## FORMALDEHYDE FROM COMPOSITE WOOD PRODUCTS:

EXPOSURE ASSESSMENT

Final Report

Exposure Assessment Branch
Economics, Exposure and Technology Division

Office of Pollution Prevention and Toxics
Office of Chemical Safety and Pollution Prevention U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, N. W.
Washington , D.C. 20460



### July 2012i 

### ACKNOWLEDGMENT

EPA acknowledges the analytical and draft preparation support of Versar, Inc. of Springfield, Virginia in th e preparation of this report, provided under Contract No. EP

- W

- 10

- 005.



### Notice

This is not an official guidance document and should not be relied upon to determine appli cable regulatory requirements. This document was prepared to provide e xposure information for the rulemaking process, and to meet various administrative and legislat ive requirements. Due to the nature of the information available to EPA, the document contains various assumptions that may not reflect the regulatory determinations that an

individual firm or organization would make were it to apply the rule's requirements to its specific circumstances. Persons seeking information on specific regulatory requirements

should consult 40 CFR P art 7 70

, and the pre amble for the regulatory action

.

Mention of the names of specific companies, organizations, or entities does not constitute

an endors ement by EPA.ii 

### TABLE OF CON T ENTS

Section 1 EXECUTIVE SUMMARY

................................ ................................ ......................... 1

1.1 BAC KGROUND

................................ ................................ ................................ .............. 1

1.2 APPROACH

................................ ................................ ................................ .................... 2

1.3 RESULTS

................................ ................................ ................................ ......................... 5

1.4 IMPLICATIONS

................................ ................................ ................................ .............. 8

Section 2 INTRODUCTION

................................ ................................ ................................ ..... 10

2.1 BACKGROUND

................................ ................................ ................................ ............ 10

2.1.1 Formaldehyde U ses and Emissions

................................ ................................ ........ 10

2.1.2 Examples of Elevated Formaldehyde Levels in Residences

................................ .. 10

2.2 OBJECTIVES AND SCOPE

................................ ................................ ......................... 11

2.2.1 Rationale for the OPPT Exposure Assessment

................................ ...................... 11

2.2.2 Scope of the Assessment

................................ ................................ ........................ 13

2.3 THIS REPORT

................................ ................................ ................................ ............... 14

Section 3 FORMALDEHYDE CONCENTRATIONS OUTDOORS AND INDOORS

...... 15

3.1 FORMALDEHYDE IN OUTDOOR AIR

................................ ................................ ..... 15

3.2 FORMALDEHYDE IN INDOOR AIR

................................ ................................ ......... 16

3.2.1 Indoor Sources of Formaldehyde

................................ ................................ ........... 16

3.2.2 Recent Studies of Formaldehyde Concentrations Indoors

................................ ..... 16

3.3 FORMALDEHYDE BACKGROUND CONCENTRATION

................................ ...... 18

Secti on 4 MODELING APPROACH

................................ ................................ ....................... 19

4.1 MODEL USED FOR THE ASSESSMENT

................................ ................................ .. 20

4.2 FACTORS AFFECTING FORMALDEHYDE EXPOSURE INDOORS

.................... 21

4.3 SENSITIVITY ANALYSIS

................................ ................................ ........................... 22

4.4 MODEL INPUTS

................................ ................................ ................................ ........... 25

4.4.1 Background Con centration

................................ ................................ ..................... 25

4.4.2 Housing Types and House Volumes

................................ ................................ ...... 25

4.4.3 Airflow Rates

................................ ................................ ................................ ......... 26

4.4.4 Emissions Half Life

................................ ................................ ................................ 27

4.4.5 Indoor Temperature and Humidity

................................ ................................ ......... 27

4.4.6 PWP Loadings

– New

- home Case

................................ ................................ ......... 31

4.4.7 PWP Loadings

– Renovation Case

................................ ................................ ......... 36

4.4.8 CWP Emission Rates

................................ ................................ .............................. 39

4.4. 9 Exposure Groups and Activity Patterns

................................ ................................ . 54

4.4.1 0 Concentrations at Locations Outside the Home

................................ ..................... 55

4.5 MODEL RUN MATR IX

................................ ................................ ............................... 57

Section 5 MODELING RESULTS

................................ ................................ ........................... 59

5.1 NEW

- HOME CASE

................................ ................................ ................................ ...... 59

5.2 RENOVATION CASE

................................ ................................ ................................ .. 70

Section 6 DISCUSSION

................................ ................................ ................................ ............. 81iii 6.1 APPROACH AND RESULTS

................................ ................................ ...................... 81

6.1.1 Summary of Approach

................................ ................................ ........................... 81

6.1.2 Summary of Modeled Initial Formaldehyde Concentrations in Homes

................. 81

6.1.3 Summary of Modeled ADCs for Exposure Groups

................................ ............... 84

6.2 DATA GAPS AND INFORMATION NEEDS

................................ ............................. 87

6.2.1 Emissions Data

................................ ................................ ................................ ....... 87

6.2.2 Near

- field Exposures

................................ ................................ .............................. 87

Section 7 REFERENCES

................................ ................................ ................................ .......... 88

Appendix A

– Floor Plans by Structure Type

Appendix B

– PWP Lo ading Spreadsheets

Appendix C

– Section 3.2 of F IAM

- p wp Model Documentation Reportiv 

### LIST OF TABLES

Table Page

1

- 1. Alternative Analytical Options Used for the Exposure Assessment

................................ ...... 4

3

- 1. Ambient Air Formaldehyde Level s (μg/m 3 ) by Land Use Category

................................ .... 1 4

3

- 2. Emission Rates of Selected Indoor Sources of Formaldehyde

................................ ............. 1 5

3

- 3. Summary of Recent Formaldehyde Field Monitoring Studies

................................ ............. 1 6

4

- 1. Input Values for Sensitivity Analysis

– Base Condition for Conventional Home

............... 2 3

4

- 2. Model Results for Base Conditi on for the Conventional Home

................................ ........... 2 3

4

- 3. Input Values for Sensitivity Analysis

– Base Condition for Manufactured Home

............... 2 5

4

- 4. Model Results for Base Condition for the Manufactured Home

................................ .......... 2 5

4

- 5. House Dimensions and Calculated Volume for Five Housing Types

................................ .. 2 7

4

- 6

. Summer and Winter Indoor Temperatures from RECS 2005, by Climate Zone

.................. 30

4

- 7. Year

- round Indoor Temperatures Derived from RECS 2005, by Climate Zone

.................. 30

4

- 8. Modeled Year

- round Indoor RH Level, by Climate Zone

................................ .................... 3 2

4

- 9. PWP Loading/Mix for SF Detache d Homes (volume = 811 m 3 )

– New Home

................... 3 3

4

- 10. PWP Loading/Mix for SF Attached Homes (volume = 523 m 3 )

– New Home

................... 3 3

4

- 11. PWP Loading/Mix for Apartments (volume = 261 m 3 )

– New Home

................................ . 3 4

4

- 12. PWP Loading/Mix for Manufactured Homes (volume = 360 m 3 )

– New Ho me

................. 3 5

4

- 13. PWP Loading/Mix for Camper Trailers (volume = 61 m 3 )

– New Home

........................... 3 6

4

- 14. PWP Loading/Mix for SF Detached Homes (volume = 811 m 3 )

- Renovation

................... 3 7

4

- 15. PWP Loading/Mix for SF Attached Homes (volume = 523 m 3 )

- Renovation

.................... 3 7

4

- 16. PWP Loading/Mix for Apartments (volume = 261 m 3 )

- Renovation

................................ . 3 7

4

- 17. PWP Loading/Mix for Manufactured Homes (volume = 360 m 3 )

-- Renovation

................ 3 8

4

- 18. PWP Loading/Mix for Camper Trailers (volume = 61 m 3 )

– Renovation

........................... 3 8

4

- 19. Baseline Emission Levels (2013) For Domestica lly Produced CWPs, by Product Type and Emissions Certification Standard

................................ ....................... 3 9

4

- 20. Formaldehyde Emissions Standards in the CARB Air Toxic Control Measure for Formaldehyde Emissions from Compressed Wood Products (ppm)

................................ .... 40

4

- 21. Baseline Emission Levels f or N on

- Canadian Imported Composite Wood Products, by Product Type and Emissions Standard

................................ ................................ ............ 4 1

4

- 22. Baseline Emission Levels for Composite Wood Products by Product Type, Country of Origin, and Emissions Standard

................................ ................................ ............................ 4 3

4

- 23. Alternative Analytical Options Evaluated in the Exposure Assessment

.............................. 4 4

4

- 24. Emission Levels for CARB1 Regulatory Option by CWP Type, Origin,

and Emissions Standard

................................ ................................ ................................ ........ 4 5

4

- 25. Emission Levels for CARB2 Analytical Option by CWP Type, Origin, and Emissions

Standard

................................ ................................ ................................ ................................ 4 7

4

- 26. Emission Levels for NAF Scenario by CWP Type, Origin, and Emissions Standard

......... 4 8

4

- 27. Emission Levels for CARB2 Scenario with Laminates at NAF by CWP Type, Origin, and Emissions Standard

................................ ................................ ............................ 4 9

4

- 28. Calculated Intercepts for Various Emissi on Levels for Each CWP Type

............................ 5 1

4

- 29. Composite Intercepts by CWP Type

– Baseline Scenario

................................ ................... 5 2

4

- 30. Composite Intercepts by CWP Type and Emissions Scenario

................................ ............. 5 3v 4

- 31. Emission Rates for Underlayment and Coated CWPs

– Baseline Scenario

......................... 5 3

4

- 32. Annual Hours at Home and Non

- home Locations, by Exposure Group

.............................. 5 6

4

- 33. Concentration Values for Non

- home Locations

– Baseline Scenario

................................ .. 5 6

4

- 34. Derivation of Baseline Values for Daycare, School and Work Locations

........................... 5 7

4

- 35. Concentration Values for Selected Non

- home Locat ions, by Emissions Scenario

.............. 5 8

4

- 36. Model Run Matrix

................................ ................................ ................................ ................ 5 9

5

- 1. Modeled Initial Residential Concentrations for Eight Emissions Scenarios, ppb

– New

- home Case

................................ ................................ ................................ .......... 6 1

5

- 2. Modeled Residential ADCs (House Age 0

- 1 Years) for Eight Emissions Sc enarios, ppb

– New

- home Case

................................ ................................ ................................ .......... 6 3

5

- 3. Modeled Residential ADCs by House Age for Manufactured Home in Climate Zone 3, by Emission Scenario, ppb

– New

- home Case

................................ ................................ ..... 6 4

5

- 4. Modeled ADCs ( House Age 0

- 1 Years ) for Infants for Eight Emissions Scenarios

, ppb

– New

- home Case

................................ ................................ ................................ .......... 6 5

5

- 5. Modeled ADCs ( House Age 0

- 1 Years ) for Preschool/School Children for Eight

Emissions Scenarios, ppb

– New

- home Case

................................ ................................ ....... 6 6

5

- 6. Modeled ADCs ( House Age 0

- 1 Years ) for Non

- industry Workers for Eight

Emissions Scenarios, ppb

– New

- home Case

................................ ................................ ....... 6 7

5

- 7. Modeled ADCs ( House Age 0

- 1 Years ) for Fabrication

- industry Workers for Eight

Emissions Scenarios, ppb

– New

- home Case

................................ ................................ ....... 6 8

5

- 8. Modeled ADCs ( House Age 0

- 1 Years ) for Retirees for Eight Emissions Scenarios,

pp b

– New

- home Case

................................ ................................ ................................ ....... 6 9

5

- 9. Modeled ADCs ( House Age 0

- 1 Years ) for Part

- time Workers for Eight Emissions

Scen arios, ppb

– New

- home Case

................................ ................................ ........................ 70

5

- 10. Modeled Initial Residential Concentrations for Eight Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ................................ ......... 7 2

5

- 11. Modeled Residential ADCs (House Age 0

- 1 Years) for Eight Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ................................ ......... 7 4

5

- 12. Modeled Residential ADCs by House Age for Manufactured Home in Climate Zone 3, by Emission Scenario, ppb

– Renovation C ase

................................ ................................ ..... 7 5

5

- 13. Modeled ADCs ( House Age 0

- 1 Years ) for Infants for Eight Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ................................ ......... 7 6

5

- 14. Modeled ADCs ( House Age 0

- 1 Years ) for Preschool/School Children for Eight

Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ...... 7 7

5

- 1 5. Modeled ADCs ( House Age 0

- 1 Years ) for Non

- industry Workers for Eight

Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ...... 7 8

5

- 16. Modeled ADCs ( House Age 0

- 1 Years ) for Fabrication

- industry Workers for Eight

Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ...... 7 9

5

- 17. Modeled ADCs ( House Age 0

- 1 Years ) for Retirees for Eight Emissions Scenarios, ppb

– Renovation Case

................................ ................................ ................................ ......... 80

5

- 18. Modeled ADCs ( House Age 0

- 1 Years ) for Part

- time Workers for Ei ght Emissions

Scenarios, ppb

– Renovation Case

................................ ................................ ........................ 8 1

6

- 1. Percent Reduc tion in Initial F ormaldehyde Concentration, Relative to Baseline, by Alternate Emissions Scenario and Housing Type for New

- home and Renovation Cases

.... 8 5

6

- 2. Average Modeled ADC ( House Age 0

- 1 Years ) by Exposure Group and Emissions

Scenario for New

- home an d Renovation Cases , ppb

................................ ........................... 8 6vi 

### LIST OF FIGURES

Figure Page

1

- 1. Modeled Initial F ormaldehyde Concentrations by Housing Type

– New

- home Case

........... 6

1

- 2. Modeled Initial F ormaldehyde Concentrations by Housing Type

– Renovation Case

.......... 6

1

- 3. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups

– New

- home Case

................ 7

1

- 4. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups

– Renovation Case

............... 8

1

- 5. Percent Reduction in Modeled Initial F ormaldehyde Concentration by Alternate

Emissions Scenario

– New

- home and Renova tion Cases

................................ ....................... 9

1

- 6. Percent Reduction in Modeled ADCs for Exposure Groups by Alternate Emissions

Scenario

– New

- home Case

................................ ................................ ................................ .... 9

4

- 1. Modeling Construct

................................ ................................ ................................ .............. 1 8

4

- 2

. Factors Affecting Indoor Formaldehyde Concentrations and Human Exposures

................ 2 2

4

- 3

. Relative Model Sen sitivity for the Conventional Home

................................ ....................... 2 4

4

- 4

. Relative Model Sensitivity for the Manufactured Home

................................ ...................... 2 5

4

- 5

. U.S. Climate Zones

................................ ................................ ................................ ............... 2 9

5

- 1. Modeled Initial F ormaldehyde Concentrations by Emissions Scenario /Analytical Option and Housing Type

– New

- home Case

................................ ................................ .................. 60

5

- 2. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups by Emissions

Scenario /Analytical Option and Housing Type

– New

- home Case

................................ ...... 6 2

5

- 3. Modeled Initial F ormaldehyde Concentrations by Emissions Scenario /Analytical Option and Housing Type

– Renovation Case

................................ ................................ .................. 7 1

5

- 4. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups by Emissions

Scenario /Analytical Option and Housing Type

– Renovation Case

................................ ..... 7 3

6

- 1. Modeled Initial F ormaldehyde Concentration by Emissions Scenario /Analytical Option

for New

- home and R enovation Cases

................................ ................................ ................... 8 3

6

- 2. Reduction in Modeled Initial F ormaldehyde Concentration, Relative to Baseline, by Alternate Emissions Scenario for New

- home and Renovation Cases

............................. 8 3

6

- 3. Percent Reduction in Modeled Initial F ormaldehyde Concentration, Relative to Baseline, by Alternate Emissions Scenario for New

- home and Renovation Cases

............................. 8 4

6

- 4. Percent Reduction in Modeled ADCs for Exposure Groups, Relative to Baseline, by Alternate Emissions Scenario for New

- h ome Case

................................ ......................... 8 7

6

- 5. Percent Reduction in Modeled ADCs for Exposure Groups, Relative to Baseline, by Alternate Emissions Scenario for Renovation Case

................................ ........................ 8 71 

### Section 1

EXECUTIVE SUMMARY

1.1 BACKGROUND

Formaldehyde is used widely by industry t o manufacture certain types of building materials and household products. It also is a by

- product of combustion and certain other natural processes.

Indoor sources of formaldehyde include building materials such as composite wood products
(CWPs 1 ) and insul ation , furnishings such as carpeting and furniture / flooring materials made with composite wood, tobacco smoke, household products such as cosmetics and paint s, and unvented

fuel

- burning appliances such as gas stoves or kerosene heaters.

In residences, the most significant sources of formaldehyde are likely to be CWPs made with adhesives containing urea

- formaldehyde (UF) resins ( http://www.epa.gov/iaq/formalde.html ). CWPs made for indoor use include: part icleboard (PB, used as sub

- flooring and shelving and in countertops, cabinetry and furniture); hardwood plywood (HWPW

, used for decorative wall covering and in cabinets/furniture); and medium

- density fiberboard (MDF, used for drawer

fronts, cabinets, and f urniture tops). MDF contains a higher resin

- to

- wood ratio than any other

UF

- based C WP and is generally recognized as being the highest formaldehyde emitter among

C WPs

.

Formaldehyde received national attention as recently as 2006, when the U.S. Federal Eme rgency Management Agency (FEMA) provided travel trailers and mobile homes for habitation by residents of the U.S. gulf coast who were displaced by Hurricane Katrina and Hurricane Rita

. Some individuals who moved into these temporary homes complained of bre athing difficulties, nosebleeds, and persistent headaches. In December 2007 and January 2008, the Centers for Disease
Control and Prevention measured formaldehyde levels averaging 77 parts per billion (ppb; geometric mean) in a random sample of FEMA

- suppli ed occupied travel trailers, park models, and mobile

homes. In February 2008 U.S. health officials announced that potentially hazardous formaldehyde levels were found in both travel trailers and mobile homes provided by FEMA

.

In April 2008 the California Air Resources Board (C ARB ) formally adopte d an Airborne Toxic

Control Measure (ATCM) t o reduce formaldehyde emissions from CWPs sold, offered for sale, supplied, used, or manufactured for sale in California. The ATCM was intended to reduce the public’s exp osure to formaldehyde by reducing emissions from HWPW, PB and MDF panels. At about the same time, the USEPA was petitioned under section 21 of TSCA by 25 organizations and approximately 5,000 individuals to adopt under TSCA Section 6(a) the CARB ATCM as a

national standard. EPA found that the available information was not sufficient to support regulating formaldehyde emissions from composite wood products under TSCA S ection 6(a). In response to the petition, EPA announced in the Federal Register on June 27, 2008 (73 FR
36504) 2 that EPA would initiate a proceeding to investigate whether and what type of regulatory or other action might be appropriate to protect against risks that may be posed by formaldehyde

1 In this report, the term “composite wood product” (CWP) refers only to hardwood pl ywood, medium density
fiberboard or particleboard whereas “pressed wood product” (PWP) refers to a broader set of wood materials including, for example, softwood plywood and oriented strand board.

2 Available at http://www.gpo.gov/fdsys/pkg/FR

- 2008

- 06

- 27/pdf/E8

- 14618.pdf2 emitted from composite wood products. In December 2 008, EPA published an Advance Notice of Proposed Rulemaking (ANPR) to publicly initiate the investigation and obtain stakeholder input (73 FR 73620). 3 On July 7, 2010, the Formaldehyde Standards for Composite Wood Products Act (FSCWPA) was signed into law. This statute , which adds a Title VI to TSCA, establishes formaldehyde emission standards for hardwood plywood, particleboard, and medium

density fiberboard that are identical to the CARB ATCM Phase II standards. 4 TSCA Title VI directs EPA to promulgate i mplementing regulations by January 1, 2013 that address: sell

through dates for products; stockpiling; third

- party testing and certification; auditing and reporting of third

- party certifiers; recordkeeping; chain of custody; labeling; enforcement; products made with no

- added formaldehyde (NAF) and ultra

- low emitting formaldehyde (ULEF) resins; laminated products; finished goods; hardboard; and products containing de minimis amounts of composite wood products.

In support of the implementing regulations, a s with other rulemaking s that are determined to be “significant regulatory action[s]” under Executive Order 12866

— Regulatory Planning and

Review , EPA is required to conduct an economic analysis of the costs and benefits associated with the rulemaking. In s upport of this economic analysis, EPA assessed formaldehyde exposures indoors in recently constructed or renovated residential structures. That assessment is the subject of this report.

1.2 APPROACH

A modeling

- based approach was chosen for the exposure a ssessment because of the number of situations of potential interest and the limited amount of current or recent monitoring data

available. Both new

- construction, or new

- home, and renovation cases were examined. As a general rule, expected or average values were used for model inputs, as opposed to a range or distribution of values. Variability was introduced for certain input parameters expected to have a significant influence on the modeling results. Seven alternative emissions scenarios ( analytical option s) were modeled along with a baseline (year 2013) scenario. Model runs were made for five different housing types, in five different climates zones, for each emissions scenario. Six exposure groups were included in the assessment, which estimated not only at

- home but also

away

- from

- home formaldehyde exposure in the form of an average daily concentration (ADC) reflecting “around the clock” exposure.

The model used for the assessment

– Formaldehyde Indoor Air Model

- Pressed Wood Products

, Version 2.0 ( FIAM

- pwp v2.0 )

– is an adaptation of one initially developed d uring the 1980s by Dr. Thomas Matthews and colleagues at the Oak Ridge National Laboratory . In brief, t he “Matthews model” was designed to estimate the steady

- state formaldehyde concentration indoors

due to emission sources such as PWPs

. PWP e mission r ates are dependent on the formaldehyde

concentration in the vapor phase, in accordance with Fick’s Law describing the bulk

- vapor interphase at the surface of a pressed wood emission source . The initial, “steady

- state” indoor concentration estimated by the model is assumed to decrease over time as the reservoir of formaldehyde in various sources is gradually depleted ; t he gradual decrease is assumed to follow

a first

- order exponential process.

3 Available at http://www.gpo.gov/fdsys/pkg/FR

- 2008

- 12

- 03/pdf/E8

- 28585.pdf

4 Available at http://www.arb.ca.gov/toxics/compwood/compwood.htm3 Inputs to the FIAM

- pwp model include the formaldehyde background concentration (intended to

reflect the contribution of formaldehyde outdoor s as well as indoor sources other than PWPs), the number of zones (1 or 2), zone volumes and airflows, indoor temperature and humidity, the

types and amounts of PWPs installed in the structure and the ir emission rates, and exposure factors such as time spent in/out of the residence for exposure groups including children, workers

and retirees. The results include modeled indoor fo rmaldehyde concentrat ions, both initial steady

- state values and those at later points in time, together with exposure estimates such as the daily average concentra tion (ADC) to which an individual is exposed

.

F loor plans for representative structures were used as a guide in developing PWP loading rates for five housing types

– single

- family attached and detached homes, apartments, manufactured homes, and camper trailers. The loading rates differed for the new

- home versus renovation cases.

For the renovatio n case, it was assumed that an entire kitchen was renovated, including cabinets, countertop and ancillary areas such as a pantry. It was further assumed that the vinyl covering the kitchen floor and adjacent hallway floor was replaced with engineered wood.

Because m any CWP manufacturers are in the midst of modifying their production technology and raw materials to achieve compliance with Phase 2 of the CARB ATCM, using current

emission levels to estimate emission levels in 2013 would not accurately reflect the 2013

baseline. Instead, baseline emission levels we re estimated using responses to a survey question

about emission levels that mills planned to achiev e within the next three years. These emission levels were weighted by production levels that mills r eported in the survey, in order to estimate

average emission levels by certification standard. The survey data also were used to estimate the share of total production volume represented by products meeting each emissions standard.

Among imported product s, baseline emission levels were estimated separately for products from Canada versus those from the rest of the world. The known composite wood manufacturers in Canada were compared to the CARB list of certified mills, and most Canadian mills were found

t o be CARB

- certified. As a result, Canadian mills were assumed to achieve the same baseline

emissions as U.S. mills. The baseline emission levels for non

- Canadian imported CWPs were estimated using data from a 2009 presentation by Professional Service Indus tries (PSI ) , a CARB Third Party Certifier ( TPC ). Although PSI is located in the U.S., the mills that it certifies are located in countries that are major sources of pressed wood products imported into the U .S

.

For the purposes of TSCA Title VI, laminated products are a subset of hardwood plywood. The

statute defines a laminated product as one made by affixing a wood veneer to a particleboard,

medium

- density fiberboard, or veneer

- core platform. The statutory definition goes on to state that laminated produ cts are component parts used in the construction or assembly of a finished good, and that a laminated product is produced by the manufacturer or fabricator of the finished good in which the product is incorporated. EPA is given the authority to modify the statutory definition of laminated product through rulemaking , and also is directed to use all available and

relevant information to determine whether the definition of HWPW should exempt engineered veneer or any laminated product. The Hardwood Plywood and Veneer Association has indicate d that laminated products represent about 30% of engineered wood floori ng production

. Therefore, this exposure analysis assumes that laminated products represent 30% of the volume of HWPW.

Seven alternative emissions scenari os or analytical options were used for the assessment, as listed and described briefly in Table 1

- 1 . The first four scenarios

– CARB1, CARB2/Statutory4 Option, CARB2/Statutory Option including laminated products at NAF, and NAF

– assume that progressively h igher percentages of CWPs meet stricter emission standards. The last three scenarios are similar to CARB1, CARB2/Statutory Option, and NAF, with the single exception that laminated products are not regulated as HWPW under TSCA. The methods and associated

a ssumptions for estimating emission levels for the various scenarios are fairly involved and do not lend themselves to a convenient summary; instead, the reader is referred to the detailed descriptions that can be found in Section 4.4.8 of this report.

Tab le 1

- 1 . Alternative Analytical Options Used for the Exposure Assessment

Analytical Option Description

CARB1, Including Laminate d

Products All CWPs, including laminated products a , are at emission levels that

meet CARB Phase 1 standards1. Products that meet CARB Phase 1

standards at baseline are assumed to remain at that emission level.

CARB2 /Statutory Option

, Including Laminate d

Products b All CWPs, including laminated products, are at emission levels that

meet CARB Phase 2 standards. Products that meet CAR B Phase 2

standards at baseline are assumed to remain at that emission level.

CARB2 /Statutory Option

, with Laminate d Products Meeting NAF

- based Resin Statutory Emission Standards As above, except that laminated products are assumed to meet NAF c

statutory emission standards.

NAF, Including Laminate d

Products All CWPs, including laminated products, are at emission levels that

meet NAF standards. Products that meet NAF standards at baseline

are assumed to remain at that emission level.

CARB1, Excluding

Lami nate d Products Like CARB1 above, except that laminated products are not regulated
as HWPW and, thus, are assumed remain at baseline emission levels.

CARB2 /Statutory Option

, Excluding Laminate d

Products Like CARB2 above, except that laminated products are not regulated
as HWPW and, thus, are assumed remain at baseline emission levels.

NAF, Excluding Laminate d

Products Like NAF above, except that laminated products are not regulated
and, thus, are assumed remain at baseline emission levels.

a 30 % of all HW PW products are assumed to be laminated products

.

b Th e CARB emission standards for this scenario are equivalent to th ose specified in the FSCWPA.

c NAF = no added formaldehyde.

This document discusses various optio ns with respect to formaldehyde and comp osite wood products, includi ng emissions standards that are different from those set in TSCA Ti tle VI. This

document discusses alternative emissions standards sim ply for informational purposes. The

breadth of the discussion here sh ould not necessarily impl y that EPA has corresponding flexibility in implementing the statute.

The modeling also accou n ted for PWP types (e.g., structural plywood, structural composite lumber, oriented strand board, and glued laminated lumber) that would not be subject to emissio n stand ards because they are specifically exempt under TSCA Title VI

. During the 1980s and up through the mid

- 1990s, emission rates for various types of PWPs were derived from sets of

chamber emission tests that were conducted at multiple air exchange rate s and/or product loading ratios. These multiple tests enabled estimation of model parameters

– slope and intercept

– that5 reflect the dependence of the emission rate on the indoor formaldehyde concentration. The s lope

is a mass transfer coefficient that re flects the “backpressure” effect of the indoor formaldehyde

concentration on the emission rate ; t he intercept reflects the hypothetical emission rate when the

indoor formaldehyde concentration is zero.

Because multiple tests as described above are rarely c onducted at present, it was not possible to directly estimate the slope and intercept for CWPs complying with var ious emission standards. American Society for Testing and Materials ( ASTM , now known as ASTM International)

Standard E 1333

- 10

, Standard Test Me thod for Determining Formaldehyde Concentrations in Air and Emission Rates from Wood Products Using a Large Chamber (ASTM 2010), is commonly

used to demonstrate compliance with formaldehyde emission standards. The method prescribes both an air exchange rat e and product loading ratios for the chamber tests. By u sing these rates together with an assumed slope (based on earlier testing) for each CWP type, it was possible to determine the corresponding intercept for a hypothetical source that meets a given emis sions

standard

.

To cover the various exposure situations that can depend on factors such as age and work status, the following exposure groups were defined:

• Infant (age 0 to <2)

• Pre

- school/school

- age children (age 2 to <16)

• Worker (age 16 to <64)

• Retiree (age 64 or greater)

The choice of age breaks to distinguish infants and pre

- school/school children from adults was
driven by the possible age dependency of cancer slope factors. The worker group was further divided among non

- industry workers, fabrication

- industry workers, and part

- time workers. In terms of activity patterns, the retiree group also can be used to represent individuals of age 16 to <64 who are unemployed or working at home.

Locations outside the home where individuals spend time were consid ered in the assessment to provide a total or “around

- the

- clock” exposure perspective. Concentrations assigned to these locations for the baseline emissions scenario were derived from several sources. For example,

both in

- vehicle and outdoor concentrations were based on average values reported from EPA’s air monitoring network. Values assigned to workplaces were taken from a recent EPA report developed by OPPT’s Chemical Engineering Branch, wherein concentrations were estimated using a similar modeling appro ach to that described in this report. Values assigned to schools and daycare facilities were based largely on measurement results from field monitoring studies.

1.3 RESULTS

Figure 1

- 1 conveys the modeled initial steady

- state concentrations for the new

- ho m e case.
Results are shown for the baseline scenario and seven alternate analytical options , for each of the five housing types used in the assessment (results are averaged across climates zones for each type). The highest modeled concentrations are for ca mper trailers. The lowest concentrations

occur for the case where CWPs are at emission levels that meet no

- added

- formaldehyde (NAF)

standards , whether or not laminate d product s are assumed to be regulated. Figure 1

- 2 shows a very similar pattern for the re novation case, but with lower concentrations as compared to the

new

- home case.6 Figure 1

- 1. Modeled Initial Formaldehyde Concentrations by Housing Type

– New

- home Case.

Figure 1

- 2. Modeled Initial Formaldehyde Concentrations by Housing Type

– Renovation Case. * Results shown are

for Zone 1 of these

two

- zone structures

* Results shown are

for Zone 1 of these

two

- zone structures7 Figure 1

- 3 conveys the overall ADCs for the new

- home case, reflecting combined in

- home and

away

- from

- home exposure, for each exposure group (results for each group are averaged across housing types and c limate zones). The ADCs that are shown are for the first year following new construction (i.e., house age of 0

- 1 years). Differences across the exposure groups generally are no more than 20 percent, with the notable exception of workers in the fabrication industry who have a substantially higher overall exposure due to their elevated at

- work exposure. Figure 1

- 4 shows a similar pattern for the renovation case, but at lower exposure levels than for the case of

new construction.

Figure 1

- 3

. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups

– New

- home Case

.8 Figure 1

- 4. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups

– Renovation Case.

1.4 IMPLICATIONS

Figure 1

- 5 indicates the percent concentration reduction f or each alternate analytical option

, relative to baseline, for both the new

- home and the renovation cases (results are averaged across housing types and climate zones). In either case, the reduction clearly is the greatest for the NAF scenarios. Figure 1

- 6 indicates the percent ADC reduction per exposure group for the alternate

emissions scenarios for the new

- home case, again showing the greatest reductions for the NAF scenarios (the pattern i s very similar for renovation).9 Figure 1

- 5

. Pe rcent Reduction in Modeled Initial F ormaldehyde Concentration by

Emissions Scenario

– New

- home and Renovation Cases.

Figure 1

- 6

. Percent Reduction in Modeled ADCs for Exposure Groups by Alternate

Emissions Scenario

– New

- home Case.10 

### Sect ion 2

INTRODUCTION 5

2.1 BACKGROUND

2.1.1 Formaldehyde Uses and Emissions

Formaldehyde is used widely by industry to manufacture certain types of building materials and household products. It also is a by

- product of combustion and certain other natural processes. Thus, it may be present in substantial concentrations both indoors and outdoors. Indoor sources of formaldehyde include building materials such as composite wood products (CWPs 6 ) and

insulation , furnishings such as carpeting and furniture / floor ing materials made with composite wood, tobacco smoke, household products such as cosmetics, paint s coatings and paper goods

, and unvented fuel

- burning appliances such as gas stoves or kerosene heaters. Formaldehyde, by

itself or in combination with other chemicals, serves a number of purposes in manufactured products. For example, it is used to add permanent

- press qualities to clothing and draperies, as a component of glues and adhesives, and as a preservative in some paints and coating products.

In resid ences, the most significant sources of formaldehyde are likely to be CWPs made with adhesives containing urea

- formaldehyde (UF) resins ( http://www.epa.gov/iaq/formalde.html ).

CWPs made for indoor use inc lude: particleboard (PB, used as sub

- flooring and shelving and in countertops, cabinetry and furniture); hardwood plywood (HWPW

, used for decorative wall covering and in cabinets/furniture); and medium

- density fiberboard (MDF, used for drawer

fronts, cabin ets, and furniture tops). MDF contains a higher resin

- to

- wood ratio than any other

UF

- based C WP and is generally recognized as being the highest formaldehyde emitter among
C WPs ( http://www.epa.gov/iaq/for malde.html ). Products such as softwood plywood and oriented

strand board (OSB) are produced primarily for exterior construction use and contain the dark or

red/black

- colored phenol

- formaldehyde (PF) resin. Although formaldehyde is present in both types of resins, pressed woods that contain PF resin generally emit formaldehyde at considerably lower rates than those containing UF resin.

The rate at which products like pressed wood or textiles release formaldehyde can change over

time. F ormaldehyde emissions generally decrease as products age. High indoor temperature or humidity can cause increased formaldehyde release from these products, particularly when they

are new.

2.1. 2 Examples of Elevated Formaldehyde Levels in Residences

During the 1970s many home owners had urea

- formaldehyde foam insulation (UFFI) installed in the wall cavities of their homes as an energy conservation measure. Many of these homes were

5 Portions of this section were extracted or adapted from the following web sites or citations:
http://www.epa.gov/iaq/formalde.html
http://www.pbmdf.com
T. Salthammer, S. Mentese, and R. Marutzky. 2010 Formaldehyde in the Indoor Environment, Chem. Rev.

, 110 :
2536

– 2572 ; available at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855181/

6 In this report, the term “composite wood product” (CWP) refers only to hardwood plywood, medium density fiberboard, or particleboard whereas “pressed wood product” (PWP) refers to a broader set of wood materials
including, for example, softwood plywood and oriented strand board.11 found to have relatively high indoor formaldehyde concentrations soon after UFFI installation.

The use of UFFI insulation in residences has steadily declined to the point that recent installations, if any, are extremely rare. Because formaldehyde emissions from UFFI decline with time, homes in which UFFI was installed many years ago are unlikely to hav e high levels of formaldehyde now.

Elevated formaldehyde levels have been noted in prefabricated and mobile homes, largely because of the relatively high loading of higher

- emitting C WPs used in their construction. Since 1985, the Department of Housing and Urban Development (HUD) has permitted only the use of PB and HWPW products that conform to specified formaldehyde emission limits in the

construction of manufactured homes. The Composite Panel Association ( CPA ) Formaldehyde Grademark Program 7 has been deve loped to provide independent certification of formaldehyde emission levels from wood panel products. The Program includes requirements for initial qualification for product certification, plant quality control procedures

, and periodic inspections

to reason ably assure that certified unfinished composite panel products meet the emission limits specified in applicable standards. Although the Program originally was developed in response to HUD’s certification requirements, it can be used to certify conformance of different types of panel products to different governmental or voluntary industry standards

.

In 2005 the U.S. Federal Emergency Management Agency (FEMA) provided travel trailers and mobile homes for habitation by residents of the U.S. gulf coast who wer e displaced by Hurricane

Katrina and Hurricane Rita . Some individuals who moved into these temporary homes complained of breathing difficulties, nosebleeds, and persistent headaches. In December 2007 and
January 2008, the Centers for Disease Control and Pr evention (CDC) measured formaldehyde levels in a random sample of 519 FEMA

- supplied occupied travel trailers, park models, and mobile homes (CDC 2008/2010; DHS 20009). In many of the homes tested, formaldehyde levels were higher than
typical U.S. indoor le vels. The geometric mean level of formaldehyde in the sampled structures was
77 parts per billion (ppb), with a range from 3 to 590 ppb. Formaldehyde levels varied by trailer type,
but all types tested had some levels at or above 100 ppb. In February 2008 U.S. health officials

announced 8 that potentially hazardous formaldehyde levels were found in both travel trailers and mobile homes provided by the agency.

2.2 OBJECTIVES AND SCOPE

2. 2 .1 Rationale for the OPPT Exposure Assessment

In April 200 8 CARB forma lly adopte d an Airborne Toxic Control Measure 9 (ATCM) t o reduce formaldehyde emissions from composite wood products sold, offered for sale, supplied, used, or

manufactured for sale in California. The ATCM was intended to reduce the public’s exposure to

for maldehyde by reducing emissions from HWPW, PB and MDF.

On March 24, 2008, EPA was petitioned under section 21 of TSCA by 25 organizations and approximately 5,000 individuals to adopt under TSCA Section 6(a) the CARB ATCM as a

national standard. EPA found that the available information was not sufficient to support regulating formaldehyde emissions from composite wood products under TSCA S ection 6(a).

7 See http://www.pbmdf.com/Certification

--- Forma ldehyde

- Grademark

- Program

8 See http://www.msnbc.msn.com/id/23168160/ns/us_news

- life/t/cdc

- tests

- confirm

- fema

- trailers

- are

- toxic/

9 See http://www.arb.ca.gov/toxics/compwood/compwood.htm for recent activity related to this ATCM.12 In response to the petition, EPA announced in the Federal Register on June 27, 2008 (73 FR
36504) 10 that EP A would initiate a proceeding to investigate whether and what type of regulatory or other action might be appropriate to protect against risks that may be posed by formaldehyde

emitted from composite wood products. In December 2008, EPA published an Advanc e Notice of Proposed Rulemaking (ANPR) to publicly initiate the investigation and obtain stakeholder input (73 FR 73620). 11 On July 7, 2010, the Formaldehyde Standards for Composite Wood Products Act (FSCWPA) was signed into law. This statute , which adds a Title VI to TSCA, establishes formaldehyde emission standards for hardwood plywood, particleboard, and medium

density fiberboard that are identical to the CARB ATCM Phase II standards

. 12 TSCA Title VI directs EPA to promulgate implementing regulations by Ja nuary 1, 2013 that address: sell

through dates for products; stockpiling; third

- party testing and certification; auditing and reporting of third

- party certifiers; recordkeeping; chain of custody; labeling; enforcement; products made with no

- added formaldeh yde (NAF) and ultra

- low emitting formaldehyde (ULEF) resins; laminated products; finished goods; hardboard; and products containing de minimis amounts of composite wood products.

In support of the implementing regulations, as with other rulemakings that are determined to be “significant regulatory action[s]” under Executive Order 12866

– Regulatory Planning and

Review , EPA is required to conduct an economic analysis of the costs and benefits associated with the rulemaking

. In support of this economic anal ysis, EPA has assessed formaldehyde exposures indoors, due to CWPs, in recently constructed or renovated residential structures. In view of the considerable number of situations or structures of potential interest and the limited

amount of current or recen t monitoring data available, a modeling

- based approach was chos en for the exposure assessment. The model that was used for the assessment

– Formaldehyde

Indoor Air Model

- Pressed Wood Products ( FIAM

- pwp ; USEPA 2012 a )

– is an adaptation of

one that initial ly was developed d uring the 1980s by Dr. Thomas Matthews and colleagues at the Oak Ridge National Laboratory (Matthews et al. 1983; Matthews et al. 1987)

.

In brief, t he “Matthews model” was designed to estimate the steady

- state formaldehyde

concentration due to emission sources such as PWPs in a single indoor compartment or zone.
Product e mission rates in the model are dependent on the formaldehyde concentration in the vapor phase, in accordance with Fick’s Law describing the bulk

- vapor interphase at the s urface of a pressed wood emission source . The initial (steady

- state) indoor concentration calculated by

the model is assumed to decrease over time , in accordance with a first

- order exponential process,

as the reservoir of formaldehyde in various sources (o r sinks ) is gradually depleted. A “ back

pressure ” effect also was introduced by Matthew s , which essentially is a dampening effect produced by the amount of formaldehyde in the indoor air already. As noted earl ier , there are many sources of formaldehyde in cluding infiltration of outdoor air, gas

- fired stoves and tobacco smoke. Fick’s law states that the migration of a substance is concentration depend ent

, with the chemical migrating from a higher

- concentration medium to a lower

- concentration one until equil ibrium is established. The total amount of formaldehyde emitted from all sources could

reduce th e amount of formaldehyde emitted from individual PWPs because the concentration gradient is “ pushing back ” towards each PWP source. This effect will increase th e amount of

10 Available at http://www.g po.gov/fdsys/pkg/FR

- 2008

- 06

- 27/pdf/E8

- 14618.pdf

11 Available at http://www.gpo.gov/fdsys/pkg/FR

- 2008

- 12

- 03/pdf/E8

- 28585.pdf

12 Available at http://www.arb.ca.gov/toxics/compwood/compwood.htm13 time over which emissions can occur from any specific PWP

. In reality, this push and pull of formaldehyde from PWPs to indoor air may change many times during a day as the activity patterns of occupants change. For example, a t night people who are sleeping would not be smoking, cooking, or bringing in dry cleaning, all potential sources of formaldehyde. The effects

of activit y patterns are explored in the sensitivity analy s is later in this report.

In the mid

- 1990s a n EPA

- sponsored pilot study w as undertaken (Koontz et al. 1996) to assess

the contribution of UF

- bonded wood products to formaldehyde levels in homes and to evaluate EPA exposure models . Shortly a fter this study was completed, Versar develop ed a modified

version of the “ Matthews model ” for OPPT that included: (1) estimation of steady

- state formaldehyde concentrations for the case of a two

- zone indoor environment ; and (2) incorporation of reversible (re

- emitting) indoor sinks. The modified model also included the option to be run in a s ingle

- zone mode. The model was recently updated and has been subjected to peer review; the updated model has the capability to provide exposure estimates, primarily to support OPPT efforts such as the exposure assessment described in this document.

2.2.2 Scope of the Assessment

As noted above, formaldehyde emissions tend to decrease as the formaldehyde

- bearing mat erials

age. This assessment focuses on formaldehyde concentrations and associated inhalation exposures in recently built or renovated residentia l structures. The FIAM

- pwp model used to support the assessment provides estimates of indoor formaldehyde concentrations due to CWP
emissions. As described in Section 3.2 of the model documentation ( USEPA 20 12 a ), the model

calculates the initial indoor con centration(s) under an assumed steady

- state condition. In real life, a true steady

- state is never achieved, due to the dynamics of formaldehyde source emissions and

indoor sinks. However, it has been observed in field studies that the combined actions of s ources and sinks typically result in an initial rise in the indoor concentration, followed by a “leveling

off” period that may be fairly brief and then a longer period of gradual decline in concentration. The initial formaldehyde concentrations estimated b y the model are intended to approximate indoor concentrations during the leveling

- off period, which often occurs within 30 days or less following the installation of formaldehyde

- bearing materials

.

Inputs to the FIAM

- pwp model include the formaldehyde bac kground concentration, the number of zones (1 or 2), zone volumes and airflows, indoor temperature and humidity, types and

amounts of CWPs installed in the structure and the ir emission rates, and exposure factors such as time spent in/out of the residence for exposure groups including children, workers and retirees.

The results include modeled indoor formaldehyde concentrat ions, both initial “steady

- state” values and those at later points in time, together with exposure estimates such the daily average

conc entra tion (ADC) to which an individual is exposed

. To support the exposure assessment, the model was run for a variety of scenarios by varying inputs such as the type of residence (e.g., single

- family detached , apartment, mobile home), climate zone in whic h the structure is located, amounts of CWPs, and exposure factors for exposed individuals. In addition, the impact on exposure of different analytical options (i.e., different emission s standards) was assessed.

This document discusses various optio ns with respect to formaldehyde and composite wood products, includi ng emissions standards that are different from those set in TSCA Ti tle VI. This

document discusses alternative emissions standards sim ply for informational purposes. The14 breadth of the discussion here sh ould not necessarily imply that EPA has corresponding flexibility in implementing the statute.

2.3 THIS REPORT

Following a discussion of formaldehyde concentrations outdoors and indoors in Section 3 of this document, the modeling approach is descr ibed in Section 4 . The description of approach

includ es : (1) the specific indoor environments (i.e., housing types) of interest ; (2) factors affecting formaldehyde concentrations/exposures and their relative influence as inferred from sensitivity analysis ; and (3) the sets of model inputs that were chosen to support the exposure

assessment . Modeling results, both for indoor concentrations and for associated exposures, are provided in Section 5. The implications of these results, along with information gaps identified in the course of preparing for and conducting the assessment effort, are discussed in Section 6. References cited throughout the document are listed in Section 7.15 

### Section 3

FORMALDEHYDE CONCENTRATIONS OUTDOORS AND INDOORS

3.1 FORMALDEHYDE IN OUTDOOR AIR

Formaldehyde is the most common aldehyde in the outdoor ambient environment and is usually present in the highest concentration of all the major aldehydes and ketones in ambient air (Finlayson

- Pitts and Pitts, 2000). As summarized by ATSDR ( 1999), outdoor formaldehyde levels are quite low (about 0.2 ppb) in unpopulated areas and range from 2 to 6 ppb in suburban areas and from 10 to 20 ppb in heavily populated or industrial areas.

The most current ambient air monitoring data for formaldehyd e come from the EPA’s air quality system database (EPA’s AirData website: http://www.epa.gov/air/data/index.html ). These data have been collected from a wide variety of sources, including state and lo cal environmental agencies, but have not been collected from a statistically based survey. The most recent data, for the year 2007, come from 188 monitors located in 33 states (USEPA 20 12b ). The annual means for these monitors range from 0.7 to 45.0 μg/m 3 (0.56

- 36.3 ppb) and have an overall average of 3.44 μg/m 3 (2.77 ppb). Table 3

- 1 shows a breakout of the data by land use based on the combined data for 2005, 2006 and 2007. The mobile category (land near major highways or interstates such that it is primarily impacted by mobile sources) has the highest mean levels and agricultural lands have the lowest. The means in the table (in μg/m 3 ) for agricultural, residential and commercial areas correspond to 1.7 ppb, 2.2 ppb and 2.65 ppb, respectively.

Most of the recent indoor

- air formaldehyde monitoring studies described in Section 3.2 included

outdoor formaldehyde measurements. The average outdoor formaldehyde concentration measured in these studies ranged from about 2 to 5 ppb.

Table 3

- 1. Ambient Air Formaldehyde Level s (μg/m 3 ) by Land Use Category

Statistic Land Use Category

Agriculture Commercial Forest Industrial Mobile a Residential

No. of samples 17 166 19 61 16 282

Mean ± std. dev. 2.08 ± 0.98 3 .26 ± 2.76 2.79 ± 2.17 6.28 ± 14.45 6.84 ± 7.28 2.75 ± 1.71

Minimum 0.34 0.20 0.40 0.14 2.02 0.17

Maximum 4.34 20.61 7.33 74.72 23.39 12.35

a “Mobile” is ambient air in locations primarily impacted by mobile sources.

Source: AirData for 2005, 2006, and 2007 (USEPA 20 12b )

.16 3.2 FORMALDEHYDE IN INDOOR AIR

3.2.1 Indoor Sources of Formaldehyde

As noted in Section 2.1, indoor sources of formaldehyde include building materials, tobacco smoke, household products, and unvented fuel

- burning appliances. H ou sehold products include

t extile products, carpet, pads and tape, drapes, and a fairly wide array of consumer products (CARB 2005). The most comprehensive set of emission tests for formaldehyde

- bearing products and materials was performed by Battelle for CA RB (Kelly 1996; Kelly et al. 1999). Formaldehyde emissions were determined from bare UF and PF wood products, UF wood products with vinyl, paper and other coatings, and from decorative laminates, permanent

- press fabrics, fiberglass insulation, paper goods, paints, cosmetics and acid

- cured coatings.

Table 3

- 2 lists formaldehyde emission rates for selected indoor sources that were tested under this project. Although initial emission rates for wet products such as nail polish or floor finish generally are muc h higher than those for dry products such as CWPs, the dry

- product emissions can persist for years whereas the emissions for wet products are relatively short

- lived, often declining by orders of magnitude over a time period of 24 hours. The dry

- product emi ssions also decrease in strength with the passage of time, but at a much slower rate of decline.

Table 3

- 2. Emission Rates of Selected Indoor Sources of Formaldehyde

Source of Formaldehyde Emission Rate, μg/m 2 /hr a

Bare Urea

- Formaldehyde Wood Products 8.6 to 1,580

Coated Urea

- Formaldehyde Products < 2.7 to 460

Permanent Press Fabrics 42 to 215

Decorative Laminates 4 to 51

Fiberglass Products 16 to 32

Bare Phenol

- Formaldehyde Wood Produ cts 4.1 to 9.2

Paper Grocery Bags and Towels < 0.6

Latex Paint 502

Fingernail Hardener 215,500

Nail Polish 20,700

Base Coat Floor Finish 1,050,000

Top Coat Floor Finish 421,000

a Values listed for wet products (e.g., latex paint, fingernail hardener ) are average initial emissions.

3.2.2 Recent Studies of Formaldehyde Concentrations Indoors

One of the earlier major studies of formaldehyde indoors was conducted by Sexton and colleagues (1989) in the mid

- 1980s. Participants in this field monitoring st udy, involving 470 mobiles homes in California, were volunteers solicited by mail. One

- week formaldehyde

concentrations were measured in the kitchen and bedroom of each trailer in both winter and17 summer using passive monitors. The average measurement resul t was about 70 ppb during the summer and 80 ppb during the winter; 31 percent of the measurement results exceeded 100 ppb.

More recent formaldehyde field studies of note, mainly in residential structures, are summarized

in Table 3

- 3. The first two studies

– Offerman et al. (2008) and Hodgson et al. (2000)

– both were conducted on new homes, with the Offerman study covering 100+ new single

- family homes in California and the Hodgson study covering fewer structures in the eastern and southeastern regions of th e U.S. but including both manufactured and site

- built homes. The average (geometric mean) formaldehyde concentration indoors was between 30 and 35 ppb for both studies, with maximum values of 117 and 58 ppb reported by the two studies, respectively.

Studie s of existing homes in urban U.S. areas by Liu et al. (2006) and Sax et al. (2006) measured lower average (median) formaldehyde concentrations, on the order of 10

- 15 ppb, and lower maximum values as well, with the highest reported maximum (45 ppb) in a Los Angeles home during the winter. Two Canadian studies (Gilbert et al 2006; Gilbert et al 2005) had nearly identical results; in each case the average (geometric mean) indoor formaldehyde concentration was around 25 ppb and the highest measured concentratio n was slightly above 70 ppb.

Table 3

- 3

. Summary of Recent Formaldehyde Field Monitoring Studies

Study/Reference Description (Location and Number/Types of Structures) Formaldehyde Concentration , ppb

Central Value Range

Offerman et al.

2008 108 new SF homes in CA 31.1 (median) 3.8 to 116.7

Hodgson et al.

2000 New homes in eastern/SE U.S.:

4 new manufactured homes

7 new site

- built homes Geometric Means:

34

36 21 to 47

14 to 58

Liu et al. 2006 234 homes in Los Angeles County, CA;

Elizabeth, NJ; and Ho uston, TX 16.3 (median) 10.2 to 26.4

(5 th

- 95 th percentiles)

Sax et al. 2006 Inner

- city homes: NY City (46)

– winter (W), summer (S) Los Angeles (41)

– Winter (W), fall (F) Medians:

10 W, 15 S

15 W, 12 F 4

- 18 W, 5

- 41 S

6

- 45 W, 6

- 26 F

Gilbert et al. 200 6 96 homes in Quebec City, Canada 24.0 (geo. mean) 7.8 to 73.2

Gilbert et al. 2005 59 homes in Prince Edward Island,

Canada 27.0 (geo. mean) 4.5 to 71.1

Hodgson et al.

2004 4 new relocatable classrooms 8 (average indoor

outdoor level ) 4 to 12
(indoor

- out door)

CARB 2004 Portable and traditional classrooms in

67 California schools (Phase II study) Arithmetic Means: 15 (portable)
12 (traditional) 95 th Percentiles: 26 (portable)
22 (traditional)

CDC 2008/2010;

DHS 2009 519 structures:
Travel trailers (360)
Park models (90)
Mobile homes (69) 77 (geo. mean)

---

---

--- 3 to 590

3 to 590

3 to 160

11 to 320

Maddalena et al.

2008 4 FEMA camper trailers 463 (average) 269 to 753

EPA BASE Study a 100 public/commercial buildings in 37

cities 12 (median) 3.6 to 26.0

(5 th

- 95 th percentiles)

a http://www.epa.gov/iaq/base/18 Some other indoor environments of potential interest for this exposure assessment have been monitored on occasion. During December/January 2007

- 2008 the C DC measured formaldehyde levels in 500+ structures of the types (travel trailers, park models and mobile homes) used by FEMA for displaced Hurricane Katrina/Rita victims (CDC 2008/2010; DHS 2009). The average (geometric mean) formaldehyde concentration in these structures was 77 ppb and the maximum measured concentration was 590 ppb. Under an interagency agreement with the CDC, the

Lawrence Berkeley National Laboratory (LBNL ; Maddalena et al. 2008) studied four FEMA temporary housing units (camper trailers) to assess indoor emissions of aldehydes and other VOCs. Measured formaldehyde levels in these structures ranged from 269 to 753 ppb.

Formaldehyde measurements in buildings other than residential structures have been relatively rare. Probably the most com prehensive survey was the Building Assessment Survey and Evaluation (BASE) study conducted by EPA between 1994 and 1998 to characterize indoor air quality (IAQ) and occupant perceptions in representative public and commercial office buildings

across the U. S. The BASE study used a standardized protocol to collect extensive IAQ data from 100 randomly selected public and commercial office buildings in 37 cities. F ormaldehyde was among the VOCs measured in this study. Measured formaldehyde levels averaged 13 pp b, with a median concentration of 12 ppb and a range (5 th to 95 th percentiles) from 3.6 to 26 ppb. CARB
(2004) measured formaldehyde concentrations averaging 15 ppb in portable classrooms and 12 ppb in traditional classrooms in California (Phase II study

– measurements by field technicians),

with 95 th percentile values of 26/22 ppb for portable/traditional. Hodgson et al. (2004) measured formaldehyde concentrations ranging from 4 to 12 ppb in four new temporary classrooms.

3.3 FORMAL DEHYDE BACKGROUND CONC ENTRATION

As described in Section 3.2 of the model documentation ( USEPA 20 12 a ), t he formaldehyde background concentration reflect s the contribution to the indoor concentration of the outdoor formaldehyde concentration plus indoor sources other than CWPs (e .g., tobacco smok e, permanent press fabrics, paints, cosmetics ). Although no studies have been conducted with the explicit purpose of characterizing the formaldehyde background concentration, such a value conceivably can be inferred from the formaldehyde c oncentration distribution characterized via field monitoring studies. For example, if the field survey focused on existing homes, then those toward the lower end of the concentration distribution presumably would be older homes with aged C WP sources and, t hus, indicative of the background formaldehyde concentration.

Among the recent formaldehyde field studies summarized in the previous section, Liu et al. (2006) reported a 5 th

- percentile value of about 10 ppb. Minimum values from the Sax et al.
(2006) in t wo cities, during two seasons, were on the order of 5 ppb. The Offerman et al. (2008) study, albeit for new homes, had a minimum measured concentration of about 4 ppb. The EPA BASE study, for commercial buildings, had a 5 th percentile value that also was c lose to 4 ppb. These results collectively suggest that an appropriate value for the formaldehyde background concentration would lie between 5 and 10 ppb.19 

### Section 4

MODELING APPROACH

The primary objective of the modeling effort described in this sectio n is to characterize residential formaldehyde exposure s for different segments of the population, under different sets of assumptions and analytical options (e.g., baseline scenario, reduced emissions) regarding the strength of emissions from composite woo d products ( C WPs 13 ). Under t he specific emission

scenarios examined

, the average daily concentration (ADC) of formaldehyde can be used to

examine cancer as well as non

- cancer health endpoints such as sensory irritation and asthma

. A lthough the focus is on r esidential exposure, formaldehyde exposures in other environments where individuals spend time also are considered to provide a total or “ a round

- the

- clock” exposure perspective.

The above con struct is p resented schematically in Figure 4

- 1. The schematic a pplies to a specific exposure group or population segment, of which there are several ( exposure groups are described
later in this section). For each group, baseline and alternative analytical options are contrasted in terms of residential exposure and the associated total exposure. The difference in exposure, as measured by the differential ADC (baseline vs. alternative) , can be translated into a differential

likelihood of an adverse health effect

.

Figure 4

- 1. Modeling Con struct

.

Section 4.1 describes the model that was used for the assessment. As a general rule, expected or average values were used for model inputs, as opposed to a range or distribution of values

. Variability was introduced for certain input parameters expected to have a significant influence on the modeling results (e.g., temperature ). Factors affecting fo rmaldehyde exposure indoors are

described in Section 4.2 and a n analysis to assess the model’s relative sensitivity to the values used for various inputs is prov ided in Section 4. 3

. Section 4. 4 describes the values chosen for model input parameters and Section 4. 5 summarizes th e matrix of model runs that were made.

13 In this report, the term “composite wood product” (CWP) refers only to hardwood plywood, medium density fiberboard, or particleboard whereas “pressed wood product” (PWP) refers to a broader set of wood materials
including, for example, softwood plywood and oriented strand board. Baseline Emissions Scenario

Residential Formaldehyde
Exposure Residential Formaldehyde
Exposure

Total Formaldehyde Exposure Total Formaldehyde Exposure

Differential Formaldehyde
Exposure Alternative Analytical Option20 4. 1 MODEL USED FOR THE ASSESSMENT

As noted in Section 2.2.2, the FIAM

- pwp v2.0 model is being use d to support the exposure

assessment. Model inputs include formaldehyde background concentration, number of zones 14

(one or two), zone volumes and airflows, indoor temperature and humidity, types and amounts of pressed wood products (PWPs) in the ho me and t heir emission s , and exposure factors such as

amount of time spent in and out of the home . The results include modeled indoor formaldehyde concentrations, both initial steady

- state values and those at later points in time, together with exposure estimates s uch as average daily concentra tion (ADC)

. As indicated in S ection 2.2.1, the initial (steady

- state) indoor concentration predicted by the model is assumed to decrease over

time as the reservoir of formaldehyde in various sources (or sinks ) is gradually dep leted. The gradual decrease over time is assumed to follow a first

- order exponential process.

The model, described more fully in a separate document ( US EPA 20 12 a ), provides context

sensitive help as well as an overview on each input/output screen. The use r interface consists of

three input screens

– House Screen, Source Screen and Exposure Screen

– together with a Run

FIAM Model button that provides access to a Result Screen. The House Screen collects

information on house volumes and air flows and provides certain options pertaining to model

calculations. The Source s Screen allows the user to specify the types and amounts of PWPs installed in the house and the zone in which each product is located. The Exposure s Screen

contains location/ activity patte r ns (t ime spent in each zone of the house and environments away
from home) for exposure groups such as infants, children, adults and retirees

. The Results Screen shows modeled indoor formaldehyde concentrat ions, both initial steady

- state values and those at

late r points in time, together with exposure estimates such as average daily concentra tion and percent of time at or above a formaldehyde level of interest

. The exposure estimates are shown

on an annual basis, starting with year 1 (house age 0

- 1 years) and con tinuing through year 11 (house age 10

- 11 years).

Implementation of the model for this exposure assessment required the ability to run the model efficiently , by reduc ing the number of model runs and the subsequent computations needed to
estimate total (24

- hour) exposures for a broad number of exposure groups . An equivalent Excel version, fully checked for identical results given identical sets of inputs, was developed for this

purpose. When running FIAM

- pwp v 2.0 and selecting the default values for each of the structure types (e.g., singl e

- family home, camper trailer), the user will obtain results identical to those provide d in this exposure assessment report.

For this assessment, i t was assumed in the modeling that formaldehyde emissions from P WPs

insta lled during construction of a new residential structure would decay to a near

- zero value within 10 years. Several exposure groups were model ed and the results were compiled within the spreadsheet

– residential

- and total

- ADC estimates for each exposure gro up, for one

- year time segments representing new home s and those aged one year, two years, ..., up to and including 10

years. Beyond 10 years, the emissions from P WPs associated with new construction were

14 In the context of indoor

- air modeling, the term “zone” refers to a compartment or section of a structure, within
which the concentration in air of a pollu tant such as formaldehyde is assumed to be well mixed or relatively uniform

. A two

- zone structure has two such compartments, each with its own well

- mixed concentration but with the average
concentration differing between the two zones.21 assumed to be zero or nearly so , such that the indoor formaldehyde concentration reverts to the assumed background level. These one

- year time segments will be used in the benefits assessment.

4 .2 FACTORS AFFECTING FORMALDEHYDE EXPOSURE INDOORS

Each factor shown in Figure 4

- 2 ultimately affects inhalation e xposure to formaldehyde indoors, either through its effect on the initial concentration (e.g., emission rate), through its effect on the concentration at later points in time (emissions half life), or through human interaction (e.g., activity patterns ) wit h the time

- varying indoor concentration. All factors shown in the figure are available as input parameters in the FIAM

- pwp version 2.0 of the model.

Figure 4

- 2 . Factors Affecting Indoor Formaldehyde Concentrations and Human Exposures. Background Concentration

Structure Volume & Airflows

C WP Loadings & Emission Rates

Indo or Sinks
Temperature & Humidity Initial Indoor Formaldehyde Concentration (steady

- state)

Emissions Half Life Indoor Concentration s
at Later Points in Time

A ctivity P atterns (time spent in
different locations/environments) Exposure Estim ates :
ADC s for Exposure Groups22 4.3 SENSITIVITY ANALYSIS

A preliminary sensitivity analysis was conducted to guide the choice of factors to be varied and

the relative number of variations for each factor. The analysis was conducted for two cases
available in the FIAM

- pwp model

– a convention al ho me (i.e., the single

- family detached ho me used in the EPA formaldehyde pilot study ; see Section 2.2.1) an d a manufactured ho me . The

conventional ho me , with a volume of 471 cubic meters, is conceptualized as having two zones

whereas the manufactured ho me is a single

- zone structure with a volume of 222 cubic meters.

As summarized in Table 4

- 1 for the conventional ho me , t en factors (input parameters) were systematically varied for the sensitivity analysis. T he background concentration and average

concen tration encountered when an individual is away from home both were set to zero for this analysis, so that modeled concentrations and exposures would reflect only the impact of PWPs in

the house. The source and sink loading areas in the table represent one of the actual loading

conditions that were used in the pilot study.

Sensitivity was examined by varying each input parameter

– one at a time

– by 20 percent in each direction (i.e., 20 % lower and 20 % higher) from the base condition shown in Table 4

- 1. Five model outputs were examined for sensitivity to the ten factors: (1) initial concentration in zone 1 (upstairs); (2) concentration 24 months later in zone 1; (3) average daily concentration (ADC); (4) average daily dose (ADD); and (5 ) % of time the con centration is ≥ 0.01 ppm (10
ppb). Values of these outputs for the base condition are listed in Table 4

- 2.

Table 4

- 1. Input Values for Sensitivity Analysis

– Base Condition for Conventional Ho me

Input Parameter(s) Base Value(s)

Air Exchange Rate (ACH) 0. 59

Emissions Half Life (years) 2.92

Temperature (°C) 23

Relative Humidity (%) 50

Source Loading Area s a (m 2 ) 46, 59, 35, 4

Sink Loading Area s a (m 2 ) 94, 420

House A ge at Move

- in (years) 5

Years Lived in H ouse 5

H our s in H ouse on W ee kd a y, W ee k e nd Day 15, 18

Inhalation R ate (m 3 /day) 13.3

a Sources are underlayment, cabinets, interior doors, and countertop;

sinks are carpet/padding and painted wallboard

.

Table 4

- 2. Model Results for Base Condition for the Conventional Ho me

Initial Conc in
Zone 1,

mg /m 3 Conc 24 Months
Later in Zone 1,
mg/m 3 Average Daily
Concentration,
mg/m 3 Average Daily
Dose, mg/kg

- day % of Time

Concentration

≥ 0.01 ppm

0.0514 0.0320 0.0061 0.0011 13.723 Changes in each model output associated with the change in each input, in e ach direction, were averaged and then expressed as a percent change from the result for the base condition. The sensitivity results are summarized in Figure 4

- 3 as the percent change for each model output associated with a 20 % change in each input. Certai n inputs, by definition, do not affect certain model outputs. For example, the emissions half life has no effect on the initial concentration and the inhalation rate affects only the average daily dose . Based on this analysis, the most sensitive input para meters, in order of relative sensitivity (most sensitive first), are indoor temperature, emissions half life, house age, and indoor humidity.

Figure 4

- 3

. Relative Model S ensitivity for the Conventional Ho me

.

For the manufactured ho me (Table 4

- 3), the same ten factors were systematically varied for the sensitivity analysis. As with the conventional ho me , the background concentration and average concentration encountered when an individual is away from home both were set to zero for the analysis. A broa der set of PWPs, with generally higher loading rates, was used for this case. As a result, the modeled initial concentration was about three times as high as the conventional home
case (Table 4

- 4). Due to the higher concentration, a higher threshold (0.02 ppm) was used to examine the relative frequency of higher concentrations. As with the conventional ho me , the most sensitive input parameters for this case are indoor temperature, emissions half life, house age, and indoor humidity (Figure 4

- 4 ).24 Table 4

- 3

. Input Values for Sensitivity Analysis

– Base Condition for Manufactured Ho me

Input Parameter(s) Base Value(s)

Air Exchange Rate (ACH) 0.5 0

Emissions Half Life (years) 2.92

Temperature (°C) 23

Relative Humidity (%) 50

Source Loading Area s a (m 2 ) 95, 5 3, 26, 3, 43, 36

Sink Loading Area s a (m 2 ) 72, 158

House A ge at Move

- in (years) 5

Years Lived in H ouse 5

H our s in H ouse on W ee kd a y, W ee k e nd Day 15, 18

Inhalation R ate (m 3 /day) 13.3

a Sources are PB underlayment, paneling, interior doors, countertop (p articleboard)

,

cabinets, and closet shelving ( PB / MDF ); sinks are carpet/padding and wallboard

.

. Table 4

- 4

. Model Results for Base Condition for the Manufactured Ho m e

Initial Conc in
Zone 1,
mg/m 3 Conc 24 Months
Later in Zone 1,
mg/m 3 Average Daily
Concentration,
mg/m 3 Average Daily
Dose, mg/kg

- day % of Time

Concentration

≥ 0.02 ppm

0.1507 0.0937 0.0178 0.0033 35.0

Figure 4

- 4

. Relative Model Sensitivity for the Manufactured Ho m e

. 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00% 

### Percent Change in Model Output Due to 20 % Change in Input Value

Initial Concentration

Conc @ 24 months

ADC

ADD

% Time ≥ 0.02 ppm25 4

. 4 MODEL INPUTS

4 .4.1 Background Concentration

As described in Section 3. 3 of this document, t he background conc entration reflect s the

contribution to the indoor concentration of the outdoor formaldehyde concentration plus indoor

sources other than pressed wood products (e.g ., tobacco smok e, permanent press fabrics, paints,

cosmetics ). As noted in Section 3.3, resul ts of field studies indicate that an appropriate value for the residential background concentration would lie between 5 and 10 ppb. The midpoint of this

range

– 7.5 ppb

– was chosen as the background concentration for all modeling runs.

4 .4.2 Housing Typ es and House Volumes

To limit the number of model runs, it is desirable to minimize the number of structure categories yet retain sufficient diversity to make appropriate or necessary distinctions. The first distinction

is between a “one

- zone ” and a “two

- z one ” structure. One

- zone means one floor or story, and pertains to structures such as m anufactured homes, apartments , and camper trailers. Two

- zone pertains to structures that can have multiple stories, including single

- family attached and

detached homes.

Structure c ategories were established to sufficiently cover major housing types used in the American Housing Survey (AHS) ( http://www.census.gov/hhes/www/housing/ahs/ahs.html ) and in

the Residential Energy Consumption Survey (RECS) ( http://www.eia.doe.gov/emeu/recs/ ): single

family (SF) detached homes; SF attached homes; multi

- unit structures (apartments); and

manufactured/mobile homes or trailers. For the purpose of estimating structure volume, a further

distinction was made for manufactured homes due to distinct size differences

– single

- wide (SW)

versus double

- wide (DW). C amper trailers and park models also are of interest because, like

m anufactured homes, these ho us ing types have been used for some residents displaced by natural

disasters such as Hu rricane Katrina

. C amper trailer s were chosen to represent the small

- volume temporary housing for displaced residents

, as this t ype of housin g accounted for 80 percent of the

smaller

- volume housing types that were tested as part of FEMA’s formaldehyde monitoring in such temporary housing (CDC 2008/2010; DHS 2009).

An apartment could be a challenging case for modeling because it interacts not o nly with the outdoors but also with adjacent apartments. However, an apartment unit that is adjacent to a new apartment can be assumed to be new as well, such that the adjoining apartments would have

similar formaldehyde concentrations and, thus, could be safely ignored. With this assumption or caveat, apartments were modeled in the same manner as other one

- zone residential structures.

For SF detached / attached homes, apartments, and m anufactured homes, the structure volume was inferred from statistics pro vided by the U.S. Department of Energy’s 2005 RECS 15

, using the average floor area for the most recently built category (years 2000

- 2005) and assuming a ceiling height of 8.5 feet. For camper trailers

, a typical size assigned to displaced hurricane victims was used, with an assumed ceiling height of 7 feet

.

15 See, for example, http://www.eia.doe.gov/emeu/recs/contents.html26 The following floor areas and associated dimensions were assumed for the five structure types:

1. SF detached home

– 3456 sq ft (36 ft x 48 ft, 2 stories)

2. SF attached home

– 2240 sq ft (28 x 40 ft, 2 stori es)

3. Apartment

– 1120 sq ft (28 ft x 40 ft)

4. M anufactured home

– 1216 sq ft (16 ft x 76 ft) for SW; 1680 sq ft (28 ft x 60 ft) for DW

5. Camper trailer

– 328 sq ft ( 8 ft x 3 5 ft with 4 ft x 12 ft “slide

- out”)

The dimensions chosen for SF homes and apartments we re consistent with their respective average floor areas as reported in the RECS 2005 survey results.

The dimensions listed above are exterior dimensions; for interior volume calculations, 0.5 ft was subtracted from both the length and width to account for the area occupied by exterior cladding, sheathing, studs and wallboard. For SF homes a simplifying assumption was made that the upper

and lower floors are of identical dimensions. For manufactured homes, a weighted average of

SW and DW volumes was used; b ased on statistics from the U.S. Census Bureau’s Manufactured
Home Survey (MHS) for years 2000

- 2009 ( http://www.census.gov/const/www/mhsindex.html ),

70 percent of the manufactured homes were ass umed to be the double

- wide type

. The resultant

house volumes are listed , along with the house dimensions, in Table 4

- 5

.

Table 4

- 5

. House Dimensions and Calculated Volume for Five Housing Types

Housing Type Number of

Stories Length,

ft Width,

ft Ceiling
Height, ft Volume,

ft 3 (m 3 )

SF Detached 2 48 36 8.5 28,6 66 (811)

SF Attached 2 40 28 8.5 18,466 (523)
Apartment 1 40 28 8.5 9,233 (261)
Manufactured

Single

- wide

Double

- wide
Average a 1

1

1 16

28

-- 76

60

-- 8.5

8.5

8.5 9,947 (282)

13, 908 (394)
12,720 (360)
Camper Trailer

Main body

Slide

- out 1

1 35

12 8

4 7

7 2,147 (61)

a Weighted average of single

- wide (30 %) and double

- wide (70 %) ; see text.

4.4.3 Airflow Rates

A single air exchange rate, in air changes per hour (ACH), was assumed for each structure type. Because the modeling focus is on new housing, t he chosen value was toward the lower end of the

distribution , as newer structures tend to be better sealed and have lower air exchange rates

. For
residences, the Exposure Factors Handbook ( EFH ) suggests 0.45 ACH as a central value and

0.18 as a lower

- end value, based on statistic s developed by Koontz and Rector (1995) from a database of perfluorocarbon tracer (PFT) measurement results. The EFH also cites a study by
Murray a nd Burmaster (1995) using the same database ; t hese authors summarized distributions for subsets of the data defined by climate region and season. The 10 th percentile value ranged

from 0.1 to 0.3 ACH across climates and seasons , averaging about 0.20 ACH.27 I n a 2008 study by Offerman et al

. on ventilation and formaldehyde in new California homes, the

25 th percentile value for air exchange rate was 0.2 ACH for the two larger subsets of homes that

were studied. In a study by Maddalena (2008) concerning chemical emissions in four FEMA temporary housing units (camper trailers), the measured air exchange rate varied from 0.15 to 0.39 ACH across the trailers, averaging 0.25 ACH. Persily et al. (2010) modeled air infiltration rate distributions for the U.S. housing s tock; for single

- family homes built in 1990 or later, the

25 th percentile value was 0.15 ACH and the 50 th percentile value was 0.26 ACH. Given the

above statistics

, 0. 2 ACH was chosen as the value to represent new home s, including

detached/attached homes, apartments, manufactured homes, and camper trailers. For the

renovation case a central value such as 0.45 ACH

, as suggested in the EFH

, may be more appropriate. However, the data on which th at suggested value is based are somewhat dated and

there has been a general tendency toward increasing airtightness of U.S. homes over time; for example, the median value reported for the Offerman et al. (2008) study is 0.33 ACH. Thus, a

value of 0.40 ACH

– double that used for new ho mes

– was chosen for the renovation c ase.

The indoor

- outdoor airflow rates that were used for modeling can be determined from the house volume and air exchange rate. For example, for an apartment with a volume of 261 m 3 and an air exchange rate of 0.2 ACH or 0.2 air changes per hour, the in door

- outdoor airflow rate would be
( 261 m 3 x 0.2/h ) , or 52.2 m 3 /h. A balanced flow was assumed

– that is, the airflow rate from outdoors to indoors was assumed to equal the rate from indoors to outdoors. For two

- zone

structures

– SF detached or attached ho mes

– the house volume was equally apportioned between the upper and lower stories/floors and identical indoor

- outdoor airflow rates were assumed for each story. Further, as an expedience, it was assumed that the airflow rate between the two

indoor zones w as balanced and equal to the indoor

- outdoor airflow rate. Thus, for example, for a

SF detached home with a volume of 811 m 3 or 4 05 .5 m 3 per story, both the airflow rate per story

and the interzonal airflow rate were set to (4 05 .5 m 3 x 0.2/h), or 8 1 .1 m 3 /h

.

4 .4. 4 Emissions Half Life

As described in Section 3.6 of the FIAM

- pwp model documentation, suggested values for the formaldehyde emissions half life , reflecting its decay over time, range from 1.5 to 3 years

. An estimate of 2.92 years was based on a cross

- sectional analysis of homes of varying ages, as a proxy for time

- series data from one or a few ho m es. If none of the materials or furnishings in such homes were changed by the occupants, then this approach might provide an unbiased

estimate of the ha lf life. However, as a house ages the occupants will tend to add or replace materials and furnishings, some of which may emit formaldehyde. Such changes introduce new

sources, thereby raising the formaldehyde concentration and artificially inflating the ha lf

- life

estimate ; t hus, the estimate is best viewed as an upper bound. A more likely value, based on

chamber studies of collection s of pressed wood products as they aged, is within the range of 1.5 to 2 years. An emissions half

- life of 1.5 years was chosen for this analysis; with this half life, the emission rate 10 years after new construction would be about 1 % of the initial value.

4.4.5 Indoor Temperature and Humidity

The FIAM

- pwp model is more sensitive to indoor temperature than to any other single factor and

also is relatively sensitive to indoor humidity (see Section 4.3). No nationally representative study was identified in which indoor temperature and humidity have been measured. The RECS, which is nationally representative, does ask survey respo ndents about usual temperatures28 maintained in the residence. One of the questions

– “ At what temperature does your household usually keep your home in the winter ?”

– is asked under three conditions: (1) during the day

when someone is home; (2) during the d ay wh en no one is home; and (3) during sleeping hours

. The same set of questions also is posed with reference to the summer season

.

Temperature. The RECS database was analyzed for these questions to estimate the year

- round average temperature in each of f ive different climate zones that have been defined by the U.S. Energy Information Administration (EIA). The five climate zones are delineated in Figure 4

- 5

. Formaldehyde modeling was performed separately for each housing type in each climate zone.

Figure 4

- 5

. U.S. Climate Zones

.

Source : U.S. Energy Information Administration ( http://www.eia.doe.gov/emeu/cbecs/climzonenew.gif )

Table 4

- 6 summarizes responses to the RECS questions on daytime temperature when someone is home and nighttime (sleeping hours) temperature by climate zone. The columns labeled “Overall” are weighted averages of the daytime and nighttime average temperatures for summer and winter, with weights of 2/3 for daytime and 1 /3 for nighttime. The overall summer and winter temperatures, in turn, were averaged to derive a year

- round average temperature, by29 weighting the season

- specific averages by the number of months associated with each. The resultant year

- round temperature es timates are listed in Table 4

- 7

.

Table 4

- 6 . Summer and Winter Indoor Temperatures from RECS 2005, by Climate Zone

Climate

Zone Average Summer Temperature Average Winter Temperature

Day Night Overall Day Night Overall

1 (coldest) 73.4 73.3 73.4 69.1 65.8 68.0

2 73.0 73.0 73.0 69.6 67.6 68.9

3 73.2 73.2 73.2 69.8 68.1 69.3

4 73.9 73.2 73.7 70.9 68.6 70.1

5 (warmest) 75.1 74.8 75.0 72.4 70.6 71.8

Table 4

- 7 . Year

- round Indoor Temperatures Derived from RECS 2005, by Climate Zone

Climate

Zone Summer Tem p erature Winter Temp erature Year

- Round

Temperature Average
Temperature Number of

Months Average
Temperature Number of

Months

1 (coldest) 73.4 3 68 .0 9 69.4

2 73.0 4 68.9 8 70.3

3 73.2 4 69.3 8 70.6

4 73.7 5 70.1 7 71.6

5 (warmest) 75.0 7 71.8 5 73. 6

Humidity. The RECS does not ask about humidity levels maintained in the residence. Consequently, a mass

- balance modeling approach was applied to estimate the year

- round average indoor relative humidity (RH) level for each climate zone. A representativ e city was

chosen for each zone:

• Climate Zone 1

– Milwaukee, WI

• Climate Zone 2

– Chicago, IL

• Climate Zone 3

– New York, NY

• Climate Zone 4

– Charlotte, NC

• Climate Zone 5

– Houston, TX

Hourly outdoor temperatures for a typical meteorological year 16 (TMY) wer e obtained for each city as inputs to the mass

- balance model that was developed. The m ass

- balance approach, which

is consistent with methods described in American Society for Heating, Refrigerating and Air

-

16 Available at http://rredc.nrel.gov/solar/old_data/nsrdb/1991

- 2005/tmy 3/

.30 Conditioning Engineers ( ASHRAE ) Standard 160P ( Cri teria for Moisture

- Control Design Analysis in Buildings), expresses moisture in the indoor air as a function of moisture in the outdoor air, indoor moisture generation by the occupants, and moisture removal by a central air

conditioning (AC) system. More s pecifically, a steady

- state mass

- balance equation for the water concentration in indoor air can be expressed as follows:

Where:

C

wi = Average hourly water concentration in the indoor air (g/m 3 )
Q inf = Hourly airflow rate due to natural ventilation (m 3 /s)

C

wo = Average hourly water concentration in the outdoor air (g/m 3 )
Q

AH = Average hourly airflow rate through the air handler, factoring in run

- time (m 3 /s)

C

wAH = Water concentration in the air leaving the air conditioner coils, assumed to be at the dewpoint of the coil temperature (g/m 3 )

S i = Moisture generation rate due to occupant presence/activities (g/s)

An average floor area of 2,000 sq ft was assumed, together with an average of 2.5 occupants and an average of 1.8 bathrooms, based on stat istics from the RECS and AHS surveys. An air exchange rate of 0.2 ACH was assumed, consistent with the value selected for formaldehyde modeling (see Section 4.4.3). The calculations for moisture removal via air conditioning, which

are not included in ASHRA E 160P, involved an AC sizing algorithm based on house size, design outdoor temperature, cooling thermostat setting equal to the overall summer temperature per

Table 4

- 6 , and an assumed coil temperature of 55 °F.

The steady

- state approach is an oversimpl ification, in that the hourly run time for the air handler actually is determined by dynamic processes affecting the indoor air temperature at any point in time. For example, during a period of rising outdoor temperature the air conditioner will not

come o n as soon as the outdoor temperature meets or exceeds the setpoint, due to the thermal lag in the indoor environment. Similarly, later in the day, when the outdoor temperature falls below the setpoint, the air conditioner will continue to run due to the th ermal lag indoors.

As an expedience, the run time for the air handler during the cooling season was determined based on the outdoor temperature relative to the thermostat setpoint (the overall RECS summer temperature in the above table was used as the se tpoint for each per climate zone). This expedience is practical because we are interested in estimating an annual average RH value and the two types of biases noted above tend to cancel out. That is, the overestimation of run time when the outdoor temperat ure is rising early in the day generally is compensated by the underestimation later in the day.

To account for the thermal lag, a running average of multiple hours (i.e., average of the current hour and some number of previous hours) was used for the ou tdoor temperature, with the number of hours to be used in the running average set as a user input. It was found, through experimentation with different values for the number of hours used to average the outdoor temperature, that the bottom

- line model outpu t

– average indoor RH level over the entire year

– AH i

wAH AH wo
wi 

### Q Q S C Q C Q C

+ + +

=

inf inf31 was not very sensitive to the length of time used in the running average, due largely to the self

compensating effects of the thermal lag.

A phenomenon similar to the temperature lag indoors also occurs with the RH level . When the outdoor temperature dictates that the AC will operate after a period of no operation, the model predicts the RH to immediately achieve the steady

- state value whereas it actually would take several hours to dehumidify the air to that value. This bias is offset by periods, usually in the evening or night, when the AC is no longer needed after operating during previous hours. At such a time, the indoor RH will rise gradually over several hours because the AC is no longer removing m oisture, whereas the model instantaneously predicts the relatively high RH value due to the AC not operating.

Modeling results are listed for each climate zone in Table 4

- 8 for two cases

– with and without

an AC unit

– based on a 6

- hour running average fo r outdoor temperature. The effect of the AC unit is most pronounced in Houston, due primarily to the higher outdoor temperature and, hence, the greater AC run time leading to greater moisture removal from the house. Because the vast majority of the U.S. ho using stock has air conditioning 17 , the estimated RH values with AC were used in the formaldehyde modeling.

Table 4

- 8 . Modeled Year

- round Indoor RH Level, by Climate Zone

Climate Zone RH Level with AC RH Level with out AC

1 (coldest) 59.1% 63.8%

2 58.1% 64.7%

3 56.3% 66.4%

4 59.8% 72.6%

5 (warmest) 61.4% 85.3%

4 .4. 6 P WP Loadings

– New

- ho me Case

The types and loading rates of PWPs, and the subset of C WPs

, can vary both across structure

types and over time within the same structure. Modeling results a re not as sensitive to the loading rate (because of the “concentration feedback” effect) as to some other parameters , most notably temperature and humidity. On the other hand, C WPs are the focus of this assessment. To develop a representative loading rate, t wo loading rates ( higher and lower ) were defined for each housing type and then averaged

.

The following philosophy was adopted in determining appropriate loading rates for different types of P WPs in the various structures . Technically, the specific sou rce (cabinets, countertop, paneling, etc.) of each P WP type does not matter, as the model treats all sources in the same way.

Thus, for each loading scenario it is sufficient to determine and then sum all exposed surface

areas per PWP type. F loor plans wer e used as a basis for develop ing the loadings ( see Appendix

17 According to the Residential Energy Consumption Survey, 84 percent of U.S. housing units had air

- conditioning equipment as of 2005 ( http://205.254.135.24 /emeu/recs/recs2005/hc2005_tables/detailed_tables2005.html ).

.32 A for examples ). Spreadsheets were developed to document the specific P WP components (and associated loadings) comprising each general type or class listed in the tables in this section

. E xample s of these spreadsheets are provided in Appendix B. The loading rates differed for the new

- ho m e v ersus renovation cases . The loading s are described

for the new

- ho me case below and for the renovation case in the next s ection ( 4.4.7 )

.

Single

- family Home s

. Ta ble 4

- 9 lists the loading and mix of P WPs, including the loading ratio

– the ratio of exposed surface area ( m 2 ) to volume ( m 3 )

– for single

- family detached homes. Table

4

- 10 provides the same information for single

- family attached homes. For each of these two

story housing types, loading information is provided for each story, with the upstairs (sleeping
area) labeled as Zone 1 and the downstairs ( living area) labeled as Zone 2

. The PWP types or

classes in the ta bles generally refer to exposed PWP surfaces

. Underlayment was assumed to be OSB and doors were assumed to have an MDF or largely hollow interior and an exterior covered with primer. Countertops were assumed to have bare PB on the underside and cabinet drawers

were assumed to have bare MDF on the und erside. Cabinet sides and backs, floor/ceiling trim,

and the interiors of cabinet doors were assumed to be coated with a vinyl/plastic film. Shelves in the kitchen pantry and master bedroom closet, along with the top, sides and shelves of an

entertainment center and the exteriors of cabinet doors, were assumed to be made of HWPW.

Table 4

- 9

. PWP L oading/Mix for S F De tached Home s (volume = 811 m 3 )

– New Ho m e

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Average
Loading, m 2

(Zone1, Zone 2) Loading
Ratio, m 2 /m 3

Underlayment 117.49, 117.49 104.44, 104.44 110.97 , 110.97 0.274 , 0.274

Doors 39.8 0, 19.9 0 39.8 0, 19.9 0 39.80, 19.90 0.098, 0.049
Countertop a 1.20

, 3.44 0.96, 2.75 1.08, 3.10 0.003, 0.008

Cabine t drawer s a 2.79

, 4.65 2.44, 4.06 2.62, 4.36 0.006, 0.011

Cabinet Sides/Backs, Floor/Ceiling Trim

, Cabinet Doors Interior 26.48, 47.84 24.91, 43.60 25.70, 45.72 0.063, 0.113

Cabinet Doors Ext erior

, Shelves , ET Center 8.04, 24.17 7.60, 22.87 7.82, 23.52 0.019, 0.058

a Exposed underside

Table 4

- 10. PWP Loading/Mix for SF Attached Homes (volume = 523 m 3 )

– New Ho m e

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Average
Loading, m 2

(Zone1, Zone 2) Loa ding
Ratio, m 2 /m 3

Underlayment 75.68

, 75.68 67.61,67.61 71.65, 71.65 0.274, 0.274

Doors 34.64, 17

. 32 34.64, 17

. 32 34.64, 17

. 32 0.132, 0.066
Countertop a 1. 49, 5.57 1.29, 4.84 1.39, 5.21 0.005, 0.020

Cabinet drawer s a 2.32, 5.11 2.03, 4.47 2.18, 4.79 0. 008, 0.018

Cabinet Sides/Backs, Floor/Ceiling Trim

, Cabinet Doors Interior 18.96, 41.90 17.58, 37.48 18.27, 39.69 0.070, 0.15233 Cabinet Doors Ext erior

, Shelves, ET Center 9.17, 22.48 8.74, 21.17 8.96, 21.83 0.034, 0.083

a Exposed underside34 Apartment s

. Table 4

- 11 lists the loading / mix of PWP s, together with the loading ratio, for apartments. Unlike single

- family homes, apartments are assumed to be one

- story and are conceptualized as consisting of a single zone. The types of PWP s assumed for apartments ar e the same as for single

- family homes, but with different loading ratios in most cases.

Table 4

- 11

. PWP Loading/Mix for Apartments (volume = 261 m 3 )

– New Ho m e

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Average
Loading, m 2

(Zone1, Zone 2) Loading
Ratio, m 2 /m 3

Underlayment 75.68 67.28 71.48 0.274

Doors 30.09 30.09 30.09 0.115
Countertop a 3.72 2.79 3.26 0.013

Cabinet drawer s a 5.11 4.18 4.6 5 0.018

Cabinet Sides/Backs, Floor/Ceiling Trim

, Cabinet Doors Interior 49.18 46.97 48.08 0.184

Cabinet Doors Ext erior

, Shelves, ET Center 27.07 24.75 25.91 0.099

a Exposed underside35 Manufactured Home s

. Table 4

- 12 lists the loading / mix of PWPs, together with the loading ratio,

for manufactured homes. The composite case in the lower third of the table, representing a weighted average of the single

- wide (30%) and double

- wide (70%) cases that also are shown in

the table, was used for modeling. The composition of each PWP type/class was assumed to b e the same as for single

- family homes and apartments, except that cabinet sides and backs were assumed to be vinyl/plastic covered for the higher loading and HWPW for the lower loading 18

.

Table 4

- 12

. PWP Loading/Mix for Manufactured Home s ( volume = 360 m 3 )

– New Ho m e

PWP Type/Class Higher
Loading, m 2 Lower Loading, m 2 Average
Loading, m 2 Loading
Ratio, m 2 /m 3

Single

- wide (SW) (volume = 281 m 3 )
Underlayment 81.54 72.48 77.01 0.274

Doors 23.09 23.09 23.09 0.082
Countertop a 3.72 2.79 3.26 0.012

Cabinet drawer s a 4.18 3.25 3.72 0.013
Floor/Ceiling Trim

, Cabinet Doors Interior 21.43 17.48 19.46 0.069

Cabinet Sides/Backs b 29.31 17.88 N/A 0.104, 0.064

Cabinet Doors Ext erior

, Shelves, ET Center 26.60 22.65 24.63 0.088

Double

- wide (DW) (vol ume = 393 m 3 )
Underlayment 114.01 101.34 107.68 0.274

Doors 28.87 28.87 28.87 0.073
Countertop a 4.65 3.72 4.19 0.011

Cabinet drawer s a 5.11 4.18 4.65 0.012
Floor/Ceiling Trim

, Cabinet Doors Interior 25.36 21.41 23.39 0.060

Cabinet Sides/Back s b 34.42 22.99 N/A 0.088, 0.058

Cabinet Doors Ext erior

, Shelves, ET Center 30.40 26.45 28.43 0.072

Composite (30% SW; 70 % DW) (volume = 360 m 3 )
Underlayment

--- --- 98.48 0.274

Doors

--- --- 27.14 0.075
Countertop a

--- --- 3.91 0.011

Cabinet drawer s a

--- --- 4.37 0.012
Floor/Ceiling Trim

, Cabinet Doors Interior --- --- 22.21 0.062

Cabinet Sides/Back s b 32.89 21.46 N/A 0.091, 0.060

Cabinet Doors Ext erior

, Shelves, ET Center --- --- 27.29 0.076

a Exposed underside

b Assumed to be vinyl/plastic

- covered for hi gher loading and HWPW for lower loading

18 Observations of new manufactured homes on dealers’ lots indicated that higher

- priced models tend to have more
cabinets, covered with vinyl/plastic, whereas lower

- priced models tend to have fewer cabinets, made of HWPW.36 Camper Trailer s

. Table 4

- 1 3 lists the loading and mix of PWP s, together with the loading ratio, for camper trailers. For t his housing type

, several additional pressed

- wood furnishings were included, such as a wardrob e , a composite wood unit surrounding the refrigerator, and composite wood fronts for the lower portions of a bed, dinette and sofa, that are not included for any of the other housing types. The exterior portions of all cabinets, wardrobe, pantry, and bed/d inette/sofa

fronts were assumed to be made of HWPW.

Table 4

- 1 3

. PWP Loading/Mix for Camper Trailer s (volume = 61 m 3 )

– New Ho m e

PWP Type/Class Higher
Loading, m 2 Lower Loading, m 2 Average
Loading, m 2 Loading
Ratio, m 2 /m 3

Underlayment 17 .10 14.25 15.68 0.258

Doors 5.16 5.16
Countertop a 1.11 0.93 1.02 0.017

Cabinet drawer s a 2.32 1.86 2.09 0.034

Cabinet/Wardrobe/Pantry

Doors/Fronts Int erior + Trim 8.45 7.24 7.85 0.129

Cabinet/Wardrobe/Pantry

Doors/Fronts Ext erior

, ET Center, Fridge Unit, Bed/dinette/sofa fronts 21.15 19.94 20.55 0.338

Cabinet/Wardrobe/Pantry

Sides/Backs 24.13 19.28 24.23 0.399

a Exposed underside

4.4.7 PWP Loadings

– Renovation Case

For th is case, it was assumed that an entire kitchen was renovated, incl uding cabinets, countertop and ancillary areas such as a pantry. It was further assumed that the vinyl covering the kitchen floor and adjacent hallway floor was replaced with engineered wood. Bathroom vanities also were assumed to be replaced. The interior doors , underlayment and trim throughout the house

were assumed to re main as before the renovation, as were PWP s in any areas beyond the kitchen other than the hallway floor. Thus, for example, unlike the new

- ho m e case

, it was assumed that a

new entertainm ent center was not installed.

Single

- family Homes. T he PWP loading / mix for the renovation case is shown for single

- family

detached homes in Table 4

- 14 and for single

- family attached homes in Table 4

- 15. As in the previous tables for the new

- ho m e case, loa ding information is provided for each zone of these

two

- story ho mes (Zone 1 is the upstairs / sleeping area and Zone 2 is the downstairs / living area )

. The loadings for countertop and cabinet drawers are the same as the new

- ho m e case

. The loadings for cabinet sides, cabinet backs and interior doors of the cabinets, all assumed to be vinyl/plastic covered, are somewhat lower than for the new

- ho m e case because certain areas of the house are unaffected by the renovation. The HWPW components are higher in the reno vation case, however, because the addition of an engineered wood floor more than compensates for the HWPW that are unaffected by the renovation, such as the entertainment center and shelves in the

master bedroom closet.37 Table 4

- 14. PWP Loading/Mix for SF Detached Homes (volume = 811 m 3 )

- Renovation

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Average
Loading, m 2

(Zone1, Zone 2) Loading
Ratio, m 2 /m 3

Countertop a 1.20

, 3.44 0.96, 2.75 1.08, 3.10 0.0 03, 0.008

Cabinet drawer s a 2.79

, 4.65 2.44, 4.06 2.62, 4.36 0.006, 0.011

Cabinet Sides/Backs,

Cabinet Doors Interior 12.54, 33.91 10.97, 29.67 11.76, 31.79 0.029, 0.078

Cabinet Doors Exterior,

Shelves, Engineered

Wood Floor 3.48, 39.71 3.05, 38.41 3. 27, 39.06 0.008, 0.096

a Exposed underside

Table 4

- 15. PWP Loading/Mix for SF Attached Homes (volume = 523 m 3 )

- Renovation

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Average
Loading, m 2

(Zone1, Zone 2) Loading
Ratio, m 2 /m 3

Countertop a 1. 49, 5.57 1.29, 4.84 1.39, 5.21 0.005, 0.020

Cabinet drawer s a 2.32, 5.11 2.03, 4.47 2.18, 4.79 0.008, 0.018

Cabinet Sides/Backs,

Cabinet Doors Interior 11.03, 35.42 9.65, 30.99 10.34, 33.21 0.040, 0.127

Cabi net Doors Exterior,

Shelves , Engineered

Wood Floor 3.48, 27.34 3.05, 26.03 3.27, 26.69 0.012, 0.102

a Exposed underside

Apartments, Manufactured Homes and Camper Trailers

. T he PWP loading / mix for renovation is shown for apartments in Table 4

- 16, for man ufactured homes in Table 4

- 17, and for camper

trailers in Table 4

- 18. As noted previously, these homes all are one

- story, single

- zone structures.

Differences as well as similarities between the renovation and new

- ho m e cases for these homes are along the sa me lines as described above for single

- family detached and attached homes.

Table 4

- 16. PWP Loading/Mix for Apartments (volume = 261 m 3 )

- Renovation

PWP Type/Class Higher
Loading, m 2

(Zone1, Zone 2) Lower Loading, m 2

(Zone1, Zone 2) Ave rage Loading, m 2

(Zone1, Zone 2) Loading
Ratio, m 2 /m 3

Countertop a 3.72 2.79 3.26 0.013

Cabinet drawer s a 5.11 4.18 4.6 5 0.018

Cabinet Sides/Backs,

Cabinet Doors Interior 40.88 38.67 39.78 0.152

Cabinet Doors Exterior,

Shelves, Engineered

Wo od Floor 23.11 20.79 21.95 0.084

a Exposed underside38 Table 4

- 17. PWP Loading/Mix for Manufactured Homes (volume = 360 m 3 )

-- Renovation

PWP Type/Class Higher
Loading, m 2 Lower Loading, m 2 Average
Loading, m 2 Loading
Ratio, m 2 /m 3

Single

- wide (SW) (volume = 281 m 3 )
Countertop a 3.72 2.79 3.26 0.012

Cabinet drawer s a 4.18 3.25 3.72 0.013

Cabinet Doors Interior 9.29 8.13 8.71 0.031

Cabinet Sides/Backs b 22.06 17.88 N/A 0. 079 , 0.064
Cabinet Doors Exterior,

Shelves, Engineered

Wood Floor 23 .90 25.80 24.85 0.088

Double

- wide (DW) (volume = 393 m 3 )
Countertop a 4.65 3.72 4.19 0.011

Cabinet drawer s a 5.11 4.18 4.65 0.012

Cabinet Doors Interior 11.61 10.45 11.03 0.028

Cabinet Sides/Backs b 27.17 22.99 N/A 0.069, 0.058
Cabinet Doors Exterior,

Shelves, Engineered

Wood Floor 30.10 30.10 30.10 0.077

Composite (30% SW; 70 % DW) (volume = 360 m 3 )
Countertop a

--- --- 3.91 0.011

Cabinet drawer s a

--- --- 4.37 0.012

Cabinet Doors Interior

--- --- 10.33 0.062

Cabinet Sides/Backs b 25.64 21.46 N/A 0.0 71, 0.060
Cabinet Doors Exterior,

Shelves, Engineered

Wood Floor --- --- 28.53 0.076

a Exposed underside

b Assumed to be vinyl/plastic

- covered for higher loading and HWPW for lower loading

Table 4

- 18. PWP Loading/Mix for Camper Trailers (volume = 61 m 3 )

– Renovation

PWP Type/Class Higher
Loading, m 2 Lower Loading, m 2 Average
Loading, m 2 Loading
Ratio, m 2 /m 3

Countertop a 1.11 0.93 1.02 0.017

Cabinet drawer s a 2.32 1.86 2.09 0.034

Cabinet/Wardrobe/Pantry

Doors/Fronts Interior 4.76 4.18 4.47 0.074

Cabinet/Wardrobe/Pantry

Doors/Fronts Exterior

, Fridge Unit, Bed/dinette/sofa
fronts , Engineered Wd Floor 11.06 11.06 11.06 0.182

Cabinet/Wardrobe/Pantry

Sides/Backs 14.47 12.03 13.25 0.218

a Exposed underside39 4 .4. 8 C WP Emission Rat es

Baseline Emissions Scenario. B etween June and October 2010

, EPA administered a survey to domestic manufacturers of composite wood panels ; t he survey asked about both current and planned emission levels. Because m any CWP manufacturers are in the midst of modifying their production technology and raw materials to achieve compliance with Phase 2 of the CARB ATCM, using current emission levels to estimate emission levels in 2013 would not accurately

reflect the 2013 baseline. Instead, baseline emission level s we re estimated using responses to a survey question about emission levels that mills planned to achiev e within the next three years.

These emission levels were weighted by production levels that mills reported in the survey, in order to estimate average emission levels by certification standard. The survey data also were used to estimate the share of total production volume represented by products meeting each of

the emission standards. The survey results are reported in Table 4

- 19. For comparison purpose s, the CARB emission limits (which are identical to the FSCWPA limits) are shown in Table 4

- 20.

Table 4

- 19. Base line Emission Levels (2013) For Domestically Produced CWPs,
by Product Type and Emissions Certification Standard

Emissions Standard Product T ype

HWPW MDF PB

Weighted Average Emissions (ppm)

None 0.058

--- 0.058

CARB 1 a

--- --- 0.090

CARB 2 0.032 0.082 0.057

CARB ULEF b 0.024 0.042

CARB NAF c 0.013 0.035 0.013

Share of Production

None 0.4%

--- 0.2%

CARB 1

--- --- 1.8%

CARB 2 60.2% 86.1% 88.5%

CARB ULEF 4.6% 2.8%

CARB NAF 39.4% 9.3% 6.7%

a Some mills producing product s currently certified under CARB Phase 1 (CARB 1) reported that they would
continue this product line after the CARB Phase 2 (CARB 2) effective date.

b Hardwood plyw ood mills meeting CARB 2 and CARB Ultra Low Emission Formaldehyde ( ULEF ) were grouped together in the CARB 2 category. Several HWPW mills appeared to be meeting CARB ULEF
standards but did not report this in their response. For example, they listed the cer tification standard as “CARB
2” but the resin type as “ULEF” and/or reported maximum emissions that satisfy ULEF requirements. Due to
difficulties in distinguishing between CARB 2 and CARB ULEF product lines and the fact that emission levels
appeared simil ar among mills reporting either CARB 2 or CARB ULEF certification standards, these mills were grouped together.

c NAF = No Added Formaldehyde.40 Table 4

- 20. Formaldehyde Emissions Standards in the CARB Air Toxic Control Measure
for Formaldehyde Emissio ns from Compressed Wood Products a (ppm)

Emissions Standard HWPW MDF Particleboard

CARB 1 0.08 0.21 0.18

CARB 2 0.05 0.11 b 0.09

CARB ULEF

– less frequent testing 0.05 90% of samples < 0.06 All samples < 0.09 c 90% of samples < 0.05 All samples < 0.0 8

CARB ULEF

– exemption from third party certification 90% of samples < 0.04 All samples < 0.05 90% of samples < 0.04 All samples < 0.06 90% of samples < 0.04 All samples < 0.06

CARB NAF 90% of samples < 0.04 All samples < 0.05 90% of samples < 0.04

All samples < 0.06 90% of samples < 0.04 All samples < 0.06

a The FSCWPA emission limits are the same as the CARB ATCM limits.

b The CARB 2 emission limit for thin MDF is 0.13 ppm.

c The CARB ULEF limits for thin MDF are 90% of samples < 0.08 ppm and all samp les < 0.11 ppm.

Among imported products, baseline emission levels were estimated separately for products from Canada versus those from the rest of the world. The known composite wood manufacturers in Canada were compared to the CARB list of certified mill s, and most Canadian mills were found

to be CARB

- certified. As a result, Canadian mills were assumed to achieve the same baseline
emissions as U.S. mills (whose emissions are shown above in Table 4

- 19).

The baseline emission levels for non

- Canadian import ed CWPs were estimated using data from a 2009 presentation by Professional Service Industries (PSI 2009), a CARB Third Party Certifier
( TPC ). Although PSI is located in the U.S., the mills that it certifies are located mainly in Asia. 19

The mills certifie d by PSI are located in countries that are major sources of pressed wood products imported into the U nited States; thus, the data from the PSI presentation were assumed to represent emission levels from all non

- Canadian CWPs imported into the U.S.

The PSI presentation included histograms of observed formaldehyde emission levels for hardwood plywood, MDF, and particleboard. The data included emission levels for 387, 198, and 193 samples of hardwood plywood, MDF, and particleboard, respectively, and for all t hree product types combined. After imputing the data underlying these graphs, the average emission values reported in the presentation were successfully replicated. 20 This information was used to estimate the number of samples at different emission levels.

19 According to CARB’s list of certified mills, as of November 12, 2010

, PSI was the TPC for 95 mills in 9
countries. The countries, and the number of mills certified by PSI in each, a re as follows: Argentina (1) ; Chile (1) ; China (55) ; Ecuador (2) ; Indonesia (2) ; Malaysia (26) ; the Philippines (1) ; Taiwan (1) ; and Thailand (6).

20 The emission levels in the graphs seemed to be labeled according to the interval midpoints (e.g., a reported value of 0.05 ppm represented an inter val of 0.0375 to 0.075 ppm). The maximum values reported in the presentation for
MDF and particleboard were used for the maximum intervals. The median value was used for the median interval
for MDF. The data in the hardwood plywood graphic were consistent with an average value of 0.07 ppm rather than
the 0.05 ppm value that could be calculated from the summary statistics shown in the presentation for all three
product types combined. For hardwood plywood, the three highest emission levels (all of which exce eded 1.0 ppm)
seemed to be driving this discrepancy; thus, they were dropped from the analysis. After dropping these outliers the imputed average emissions matched the 0.05 ppm value that could be calculated from the other summary statistics
shown in the p resentation.41 The emission levels reported in the PSI presentation ranged from near zero to levels exceed ing the CARB 2 emission standards by a substantial margin. The emission levels observed in these data were from a period after CARB 1 took effect but before CARB 2 d id. Because many of the

mills that met the CARB 1 standards at the time when samples were taken may subsequently achieve CARB 2 levels, baseline emissions were predicted by assuming that products with

emission levels between the CARB 1 and CARB 2 levels in the PSI data would achieve CARB 2 levels by 2013. Emission levels of 0.06 and 0.05 ppm were used for CARB 2 baseline emissions for MDF and particleboard, respectively, because these levels represent the midpoints of the highest emission intervals in the P SI data that meet the CARB 2 limits. None of the intervals in

the PSI data for HWPW reflected the CARB 1 emission limits ( t he CARB 1 limit of 0.08 ppm is spanned by the interval of 0.075 to 0.125 ppm in the PSI data and the CARB 2 limit of 0.05 ppm is span ned by the interval of 0.0375 to 0.075 ppm). Therefore, no adjustments were made to hardwood plywood for the shift from CARB 1 to CARB 2. After making the MDF and PB adjustments, the average emissions by product type were calculated (see Table 4

- 21).

Alth ough a number of samples in the PSI data had emission levels close to zero, it was not possible to determine whether the products qualify for certification as ultra low

- emitting formaldehyde ( ULEF ) or no added formaldehyde ( NAF ) 21 ; the PSI presentation did not identify the resin type used for each sample. Also, as indicated in a footnote to Table 4

- 20 above, NAF and ULEF have emissions requirements that must be met by 90% of the samples from a mill as well a ceiling value that must be met by all samples. Thi s distribution of emissions could not be determined from the PSI presentation; thus, baseline emission levels were not estimated separately for non

- Canadian imports of ULEF and NAF products. Such products are included in

the baseline emission estimates for the CARB

- 2 category.

Table 4

- 21 also includes the share of imports for each product type and emissions standard. This share was estimated by assuming that the fraction of samples for each category in the PSI presentation is equivalent to the share of imp orts for that category across all non

- Canadian composite wood products imported into the U.S.

Table 4

- 21. Baseline Emission Levels f or Non

- Canadian Imported Composite Wood
Products, by Product Type and Emissions Standard

Emissions Standard Hardwood Plywo od MDF Particleboard

Average Emissions (ppm)

None 0.163 0.502 0.384

CARB 2 0.015 0.047 0.036

Share of Imports

None 26% 11% 38%

CARB 2 74% 89% 62%

21 Resin formulations that meet the NAF definition are those that do not contain any added formaldehyde in their

formulation.42 The estimates presented above in Table 4

- 21 rely on several critical assumptions that are a

source of uncertainty in this analysis, the most important being as follows:

• The sample is representative of imported non

- Canadian composite wood products.

− It is not known whether the sample is representative of products destined for the

United States. The destinat ion of these products could be other countries or their country of origin. On the one hand, U.S. end users may be more likely to insist on

lower

- emitting products. On the other hand, U.S. end users not shipping to California face less stringent formaldehyd e emissions standards than many other potential destinations. (Although many end users prefer to handle a single type of product, rather than one product that meets the California requirements and another type for the
other 49 states). The fact that the sa mples were being tested for formaldehyde emissions by a CARB TPC suggests that many of them were produced by mills whose products ultimately end up in the U.S.

• The distribution of emission levels will not change for mills that were producing products

wit h emission levels that currently exceed the CARB 1 standards.

− If some of these mills decide to obtain CARB 2 certification, it is not known whether these will be the higher or lower emitting mills on average. Some additional mills
(aside from those below t he CARB 1 limits but above the CARB 2 limits) may subsequently decide to lower their emission levels.

− Conversely, the PSI data may under

- represent imported products with very high

emission levels. Mills making products likely to exceed the CARB levels ma y not have had their products tested because they intended to sell them in the other 49 states

.

• The percentage of samples with current emissions below CARB 1 levels is a reasonable estimate of the percentage of mills that will be achieving CARB 2 levels in the baseline

scenario.

− The PSI presentation was given after CARB 1 was in effect but before CARB 2 was. It is not known whether more overseas producers ultimately will meet the Phase 2 emission limits than initially met the Phase 1 limits.

For the purp oses of TSCA Title VI, laminated products are a subset of hardwood plywood. The

statute defines a laminated product as one made by affixing a wood veneer to a particleboard,

medium

- density fiberboard, or veneer

- core platform. The statutory definition goes on to state that laminated products are component parts used in the construction or assembly of a finished good, and that a laminated product is produced by the manufacturer or fabricator of the finished good in which the product is incorporated. EPA is gi ven the authority to modify the statutory definition of laminated product through rulemaking. EPA also is directed to use all available and relevant information to determine whether the definition of hardwood plywood should exempt engineered veneer or any laminated product.

Note that baseline emissions data are not available for hardwood plywood defined as laminated products. The CARB 1 standard for hardwood plywood is used to represent the average baseline

emission level for laminated product s made in t he U.S. and Canada. The CARB 1 level

represent s the average emission level that CARB found prior to promulgating the ATCM. It reflects a mix of products using different resin types, including both UF and NAF resins. This43 level is considered to be a reasona ble proxy for domestically produced laminated products. These products are thought to generally be made with UF or PVA resin, so their emissions may be similar to those from stock hardwood panel products before the ATCM went into effect. For laminated pr oducts made outside the U.S. and Canada, average baseline emissions wer e assumed to be the same as the levels for imported hardwood plywood that does not meet an emission standard (estimated from the PSI presentation). Emissions data prior to the CARB

ATCM are not available for non

- Canadian imported hardwood plywood. Because the PSI presentation was given after CARB 1 was in effect, it presumably reflects a reduction in emissions compared to pre

- ATCM levels. Therefore, if baseline laminated product emission s are similar to pre

- ATCM emissions, using the average of all non

- Canadian imported hardwood plywood would underestimate emission levels for laminated products. Using the estimated average emissions from hardwood plywood that does not meet an emissions sta ndard reflects the possibility that many of these imported laminated products are made with UF resins.

Table 4

- 22 lists the emission levels used for the baseline 2013 scenario for CWPs, including laminated products; the values listed reflect the assumptio ns and choices described above. The estimated share of U.S. consumption also is listed in the table for each product type and associated country of origin.

Table 4

- 22. Baseline Emission Levels for Composite Wood Products by Product Type,
Country of Origin , and Emission Standard

Emissions

Standard Hardwood Plywood MDF Particleboard Laminated Products

U.S./Can. Non

U.S./Can. U.S./Can. Non

U.S./Can. U.S./Can. Non

U.S./Can. U.S./Can. Non

U.S./Can.

Average Emissions (ppm)

None 0.058 0.163

--- 0.502 0.058 0. 384 0.058 0.163

CARB 1

--- --- --- --- 0.090

--- --- ---
CARB 2 0.032 0.015 0.082 0.047 0.057 0.036

--- ---
CARB ULEF 0.024 0.042

CARB NAF 0.013 0.035 0.013

Share of U.S. Consumption

None 0.1% 16.6%

--- 0.8% 0.2% 1.1% 36.0% 64.0%

CARB 1

- -- --- --- --- 1.7%

--- --- ---
CARB 2 19.7% 47.4% 79.2% 7.2% 85.0% 1.9%

--- ---
CARB ULEF 4.2% 3.0%

CARB NAF 16.2% 8.6% 7.1%44 Analytical Option Scenarios. Seven analytical options were evaluated in the assessment, as

listed and described b riefly in Table 4

- 23. The first four options

– CARB1, CARB2/Statutory Option, CARB2/Statutory Option including laminated products at NAF, and NAF

– assume that progressively higher percentages of CWPs meet stricter emission standards. The last three

scenar ios are similar to CARB1, CARB2/Statutory Option, and NAF, with the single exception that laminated products are not regulated as HWPW under TSCA.

Table 4

- 23. Alternative Analytical Options Evaluated in the Exposure Assessment

Analytical Option Descripti on

CARB1, Including

Laminate d Products All CWPs, including laminated products a , are at emission levels that meet

CARB Phase 1 standards1. Products that meet CARB Phase 1 standards at

baseline are assumed to remain at that emission level.

CARB2 /Statutory Option

, Including Laminate d

Products b All CWPs, including laminated products, are at emission levels that meet

CARB Phase 2 standards. Products that meet CARB Phase 2 standards at

baseline are assumed to remain at that emission level.

CARB2 /Statutory Opti on

, with Laminate d Products

at NAF As above, except that laminated products are assumed to meet NAF c

standards.

NAF, Including

Laminate d Products All CWPs, including laminated products, are at emission levels that meet

NAF standards. Products that meet NA F standards at baseline are assumed

to remain at that emission level.

CARB1, Excluding

Laminate d Products Like CARB1 above, except that laminated products are not regulated as

HWPW and, thus, are assumed remain at baseline emission levels.

CARB2 /Statutor y Option

, Excluding Laminate d

Products Like CARB2 above, except that laminated products are not regulated as

HWPW and, thus, are assumed remain at baseline emission levels.

NAF, Excluding

Laminate d Products Like NAF above, except that laminated products a re not regulated and,

thus, are assumed remain at baseline emission levels.

a 30 % of all HWPW products are assumed to be laminated products

.

b Th e CARB emission standards for this scenario are equivalent to th ose specified in the FSCWPA.

c NAF = no added formaldehyde.

In the economic analysis presented to the Small Business Advocacy Review (SBAR) Panel for the formaldehyde rule, EPA estimated that HWPW production (excluding engineered wood flooring) was 1,749 thousand square feet (on a 3/8

- inch basis) in 2006, and that laminated product production (excluding engineered wood flooring) was about 408 million square feet on a

5/8

- inch basis, equivalent to about 680 million square feet on a 3/8

- inch basis. Thus, based on these estimates, laminated products ac count for about 28% of combined HWPW production. The Hardwood Plywood and Veneer Association has indicated that laminated products represent about 30% of engineered wood flooring production ( HPVA 2010 )

. Therefore, this exposure analysis assumes that lamina ted products represent 30% of the volume of HWPW

.45 Table 4

- 2 4 lists emission levels and market shares for the same set of CWPs under the assumption that CARB1 emission limits are in effect for all CWPs, including laminated products. In compiling this tabl e, it was first assumed that emission levels of all products meeting CARB1 or stricter (CARB2/ULEF/NAF) standards at baseline would not change. Next, it was assumed that any products listed as not meeting any emission standard at baseline, but

whose emissi on levels would comply with CARB1, also would remain at their baseline emission levels. For example, some U.S.

- produced HWPW and PB products are not certified as meeting an emission standard at baseline but nonetheless have emission levels that comply with CARB

Phase 1 emission limits; thus, their emission levels are assumed to remain at the baseline level

under this scenario/ analytical option. As noted in a table footnote, for the CARB1 analytical option laminated products were assumed to be at the same em ission levels as HWPW if regulated and at baseline emission levels (see Table 4

- 22) if not regulated.

Table 4

- 2 4

. Emission Levels for CARB1 Analytical Option by CWP Type, Origin, and Emissions Standard

Emissions

Standard Hardwood Plywood a MDF Particleboa rd

U.S. Non

- U.S. U.S. Non

- U.S. U.S. Non

- U.S.

Average “Emissions” (ppm)

None

--- --- --- --- --- --- CARB1
( previously NOT
CARB1) 0.058 b 0.058

--- 0.14 c 0.058 b 0.090

Already at

CARB1 --- --- --- --- 0.090

---

CARB2 0.032 0.015 0.082 0.047 0.057 0.036

ULEF

--- --- 0.024

--- 0.042

---
NAF 0.013

--- 0.035

- 0.013

- Share of U.S. Consumption

None

--- --- --- --- --- --- CARB1
( previously NOT
CARB1) 0.1% 16.6%

--- 0.8% 0.2% 1.1%

Already at

CARB1 --- --- --- --- 1.7%

---

CARB2 19.7% 47.4% 79.2% 7.2% 85.0% 1.9%

ULEF

--- --- 4.2%

--- 3.0%

---
NAF 16.2%

--- 8.6%

--- 7.1%

---

a For the CARB1 scenario that includes laminated products, those products are assumed to have the same emission levels as hardwood plywood; for the CARB1 scenario that excludes la minated products, those products are assumed

to have baseline emission levels as listed in Table 4

- 22.

b Products in these cells have baseline emission levels that comply with CARB1, even though producers reported
that they were not intentionally meeting a ny particular standard. Because the baseline levels comply with CARB1,
the emission levels for these products are assumed not to change and, thus, are the same as listed in Table 4

- 14.

c Products in this cell are not CARB1

- compliant at baseline; thus, thei r emission levels are assumed to change for

the CARB1 scenario. The assumed emission level is 67 % of the level that would exactly comply with CARB1; as noted in the text, industry generally sets target emission levels below the standard to ensure that it is being met

, given variability across/within production lots as well as measurement uncertainty.46 For the CARB1 scenario it was further assumed that products listed as not meeting any emission

standard at baseline, and whose emission levels exceed the CARB Phase 1 limit, would attain emission levels equal to those of corresponding U.S. products listed as not meeting any emission standard but nonetheless complying with CARB1 at baseline. For example, non

- U.S. HWPW not complying with CARB1 at baseline, with a n average emission level of 0.163 ppm, was assumed to match the level (0.058 ppm) of U.S.

- produced HWPW complying with CARB1 at baseline,
and its market share (16.6%) was shifted from “None” to “CARB1” in the table.

Lastly, it was assumed that products n ot meeting any emission standard at baseline, and for which there are no comparable products complying with CARB1 at baseline, would obtain an emission level equal to 67% of the CARB1 limit

– the CWP industry generally sets targets for

emission levels belo w the standard to ensure that it is being met

, considering the variability across/within production lots as well as measurement unc ertainty. For example , non

- U.S. MDF,

with an emission level at baseline (0.502 ppm) that is not CARB1

- compliant, was assumed to change to a level equal to 67 percent of the CARB1 standard (0.67 x 0.21 ppm = 0.14 ppm).

Table 4

- 2 5 lists emission levels and market shares for the analytical option where CARB2 /TSCA Title VI statutory emission limits are in effect. As with the CARB1 scenario, it was assumed that emission levels of all products already meeting CARB2 or stricter standards (ULEF/NAF) would not change. Next, it was assumed that products not meeting CARB2 at baseline (including those meeting the less strict CARB1 standard) would obtain emission levels equal to U.S. products 22 of the same CWP type that comply with CARB2 at baseline. For example, both U.S.

- produced HWPW (baseline level of 0.058 ppm) and non

- U.S. HWPW (baseline level of 0.163 ppm) were

assumed to shift to a CAR B2

- compliant emission level of 0.032 ppm. For this analytical option, laminated products were assumed to be at the same emission levels as HWPW if regulated and at

baseline emission levels (see Table 4

- 22) if not regulated.

22 Emission levels for U.S. CARB2

- compliant products (as opposed to non

- U.S. products) were chosen because

the data set from which average emission levels were determined was larger and, thus, considered more reliable.47 Table 4

- 2 5

. Emission Levels f or CARB2 Analytical Option by CWP Type, Origin, and Emissions Standard

Emissions

Standard Hardwood Plywood a MDF Particleboard

U.S. Non

- U.S. U.S. Non

- U.S. U.S. Non

- U.S.

Average “Emissions” (ppm)

None

--- --- --- --- --- ---
CARB1

--- --- --- --- --- -- - CARB2
( previously NOT
CARB2) 0.032 0.032

- 0.082 0.057 0.057

Already at

CARB2 0.032 0.015 0.082 0.047 0.057 0.036

CARB2

--- --- 0.024

--- 0.042

---
ULEF 0.013

--- 0.035

--- 0.013

---
NAF

--- --- --- --- --- --- Share of U.S. Consumption

None

--- - -- --- --- --- ---
CARB1

--- --- --- --- --- --- CARB2
( previously NOT
CARB2) 0.1% 16.6%

--- 0.8% 1.9% 1.1%

Already at

CARB2 19.7% 47.4% 79.2% 7.2% 85.0% 1.9%

CARB2

--- --- 4.2%

--- 3.0%

---

ULEF 16.2%

--- 8.6%

--- 7.1%

---
NAF

--- --- --- --- --- -- -

a For the CARB2 scenario that includes laminated products, those products are assumed to have the same emission
levels as hardwood plywood; for the CARB2 scenario that excludes laminated products, those products are assumed

to have baseline emission lev els as listed in Table 4

- 22.

Table 4

- 2 6 lists emission levels and estimated percentages under the analytical option whereby

NAF emission limits are in effect. First, it was assumed that emission levels of all products meeting the NAF standard at baseline would not change. Next, it was assumed that products not meeting NAF at baseline (including those meeting less strict standards) would attain the emission levels for U.S. products of the same CWP type that are NAF

- certified at baseline. For example, U.S.

- produced HWPW accounts for 36 percent of all HWPW production. A subset of the U.S. HWPW production, accounting for 19.8 percent, does not comply with NAF at baseline

but attains a NAF

- compliant emission level of 0.013 ppm under the NAF analytical option ; t he remaining 16.2 percent, already NAF

- compliant, likewise has an emission level of 0.013 ppm. Lastly, it was assumed that MDF products meeting ULEF at baseline, but with average emission

levels lower than those for NAF

- compliant MDF products at baseline, would not change. As

with the analytical options described above (CARB1 and CARB2), for the NAF analytical option laminated products were assumed to be at the same emission levels as HWPW meeting the NAF

standard if regulated and at baseline emission level s (see Table 4

- 22) if not regulated.48 Table 4

- 2 6

. Emission Levels for NAF Scenario by CWP Type, Origin, and Emissions Standard

Emissions

Standard Hardwood Plywood a MDF Particleboard

U.S. Non

- U.S. U.S. Non

- U.S. U.S. Non

- U.S.

Average “Emissions” (ppm)

N

one

--- --- --- --- --- ---
CARB P1

--- --- --- --- --- ---
CARB P2

--- --- --- --- --- - NAF ( previously

not NAF with

non

- NAF

emissions ) 0.013 0.013 0.035 0.035 0.013 0.013

NAF ( previously

not NAF with
NAF emissions) --- --- 0.024

--- --- ---

Already at NAF 0.013

--- 0.035

--- 0.013

--- Share of U.S. Consumption

None

--- --- --- --- --- ---
CARB P1

--- --- --- --- --- ---
CARB P2

--- --- --- --- --- --- NAF ( previously

not NAF with

non

- NAF

emissions ) 19.8% 64.0% 79.2% 8.0% 89.9% 3%

NAF ( previous ly

not NAF with
NAF emissions) --- --- 4.2%

--- --- ---

Already at NAF 16.2%

--- 8.6%

--- 7.1%

---

a For the NAF scenario that includes laminated products, those products are assumed to have the same emission
levels as hardwood plywood; for the NAF scena rio that excludes laminated products, those products are assumed to

have baseline emission levels as listed in Table 4

- 22.

Table 4

- 2 7 lists emission levels and market shares under the analytical option whereby CARB2

emission limits are in effect, but wit h the added assumption that all laminated products (assumed to account for 30 percent of all HWPW production) are NAF

- compliant ( e.g., using NAF cores
laminated with NAF resins) at an emission level of 0.013 ppm. Note that the estimated percentages for the U.S. and non

- U.S. HWPW columns have been adjusted in the table such that all HWPW production, including laminates, sums to 100 percent.49 Table 4

- 2 7

. Emission Levels for CARB2 Scenario with Lam inates at NAF by CWP Type, Origin,

and Emissions Standard

E missions

Standard Hardwood Plywood MDF Particleboard Laminated

Products a

U.S. Non

- U.S. U.S. Non

- U.S. U.S. Non

- U.S. U.S. Non

- U.S.

Average “Emissions” (ppm)

None

--- --- --- --- --- --- --- ---
CARB1

--- --- --- --- --- --- --- --- CARB2
( previously

NO T CARB2) 0.032 0.032

--- 0.082 0.057 0.057

--- ---

Already at

CARB2 0.032 0.015 0.082 0.047 0.057 0.036

--- ---

CARB2

--- --- 0.024

--- 0.042

--- --- ---
ULEF 0.013

--- 0.035

--- 0.013

--- --- ---
NAF

--- --- --- --- --- --- 0.013 0.013

Share of U.S. Consumption

None

--- --- --- --- --- --- --- ---
CARB1

--- --- --- --- --- --- --- --- CARB2
( previously

NOT CARB2) 0.1% 11.6%

--- 0.8% 1.9% 1.1%

--- ---

Already at

CARB2 13.8% 33.2% 79.2% 7.2% 85.0% 1.9%

--- ---

CARB2

--- --- 4.2%

--- 3.0%

--- --- -- -
ULEF 11.3%

--- 8.6%

--- 7.1%

--- --- ---
NAF

--- --- --- --- --- --- 10.8% 19.2%

a Assumed to account for 30% of all HWPW production.50 Slopes and Intercepts for Emission Rates

. Section 2.3 of the FIAM

- pwp model documentation

report lists emission r ates for various types of PWP s that were derived from sets of chamber emission tests conducted during the 1980s and up through the mid

- 1990s. A distinguishing feature of these chamber tests is that they were conducted at multiple air exchange rates and/or product loading ratios, enabling estimation of model parameters

– slope and intercept

– that reflect the dependence of the emission rate on the indoor formaldehyde concentration. The s lope is a mass transfer coefficient that reflects the “backpressure” eff ect of the indoor formaldehyde

concentration on the emission rate , whereas t he intercept reflects the hypothetical emission rate when the indoor formaldehyde concentration is zero.

The following equation was used as a basis for determining the intercept ( b ) associated with products meet ing certain emission standards:



## [ ] [ ]

D O CH VOL PEX Area

b

O CH out

SS 2

2 * *

+

= (Eqn. 4

- 1)

where:

[CH 2 O] SS = steady

- state formaldehyde concentration inside the
compartment (mg/m 3 )

[CH 2 O] out = steady

- state formaldehyde concentration outside the

comp artment (mg/m 3 )

b = the emission rate at zero CH 2 O concentration in the air
(mg/m 2

- hr)

Area = Exposed surface a rea of the source (m 2 )

PEX = the compartment’s air exchange rate with outdoors (hr - 1 ), assuming a mixing factor equal to unity

VOL = the volume o f the compartment (m 3 )

D = VOL PEX Area

m

* * 1 +

m = the mass transfer coefficient (m/hr).

Assuming that [CH 2 O] out is zero, s ubstituting for D in Eqn

. 4

- 1 , and denoting PEX * VOL as Q
(i.e., the airflow rate in/out of the chamber

, in m 3 /hr ) , we can sol ve for b as follows :

b = [CH 2 O] SS * (1 + m * Area / Q) * (Q / A rea) (Eqn. 4

- 2)

ASTM E 1333

- 10

, Standard Test Method for Determining Formaldehyde Concentrations in Air
and Emission Rates from Wood Products Using a Large Chamber (ASTM 2010 ), is a commonly

u sed m ethod for demonstrating compliance with formaldehyde emission standards. The method prescribes an air exchange rate for testing of 0.5 hr - 1 (i.e., 0.5 ACH) and product loading rat ios of

0.43 m 2 /m 3 for PB, 0.95 m 2 /m 3 for HWPW , and 0.26 m 2 /m 3 for MDF. Usin g these rates along with an assumed slope ( m ) for a given PWP type, the corresponding intercept can be determined for a hypothetical source that just meets a given emissions standard

.51 For example, the CARB2 emission standard for MDF is 0.11 ppm or 0.135 m g/m 3

. An arbitrary

chamber volume of 100 m 3 , which together with a PEX of 0.5 hr - 1 yields a value of 50 m 3 /hr for

Q , was used in the calculation . T he volume assumed does not matter, as the exposed surface area scales to the volume via the loading ratio

– w ith a volume of 100 m 3 the corresponding surface

area is 26 m 2

. A slope of 1. 06 m/hr was assumed; this value is the average slope from about 30

tests of different MDF specimens, as listed in the FIAM

- pwp model documentation report.

Substituting the assum ed values given above in Eqn. 4

- 2, the intercept ( b ) that corresponds to the

CARB2 emission standard for MDF is calculated as follows:

b = 0.135 mg/m 3 * (1 + 1. 06 m/hr * 26m 2 / 50 m 3 ) * ( 50 m 3 / 26 m 2 )

= 0.40 mg/m 2

- hr

Table 4

- 2 8 lists the calculated interc epts associated with various emission levels for HWPW,

MDF and PB

, as listed previously in Tables 4

- 15 through 4

- 19 , using the calculation method

described above and an assumed slope for each CWP type as indicated in the table.

Table 4

- 2 8

. Calculated Inte rcepts for Various Emission Levels for Each CWP Type

Emission Standard

– Origin Emission Level a Assumed Slope Calculated
Intercept

ppm mg/m 3 m/hr mg/m 2 /hr

H

ardwood Plywood

None

– U.S. 0.058 0.072 0.27 0.057

None

– non

- U.S. 0.163 0.201 0.27 0.160

CA RB1

– U.S. & non

- U.S. 0.0 58 0.0 72 0.27 0.0 57

CARB2

– U.S. 0.032 0.040 0.27 0.031

CARB2

– non

- U.S. 0.015 0.019 0.27 0.019

NAF

– U.S. 0.013 0.016 0.27 0.013

M edium Density Fiberboard

None

– U.S.

--- --- 1.06

--- None

– non

- U.S. 0.502 0.620 1.06 1.849

CARB1

– U

. S

. 0.140 0.173 1.06 0.516

CARB2

– U.S. 0.082 0.101 1.06 0.302

CARB2

– non

- U.S. 0.047 0.058 1.06 0.173

ULEF

– U.S. 0.024 0.030 1.0 6 0.088

NAF

– U.S. 0.035 0.043 1.06 0.129

P

articleboard

None

– U.S. 0.058 0.072 0. 7 0.133

None

– non

- U.S. 0.38 4 0.474 0. 7 0.883

CARB1

– U.S. 0.058 0.072 0. 7 0.133

CARB1

– non

- U.S. 0.090 0.111 0.7 0.207

CARB2

– U.S. 0.057 0.070 0. 7 0.131

CARB2

– non

- U.S. 0.036 0.044 0.7 0.083

NAF

– U.S. & non

- U.S

. 0.013 0.016 0. 7 0.030

a mg/m 3 formaldehyde = ppm formaldehyde * 1.2352 Providing standard

- specific slopes and intercepts for each CWP type would prove cumbersome, exceeding the number of input rows available for sources in the FIAM

- pwp model. It was determined experimentally that using a composite intercept together w ith the corresponding total exposed surface area for a given CWP type yielded identical modeling results to that from the more tedious approach of using values for the individual components meeting different emission standards. The composite intercept was calculated as a weighted average of the individual intercepts, using the market share as the weight ; the resultant c omposite intercepts are shown for

the baseline scenario in Table 4

- 29 for each CWP type

, along with standard

- specific intercepts.

Table 4

- 29

. Composite Intercepts by CWP Type

– Baseline Scenario

Emission Standard

– Origin Slope Intercept Market

Share

Hardwood Plywood

None

– U.S. 0.27 0.057 0.1%

None

– non

- U.S. 0.27 0.160 16.6%

CARB2

– U.S. 0.27 0.031 19.7%

CARB2

– non

- U

. S

. 0.27 0.015 47.4%

NAF

– U.S. 0.27 0.013 16.2%
Composite 0.27 0. 042 100 %
Medium Density Fiberboard

None

– non

- U.S. 1.06 1.849 0.8%

CARB2

– U.S. 1.06 0.302 79.2%

CARB2 non

- US 1.06 0.173 7.2%

ULEF

– U.S. 1.06 0.088 4.2%

NAF

– U.S. 1.06 0.129 8.6%
Composite 1.06 0.2 81 100 %

P

articleboard

None

– U.S. 0.70 0.133 0.2%

None

– non

- U.S. 0.70 0.883 1.1%

CARB1

– U.S. 0.70 0.207 1.7%

CARB2

– U.S. 0.70 0.131 85.0%

CARB2

– non

- U.S. 0.70 0.083 1.9%

ULEF

– U.S. 0.70 0.097 3.0%

NAF

– U.S. 0.70 0.030 7.1%
Composite 0. 70 0.131 100 %

Composite intercepts for baseline and other emission scenarios

– CARB1, CARB2 and NAF

– are shown by CWP type in Table 4

- 3 0 , without the underlying details. The most notable difference across scenarios is that the NAF intercepts are subs tantially lower than for the other three scenarios, for each CWP type.53 Table 4

- 3 0

. Composite Intercepts by CWP Type and Emissions Scenario

CWP Type Composite Intercept

Baseline CARB1 CARB2 NAF

Hardwood Plywood 0. 042 0.025 0.021 0.013
Medium Density Fi berboard 0.281 0.271 0.269 0.127

P

articleboard 0.131 0.124 0.122 0.030

The modeling also accou n ted for some PWP types that would not be subject to emission

stand ards because they are specifically exempt from TSCA Title VI. Underlayment in homes typical ly is either tongue

- and

- groove softwood plywood (SWPW) or oriented strand board
(OSB). The emission rates from earlier chamber tests on SWPW are thought to be applicable to either type; for example, a study by Hodgson et al. (2000) reported virtually the s ame intercept
(0.029) for OSB as did the earlier tests for S WPW (0.030)

.

Interior d oors were represented using estimated emission rates from chamber testing of 6

- panel

white doors that were used in the EPA pilot study ; this is the only known study in whi ch such doors have been tested at multiple air exchange/loading rates, enabling calculation of both a slope and an intercept. The emission rates for these doors also were used to represent those for

coated (but not laminated) CWP materials , assuming a simi lar barrier effect.

Because the interiors of such coated materials presumably would be in compliance with any rules governing CWP emissions, the intercept for interior doors and coated CWPs was varied across

emission scenarios. It was observed that, at baseline, the intercept for these products was close to halfway between the intercepts for HWPW and PB. Thus, the average of those two intercepts for

other emission scenarios

– CARB1, CARB2 and NAF

– was used for doors and coated CWPs ;

t he average intercep ts were 0.074 for CARB1, 0. 0 71 for CARB2, and 0. 0 21 5 for NAF.

Emission factors for underlayment, interior doors, and coated CWPs are listed in Table 4

- 31.

Table 4

- 3 1 . Emission Rates for Underlayment and Coated CWPs

– Baseline Scenario

PWP Type/Class Pro xy Used for Emission Rate Slope Intercept

Underlayment (OSB) Softwood Plywood
(PF R esin ) 0.61 0.03 0

Interior Doors & Coated CWPs a 6

- panel D oors Used in EPA Pilot Study 0.52 0.08 2

a CWPs could be coated, for example, with primer/paint, vinyl film, or thermally fused paper.54 4 .4. 9 E xposure Groups and Activity Patterns

To cover the various exposure situations that can depend on factors such as age and work status, the following exposure groups were defined:

• Infant (age 0 to < 2)

• Pre

- school/school (a ge 2 to <1 6)

• Worker (age 16 to <64 )

• Retiree (age 64 or greater)

The choice of age breaks to distinguish infants and pre

- school/school children from adults was
driven by the possible age dependency of cancer slope factors. The US EPA has developed age

depend ent adjustment factors (ADAFs) 23 to address the potential for differential potency associated with exposure during early life (below 16 years of age). There sometimes is a 10

- fold adjustment for ages 0 to < 2 years and a 3

- fold adjustment for ages 2 to <16 y ears ; there is no adjustment for ages 16 years and older. Workers were split into full

- time and part

- time subgroups ; full

- time workers were further divided to distinguish non

- industry workers from

wood

- industry segments where higher occupational formaldehy de exposures can occur . As described in a separate EPA report ( ERG 2011) , three such industry segments were examined

– manufacturing, fabrication and wholesale. However, sufficient data to support the current

exposure assessment w ere available only for the fabrication segment. In terms of activity patterns, the retiree group also can be used to represent individuals of age 16 to <64 who are unemployed or working at home.

The 2 009 Exposure Factors Handbook ( EFH ) update 24 ( draft ) was the primary source of

inf ormation on activity patterns, that is, how an individual’s time is allocated among residential

and non

- residential locations. Estimates of annual hours at selected home and non

- home location groupings are provided for each exposure group in T able 4

- 3 2 . Th e t otal time spent at home was

determined from EFH tables that indicate the time spent at home in all rooms combined; the time

at home in Zone 1 was defined as the sum of time spent in the bedroom or bathroom

. EFH

statistics indicate that infants spend, on the a verage across the population , one hour per day at daycare facilities. Children of school age were assumed to spend 6.5 hours per day at school, for 180 days per year. Full

- time workers were assumed to spend 8 hours per day at work, for 250 days per y ear. The h ours at work or school for part

- time workers and retirees were based on EFH
statistics, as were the hours in a vehicle for each exposure group. The time spent in “ all other ” environments was determined by subtraction from the total time budget of 8760 hours per year.

23 See, for example, http://www.epa.gov/oswer/riskassessment/sghandbook/chemi cals.htm

. 24 http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=20986655 Table 4

- 3 2 . Annual Hours at Home and Non

- home Location s , by Exposure Group.

Exposure Group Location

Home

Zone 1 a Home

Zone 2 Work or

School or
Daycare In

Vehicle All

Other Total , all

Locations

Infants 4958 1652 365 252 1533 8760

Pre

- school/School 4253 1292 1170 356 1689 8760

Full

- time Workers 3327 2032 2000 590 811 8760

Part

- Time Workers 3935 2038 1000 401 1386 8760

Retirees 3607 3538 107 372 1136 8760

a Zone 1

– upstairs (sleeping area); Zone 2

– downstairs (livin g area).

4.4.1 0 Concentrations at Locations Outside the Home

As noted in the beginning of Section 4, locations outside the home where individuals spend time were considered in the assessment to provide a total or “around

- the

- clock” exposure perspective

. C oncentrations assigned to these locations for the baseline emissions scenario (see Table 4

- 3 3 )

were deriv ed from several sources. In

- v ehicle and outdoor/other concentrations were based on average values reported from EPA’s air monitoring network (see Se ction 3.1). The value assigned to vehicles (6 ppb) is the average reported for the “mobile” land use category; the value assigned to outdoors/other (3 ppb) is the average of values reported for “residential” and “commercial” land use categories , with consi deration also given to outdoor formaldehyde levels measured in residential monitoring studies

. The value assigned to the fabrication

- industry workplace was taken from a recent EPA report ( ERG 2011 ). The v alues assigned to daycares,

schools and non

- industry workplaces involved calculations that are described below.

Table 4

- 3 3

. Concentration Values for Non

- home Locations

– Baseline Scenario

Location Formaldehyde Concentration

pp b μ g/m 3

Day c are 9.8 12.0

School 8.7 10.7

Work, Non

- Industry 10.0 12.3

Work , Fabrication 199

. 5 244

. 9

Vehicle 6

. 0 7

. 4

Outdoors/Other 3

. 0 3

. 756 In developing the baseline concentrations for daycare, school and non

- industry work locations, it was assumed that 10 percent 25 of the buildings in each category were of recent constructio n or were recently renovated. As with the fabrication

- industry workplace, the value for newer buildings associated with the non

- industry workplace was taken from the recent EPA report

reference d above

. Newer s chools w ere assigned the 95 th percentile formal dehyde concentration, thought to represent newer or recently renovated buildings, from a relatively large monitoring study of portable and traditional classrooms in California schools (CARB 2004; see Section 3.2)

. The value assigned to newer daycare facili ties is an average of the concentration for non

- industry

work and averages from field studies of newer home s (see Section 3.2) by Offerman et al. (2008) and Hodgson et al. (2000). For older daycare, school and non

- industry buildings , the 25 th

percentile fo r formaldehyde levels measured in the EPA BASE study was used. Table 4

- 3 4 shows the derivation of the age

- weighted baseline concentration values for these building types.

Table 4

- 3 4

. Derivation of Baseline Values for Daycare, School and Work Locations

Lo cation Formaldehyde Concentration , ppb

Older Buildings Newer Buildings Composite a of

Older & Newer

Day c are 7.0 35.0 9.8

School 7.0 24.0 8.7

Work, Non

- Industry 7.0 36.5 10.0

a Composite value = 90 % x (value for older buildings) + 10 % x ( valu e for newer buildings ).

The values for vehicle and outdoor/other concentrations were kept constant across analytical options whereas those for the other locations were varied (see Table 4

- 3 5 )

, because the formaldehyde concentrations in the fabrication wo rkplace as well as newer /renovated daycares,

schools and non

- indus try workplaces could be affected by a new rule for formaldehyde. As with

the baseline values, the concentrations assigned to the other analytical options for newer non

industry workplaces we re taken from the EPA report reference d above . For daycare facilities the percent reductions across analytical options that were used for fabrication and non

- industry work were applied. A similar approach was used for schools, except that the percent reduc tions were lowered slightly (i.e., by 10 percent) to account for generally higher prevailing air exchange rates in schools, which would tend to temper the effect of formaldehyde emission reductions.

25 The most recent DOE/EIA Commercial Building Energy Consumption Survey (CBECS) indicated that about 5 %

of o ffice buildings and 8 % of education buildings were of recent construction (i.e., 3 years old or less); see http://www.eia.gov/emeu/cbecs/cbecs2003/detail ed_tables_2003/detailed_tables_2003.html , Table B

- 8.57 Table 4

- 3 5

. Concentration Values for Selected Non

- ho me Locations, by Emissions Scenario

Location Formaldehyde Concentration , ppb

Baseline CARB1 CARB2 NAF

Day c are a 9.8 (35.0) 9.5 (30.7) 9.4 (29.7) 8.0 (16.0)

School a 8.7 (24.0) 8.1 (17.8) 8.0 (17.3) 7.3 (10.2)

Work, Non

- Industry a 10.0 (36.5) 9.4 (32.0) 9 .3 (31.0) 7.9 (16.7)

Work, Fabrication 199

. 5 192.0 190.8 93.0

a T he v alues assigned to these locat i ons are a weighted average of those for older buildings (see Table 4

- 31) and

newer buildings (values in parentheses).

4

. 5 MODEL RUN MATRIX

The matrix o f model runs (Table 4

- 3 6 ) to support the exposure as sessment consists of 2 00 cells

that represent all possible combinations of values for the three factors that were varied across

model runs

– housing type (5 types ), climate zone (5 zones ), and analytical option ( 8 scenarios ).

T he results are saved in a spreadsheet for each run

, includ ing ADCs for each environment where exposure groups spend time and a total ADC

, for all environments combined

, for each exp osure group. These results are provided for cases re presenting new ho m es as well as those aged one
year, two y ears, etc., up to and including 10 years.

The m atrix shown in Table 4

- 33 was used for two separate cases

– new homes and recently

renovated homes . The differences between the two cases were in the air exchange rate s (see
Section 4.4.3) and the P WP loadings (see Sections 4.4.6 and 4.4.7 ) that were used.58 Table 4

- 3 6

. Model Run Matrix a

Housing Type Climate Zone

1 2 3 4 5

Baseline Emissions Scenario

SF Detached

SF Attached
Apartme nt Manufactured
Camper Trailer

CARB1 Analytical Option , Including Laminate d Products

SF Detached

.

.

.

CARB2 Analytical Option , Including Laminated Products

SF Detached

.

.

.

CARB 2 Analytical Option , with Laminates at NAF

S F Detached

.

.

.

NAF Analytical Option , Including Laminates

SF Detached

.

.

.

CARB1 Analytical Option , Excluding Laminates

SF Detached

.

.

.

CARB 2 Analytical Option , Excluding Laminates

SF Detached

.

.

.

NAF Analytical Option , E xcluding Laminates

SF Detached

.

.

.

a Applied to both the new

- ho m e and the renovation cases; see text.59 

### Section 5

MODELING RESULTS

5.1 NEW

- HOME CASE

Table 5

- 1 lists one set of modeling results

– initial modeled formaldehyde “steady

- state”

concen trations

– for new residential construction. As described in Section 2 it has been observed that, for new construction, the combined actions of sources and sinks typically result in an initial rise in the indoor concentration followed by a “leveling

- off” p eriod that may be fairly brief and then a longer period of gradual decline. The initial formaldehyde concentrations estimated by the model are intended to approximate indoor concentrations during this leveling

- off period, which often occurs within 30 days or less following the installation of formaldehyde

- bearing materials

.

The initial concentrations are listed for each of eight emissions scenarios (columns in the table), five housing types (sub

- headings within the table), and five climate zones (table row s). Some general patterns apparent from inspection of the table are as follows:

• The highest modeled concentrations are for camper trailers

• Within each housing type, the highest concentrations are in the South (climate zone 5)

• Among the analytical options

, the lowest concentrations occur for the case where CWPs

are at emission levels that meet no

- added

- formaldehyde (NAF) standards (see Table 4

- 23 for brief descriptions of each emissions scenario), whether laminates are regulated or not.

Figure 5

- 1, where in itial modeled concentrations are averaged across climate zones, shows more clearly the patterns of results across emissions scenarios/analytical options and housing types.

Figure 5

- 1. Modeled Initial F ormaldehyde Concentrations by Emissions

Scenario /Ana lytical Option and Housing Type

– New

- home Case

. * Results shown are

for Zone 1 of these

two

- zone structures60 Table 5

- 1. Modeled Initial Formaldehyde Concentrations for Eight Emission s Scenarios, ppb a

– New

- ho m e Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

I ncl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 43.4, 45.4 40.5, 42.0 39.5, 40.8 39.4, 40.6 26.0, 26.6 40.8, 42.4 39.8, 41.3 24.6, 25.4

2 44.8, 46.9 41.8, 43.4 40.7, 42.1 40.6, 4 2.0 26.7, 27.2 42.1, 43.8 41.0, 42.6 25.3, 26.1

3 44.2, 46.3 41.3, 42.8 40.2, 41.5 40.1, 41.4 26.4, 26.9 41.5, 43.2 40.5, 42.0 25.0, 25.8

4 49.6, 52.0 46.2, 48.0 45.0, 46.6 44.9, 46.4 28.8, 29.4 46.5, 48.4 45.3, 47.1 27.6, 28.5

5 57.1, 59.9 53.2, 55.2 5 1.7, 53.6 51.6, 53.3 32.2, 32.9 53.5, 55.7 52.1, 54.2 31.2, 32.3
Single

- family Attached Homes (Zone 1, Zone 2)

1 47.2, 46.8 43.7, 43.0 42.4, 41.7 42.3, 41.5 24.4, 23.6 44.0, 43.5 42.8, 42.3 24.9, 24.3

2 48.8, 48.4 45.1, 44.4 43.8, 43.1 43.7, 42.9 25.1, 24.2 45.4, 44.9 44.2, 43.7 25.6, 25.0

3 48.1, 47.7 44.5, 43.8 43.2, 42.5 43.1, 42.3 24.8, 23.9 44.8, 44.3 43.6, 43.0 25.3, 24.7

4 54.0, 53.6 49.9, 49.1 48.5, 47.6 48.3, 47.4 27.3, 26.3 50.3, 49.7 48.9, 48.3 28.0, 27.2

5 62.4, 61.9 57.5, 56.6 55.8, 54.8 55.6, 54.5 30.9, 29.7 58.0, 57.2 56.3, 55.6 31.6, 30.8
Apartments

1 58.9 53.5 51.6 51.3 26.9 54.1 54.1 29.6

2 61.0 55.3 53.3 53.0 27.6 56.0 55.8 30.4

3 60.0 54.5 52.6 52.3 27.3 55.1 55.0 30.0

4 67.8 61.4 59.2 58.9 30.2 62.2 61.6 33.4

5 78.6 71.1 68.5 68.1 34.3 72.0 70.7 38.0
Manufactured Homes

1 50.4 45.5 43.9 43.5 25.6 46.2 44.9 26.9

2 52.1 47.0 45.3 44.9 26.3 47.8 46.3 27.7

3 51.3 46.3 44.7 44.3 26.0 47.1 45.7 27.4

4 57.8 52.0 50.1 49.7 28.7 52.9 51.3 30.3

5 66.8 60.0 57.8 57.3 32.5 61.1 59.1 34.4
Camper Trailers

1 72.3 57.6 53.6 51.9 30.2 61.3 58.3 36.5

2 74.9 59.6 55.4 53.7 31.1 63.5 60.3 37.7

3 73.7 58.7 54.6 52.9 30.7 62.5 59.4 37.2

4 83.5 66.2 61.5 59.6 34.1 70.6 67.1 41.5

5 97.1 76.8 71.2 69.0 38.9 81.9 77.7 47.6

a Modeled resident ial concentrations, in μg/m 3 , were converted to ppm using the relat ionship ppm = μg/m 3 x CF, where CF is a temperature

- dependent conversion

factor; the CF varied with climate zone from 0.8032 ( c limate z one 1) to 0.8 09 6 ( c limate z one 5), in accordance with the year

- round temperatures given in Table 4

- 7.61 Table 5

- 2, arranged in the same manner as Table 5

- 1, lists the average daily concentration (ADC) within each housing type during the first year (i.e., house age 0

- 1 years) following construction. The patterns of results for the two tables are very similar (e.g., highest levels in camper trailers and in the South).

Table 5

- 3 illustrates the decline in formaldehyde concentrations over the 10

- year period that was modeled, using ADCs for manufactured homes in cli mate zone 3 (see Figure 4

- 9 for a depiction of U.S. climate zones). As noted in Section 4, an emissions half life of 1.5 years was assumed for the exponential decay of formaldehyde from initial modeled values; with this half life, the formaldehyde concentr ations 10 years after construction due to CWP emissions are about one percent of their initial values. As evident in the bottom row of the table, the formaldehyde levels have nearly reached background (7.5 ppb) at this time.

Tables 5

- 4 through 5

- 9 list overall ADCs reflecting combined in

- home and away

- from

- home exposure (i.e., “around

- the

- clock” exposure) for infants, children, non

- industry workers,

fabrication

- industry workers, retirees and part

- time workers during the first year following house

constru ction ; the time allocations for these exposure groups were previously given in Section 4.10. Differences across the exposure groups generally are no more than 20 percent, with the notable exception of fabrication

- industry workers who have substantially hig her overall exposure

due to their elevated at

- work exposure. Such differences can be seen more clearly in Figure 5

- 2, wherein the ADCs for each exposure group are averaged across housing types and climate zones.

Figure 5

- 2

. Modeled ADCs (House Age 0

- 1 Ye ars) for Exposure Groups by Emissions

Scenario /Analytical Option and Housing Type

– New

- home Case

.62 Table 5

- 2. Modeled Residential ADC s (House Age 0

- 1 Years) for Eight Emission s Scenarios

, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB 2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 36.2, 37.8 34.0, 35.1 33.1, 34.2 33.0, 34.1 20.9, 21.4 34.1, 35.4 33.3, 34.5 21. 2, 21.8

2 37.3, 39.1 35.0, 36.2 34.1, 35.2 34.0, 35.1 21.5, 21.9 35.2, 36.5 34.4, 35.6 21.8, 22.4

3 36.9, 38.6 34.5, 35.7 33.6, 34.8 33.6, 34.6 21.3, 21.7 34.7, 36.1 33.9, 35.2 21.5, 22.1

4 41.2, 43.1 38.5, 39.9 37.5, 38.8 37.4, 38.6 23.2, 23.7 38.7, 40 .2 37.8, 39.3 23.6, 24.4

5 47.2, 49.5 44.0, 45.7 42.9, 44.4 42.8, 44.2 26.1, 26.6 44.3, 46.1 43.2, 44.9 26.5, 27.4
Single

- family Attached Homes (Zone 1, Zone 2)

1 39.3, 39.0 36.5, 36.0 35.5, 34.9 35.3, 34.8 21.0, 20.4 36.7, 36.3 35.8, 35.3 21.4, 21.0

2 40.5, 40.2 37.7, 37.1 36.6, 36.0 36.4, 35.8 21.6, 20.8 37.9, 37.4 36.9, 36.4 22.0, 21.5

3 40.0, 39.7 37.1, 36.5 36.1, 35.5 36.0, 35.3 21.3, 20.7 37.4, 36.9 36.4, 36.0 21.8, 21.3

4 44.8, 44.4 41.5, 40.8 40.3, 39.6 40.2, 39.4 23.4, 22.6 41.8, 41.3 40.6, 4 0.2 23.9, 23.3

5 51.4, 51.1 47.6, 46.8 46.1, 45.4 46.0, 45.2 26.2, 25.3 47.9, 47.4 46.6, 46.0 26.8, 26.1
Apartments

1 48.7 44.3 42.8 42.6 23.0 44.8 43.5 25.1

2 50.3 45.8 44.3 44.0 23.6 46.3 44.9 25.8

3 49.6 45.2 43.6 43.4 23.3 45.6 44.3 25.5

4 55.8 5 0.6 48.9 48.6 25.6 51.3 49.7 28.2

5 64.4 58.4 56.3 56.0 28.9 59.1 57.2 31.9
Manufactured Homes

1 41.8 37.9 36.6 36.4 22.0 38.6 37.4 23.1

2 43.2 39.1 37.8 37.5 22.6 39.7 38.6 23.7

3 42.6 38.6 37.3 36.9 22.3 39.2 38.1 23.4

4 47.7 43.1 41.6 41.3 24.5 43 .9 42.6 25.7

5 55.0 49.5 47.8 47.4 27.5 50.4 48.8 29.1
Camper Trailers

1 59.4 47.6 44.4 43.1 25.7 50.6 48.2 30.8

2 61.5 49.2 45.9 44.5 26.4 52.3 49.8 31.7

3 60.5 48.5 45.2 43.9 26.1 51.6 49.1 31.2

4 68.3 54.5 50.8 49.2 28.8 58.1 55.2 34.8

5 79.3 63. 0 58.5 56.8 32.6 67.1 63.7 39.763 Table 5

- 3. Modeled Residential ADCs by House Age for Manufactured Home in Climate Zone 3, by Emission Scenario, ppb

– New

- home Case

House Age (years) at Start of
Exposure Period Baseline CARB1 Incl.

Laminates CARB2 Incl.

L aminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.

0 42.6 38.6 37.3 36.9 22.3 39.2 38.1 23.4

1 29.6 27.0 26.2 26.1 16.8 27.5 26.7 17.5

2 21.4 19.8 19.3 19.2 13.4 20.0 19.6 13.8

3 16.3 15 .3 15.0 14.9 11.2 15.5 15.1 11.5

4 13.0 12.4 12.2 12.2 9.8 12.5 12.3 10.0

5 10.9 10.5 10.5 10.5 8.9 10.6 10.5 9.1

6 9.7 9.4 9.3 9.3 8.5 9.5 9.4 8.5

7 8.9 8.7 8.7 8.7 8.1 8.8 8.7 8.1

8 8.4 8.3 8.2 8.2 7.9 8.3 8.3 7.9

9 8.1 8.0 8.0 8.0 7.7 8.0 8.0 7.7

10 7.8 7.8 7.8 7.8 7.6 7.8 7.8 7.664 Table 5

- 4. Modeled ADC s (House Age 0

- 1 Years) for Infants for Eight Emissions Scenarios, ppb a

– New

- ho m e Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 29.2 27.3 26.6 26.6 17.1 27.5 26.8 17.4

2 30.0 28.0 2 7.4 27.3 17.5 28.3 27.6 17.8

3 29.6 27.7 27.0 27.0 17.3 27.9 27.2 17.6

4 32.8 30.7 29.9 29.8 18.8 30.9 30.1 19.1

5 37.4 34.9 34.0 33.8 20.9 35.1 34.2 21.3
Single

- family Attached Homes (Zone 1, Zone 2)

1 31.1 28.9 28.1 28.0 17.0 29.1 28.4 17.4

2 32.0 29.7 28.9 28.8 17.4 30.0 29.2 17.8

3 31.6 29.3 28.5 28.4 17.2 29.6 28.8 17.6

4 35.2 32.6 31.7 31.5 18.7 32.8 32.0 19.1

5 40.1 37.1 36.0 35.8 20.8 37.4 36.3 21.3
Apartments

1 38.4 35.0 33.9 33.6 18.7 35.4 34.4 20.3

2 39.5 36.1 34.9 34.7 19.1 36.5 35.4 20.8

3 38.9 35.5 34.4 34.2 18.8 35.9 34.9 20.5

4 43.6 39.7 38.4 38.1 20.6 40.2 38.9 22.6

5 50.0 45.5 43.8 43.6 23.0 46.0 44.6 25.3
Manufactured Homes

1 33.2 30.1 29.1 28.9 17.8 30.6 29.7 18.7

2 34.1 31.0 30.0 29.7 18.2 31.4 30.6 19.1

3 33.6 30.6 29 .6 29.3 18.1 31.0 30.1 18.9

4 37.5 34.0 32.8 32.6 19.7 34.5 33.6 20.7

5 42.9 38.7 37.4 37.1 21.9 39.4 38.2 23.1
Camper Trailers

1 46.6 37.6 35.1 34.1 20.7 39.8 38.0 24.5

2 48.1 38.7 36.2 35.1 21.2 41.1 39.1 25.3

3 47.3 38.1 35.6 34.6 20.9 40.5 38.5 2 4.9

4 53.2 42.7 39.8 38.6 23.0 45.4 43.2 27.5

5 61.3 48.9 45.5 44.2 25.8 52.1 49.5 31.1

a Modeled overall (24

- hour) ADCs , in μ g/m 3

, were converted to ppm using the relationship ppm = μ g/m 3 x CF, where CF is a temperature

- dependent conversion

factor; the CF that was used

– 0.8147

– corresponds to an assumed temperature of 25 °C (77 °F)

.65 Table 5

- 5. Modeled ADCs (House Age 0

- 1 Years) for Preschool/School Children for Eight Emissions Scenarios, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 25.5 23.9 23.3 23.2 15.3 24.0 23.5 15.6

2 26.2 24.5 24.0 23.9 15.6 24.7 24 .1 15.9

3 25.8 24.2 23.6 23.5 15.5 24.4 23.8 15.7

4 28.6 26.7 26.1 26.0 16.7 26.9 26.2 17.0

5 32.4 30.2 29.4 29.3 18.5 30.4 29.7 18.8
Single

- family Attached Homes (Zone 1, Zone 2)

1 27.1 25.3 24.6 24.5 15.2 25.4 24.8 15.5

2 27.9 25.9 25.3 25.2 15.6 2 6.2 25.5 15.8

3 27.5 25.6 24.9 24.8 15.4 25.7 25.2 15.6

4 30.6 28.4 27.5 27.5 16.6 28.5 27.8 16.9

5 34.7 32.1 31.2 31.0 18.3 32.3 31.5 18.8
Apartments

1 33.2 30.4 29.4 29.2 16.5 30.7 29.8 17.9

2 34.2 31.2 30.2 30.1 16.9 31.6 30.6 18.4

3 33.7 30.8 29 .8 29.7 16.8 31.1 30.2 18.2

4 37.6 34.3 33.2 33.0 18.2 34.7 33.6 19.8

5 43.0 39.1 37.8 37.6 20.2 39.6 38.4 22.2
Manufactured Homes

1 28.8 26.2 25.4 25.3 16.0 26.6 25.9 16.6

2 29.7 27.0 26.1 25.9 16.3 27.4 26.6 16.9

3 29.2 26.6 25.7 25.6 16.1 27.0 26. 3 16.8

4 32.5 29.5 28.5 28.4 17.4 30.0 29.1 18.2

5 37.0 33.5 32.3 32.1 19.4 34.0 33.0 20.3
Camper Trailers

1 40.1 32.5 30.4 29.6 18.2 34.4 32.8 21.5

2 41.4 33.4 31.3 30.4 18.7 35.4 33.8 22.1

3 40.7 33.0 30.9 30.0 18.5 35.0 33.3 21.8

4 45.7 36.7 34.4 33.4 20.2 39.0 37.2 24.0

5 52.5 42.0 39.2 38.0 22.6 44.6 42.5 27.066 Table 5

- 6. Modeled ADCs (House Age 0

- 1 Years) for Non

- industry Workers for Eight Emissions Scenarios, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminat es CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 25.8 24.2 23.6 23.5 15.6 24.4 23.8 15.8

2 26.5 24.8 24.2 24.2 15.9 24.9 24.4 16.1

3 26.2 24.5 24.0 23.9 15.7 24.7 24.1 16.0

4 28.8 27.0 26.3 26.2 16.9 27.1 26.6 17.3

5 32.6 30.4 29.6 29.5 18.7 30.6 29.8 19.0
Single

- family Attached Homes (Zone 1, Zone 2)

1 27.3 25.3 24.7 24.6 15.4 25.6 24.9 15.7

2 28.0 26.0 25.3 25.3 15.7 26.2 25.6 16.1

3 27. 6 25.7 25.0 24.9 15.6 25.9 25.3 15.9

4 30.6 28.4 27.5 27.5 16.8 28.5 27.9 17.1

5 34.5 31.9 31.0 31.0 18.4 32.2 31.4 18.8
Apartments

1 33.2 30.4 29.4 29.2 16.8 30.7 29.8 18.1

2 34.1 31.2 30.2 30.1 17.1 31.5 30.6 18.5

3 33.6 30.8 29.8 29.7 16.9 31.1 30 .2 18.3

4 37.4 34.1 33.1 32.9 18.4 34.5 33.6 20.0

5 42.6 38.8 37.5 37.3 20.3 39.3 38.0 22.2
Manufactured Homes

1 28.9 26.4 25.6 25.4 16.1 26.7 26.1 16.9

2 29.7 27.0 26.2 26.1 16.5 27.5 26.7 17.2

3 29.3 26.7 25.9 25.7 16.3 27.1 26.4 17.0

4 32.5 29.5 28.6 28.4 17.7 30.0 29.2 18.4

5 36.8 33.3 32.3 32.0 19.5 33.9 32.9 20.4
Camper Trailers

1 39.8 32.4 30.4 29.6 18.4 34.3 32.8 21.6

2 41.1 33.3 31.2 30.4 18.8 35.3 33.6 22.2

3 40.4 32.9 30.8 30.0 18.7 34.8 33.2 21.8

4 45.2 36.6 34.2 33.2 20.3 38.7 36.9 24.0

5 51.7 41.6 38.9 37.7 22.6 44.2 42.0 26.967 Table 5

- 7. Modeled ADCs (House Age 0

- 1 Years) for Fabrication

- industry Workers for Eight Emissions Scenarios, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 wit h

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 69.1 65.8 65.0 65.0 35.0 66.0 65.3 35.2

2 69.7 66.5 65.7 65.6 35.3 66.6 65.8 35.5

3 69.4 66.2 65.3 65.3 3 5.1 66.3 65.5 35.4

4 72.1 68.7 67.7 67.6 36.4 68.8 67.9 36.7

5 75.9 72.0 71.0 70.9 38.0 72.3 71.3 38.5
Single

- family Attached Homes (Zone 1, Zone 2)

1 70.6 67.1 66.2 66.1 34.8 67.2 66.3 35.1

2 71.3 67.7 66.7 66.6 35.1 67.9 67.0 35.4

3 70.9 67.4 66.5 66.4 35.0 67.5 66.6 35.3

4 73.8 70.0 69.0 68.9 36.2 70.2 69.3 36.5

5 77.8 73.7 72.5 72.3 37.8 73.9 72.8 38.3
Apartments

1 76.4 72.0 70.8 70.6 36.2 72.3 71.2 37.6

2 77.4 72.8 71.6 71.5 36.6 73.2 72.0 38.0

3 76.9 72.4 71.2 71.1 36.3 72.8 71.6 37.7

4 8 0.7 75.9 74.5 74.3 37.8 76.2 75.0 39.4

5 85.9 80.5 78.9 78.7 39.8 80.9 79.5 41.6
Manufactured Homes

1 72.2 68.0 67.0 66.8 35.6 68.4 67.5 36.3

2 73.0 68.8 67.6 67.5 35.9 69.2 68.2 36.6

3 72.6 68.4 67.3 67.1 35.8 68.8 67.8 36.4

4 75.8 71.2 70.0 69.8 37 .1 71.6 70.6 37.8

5 80.1 75.0 73.7 73.4 38.9 75.5 74.3 39.8
Camper Trailers

1 83.1 74.1 71.8 71.0 37.8 75.9 74.1 41.0

2 84.3 75.0 72.7 71.8 38.3 76.9 75.1 41.6

3 83.7 74.5 72.3 71.4 38.0 76.4 74.6 41.3

4 88.5 78.2 75.6 74.6 39.7 80.4 78.4 43.4

5 95. 0 83.3 80.3 79.2 42.0 85.9 83.5 46.468 Table 5

- 8. Modeled ADCs (House Age 0

- 1 Years) for Retirees for Eight Emissions Scenarios, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam

. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 31.4 29.3 28.6 28.5 18.2 29.6 28.8 18.6

2 32.3 30.1 29.4 29.3 18.7 30.4 29.7 19.0

3 31.9 29.7 29.0 28.9 18.4 30.0 29.2 18.7

4 35.5 33.1 32.2 32.1 20.0 33.3 32.5 20.4

5 40.5 37.6 36.6 36.4 22.3 37.9 36.9 22.8
Single

- family Attached Homes (Zone 1, Zone 2)

1 33.2 30.7 29.9 29.7 17.8 31.0 30.2 18.3

2 34.1 31.6 30.7 30.6 18.2 31.9 31.0 18.7

3 33.6 31.2 30.3 30.2 18.1 31.4 30.6 18.5

4 37.5 34.7 33.7 33.6 19.7 35.0 34.1 20.2

5 42.9 39.5 38.4 38.2 21.9 39.8 38.8 22.5
Apartments

1 41.1 37.4 36.2 36.0 19.8 37.9 36.7 21.6

2 42.3 38.5 37.3 37.1 20.2 39.0 37.8 22.1

3 41.7 38.0 36.7 36.6 20.0 38.5 37.3 21.8

4 46.7 42.5 41.1 40.8 21.9 43.0 41. 7 24.0

5 53.7 48.7 47.0 46.8 24.5 49.3 47.7 27.0
Manufactured Homes

1 35.4 32.1 31.0 30.8 19.0 32.7 31.7 19.8

2 36.4 33.1 31.9 31.7 19.4 33.6 32.7 20.3

3 35.9 32.6 31.5 31.3 19.1 33.2 32.2 20.0

4 40.1 36.3 35.0 34.8 20.9 36.9 35.8 22.0

5 45.9 41.4 4 0.0 39.7 23.4 42.1 40.9 24.6
Camper Trailers

1 49.9 40.2 37.5 36.4 22.0 42.6 40.7 26.2

2 51.5 41.4 38.6 37.5 22.6 44.0 41.9 26.9

3 50.8 40.8 38.0 37.0 22.2 43.3 41.2 26.6

4 57.1 45.7 42.6 41.3 24.4 48.6 46.2 29.4

5 65.8 52.5 48.8 47.3 27.5 55.8 53.0 33.369 Table 5

- 9. Modeled ADCs (House Age 0

- 1 Years) for Part

- time Workers for Eight Emissions Scenarios, ppb

– New

- home Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 27.2 25.4 24.8 24.8 16.1 25.6 25.0 16.4

2 27.9 26.2 25.5 25.4 16.5 26.3 25.7 16.7

3 27.6 25.8 25.2 25.1 16.3 26.0 25.4 16.5

4 30.6 28.6 27.9 27.8 17.7 28.8 28. 1 18.0

5 34.7 32.3 31.5 31.4 19.6 32.6 31.8 20.0
Single

- family Attached Homes (Zone 1, Zone 2)

1 28.8 26.7 26.0 25.9 15.9 27.0 26.2 16.2

2 29.6 27.5 26.7 26.6 16.2 27.7 27.0 16.6

3 29.2 27.1 26.4 26.3 16.1 27.3 26.6 16.5

4 32.4 30.1 29.2 29.1 17.4 30 .3 29.5 17.8

5 36.9 34.1 33.1 33.0 19.2 34.4 33.5 19.7
Apartments

1 35.4 32.3 31.3 31.1 17.4 32.7 31.7 18.9

2 36.4 33.2 32.2 32.0 17.8 33.6 32.7 19.4

3 35.9 32.8 31.7 31.5 17.6 33.2 32.2 19.1

4 40.1 36.6 35.4 35.1 19.2 37.0 35.8 20.9

5 45.9 41.7 40. 3 40.1 21.3 42.2 40.9 23.5
Manufactured Homes

1 30.6 27.9 27.0 26.8 16.8 28.3 27.5 17.5

2 31.5 28.7 27.7 27.5 17.1 29.1 28.3 17.9

3 31.0 28.3 27.4 27.1 16.9 28.7 27.9 17.7

4 34.6 31.4 30.3 30.1 18.4 31.9 31.0 19.3

5 39.4 35.6 34.5 34.1 20.4 36.3 35.2 21.4
Camper Trailers

1 42.8 34.5 32.3 31.4 19.3 36.7 35.0 22.8

2 44.2 35.6 33.3 32.3 19.7 37.8 36.0 23.4

3 43.5 35.1 32.8 31.9 19.6 37.2 35.5 23.1

4 48.8 39.2 36.6 35.5 21.3 41.6 39.7 25.5

5 56.1 44.9 41.8 40.6 24.0 47.7 45.4 28.870 5.2 RENOVATION CASE

The same set of results as shown in the previous section for the new

- home case is provided here

for the renovation case. Table 5

- 1 0 lists initial modeled “steady

- state” formaldehyde

concentrations for residential renovation. The initial concentration s are listed for each of eight

emissions scenarios /analytical options (columns in the table), five housing types (sub

- headings
within the table), and five climate zones (table rows). Although the formaldehyde concentrations

are lower in this case, t he same general patterns as for the new

- ho m e case are apparent in the

table:

• The highest modeled concentrations are for camper trailers

• Within each housing type, the highest concentrations are in the South (climate zone 5)

• Among the analytical options , the lowest concentrations occur for the case where CWPs

are at emission levels that meet no

- added

- formaldehyde (NAF) standards , whether laminates are regulated or not.

Figure 5

- 3, wherein the initial modeled concentrations are averaged across climate zones, shows

mo re clearly the patterns of results across emissions scenarios/analytical options and housing

types. Although the concentrations are lower for renovation than for new residential construction, the scale in Figure 5

- 3 was kept the same as in Figure 5

- 1 to en able direct comparisons.

Figure 5

- 3

. Modeled Initial Formaldehyde Concentrations by Emissions

Scenario /Analytical Option and Housing Type

– Renovation Case

. * Results shown are

for Zone 1 of these

two

- zone structures71 Table 5

- 1 0 . Modeled Initial Residential Concentrations for Eight Emission s Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 20.0, 24.6 18.2 , 21.8 17.7, 21.0 17.5, 20.7 11.0, 12.3 18.5, 22.4 18.0, 21.7 11.6, 13.2

2 20.4, 25.3 18.6, 22.4 18.1, 21.5 17.9, 21.3 11.2, 12.4 18.9, 23.0 18.5, 22.2 11.7, 13.4

3 20.2, 25.0 18.4, 22.1 17.9, 21.3 17.7, 21.0 11.1, 12.4 18.7, 22.7 18.3, 22.0 11.7, 13.3

4 22.1, 27.6 20.0, 24.3 19.4, 23.3 19.3, 23.0 11.7, 13.1 20.4, 24.9 19.9, 24.1 12.3, 14.2

5 24.7, 31.2 22.3, 27.3 21.5, 26.1 21.4, 25.8 12.4, 14.1 22.7, 28.1 22.1, 27.1 13.1, 15.4
Single

- family Attached Homes (Zone 1, Zone 2)

1 25.0, 32.1 22.8, 28.7 22. 1, 27.6 22.0, 27.4 12.4, 14.3 23.1, 29.2 22.5, 28.3 13.0, 15.2

2 25.7, 33.0 23.4, 29.5 22.7, 28.4 22.5, 28.2 12.6, 14.5 23.7, 30.1 23.1, 29.2 13.2, 15.5

3 25.4, 32.6 23.1, 29.1 22.4, 28.1 22.3, 27.8 12.5, 14.4 23.5, 29.7 22.8, 28.8 13.1, 15.4

4 28.0, 36 .3 25.4, 32.3 24.6, 31.1 24.5, 30.8 13.3, 15.4 25.8, 33.0 25.1, 31.9 13.9, 16.5

5 31.7, 41.5 28.6, 36.8 27.7, 35.3 27.5, 35.0 14.3, 16.9 29.1, 37.6 28.3, 36.3 15.0, 18.2
Apartments

1 37.5 33.5 32.2 31.9 15.6 34.1 33.0 16.6

2 38.7 34.5 33.2 32.9 15.9 35 .1 34.0 17.0

3 38.2 34.1 32.7 32.5 15.8 34.7 33.5 16.8

4 42.7 38.0 36.5 36.2 17.0 38.7 37.4 18.2

5 49.0 43.4 41.7 41.3 18.7 44.3 42.7 20.1
Manufactured Homes

1 30.2 25.6 24.3 23.8 13.8 26.7 25.6 15.6

2 31.1 26.3 25.0 24.5 14.1 27.4 26.4 16.0

3 30.7 26.0 24.7 24.2 14.0 27.1 26.0 15.8

4 34.1 28.7 27.2 26.7 14.9 30.0 28.8 17.0

5 38.9 32.5 30.7 30.1 16.3 34.0 32.6 18.7
Camper Trailers

1 48.5 38.6 36.1 34.9 19.8 41.2 39.3 24.1

2 50.1 39.9 37.2 36.0 20.3 42.5 40.5 24.8

3 49.4 39.3 36.7 35.5 20.1 41.9 40.0 24.5

4 55.5 44.0 41.0 39.7 21.9 47.0 44.8 27.0

5 64.1 50.6 47.0 45.4 24.5 54.1 51.4 30.572 Table 5

- 11, arranged in the same manner as Table 5

- 10, lists the average daily concentration (ADC) within each housing type during the first year (i.e., hou se age 0

- 1 years) following construction. The patterns in these two tables are very similar to one another ; for example, in both tables the highest formaldehyde levels are in camper trailers and in the South

.

Table 5

- 12 illustrates the decline in formalde hyde concentrations over the 10

- year period that was modeled, using ADCs for manufactured homes in climate zone 3 (see Figure 4

- 9 for a depiction of U.S. climate zones). As with the new

- ho m e case, the concentrations 10 years after

construction due to CWP e missions are about one percent of their initial values. As evident in the

bottom row of the table, the formaldehyde levels have nearly reached background (7.5 ppb) at

this time.

Tables 5

- 13 through 5

- 18 list overall ADCs reflecting combined in

- home and away

- from

- home exposure (i.e., “around

- the

- clock” exposure) during the first year following construction for

infants, children, non

- industry workers, fabrication

- industry workers, retirees and part

- time

workers

. Differences across the exposure groups for t his case are similar in magnitude to those

for the new

- home case, and fabrication

- industry workers again have the highe st overall exposure

due to their elevated at

- work exposure. Such differences can be seen more clearly in Figure 5

- 4,

wherein the ADCs for each exposure group are averaged across housing types and climate zone s

.

Figure 5

- 4. Modeled ADCs (House Age 0

- 1 Years) for Exposure Groups by Emissions

Scenario /Analytical Option and Housing Type

– Renovation Case.73 Table 5

- 11 . Modeled Residential ADC s (H ouse Age 0

- 1 Years) for Eight Emission s Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- f

amily Detached Homes (Zone 1, Zone 2)

1 17.5, 21.2 16.1, 19.0 15.7, 18.3 15.5, 18.1 10.4, 11.3 16.3, 19.4 15.9, 18.9 10.8, 12.0

2 17.9, 21.8 16.4, 19.4 15.9, 18.7 15.8, 18.5 10.5, 11.4 16.7, 19.9 16.3, 19.3 10.9, 12.2

3 17.7, 21.5 16.3, 19.2 15.8, 18.5 15.7, 18.4 10.4, 11.4 16.5, 19.6 16.1, 19.1 10.8, 12.2

4 19.2, 23.6 17.5, 21.0 17.0, 20.2 16.9, 19.9 10.8, 11.9 17.8, 21.5 17.4, 20.8 11.3, 12.8

5 21.3, 26.5 19.3, 23.3 18.8, 22.4 18.6, 22.2 11.4, 12.8 19.7, 24.0 19.2, 23.2 12.0, 13.8
Single

- family Atta ched Homes (Zone 1, Zone 2)

1 21.5, 27.1 19.8, 24.5 19.2, 23.6 19.1, 23.5 11.4, 12.9 20.0, 24.9 19.5, 24.2 11.9, 13.7

2 22.0, 27.9 20.2, 25.1 19.6, 24.3 19.6, 24.1 11.6, 13.1 20.5, 25.6 20.0, 24.9 12.1, 13.9

3 21.8, 27.6 20.0, 24.8 19.5, 24.0 19.3, 23.7 11.5, 13.0 20.3, 25.3 19.8, 24.6 12.0, 13.8

4 23.9, 30.6 21.9, 27.4 21.2, 26.4 21.1, 26.2 12.1, 13.9 22.2, 27.9 21.6, 27.1 12.7, 14.8

5 26.9, 34.6 24.4, 30.9 23.6, 29.8 23.5, 29.5 13.0, 15.0 24.8, 31.6 24.1, 30.6 13.5, 16.0
Apartments

1 31.5 28.3 27.3 27.1 14.0 28.8 27.9 14.8

2 32.5 29.1 28.1 27.8 14.2 29.6 28.7 15.1

3 32.0 28.7 27.7 27.5 14.2 29.2 28.3 15.0

4 35.6 31.9 30.7 30.5 15.1 32.5 31.4 16.0

5 40.7 36.3 34.9 34.6 16.5 36.9 35.7 17.6
Manufactured Homes

1 25.7 22.0 21.0 20.6 12.6 22.8 22.0 14.0

2 26.4 22.5 21.5 21.1 12.8 23.4 22.6 14.2

3 26.1 22.3 21.3 20.8 12.7 23.2 22.4 14.2

4 28.8 24.5 23.3 22.8 13.5 25.5 24.5 15.2

5 32.6 27.5 26.1 25.6 14.5 28.7 27.6 16.5
Camper Trailers

1 40.3 32.4 30.4 29.5 17.3 34.5 32.9 20.8

2 41.6 33.4 31.3 3 0.3 17.7 35.6 34.0 21.3

3 41.1 33.0 30.9 29.9 17.5 35.1 33.5 21.1

4 46.0 36.8 34.4 33.3 19.0 39.1 37.3 23.1

5 52.9 42.0 39.1 37.9 21.1 44.8 42.7 25.974 Table 5

- 12. Modeled Residential ADCs by House Age for Manufactured Home in Climate Zone 3, by Emissi on Scenario, ppb

– Renovation Case

House Age (years) at Start of Exposure Period Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.

0 26.1 22.3 2 1.3 20.8 12.7 23.2 22.4 14.2

1 19.2 16.8 16.2 15.9 10.8 17.4 16.8 11.7

2 14.9 13.4 13.0 12.8 9.6 13.7 13.4 10.1

3 12.2 11.2 10.9 10.9 8.8 11.4 11.2 9.2

4 10.4 9.8 9.7 9.6 8.3 10.0 9.8 8.5

5 9.3 8.9 8.9 8.9 8.1 9.0 8.9 8.1

6 8.7 8.5 8.4 8.4 7.8 8.5 8.5 7.9

7 8.2 8.1 8.1 8.1 7.7 8.1 8.1 7.7

8 8.0 7.9 7.8 7.8 7.6 7.9 7.9 7.6

9 7.8 7.7 7.7 7.7 7.6 7.7 7.7 7.6

10 7.6 7.6 7.6 7.6 7.6 7.6 7.6 7.675 Table 5

- 13 . Modeled ADC s (House Age 0

- 1 Years) for Infants for Eight Emissions Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 15.2 13.9 13.5 13.4 9.1 14.2 13.9 9.5

2 15.5 14.2 13.8 13.7 9.2 14.4 14.1 9.6

3 15.3 14.1 13.7 13.6 9.1 14.3 13.9 9.5

4 16.5 15.1 14.7 14.6 9.5 15.4 15.0 9.9

5 18.2 16.5 16.1 15.9 9.9 16.9 16.4 10.5
Single

- family Attached Homes (Zone 1, Zone 2)

1 18.7 17.1 16.6 16.5 10.0 17.4 16.9 10.4

2 19.1 17.5 17.0 16.9 10.2 17.8 17.3 10.6

3 18.8 17.3 16.8 16.7 10.1 17.5 17.1 10.5

4 20.6 18.8 18.2 18.1 10.6 19.1 18.6 11.1

5 23.0 20.9 20.2 20.1 11.2 21.2 20.6 11.8
Apartments

1 25.3 22.7 22.0 21.8 11.7 23.1 22.4 12.4

2 25.9 23.4 22.6 22.3 11.9 23.7 23.0 12.5

3 25.6 23.1 22.2 22.1 11.8 23.5 22.7 12.5

4 28.3 25.4 24.5 24.3 12.5 25.8 25.0 13.3

5 32.0 28.6 27.5 27.3 13.5 29.2 28.2 14.4
Manufactured Homes

1 20.8 17.9 17.1 16.9 10.7 18.6 17.9 11.7

2 21.3 18.3 17.5 17.2 10.8 19.0 18.3 11.9

3 21.0 18.1 17.4 17.0 10.7 18.8 18.2 11.8

4 23.1 19.7 18.8 18.5 11.2 20.5 19.8 12.5

5 25.9 22.0 20.9 20.5 12.1 22.9 22.0 13.5
Camper Trailers

1 31.9 25.9 24.4 23.6 14.3 27.5 26.3 16.9

2 32.9 26.6 25.0 24.3 14.6 28.3 27.0 17.4

3 32.4 26.3 24.7 24.0 14.4 27.9 26.6 17.1

4 36.2 29.1 27.2 26.5 15.6 31.0 29.6 18.7

5 41.2 33.0 30.8 29.8 17.0 35.1 33.5 20.776 Table 5

- 14. Modeled ADC s (House Age 0

- 1 Years) for Preschool/School Children for Eight Emissions Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Lamina tes CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 13.8 12.6 12.3 12.2 8.6 12.9 12.5 8.9

2 14.0 12.9 12.5 12.5 8.6 13.0 12.8 9.0

3 13.9 12.8 12.5 12.4 8.6 13.0 12.6 9.0

4 14.9 13.6 13.3 13.1 8.9 13.9 13.5 9.3

5 1 6.3 14.8 14.3 14.3 9.3 15.1 14.7 9.7
Single

- family Attached Homes (Zone 1, Zone 2)

1 16.6 15.3 14.9 14.8 9.4 15.5 15.2 9.7

2 17.0 15.6 15.2 15.1 9.5 15.8 15.4 9.8

3 16.8 15.5 15.0 14.9 9.4 15.6 15.3 9.8

4 18.2 16.7 16.2 16.1 9.8 16.9 16.5 10.2

5 20.3 18.4 17.8 17.8 10.3 18.7 18.2 10.8
Apartments

1 22.2 20.0 19.4 19.3 10.8 20.4 19.8 11.3

2 22.8 20.6 19.9 19.7 10.9 20.9 20.3 11.5

3 22.5 20.4 19.6 19.5 10.8 20.6 20.0 11.4

4 24.8 22.3 21.5 21.3 11.5 22.6 22.0 12.1

5 27.9 25.0 24.1 23.9 12.3 25.4 24.6 13.0
Manufactured Homes

1 18.5 16.1 15.3 15.1 9.9 16.5 16.1 10.8

2 18.9 16.4 15.6 15.4 10.0 16.9 16.4 10.9

3 18.7 16.2 15.5 15.2 9.9 16.8 16.2 10.8

4 20.4 17.6 16.8 16.5 10.4 18.2 17.6 11.5

5 22.7 19.5 18.5 18.2 11.1 20.2 19.5 12. 3
Camper Trailers

1 27.9 22.7 21.4 20.9 13.0 24.0 23.1 15.2

2 28.7 23.3 21.9 21.3 13.2 24.7 23.6 15.5

3 28.3 23.1 21.7 21.1 13.0 24.4 23.4 15.3

4 31.4 25.4 23.9 23.1 13.9 27.0 25.7 16.5

5 35.7 28.7 26.8 26.0 15.2 30.5 29.1 18.377 Table 5

- 15. Modeled ADCs (House Age 0

- 1 Years) for Non

- industry Workers for Eight Emissions Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminate s CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 14.7 13.5 13.1 13.0 9.1 13.7 13.4 9.5

2 15.0 13.7 13.4 13.3 9.2 13.9 13.6 9.5

3 14.8 13.6 13.3 13.2 9.2 13.9 13.5 9.5

4 15.9 14.5 14.1 14.0 9.5 14.7 14.3 9.9

5 17. 3 15.7 15.2 15.1 9.9 16.0 15.6 10.3
Single

- family Attached Homes (Zone 1, Zone 2)

1 17.6 16.2 15.8 15.7 9.9 16.4 16.1 10.3

2 18.0 16.5 16.1 16.0 10.0 16.8 16.4 10.4

3 17.8 16.4 16.0 15.8 10.0 16.6 16.2 10.3

4 19.3 17.7 17.2 17.0 10.4 17.9 17.4 10.8

5 21.3 19.4 18.8 18.7 10.9 19.7 19.1 11.4
Apartments

1 22.5 20.4 19.8 19.6 11.2 20.7 20.1 11.7

2 23.1 20.9 20.2 20.0 11.3 21.2 20.6 11.9

3 22.8 20.7 20.0 19.9 11.2 20.9 20.4 11.8

4 25.0 22.6 21.8 21.7 11.8 22.9 22.2 12.5

5 28.0 25.2 24.3 24.1 12.6 2 5.6 24.8 13.4
Manufactured Homes

1 18.9 16.5 15.8 15.6 10.3 17.0 16.5 11.2

2 19.3 16.8 16.1 15.9 10.4 17.4 16.9 11.3

3 19.1 16.6 16.0 15.7 10.3 17.2 16.7 11.2

4 20.8 18.0 17.2 16.9 10.8 18.6 18.0 11.9

5 23.1 19.8 18.9 18.6 11.4 20.5 19.8 12.7
Camper Trailers

1 27.9 23.0 21.7 21.1 13.3 24.3 23.3 15.4

2 28.8 23.5 22.2 21.6 13.5 24.8 23.9 15.7

3 28.4 23.3 21.9 21.3 13.4 24.6 23.5 15.6

4 31.4 25.6 24.0 23.4 14.3 27.0 25.9 16.8

5 35.5 28.7 26.9 26.2 15.5 30.5 29.1 18.478 Table 5

- 16. Modeled ADCs (Hou se Age 0

- 1 Years) for Fabrication

- industry Workers for Eight Emissions Scenarios, ppb

– Ren ovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 57.9 55.2 54.6 54.5 28.6 55.4 54.8 28.9

2 58.3 55.4 54.7 54.7 28.6 55.6 55.1 29.0

3 58.1 55.2 54.7 54.6 28.6 55.5 54.9 28.9

4 59.1 56.1 55.5 55.4 28.8 56.4 55.8 29.2

5 60.5 57.4 56 .6 56.5 29.2 57.6 56.9 29.7
Single

- family Attached Homes (Zone 1, Zone 2)

1 60.9 57.8 57.2 57.1 29.3 58.1 57.4 29.7

2 61.3 58.2 57.5 57.4 29.5 58.4 57.8 29.8

3 61.1 58.0 57.4 57.3 29.4 58.3 57.6 29.7

4 62.6 59.3 58.6 58.5 29.8 59.6 58.9 30.2

5 64.6 6 1.1 60.3 60.1 30.4 61.3 60.6 30.8
Apartments

1 65.8 62.1 61.2 61.0 30.6 62.4 61.5 31.1

2 66.3 62.6 61.6 61.5 30.7 62.9 62.0 31.3

3 66.1 62.3 61.4 61.3 30.6 62.7 61.8 31.2

4 68.3 64.2 63.2 63.1 31.3 64.6 63.6 31.9

5 71.3 66.8 65.7 65.5 32.1 67.3 66.2 32.8
Manufactured Homes

1 62.2 58.2 57.3 57.0 29.7 58.7 57.9 30.6

2 62.6 58.5 57.5 57.3 29.8 59.1 58.3 30.8

3 62.4 58.3 57.4 57.2 29.7 58.9 58.1 30.7

4 64.0 59.6 58.7 58.3 30.2 60.3 59.4 31.3

5 66.3 61.4 60.3 60.0 30.9 62.2 61.2 32.1
Camper Trailers

1 71.2 64.7 63.1 62.6 32.7 65.9 64.7 34.8

2 72.0 65.3 63.6 63.1 32.9 66.6 65.3 35.1

3 71.6 64.9 63.4 62.8 32.8 66.2 65.0 35.0

4 74.6 67.2 65.4 64.8 33.6 68.7 67.3 36.2

5 78.8 70.4 68.4 67.5 34.9 72.1 70.6 37.979 Table 5

- 17 . Modeled ADC s (House Age 0

- 1 Years) for Retirees for Eight Emissions Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 16.8 15.2 14.7 14.7 9.7 15.6 15.2 10.2

2 17.1 15.6 15.1 14.9 9.8 15.8 15.4 10.3

3 16.9 15.4 14.9 14.8 9.7 15.6 15.3 10.2

4 18.4 16.6 16.1 15.9 10.1 16.9 16.5 10.7

5 20.4 18.2 17.7 17.4 10.7 18.7 18.2 11.3

Sin gle

- family Attached Homes (Zone 1, Zone 2)

1 20.9 19.1 18.5 18.3 10.8 19.3 18.8 11.3

2 21.3 19.5 18.9 18.7 10.9 19.8 19.2 11.5

3 21.1 19.2 18.7 18.6 10.8 19.6 19.1 11.4

4 23.1 21.0 20.4 20.2 11.4 21.3 20.8 12.0

5 26.0 23.5 22.6 22.5 12.2 23.9 23.2 12. 9
Apartments

1 26.9 24.2 23.3 23.1 12.3 24.6 23.9 13.0

2 27.6 24.8 24.0 23.8 12.5 25.3 24.4 13.2

3 27.2 24.5 23.6 23.5 12.4 24.9 24.1 13.1

4 30.1 27.0 26.1 25.8 13.2 27.5 26.6 14.0

5 34.2 30.6 29.3 29.2 14.3 31.0 30.1 15.2
Manufactured Homes

1 22.0 19.0 18.1 17.8 11.2 19.6 19.0 12.3

2 22.6 19.4 18.5 18.2 11.3 20.1 19.4 12.5

3 22.3 19.1 18.3 18.0 11.2 19.9 19.2 12.5

4 24.5 20.9 20.0 19.6 11.8 21.8 20.9 13.2

5 27.5 23.4 22.2 21.8 12.6 24.4 23.4 14.3
Camper Trailers

1 34.1 27.6 25.9 25.2 15.1 29. 3 28.0 17.9

2 35.1 28.4 26.6 25.8 15.4 30.1 28.8 18.3

3 34.6 28.0 26.2 25.5 15.2 29.7 28.4 18.2

4 38.6 31.0 29.0 28.2 16.5 33.0 31.5 19.8

5 44.2 35.2 32.9 31.9 18.1 37.6 35.8 22.080 Table 5

- 18. Modeled ADCs (House Age 0

- 1 Years) for Part

- time Workers f or Eight Emissions Scenarios, ppb

– Renovation Case

Climate

Zone Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.
Single

- family Detached Homes (Zone 1, Zone 2)

1 14.8 13.5 13.2 13.1 9.0 13.8 13.4 9.3

2 15.1 13.8 13.4 13.3 9.0 14.0 13.7 9.5

3 15.0 13.7 13.3 13.2 9.0 13.9 13.6 9.4

4 16.1 14.7 14.3 14.1 9.3 14.9 14.6 9.8

5 17.8 16.1 15.5 15.4 9.7 16.3 15.9 10.3
Single

- family Attached Homes (Zone 1, Zone 2)

1 18.1 16.6 16.1 16.1 9.9 16.9 16.5 10.3

2 18.6 16.9 16.5 16.4 9.9 17.2 16.8 10.3

3 18.3 16.8 16.3 16.2 9.9 17.0 16.6 10.3

4 20.0 18.2 17.7 17.6 10.3 18.5 18.0 10.8

5 22.2 20.2 19.6 19.5 11.0 20.5 20.0 11.5
Apartments

1 23.5 21.2 20.5 20.4 11.2 21.6 20.9 11.7

2 24.1 21.8 21.0 20.9 11.4 22.1 21.4 12.0

3 23.8 21.5 20.8 20.6 11.2 21.8 21.2 11.9

4 26.2 23.6 22.8 22.6 12.0 24.0 23.3 12.6

5 29.7 26.6 25.6 25.3 12.9 27.0 26.2 13.6
Manufactured Homes

1 19.5 16.9 16.1 15. 9 10.2 17.4 16.9 11.2

2 19.9 17.2 16.5 16.2 10.3 17.8 17.3 11.4

3 19.6 17.0 16.3 16.1 10.3 17.6 17.0 11.3

4 21.5 18.5 17.7 17.4 10.8 19.2 18.5 12.0

5 24.0 20.5 19.6 19.2 11.5 21.3 20.5 12.9
Camper Trailers

1 34.1 24.1 22.6 22.0 13.5 25.5 24.4 15.9

2 35.1 24.7 23.2 22.6 13.8 26.2 25.1 16.3

3 34.6 24.4 23.0 22.3 13.6 25.8 24.8 16.1

4 38.6 27.0 25.3 24.5 14.7 28.6 27.4 17.4

5 44.2 30.5 28.5 27.6 16.0 32.4 31.0 19.381 

### Section 6

DISCUSSION

6.1 APPROACH AND RESULTS

6.1.1 Summary of Approach

A model ing

- based approach was chosen for the exposure assessment to accommodate the number of situations of potential interest and the limited amount of current or recent monitoring

data available. Both new

- construction, or new

- home, and renovation cases were exa mined. As a general rule, expected or average values were used for model inputs, as opposed to a range or distribution of values. Variability was introduced for certain input parameters expected to have a significant influence on the modeling results. Seve n alternative emissions scenarios ( analytical options) were modeled along with a baseline (2013) scenario. Model runs were made for five different structure types, in five different climates zones, for each emissions scenario /analytical option . Six exposur e groups

– infants, children, non

- industry workers, fabrication industry workers, retirees, and part

- time workers

– were included in the assessment, which estimated not only at

- home but also away

- from

- home formaldehyde exposure in the form of an average da ily concentration (ADC) reflecting “around the clock” exposure.

6 .1.2 S ummary o f Modeled Initial Formaldehyde Concentrations in Homes

For the baseline 2013 scenario, modeled formaldehyde level s (initial values, representing the “steady state” condition shortly after installation of new PWPs) had the following ranges across climate zones for the five structure types that were included in the assessment:

• S ingle

- family d etached homes

– 43 to 6 0 ppb (new house); 20 to 31 ppb (renovation)

• S ingle

- family at tach ed homes

– 47 to 62 ppb (new house); 25 to 42 ppb (renovation)

• Apartments

– 59 to 79 ppb (new house); 38 to 49 ppb (renovation)

• Manufactured homes

– 50 to 67 ppb (new house); 30 to 39 ppb (renovation)

• Camper trailers

– 72 to 97 ppb (new house); 49 to 64 pp b (renovation)

The modeled concentrations were higher, and the ranges somewhat broader, for the new

- ho me case than for the renovation case. As noted in Section 4.4.8, using current emission levels to

estimate emission levels in 2013 would not accurately re flect the 2013 baseline, because m any
CWP manufacturers are modifying their production technology and raw materials to achieve compliance with Phase 2 of the CARB ATCM. Instead, baseline emission levels we re estimated

on the basis of responses to a survey question about emission levels that mills planned to achiev e within the next three years.

Figure 6

- 1 depicts the initial modeled indoor concentrations at baseline and under the seven analytical options for both the new

- ho me and the renovation cases, with results averaged across housing types and climate zones. Figure 6

- 2 indicates the concentration reduction for each option , relative to baseline, for the same two cases. In either case, the reduction clearly is the greatest for the NAF option , whether lamin ates are regulated or not.8 2 Figure 6

- 1. Modeled Initial Formaldehyde Concentration by Emissions Scenario /Analytical
Option for New

- home and Renovation Cases.

Figure 6

- 2

. Reduction in Modeled Initial Formaldehyde Concentration , Relat ive to

Baseline, by Alternate Emissions Scenario for New

- home and Renovation Cases. 0 10 20 30 40 50 60 70 80Initital Formaldehyde Concentration, ppb

New

- home Case

Renovation Case83 Figure 6

- 3, with the concentration reductions expressed in percentage terms, again shows the substantially greater reduction for the NAF option . Table 6

- 1 lists some of th e underlying details, with the percent differences shown separately by housing type. The percent reductions clearly are greatest for camper trailers, but the advantage of the NAF option relative to the other analytical options is not quite as great for thi s structure type

. The percent reductions are somewhat greater for apartments and manufactured homes than for single

- family attached and

detached homes.

Figure 6

- 3

. Percent Reduction in Modeled Initial Formaldehyde Concentration , Relative to
Baseline, by Alternate Emissions Scenario for New

- home and Renovation Cases.84 Table 6

- 1. Percent Reduction in Initial Formaldehyde Concentration , Relative to Baseline, by Alternate Emissions Scenario and Housing Type for New

- home and Renovation Cases

Housing

Type CAR B1

Incl.

Laminates CARB2

Incl.

Laminates CARB2

with Lam.

@ NAF CARB

NAF Incl.

Lam inates CARB1

Excl.

Laminates CARB2

Excl.

Laminates CARB

NAF Excl.

Lam inates

New

- home Case

SF Detached

Homes 6.7% 9.2% 9.4% 44.9% 6.2% 8.5% 44.0%

SF Attached

Hom es 7.5% 10.2% 10.5% 49.0% 6.8% 9.4% 47.9%

Apartments 9.4% 12.6% 13.1% 55.1% 8.2% 11.2% 50.5%

Manufactured

Homes 9.9% 13.1% 13.8% 49.9% 8.3% 11.1% 47.2%

Camper

Trailers 20.6% 26.1% 28.4% 58.8% 15.3% 19.6% 50.0%

Renovation Case

SF Detached

Homes 9.2% 11.9% 12.7% 46.6% 7.6% 9.9% 43.8%

SF Attached

Homes 9.2% 12.0% 12.5% 52.1% 7.8% 10.3% 49.8%

Apartments 11.0% 14.5% 15.2% 59.7% 9.3% 12.4% 57.0%

Manufactured

Homes 15.7% 20.1% 21.6% 55.7% 12.0% 15.5% 49.6%

Camper

Trailers 20.6% 2 6.0% 28.4% 60.2% 15.3% 19.3% 51.1%

6.1.3 Summary of Modeled ADCs for Exposure Groups

For the baseline 2013 scenario, modeled ADCs for the first year immediately following new construction or renovation had the following ranges across structure types fo r the six exposure groups that were included in the assessment:

• Infants

– 32 to 51 ppb (new house); 16 to 35 ppb (renovation)

• Children

– 28 to 44 ppb (new house); 15 to 3 0 ppb (renovation)

• Non

- industry workers

– 28 to 44 ppb (new house); 15 to 30 ppb (reno vation)

• Fabrication industry workers

– 72 to 87 ppb (new house); 59 to 73 ppb (renovation)

• Retirees

– 34 to 55 ppb (new house); 18 to 37 ppb (renovation)

• Part

- time workers

– 29 to 47 ppb (new house); 15 to 33 ppb (renovation)

The ranges listed for each exp osure group are across housing types

, based on averages across

climate zones within each type

. As with the initial modeled formaldehyde concentrations, exposures are higher for new construction than for renovation. The range of exposures (ADCs)

within each group is 15

- 25 ppb

, for both the new

- ho me and renovation cases . Individuals living in single

- family detached homes have the lowest modeled exposures and those living in camper trailers have the highest. The much higher overall/total exposures for workers in the fabrication industry are due to their elevated at

- work exposures.85 Table 6

- 2 lists the ADCs for each exposure group at baseline and under the seven analytical options for both the new

- ho me and the renovation cases, with results averaged across hous ing types and climate zones. The reduction in ADCs is the greatest for the NAF option , whether laminates are regulated or not. The higher reductions for the NAF option , on the order of 50 percent, can be seen more clearly in Figures 6

- 4 (new

- ho me case) and 6

- 5 (renovation case), wherein percentage reductions relative to baseline are shown.

Table 6

- 2

. Average Modeled ADC (House Age 0

- 1 Years) by Exposure Group and Emissions Scenario for New

- ho m e and

Renovation Cases , ppb

Exposure

Group Baseline CARB1 Incl.

Laminates CARB2 Incl.

Laminates CARB2 with

Lam. @ NAF CARB NAF

Incl. Lam. CARB1 Excl.

Laminates CARB2 Excl.

Laminates CARB NAF

Excl. Lam.

New

- home Case

Infants 39.1 34.7 33.4 33.0 19.6 35.5 34.4 21.2

Children 33.8 30.1 29.0 28.7 17.4 30.8 29.8 18.7

N

on

- industry Workers 33.8 30.1 29.0 28.8 17.6 30.8 29.8 18.8

Fabrication

Workers 77.1 71.8 70.4 70.1 37.0 72.4 71.2 38.3

Retirees 41.9 37.2 35.7 35.3 20.9 38.0 36.7 22.6

Part

- time Workers 36.0 32.1 30.8 30.6 18.3 32.8 31.8 19.7

Renovation Case

Infants 24.2 21.0 20.1 19.8 11.7 21.7 21.0 12.9

Children 21.3 18.6 17.8 17.6 10.8 19.1 18.6 11.7

Non

- industry Workers 21.8 19.1 18.4 18.2 11.2 19.7 19.1 12.1

Fabrication

Workers 65.1 60.8 59.8 59.6 30.6 61.3 60.5 31.5

Retirees 26.2 22.6 21.7 21.3 12.4 23.4 22. 6 13.7

Part

- time Workers 22.7 19.8 19.0 18.7 11.2 20.4 19.8 12.386 Figure 6

- 4

. Percent Reduction in Modeled ADCs (House Age 0

- 1 Years) for Exposure

Groups, Relative to Baseline, by Alternate Emissions Scenario for New

- home Case.

Figure 6

- 5

. Percent R eduction in Modeled ADCs (House Age 0

- 1 Years) for Exposure

Groups, Relative to Baseline, by Alternate Emissions Scenario for Renovation Case.87 6. 2 DATA GAPS AND INFORMATION NEEDS

6. 2 .1 Emissions Data

Considering the factors that can influence formaldeh yde concentrations indoors, particularly in the context of modeling the impact of P WPs on concentrations and associated exposures, one notable information gap is the lack of emissions data for recently manufactured PWPs. Most

emission rates in the FIAM mod el are based on emission tests conducted around the mid

- 1990s or earlier. One feature of these tests is that they were conducted at multiple air exchange and/or product loading rates, to enable estimation of slope and intercept parameters that convey the

d ependence of the emission rate on the prevailing indoor formaldehyde concentration.

In the absence of similar data for recent CARB

- compliant PWPs, it was necessary to estimate these factors using some assumptions, as described in Section 4.4.8 of this re port. Ideally, appropriate sets of emission tests to support the model’s input needs would be conducted for a variety of CARB

- compliant products. Similar tests for products or ensembles such as

entertainment centers, kitchen cabinets and interior doors als o would be useful, as their emission profiles ha ve not been well characterized.

6. 2 .2 Near

- field Exposures

One of the assumptions inherent in the F IAM model is complete mixing; that is, formaldehyde concentrations are assumed to be uniform throughout eac h compartment that is modeled.

Whereas this assumption may be reasonable for PWPs that are dispersed throughout the residence, a notable exception that has received some recent attention is infant cribs with pressed wood components. A potential concern her e is the infant’s near

- field exposure due to close proximity to the formaldehyde source when sleeping.

Available data on this particular exposure situation are quite scarce. The Environment California Research & Policy Center (Madsen and Gibson 2008) pur chased 26 21 consumer products, mainly baby nursery furnishings such as cribs and changing tables, and arranged for chamber testing of these products. Emission rates determined from these tests covered a very broad range, from 1 to 3,580 μg/unit per hour.

As implied above, such near

- field exposures present a challenging case for indoor air modeling, possibly involving fairly complex analytical techniques such as computational fluid dynamics (CFD). A simpler alternative, compatible with the FIAM model, woul d involve a two

- zone modeling approach with one of the zones representing the “virtual air space” surrounding the infant while sleeping in a crib. This two

- zone approach has been described, for example, in

ASTM D6178

- 97

, Standard Practice for Estimation of Short

- term Inhalation Exposure to
Volatile Organic Chemicals Emitted from Bedding Sets (ASTM 2008). The validity of this approach, as well as that of the more complex CFD technique, would require assessment through detailed spatial and temporal monitoring

.

26 The cited report is dated May 2008 but does not indicate when the tested products were purchased. An appendix
in the report lists the product name, product sample ID, and manufacturer ID for each pro duct that was tested.88 

### Section 7

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- 465.

F. J. Offermann, J. Robertson, D. Springer, S. Brennan, and T. Woo. 2008. Window Usage, Ventilation, and Formaldehyde Concentrations in New California Homes: Su mmer Field

Sessions. ASHRAE IAQ 2007 Conference , Baltimore, MD.

A. Persily, A. Musser, and S.J. Emmerich. 2010. Modeled Infiltration Rate Distributions f or U.S. Housing

. Indoor Air 20: 473

- 485.

A.K. Persily. 1989. Ventilation Rates in Office Buildings. IAQ 1989 , American Society of Heating, Refrigerating and Air

- Conditioning Engineers, Inc., Atlanta, GA, pp 128

- 136.90 PSI. 2009. Professional Services Industries, Inc. (PSI)

. “The TPC Perspective

, ” a vailable at http://university.ahfa.us/documents/fmhyde309_schutfort.pdf

. S.N. Sax, D.H. Bennett, S.N. Chillrud, P.L. Kinney, and J.D. Spengler. 2004. Differences in Source Emission Rates of Volatile Organic Compounds in Inner

- City Residences of New York City and Los Angeles. Journal of Exposure Analysis and Environmental Epidemiology 14 (Supplement 1): S95

- S109.

K. Sexton, M. Petreas, and K. Liu. 1989. Formaldehyde Exposures inside Mobile Homes.
Environmental Science & Technology 23 (8): 985

- 98 8.

USEPA

. 2011. Draft Final. Assessment of Occupational Exposure to Formaldehyde From
Composite Wood Products. U.S. Environmental Protection Agency

, Office of Pollution

Prevention and Toxics

, Chemical Engineering Branch

, 1200 Pennsylvania Avenue NW

, Washin gton, DC 20460

. 6 October 2011

.

USEPA. 2012 a

. Formaldehyde Indoor Air Model

– Pressed Wood Products, Version 2.0 (FIAM

pwp v2.0): Model User Manual and Documentation

. U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Exposu re Assessment Branch, 1200 Pennsylvania

Av enue NW, Washington, DC 20460. Ju ly 2012.

USEPA. 20 12b

. AirData: Access to monitored air quality data from the EPA’s Air Quality System (AQS)

Data Mart , available at http: //www.epa.gov/airdata/

.

### Appendix A

Floor Plans by Structure TypeA

- 1 

### SINGLE FAMILY DETACHED (2 Story)A

- 2 

### SINGLE FAMILY ATTACHED (2 Story)A

- 3 

### APARTMEN TA

- 4 

### SINGLE

- WIDE MANUFACTURED HOMEA

- 5 

### DOUBLE

- WIDE MANUFACTURED HOMEA

- 6 

### CAMPER TRAILER

### Appendix B

PWP Loading SpreadsheetsB

- 1 

### SINGLE

- FAMILY DETACHED HOME

– HIGH LOADING

, NEW

- HOME CASEB

- 2 

### SINGLE

- FAMILY AT TACHED HOME

– HIGH LOADING , NEW

- HOME CA SEB

- 3 

### APARTMENT

– HIGH LOADING , NEW

- HOME CASEB

- 4 

### SINGLE

- WIDE MANUFACTURED HOME

– HIGH LOADING , NEW

- HOME CASEB

- 5 

### DOUBLE

- WIDE MANUFACTURED HOME

– HIGH LOADING , NEW

- HOME CASEB

- 6 

### CAMPER TRAILER

– HIGH LOADING , NEW

- HOME CASEB

- 7 

### SINGLE

- FAMIL Y DETACHED HOME

– HIGH LOADING , RENOVATION CASEB

- 8 

### SINGLE

- FAMILY AT TACHED HOME

– HIGH LOADING , RENOVATION CASEB

- 9 

### APARTMENT

– HIGH LOADING , RENOVATION CASEB

- 10 

### SINGLE

- WIDE MANUFACTURED HOME

– HIGH LOADING , RENOVATION CASEB

- 11 

### DOUBLE

- WIDE MANUFA CTURED HOME

– HIGH LOADING , RENOVATION CASEB

- 12 

### CAMPER TRAILER

– HIGH LOADING , RENOVATION CASE

### Appendix C

SECTION 3.2 OF FIAM

- pwp MODEL DOCUMENTATION REPORTC

- 1 3.2 Steady

- State Model for Initial Formaldehyde Concentration in One Zone

A m odel developed in the 1980s by Matthews and colleagues was designed to estimate the steady

state formaldehyde concentration resulting from emission sources in a single indoor zone or compartment. The following discussion is in large part excerpted from Mat thews et al. 1 The underlying model theory and its derivation are described in the same document and in another by Matthews and colleagues. 2

At steady state, the formaldehyde (CH 2 O) concentration in a single compartment can be expressed as follows:

[CH 2 O] SS = [CH 2 O] out + CH 2 OER/(F * ACH * VOL) (Eqn. 3

- 2)

where:

[CH 2 O] SS = steady

- state formaldehyde concentration inside the

compartment (mg/m 3 )

[CH 2 O] out = steady

- state formaldehyde concentration outside the

compartment (mg/m 3 )

CH 2 OER = emission rate of a formal dehyde source inside the compartment (mg/h)

F = fraction of air coming into the compartment that mixes within the volume (i.e., the mixing factor)

ACH = air exchange rate with outdoors for the compartment (hr - 1 )

VOL = volume of the compartment (m 3 ).

Assumi ng that F is equal to unity and using Q (airflow rate into and out of the compartment, in

m 3 /hr) to denote the product of ACH * VOL, Equation 3

- 2 becomes:

[CH 2 O] SS = [CH 2 O] out + CH 2 OER/Q (Eqn. 3

- 3)

Application of the model as expressed in Equation 3

- 3 is s implified by assuming that all parameters in the equation remain constant (at steady state) and that there are no permanent losses of formaldehyde due to irreversible sorption to sinks.

Emissions from pressed

- wood sources are area

- dependent in that the mag nitude of the emission
is a direct function of the surface area ( Area ) of the source in the compartment. The equivalent of Equation 3

- 3 for an area

- dependent source is:

[CH 2 O] SS = [CH 2 O] out + (CH 2 OER ′ * Area)/ Q (Eqn. 3

- 4)

with CH 2 OER ′ in units of mg/ m 2

- hr and area in m 2

.

1 T. Matthews, T. Reed, B. Tromberg, C. Daffron, and A. Hawthorne. 1983. Formaldehyde Emissions from

Combustion Sources and Solid Formaldehyde Resin Containing Products: Potential Impact on Indoor
Formaldehyde Concentration and Possi ble Corrective Measures. In Proceedings of ASHRAE Symposium
“Management of Atmospheres in Tightly Enclosed Spaces ,” Santa Barbara, CA.

2 T. Matthews, A. Hawthorne, C. Daffron, T. Reed, and M. Corey. 1983b. Formaldehyde Release from Wood

Products. In Proce edings of the 17th International Particleboard Symposium , Washington State University,

Pullman, WA.C

- 2 The formaldehyde emission rate, CH 2 OER ′ , is formulated consistent with a one

- dimensional representation of Fick’s Law 3

, describing the emission rate as the rel ease rate when the formaldehyde air concentration is zero, reduced by the produc t of the mass transfer coefficient and the vapor

- phase concentration . This formulation can be expressed as follows:

CH 2 OER ′ =

- m * [CH 2 O] V + b (Eqn. 3

- 5)

where:

m = the mass transfer coefficient (m/hr)

[CH 2 O] V = the CH 2 O concentration in the vapor phase ( mg/m 3 )

b = a constant; the emission rate at zero CH 2 O concentration in the air (mg/m 2

- hr).

As noted by Matthews, Hawthorne and Thompson (see footnote on this page ):

“Thus, the modeled CH 2 O emission rates maximize at zero CH 2 O concentration and decrease

lin early to a net emission rate of zero at some equilibrium CH 2 O concentration. I f the CH 2 O concentration is raised beyond the equilibrium level with the addition of new CH 2 O sources, extrapolation of the model to higher CH 2 O concentrations indicates that sor ption of the CH 2 O by the original ‘emitter’ is expected to occur. Experimental results of individual and paired emitters

in small

- scale environmental chambers by Pickrel et al. 4 and Godish et al. 5 are consistent with this theory. Paired source contribution s of pressed

- wood products, insulation, carpeting and UFFI typically yielded CH 2 O concentrations less than the sum of the concentrations for the individual
emitters. In addition, Godish found that the CH 2 O emission strength of many weaker emitters in paire d source combinations was enhanced following brief exposure to a stronger emitter. This suggests a temporary sorptive mechanism for CH 2 O followed by reemission of CH 2 O at reduced

CH 2 O concentrations.”

The vapor

- phase concentration, [CH 2 O] V , by definition i s equal to [CH 2 O] SS at steady state; therefore, substitution of [CH 2 O] SS and Equation 3

- 5 into Equation 3

- 4 results in the following expression:



## [ ] [ ]

Q Area m O CH Q Area b

O CH out

SS * 1 *

2

2

+ +

= (Eqn. 3

- 6)

In the case of multiple pressed

- wood sources, Equation 3

- 4 becomes:

[CH 2 O] SS = [CH 2 O] out + Σ (CH 2 OER ′ k * Area k ) / Q (Eqn. 3

- 7)

where the subscript k refers to the k th source. By extension, Equation 3

- 6 then becomes:



## [ ] ( ) 

## [ ]

( )

Q Area m O CH Q

Area b

O CH

k k k out k k k

SS 

## ∑ ∑

+ +

= *

1 *

2

2 (Eqn. 3

- 8 )

3 T. Matthews, A. Hawthorne, and C. Thompson. 1987. Formaldehyde Sorption and Desorption Characteristics of

Gypsum Wallboard. Environmental Science & Tec hnology 21: 629

- 634.

4 J. Pickrel, L. Griffis, B. Mokier, G. Kanapilly, and C. Hobbs. 1984. Formaldehyde Release Rate Coefficients

from Selected Consumer Products. Environmental Science & Technology 18 : 682

- 6 86

. 5 T. Godish and B. Kanyar. 1985. Formaldehyd e Source Interaction Studies. Forest Products Journal 35: 13

- 17.