1 **U.S. ENVIRONMENTAL**  **PROTECTION AGENCY OFFICE OF**  **POLLUTION PREVENTION AND TOXICS**  **Response to External P**  **eer R**  **eview Comments** 

**on MEASURING FORMALDEHY** **DE EMISSIONS FROM LO W 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 generall y supported by

the work. EPA appreciates this comment.

The obj ectives 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 particu larl y 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 onl y 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 specificall y 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 hy potheses 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 advis able 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 NI OSH 3500 method states that there may be ne gative interference in the formaldehyde measurement if phenols are Parthasarath y et al. is now cited in the report and revisions have been made in Section 5.2 t o 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 chromotropi c acid method is the primary method cited in ASTM E1333 and ASTM D6007, and i t is extremely unlikely that there is any

interference2 **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 th e ULEF

- PF HWPW samples may be due to interference in the anal yt ical method. If the reason for the lower formaldeh yde concentrations is an artifact of the anal yt ical method , where experimental conditions result ed 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 form aldeh yd e in air in this study

. The reason is th at an 8

- to

- 1 excess of phenol relative to formaldeh yde in the sampled air is difficult to envision, given the low volatility of p h enol relative to formaldeh yde. 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 M ye rs (1985) citation in the background found that formaldeh yde “ 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 anal ys is but should be discussed in the report. See response to th e 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 day s 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 chamber s
. 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 e xposed in the chamber testing. This is now stated in Section 3.1.1 of the report. The requested tab le 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 ch amber 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 subtracte d 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 earl y 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 m y point of view, this technical report can only be regarded as an indication showing the impact of temperature and relative humidity on low emitting ply

wood boards and not as a scientific report showing important new aspects / assessment parameter s or a general ly valid calculation formula due to the several remarks mentioned in this rev iew. 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 bas is 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 cause d 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 thickn esses having more or few er layer s m ay cause different results and need to be verified ;
 H igh chamber blank values (in relation to very low emitting test materials) ; and

 Analy tical 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 pane ls 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 m y point of view, this technical report in the present form can onl y be regarded as an indication showing the impact of temperature and relative humidity on low emitting ply

wood 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 accur atel y and understandable

– w ith some small exception s as stated below. The technical report was written in a very

structured and unders tandable way

. The literature is adequatel y cited, but has to be extended. There are some important publication s missing. The reviewer did not indicate what publications she feels are missing. However, an additional study by Parthasarath y is now cited and discussed in the report , as noted above. In the present form, the ar ticle cannot be published and need s 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 anal yt ical procedure are described in detail, but rais e 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: NAF

acryl ic and ULEF

- PF panels were 9 millimeters thick, the ULEF

UF panels were **0.5 in ch**  thick

. ” Is this a mistake: 5

- layer pl ywood 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 s pecified i n 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 specificall y 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 b y an equation using the mass transfer coefficient or a second possibili ty is to run the small chamber with preconditioned samples as the large ASTM E 1333 chamber test (7 days). If the samples were onl y conditioned for 48 hours, are there some additional test results to verify the proper conditioning of the samples

– m eaning was the equilibrium reached? Are the K

- values calculated and/or are there additional test results to verify a steady state concentration? T ext has been added in Section 3.3.2 noting pre

- test weighing procedures that confirmed the adequacy of the co nditioning, and the consistency of our results with those of Parthasarathy et al.

Page 9

- 3.3.3 Chromotropic acid analy sis The calibration curve was extended to lower concentrations to “assure accurate determination of HCH O emissions from the panels”... (s ummary

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 data6 **COMMENT RESPONSE**  the “state of the art” analy tical test method for formaldehyde determination due to several problems

– see below. Another anal yt ical meth od 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 anal yt ical method: phenols as negative interference at an 8:1 excess over formaldeh yde, modifications in the analytical procedure shall be made when relativel y high phenol to formaldeh yd e concentration (8:1) are anticipated (L it.: Hakes, D., Johnson, G. and Marhevka, J., April 1984 and Technical Bulletin No. 415, 1983) .” quality summariz ed in Section 4 of the report. In addition, as discussed in a previous response, EPA does not believe that high phenol to formaldeh yde concentrations were present during the testing. The response below provides a dditional comments on the chromotropic acid method

.

Page 9

– Additionall y , the CARB ATCM Standard Operating Procedure (SOP) SAS 20 , “Sampling and Anal ys is of Formaldeh yd e Emissions from Composite Wood Products ,” June 2012, describes the DNPH method by anal ys is by

high performance liquid chromatography (HP LC) as analy tical proc edure wi th 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 NI OSH 3500 chromotropic acid method and were published in CWP

- 10

- 002. Therefore , CARB recommend s 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 m ethod, but calls for increased scrutiny of method performance when that method is used to determine emissio ns from low

- emitting products. EPA believes that this study implemented the increased scrutiny recommended in the CARB guidance, for example, by

exte nsion 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 highl y linear (as stated in Section 4.2 of the report), and that no non

- detects occurred in determining eith er product emissions or chamber background levels in this study . Furthermore, CARB does not recommend the MBTH or acetylacetone 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 full y meets the intent of CWP

-7 **COMMENT RESPONSE**  10

- 002. Page 10

- 4.1 Chamber Test C onditions The test conditi ons are described well, but back ground 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 formaldeh yde. EPA appre ciates 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 I SO, JI S , and EN standards request a calibration curve in a c ontinuously repeating period. For example, the European referen ce chamber test method for wood

- based materials EN 717

- 1, 2005

- 01: “Wood

- based panels

– Determination of formaldeh yd e 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 well

established procedures. While the reviewer may

p refer 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 Backgro und 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 exceed ed 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.
Fro m m y point of view , th e back ground level has to be much lower to determine the formaldehyde emission of very low emitting materials. Referring to the European test cha mber standard EN 717

- 1, the back ground 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 int erest in mi nimizing 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 regarde d as complex statistical work, but I assume that the results cannot be assessed accuratel y based on the basis of the obtained/available data

. It is unclear wh y the reviewer is assuming that the results cannot be assessed accurate ly

. 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

. EP A appreciates the comment s and has revised the table (now Table 4).

Page 14

- As shown in T able 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 anal yt ical method chromotropic acid, the test results hav e 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 presumabl y 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 whe n the value of 0.012 ppm was obtained was 0.009 ppm. Therefore, the relevant background level was not higher than the measured t est 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 analy tical method used (chromotropic acid) can probab ly

cause minor values and misinterpretation b ecause phenols are regarded as causing a negative interference at an 8:1 excess over formaldeh yd e. For verification , another anal yt ical test method (acetylacetone 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 th is 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 formaldeh yde. The chromotropic acid method is the primary

method cited in ASTM E1333 and D6007; therefore, EPA does not b elieve that another anal yt ical test me thod 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 ply wood with veneer core made with vari ous resins. The motivation for this study was described in Chapter s 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, logicall y 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 anal ys is, equivalency tests for large/small chamber comparison, experiments on the first batch of ULEF

- UF panels). The objectives o f the study were achieved and the conclusions are technicall y sound , supported by all the technical data and statistical interpretation. The study

i s technically

s ound and includes evidence for an y 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 ty pe 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 u sed adequate equipment to ensure operation within the parameters recommended by the standard methods;

 Tests are performed by an accredited TPC laboratory approved b y 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 b y 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 clearl y 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 anal ys is (fresh solutions, consistent over time in the preparation of calibration curves), etc
**. Results:** 
 The results are clearl y presented with adequate reporting of statistics and appropriate use of tables.

 Interpretations and expl anations are provi ded in detailed, mentioning also the unexpected results (large/small chamber comparison results at elevated T and RH conditions, ULEF

PF behavior at 70% RH).

 Tables and figure fa cilitate 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

onl y v eneer core HW PW 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 onl y on veneer core HWPW panels. These were chosen over other alternatives because one of the goals of the study was to compare th e 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 commerciall y available , so yes, the panels and the resins used to make them are representative of HWPW manufacturing. However, commerciall y available HWPW is made with other ty pes of resins, with different ty pes 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 (30 0 C temperature, respective 85% relative humidity)? The elevated test conditions were chosen to simulate conditions that might realisticall y occur in a residence during warm humid weather. In addition, these were the highest temperature/humidity

condition s 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 b y TPC on July 2012 can be used no matter the product ty pes?

- 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 e quivalency test documents the comparability

of large and small chamber test procedures and results , so ye s it ap plies to different product ty pes as long as their emissions are similar. EPA does not have access to the referenced equivalency

results, as thos e 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 /m 3 ) (on page 8) as is recommended for Industrial Hardwood Pl ywood 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 ty pe used panels from a single batch. Page 8 line 5

- It was considered less important the use of th e same thickness for all panels due to that only exposed surface areas were taken into consideration in the emission rate

. T he same unit measure for all thicknesses would have be better. In order to test multiple resin ty pes it was necessary

to obtain panels from different manufacturers, and the panels available in 5

- pl y 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 bef ore sampling for formaldeh yde. 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 E13 33 and D6007 methods (0.03 ppm respec tive 0.02 ppm); this note should be added in sec tion 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 Ihave already mentioned before, for The reviewer is correct that the TPC’s12 **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 ty

pes), 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 bo th 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

.