c 

I 

t 

3 445b 0070928 b 
I 
ORNL/TM-9867 

HEALTH AND SAFETY RESEARCH DIVISION 

MODELING AND TESTING OF FORMALDEHYDE EMISSION CHPlRACTERISTICS 

OF PRESSED-WOOD PRODUCTS: 

Report: XVIII 

to the 

U.S. Consumer Product Safety Commission 

1985 

T. G. Matthews 

Contributors : 

T. J. Reed, B. R. Tromber ,l K. W. Fung,2 

C. V. Thompson, J. 0. Simpson, $ and A. R. Hawthorne 

Date Completed - November 1985 

Date Published - September 1986 

OAK RIDGE NATIONAL LABORATORY 

Oak Ridge, Tennessee 37830 

operated by 

MARTIN MARIETTA ENERGY SYSTEIMS, INC. 

for the 

U.S. DEPARTMENT OF ENERGY 

IDepartment of Chemistry, University of Tennessee, Knoxville, TN 37916 

2Safety Office, University of Hong Kong, Hong Kong 

3Department of Chemistry, Spelman College Chattanooga, TN 37405 

c- 'i l. 1 

CONTENTS 

LIST OF FIGURES ......................................................... V 

LIST OF TABLES .......................................................... vii 

ACKNOWLEDGMENT .......................................................... ix 

SUMMARY ................................................................. xi 

REPORT XVIII 

INTRODUCTION .......................................................... 2 

ENVIRONMENTAL PARAMETERS STUDY 11 ..................................... 3 

Models I and I1 ..................................................... 3 

Analysis of Particleboard, Paneling, and Medium Density 

Fiberboard Data 5 

Modeling of CH20 Emissions Data 9 

Interproduct and Interstudy Comparisons of Modeling Results ......... 11 

Sensitivity Analysis for Model I, I1 Coefficients ................... 18 

Uncertainty Analysis for Model I and Model I1 ....................... 23 

..................................................... ..................................... 

SINKS STUDY ........................................................... 28 

SLOW DECAY STUDY ...................................................... 35 

FAST DECAY STUDY ...................................................... 38 

Temperature, RH Correction Model .................................... 39 

Formaldehyde Emission Rate Decay Modeling ........................... 42 

Front/Back Emtssion Ratios for Paneling ............................. 43 

PERMEATION BARRIERS STUDY ............................................. 47 

Simulated Flooring Experiments ...................................... 47 

Permeation Barriers Modeling ........................................ 52 

INTERLABORATORY TEST COMPARISON OF THE FSEM ........................... 56 

APPENDIX I: Uncertainty Analysis of Models I and I1 .................... A.l 

iii 

LIST OF FIGURES 

REPORT XVIII 

Figure 1: 

at Constant N/L . 0.5 m/h ............................................. 19 

Model I Analyses of All PBU. PAN Data Set 

Figure 2: Model I1 Analyses of All PBU. PAN Data Set 

at Constant [CH20] . 0.1 ppm .......................................... 20 

Figure 3: Summary of Sinks Sorption Data ............................. 31 

Figure 4: Summary of Sinks Desorption Data ........................... 34 

V 

LIST OF TABLES 

REPORT XVIII 

Table 1. Temperature, RH Zest conditions used in 

the Environmental Parameters Study I1 ................................. 5 

values for Table 2. Summary of C , CH20ERstd 

7 VSt Environmental Parameters gtudy I1 ..................................... 

Table 3. Selected, standard-conditim, normalization 

factors for Environmental Parameters Study IT ......................... 10 

Table 4. Results of nonlinear regression analyses for Model I ........ 12 

Table 5. Results of nonlinear regression analyses €or Model I1 ........ 13 

Table 6. Model I analyses. Comparison of C for individual 

and combined product data sets as a function of environmental parameters. 15 

T,RH,N/L 4 std V 

Table 7. Model I1 Analyses. Comparison of CH OE 

for individual and combined test product data sets 2 %, RH[ CH20]’CH20ERstd 

as a function of environmental parameters ............................. 16 

Table 8. Sensitivity Analysis of Model I: and I1 Coefficients ......... 21 

Table 9. Uncertainty analysis for ALLPBU, ALLPAN and ALLMDF 

Model 1 Analyses ...................................................... 25 

Table 10. Uncertainty analysis for ALLPBU, ALLPAN and ALLMDF 

Model I1 Analyses ..................................................... 25 

Table 11. Slow decay study data file ................................. 36 

Table 12. Environmental conditions inside the storage room for 

the fast decay study boards at the time of FSEM measurements .......... 40 

Table 13. Summary of decay periods (P, months) for 

individual boards in the fast decay study ............................. 44 

Table 14. Summary of average decay periods (7, months) 

for the fast decay study .............................................. 45 

Table 15. Summary of frontback CH 0 emission ratios 2 of fast decay study boards ............................................ 45 

Table 16. Formaldehyde vapor concentration data (ppm) from the 

simulated flooring experiments of the permeation barriers study ....... 49 

vi i 
Table 17. Modeled CH2O vapor concentration data (ppm) for uncovered 

particleboard during flooring-covered particleboard experiments ....... 51 

Table 18. Linear regression analyses of the modeled CH28 

concentration data for uncovered particleboard underlayment 

during flooring - covered particleboard experiments ".................. 54 

a 

Table 19. Comparison of measured and modeled CH 0 vapor 

concentrations (ppm) from simulated flooring experiments .............. 55 2 

Table 20. 

the FSEM for particleboard underlayment samples ....................... 57 

Interlaboratory test comparison results of 

Table 21. Interlaboratory test comparison results of 

the FSEM for hardwood plywood paneling samples ........................ 58 

viii 
ACKNOWLEDGMENT 

Research sponsored by the U.S. Consumer Product Safety Commission under 

Interagency Agreement CPSC-IAG-82-1297 under contract DE-AC05-840R21400 with 

the Martin Marietta Energy Systems, Inc. 

ix 

SUMMARY OF PRESSED-WOOD PRODUCT RESEARCH PROGW: REPORT XVIII 

Research has been conducted at Oak Ridge National Laboratory to better 

understand the formaldehyde emission characteristics of pressed-wood products 

that are manufactured in the U.S. and commonly incorporated in domestic 

environments. There were strong experimental and modeling components to this 

research including analytical method development, the survey of product 

emissions and the modeling of the interaction of these products in indoor 

environments. The results of these investigations have been reported to the 

sponsor, the U.S. Consumer Product Safety Commission (CPSC), in the form of 

detailed bimonthly to quarterly reports. Report XVIIT comprises the final 

progress report to CPSC, which discusses the final results of six projects 

conducted as part of the pressed-wood products research program. No final, 

comprehensive project report was written due to resource limitations. 

The experimental results and modeling of a second environmental chamber 

study of the environmental dependence of CH2Q emissions from selected 

pressed-wood products are reported. Results for particleboard underlayment, 

hardwood plywood paneling, and medium density fiberboard are given. Revised 

models for (1) variation in CH2Q concentration inside a single compartment 

with a single emitter (i.e., Model I), and (2) variation in CH2O emission rate 

of a single emitter (Model 11) as a function of environmental parameters are 

presented. The revised models include a (1) a linear function for the 

temperature (T) and relative humidity (RH) dependence of the CH20 transport 

rate through the bulk phase (i.e., board) and (2) a non-linear function for 

the RH dependence of the CH20 concentration in the bulk phase. Pressed-wood 

product emissions data from individual Study I1 boards and the combined data 

sets from Environmental Parameters Studies I and I1 are analyzed using the 

revised models. Good fits between individual product data sets and Models I 

and I1 are observed. Due to the complexity of the Models 1 and. IT (i.e., 5 

term models), simple analyses of the model results (such as interproduct and 

interstudy comparisons) based on values of individual model coefficients are 

often inadequate. Instead, analyses of the model. results are performed by 

substituting selected environmental conditions into the test-product models 

for comparison of the calculated dependent variables; that is, the 

proportionate changes in CH20 concentration (i.e., Model I) and CH20 emission 

xi 
rate (i.e., Model 11). The Model. 1 results €or combined particleboard, 

paneling and fiberboard data sets indicate two-fold increases in CH2O 

concentration with approximate increases of 7OC and 30-50% RH at constant air 

exchange and product loading conditions. The Model I1 results for combined 

product data sets indicate two-€old increases in CH20 emission rate with 

increases of 4-SoC and 20-40% W at constant CH2O concentration. Additional 

statistical analyses concerning (1) the sensitivity of Models 1 and I1 to 

variation in individual model coefficients and (2) the uncertainties in Model 

I and 11 estimates with changes in environmental parameters, are also 

presented. 

The sorption and subsequent desorption of CW20 vapor on the surface of 

unpainted gypsum wallboard has been studied in environmental chamber 

experiments at 23OC and 58% RH. Simple, three-term, single exponential models 

with riseJdecay periods of about three days describe the time dependent rise 

and fall of CH20 concentrations in chamber experiments where gypsum board is 

exposed to (step-function) increases and decreases in CH20 concentrations, 

respectively. Gypsum board acts as a time-dependent buffer to changes in CH20 

concentration but constitutes only a weak permanent CH2O loss mechanism. 

The final results of two decay studies examining the time-dependent 

decline in CH20 emissions from selected particleboard underlapent, industrial 

particleboard, hardwood plywood paneling and medium density fiberboard are 

reported. In the slow decay study, the decline in CH20 concentration 

generated from a collection of pressed-wood products, contained in a walk-in 

chamber about 23OC, 50% RN and a 0.4 h’l air exchange rate, was monitored 

for 14 months. In the fast decay study, che decline in CH20 emission rates 

from individual pressed-wood products, conditioned at about 23%, 50% RH and 

typically < -0.1 ppm CH20, was monitored for 16 months. The 1Je decay period 

for the slow decay study was 2.2 years. The average l/e decay periods for 

particleboard, paneling and fiberboard products were 1.1, 0.9 and 1.6 years. 

The shorter decay periods in the fast decay study are consistent with 

anticipated higher CH20 emissions from particularly weaker boards at reduced 

CH20 concentrations. 

at 

xii 
The retardation of CH2O emissfons from particleboard underlayment by 

three decorative flooring barriers has been studied in small scale 

environmental chamber experiments at approximately 23% and 50% RH. The 

permeation barriers consisted of nylon carpet over sponge rubber and urethane 

foam cushion, and vinyl tile flooring. The effectiveness of the flooring 

barrier in reducing CH20 emissions was experimentally evaluated through 

sequential measurements of CH20 emissions from bare and covered particleboard 

underlayment. The carpet and cushion barriers resulted in 5 2.5 fold 

reductions in CH2O emissions in comparison to approximate 30 fold reductions 

with the vinyl flooring. Formaldehyde transport models based on measurement 

of the CH20 diffusion coefficients of the flooring products predicted 

reductions in CH20 emissions from the particleboard quite similar to the 

experimental results for two of three flooring barriers. 

The preliminary results of an incomplete interlaboratory comparison of 

measurements of CH20 emission rate from particleboa.rd underlayment and 

hardwood plywood paneling samples using the formaldehyde surface emission 

monitor are reported. Correcting for interboard variatlon in CH2O emission 

strength as determined from 0RNL emission measurments, the coefficients of 

variation between the average results of six of seven participants is 10% and 

14% for the paneling and particleboard measurements, respectively. 

MODELING AND TESTING OF FORMALDEHYDE EMISSiON 

CHARACTERISTICS OF PRESSED-WOOD PRODUCTS 

Rep o r t Xi7 I I I 

June 1984 - May 1985 

T. G. Matthews, T. J. Reed, B. R, Tromberg, K. W. Fung,** 

C. V. Thompson, J. 0. Simpson, and A. R. Hawthorne 

Measurement and Applications Group 

Health and Safety Research Division 

Oak Ridge National Laboratory 

Oak Ridge, Tennessee 37831 

**Safety Office, University of Hong Kong 

* Research sponsored by the Consumer Product Safety Commission under 

Interagency Agreement CPSC-IAG-84-1103 under Martin Marietta Energy 

Systems, Inc., Contract DE-AC05-840R21400 with the U.S. Department of 

Energy. 
Report XVIII 2 CPSC-IAG-84-1103 

MODELING AND TESTING OF FORMAIDEHYDE EMTSSJON 

CHARACTERISTICS OF PRESSED-WOOD PRODUCTS 

Report XVXII 

June - December 11984 

T. G, Matthews, T. J. Reed, B. R. Tromberg, K. W. Fung,** 

C. V. Thompson, J. 0. Simpson, and A. R. Hawthorne 

Measurement and Applications Group 

Health and Safety Research Division 

Oak Ridge National Laboratory 

Oak Ridge, Tennessee 37831 

INTRODUCTION 

The projects that are discussed in this report include: 

1. the environmental parameters study 'TI using particleboard 

underlapent, decorative paneling, and medium density fiberboard 

materials acquired in the commercial pressed-wood product survey, 

2. the formaldehyde (CH20) 'sinks' (i.e., water bearing sorbent 

materials) study of gypsum wallboard and carpeting, 

3. the 'slow' decay study for pressed-wood CH 0 emissions at a fixed 2 

air exchange and loading, 

4. the 'fast' decay study for pressed-wood emissions at low CH20 

concentrations, 

5. the permeation barriers study, and 

6. the interlaboratory test comparison of the FSEM. 

The final results from all projects will be reviewed 

* Research sponsored by the Consumer Product Safety Commission under 

Interagency Agreement CPSC-IAG-84-1103 under Martin Marietta Energy 

Systems, Inc., Contract: DE-AC05-84OR21400 with the U.S, Department of 

Energy . 
Report XVIII 3 CPSC-IAG-84-1103 

ENVIRONMENTAL PARAMETERS STUDY I1 

The environmental chamber studies for particleboard underlapent, 

hardwood plywood paneling and medium density fiberboard (MDF) samples are 

complete. Results of the modeling of the Environmental Parameters Study I1 

data are presented in this report. 

Models I and I1 

The CM 0 concentration model (i.e., Model I) and the CH20 emission rate 2 

model (i.e., Model 11) that were originally presented in Report XIV have been 

revised. 

The final expression for Model I is: 

P 

std 11 cV 

-C(- - -) 

[l+B(T-296)] - [l+E(RH-SQ)] e 296 - (RH/5Q)* [KB + 0.51 

s ta 

[l+B(T-296)] [l+E(RH-50)] * KB -I- N/L 

std 

where : 

T = temperature (degrees Kelvin), 

RW = relative humidity (%), 

N/L = air exchange to loading ratio (m/h), 

Cv - CH 0 vapor concentration (ppm), 2 
Report XVIII 4 CPSC-IAG-84-1103 

K = modeled CH 0 transport coefficient for the bulk phase (m/h), R 2 

std = standard test conditions (i.e., 23"C, 50% RH, N/L - 0,5 m/h), and 

A,B,C,E = model coefficients for temperature and RH terms. 

The final expression for Model I1 is: 

C"20EKT, RII, Cv 

CW20ERstd 

_- =c 

1 1 -e(- - -) 

[l+B(T-296)] - [1+E(RH-50)] [e 296 (RH/50)A * C - cvl % td 

where : 

CH OER = 2 

std = 

- 

- 0.1 

std cB 

2 CH 0 emission rate (mg/m h), 2 

standard test conditions (i.e., 23°C. 50% RH, Cv = 0.1 ppm), and 

CH 0 concentration in the bulk phase. 2 

The revisions in Models I and I1 are based upon two refinements in the 

assumptions used in the mathematical development of the Models. 

1. The CH 0 transport coefficient for the bulk phase, KB, is assumed to be a 

function of temperature and relative humidity (RH). Previously K was 

assumed to be constant. 

2 

B 

2. The KH dependence of the CH 0 vapor concentration in the porous bulk 2 

phase is assumed to follow the nonlinear expression: 

Previously f (RH) was assumed to be a simple linear function. 

cB 
Report XVIII 5 CPSG-IAG-84-1103 

The justification for these revised assumptions and the complete 

derivation of Models I and I1 have been previously reported. (1) 

Analysis of Particleboard, Paneling, and Medium Density Fiberboard Data 

The experimental testing sequences for the particleboard underlayment, 

hardwood plywood paneling, and medium density fiberboard products used in the 

Environmental Parameters Study I1 are listed in Table 1. The testing of the 

particleboard and paneling products received a larger number of test cycles 

than the medium density fiberboard. The numbers 1 through 5 in Table 1 refer 

to successive measurement series taken at standard conditions of 23" C and 50% 

RH. emissions 

at standard test conditions. These data are used to determine C and 

CW20ERstd values, which are the normalization factors used to treat gff of 

the CH 0 emissions data for Model I and I1 analyses. The numerical values of 

for Model I and CH20ERstd for Model I1 are listed in Table 2. The 

an3 CH OERstd values determined from cv td cofumn headings 1 through 5 are for C 

's td individual data sets taken at standard conditions. The column headings 1 2 

and 2 5 are for Cv and CH OERstd values determined from combinations of 

two data sets (i. e. , ls$dand 2,5, respectively) taken at standard conditions. 

The Study I1 design allowed for frequent determination of CH 0 2 

V * 

2 

2 

2 

The selection of appropriate normalization factors for the experimental 

CH 0 emissions data are required before Model I and I1 analyses can be 

performed. These factors are chosen to best account for the aging of the test 

products during the enviromental parameters study and potential experimental 

2 

problems that might strongly affect the modeling results. For example, 

analysis of the Cv and CH OERstd values listed in Table 2 indicates that 

data taken at stana%!d conditions 4 were collected prior to adequate 

2 

1. T. G. Matthews, T. J. Reed, C. R. Daffron and A. R. Hawthorne, 

"Environmental Dependence of Formaldehyde Emissions From Pressed-Wood 

Products : Experimental Studies and Modeling" Proceedings, 18th 

International Washington State University Particleboard/Composite 

Materials Symposium, pp 10-23, 1984. 

* The calculations used to determine the CVstd and CH OERstd values have 

been previously reported. See reference 1, pages 21-3. 
Report XVIII 6 CPSC-IAG-84-1103 

Table 1. Temperature, RH test conditions used in 

the Environmental Parameters Study 11. 

~.. 

Study 

Conditions Design 

Standard 

A. Particleboard (i*e., PRU3), Paneling (i.e., PPR2, PPR3) Study 

23 

23 

23 

23 

28 

33 

23 

26 

30 

23 

23 

40 

50 

75 

50 

50 

50 

50 

80 

65 

50 

50 

1 Iso-Thermal 

2 

Iss-RH 

3 

Matrix 

Variation 

4 

5 

B. Medium Density Fiberboard (i.e., MDF1, MDF2) Study 

23 50 

28 50 

33 75 

23 50 

Matrix 

Variation 
Report XVIII 7 CPSC-IAG-84-1103 

a Table 2. Summary of Cv 9 CW20ERstd values for 

std 

Environmental Parameters Study 11. 

- 

Test Product Model 1 2 3 4 5 12 25 

PBU3 

PPR2 

PPR3 

MDFl 

MDF2 

PBU3 

PPR2 

PPR3 

MDFl 

MDF2 

Ia 0.258 0.237 0.221 0.260 

Ia 0,312 0.256 0.150 0.263 

Ia 0.153 0.121 0.102 0.150 

Ia 0.855 0,689 

xa 0.434 0.395 

IIb 0.422 0.489 0.305 8.443 

IIb 0.373 0.312 0.117 0.325 

IIb 0.169 0.103 0.063 0.161 

IIb 1.69 1.95 

Ilb 0.811 0.960 

0.251 0.247 0.240 

0.185 0.282 0.214 

0.120 0,136 0.121 

0.787 

0.415 

0.437 0.447 0.459 

0.177 0,340 0.231 

0.096 0.132 0.101 

1.78 

0.866 

a Model I: Cv 

23"C,508 RH,O.5 m/h 

bModel 'I: CH20ER230C,50% RH,O. 1 ppm' 
Report XVXPI a CPSC-IAG-84-1103 

conditioning of the particleboard and paneling test products, For both Models 

I and 11, the standard conditions 4 values are high in comparison to all 

standard conditions 3 values, most 2 values, and some 1 values (see Table 2). 

Since product aging should have occurred over the duration of the entire three 

to four month study, repeat tests were performed at standard conditions (i.e., 

5 values) following an additional two to three week conditioning period. The 

reductions in standard conditions 5 values in comparison to 4 values (observed 

primari 1.y in the paneling test products) confirm that insufficient 

conditioning time had been alotted prior to the standard conditions 4 tests. 

The high values for standard conditions 4 may have been caused by relatively 

harsh environmental exposures of the particleboard and paneling test products 

at 30°C and 65% RH during the previous test cycle. For these reasons, data 

for standard conditions 4 are not considered in further analysis and modeling. 

Further analysis of the standard conditions data in Table 2 indicates 

that the C and CH20ERstd values for standard conditions 3 are low relative 

to standard conditions 2 and 5. This is true for all three particleboard and 

paneling test products, particularly for CH OER values. The low results 

for standard conditions 3 are inconsistent with an anticipated continuous 

decline in CH 0 emission strength between standard conditions 2, 3, and 5. In 

addition, the low results for standard conditions 3 are particularly 

unexpected in light of the relatively high results for standard conditions 5, 

which were taken following an additional one to two month conditioning and 

testing period. The results for standard conditions 3 are rejected from 

further analysis and modeling based on two considerations. 

'std 

2 std 

2 

A higher confidence is placed on the results for standard conditions 5 

than standard conditions 3 because of the lengthy conditioning period 

prior to standard conditions 5 testing. This lengthy conditioning period 

plus normal product aging between the standard conditions 3 and 5 tests 

would predict that the results for standard conditions 5 should be lower 

than for standard conditions 3. 

Any potential error in the rejection of the data for standard conditions 

3 should result in a more conservative treatment of the impact of 

environmental parameters on CH 0 emissions from the test products. The 2 
Report XVIII 9 CPSC-IAG-84-1103 

inclusion of standard conditions 3 data would result in smaller 

normalization factors for particularly the Iso-Relative Humidity and 

Matrix Variation experiments (see Table I), thus increasing the 

sensitivity of the model to changes in the temperature and RH. 

and CW DERstd normalization factors are 

listed in Table 3. The standad conditions 1, I 2, and 2 5 refer to 

product-dependent numerical values specified in Table 2 for both Model I and 

I1 analyses. The Cv and CH20ERstd normalization factors are chosen to 

reduce the modeled impaztdof changes in product emission strength due to 

product aging between consecutive chamber tests at standard conditions. For 

most test cycles this is accomplished using combined normalization factors 

(i.e., 1 2, 2 5) determined from pairs of standard conditions data sets 

that bracket one or more data sets taken at non standard conditions, To 

exemplify the use of Tables 2 and 3, the 2 value for normalization 

of PBU3 emission data (i.e., 0.240 ppm, Table 2) is applied to the consecutive 

test cycles at 23"C/50% RH, 28"C/50% RH, 33"C/50% RH, 26"G/80% RH, 30°C/65% KH 

and 23"C/50% KH as specified in Table 3. 

2 The final selection of the C 

vst 

* 

std cv 

Modeling of CH 0 Emissions Data 2 

The normalized CH 0 concentration and CH 0 emission rate data for all 

test products were fit to Models h and II, respectively, using nonlinear 

regression analyses (see Reference I, pi). 25-6). All model coefficients were 

bounded to positive valaes as a reasonable expectation of the physical theory. 

The SAS nonlinear regression software with Marquardt iteration was used with 

analytical derivatives to analyze of all individual pressed-wood product data 

sets. The combined product data sets Erom Environmental Parameters Studies I 

and I1 were analyzed using DUD iteration techniques with numerical derivatives 

to reduce computer costs. In the modeling of Environmental Parameters Study I 

data, the DUD iteration method was shown to give reliable estimates sf model. 

parameters when large, combined product data sets were used. 

2 2 

* For detailed discussion of calculations for CV and CH 2 OERstd, see 

reference 1, pages 21-3. std 
Report XVIII 10 CPSC-IAG-84-1103 

Table 3. Selected, standard-condition, normalization 

factors for Environmental Parameters Study II ..- 

Temp ("C) RH (8) Standard Conditiona 

23 

23 

23 

23 

23 

23 

28 

33 

26 

30 

23 

23 

28 

33 

23 

A. Particleboard (i.e., PBU3), Paneling (i.e., PPR2,PPR3) Study 

40 

50 

so 

75 

50 

50 

50 

50 

80 

65 

50 

1 

1 

12 

12 

12 

25 

25 

25 

25 

25 

25 

8. Medium Density Fiberboard (i.e., MDF1, MDF2) Study 

50 

60 

75 

50 

12 

12 

12 

12 

a Numerical values listed in Table 2. 
Report XVIII 11 CPSC-IAG-84-1103 

The results of the Model I and I1 analyses of the particleboard, paneling 

and MDF data sets are listed in Tables 4 and 5. Several analogies are 

observed with the results from Environmental. Parameters Study I (See Reference 

1, pp. 27-8). 

1. 

2. 

3. 

A good fit between the experimental data and Models I and I1 is indicated 

by the rgncorr values of 0.91 - 0.99 and root mean square errors of 

typically <0.5 for individual product data sets. 

The Model I and Model I1 coefficients for individual particleboard data 

sets determined in Study I typically overlap within 95% confidence 

intervals with the same model coefficients for individual particleboard 

data sets determined in Study 11. For both Studies I and I1 the 95% 

confidence intervals are generally broad. 

The Model I and Model I1 coefficients for various combinations of 

particleboard paneling products data sets determined in Study I are 

closely comparable to the same model caefficients determined from both 

Study I and Study 11 data. A variation of <25% is typically observed 

between model coefficients determined for Study I- and Study 1,IIcombined product models. 

and 

Interproduct and Pnterstudy Comparisons of Modeling Results 

The method chosen for detailed interproduct and interstudy comparisons of 

the environmental parameters models is to examine the variation in 

CVT,~,,J/L/CV~~~ (ie.. Model I dependent variable) and CH~OERT,RH,CV/CH~OERS~~ 

(le., Model I1 dependent variable) for different product models as a function 

of T, RH, and N/L or Cv parameters. A comparison is performed by substituting 

the model coefficients for different product models and selected T, RH, and 

N/L or Cv conditions back into Equations 1011 2 for Model I or I1 analyses, 

respectively. The result is a direct comparison of the predicted 

CVT,~,N/L/CV~~~ or CH~~ERT,RH,~V/CH~OERS~~ values far different product 

models under selected environmental conditions. An advantage of this type of 

comparison is a reduced uncertainty (as estimated by the root mean square 

error) in modeled CVT,~,.J/L/CV~~~ or CB~QERT,RH,CV/CH~OER~~~ values in 
13 

c 

H 

Table 4. Randts of nonlinear regression analyses for Model 1 

c. 

1-0 st 95% Confidence li 9% Confidence 95% Confidance 95% Confidence E 95% Coaffdence Root mea8 2 

product intern rrl 1 at erv 61 i ut ervnl intervnl i nt erv a1 qunre error 'wcorr 

brn 

PW 

FER3 

HDF1 

m 

AIi RPB 

Study 1,XI 

All PAN 

stug I, I1 

AI1 WU, PAN 

study 1.11 

study 11 

AI1 WDF 

83 50 

s SO0 

13400 

s 800 

93 00 

7200 

5soo 

6 IO0 

87 00 

110C+9500 

4200-6800 

730&9500 

MOO-7 000 

6660-12000 

6800-7700 

4800-6200 

5600-66 00 

6 3 00- 1 IO00 

0.57 

0.23 

1.23 

1.25 

0.93 

0.65 

0.98 

0.88 

0.74 

0.33-0.81 

0.0 5- 0.42 

1.02-1.44 

0.7 3-1.78 

0 .16-2.02 

0.40-0.89 

- 

0.661.36 

0.62-1 .14 

- 

0.23-1.71 

0.93 

0.40 

om 

1.25 

1.18 

6.6s 

0 35 

0.60 

1.58 

O.'P*f.lB 

0.93-0.46 

0.63-1.07 

0.73-1.76 

1 .lb2.06 

0.54-0.77 

! 

0.40-0.ii 

0.4 9-0.74 

1 .10-2.06 

0.054 

0.016 

0.042 

6.POO 

0.624 

0.074 

0.121 

0.107 

0.026 

0.000-0.108 

0.013-0.129 

0.009-0 .OB 

0.03 9-0 .16 1 

0.050-0.097 

0.042-0.105 

- 

- 

0.045-0.197 

0.063-0 .I 50 

- 

0.055-0.108 

0.019 

0.03R 

0.m 

0.011 

0.017 

0.015 

0.021 

0.017 

0.033 

0.005-0.036 

0.825-0 .OS2 

0.001-0.030 

0.007-0.040 

0.029-0.063 

0.001-0.031 

- 

- 

- 

- 

0.005-0.050 

- 

0.001-0.03 5 

- 

a. 027 -0. o 93 

0.16 

0.16 

0.20 

0.04 

0.10 

0.2& 

0.66 

0.53 

0.14 

0.99 

0.99 

0.99 

5.99 

0.99 

0.9s 

0.92 

0.95 

0.99 
Table 5. Results of nodincat regressloa rrmlyrar for Model 11 

P 

w 

0 

Y 

r? 

2 

H 

H 

W 

Teat 95% Confidence A 93% Coaf idence 951 Confideam 95% Coafidencs E 95% Confidence loot mean 2 

pr odu et iat ervsl i nt em81 CBatd LUt0tr.f latsrral intervd sqtmre error 'meorr 

wm 7900 6800-9000 0.44 0.23-0.64 0.41 0.38-0.44 0.004 0.017-0.02s 0.013 0.006-0.021 0.25 0.96 

gRu 6500 4SOO-8400 0.76 0.37-1.15 0.51 0.45-0.38 0.016 0.020-0.051 0.004 0 .0O7-0.014 0.33 0.93 

m3 7300 610&8SOO 0.94 032-1.15 0.25 o.zz-o.au 0.050 0.017-O.OM 0.028 0.01~-0.039 0.45 0.96 

Mal 5WO 4900-7000 1.1s 0.83-1.48 1.05 6.89-1.21 0.091 0.057-0.125 0.022 0.01iF0.034 0.17 0.99 

- 

- - 

- 

mF2 9WO 6300-11000 0.88 0.38-1.37 0.36 0.46-0.63 0.000. 0.02S-0,025 0,023 -0.064-0.043 3.20 a.9s 

- - All Ll.8. WU 9400 7800-11000 0.37 0.38-1.12 0.36 0.27-0.45 O.@ZS 0.013-0.062 0.016 0.012-0.043 1.38 0 .84 

stndy I.11 

Study 1.11 

stedy I, I1 

stag LIZ 

All HDDP 5000 1500-8500 1.90 0.70-3.10 0.90 0.54-1.26 0.090 -0.009-0.190 0.000' -0.024-0.024 0.60 0.96 

Study I1 

- - All PBU 9100 7600-11000 0.36 0.43-1.14 0.33 0.24-0.43 0.01J -0.OOtO.MS 0.023 0.011-0.057 1.91 0.79 

All PAW 6500 5100-7800 0.66 0.32-1.00 0.41 0.34-0.4'1 0.05s 0.02fM*OW 0.029 0.015-0.044 0.71 0.88 

All PBU, PAN 8300 7400-9200 0.60 0.16-1.02 0.33 0.29-0.40 0.036 0.012-0.061 0.024 0.006-0.041 1 .s 0 .EO 

- 

P 

W 

- 

'Ibdel eoeffialent bounded to rrlwr )O. Error estimate8 are ~pproriaats. I 

H 

=; 

f 

co 

P 

P 

0 

W 
Report XVIII 14 CPSC-IAG-84-1103 

comparison to the uncertainty for most individual model coefficients. In 

addition, a direct interproduct or interstudy comparison of model coefficients 

could be misleading because of the complexity of Models I and I1 and the use 

of dual temperature and RN coefficients. 

An analysis of the interproduct variation in modeled CVT,~,N/L/CV~~~ 

(ie., Model I) and CH~OERT,R~~,CV/CH~OERS~~ (ie., Model 11) as a function of 

environmental parameters for test products from Study I has previously been 

reported (see Reference 1, pp 29-36). To facilitate Study I, Study I1 

comparisons, the Study I1 analysis listed in Tables 6 and 7 are given in a 

similar format to that used for Study I (see *Tables VII, VIII, Reference 1). 

For Model I comparisons, several similarities are observed between the 

results for Environmental Parameters Studies I and 11. 

1. For potential seasonal changes in environmental conditions from 20"C, 

35% RN to 28"C, 75% RN at a constant N/L of 0.5 m/h, a range of 3 to 10 

fold increases in the modeled CVT,RH,N/T/CV~~~ are predicted from the 

results of Study I. A smaller but overlaping range of 5 to 8 fold 

increases are predicted from the results of Study 11. 

2. Twofold increases in modeled CV~,m,~/dCv~td are predicted with * increases of 6 to 8 Celcius degrees and 20 to >50 additional percent RH 

in both Studies I and 11. 

3. I.arger interproduct variation in C~~,m,N/dCv,td is predicted as a 

function of variation in RH than temperature or N/L parameters in both 

studies . 

Both similarities and differences are observed between the results of 

Model I1 comparisons for Study I and Study 11. 

* Certain testr products whose CH20 emissions are insensitive to changes in 

RH would require a >50% increase in RH from 50% to >-loo% RH to achieve a 

twofold modeled increase in cV~,w,N/L/cVs~d (ie., Model I) at a constant 

temperature and N/L. A >-50% increase in RH from 50% R1.l is not considered 

because it is a non-physical solution. 
Report XVIII 15 CPSC-IAG-84-1103 

Tabla 6. Modal I analysoe. Ccmprrison of C+, for individual and combined product data sets 

'L .RB.tl/L/'std 

as a function of onvironmsntal parmnatars 

Ieo-RH.B/L Iso-Tamg.H/L Iso-Temp,W Standard 

Conditions 

Temperature ("C): 23 29 30 31 23 23 23 23 23 23 23 

RII (XI: 50 50 50 50 70 80 90' 100' 50 50 50 

NIL (mih): 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1.5 2.0 2.5 

PRODUCT 

PBU3 1 1.9 2.1 2.3 1.3 1.5 1.6 1.8 0.59 0.49 0.42 

PPRZ 1 1.7 1.9 2.1 1.4 1.6 1.7 1.9 0.47 0.37 0.31 

PPR3 1 1.9 2.1 2.3 1.7 2.0 2.4 2.8 0.57 0.47 0.60 

All Pd 1 1.9 2.1 2.3 1.4 1.6 1.7 1.9 0.54 0.43 0.37 

All PANb 1 1.8 2.0 2.1 1.6 1.9 2.3 2.6 0.51 0.41 0.35 

All mu, PANb 1 1.8 2.0 2.2 1.5 1.8 2.1 2.3 0.52 0.42 0.35 

HDF 1 1 1.6 1.7 1.0 1.6 2.0 2.3 2.7 0.67 0.53 0.51 

rnF2 1 1.9 2.1 2. h 1.5 1.7 1.8 2.1 0.67 0.55 0.51 

All mF 1 1.9 2.0 2.3 1.4 1.8 1.8 2.0 0.68 0.58 0.51 

Standard Rporinuntal Seasonal 

Conditions Tort Cotrditionr Fluctuation 

T__ 

PRODUCT 

PBU3 

PPR2 

PPR3 

All PB# 

All PBU.PAd3 

All PANb 

WF1 

MlF2 

All MDF 

23 

50 

0.5 

23 23 28 33 26' 30 20' 28 

40 75 50 50 50. 65 35' 75 

0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 

0.81 1.4 1.7 2.6 2.1 2.6 

0.71 1. s 1.6 2.4 2.0 2.4 

0.71 1.8 1.7 2.8 2.8 3.1 

0.80 1.5 1.7 2.7 2.1 2.6 

0.71 1.6 1.7 2.5 2.6 2.8 

0.75 1.7 1.7 2.6 2.6 2.7 

0.50 2.4 

0.36 2.3 

0.kl 3.1 

0.48 2.4 

0.36 2.8 

0.41 2.7 

0.71 1.8 1.5 2.2 2.5 2.6 0.k3 2.6 

0.77 1.5 1.7 2.9 2.3 2.9 0.47 2.7 

0.76 1.5 1.7 2.7 2.2 2.7 0.44 2.5 

Wodel extrapolated beyond tho range of rxporimontal trst conditions. 

bEnvironmental Paramators Study I and 11 data includod. 
Report XVIIT. 16 CPSC-IAG-84-1103 

Table 7. Model I1 Analysss. Cornparlaon ob CA20~,RB~CB201/~RZODRstd 

for individual and combined te6t product. data sats 

an a function of mvirormnntal parameters 

Im-RB,[cR201 Iso-Tmp.,[CB201 Standard 

Conditionn 

Exporimsntal 

Tnst Conditions 

Tomperatore (*C): 

RH (Z): 

ICAZ0l (piman): 

PRODUCT 

PBU3 

PPR2 

PPR3 

All PBUc 

A11 US PBUC 

All PANC 

All PAN,PBUC 

MDF 1 

MDFZ 

All MDF 

23 

50 

0.1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

27 28 

50 50 

0.1 0.1 

29 23 

50 70 

0.1 0.1 

23 23 23 23 23 28 33 26 30 

80 goa looa 40 75 50 50 80 65 

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 

1.6 1.8 

1.5 1.7 

2.0 2.3 

1.9 2.3 

1.9 2.2 

1.8 2.0 

1.9 2.2 

1.8 2.1 

1.7 1.9 

1.8 2.0 

2.0 1.5 

1.8 1.5 

2.7 2.5 

2.6 1.7 

2.5 1.6 

2.3 2.1 

2.5 1.9 

2.4 2.2 

2.1 2.1 

2.2 2.0 

1.8 2.1 2.5 0.76 1.7 1.8 3.0 2.5 3.0 

1.7 1.9 2.2 0.77 1.6 1.7 2.7 2.3 2.7 

3.6 4.8 6.1 0.48 3.0 2.3 4.6 5.6 6.0 

2.1 2.6 3.0 0.58 1.9 2.3 4.6 3.5 4.6 

1.9 2.2 2.5 0.75 1.7 2.2 4.4 3.0 4.1 

2.8 3.5 4.4 0.58 2.4 2.0 3.7 4.2 4.5 

2.5 3.1 3.8 0.63 2.2 2.2 4.2 3.9 4.7 

3.0 3.9 5.0 0.58 2.6 2.1 3.8 4.7 4.9 

2.8 3.5 4.4 0.60 2.4 1.9 3.4 4.0 4.1 

2.6 3.3 4.1 0.61 2.3 2.0 3.5 4.0 4.3 

Standard 

Conditions 

Xso-Tomp, .88 Iso-Temp.,RR Seasonal 

Fluctuations 

EKIDUCT 

PBU3 

PPR2 

PPR3 

All US PBUc 

All PAWc 

All PAN,PBUc 

KDEl 

MnF2 

All. PBUC 

23 23 23 23 23 28 20 28 20 28 208 28 

50 50 SO 50 50 75 75 75 75 75 35 75 

0.1 0.15 0.20 0.25 0.30 0.1 0.2 0.3 0.4 0.5 0.1 0.1 

0.84 0.68 0.51 0.35 2.9 2.5 2.0 1.6 1.2 

0.88 0.76 0.64 0.51 2.6 2.3 2.0 1.7 1.4 

0.66 0.32 b b 6.5 5.0 3.5 2.1 0.6 

0.79 0.57 0.38 0.14 4.2 3.5 2.7 1.Q 1.1 

0.81 0.62 0.43 0.24 3.8 3.0 2.5 1.9 1.3 

0.84 0.67 0.51 0.35 4.7 4.0 3.3 2.6 1.9 

0.80 0.60 0.40 0.19 4.6 3.9 3.1 2.3 1.6 

0.95 0.89 0.84 0.79 5.3 5.1 4.9 4.6 4.4 

0.89 0.78 0.67 0.56 h.h 4.1 3.7 3.4 3.0 

All MDE 1 0.94 0.87 0.81 0.75 4.5 4.3 4.1 3.9 3.8 

- Wdels extrapolated boyond tha range of experimental test conditions. 

0.42 

0.46 

0.12 

0.29 

0.35 

0.24 

0.26 

0.24 

0.27 

0.26 

2.9 

2.6 

6.5 

4.2 

3.6 

4.7 

4.6 

5.3 

4.4 

4.5 

bp'rojectsd CB OEX 5 0. 2 T,RII,O.lpp% 

cEoviromRnta1 Parameters Study I and I1 data included. 
Report XVIII 17 CPSC-IAG-84-1103 

, 

1. For potential seasonal changes in temperature and RH from 20"C, 35% RH to 

28"C, 75% RH at a constant CH20 concentration of 0.1 ppm, widely variable 

increases in modeled CW~QERT,RH,CV/CNZQERS~~ are predicted from the 

results of Study I and Study 11. For Study I, the range of modeled 

increase in CH2OER spans from sevenfold to unquantified values because 

several of the weaker emitting products have near zero or negative 

modeled CH20ERs at 20"C, 35% RN and 0.1 ppm due to suppression effects. 

For Study XI, where generally stronger emitting products were studied, a 

smaller and overlaping range of 7 to 54 fold increases in modeled CH20ER 

is predicted. 

2. Twofold increases in modeled CH~OERT,RH,CV/CH~OER~~~ are predicted with 

increases of 3 to 5 Celcius degrees in Study I and 4 to 6 Celcius degrees 

in Study 11. For humidity, approximate increases of 15 to >a50 

additional percent RH are required for twofold increases in modeled 

CH20ER in both studies. 

* 

3. Larger interproduct variation in modeled CH~UERT,M,CV/CH~OERS~~ is 

predicted as a function of changes in RH and CH20 concentration than 

temperature in both Study I and Study 11. 

4. The modeled suppression of CH20ER with increases in CH20 concentration is 

typically less variable for Study I1 test products (see Table 7) in 

comparison to Study I products (see Table VIII, Reference 1). For 

example, for Study I products the range of modeled decrease in 

CH2OERT,RH,cv/CHZOERstd with a 0.1 to 0.3 ppm increase in CH20 

concentration (at 23"C, 50% RH) spans from twofold for PBU#2 to 

unquantified values for all other test products. In contrast, for 

Study I1 the range of modeled decrease in CH~OERT,RH,CV/CH~QERS~~ spans 

from 1.3 to 2 fold for all products except PPR3. This is because the 

* Certain test products whose CH20 emissions are insensitive to changes in 

RH would require a %50% increase in. RH from 50% to >-loo% RH to achieve a 

twofold modeled increase in CH~OER.T,RH,~/CH~~ERS~~ tie., Model 11) at a 

constant temperature and Q. A -50% increase in RH from 50% RH is not 

considered because it is a non-physical solution. 
Report XVIII 1.8 CPSC-IAG-84-1103 

Study 11 products are typically stronger CH2Q emitters that have positive 

emission rates at 23"C, 50% RH and 0.3 ppm CM20. 

A graphical presentation of the effects of variation in temperature and 

RH is illustrated in Figures 1 and 2 for Models I and I1 analyses, 

respectively. These graphs are developed from the model coefficients for the 

Study I and I1 combined particleboard and paneling models. The graphs 

illustrate the effect of variation in temperature at RH levels of 25, 50 and 

75% RH. 

Sensitivity Analysis for Model I, I1 Coefficients 

An analysis has been performed to determine the impact of variation in 

model coefficients on the predicted C /C and CH2QER/CH2QERstd values of vv 

Models I and 11. This analysis assumes thgtdcomplete independence of the 

coefficients in the models. To calculate the sensitivity of Nodels I and IT. 

(Sens) to variation in each model coefficient, the derivative of the model 

with respect to a given coefficient (e.g., X) is normalized to the absolute 

value of the model and the coefficient. 

d Hodel 

dx Sens 16 = X - (Model) -' 

The resultant sensitivity value is the fractional change in the model per unit 

change in the coefficient. For example, a sensitivity of 0.1 means that a 10% 

change in the model is expected with a 100% change in the coefficient. 

The sensitivity analysis depends on both the values of the model 

coefficients determined for a given pressed-wood product data set and the 

environmental conditions that are substituted into the model. Therefore, the 

sensitivity analysis has been performed for model coefficients determined from 

combined particleboard, paneling and KDF data sets at several different 

environmental conditions (see Table 8). The ALL PBU and ALL PAN data sets 

represent both Environmental Parameters Studies I and I1 results. The results 

of the sensitivity analysis indicate several points. 
\ M ln 

E4 

4 

M 

1 

k 

W 

4 

.. 

9 

a 

4 

U 

4 

VI 

u 

u 

e4 4 

Report XVIII 21 CPSC-IAG-84-1103 

Tabla 8. Sensitivity hnalysis of Hadrl 1 ond I1 Coefifcieats 

I 

I 

I 

I 

I 

I 

I1 

I1 

If 

I1 

11 

I1 

11 

I 

I 

I 

I 

I 

I 

I1 

11 

I1 

11 

I1 

IS 

I1 

23 

28 

23 

23 

20 

28 

23 

28 

23 

23 

20 

28 

28 

23 

28 

23 

23 

20 

28 

23 

28 

23 

23 

20 

28 

28 

50 

50 

75 

50 

35 

75 

50 

50 

75 

50 

35 

75 

75 

50 

50 

75 

50 

35 

75 

50 I 

50 

75 

50 

35 

75 

75 

0.5 

0.5 

0.5 

1.0 

0.5 

0.5 

- 

- 

- 

- 

- 

0.5 

0.5 

0.5 

1.0 

0.5 

0.5 

- 

- 

- 

- 

- 

- 

- 

- 

- 

0.1 

0.1 

0.1 

0.2 

0.1 

0.1 

0.9 

- 

- 

- 

0.1 

0.1 

0.1 

0.2 

0.1 

0.1 

0.3 

Tabla 8-A: ALL PBU Data Sat 

1.00 0.00 0.00 0.00 0.00 

1.70 0.38 0.09 0.00 0.00 

1.47 0.00 0.00 0.26 0.10 

0.70 0.00 0.00 0.00 0.00 

0.48 -0.26 -0.17 -0.24 -0.17 

2.45 0.38 0.07 Q.25 0.07 

- 

- 

- 

- 

- 1.00 0.00 0.00 0.00 0.00 

2.27 0.§7 0.13 0.00 0.00 

1.92 0.00 0.00 0.20 0.36 

0.57 0.00 0.00 0.00 0.00 

0.29 -0.62 -0.12 -0.25 -0.57 

4.24 0.S5 0.13 0.16 0.33 

2.68 0.88 0.12 0.25 0.31 

- 

- 

- 

- 

Table 8-8: AIJ. PAN Drta Set 

1.00 0.00 0.00 0.00 0.00 

1.66 0.20 0.13 0.00 0.00 

1.78 0.00 0.00 0.40 0.13 

0.68 0.00 0.00 0.00 0.00 

0.36 - -0.20 -0.40 -0.36 -0.33 

2.82 0.29 0.10 0.38 0.09 

- 

- 

- 1.00 0.00 0.00 0.00 0.00 

2.00 0.61 0.18 0.00 0.00 

0.67 0.00 0.00 0.00 0.00 

0.24 -0.38 -0.20 -0.40 -0.84 

2.44 0.00 0.00 0.33 0.42 

- 4.74 0.30 0.18 0.29 0.39 

- 3.31 0.5K 0.19 0.41 0.38 

0.00 

-0.07 

-0.08 

0.17 

0.13 

-0.13 

- 

- 

- 

- 

0.00 

-0 * 11 

-0.10 

0.17 

0.21 

-0.20 

- 

- 

- 

0.00 

0.17 

0.08 

1.07 

0.40 

-0.20 

0.51 

- 

0.00 

-0.10 

-0.09 

0.65 

0.29 

-0.15 

0.35 
Report XVIXI 22 CPSC-IAG-84-1103 

Table 8. Sanaitivity Analysis of Ekrdel I and 11 Coafficienta (continued) 

I 23 50 

I 2a 50 

I 23 15 

I 23 50 

I 20 3s 

I 28 75 

I1 23 50 

I1 28 50 

I1 23 75 

11 23 50 

IT 20 35 

rz 28 75 

I1 28 75 

0.5 

0.5 

0.5 

1.0 

0.s 

0.5 

0.1 

0.1 

0.1 

0.2 

0.1 

0.1 

0.3 

Table 6-C: AIJ. UQF Data Set 

1.00 0.00 

1.67 0.45 

1.51 0.00 

0.81 0.00 

0.44 -0.32 

2.51 0.45 

- 

- 

- 0.00 1.00 

1.98 0.29 

2.30 0.00 

- 0.87 0.00 

0.28 -0.24 

4.69 0.28 

4.13 0.30 

- 

0.00 

0.02 

0.00 

0.00 

-0.04 

0.01 

0.00 

0.30 

0.00 

0.00 

-0.39 

0.30 

0.30 

0.00 

0.00 

0.30 

0.00 

-0.28 

0.28 

0.00 

0.00 

0.81 

0.00 

-0.94 

0.76 

0.83 

0.00 

0.00 

0.07 

0:oo 

-0.42 

0.06 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

-0.02 

-0.09 

0.15 

0.17 

-0.10 

0.00 

-0.03 

-0.07 

0.16 

0.22 

-0.08 

0.01 
Report XVIII 23 CPSC-IAG-84-1103 

1. For Model I, the modeled C values are most sensitive to changes in 

coefficients C and A represen ing the temperature and RH dependence of 

C . Bs td 

This was observed for all three combined product data sets. 

2. For Model 11, the results of the sensitivity analysis are highly 

product-dependent. The particleboard and paneling models are most 

sensitive to changes in coefficients C, E, and particularly . The 

is presumably based on the ma%$matical B sensitivity to changes in C 

form of the denominator of ModEf'II (i.e. ,C -0.1). In contrast, the 

MDF model is relatively insensitive to ctanges in C, , presumably 

cB 

Bs t 

std u 

because of the large value of the modeled C (i.e.,0.90 ppm). 

Bs td 

3. In general, Model 11 is more sensitive than Model I to changes in model 

coefficients. For potential seasonal fluctuations in environmental 

conditions from 20"C, 35% RH to 28"C, 75% RH, the sensitivity numbers for 

Model I coefficients range from 0.00 to 0.45. For the same environmental 

conditions , the sensitivity numbers for Model I1 coefficients range from 

0.00 to 0.94. 

Uncertainty Analysis for Model I and Model IT 

An analysis has been performed to estimate the uncertainty in modeled 

CV/CVstd and CH20ER/CH20ERstd values calculated from Model I and Model 13: 

analyses, respectively, at various environmental conditions. The uncertainty 

analysis is performed for two quantities: the uncertainty in the modeled mean 

(%.-e.? populatlon) value for a large number of future observations under 

identical environmental conditions and the uncertainty in the modeled value 

for a single future observation, These statistics could he used, for example, 

to estimate the standard error in the Model 1 prediction of the mean CH2O 

concentration inside a large population of uniformly produced compartments 

containing a single type of pressed-wood products under uniform environmental 

and air exchange conditions. The standard error in the modeled mean value 

would be the contribution of the model to the uncertainty in the prediction of 

the mean CH2O concentration inside the compartment. The standard error in an 

individual model prediction would be the model contribution to the uncertainty 

(i.e., spread) of the distribution of CW20 concentrations predicted inside the 
Report XVIII 24 CPSC-TAG-84-1103 

compartments. A detailed mathematical presentation of this uncertainty 

analysis is given in Appendix I. 

A second order Taylor Series approximation of the variance in the 

dependent variable of Hodel I and Model I1 is used to estimate the standard 

error in predicted mean (t.e., population) values for each Model under various 

environmental conditions (see Appendix I). This analysis takes into account 

the combined uncertainty of all model coefficients and the affect of any first 

order dependence between individual coefficients. This uncertainty analysis 

is therefore contrasted with the sensitivity analysis in the previous section 

where the iincertainty in CV/CVstd and CH20ER/CH2QERstd were calculated as a 

result of variation in individual model coefficients that were assumed to be 

independent, The uncertainty analysis assumes that- (1) the mathematical forms 

of Models 1 and I1 are correct and that pressed-wood data set under 

consideration (e.g., ALLPBU data set for Model I) represent the environmetrtal 

dependance of the CH20 emission strengeh of a future population of boards to 

be considered. Thus, the analysis does not account for interboard variation 

in the environmental dependence of the CH20 emission strength, either between 

boards tested in OWL studies or other boards manufactured and used elsewhere. 

The standard error in model predictions of individual observations is 

estimated from a combination of (1) the estimated variance in the modeled mean 

value as calculated with the Taylor Series approximation, and (2) the mean 

square error (mse) for the pressed-wood data set under consideration (see 

Appendix I). The mse is the best estimate of the random variation in the 

dependent variable of Models I and TI about the true mean predicted value in 

future observations. 

The results of the uncertainty analyses for the ALLPBU, ATALPAN and ALIMDF 

data sets are given in Tables 9 and 10 for Model I and Model 11 treatments, 

respective1.y. For each Model (e.g., ALLPBU for Model I) the numerical value 

of the dependent variable (e.g., Cv/Cv,,d for Model I) the root mean square 

error, and the standard error for the modeled mean value and modeled 

individual. values of future observations are given for environmental 

conditions spanning from 20°C, 35% M to 35"C, 75% RH. The coefficient of 

variation for the modeled mean and individual values of future observations 
Report XVIII 25 CPSC-IAG-84-1103 

-- Table 9. Uncertainty analysis for ALLPBU, ALLPAN and ALLMDF 

Model I Analyses. 

Standard Errar Caef. of Var. (8) 

Temp RH WL rmSe CV/CVstd Mean Single Mean Single 

("C) (%I (mm Qbs. Obs. Qbs . Qbs . 

20 35 0.5 0.28 

23 50 0.5 0.28 

28 75 0.5 0.28 

35 75 0.5 0.28 

28 75 1.0 0.28 

35 75 1.0 0.28 

20 35 0.5 0.66 

23 50 0.5 0.66 

28 75 0.5 0.66 

35 75 0.5 0.66 

28 75 1.0 0.66 

35 75 1.0 0.66 

20 35 0.5 0.14 

23 50 0.5 0.14 

28 75 0.5 0.14 

35 75 0.5 0.14 

28 75 1.0 0.14 

35 75 1.0 0.14 

A. ALLPBU Data Model I 

0.48 0.02 0.28 

1.00 0.00 0.28 

2.45 0.03 0.28 

4.60 0.04 0.28 

1.90 0.04 0.28 

3.74 0.04 0.28 

B. ALLPAN Data Model I 

0.36 0.06 0.66 

1.00 0.00 0.66 

2.81 0.07 0.66 

4.70 0.10 0.66 

2.22 0.08 0.66 

3.94 0.11 0.67 

C. ALLMDF Data Model I 

0.44 0.90 0.17 

1.00 0.00 0.14 

2.50 0.24 0.27 

4.92 0.98 0.23 

2.21 0.16 0.21 

4.41 0.13 0.19 

4 58 

0 28 

1 11 

1 6 

2 15 

1 7 

17 183 

0 66 

2 23 

2 14 

4 30 

3 17 

23 39 

0 14 

10 11 

5 5 

7 10 

3 4 
Report XVlII 26 CPSC-IAG-84-1103 

Table 10. Uncertainty analysis for ALLPBU, ALLPM and ALLMDF 

Model IT Analyses. 

20 

23 

28 

35 

28 

35 

20 

23 

28 

35 

28 

35 

20 

23 

28 

35 

28 

35 

35 

50 

75 

75 

75 

75 

35 

50 

75 

75 

75 

75 

35 

so 

7 5 

75 

75 

75 

0.10 

0.10 

0.10 

0.10 

0.25 

0.25 

0.10 

0.18 

0.10 

0.10 

0.25 

0.25 

0.10 

0.10 

0.10 

0.19 

0.25 

0.25 

1.91 

1.91 

1.91. 

1.91 

1.91 

1.91 

0.71 

0.71 

0.71 

0.71 

0.71 

0.71 

0.60 

0.60 

0.60 

0.60 

0.60 

0.60 

A. ALLPRlJ Data Model 

0.29 0.05 

1.00 0.00 

4.26 0.31 

10.99 0.43 

3.07 0.22 

9.59 0.34 

B. ALLPAN Data Model 

0.24 0.02 

1.00 0.00 

4.74 0.14 

10.58 0.34 

3.67 0.09 

9.19 0.28 

C. ALTXDF DaCa Model 

0.26 0.05 

1.00 0.00 

4.49 0.12 

9.55 0.48 

4.22 0.10 

9.16 0.45 

I1 

1.. 91 

1.91 

1.94 

1.96 

1.93 

1.94 

I1 

0.71 

0.71 

0.72 

0.79 

0.72 

0.76 

'I 

0.60 

0.60 

0.61 

0.77 

0.61 

0.75 

1 'I 

0 

7 

4 

7 

4 

a 

0 

3 

3 

2 

3 

19 

0 

3 

5 

2 

5 

660 

191 

46 

18 

63 

20 

296 

71 

15 

7 

20 

8 

231. 

60 

14 

8 

1 4 

8 
Report XVIII 27 CPSC-IAG-84-1103 

are also given in Tables 9 and 10 to facilitate direct comparisons between the 

uncertainty in Models I and 11. The coefficient of variation is corrected for 

the absolute value of the model. 

There are several similarities between the results of the Model 1 and 

Model I1 uncertainty analyses. First, the root mean square error is constant 

for each model (e.g., ALLPBU for Model I). This is because the nonlinear 

regression analyses used to determine the model coefficients were unweighted 

with regards to the numerical value of the model. Second, the standard error 

for the modeled mean Observation is much smaller than for modeled single 

observations. This is expected because the modeled mean observation is a 

result predicted from a large number of individual observations and does not 

incorporate the randomness observed in individual observations. The 

coefficient of variation in the modeled mean values are typically less than 

10%. A third similarity in the results of the Model I and I1 treatments is 

that the root mean square error is approximately equal to the standard error 

for individual observations. This indicates that the uncertainty in the 

modeled mean observation is typically small in comparison to the randomness 

(i.e+, breadth of the distribution) of modeled individual observations. 

It is instructive to compare the coefficients of variation for future 

single and mean observations between the results of the Model I and Model I1 

uncertainty analyses. This comparison can only be directly made for the 

ALLPBU and ALLMDF Models where the pressed-wood product data sets are 

identical between the Model I and IT analyses. For the ALLPBU Model, the 

coefficient of varfaeion for single and mean observations in the Model 11 

analyses are consistently a factor of 3 to 18 larger that the analogous 

coefficient of variations in the Model I analyses. In contrast, the 

coefficients of variation in the single and mean observations for the ALLMDF 

Models are comparable between the Model I and Model I1 analyses. This may be 

caused in part by the mathematical form of Model I1 and the selected standard 

test conditions of 23"C, 50% RH and 0.1 ppm. The resulting denominator of 

* For the ALLPAN Models, certain data sets for weak emitting paneling 

products from Environmental Parameters Study I could not be included in 

Model 11 type analyses because the CH2QERs were < zero at standard 

conditions of 23"C, 50% RH and 0.1 ppm CHZO. 

* 
Report XVIII 3% C PS C - I AG - 84 - 1 10 3 

Model PI (i.e., Qstd - 0.1) is unstable for weak emitting products whose 

Qstd values approach 0.1 ppiii. This may cause increased uncertainty in 

Mode3 YT predictions of future olsservar.i..ons kl'riere the Model. coefficients are 

developed from pressed-waod data sets of weak eiiiittlng boards. Consistrent 

with this hypothesis, the ALLPBU I':odel (which has the largest cmcertai.nties 

for Model I1 predictions) is developed from four hoards with Qstd values of 

0.14, 0.46, 0.24, and 0.41 ppm. In contrast, the :model.ed CBstd values for the 

two boards in the ALLEIDF data set are !..05 and 0.56 ppm. A potential solution 

to the mathematical. singulari.ty in the denoiiiiriatror of Model II would be to 

iio~ii~alize the Model. IT data sets to standard conditions O€ 23"C, SO% RII and 

0 ppm. Although the CH20ER at standard conditions could only be extrapolated 

from avai.Lable experimental data, the ilsw mathematical fom of the denoininator 

of Model I1 (i.e., C~~td) would then be more stable for a wider range of 

product: emission strengths. 

SINKS STUDY 

The CH 0 sinks study for gypsum-wallboard is complete. Several types of 

experimental sti.dbr?s have been performed 1.0 inves'l.i.gatr: r:he time dependent 

CH 0 sorption and desorption characteristics of gyps-m board. The resul.ts of 

two 3 to 4 week long sorption studies were presented in Reports XVI and XVII. 

Gypsum board coi~dit:i.on.;..d at <lo ppb CH c) was exposed to CH 0 from a generation 

apparatus at 100 and 400 ppb in separate experiments. Preliminary modeling 

indicated exponen(:ial risetiine values of 2.2 l:o 6.4 days an.d steady state CH 0 

concent~rati.ons of 91 to 98% of the generated CH 0 I-evels. 

2 

2 

2 2 

2 

2 

Addi Gjonal 1 co 2 day sorption studies have been pecforrned on gypsurn 

board to study the initial time-dependent behavior of gypsum board exposed to 

sudden increases in CI-E 0 vapor concentration. 1 II these expprirneiits ~ gypsum 

board conditioned at 100 ppb CH 0 wzs exposed to 200 ppb CH2C from the 

generat i.on apparatus ~ The temperature, ELF1 arid air exchanp?/loading ratio 

were maintained at 23"C, 50% RH and 0.43 m/h, respecti-vcly, during both the 

100 ppb conditioning atid 200 exposur- periods. 

2 

2 
Report XVIII 29 CPSC-IAG-84-1103 

The results of the short duration sorption studies can be characterized 

by two separate phenomena. Within the first 2 hours following the change from 

100 to 200 ppb from the CH20 generation apparatus, the CH 0 concentration 

inside the gypsum board exposure chamber rose rapidly to about 120 ppb. Two 

hours is the approximate time required to completely exchange the atmosphere 

inside chamber assuming perfect mixing and an air exchange rate of about 

1.5 h-l. From this time through the duration of the experiment, the CHZO 

concentration in the gypsum board exposure chamber rose very slowly, 

consistent with the 2 to 4 day risetimes observed in the previous long term 

sorption experiments. It is instructive to nate that an Initial rapid rise in 

CH 0 concentration was also observed in the first set of data taken 2 to 5 

hours after the start of the long term sorption experiments. However, the 

short duration sorption experiments were needed to quantiEy this phenomena. 

2 

the 

2 

To model the time-dependent sorption behavior of the gypsum board 

observed in both the 1 to 2 day and 3 to 4 week sorption experiments, the 

following expression is considered. 

R - Z + (A - 2) ) -time/ 7 (1 - e (5) 

where : 

Z = the modeled value of R achieved during the first 2 hours of the 

experiment, 

A - the modeled steady state (i.e., maximum) value of R achieved at time 

infinity , and 

7 - the modeled exponential risetime of the sorption process. 

The expression for R is the ratio of the change in CH2O concentration 

inside the gypsum-board-exposure ([CH20]gyp) and reference ([CH20]ref) 
Report XV:C'T. I. 30 CPSC-TAG-84-1103 

chambers. This ratio of delta concentrations is normalized for differences in 

the potential span of CM20 concentrations in each chamber during the 

experiment. The normalization factor provides an R value of unity in the 

ahscence of CH20 sinks in both the reference and gypsPLr71-boara-exposure 

chambers. R is calculated as 

where : 

= the final CH20 concentration in the abscence of CM20 sinks [CH201fina1 

(e.g., 0.4 ppm in the 0 to 0.4 ppm sorption series), and 

0 0 [ 1 gyp ? [ CHp 1 ref = the measured CH20 concentrations in the gypsumboard-exposure and reference chambers at the start of the experiment. 

The experimsntal data and the resulting fit to Equation 5 are illustrated 

in Figure 3. The model coefficients determined from a SAS non-linear 

regression analysis are 

z = 0.15 +- 0.01, 

A = 0.94 k 0.01, and 

7 3 3,1. -C 0.1 days 

The root mean square error for the regression analysis is 0.065. 

Two types of CH 0 desorption studies have been performed. During a 

week-long study, the CH 0 concentration of the supply air to the gypsum board 

chamber was dropped to and maintained at zero 1evel.s. In duplicate one-day 

2 

2 
al 

n 

0 

w 

m 

-4 

c 

x 

111 

m 

0 

LI 

a 

c, 

-4 

0 

c 

L3 

m 

u 

m 

w 

m 

n 

orl 

k? 

4 

I 

N 

I 

N 

+ 

v 
Report XVII:I 32 CPSC-IAG-84-1103 

studies, the CH 0 concentration in the supply air was dropped from 100 ppb to 

50 ppb . In all experiments, the temperature, Rlll, and air exchange/loading 

ratios werc maintained at 23"C, 50% Hi, and 0.113 m/h, respectively. 

2 

The results of both experimental designs can be characterized by two 

phenomena analogous to those observed in the sorption experiments. Within the 

first 2 hours the concentration inside the gypsyum board exposure chamber 

dropped about 20% of the total change in CH 0 concentration in the supply air 

from the generation apparatus. Froin 1:his period though the duration of the 

experiment the CH 0 concentrat-ion dropped very slowly, consistent with a decay 

period of several days. 

2 

2 

To model the time-dependent desorption be!-t;ivior of the gypsum board 

observed in both the 1 week a~d 1 day desorpt;on studies, the followjng 

expression is considered. 

I -cime/q 

R = (1 - z9e 

where : 

7 = the model.ed exponential decay period of the desorption process 

The expression for R' is analogous to that for R and is calculated as I.he 

quantity 1 - R. In conl;rast to the expression for K, the ratio of delta CH20 

concentrations in the gypsum-board-exposure and reference chambers expressed 

in R' is normalized to provide an R' of zero in the abscence of sinks in both 

chambers, 
Report XVIII 33 CPSC-IAG-84-1103 

The experimental data and the resulting fit to Equation 7 are illustrated 

in Figure 4. The model coefficients determined from a SAS non-linear 

regression analysis are 

2 = 0.21 f 0.01, and 

7 - 2.6 k 0.3 days. 

The root mean square error for the regression analysis is 0.04. 

Further nonlinear regression analyses of the CH 0 sorption and desorption 

data sets for gypsum board have been performed tor compare the temporal 

2 

dependence. of the CH 0 sorption and desorption processes. The goal was to 

evaluate the consistency between the nonlinear sorption and desorption model 

coefficients. To accomplish this, non-linear regression analyses of the 

sorption desorption data sets have bee2 performed using the sorption and 

desorption models with a single set of model coefficients A modified form of 

the desorption model was required to include both the A and Z coefficients 

incorporated in the sorption model. 

2 

and * 

-time/r R = (A - Z).e 

The model coefficients determined from the non-linear regression analysis are 

Z - 0.15 k 0.01, 

A - 0.92 f 0.01, and 

7 = 2.9 _+ 0.1 days. 

The r value of 2.9 days is the approximate average of the 3.1 and 2.6 day 

values of 7 for the individual sorption and desorption models, respectively. 

These results indicate that gypsum board can be a potentially strong buffer 

against fluctuations in indoor CH 0 concentrations. The A value of 0.92 may 

indicate a small (i.e., 5-10s) permanent CH 0 loss mechanism for gypsum board. 

The root mean square error for the regression analysis is 0.06. 

2 

2 

* This option is available in the SAS Institute non-linear regression 

analysis procedure 
0 

%I 

VI 

.rl 

c 

x 

m 

.-I 

z 

0 

a 

aJ 

e 

;cI 

/ 

/ 

+¶ 

10 

I 

i 

I 

I 

I- 
Report XVIII 35 CPSC-PAG-84-1103 

SLOW DECAY STUDY 

The experimental investigation of the decline in CH20 concentration in 

the slow decay study lasted 14 months through March, 1985. The final FSEM 

measurements of the individual boards could not be performed due to resource 

restrictions. The raw CH 0 concentration data and a summary of environmental 

parameters are listed in Table 11. Assuming no variation in environmental 

conditions, the raw CH 0 concentration data can be fit to a single exponential 

decay function. 

2 

2 

-t ime/r ==A.t? [ CH20 1 vapor (9) 

The calculated decay period r is 2.2 5 0.2 years. 

To assess the impact of variation in temperature, RH and air 

exchange/loading ratio on the calculated CH 0 emission decay period, a 

correction model for the CH 0 concentration data is developed based on Model I 

from the environmental parameters studies. However, additional assumptions 

for Model I must be considered 

2 

2 

1. 

2. 

Variation in (N/L)std from 0.5 m/h, used in the environmental parameters 

studies, to 0.15 m/h, used in the slow decay study has a minimal impact 

on the Model I coefficients. 

Model I coefficients determined from a combination of individual 

particleboard, paneling and medium density fiberboard data sets can be 

applied to an environmental chamber experiment with mixed pressed-wood 

products. 

To refine Model I to better predict the impact of small changes in 

temperature and RH about standard conditions, a subset of available data taken 

in Envlronmental Parameters Studies I and I1 is selected for nonlinear 

regression analysis. All particleboard underlayment, hardwood plywood 
Report XVIII 36 CPSC-ZAG-84-1103 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

1.5 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

0.00 

0.07 

0.50 

0.53 

0.93 

1.17 

1.23 

1.30 

1.40 

1.63 

1.73 

1.80 

1.97 

2.07 

2.20 

2.43 

2.50 

2.60 

2.80 

2.97 

3.00 

3.15 

3.30 

3.43 

3.50 

3.70 

3.83 

3.87 

4.10 

4.17 

4.33 

4.40 

4.53 

4.60 

4.67 

4.77 

4.90 

5.82 

5.99 

6.05 

6.22 

6.28 

6.45 

6.55 

5.81 

6.91 

23.0 

23.0 

23.0 

22,6 

22 ~ 6 

22.9 

23.0 

22.6 

22.7 

23.5 

23.0 

23.0 

22.7 

22.6 

23.0 

22.6 

22.7 

22.6 

23.0 

22.6 

23.1 

23.0 

23.0 

23 .O 

23.0 

22.4 

22.4 

23.0 

23,O 

23.0 

23.0 

23.0 

23.0 

23.0 

23.0 

22.5 

23.4 

23.0 

23.0 

23.0 

23.0 

23.0 

23.2 

23.8 

23.0 

23.0 

57.0 

57.0 

47 .o 

47.0 

45.0 

47.5 

48.0 

47.5 

49.5 

50.0 

51.5 

50.0 

50.5 

49.5 

50.0 

47 .O 

51.. 5 

50.1 

50.0 

48.9 

50.1 

50.0 

50.5 

49.0 

49.0 

49.5 

51.2 

49.5 

50.1 

48.5 

50.0 

50.0 

50.0 

50.0 

50.0 

51.0 

51.0 

50.0 

50.0 

50.0 

52.0 

51.0 

49 .O 

51.5 

49.5 

49 .O 

0.40 

0.40 

0.40 

0.40 

0.45 

0.45 

0.45 

0.45 

0.45 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.42 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.42 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.37 

0.37 

0.37 

0.37 

0.37 

0.37 

0.37 

0.39 

0.39 

0.523 

0.513 

0.409 

0.407 

0.382 

0.431 

0.382 

0.437 

0.453 

0.399 

0.417 

0.393 

0.411. 

0.395 

0.389 

0.366 

0.438 

0.401 

0.391 

0.387 

0.398 

0.390 

0.390 

0.371 

0.372 

0.355 

0.343 

0.353 

0.371 

0.343 

0.363 

0.356 

0.362 

0.349 

0.352 

0.343 

0.355 

0.360 

0.391 

0.395 

0.357 

0.395 

0.345 

0.390 

0.343 

0.335 

O.lr-57 

0.448 

0.434 

0.448 

0.451 

0.468 

0.406 

0.488 

0.480 

0.380 

0.403 

0.392 

0.417 

0.413 

0.388 

0.403 

0.435 

0.418 

0.390 

0.409 

0.392 

0.389 

0.385 

0.377 

0.378 

0.382 

0.353 

0,355 

0.369 

0.352 

0.362 

0.355 

0.361 

0.348 

0.351 

0.351 

0.335 

0.354 

0.384 

0.388 

0.337 

0.381 

0.340 

0.348 

0,344 

0.339 
Report XVIII 37 

Table 11. Slow decay study data file (cont.) 

CPSG-IAG-84-1103 

47 

48 

49 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

60 

61 

62 

63 

64 

65 

7.05 

7.14 

7.61 

7.74 

7.87 

7.94 

8.10 

8.40 

8.57 

9.03 

9.56 

9.82 

9.92 

10.30 

10.70 

12.50 

13.0 

13.9 

14.4 

23 .O 

22.5 

23.0 

22.7 

22.8 

23.0 

22.8 

23 .O 

23.5 

22.5 

23.0 

23.0 

22.5 

22.9 

23.0 

23.0 

22.9 

23.0 

22.0 

49.0 

49.7 

50.0 

50.0 

47 .O 

50.0 

50.0 

50.0 

48.0 

48 .O 

48.0 

50.0 

48.0 

49.8 

50.0 

50.0 

46 .O 

47 .O 

48.0 

0.39 

0.39 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.4C 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.40 

0.4~1 

0.304 

0.326 

0.354 

0.323 

0.309 

0.242 

0.301 

0.272 

0.337 

0.348 

0,296 

0.289 

0.286 

0.331 

0.351 

0.283 

0.239 

0.259 

0.270 

0.308 

0.313 

0.344 

0.331 

0.334 

0.242 

0,306 

0.335 

0,272 

0.379 

0.308 

0.288 

0.312 

0.335 

0.351 

0.283 

0.262 

0 I 275 

0.309 

Formaldehyde concentration data corrected to standard conditions (i.e., 23"C, a 

50% RH, 0.15 m/h) using Equation 2. 
Report XVIII 38 CPSC - IAG - 84 - 1103 

paneling and medium density fiberboard data taken at 23-28°C and 40-808 RH are 

included. These environmental conditions bracket the range of conditions 

encountered with the slow decay study. The resulting model coefficients are 

c => 5290, 

A - 0.927, 

= 0.656, 

std Kg 

B = 0.163, and 

E - 0.017. 

The CH 0 concentration data corrected to 23”C, 50% M, and 0.15 m/h are 

listed in Table 11. Fitting this data to Equation 9, the calculated decay 

period is 2.3 i 0.2 years. Based on approximately 14 months of data, the 

impact of the small experimental variation in temperature, RH, and N/L during 

the slow decay study appears to be small. 

2 

Care should be used in the interpretation of the resul-ts of the slow 

decay study. The 14 month duration of the study may be i-nadequate to 

accurately measure the CH 0 emission decay period of this collection of 

boards. The data may reflect a relatively rapid decay of CM 0 emissions from 

a few of the strongest emitting boards as opposed to the entire. collection of 

products. 

2 

2 

FAST DECAY STUDY 

The “fast” decay study has been completed with data taken through 

December 1984. This includes seven measurement series of medi.m density 

fiberboard, particleboard underlapent, industrial particleboard, print 

paneling, paper (overlayed) paneling, and domestic paneling samples acquired 

during the pressed-wood produet survey. During each measurement series, CH20 
Report XVIII 39 CPSC-IAG-84-1103 

emission rate measurements were performed on three identical sites on a 

specific side of each 4 x 4 foot board. Paneling samples were measured on 

bath the decorative face and back sides. The experimental data spans an 16 

month decay period starting approximately 6-12 months after board manufacture, 

A summary of the environmental conditions inside the storage room at the 

time of the FSEM measurements is given in Table 12. Temperature control is 

quite uniform throughout the study. Relative humidity values tend to follow 

seasonal fluctuations, particularly for the first seven test cycles. The 

lowest RH levels occur during winter months of 1983-84 while the highest W 

levels occur during late spring and summer, 1984. After the first measurement 

series, the CH 0 vapor concentration was maintained at low levels between 0.04 

and 0.11 ppm. 

2 

Due to the sub-50% RH levels for measurement series 3 to 5 and greater 

than 50% KH levels for measurement series 6 to 8, the measured decay periods 

may be lengthened in comparison to what would have been determined from these 

test products under constant temperature and RH conditions (i.e., 23"C, 50% 

RH). As a result, a correction model for the temperature and RH dependence of 

the measured CH20 emission rates from the fast decay study boards is 

considered . 

Temperature, RH Correction Model 

Several simplifying assumptions are considered for Model I1 (l.e., 

Equation 3), the CH 0 emission rate model that was developed in the 

environmental parameters studies. 

2 

1. The environmental parameters studies data and modeling can be applied to 

FSEM measurements. 

2. For small variation in temperature and KH about 23°C and 50% RH, F 

and F (RH) are approximately equal to unity. 

Kg 
Report XVIXI 40 

Tabla 12. Envlrarrmantal conditions inaid. the stors80 soom for 

the fast decay study boards at the tiw 02 FSEM meaausemasts 

CPSC-TAG-84-1103 

MeaaurPment Series 

1 2 3 4 5 6 

- _-- ._- 

Temp ('C) 23 + 1 23 f 1 22.5 + 0.9 23.0 + 0.7 22.5 + 0,4 22.8 + 0.6 

RB (7.1 50 + 10 50 + 10 43 + 10 45 + 7 48 + 4 52 + 3 

[CB201 (PPI 0.22 + 0.04 0.0s + 0.02 0.09 + 0.02 0.07 + 0.02 0.05 + 0.02 0.07 + 0.02 

1.1 3.0 4.5 6.4 8.0 9.6 

Date 8/83 10183 11/83 1/84 3/64 4/84 

I 

7 6 S 

Tamp ('C) 23.2 f 0.4 22.7 t 0.5 23.0 * 0.4 

RE (X) 56 f 4 46 f 1 52 t 2 

[CH20J (PPI 0.11 f 0.03 0.09 f 0.06 0.06 f 0.01 

Elapse Time 12.5 

(montha) 

14.9 17.3 

Data 7/84 10164 12/84 
Report XVIIf 

Equation 2 then becomes 

49 

CH OERstd 2 

To refine this model to better predict the impact of small changes in 

temperature and RH about standard conditions, a subset of available data taken 

in Environmental Parameters Studies I and I1 is selected for non-linear 

regression analysis. All particleboard underlayment, hardwood plywood 

paneling and medium density fiberboard data taken at 23-28°C and 40-80% RH are 

included. These environmental conditions bracket the range of conditions for 

the fast decay study. The resulting model coefficients are: 

c - 10500, 

A = 1.43, and 

- 0.461 ppm. 

std cB 

To further simplify Equation 10, one additional assmption is considered. 

3. A low CH 0 vapor concentration (i.e., C << CB ) is maintained during 

std 2 V 

the monitoring period due to the design of the FSEM. 
Report XVIII 

Therefore, 

42 CPSC-IAG-84-1103 

CH20E%, RH 

CH OERstd 2 

11 A -C(T - -)*(RH/50) .C 

Bstd 296 

P I 'v -, 

- e -0.1 

Bs td 

Collecting constants and rearranging, the fi.nal expression for the CH 0 emission rate correction model is: 

2 

CH OERT RH h) 2 , .1 1 = 

-10500(, - ;-;) 

CH20ER23 C , 50%RH 

e 1-28 

Formaldehyde Emieon Rate Decay Modeling 

A single-exponential, CH OER decay model with a zero steady-state CH20ER 2 

is considered for the fast decay study data, 

CH~QER - CH~OERO.~ - t ime/r 

where CH20ERo equals the modeled CH20ER at the beginning of the study. 

Multiple exponential decay models and positive steady-state CH OERs were 

considered but could not be properly evaluated due to resource restrictions. 

2 

The experimental. CH20ER data plus the CH OER data corrected for 

temperature and RH (using Equation 12) were fit to Equation 13 using nonlinear 

regression analyses. The normal regression assumption of equal absolute 

errors in all measured CH OERs was modified to assume equal errors in 

proportion to the measured CH OERs (i.e., equal coefficients of variation). 

This procedure tends to deweight the initial measurement series where Lhe 

CH OEKs and thus the absolute magnitude of the measurement errors are largest. 

This weighting procedure is accomplished by weighting the sums of squares of 

2 

2 

2 

2 
Report XVIII 43 CPSC-IAG-84-1103 

residuals in the regression analysis by the magnitude of the inverse of the 

Model (i.e., Equation 13). ‘2’ The resulting r values obtained from for all of 

the decay study boards are listed in Table 13 and summarized by product 

category in Table 14. The temperature and RH corrected decay periods are 

typically 0 to 3 months shorter than those calculated from the uncorrected 

data. The corrected z values range from about 8 to 25 months for all test 

products. The average corrected r values rank from 10.7 2 2.1 months for 

paneling to 13.2 13.0 months for particleboard to 18.8 2 4.4 months for 

medium density fiberboard, These 7 values correlate generically with the 

order of increasing product emission strength and increasing product 

thickness. 

fast 

Front/Back Emission Ratios for Paneling 

A secondary objective of the fast decay study was to examine front to 

back CH 0 emission ratios of the hardwood plywood paneling samples as measured 

by the FSEM. This information could impact environmental chamber test designs 

for paneling and the modeling of the impact of paneling on indoor CH 0 

concentrations. The front to back CH20 emission ratios for each measurement 

series of the fast decay study are summarized in Table 15. These ratios are 

calculated as the average of three FSEM measurements taken on the decorative 

front of the board divided by the average of three FSEM measurements taken on 

the back of the board. 

2 

2 

For print paneling the average frontback ratios for individual boards 

vary from 0.5 to 1.4 with an overall mean of 1.0. Four out of five of the 

boards have mean ratios within approximately one standard deviation of unity. 

For the paper overlayed paneling the average frontback ratios for individual 

boards vary from 0.3 to 0.6. The overall mean ratio of 0.4 k 0.2 indicates 

that CW 0 emission strength from the back of paper overlayed paneling is 

typically 2 to 3 times stronger than the emissions from the front of the 

panels. For domestic veneer overlayed paneling, the average front to back 

ratios range from 0.8 to 2.1. With the exception of PAND1#3, which was by far 

the strongest emitting domestic paneling in the pressed-wood product survey, 

the 2 

2. McCullagh and Nelder, General Linear Models, Chapman and Hall. 
Report XVIII 44 CPSC-IAG-84-1103 

Table 13. Summary of decay periods (7, months) for 

individual boards in the fast decay study. ll__l - .----._.I 

Board r: T,RH Corrected 7: T,RH Uncorrected 

-I.._ 

MDF1#3 17.3 f 4.4 19.6 -C 4.7 

MDF2#5 20,O -t 7.2 23.2 k 9.4 

MDF2#6 25.2 111.3 29.7 f 14.6 

MDF3#9 14.0 F: 1.8 15.0 d- 2.6 

PBU1#1 11.0 2 2.7 14.2 I 3.6 

PBU1#5 13.3 f 3.0 14.6 f. 3.5 

PBU3#6 14.3 f. 3.5 16.0 1- 4.4 

PRXl#4 11.0 f 2.7, 10.9 2 2.8 

PBI2#5 19.5 -C 5.7 22.1 5 7.8 

PBI3#4 11.6 f 1.9 13.0 k 2.3 

PB13#5 11.9 t 2.5 14.0 I 3.5 

PANPRP#2 Face 11.0 +. 2.2 11.0 t- 2.3 

PANPR1#2 Back 10.8 t- 1.9 11.0 f. 1.6 

PANPR1#6 Face 12.0 rt 1.9 13.4 k 1.8 

PANPK2#4 Face 10.0 k 1.4 10.9 rt 1.8 

PANPR2#4 Back 7.9 9 1.5 8.0 t 7..6 

MDF3#3 17.7 zf: 3.5 20.0 I h.3 

PANPR1#6 Back 10.4 zf: 1.6 11.2 I 2.0 

PANPR2#6 Face 8.0 f. 1.4 7.9 I 1.2 

PANPR2#6 Back 9.8 ? 2.3, 9.0 2 1.9, 

PANPR3#2 Face 25.5 zf: 13.1 31.5 15.5 

PANPR3#2 Back 15.3 f 4.1 15.5 -t 3.5 

PANP1#6 Face 9.9 f 2.1 12.0 k 2.6 

PANP1#6 Back 12.4 F: 1.6 12.8 -C 2.5 

BANP2#2 Face 8.4 f 1.3 8.5 t- 1.3 

PANP2#5 Fack 8.3 t 1.4 9.4 k 1.9 

PANP2#5 Back 10.0 -t 1.8 9.9 2 1.7 

PANP3#6 Face 15.0 It 5.7 14.7 t- 1.7 

PANP3#6 Back 12.6 t- 3.3 12.8 d- 4.0 

PAND1#3 Face 20.4 f 6.3 22.6 t- 8.0 

PAND1#3 Back 

PAND1#4 Face 8.9 rt 2.0 10.0 2 2.7 

PAND1#4 Back 8.0 ? 0.2 8.0 -f- 1.8 

PAND3#3 Back 13.0 F: 2.9 14.7 P 3.1 

PAND3#4 Face 13.3 -t 3.4 14.3 k 3.4 

PAND3#4 Back 10.0 2 1.3 10.2 a 1.6 

*Data Q-test ieioved at a >96% confidence level in subsequent calculations of 

average 7 values for each product category (i.e., Table 14). 

PANP2#2 Back 10.0 f 2.3 9.9 2 2.2 

* * 

10.7 2 1.5 11.1 2 2.0 

PAND3#3 Face 10.9 F: 3.5 12.7 -I- 3.7 
Report XVIII 45 CPSC-IAG-84-1103 

Table 14. Summary of average decay periods 

(7, months) for the fast decay study. 

7: T,RM Corrected 7: T,RH Uncorrected 

Average Range Ave rag e Range 

Product 

Medium Density 18.8 rf: 4.4 14.0 - 25.2 21.5 C 5.4 15.0 - 29.7 

Fiberboard 

Particleboard 

(All data) 

- Underlayment 

- Industrial 

13.2 +. 3.0 11.0 - 14.3 15.0 -b 3.9 10.9 2 22.1 

12.9 2 1.7 

11.5 2 0.5 

11.0 - 14.3 

11.0 - 11.9 

14.9 4 0.9 

15.0 ? 4.9 

14.2 - 16.0 

10.9 - 22.1 

Paneling (All data) 

- Print 

- Face 

- Back 

10.7 k 2.1 

10.6 Lt: 2.2 

10.3 -_t 1.7 

10.8 k 2.7 

7.9 - 15.3 

7.9 - 15.3 

8.0 - 12.0 

7.9 - 15.3 

11.2 & 2.3 

10.9 4 2.5 

10.8 5 2.3 

10.9 .fr 2.9 

7.9 - 15.5 

7.9 - 15.5 

7.9 - 13.4 

8.0 - 15.5 

- Paper 

- Face 

- Back 

10.8 k 2.3 

10.4 -_t 3.2 

11.3 2 1.4 

8.3 - 15.0 

8.3 - 15.0 

10.0 - 12.6 

11.3 4 2.1 

11.2 rt 2.8 

11.4 4 1.7 

8.5 - 14.7 

8.5 - 14.7 

9.9 - 12.8 

Domestic 

- Face 

- Back 

10.7 k 2.0 

11.0 f 2.2 

10.4 -C 2.1 

' 8.0 - 13.3 

a,9 - 13.3 

8-0 - 1.3.0 

11.6 t 2.4 

12.3 2 2.3 

11.0 k 2.8 

8.0 - 14.7 

10.0 14.3 

8.0 - 14.7 
Report XVIIX 46 CPSC-IAG-84-1103 

TabLa 1s. Surrr~asy of irmtlback CB2Q miarion ratios 

wf faat decay atudy bud.. 

Maasurrmmt Sar1as 

1 2 3 4 S 6 7 8 Q 

Product Ms an 

PAUPRMZ 

PAUFRlC6 

PANPR2Wh 

PANPR2#6 

PANE'R3#2 

All PMFR 

PANPlM 

PMpp292 

PANP2+5 

PMP3#6 

All PANP 

PANDlY3 

PmM4 

Prn3#3 

PAND3C4 

All PAN2 

0.96 0.90 

0.86 0.58 

0.80 1.63 

0.44 0.4Q 

0.72 1.07 

0.43 0.28 

0.37 0.45 

0.26 0.10 

0.52 0.S3 

1.74 1-28 

0.30 1.30 

1.00 0.86 

0.83 0.80 

-..- 0.70 0.85 0.94 1.33 

1.00 1.31 1.15 0.84 0.86 

--- 1.M 1.27 1.33 1.01 

0.9$* 0.S6 0.S0 0.58 0.46 

_-- 0.7s 0.91 1.10 1.81 

0.42 

0.38 

0.30 

0.6s 

0.41 

0.36 

0.34 

0.so 

2.0s 

1.21 

0.88 

0.87 

0.68 0.33 0.20 

0.S4 0.38 0.32 

0.33 0.21 0.41 

0.82 0.71 0.29- 

2.13 2.05 2.07 

0.88 0.56 1.42 

0.79 1.2s 0.40 

1.13 1.21 0.93 

0.75 

1.00 

1.20 

0.27* 

1.23 

0.55 

0.28 

0.27 

0.82 

2.70 

1.46 

0.m 

1.4s 

1.20 

1.05 

2.12 

0.02 

1.42 

0.28 

0.32 

0.15 

0.84 

4.23. 

0.89 

0.71 

1.01 

0.90 2 0.16 

0.97 2 0.21 

1.42 2 0.45 

0.53 0.07 

1.04 0.26 

0.38 2 0.38 

0.38 +- 0.10 

0.30 2 0.08 

0.27 2 0.09 

0.82 f: 0.11 

0.41 2 0.16 

2.12 0.31 

1.09 2 0.26 

0.84 f: 0.23 

1.01 t 0.20 

1.21 2 0.53 

-1 

- 1 

'Data Q-teat reamvad at a > $02 confidmca luval Srm mubmqmt ealculationa ol nuen irantlb8ck amiraion ratios. 
Report XVIII 47 CPSC-IAG-84-1103 

the average ratios for domestic paneling are within one standard deviation of 

unity. Thus, on the basis of the fast decay study data, the majority of the 

print and domestic paneling appear to have fairly uniform CH Q emission 

strength from the front and back of the panels. In contrast, paper overlayed 

paneling appears to have consistently weaker CH 0 emission strength from the 

decorative front of the panels. 

2 

2 

PERMEATION BARRIERS STUDY 

The permeation barriers study has been divided into three major parts: 

(1) the measurement of the CH 0 transport coefficients of decorative floor 

3 coverings, (2) simulated flooring experiments using an QRNL 0.2 m 

environmental chamber, and (3) permeation barriers modeling to predict the 

impact of decorative flooring materials on CH O emissions from particleboard 

underlapent. results of the measurement of CH 0 transport coefficients 

of common decorative floor coverings were summarized in Report XV. A 

preliminary evaluation of the results of the simulated flooring experiments 

and comparisons to permeation barriers modeling are given in this report. 

2 

2 

The 2 

Simulated Flooring Experiments 

Three separate floor coverings were tested in the simulated flooring 

experiments. Permeation Barrier I consisted of waffled sponge rubber cushion 

and cut and loop pile nylon carpet. Permeation Barrier II consisted of 

urethane foam cushion and cut pile nylon carpet. Permeation Barrier 1x1 

consisted of vinyl tile flooring. The physical specifications of these 

decorative flooring materials have been summarized in Table I1 of Report XV. 

The basic experimental design of the simulated flooring experiments has 

remained unchanged from the outline of the study presented in Report XV. me 

testing sequence was to measure the CM20 emissions from uncovered 

particleboard underlayment, floorlng covered underlayment and finally repeat 

measurements of the uncovered underlayment. The dual measurements of the 

uncovered particleboard are used to estimate the temporally dependent decline 

in the CH 0 emission strength of the board during the study. The experimental 

apparatus consisted of a 0.2 m3 Teflon-lined chamber with one wall removed and 

2 
Report XVIII 48 CPSC-IAG-84-1103 

replaced by the simulated floor. Formaldehyde emissions testing was performed 

23 

at for both uncovered 

and flooring covered underlapent. Four different air flow rates from 2 to 15 

L/min (i-e., 0.6 to 4.4 air exchanges per hour) were used to create a wide 

range of CH 0 concentrations inside the test chamber. The resulting air 

exchange/loading ratios were 0.37 to 2,8 m/h. A small fan was operated inside 

the chamber to create turbulent mixing independent of the air flow rate 

through the chamber. Separate conditioning procedures were used €or 

measurements of uncovered and flooring covered underlayment. For bare 

underlayment, environmental conditions of 23"C, 50% RH and <0.1 ppm CH 0 were 

maintained for 32 weeks prior to CH 0 emission measurements. A second, brief 

conditioning period equal to 3 to 4 air exchanges of the chamber was then used 

prior to CH 0 measurements at each of the four different air flow rates. For 

carpet-covered-particleboard, a minimum of one week conditioning period was 

used at each air flow rate prior to CH2Q emission measurements. For tilecovered-particleboard, six week conditioning period was used prior to CH 0 

emission measurements. 

23 2 0.5"C, 50 2 3% RH and a floor loading of 1.6 m /sn 

2 

2 

2 

2 

8 2 

The average CH 0 concentration data for uncovered and flooring covered 

particleboard underlayment as a function'df air flow through the environmental 

chamber are summarized in Table 16. Examination of the uncovered 

particleboard data indicates a twofold decrease in CH 0 emission strength 

between measurement series I and XI and a comparatively small change between 

series I1 and 111. The strong decline in CH 0 emissions between series I and 

I1 may be caused in part by the lenghty seven month duration of this portion 

of the permeation barriers studies. Following the initial measurements of the 

uncovered underlayment, approximately 3 months were lost due to various 

experimental problems including (1) shifting the 0.2 m measurement chamber 

from our Elotpack environmental chamber to a laboratory bench with the start of 

the Environmental Parameters Study 11, (2) eliminating air leaks at the joint 

between the simulated floor and the base of the chamber, and (3) determining 

how long the carpet, carpet cushion, and underlayment system would take to 

reach a steady state CH 0 concentration. In contrast the second phase of the 

permeation barriers study between particleboard measurement series I1 and I11 

required approximately 3 months. 

2 

2 

2 

3 

2 
Table 16. Formaldehyde vapor concentration data (pp) from the simulated 

flooring experiments of the permeation barriers studya 

Air Flow Particleboard Carpet, Cushion Particleboard Carpet, Cushion Particleboard Tile Floor 

rate (L/min) Seriea I Barrier I Series I1 Barrier 11 Series I11 Barrier I11 

2 0.429 * 0.024 0.147 f 0.016 0.220 f 0.011 0.232 t 0.011 0.238 f 0.005 0.008 i 0.005 

5 0.319 f 0.022 0.086 f 0.005 0.156 f 0.008 0.147 t 0.005 0.168 f 0.005 - 

8 0.254 * 0.020 - - - - - - 0.063 f 0.005 0,100 f 0.005 0.089 f 0.005 0.129 f 0.005 10 

15 0.154 f 0.012 0.038 t 0.005 0.078 f 0.005 0.041 t 0.005 0.087 f 0.005 

- 

- 

~ ~ ~ 

aAL1 data listed to three signifioant digsts to reduce routad off error in subsequent calculations. 
Report XVIII 50 CPSC-IAG-84-1103 

To investigate the impact of the decorative €loor coverings on the CH20 

emissions from the particleboard underlayment, estimates of the CH 0 emission 

strength of the uncovered particleboard during flooring-covered experiments 

are required. These temporal-dependent estimates of board emission strength 

are simplest to model when the CH 0 emissions from the uncovered underlayment 

change little between measurements taken before and after the flooring covered 

experiments. Thus, for the carpet, cushion Barrier I1 experiments a simple 

average of particleboard measurement series I1 and I11 is used to determine 

the CH 0 emission strength of the board. For the tile floor barrier III 

experiments, particleboard measurment series 111 data are used. It is presuNed 

that the CH 0 emission strength of the particleboard remained unchanged during 

the 1.5 months during which it was covered by the very effective 

vinyl floor permeation barrier. To model the CH 0 emissions of the uncovered 2 

particleboard during the carpet, cushion Barrier 1 experiments, the 

particleboard measurement series I and I1 data have been fit to a single 

exponential decay model (i.e., Equation 13). An average decay period, T, of 

10.4 k 0.4 months is determined from the CH 0 emission data taken at 2, 5 and 

15 L/min air flow rates. This decay period is consistent with some of the 

particleboard underlayment products measured in the fast decay study (see 

Tables 13 and 14). The CK 0 concentration data for uncovered particleboard 

during the middle of the carpet, cushion barrier I experiments (ie., 19.5 

weeks following particleboard measurevent series I) are then determined from 

the following expression: 

2 

2 

2 

2 

approximate 

2 

2 

-19.5/45 a[CH201~eries I *e [ CH20 Model 

where 45 weeks is the 10.4 month decay period, The results of the modeled 

@H 0 emissions data for uncovered underlayment during Barriers I, 11, and I11 

experiments are summarized in Table 17. 

2 

The general effectiveness of the test flooring materials as CH20 

permeation barriers can be evaluated by comparing the modeled CH20 

concentrations for uncovered underlayment from Table 17 with the measured CH 0 

concentrations for flooring-covered underlayment; listed in Table 16. The 

waffled sponge rubber cushion and nylon carpet barrier resulted in approximate 

twofold reductions in CH 0 concentrations in comparison to the uncovered 

2 

2 
Table 17. Modeled CAZO vapor concentration data (ppn) for uncovered 

particleboard during flooring-covered particleboard experiments 

Carpet, Cushion Barrier I Carpet, Cushion Barrier I1 

Air Flow (Modeled from PCB (Modeled from PCB Tile Floor Barrier 

Rate (Lfmin) Series I, II)a Series 11, IIIlb (FCB Series 111 data) 

2 0.276 0.229 r 0.010 0.238 f 0.005 

5 0.206 0.169 * 0.0U5 

10 0.129 0.111 f 0.012 0.122 * 0.005 

15 0.100 0.088 0.011 0.097 2 0.505 

0.163 f 0.008 

aThe modeled CHZO concentration for umovered particleboard during the midpoint of Carpet, Cushion Barrier I experiments from 

weeks 12 to 27 of the 31 week period between particleboard 

bThs m~deld CHzO concentration for mcovered underiayment 

age of Particleboard Series I1 and 111. 

Measurement Series 1 and I1 is calculated as 

-19.5145 

rCB201Series I * e 

during the Carpet, Cushion Barrier I1 experiments is the simple aver- 
Report XVIII 52 CPSC-IAG-84-1103 

particleboard. In contrast, the effectiveness of the urethane foam cushion 

and nylon carpet varied from near zero changes at 2 L/min flow rates to twofold reductions at 15 L/min flow rates. The vi.ny1 floor caused approximate 

30-fold reductions in CH 0 concentrations. 2 

Permeation Barriers Modellng 

A steady state model to predict the potential impact of decorative floor 

coverings on CH 0 emissions from particleboard underlayment has been 

previously published. The final expression for the steady state CI120 

concentration inside a single indoor compartment wLth uniform mixing and a 

single CH Q emission source covered by a permeation barrier of uniform CH20 

permeability (i.e., Equation ll*) is 

** 

2 

where: 

[CH20]* - 

the steady state CH 8 concentration inside the single 

compartment (mg/m ), 

2 3 

the CH 0 concentration outside the compartment, 2 

2 

-1 3 

the area of the emission source (m ) divided by the product 

of the pollutant exchange rate (h j and the volume (m ) of 

the compartment, and 

-ir T.G.Matthews, T. J. Reed, B. J. Tromberg, C. R. Daffron and A. R. 

Hawthorne, (1985) "Formaldehyde Emission from Combustion Sources and Solid 

Formaldehyde-Resin-Containing Products: Potential Impact on Indoor 

Formaldehyde Concentrations" Advances in Chemistry Series No. 210, 

Formaldehyde: Analytical Chemistry and Toxicology, 131-50. 
Report XVIII 53 CPSC-TAG-84-1103 

KThe quantities 

least squares 

the CH 0 transport coefficient for the permeation barrier 2 

(m/h) * 

m and b are the slope and intercept determined from a linear 

analysis of the CH20 emission rate of the uncovered CH 0 2 

emission source (€.e., particleboard underlayment) as a function of CH20 

concentration. 

The m and b values are determined from the modeled CH20 emissions of the 

underlayment during flooring-covered underlayment measurements (see Table 18). 

Assuming a zero [CH20J0 for the laboratory supply air to the 

environmental chamber, Equation 16 simplifies to 

A-b 

[l + (:/K) +)m - A] [CH201§S 

A comparison of the measured CH20 vapor concentrations from the carpetcovered underlayment experiments with [CH2OJSs values calculated using 

Equation 17 are summarized in Table 19. Good agreement is observed between 

the measured and modeled GH 0 concentrations for both the waffled sponge 

rubber, nylon carpet barrier and the vinyl tile floor barrier. These data are 

consistent with the permeation barriers modeling. In contrast, the modeling 

results for the urethane foam cushion, nylon carpet barrier generally 

overpredict the CH 0 permeation resistance of these decorative floaring 

materials, particularly at the lower air flow rates. The reason for the 

discrepancy between the experimental and modeled CH 0 concentrations for the 

urethane foam cushion, nylon carpet barrier is currently unknown. 

2 

2 

2 
a Table 18. Linear regression analyses of the modeled CH20 

concentration data for uncovered particleboard underlayment 

during flooring - covered particleboard experiments 

Carpet, Cushion Carpet, Cushion Tile Floor 

Barrier I Barrier I1 Barrier 

PCB Series I, 11) PCB Series 11, 111) PCB Series 111) 

(Modeled from (Modeled from (Modeled from 

Slope 0.94 

Intercept 0.47 

1.02 k 0.11 1.29 5 0.06 

0.40 k 0.02 0.48 k 0.01 

%ee Equation 16. 
Table 19. Comparison of measured and modeled CHzO vapor 

concentrations (ppn) from simulated flooring experiments 

Carpet, waffled 6ponpe Carpet, urethane 

Air flow Rubber Barrier I Fom Barrier I1 

rate (Llmin) A Measured Modeled Measured Modeled 

Tile floor 

Barrier 

Measured Modeled 

2 2.71 0.15 5 0.02 0.18 0.23 f 0.01 0.16 t 0.02 0.008 k 0.005 0.002 i 0.001 

5 1.08 0.09 f 0.01 0.10 0.15 f 0.01 0.03 f 0.02 - 

10 0.54 0.06 f 0.01 0.06 0.08 f 0.01 0.05 f 0.01 - 

15 0.36 0.04 i 0.01 0.04 0.04 f 0.01 0.04 P 0.01 - 

. 

I 

co 

F- 

+." 

+." 

0 

W 

I 
Report XVIII 56 CPSC-IAG-84-1103 

INTERLABORATORY TE_T COMPARISON OF THE FSEM 

The preliminary experimental results and analysis of the interlaboratory 

test comparison of the FSEM are given in this report. The test data consist 

of FSEM measurements of the particleboard and paneling samples taken initially 

at ORNL and then by participants in the interlaboratory test comparison. The 

final set of FSEM measurements, to be taken at ORNL after the return of all 

test samples from the participants, could not be performed due to time and 

resource restrictions. Two of the original ten participants that contributed 

experimental results to the interlaboratory comparison of the CH 0 analysis of 

CH 0-exposed molecular sieve samples did not contribute FSEM data. These 

groups used molecular sieve and filter paper that had been supplied by ORNL 

but had become contaminated in mailing. They were unable to repeat the FSEM 

tests with uncontaminated sieve and filter paper due to time and resource 

restrictions. The results of one additional participant were deleted because 

the reported CH OERs of the test products were all zero. This is the same 

participant that got twofold low results in the original measurements of the 

CH 0-exposed molecular sieve samples. The close results from the remaining 

nine participants in the first interlaboratory comparison (i.e.? coefficient 

of variation of 7%) indicate that this participant continued to have problems 

with the analysis of the molecular sieve. 

2 

2 

2 

2 

The average results of FSEM measurements taken initially at ORNP. and 

subsequently by participants in the interlaboratory comparison of the FSEM are 

listed in Table 20 for particleboard underlayment and Table 21 for hardwood 

plywood paneling (ice., domestic veneer) samples. The participant, product 

sample numbers in the tables do not represent the same institutions as the 

participant numbers that were given in Report XI11 for the first 

interlaboratory test comparison of the CH 0-exposed molecular sieve samples. 

The columns ORNL/0.301 and ORNL/O.163 in Tables 20 and 21, respectively, 

represent the relatjve CH 0 emission strength of the test samples as 

determined from the initial OWL FSEM measurements. The corrected participant 

data are simply normalized for the relative CH OER determined from the ORNL 

FSEM measurements. No corrections for product aging during the study can be 

applied since the final series of FSEM measurements at OWL could not be 

performed. The average results for the particleboard samples (i.e., Table 20) 

2 

2 

2 
Table 20. Interlaboratory test comparison results of 

the FSEM for particleboard underlapent samples 

Partici ants Corrected 

Partici ants 

bg/m s h) 

ORNL/O. 163 s Sample No. (mg/m2h) (mg/m h) 

Participant OWL Meas. 

Average 

cv 

0.392 f 0.039 

0.322 2 0.018 

0.261 2 0.084 

0.326 f 0.072 

0.215 f 0.034 

0.285 k 0.015 

0.308 50.020 

0.301 2 0.056 

19% 

~~ 

1.30 

1.07 

0.87 

1.08 

0.71 

0.95 

1.02 

'1.00 

0.212 f 0.025 

0.276 +_ 0.033 

0.192 f 0.036 

0,246 k 0.031 

0.174 k 0.062 

0.185 2 0.032 

0.222 f 0.042 

0.215 k 0.036 

17% 

0.163 

0.258 

0.221 

8.228 

0.245 

0.195 

0.218 

0.218 k 0 

14% 

031 
Table 21. Interlaboratory test comparison results of 

the FSEM for hardwood plywood paneling samples 

Corrected 

Partici ants Partici ants 

bg/m 4 h) ORNL/O. 163 (w/m 4 h) Participant OWL Meas. 

Sample No. (mg/m2h> 

1 0.171 2 0.036 1.05 0.088 2 0.020 0.084 

2 0.198 5 0.014 1.21 0.175 2 0.011* 0.145* 

3 0.183 f 0.013 1.12 0.096 2 0.026 0.086 

4 0.191 k 0.048 1.17 0.109 5 0.033 0.093 

5 0.126 5 0.015 0.77 0.074 2 0.018 0.096 

6 0.115 2 0.024 0.70 0.067 2 0.025 0.095 

7 0.158 k 0.028 0.97 0.103 2 0.030 0. I06 

Average 0.163 f 0.032 

cv 20% 

Q-tested hV 

CV 

0.102 0.036 0.101 k 0.021 

35% 21% 

0.090 ? 0.014 0.093 9 0.809 

16% 10% 

"Q-test positive at 2 96% confidence interval. 

H 
Report XVIII 59 CPSC-IAG-84-1103 

indicate coefficients of variation (CV) of 19% and 17% for ORNL and 

participant measurements of the test samples. This is within the range of 07s 

for interboard variation determined for particleboard materials from the 

pressed-wood product survey (see Table VII, Report XII). The CV for the 

corrected participants data (14%) is somewhat improved presumably because some 

of the interboard variation has been removed by the normalization procedure. 

The average results for paneling indicate CVs of 21%, 35% and 21% for the 

ORNL, participants and corrected participants data. If the results for 

participant 2 are Q-tested (ie., at,a 96% confidence level) the CVs for the 

participant and corrected partichpants data are 16% and lo%, respectively. The 

CVs for both the Q-tested and non-Q-tested participant data sets are within 

the range of CVs for combined intraboard and interboard variation determined 

for paneling products from the pressed-wood product survey (see Table VZII, 

Report XII). Analogous to the particleboard results, the CVs for the 

corrected participants paneling data are improved presumably because some of 

the interboard variation has been removed. The overall results for this 

preliminary interlaboratory comparison indicate that several independent 

laboratories could perform FSEM measurements with a precision of approximately 

a 10-20%CV. 

61 

APPENDIX I: 

Uncertainty Analysis of Models I and I1 

The mathematical development of the uncertainty analyses for both 

Models I and IT is presented for a general five term model of functionality f, 

independent variables x x2 ... x and model coefficients el, e2 ... e5. 5’ 

where : 

y - single observation, and 

e randomness in y, 

The functional form f, of the model is assumed to be true. 

x2 ... x values 5 The population mean value for y for a given set of x 

is 

There is no randomness in E(y) so no E term is included. 

For a given experimental data set (e.g., ALLPBU for Model I), the 

mathematical form of Equation A1 is 
62 

where: 

y = estimate of y for a single observation, and 

b' = estimate of 6' based on a given data set D. D 

E is unknown and not included mathematically in Model I or Model IT. y may 

be used to estimate future values of y as given in Equation A1 or values of 

E(y) as given in Equation A2. 

described in the following discussion. 

D 

The uncertainty in such predictions is 

Consider the uncertainty in E(y) as estimated by y. 

(i.e., error) between the two functions is 

The difference 

All uncertainty in E(y) is in dD1, OD2 ... eD5. 

(i.e., V) in E(y) for complex models, a second order Taylor Series Approxima- * 

tion is commonly used, 

To estimate the variance 

and 0 . 'Di Dj 

where COV is the Covariance between two model coefficients, 

* A. M. Mood, F. A. Graybill, D. C. Base, "Introduction to the Theory of 

Statistics," McGraw-Hill, NY, 1974, pp. 181. 
63 

The expanded form of Equation A5 is 

The estimate of the standard error of E(y) is the square root of V[E(y)]. 

Consider the uncertainty in y as predicted by y. The difference (i.e., 

error) between the two functions is 

Error = y - y 
64 

Uncertainty in y comes from two sources: 

cients d 

The variance of y Fs 

the uncertainty in the model coeffiand E, the randomness involved in future observations. D1' 'D2 "* 'D5 

where o2 is the variance of the randomness component E. 

the mean square error (mse) of y for the given pressed-wood product model 

(e.g., ALLPBU for Model I) under consideration. The estimated standard error 

(SE) of y is 

a2 is estimated by 
65 

ORNL/TM-9867 

INTERNAL DISTRIBUTION 

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4. A. R.Hawthorne 43. Document Reference Section 

5. S. V. Kaye 44-45. Laboratory Records 

6-36. T. G. Matthews 45. Laboratory Records, RC 

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66 

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