1

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF POLLUTION PREVENTION AND TOXICS

Response to External Peer Review Comments

on

MEASURING FORMALDEHYDE EMISSIONS FROM LOW EMITTING HARDWOOD 

PLYWOOD PANELS UNDER DIFFERENT CONDITIONS OF TEMPERATURE 

AND RELATIVE HUMIDITY

COMMENT RESPONSE

Randy Maddalena, Ph.D.

Overall, the project was well conceived and work appears to be 

careful and complete producing high quality data. The report is 

very well written and the conclusions are reasonable and generally 

supported by the work. 

EPA appreciates this comment.

The objectives and methods of the study were clearly articulated 

and the experimental design was appropriate to address the stated 

objectives. The quality of the work is excellent, including 

sufficient quality assurance measures and data interpretation. I 

particularly like the detail given to measuring and reporting the 

variability in the small chamber test method results and the careful 

comparison between the small and large chamber methods.

EPA appreciates this comment.

I have two issues with the experimental design described below. 

First, the study used only two temperature levels. Using only two 

temperature levels limits the ability to characterize the linearity of 

the emission/temperature profile. This limitation is not expected to 

weaken the results of the study because the work was focused 

specifically on the issue of increasing temperature and humidity

above the standard conditions and only tested a relatively small 

temperature range (25 C - 30 C). Given how the hypotheses 

were formulated and the limited temperature range being tested, 

the assumption of linearity in the emission/temperature profile is 

probably valid. However, the authors should clarify that previous 

studies found that the relationship was not linear and discuss how 

those findings might impact their conclusions. For example, both 

Myers (1985, cited in the report) and Parthasarathy et al. (2011 

citation provided at end of the review) found an exponential 

relationship between formaldehyde emissions and temperature, so 

it is probably not advisable to extrapolate the relationship found in 

this study beyond the range tested.

The second issue may be more significant. This reviewer is not 

familiar with the chromotropic acid method used in the study but 

NIOSH 3500 method states that there may be negative 

interference in the formaldehyde measurement if phenols are 

Parthasarathy et al. is now cited in the 

report and revisions have been made in 

Section 5.2 to indicate that the data 

obtained here do not allow distinction 

of an exponential temperature 

dependence, and that the temperature 

relationship found here should not be 

extrapolated beyond the range of 

temperature used in testing.

The chromotropic acid method is the 

primary method cited in ASTM E1333 

and ASTM D6007, and it is extremely

unlikely that there is any interference 
2

COMMENT RESPONSE

present at levels greater than 8:1 relative to formaldehyde. This 

interference may have already been resolved in the method used 

by the third party certifier. However, the report stated that the PF 

product tested in Riedlinger et al. (2012) seemed to show an 

increase in emission with T/RH (page 4, paragraph 1 in the 

report), which is inconsistent with the findings of the current 

report. The authors need to discuss why their results differ from 

Riedlinger et al (2012) and discuss the possibility that the lower 

apparent emissions from the ULEF-PF HWPW samples may be 

due to interference in the analytical method. If the reason for the 

lower formaldehyde concentrations is an artifact of the analytical 

method, where experimental conditions resulted in higher 

concentration of phenols in the test chamber, then the comparisons 

with ULEF-PF may not be valid. 

due to phenol in the use of the 

chromotropic acid method for 

determining formaldehyde in air in this 

study. The reason is that an 8-to-1 

excess of phenol relative to

formaldehyde in the sampled air is 

difficult to envision, given the low 

volatility of phenol relative to 

formaldehyde. To our knowledge,

significant phenol emissions have not

been reported from PF wood products. 

Nevertheless, discussion has been 

added in Section 6.2.1 of the report 

noting that the present results for the PF 

HWPW product differ from those of 

Riedlinger for the PF particleboard, and 

suggesting possible explanations.

Page 1 - The Executive Summary is very well written and 

complete. 

EPA appreciates the comment.

Page 4 line 2 - The Myers (1985) citation in the background found 

that formaldehyde “emissions increased exponentially” with 

increasing temperature. This point should be reconciled with the 

authors’ assumption of a linear relationship between emission and 

temperature later in the report. Again, I don’t expect this to change 

the results of the statistical analysis but should be discussed in the 

report.

See response to the first comment 

above.

Page 6 line 1 - I agree with the authors’ use of an extended 

conditioning time at the higher T/RH conditions. Others have 

found that for some composite wood materials, it may take from 

one to ten days for the material to come to equilibrium with the 

humidity (Parthasarathy et al. 2011). It is unclear what effect the 

continued uptake of moisture into the material will have on 

emission rates but future work may want to confirm that moisture 

uptake into composite wood does not increase formaldehyde 

emissions. 

EPA appreciates the comment and 

agrees.

Page 6 line 2 – The exposed surface area of the HWPW is reported 

here but it is not clear whether the edges/backs are covered. When 

I tried to estimate the area and other test conditions from the 

information provided in the report (page 6, paragraph 2 and page 

8, section 3.3.1 and 3.3.2) I was not able to reconcile the factors in 

the small and large chambers. I suggest providing a table with the 

following factors listed for both the large and small chambers: 

Loading (L, m2/m3); Air change rate (ACH, 1/h); Chamber 

volume (V, m3); Ventilation rate (Q, m3/h); Area of emitting 

surface including edges (A, m2).

The edges of all HWPW pieces were 

covered with aluminum tape; both faces 

(front and back) were exposed in the 

chamber testing. This is now stated in 

Section 3.1.1 of the report.

The requested table has now been 

added as a new Section 3.3.3 of the 

report.
3

COMMENT RESPONSE

One of the most important factors that influence results from 

different size chambers when the emissions are reported at 

concentration (ppm) is the Q/A (m/h). I was not able to confirm 

that Q/A was the same for both chambers. I was also not able to 

confirm the emitting sample area for the small and large chambers.

The table added in Section 3.3.3 shows 

that the Q/A values in the large and 

small chambers were the same. 

Page 11 line 2 - Paragraph 2 and Section 4.3 report the method 

blanks (~0.006) and chamber blanks (range from 0.009 to more 

than 0.03, average 0.017 ppm after excluding outlier). Were the 

blanks/background concentrations subtracted from the 

measurements when the data were processed? 

No, the indicated background readings 

were not subtracted from the 

measurements. This is now indicated in 

Section 4.3 of the report. ASTM E1333 

and D6007 specify that background be 

measured and reported but not 

subtracted from the sample 

measurements

Page 11 line 4 - Was a formal statistical test used to identify and 

exclude the two outliers that “exceeded 0.03 ppm”?

No formal statistical test was done; 

those two values occurred early in the 

project and were identified on the basis 

of being 50% or more higher than the 

next highest value and much higher 

than the background values determined 

subsequently in the project. 
4

COMMENT RESPONSE

Bettina Meyer

From my point of view, this technical report can only be regarded 

as an indication showing the impact of temperature and relative 

humidity on low emitting plywood boards and not as a scientific 

report showing important new aspects / assessment parameters or 

a generally valid calculation formula due to the several remarks 

mentioned in this review.

EPA appreciates this comment and 

agrees.

The technical report is well written and the topic is very important. 

A detailed description and interpretation of test results was given 

on basis of the obtained test results. 

But due to the following items below, the experimental approach 

and the results and their interpretation/statistical evaluation need a 

major revision.

 Special production process of test material caused by the 

multi-layer structure. Note: only 5-layer glued boards with a

thickness of 9 mm (and 0.5 inch – mistake?) have been 

tested, other thicknesses having more or fewer layers may

cause different results and need to be verified;

 High chamber blank values (in relation to very low emitting 

test materials); and 

 Analytical procedure used (chromotropic acid method)

EPA agrees that testing of other types 

of ULEF products would be valuable, 

including those with different 

thicknesses. However, the intent of this 

study was to test common ULEF 

products, and the HWPW panels tested 

meet that criterion. Resources and time 

limited the number of panels that could 

be tested.

Responses regarding the chamber blank 

values and chromotropic acid method 

are provided with specific comments 

below.

From my point of view, this technical report in the present form 

can only be regarded as an indication showing the impact of 

temperature and relative humidity on low emitting plywood 

boards. 

EPA agrees and appreciates the 

comment.

The statistical evaluation of the results is complex, but cannot be 

assessed on the basis of the available data with respect to these test 

results due to reasons mentioned above. Details are discussed in 

following pages of this review.

This comment is unclear, but it appears 

no response is necessary.

The background, experimental work, and statistical evaluation of 

test results are described accurately and understandable – with 

some small exceptions as stated below. The technical report was 

written in a very structured and understandable way. The literature 

is adequately cited, but has to be extended. There are some 

important publications missing. 

The reviewer did not indicate what 

publications she feels are missing. 

However, an additional study by

Parthasarathy is now cited and

discussed in the report, as noted above.

In the present form, the article cannot be published and needs a 

major revision.

EPA has made revisions to the report 

based on peer review comments.

Pages 1-2 - The summary gives a good overview of the topic and 

the main results of this work.

EPA appreciates the comment.

Pages 3-4 - Excellent description of the current situation,

beginning in 2007 with the CARB regulation and some first test 

EPA appreciates the comment.
5

COMMENT RESPONSE

results concerning the variation of temperature and relative 

humidity as the base to continue studies on this topic.

Chapter 3 - This chapter gives a good overview of the 

experimental design of the investigation. The samples, test 

methods, and analytical procedure are described in detail, but raise 

some questions: 

EPA appreciates the comment. 

Responses to the questions are below.

Page 8 - 3.2 Test material

“All three test materials were 5-ply veneer core HWPW: NAFacrylic and ULEF-PF panels were 9 millimeters thick, the ULEFUF panels were 0.5 inch thick.” Is this a mistake: 5-layer plywood 

with thickness of 0.5 inch?

The report is correct as written; the UF 

panels were of a different thickness 

than the PF or NAF panels. 

Page 8 – 3.3.2 Small chamber tests

“A conditioning of 48 hours was used to ensure that test materials 

were equilibrated to the elevated T and RH conditions used in 

testing.” “The HWPW specimens remained in the small chambers 

until steady state HCHO concentration was reached, i.e., 

approximately 2.5 hours after the start of the small chamber test.”

Does it mean that the test samples were conditioned only for 48 

hours and testing was done for 2.5 hours? A clarification should be 

given in the description.

The 48 hour conditioning period 

exceeds the conditioning time of 2 

hours specified in ASTM D6007. As 

stated in Sections 3.1.1 and 3.3.2 of the 

report, the extended 48 hour 

conditioning was implemented in this 

study specifically to ensure adequate 

sample conditioning. Section 3.3.2 has 

been revised to emphasize this point. 

Sampling to determine formaldehyde 

emission in the small chamber tests 

began 2.5 hours after the test items

were placed into the chamber. This 

schedule was based on extensive past 

testing of the small chamber procedure 

in the TPC laboratory. Section 3.3.2 has

been revised to clarify this point.

Page 8 – Referring to ASTM D 6007, the test has to be carried out 

until a steady state concentration is reached and the time has to be 

calculated by an equation using the mass transfer coefficient or a 

second possibility is to run the small chamber with preconditioned 

samples as the large ASTM E 1333 chamber test (7 days). 

If the samples were only conditioned for 48 hours, are there some 

additional test results to verify the proper conditioning of the 

samples – meaning was the equilibrium reached? Are the K-values 

calculated and/or are there additional test results to verify a steady

state concentration?

Text has been added in Section 3.3.2 

noting pre-test weighing procedures 

that confirmed the adequacy of the 

conditioning, and the consistency of 

our results with those of Parthasarathy 

et al.

Page 9 - 3.3.3 Chromotropic acid analysis 

The calibration curve was extended to lower concentrations to 

“assure accurate determination of HCHO emissions from the 

panels”... (summary in Section 4 of the report). From my point of 

view, the chromotropic acid method can no longer be regarded as 

ASTM D6007 cites the chromotropic 

acid procedure as the primary method, 

and EPA believes the method was 

appropriate for the purposes of this 

study, as demonstrated by the data 
6

COMMENT RESPONSE

the “state of the art” analytical test method for formaldehyde 

determination due to several problems – see below. Another 

analytical method has to be used to determined formaldehyde 

emission – especially for these low ranges/levels.

As stated in:

- ASTM E 1333 standard, “Detailed procedures based on acetyl

acetone, pararosanilin, DNPH and MBTH have been found to give 

results equivalent or greater in accuracy and precision than 

chromotropic acid” and

- ASTM D 6007 standard, “NIOSH 3500 analytical method: 

phenols as negative interference at an 8:1 excess over 

formaldehyde, modifications in the analytical procedure shall be 

made when relatively high phenol to formaldehyde concentration 

(8:1) are anticipated (Lit.: Hakes, D., Johnson, G. and Marhevka, 

J., April 1984 and Technical Bulletin No. 415, 1983).”

quality summarized in Section 4 of the 

report. In addition, as discussed in a 

previous response, EPA does not 

believe that high phenol to 

formaldehyde concentrations were 

present during the testing. The response 

below provides additional comments on 

the chromotropic acid method. 

Page 9 – Additionally, the CARB ATCM Standard Operating 

Procedure (SOP) SAS 20, “Sampling and Analysis of 

Formaldehyde Emissions from Composite Wood Products,” June 

2012, describes the DNPH method by analysis by high 

performance liquid chromatography (HPLC) as analytical 

procedure with detection limits of 0.6 ppb and estimated 

quantification limit (EQL) of 3 ppb.

In 2010, difficulties in high detection limit have already been 

noticed by CARB in reference to small-scale test methods in 

combination with NIOSH 3500 chromotropic acid method and 

were published in CWP-10-002. Therefore, CARB recommends

using MBTH or the acetyl acetone method for small-scale test 

methods. 

The CARB CWP-10-002 guidance 

does not require the use of another test 

method in place of the chromotropic 

acid method, but calls for increased 

scrutiny of method performance when 

that method is used to determine 

emissions from low-emitting products. 

EPA believes that this study

implemented the increased scrutiny

recommended in the CARB guidance, 

for example, by extension of the 

calibration curve to lower 

concentrations (as stated in Section 

3.3.3 of the report). We note that the 

resulting calibration curve was highly 

linear (as stated in Section 4.2 of the 

report), and that no non-detects 

occurred in determining either product 

emissions or chamber background 

levels in this study. Furthermore, 

CARB does not recommend the MBTH 

or acetyl acetone methods in CWP-10-

002, but only suggests them as potential 

alternative methods that may be 

adopted if repeated non-detects occur 

with the chromotropic acid method. 

Text in Section 3.3.4 of the report has 

been revised to emphasize that use of 

the chromotropic acid method in this 

study fully meets the intent of CWP-
7

COMMENT RESPONSE

10-002.

Page 10 - 4.1 Chamber Test Conditions

The test conditions are described well, but background test results 

in the conditioning chamber are an important parameter in 

addition. Investigations of very low emitting materials stored in an 

area of high emitting materials can showed an impact on absorbing 

formaldehyde. 

EPA appreciates the comment and 

agrees. Background formaldehyde 

concentrations were measured 

throughout the study and met the 

specified conditions of ASTM E1333 

and D6007.

Page 10 - 4.2 Chromotropic Acid Calibration

Only a single calibration curve has been established at the 

beginning of this study in August 2012 and the slope was 

compared to the calibration curves done between March and July

2012 in this laboratory. It was indicated based on the slope, that 

the laboratory spectrophotometer and the preparation of 

calibration standards were consistent over time. 

As mentioned in this chapter, this is a standard practice for the 

TPC, but from my point of view it is not sufficient. 

The ISO, JIS, and EN standards request a calibration curve in a 

continuously repeating period. For example, the European 

reference chamber test method for wood-based materials EN 717-

1, 2005-01: “Wood-based panels – Determination of formaldehyde 

release, Part 1: Formaldehyde emission by the chamber method” 

requires in chapter 9.4.1 “The calibration curve shall be checked at 

least once a week.” 

European labs being accredited have to act this way and WKI uses 

the same procedure for ASTM chamber test evaluation, as well as 

for European test methods.

The intent of this study was to conduct 

emission testing under several

temperature and humidity conditions 

with consistent test procedures

following ASTM E1333 and D6007. 

That was accomplished through a 

designated TPC using the TPC’s wellestablished procedures. While the 

reviewer may prefer alternate 

approaches, it would have been 

problematic to require changes to the

TPC’s established procedures. EPA 

believes that the procedures were 

sufficient as there was no evidence of 

any issues with calibration.

Page 11 – 4.3 Chamber HCHO Background

The large chamber background was detected with 0.010 ppm, 

small chamber backgrounds were given with an average value of 

0.020 (+ 0.009) ppm for 22 measurements, excluding two tests 

which exceeded 0.03 ppm, the averaged background level was 

given with 0.017 (+ 0.005) ppm, with a maximum of 

0.026 ppm and a minimum of 0.009 ppm.

Indeed, the background levels determined during this investigation 

correspond to those requested by ASTM standards. 

From my point of view, the background level has to be much 

lower to determine the formaldehyde emission of very low 

emitting materials. Referring to the European test chamber 

standard EN 717-1, the background level has to be lower than 

0.005 ppm before starting the test.

The chamber background values in this 

study are reported in much more detail 

than in many other studies, and as 

noted by the peer reviewers, meet

levels specified in the ASTM methods.

Consequently, while we share the 

reviewer’s interest in minimizing 

background, we do not believe that the 

main findings of this study are affected 

by the background observed. The 

European requirement is commendable 

but not applicable to the testing in this 

study, which was following ASTM 

methods. 
8

COMMENT RESPONSE

Page 12 and Appendix - It can be regarded as complex statistical 

work, but I assume that the results cannot be assessed accurately 

based on the basis of the obtained/available data.

It is unclear why the reviewer is 

assuming that the results cannot be 

assessed accurately.

Page 14 – 6.2 Small Chamber Emission Tests 

In Table 2, the test results were mentioned in order of testing (ref. 

Table 1) but this causes a difficult overview of test results in 

respect to the impact of T and RH. 

My proposal is to sort the test results corresponding to the test 

material first. The second criteria can be the temperature and third 

criteria the relative humidity.

We note that the reviewer’s comments 

refer to Table 2; however, it appears 

that her comments instead apply to 

Table 3. EPA appreciates the comments

and has revised the table (now Table 4).

Page 14 - As shown in Table 2, the lowest test result has been 

detected with 0.012 ppm for NAF-acrylic boards (average of 0.015 

ppm). Most of the test results are within the range of 0.02 up to 

0.05 ppm, and only the results for ULEF-UF boards exceed this 

range after increasing the temperature and/or relative humidity. 

Due to high background level (blank value) of chambers and the 

analytical method chromotropic acid, the test results have to be 

regarded critical. Measuring an average blank value of the test 

chamber of app. 0.02 ppm (see technical report, page 11), a test 

result of 0.012 ppm has to be verified because the blank value was 

lower than those measured for the test sample.

The reviewer presumably means that 

the average blank value was higher than 

the result from this individual small 

chamber test. We understand the 

reviewer’s concern; however, it is more 

appropriate to compare background 

readings measured closest to the time 

the test measurements were taken, 

rather than the average value. The 

chamber background measured on the 

day prior to the testing when the value 

of 0.012 ppm was obtained was 0.009 

ppm. Therefore, the relevant 

background level was not higher than 

the measured test sample values.

Page 15 – “A more complex relationship with respect to T and RH 

is observed for the ULEF-PF panel type. For this panel Type 

HCHO emissions are similar for both T levels at 50% RH and at 

85%RH, but they differ considerably at 70%RH. It is not clear 

what is causing this type of relationship.”

As stated above, the analytical method used (chromotropic acid) 

can probably cause minor values and misinterpretation because 

phenols are regarded as causing a negative interference at an 8:1 

excess over formaldehyde. For verification, another analytical test 

method (acetyl acetone or DNPH) had to be used. An 

inhomogeneity of test material may also be considered. 

As stated in responses above, phenol 

interference in the chromotropic acid 

method in this study is very unlikely, as 

there is no evidence of phenol being 

emitted into air from finished PF 

products at an 8-to-1 excess over 

formaldehyde. The chromotropic acid 

method is the primary method cited in 

ASTM E1333 and D6007; therefore, 

EPA does not believe that another 

analytical test method should have been 

used. Regarding inhomogeneity of test 

material, despite efforts to minimize 

inhomogeneity, EPA agrees that it may 

have contributed to the observed 

results. 

Octavia Zeleniuc, Ph.D.

Overall it is a comprehensive report, developed on 8 chapters 

(references included) well defined, presenting relevant data related 

EPA appreciates the comments.
9

COMMENT RESPONSE

to the effect of elevated T and RH conditions on formaldehyde 

emissions from hardwood plywood with veneer core made with 

various resins. 

The motivation for this study was described in Chapters 1 and 2, 

where a few references are mentioned highlighting the influence of 

temperature and relative humidity on formaldehyde emissions 

from wood composite panels. 

It is a clear presentation, logically organized, including sufficient 

data presented in appropriate tables and graph, which sustain the 

results, interpretation, and conclusions. 

In general, explanations are included that clarify the presentation 

and avoid confusion in interpretation of results (e.g., establishing 

the test matrix, presentation in details of statistical methodology

used in data analysis, equivalency tests for large/small chamber 

comparison, experiments on the first batch of ULEF-UF panels). 

The objectives of the study were achieved and the conclusions are 

technically sound, supported by all the technical data and 

statistical interpretation.

The study is technically sound and includes evidence for any 

statements or conclusions that it makes.

The report contains accurate information on procedures, facilities, 

quality assurance and control, and results:

Procedure and facilities:

 Tests are performed according to standard methods 

recommended for this type of product, ASTM D-6007-02-

small chamber and ASTM E-1333-96 (2002)- large chamber, 

with a few exceptions mentioned and justified in the report 

(e.g., lower concentrations for calibration curve, greater 

conditioning period for the small chamber). The study used 

adequate equipment to ensure operation within the 

parameters recommended by the standard methods; 

 Tests are performed by an accredited TPC laboratory 

approved by CARB;

 Tests were well conducted based on an equilibrated test 

design.

The products used were veneer core HWPW panels labeled as 

NAF and ULEF panels, selected by EPA as representative for 

ULEF composite wood products category.

EPA appreciates the comments.

Quality Assurance/Quality Control: EPA appreciates the comments.
10

COMMENT RESPONSE

There were clearly specified measures taken to ensure the results 

accuracy by the following: monitoring the equipment (measuring 

the chambers’ parameters), control in the process (accurate records 

of all measurements), precision and clarity on sampling and 

analysis (fresh solutions, consistent over time in the preparation of 

calibration curves), etc.

Results: 

 The results are clearly presented with adequate reporting of 

statistics and appropriate use of tables. 

 Interpretations and explanations are provided in detailed,

mentioning also the unexpected results (large/small chamber 

comparison results at elevated T and RH conditions, ULEFPF behavior at 70% RH). 

 Tables and figure facilitate comparisons, better understanding 

of results and drawing conclusions.

 The results are in reasonable agreement with the findings in 

literature.

EPA appreciates the comments.

Page 5 line 1 - Why only veneer core HWPW panels? What about 

the other category of HWPW –with composite core? 

- Are the tested resins ULEF-UF, PF and NAF-acrylic 

representatives for the HWPW manufacturing?

Due to limited time and resources, EPA 

chose to conduct the study only on 

veneer core HWPW panels. These were 

chosen over other alternatives because 

one of the goals of the study was to 

compare the results obtained in this 

study to the results of the Frihart study 

(EPA was unaware of the Riedlinger 

when the EPA study was initiated). The 

panels used in the study are 

commercially available, so yes, the 

panels and the resins used to make 

them are representative of HWPW 

manufacturing. However, commercially 

available HWPW is made with other 

types of resins, with different types of 

wood and different thicknesses; 

therefore, the test specimens are not 

representative of all HWPW.

Page 5 lines 3 and 4 - How were the elevated test conditions 

chosen (300C temperature, respective 85% relative humidity)?

The elevated test conditions were 

chosen to simulate conditions that 

might realistically occur in a residence 

during warm humid weather. In 

addition, these were the highest 

temperature/humidity conditions that 

the TPC lab could reliably use and 

maintain for the testing.
11

COMMENT RESPONSE

Page 5 line 10 - Why didn’t E1333 constitute the basic standard 

for tests instead ASTM D6007?

ASTM E1333 is time-consuming, and 

most TPC labs only have one large 

chamber; therefore, due to time and 

resource constraints, it wasn’t feasible 

to use E1333 as the standard test for 

this study. Instead, ASTM D6007 was 

used after demonstrating its 

equivalence to ASTM E1333. 

Page 5 line 8 - This equivalency test made by TPC on July 2012 

can be used no matter the product types? 

- Would be interesting to have these results of equivalency shown 

in a table as an annex or after Table 2 in Chapter 6, for 

comparison.

The equivalency test documents the 

comparability of large and small 

chamber test procedures and results, so 

yes it applies to different product types 

as long as their emissions are similar. 

EPA does not have access to the 

referenced equivalency results, as those 

were done for CARB; however, a 

separate equivalency test under

standard conditions as well as elevated 

temperature and humidity was 

conducted for this study, and those 

results are presented in the study report

in Section 6.1, Table 3.

Page 6 line 12 - The sample dimensions (for test in the large 

chamber) are not given; it is mentioned only the product loading 

ratio of 0.43 (m2/m3) (on page 8) as is recommended for Industrial 

Hardwood Plywood Panels; 

- The sample for the large chamber was from the same batch as the 

boards tested in the small chamber?

As noted in a response above, a new 

table has been added in Section 3.3.3 of 

the report that specifies all test loadings 

and parameters.

Yes, all testing of each HWPW product

type used panels from a single batch.

Page 8 line 5 - It was considered less important the use of the same 

thickness for all panels due to that only exposed surface areas 

were taken into consideration in the emission rate. The same unit 

measure for all thicknesses would have be better.

In order to test multiple resin types it 

was necessary to obtain panels from 

different manufacturers, and the panels 

available in 5-ply veneer core HWPW 

were as stated. EPA agrees that it could

have been better to use panels with 

identical thicknesses, but this was not 

possible.

Page 8 - How long was the sample in the large chamber tested?

The standard mentions 16-20 hours!

All samples were in the large chamber 

for at least 16.5 hours before sampling 

for formaldehyde. This is now specified 

in Section 3.3.1 of the report. 

Page 11 line 1 - It should be noted that these low background 

levels are below the values indicated in the ASTM E1333 and 

D6007 methods (0.03 ppm respective 0.02 ppm); this note should 

be added in section 3.1.1 page 6 line 3.

Revision has been made in Section 4.3 

to indicate that the background levels 

meet the method requirements.

Page 13 lines 9 and 16 - As I have already mentioned before, for The reviewer is correct that the TPC’s 
12

COMMENT RESPONSE

comparison, it would be better to add the results for equivalency

obtained by TPC in July 2012 for standard conditions.

- Requirements for that equivalency are referred only for standard 

conditions. The equivalency large/small chamber for higher 

conditions cannot be applied.

2012 equivalency designation resulted 

from testing at standard conditions, and 

equivalency at other conditions is not 

implied. Therefore, this study included 

additional equivalency testing at 

elevated temperature/humidity

conditions.

Page 15 line 4 - To clarify this issue with ULEF-PF panel, the test 

at high RH should be repeated.

EPA agrees that repeating some of the 

testing might be useful but does not 

believe that it is necessary in order to 

draw conclusions from the data 

collected.

Page 15 line 3 - To have a clear evidence of comparison made (for 

each pair of resin types), it should be added if possible, a table 

with these results.

The intent of the reviewer’s comment is 

not entirely clear, as the test results are 

already shown in the report in both 

tabular and graphical form. However, 

the revision of Table 3 (which is now 

Table 4), as described in a previous 

comment, provides a clearer 

comparison of results.