicate and blank samples were 

sent to the analytical laboratory in a blinded fashion. Statistical analysis of blank and 

duplicate samples is further discussed in Section 4.7.9. 

In the EPA Method TO-11A, aldehydes in the sample air react with DNPH to form stable 

hydrazones, which are extracted from the silica gel and analyzed by high performance 

liquid chromatography coupled with an ultraviolet detector (HPLCUV). The aldehyde 

analyses were conducted by Columbia Analytical Services, Inc., Simi Valley, California. 

Table 4.4 lists twelve aldehyde compounds assessed during the study and the 

associated laboratory reporting limits for each aldehyde. 

Table 4.4 Targeted Aldehydes and Laboratory Reporting Limits

Compound CAS # Laboratory Reporting Limits (μg/m3

)* 

2,5-Dimethylbenzaldehyde 5779-94-2 8.9 – 22 

Acetaldehyde 75-07-0 8.9 – 14 

Benzaldehyde 100-52-7 8.9 – 14 

Butyraldehyde 123-72-8 8.9 – 14 

Crotonaldehyde, total 4170-30-3 8.9 – 24 

Formaldehyde 50-00-0 8.9 – 14 

n-Hexaldehyde 66-25-1 8.9 – 14 

Isovaleraldehyde 590-86-3 8.9 – 14 

Propionaldehyde 123-38-6 8.9 – 14 

m,p-Tolualdehyde 104-07-0 18 – 29 

o-Tolualdehyde 529-20-4 8.9 – 14 

Valeraldehyde 110-62-3 8.9 – 14 

CAS# Chemical Abstract Service number 

μg/m3

 micrograms per cubic meter 

* Calculated based on the reporting limit in μg/sample using the nominal air sampling volume of 0.1 m3

. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 30 of 128
4.3.4 Passive Diffusive Sampling 

Passive air samples have been demonstrated as a valid tool in residential exposure 

assessment (Pellizzari et al. 2001; WHO 2000). Passive monitors were utilized to collect 

two-week integrated samples for sulfur dioxide, nitrogen dioxide, hydrofluoric acid, 

hydrogen sulfide, aldehydes, and ozone using Radiello Diffusive Sampling Systems 

(Buzica et al. 2008; Cocheo et al. 1996; Sigma-Aldrich 2006; Swaans et al. 2007). For 

each analyte there is a specific chemiadsorbing cartridge and sampling protocol. The 

diffusive sampler is composed of two surfaces, a diffusive surface and an adsorbing 

surface. The sampling process is driven by the concentration gradient as the gaseous 

molecules cross the diffusive surface towards the adsorbing surface. The molecules are 

trapped by the selected adsorbing material in each type of passive diffusion sampler 

(Sigma-Aldrich 2006). The specific passive sampling system and the analytical 

technique used for each class of analyte is shown in Table 4.5 

Table 4.5 Summary of Target Parameters, Passive Air Sampling 

Analyte 

Radiello 

Badge Type Analytical Method* 

Aldehydes 165 Aldehydes by Radiello 165, HPLC-UV 

Hydrogen sulfide 170 Hydrogen sulfide by Radiello 170 Spectrophotometer at 

665 nm 

Ozone 172 Ozone by Radiello 172 Spectrophotometer at 430 nm 

Sulfur dioxide** 166 Sulfur dioxide by Radiello 166 Ion Chromatography 

Nitrogen dioxide** 166 Nitrogen dioxide by Radiello 166 Spectrophotometer at 

537 nm 

Hydrofluoric acid 

(as F)**

166 Hydrofluoric acid by Radiello 166 Ion Chromatography 

HPLC high performance liquid chromatography 

UV ultra violet 

nm nanometer 

* Analytical methods provided by Fondazione Salvatore Laboratory, Radiello Manual, Supelco Edition. 

** Sulfur dioxide, nitrogen dioxide, and hydrofluoric acid analysis conducted using one cartridge. 

Three indoor locations and one outdoor sampling location were selected in each home. 

At one indoor station per house, a duplicate sampling device for each analyte was used 

to assess repeatability of these methods. To begin sampling, the adsorbent cartridge 

was transferred from the sealed storage tube into the diffusive body and was screwed 

onto the supporting plate. Field personnel recorded the start time and date on the field 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 31 of 128
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 32 of 128

log sheet, and the assembled device was attached to the sampling tripod at a sampling 

height of approximately 4 feet. To achieve the desired limit of detection, the sampling 

devices were deployed for 13 to 15 days in each of the test homes. Upon completion of 

the sampling period a field investigator retrieved the sampling device, sealed the 

chemiadsorbing cartridge into the storage tube and shipped the sample to the analytical 

laboratory. All samples were temperature controlled before and after the sampling period 

and QA/QC samples were sent to the analytical laboratory in a blinded manner. 

Statistical analysis of blank and duplicate samples is further discussed in Section 4.7.9. 

The concentrations of H2S, SO2, NO2, HF, O3, and several aldehydes measured in each 

study home were calculated using Equation 4.1: 

000,000,1* * t k Q

m C = (Equation 4.1) 

Where: 

C = concentration in μg/m3

 

m = mass in μg 

Qk = analyte specific sampling rate, adjusted for temperature at the 

sampling site, in ml/min 

t = sample duration in minutes 

1,000,000 = conversion factor, ml/m3

 

 

 

Where appropriate, sampling rates for indoor samples were adjusted to account for 

different temperatures and their potential effect on the sampling rate by using the mean 

indoor temperature measured in each home. For outdoor samples, the sampling rates 

were adjusted using the mean outside temperature over the sampling period.1

 The 

reported passive sampling results were adjusted for temperature in accordance with 

Equation 4.2, which is provided by the manufacturer of the passive diffusion samplers 

(Sigma-Aldrich 2006). 

1

 Outside temperatures were obtained from the nearest National Weather Service weather station. 
exp

298 298

* ⎟

⎠

⎞ ⎜

⎝

⎛ = K

k QQ (Equation 4.2) 

Where: 

Qk = analyte specific sampling rate, adjusted for temperature at the sampling 

site, in ml/min 

Q298 = analyte specific sampling rate at 298 K (25 °C) in ml/min 

K = temperature at the sampling site, in degrees kelvin 

exp = diffusion sampler-specific factor (provided by manufacturer) 

Analyte specific sampling rates at 298 K (Qk) and the sampler-specific factor (exp) are 

listed in Table 4.6, and are all provided by the manufacturer, based on a standard 

temperature of 298 K (Sigma-Aldrich 2006). No temperature adjustments are 

recommended for SO2 or HF because the sampling rate for SO2 has been shown to be 

constant over temperatures of -10 through 40 °C and the temperature influence on 

sampling rates for HF is currently being studied (Sigma-Aldrich 2006). No sampling rate 

adjustments for relative humidity or wind speeds are recommended because rates have 

been shown to be constant over wide ranges of relative humidity and wind speed 

conditions (Sigma-Aldrich 2006). 

Table 4.6 Sampling Rates for Targeted Analytes for Passive Sampling 

Compound CAS # 

Sampling Rate in ml/min 

at 298 K (Q298) exp 

Acetaldehyde 75-07-0 84 0.35

Acrolein 107-02-8 33 0.35

Benzaldehyde 100-52-7 92 0.35

Formaldehyde 50-00-0 99 0.35

Hexanal 66-25-1 18 0.35

Isopentanal 590-86-3 61 0.35

Butanal* 123-72-8 11 0.35

Pentanal 110-62-3 27 0.35

Propanal 123-38-6 39 0.35 

Hydrogen sulfide 7783-06-4 69 3.8 

Nitrogen dioxide 10102-44-0 78 7.0 

Sulfur dioxide 7446-09-5 119 7.0 

Ozone 10028-15-6 25 1.5 

Hydrofluoric acid 7664-39-3 187 7.0 

CAS# Chemical Abstract Service number 

ml/min milliliters per minute 

K degrees kelvin 

exp sampler-specific factor provided by manufacturer 

* Butanal coelutes with isobutanal and methyl ethyl ketone. The corresponding peak was reported by 

the laboratory as butanal. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 33 of 128
All analysis of the diffusive sampling media was conducted by Air Toxics Ltd. located in 

Folsom, California. The various analytes collected by each type of passive system are 

summarized in Table 4.7, which also lists the laboratory reporting limits achieved for the 

analysis. 

Table 4.7 Passive Sampling, Targeted Analytes and Laboratory Reporting Limits 

Compound CAS # Laboratory Reporting Limits (μg/m3

)* 

Aldehydes 

Acetaldehyde 75-07-0 0.5 – 5 

Acrolein 107-02-8 0.3 – 2.5 

Benzaldehyde 100-52-7 0.3 – 2.5 

Formaldehyde 50-00-0 0.3 – 2.5 

Hexanal 66-25-1 1 – 10 

Isopentanal 590-86-3 0.3 – 2.5 

Butanal 123-72-8 0.3 – 2.5 

Pentanal 110-62-3 0.3 – 2.5 

Propanal 123-38-6 0.3 – 2.5 

Other 

Hydrogen sulfide 7783-06-4 0.5 – 0.7 

Hydrofluoric acid as fluoride 7664-39-3 5.3 

Nitrogen dioxide 10102-44-0 0.2 – 0.3 

Ozone 10028-15-6 0.6 – 1.3 

Sulfur dioxide 7446-09-5 17 

CAS# Chemical Abstract Service number 

μg/m3

 micrograms per cubic meter 

* Reporting limits provided by the laboratory in μg/m3

, based on the analyte specific sampling rate 

and a nominal sampling time for each sample batch. 

4.3.5 Inorganic and Organic Acids 

Active air samples for analysis of inorganic and organic acids were collected using silica 

gel tubes (SKC Cat. No. 226-10-03) and personal sampling pumps set to draw at 

500 ml/min over a sampling period of approximately 200 minutes. Samples for inorganic 

and organic acids were collected and analyzed in accordance with National Institute for 

Occupational Safety and Health (NIOSH) Methods 7903 and 2011, respectively. Pump 

filters were inspected and batteries conditioned (i.e., charged) before each sampling 

period in order to reduce the possibility of faults during sampling. Pump flows were 

verified using a calibrated flow meter (Bios International, Drycal) at the start and end of 

the sampling period. The flow rates measured at the start and end of sampling were 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 34 of 128
averaged to obtain an average flow rate. Start and end flows used to calculate the 

sample volumes were within 7.3%. 

For each test home, three indoor locations and one outdoor sampling location were 

selected to collect samples for analysis of inorganic and organic acids. At one indoor 

station per house, a duplicate sample was collected for inorganic and organic acids to 

assess repeatability of these methods. All samples were refrigerated before and after the 

sampling day and were sent to the analytical laboratory blinded. A minimum of one field 

blank and one shipping blank was collected and analyzed for every 10 primary samples 

collected. Statistical analysis of blank and duplicate samples is further discussed in 

Section 4.7.9.

Analysis for inorganic and organic acids was conducted using ion chromatography (IC) 

according to NIOSH Methods 7903 and 2011, respectively, by Liberty Mutual Industrial 

Hygiene Laboratory in Hopkinton, Massachusetts. Table 4.8 lists the analytes for the 

acid samples and the laboratory reporting limits achieved for the analysis during the 

study. 

Table 4.8 Targeted Organic and Inorganic Acids and Laboratory Reporting Limits

Compound CAS # Laboratory Reporting Limits (μg/m3

)* 

Organic Acids 

Acetic acid 64-19-7 23 

Butyric acid 107-92-6 23 

Formic acid 64-18-6 15 

Propionic acid 79-09-4 23 

Inorganic Acids 

Hydrochloric acid 7647-01-0 46 

Hydrobromic acid 10035-10-6 23 

Hydrofluoric acid as fluoride 7664-39-3 30 

Nitric acid 7697-37-2 15 

Phosphoric acid 7664-38-2 15 

Sulfuric acid 7664-93-9 23 

CAS# Chemical Abstract Service number 

μg/m3

 micrograms per cubic meter 

* Calculated based on the reporting limit in μg/sample using the nominal air sampling volume of 

0.1 m3

. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 35 of 128
4.3.6 Relative Humidity/Temperature 

Real-time temperature and relative humidity measurements were collected in each home 

using U10-003 HOBO® Temperature Relative Humidity Data Loggers manufactured by 

Onset Computer Corporation, Bourne, Massachusetts. The temperature sensor is a 

thermistor and relative humidity is measured by a thin-film capacitive sensor. The 

temperature sensor has a range of -20 degrees Celsius (°C) to 70 °C (-4 to 158 degrees 

Fahrenheit [°F]) with accuracy of ± 0.4 °C at 25 °C (± 0.7 °F at 77 °F). The sensor is 

factory rated to achieve a resolution of 0.1 °C at 25 °C (0.2 °F at 77 °F). The relative 

humidity sensor has a range of 25% to 95% with accuracy of ± 3.5% from 25% to 85%. 

The sensor is factory rated to achieve a resolution of 0.07%. As recommended by the 

manufacturer, the accuracy of the temperature and relative humidity sensors is verified 

annually, and the instrument is repaired or replaced, if necessary. The data loggers were 

programmed to record 5 minute average measurements with a sampling rate of 

5 seconds. A minimum of two temperature and humidity monitoring locations were 

selected in each of the homes: one typically in the central room of the house and the 

second typically in the master bedroom. If the home had two stories, one monitor was 

placed on each floor. Temperature and relative humidity measurements were collected 

for approximately 13 – 15 days in each home.

4.4 AIR EXCHANGE RATE 

The air exchange rates in each test home were assessed using the method outlined in 

ASTM Standard E741-00, Standard Test Method for Determining Air Change Rate in a 

Single Zone by Means of a Tracer Gas Dilution. Air exchange rate determinations 

utilized CO2 as a tracer given that this gas is readably available in the field and can be 

measured using portable real-time instruments. The tests were conducted by introducing 

approximately five pounds of CO2 throughout the home, allowing the gas to mix, and 

recording the decaying part of the tracer curve over time. 

CO2 concentrations were measured continuously at multiple locations inside the home 

using a Q-Trak Model 8551 Indoor Air Quality Monitor, manufactured by TSI, Inc. (St. 

Paul, Minnesota). The CO2 sensor utilized by this monitor is non-dispersive infrared 

(NDIR) and is accurate within 3% (or 50 parts per million [ppm] at 25 °C (78 °F) of the 

reading. Prior to each air exchange rate test, the sensors were calibrated at zero using 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 36 of 128
hydrocarbon free air and spanned to approximately 1,000 ppm of CO2. Air exchange 

rates were calculated from the CO2 decay results using the regression method after 

correcting for estimated outdoor air CO2 concentrations. For the purpose of this analysis, 

outdoor air CO2 concentrations were assumed to be 400 ppm. 

4.5 CORROSION ASSESSMENT 

In order to evaluate corrosion of metal building components, EH&E conducted a detailed 

inspection of each home to qualitatively determine the extent of corrosion found on 

specific surfaces as well as to deploy devices to quantitatively measure the corrosion 

rate in each home over time. 

4.5.1 Visual Inspection 

Detailed visual inspections were performed on the electrical grounding wires, air 

handling units (AHUs), plumbing components, and appliances. Notes were also made 

regarding other home contents that could show visible evidence of corrosion. 

Grounding wires were evaluated on a three point scale. A score of one indicated no 

visible corrosion, two indicated moderate visible corrosion and three indicated significant 

visible corrosion. Field team members performed cross reference evaluations during 

training to ensure consistency between teams in the field. Visual corrosion ratings were 

recorded in the master field log binder. Examples of grounding wires and the associated 

evaluation are provided in Figure 4.1. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 37 of 128
Figure 4.1 Example of Visual Corrosion Ratings, Electrical Ground Wire 

(3—Significant Visible Corrosion, 2—Moderate Visible Corrosion, 1—No Visible Corrosion) 

AHU inspection focused on the cooling coils and associated copper refrigerant lines. 

Surfaces were photographed and all locations were logged into the master field log 

binder. Appliances and fixtures including accessible refrigerator components, hot water 

heaters, faucets, plumbing lines, and other items indicating patterns of corrosion were 

logged and photographed. 

4.5.2 Corrosion Classification Coupons 

Corrosion classification coupons were used to determine the integrated corrosion rate 

present in the study homes. The corrosion coupons used in this study contained copper 

and silver metal and were supplied by Purafil, Inc., research and development laboratory 

in Doraville, Georgia. Pre-cleaned copper and silver corrosion coupons were placed at 

four indoor locations and one outdoor location for an approximately two week period 

(range of 12 to 15 days). Due to the limited availability of obtaining sufficient 

copper/silver coupon kits as the study progressed, duplicate samples were collected 

early in the study and represented approximately five percent of the total coupon 

samples collected. At the end of the sampling period, the corrosion coupons were 

collected, placed in sealed containers and returned to Purafil for analysis. The laboratory 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 38 of 128
measured the thickness of several copper and silver compounds including silver sulfide 

(Ag2S), silver chloride (AgCl), Ag unknown, copper sulfide (Cu2S), copper oxide (CuO), 

and Cu unknown present in the sample corrosion coupons. The laboratory normalized 

the data using the actual period of exposure and reported the result in units of 

“angstroms per 30 days of exposure.” The laboratory reporting limit for the analysis was 

32 angstroms per 14 days of exposure. Corrosion rates were compared with reference 

values contained in the Instrumentation, Systems, and Automation Society (ISA) 

standard ISA-71.04-1985, Environmental Conditions for Process Measurement and 

Control Systems: Airborne Contaminants. 

According to ISA, the use of corrosion coupons and measurement of corrosion 

accumulation is referred to as “reactivity monitoring” and the method provides a 

quantitative measure of the overall corrosion potential of an environment. Copper has 

been selected by ISA as a primary standard because extensive data exist that correlate 

copper film formation with reactive (corrosive) environments. Four levels of corrosion 

severity have been established for this standard. 

G1 Mild—Defined as an environment sufficiently well-controlled such that corrosion is 

not a factor in determining equipment reliability. Less than 300 angstroms corrosion 

buildup per 30 days of exposure. 

G2 Moderate—Defined as an environment in which the effects of corrosion are 

measurable and may be a factor for determining equipment reliability. Less than 1,000 

and greater than 300 angstroms corrosion buildup per 30 days of exposure. 

G3 Harsh—Defined as an environment in which there is a high probability that a 

corrosive attack will occur on metallic equipment surfaces. These harsh levels should 

prompt further evaluation resulting in environmental controls or specially designed and 

packaged equipment. Less than 2,000 and greater than 1,000 angstroms corrosion 

buildup per 30 days of exposure. 

GX Severe—Defined as an environment in which only specially designed and packaged 

equipment would be expected to survive. Specifications for equipment in this class are a 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 39 of 128
matter of negotiation between user and supplier. Greater than or equal to 2,000 

angstroms corrosion buildup per 30 days of exposure. 

4.5.3 Elemental Composition Analysis 

A subset of the corrosion coupons exposed to the atmospheres within complaint homes 

underwent further analytical/spectroscopic testing to characterize the corrosion films 

present utilizing optical and electron beam analytical methods. This additional analysis 

was completed on six copper and silver coupon sets that were selected from complaint 

homes where high visual corrosion rankings were observed from copper ground wire 

inspections as described in Section 4.5.1. Four of the coupon sets selected were those 

that had been placed at the AHU supply air register, and two of the coupon sets were 

selected from other indoor locations within the home. 

Coupon sets were sent under chain of custody to Corrosion Testing Laboratories, Inc., 

Newark, Delaware for analysis by visual, light microscopy, scanning electron microscopy 

(SEM) utilizing energy dispersive spectroscopy (EDS) and x-ray photoelectron 

spectroscopy (XPS). SEM/EDS were performed to identify the primary elemental 

composition of the corrosion layer on the coupons. Because the SEM/EDS method 

tends to provide results at greater surface depths, XPS analysis was utilized to identify 

elemental composition at the surface layer of the samples. 

4.6 PROCEDURES FOR STATISTICAL ANALYSIS OF DATA 

All statistical analyses of the study data were performed using SAS statistical software, 

version 9.1 (Cary, North Carolina). Field blank samples (discussed in Section 4.7) were 

analyzed to determine if field samples should be blank corrected. Based on statistical 

analysis of the field and shipping blank data (refer to Section 4.7.9) samples were not 

blank corrected. Values below the laboratory reporting limit, generally defined as 3x the 

method detection limit, were substituted using one-half of the reporting limit in statistical 

analyses. As described in Section 4.7.9, good agreement was observed between paired 

primary samples and duplicates; samples and duplicates were averaged for all statistical 

analyses. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 40 of 128
Statistical analysis included compiling descriptive statistics, scatter plots and box plots. 

Box plots depict the mean, median, 10th, 25th, 75th, and 90th percentiles, as well as 

individual points beyond the 10th and 90th percentiles. Bivariate statistical relationships 

were assessed using Spearman correlation and linear regression. Generalized linear 

models were used for analysis of variance and multivariate regression. Outcome 

variables were natural log-transformed to satisfy normality assumptions. The multivariate 

linear models for predictors of corrosion followed the general form: 

ln(corrosion) = β0 + β 1*analyte + β 2*modifying variable + β 3*modifying variable + ε

where ln(corrosion) is the natural log-transformed silver or copper corrosion level, 

analyte is the concentration of the target analyte in indoor air, modifying_variables are 

potential modifiers of the relationship (e.g., air exchange rate, temperature), and ε is 

model error. 

Linear mixed effects models were used to account for within-home correlation in 

analyses that included multiple measures in a home (e.g., air samples taken at the same 

time in two rooms). Fixed effects were modeled with a random effect for each home and 

fit using restricted maximum likelihood. Random effects models assumed a compound 

symmetry covariance matrix. The compound symmetry covariance structure was 

determined to be valid based on additional modeling using a repeated measures design 

and comparing covariance matrices using Akaike’s Information Criteria (AIC) and 

likelihood ratio tests. 

Covariate selection for multivariate models was determined based on bivariate 

relationships at the α=0.10 level. Statistical significance for all statistical analyses was 

defined at the α=0.05 level. 

4.7 QUALITY ASSURANCE AND QUALITY CONTROL PROCEDURES 

This section describes the overall project QA/QC measures used to design, implement, 

and report the results of the study and analysis described in this Report. Every effort was 

made in each phase of the project to ensure completeness and accuracy of data 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 41 of 128
collection, analytical methods, data entry, calculation procedures, and reporting of 

results. 

As described in this report, EH&E conducted a series of inspections and environmental 

measurements in the complaint and non-complaint homes selected for inclusion in this 

study by CPSC. All sampling and analytical procedures for the project utilized 

appropriate and valid monitoring procedures approved and recommended in relevant 

published sources, either from regulatory agencies, such as the EPA, U.S. Occupational 

Safety and Health Administration (OSHA), other cognizant governmental organizations 

such as NIOSH, consensus standard organizations such as ASTM, or the peer-reviewed 

scientific literature. The following sections describe specific measures and procedures 

implemented to assure quality of the data collected and reported. 

4.7.1 Quality Assurance Project Plan 

A quality assurance project plan (QAPP) was developed as a critical component of the 

study. The QAPP documented the standardized quality assurance protocols that were 

established for the study, including protocols for data collection, data entry, laboratory 

analysis, data management, and data analysis. This included: 

• Criteria for determining acceptable data quality, including information on target 

precision, accuracy, and data capture for all study variables 

• Sample handling and custody procedures 

• Calibration and performance evaluation procedures 

• Data reduction and reporting procedures 

The QAPP is included as Appendix B to this document. 

4.7.2 Project Organization(s) and Responsibilities 

EH&E’s project manager was responsible for overall implementation, documentation, 

and delivery of the project and had the responsibility of ensuring the accuracy, precision, 

and completeness of all data presented. The Project Executive was responsible for 

technical oversight of the overall project and for ensuring that high data quality 

objectives were met by the Project Manager and the project team. Prior to release, all 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 42 of 128
deliverables at EH&E are reviewed and approved by qualified Senior Level staff, with 

relevant qualifications and expertise, whose responsibilities include ensuring the 

accuracy and appropriateness of technical information presented. All members of the 

project team were trained in, and responsible for, data validation and quality control 

checks during each of their tasks. 

4.7.3 Quality Assurance and Quality Control Samples 

As detailed above, in addition to the primary samples collected during the study, a 

number of quality control samples were collected and analyzed in each sample set to 

evaluate the quality and reasonableness of the data collected during the study. The 

types and frequency of QA/QC samples collected during the study are outlined in Table 

4.9. 

Table 4.9 Quality Assurance and Quality Control Samples Collected During the Project 

Sample Type Frequency Definition 

Duplicate sample Minimum of one per 

sample set and one 

per every 10 primary 

samples 

A sample collected concurrently with a primary 

field sample to assess repeatability of methods. 

Field blank Minimum of one per 

sample set and one 

per every 10 primary 

samples 

A sample prepared by the field team that 

represents the procedure for preparing for 

integrated sampling, and is handled as such, but 

is not actually used for sampling. This is sent in a 

blinded fashion to the laboratory. The results of 

the field blanks can be used to determine 

whether there was any contamination in the 

preparation, handling or shipping process in the 

field, or during the analysis of the samples by the 

laboratory. 

Shipping Blank Minimum of one per 

sample set and one 

per every 10 primary 

samples 

An unused sample that is not handled in the field 

other than to have it incorporated into a regular 

sample shipment and sent in a blind fashion to 

the laboratory. The results of shipping blanks 

can be used to determine whether there was any 

contamination during the shipping process . 

In addition to the use of different QA/QC samples in the field, QA/QC of integrated air 

samples included verification of pump flows by use of calibrated flowmeters at the start 

and end of each sampling period. The start and stop flow rates were then averaged to 

obtain an average flow rate. Sample duration was also calculated from the start and stop 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 43 of 128
times recorded on the field data sheets. Total sample volumes were then calculated 

using the average flow rate and the duration of sampling as follows: 

Total Sample Volume (L) = Average Flow Rate (L/min) x Total Sample Time (minutes) 

4.7.4 Sample Handling 

EH&E followed the requirements for holding times and sample perseveration outlined in 

the respective reference sampling methods used. After each day of sampling, samples 

were shipped to the laboratory via overnight express delivery within the holding time 

specified by the analytical method. The reduced sulfur air samples were shipped 

immediately after sampling via first priority overnight express delivery. 

4.7.5 Sample Custody 

All project samples were handled in accordance with appropriate chain of custody 

procedures. Compliance was overseen by the field team leader. The field team leader 

was also responsible for ensuring that all unused sample media as well as collected 

samples were properly cared for before, during, and after sampling. At the time of use, 

each sample was assigned a unique sample identification label. Each sample label was 

recorded on the field sample log sheets prior to sample collection. All log sheets were 

stored in a master field binder during the study. 

4.7.6 Calibration Procedures 

All measuring, monitoring, and sampling instrument calibrations, except those requiring 

factory calibrations, were performed in EH&E’s Field Operations Support Center (FOSC) 

prior to shipment of instruments to the field. All instruments that are factory calibrated 

are checked periodically in the FOSC by comparing them against other, recently 

calibrated instruments. Prior to use in the field, each instrument was zeroed and spanchecked with appropriate gases, or flow checked with rotameters to insure that they 

were operating within specification (and adjusted as necessary). Table 4.10 summarizes 

the calibration procedures for instruments used in the study. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 44 of 128
Table 4.10 Calibration Procedures

Parameter 

Instrument 

Type Instrument Calibration Method Frequency 

Air 

temperature 

Thermistor, 

data logger 

HOBO® U10-003 

(Onset Computer 

Corp) 

Calibrations performed by 

the manufacturer 

Annual 

Relative 

humidity 

Thin-film 

capacitive sensor, 

data logger 

HOBO®

 U10-003 

(Onset Computer 

Corp) 

Calibrations performed by 

the manufacturer 

Annual 

Carbon 

dioxide 

Non-dispersive 

infrared sensor 

Q-Trak Model 8551 

Indoor Air Quality 

Monitor 

Multipoint with standard 

gas mixtures ranging from 

0 to 2,000 ppm along 

linear response curve. 

Pre and post 

field 

measurements 

Active air 

sampling 

Air-sampling 

pump 

Gilair-3/5 

(Sensodine, Inc.) 

SKC Inc. 

Compared against 

calibrated flow meter. 

Pre and post 

measurements 

Active air 

sampling 

Flow meter Dry-Cal DC-Lite, 

Bios International 

Corp. 

Annual factory calibration Pre and post 

measurements 

Volatile 

organic 

compounds 

SUMMA 

canister flow 

controller 

6 Liter SUMMA 

canister 

Provided pre-calibrated by 

laboratory 

Each canister 

4.7.7 Recordkeeping 

4.7.7.1 Written Documentation 

All data and documentation generated during the study, except that generated in 

electronic formats (raw data files, digital photographs), was transcribed into the 

appropriate collection forms which are subsequently stored in a single data collection 

binder. Hardcopies of final analytical laboratory reports (and the completed chains of 

custody) were also received and retained in EH&E’s central filing system. Any changes 

in data entries are done in a manner that does not obscure the original entry. The reason 

for the revision is indicated, dated, and signed at the time of change. All original 

hardcopy records for the project are retained (together) in a central file system at 

EH&E’s main office. 

4.7.7.2 Electronic Documentation 

Electronic documentation generated in the field during the study included digital 

photographs, XRF data files, carbon dioxide measurements and temperature and 

relative humidity data files. All files generated during the field phases of the study were 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 45 of 128
downloaded and stored temporarily on a field computer under the control of the field 

team leader. Electronic files were then transferred from the field computer onto EH&E’s 

central server routinely (typically at the end of each day). In order to track the various 

electronic data files, a standardized filing and naming system was used to clearly 

differentiate between files by type and the home in which they were collected. Also, field 

personnel documented the location of digital photographs, XRF measurements, and 

real-time data monitor deployments on the appropriate field forms. 

4.7.8 Data Reduction, Validation, and Reporting 

A systematic, standardized approach was implemented by EH&E to analyze, validate, 

and report the data collected during the study, including incorporating the following 

steps: 

• Senior level staff at EH&E reviewed and verified the overall study approach, data 

collection strategy, methodology, appropriateness of all calculations and statistical 

analysis, and deliverables. 

• EH&E developed a database (Microsoft Access), where all field data and laboratory 

results were stored. 

• All (100%) field log entries and calculations were reviewed by independent staff 

members prior to entry into the study database. 

• All (100%) of the data entry into the study database was reviewed and verified by 

independent, qualified personnel. 

• To minimize database entry errors, EH&E requested that, when possible, all 

laboratory reports be provided in electronic data delivery (EDD) formats, such as 

Microsoft Excel so that the data could be directly imported into the central study 

database. 

• After the database was populated, the number and sample identification labels in the 

database were compared with those on the field log sheets and the analytical 

laboratory reports (using a program coded in SAS 9.1). 

• As discussed above, data summary and analysis was completed using SAS 9.1. All 

programming codes developed and executed for processing the data were 

independently reviewed by qualified personnel. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 46 of 128
• In the limited instances where data entry or recording errors were identified during 

the QA/QC review processes described above, the entry was corrected in all relevant 

locations (back to the original entry). Corrections were noted on all original 

documentation. 

• All of the final results underwent QA/QC review, including completeness and 

reasonableness checks. 

4.7.9 Evaluation of Data Quality 

As described above, a number of measures were implemented to ensure the collection 

of reproducible and accurate data during the study. This section describes the measures 

used to evaluate the completeness, precision, and accuracy of the data collected during 

the study. The completeness of the data set was evaluated by analyzing the capture 

efficiency for each environmental parameter targeted in the study. Accuracy was 

evaluated by reviewing results of blank samples. Precision was evaluated by examining 

the strength of the association between paired primary and duplicate samples. Paired 

duplicates were averaged and no blank correction was done for purposes of analysis. 

4.7.9.1 Completeness 

The completeness of air sampling data from the study was evaluated by examining the 

overall data capture efficiency for each sample group and sample type collected in the 

field (primary samples, duplicate samples, and field blanks and shipping blanks). Table 

4.11 summarizes the data capture efficiency during the study. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 47 of 128
Table 4.11 Summary of Data Capture Efficiency for Air Samples 

Number of 

Valid Samples* 

Number of 

Void Samples 

Capture 

Efficiency 

(%) 

Sample Type S D FB SB S D FB SB S/D All 

Acids (inorganic) 193 49 30 21 39 12 0 1 82.6 84.9 

Acids (organic) 194 49 30 22 15 4 1 0 92.7 93.7 

Active aldehydes 194 48 32 22 6 1 0 0 97.2 97.7 

Reduced sulfur 203 51 NA NA 0 0 0 0 100 100 

H2S passive 201 51 38 17 7 1 0 1 96.9 97.2 

HF passive 198 51 37 16 10 1 0 1 95.8 96.2 

NO2 passive 198 51 37 16 10 1 0 1 95.8 96.2 

O3 passive 198 50 38 17 10 2 0 1 95.4 95.9 

SO2 passive 198 51 37 16 10 0 0 1 96.1 96.5 

Passive aldehydes 201 51 37 17 7 1 1 1 96.9 96.8 

VOCs** 111 30 12 5 0 0 0 0 100 100 

Overall data capture efficiency 95.0 95.5 

S primary samples H2S hydrogen sulfide 

D duplicates HF hydrogen fluoride 

FB field blanks NO2 nitrogen dioxide 

SB shipping blanks O3 ozone 

NA not applicable SO2 sulfur dioxide 

S/D samples/duplicates VOC volatile organic compound 

* Data points considered in the analysis. 

** Acetonitrile readings were excluded in all test homes (64% of samples) where potential 

contamination was a concern. 

Overall, data capture efficiency was greater than 95%, and greater than approximately 

85% for all individual sample types. A limited number of samples collected using sorbent 

media (active aldehydes, passives, and acids) were voided, primarily due to field 

conditions, such as pump failure, sample breakage in the field or during shipping, or 

when samples were adversely impacted by moisture. Data capture efficiency was 100% 

for whole air samples (VOCs and reduced sulfur). As discussed below, acetonitrile 

measurements from several homes were excluded. Although not listed in Table 4.11, no 

data from real-time monitoring results collected in the field (temperature, humidity, CO2) 

were excluded from the analysis. 

During the initial phases of data review, EH&E noted several elevated acetonitrile 

concentrations in both indoor and outdoor samples collected at some homes. Based on 

consultation with the laboratory, it was determined that these elevated measurements 

may be due to contamination, since acetonitrile may be liberated from DNPH during 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 48 of 128
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 49 of 128

active aldehyde air sampling. DNPH is the sorbent media used for collection of the 

active aldehyde samples and these samples were typically deployed in close proximity 

to the SUMMA Canisters. Based on these findings, for the remainder of the study, an 

adsorbent charcoal tube was placed into the sampling train (downstream of the DNPH 

tube) for the active aldehyde samples. EH&E excluded all acetonitrile measurements 

from VOC sample sets that were collected in test homes where charcoal tubes were not 

in place on the aldehyde samples. All other VOC analytes were included in the data 

analysis. 

4.7.9.2 Accuracy 

Field and shipping blanks analysis were used to assess the accuracy of air sample 

measurements. For purposes of comparison of the air sample data analyzed in this 

report, the nominal laboratory reporting limit, expressed as quantity per sample and as 

quantity per unit volume of air sampled, was used as the metric of comparison to 

determine when results were below detection. The reporting limits presented are as 

reported by the respective analytical laboratory. EH&E did not review the methods used 

by the laboratories to derive these values. For passive, active aldehyde, and acid 

samples reporting limits per cubic meter of air sampled assumes that the nominal 

sample volume specified in the study protocol was collected. 

Table 4.12 summarizes the number and percent of field and shipping blank results that 

were above detection (the reporting limit), and the limited number of individual 

compounds detected. 
Table 4.12 Summary of Detection Frequency for Air Sample Field and Shipping Blanks 

Field Blanks Shipping Blanks All Blanks 

Sample Group Compound 

N 

Total 

N 

Detect 

% Nondetect N Total N Detect % Non- detect % Non- detect 

Active aldehydes All compounds (12) 384 0 100 264 0 100.0 100.0 

Nitric acid 30 1 96.8 21 0 100.0 98.1 Sulfuric acid 30 19 61.2 21 13 61.8 61.4 

Inorganic acids 

Other compounds (5) 150 0 100 105 0 100.0 100.0 

Organic acids All compounds (4) 120 0 100 88 0 100.0 100.0 Passive aldehyde Acetaldehyde 37 1 97.4 17 0 100.0 98.2 

Other compounds (8) 296 0 100 136 0 100.0 100.0 

Hydrogen sulfide (H2S) 38 0 100 17 0 100.0 100.0 Hydrogen fluoride (HF) 37 0 100 16 0 100.0 100.0 Nitrogen dioxide (NO2) 37 5 88.1 16 4 80.0 85.5 Ozone (O3) 38 1 97.4 17 0 100.0 98.2 

Passive other 

Sulfur dioxide (SO2) 37 0 100 16 0 100.0 100.0 

2-Butanone (MEK) 12 3 80.0 5 1 83.3 81.0 2-Hexanone 12 0 100 5 1 83.3 94.4 Acetone 12 2 85.7 5 1 83.3 85.0 Acrolein 12 1 92.3 5 1 83.3 89.5 cis-1,2-Dichloroethene 12 0 100 5 1 83.3 94.4 Propene 12 0 100 5 1 83.3 94.4 

Volatile organic compound (VOC) 

Other compounds (69) 818 0 100 344 0 100.0 100.0 

Overall blank detection frequencies 98.5 – – 98.0 98.3 

N number of data points Max maximum μg/m3 micrograms per cubic meter 

RL reporting limit 

Draft Final Report CPSC Drywall and Indoor Environmental Quality Assessment Environmental Health & Engineering, Inc.16512 
Overall, 98.3% of the blank measurements were below detection and less than 10% 

(11 of 112) of the individual analytes targeted during the study were detected in one or 

more blank sample. Also, with the exception of sulfuric acid, all compounds were 

detected in blanks infrequently (all less than 20% and most less than 10% detection 

frequency). Also, for all detected analytes, the maximum (nominal) concentration 

detected in blank samples was below the maximum reporting limit for the overall sample 

set, with the exception of ozone and sulfuric acid. Ozone was only detected in 1 of 55 

blanks. Sulfuric acid was below detection in all of the test homes, both case and control. 

No blank correction was done in EH&E’s analysis of the study data, except blank 

corrections performed by the laboratory as part of their standard reporting procedures. 

EH&E also reviewed the quality assurance procedures implemented by the analytical 

laboratories to evaluate the accuracy of the air sample measurements (this analysis is 

summarized in Table A.1 in Appendix A). In accordance with the standard or published 

methodologies employed for the air sampling and analysis, laboratory quality control 

measures included blanks, duplicates, standards, and continuing calibration verification. 

These quality control metrics demonstrated excellent compliance with the accuracy 

requirements specified in the respective reference methods. Analytical quality assurance 

exceptions were noted in less then 0.2% of the air sample measurements (48 out of 

28,661 measurements). The exceptions included laboratory duplicate and control 

standard recoveries slightly outside of the limits outlined in the reference methods and 

occasional exceedances of sample storage times or temperatures. EH&E also evaluated 

the laboratory results to determine if there was potential breakthrough and sample media 

saturation; no breakthrough or saturation occurred during the study. 

No laboratory quality assurance flags were noted for laboratory blank samples, although 

analytes were detected in some laboratory blanks that were analyzed in conjunction with 

the active aldehyde samples. In all cases, results reported by the laboratories were 

blank corrected in accordance with the appropriate standard laboratory protocols. 

The accuracy of the XRF instruments was ensured using several measures. First, each 

XRF analyzer was individually calibrated by the manufacturer prior to delivery to EH&E 

using standard reference materials that include many elements, including strontium. The 

manufacturer’s calibration procedure specifically includes an assessment of the 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 51 of 128 
concentration of strontium in the standard reference material and values reported by the 

analyzer. Second, agreement between the three XRF instruments used during the field 

study and in subsequent analysis at EH&E’s laboratory was evaluated. All analyzers 

were found to be in excellent agreement for strontium concentrations (Spearman r=0.98, 

p<0.0001). Third, EH&E evaluated the strontium concentrations measured 

independently by EH&E and the EPA from the same bulk samples of drywall. These 

independent readings also demonstrated a high level of 1:1 agreement (Spearman 

r=0.99, p<0.0001). Last, seven drywall samples were analyzed by the U.S. Geologic 

Survey for total strontium using inductively coupled mass spectrometry (ICP/MS). The 

same samples were analyzed using the XRF instruments and the strontium 

concentrations reported by both methods were found to be in excellent agreement 

(slope=1.06; R2

=0.997; p<0.001). In addition, internal instrument background checks 

were run on each instrument before use. For FTIR, internal calibration programs were 

run on the instrument monthly in accordance with manufacturer’s recommendations. 

The accuracy of real-time temperature, relative humidity, and dew point monitors was 

ensured in accordance with manufacturer’s recommendations (annual calibration against 

a primary standard). Accuracy of the CO2 monitors was maintained using a primary 

calibration procedure, with NIST-traceable zero and span gases, prior to field 

deployment, where the instrument response was set or calibrated to a primary standard 

device, zero or span gas, or mercury thermometers and hygrometers. Each day during 

the field study, the performance of each sensor was measured or verified against these 

primary standards. This method allows both the repeatability (precision) and the 

instrument accuracy to be recorded. 

4.7.9.3 Precision 

Measurement precision for targeted analytes was characterized by analysis of the 

duplicate samples collected during the field study. Numerous methods have been 

developed to characterize the precision of environmental measurement systems from 

duplicate measurements. Estimates of precision attained from the various methods are 

reported to be a function of the magnitude that the differences between duplicate 

samples deviate from normality (Hyslop and White 2009). Therefore, both a primary and 

secondary method was used to estimate the precision of the measurements in this study 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 52 of 128 
in order to ensure that a robust determination of precision was obtained. The precision 

estimates discussed below included all duplicate pairs where both measurements were 

above the laboratory reporting limit. 

The primary method for estimating precision was based upon guidance from the EPA 

(EPA 2008). In this method, precision is calculated as the root mean square of the 

scaled relative differences between pairs of duplicate samples (Equation 4.3). The 1σ

estimate of precision derived from this method provides a concentration range within 

which the actual concentration is expected to occur 68% of the time. 

%100 1

1

2 = ∑ × =

n

i

Di

n

meanRoot square , (Equation 4.3) 

where 

( )

( )

2

2

21

21

ii

ii

i CC

CC

D

+

−

=

The secondary method used to estimate precision of the study data was the coefficient 

of variation (CV) computed from an ordinary least squares regression of the paired 

duplicate samples. In this case, the CV is calculated as the root mean square error of 

the regression model divided by the mean of the dependent variable (the second sample 

of each duplicate pair). 

Precision estimates for each parameter targeted during the study are listed in Table A.2 

of Appendix A. Estimates of precision for the following major sample groups and for 

selected specific chemicals in indoor air are tabulated below. 

• Air: inorganic acids, organic acids, aldehydes sampled both actively and passively, 

reduced sulfur gases, and volatile organic compounds. 

• Specific chemicals: acetic acid, carbon disulfide, formaldehyde, formic acid, 

hydrogen sulfide, nitrogen dioxide, and ozone. 

• Drywall: strontium by XRF and carbonate by FTIR. 

• Corrosion: rates of copper and silver sulfide corrosion. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 53 of 128 
The primary estimates of precision for the major groups of chemicals measured in air are 

provided in Table 4.13. Precision ranged from 4.4% for inorganic acids to 21% for VOCs. 

Table 4.13 Primary Estimate of Measurement Precision for Groups of Analytes in Indoor Air 

by Sampling Method 

Group of Analytes Number of Pairs Precision (%) 

Acids, inorganic 5 4.4 

Acids, organic 70 6.9 

Aldehydes, active samples 364 10.5 

Aldehydes, passive samples 375 6.9 

Reduced sulfur gases 3 8.8 

Volatile organic compounds 1,005 21.0 

The high precision shown in Table 4.13 is illustrated in the scatter plots presented in 

Figure 4.2. The secondary estimates of precision inset in the figure agree well with the 

corresponding primary estimates with one exception. The agreement for duplicate pairs 

of VOC samples (Figure 4.2 f) is somewhat lower than the agreement for other groups 

according to the secondary method for estimating precision. However, examination of 

sample and duplicate measurements for individual compounds indicates that this high 

variability is accounted for by a limited number of individual compounds. These 

compounds include several that were typically detected at low levels in some homes 

(1,1,2-trichlorotrifluoroethane, trichlorofluoromethane, and naphthalene) and two 

common indoor VOCs (acetone and ethanol) that are not relevant to the findings or 

conclusions of this study. Excluding these compounds from the regression analysis 

results in improved agreement between the sample and duplicate pairs for the VOC 

sample group (coefficient of variation=27.4, RMSE=7.0).

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 54 of 128 
Samples - Inorganic Acid (μg/m3

)

0 10 20 30 40 50 60 70

Duplicates - Inorganic Acid (μg/m3

)

0

10

20

30

40

50

60

70

Samples - Organic Acid (μg/m3)

0 200 400 600 800 1000

Duplicates - Organic Acid (μg/m3

)

0

200

400

600

800

1000

Samples - Active Aldehyde (μg/m3)

0 100 200 300 400 500

Duplicates - Active Aldehyde (μg/m3

)

0

100

200

300

400

500

Samples - Passive Aldehyde (μg/m3)

0 100 200 300 400

Duplicates - Passive Aldehyde (μg/m3

)

0

100

200

300

400

Samples - Reduced Sulfur Gases (μg/m3

)

0 2 4 6 8 10 12 14

Duplicates - Reduced Sulfur Gases (μg/m3

)

0

2

4

6

8

10

12

14

Samples - VOC (μg/m3)

0

1000

2000

3000

4000

5000

6000

Duplicates - VOC (μg/m3

)

0

1000

2000

3000

4000

5000

6000

(A) (B)

(C) (D)

(E) (F)

RMSE = 2.5 μg/m3

CV = 5.9%

RMSE = 11.8 μg/m3

CV = 7.2%

RMSE = 3.8 μg/m3

CV = 15.5%

RMSE = 3.1 μg/m3

CV = 8.9%

RMSE = 1.9 μg/m3

CV = 18.4%

RMSE = 106.7 μg/m3

CV = 233%

Figure 4.2 Comparison of Paired Duplicate Air Sample Measurements by Group

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 55 of 128 
Table 4.14 contains the primary estimates of precision determined for a selection of 

specific analytes that includes many of the reactive species that were sampled in 

complaint and non-complaint homes. Precision was less than 15% for all of the species 

except nitrogen dioxide. As detailed in Section 5, NO2 was found to be present at normal 

indoor concentrations for the complaint and non-complaint homes in this study. 

Table 4.14 Primary Estimate of Measurement Precision for Specific Analytes in Indoor Air 

Analyte Number of Pairs Precision (%) 

Acetic acid 47 5.9 

Carbon disulfide (reduced sulfur) 3 8.8 

Carbon disulfide (SUMMA canister) 14 6.1 

Formaldehyde (active) 48 10.0 

Formaldehyde (passive) 51 3.9 

Formic acid 23 8.5 

Hydrogen sulfide (passive) 28 12.5 

Nitrogen dioxide 48 18.5 

Ozone 1 6.7 

Scatter plots and secondary estimates of precision are shown in Figure 4.3 for acetic 

acid, formic acid, carbon disulfide (SUMMA), formaldehyde (active and passive), and 

hydrogen sulfide (passive). There was good agreement between the primary and 

secondary estimates of precision for these analytes. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 56 of 128 
Samples - Acetic Acid (μg/m3

)

0 200 400 600 800 1000

Duplicates - Acetic Acid (

μg/m3

)

0

200

400

600

800

1000

Samples - Carbon Disulfide (μg/m3)

0 2 4 6 8 10

Duplicates - Carbon Disulfide (

μg/m3

)

0

2

4

6

8

10

Samples - Active Formaldehyde (μg/m3)

Duplicates - Active Formaldehyde (

0 100 200 300 400 500

μg/m3

)

0

100

200

300

400

500

Samples - Passive Formaldehyde (μg/m3)

0 30 60 90

Duplicates - Passive Formaldehyde (

μg/m3

)

0

30

60

90

Samples - Formic Acid (μg/m3)

0 20 40 60 80 100

Duplicates - Formic Acid (

μg/m3

)

0

20

40

60

80

100

Samples - Hydrogen Sulfide (μg/m3)

012345

Duplicates - Hydrogen Sulfide (

μg/m3

) 0

1

2

3

4

5

(A)

RMSE = 14.2 μg/m3

CV = 6.4%

(B)

RMSE = 1.1 μg/m3

CV = 63.6%

(C)

RMSE = 6.8 μg/m3

CV = 8.8%

(D)

RMSE = 3.1 μg/m3

CV = 6.0%

(E)

RMSE = 5.4 μg/m3

CV = 30.8%

(F)

RMSE = 0.2 μg/m3

CV = 13.2%

Figure 4.3 Comparison of Paired Duplicate Air Sample Measurements for Selected Compounds

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 57 of 128 
The primary estimates of precision for the strontium (by XRF) and carbonate (by FTIR) 

measurements are shown in Table 4.15. Precision ranged from 3.4% for the carbonate 

measurements to 13.8% for the strontium field measurements. 

Table 4.15 Primary Estimate of Measurement Precision for XRF and FTIR Measurements 

Parameter Number of Pairs Precision (%) 

Strontium (XRF Field measurements) 98 13.8 

Strontium (XRF laboratory measurements) 810 12.3 

Carbonate (FTIR laboratory measurements) 111 3.4 

XRF x-ray fluorescence 

FTIR Fourier transform infrared spectroscopy 

Figures 4.4 and 4.5 summarize the regression analysis for strontium field 

measurements, strontium laboratory measurements, and carbonate laboratory 

measurements, all of which demonstrate a high level of precision. 

Samples - XRF Field Strontium (ppm)

Duplicates - XRF Field Strontium (ppm)

0 1000 2000 3000 4000

0

1000

2000

3000

4000

Samples - XRF Laboratory Strontium (ppm)

0 10 20 30 40 50 60

Duplicates - XRF Laboratory Strontium (ppm)

0

10

20

30

40

50

60

RMSE = 115.0 ppm

CV = 16.0%

RMSE = 116.8 ppm

CV = 7.3%

Figure 4.4 Comparison of Paired Duplicate XRF Field and Laboratory Strontium Measurements 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 58 of 128 
Samples - FTIR Laboratory 

Carbonate (absorbance)

0

1000

2000

3000

4000

5000

6000

Duplicates - FTIR Laboratory 

Carbonate (absorbance)

0

1000

2000

3000

4000

5000

6000

RMSE = 1.7 absorbance

CV = 14.8%

Figure 4.5 Comparison of Paired Duplicate FTIR Laboratory Carbonate Measurements 

The precision of the FTIR instrument used in testing at EH&E’s laboratory was also 

examined by evaluating the agreement between measurements repeated daily from the 

same sample of drywall. The CV from the repeat reference readings for carbonate 

indicated strong agreement as well (N=12, CV=3.3%). 

The primary estimate of precision for the coupon corrosion measurements was an 

evaluation of the agreement between paired duplicate measurements of Cu2S and Ag2S. 

The precision estimates for the corrosion measurements are shown in Table 4.16. 

Samples - Cu2S Corrosion Rate (A/30 d)

0 50 100 150 200 250 300

Duplicates - Cu2S Corrosion Rate (A/30 d)

0

50

100

150

200

250

300

Samples - Ag2S Corrosion Rate (A/30 d)

0 500 1000 1500 2000 2500

Duplicates - Ag2S Corrosion Rate (A/30 d)

0

500

1000

1500

2000

2500

RMSE = 409.4 A/30 d

CV = 2.0%

RMSE = 130.5 A/30 d

CV = 29.1%

Figure 4.6 Comparison of Paired Duplicate Corrosion Rate Measurements for Copper and Silver 

Coupons 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 59 of 128 
In addition to the calibration procedures implemented prior to, and in the field (described 

above), the precision and reasonableness of real-time monitoring data (temperature, 

relative humidity, dew point temperature, and CO2) was evaluated utilizing several 

measures. For the temperature, relative humidity, and dew point temperature 

measurements the CV between the average values at each measurement location within 

a test home was used as an indicator of agreement (CV=[standard 

deviation/mean]∗100). Table 4.16 summarizes the mean CVs for the temperature and 

humidity monitoring data, all of which were less than 10%. 

Table 4.16 Coefficient of Variation, Inter-home Temperatures, Relative Humidity and Dew 

Point Temperature Measurements 

Parameter N Mean CV (%) 

Temperature 120 1.4 

Relative humidity 120 4.4 

Dew point temperature 120 2.1 

N number 

CV coefficient of variation 

The precision of air exchange rate measurements was evaluated using linear regression 

analysis between each of the coincident air exchange rate estimates within each home 

(between one and three locations were monitored in each home), which were based on 

CO2 readings. The CVs for the air exchange rate estimates averaged 29% (range 

0 – 104%). Although some houses exhibited relatively high variability in air exchange 

rate estimates, the error for these measurements average 7% and ranged from 2 – 30% 

(based on an overall RMSE of 0.016). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 60 of 128 
5.0 RESULTS 

5.1 SOURCE IDENTIFICATION 

5.1.1 Known Origin Sample Analysis 

A preliminary laboratory study, at the EH&E facility, analyzed 34 drywall samples of 

known origin (also referred to as “catalog” samples) using both XRF and FTIR 

techniques. This analysis focused on the core of the drywall samples and excluded paint 

and paper associated with the drywall. 

The results of the analysis of 34 samples are presented in Figure 5.1. Drywall samples 

imported from China are depicted in red triangles and all demonstrate elevated levels of 

strontium as measured by XRF and carbonate as measured by FTIR. Of note, one 

imported drywall sample with elevated carbonate but muted strontium concentration was 

determined to be a mix of synthetic and mined gypsum. All of the domestic drywall 

samples had low carbonate levels and the majority also had low strontium 

concentrations. 

Strontium (ppm) - XRF

0 1000 2000 3000 4000 5000

Calcium Carbonate (absorbance) - FTIR

0

2

4

6

8

10

12

14

16

Imported

Domestic - Mined

Domestic - Synthetic

Domestic - Unknown

Blend

(Synthetic + Mined)

Figure 5.1 Comparison of Cored Drywall Samples of Known Origin and Analyzed in a Laboratory 

Setting for Strontium Concentrations (ppm) Measured by XRF and Carbonate 

(Absorbance) Measured Using FTIR. See Figure for Legend of Sample Type 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 61 of 128 
This separation observed in the catalog data permitted the tentative discrimination of 

various categories of drywall based on the following criteria: 

• Samples with greater than 1,200 ppm of strontium AND carbonate absorbance 

values greater than 5 (imported from China) 

• Samples with less than 1,200 ppm of strontium and carbonate less than 5 (not 

imported from China) 

Of note, one sample imported from China that was a blend of synthetic and mined 

material had high carbonate but a strontium concentration close to but below the 

1,200 ppm cutoff. 

5.1.2 FTIR and XRF Laboratory-Based Analysis of Core Samples Collected in the 

51-home Field Study 

The drywall core samples obtained from multiple locations within each home (at least 

one per wall) in the 51-home study were analyzed using XRF and FTIR under the same 

sampling protocol as the preliminary “catalog” samples described above. Results for the 

core samples taken from the 51 homes in the field study and analyzed in the laboratory 

are presented in Figure 5.2. In general, the two main groups described above, and a 

third group, are apparent in the data collected from the field: 

• Group 1—Samples with greater than 1,200 ppm of strontium AND carbonate values 

greater than 5 

• Group 2—Samples with less than 1,200 ppm of strontium and carbonate less than 5 

• Group 3—Samples with less than 1,200 ppm of strontium and carbonate greater than 5. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 62 of 128 
FTIR/XRF Marker 

Strontium (ppm) - XRF

0 1000 2000 3000 4000 5000

Carbonate (absorbance) - FTIR

0

10

20

30

40

50

60

Sample size by quadrant

1

2

3

181 633

313 28

Figure 5.2 Comparison of Cored Drywall Samples Obtained in the Field and Analyzed in a 

Laboratory Setting for Strontium Concentrations (ppm) Measured by XRF and 

Carbonate (Absorbance) Measured Using FTIR. White Circles Denote Points with 

Elevated Carbonate and Quartz and Identified as Containing Plaster (See Text for 

Explanation) 

Groups 1 and 2 are shown in Figure 5.2 and correspond to the cutoff points found in the 

”catalog” samples presented in Figure 5.1 and appear to be useful indicators of imported 

and domestic drywall, respectively. An important difference between the analysis of the 

“catalog” samples and those collected from the 51 homes is that several samples had 

elevated carbonate levels (Group 3). For analyses in this report, drywall samples falling 

in Group 1 were defined as “FTIR/XRF Marker Present” and all others defined as 

“FTIR/XRF Marker Not Present.” 

The field samples with elevated carbonate and lower strontium (Group 3) may be due to 

imported samples comprised of blended material (see Figure 5.1) or domestic samples 

impacted by wall coverings such as plaster. The samples with elevated carbonate were 

examined further and determined to also have elevated quartz (samples denoted by 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 63 of 128 
white circles have elevated quartz). Additional analysis was conducted on the drywall 

samples with the elevated quartz. It was determined that the elevated carbonate 

readings were due to finish plaster on the drywall being mixed with the drywall sample 

during the coring procedure used for sample collection (Figure 5.3). Plaster is often used 

on drywall to provide a smooth painting surface and commonly contains up to 50% 

carbonate and 1-2% of quartz. 

1 2 3 4 5 6 7 8 9 10

Carbonate (FTIR)

0

10

20

30

40

50

60

70

Plaster

Drywall Core

Figure 5.3 Carbonate Levels Measured Using FTIR in Matched Samples of Plaster and 

Drywall and Core Material Alone in Drywall 

The information provided in Figure 5.3 indicates that the presence of plaster in a sample 

can significantly influence the results and provide a significant positive bias for the 

carbonate reading. This bias could result in overstating drywall carbonate results by a 

factor of approximately 5 to 50. In reviewing the data there are very few individual data 

points in which applying the correction would modify the original quadrant in which the 

sample would fall. The possible bias is nearly eliminated when all the samples from a 

home are aggregated and analyzed. The original data was used for plotting Figure 5.2 

and no correction has been applied in this analysis. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 64 of 128 
5.1.3 Comparison of CPSC House Status and Status as Determined Using 

FTIR/XRF 

Using the results of the FTIR and XRF analysis of the core samples, any sample falling 

in Group 1 was labeled as having the FTIR/XRF marker present. All other samples were 

labeled as ‘Not Present.’ To compare the objective determinant of house status (i.e., 

contains imported drywall or not) against the CPSC home status (i.e., complaint or noncomplaint home), homes that contained greater than one sample in Group 1 were 

labeled as having the FTIR/XRF marker present. 

A comparison of the FTIR/XRF marker against the CPSC home status is presented in 

Table 5.1. The two methods showed strong agreement across the 51 homes. Small 

differences between the two metrics were expected; three of the 41 homes self-identified 

to CPSC as being complaint homes were not found to have imported drywall based on 

the FTIR/XRF marker. The self reported CPSC ranks for these three homes are 3, 4, 

and 4 (Scale 0 – 7). 

Table 5.1 2x2 Table Comparing CPSC Home Status and Objectively Measured Status Using 

FTIR/XRF

CPSC Status 

Complaint Non-complaint Total

Present 38 0 38 FTIR – XRF Marker 

Not Present 3 10 13 

Total 41 10 51 

5.2 INTEGRATED MEASURE OF EFFECT 

5.2.1 Corrosion Classification Coupons 

Corrosion classification coupons containing one strip of copper and one strip of silver 

represent an objective integrated measure of effect. Corrosion coupons obtained from 

one non-complaint home (A) and three complaint homes (B-D) are depicted in Figure 5.4 

and represent typical results for the non-complaint and complaint homes. Visible levels 

of corrosion were commonly observed on the metal coupons collected from complaint 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 65 of 128 
homes, while the metal coupons from non-complaint homes showed less evidence of 

corrosion. 

Figure 5.4 Photographs of Corrosion Coupons after Retrieval from One Non-complaint Home 

(A) and Three Complaint Homes (B – D) 

5.2.2 Characterization of Corrosion 

Corrosion rates from the silver coupons are reported as silver sulfide (Ag2S), silver 

chloride (AgCl), or unknown. For copper, the rates are reported as copper sulfide (Cu2S), 

copper oxide (Cu2O), or unknown. The dominant species found in this study for most 

homes were silver and copper sulfides. For the silver coupons, only one sample at the 

air supply register showed silver chloride based corrosion products on the test strip. 

Similar results were found for the coupons in the rooms. For the copper coupons, the 

samples were dominated by Cu2S but there was also a consistent, low-level rate of 

Cu2O corrosion (Figure 5.5). 

Summary statistics for corrosion rates, in angstrom per 30 days, are presented in 

Appendix A, Table A.3. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 66 of 128 
Study Homes

Corrosion Rates at the AHU Air Register

0

2000

4000

6000

8000

10000

Cu2S

Cu2O

Figure 5.5 Corrosion Rates at AHU Air Register for All 51 Homes, by Corrosion Species 

Corrosion species observed on the coupons were further validated using a subset of 

samples of co-located copper and silver coupons (n=6), which were also characterized 

using a scanning electron microscope (SEM) fitted with an energy dispersive 

spectroscopy (EDS) microprobe, and by x-ray photoelectron spectroscopy (XPS). The 

6 samples (12 total coupons) were selected based on the observation of tarnish with a 

visual inspection. EDS analysis established that corrosion was heterogeneous on all 

coupons, with very similar elemental composition consisting of carbon, oxygen, sulfur, 

and silicone. XPS analysis confirmed the EDS findings with additional characterizations 

of the relative contributions which varied from coupon to coupon (Table 5.2). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 67 of 128 
Table 5.2 Major, Minor, and Trace Elemental Composition of Corrosion Coupons Analyzed by 

Energy Dispersive Spectroscopy 

Metal Major Elements Minor Elements Trace Elements 

Copper C, O, Cu S, Si, O, Ag S, Ag, Cl, N 

Silver C, Ag S, O, Si, Cu Cl, N 

C carbon 

O oxygen 

Cu copper 

S sulfur 

Si silicone 

Ag silver 

N nitrogen 

Note: Variation was observed across samples. For example, sulfur was reported as a minor element in 

one copper sample and a trace element in another. 

As a result of these findings, the analysis focuses on the sulfide based corrosion 

throughout the results section. 

5.2.3 Comparison of Corrosion Across Rooms 

Corrosion test strips were deployed at up to four unique indoor locations as well as one 

outdoor location. A correlation matrix comparing results from each sampling location is 

presented in Table 5.3. Corrosion rates on co-located copper and silver coupons were 

moderately to strongly correlated in indoor locations (r=0.57 – 0.74; p<05). Similar 

correlations were observed for the same type of metal strip across rooms in the same 

home (r=0.51 – 0.78; p<0.01). Outdoor corrosion was not correlated with indoor 

corrosion (p>0.05) except for a weak correlation for copper (r=0.29-0.31; p=0.03-0.06). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 68 of 128 
Table 5.3 Corrosion Correlation Matrix 

Living Room Master Bedroom Bedroom 

AHU Air 

Register Outdoors 

Cu2S Ag2S Cu2S Ag2S Cu2S Ag2S Cu2S Ag2S Cu2S Ag2S

1 

 

Cu2S 

50 

0.62 1 

<0.001 

Living Room 

Ag2S 

50 50 

0.61 0.53 1 

<0.001 <0.001 

Cu2S 

50 50 51 

0.51 0.65 0.71 1 

<0.001 <0.001 <0.001 

Master 

Bedroom Ag2S 

50 50 51 51 

0.51 0.40 0.56 0.53 1 

<0.001 0.01 <0.001 <0.001 

Cu2S 

40 40 41 41 41 

0.48 0.63 0.73 0.78 0.57 1 

Bedroom 

0.002 <0.001 <0.001 <0.001 <0.001 

Ag2S 

40 40 41 41 41 41 

0.44 0.48 0.51 0.45 0.30 0.60 1 

0.002 <0.001 <0.001 0.001 0.05 <0.001 

Cu2S 

48 48 49 49 41 41 49 

0.48 0.65 0.61 0.68 0.46 0.82 0.74 1 

<0.001 <0.001 <0.001 <0.001 0.002 <0.001 <0.001 

AHU Air 

Register 

Ag2S 

48 48 49 49 41 41 49 49 

0.18 -0.05 0.29 0.04 0.30 0.10 0.31 0.20 1 

0.21 0.72 0.04 0.76 0.06 0.52 0.03 0.18 

Cu2S 

49 49 50 50 41 41 48 48 50 

0.1 0.17 0.01 -0.05 -0.04 0.01 0.08 0.01 0.04 1

Outdoors 

0.51 0.23 0.95 0.76 0.79 0.93 0.60 0.93 0.78 

Ag2S 

49 49 50 50 41 41 48 48 50 50

Cu2S copper sulfide 

Ag2S silver sulfide 

AHU air handling unit 

KEY 

correlation coefficient (Spearman r) 

p-value 

n (sample size) 

Note: bolded correlation coefficients are significant at p<0.05 

The range of corrosion rates were similar in rooms and significantly higher on the 

corrosion strips located near the AHU air register (Figure 5.6). This may be due to a 

greater volume and higher velocity of air moving past them on a regular basis or 

variations in temperature and relative humidity during AHU cycling. This issue is 

discussed further in Section 6.4.2. Outdoor corrosion rates were low on the silver and 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 69 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 70 of 128 

copper coupons, in general. The copper coupons located outdoors also exhibited 

significantly more variability than the outdoor silver coupons. 

Living Room

Master Bedroom

Bedroom/Office

AHU Air Register

Outdoor

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Living Room

Master Bedroom

Bedroom/Office

AHU Air Register

Outdoor

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.6 Corrosion Rates by Location within the Home and Outdoors 

5.2.4 Comparison of Corrosion by House Status 

Corrosion rates were compared based on the CPSC complaint or non-complaint house 

status (Figure 5.7). Complaint homes had significantly greater rates of corrosion on both 

the silver and copper coupons compared to non-complaint homes, on average (p<0.01). 

Multivariate regression modeling showed this finding remained after controlling for 

outdoor corrosion, indoor temperature and study region (p<0.01; model R2

=0.46 and 

0.43). These findings also remained when room-specific corrosion rate results (e.g., 

master bedroom, living room) were used in the regression models in place of corrosion 

rates at the AHU air register (p<0.05; model R2

=0.33 - 0.63). 
CPSC House Status

 Complaint Non-complaint

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

CPSC House Status

 Complaint Non-complaint

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

ISA Class

Severe

Harsh

Moderate

Mild

Figure 5.7 Comparison of Corrosion Film Thickness by CPSC House Status 

The house status determined using the FTIR/XRF marker to assess the presence or 

absence of imported drywall was compared against corrosion rates in the home, similar 

to Figure 5.8 that used the CPSC home status by complaint. Similar to the CPSC status, 

homes with the FTIR/XRF marker were found to have significantly elevated rates of both 

silver and copper corrosion, an effect that remained after controlling for outdoor 

corrosion, indoor temperature and study region in multivariate models (p<0.001) (see 

Tables 5.11 and 5.12). Using the FTIR/XRF marker to classify home status explained 

approximately 10% more of the variability in corrosion rates compared to the CPSC 

homeowner’s self reported home status (model R2

=0.57 for silver and 0.52 for copper). 

Models using room-specific corrosion rate results (e.g., master bedroom, living room) 

produced similar results (p<0.05; model R2

=0.40 – 0.63). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 71 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 72 of 128 

FTIR/XRF Marker of Chinese Drywall

 Present Not Present

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

FTIR/XRF Marker of Chinese Drywall

 Present Not Present

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.8 Comparison of Corrosion Film Thickness by FTIR/XRF Marker 

5.2.5 Corrosion Determined by Visual Inspection 

EH&E field technicians conducted inspections throughout the home and classified 

corrosion rates on various surfaces based on a three point scale: 1 = no visible 

corrosion; 2 = some visible corrosion; 3 = severe corrosion. Complete details of the 

corrosion scale with example photographs can be found in the Methods Section (Section 

4). 

Mean ground wire corrosion ratings for each home were compared based on CPSC 

home status (e.g., complaint or non-complaint) and FTIR/XRF marker. Complaint homes 

had a statistically significant greater mean ground wire corrosion rating than noncomplaint homes (Figure 5.9). 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 73 of 128 

Distribution of Mean Ground Wire Corrosion Rating

by CPSC Status

1

>1 - 1.5

>1.5 - 2

>2 - 2.5

>2.5 - 3

Percent of Homes

0%

20%

40%

60%

80%

100%

Complaint Homes

Non-Complaint Homes

Distribution of Mean Ground Wire Corrosion Rating

by FTIR/XRF Marker

1

>1 - 1.5

>1.5 - 2

>2 - 2.5

>2.5 - 3

Percent of Homes

0%

20%

40%

60%

80%

100%

FTIR/XRF Marker Present

FTIR/XRF Marker Not Present

Figure 5.9 Comparison of Mean Ground Wire Corrosion Rating by CPSC Home Status 

5.2.6 Comparison of Corrosion by Study Region 

Corrosion rates at the AHU air register were compared across the four major regions in 

the field study—Florida east coast, Florida west coast, Gulf Coast, Virginia (Figure 5.10). 

Only for corrosion measured at the AHU air register, both silver and copper corrosion 

were found to be significantly higher in the Florida East region compared to Virginia 

(p<0.01), with the model accounting for a relatively small amount of variability in 

corrosion overall (R2

=0.15;0.20). 

Region

Florida-East

Florida-West

Gulf Coast

Virginia

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Region

Florida-East

Florida-West

Gulf Coast

Virginia

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.10 Comparison of Corrosion Film Thickness Across Study Regions 
We examined potential explanatory variables to investigate the basis for the differences 

in corrosion rates observed across regions for the AHU air register. Contrary to the 

findings observed for corrosion at the AHU air register (Figure 5.10), there were no 

differences in room-level corrosion (e.g., bedroom, office) across the study regions. 

Additionally, there were no differences in the visual inspection of ground wire corrosion 

by region. The ground wire corrosion rating is a useful marker of long-term corrosion, 

although it will not be able to provide information on corrosion rate such as can be 

gathered through use of long-term coupons in the homes. The difference observed 

between coupons placed at the AHU air register and lack of a difference between 1) 

regions for room-level corrosion measured by corrosion coupons and 2) longer-term 

corrosion ascertained by visual inspection of ground wires suggest that the AHU supply 

air register corrosion differences by region are due to short-term environmental 

differences at the various AHU air registers that may not be reflective of the environment 

in the whole house. One plausible explanation is related to the ambient temperature 

during the sampling period by region; the maximum outdoor temperature during the 

sampling period in the Florida regions ranged from 91 – 97 (mean = 94), while the 

maximum outdoor temperature in Virginia ranged from 83 – 90 (mean = 84), with all 

homes in Virginia visited during the same 2-week period (Figure 5.11). The higher 

ambient air temperatures in the Florida regions would be associated with greater AHUload, resulting in a consistently lower temperature and greater air flow and deposition 

velocity (Vdep) at the AHU air register where greater corrosion rates were observed (see 

Section 6.4.2 for discussion of Vdep). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 74 of 128 
Region

Florida-East

Florida-West

Gulf Coast

Virginia

Maximum Outdoor Temperature (oF)

during Sampling Period 

80

85

90

95

100

Figure 5.11 Maximum Outdoor Temperature During the Sampling Period for Each Region 

5.3 AIR SAMPLING RESULTS 

Air sampling results are divided by target analyte group in the following sections. For 

each analyte group, summary statistics for each home are presented in the Appendix 

tables and a comparison of house average results is made by the CPSC home status. 

Results for select analytes are then compared against corrosion rates. 

5.3.1 Aldehydes via Active Sampling 

Summary statistics for aldehyde concentrations by home are presented in Appendix A 

(Table A.4). Indoor concentrations of aldehydes generally exceeded outdoor 

concentrations by an order of magnitude. 

 

5.3.1.1 Aldehyde Concentrations by House Status 

Aldehyde concentrations (μg/m3

) in indoor air stratified by the CPSC home status are 

presented in Table 5.4. The mean, median and 75th percentile values show the 

complaint and non-complaint homes are comparable. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 75 of 128 
Table 5.4 House Average Aldehyde (Active Sampler) Concentrations (μg/m3

) in Indoor Air by 

House Status 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Acetaldehyde Complaint 91.3 36.9 7 24.9 32.7 48.4 138.3 

Non-complaint 97.4 30.7 8.4 17.3 28.9 43.3 52.5 

Benzaldehyde Complaint 78.3 8 2.7 5.2 7.4 9.8 21.7 

Non-complaint 78.9 7.1 3.3 4.3 6.5 9.3 14.3 

Butyraldehyde Complaint 75.2 4.8 0.7 2.9 4 5.9 18.5 

Non-complaint 78.9 4.7 1.2 2.4 4 6.2 11.7 

Crotonaldehyde Complaint 0.6 0.6 0.5 0.5 0.5 0.5 2.2 

Non-complaint 0 0.5 0.5 0.5 0.5 0.5 0.5 

Dimethylbenzaldehyde Complaint 6.8 0.7 0.5 0.5 0.5 0.5 5.7 

Non-complaint 10.5 0.6 0.5 0.5 0.5 0.5 1.3 

Formaldehyde Complaint 96.3 83.5 21.7 48.7 59.4 97.3 361.7 

Non-complaint 97.4 62.4 27.7 40.7 58.9 74.7 128.4 

Complaint 55.3 1.5 0.5 0.9 1.4 2.2 4 Isovaleraldehyde 

Non-complaint 44.7 1.3 0.5 0.5 0.9 2.1 2.5 

Propionaldehyde Complaint 76.4 4.6 1 2.6 3.8 5.4 12.2 

Non-complaint 73.7 4.2 0.8 2.2 3.3 4.6 14 

Valeraldehyde Complaint 76.4 11.4 2 5.6 9.2 14.5 46 

Non-complaint 78.9 9.6 2.6 6.5 8.8 12 18.7 

m,p-Tolualdehyde Complaint 0 1 0.9 1 1 1 1.1 

Non-complaint 0 1 0.9 1 1 1 1 

n-Hexaldehyde Complaint 77 45.8 6.4 21.1 34.7 59 173.3 

Non-complaint 78.9 39.4 7.7 24.2 38.4 42.3 96.5 

o-Tolualdehyde Complaint 0 0.5 0.5 0.5 0.5 0.5 0.5 

Non-complaint 0 0.5 0.5 0.5 0.5 0.5 0.5 

μg/m3 micrograms per cubic meter 

pct percent 

min minimum 

p percentile 

max maximum 

Note: sample size is 41 for complaint; 10 for non-complaint 

5.3.1.2 Aldehyde Concentrations and Corrosion 

Formaldehyde concentrations from the active sampling program were compared against 

silver and corrosion rates (Figure 5.12). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 76 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 77 of 128 

Formaldehyde (μg/m3) 

0 100 200 300 400

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Formaldehyde (μg/m3) 

0 100 200 300 400

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.12 Comparison of Corrosion Film Thickness by Formaldehyde Concentration 

5.3.2 Aldehydes Via Passive Sampling 

Aldehyde concentrations were measured in a second set of samples using passive 

sampling techniques. The passive samplers were used because they provide lower 

detection limits due to a longer sampling period and the fact that they would be 

measuring the concentrations of aldehydes in the air that the passive samplers were 

exposed to over the two-week integration period which was also coincident with the 

corrosion coupon deployment. Results of the aldehyde concentrations collected on 

passive monitors for each home are reported in Appendix A (Table A.5). 

5.3.2.1 Aldehyde Concentrations by House Status 

Aldehyde concentrations measured using the passive monitors are presented by the 

CPSC house status in Table 5.5. 
Table 5.5 House Average Aldehyde (Passive Sampler) Concentrations (μg/m3

) in Indoor Air by 

House Status 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Acetaldehyde Complaint 93 9.6 0.7 5.5 9.9 12.5 21.8 

Non-complaint 100 11.5 5.4 8.1 12.3 14 19.4 

Acrolein Complaint 47 3 0.8 1 2.9 4.1 8 

Non-complaint 60 3.2 0.8 2.3 3.1 4.6 5.4 

Benzaldehyde Complaint 76 2.6 1.3 1.9 2.7 3.3 4.2 

Non-complaint 75 2.3 1.3 2.1 2.4 2.6 3.4 

Butanal Complaint 94 24.5 2.7 16.3 22.1 26.2 98.2 

Non-complaint 100 29.1 9.5 20.9 31.4 33.5 56.8 

Formaldehyde Complaint 100 54.2 22.5 47.4 52.8 62.6 85.6 

Non-complaint 100 44 27.6 32.5 41.7 54.6 64.7 

Complaint 12 0.7 0.4 0.5 0.5 1 1.8 Isovaleraldehyde 

Non-complaint 15 0.7 0.5 0.5 0.5 0.7 1.3 

Propionaldehyde Complaint 68 3 0.7 1.5 3.2 4 7.8 

Non-complaint 98 4.1 2.2 2.8 3.6 5.6 6.7 

Valeraldehyde Complaint 94 25.8 4.7 16.6 25 34 46.4 

Non-complaint 98 26.8 8.4 13.4 25 40.5 50 

nHexaldehyde Complaint 100 134.1 24.3 81.3 118.7 178.9 316.9 

Non-complaint 100 138.1 27.5 61.9 135.7 175.9 340.1 

μg/m3 micrograms per cubic meter 

pct percent 

min minimum 

p percentile 

max maximum 

Note: sample size is 41 for complaint; 10 for non-complaint 

5.3.2.2 Aldehyde Concentrations and Corrosion 

Aldehydes concentrations measured using passive monitors were compared to silver 

and copper corrosion. Results for formaldehyde are presented in Figure 5.13. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 78 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 79 of 128 

Formaldehyde (μg/m3) 

0 30 60 90

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Formaldehyde (μg/m3) 

0 30 60 90

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.13 Comparison of Corrosion Rates at the AHU Air Register by House Average 

Formaldehyde Concentration Measured Using 2-week Passive Monitors 

5.3.3 Reduced Sulfur Gases via Grab Sampling 

The majority of samples collected in the homes using grab sample methods had reduced 

sulfur concentrations less than the reporting limit for the analytical method (see Section 

4 for reporting limits). Only 9 samples were above the reporting limit for carbon disulfide 

(max concentration = 12 μg/m3

; reporting limit = 7.8 μg/m3). The 9 detected samples 

came from 4 homes, 3 of which were located within the same neighborhood. Carbonyl 

sulfide was also detected in one reduced sulfur sample (concentration = 13 μg/m3

; 

reporting limit = 12 μg/m3

).

5.3.4 Hydrogen Sulfide, Ozone, Nitrogen Dioxide, Sulfur Dioxide, Hydrofluoric 

Acid (Passive Sampling) 

Concentrations for analytes collected using passive monitors with low limits of detection 

and two-week integration periods are reported for each home (Appendix A, Table A.6). 

5.3.4.1 H2S, O3, NO2, SO2, HF by House Status 

House average concentrations (parts per billion [ppb]) of analytes collected over a twoweek integration period are presented by the CPSC home status in Table 5.6. 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 80 of 128 

Table 5.6 House Average Concentrations (ppb) of Analytes Collected Using Passive Samplers

Analyte Status 

Pct 

Detect Mean Min p25 p50 p75 Max 

Hydrogen Complaint 65.8 0.66 0.19 0.29 0.59 0.88 2.23

sulfide Non-complaint 37.5 0.45 0.2 0.22 0.23 0.28 2.23

Ozone Complaint 25.9 0.36 0.3 0.33 0.34 0.36 0.92

Non-complaint 25 0.34 0.31 0.33 0.34 0.36 0.36

Nitrogen Complaint 97.5 2.6 0.06 0.7 1.09 3.67 12.49

dioxide Non-complaint 100 4.42 0.89 1.77 2.15 5.03 18.67

Sulfur dioxide Complaint 0 NA NA NA NA NA NA

Non-complaint 2.6 1.44 1.34 1.36 1.41 1.46 1.73

Hydrogen Complaint 0 NA NA NA NA NA NA

fluoride Non-complaint 0 NA NA NA NA NA NA

ppb parts per billion 

pct percent 

min minimum 

p percentile 

max maximum 

NA not applicable 

Note: sample size is 41 for complaint; 10 for non-complaint 

5.3.4.2 H2S, O3, NO2, SO2, HF and Corrosion 

Hydrogen sulfide and nitrogen dioxide concentrations were compared to rates of silver 

and copper corrosion (Figure 5.14). 

Hydrogen Sulfide (ppb) 

0123

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Hydrogen Sulfide (ppb) 

0123

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.14a Comparison of Corrosion Rates at the AHU Air Register by House Average 

Hydrogen Sulfide Concentration Measured Using 2-week Passive Monitors 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 81 of 128 

Nitrogen Dioxide (ppb) 

0 5 10 15 20

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Nitrogen Dioxide (ppb) 

0 5 10 15 20

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.14b Comparison of Corrosion Rates at the AHU Air Register by House Average 

Nitrogen Dioxide Concentration Measured Using 2-week Passive Monitors 

5.3.5 Volatile Organic Compounds 

Summary statistics of VOC concentrations (μg/m3

) in indoor and outdoor air are 

presented in Appendix A, Table A.7. 

5.3.5.1 VOCs by House Status 

House average concentrations for select VOCs in indoor air stratified by the CPSC 

house status are presented in Table 5.7. Several VOCs show elevated concentrations in 

complaint homes (n=26) compared to non-complaint homes (n=5). Statistical 

comparisons are currently limited due to the small sample size of non-complaint homes 

with VOC samples. 
Table 5.7 House Average VOC Concentrations (μg/m3

) in Indoor Air by House Status 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

1,1,2- Complaint 96 0.57 0.06 0.51 0.57 0.64 0.74

Trichlorotrifluoroethane Non-complaint 85 0.56 0.14 0.49 0.67 0.73 0.78

Complaint 70 6.97 0.31 2.58 5.01 9.48 28.83

1,2,4-Trimethylbenzene Non-complaint 65 5.44 0.62 0.93 5.05 6.42 14.17

Complaint 96 7.88 0.31 4.51 5.73 10.5 29.5

2-Butanone (MEK) Non-complaint 95 11.52 3.22 3.57 4.48 8.35 38

2-Propanol (Isopropyl Complaint 87 66.38 0.31 7.62 13.85 92.75 355

Alcohol) Non-complaint 75 11.42 5.45 6.26 9.93 11.47 24

Complaint 95 112.17 3.05 64.75 115 155 220

Acetone Non-complaint 85 74.75 41.5 55.9 80.67 85 110.67

Complaint 82 134.03 0.36 58.25 107.54 233.33 265

Acetonitrile Non-complaint 89 141.56 58 58 76.67 290 290

Complaint 91 5.88 0.31 4.08 5.51 6.98 14.67

Acrolein Non-complaint 95 4.38 1.62 2.77 5.5 5.87 6.13

Complaint 95 5.88 0.06 1.38 2.92 7.85 30.83

Benzene Non-complaint 85 4.27 0.27 0.4 2.07 4.45 14.17

Complaint 55 1.76 0.31 0.52 1.31 2.3 9.1

Carbon Disulfide Non-complaint 25 0.57 0.31 0.31 0.39 0.69 1.15

Complaint 95 0.61 0.06 0.48 0.57 0.67 1.23

Carbon Tetrachloride Non-complaint 85 0.48 0.13 0.45 0.59 0.62 0.62

Complaint 80 1.9 0.06 0.32 1.01 2.55 9.23

Chloroform Non-complaint 70 1.08 0.3 0.43 1.06 1.66 1.97

Complaint 93 1.19 0.06 0.72 0.87 1.1 9.67

Chloromethane Non-complaint 70 0.47 0.06 0.19 0.53 0.68 0.88

Complaint 90 1106.18 3.05 131.67 389.17 1450 5066.67

Ethanol Non-complaint 80 362.61 100.5 235.9 328.33 421.67 726.67

Complaint 71 10.22 0.31 1.88 4.88 9.82 58

Ethyl Acetate Non-complaint 75 7.51 2.09 3.37 6.23 6.35 19.5

Complaint 66 6.4 0.31 1.68 5.04 7.6 24.67

Ethylbenzene Non-complaint 60 4.47 0.59 1.09 4.47 6.27 9.95

Complaint 71 3.53 0.31 1.81 2.98 4.28 10

Styrene Non-complaint 65 1.85 0.52 1.28 1.47 1.68 4.28

Complaint 91 32.77 0.31 14.17 21.03 42 124.67

Toluene Non-complaint 70 20.91 1.62 5.45 21.67 28 47.83

Complaint 97 1.4 0.06 1.25 1.42 1.55 2.2

Trichlorofluoromethane Non-complaint 85 1.14 0.25 1.18 1.3 1.4 1.55

Complaint 87 88.47 0.31 36.25 77.58 116.67 235

α-Pinene Non-complaint 80 53.08 7.92 30.67 52.33 83.83 90.67

Complaint 79 25.86 0.31 15 24.63 39.5 57

d-Limonene Non-complaint 65 12.09 5.09 7.2 14.83 15.17 18.17

Complaint 81 20.5 0.31 6.93 14.46 24.17 82.5

m,p-Xylenes Non-complaint 65 14.46 1.92 2.92 14.63 19.5 33.33

Complaint 73 4.87 0.31 1.68 3.22 5.07 26.33

n-Butyl Acetate Non-complaint 65 2.7 0.54 1.81 3.05 3.17 4.95

Complaint 67 4.66 0.31 1.55 3.03 5.9 25.67

n-Heptane Non-complaint 50 3.05 0.31 0.61 1.08 3.38 9.85

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 82 of 128 
Table 5.7 Continued 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Complaint 73 10.28 0.31 1.05 5.08 12.65 71.33

n-Hexane Non-complaint 50 6.14 0.31 0.47 1.62 9.15 19.17

Complaint 71 2.25 0.31 1.25 1.6 2.23 12.67

n-Octane Non-complaint 70 1.91 0.42 0.77 1.05 2.05 5.27

Complaint 67 7.34 0.31 1.43 5.23 9.09 27.83

o-Xylene Non-complaint 65 4.69 0.83 1.07 4.93 5.07 11.53

μg/m3 micrograms per cubic meter 

pct percent 

min minimum 

p percentile 

max maximum 

Note: sample size is 26 for complaint; 5 for non-complaint 

The results presented in Table 5.7 suggest that one reduced sulfur compound, carbon 

disulfide, may be slightly elevated in complaint homes compared to non-complaint 

homes. Boxplots comparing summary statistics for carbon disulfide by the CPSC home 

status and FTIR/XRF marker is presented in Figure 5.15. In statistical models (n=29), a 

significant difference in house average carbon disulfide concentrations was not observed 

by CPSC status (p=0.26) or by FTIR/XRF marker (p=0.26) after controlling for outdoor 

carbon disulfide concentrations and study region (see Table 5.10). Statistical inference is 

limited due to the small sample size. 

CPSC Status

Complaint Non-Complaint

Carbon Disulfide (μg/m3

)

0

2

4

6

8

10

FTIR/XRF Marker of Chinese Drywall

Present Not Present

Carbon Disulfide (μg/m3

)

0

2

4

6

8

10

Figure 5.15 Boxplots of House Average Carbon Disulfide Concentrations by CPSC Home 

Status 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 83 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 84 of 128 

5.3.5.2 Selected VOCs and Corrosion 

Carbon disulfide concentrations were also compared against silver and copper corrosion 

rates in the home. 

Carbon Disulfide (μg/m3) 

0 2 4 6 8 10

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Carbon Disulfide (μg/m3) 

0 2 4 6 8 10

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.16 Comparison of Corrosion Film Thickness at the AHU Air Register by House 

Average Carbon Disulfide Concentration 

5.3.6 Organic and Inorganic Acids 

Only three of the acids sampled and analyzed for had values above the limit of 

detection. Summary statistics for the detected acids in indoor and outdoor samples are 

presented in Appendix A, Table A.8. 

5.3.6.1 Acids by House Status 

Results for the two organic acids and one inorganic acid that were found above the 

detection limit are presented in Table 5.8 by the CPSC house status. Concentrations of 

the acids appear similar in complaint and non-complaint homes, but inference is limited 

due to low percent detects for formic acid and hydrofluoric acid. 
Table 5.8 House Average Acid Concentrations (ppb) in Indoor Air by House Status 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Acetic Acid Complaint 51 99 9 41 60 119 440 

Non-complaint 51 67 17 42 55 98 137 

Formic Acid Complaint 26 11 4 4 7 18 35 

Non-complaint 23 9 4 4 6 13 20 

Hydrofluoric Acid Complaint 8 25 16 19 20 21 94 

Non-complaint 0 NA NA NA NA NA NA

ppb parts per billion 

pct percent 

min minimum 

p percentile 

max maximum 

NA not applicable 

Note: sample size is 41 for complaint; 10 for non-complaint 

5.3.7 Home Characteristics 

5.3.7.1 Air Exchange Rate 

Air exchange rates, in units of air changes per hour (ACH), are presented for each home 

in Appendix A, Table A.9. Short-term, house average air exchange rates ranged from 

0.05 – 0.8 ACH (median 0.19), indicating that the majority of these homes were tightly 

sealed homes with low ventilation rates. 

5.3.7.1.1 Air Exchange Rate by House Status 

Short-term, house average air exchange rates were compared by the CPSC house 

status and found to be similar between complaint and non-complaint homes, with status 

explaining only 6% of the variability in air exchange rate (mean air exchange rate 0.18 v. 

0.24 ACH; p=0.09; R2

=0.06) (Figure 5.17). Similar findings were observed when using 

FTIR/XRF marker in place of the CPSC house status (p=0.26, R2

=0.03). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 85 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 86 of 128 

CPSC Status

Complaint Non-Complaint

Air Exchange Rate (h-1) 0.0

0.2

0.4

0.6

0.8

1.0

FTIR/XRF Marker of Chinese Drywall

Present Not Present

Air Exchange Rate (h-1) 0.0

0.2

0.4

0.6

0.8

1.0

Figure 5.17 Comparison of Short-term, House Average Air Exchange Rates by CPSC House 

Status and FTIR/XRF Status 

5.3.7.1.2 Air Exchange Rate v. Corrosion 

A comparison of air exchange rates and silver and copper corrosion is presented in 

Figure 5.18. 

Air Exchange Rate (h-1)

0.0 0.2 0.4 0.6 0.8 1.0

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Air Exchange Rate (h-1)

0.0 0.2 0.4 0.6 0.8 1.0

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.18 Comparison of Corrosion Film Thickness at the AHU Air Register by Air Exchange 

Rate 
5.3.7.2 Temperature and Dew Point 

Temperature and dew point values were averaged over the two-week passive sampling 

period. The two-week average values are reported for each home in Appendix A (Table 

A.10). Two-week average temperature ranged from 71 – 87 °F (median = 77 °F), and 

two-week average dew point ranged from 50 – 74 (median = 58) for individual homes. 

An examination of hourly average temperature over the two-week period showed some 

homes with stable temperature ranges and others with diurnal patterns, reflecting the 

use patterns of air handling devices to maintain stable temperature in the home. Certain 

unoccupied study homes may have had their AHUs off during a portion or all of the 

sampling periods and would account for the extreme high values in the range noted 

above. 

5.3.7.2.1 Temperature and Dew Point by House Status 

Temperature and dew point results were stratified by the CPSC house status (Figure 

5.19). Complaint homes demonstrated more between-home variability for both 

temperature and dew point than non-complaint homes. Again, this may be due to lack of 

consistent AHU use in vacant homes. 

Status

Complaint Non-complaint

Temperature (oF)

70

75

80

85

90

Status

Complaint Non-complaint

Dew Point (oF)

40

50

60

70

80

Figure 5.19 Boxplots of Indoor Temperature by CPSC Home Status 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 87 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 88 of 128 

5.3.7.2.2 Temperature and Dew Point and Corrosion 

Temperature and dew point were compared against silver and copper corrosion rates. A 

potential positive association was observed between temperature and silver corrosion 

rate at the AHU air register (Figure 5.20). 

Temperature (oF)

70 75 80 85 90

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Temperature (oF)

70 75 80 85 90

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Dew Point (oF)

40 50 60 70 80

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Dew Point (oF)

40 50 60 70 80

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.20 Comparison of Dry Bulb Temperature and Dew Point to Silver and Copper 

Corrosion Rates 

5.3.8 Multivariate Modeling 

Multivariate regression modeling was used to explore relationships between 

characteristics of drywall, constituents of indoor air, and corrosion observed for the 
homes in this investigation as reported in Section 5.2 while controlling for potential 

confounding and/or explanatory variables. The modeling aimed to address three 

questions: 

1) Are reduced sulfur gases in indoor air associated with the presence of imported 

drywall (if so, what house characteristics/environmental conditions are associated 

with the presence of those compounds)? 

2) Are corrosion rates associated with the presence of imported drywall? 

3) Which compounds or house characteristics are associated with corrosion rates? 

5.3.8.1 Reduced Sulfur Gases and Imported Drywall 

5.3.8.1.1 Hydrogen Sulfide 

A comparison of hydrogen sulfide concentration (ppb) by the CPSC home status and by 

FTIR/XRF marker is presented in Figure 5.21. In general, house average hydrogen 

sulfide concentrations in complaint homes appear to be higher than in non-complaint 

homes. However, there is considerable variability in the non-complaint homes driven by 

one home with elevated hydrogen sulfide concentrations. 

CPSC Status

Complaint Non-Complaint

Hydrogen Sulfide (ppb)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

FTIR/XRF Marker of Chinese Drywall

Present Not Present

Hydrogen Sulfide (ppb)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Figure 5.21 House Average Hydrogen Sulfide Concentration (ppb) by a) CPSC House Status, 

and b) FTIR/XRF Marker 

House-average hydrogen sulfide concentrations were modeled as a function of house 

status while controlling for potential confounding variables. With a median concentration 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 89 of 128 
of 0.59 ppb, complaint homes, as determined by CPSC, had significantly (p<0.05) 

elevated concentrations of hydrogen sulfide (natural log-transformed) compared to 

homes with domestic drywall (median < reporting limit [0.35-0.50]) controlling for outdoor 

hydrogen sulfide concentrations, study region and dew point (Table 5.9). The hydrogen 

sulfide concentrations can be characterized as a dichotomous variable based on the 

presence or absence of the gas. Dew point was also a significant and positive predictor 

of indoor hydrogen sulfide concentrations in these homes (p<0.01) while outdoor 

hydrogen sulfide was not (p=0.11). (Potentially relevant variables such as air exchange 

rate and study region were not associated with concentrations of hydrogen sulfide in 

indoor air. Covariate selection was based on bivariate relationships evaluated at the 

p<0.10 level – see Methods Section for details). When the model was re-run with house 

status determined by FTIR/XRF, as opposed to CPSC status, status remained a 

significant predictor of hydrogen sulfide levels (p<0.01; R2

=0.39). Additionally, when 

these analyses are repeated with the one influential point removed (i.e., one noncomplaint home with elevated hydrogen sulfide), the associations are further 

strengthened (R2

=0.53 [CPSC status]; 0.58 [FTIR/XRF marker]). 

Table 5.9 Regression Model Results Showing Predictors of House Average Hydrogen Sulfide 

Concentrations (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept -4.39 0.93 <0.0001 

FTIR/XRF Marker Present 0.52 0.19 0.009 

FTIR/XRF Marker Not Present – – – 

Outdoor Hydrogen Sulfide (H2S) 0.17 0.10 0.11 

Dew Point 0.05 0.02 0.002 

Model R2

=0.39 

Dew point was a significant predictor of hydrogen sulfide concentrations in indoor air in 

the regression model. A scatterplot comparing hydrogen sulfide concentrations by dew 

point was made to further demonstrate the potential role of dew point as a modifying 

factor associated with the presence of hydrogen sulfide, stratifying by type of drywall as 

determined by FTIR/XRF marker (Figure 5.22). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 90 of 128 
Dew Point (o

F)

40 50 60 70 80

Hydrogen Sulfide (ppb)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Present

Not Present

Figure 5.22 Scatterplot Comparing House Average Hydrogen Sulfide Concentration (ppb) 

by Dew Point, Stratified by Drywall Type as Determined by FTIR/XRF Marker 

5.3.8.1.2 Carbon Disulfide 

Carbon disulfide concentrations were elevated in CPSC complaint homes compared to 

non-complaint homes (Figure 5.15). Similar results were observed for house 

classification based on FTIR/XRF (Figure 5.23). 

CPSC Status

Complaint Non-Complaint

Carbon Disulfide (μg/m3

)

0

2

4

6

8

10

FTIR/XRF Marker of Chinese Drywall

Present Not Present

Carbon Disulfide (μg/m3

)

0

2

4

6

8

10

Figure 5.23 Boxplots of House Average Carbon Disulfide Concentrations by CPSC Home 

Status 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 91 of 128 
House-average carbon sulfide concentrations were then modeled as a function of house 

status while controlling for potential confounding variables. Homes with imported drywall, 

as determined by FTIR/XRF, did not have significantly elevated concentrations of carbon 

disulfide (natural log-transformed) compared to homes with domestic drywall, on 

average, controlling for outdoor carbon sulfide concentrations and study region (p=0.29) 

(Table 5.10). This null finding is limited by the small sample size and resultant low power 

to see a difference between groups if one is present (Type II error). Similar results were 

obtained when CPSC status was modeled in place of the FTIR/XRF marker (p=0.25). 

Several parameters were significant predictors of indoor carbon disulfide concentrations 

on a bivariate basis (dew point p=0.08; temperature p=0.03) but could not be included in 

one regression model due to sample size (n=29). 

Table 5.10 Regression Model Results Showing Predictors of House Average Carbon Disulfide 

Concentrations (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept -0.56 0.36 0.13 

FTIR/XRF Marker Present 0.39 0.36 0.29 

FTIR/XRF Marker (ref) – – – 

Region—Florida East 0.95 0.41 0.03 

Region—Florida West -0.15 0.41 0.73 

Region—Gulf Coast -0.33 0.44 0.45 

Region—Virginia (ref) – – – 

Outdoor Carbon Disulfide (CS2) 0.16 0.14 0.26 

Model R2

=0.40 

5.3.8.2 Corrosion Rates and Imported Drywall 

Homes with imported drywall were found to have elevated rates of both silver and 

copper corrosion compared to homes with domestic drywall, as determined by 

FTIR/XRF (see Section 5.2.3; Figure 5.8 reproduced here as Figure 5.24). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 92 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 93 of 128 

FTIR/XRF Marker of Chinese Drywall

 Present Not Present

Ag2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

FTIR/XRF Marker of Chinese Drywall

 Present Not Present

Cu2S Corrosion Rate (A/30 d) at AHU Air Register

101

102

103

104

Moderate

Severe

Harsh

Mild

ISA Class

Figure 5.24 Comparison of Corrosion Film Thickness by FTIR/XRF Marker 

To examine this relationship further, predictors of corrosion rates (natural logtransformed) at the AHU air register and in rooms were modeled. The findings from the 

bivariate analysis hold in regression models that control for corrosion rates outdoors, 

study region and indoor temperature (Tables 5.11 and 5.12); homes with imported 

drywall as determined by FTIR/XRF had elevated rates of silver and copper corrosion, 

on average (p<0.001). The variables explain 57% and 52% of the variability in silver and 

copper corrosion, respectively. In both models, the east coast of Florida region had 

significantly elevated corrosion compared to the Virginia region. 

Table 5.11 Regression Model Results Showing Predictors of Silver Corrosion Rates at the AHU 

Air Register (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept 4.00 2.27 0.09 

FTIR/XRF Marker Present 1.56 0.26 <.0001 

FTIR/XRF Marker (ref) – – – 

Region—Florida East 0.98 0.36 0.01 

Region—Florida West 0.49 0.38 0.21 

Region—Gulf Coast 0.20 0.34 0.55 

Region—Virginia (ref) – – – 

Outdoor Silver Sulfide (Ag2S) 0.001 0.001 0.23

Temperature (°F) 0.02 0.03 0.59 

Model R2

=0.57 
Table 5.12 Regression Model Results Showing Predictors of Copper Corrosion Rates at the 

AHU Air Register (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept 6.27 4.54 0.18 

FTIR/XRF Marker Present 2.74 0.52 <.0001 

FTIR/XRF Marker (ref) – – –

Region—Florida East 2.16 0.76 0.01 

Region—Florida West 1.11 0.74 0.14 

Region—Gulf Coast 0.53 0.57 0.43 

Region—Virginia (ref) – – – 

Outdoor Copper Sulfide (Cu2S) 0.0003 0.0003 0.33

Temperature (°F) -0.05 0.06 0.42 

Model R2

=0.52 

Consistent results were found when room-level corrosion rates were modeled as a 

function of house status determined by FTIR/XRF marker and the same potential 

confounding variables (p<0.01; R2

=0.41 – 0.63). As expected based on the results of the 

analysis by Region in Section 5.2.6, there were no differences in room-level corrosion by 

study region. Additionally, using CPSC status in place of the FTIR/XRF marker produced 

similar results, with models using the FTIR/XRF marker explaining approximately 10% 

more of the variability in room-level corrosion rates. 

5.3.8.3 Predictors of Corrosion Rates in Homes 

In Section 5.3.8.1, reduced sulfur gases were found to be elevated in homes with the 

FTIR/XRF marker present compared to homes where it was not present. In Section 

5.3.8.2, corrosion rates were found to be elevated in homes with imported drywall 

compared to domestic drywall. In this section, the direct relationship between corrosion 

and reduced sulfur gases and other factors is examined. 

In the first set of analyses, house-average reduced sulfur concentrations were compared 

to corrosion rates from the AHU supply air register. House-average, indoor hydrogen 

sulfide concentrations were positively and significantly associated with silver and copper 

corrosion rates (natural log-transformed) in homes, on average (p<0.05) (Tables 5.13 

and 5.14). As with previous models, the east coast of Florida had significantly elevated 

rates of corrosion compared to the Virginia study region. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 94 of 128 
Table 5.13 Regression Model Results Showing Predictors of Silver Corrosion Rates at the AHU 

Air Register (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept 5.98 0.39 <.0001 

Indoor H2S 0.93 0.32 0.01 

Indoor Formaldehyde 0.002 0.002 0.45 

Region—Florida East 1.17 0.41 0.01 

Region—Florida West 0.65 0.43 0.14 

Region—Gulf Coast 0.14 0.42 0.75 

Region—Virginia (ref) – – –

Model R2

=0.32 

Table 5.14 Regression Model Results Showing Predictors of Copper Corrosion Rates at the 

AHU Air Register (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept 4.01 0.73 <.0001 

Indoor H2S 1.51 0.61 0.02 

Indoor Formaldehyde -0.01 0.005 0.11 

Region—Florida East 2.61 0.78 0.002 

Region—Florida West 1.26 0.83 0.13 

Region—Gulf Coast 0.80 0.80 0.32 

Region—Virginia (ref) – – –

Model R2

=0.31 

Using room-specific corrosion rates (i.e., master bedroom, living room) as the outcome 

variable yielded similar results. For silver, house-average hydrogen sulfide was 

significantly associated with room-specific corrosion rates for the living room and 

bedroom (p<0.05), with a suggestive association observed in the master bedroom 

(p=0.07). Interestingly, house average formaldehyde was significantly associated with 

corrosion in the master and secondary bedroom (p<0.05). For copper, there was 

suggestive evidence that house average hydrogen sulfide was associated with corrosion 

rates in the master and secondary bedrooms (p<0.06-0.08). These findings suggest that 

room-level analysis of the relationship between hydrogen sulfide, formaldehyde and 

corrosion is warranted. 

The second set of analyses, therefore, focused on room-specific results and 

incorporated co-located room measurements of airborne compounds and corrosion 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 95 of 128 
rates. Linear mixed effects models were used to examine relationships between colocated measurements while accounting for within-home correlation of measurements. 

Hydrogen sulfide concentrations were positively and significantly associated with roomspecific silver corrosion rates in homes, controlling for outdoor hydrogen sulfide 

concentrations and study region (p=0.01). In this model, formaldehyde was also 

positively associated with silver corrosion rates (p=0.01). 

Table 5.15 Linear Mixed Effects Model Fixed Effects Results for Predictors of Room-Specific 

Silver Corrosion Rates (Natural log-transformed) 

Effect Estimate Standard Error p-value 

Intercept 5.42 0.28 <.0001 

Indoor Hydrogen Sulfide (H2S) 0.54 0.19 0.005 

Indoor Formaldehyde 0.004 0.002 0.01 

Region—Florida East 0.30 0.31 0.34 

Region—Florida West 0.09 0.32 0.78 

Region—Gulf Coast 0.13 0.32 0.67 

Region—Virginia (ref) – – –

To further examine the relationship between hydrogen sulfide and formaldehyde 

concentrations on silver corrosion, a multiplicative interaction term was added to the 

linear mixed effects model. A dichotomous variable indicating the presence or absence 

of hydrogen sulfide was created (LOD ~ 0.35 ppb). Suggestive evidence of interaction 

was observed between formaldehyde and the presence of hydrogen sulfide; the effect of 

formaldehyde on silver corrosion in rooms was dependent upon, and increases, in the 

presence of hydrogen sulfide (p=0.08) (Table 5.16). 

Table 5.16 Interaction Mode—Linear Mixed Effects Model Fixed Effects Results for Predictors 

of Room-Specific Silver Corrosion Rates (Natural log-transformed) 

Effect Estimate Standard Error p-value 

Intercept 5.82 0.34 <.0001 

Indoor H2S Present 0.05 0.35 0.88 

Indoor H2S (ref) – – –

Indoor Formaldehyde -0.002 0.004 0.63 

Region—Florida East 0.27 0.29 0.35 

Region—Florida West 0.07 0.31 0.82 

Region—Gulf Coast 0.24 0.29 0.42 

Region—Virginia (ref) – – –

Indoor Formaldehyde*H2S Present 0.01 0.004 0.08 

Indoor Formaldehyde*H2S (ref) – – –

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 96 of 128 
To aid in interpretation of the interaction model results presented in Table 5.16, a 

scatterplot was created comparing measured formaldehyde concentrations in the 

presence or absence of hydrogen sulfide (Figure 5.25). The figure suggests that for 

homes with hydrogen sulfide present, an increase in formaldehyde concentrations is 

associated with an increase in silver corrosion. 

Formaldehyde (μg/m3)

0 100 200 300 400

Ag

2S Corrosion Rate (A/30 d) 

101

102

103

104

H2S Present (> 0.25 ppb)

H2S Not Present (< 0.25 ppb)

Figure 5.25 Scatterplot of Silver Corrosion Rate by Indoor Formaldehyde Concentration, 

Stratified by the Presence or Absence of Hydrogen Sulfide 

For copper corrosion, hydrogen sulfide concentrations were positively and significantly 

associated with room-specific corrosion rates in homes, controlling for outdoor hydrogen 

sulfide concentrations and study region (p=0.04) (Table 5.17). Similar to the AHU air 

register corrosion model (Table 5.14), formaldehyde concentrations were not associated 

with room-specific copper corrosion (p=0.20). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 97 of 128 
Table 5.17 Linear Mixed Effects Model Fixed Effects Results for Predictors of Room-Specific 

Copper Corrosion Rates (Natural log-transformed) 

Effect Estimate Standard Error p-value 

Intercept 3.16 0.50 <.0001 

Indoor Hydrogen Sulfide (H2S) 0.67 0.32 0.04 

Indoor Formaldehyde 0.004 0.003 0.20 

Region—Florida East 1.35 0.55 0.02 

Region—Florida West 0.62 0.57 0.28 

Region—Gulf Coast 0.22 0.56 0.69 

Region—Virginia (ref) – – – 

All of the models presented that include formaldehyde concentrations are based on the 

short-term, active air sampling of formaldehyde. In addition to the active sampling, 

2-week integrated formaldehyde concentrations were measured using passive monitors. 

The regression analyses were repeated using the 2-week formaldehyde concentrations. 

Hydrogen sulfide remained a significant predictor of corrosion controlling for 

formaldehyde concentrations regardless of the type of formaldehyde measurement (e.g., 

active or passive) (p<0.05). However, contrary to the findings for formaldehyde 

concentrations measured with active sampling, 2-week formaldehyde concentrations 

measured passively was only a marginal predictor of silver corrosion in the mixed effects 

models, and not statistically associated with copper corrosion (p=0.09, p=0.17, 

respectively). One plausible reason for this observation is that the 2-week measurement 

averages through diurnal effects, while the short-term active sample captured peak 

formaldehyde concentration during day-time hours. 

Potential contributors to formaldehyde concentrations were also explored. Indoor 

temperature was a significant predictor of formaldehyde concentrations in the home 

(Table 5.18), with increased temperatures associated with increased formaldehyde 

concentrations (p<0.001), controlling for outdoor formaldehyde concentration and study 

region (R2

=0.31). A scatterplot depicting the bivariate association between temperature 

and formaldehyde is presented in Figure 5.26. A consistent relationship between 

formaldehyde and temperature was also found when the 2-week formaldehyde 

measurement was used (p<0.01; R2

=0.23). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 98 of 128 
Table 5.18 Regression Model Results Showing Predictors of House Average Formaldehyde 

Levels (Natural log-transformed) in Indoor Air 

Parameter Estimate Standard Error p-value 

Intercept -1.57 1.53 0.31 

Region—Florida East -0.34 0.30 0.25 

Region—Florida West -0.45 0.30 0.15 

Region—Gulf Coast 0.02 0.30 0.93 

Region—Virginia (ref) – – – 

Indoor Temperature 0.07 0.02 <0.001 

Outdoor Formaldehyde 0.05 0.05 0.28 

Model R2

=0.32 

Temperature (oF)

70 75 80 85 90

Formaldehyde (

μg/m3

)

0

100

200

300

400

Figure 5.26 Scatterplot Comparing House Average Formaldehyde Concentrations (μg/m3

) 

Across Temperature Ranges (°F) 

 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 99 of 128 
6.0 DISCUSSION 

6.1 SUMMARY 

An early objective of this study was to identify reliable markers of imported drywall (and 

techniques for measuring the marker). These measurement techniques were then used 

to evaluate the presence or absence of imported drywall in sample homes. The homes 

were selected by CPSC staff for inclusion in this study and were located in 

five states in the southeastern United States. CPSC classified the homes into two types, 

complaint and non-complaint. EH&E was blind to the classification of the homes during 

the site visits and data collection phase of the study. There were 41 complaint homes 

selected by CPSC from their existing incident reporting database and 10 non-complaint 

homes recruited by CPSC for a total sample size of 5 homes. The 10 non-complaint 

homes were located in the same neighborhoods as the complaint homes and were 

selected to approximate the characteristics of the complaint homes as much as possible. 

EH&E visited each of the 51 homes and collected data on construction/building related 

characteristics such as the presence of imported drywall, locations of the types drywall, 

dimensions of the drywall, house and room size, type of construction, geographic 

location, air exchange rate and the type of heating ventilation and air conditioning 

systems. In addition, air samples were collected for a wide range of chemical agents 

including reduced sulfur gases, aldehydes, volatile organic compounds, organic and 

inorganic acids. To assess the corrosivity of the atmosphere inside the building, 

corrosion coupons composed of precleaned copper and silver test strips were placed 

inside and outside the home. Physical parameters such as temperature and relative 

humidity were also measured inside and outside the home. After data collection the data 

were analyzed using statistical techniques that included log linear models (random and 

fixed effects), correlation analysis and ordinary linear regression. 

The study found that the concentrations of strontium and carbonate ion (carbonate), in 

combination, could be used as a reliable marker of imported drywall. Portable XRF and 

FTIR spectrometry instruments were used to measure strontium and carbonate, 

respectively. The portable XRF instruments were used to make measurements in each 

home, and the FTIR, although portable, was used in the laboratory. These data were 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 100 of 128 
used to determine which study homes contained imported drywall, how much it 

contained and where it was located. 

Imported drywall was found to be present in 92.7% of the complaint homes and not 

present in any of the non-complaint homes. The differences are clear but the results 

could be affected by a bias in the process leading to the complaint classification, e, g., if 

an individual knew they have imported drywall they may be more likely to file a complaint 

than someone that does not have imported drywall in their home. 

Corrosion was found to be greater in the complaint houses than in the non-complaint 

houses (p<0.01). The corrosion effect was significant both when quantitative measures 

(corrosion coupons) were used as measures of corrosion as well as when the 

observations of corrosion on ground wires by trained technicians onsite were used. The 

region where the house was located was associated with corrosion rate in certain 

applications. Specifically, the east coast of Florida homes had the highest corrosion 

rates when corrosion coupons from the air handlers were compared and used as a 

measure of corrosion rate. When other corrosion coupons, were used, e.g., from the 

bedrooms or living rooms in the analysis there was no regional effect. This finding 

demonstrates how sensitive these measurements may be to micro environmental effects 

and indicates caution must be exercised in interpreting data from limited measurements 

to ensure unwitting bias is not introduced. Outdoor corrosion rates were not correlated 

with indoor corrosion rates. 

Short-term, average air exchange rates were measured in each home using carbon 

dioxide as a tracer gas. The results of these studies indicated that the air exchange rates 

for complaint and non-complaint homes were similar (p=0.09). The tracer gas study also 

showed that the houses in the sample were relatively tightly sealed with a median shortterm average air exchange rate of 0.19 ACH (range 0.05 – 0.8). 

Several gases/vapors that were measured in this study were present at different 

concentrations in homes with and without imported drywall (as determined by CPSC 

status or the XRF/FTIR pair of markers). These gases/vapors were also investigated for 

their potential to contribute to corrosion or malodor. These gases/vapors include 

hydrogen sulfide, carbon disulfide, and potentially inorganic and organic acids. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 101 of 128 
In homes that were both non-complaint and did not have the XRF/FTIR marker of 

imported drywall H2S concentration ranged from background (0.33 ppb) to levels below 

the minimum reported odor threshold (0.5 ppb) for samples collected with the two week 

passive samplers. In contrast, approximately 67% of the measurements from homes that 

were either complaint or had the XRF/FTIR marker of imported drywall contained twoweek average concentrations of H2S that exceeded the maximum reported background 

concentration level. Approximately one-half of the measured H2S levels in complaint or 

imported drywall homes were greater than the minimum reported odor threshold. In 

multivariate analyses, hydrogen sulfide concentration was found to be positively and 

significantly associated with silver and copper corrosion rates (p=0.01). 

Carbon disulfide concentrations differed between complaint and non-complaint homes, 

with median concentrations of 2.2 and 0.74 μg/m3

, respectively. The difference however, 

is not statistically significant (p=0.07) although this analysis is limited due to the small 

sample size. Carbon disulfide concentration was also not significant when evaluated as 

a predictor of corrosion rates in multivariate modeling while controlling for several 

potential confounding variables (p=0.29). Carbon disulfide concentrations were also not 

significantly correlated with hydrogen sulfide concentrations (p=0.22). 

Organic acids were detected at a mean concentration of 11 ppb in complaint homes and 

7 ppb in non-complaint homes. The differences were not statistically significant (p=0.5). 

Organic acid concentrations were also not significantly correlated with corrosion rates. 

Concentrations of aldehydes in the indoor air of both complaint and non-complaint 

homes did not differ significantly but both were generally greater than levels reported in 

the scientific literature for residences in various areas of the United States. For example, 

the average concentration of formaldehyde (active sampling) in complaint and noncomplaint homes was 53 μg/m3

 while mean values reported in studies of homes in large 

cities like New York City; Houston; Elizabeth, NJ; and Los Angeles, CA, ranged from 

18 and 22 μg/m3

. Concentrations of other aldehydes in indoor air of homes in the 

present study were also generally two to four times greater than the corresponding 

levels reported for these cities. Most (78%) of the homes in the present study were 

constructed after 2005, thus variation in concentrations of aldehydes in indoor air 

compared to previous studies may be a function of age of construction and related 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 102 of 128 
factors such as air exchange rate. For example, Hodgson et al. (2000) evaluated air 

exchange rates, formaldehyde, and volatile organic compound (VOC) concentrations in 

new manufactured houses and site built houses. The average indoor-outdoor 

concentrations for these fourteen residences was 49 μg/m3

 (40 ppb) with a median of 47 

μg/m3 (38 ppb) with a range from 9 – 66 μg/m3 (7 – 54 ppb). The average air exchange 

rate was 0.40 per hour with a median of 0.38 per hour. The Hodgson et al. (2000) study 

also demonstrated that formaldehyde is emitted by materials in a new house at fairly 

constant rates over the period they studied, which was nine months. The levels of 

formaldehyde measured in their study of newly constructed houses are quite consistent 

with what was measured in both the complaint and non-complaint houses in this study, 

even though the air exchange rates are higher in the Hodgson study (Hodgson et al. 

2000). 

Multivariate modeling was used to assess the significance of formaldehyde 

concentration as a predictor of corrosion rates. In the mixed models which compare 

room-specific formaldehyde concentrations and corrosion rates, formaldehyde was a 

significant predictor of silver corrosion rates but not copper (p=0.01; p=.10) (see 

additional discussion of formaldehyde and corrosion rates in Section 6.5.3). 

Samples for VOCs were collected at 31 of the 51 homes using SUMMA canisters and 

analyzed by GC/MS. Five of the 31 homes were non-complaint, the remainder were 

complaint homes. Several VOCs show elevated concentrations in complaint homes 

compared to non-complaint homes. Statistical comparisons are currently limited due to 

the small sample size of non-complaint homes with VOC samples (n=5). VOCs were not 

significantly associated with corrosion rates. 

6.2 SOURCE MARKERS 

6.2.1 Markers of imported drywall 

Laboratory-based testing of drywall samples of known origin was used to determine the 

utility of using real-time instruments for identifying sensitive and specific markers of 

imported drywall. Portable FTIR and XRF analyzers were used to quantify carbonate 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 103 of 128 
and strontium concentrations, respectively. A comparison of strontium and carbonate 

levels was previously presented in Section 5 (Figure 5.1 reproduced here as Figure 6.1). 

Strontium (ppm) - XRF

0 1000 2000 3000 4000 5000

Calcium Carbonate (absorbance) - FTIR

0

2

4

6

8

10

12

14

16

Imported

Domestic - Mined

Domestic - Synthetic

Domestic - Unknown

Blend

(Synthetic + Mined)

Figure 6.1 Comparison of Cored Drywall Samples of Known Origin and Analyzed in a 

Laboratory Setting for Strontium Concentrations (ppm) Measured by XRF and 

Carbonate (Absorbance) Measured using FTIR 

The results demonstrate that using elevated strontium concentrations alone may be a 

sensitive marker of imported drywall but not perfectly specific; there were two examples 

of domestic samples with high strontium concentrations. The analysis of known samples 

also indicates that carbonate alone may be sufficient to identify imported drywall. 

However, results from the 51 home field study indicate that there are many instances 

where a sample had elevated carbonate but not elevated strontium concentrations 

(Figure 5.2). When carbonate levels are considered in conjunction with strontium 

concentrations, the results demonstrate that a good indicator of imported drywall is a 

sample with both elevated strontium and elevated carbonate. Using both FTIR and XRF 

measurements of carbonate and strontium, respectively, was therefore determined to be 

the most sensitive and specific marker of imported drywall. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 104 of 128 
6.2.2 Evaluation of Portable XRF as a Field Screening Tool for Source 

Identification 

Portable XRF has been suggested as a useful tool for field identification of imported 

drywall, using elevated strontium concentrations as a marker. As the previously 

described lab analysis of core samples collected from homes demonstrates, imported 

drywall has elevated concentrations of strontium (greater than 1,200 ppm) compared to 

domestic samples. However, XRF analysis in the field can be significantly impacted by 

various surface materials. When drywall is measured in situ, the paint and any other of 

the myriad surface coatings that could be applied to walls have a muting effect on the 

strontium concentrations because the strontium is located at depth. 

Results from a pilot study in a complaint home indicated that elevated strontium 

concentrations measured via XRF in situ may still be a useful indicator of imported 

drywall. The apparent ability of strontium concentrations to act as a differentiator is 

demonstrated in Figure 6.2, which shows one wall in the pilot home that appears 

homogeneous in texture and finish (Figure 6.2a). In Figure 6.2b, strontium 

concentrations from XRF are overlayed on the picture of the wall and indicate that 

elevated levels of strontium were detected on the lower half of the wall. The presence of 

imported drywall on the lower half of the wall was confirmed on another wall in the room. 

Therefore, in situ measurements of strontium via XRF were able to be used to identify 

where domestic and imported drywall were located in an otherwise uniformly painted 

wall. However, as discussed below there are significant limitations on using this 

technique as an absolute indicator. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 105 of 128 
Figure 6.2 Picture of One Wall from a Complaint Home (a) and Same Wall with Strontium 

Concentrations Measured using XRF through Paint (b) demonstrating two Different 

Drywall Boards in an Otherwise Uniformly Painted Wall 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 106 of 128 
During the 51 home study, at each location where a sample was cored from the wall for 

laboratory analysis of the core sample, a co-located measurement using XRF was taken 

in situ, through the paint to allow for an assessment of the utility of portable XRF as a 

field tool. A point by point comparison is presented in Figure 6.3. The laboratory and 

field-based measurements show strong agreement, in general. However, there is no 

clear strontium concentration measured through the paint that could be reliably used to 

differentiate drywall with true elevated strontium (i.e., many false negatives). The false 

negatives likely occur on locations in the home that have drywall with thick layers of 

paint and/or plaster. 

Strontium (ppm) - Field Data

0 1000 2000 3000 4000 5000 6000

Strontium (ppm) - Lab Data

0

1000

2000

3000

4000

5000

6000

1:1 

Figure 6.3 Comparison of Strontium Concentrations of Co-located Samples Measured in the 

Field through Paint and/or Plaster, and Samples Measured of the Drywall Core in a 

Controlled Laboratory Setting 

To further refine the analysis presented in Figure 6.3 and reduce the misclassification 

due to some walls having thick coats of paint and/or plaster, we analyzed the percent of 

XRF in situ samples >600 ppm (half of the 1,200 ppm value used as the cut-off in 

controlled laboratory analysis). This marker was created as a means of attempting to 

obtain an overall characterization of the home in light of the evidence that some samples 

may have muted strontium concentration due to wall coatings. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 107 of 128 
Results comparing the percent of in situ measurements >600 ppm strontium against 

house status as determined by laboratory-based analysis of core samples (i.e., no paint 

or plaster) are presented in Figure 6.4. These results, combined with the information 

presented above, suggest that while in situ measurements using XRF may not be a 

absolute predictor of an individual drywall measurement being from imported or 

domestic material (due to the potential for false negatives), the house as a whole can be 

reasonably well characterized using the percent of XRF samples with strontium greater 

than 600 ppm. 

House Status by Lab-Based FTIR/XRF

Complaint Non-complaint

Percent of in situ measurements 

>600 ppm strontium

0%

20%

40%

60%

80%

100%

Figure 6.4 Comparison of the Percent of Situ Samples >600 ppm Strontium and Home Status 

Determined Using the FTIR/XRF Marker 

6.3 INDOOR AIR QUALITY 

6.3.1 Concentrations of Gases 

The levels of several gases measured in this investigation are of note because of (i) 

differences observed between homes with and without imported drywall (based on 

CPSC status or the XRF/FTIR pair of markers), (ii) their potential to contribute to 

corrosion or malodor, and (iii) their absolute levels. These gases which include hydrogen 

sulfide, carbon disulfide, inorganic and organic acids, and formaldehyde are discussed in 

this section relative to levels reported in other exposure studies and related benchmarks. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 108 of 128 
A summary of concentrations reported in the literature for gases common to this 

investigation and relevant comparison studies is tabulated in Appendix A. 

Two-week average concentrations of hydrogen sulfide in indoor air of complaint and 

non-complaint homes ranged from non-detect (<0.7 μg/m3

) to 3 μg/m3. Few published 

studies of indoor air quality in homes report measurements of hydrogen sulfide and other 

reduced sulfur gases, especially with the same degree of sensitivity as the present 

study. For example, Inserra et al. (2002) reported that 91% of 30-min average H2S levels 

inside of homes in a community impacted by point sources of H2S were less than the 

method detection limit of 30 ppb (Inserra et al. 2002). All of the H2S levels in the present 

study were well below 30 ppb, yet the information available from the study by Inserra et 

al. does not allow any further comparison to be made. Concentrations of H2S in ambient 

air as a result of emissions from natural sources have been estimated to range from 

0.11 to 0.33 ppb (EPA 1993 as cited in ATSDR 2006). Similarly, the World Health 

Organization reports that H2S levels in outdoor air are generally less than 0.1 ppb (WHO 

1981 as cited in ATSDR 2006). With a minimum reported odor threshold of 0.5 ppb 

(Ruth 1986 as cited in ATSDR 2006), background concentrations of H2S in outdoor air 

are not expected to be detected by olfactory means (ATSDR 2006). H2S measured in 

homes that were both non-complaint and did not have the XRF/FTIR marker of imported 

drywall were in the range of background and below the minimum reported odor 

threshold. In contrast, approximately 66% of the measurements from homes that were 

either complaint or had the XRF/FTIR marker of imported drywall contained two-week 

average concentrations of H2S that exceeded the maximum reported background level 

of 0.33 ppb. Likewise, approximately one-half of the measured H2S levels in complaint or 

imported drywall homes were greater than the minimum reported odor threshold of 

0.5 ppb. 

With regard to carbon disulfide and additional reduced sulfur gases other than hydrogen 

sulfide, a search of the published literature did not identify measurements in residential 

indoor air. Among these gases, only carbon disulfide was found to differ between 

complaint and non-complaint homes in this investigation; median concentrations of 

2.2 and 0.74 μg/m3

, respectively. According to the ATSDR, most people can detect the 

burnt match odor characteristic of carbon disulfide at concentrations between 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 109 of 128 
62 and 310 μg/m3

 (ATSDR 2004). Thus, the concentrations of carbon disulfide 

measured in this study are below the reported odor threshold for this substance. 

Information on acid gas concentrations in homes that can be compared to results from 

the present study are available in a small number of published studies all of which were 

conducted in the northeastern United States. Formic acid, for example, was detected at 

a mean concentration of 11 ppb in complaint homes and 7 ppb in non-complaint homes. 

Reiss (Reiss et al. 1995) reported mean formic acid values of 9.8 ppb in the summer and 

17.8 ppb in the winter for homes in Massachusetts, and Zhang (Zhang et al. 1994) 

reported a mean of 8.8 ppb in New Jersey. Concentrations of other acids measured in 

complaint and non-complaint homes were also similar to background levels reported in 

the published literature. 

The indoor air levels of formaldehyde and other aldehydes were similar for complaint 

and non-complaint homes although generally greater than levels reported in the 

scientific literature for residences in various areas of the United States. For example, the 

average concentration of formaldehyde (active sampling) in complaint and noncomplaint homes was 53 μg/m3

 while mean values reported for homes in the TEACH 

(New York City and Los Angeles) and RIOPA (Houston, Los Angeles, and Elizabeth, NJ) 

studies were 18 and 22 μg/m3

, respectively (NUATRC 2000; Weisel et al. 2004). 

Concentrations of other aldehydes in indoor air of homes in the present study were also 

generally two to four times greater than the corresponding levels reported for the TEACH 

and RIOPA studies. Most (78%) of the homes in the present study were constructed 

after 2005, thus variation in concentrations of aldehydes in indoor air compared to 

previous studies may be a function of age of construction and related factors such as air 

exchange rate. For example, Hodgson et al. (2000) evaluated air exchange rates, 

formaldehyde, and VOC concentrations in new manufactured houses and site built 

houses. The average indoor-outdoor concentrations for those fourteen residences was 

49 μg/m3

 (40 ppb) with a median of 47 μg/m3 (38 ppb) with a range from 9 – 66 μg/m3 

(7 – 54 ppb). The average air exchange rate was 0.40 per hour with a median of 0.38 

per hour. The Hodgson et al. (2000) study also demonstrated that formaldehyde is 

emitted by materials in a new house at fairly constant rates over the period they studied, 

which was nine months. The levels of formaldehyde measured in their study of newly 

constructed houses are quite consistent with what was measured in both the complaint 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 110 of 128 
and non-complaint houses in this study, even though the air exchange rates are higher 

in the Hodgson study. 

Concentrations of VOCs in the indoor air of complaint homes were nominally greater 

than in non-complaint homes, although a statistical test of equality of the central 

tendency is limited by the modest sample size in each group. Nonetheless, the 

concentrations of VOCs found in homes of both groups were in the range of levels 

reported in the published scientific literature such as the TEACH (NUATRC 2009) and 

RIOPA (Weisel et al. 2004), and Hodgson et al. (2000) studies. For example, toluene 

concentrations averaged 29.15 μg/m3

 and 10.99 μg/m3 in complaint and non-complaint 

homes. In comparison, the average concentration in the TEACH and RIOPA studies 

were studies were 18.26 and 20.28 μg/m3

, respectively. In addition, the nominal 

differences between concentrations of VOCs for complaint and non-complaint homes 

was similar to the differences observed across homes and cities in the TEACH and 

RIOPA studies. For example, the average concentration of benzene in non-complaint 

homes was 1.06 μg/m3

 and 5.05 μg/m3 in complaint homes. In comparison, 

concentrations of benzene ranged from <0.4 μg/m3

 to 39 μg/m3 across homes in New 

York City and from 2.5 μg/m3

 to 5.3 μg/m3 between average levels in Los Angeles and 

New York City. A larger number of observations would be required to ascertain whether 

any true differences in VOC concentrations exist between homes with and without 

imported drywall. However, the available information suggests that concentrations of 

VOCs in both groups of homes are similar and typical of residential buildings. 

6.3.2 The Role of Air Exchange and Ventilation 

Home ventilation rate, measured in air changes per hour (ACH), is an important 

determinant of concentrations of gases in the indoor environment. Air exchange rates in 

residential buildings vary considerably based on the type of construction, seasonal 

variability in weather, and geographic region (ASHRAE 2005). 

Short-term air exchange rates were measured in each home during the sampling period. 

A short-term test only provides a snapshot of typical conditions in a home, yet the results 

can still provide useful insights if gross-level differences across homes existed. The 

median ventilation rate for all homes in the study was 0.19 (range 0.05 – 0.8), with no 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 111 of 128 
significant differences between complaint and non-complaint homes or across study 

region. 

Typical air exchange rates for residential buildings in North America range from a 

seasonal average of about 0.2 ACH for tightly constructed homes to upwards of 2 ACH 

for loosely constructed housing (ASHRAE 2005). Additional studies have shown that an 

ACH of approximately 0.4 to 0.5 is a reasonable estimate of average seasonal air 

exchange rate for residences (ASHRAE 2005; Ek et al. 1990; Grimsrud et al. 1982; 

Palmiter and Brown 1989; Parker et al. 1990). This suggests that the homes in this 

study, both complaint and non-complaint, are on the lower end of the distribution of 

typical air exchange rates found in North America. The lack of variability in air exchange 

rates from homes in this study (i.e., most on low end of typical range) may partly explain 

why air exchange rate, while known to be an important variable in determining indoor 

gas concentrations, was not a significant predictor of gas concentrations or corrosion in 

the regression analyses in this study. 

6.4 CORROSION 

6.4.1 Corrosion Classification Coupons 

Corrosion classification coupons were used as an integrated measure of effect. The 

levels of corrosion observed on the classification coupons represent the combined effect 

of all variables in the home, including both measured and unmeasured characteristics. 

The corrosion rates measured accounted for conditions in the home at the time of the 

indoor air sampling and allowed for a determination of effect to be seen even if the 

corrosion detected was due to a potentially un-quantifiable synergistic effect between 

low-level indoor air contaminants. 

The corrosion classification coupons deployed in the 51 homes in this study were 

comprised of two metal strips—one copper and one silver. Using two different metals 

allows for the potential to identify and/or rule-out the presence of airborne contaminants 

based on differential rates of corrosion between the two metals. For example, Table 6.1 

lists the material sensitivities of silver and copper to various corrosive agents. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 112 of 128 
Table 6.1 Material Sensitivities to Atmospheric Corrodants 

Corrodants Silver (Ag) Copper (Cu) 

CO2/CO3

2- L – 

NH3/NH4

+ M M 

NO2/NO3

- N M 

H2S H H 

SO2/SO4

2- L H 

HCl/Cl- M M 

RCOOH/COOH- L M 

O3 M M 

H = High sensitivity 

M = Moderate sensitivity 

L = Low sensitivity 

N = No sensitivity 

* Table reproduced from (Leygraf and Graedel 2000) Table 4.1. 

From this table we can infer that if the corrosion observed in the homes was due to SO2, 

then copper corrosion would be expected to be elevated compared to silver corrosion. 

As there was generally good agreement between copper and silver corrosion in the 

same homes, corrosive agents that act on silver and copper at differential rates (such as 

SO2) are unlikely to be the primary cause of effect in the study homes. Similarly, the 

information in Table 6.1 can be used to add further evidence that hydrogen sulfide is a 

primary corrosive agent in this study because both silver and copper are highly sensitive 

to H2S—a finding supported by field measurements which recorded high rates of 

corrosion for both metals observed in this study. 

6.4.2 Differences in Corrosion Rates by Location in a Home 

In general, co-located measurements of corrosion levels measured in rooms were 

moderately to highly correlated. Corrosion rates measured at the AHU supply vents was 

significantly greater than levels measured in the rooms. Atmospheric corrosion is 

dependent upon corrosive species contacting the metal surface, which is most 

commonly governed by the process of dry deposition where contact at the surface 

occurs via turbulent diffusion (Leygraf and Graedel 2000). The vertical flux (Φ) of a 

contaminant is dependent upon the concentration of the contaminant in air (C) and 

deposition velocity (Vdep), expressed in terms of flux units (m3

/h/m2): 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 113 of 128 
Φ = C*Vdep (Equation 6.1) 

Measured deposition velocities are typically much greater outdoors than indoors as a 

result of increased air movement (Leygraf and Graedel 2000). The increased corrosion 

rate observed at the AHU supply vent compared to the rooms may be explained, 

therefore, by the increased Vdep in the supply duct air stream due to increased volume of 

air passing the corrosion coupon (i.e., increased mass-transfer rates). 

6.4.3 Hydrogen Sulfide and Formaldehyde 

The results of the multivariate modeling (Section 5.3.8.3) indicate that both indoor 

formaldehyde and hydrogen sulfide concentrations were associated with silver and 

copper corrosion. Formaldehyde and its related acid (formic acid), can cause corrosion 

on copper and silver, with silver having a lower sensitivity to formic acid (Table 6.1) 

(Leygraf and Graedel 2000). 

Reduced sulfur gases in air, even at low concentrations, are able to initiate corrosion 

and disrupt the protective cuprous oxide layer that forms on copper thereby enabling 

other corrosive agents (i.e., formaldehyde, formic acid) to more readily act on the metal. 

While silver does not form an oxide layer in typical temperature ranges (Campbell and 

Thomas 1939; Graedel et al. 1985), synergistic effects have been seen between 

hydrogen sulfide and other airborne corrosive agents (Leygraf and Graedel 2000). 

The results from the field study support this hypothesis. The multivariate modeling 

results suggest that for silver corrosion there was an interactive effect between hydrogen 

sulfide and formaldehyde; the level of silver corrosion associated with formaldehyde was 

dependent upon the presence of hydrogen sulfide. This same interactive effect would be 

expected to be seen for copper but was not. One possible explanation relates to the 

mass increase rates for silver and copper. Copper and silver both have fast mass 

increase rates, but, in an experimental study, silver was shown to have a mass increase 

rate an order of magnitude faster than copper, showing mass responses within several 

minutes after hydrogen sulfide was introduced (Forslund et al. 1997). 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 114 of 128 
Further support of a multi-component model of corrosion can be found in the literature. A 

study of corrosion rates of copper by sulfurous gases determined a copper corrosion 

rate of 29 Angstrom per ppb of hydrogen sulfide per 30 days (0.04 Ǻ ppb 30d-1) (Graedel 

et al. 1983). Using the 75th percentile of hydrogen sulfide concentration in homes with 

imported drywall (0.79 ppb), the estimated rate of corrosion due to hydrogen sulfide 

would be 23 Ǻ per 30 days. In this study, the average rate of copper corrosion in homes 

with imported drywall was ~350 Ǻ 30d-1 in room air and 1400 Ǻ 30d-1 at the AHU air 

register, values that are 1 to 2 orders of magnitude greater than predicted based on 

hydrogen sulfide alone. Accounting for corrosion rates associated with another reduced 

sulfur, carbon disulfide, does not alter this finding; adding the 75th percentile air 

concentration for carbon disulfide (3.13 ppb) and the copper corrosion rates reported by 

Graedel et al (Graedel et al. 1983) does not significantly increase the copper corrosion 

rate (<0.1%). Therefore, the copper corrosion observed in homes may not be solely 

attributable to the concentration of reduced sulfur gases observed in this study. 

Additional work would be necessary to confirm this observation. 

6.5 HEALTH CONSIDERATIONS 

This assessment of indoor environmental quality in homes provides new information that 

is relevant to understanding the potential for human health effects to occur in association 

with the imported drywall that is under investigation by CPSC and its federal and state 

partners. The principal contrasts in exposure conditions between homes with and 

without imported drywall that were observed in this field study were: (1) levels of 

hydrogen sulfide and possibly carbon disulfide and selected hydrocarbons in indoor air; 

(2) rates of silver and copper corrosion; and (3) malodor. Factors such as formaldehyde 

concentrations and air exchange rate that were approximately equal between complaint 

and non-complaint homes but notable because of their magnitude and potential to 

influence health symptoms are considered in this discussion as well. 

Hydrogen sulfide is a flammable, colorless gas with a characteristic odor of rotten eggs 

that may cause irritation to the eyes, nose, or throat at low concentrations and can be 

poisonous at elevated concentrations (ATSDR 2006). Health-based benchmarks for 

hydrogen sulfide exposures in non-occupational settings have been recommended by 

ATSDR and EPA. The ATSDR minimum risk level (ATSDR 2008) of 20 ppb for 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 115 of 128 
inhalation exposure to hydrogen sulfide over an intermediate duration (more than 

14 days and less than a year) is based on the prevalence of damage to olfactory 

neurons observed in mice exposed to 10, 30 and 80 part per million of hydrogen sulfide 

for 6 hours per day, 7 days per week for 10 weeks reported by Brenneman et al. 

(Brenneman et al. 2000). ATSDR also recommends a minimum reporting limit (MRL) of 

70 ppb for acute exposure (duration of one to 14 days) based on suggestive evidence of 

bronchial obstruction among asthmatics exposed to 2 ppm hydrogen sulfide for 

30 minutes reported by Jappinen et al. (Jappinen et al. 1990). The EPA inhalation 

reference concentration (RfC) for hydrogen sulfide of 2 x 10-3 milligrams per cubic meter 

(1.4 ppb) was also derived from the Brenneman (2000) study of mice. Most of the twoweek average concentrations of hydrogen sulfide measured in complaint homes 

included in this study were below these health-based benchmarks. 

Concentrations of carbon disulfide and hydrocarbons measured in whole air samples 

collected with SUMMA canisters were nominally about 1.5 to 2 times greater in 

complaint homes than in non-complaint homes. As discussed in Section 6.2, the 

strength of conclusions about systematic differences in VOCs levels between complaint 

and non-complaint homes are constrained by the number of non-complaint homes (5) 

from which these types of samples were obtained. The MRL for carbon disulfide of 

300 ppb (936 μg/m3

) recommended by ATSDR is based upon reports of reduced motor 

nerve conduction velocity in humans after prolonged occupational exposure to the 

chemical (ATSDR 1996). The EPA derived the RfC for carbon disulfide of 700 μg/m3

from an observational study of workers in the viscose rayon industry (EPA 2002). With a 

maximum house-wide average concentration of 9.1 μg/m3

, the levels of carbon disulfide 

in complaint and non-complaint homes were well below the ATSDR and EPA healthbased benchmarks. Similar conclusions can be reached for hydrocarbons that were also 

assessed through the SUMMA canister sampling and analysis. For instance, the median 

concentration of n-hexane in complaint homes was 4.13 μg/m3

 compared to 0.95 μg/m3

in non-complaint homes, levels that are more than 500 times below the MRL of 

2,117 μg/m3

 and 150 times below RfC of 700 μg/m3. Moreover, the target organs and 

health endpoints from which MRLs and RfCs are derived typically differ across VOCs 

and differ from the symptoms reported by occupants of complaint homes such as 

respiratory irritation, headache, and eye irritation. Thus while effects of concurrent 

exposure to multiple VOCs are possible, the variety of health endpoints that form the 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 116 of 128 
basis of health-based benchmarks complicates an assessment of risk associated with 

cumulative exposure. Additional analysis would be needed to evaluate the potential for 

cumulative effects of these gases further. 

As described in Section 5.2.3, corrosion of silver and copper coupons was accelerated in 

complaint homes compared to non-complaint homes. The levels of hydrogen sulfide 

found in complaint homes may not be sufficient cause for the rate of corrosion observed 

in these buildings (see Section 5.3). The accelerated corrosion could be the product of 

synergistic effects of hydrogen sulfide with formic or acetic acid or other species that are 

ubiquitous in indoor environments, perhaps potentiated by dew points in the vicinity of 

ambient indoor temperatures as described in Section 5.3.8.1. The mixtures of corrosive 

species found in the air of these homes have not been studied in relation to health based 

considerations based upon a literature search completed by EH&E. Nevertheless, the 

acid gases found in these homes including hydrogen sulfide, nitrogen dioxide, acetic 

acid, and formic acid, are well known to be irritating to the eyes and respiratory tract 

(Klaassen et al. 1986; Lewis 2000) although typically at higher concentrations in air than 

were observed in this investigation. Hence, a close examination of the acid gas and 

health literature may be valuable for further evaluation of the health implications of the 

corrosion observed in these homes. 

Malodor perceived in indoor air is another distinct difference that was observed between 

the complaint and non-complaint homes included in this study. Hydrogen sulfide has a 

low odor threshold, was enriched in indoor air of complaint homes, and therefore could 

be responsible for contributing to the malodors in complaint homes (see Section 6.2). 

Symptoms of eye, nose, and throat irritation are often cited by occupants of polluted 

indoor environments (Cometto-Muñiz 2001; Molhave 2001). Studies conducted by 

Fanger (Fanger 201), and Molhave (Molhave et al. 1986) have shown that emissions 

associated with building materials, furnishings, and equipment contribute to the pollution 

and sensory load of the indoor environment. Liu et al. (Liu et al. 2007) found that people 

who had been exposed to moderate to strong odors from home renovations were 

approximately four times more likely to experience discomfort than those who had been 

exposed to emissions that generated “weak” odors. A paper by (Schiffman and Williams 

2005) cites three mechanisms by which odors may produce health symptoms. Although 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 117 of 128 
their paper focuses primarily on the impact of ambient odors on community health, it 

does provide a useful construct by which to consider the possible impact of malodors on 

occupants of homes containing suspect Chinese drywall. Schiffman and Williams (2005) 

describe these mechanisms as: 

• Mechanism One: Irritation, rather than the odor, causes the health symptoms. 

• Mechanism Two: Health symptoms occur at odorant concentrations that are not 

irritant. 

• Mechanism Three: A co-pollutant in an odorous mixture is responsible for the 

reported health symptoms. 

The first mechanism proposed details a direct association between symptoms and the 

compounds producing the malodors. In this case irritation, rather than the odor, is the 

cause of the health symptoms. The associated odor is not the cause, but rather serves 

as an exposure marker. Of interest is the fact that this mechanism is not dependent 

upon only one chemical being above its odorant threshold; irritation may be induced by a 

number of chemicals that each individually may be below the concentrations that cause 

irritation, but taken in aggregate may exceed the irritant threshold (Cometto-Muñiz et al. 

1999; Cometto-Muñiz et al. 1997). 

In the second mechanism it is postulated that health symptoms can occur from odors, 

even when the odorant is below the irritant threshold. Schiffman and Williams (2005) 

acknowledge that the mechanism responsible for health complaints in the absence of 

irritation is not well understood, however they cite several community-based studies in 

which low levels of hydrogen sulfide were associated with health complaints (Haahtela et 

al. 1992; Jaakkola et al. 1991; Jaakkola et al. 1990). 

The third mechanism acknowledges that the odorant is not the only source of pollutant 

or irritant that is in the indoor environment. Other co-pollutants may originate from the 

source of the odorant material, from other sources within the residence such as VOCs 

and formaldehyde from wood products or NO2 associated with gas stoves (Andersson et 

al. 1997; Hodgson et al. 2000), or be transported from outdoors such as ozone or 

vehicular pollutants . In this case the odorant may focus occupants’ attention on the 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 118 of 128 
indoor air and the irritant symptoms, but may only be a minor contributor to the health 

concerns that are really attributable to other materials present in the indoor environment. 

One additional effect of malodor is that occupants are aware of the status of a building 

with respect to construction with imported drywall. Knowledge of the drywall status of a 

building could bias beliefs about relationships between health symptoms and occupancy 

of that space. This type of bias is commonly described as dependent error in the 

vernacular of epidemiology (Rothman et al. 2008). Under this scenario, symptoms such 

as upper respiratory irritation experienced by occupants of complaint homes could be 

incorrectly ascribed to construction with imported drywall, as opposed to other factors. At 

least one well known respiratory irritant, formaldehyde, was found at elevated 

concentrations in the indoor air of both complaint and non-complaint homes. Yet, homes 

without the malodor do not have a history of health complaints with CPSC. The low air 

exchange rate in complaint and non-complaint homes could also be a factor in 

dependent error because of the potential for other common respiratory irritants to 

accumulate within these residences. Further research would be needed to evaluate the 

role of odor in reported health effects in greater detail. 

6.6 COMPARISON TO CHAMBER STUDIES 

Results of chamber studies of imported drywall reported to date are generally consistent 

with the observations made during the field investigation with some notable exceptions. 

Accelerated corrosion of copper evidenced by visual inspection and SEM/EDS was 

reported when clean copper tubing was stored with imported drywall (Unified 

Engineering Inc. 2009). Similarly, the rate of corrosion measured on both copper and 

silver test coupons during the field investigation was substantially and significantly 

greater in homes with imported drywall than in homes with domestic drywall (see Section 

5.2.3). The type of corrosion observed in the chamber studies also agrees with the 

results of the field investigation. Specifically, analysis of corrosion material in the 

chamber studies and the field investigation indicate production of Cu2S (and Ag2S in the 

field study coupons) rather than sulfates, chlorides or other common forms of copper 

corrosion. These results are consistent with sulfidation via H2S and carbonyl sulfide 

although only the former species was found at elevated levels in indoor air of homes with 

imported drywall (Graedel et al. 1983), whereas chamber studies have identified both 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 119 of 128 
H2S and carbonyl sulfide in headspace analysis (CAS 2009; EPA 2009; Unified 

Engineering Inc. 2009). 

In contrast to the agreement note here, some corrosive species reported to be released 

from imported drywall tested in chamber studies were not observed at elevated 

concentrations during the field investigation. For instance, carbonyl sulfide has been 

observed in some chamber tests (Unified Engineering Inc. 2009) but was not found in 

homes of this field investigation. The absence of carbonyl sulfide in samples obtained 

from homes could be explained by several reasons. First, carbonyl sulfide may have 

been present at concentrations below the method detection limit of the grab sampling 

procedure (see Table 4.2). Second, some species present in chamber studies may not 

be produced in the field because of differences in environmental conditions between the 

lab and actual homes. The chamber studies are typically performed at elevated 

temperatures (e.g., 37 °C, 98 °F), while the average indoor temperature of homes 

included in the present study was 25.5 °C (78 °F). Third, species evolved from imported 

drywall could be rapidly scavenged by sinks inside of homes that are not present in the 

chamber studies. For example, hydrogen sulfide and carbonyl sulfide are known to 

rapidly react with copper (Graedel et al. 1985), which could result in limited direct 

evidence of their presence within homes. Measurements of sulfur dioxide made during 

exploratory experiments conducted in EH&E’s laboratory also support this explanation. 

As shown in Figure 6.5, sulfur dioxide was measured at elevated concentrations in the 

air of a sealed and heated glass container that held imported drywall and water. Yet, no 

notable differences in sulfur dioxide concentrations compared to the control conditions 

were observed when a piece of clean copper tubing was also present inside the jar, 

although the copper tubing rapidly showed evidence of corrosion, thereby supporting the 

scavenging of the reactive gases from the air. Additional investigation is required to 

ascertain the reasons that fully explain differences between the field investigation and 

chambers studies that have been reported to date. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 120 of 128 
Sample Only

Heat (46 degree oC)

Water Present

Heat and Water

Heat, Water and Copper

SO2 (ppb)

0

20

40

60

80

100

120

Domestic

Import 1

Import 2

Figure 6.5 Sulfur Dioxide (SO2) Concentrations inside Small-volume Chamber Studies 

Comparing Two Imported and One Domestic Drywall Sample Under Varying 

Environmental Conditions. 

6.7 LIMITATIONS 

This study was designed to characterize the air quality in homes that had health and/or 

corrosion complaints suspected to be associated with certain types of drywall. This 

“suspect” drywall is believed to originate and be imported from the People’s Republic of 

China. However, at this time there is insufficient evidence to support or refute the 

assertion that all Chinese-origin or imported drywall exhibits the health or corrosive 

characteristics reported in complaint homes. 

The intent of this sampling and analysis program was to elucidate the relationships 

between suspect drywall and environmental conditions existing in the home that could 

be characterized by use of objective measurements such as the rate of corrosion on 

metal surfaces. A variety of sampling and inspectional techniques were utilized in this 

study. This study was designed as an in situ investigation in which the house was 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 121 of 128 
characterized in the “lived in” condition. (Certain exceptions to this “lived in” 

characterization, where the houses were unoccupied during the testing, are discussed in 

the body of the report.) So as to not possibly miss an important interaction effect, no 

attempt was made to restrict occupant activities, manipulate the mechanical systems or 

remove materials from the residence prior to, or during, sampling. Thirteen of the 51 

homes in this study were unoccupied during the sampling (12 complaint homes). 

Unoccupied homes represent a different environment than occupied homes and thus 

could potentially be an important factor when looking for associations between sources, 

the environment and effects. To examine the potential for occupancy status to impact 

the study findings, we compared several key parameters (hydrogen sulfide, 

formaldehyde, air exchange rate, dew point, temperature) by occupancy status and 

found that only temperature was significantly different across the two groups (similar 

results were observed when the analysis was restricted to comparing occupied status 

within complaint homes only). Additionally, consistent results were observed in all 

regression models when they were re-run controlling for occupancy status. 

Formaldehyde was observed to be a predictor of silver corrosion but this study cannot 

rule out the possibility that formaldehyde is a surrogate for some other agent. For 

example, formaldehyde is corrosive to some metals, although its related acid (formic 

acid) is known to be more corrosive. Similarly, formaldehyde concentrations were 

positively associated with indoor air temperature. Therefore, the effect of formaldehyde 

on corrosion could be a true effect, or formaldehyde could be a marker for formic acid, 

temperature or some other variable. 

The indoor environment of the complaint homes is complex, dynamic and in many ways 

challenging to characterize due to the low concentrations of the contaminants present 

and the highly reactive nature of many of the species of interest. It is also probable that 

there are important interactions between the materials emitted from the suspect drywall 

and airborne compounds present in the indoor environment that may be associated with 

other sources, as well as specific home characteristics, that could cause, or be a 

significant contributor to, the complaints reported. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 122 of 128 
7.0 CONCLUSIONS 

The objective of the in-home investigation was to characterize the indoor environment in 

representative complaint homes in detail, obtain air samples and other objective 

measurements that could be used for future risk assessments and examine homes for 

evidence of health stressors that could plausibly be related to drywall based on 

complaints and scientific information compiled by CPSC and EH&E. The following 

associations were observed based on the results of the 51-home study: 

• Study homes with imported drywall had elevated rates of objectively quantified 

corrosion 

CPSC complaint homes were found to have elevated rates of corrosion as 

measured objectively by metal coupon and visual inspection, compared to noncomplaint homes. This finding remained when house status was determined 

using an objective marker of imported drywall (FTIR/XRF). 

• Imported drywall found in these homes was associated with increased levels of 

hydrogen sulfide in indoor air 

Homes with imported drywall had significantly greater hydrogen sulfide 

concentrations compared to homes with domestic drywall. 

• Hydrogen sulfide concentrations in air were associated with higher dew points for 

complaint homes 

A positive association was observed between elevated dew points and hydrogen 

sulfide concentrations for homes with imported drywall. Hydrogen sulfide was 

present where the dew point reached typical room temperatures and 

condensation of water vapor would be expected. 

• Hydrogen sulfide and formaldehyde concentrations in indoor air were associated with 

corrosion rates 

Hydrogen sulfide was associated with corrosion rates in these study homes. For 

silver, a potential interactive effect was seen with formaldehyde; the effect of 

formaldehyde on corrosion rates was dependent upon the presence of hydrogen 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 123 of 128 
sulfide. Formaldehyde may be associated itself or may be a marker of some 

other factor associated with corrosion (e.g., formic acid). 

• Objective markers of imported drywall can be quantified using portable FTIR and 

XRF analyzers 

FTIR and XRF analyzers provide an additional metric for characterizing homes 

with imported drywall that can be used in conjunction with objectively measured 

estimates of corrosion rates and malodor. 

• Air exchange rates in the study homes were all on the low-end of typical air 

exchange rates in homes 

Both complaint and non-complaint homes were newly constructed homes with air 

exchange rates consistent with the low end of the distribution for North American 

housing stock (i.e., tightly constructed homes). These low air exchange rates 

may play an important role in the effect of gases and indoor environmental 

conditions on corrosion and possible exposures to indoor contaminants. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 124 of 128 
8.0 REFERENCES 

Andersson K, Bakke JV, Bjørseth O, Bornehag CG, Clausen G, Hongslo JK, Kjellman M, 

Kjærgaard S, Levy F, Mølhave L, Skerfving S and Sundell J. 1997. TVOC and 

Health in Non-industrial Indoor Environments, Report from a Nordic Scientific 

Consensus Meeting at Langholmen in Stockholm, 1996. Indoor Air. 7:78-91. 

ASHRAE. 2005. 2005 ASHRAE Handbook - Fundamentals [SI Edition]. Atlanta, GA: 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. 

ATSDR. 1996. Toxicological Profile for Carbon Disulfide. Washington, DC: Agency for 

Toxic Substances and Disease Registry. 

ATSDR. 2004. Medical Management Guidelines (MMGs) for Carbon Disulfide 

(CS2).Atlanta, GA: Agency for Toxic Substances and Disease Registry, Division 

of Toxicology. http://www.atsdr.cdc.gov/MHMI/mmg82.html 

ATSDR. 2006. Toxicological Profile for Hydrogen Sulfide. Washington, DC: Agency for 

Toxic Substances and Disease Registry. 

ATSDR. 2008. Minimal Risk Levels (MRLs). Washington, DC: Agency for Toxic 

Substances and Disease Registry. 

Brenneman KA, James RA, Gross EA and Dorman DC. 2000. Olfactory neuron loss in 

adult male CD rats following subchronic inhalation exposure to hydrogen sulfide. 

Toxicologic Pathology. 28(2):326-333. 

Burdack-Freitag A, Mayer F and Breuer K. 2008. Identification of odorous sulfur 

containing organic compounds in building products on gypsum basis. Indoor Air 

2008, 11th International Conference on Indoor Air Quality and Climate, 

Copenhagen, Denmark. August 17-22, 2008. 

Buzica D, Gerboles M and Plaisance H. 2008. The equivalence of diffusive samplers to 

reference methods for monitoring O3, benzene and NO2 in ambient air. Journal 

of Environmental Monitoring. 10(9):1052-1059. 

Campbell WE and Thomas UB. 1939. Tarnish studies: The electrolytic reduction method 

for the analysis of films on metal surfaces. Transactions of the Electrochemical 

Society. 76:303-328. 

CAS. 2009. Chromatogram from Gas Chromatography/Sulfur Chemiluminescence 

Detector (GC/SCD) Analysis of Chinese Drywall Chamber Sample. Personal 

Communication dated May 22, 2009. Simi Valley, CA: Columbia Analytical 

Services, Inc. 

Cocheo V, Boaretto C and Sacco P. 1996. High uptake rate radial diffusive sampler 

suitable for both solvent and thermal desorption. American Industrial Hygiene 

Association Journal. 57:897-904. 

Cometto-Muñiz JE. 2001. Physicochemical basis for odor and irritation potency of VOCs. 

Indoor Air Quality Handbook. J.D. Spengler, J.M. Samet and J.F. McCarthy, 

(Eds.). New York: McGraw-Hill. 

Cometto-Muñiz JE, Cain WS, Abraham MH and Gola JM. 1999. Chemosensory 

detectability of 1-butanol and 2-heptanone singly in binary mixtures. Physiology & 

Behavior. 67:269-276. 

Cometto-Muñiz JE, Cain WS and Hudnell HK. 1997. Agonistic sensory effects of 

airborne chemicals in mixtures: Odor, nasal pungency, and eye irritation. 

Perception and Psychophysics. 59:665-674. 

CPSC. 2009a. Drywall Information Center. October 5, 2009. 

http://www.cpsc.gov/info/drywall/. 

CPSC. 2009b. Drywall Information Center: Where Has Problem Drywall Been Reported?

October 5, 2009. http://www.cpsc.gov/info/drywall/where.html. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 125 of 128 
CPSC. 2009c. Investigation of Imported Drywall - Status Report (July). Washington, DC: 

Consumer Product Safety Commission. 

CTEH. 2007. Knauf Tianjin Plasterboard Evaluation (February 13, 2007). Little Rock, 

AR: Center for Toxicology and Environmental Health, L.L.C. 

Ek CW, Onisko SA and Gregg GO. 1990. Air Leakage Tests of Manufactured housing in 

the Northwest United States. Air Change Rate and Airtightness in Buildings, 

ASTM STP 1067. Sherman MH. Philadelphia, PA, USA: American Society for 

Testing and Materials. 152-164. 

ENVIRON. 2008. Indoor Air Results Relating to Chinese Drywall. Memorandum to 

Florida Department of Health dated December 22, 2008. Tampa, FL: ENVIRON 

International. 

EPA. 2002. Integrated Risk Information System (IRIS): Carbon disulfide (CASRN 75-15-

0). November 5, 2009. Washington, DC: U.S. Environmental Protection Agency. 

http://www.epa.gov/ncea/iris/subst/0217.htm. 

EPA. 2008. Quality Assurance Handbook for Air Pollution Measurement Systems 

Volume II Ambient Air Quality Monitoring Program. Research Triangle Park, NC: 

U.S. Environmental Protection Agency. 

EPA. 2009. Drywall Investigations: Additional Five Drywall Sample Analysis Summary 

Results. Memorandum dated August 27, 2009. Washington, DC: U.S. 

Environmental Protection Agency. 

EPA. 2009a. Drywall Sampling Analysis. Washington, DC: U.S. Environmental 

Protection Agency. 

Fanger PE. 201. Perceived air quality and ventilation requirements. In:. Indoor Air 

Quality Handbook. J.D. Spengler, J.M. Samet and J.F. McCarthy, (Eds.). New 

York: McGraw-Hill. 

Forslund M, Majoros J and Leygraf C. 1997. A sensor system for high resolution in situ

atmospheric corrosivity monitoring in field environments. Journal of the 

Electrochemical Society. 144(8):2637-2642. 

Graedel TE, Franey JP, Gualtieri GJ, Kammlott GW and Malim DL. 1985. On the 

mechanism of silver and copper sulfidation by atmospheric hydrogen sulfide and 

carbonyl sulfide. Corrosion Science. 25(12):1163-1180. 

Graedel TE, Franey JP and Kammlott GW. 1983. Corrosion of copper by atmospheric 

sulphurous gases. Corrosion Science. 23(11):1141-1152. 

Grimsrud DT, Modera MP and Sherman MH. 1982. A predictive air infiltration modellong-term field test validation, United States. 

Haahtela T, Marttila O, Vilkka V, Jäppinen P and Jaakkola JJ. 1992. The South Karelia 

air pollution study: Acute health effects of malodorous sulfur air pollutants 

released by a pulp mill. American Journal of Public Health. 82(4):603-605. 

Hodgson AT, Rudd AF, Beal D and Chandra S. 2000. Volatile organic compound 

concentrations and emission rates in new manufactured and site-built houses. 

Indoor Air. 10(3):178-192. 

Hyslop NP and White WH. 2009. Estimating precision using duplicate measurements. 

Journal of Air & Waste Management Association. 59:1032-1039. 

Inserra S, Phifer B, Pierson R and Campagna D. 2002. Community-based exposure 

estimate for hydrogen sulfide. Journal of Exposure Science and Environmental 

Epidemiology. 12(2):124-129. 

Jaakkola JJ, Paunio M, Virtanen M and Heinonen OP. 1991. Low-level air pollution and 

upper respiratory infections in children. American Journal of Public Health. 

81(8):1060-1063. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 126 of 128 
Jaakkola JJ, Vilkka V, Marttila O, Jäppinen P and Haahtela T. 1990. The South Karelia 

air pollution study. The effects of malodorous sulfur compounds from pulp mills 

on respiratory and other symptoms. American Review of Respiratory Disease. 

142(6):1344-1350. 

Jappinen P, Vilkka V, Marttila O and Haahtela T. 1990. Exposure to hydrogen sulphide 

and respiratory function. British Journal of Industrial Medicine. 47(12):824-828. 

Klaassen C, Amdur M and Doull J. 1986. Caserett and Doull's Toxicology: The Basic 

Science of Poisons, Third Edition. New York, NY: MacMillan Publishing 

Company. 

Lewis R. 2000. Sax's Dangerous Properties of Industrial Materials, Tenth Edition. 

Hoboken, NJ: John Wiley & Sons, Inc. 

Leygraf C and Graedel TE. 2000. Atmospheric Corrosion Hoboken, NJ: John Wiley & 

Sons, Inc. 

Liu H, Lam LT, Wang T, Hou C, Zeng Q, Feng L and Chen X. 2007. The Health Effects 

of Odor Emission from Domestic Renovation on Household Residents in Tianjin, 

China. Journal of Environmental Health. 3:46-50. 

Molhave L. 2001. Sensory irritation in humans caused by volatile organic compounds 

(VOCs) as indoor air pollutants: a summary of 12 exposure experiments. Indoor 

Air Quality Handbook. J.D. Spengler, J.M. Samet and J.F. McCarthy, (Eds.). New 

York: McGraw-Hill. 

Molhave L, Bach B and Pedersen OF. 1986. Human reactions to low concentrations of 

volatile organic compounds. Environment International. 12:167-175. 

NUATRC. 2000. Final Report: Air Toxics Exposures Among Teenagers in New York City 

and Los Angeles - A Columbia-Harvard Study (TEACH). Mickey Leland National 

Urban Air Toxics Research Center. Washington, DC: U.S. Environmental 

Protection Agency. 

Palmiter L and Brown I. 1989. Northwest Residential Infiltration Survey: Analysis and 

Results. Seattle, WA, USA: Ecotope, Inc. for Washington State Energy Office. 

Parker GB, McSorley M and Harris J. 1990. The Northwest Residential Infiltration 

Survey: A Field Study of Ventilation in New Homes in the Pacific Northwest. Air 

Change Rate and Airtightness in Buildings, ASTM STP 1067. Sherman MH: 

ASTM International. 93-103. 

Pellizzari ED, Smith DJ, Clayton CA, Michael LC and Quackenboss JJ. 2001. An 

assessment of the data quality for NHEXAS--Part I: Exposure to metals and 

volatile organic chemicals in Region 5. Journal of Exposure Analysis and 

Environmental Epidemiology. 11(2):140-154. 

Reiss R, Ryan PB, Tibbetts SJ and Koutrakis P. 1995. Measurement of organic acids, 

aldehydes, and ketones in residential environments and their relation to ozone. 

Journal of Air & Waste Management Association. 45(10):811-822. 

Rothman K, Greenland S and Lash T. 2008. Modern Epidemiology, Third Edition. New 

York, NY: Lippincott Williams & Wilkins. 

Schiffman SS and Williams CM. 2005. Science of odor as a potential health issue. 

Journal of Environmental Quality. 34:129-138. 

Sigma-Aldrich. 2006. Radiello® Manual. Bellefonte, PA: Sigma-Aldrich Co. 

Swaans W, Goelen E, De Fré R, Damen E, Van Avermaet P, Roekens E and Keppens 

V. 2007. Laboratory and field validation of a combined NO2-SO2 Radiello 

passive sampler. Journal of Environmental Monitoring. 9(11):1231-1240. 

Unified Engineering Inc. 2009. First Report of Florida Drywall Samples (Unified 

Engineering File No. 4050). Report to Florida Department of Health dated March 

17, 2009. Aurora, IL: Unified Engineering Inc. 

Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 127 of 128 
Final Report CPSC Drywall and Indoor Environmental Quality Assessment January 28, 2010 

Environmental Health & Engineering, Inc.16512 Page 128 of 128 

Weisel CP, Zhang J, Turpin BJ, Morandi MT, Colome S, Stock TH, Spektor DM, Korn L, 

Winer A, Alimokhtari S, Kwon J, Mohan K, Harrington R, Giovanetti R, Cui W, 

Afshar M, Maberti S and Shendell D. 2004. Relationship of Indoor, Outdoor and 

Personal Air (RIOPA) study: study design, methods and quality 

assurance/control results. Journal of Exposure Analysis and Environmental 

Epidemiology. 15(2):123-137. 

WHO. 2000. Environmental Health Criteria 214: Human Exposure Assessment, 

International Program on Chemical Safety. Geneva: World Health Organization. 

Zhang J, Wilson WE and Lioy PJ. 1994. Sources of organic acids in indoor air: a field 

study. Journal of Exposure Analysis and Environmental Epidemiology. 4(1):25-

47. 
APPENDIX A 

SUMMARY DATA TABLES 
SUMMARY DATA TABLES 

Table A.1 Summary of Analytical Laboratory Quality Assurance Flags 

Laboratory Quality Assurance Flags** 

Sample Group 

Total Number of 

Measurements* Receiving 

Laboratory 

Blank 

Laboratory 

Duplicate 

Laboratory 

Spike 

(Standard) La

Acids (inorganic) 1,758 0 0 0 0 Acids (organic) 1,180 0 0 0 0 Active aldehydes 3,552 0 0 0 0 Reduced sulfur 5,080 460 0 0 0 H2S passive 307 58 0 2 0 HF passive 302 58 0 0 0 NO2 passive 302 162 0 0 0 O3 passive 303 58 0 4 0 SO2 passive 302 0 0 0 0 Passive aldehydes 2,754 522 0 0 34 VOCs 11,749 0 0 0 8 Totals 27,589 1,318 0 6 42 H2S hydrogen sulfide 

HF hydrogen fluoride NO2 nitrogen dioxide 

O3 ozone 

SO2 sulfur dioxide 

VOC volatile organic compound * Data points considered in the analysis, including samples, duplicates, field blanks, and shipping blanks ** Number of measurements with one or more laboratory quality assurance flags divided by the total number of measurements. 
Table A.2 Summary of Precision Estimates for Air Samples, Corrosion, and Drywall Measurements 

Compound Sample Group 

Sample 

Matrix N* 

Precision 

Estimate (%)** 

Hydrofluoric acid Acids (inorganic) Air 5 4.4 

Acetic acid Acids (organic) Air 47 5.9 

Formic acid Acids (organic) Air 23 8.5 

2,5-Dimethylbenzaldehyde Active aldehyde Air 1 10 

Acetaldehyde Active aldehyde Air 48 5.7 

Benzaldehyde Active aldehyde Air 48 14.4 

Butyraldehyde Active aldehyde Air 46 13.7 

Formaldehyde Active aldehyde Air 48 10 

Isovaleraldehyde Active aldehyde Air 32 9.2 

n-Hexaldehyde Active aldehyde Air 48 8.7 

Propionaldehyde Active aldehyde Air 45 10 

Valeraldehyde Active aldehyde Air 48 9.9 

Hydrogen sulfide (H2S) H2S Passive Air 28 12.5 

Nitrogen dioxide (NO2) NO2 Passive Air 48 18.5 

Ozone (O3) O3 Passive Air 1 6.7 

Acetaldehyde Passive aldehyde Air 47 9.2 

Acrolein Passive aldehyde Air 32 5.9 

Benzaldehyde Passive aldehyde Air 51 8 

Butanal (*) Passive aldehyde Air 48 5.9 

Formaldehyde Passive aldehyde Air 51 3.9 

Hexanal Passive aldehyde Air 51 3.5 

Pentanal Passive aldehyde Air 6 17.3 

Propanal Passive aldehyde Air 51 7.4 

Carbon disulfide Reduced sulfur Air 38 7.2 

1,1,1-Trichloroethane VOC Air 3 8.8 

1,1,2-Trichlorotrifluoroethane VOC Air 2 3.7 

1,1-Dichloroethene VOC Air 26 5.6 

1,2,4-Trimethylbenzene VOC Air 1 1.7 

1,2-Dichlorobenzene VOC Air 26 6 

1,2-Dichloroethane VOC Air 1 4.9 

1,2-Dichloropropane VOC Air 24 27 

1,3,5-Trimethylbenzene VOC Air 2 13.9 

1,3-Butadiene VOC Air 20 6.2 

1,4-Dichlorobenzene VOC Air 6 11.8 

1,4-Dioxane VOC Air 13 10.9 

2-Butanone (MEK) VOC Air 1 5.1 

2-Hexanone VOC Air 27 23.6 

2-Propanol (isopropyl alcohol) VOC Air 18 18.4 

4-Ethyltoluene VOC Air 28 33.9 

4-Methyl-2-pentanone VOC Air 20 6.9 

Acetone VOC Air 20 10.1 

Acetonitrile VOC Air 27 19 

Acrolein VOC Air 7 16.3 

Acrylonitrile VOC Air 28 24.4 

α-Pinene VOC Air 1 0 

Benzene VOC Air 28 33.9 

Benzyl Chloride VOC Air 28 33.1 

Bromodichloromethane VOC Air 1 5.2 

Bromoform VOC Air 11 5.8 

Appendix A–2 
Appendix A–3 

Table A.2 Continued 

Compound Sample Group 

Sample 

Matrix N* 

Precision 

Estimate (%)** 

Bromomethane VOC Air 2 3.7 

Carbon Disulfide VOC Air 6 7.7 

Carbon Tetrachloride VOC Air 14 6.1 

Chloroform VOC Air 27 7 

Chloromethane VOC Air 27 17.5 

cis-1,3-Dichloropropene VOC Air 26 26.4 

Cumene VOC Air 3 0.6 

Cyclohexane VOC Air 6 4.1 

Dibromochloromethane VOC Air 19 14.1 

Dichlorodifluoromethane (CFC 12) VOC Air 5 8 

d-Limonene VOC Air 27 14.3 

Ethanol VOC Air 28 35.9 

Ethyl acetate VOC Air 28 33.9 

Ethylbenzene VOC Air 25 24.9 

m,p-Xylenes VOC Air 24 6.9 

Methyl methacrylate VOC Air 28 33 

Methyl tert-Butyl Ether VOC Air 1 0 

Methylene chloride VOC Air 2 5.3 

Naphthalene VOC Air 6 2.4 

n-Butyl acetate VOC Air 20 27.3 

n-Heptane VOC Air 25 13.8 

n-Hexane VOC Air 25 25 

n-Nonane VOC Air 24 5.8 

n-Octane VOC Air 24 24.9 

n-Propylbenzene VOC Air 24 16.2 

o-Xylene VOC Air 17 5.6 

Propene VOC Air 25 6.9 

Styrene VOC Air 22 28 

Tetrachloroethene VOC Air 26 6.2 

Tetrahydrofuran (THF) VOC Air 15 12.1 

Toluene VOC Air 17 16.5 

trans-1,2-Dichloroethene VOC Air 28 32.7 

trans-1,3-Dichloropropene VOC Air 2 7.8 

Trichloroethene VOC Air 3 0 

Trichlorofluoromethane VOC Air 8 15.8 

Vinyl acetate VOC Air 27 8.5 

Vinyl chloride VOC Air 2 23.4 

Copper sulfide Corrosion Corrosion 1 3.6 

Silver silfide Corrosion Corrosion 10 28.1 

Carbonate Drywall (FTIR Lab) Drywall 98 13.8 

Strontium Drywall (XRF Field) Drywall 810 12.3 

Strontium Drywall (XRF Lab) Drywall 111 3.4 

VOC volatile organic compound 

* number of primary sample and duplicate pairs above the reporting limit. 

** root mean square of the scaled relative differences between pairs of duplicate samples 
Table A.3 Summary Statistics for Corrosion Rates (Angstrom/30 days) in Indoor and Outdoor Air, by House 

Cu2S Ag2S 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 2 331.5 (445.0) 16.0 932.0 (1102.0) 601.0 

 2 FL Non-complaint 2 16.0 (16.0) 16.0 290.5 (381.0) 253.0 

 3 FL Complaint 2 255.5 (304.0) 16.0 531.0 (581.0) 401.0 

 4 FL Complaint 2 16.0 (16.0) 16.0 555.5 (748.0) 140.0 

 5 FL Non-complaint 3 16.0 (16.0) 16.0 95.7 (112.0) 246.0 

 6 FL Complaint 2 16.0 (16.0) 16.0 512.0 (563.0) 321.0 

 7 FL Complaint 3 591.0 (752.0) 16.0 1082.0 (1684.0) 64.0 

 8 FL Non-complaint 2 16.0 (16.0) 16.0 168.0 (172.0) 182.0 

 9 FL Complaint 3 260.7 (750.0) 16.0 446.3 (475.0) 203.0 

10 FL Complaint 2 273.5 (531.0) 462.0 514.0 (727.0) 216.0 

11 FL Complaint 3 627.3 (1221.0) 16.0 908.3 (1162.0) 464.0 

12 FL Complaint 2 332.0 (377.0) 16.0 1658.0 (2602.0) 186.0 

13 FL Complaint 3 529.0 (577.0) 16.0 775.3 (935.0) 187.0 

14 FL Complaint 3 337.3 (400.0) 2687.0 878.7 (1253.0) 371.0 

15 FL Complaint 2 268.5 (301.0) 0.0 463.0 (599.0) 0.0 

16 FL Complaint 3 446.3 (531.0) 16.0 914.0 (1112.0) 45.0 

17 FL Non-complaint 2 52.0 (88.0) 556.0 195.0 (230.0) 251.0 

18 FL Complaint 3 16.0 (16.0) 602.0 171.3 (309.0) 253.0 

19 FL Complaint 3 669.7 (866.0) 462.0 1061.0 (2066.0) 281.0 

20 FL Complaint 3 478.3 (512.0) 734.0 815.3 (1223.0) 200.0 

21 FL Complaint 3 924.7 (1561.0) 750.0 1054.3 (1317.0) 345.0 

22 FL Non-complaint 3 16.0 (16.0) 2473.0 291.3 (410.0) 518.0 

23 FL Complaint 3 1231.3 (2204.0) 4845.0 1165.3 (1497.0) 643.0 

24 FL Complaint 3 130.7 (191.0) 16.0 593.7 (745.0) 262.0 

25 FL Complaint 3 16.0 (16.0) 16.0 327.7 (441.0) 401.0 

26 FL Complaint 3 262.0 (346.0) 16.0 679.7 (727.0) 496.0 

27 FL Complaint 3 321.3 (762.0) 16.0 1180.0 (1511.0) 626.0 

28 FL Complaint 3 243.0 (294.0) 16.0 1434.0 (1777.0) 468.0 

29 LA Complaint 3 207.0 (589.0) 16.0 956.7 (1381.0) 367.0 

30 LA Complaint 3 363.3 (506.0) 16.0 751.0 (962.0) 401.0 

31 LA Complaint 3 126.0 (346.0) 16.0 996.3 (1209.0) 345.0 

32 LA Complaint 3 243.3 (416.0) 16.0 2014.3 (2288.0) 338.0 

33 LA Non-complaint 3 16.0 (16.0) 16.0 145.3 (164.0) 432.0 

34 LA Complaint 3 216.3 (334.0) 16.0 483.3 (579.0) 253.0 

35 LA Non-complaint 3 16.0 (16.0) 16.0 269.7 (285.0) 401.0 

36 LA Complaint 3 1225.0 (1873.0) 16.0 4446.3 (7767.0) 413.0 

37 LA Complaint 3 16.0 (16.0) 16.0 435.0 (478.0) 722.0 

38 LA Complaint 3 331.7 (779.0) 16.0 943.7 (1844.0) 641.0 

39 MS Complaint 3 87.7 (231.0) 16.0 735.7 (877.0) 367.0 

40 MS Complaint 3 122.0 (203.0) 16.0 1213.3 (2165.0) 134.0 

41 VA Complaint 3 16.0 (16.0) 16.0 315.3 (412.0) 432.0 

42 VA Non-complaint 3 16.0 (16.0) 16.0 166.3 (268.0) 352.0 

43 VA Complaint 3 239.3 (686.0) 16.0 1366.3 (2405.0) 235.0 

44 VA Complaint 3 16.0 (16.0) 16.0 208.7 (248.0) 669.0 

45 VA Complaint 3 349.7 (462.0) 16.0 671.3 (820.0) 518.0 

46 VA Non-complaint 3 16.0 (16.0) 16.0 157.0 (194.0) 345.0 

47 VA Complaint 3 90.3 (239.0) 16.0 1157.0 (1924.0) 200.0 

48 VA Complaint 3 156.0 (241.0) 16.0 615.0 (857.0) 496.0 

49 AL Complaint 3 76.0 (196.0) 16.0 451.0 (529.0) 90.0 

50 AL Complaint 2 106.0 (196.0) 16.0 403.5 (601.0) 104.0 

51 AL Non-complaint 3 16.0 (16.0) 16.0 113.3 (158.0) 156.0 

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–4 
Table A.4 Summary Statistics for Aldehyde Concentrations (μg/m3

) in Indoor and Outdoor Air, by House 

Acetaldehyde Benzaldehyde Butyraldehyde Crotonaldehyde 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 25.7 (26.7) 1.6 5.2 (5.5) 0.5 5.3 (5.5) 0.5 0.5 (0.5) 0.5

 2 FL Non-complaint 3 40.7 (42.0) 1.1 7.5 (7.7) 0.5 6.2 (6.5) 0.5 0.5 (0.5) 0.5

 3 FL Complaint 3 14.7 (29.8) 0.6 3.7 (8.0) 0.6 3.6 (7.6) 0.6 0.5 (0.5) 0.6

 4 FL Complaint 3 54.9 (59.6) 1.9 4.5 (4.7) 0.7 2.7 (3.0) 0.7 0.5 (0.5) 0.7

 5 FL Non-complaint 3 22.2 (24.0) 1.8 6.2 (7.0) 0.7 4.1 (4.4) 0.7 0.5 (0.5) 0.7

 6 FL Complaint 3 29.2 (30.0) 1.5 2.7 (3.2) 0.5 4.7 (5.0) 0.5 0.5 (0.5) 0.5

 7 FL Complaint 3 31.1 (33.0) 1.4 17.0 (19.0) 1.3 4.0 (4.4) 0.5 0.5 (0.6) 0.5

 8 FL Non-complaint 3 24.5 (25.5) 1.6 4.3 (4.4) 0.6 1.6 (1.8) 0.6 0.5 (0.5) 0.6

 9 FL Complaint 3 30.0 (31.0) 1.6 4.9 (5.0) 0.5 6.0 (6.4) 0.5 0.5 (0.5) 0.5

10 FL Complaint 3 50.8 (53.0) 1.6 3.9 (4.5) 0.5 3.4 (3.7) 0.5 0.5 (0.5) 0.5

11 FL Complaint 3 14.3 (15.0) 1.4 6.4 (6.6) 0.5 1.7 (1.7) 0.5 0.5 (0.5) 0.5

12 FL Complaint 3 31.1 (31.2) 44.4 6.9 (7.2) 0.5 6.2 (6.5) 0.5 0.5 (0.5) 0.5

13 FL Complaint 3 43.0 (44.0) 0.5 9.8 (10.0) 0.5 6.1 (6.3) 0.5 0.5 (0.5) 0.5

14 FL Complaint 3 24.0 (24.0) 0.5 3.4 (3.8) 0.5 2.7 (4.0) 0.5 0.5 (0.5) 0.5

15 FL Complaint 3 18.2 (20.0) 1.8 4.9 (5.3) 0.5 2.6 (4.3) 0.5 2.2 (5.7) 0.5

16 FL Complaint 3 138.3 (140.0) 1.7 10.9 (12.0) 0.5 4.8 (5.0) 0.5 0.5 (0.5) 0.5

17 FL Non-complaint 3 50.2 (52.0) 1.7 6.9 (7.1) 0.5 8.5 (8.7) 0.5 0.5 (0.5) 0.5

18 FL Complaint 3 52.5 (54.1) 1.9 11.4 (13.0) 0.5 8.4 (9.7) 0.5 0.5 (0.5) 0.5

19 FL Complaint 3 26.3 (27.0) 1.3 4.9 (5.2) 0.5 4.3 (5.2) 0.5 0.5 (0.5) 0.5

20 FL Complaint 3 28.1 (29.9) 1.4 9.0 (10.0) 0.5 6.5 (6.8) 0.5 0.5 (0.5) 0.5

21 FL Complaint 3 50.5 (54.0) 0.5 5.7 (6.2) 0.5 4.4 (6.2) 0.5 0.5 (0.5) 0.5

22 FL Non-complaint 3 52.5 (54.3) 1.2 9.3 (10.0) 0.5 11.7 (12.1) 0.5 0.5 (0.5) 0.5

23 FL Complaint 3 44.7 (46.0) 1.1 8.1 (8.7) 0.5 10.3 (11.0) 0.5 0.8 (1.0) 1.0

24 FL Complaint 3 28.7 (30.0) 0.5 4.3 (4.7) 0.5 3.4 (3.5) 0.5 0.5 (0.5) 0.5

25 FL Complaint 3 34.0 (37.0) 0.5 6.4 (7.1) 0.5 5.1 (5.4) 0.5 0.5 (0.5) 0.5

26 FL Complaint 3 24.9 (26.0) 0.5 12.1 (12.4) 0.5 7.3 (9.0) 0.5 0.5 (0.5) 0.5

27 FL Complaint 3 52.7 (59.0) 0.5 5.3 (6.2) 0.5 5.0 (5.8) 0.5 0.5 (0.5) 0.5

28 FL Complaint 3 57.2 (59.0) 0.5 10.5 (11.5) 0.5 18.5 (19.5) 0.5 0.5 (0.6) 0.5

29 LA Complaint 3 48.4 (51.2) 0.5 8.7 (8.8) 0.5 3.2 (3.3) 0.5 1.0 (1.0) 1.0

30 LA Complaint 3 26.3 (28.0) 0.6 12.0 (13.0) 0.6 2.9 (3.0) 0.6 1.0 (1.0) 1.2

31 LA Complaint 3 63.9 (66.0) 1.2 7.5 (8.4) 0.5 5.9 (6.3) 0.5 0.6 (1.0) 0.5

32 LA Complaint 3 55.2 (56.0) 0.5 21.7 (23.0) 0.5 10.6 (11.0) 0.5 0.5 (0.5) 0.5

33 LA Non-complaint 3 43.3 (48.7) 1.1 10.3 (11.1) 0.5 5.1 (5.8) 0.5 0.5 (0.5) 0.5

34 LA Complaint 3 23.7 (24.0) 1.6 5.9 (6.3) 0.5 2.5 (2.9) 0.5 0.5 (0.5) 0.5

35 LA Non-complaint 3 33.4 (37.0) 1.8 4.8 (4.9) 0.5 3.9 (4.3) 0.5 0.5 (0.5) 0.5

36 LA Complaint 3 33.4 (37.0) 2.8 9.8 (11.0) 0.4 4.0 (4.4) 0.4 0.5 (0.5) 0.4

37 LA Complaint 3 17.7 (19.0) 1.5 7.0 (7.9) 0.5 1.8 (2.0) 0.5 0.5 (0.5) 0.5

38 LA Complaint 3 7.0 (8.8) 1.3 5.2 (5.3) 3.1 0.7 (1.2) 0.5 0.5 (0.5) 0.5

39 MS Complaint 3 18.7 (23.0) 0.5 7.4 (8.3) 0.5 2.1 (2.3) 0.5 0.5 (0.6) 0.5

40 MS Complaint 3 33.3 (35.0) 1.3 5.6 (6.0) 0.6 2.9 (5.9) 0.6 0.5 (0.5) 0.6

41 VA Complaint 3 18.1 (31.8) NA 8.4 (11.9) NA 3.3 (5.8) NA 0.5 (0.5) NA

42 VA Non-complaint 3 8.4 (10.0) NA 3.3 (3.5) NA 1.2 (1.4) NA 0.5 (0.5) NA

43 VA Complaint 3 33.5 (34.0) 1.3 16.8 (17.5) 0.5 6.3 (6.5) 0.5 0.5 (0.5) 0.5

44 VA Complaint 3 40.8 (44.0) 1.2 9.0 (9.3) 0.5 5.2 (5.7) 0.5 0.5 (0.5) 0.5

45 VA Complaint 3 19.0 (23.1) 0.5 8.8 (11.1) 0.5 2.9 (3.7) 0.5 0.5 (0.5) 0.5

46 VA Non-complaint 3 17.3 (19.0) 0.6 4.3 (6.4) 0.6 2.8 (2.9) 0.6 0.5 (0.5) 0.6

47 VA Complaint 3 32.7 (33.1) NA 10.7 (12.0) NA 5.5 (5.8) NA 0.5 (0.5) NA

48 VA Complaint 3 63.0 (79.0) NA 7.5 (8.9) NA 3.2 (3.5) NA 0.5 (0.5) NA

49 AL Complaint 3 39.0 (41.0) 1.4 8.1 (8.8) 1.5 3.6 (3.9) 0.5 0.5 (0.5) 0.5

50 AL Complaint 3 35.3 (38.0) NA 6.6 (7.1) NA 3.4 (3.6) NA 0.5 (0.6) NA

51 AL Non-complaint 3 14.7 (15.0) NA 14.3 (17.0) NA 2.4 (2.6) NA 0.5 (0.5) NA

μg/m3 micrograms per cubic meter ave average OA outdoor 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–5 
Table A.4 Summary Statistics for Aldehyde Concentrations (μg/m3

) in Indoor and Outdoor Air, by House 

2,5-Dimethylbenzaldehyde Formaldehyde n-Hexaldehyde Isovaleraldehyde

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 0.5 (0.5) 0.5 46.6 (49.3) 4.5 31.8 (32.8) 0.5 1.2 (1.2) 0.5

 2 FL Non-complaint 3 1.3 (1.7) 0.5 74.7 (77.0) 3.2 24.2 (25.0) 0.5 2.4 (2.5) 0.5

 3 FL Complaint 3 0.7 (1.2) 0.6 33.5 (78.1) 2.5 17.6 (40.3) 0.6 0.9 (1.6) 0.6

 4 FL Complaint 3 0.5 (0.5) 0.7 57.1 (60.0) 3.4 21.6 (24.0) 0.7 1.3 (1.4) 0.7

 5 FL Non-complaint 3 0.5 (0.5) 0.7 65.7 (68.0) 6.2 41.5 (46.0) 0.7 0.9 (1.3) 0.7

 6 FL Complaint 3 0.5 (0.5) 0.5 36.7 (42.0) 5.3 14.5 (17.0) 0.5 1.5 (1.5) 0.5

 7 FL Complaint 3 0.5 (0.6) 0.5 154.9 (200.0) 5.0 58.5 (64.0) 0.5 0.9 (1.2) 0.5

 8 FL Non-complaint 3 0.8 (1.3) 0.6 40.7 (42.0) 2.9 7.7 (9.0) 0.6 0.5 (0.5) 0.6

 9 FL Complaint 3 0.5 (0.5) 0.5 43.5 (44.0) 4.1 61.3 (66.0) 0.5 1.7 (1.8) 0.5

10 FL Complaint 3 0.5 (0.5) 3.4 56.2 (63.0) 1.5 13.7 (15.0) 0.5 0.6 (1.0) 0.5

11 FL Complaint 3 0.5 (0.5) 0.5 97.3 (100.0) 5.3 24.0 (25.0) 0.5 0.5 (0.5) 0.5

12 FL Complaint 3 0.5 (0.5) 0.5 48.7 (49.0) 0.5 21.1 (23.0) 0.5 2.2 (2.3) 0.5

13 FL Complaint 3 0.5 (0.5) 0.5 88.5 (92.5) 0.5 50.2 (53.5) 0.5 2.0 (2.3) 0.5

14 FL Complaint 3 5.7 (7.0) 7.5 36.3 (37.0) 0.5 6.4 (7.4) 0.5 0.5 (0.5) 0.5

15 FL Complaint 3 0.5 (0.6) 0.5 50.8 (58.0) 5.6 16.4 (18.0) 0.5 0.5 (0.6) 0.5

16 FL Complaint 3 0.8 (1.3) 0.5 110.0 (110.0) 3.7 26.5 (28.5) 0.5 2.8 (3.4) 0.5

17 FL Non-complaint 3 0.5 (0.5) 0.5 66.2 (68.0) 5.1 96.5 (99.0) 0.5 2.5 (2.7) 0.5

18 FL Complaint 3 0.5 (0.5) 0.5 56.4 (73.2) 6.5 21.0 (24.1) 0.5 1.5 (1.6) 0.5

19 FL Complaint 3 0.5 (0.5) 3.4 58.5 (66.0) 1.4 14.3 (15.0) 0.5 1.4 (1.7) 0.5

20 FL Complaint 3 0.5 (0.5) 0.5 53.3 (60.8) 6.0 23.4 (25.9) 0.5 0.5 (0.5) 0.5

21 FL Complaint 3 0.5 (0.5) 3.1 43.3 (44.0) 1.1 31.0 (35.0) 0.5 1.4 (1.5) 0.5

22 FL Non-complaint 3 0.5 (0.5) 0.5 96.5 (110.5) 5.9 42.3 (44.8) 0.5 2.1 (2.1) 0.5

23 FL Complaint 3 0.8 (1.0) 1.0 21.7 (22.0) 2.0 44.2 (48.0) 0.5 1.5 (1.7) 0.5

24 FL Complaint 3 0.5 (0.5) 0.5 64.5 (65.5) 3.4 20.8 (22.0) 0.5 1.1 (1.1) 0.5

25 FL Complaint 4 0.5 (0.5) 0.5 77.0 (84.8) 3.1 60.2 (67.0) 0.5 2.2 (2.4) 0.5

26 FL Complaint 3 0.5 (0.5) 0.5 129.4 (140.0) 2.3 77.8 (85.0) 0.5 2.2 (2.4) 0.5

27 FL Complaint 3 0.5 (0.5) 0.5 52.3 (55.0) 3.2 59.0 (63.0) 0.5 2.0 (2.2) 0.5

28 FL Complaint 3 1.1 (1.1) 1.0 165.0 (190.0) 0.5 107.7 (120.0) 0.5 4.0 (4.2) 0.5

29 LA Complaint 3 1.0 (1.0) 0.5 120.5 (120.6) 2.7 38.2 (41.2) 0.5 1.7 (1.9) 0.5

30 LA Complaint 3 0.5 (0.5) 0.6 47.7 (52.9) 0.6 49.0 (54.0) 0.6 0.7 (1.1) 0.6

31 LA Complaint 3 0.5 (0.5) 0.5 67.7 (69.0) 3.5 90.5 (96.5) 0.5 2.5 (2.7) 0.5

32 LA Complaint 3 0.5 (0.5) 0.5 361.7 (375.0) 1.8 173.3 (180.0) 0.5 2.5 (5.2) 0.5

33 LA Non-complaint 3 0.5 (0.5) 0.5 43.5 (45.2) 1.8 63.5 (70.0) 0.5 0.9 (1.8) 0.5

34 LA Complaint 3 1.0 (1.3) 0.5 31.5 (31.8) 4.5 27.7 (30.0) 0.5 1.1 (1.1) 0.5

35 LA Non-complaint 3 0.5 (0.5) 0.5 52.0 (53.0) 4.9 41.2 (45.0) 0.5 1.8 (2.0) 0.5

36 LA Complaint 3 0.5 (0.5) 0.4 220.3 (240.0) 5.2 101.8 (110.0) 1.0 3.3 (3.7) 0.4

37 LA Complaint 3 0.5 (0.5) 0.5 51.7 (55.1) 3.7 13.7 (15.0) 0.5 0.9 (1.1) 0.5

38 LA Complaint 3 0.5 (0.5) 0.5 37.0 (54.0) 3.7 7.8 (12.0) 0.5 0.5 (0.5) 0.5

39 MS Complaint 3 0.9 (1.1) 1.0 84.8 (86.5) 3.7 30.5 (33.0) 0.5 0.7 (1.0) 0.5

40 MS Complaint 3 0.5 (0.5) 0.6 108.4 (120.1) 4.4 27.2 (30.0) 0.6 0.7 (1.1) 0.6

41 VA Complaint 3 0.5 (0.5) NA 59.4 (81.6) NA 34.7 (62.7) NA 1.1 (2.4) NA

42 VA Non-complaint 3 0.5 (0.5) NA 28.3 (31.5) NA 16.1 (20.0) NA 0.5 (0.5) NA

43 VA Complaint 3 0.5 (0.5) 0.5 125.1 (130.0) 2.8 130.1 (139.9) 0.5 3.4 (3.8) 0.5

44 VA Complaint 3 0.5 (0.5) 0.5 93.2 (110.0) 2.2 68.3 (73.0) 0.5 2.7 (3.0) 0.5

45 VA Complaint 3 0.5 (0.5) 0.5 76.0 (88.5) 1.9 36.3 (51.2) 0.5 0.5 (0.5) 0.5

46 VA Non-complaint 3 0.5 (0.5) 0.6 27.7 (29.0) 0.6 35.6 (39.0) 0.6 0.9 (1.1) 0.6

47 VA Complaint 3 0.5 (0.5) NA 86.2 (100.4) NA 91.4 (95.4) NA 1.1 (2.3) NA

48 VA Complaint 3 0.5 (0.5) NA 51.7 (65.0) NA 43.7 (50.0) NA 1.1 (1.4) NA

49 AL Complaint 3 0.5 (0.5) 0.5 158.3 (180.0) 4.3 47.8 (52.0) 0.5 2.4 (2.6) 0.5

50 AL Complaint 3 0.5 (0.6) NA 62.7 (72.0) NA 43.3 (46.0) NA 1.5 (1.8) NA

51 AL Non-complaint 3 0.5 (0.5) NA 128.4 (140.1) NA 25.5 (27.0) NA 0.5 (0.5) NA

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–6 
Table A.4 Summary Statistics for Aldehyde Concentrations (μg/m3

) in Indoor and Outdoor Air, by House 

Propionaldehyde m,p-Tolualdehyde o-Tolualdehyde Valeraldehyde 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 3.2 (3.4) 0.5 1.0 (1.1) 1.0 0.5 (0.5) 0.5 8.6 (8.9) 0.5

 2 FL Non-complaint 3 3.3 (3.4) 0.5 1.0 (1.0) 1.1 0.5 (0.5) 0.5 7.8 (8.2) 0.5

 3 FL Complaint 3 2.2 (4.6) 0.6 1.0 (1.0) 1.1 0.5 (0.5) 0.6 5.5 (11.9) 0.6

 4 FL Complaint 3 3.1 (3.5) 0.7 0.9 (1.0) 1.4 0.5 (0.5) 0.7 5.7 (6.2) 0.7

 5 FL Non-complaint 3 3.7 (4.0) 0.7 0.9 (1.0) 1.5 0.5 (0.5) 0.7 11.0 (11.0) 0.7

 6 FL Complaint 3 3.8 (3.9) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 4.0 (4.4) 0.5

 7 FL Complaint 3 7.7 (8.3) 17.0 1.0 (1.1) 1.0 0.5 (0.6) 0.5 16.3 (17.0) 0.5

 8 FL Non-complaint 3 2.2 (2.5) 0.6 1.0 (1.1) 1.1 0.5 (0.5) 0.6 2.6 (3.1) 0.6

 9 FL Complaint 3 4.8 (5.4) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 15.2 (16.0) 0.5

10 FL Complaint 3 2.0 (2.3) 0.5 0.9 (1.0) 1.0 0.5 (0.5) 0.5 3.9 (4.8) 0.5

11 FL Complaint 3 3.0 (3.1) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 6.1 (6.8) 0.5

12 FL Complaint 3 4.3 (4.6) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 5.6 (5.8) 0.5

13 FL Complaint 3 5.0 (5.1) 0.5 0.9 (1.0) 1.1 0.5 (0.5) 0.5 14.2 (14.5) 0.5

14 FL Complaint 3 2.1 (2.2) 0.5 0.9 (1.0) 1.0 0.5 (0.5) 0.5 2.8 (3.6) 0.5

15 FL Complaint 3 2.3 (2.5) 0.5 1.1 (1.2) 1.0 0.5 (0.6) 0.5 4.0 (4.4) 0.5

16 FL Complaint 3 8.1 (8.2) 0.5 1.0 (1.0) 0.9 0.5 (0.5) 0.5 10.3 (12.0) 0.5

17 FL Non-complaint 3 4.6 (4.8) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 18.7 (19.0) 0.5

18 FL Complaint 3 5.2 (5.6) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 7.8 (8.4) 0.5

19 FL Complaint 3 2.6 (2.8) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 4.2 (4.4) 0.5

20 FL Complaint 3 3.6 (3.9) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 6.6 (6.9) 0.5

21 FL Complaint 3 3.1 (3.2) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 7.8 (8.0) 0.5

22 FL Non-complaint 3 14.0 (15.1) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 12.0 (13.1) 0.5

23 FL Complaint 3 5.7 (6.1) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 14.5 (15.5) 0.5

24 FL Complaint 3 3.4 (3.4) 0.5 1.0 (1.0) 1.1 0.5 (0.5) 0.5 5.3 (5.5) 0.5

25 FL Complaint 4 5.3 (5.5) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 13.2 (15.0) 0.5

26 FL Complaint 3 5.4 (5.7) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 17.4 (19.0) 0.5

27 FL Complaint 3 5.0 (5.6) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 13.3 (14.0) 0.5

28 FL Complaint 3 10.4 (11.0) 0.5 1.1 (1.1) 1.0 0.5 (0.6) 0.5 28.5 (31.0) 0.5

29 LA Complaint 3 12.1 (27.1) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 8.9 (8.9) 0.5

30 LA Complaint 3 4.8 (5.1) 0.6 1.0 (1.0) 1.2 0.5 (0.5) 0.6 11.2 (12.0) 0.6

31 LA Complaint 3 10.2 (10.9) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 22.5 (23.0) 0.5

32 LA Complaint 3 12.2 (12.5) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 46.0 (49.0) 0.5

33 LA Non-complaint 3 6.1 (6.9) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 16.7 (17.1) 0.5

34 LA Complaint 3 1.9 (2.6) 0.5 0.9 (1.0) 1.0 0.5 (0.5) 0.5 7.8 (8.2) 0.5

35 LA Non-complaint 3 3.2 (3.4) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 9.2 (10.0) 0.5

36 LA Complaint 3 5.2 (5.6) 0.4 1.0 (1.0) 0.9 0.5 (0.5) 0.4 19.4 (21.0) 0.4

37 LA Complaint 3 2.1 (2.4) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 4.0 (4.3) 0.5

38 LA Complaint 3 1.0 (1.5) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 2.0 (2.9) 0.5

39 MS Complaint 3 2.3 (2.4) 0.5 1.0 (1.1) 1.0 0.5 (0.6) 0.5 7.1 (7.8) 0.5

40 MS Complaint 3 2.6 (2.8) 0.6 0.9 (1.0) 1.1 0.5 (0.5) 0.6 5.6 (5.7) 0.6

41 VA Complaint 3 2.6 (5.2) NA 1.0 (1.0) NA 0.5 (0.5) NA 9.6 (16.9) NA

42 VA Non-complaint 3 0.8 (1.5) NA 1.0 (1.1) NA 0.5 (0.5) NA 3.3 (4.1) NA

43 VA Complaint 3 6.4 (7.0) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 26.2 (27.0) 0.5

44 VA Complaint 3 6.1 (6.6) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 17.2 (18.5) 0.5

45 VA Complaint 3 2.5 (3.4) 0.5 1.0 (1.0) 1.0 0.5 (0.5) 0.5 9.2 (12.1) 0.5

46 VA Non-complaint 3 1.8 (1.9) 0.6 1.0 (1.0) 1.1 0.5 (0.5) 0.6 8.4 (9.1) 0.6

47 VA Complaint 3 5.7 (6.2) NA 1.0 (1.0) NA 0.5 (0.5) NA 19.8 (21.1) NA

48 VA Complaint 3 3.1 (3.4) NA 1.0 (1.0) NA 0.5 (0.5) NA 10.3 (11.0) NA

49 AL Complaint 3 4.4 (4.6) 0.5 0.9 (1.0) 1.0 0.5 (0.5) 0.5 11.2 (12.0) 0.5

50 AL Complaint 3 2.8 (2.9) NA 1.0 (1.1) NA 0.5 (0.6) NA 9.9 (10.5) NA

51 AL Non-complaint 3 2.5 (3.0) NA 1.0 (1.0) NA 0.5 (0.5) NA 6.5 (6.7) NA

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–7 
Table A.5 Summary Statistics for Aldehyde (Passive) Concentrations (μg/m3

) in Indoor and Outdoor Air, by House

Acetaldehyde Acrolein Benzaldehyde 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 12.5 (12.7) 0.8 4.5 (4.8) 0.2 2.5 (2.7) 0.1 

 2 FL Non-complaint 3 12.9 (15.4) 0.9 3.7 (4.4) 0.2 2.4 (2.9) 0.1 

 3 FL Complaint 3 10.7 (11.3) 0.7 5.9 (6.0) 0.2 2.7 (2.8) 0.1 

 4 FL Complaint 3 13.4 (15.2) 1.1 0.8 (0.9) 0.2 1.7 (1.8) 0.1 

 5 FL Non-complaint 3 10.5 (11.6) 0.8 0.8 (0.8) 0.2 2.2 (2.5) 0.1 

 6 FL Complaint 3 15.5 (15.5) 1.4 0.8 (0.8) 0.2 1.5 (1.5) 0.1 

 7 FL Complaint 3 2.1 (3.6) NA 5.4 (7.9) NA 3.8 (4.7) NA 

 8 FL Non-complaint 3 14.4 (15.0) 1.1 0.8 (0.8) 0.2 2.6 (2.8) 0.1 

 9 FL Complaint 3 11.4 (11.9) 1.1 0.8 (0.8) 0.2 2.0 (2.2) 0.1 

10 FL Complaint 3 21.8 (23.3) 1.3 0.9 (1.0) 0.2 1.9 (2.7) 0.1 

11 FL Complaint 3 4.4 (4.8) 0.7 1.9 (1.9) 0.2 2.6 (2.9) 0.1 

12 FL Complaint 3 20.8 (21.0) 1.0 1.0 (1.0) 0.2 3.0 (3.4) 0.1 

13 FL Complaint 3 11.1 (13.0) 0.8 2.2 (2.2) 0.2 3.3 (3.5) 0.1 

14 FL Complaint 3 10.4 (10.9) 0.8 0.8 (0.8) 0.2 1.4 (1.4) 0.1 

15 FL Complaint 3 9.1 (9.1) 0.8 1.6 (3.5) 0.2 1.8 (2.0) 0.1 

16 FL Complaint 3 10.0 (10.4) 1.2 1.1 (1.2) 0.2 2.7 (2.9) 0.1 

17 FL Non-complaint 3 13.1 (14.4) 1.0 4.6 (4.7) 0.2 2.7 (2.9) 0.1 

18 FL Complaint 3 15.5 (18.1) NA 1.8 (4.0) NA 4.2 (4.4) NA 

19 FL Complaint 3 8.3 (8.3) 0.9 0.9 (1.0) 0.2 1.9 (2.0) 0.1 

20 FL Complaint 3 8.2 (10.7) 0.7 3.5 (3.6) 0.2 3.0 (3.4) 0.1 

21 FL Complaint 3 19.3 (19.4) 1.2 1.0 (1.0) 0.2 2.7 (2.8) 0.1 

22 FL Non-complaint 3 5.9 (8.3) 1.5 2.6 (2.7) 0.2 2.6 (2.8) 0.1 

23 FL Complaint 3 20.2 (20.6) 1.0 1.1 (1.1) 0.2 4.2 (4.3) 0.1 

24 FL Complaint 3 10.6 (11.3) 0.7 2.3 (2.3) 0.2 1.3 (1.3) 0.1 

25 FL Complaint 3 7.2 (8.5) 1.0 2.7 (2.8) 0.2 3.5 (3.6) 0.1 

26 FL Complaint 3 3.8 (4.2) 0.9 4.1 (4.5) 0.2 2.8 (2.8) 0.1 

27 FL Complaint 3 12.3 (13.5) 0.8 5.8 (6.0) 0.2 2.5 (2.7) 0.1 

28 FL Complaint 3 4.0 (4.7) 0.9 3.7 (3.8) 0.2 3.3 (3.8) 0.1 

29 LA Complaint 3 4.2 (4.6) 1.0 3.6 (3.7) 0.2 2.7 (2.8) 0.1 

30 LA Complaint 2 12.5 (12.5) 0.7 7.2 (7.3) 0.2 3.7 (3.7) 0.1 

31 LA Complaint 3 14.1 (15.3) 1.7 6.4 (6.7) 0.2 2.5 (2.7) 0.1 

32 LA Complaint 3 0.9 (0.9) 0.8 3.0 (3.1) 0.2 1.4 (1.5) 0.1 

33 LA Non-complaint 3 19.4 (22.2) 1.1 5.4 (5.8) 0.2 3.4 (3.7) 0.1 

34 LA Complaint 3 11.2 (11.9) 1.0 0.9 (0.9) 0.5 2.0 (2.1) 0.1 

35 LA Non-complaint 3 14.0 (15.0) 0.8 5.4 (6.0) 0.2 2.3 (2.5) 0.1 

36 LA Complaint 3 0.7 (0.7) 0.9 2.9 (3.3) 0.2 1.4 (1.8) 0.1 

37 LA Complaint 3 9.9 (10.7) 0.8 8.0 (8.8) 0.4 2.2 (2.5) 0.1 

38 LA Complaint 3 0.7 (0.7) 0.8 4.7 (4.9) 0.2 1.8 (1.9) 0.1 

39 MS Complaint 3 5.7 (8.3) 0.8 3.8 (4.5) 0.2 2.2 (2.5) 0.1 

40 MS Complaint 3 4.5 (5.7) 0.9 2.9 (3.0) 0.2 1.5 (1.6) 0.1 

41 VA Complaint 3 11.0 (11.5) 0.8 2.9 (3.2) 0.2 4.0 (4.2) 0.1 

42 VA Non-complaint 3 8.1 (9.0) 0.8 2.6 (2.9) 0.2 1.3 (1.7) 0.1 

43 VA Complaint 3 2.9 (3.7) 0.7 4.1 (4.3) 0.2 3.8 (3.9) 0.1 

44 VA Complaint 3 6.6 (11.1) 1.0 3.1 (3.6) 0.2 3.1 (3.5) 0.1 

45 VA Complaint 3 6.8 (7.1) 1.0 3.0 (3.6) 0.2 3.3 (3.9) 0.1 

46 VA Non-complaint 3 11.7 (12.1) 0.8 2.3 (2.6) 0.2 2.1 (2.1) 0.1 

47 VA Complaint 3 6.7 (8.2) 0.7 4.8 (5.1) 0.2 3.4 (3.5) 0.1 

48 VA Complaint 3 17.8 (22.4) 0.8 1.0 (1.0) 0.2 3.6 (3.7) 0.1 

49 AL Complaint 3 5.5 (7.7) 0.7 3.5 (4.2) 0.2 2.1 (2.3) 0.1 

50 AL Complaint 3 8.8 (9.5) 1.0 NA 0.2 2.8 (3.1) 0.1 

51 AL Non-complaint 3 5.4 (5.9) 0.8 4.1 (4.2) 0.2 1.7 (1.9) 0.1 

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–8 
Table A.5 Summary Statistics for Aldehyde (Passive) Concentrations (μg/m3

) in Indoor and Outdoor Air, by House

Formaldehyde n-Hexaldehyde Isovaleraldehyd 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 47.0 (48.6) 1.9 152.8 (157.4) 1.2 0.7 (1.2) 0.1 

 2 FL Non-complaint 3 56.0 (65.2) 2.1 83.7 (96.5) 1.0 0.7 (1.0) 0.1 

 3 FL Complaint 3 56.2 (57.9) 1.9 114.5 (116.3) 1.1 1.0 (1.3) 0.1 

 4 FL Complaint 3 47.7 (47.7) 2.6 70.8 (78.7) 1.6 0.4 (0.5) 0.1 

 5 FL Non-complaint 3 54.0 (56.4) 2.7 143.0 (152.5) 1.9 0.5 (0.5) 0.1 

 6 FL Complaint 3 38.7 (39.7) 2.8 57.5 (58.5) 2.0 0.4 (0.4) 0.1 

 7 FL Complaint 3 62.6 (65.8) NA 167.1 (193.8) NA 1.0 (1.0) NA 

 8 FL Non-complaint 3 38.7 (39.7) 2.6 27.5 (27.7) 1.3 1.3 (1.5) 0.1 

 9 FL Complaint 3 41.1 (41.9) 4.1 137.4 (144.3) 2.0 0.4 (0.4) 0.1 

10 FL Complaint 3 52.8 (55.0) 3.3 56.4 (60.5) 2.1 0.5 (0.5) 0.1 

11 FL Complaint 3 85.3 (92.2) 2.2 88.7 (98.6) 1.0 1.0 (1.0) 0.1 

12 FL Complaint 3 50.6 (52.3) 2.6 94.1 (94.7) 1.2 0.5 (0.5) 0.1 

13 FL Complaint 3 67.9 (69.8) 1.9 138.1 (139.2) 1.1 1.2 (1.2) 0.1 

14 FL Complaint 3 33.3 (35.4) 1.7 24.8 (25.7) 0.8 0.4 (0.4) 0.1 

15 FL Complaint 3 52.8 (57.7) 2.0 67.0 (71.4) 0.9 0.4 (0.5) 0.1 

16 FL Complaint 3 74.4 (77.1) 2.3 81.3 (84.9) 1.2 0.6 (0.7) 0.1 

17 FL Non-complaint 3 44.6 (46.8) 1.9 340.1 (349.4) 2.5 0.5 (0.5) 0.1 

18 FL Complaint 3 43.7 (56.6) NA 67.9 (72.6) NA 0.4 (0.5) NA 

19 FL Complaint 3 50.2 (56.9) 1.9 51.2 (53.7) 1.3 0.5 (0.5) 0.1 

20 FL Complaint 3 59.0 (65.8) 1.6 127.1 (136.3) 1.1 0.5 (0.5) 0.1 

21 FL Complaint 3 48.3 (49.5) 2.3 113.4 (118.0) 1.7 0.5 (0.5) 0.1 

22 FL Non-complaint 3 64.7 (70.1) 2.1 128.4 (133.4) 1.7 0.5 (0.5) 0.1 

23 FL Complaint 3 22.5 (23.3) 2.1 162.6 (166.9) 1.5 0.6 (0.6) 0.1 

24 FL Complaint 3 42.6 (44.1) 2.1 67.2 (68.5) 1.1 0.5 (0.5) 0.1 

25 FL Complaint 3 63.2 (66.7) 2.4 215.8 (220.0) 2.2 1.1 (1.3) 0.1 

26 FL Complaint 3 75.7 (79.4) 1.9 288.5 (290.5) 1.7 0.5 (0.5) 0.1 

27 FL Complaint 3 57.9 (59.8) 1.9 288.0 (298.9) 1.7 0.9 (1.6) 0.1 

28 FL Complaint 3 75.9 (80.7) 2.1 316.9 (316.9) 2.0 1.7 (2.6) 0.1 

29 LA Complaint 3 70.2 (70.2) 2.5 118.7 (124.7) 2.4 1.0 (1.2) 0.1 

30 LA Complaint 2 35.1 (36.5) 1.5 178.9 (183.8) 1.1 0.5 (0.5) 0.1 

31 LA Complaint 3 47.6 (49.1) 4.0 246.7 (256.6) 6.5 0.5 (0.5) 0.1 

32 LA Complaint 3 85.6 (85.6) 2.3 129.0 (132.5) 1.6 0.7 (0.7) 0.1 

33 LA Non-complaint 3 38.3 (44.2) 2.3 175.9 (189.8) 1.6 0.5 (0.5) 0.1 

34 LA Complaint 3 31.5 (32.2) 2.2 110.4 (113.6) 1.1 0.5 (0.5) 0.1 

35 LA Non-complaint 3 32.5 (36.1) 2.0 225.8 (233.1) 1.2 0.5 (0.5) 0.1 

36 LA Complaint 3 63.9 (67.2) 1.7 146.1 (156.1) 1.2 1.0 (1.2) 0.1 

37 LA Complaint 3 47.4 (50.4) 1.9 42.5 (44.4) 0.8 0.5 (0.5) 0.1 

38 LA Complaint 3 49.7 (54.4) 1.7 24.3 (27.2) 0.9 0.5 (0.5) 0.1 

39 MS Complaint 3 53.6 (62.9) 1.8 88.0 (96.8) 0.9 0.5 (0.5) 0.1 

40 MS Complaint 3 64.5 (65.3) 1.7 94.9 (102.3) 1.0 0.5 (0.5) 0.1 

41 VA Complaint 3 50.7 (54.1) 1.5 183.4 (249.9) 0.9 0.8 (1.4) 0.1 

42 VA Non-complaint 3 27.6 (29.4) 1.6 61.9 (74.9) 0.8 0.5 (0.5) 0.1 

43 VA Complaint 3 61.9 (67.1) 1.5 283.9 (283.9) 1.1 1.8 (2.1) 0.1 

44 VA Complaint 3 60.2 (70.1) 1.9 195.4 (207.7) 1.1 0.8 (1.2) 0.1 

45 VA Complaint 3 53.8 (62.9) 2.1 102.3 (132.4) 0.9 0.5 (0.5) 0.1 

46 VA Non-complaint 3 28.6 (32.2) 1.5 146.7 (157.6) 0.9 1.1 (1.6) 0.1 

47 VA Complaint 3 52.0 (56.4) 1.7 203.3 (217.0) 0.9 1.2 (1.9) 0.1 

48 VA Complaint 3 47.6 (51.1) 1.8 186.2 (191.2) 0.8 1.0 (1.8) 0.1 

49 AL Complaint 3 57.1 (60.4) 1.7 85.4 (85.8) 0.9 0.5 (0.5) 0.1 

50 AL Complaint 3 38.2 (44.1) 1.7 129.8 (145.5) 1.2 0.5 (0.5) 0.1 

51 AL Non-complaint 3 54.6 (60.5) 1.7 47.6 (51.3) 0.9 0.5 (0.5) 0.1 

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–9 
Table A.5 Summary Statistics for Aldehyde (Passive) Concentrations (μg/m3

) in Indoor and Outdoor Air, by House

Butanal Propionaldehyde Valeraldehyde 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 28.1 (29.9) 2.0 4.3 (4.5) 0.2 29.7 (31.9) 0.7 

 2 FL Non-complaint 3 23.3 (28.9) 1.8 2.7 (3.4) 0.3 16.6 (18.4) 0.6 

 3 FL Complaint 3 26.1 (27.2) 1.9 3.4 (3.7) 0.2 24.9 (25.8) 0.6 

 4 FL Complaint 3 25.0 (30.1) 2.1 3.4 (4.1) 0.5 14.5 (17.5) 0.6 

 5 FL Non-complaint 3 31.5 (35.1) 1.5 3.6 (3.9) 0.3 26.7 (28.4) 0.5 

 6 FL Complaint 3 22.0 (22.8) 2.0 5.4 (5.4) 0.6 11.4 (11.9) 0.6 

 7 FL Complaint 3 10.8 (16.1) NA 1.5 (1.5) NA 19.4 (24.1) NA 

 8 FL Non-complaint 3 39.2 (41.7) 2.2 4.5 (4.8) 0.5 8.4 (8.6) 0.6 

 9 FL Complaint 3 28.1 (29.1) 2.5 3.6 (3.8) 0.5 25.0 (25.9) 0.8 

10 FL Complaint 3 20.4 (21.8) 2.1 3.3 (3.3) 0.5 15.5 (15.9) 0.7 

11 FL Complaint 3 5.8 (5.8) 1.8 1.6 (1.6) 0.2 11.8 (12.8) 0.5 

12 FL Complaint 3 56.5 (57.4) 2.2 6.7 (6.8) 0.5 27.3 (30.4) 0.6 

13 FL Complaint 3 44.3 (48.2) 1.8 1.8 (1.8) 0.2 27.4 (29.9) 0.7 

14 FL Complaint 3 22.1 (23.1) 2.4 0.7 (0.7) 0.4 9.3 (10.0) 0.5 

15 FL Complaint 3 18.5 (19.9) 1.9 1.4 (3.1) 0.4 17.1 (19.4) 0.5 

16 FL Complaint 3 29.0 (30.5) 3.4 0.9 (1.0) 0.6 22.2 (22.2) 0.6 

17 FL Non-complaint 3 31.3 (32.9) 2.9 5.6 (6.1) 0.4 50.0 (52.2) 0.7 

18 FL Complaint 3 35.4 (42.0) NA 6.1 (7.2) NA 26.8 (28.5) NA 

19 FL Complaint 3 17.1 (17.6) 2.1 3.2 (3.3) 0.4 14.7 (14.9) 0.8 

20 FL Complaint 3 23.6 (25.5) 1.8 3.7 (4.5) 0.2 31.8 (33.4) 0.6 

21 FL Complaint 3 98.2 (104.0) 4.1 4.1 (4.3) 0.5 28.2 (30.3) 1.2 

22 FL Non-complaint 3 32.4 (35.4) 2.7 2.9 (3.8) 0.5 23.4 (23.7) 0.8 

23 FL Complaint 3 63.0 (63.0) 3.5 7.8 (7.9) 0.4 46.4 (47.1) 0.9 

24 FL Complaint 3 26.2 (27.2) 1.4 3.3 (3.5) 0.2 14.6 (15.3) 0.2 

25 FL Complaint 3 23.7 (24.0) 2.1 3.7 (3.9) 0.4 32.9 (34.8) 0.7 

26 FL Complaint 3 18.9 (19.2) 2.0 1.5 (2.1) 0.4 39.8 (43.2) 0.7 

27 FL Complaint 3 37.1 (37.4) 2.0 4.0 (4.3) 0.2 41.8 (43.8) 0.7 

28 FL Complaint 3 24.3 (27.5) 1.9 1.7 (2.2) 0.4 45.1 (46.5) 0.9 

29 LA Complaint 3 14.7 (15.5) 2.4 1.5 (2.0) 0.6 22.0 (23.7) 0.9 

30 LA Complaint 2 25.9 (26.2) 1.2 4.3 (4.5) 0.2 42.2 (43.6) 0.2 

31 LA Complaint 3 24.8 (25.0) 2.6 5.6 (5.6) 0.5 45.5 (49.4) 1.8 

32 LA Complaint 3 4.8 (7.2) 1.5 1.0 (1.0) 0.2 17.3 (17.9) 0.8 

33 LA Non-complaint 3 33.5 (36.9) 2.2 6.7 (7.4) 0.4 43.5 (49.4) 0.7 

34 LA Complaint 3 20.7 (21.8) 1.9 3.3 (3.5) 0.5 27.4 (29.6) 0.5 

35 LA Non-complaint 3 56.8 (58.3) 1.9 6.5 (6.8) 0.3 40.5 (43.0) 0.6 

36 LA Complaint 3 6.6 (7.2) 1.8 0.8 (0.8) 0.2 15.6 (18.3) 0.5 

37 LA Complaint 3 13.0 (14.1) 1.4 3.1 (3.2) 0.4 13.3 (13.8) 0.6 

38 LA Complaint 3 2.7 (2.7) 1.6 0.8 (0.8) 0.2 4.7 (5.3) 0.2 

39 MS Complaint 3 23.8 (25.6) 1.4 3.2 (4.2) 0.5 16.7 (17.3) 0.2 

40 MS Complaint 3 10.2 (10.9) 2.0 1.1 (1.7) 0.4 16.6 (18.4) 0.5 

41 VA Complaint 3 28.4 (33.1) 1.7 4.1 (4.5) 0.5 44.3 (53.5) 0.2 

42 VA Non-complaint 3 12.7 (14.2) 1.4 2.8 (3.0) 0.3 13.4 (14.6) 0.2 

43 VA Complaint 3 15.1 (18.3) 1.6 0.8 (0.8) 0.2 37.2 (37.8) 0.2 

44 VA Complaint 3 22.0 (29.1) 2.3 2.4 (4.2) 0.4 34.0 (40.6) 0.2 

45 VA Complaint 3 16.3 (18.7) 2.1 2.5 (2.7) 0.4 23.1 (28.1) 0.5 

46 VA Non-complaint 3 20.9 (22.9) 1.4 3.5 (3.6) 0.2 32.7 (34.7) 0.5 

47 VA Complaint 3 17.9 (19.8) 1.5 2.2 (2.5) 0.2 34.1 (35.7) 0.5 

48 VA Complaint 3 25.8 (27.4) 1.6 4.2 (4.8) 0.2 40.5 (41.8) 0.2 

49 AL Complaint 3 9.9 (11.3) 1.5 1.8 (2.7) 0.2 16.7 (17.2) 0.2 

50 AL Complaint 3 16.7 (18.6) 1.8 3.1 (3.3) 0.6 27.4 (30.5) 0.5 

51 AL Non-complaint 3 9.5 (9.8) 1.8 2.2 (2.2) 0.5 12.4 (13.9) 0.5 

μg/m3 micrograms per cubic meter ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–10 
Table A.6 Summary Statistics for Analyte Concentrations (ppb) Collected Using Passive Monitors in Indoor and 

Outdoor Air, by House 

Hydrogen Sulfide Ozone Nitrogen Dioxide 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 0.21 (0.21) 0.8 0.33 (0.33) 12.5 0.18 (0.21) 1.0 

 2 FL Non-complaint 3 0.2 (0.2) 0.7 0.33 (0.33) 10.2 1.25 (1.76) 0.5 

 3 FL Complaint 3 0.45 (0.54) 0.8 0.33 (0.33) 11.3 0.1 (0.13) 1.1 

 4 FL Complaint 3 0.64 (0.67) 1.9 0.45 (0.74) 17.5 7.06 (8.28) 1.6 

 5 FL Non-complaint 3 0.48 (0.55) 2.2 0.31 (0.31) 13.4 2.03 (2.27) 1.3 

 6 FL Complaint 3 0.71 (0.82) 1.7 0.33 (0.33) 9.9 3.09 (3.65) 0.6 

 7 FL Complaint 3 1.28 (1.56) NA 0.3 (0.3) NA 0.64 (1.11) NA 

 8 FL Non-complaint 3 2.23 (2.68) 0.7 0.33 (0.33) 15.7 0.89 (0.99) 1.8 

 9 FL Complaint 3 0.82 (0.93) 1.4 0.33 (0.33) 9.1 1.17 (1.39) 1.0 

10 FL Complaint 3 0.81 (1.18) 0.6 0.36 (0.36) 12.4 0.61 (0.8) 1.3 

11 FL Complaint 3 0.46 (0.97) 0.8 0.34 (0.34) 12.6 2.36 (2.64) 1.5 

12 FL Complaint 3 0.26 (0.26) 3.0 0.42 (0.42) 12.4 0.5 (0.62) 1.0 

13 FL Complaint 3 0.94 (1) 0.6 0.38 (0.38) 10.6 0.06 (0.06) 0.5 

14 FL Complaint 3 0.21 (0.21) 1.6 0.33 (0.33) 14.6 0.76 (0.93) 1.0 

15 FL Complaint 3 0.55 (0.61) 0.2 0.32 (0.32) 15.9 3.92 (6.42) 5.1 

16 FL Complaint 3 0.44 (0.56) 0.9 0.36 (0.36) 13.5 1.09 (1.31) 2.7 

17 FL Non-complaint 3 0.22 (0.22) 0.2 0.34 (0.34) 14.7 2.27 (2.64) 4.0 

18 FL Complaint 3 0.19 (0.19) NA 0.31 (0.31) NA 0.81 (0.92) NA 

19 FL Complaint 3 0.22 (0.22) 0.2 0.35 (0.35) 13.3 2.41 (3.54) 4.6 

20 FL Complaint 3 0.63 (0.7) 0.2 0.33 (0.33) 11.2 1.16 (1.25) 1.5 

21 FL Complaint 3 0.59 (0.73) 0.2 0.36 (0.36) 10.8 1.03 (1.22) 3.0 

22 FL Non-complaint 3 0.22 (0.22) 0.5 0.35 (0.35) 15.3 1.84 (1.9) 3.2 

23 FL Complaint 3 0.24 (0.24) 0.6 0.38 (0.38) 11.2 0.84 (0.93) 7.4 

24 FL Complaint 3 0.29 (0.47) 1.4 0.31 (0.31) 8.7 0.84 (1.04) 1.5 

25 FL Complaint 3 0.29 (0.46) 1.3 0.34 (0.34) 10.3 0.61 (0.83) 1.3 

26 FL Complaint 3 0.8 (0.83) 1.6 0.35 (0.35) 10.5 0.29 (0.47) 1.7 

27 FL Complaint 3 0.9 (1.04) 0.9 0.35 (0.35) 13.3 0.2 (0.23) 1.3 

28 FL Complaint 3 1.18 (1.19) 0.7 0.37 (0.37) 11.7 0.91 (1.22) 1.0 

29 LA Complaint 3 0.85 (1) 1.2 0.35 (0.35) 12.2 11.86 (13.87) 2.6 

30 LA Complaint 2 0.4 (0.58) 0.2 0.33 (0.33) 6.4 0.98 (1.02) 1.1 

31 LA Complaint 3 1.47 (1.66) 1.1 0.35 (0.35) 12.2 3.87 (4.7) 2.6 

32 LA Complaint 3 0.88 (1) 0.7 0.35 (0.35) 11.9 1.5 (1.68) 1.1 

33 LA Non-complaint 3 0.23 (0.23) 1.2 0.36 (0.36) 15.6 4.33 (4.95) 3.6 

34 LA Complaint 3 0.95 (1.12) 1.5 0.33 (0.33) 12.5 4.12 (4.65) 1.5 

35 LA Non-complaint 3 0.28 (0.43) 1.6 0.33 (0.33) 11.3 5.03 (5.83) 0.8 

36 LA Complaint 3 1.82 (2.02) 2.7 0.32 (0.32) 12.0 2.74 (2.98) 2.5 

37 LA Complaint 3 0.86 (1.44) 3.2 0.33 (0.33) 14.6 4.98 (5.04) 4.0 

38 LA Complaint 3 2.23 (2.54) 3.5 0.92 (1.39) 11.9 2.92 (3.18) 3.0 

39 MS Complaint 3 0.29 (0.45) 0.2 0.33 (0.33) 7.2 0.68 (0.89) 0.8 

40 MS Complaint 3 0.42 (0.55) 0.2 0.33 (0.33) 5.8 0.76 (0.81) 0.2 

41 VA Complaint 3 0.31 (0.5) 0.8 0.36 (0.36) 13.3 3.92 (4.8) 4.8 

42 VA Non-complaint 3 0.23 (0.23) 0.8 0.36 (0.36) 16.9 18.67 (20.93) NA 

43 VA Complaint 3 1.01 (1.53) 0.2 0.34 (0.34) NA 5.51 (6.55) NA 

44 VA Complaint 3 0.22 (0.22) 0.8 0.35 (0.35) 13.3 3.61 (4.18) 12.7 

45 VA Complaint 3 0.98 (1.1) 0.5 0.36 (0.36) 15.6 3.67 (4.25) 8.5 

46 VA Non-complaint 3 0.23 (0.23) 0.6 0.36 (0.36) 15.7 6.11 (6.63) 7.4 

47 VA Complaint 3 0.59 (0.85) 0.2 0.34 (0.34) 19.0 12.49 (15.2) 7.8 

48 VA Complaint 3 0.31 (0.46) 0.2 0.36 (0.36) 20.3 10.75 (14.26) 9.4 

49 AL Complaint 3 0.21 (0.21) 0.2 0.33 (0.33) 8.7 0.7 (0.77) 0.8 

50 AL Complaint 3 0.21 (0.21) 0.2 0.33 (0.33) 7.7 1 (1.27) 0.8 

51 AL Non-complaint 3 0.21 (0.21) 0.2 0.33 (0.33) 5.8 1.77 (2.58) 1.1 

ppb parts per billion ave average OA outdoor 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–11 
Appendix A–12 

Table A.6 Summary Statistics for Analyte Concentrations (ppb) Collected Using Passive Monitors in Indoor and 

Outdoor Air, by House 

Sulfur Dioxide Hydrogen Fluoride 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

 1 FL Complaint 3 1.38 (1.38) 1.4 0.88 (0.88) 0.9 

 2 FL Non-complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

 3 FL Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

 4 FL Complaint 3 1.29 (1.29) 1.3 0.82 (0.82) 0.8 

 5 FL Non-complaint 3 1.73 (2.65) 1.3 0.81 (0.81) 0.8 

 6 FL Complaint 3 1.36 (1.36) 1.4 0.87 (0.87) 0.9 

 7 FL Complaint 3 1.28 (1.28) NA 0.81 (0.81) NA 

 8 FL Non-complaint 3 1.37 (1.37) 1.4 0.87 (0.87) 0.9 

 9 FL Complaint 3 1.36 (1.36) 1.4 0.87 (0.87) 0.9 

10 FL Complaint 3 1.48 (1.48) 1.5 0.94 (0.94) 0.9 

11 FL Complaint 3 1.38 (1.38) 1.4 0.88 (0.88) 0.9 

12 FL Complaint 3 1.72 (1.72) 1.7 1.09 (1.09) 1.1 

13 FL Complaint 3 1.58 (1.58) 1.6 1 (1) 1.0 

14 FL Complaint 3 1.39 (1.39) 1.4 0.88 (0.88) 0.9 

15 FL Complaint 3 1.29 (1.29) 1.3 0.82 (0.82) 0.8 

16 FL Complaint 3 1.49 (1.49) 1.5 0.95 (0.95) 1.0 

17 FL Non-complaint 3 1.37 (1.37) 1.4 0.87 (0.87) 0.9 

18 FL Complaint 3 1.27 (1.27) NA 0.81 (0.81) NA 

19 FL Complaint 3 1.47 (1.47) 1.5 0.93 (0.93) 0.9 

20 FL Complaint 3 1.37 (1.37) 1.4 0.87 (0.87) 0.9 

21 FL Complaint 3 1.48 (1.48) 1.5 0.94 (0.94) 0.9 

22 FL Non-complaint 3 1.46 (1.46) 1.5 0.93 (0.93) 0.9 

23 FL Complaint 3 1.58 (1.58) 1.6 1 (1) 1.0 

24 FL Complaint 3 1.29 (1.29) 1.3 0.82 (0.82) 0.8 

25 FL Complaint 3 1.38 (1.38) 1.4 0.88 (0.88) 0.9 

26 FL Complaint 3 1.48 (1.48) 1.5 0.94 (0.94) 0.9 

27 FL Complaint 3 1.47 (1.47) 1.5 0.93 (0.93) 0.9 

28 FL Complaint 3 1.56 (1.56) 1.6 0.99 (0.99) 1.0 

29 LA Complaint 3 1.46 (1.46) 1.5 0.92 (0.92) 0.9 

30 LA Complaint 2 1.36 (1.36) 1.4 0.87 (0.87) 0.9 

31 LA Complaint 3 1.46 (1.46) 1.5 0.92 (0.92) 0.9 

32 LA Complaint 3 1.45 (1.45) 1.5 0.92 (0.92) 0.9 

33 LA Non-complaint 3 1.45 (1.45) 1.5 0.92 (0.92) 0.9 

34 LA Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

35 LA Non-complaint 3 1.34 (1.34) 1.3 0.85 (0.85) 0.9 

36 LA Complaint 3 1.35 (1.35) 1.4 0.86 (0.86) 0.9 

37 LA Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

38 LA Complaint 3 1.34 (1.34) 1.3 0.85 (0.85) 0.9 

39 MS Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

40 MS Complaint 3 1.35 (1.35) 1.4 0.86 (0.86) 0.9 

41 VA Complaint 3 1.46 (1.46) 1.5 0.93 (0.93) 0.9 

42 VA Non-complaint 3 1.47 (1.47) NA 0.93 (0.93) NA 

43 VA Complaint 3 1.39 (1.39) NA 0.89 (0.89) NA 

44 VA Complaint 3 1.46 (1.46) 1.5 0.92 (0.92) 0.9 

45 VA Complaint 3 1.48 (1.48) 1.5 0.94 (0.94) 0.9 

46 VA Non-complaint 3 1.45 (1.45) 1.5 0.92 (0.92) 0.9 

47 VA Complaint 3 1.38 (1.38) 1.4 0.88 (0.88) 0.9 

48 VA Complaint 3 1.46 (1.46) 1.5 0.93 (0.93) 0.9 

49 AL Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

50 AL Complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

51 AL Non-complaint 3 1.36 (1.36) 1.4 0.86 (0.86) 0.9 

ppb parts per billion ave average OA outdoor 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 
Table A.7 Volatile Organic Compound Concentrations (μg/m3

) in Indoor Air by House Status 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

1,1,1-Trichloroethane Complaint 6.6 0.16 0.06 0.07 0.08 0.08 1.2

Non-complaint 0 NA NA NA NA NA NA

1,1,2,2-Tetrachloroethane Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,1,2-Trichloroethane Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,1,2- Complaint 95.6 0.57 0.06 0.51 0.57 0.64 0.74

Trichlorotrifluoroethane Non-complaint 85 0.56 0.14 0.49 0.67 0.73 0.78

1,1-Dichloroethane Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,1-Dichloroethene Complaint 2.2 0.09 0.06 0.06 0.08 0.08 0.33

Non-complaint 0 NA NA NA NA NA NA

1,2,4-Trichlorobenzene Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,2,4-Trimethylbenzene Complaint 70.3 6.97 0.31 2.58 5.01 9.48 28.83

Non-complaint 65 5.44 0.62 0.93 5.05 6.42 14.17

1,2-Dibromo-3- Complaint 0 NA NA NA NA NA NA

chloropropane Non-complaint 0 NA NA NA NA NA NA

1,2-Dibromoethane Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,2-Dichloro-1,1,2,2- Complaint 2.2 0.52 0.31 0.32 0.38 0.4 3.96

tetrafluoroethane (CFC 114) Non-complaint 0 NA NA NA NA NA NA

1,2-Dichlorobenzene Complaint 3.3 0.09 0.06 0.06 0.08 0.08 0.27

Non-complaint 0 NA NA NA NA NA NA

1,2-Dichloroethane Complaint 62.6 3.04 0.06 0.29 1.33 3.1 17.5

Non-complaint 60 1.67 0.06 0.32 0.77 0.91 6.32

1,2-Dichloropropane Complaint 9.9 0.11 0.06 0.07 0.08 0.11 0.37

Non-complaint 10 0.08 0.06 0.06 0.06 0.07 0.15

1,3,5-Trimethylbenzene Complaint 53.8 2.06 0.31 0.86 1.68 2.68 8.27

Non-complaint 45 1.54 0.31 0.31 1.45 1.75 3.88

1,3-Butadiene Complaint 15.4 0.41 0.06 0.07 0.08 0.13 8.15

Non-complaint 15 0.45 0.06 0.06 0.06 0.07 2

1,3-Dichlorobenzene Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

1,4-Dichlorobenzene Complaint 40.7 0.25 0.06 0.08 0.17 0.3 1.24

Non-complaint 20 0.1 0.06 0.07 0.08 0.1 0.17

1,4-Dioxane Complaint 3.3 0.43 0.31 0.33 0.38 0.4 0.93

Non-complaint 0 NA NA NA NA NA NA

2-Butanone (MEK) Complaint 95.6 7.88 0.31 4.51 5.73 10.5 29.5

Non-complaint 95 11.52 3.22 3.57 4.48 8.35 38

2-Hexanone Complaint 52.7 1.14 0.31 0.6 1.05 1.37 3.73

Non-complaint 60 1.05 0.31 0.8 1.03 1.16 1.95

2-Propanol (isopropyl Complaint 86.8 66.38 0.31 7.62 13.85 92.75 355

alcohol) Non-complaint 75 11.42 5.45 6.26 9.93 11.47 24

3-Chloro-1-propene (allyl Complaint 0 NA NA NA NA NA NA

chloride) Non-complaint 0 NA NA NA NA NA NA

4-Ethyltoluene Complaint 51.6 2.12 0.31 0.4 1.27 2.68 9.37

Non-complaint 45 1.68 0.31 0.31 1.6 1.82 4.37

4-Methyl-2-pentanone Complaint 52.7 1.92 0.31 0.51 1.07 2.02 17.17

Non-complaint 65 1.5 0.8 0.82 1.07 1.17 3.62

Acetone Complaint 94.5 112.17 3.05 64.75 115 155 220

Non-complaint 85 74.75 41.5 55.9 80.67 85 110.67

Appendix A–13 
Table A.7 Continued 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Acetonitrile Complaint 81.8 134.03 0.36 58.25 107.54 233.33 265

Non-complaint 88.9 141.56 58 58 76.67 290 290

Acrolein Complaint 91.2 5.88 0.31 4.08 5.51 6.98 14.67

Non-complaint 95 4.38 1.62 2.77 5.5 5.87 6.13

Acrylonitrile Complaint 3.3 0.47 0.31 0.32 0.38 0.4 2.37

Non-complaint 0 NA NA NA NA NA NA

Benzene Complaint 94.5 5.88 0.06 1.38 2.92 7.85 30.83

Non-complaint 85 4.27 0.27 0.4 2.07 4.45 14.17

Benzyl chloride Complaint 1.1 0.08 0.06 0.07 0.08 0.08 0.19

Non-complaint 0 NA NA NA NA NA NA

Bromodichloromethane Complaint 29.7 0.53 0.06 0.08 0.12 0.38 2.41

Non-complaint 50 0.29 0.08 0.1 0.23 0.43 0.62

Bromoform Complaint 4.4 0.48 0.31 0.32 0.38 0.4 1.85

Non-complaint 0 NA NA NA NA NA NA

Bromomethane Complaint 16.5 0.14 0.06 0.07 0.08 0.1 0.59

Non-complaint 25 0.19 0.06 0.06 0.08 0.29 0.47

Carbon disulfide Complaint 54.9 1.76 0.31 0.52 1.31 2.3 9.1

Non-complaint 25 0.57 0.31 0.31 0.39 0.69 1.15

Carbon tetrachloride Complaint 94.5 0.61 0.06 0.48 0.57 0.67 1.23

Non-complaint 85 0.48 0.13 0.45 0.59 0.62 0.62

Chlorobenzene Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

Chloroethane Complaint 1.1 0.08 0.06 0.06 0.08 0.08 0.19

Non-complaint 5 0.07 0.06 0.06 0.06 0.07 0.08

Chloroform Complaint 80.2 1.9 0.06 0.32 1.01 2.55 9.23

Non-complaint 70 1.08 0.3 0.43 1.06 1.66 1.97

Chloromethane Complaint 93.4 1.19 0.06 0.72 0.87 1.1 9.67

Non-complaint 70 0.47 0.06 0.19 0.53 0.68 0.88

Cumene Complaint 14.3 0.63 0.31 0.36 0.39 0.76 2.62

Non-complaint 15 0.5 0.31 0.31 0.37 0.39 1.11

Cyclohexane Complaint 56 2 0.31 0.86 1.26 2.08 8.97

Non-complaint 35 0.91 0.31 0.37 0.56 1.17 2.13

Dibromochloromethane Complaint 17.6 0.21 0.06 0.07 0.08 0.19 1.66

Non-complaint 0 NA NA NA NA NA NA

Dichlorodifluoromethane Complaint 96.7 3.4 0.31 2.43 2.78 2.95 16.75

(CFC 12) Non-complaint 85 2.31 0.64 2.23 2.65 2.9 3.12

Ethanol Complaint 90.1 1106.18 3.05 131.67 389.17 1450 5066.67

Non-complaint 80 362.61 100.5 235.9 328.33 421.67 726.67

Ethyl acetate Complaint 71.4 10.22 0.31 1.88 4.88 9.82 58

Non-complaint 75 7.51 2.09 3.37 6.23 6.35 19.5

Ethylbenzene Complaint 65.9 6.4 0.31 1.68 5.04 7.6 24.67

Non-complaint 60 4.47 0.59 1.09 4.47 6.27 9.95

Hexachlorobutadiene Complaint 0 NA NA NA NA NA NA

Non-complaint 0 NA NA NA NA NA NA

Methyl methacrylate Complaint 2.2 0.55 0.31 0.36 0.39 0.77 1.88

Non-complaint 0 NA NA NA NA NA NA

Methyl tert-Butyl Ether Complaint 7.7 0.14 0.06 0.06 0.08 0.08 0.82

Non-complaint 5 0.07 0.06 0.06 0.07 0.08 0.09

Methylene chloride Complaint 16.5 0.78 0.31 0.32 0.39 0.49 4.65

Non-complaint 30 1.3 0.31 0.31 0.31 2.58 3

Naphthalene Complaint 54.9 1.86 0.12 0.75 1.13 2.33 7.28

Non-complaint 65 3.46 0.92 1.28 2.45 2.7 9.94

Appendix A–14 
Appendix A–15 

Table A.7 Continued 

Component Status 

Pct 

Detect Mean Min p25 Median p75 Max 

Propene Complaint 60.4 12.39 0.31 0.4 2.75 15.65 77.33

Non-complaint 75 9.75 1.45 2.09 2.28 2.75 40.17

Styrene Complaint 71.4 3.53 0.31 1.81 2.98 4.28 10

Non-complaint 65 1.85 0.52 1.28 1.47 1.68 4.28

Tetrachloroethene Complaint 49.5 0.76 0.06 0.08 0.22 0.84 4.75

Non-complaint 70 11.14 0.13 0.19 1.97 2.1 51.33

Tetrahydrofuran (THF) Complaint 57.1 2.05 0.31 0.41 1.1 2.03 13.67

Non-complaint 20 10.35 0.31 0.31 0.37 1.27 49.5

Toluene Complaint 91.2 32.77 0.31 14.17 21.03 42 124.67

Non-complaint 70 20.91 1.62 5.45 21.67 28 47.83

Trichloroethene Complaint 17.6 0.55 0.06 0.07 0.08 0.12 7.1

Non-complaint 45 0.33 0.07 0.1 0.14 0.15 1.18

Trichlorofluoromethane Complaint 96.7 1.4 0.06 1.25 1.42 1.55 2.2

Non-complaint 85 1.14 0.25 1.18 1.3 1.4 1.55

Vinyl acetate Complaint 16.5 5.27 3.05 3.73 3.92 5.43 17.17

Non-complaint 35 5.83 3.08 3.91 4.12 6.77 11.26

Vinyl chloride Complaint 3.3 0.09 0.06 0.07 0.08 0.08 0.22

Non-complaint 0 NA NA NA NA NA NA

α-Pinene Complaint 86.8 88.47 0.31 36.25 77.58 116.67 235

Non-complaint 80 53.08 7.92 30.67 52.33 83.83 90.67

cis-1,2-Dichloroethene Complaint 1.1 0.08 0.06 0.07 0.08 0.08 0.19

Non-complaint 0 NA NA NA NA NA NA

cis-1,3-Dichloropropene Complaint 12.1 0.87 0.31 0.32 0.38 0.48 7.32

Non-complaint 0 NA NA NA NA NA NA

d-Limonene Complaint 79.1 25.86 0.31 15 24.63 39.5 57

Non-complaint 65 12.09 5.09 7.2 14.83 15.17 18.17

m,p-Xylenes Complaint 81.3 20.5 0.31 6.93 14.46 24.17 82.5

Non-complaint 65 14.46 1.92 2.92 14.63 19.5 33.33

n-Butyl acetate Complaint 72.5 4.87 0.31 1.68 3.22 5.07 26.33

Non-complaint 65 2.7 0.54 1.81 3.05 3.17 4.95

n-Heptane Complaint 67 4.66 0.31 1.55 3.03 5.9 25.67

Non-complaint 50 3.05 0.31 0.61 1.08 3.38 9.85

n-Hexane Complaint 72.5 10.28 0.31 1.05 5.08 12.65 71.33

Non-complaint 50 6.14 0.31 0.47 1.62 9.15 19.17

n-Nonane Complaint 64.8 2.3 0.31 1.1 1.44 2.97 8.43

Non-complaint 45 1.19 0.31 0.57 0.66 1.27 3.12

n-Octane Complaint 71.4 2.25 0.31 1.25 1.6 2.23 12.67

Non-complaint 70 1.91 0.42 0.77 1.05 2.05 5.27

n-Propylbenzene Complaint 44 1.26 0.31 0.39 0.85 1.55 5.32

Non-complaint 40 0.94 0.31 0.31 0.79 0.94 2.35

o-Xylene Complaint 67 7.34 0.31 1.43 5.23 9.09 27.83

Non-complaint 65 4.69 0.83 1.07 4.93 5.07 11.53

trans-1,2-Dichloroethene Complaint 6.6 0.34 0.06 0.07 0.08 0.08 6.3

Non-complaint 0 NA NA NA NA NA NA

trans-1,3-Dichloropropene Complaint 12.1 0.74 0.31 0.32 0.38 0.48 5.17

Non-complaint 0 NA NA NA NA NA NA

μg/m3 micrograms per cubic meter 

pct percent 

min minimum 

p percentile 

max maximum 
Table A.8 Summary Statistics for Acid Concentrations (ppb) in Indoor and Outdoor Air, by House 

Acetic Acid Formic Acid Hydrofluoric Acid 

No. State Status n 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

Indoor 

Ave (Max) OA 

1 FL Complaint 3 19.7 (28.0) 5.5 4.2 (4.3) 4.6 20.5 (21.0) 22.5 

2 FL Non-complaint 3 47.7 (51.0) 4.8 4.1 (4.2) 4.2 22.3 (26.5) 20.0 

3 FL Complaint 3 59.7 (66.0) 5.0 4.3 (4.5) 4.5 20.3 (20.5) 21.0 

4 FL Complaint 3 42.0 (61.0) 4.8 3.9 (4.0) 4.2 19.5 (20.5) 19.0 

5 FL Non-complaint 3 69.3 (71.1) 5.5 6.5 (8.0) 4.9 18.2 (19.0) 19.5 

6 FL Complaint 3 15.0 (16.0) 4.7 3.9 (4.0) 4.1 19.3 (19.5) 20.0 

7 FL Complaint 3 440.0 (510.0) 4.2 23.7 (26.0) 3.7 93.7 (110.0) 18.0 

8 FL Non-complaint 3 16.7 (17.9) 4.9 4.1 (4.3) 4.2 19.6 (20.3) 21.5 

9 FL Complaint 3 65.3 (81.0) 160.0 3.8 (3.8) 4.1 18.7 (19.0) 20.5 

10 FL Complaint 3 28.5 (34.4) 16.0 4.1 (4.3) 4.0 19.2 (19.5) 18.5 

11 FL Complaint 3 90.0 (94.0) 4.6 6.7 (8.4) 4.0 18.8 (19.0) 19.5 

12 FL Complaint 3 57.5 (59.0) 4.5 3.9 (4.0) 3.9 19.7 (20.5) 20.0 

13 FL Complaint 3 46.4 (50.0) 4.3 3.7 (3.8) 3.8 18.3 (18.5) 18.0 

14 FL Complaint 3 42.3 (44.0) 4.5 3.7 (3.8) 3.9 18.3 (18.5) 18.0 

15 FL Complaint 3 32.3 (35.0) 4.5 4.1 (4.2) 3.9 19.7 (20.0) 19.5 

16 FL Complaint 3 34.3 (37.0) 4.2 3.8 (3.9) 3.6 18.7 (19.0) 18.5 

17 FL Non-complaint 3 36.0 (37.0) 5.0 3.9 (4.0) 4.4 19.6 (20.0) 22.0 

18 FL Complaint 3 41.3 (61.2) 4.6 5.4 (8.2) 4.0 18.8 (19.0) 19.5 

19 FL Complaint 3 26.7 (35.0) 4.9 4.5 (5.5) 4.3 19.8 (20.5) 20.0 

20 FL Complaint 3 80.2 (83.3) 4.5 4.0 (4.1) 3.9 19.5 (20.0) 19.5 

21 FL Complaint 3 40.7 (42.0) 4.9 4.0 (4.1) 4.3 19.2 (20.5) 20.5 

22 FL Non-complaint 3 61.9 (68.0) 4.5 3.9 (4.0) 3.9 18.8 (19.0) 19.5 

23 FL Complaint 3 9.1 (13.0) 4.6 4.0 (4.1) 4.1 19.1 (20.0) 24.5 

24 FL Complaint 3 46.3 (50.0) 4.9 10.0 (12.0) 4.4 19.7 (20.0) 19.5 

25 FL Complaint 3 33.3 (41.0) 5.0 7.4 (14.0) 4.4 19.4 (19.5) NA 

26 FL Complaint 3 115.0 (130.0) 4.6 18.7 (24.0) 4.1 22.6 (27.0) 19.5 

27 FL Complaint 3 58.3 (68.0) 5.0 4.2 (4.3) 4.4 16.4 (19.5) 19.0 

28 FL Complaint 3 153.0 (180.0) 4.9 18.0 (22.0) 4.4 20.6 (21.5) 23.5 

29 LA Complaint 3 54.5 (58.2) 4.5 10.7 (12.0) 4.0 18.8 (19.0) 6.5 

30 LA Complaint 3 118.9 (139.9) 4.8 26.8 (32.0) 4.2 19.0 (19.5) 19.0 

31 LA Complaint 3 226.3 (239.0) 4.6 23.6 (27.9) 4.1 18.4 (18.8) 23.5 

32 LA Complaint 3 231.6 (350.0) 360.0 34.7 (51.0) 46.0 33.2 (41.0) 19.5 

33 LA Non-complaint 3 120.0 (130.0) 4.7 13.3 (14.0) 4.2 18.8 (19.0) 19.5 

34 LA Complaint 0 NA NA NA NA NA NA

35 LA Non-complaint 3 43.0 (44.0) 4.5 14.0 (15.0) 4.0 18.6 (19.0) 18.5 

36 LA Complaint 3 276.8 (360.2) 4.3 25.0 (33.0) 3.8 47.3 (56.0) 18.5 

37 LA Complaint 3 42.3 (51.0) 4.5 14.0 (16.0) 4.0 18.8 (19.0) 19.0 

38 LA Complaint 0 NA NA NA NA NA NA

39 MS Complaint 3 82.6 (100.0) 4.7 9.5 (14.0) 4.2 20.3 (21.0) NA 

40 MS Complaint 3 42.3 (46.0) 19.0 4.0 (4.1) 4.1 19.0 (19.5) 20.5 

41 VA Complaint 3 209.8 (249.0) 4.7 21.3 (31.2) 4.1 41.9 (53.7) 19.5 

42 VA Non-complaint 3 42.0 (48.0) NA 5.6 (8.6) NA 16.2 (19.0) NA 

43 VA Complaint 3 216.6 (270.0) 4.4 17.3 (24.0) 3.9 40.5 (56.1) 18.5 

44 VA Complaint 3 117.2 (149.9) 4.5 13.3 (16.0) 4.0 19.7 (20.0) 18.5 

45 VA Complaint 3 232.9 (258.8) 4.3 12.5 (14.0) 3.8 48.0 (53.0) 19.0 

46 VA Non-complaint 3 136.7 (140.1) 5.0 12.0 (12.0) 4.5 19.8 (20.8) 20.5 

47 VA Complaint 3 203.9 (230.9) 4.0 21.1 (23.1) 3.6 44.7 (47.2) 18.5 

48 VA Complaint 3 76.3 (89.0) 4.5 12.6 (16.0) 4.0 19.3 (21.0) 19.0 

49 AL Complaint 3 88.0 (120.1) 4.5 17.4 (24.0) 4.0 18.8 (19.5) 18.5 

50 AL Complaint 3 73.7 (100.0) 4.5 19.0 (24.0) 4.0 19.8 (20.0) 18.0 

51 AL Non-complaint 3 98.3 (120.0) 4.7 19.7 (24.0) 4.2 18.7 (19.5) 19.0 

ppb parts per billion ave average OA outdoor air 

n number of samples max maximum 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–16 
Table A.9 Summary Statistics for House Average, Short-Term Air Exchange Rate, by House 

No State Status Air Exchange Rate per Hour 

1 FL Complaint 0.22 

2 FL Non-complaint 0.23 

3 FL Complaint 0.19 

4 FL Complaint 0.24 

5 FL Non-complaint 0.19 

6 FL Complaint 0.15 

7 FL Complaint 0.13 

8 FL Non-complaint 0.32 

9 FL Complaint 0.19 

10 FL Complaint 0.16 

11 FL Complaint 0.2 

12 FL Complaint 0.16 

13 FL Complaint 0.2 

14 FL Complaint 0.33 

15 FL Complaint 0.19 

16 FL Complaint 0.06 

17 FL Non-complaint NA 

18 FL Complaint 0.18 

19 FL Complaint NA 

20 FL Complaint 0.13 

21 FL Complaint 0.28 

22 FL Non-complaint 0.13 

23 FL Complaint 0.26 

24 FL Complaint 0.05 

25 FL Complaint 0.1 

26 FL Complaint 0.09 

27 FL Complaint 0.14 

28 FL Complaint 0.12 

29 LA Complaint 0.14 

30 LA Complaint 0.12 

31 LA Complaint 0.19 

32 LA Complaint 0.13 

33 LA Non-complaint 0.24 

34 LA Complaint NA 

35 LA Non-complaint 0.23 

36 LA Complaint 0.17 

37 LA Complaint 0.46 

38 LA Complaint 0.63 

39 MS Complaint 0.18 

40 MS Complaint 0.2 

41 VA Complaint 0.18 

42 VA Non-complaint 0.28 

43 VA Complaint 0.08 

44 VA Complaint NA 

45 VA Complaint 0.8 

46 VA Non-complaint 0.27 

47 VA Complaint 0.12 

48 VA Complaint 0.2 

49 AL Complaint 0.42 

50 AL Complaint 0.16 

51 AL Non-complaint 0.46 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A-17 
Table A.10 Summary Statistics for Indoor Air Temperature and Dew Point, by House 

Temperature—Fahrenheit Dew Point—Fahrenheit 

No State Status n Average Range Average Range 

1 FL Complaint 3 78.3 77.3 – 79.0 56.3 55.9 – 56.6 

2 FL Non-complaint 3 79.9 78.8 – 81.3 61.5 60.4 – 62.4 

3 FL Complaint 3 78.2 77.6 – 78.8 60.3 60.2 – 60.6 

4 FL Complaint 3 80.6 78.1 – 83.8 64.8 58.2 – 75.6 

5 FL Non-complaint 2 78.1 75.9 – 80.3 59.8 58.3 – 61.3 

6 FL Complaint 2 75.2 74.1 – 76.2 58.0 57.8 – 58.2 

7 FL Complaint 2 86.8 85.5 – 88.1 74.5 74.2 – 74.8 

8 FL Non-complaint 2 76.0 75.6 – 76.5 54.6 54.1 – 55.0 

9 FL Complaint 3 78.2 77.8 – 78.3 62.1 61.2 – 63.4 

10 FL Complaint 2 78.1 77.5 – 78.6 55.4 54.7 – 56.1 

11 FL Complaint 2 77.2 76.9 – 77.6 66.3 66.1 – 66.5 

12 FL Complaint 2 77.0 76.6 – 77.3 54.5 54.0 – 55.0 

13 FL Complaint 2 84.2 83.7 – 84.6 64.5 64.4 – 64.6 

14 FL Complaint 2 80.1 79.9 – 80.3 58.8 58.1 – 59.6 

15 FL Complaint 2 73.5 73.2 – 73.8 54.9 53.4 – 56.4 

16 FL Complaint 2 79.3 79.0 – 79.6 58.6 57.7 – 59.5 

17 FL Non-complaint 2 72.4 72.0 – 72.8 52.8 51.7 – 53.9 

18 FL Complaint 2 76.9 76.2 – 77.6 53.7 50.6 – 56.8 

19 FL Complaint 2 79.4 79.1 – 79.7 53.2 52.2 – 54.3 

20 FL Complaint 2 83.6 82.4 – 84.8 63.5 63.2 – 63.9 

21 FL Complaint 2 77.1 77.1 – 77.2 56.9 56.5 – 57.3 

22 FL Non-complaint 2 81.1 80.2 – 81.9 60.2 58.8 – 61.7 

23 FL Complaint 2 78.1 77.9 – 78.2 51.6 51.3 – 52.0 

24 FL Complaint 3 76.6 75.6 – 77.9 54.5 54.3 – 54.7 

25 FL Complaint 3 77.2 75.4 – 78.8 54.8 54.5 – 55.1 

26 FL Complaint 3 84.5 83.8 – 85.8 68.9 68.7 – 69.1 

27 FL Complaint 3 79.5 78.7 – 80.4 63.2 61.6 – 64.0 

28 FL Complaint 3 83.2 82.7 – 83.5 64.8 64.4 – 65.5 

29 LA Complaint 3 76.5 76.3 – 76.6 56.5 56.1 – 56.8 

30 LA Complaint 2 74.6 74.0 – 75.1 55.6 55.5 – 55.8 

31 LA Complaint 3 77.2 76.6 – 78.3 60.2 59.5 – 60.9 

32 LA Complaint 3 84.3 83.1 – 84.9 70.3 70.2 – 70.5 

33 LA Non-complaint 3 73.1 70.2 – 76.5 55.0 51.6 – 60.0 

34 LA Complaint 2 72.7 72.3 – 73.0 54.8 54.4 – 55.2 

35 LA Non-complaint 2 75.1 75.0 – 75.2 55.0 54.6 – 55.4 

36 LA Complaint 2 86.4 85.3 – 87.5 72.8 71.9 – 73.8 

37 LA Complaint 2 72.1 69.4 – 74.9 55.0 53.6 – 56.5 

38 LA Complaint 2 86.5 86.3 – 86.8 72.5 72.2 – 72.8 

39 MS Complaint 2 75.9 75.4 – 76.4 56.7 55.2 – 58.2 

40 MS Complaint 2 72.4 71.4 – 73.3 50.5 50.5 – 50.6 

41 VA Complaint 2 75.7 75.5 – 76.0 63.5 61.3 – 65.6 

42 VA Non-complaint 3 72.4 71.7 – 73.4 59.9 59.4 – 60.4 

43 VA Complaint 2 77.6 75.8 – 79.3 62.8 62.7 – 62.9 

44 VA Complaint 3 76.9 76.4 – 77.4 61.3 59.8 – 62.7 

45 VA Complaint 2 80.1 79.7 – 80.5 63.4 63.3 – 63.4 

46 VA Non-complaint 3 71.4 70.9 – 72.0 62.3 61.8 – 63.0 

47 VA Complaint 2 74.9 74.8 – 75.0 58.2 58.1 – 58.2 

48 VA Complaint 3 71.6 69.7 – 73.3 54.2 53.3 – 56.0 

49 AL Complaint 2 73.8 73.5 – 74.1 51.3 50.8 – 51.8 

50 AL Complaint 2 77.1 74.8 – 79.5 55.9 53.2 – 58.6 

51 AL Non-complaint 2 76.2 75.3 – 77.2 57.6 56.1 – 59.1 

n number 

States: FL = Florida, LA = Louisiana, MS = Mississippi, VA = Virginia, AL = Alabama 

Appendix A–18 
APPENDIX B 

QUALITY ASSURANCE PROJECT PLAN 
INDOOR AIR QUALITY ASSESSMENT OF 

RESIDENCES CONTAINING CHINESE DRYWALL 

Quality Assurance Project Plan

EH&E-QAP-001 REV. NO.2:08/09 

________________________________________ August 10, 2009

John F. McCarthy, ScD, C.I.H / Project Executive Date 

________________________________________ August 10, 2009

William S. Wade / Quality Assurance Officer Date 

_________________________________________ August 10, 2009

Brian J. Baker / Project Manager Date 

Prepared By: 

Environmental Health & Engineering, Inc. 

117 Fourth Avenue 

Needham, MA 02494-2725 

August 10, 2009 

©2009 by Environmental Health & Engineering, Inc. 

All rights reserved 
TABLE OF CONTENTS 

1.0 INTRODUCTION...................................................................................................... 1

1.1 PROJECT DESCRIPTION AND GOALS ........................................................ 1

1.2 QUALITY ASSURANCE POLICY.................................................................... 1

1.3 QUALITY ASSURANCE ELEMENTS AND GOALS ....................................... 2

1.4 EH&E ORGANIZATION AND LINE OF AUTHORITY..................................... 3

2.0 STUDY DESIGN ...................................................................................................... 4

2.1 OVERVIEW OF IN-HOME STUDY ................................................................. 4

2.2 IN-HOME STUDY SCHEDULE ....................................................................... 5

3.0 MEASUREMENT QUALITY GOALS........................................................................ 8

3.1 PRECISION AND ACCURACY....................................................................... 8

3.2 REPRESENTATIVENESS .............................................................................. 8

3.3 RELIABILITY ................................................................................................... 9

3.4 COMPLETENESS........................................................................................... 9

4.0 PROJECT PLANNING ........................................................................................... 10

4.1 TRAINING OF PERSONNEL ........................................................................ 10

4.2 PREVENTATIVE MAINTENANCE................................................................ 10

5.0 DATA COLLECTION.............................................................................................. 12

5.1 MEASUREMENT PARAMETERS AND METHODS ..................................... 12

5.2 QUALITY CONTROL SAMPLES................................................................... 16

5.3 EQUIPMENT CALIBRATION ........................................................................ 17

5.4 CORRECTIVE ACTION ................................................................................ 19

5.5 INTEGRATED SAMPLE FLOW RATES ....................................................... 19

6.0 DOCUMENT MANAGEMENT................................................................................ 20

6.1 SAMPLE CUSTODY ..................................................................................... 20

6.2 RECORDKEEPING....................................................................................... 20

6.3 DATA ENTRY AND DATA REDUCTION ...................................................... 21

7.0 DATA VALIDATION ............................................................................................... 22

7.1 POST DATA REDUCTION............................................................................ 22

7.2 PRECISION AND ACCURACY..................................................................... 22

7.3 DATA COMPLETENESS .............................................................................. 23
TABLE OF CONTENTS (continued) 

LIST OF APPENDIX 

Appendix A Project Team Organization 

LIST OF TABLES 

Table 2.1 CPSC Study Environmental Monitoring Parameters 

Table 2.2 Schedule of Field Sampling and Inspection Activities for the CPSC In-home 

Study 

Table 5.1 Summary of Target Parameters, Passive Air Sampling 

Table 5.2 Quality Assurance, Quality Control Samples Collected During the Project 

Table 5.3 Equipment and Sensor Calibration 

LIST OF ABBREVIATIONS AND ACRONYMS

ASTM American Society for Testing and Materials 

CPSC Consumer Product Safety Commission 

CO2 carbon dioxide 

CV coefficient of variation 

DNPH 2,4-dinitrophenyl hydrazine 

EH&E Environmental Health & Engineering, Inc. 

EPA U.S. Environmental Protection Agency 

FOSC Field Operations Support Center 

FTIR Fourier transform infrared 

ml/min milliliters per minute 

NIOSH National Institute for Occupational Safety and Health 

NIST National Institute of Standards and Technology 

ppm parts per million 

QA quality assurance 

QAPP Quality Assurance Project Plan 

QA/QC quality assurance, quality control 

VOC volatile organic compound 

XRF x-ray fluorescence 

°C degrees Celsius 

°F degrees Fahrenheit 
1.0 INTRODUCTION 

1.1 PROJECT DESCRIPTION AND GOALS 

In December 2008, the Consumer Product Safety Commission (CPSC) began to receive 

drywall related complaints from consumers that included odors emanating from the 

drywall, corrosion of metal items inside the homes, and short-term health effects. 

Complaints have been received from consumers residing in many states and the District 

of Columbia; however; the majority of reports are from Florida, Louisiana, Mississippi, 

Alabama, and Virginia. The CPSC in conjunction with the U.S. Environmental Protection 

Agency (EPA), the Centers for Disease Control and Prevention (CDC), and the Agency 

for Toxic Substances and Disease Registry (ASTDR) initiated a multi-agency approach 

to investigate the drywall-related complaints. 

One component of this investigation is the implementation of an in-home study to 

investigate the relationship between indoor environmental conditions and imported 

drywall in residential buildings. Environmental Health & Engineering, Inc. (EH&E) is 

conducting this study on behalf of CPSC. The objective of the in-home study is to 

characterize the indoor environment in representative complaint homes to that of noncomplaint homes through air sampling and other objective measurements. The key 

objectives of the study will be to identify markers of imported drywall, measure select 

indoor air parameters of representative complaint and non-complaint homes, collect 

building characteristic metrics of complaint and non-complaint homes, evaluate 

corrosion in homes, and examine relationships among drywall properties, building 

characteristics, constituents of indoor air, and rates of corrosion. 

1.2 QUALITY ASSURANCE POLICY 

EH&E has prepared this Quality Assurance Project Plan (QAPP) to ensure the collection 

of quality data throughout all field collection and data reduction/analysis activities 

associated with the study. This plan is based upon full implementation of established 

policies and procedures and fully documented recordkeeping practices. These basic and 

established principles for data collection and data processing activities will insure 

uniformly reliable data from all homes included in the study. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 1 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
The policy of EH&E is that there shall be sufficient quality assurance (QA) to assure that 

the data collected and reported from all homes is of acceptable precision, accuracy, 

representativeness, and completeness. The policies stated in this plan define the QA 

activities that will be practiced by EH&E throughout the implementation of the in-home 

study. These policies have been established to ensure uniform and standardized data 

collection and data processing activities throughout the study. The policies are dynamic 

and will be reviewed, amended, deleted, or added to as needed to ensure acceptable 

data and to accommodate changes to study design. The policies listed in this QAPP will 

be implemented and adhered to by all EH&E project team members. 

1.3 QUALITY ASSURANCE ELEMENTS AND GOALS 

Obtaining quality data is crucial to the goals of the CPSC in-home study. The study will 

involve field activities that include the collection of data as well as data reduction 

activities to facilitate data analysis and reporting. The field activities will comprise the 

collection of various types of indoor air samples, quantitative assessments of corrosion, 

qualitative assessment of building component corrosion, and elemental analysis of 

select building materials. All data collected as part of the study will be stored in a central 

data repository at EH&E and specific quality assurance elements will be implemented 

and followed throughout all aspects of field and data reduction activities. 

The basic elements of EH&E’s QA program will include program planning, 

implementation, and assessment. 

• Program planning involves the process of identifying data quality objectives and will 

form the basis for the development of EH&E’s QAPP. 

• Program implementation involves the quality assurance quality control activities 

conducted for all field data collection and data reduction activities undertaken as part 

of the study. 

• Program assessment will be made based on the outcomes of data validation and 

verification procedures. Inputs to this assessment will include field measurement 

performance and data reporting verifications, and data review. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 2 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
To meet these basic elements, EH&E will rely on the following key concepts and 

activities. 

• Developing an appropriate project organization and responsibility structure. 

• Conducting field staff training to ensure consistent data collection activities 

• Ensuring that sample collection and analysis is conducted in accordance with 

appropriate sampling methods and procedures. 

• Adhering to consistent and specified calibration requirements, including traceability 

standards and schedules. 

• Conducting regularly scheduled preventive maintenance. 

• Implementing appropriate data reporting and data validation procedures. 

1.4 EH&E ORGANIZATION AND LINE OF AUTHORITY 

In order to meet the project objectives, EH&E selected qualified personnel to conduct the 

in-home study and its related quality assurance, quality control (QA/QC) procedures. 

Appendix A provides EH&E’s project organization and line of authority. 

The study will comprise in-home field activities to be conducted over an approximate 

eight week schedule with data reduction, verification, and analysis occurring in tandem. 

The field activities will be conducted by two three person field teams chosen for his/her 

expertise in the areas of air sampling, building heating ventilating and air-conditioning 

(HVAC) assessment, field study management, and communications. Prior to the 

commencement of the field study, EH&E will conduct training sessions with field team 

members to ensure consistency among field data collection techniques and procedures. 

Field team members will be instructed to follow methods described in study sampling 

protocols and associated methods for each measurement parameter. 

Non field personnel will comprise the project QA Officer, equipment, media and supply 

support personnel and data entry support personnel. Non field personnel will be equally 

responsible for ensuring data quality with respect to the QAPP through project specific 

training and procedural documents. Note that the QA Officer will remain independent of 

the field and non-field personnel for the duration of the project. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 3 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
2.0 STUDY DESIGN 

The study design will compose integrated measures of corrosion and odor, measurements 

of gases in indoor and outdoor air, characterization of drywall, and the collection of 

building characteristics. An overview of the field activities are described below. 

2.1 OVERVIEW OF IN-HOME STUDY 

Measures of corrosion rates will be obtained through the use of copper and silver coupons 

placed at locations within each home. The coupons will be exposed to indoor air for 

approximately two weeks and rates of corrosion will be quantified. Evidence of existing 

corrosion in each home will be made from an inspection of copper ground wires in 

accessible electrical outlets and other accessible metal objects. Field personnel will record 

the presence of malodors in homes as an additional measure of impact. 

Measurements of indoor and outdoor air will be obtained through active and passive air 

sampling. A summary of the types of air samples to be obtained and the anticipated 

sampling duration in each home is provided in Table 2.1. 

Table 2.1 CPSC Study Environmental Monitoring Parameters 

Monitoring Parameter Sampling Duration 

Volatile organic compounds (active) 120 minutes 

Aldehydes (active) 200 minutes 

Inorganic acids (active) 200 minutes 

Organic acids (active) 200 minutes 

Reduced sulfur compounds Grab sample 

Sulfur dioxide (passive) 2 weeks 

Aldehydes (passive) 2 weeks 

Hydrogen sulfide (passive) 2 weeks 

Ozone (passive) 2 weeks 

Hydroflouric acid (passive) 2 weeks 

Nitrogen dioxide (passive) 2 weeks 

The study will evaluate selected elemental and mineral characteristics of drywall in the test 

homes through the use of x-ray fluorescence (XRF) and Fourier transform infrared (FTIR) 

spectroscopy. XRF methods will be employed in the field to characterize the amount of 

imported and domestic drywall in homes. In addiotn, a combination of XRF and FTIR 

analysis will occur at EH&E’s facility by analyzing bulk samples collected from each home. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 4 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Physical attributes and other indoor air quality parameters will be obtained including 

building floor area, ventilation design, air exchange rate, temperature, and relative 

humidity. A visual inspection of the home and baseline questionnaire will also be 

conducted including an inspection to document general home construction related 

characteristics and the visual assessment of corrosion. 

2.2 IN-HOME STUDY SCHEDULE 

The field activities in each home will be completed during two site visits to the home. On 

the first site visit, field activities will be completed by a three person team over the course 

of an anticipated nine to ten hour visit (~8:00 a.m. to 5:00 p.m.) The second site visit will 

occur approximately two weeks after the first by a single field investigator. The anticipated 

sequence of activities to be completed in each home are described below and 

summarized in the daily activity schedule provided as Table 2.2. 

Table 2.2 Schedule of Field Sampling and Inspection Activities for the CPSC In-home Study 

Day 1 

8:00 – 8:30 a.m. • Arrive at test home to unpack, setup and calibrate equipment. 

8:30 – 9:00 a.m. • Select three indoor and one outdoor air sampling locations 

• Setup and start continuous temperature and relative humidity monitors 

• Setup active air monitoring equipment for volatile organic compounds, 

aldehydes, organic and inorganic acids 

9:00 – 11:00 a.m. • Start active air sampling 

• Begin home inspection and questionnaire 

• Begin XRF analyzer wall survey 

11:00 a.m. – 

12:00 p.m. 

• End active air sampling 

• Begin bulk sampling of drywall from of areas behind electrical outlet 

switch plates 

• Setup and start continuous carbon dioxide monitors 

• Begin carbon dioxide release throughout the home (air exchange rate 

assessment) 

1:00 – 3:00 p.m. • Continue and complete home inspection activities and questionnaire 

• Continue and complete XRF wall scanning survey 

• Continue and complete drywall bulk sampling of areas behind electrical 

outlet switch plates 

3:00 – 4:00 p.m. • Setup and start passive air sampling equipment for sulfur dioxide, 

nitrogen dioxide, hydrogen fluoride, hydrogen sulfide, aldehydes, and 

ozone 

• Setup and expose silver and copper coupons 

4:00 – 5:00 p.m. • Collect reduced sulfur samples 

5:00 p.m. • Depart the test home 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 5 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Table 2.2 Continued 

Day 12 to 15 

Time varies • Collect passive air samplers 

• Collect temperature and relative humidity monitors 

• Collect silver and copper coupons 

XRF x-ray fluorescence 

Field personnel will arrive at each home at approximately 8:00 a.m. and began the 

unpacking, set-up, and calibration of equipment. Once inside the home, the field 

personnel will select the indoor and outdoor locations where all active and passive 

environmental sampling and monitoring are to be conducted. Following the selection of 

the indoor sites, temperature and relative humidity monitors are to be placed at two or 

three of the locations (depending on the characteristics of the home) and set to 

continuously log conditions over the course of the two week monitoring period. 

 

At 9:00 a.m. active air sampling equipment will be set up at the indoor locations and at 

the outdoor location to measure volatile organic compounds (VOCs), aldehydes, 

inorganic acids, and organic acids. VOC samplers will be set up in two or three indoor 

locations with one duplicate, and at one outdoor location. One field blank will be included 

for every ten samples. Similarly, aldehydes, inorganic acids, and organic acids are to be 

collected at three indoor locations with one duplicate and one field blank or media blank. 

The active air sampling systems will be started at approximately 9:00 a.m. and sampled 

for approximately 200 minutes. While active air samples are being collected, field 

personnel will survey walls in the home using a handheld XRF analyzer. During this 

time, field personnel will also initiate a visual home inspection to document general 

home construction related characteristics, a visual assessment for corrosion, and the 

questionnaire. 

Once the active air sampling is completed, field personnel will collect small bulk samples 

of wall board from behind the cover plates of light switches and electrical boxes. In 

addition, at each of the light switch and electrical boxes where bulk samples are 

collected, field personnel will document the condition of the copper electrical ground in 

terms of the level of corrosion identified. The drywall at each of these locations will also 

be scanned utilizing a handheld XRF analyzer. Following the completion of active air 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 6 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
sampling, the home air exchange rate will be evaluated by releasing carbon dioxide 

(CO2) throughout the home and monitoring the decay in CO2 concentration over 

approximately four hours. CO2 monitors will be placed at the three indoor sampling 

locations and will continuously monitor the concentration of the gas over the test period. 

During afternoon hours, field personnel will complete the XRF wall survey, the home 

inspection/questionnaire, and the bulk sampling. Once CO2 monitoring is completed, 

passive air sampling equipment for sulfur dioxide (SO2), nitrogen dioxide (NO2) , 

hydrogen fluoride (HF), hydrogen sulfide (H2S), aldehydes, and ozone will be deployed. 

Passive air samplers will be placed at three indoor locations with one duplicate, one field 

blank or media blank and at one outdoor location. The passive air samplers will collect 

air from the various locations for approximately two weeks. 

To measure the integrated rate of corrosion, copper/silver coupons will be placed at the 

three indoor sampling locations, at one outdoor location, and at the outlet of a supply air 

diffuser for the air conditioning unit serving the home. Due to the anticipated limited 

availability of copper/silver coupon kits, duplicate samples will be collected at 

approximately five percent of the site locations. Sampling of reduced sulfur gases will be 

initiated late in the day in order to ensure that samples are received by the laboratory 

within 24 hours of the sample collection time. Samples of reduced sulfur gases will be 

obtained from the three indoor locations, with one duplicate, and from one outdoor 

location. 

A single field investigator will return to the home approximately two weeks following the 

date of the initial survey to collect the passive air samplers, temperature, and relative 

humidity monitors, and copper/silver coupons. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 7 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
3.0 MEASUREMENT QUALITY GOALS 

Collecting high quality data is critical to the success of the in-home study. The study 

design will involve the collection of indoor air samples and the characterization of drywall 

using field and laboratory measurement techniques. Assessing the quality of these data 

will consider precision, accuracy, representativeness, reliability, comparability, and 

completeness. A description of each is provided below and further discussed in specific 

sections of this QAPP. 

3.1 PRECISION AND ACCURACY 

Two central themes in the discussion of error analysis are the concepts of precision and 

accuracy. For application to environmental sampling, the definitions of accuracy and 

precision can be defined as follows: 

Accuracy—the degree of correctness with which a measurement reflects the true value 

of the parameter being assessed 

Precision—the degree of variation in repeated measurements of the same quantity of a 

parameter 

For example, if ten measurements for a given parameter are taken at the same time at 

the same location by the same method, the accuracy would be indicated by how well the 

average of the ten measurement results reflects the actual concentration present and 

the precision would be indicated by the variation in the results of the ten measurements. 

A high degree of precision and accuracy do not necessarily occur simultaneously in a 

process. Measurements may have a high degree of precision, while not being very 

accurate. Conversely, a set of data may have high accuracy but lack precision. When 

results are both precise and accurate, confidence in data quality is maximized. The 

assessments to be undertaken concerning the precision and accuracy of the in-home 

study data are discussed in Section 7.2. 

3.2 REPRESENTATIVENESS 

The objectives of the in-home study are to characterize potential imported drywallrelated constituents that may be present in the indoor air of complaint and non-complaint 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 8 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
homes. The data will be used to support the review of potential associations between 

these two home groups and may also be utilized to support human health risk 

assessment. Target homes participating in the study were selected by CPSC based on a 

number of factors including geography and reports of health effects and corrosion. The 

study population will comprise 50 single-family residential buildings made up of 

complaint homes and non-compliant homes. Non-complaint homes will be selected by 

CPSC and will be located geographically proximate to complaint homes such that they 

would have similar ambient conditions to that of the complaint homes. Non-complaint 

homes will have similar attributes to the complaint homes including the period of 

construction, style of home, and floor area. 

3.3 RELIABILITY 

Reliability of an environmental monitoring plan is defined as the probability that the 

systems utilized will perform their intended function for a prescribed period of time under 

the operating conditions specified. Data interpretation depends to a great degree on data 

completeness for trend analysis and this demands continuous reliability in the 

operational systems. In order to ensure a sustained high degree of reliability, the 

following procedures will be followed: 

• Only highly reliable equipment will be used. 

• Incoming equipment will be inspected and tested for adherence to specifications 

prior to acceptance. 

• Control, whenever and wherever possible, of environmental operating factors which 

can influence the reliability of the measurement systems. 

• Adequate training of operating and supervisory personnel will be provided through 

on-the-job training, and in-house training sessions. 

• Preventive maintenance will be provided to reduce and minimize equipment failure. 

3.4 COMPLETENESS 

The completeness of air sampling data from the study will be evaluated by examining 

overall data capture efficiency for field measurements. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 9 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
4.0 PROJECT PLANNING 

4.1 TRAINING OF PERSONNEL 

Personnel involved in any function affecting data quality (sample collection, analysis, 

data reduction, and quality control) will have sufficient training in their appointed roles to 

contribute to the reporting of complete, comparable, representative, precise, and 

accurate environmental monitoring data. The Project Manager will insure that the 

required training is available for all personnel involved in the study. 

Training objectives will be to develop personnel to the necessary level of knowledge and 

skill required for proper operation of the environmental monitoring equipment and 

performance of the necessary inspectional activities. Primary methods of training that 

wiil be utilized by EH&E will include the following: 

• On-the-job training will comprise 

– Observing an experienced operator performing the function 

– Understanding of the QAPP and operating procedures 

– Use of the QAPP and operating procedures as guides to the operations 

– Performing the operation under the direct supervision of an experienced operator 

– Independent performance of the operations with a high level of quality control 

• Internal training will consist of completion of in-house training on project specific 

equipment and documentation prior to participation in field work. 

Evaluation of training will encompass the level of knowledge and skill achieved by the 

operator and the overall effectiveness of the training, including determination of areas in 

which the training program requires improvement. 

4.2 PREVENTATIVE MAINTENANCE 

Preventive maintenance is an orderly program of positive actions (equipment cleaning, 

lubricating, reconditioning, adjustment, and/or testing) designed to prevent failure of 

monitoring systems or parts thereof during use. The most important effect of a good 

preventive maintenance program is to increase measurement system reliability and thus 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 10 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
to increase data completeness. Preventive maintenance status of each piece of 

equipment will be confirmed prior to use. At a minimum, equipment used during the 

study will be subject to respective manufacturer’s recommended preventative 

maintenance recommendations. A record of preventive maintenance and service checks 

is maintained centrally at the EH&E Field Operations Support Center (FOSC). 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 11 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
5.0 DATA COLLECTION 

5.1 MEASUREMENT PARAMETERS AND METHODS 

Environmental samples and measurements will be collected in accordance with 

published standards and methods according to the schedule outlined in the in-home 

study protocol described in Section 2.2 of this QAPP. The following sampling and 

analytical procedures will be utilized. 

5.1.1 Source Drywall Measurements 

Material characteristics of drywall will be determined using a combination of XRF 

analysis (for metal analysis), and FTIR analysis (to determine the compounds present). 

The XRF Spectrometer (Innov-X ALPHATM Handheld XRF, Innov-X Systems, Inc., 

Woburn, Massachusetts) will provide on-site metals analysis in this study. This device is 

a handheld, tube-based, portable XRF analyzer and will be used to identify and quantify 

the elements in representative wall surfaces in each home as well as in the bulk samples 

collected from each home. 

FTIR measurements will be obtained using A2 Technologies Exoscan instrument, a full 

scanning Fourier Transform mid-infrared spectrometer, equipped with a Michelson 

interferometer and non-hydroscopic optics. The diffuse reflectance Exoscan will be 

configured for porous and rough surfaced materials. The FTIR will be employed to 

identify and profile spectra of the collected drywall samples. 

5.1.2 Reduced Sulfur Compounds 

Grab air samples will be collected and analyzed for a suite of twenty reduced sulfur 

compounds in accordance with American Society for Testing and Materials (ASTM) 

Method D5504 Standard Test Method for Determination of Sulfur Compounds in Natural 

Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence. Whole air 

samples will be collected into Tedlar Bags (Zefon International) using a SKC Vac-UChamberTM. All surfaces that come in contact with sample air will be constructed of 

stainless steel or Teflon tubing (SKC Cat. No. 231-940). The sampling pumps used to 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 12 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
fill/evacuate the chambers will be adjusted to a flow rate of 1000 milliliter per minute 

(ml/min). Sample analysis will be conducted by Columbia Analytical Services, Inc. 

located in Simi Valley, California. In accordance with recommendations outlined in the 

ASTM method, samples will be analyzed within 24 hours of collection. 

5.1.3 Volatile Organic Compounds 

Whole air samples for VOCs will be collected with individually cleaned and certified 

SUMMA canisters obtained from Columbia Analytical Services, Inc. located in Simi 

Valley, California. The flow controllers used to fill the SUMMA canisters during sampling 

will also be calibrated and conditioned by Columbia Analytical Services, Inc. on an 

individual basis. Flow controllers will be calibrated for two hour sample durations. VOC 

samples will be analyzed using gas chromatography/mass spectrometry (GC/MS). The 

analyses will be performed according to the methodology outlined in EPA Method TO-15 

from EPA’s Second Edition Compendium of Methods for the Determination of Toxic 

Organic Compounds in Ambient Air. 

5.1.4 Aldehydes (Active) 

Active air samples will be collected and analyzed according to EPA Method TO-11A for 

aldehydes, including formaldehyde, using 2,4-dinitrophenyl hydrazine (DNPH) coated 

sorbent tubes with a built-in ozone scrubber (SKC Cat. No. 226-120). Each tube will be 

connected to a personal sampling pump adjusted to a nominal flow rate of 500 ml/min. 

Analysis will be conducted by Columbia Analytical Services, Inc. in Simi Valley, 

California in accordance with EPA Method TO-11A, Determination of Formaldehyde in 

Ambient Air Using Adsorbent Cartridge Followed by High Performance Liquid 

Chromatography (HPLC). All sample media will be refrigerated before, during, and after 

sampling. 

5.1.5 Passive Diffusive Sampling 

Passive diffusion samples for analysis of sulfur dioxide, nitrogen dioxide, hydrofluoric 

acid, hydrogen sulfide, aldehydes, and ozone will be collected using Radiello Diffusive 

Sampling Systems. Specific system components included the diffusive body, supporting 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 13 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
plate, and chemiadsorbing cartridge. The type of passive sampling system and the 

analytical technique to be used for each class of analyte are summarized in Table 5.1 

Table 5.1 Summary of Target Parameters, Passive Air Sampling

Compound Analytical Method*

Aldehydes Aldehydes by Radiello 165, HPLC-UV 

Hydrogen sulfide Hydrogen sulfide by Radiello 170 Spectrophotometer at 665 nm 

Ozone Ozone by Radiello 172 Spectrophotometer at 430 nm 

Sulfur dioxide Sulfur dioxide by Radiello 166 Ion Chromatography 

Nitrogen dioxide Nitrogen dioxide by Radiello 166 Spectrophotometer at 537 nm 

Hydrofluoric acid Hydrofluoric acid by Radiello 166 Ion Chromatography 

HPLC high performance liquid chromatography 

UV ultra violet 

nm nanometer 

* Analytical methods provided by Fondazione Salvatore Laboratory, Radiello Manual, Supelco Edition. 

To achieve the desired limit of detection the sampling devices will be deployed for 13 to 

15 days in each of the test homes. All analysis of the diffusive sampling media will be 

conducted by Air Toxics LTD, located in Folsom, California. 

5.1.6 Inorganic and Organic Acids 

Air samples for analysis of targeted inorganic and organic acids will be collected using 

silica gel tubes (SKC Cat. No. 226-10-03) and personal sampling pumps set to draw at 

500 ml/min over the sampling period. Analysis for inorganic and organic acids will be 

conducted using ion chromatography (IC) according to National Institute for 

Occupational Safety and Health (NIOSH) Methods 7903 and 2011, respectively, by 

Liberty Mutual Industrial Hygiene Laboratory in Hopkinton, Massachusetts. 

5.1.7 Relative Humidity/Temperature 

Real-time temperature and relative humidity measurements will be collected in each 

home using U10-003 HOBO® Temperature Relative Humidity Data Loggers 

manufactured by Onset Computer Corporation, Bourne, Massachusetts. The 

temperature sensor is a thermistor and relative humidity is measured by a thin-film 

capacitive sensor. The temperature sensor has a range of -20 degrees Celsius (°C) to 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 14 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
70 °C (-4 to 158 degrees Fahrenheit [°F]) with accuracy of ± 0.4 °C at 25 °C (± 0.7 °F at 

77 °F). The sensor is factory rated to achieve a resolution of 0.1 °C at 25 °C (0.2 °F at 

77 °F). The relative humidity sensor has a range of 25% to 95% with accuracy of ± 3.5% 

from 25% to 85%. The sensor is factory rated to achieve a resolution of 0.07%. 

Temperature and relative humidity measurements will be collected for approximately 

13 – 15 days in each home.

5.1.8 Air Exchange Rate 

The air exchange rates in each test home will be measured in accordance with the test 

methods outlined in ASTM standard E741-00, Standard Test Method for Determining Air 

Change Rate in a Single Zone by Means of a Tracer Gas Dilution. CO2 will be utilized as 

the tracer gas and air exchange rates will be measured using the concentration decay 

test method as outlined in ASTM Standard E741-00. The tests will be conducted by 

introducing the CO2 tracer throughout the home and analyzing the decaying part of the 

tracer curve after all tracer is injected and allowed to mix within the home. 

CO2 concentrations will be measured continuously at multiple locations inside the home 

using a Q-Trak Model 8551 Indoor Air Quality Monitor, manufactured by TSI, Inc. (St. 

Paul, Minnesota). The CO2 sensor utilized by this monitor is non-dispersive infrared 

(NDIR) and is accurate within 3% (or 50 parts per million [ppm] at 25 °C [78 °F]) of the 

reading. Prior to each air exchange rate test, the sensors will be calibrated at zero using 

hydrocarbon free air and spanned to approximately 1,000 ppm of CO2. Air exchange 

rates will be calculated from the CO2 decay results using the regression method. 

5.1.9 Corrosion Assessment, Visual 

Detailed visual inspections will be performed on the air handling units, plumbing 

components, appliances, and electrical grounding wires. Notes will also be made 

regarding other home contents that could show visible evidence of corrosion. 

Grounding wires will be evaluated on a three point scale. A score of one will indicate no 

visible corrosion, two will indicate moderate visible corrosion and three will indicate 

significant visible corrosion. Field team members will perform cross reference 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 15 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
evaluations during training to ensure consistency between teams in the field. Visual 

corrosion ratings will be recorded in the master field log binder. 

Air handling unit inspection will focused on the cooling coils and associated copper 

refrigerant lines. Surfaces will be photographed and all locations will be logged into the 

master field log binder. Appliances and fixtures including accessible refrigerator 

components, hot water heaters, faucets, plumbing lines, and other items indicating 

patterns of corrosion will also be logged and photographed. 

5.1.10 Corrosion Assessment, Coupons 

Corrosion classification coupons will be employed to determine the integrated corrosion 

rate present in the study homes. Copper and silver coupons were supplied by Purafil, 

Inc., research and development laboratory in Doraville, Georgia. Copper and silver 

coupons will be placed at indoor locations and one outdoor location for an approximately 

two week period. At the end of the two week sampling period, the coupons will be 

collected, placed in sealed containers and returned to Purafil for analysis of the corrosive 

film that developed. The laboratory analysis will determine a corrosion reactivity rate by 

measuring the thickness of the copper sulfide film present and normalized it to 

“angstroms per 30 days of exposure” for each of the coupon surfaces. 

5.2 QUALITY CONTROL SAMPLES 

A number of samples will be collected and analyzed in each sample set to evaluate the 

quality and reasonableness of the data collected during the study. The types and 

frequency of QA/QC samples to be collected during the study are outlined in Table 5.2. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 16 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Table 5.2 Quality Assurance, Quality Control Samples Collected During the Project 

Sample Type Frequency Definition 

Duplicate sample Minimum of one per 

sample set and one 

per every 10 primary 

samples 

A sample collected concurrently with a primary 

field sample to assess repeatability of methods. 

Field blank Minimum of one per 

sample set and one 

per every 10 primary 

samples 

A sample prepared by the field team that 

represents the procedure for preparing for 

integrated sampling, and is handled as such, but 

is not actually used for sampling. This is sent in a 

blinded fashion to the laboratory. The results of 

the field blanks can be used to determine whether 

there was any contamination in the preparation, 

handling or shipping process in the field, or during 

the analysis of the samples by the laboratory. 

Shipping Blank Minimum of one per 

sample set and one 

per every 10 primary 

samples 

An unused sample that is not handled in the field 

other than to have it incorporated into a regular 

sample shipment and sent in a blind fashion to the 

laboratory. The results of shipping blanks can be 

used to determine whether there was any 

contamination during the shipping process. 

5.3 EQUIPMENT CALIBRATION 

Calibration procedures require the application of primary or secondary standards. The 

standards used for apparatus or materials will be certified as being traceable to 

standards of the National Institute for Standards and Technology (NIST) or some other 

recognized fundamental standard. Regardless of the type of calibration equipment or 

material, an effective QA program requires accuracy levels of these materials that are 

consistent with the method of analysis. The calibration policies and procedures set forth 

within this section will apply to all measuring and test equipment identified, including 

environmental sampling equipment, and measuring devices (e.g., rotameters, dry gas 

meters, temperature sensors, etc.). 

The calibration standards used will be referenced against higher-level, primary 

standards having unquestionable and higher accuracy. The higher-level standards will 

be certified by the NIST or another recognized organization or derived from accepted 

values of physical or chemical constants. Calibration gases purchased from commercial 

vendors normally contain a certificate of analysis. Whenever a certified gas is available 

from the NIST, commercial gas vendors will be requested to establish traceability of the 

certificate of analysis. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 17 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Measuring equipment, test equipment, and calibration standards will be calibrated in an 

area that provides control of environmental conditions to the degree necessary to assure 

required accuracy. The calibration area will be reasonably free of dust, vapor, and 

vibration, and it will not be close to equipment that produces noise, vibration, or chemical 

emissions that can affect the calibration results. All calibration standards, measuring 

equipment, and test equipment are assigned an established interval for calibration and 

these documents will be maintained centrally at the EH&E FOSC. 

All measuring, monitoring, and sampling instrument calibrations, except those requiring 

factory calibrations will be performed in EH&E’s FOSC prior to shipment of instruments 

to the field. All instruments that are factory calibrated are checked periodically in the 

FOSC by comparing them against other, recently calibrated instruments. Table 5.3 

summarizes the calibration procedures for instruments used in the study. 

Table 5.3 Equipment and Sensor Calibration 

Parameter 

Instrument 

Type Instrument Calibration Method Frequency 

Air 

temperature 

Thermistor, 

data logger 

HOBO® U10-003 

(Onset Computer 

Corp) 

Calibrations performed 

by the manufacturer 

Annual 

Relative 

humidity 

Thin-film 

capacitive 

sensor, data 

logger 

HOBO®

 U10-003 

(Onset Computer 

Corp) 

Calibrations performed 

by the manufacturer 

Annual 

Carbon 

dioxide 

Nondispersive 

infrared 

sensor 

Q-Trak Model 

8551 Indoor Air 

Quality Monitor, 

Multipoint with standard 

gas mixtures ranging 

from 0 to 2000 ppm 

along linear response 

curve. 

Pre and post 

field 

measurements 

Active air 

sampling 

Air-sampling 

pump 

Gilair-3/5 

(Sensodine, Inc.) 

SKC Inc. 

Compared against 

calibrated flow meter. 

Pre and post 

measurements 

Active air 

sampling 

Flow meter Dry-Cal DC-Lite, 

Bios International 

Corporation 

Annual factory 

calibration 

Pre and post 

measurements 

Volatile 

organic 

compounds 

SUMMA 

canister flow 

controller 

6 Liter SUMMA 

canister 

Provided pre-calibrated 

by laboratory 

Each canister 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 18 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
5.4 CORRECTIVE ACTION 

In a QA program, one of the most effective means of preventing trouble is to respond 

immediately to reports from the operator of suspicious data or equipment malfunctions. 

Application of proper corrective actions can reduce or prevent the collection of poor 

quality data and/or the loss of data. Established procedures for corrective actions are 

available in the methods if the performance limits are found to be exceeded. Specific 

control procedures, calibration, or operational checks, etc. are designed to detect 

instances in which corrective action is necessary. Troubleshooting guides for operators 

are found in the instrument manufacturer's manuals. On-the-spot corrective actions 

routinely made by field technicians will be documented as normal operating procedures, 

and no specific documentation other than notations in operations logbooks need be 

made. Corrective actions are a continual part of the environmental monitoring system for 

quality, and they will be documented throughout the in-home study. 

5.5 INTEGRATED SAMPLE FLOW RATES 

QA/QC of integrated air samples will include verification of pump flows by use of 

calibrated flowmeters at the start and end of each sampling period. The start and stop 

flow rates will then be averaged to obtain an average flow rate. Sample duration will also 

be calculated from the start and stop times recorded on the field data sheets. Total 

sample volumes will then be calculated using the average flow rate and the duration of 

sampling as follows: 

Total Sample Volume (L) = Average Flow Rate (L/min) x Total Sample Time (minutes) 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 19 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
6.0 DOCUMENT MANAGEMENT 

Strict attention will be paid to sample custody and record keeping throughout all aspects 

of the in-home study as described below. 

6.1 SAMPLE CUSTODY 

EH&E will follow the requirements for holding times and sample perseveration outlined in 

the respective reference sampling methods to be used. After each day of sampling, 

samples will shipped to the laboratory via overnight express delivery within the holding 

time specified by the analytical method. The reduced sulfur air samples will be shipped 

immediately after sampling via first priority overnight express delivery so that they would 

be received at the laboratory within 24 hours of sample collection. 

All project samples will be handled in accordance with appropriate chain of custody 

procedures. Compliance will be overseen by the lead field technician. The lead field 

technician will also be responsible for ensuring that all unused sample media as well as 

collected samples are properly cared for before, during, and after sampling. At the time 

of use, each sample will be assigned a unique sample identification label. Each sample 

label will be recorded on the field sample log sheets prior to sample collection. All log 

sheets will be stored in a master field binder during the study. 

6.2 RECORDKEEPING 

All data and documentation generated during the study, except that generated in 

electronic formats (raw data files, digital photographs), will be transcribed into the 

appropriate field collection forms which will be subsequently stored in a single data 

collection binder. Hardcopies of final analytical laboratory reports (and the completed 

chains of custody) will also be received and retained in EH&E’s central filing system. Any 

changes in data entries will be done in a manner that does not obscure the original 

entry. The reason for the revision will be indicated, dated, and signed at the time of 

change. All original hard copy records for the project will be retained (together) in a 

central file system at EH&E’s main office. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 20 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Electronic documentation generated in the field during the study will include digital 

photographs, XRF data files, carbon dioxide measurements, temperature and relative 

humidity data files. All files generated during the field phases of the study will be 

downloaded and stored temporarily on a field computer under the control of the lead field 

technician. Electronic files will then be transferred from the field computer onto EH&E’s 

central server routinely (typically at the end of each day). In order to track the various 

electronic data files, a standardized filing and naming system will be used to clearly 

differentiate between files by type and study home. Also, field personnel will document 

the location of digital photographs, XRF measurements, and real-time data monitor 

deployments on the appropriate field forms. 

6.3 DATA ENTRY AND DATA REDUCTION 

A systematic, standardized approach will be implemented by EH&E for all data entry and 

data reduction activities. EH&E will develop a database (Microsoft Access), where all 

field data and laboratory results will be stored. All (100%) field log entries and 

calculations will be reviewed by independent staff members prior to entry into the study 

database. Data entry personnel will initiate data entry activities as soon as the respective 

data binders are reviewed. Data entry personnel will be trained on all data entry 

procedures and requirements. Once in the database, all (100%) of the data entry fields 

will be reviewed and verified by independent, qualified personnel. 

To minimize database entry errors, EH&E will request that, when possible, all laboratory 

reports be provided in electronic data delivery (EDD) formats, such as Microsoft Excel so 

that the data can be directly imported into the central study database. All laboratory data 

will be uploaded to the project database through program codes developed using SAS 

9.1. All programming codes developed and executed for processing the data will be 

independently reviewed by qualified personnel. In the limited instances where data entry 

or recording errors are identified during the QA/QC review processes described above, 

the entry will be corrected in all relevant locations (back to the original entry). 

Corrections will be noted on all original documentation. 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 21 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
7.0 DATA VALIDATION 

All data will undergo a validation process whereby data are accepted or rejected based 

on a set of specific quality control and QA criteria. A number of measures will be 

implemented to ensure the collection of reproducible and accurate data during the study 

including the assessment of precision and accuracy, a review of QA samples, and an 

assessment of sample completeness. 

The assessment of sample duplicates, field blanks, and shipping blanks will be used for 

evaluating the error within the data set. The completeness of the data set will be 

evaluated by analyzing the capture efficiency for each environmental parameter targeted 

in the study. Precision will be evaluated by calculating relative percent differences 

between paired primary and duplicate samples while accuracy will be evaluated by 

reviewing results of blank samples. The data validation methods to be employed are 

described below. 

7.1 POST DATA REDUCTION 

After the database is populated, the number and sample identification labels in the 

database will be compared with those on the field log sheets and the analytical 

laboratory reports (using a program coded in SAS 9.1) to ensure all samples are 

accounted for. All programming codes developed and executed for processing the data 

will be independently reviewed by qualified personnel. 

7.2 PRECISION AND ACCURACY 

While the sampling and analytical methods for the integrated parameters vary widely, 

the analyses of precision and accuracy do not. Duplicate laboratory samples, field 

blanks, and laboratory limit of detection will be the tools used for measuring confidence 

with the integrated samples. The following paragraphs describe methods that will be 

used to estimate the precision and accuracy of integrated samples collected as part of 

the study. 

Precision will be evaluated by analyzing statistical variance between primary sample and 

duplicate samples. For the real-time and continuous data, precision will be evaluated by 

Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 22 of 23 

EH&E-QAP-001 Rev. No.2:08/09 
Quality Assurance Project Plan August 10, 2009 

Environmental Health & Engineering, Inc. Page 23 of 23 

EH&E-QAP-001 Rev. No.2:08/09 

comparison of differential results between instrument readings. It will be essential to 

have an understanding of how data quality will potentially be impacted by measurement 

error. 

Compared to estimates of precision, there will be less certainty in available estimates of 

accuracy with respect to the environmental integrated data collected. Field and shipping 

blanks will be used for assessing the accuracy of the data. It should be noted that many 

of the estimates of accuracy may have considerable variation in their values. However, 

this variation reflects the precision, which is best estimated by the field duplicate 

samples discussed above. 

The concepts of precision and accuracy are more inherent to continuous and real time 

monitoring than time-integrated sampling, as sensor performance can be more directly 

evaluated and/or manipulated. While integrated data requires laboratory intervention and 

subsequent analysis, continuous and real time data records can be adjusted and tracked 

in the field. 

At the beginning of sampling event instrument response will be set or calibrated to a 

primary standard device in the EH&E field operations support center or by the factory. 

Each day the performance of each sensor will be measured or verified against the 

appropriate standard. This method will allow both the repeatability (precision) and the 

instrument accuracy to be evaluated. Evaluating the precision and accuracy of 

continuous and real time monitoring parameters will be based upon predictable and 

repeatable instrument response as well as on comparisons to NIST traceable standards. 

7.3 DATA COMPLETENESS 

The completeness of air sampling data from the study will be evaluated by examining 

the overall data capture efficiency for each sample group and sample type collected in 

the field (primary samples, duplicate samples, and field blanks and shipping blanks). 
APPENDIX A 

PROJECT TEAM ORGANIZATION 
Principal Investigator/Project 

Executive

John F. McCarthy, Sc.D., C.I.H. 

Project Manager

Brian J. Baker 

Technical Directors

Joseph G. Allen, D.Sc. 

David L. MacIntosh, Sc.D. 

Quality Assurance Officer

William S. Wade 

Data Manager

Taeko Minegishi, M.S.

Field Team Manager

Matt A. Fragala, M.S., C.I.H. 

Data Support

Ted A. Myatt, Sc. D., RBP

Alex Ostroff

Cynthia A. Straley

Deborah A. Shepard, M.S.

Tuan Trong

Field Team Support

Wayne E. Carlson

Matthew H. Kaufman

Todd Megrath, A.L.M., LEED AP

David Shore

PROJECT TEAM ORGANIZATION