EPA 747-R-96-007

May 1997

LEAD EXPOSURE ASSOCIATED WITH

RENOVATION AND REMODELING ACTIVITIES:

ENVIRONMENTAL FIELD SAMPLING STUDY

VOLUME I: TECHNICAL REPORT

Prepared By

Battelle

505 King Avenue

Columbus, OH 43201

for

Technical Programs Branch

Chemical Management Division

Office of Pollution Prevention and Toxics

Office of Prevention, Pesticides, and Toxic Substances

U.S. Environmental Protection Agency

Washington, DC 20460
ii

DISCLAIMER

Mention of trade names, products, or services does not

convey, and should not be interpreted as conveying official EPA

approval, endorsement, or recommendations.

This report is copied on recycled paper.
iii

Contributing Organizations

This study was funded and managed by the U.S. Environmental Protection Agency. The

study was conducted collaboratively by two organizations under contract to the Environmental

Protection Agency, Battelle, and Midwest Research Institute. Each organization's responsibilities

are listed below.

Battelle

Battelle was responsible for designing the study, recruiting participants, creating and

maintaining the study data, conducting the statistical analysis, and producing the final report. 

Midwest Research Institute (MRI)

MRI was responsible for field data collection, chemical analysis, and reporting of chemical

analysis results. 

U.S. Environmental Protection Agency

The Environmental Protection Agency was responsible for oversight in the developing the

study plan, managing and coordinating the overall study, and reviewing and editing this report. 

EPA Project Managers included Dan Reinhart, Darlene Watford, Susan Dillman, and Betsy

Dutrow. Cindy Stroup was the Branch Chief of the Technical Programs Branch under whose

direction the study was conducted.
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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY .................................................. xiii

1.0 INTRODUCTION TO THE OVERALL RENOVATION AND REMODELING

(R&R) STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.1 Objectives of the R&R Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.2 Scope of the R&R Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2.1 Definition of Renovation and Remodeling . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2.2 Components of the Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2.3 Specification of R&R Target Activities . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.3 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.3.1 Blood-Lead Measurements Versus Environmental Measurements . . . . . . . 1-4

1.3.2 Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

1.4 Peer Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

2.0 LITERATURE SEARCH AND INFORMATION GATHERING . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.1 Relevance of Information on Abatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2 Characterization of Renovation and Remodeling . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

2.3 Review of the Available Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.4 Review of Available Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

3.0 QUALITY ASSURANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

4.0 STUDY DESIGN FOR THE ENVIRONMENTAL FIELD SAMPLING STUDY (EFSS) . . . . . . . 4-1

4.1 Objectives of the EFSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2 Environmental Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4.3 Evaluation of Sampling Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4.4 Human Subjects Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.5 Data Gaps and Limitations of the R&R Study . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.6 Sampling and Analytical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.6.1 Sampling Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

4.6.2 Analytical Methods ..................................... 4-11

5.0 OVERVIEW OF RECRUITMENT IN THE EFSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.1 Details and Results of the Recruitment Process . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

5.1.1 Carpet Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

5.1.2 Window Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5.1.3 Large Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5.1.4 CED Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

5.2 General Characteristics of the Workers and Units Recruited . . . . . . . . . . . . . . . . . 5-7

5.2.1 Worker Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

5.2.2 Unit Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

5.2.2.1 Comparability with Units from Previous Studies ........... 5-10

6.0 DATA ANALYSIS OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6.1 Data Analysis Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6.2 Approach to Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

6.2.1 Common Approaches Taken Within Each Study Phase . . . . . . . . . . . . . . 6-3

6.2.2 Estimating Lead Disturbance in a 6' x 1' Gradient Region . . . . . . . . . . . . 6-5

6.2.3 Significant Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
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7.0 METHODOLOGY ISSUES AND RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

7.1 Stainless Steel Dustfall Collectors vs. Post- minus Pre-activity Floor Dust

Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

7.2 Stainless Steel Dustfall Collectors: Collecting Samples 1 Hour vs. 2 Hours

after R&R Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

7.3 Collecting Samples via Vacuum Techniques vs. Wipe Techniques . . . . . . . . . . . . 7-8

7.4 Comparing Results Between Side-by-Side Samples ...................... 7-11

8.0 STUDY RESULTS FOR INDIVIDUAL PHASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

8A-1.0 STUDY DESIGN IN THE CARPET REMOVAL PHASE . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

8A-1.1 Sampling Design for the Carpet Removal Phase . . . . . . . . . . . . . . . . . . . . . 8-2

8A-1.2 Unit Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

8A-2.0 Study Results for the Carpet Removal Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7

8A-2.1 Characterize Lead Disturbance and Potential Lead Exposure . . . . . . . . . . . . . 8-8

8A-2.1.1 Personal Worker Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8

8A-2.1.2 Potential Occupant Exposures to Airborne Lead . . . . . . . . . . . . 8-9

8A-2.1.3 Lead Disturbance and Potential Occupant

Exposure to Lead In Dust .......................... 8-11

8A-2.1.3.1 Vacuum Dust Samples Taken Pre- and

Post-Activity from Floor Surfaces ........... 8-11

8A-2.1.3.2 Vacuum Dust Samples from Stainless Steel

Dustfall Collectors. ..................... 8-12

8A-2.1.3.3 Vacuum Dust Samples from Window Sill

Surfaces Taken Pre- and Post-Activity. ....... 8-13

8A-2.2 Assess Factors or Measurements Related to Lead Disturbance ......... 8-13

8A-2.2.1 Personal Worker Exposures ......................... 8-14

8A-2.2.2 Potential Occupant Exposures ....................... 8-14

8A-2.2.3 Predicting Lead Disturbance and Potential

Occupant Exposures to Lead in Dust .................. 8-15

8A-2.2.3.1 Vacuum Dust Samples Taken PostActivity from Floor Surfaces .............. 8-15

8A-2.2.3.2 Vacuum Dust Samples from Stainless

Steel Dustfall Collectors .................. 8-16

8A-2.2.3.3 Vacuum Dust Samples Taken Post-Activity

from Window Sill Surfaces ................ 8-16

8A-2.2.4 Estimating Variance Components .................... 8-16

8A-2.3 Evaluate Different Media and Methods as Indicators of Exposure ....... 8-18

8A-2.4 Summary of Results ...................................... 8-20

8B-1.0 STUDY DESIGN IN THE WINDOW REPLACEMENT PHASE................... 8-22

8B-1.1 Sampling Design for the Window Replacement Phase ............... 8-22

8B-1.2 Unit Characteristics ...................................... 8-26

8B-2.0 Study Results for the Window Replacement Phase ........................ 8-27

8B-2.1 Characterize Lead Disturbance and Potential Lead Exposure ........... 8-27

8B-2.1.1 Personal Worker Exposures ......................... 8-27

8B-2.1.2 Potential Occupant Exposures to Airborne Lead ........... 8-29
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8B-2.1.3 Lead Disturbance and Potential Occupant Exposure to

Lead in Dust ................................... 8-29

8B-2.1.3.1 Vacuum Dust Samples Taken Pre- and

Post-Activity from Floor Surfaces ........... 8-30

8B-2.1.3.2 Vacuum Dust Samples from Stainless

Steel Dustfall Collectors .................. 8-30

8B-2.2 Assess Factors or Measurements Related to Lead Disturbance ......... 8-33

8B-2.2.1 Vacuum Dust Samples from Window Well Surfaces Taken

Pre-Activity .................................... 8-34

8B-2.2.2 Lead Disturbance as a Function of Pre-Activity

Lead Loadings .................................. 8-34

8B-2.2.3 Lead Disturbance as a Function of Distance from

the Windows .................................. 8-35

8B-2.2.4 Estimating Variance Components .................... 8-39

8B-2.3 Correlations Between Lead in Different Sample Media ............... 8-41

8B-2.4 Summary of Results ...................................... 8-42

8C-1.0 Study Design in the CED Phase ..................................... 8-45

8C-1.1 Sampling Design for the CED Phase ........................... 8-45

8C-1.1.1 CED Activities .................................. 8-46

8C-1.1.2 Sample Types and Locations......................... 8-48

8C-2.0 STUDY RESULTS .............................................. 8-52

8C-2.1 Structure of CED Data .................................... 8-53

8C-2.2 Characterizing Lead Disturbance and Potential Lead Exposures ......... 8-55

8C-2.2.1 Personal Worker Exposures ......................... 8-55

8C-2.2.2 Lead Disturbance and Potential Occupant Lead Exposure ..... 8-60

8C-2.2.3 Adjusting Estimates of Lead Disturbance for

the Amount of R&R Activity ........................ 8-65

8C-2.3 Factors or Measurements Related to Lead Disturbance .............. 8-67

8C-2.3.1 Pre-activity Measures of Lead Contamination ............. 8-67

8C-2.3.1.1 Results of Paint Chip Samples .............. 8-67

8C-2.3.1.2 Results of Dust Wipe Samples from

HVAC Systems ....................... 8-70

8C-2.3.1.3 Results of Dust Vacuum Samples (PreActivity in Denver) ..................... 8-70

8C-2.3.2 The Relationship Between Airborne Lead, Lead in Settled

Dust, and Paint Lead Levels ........................ 8-71

8C-2.4 the Potential for Cross Contamination Within R&R Field Studies ........ 8-74

8C-2.5 Discussion of the Results of the CED Phase ..................... 8-76

8D-1.0 INTRODUCTION AND OBJECTIVES OF THE CLEANUP INVESTIGATION ......... 8-78

8D-2.0 STUDY DESIGN IN THE CLEANUP INVESTIGATION ....................... 8-78

8D-2.1 Sampling Design in the Cleanup Investigation ..................... 8-79

8D-3.0 STUDY RESULTS FOR THE CLEANUP INVESTIGATION ..................... 8-80

8D-3.1 Lead Levels in Paint to Be Disturbed ........................... 8-82

8D-3.2 Pre- Versus Post-Cleanup Results ............................. 8-83
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8D-3.3 Post-cleanup Results ..................................... 8-86

8D-3.4 Next-Day SSDC Lead Loading Results.......................... 8-87

8D-3.5 Conclusions ........................................... 8-87

8E-1.0 DESCRIPTION OF RELEVANT DATA LOCATED FROM OTHER SOURCES .......... 8-89

8E-2.0 SUMMARY OF PERSONAL WORKER EXPOSURE DATA FROM OTHER SOURCES . . . 8-94

8E-2.1 Comparison of Personal Worker Exposure Data from Other Sources with

EFSS Results .......................................... 8-94

8E-3.0 RESULTS OF THE ANALYSIS OF SURFACE PREPARATION DATA FROM

OTHER SOURCES ............................................... 8-99

8E-3.1 Analysis to Estimate Average Personal Worker Exposure Levels

Across Studies for Surface Preparation ........................ 8-101

8E-3.2 Settled Dust Samples in the Massachusetts Department of Health Study

Associated with Surface Preparation .......................... 8-104

9.0 OVERALL RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1

9.1 Characterize Lead Disturbance and Potential Lead Exposures . . . . . . . . . . . . . 9-1

9.1.1 Personal Worker Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

9.1.2 Conversion of Task Length Averages (TLAs) into 8-Hour

Time Weighted Averages (TWAs) . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

9.1.3 Limitations of the Data and Additional Information Required

for anExposure Assessment for Workers . . . . . . . . . . . . . . . . . . . . . . 9-8

9.1.4 Summary Statistics for Lead Disturbance and Potential

Exposure to Occupants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9

9.1.4.1 Adjustment to a Standard Unit of Activity ............. 9-10

9.1.5 Estimated Effect of Clean-up on the Total Lead Disturbed ........ 9-14

9.1.6 Limitations of the Data on Lead Disturbance and Additional

Information Required for an Exposure Assessment for

Occupants ......................................... 9-14

9.2 Assessing Factors or Measurements Related to Lead Disturbance ......... 9-15

9.3 Evaluating Different Media as Indicators of Exposure .................. 9-16

10.0 CONCLUSIONS ............................................... 10-1

11.0 REFERENCES ................................................. 11-1

LIST OF APPENDICES

APPENDIX A SUPPORT TABLES AND FIGURES OF EFSS DATA . . . . . . . . . . . . . . . . . . . . A-1

APPENDIX B DATA PROCESSING AND OUTLIER DETECTION . . . . . . . . . . . . . . . . . . . . . . B-1

APPENDIX C STATISTICAL METHODS AND MODELS IN THE EFSS . . . . . . . . . . . . . . . . . . C-1

APPENDIX D QUALITY CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1
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LIST OF TABLES

Table 2-1. Potential Sources of Existing Data Associating Lead Exposure With a Particular

Renovation and Remodeling Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Table 5-1. Summary of Recruitment Efforts and Results in the EFSS . . . . . . . . . . . . . . . . . . 5-8

Table 5-2. Descriptive Statistics for Pre-Activity Lead Loadings on Floors, Window Sills,

and Window Wells in the EFSS, with Comparison to Levels Observed in

Previous Abatement Studies ..................................... 5-11

Table 7-1. Percentage of Sample Pairs (Regular and Side-by-Side QC Samples) Where Result

for the First Sample Collected Was Different From the Result for the Second Sample

Collected (Vacuum Samples Only) ................................. 7-13

Table 8A-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed

in the EFSS Carpet Removal Phase Within Each Study Unit . . . . . . . . . . . . . . . . . 8-2

Table 8A-2. Dwelling Units Included in the EFSS Carpet Removal Phase . . . . . . . . . . . . . . . . 8-6

Table 8A-3. Estimates of Total Variability and its Estimable Components in

Log-Transformed Lead Measurements by Sample Type for the Carpet

Removal Phase .............................................. 8-18

Table 8A-4. Pearson Correlations of Geometric Mean Lead Loadings Between Pairs of

Sample Types and Approaches in the Carpet Removal Phase .............. 8-19

Table 8B-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed

in the EFSS Window Replacement Phase Within Each Study Unit ........... 8-23

Table 8B-2. Dwelling Units Included in the EFSS Window Replacement Phase ........... 8-26

Table 8B-3. Estimates of the Average Amount of Lead Disturbed by Window

Replacement Activity in a 6' by 1' Rectangular Region Perpendicular to 

the Window ................................................ 8-32

Table 8B-4. Results of Tests for Significant Covariates in the Model Fitting to Lead Loading Data

in the Window Replacement Phase ................................ 8-35

Table 8B-5. Estimates of Total Variability and its Estimable Components in 

Log-Transformed Lead Measurements By Sample Type in the Window

Replacement Phase ........................................... 8-40

Table 8B-6. Pearson Correlation Coefficients of the Geometric Mean Lead Loadings

Between Pairs of Sample Types and Approaches in the Window 

Replacement Phase ........................................... 8-43

Table 8C-1. Sampling Design for Each CED Activity Within Each Study Unit............. 8-49

Table 8C-2. Number of Field Samples Collected and Available for Analysis in the 

CED Phase................................................. 8-55

Table 8C-3. Task Length for Each Combination of Target Activity and Substrate in

the CED Phase .............................................. 8-56

Table 8C-4. Model Estimates of the Geometric Mean and Standard Deviation of

Variance Components of Worker Personal Exposure to Airborne Lead (Task

Length Average) for Each CED Activity Based on a Variance Components

Model of log(PEM ) ijkl .......................................... 8-58

Table 8C-5. Estimates of the 50th, 75th, and 95th Percentiles for Worker

Personal Exposures, Along With 95% Confidence Intervals, by Activity

in the CED Phase ............................................ 8-58

Table 8C-6. Estimates of the Increase in Personal Air Exposures that are Attributable

to a Substrate Effect (Wood versus Plaster) in the CED Phase .............. 8-60
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Table 8C-7. Estimates of Lead Disturbance for Each CED Activity Based on

the "Population" Random Effects Modeling of Settled Dust 

Lead-Loading Results ......................................... 8-63

Table 8C-8. Estimates of the Log Increase in Intercept and Slope for the Relationship

Between log (Dust ) and Distance that are Attributable to a Substrate ijkl ijkl

Effect (Wood versus Plaster) ................................... 8-64

Table 8C-9. Estimated Differences in the 6' × 1' Lead Loading Gradient Attributable to

a Substrate Effect (Wood verses Plaster) ........................... 8-65

Table 8C-10. Estimates of the Potential Occupant Lead Exposure for Each CED Activity

Relative to a Standard Unit of Activity ............................. 8-66

Table 8C-11. Descriptive Summaries of Paint Chip Lead Loadings (mg/cm ) from 2

Samples Collected Within Each Activity in the CED Phase ............... 8-68

Table 8C-12. Descriptive Summaries of Paint Chip Lead Loadings (mg/cm ) by Substrate 2

in the CED Phase ........................................... 8-68

Table 8C-13. Descriptive Statistics for HVAC Wipe Sample Lead Loadings Across

and Within Units in the CED Phase ............................... 8-70

Table 8C-14. Pre-activity Settled Dust Results (Lead Loading and Sample Concentration)

from Window Sills and Shelves in the CED Phase ..................... 8-71

Table 8C-15. Estimated Substrate Effect on Log-Transformed Personal Exposure

Concentrations (log(PEM)), Before and After Adjusting for Paint Lead

Loading, in the CED Phase ..................................... 8-72

Table 8C-16. Estimated Substrate Effect on Settled Log-Transformed Dust (log(Dust)),

Before and After Adjusting for Paint Lead Loading, in the CED Phase ........ 8-73

Table 8C-17. Correlations of PEM Lead Concentrations, Settled Dust Lead Loadings, and

Paint Lead Loadings, Within an Experimental Unit, in the CED Phase ........ 8-74

Table 8C-18. Statistical Estimates, with Standard Errors, of Worker Personal Exposure

to Airborne Lead, and 6' × 1' Gradient Dustfall Lead Amounts for Each

CED Activity .............................................. 8-76

Table 8D-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed

in the EFSS Cleanup Investigation ................................ 8-82

Table 8D-2. Geometric Mean of Pre-Cleanup Lead Loadings, and the Average Ratio of Post-to

Pre-Cleanup Lead Loadings on the Same Floor Surface ................. 8-84

Table 8D-3. Estimated Lead Loadings (μg/ft , with Standard Errors) for Pre- and Post-Cleanup, 2

and Percent Reduction from Pre- to Post-Cleanup Periods, As Estimated from

Statistical Modeling Procedures ................................. 8-86

Table 8E-1. Summary of the Presence of Lead-Based Paint, Task Lengths, Personal

Exposure Sample Sizes, and Percent of Personal Exposure Samples

Above Detection Limit by Study and Target Activity ................... 8-93

Table 8E-2. Summary of Personal Worker Exposure Levels as Measured by a Task

Length Average (μg/m ) for the Other Sources of Data and for Data 3

From the EFSS ............................................. 8-95

Table 8E-3. Summary Statistics for Data Used in the Statistical Analysis of the

Surface Preparation Data (Dry Methods Only) ....................... 8-102

Table 8E-4. Model Estimates of the Geometric Mean, 95% Confidence Interval and

Standard Deviation of Variance Components of Worker Personal Exposures (Task

Length Average in μg/m ) for Interior and Exterior Dry Surface Preparation . . . 8-103 3

Table 8E-5. Summary Statistics for the Different Types of Settled Dust Samples

Collected in the Massachusetts DOH Study for Interior Dry and Wet

Surface Preparation ......................................... 8-106
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Table 9-1. Estimated Percentiles and Confidence Intervals of Personal Worker Exposures

Measured by a Task Length Average for R&R Activities and Tasks . . . . . . . . . . . 9-3

Table 9-2. The Percent of Workers Whose TLA Personal Air Lead Concentration

Would Exceed the OSHA PEL (50 μg/m ), as Estimated from the Observed 3

Distributions of TLAs in this Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Table 9-3. Estimated Lead Amounts (μg) Distributed Within a 6' x 1' Gradient Region,

with Standard Errors and 95% Confidence Intervals, in the EFSS .......... 9-12

LIST OF FIGURES

Figure 1-1. Overall Design Structure of the Renovation and Remodeling Study . . . . . . . . . . 1-6

Figure 4-1. Cyclone Dust Collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Figure 4-2. Personal Air Monitoring Sampler (Left) and Ambient Air Monitoring

Sampler (Right) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

Figure 6-1. Example of a Boxplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

Figure 6-2. Portrayal of Model Predicting Lead Exposure as a Function of Distance

from R&R Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

Figure 7-1. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples 2

Versus the Difference in Loadings Between Post-Activity and Pre-Activity

Floor Dust Samples in the Carpet Removal Phase . . . . . . . . . . . . . . . . . . . . . . 7-2

Figure 7-2. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector 2

Samples Versus the Difference in Loadings Between Post-Activity and PreActivity Floor Samples Taken Zero Feet from the Windows in the Window

Replacement Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Figure 7-3. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples 2

Versus the Difference in Loadings Between Post-Activity and Pre-Activity

Floor Samples Taken Six Feet from the Windows in the Window

Replacement Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Figure 7-4. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, 2

and the Difference in Loadings Between Post- and Pre-Activity Floor Dust

Samples in the Carpet Removal Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Figure 7-5a. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, 2

and the Difference in Loadings Between Post- and Pre-Activity Floor

Samples, Collected at Zero Feet from the Windows in the Window

Replacement Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Figure 7-5b. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, and 2

the Difference in Loadings Between Post- and Pre-Activity Floor Samples,

Collected at Six Feet from the Windows in the Window Replacement Phase . . . . 7-5

Figure 7-6. Difference in Loadings Between Two-Hour and One-Hour SSDC Samples

(Two-Hour Minus One-Hour) Versus the Difference in Elapsed Wait Times

Between the Two Samples, for Carpet Removal (c) and Window

Replacement (w) Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

Figure 7-7. Two-Hour SSDC Lead Loadings Versus One-Hour SSDC Loadings for the

Carpet Removal (c) and Window Replacement (w) Phases . . . . . . . . . . . . . . . . 7-7

Figure 7-8. Plot of Lead Loadings for Paired Vacuum/Wipe Samples at Each Location

and Study Unit in the EFSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

Figure 7-9. Plot of Wipe Sample Loading Versus Vacuum Sample Loading for Paired Samples

in the EFSS ............................................... 7-10
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xi

Figure 7-10. Lead Loadings for Adjoining Samples Collected via Vacuum Techniques

(Sample Collected First Versus Sample Collected Second) ............... 7-12

Figure 8A-1. Three Settled Dust Sampling Locations at Adjacent Areas Within Each Unit,

and the Types of Regular and QC Samples Collected Within Each Location, in the

Carpet Removal Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5

Figure 8A-2. Scatterplot of Task-Length Average Personal Exposure Lead

Concentrations (μg/m air) for Each Worker Within Each Study Unit in the 3

Carpet Removal Phase ........................................ 8-10

Figure 8A-3. Boxplots of Lead Concentrations (μg/m air) for Personal Exposure and 3

Ambient Air Samples in the Carpet Removal Phase .................... 8-10

Figure 8A-4. Scatterplot of Ambient Air Lead Concentrations (μg/m air) Within Each 3

Study Unit in the Carpet Removal Phase ........................... 8-11

Figure 8B-1. Settled Dust Sampling Locations at a Selected Window in the Window

Replacement Phase .......................................... 8-24

Figure 8B-2. Task-Length Average Personal Air Lead Concentrations, and Ambient Air

Sample Lead Concentrations, Within Each Study Unit in the Window

Replacement Phase .......................................... 8-28

Figure 8B-3. Lead Loadings for Post-Activity Versus Pre-Activity Floor Samples at 0, 3,

and 6 Feet from the Windows .................................. 8-31

Figure 8B-4. Geometric Mean Lead Loadings from Floor Surfaces as a Function of

Distance from the Window .................................... 8-31

Figure 8B-5a. Lead Loadings (μg/ft ) for Pre-Activity Floor Samples Versus Distance from 2

the Windows at Which the Samples Were Taken ...................... 8-37

Figure 8B-5b. Lead Loadings (μg/ft ) for Post-Activity Floor Samples Versus Distance 2

from the Windows at Which the Samples Were Taken .................. 8-37

Figure 8B-5c. Lead Loadings (μg/ft ) for Differences Between Adjoining Post-Activity and 2

Pre-Activity Floor Samples Versus Distance from the Windows at Which

the Samples Were Taken ...................................... 8-38

Figure 8B-6. Lead Loadings (μg/ft ) for One-Hour Post-Activity SSDC Samples Versus 2

Distance from the Windows at Which the Samples Were Taken ........... 8-38

Figure 8C-1. Scatterplot of Personal Exposure Loadings by Task Type and Unit ID ........ 8-57

Figure 8C-2. 75th Percentile and Associated 95% Confidence Interval for Personal

Exposure to Airborne Lead (μg/m ) from Each Combination of CED Activity 3

and Substrate ............................................. 8-59

Figure 8C-3. Estimated Lead Fallout Gradient in Settled Dust from 0 to 6 Feet Away

from the Edge of the Activity Space .............................. 8-63

Figure 8C-4. Estimated Lead Fallout Gradient in Settled Dust, From 0 to 6 feet Away From the

Edge of the Activity Space - Adjusted to the "Standard Unit of Activity" ..... 8-67

Figure 8C-5. Scatterplot of Paint Chip Loadings by Task/Unit in the CED Phase .......... 8-69

Figure 8C-6. Scatterplot of Paint Chip Loadings by Substrate in the CED Phase .......... 8-69

Figure 8C-7. Lead Loadings Within Wipe Dust Samples Collected from Inside 

HVAC Ductwork ............................................ 8-71

Figure 8D-1. Settled Dust Sampling Locations Specified by the Sampling Design for

the Cleanup Investigation ..................................... 8-81

Figure 8E-1. Comparison of Geometric Mean Task-Length Average Personal Worker Exposures

(μg/m ) for the EFSS and Other Data Sources During Window Replacement . . . 8-96 3

Figure 8E-2. Comparison of Geometric Mean Task-Length Average Personal Worker Exposures

(μg/m ) for the EFSS and Other Data Sources During Demolition ........... 8-96 3
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xii

Figure 8E-3. Comparison of Geometric Mean Task-Length Average Personal Worker

Lead Levels (μg/m ) for the EFSS and Other Data Sources During 3

Component Removal ........................................ 8-97

Figure 8E-4. Comparison of Geometric Mean Task-Length Average Personal Worker

Lead Levels (μg/m ) for the EFSS and Other Data Sources During 3

Cleanup Activities ........................................... 8-98

Figure 8E-5. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m ) During 3

Cleanup and Dry Interior Surface Preparation for Various Studies Compared to

the Combination Activities of the NIOSH-OU Study .................... 8-98

Figure 8E-6. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

for Other Data Sources During Dry Interior Surface Preparation ............ 8-99

Figure 8E-7. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

for Other Data Sources During Wet Interior Surface Preparation ........... 8-100

Figure 8E-8. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

for Other Data Sources During Dry Exterior Surface Preparation .......... 8-100

Figure 8E-9. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

for Other Data Sources During Wet Exterior Surface Preparation .......... 8-101

Figure 8E-10. Comparison of Results from Statistical Analysis of Geometric Mean Task

Length Average Personal Worker Exposures (μg/m ) for Exterior Surface 3

Preparation: Overall Mean Estimate and Individual Study Mean Exposures

with 95% Confidence Bounds ................................. 8-103

Figure 8E-11. Comparison of Results from Statistical Analysis of Geometric Mean Task

Length Average Personal Worker Exposures (μg/m ) for Interior Surface 3

Preparation: Overall Mean Estimate and Individual Study Mean Exposures

with 95% Confidence Bounds ................................. 8-104

Figure 9-1. Ranking of R&R Activities and Tasks Based on the Estimated 75th Percentile

of Worker Exposures Measured by a Task Length Average . . . . . . . . . . . . . . . . 9-4

Figure 9-2. Hypothetical 8-Hour Time-Weighted Average Worker Exposures for Each

Activity/Task and for Various Activity Durations . . . . . . . . . . . . . . . . . . . . . . . 9-7

Figure 9-3. Estimated Distribution of Dust Lead in a 6' x 1' Gradient for Various

Target Activities and Tasks, Based on Total Amount of Activity Performed in

the EFSS ................................................ 9-11

Figure 9-4. Estimated Distribution of Dust Lead in a 6' x 1' Gradient for Various Target

Activities and Tasks, Based on Performing the Standard Unit of Activity ...... 9-11

Figure 9-5. Estimated 6' x 1' Gradient Lead Amounts as a Function of Increases in

the Standard Unit of Activity for Each Generic R&R Task ................ 9-13
xiii

Executive Summary

The Residential Lead-Based Paint Hazard Reduction Act (Title X) required the U.S.

Environmental Protection Agency (EPA) to conduct a study of lead exposure resulting from

renovation and remodeling (R&R) activities (the R&R study). The information obtained from the

study is to be used primarily to help determine which groups of people require training,

certification, or educational materials because of the potential lead exposure associated with R&R

activities they perform. This report presents the results of one of the principal data collection

efforts in the R&R study: the Environmental Field Sampling Study (EFSS). The EFSS, through

the collection of environmental measurements, assessed the amount of disturbance and potential

exposure to lead that resulted from selected R&R activities. The monitored activities included

both specific R&R activities, such as carpet removal and window replacement, as well as

miscellaneous generic activities such as drilling, sawing, or surface preparation (sanding, paint

scraping, etc.). Environmental samples collected in the EFSS included over 90 personal air

samples taken within the breathing zone of R&R workers as they performed specific R&R

activities, and over 500 samples of dust that settled on building surfaces within a specified period

following completion of an activity.

Worker exposure was assessed using the airborne lead levels from each worker's

breathing zone, as measured by a task-length average (TLA) exposure. A worker's TLA

represents average airborne exposure for the worker during conduct of the activity. The average

TLAs were high during the conduct of many of the R&R activities, exceeding the OSHA

permissible exposure limit of 50 μg/m for four of the R&R activities. Average TLAs were 3

greater than 100 μg/m for paint removal, interior demolition, and sawing, and greater than 49 3

μg/m for interior surface preparation and central heating system maintenance/repair. Exposures 3

resulting from drilling, carpet removal, window replacement, and exterior surface preparation

were considerably lower (below 20 μg/m ). The TLA exposure for each activity (as estimated in 3

the EFSS) can be combined with worker profile information (available from outside sources) to

characterize worker exposure. 

Potential exposure to building occupants was assessed using the dust samples collected

by vacuum techniques from stainless steel dustfall collectors placed at specified distances from the

activity. Lead loadings from these samples were measured as indicators of the amount of lead

disturbed by an R&R activity and available for exposure to occupants. With the exception of

carpet removal and drilling into plaster, all activities monitored in the EFSS deposited significant

amounts of lead, ranging from 328 μg/ft for sawing lead-painted plaster to 42,900 μg/ft for paint 2 2

removal. Paint removal, demolition, sawing, and disturbing central heating system ductwork were

more likely to cause airborne lead to scatter and settle over a widespread area, while window

replacement and drilling confined the disturbed lead to a smaller area. While simple broom and

shop-vacuum cleanup substantially reduced the total amount of lead available to occupants,

cleanup efficiency declined as the distance from the activity increased. In addition, the average
xiv

amount of lead following cleanup often remained above 100 μg/ft , the current EPA guidance 2

level for floors. The estimates of lead amounts within settled dust presented in this report can be

linked with information on types and durations of activities, types of work practices and cleanup

activities, and human health effects to provide a more complete characterization of occupant

exposure associated with R&R activities.
1-1

1.0 INTRODUCTION TO THE OVERALL RENOVATION

AND REMODELING (R&R) STUDY

On October 29, 1992, the United States Congress enacted the Residential Lead-Based Paint

Hazard Reduction Act (Title X of HR 5334). This includes Title IV of the Toxic Substances

Control Act that requires the U.S. Environmental Protection Agency (EPA) Administrator to

conduct a study of lead exposure associated with renovation and remodeling activities. In

particular, paragraph (2) of Section 402 (c) states:

The Administrator shall conduct a study of the extent to which persons

engaged in various types of renovation and remodeling activities in target housing,

public buildings constructed before 1978, and commercial buildings are exposed to

lead in the conduct of such activities or disturb lead and create a lead-based paint

hazard on a regular or occasional basis. 

EPA conducted the above study, hereafter referred to as the Renovation and Remodeling

(R&R) study, from 1993 through 1995. Results of the R&R study are documented in three

separate reports: 

! "Lead Exposure Associated With Renovation and Remodeling Activities: Summary

Report"

! "Lead Exposure Associated With Renovation and Remodeling Activities: 

Environmental Field Sampling Study," a technical report on environmental

measurements of lead associated with renovation and remodeling; this report also

includes the results of the literature review and a summary of data collected from

other extant sources; and

! "Lead Exposure Associated With Renovation and Remodeling Activities: Worker

Characterization and Blood-Lead Study," a technical report on blood lead levels and

work practices of renovation and remodeling workers.

Chapters 1 and 2 of this report include a discussion of the overall design of the R&R study

and the complementary roles of its two principal data collection efforts: the Environmental Field

Sampling Study (EFSS, or Environmental Study) and the Worker Characterization and BloodLead Study (WCBS, or Blood-Lead Study). Subsequent chapters deal with the design,

implementation, and results of the EFSS. 

1.1 OBJECTIVES OF THE R&R STUDY

The overall or programmatic objective of the R&R study was to determine which groups

of people doing R&R work require training, certification, or educational materials because of their

potential lead exposure. In direct response to the scope of work outlined in the legislation, the

study was designed to satisfy two primary technical objectives:
1-2

1. Determine the extent to which persons engaged in various types of R&R activities in

target housing (i.e., housing constructed prior to 1978), public buildings constructed

before 1978, and commercial buildings are exposed to lead.

2. Determine the extent to which persons engaged in various types of R&R activities

disturb lead and create a lead-based paint hazard, on a regular or occasional basis, to

building occupants or other exposed individuals.

1.2 SCOPE OF THE R&R STUDY

The broad scope of the study mandated by Title X made it an arduous task to design and

implement the R&R study. The study required multiple field studies and decisions concerning

priorities, focus, and representativeness. This section presents the final decisions on key

definitions and delineation of scope. Chapter 2 provides insight into how these decisions were

made. 

1.2.1 Definition of Renovation and Remodeling

In accordance with the United States Census Bureau's C-50 report, "Expenditures for

Residential Upkeep and Improvement" (U.S. Census Bureau, 1987), remodeling is defined as any

construction-related work on an existing property intended to either maintain or improve the

property. In addition, the work must be on items permanently attached or firmly affixed to some

part of the house or property.

The major components of remodeling include:

! Maintenance (painting, papering, floor sanding, furnace cleaning or adjustment, etc.)

! Repairs (plumbing, heating, electrical work, etc.)

! Additions and alterations (adding a wing, room, porch, deck, shed, basement, fence,

driveway, etc.)

! Major replacements (bathroom, kitchen, roof, water pipes, central heating system,

siding, etc.).

Renovation is defined as work on an existing property intended to make a major

improvement in the property.

1.2.2 Components of the Scope

The scope of the study mandated by the Title X legislation called for an assessment of the

lead exposure for different categories of:

! Individuals (specifically R&R workers, building occupants, and other exposed

individuals)
1-3

! Environments (specifically private housing constructed before 1978, public buildings

constructed before 1978, and commercial buildings)

! R&R activities.

Private housing constructed before 1978, known as target housing, represented one category in

which lead exposure was to be assessed, while public or commercial buildings were placed into

one of two additional categories, according to whether or not children regularly inhabited the

buildings. The types of activities considered in the R&R activities segment are discussed in the

following section. 

1.2.3 Specification of R&R Target Activities

The EPA assembled a list of R&R activities associated with lead exposure. This list was

developed as a result of more than 200 contacts with other government agencies, lead poisoning

prevention experts, industry representatives, labor unions, and other concerned groups. At a final

summary meeting on April 16, 1993, in Washington, D.C., with a number of these contacted

individuals, the EPA obtained data and subsequently defined eleven categories of R&R activity

with potential for lead exposure that could be addressed by this study. These categories,

subsequently called target activities, were:

1. Paint removal

2. Surface preparation 

3. Removal of large structures 

4. Window replacement

5. Enclosure of exterior painted surfaces (i.e., siding)

6. Carpet or other floor covering removal

7. Wallpaper removal

8. HVAC (central heating system) repair or replacement including duct work

9. Repairs or additions resulting in isolated small surface disruptions

10. Exterior soil disruption

11. Major renovation projects involving multiple target activities.

There were several reasons for choosing HVAC repair over plumbing or electrical work as a

target activity. First, both plumbing and electrical work were believed to often only disturb small

areas of painted surfaces. Second, disturbance of lead in pipes, joints, and soldered connections

was considered out of the scope of the study, which was focused on lead-based paint hazards. 

Finally, there was concern that furnace ductwork could be a significant reservoir for large

amounts of lead dust.

1.3 APPROACH

The initial phase of the R&R study involved an extensive literature review and

information-gathering process. This process uncovered the currently available information on

lead exposure related to R&R activities. It also helped in decision making concerning the focus of
1-4

the study. The results of this process are presented in Chapter 2. The major conclusion of the

literature review and information gathering was that, with the exception of paint removal,

insufficient information was available for an exposure assessment of different categories of R&R

activities. As a result, new data collection was required to address study objectives. This section

discusses the approach to new data collection.

1.3.1 Blood-Lead Measurements Versus Environmental Measurements

The existence and extent of lead exposure created by R&R activities may be assessed

either by blood-lead or environmental-lead measurements. Once the need for new data collection

was identified, the R&R design team considered the advantages and disadvantages of each

approach. A study assessing blood-lead concentrations provides for direct measurement of an

internal (absorbed) dose of lead. However, blood-lead concentrations can be explained not only

by recent exposure but also by historical exposure and by many secondary factors (such as age,

nutrition, and smoking). A study assessing measurements of lead in the environment (dust, air, or

soil) makes a direct link between R&R activities and measurements of lead disturbance. 

However, these measurements serve only as estimates of the amount of lead available for potential

inhalation or ingestion, therefore representing only a potential internal dose to humans.

An optimal study design would involve measuring worker and occupant blood-lead

concentrations and environmental-lead levels before, during, and after R&R activity. However,

measuring blood-lead concentrations before and after an activity was not feasible for ethical and

legal reasons. Measuring environmental lead levels before and after an activity was complicated

by serious recruitment and liability problems because of the desire to target typical R&R jobs in an

unregulated environment.

The approach taken for this study circumvented these problems by defining two principal

data collection efforts: one characterizing environmental lead disturbance resulting from R&R

activities and the other focusing on the effect of R&R activity on worker blood-lead

concentrations through a retrospective study. A third effort, currently in the design stages, will be

a retrospective study to evaluate the impact of the conduct of R&R activity on elevated bloodlead concentrations in children. This effort will be conducted jointly with the University of

Wisconsin and the State of Wisconsin Public Health Department.

1.3.2 Data Collection

Environmental Field Sampling Study

The first principal data collection effort of the R&R study was the Environmental Field

Sampling Study (EFSS). In it, environmental measurements were taken to assess the relative

disturbance of and exposure to lead associated with selected R&R activities. Activity categories

that showed the greatest measured amounts of lead exposure were assumed to be the primary

contributors to any potential health effect. 
1-5

The focus of the EFSS was on monitoring specific R&R activities. An alternative

approach was considered, namely to monitor specific R&R worker groups as they performed

their normal duties with whatever mix of activities was encountered. The decision to focus on

activities rather than specific worker groups was supported by all representatives who attended

the April 16, 1993, study design meeting in Washington, D.C., described in Chapter 2. The

primary reasons for focusing on activities were that:

1. A focus on activities provided the best understanding of exactly what was causing the

lead exposure. 

2. A focus on activities was the most efficient way to assess a wide variety of R&R

worker groups. Exposure estimates based on worker groups would be applicable only

to the monitored groups. Exposure estimates based on specific activities, on the other

hand, could be combined with worker profile information for any given worker group

to assess that group's exposure. Worker profile information includes information on

the types of activities workers conduct, the type of work practices and worker

protection they use, and the percent of time they work in buildings with lead-based

paint.

3. Exposure estimates based on R&R activities provide information useful in the

development of subsequent guidelines for the conduct of R&R.

The data collection effort for the EFSS included six of the 11 target activities: removal of large

structures (demolition), window replacement, carpet removal, HVAC repair or replacement,

surface preparation, and repairs with minimal surface disruption. Paint removal was excluded

because exposure associated with paint removal could be assessed from the literature. Exterior

siding, wallpaper removal, and exterior soil disruption were excluded by consensus, because the

study design team and the individuals consulted in the information-gathering phase considered

these target activities to be of secondary importance. It is possible that inferences about exterior

siding and exterior soil abatement may be made from professional judgment and comparison with

other activities. Wallpaper removal is an activity conducted primarily by painters who were

assessed based on other activities they perform — most notably surface preparation and paint

removal. 

The EFSS was supplemented by an extensive search for extant data that could be used

either to fulfill data requirements for a specific activity or to confirm results obtained in the EFSS.

Worker Characterization and Blood-Lead Study

 The second principal data collection effort of the R&R study was the WCBS. The WCBS

involved collecting questionnaire information and blood-lead measurements from R&R workers

to 1) characterize blood-lead concentrations in specific worker groups, 2) determine if specific

worker groups or specific R&R activities are associated with increases in blood-lead

concentrations, and 3) collect information to be used to develop worker profiles. The WCBS was

intended to obtain information independent from the EFSS that would provide a direct measure of
 Decision on Assessm ent Method

 # Professional judgment # Literature # New field studies

— Monitoring field study

— Controlled designed field study

Target

Activities

RENOVATION AND REMODELING STUDY

Develop relationships between

activities and m easurements of

lead in the environment

Identify worker groups

and recruit workers

Characterize workers.

Develop relationship between

blood lead levels and activities

R&R Summary Report

Large R&R

Projects with

M ultiple Activities

Delineation of Scope; Literature Review and Inform ation G athering

Environmental Field Sam pling Study

(Environmental Study)

W orker Characterization and BloodLead Study (Blood-Lead Study)

Collect blood samples and

questionnaire inform ation

Use of other extant data sources

WCBS

(Blood-Lead Study)

Technical Report

EFSS

(Environmental Study)

Technical Report

1-6

Figure 1-1. Overall Design Structure of the Renovation and Remodeling Study

effects on worker health and to validate the results of the EFSS. Target R&R activities examined

in the WCBS included removal of large structures (demolition), window replacement, carpet

removal, HVAC repair or replacement, and paint removal. Post-activity cleanup was also

considered.

Figure 1-1 shows the design and coordination of the R&R study. This report presents the

technical results of the EFSS (right-hand side of Figure 1-1). As the figure indicates at the

bottom, the results of the EFSS and WCBS are integrated in the Summary Report for the R&R

study.

1.4 PEER REVIEW
1-7

This report on the Environmental Field Sampling Study (EFSS) was reviewed

independently by members of a peer review panel. Comments which are important for

interpreting the study results or which resulted in important modifications to the report are

discussed below. All peer reviewers recommended publishing the report with minor revisions.

A primary concern for a number of reviewers was the limited sample sizes in the EFSS

study. A separate section which discusses data gaps and data limitations is included in the report. 

In addition, the sample size consideration has been highlighted through characterization of the

EFSS independent monitoring jobs as case studies and through judicious use of language such as

"potential for disturbing significant amounts of lead during R&R activities" that do not overstate

conclusions that can be drawn from this data. Sample sizes are discussed and documented

throughout all reports. 

Related to the sample size issue was concern over the number of statistical analyses

conducted and the exploratory nature of some analyses. Additional cautionary language was

added to the reports to warn of exploratory analyses, the effect of multiple statistical comparisons,

and the limitation of small sample size on the ability to detect statistical significance. 

Another concern expressed by reviewers was the relevance of abatement data to an

exposure assessment for R&R workers, and similarly the effect of using trained abatement

workers for some of the work conducted in the EFSS. Several sections of the EFSS report

address these concerns directly. Section 2.1, Relevance of Information on Abatement, and

Section 2.2, Characterization of Renovation and Remodeling, discuss the differences between

abatement work and renovation and remodeling. Section 5.0, Overview of Recruitment,

addresses the criteria applied in the EFSS for accepting jobs and workers as representative of

typical R&R work. Professional abatement workers in the EFSS did wear respirators and follow

abatement personal hygiene procedures to protect themselves. However, they did not follow

standard abatement procedures, such as use of wet methods, and were instructed to perform the

tasks as they are typically conducted in an unregulated environment. For example, demolition

was conducted dry with hammers and crow bars, and sawing was conducted dry with a circular

saw and no HEPA attachment. Since no dust minimization procedures were used, the work was

considered representative of typical renovation and remodeling work. On the other hand,

available data sources from professional abatement work that did involve dust minimization were

not included in any data summaries.

Several comments related to clarification of the terms "surface preparation" and "paint

removal." Although there is certainly overlap between the two activities, there was general

concurrence among all parties consulted during the design of the study that it was important to

distinguish between the two activities. These terms are defined throughout the report to make as

clear as possible the exact type and duration of activity that took place. 

Concern was also expressed over the inability to collect both blood-lead and environmental

lead measurements from the same group of workers and/or occupants. Human subjects review,

for both ethical and legal reasons, would not allow measuring blood-lead concentrations for

occupants (young children) before and after conduct of an activity that was suspected of causing a
1-8

hazard. For workers, the difficulty in this study was recruiting typical R&R workers operating in

an unregulated environment. For this group of workers, employers were very reluctant to

participate even as the study was conducted. Contractors were concerned over lawsuits by

workers in the event that the study revealed a worker's blood-lead increased as a result of a

specific job they were assigned to. We had very few contractors participating in either phase of

the study. Employees participated in the WCBS largely because of either their own interest or the

interest and encouragement of their national and local union. Gaining access to work sites for

environmental and biological sampling would have required participation of the contractors,

homeowners, and workers. If such sampling was conducted under forced cooperation, then the

results may have been biased. If the study had focused on lead abatement workers this may not

have been a problem, but with a focus on typical R&R workers who were not, at the time of this

study, using worker protection practices, there were many problems recruiting contractors to

participate. In short, the difficulty in recruiting contractors was in getting at the population of

interest: unregulated R&R workers not specializing in lead abatement.

One reviewer requested more information to show that the QC data are consistent with the

statistical analysis applications and results. As a result of this comment, more documentation was

added to the reports, including references to appendices and quality assurance project plans. 

EPA has established a public record for the peer review under administrative record

AR152, “Lead Exposure Associated with Renovation and Remodeling Activities Peer Review.”

The record is available in the TSCA Nonconfidential Information Center, which is open from

noon to 4 PM Monday through Friday, except legal holidays. The TSCA Nonconfidential

Information Center is located in Room NE-B607, Northeast Mall, 401 M Street SW, Washington,

D.C.
2-1

2.0 LITERATURE SEARCH AND INFORMATION GATHERING

The initial phase of the R&R study involved an extensive literature review and

information-gathering process. This phase, conducted in concert with the development of EPA

guidelines for R&R ("Reducing Lead Hazard When Remodeling Your Home"), had three primary

objectives:

1. Define and characterize R&R and its component activities.

2. Collect the available information concerning human lead exposure and environmental

lead hazards resulting from R&R activities.

3. Identify any data sources that could be used in this study’s assessment of lead

exposure and hazards related to R&R.

The goal of the information-gathering process was to identify and thoroughly examine the

sources of information regarding lead exposure during R&R activities. This chapter presents the

methodology, findings, and the conclusions of the literature search and information gathering

phase.

2.1 RELEVANCE OF INFORMATION ON ABATEMENT

Early in the process of gathering information about R&R activities, it was decided to

exclude information developed during lead-based paint abatement. This exclusion was a difficult

decision. A number of R&R activities are conducted during abatement (e.g., paint removal and

window replacement), and comparable worker populations perform both abatement and the R&R

activities. Moreover, considerable information is available in the scientific literature on the human

lead exposure and environmental lead contamination resulting from implementation of various

abatement strategies. However, there were some important differences between R&R and

abatement that impact the relevance of abatement results.

The work practices associated with abatement are likely to be considerably different from

those associated with R&R activities. It is recommended that abatement workers wear protective

equipment (e.g., respirators) during the activities that disturb lead, and that the disturbed lead be

contained by spreading and taping into place polyurethane sheeting. The procedures employed in

abatement were developed to either minimize the lead dust generated (e.g., misting) or restrict its

spread outside the immediate area (e.g., via vacuum attachments). Abatement often includes

extensive cleanup procedures, such as wet-mopping the area with a detergent solution of 5%

trisodium phosphate (TSP), then vacuuming with a high-efficiency particle accumulator (HEPA)

vacuum. In addition, abatement workers, by definition, operate more frequently and

knowledgably in a lead-contaminated environment than do R&R workers. Both their training and

awareness of the hazards of lead are usually more advanced than that of workers performing

strictly R&R activities. Therefore, their blood-lead concentrations and the environmental lead

generated by their activities are not representative of general R&R workers and their activities in a

non-abatement environment.
2-2

2.2 CHARACTERIZATION OF RENOVATION AND REMODELING

The first objective of the information gathering phase was to characterize R&R, thereby

defining the scope of the study and the activities to be examined. The questions to be addressed

included:

! What is renovation and remodeling?

! Who performs it and what procedures do they employ?

! Is there a recognized lead hazard from such activities?

! If so, what activities have been identified as producing a hazard?

To answer these questions, the available literature was examined and prominent individuals in the

field of lead exposure (both residential and occupational) and within the R&R industry were

consulted. The primary goal was to obtain data on lead exposure to workers and occupants (as

measured by body-lead burden) resulting from R&R activities. If such data were unavailable,

information on environmental lead contamination was sought.

A comprehensive list of individuals or groups currently involved in lead research and

policy making from national committees, major trade industries, published authors, federal and

state agencies, academia, and medical institutions was compiled. People on the list were

contacted by telephone or personal interview. Target activities and worker classifications

associated with R&R were drafted by sorting through the literature and the information and

perspectives offered in the many phone calls and interviews. After more than 200 interviews were

completed, a final summary meeting was held on April 16, 1993, in Washington, D.C. with a

number of the contacted individuals. From this meeting, a general concurrence on the scope of

R&R and its component target activities and worker classifications was reached. The resulting

characterization and definition of R&R target activities to be considered was presented in Section

1.2.3.

 In addition to defining R&R and its component target activities and classifying the

workers who perform these activities, the actual work practices involved in R&R needed to be

identified. Many of the contacts from national trade unions and government agencies stressed the

need to focus on "typical" R&R practices. They also stressed their belief that abatement practices

would not be representative of typical R&R practices. Although no information was identified

that directly described actual R&R work practices, some information concerning guidelines for

performing R&R work was uncovered. The National Association of Home Builders (NAHB) has

produced guidelines entitled, "What Remodelers Need to Know and Do About Lead — An

Interim Guide" (NAHB, December 1992). These guidelines parallel the HUD Guidelines for

Evaluation and Control of Lead-Based Paint Hazards in Housing (U.S. Department of Housing

and Urban Development, July 1995). Information concerning typical work practices was targeted

for collection in the WCBS component of the R&R study.

Finally, the parties attending the Washington meeting prioritized the identified R&R target

activities according to the need for data collection efforts to assess the lead exposure or
2-3

environmental lead hazard generated. As a result, the following activities (listed in no particular

order) were chosen for new data collection as part of this study:

! Carpet removal

! Window replacement

! Removal of large structures (demolition)

! HVAC work

! Isolated surface disruptions.

2.3 REVIEW OF THE AVAILABLE LITERATURE

The second objective of the information gathering phase was to thoroughly explore and

understand the existing body of information concerning the relationship between renovation and

remodeling and lead exposure, and to identify any data that could be used to assess this

relationship. Beginning with the individuals asked to define R&R, a search was performed to

identify published reports, papers, data, or other individuals or organizations that would provide

information on lead exposure or hazards associated with R&R activities. This method of

information gathering was pursued until no previously unidentified sources were uncovered.

In addition to soliciting opinions and information from interested parties, an extensive

literature search was undertaken. The search covered all information published in the last 15

years pertaining to the lead exposure of occupants, R&R workers, activities, R&R methods within

an activity, R&R in industry, and R&R in the military. Using the on-line library search system,

DIALOG, journals available through MEDLINE, NTIS, Engineering Information, Enviroline,

Pollution Abstracts, Occupational Safety and Health, and other sources were examined for

information relating to lead exposure and renovation and remodeling. More than 500 potentially

relevant articles were identified.

From this search, it was confirmed that literature directly discussing lead hazards or

exposure created by R&R activities was limited. Only 12 articles focused on renovation and

remodeling. Moreover, there appeared to be no definitive lead exposure study examining R&R

activities. In fact, all references to R&R activities were either secondary or anecdotal. For

example, four articles described case studies of individuals suffering from elevated blood-lead

levels during renovation of their homes. Overall, however, these twelve articles did provide

evidence of lead elevations in both body burden (blood) and environmental media (dust, air, and

soil) resulting from R&R activities.

On the other hand, there was a significant body of literature discussing R&R-related

activities, such as lead abatement. Approximately 20 such articles and reports were identified,

providing detailed information about the association between disturbances to an existing lead

reservoir (e.g., lead-contaminated soil or lead-based paint) and environmental or body-burden

lead levels. As was indicated in Section 2.1, the activity performed and the actual work practice

in an abatement are likely to be different from that of R&R. In fact, an argument could be made

that exposures measured during an abatement activity represent either a best- or worst-case

scenario when applied to the same renovation and remodeling activity. They could represent a
2-4

best-case scenario because of the extensive precautions taken during abatement work. They

could represent a worst-case scenario because of the amount of lead disturbed during an

abatement. Therefore, only to the degree that an abatement activity is considered "similar" to a

typical R&R activity would the abatement literature prove useful in evaluating the lead hazard

associated with an R&R activity.

Despite the scarcity of directly relevant literature, there did appear to be a consensus that

R&R activities can produce both body-lead burden and environmental lead contamination. In a

longitudinal study of blood-lead levels in neonates, Rabinowitz and Needleman note that "infants

residing where lead paint is being resurfaced (as typically performed) may be at special risk of

increased lead exposure" (Rabinowitz et al., 1985). The Center for Disease Control and

Prevention's (CDC's) publication, "Preventing Lead Poisoning in Young Children," reports that

"many cases of childhood lead poisoning that result from renovation and remodeling of homes

have been reported" (Centers for Disease Control and Prevention, 1991). The Department of

Health and Human Services' (HHS') "Strategic Plan for the Elimination of Childhood Lead

Poisoning," cites as priorities for lead abatement "homes with lead-based paint that are being

renovated and remodeled for other reasons" (U.S. Dept. of HHS, February 1991). Dr. Julian

Chisolm, a respected doctor involved in childhood lead research, and other contacts, expressed

their personal opinion that R&R activities are responsible for elevated blood-lead levels in many

middle-class children. Renovation and remodeling activities, by their very nature, have the

potential to disturb existing reservoirs of lead (e.g., intact lead-based paint, lead dustcontaminated carpet). Once the disruption occurs, the lead is available for contamination of

workers and residents. This fact, along with the acknowledged link between environmental lead

levels (especially dust-lead levels) and blood-lead concentrations, leads to a recognition that R&R

activities are a possible source of lead exposure to both children and adults.

A debate arises, however, when assessing which R&R activities produce a lead hazard. 

Upon closer examination of the literature, the activity cited most often as responsible for lead

exposure and hazards is lead-based paint removal. Even industry sources (e.g., the National

Association of Home Builders) concede the hazard of paint removal. However, some literature

sources claim that other activities such as surface enclosure or component removal generate a

non-significant lead hazard. In fact, this dichotomy is fairly complete: lead-based paint removal is

widely recognized as generating a lead hazard, but other R&R activities are only sparsely

addressed. For example, the NAHB suggests that "while remodeling and lead abatement tasks

other than paint removal may generate small amounts of airborne lead dust and paint debris, with

proper cleanup they represent a minimal hazard to workers and occupants" (NAHB, December

1992). Within the literature, R&R activities have been effectively characterized into two groups: 

paint removal and everything else.

Chemical stripping, surface sanding, and heat gun stripping are procedures usually used for

paint removal. All are widely acknowledged to generate a lead hazard in the presence of leadbased paint. There are numerous studies of lead poisoning of construction workers employed at

removing lead-based paint. The HUD Abatement Demonstration Study found unacceptably

elevated levels of personal exposure to airborne lead for workers removing lead-based paint with

heat guns, despite temperature controls to prevent vaporization of the paint (U.S. Dept. of HUD,
 Permissible exposure limit. *

2-5

1991). Industry also concedes the problem as reported in the NAHB guidelines entitled, "What

Remodelers Need to Know About Lead" (NAHB, December 1992). The evidence from the

literature and the broad consensus suggests that additional studies of paint removal will yield little

new information on this activity's potential lead exposure to workers and occupants. 

Few references address lead hazards or exposure associated with the other renovation and

remodeling activities, and the information is insufficient for assessing the hazards presented in

R&R activities other than paint removal. A National Institute of Safety and Occupational Safety

and Health (NIOSH) evaluation of the lead hazard produced during the HUD Abatement

Demonstration Study found that "less than 5% of the personal exposures to lead measured for ...

enclosure and replacement methods, and none of the exposures for encapsulation, ... exceeded the

OSHA PEL of 50 μg/m " (NIOSH, February 1992). These figures were for abatement methods, * 3

however, not for typical R&R methods. Conversely, an abatement study conducted by NIOSH

evaluating the hazards associated with cleaning up lead-based paint found that short-term personal

exposure levels met or exceeded the OSHA PEL limit in 16 of 36 workers. NIOSH reports that

"... the results of the study are of interest because many construction workers potentially perform

similar activities during renovation ..." (NIOSH, Ohio University, May 1993). Additionally, the

Comprehensive Abatement Performance (CAP) Pilot Study reported elevated dust-lead levels

resulting from extensive renovation (including large surface demolition and plumbing installation)

of a formerly abated housing unit (Battelle Report to USEPA, September 1994). A two-year

monitoring study of lead exposure in infants found "home refinishing" as a contributor to dust and

blood-lead levels (Rabinowitz et al., 1985). The specific activities that constituted home

refinishing were not thoroughly discussed, but activities other than exclusively paint removal were

considered. Therein lies much of the reason for the scarcity of information about other R&R

activities. Discussions of R&R activities in the literature focus on the source of the lead hazard,

not the activities that contribute to that hazard. Since many R&R activities occur within the

residence, lead-based paint is usually identified as that source. Any information about the

activities is anecdotal. The lead hazard or poisoning documented in case studies may be caused

by activities other than paint removal, but details are not available. It was concluded, as a result,

that the lead hazard or exposure from renovation and remodeling activities other than paint

removal cannot be assessed from the literature alone.

2.4 REVIEW OF AVAILABLE DATA SOURCES

Since the literature search yielded little information concerning the lead hazard associated

with R&R activities other than paint removal, a comprehensive search was undertaken to uncover

any existing sources of data that might relate a specific R&R activity to the lead exposure

presented by that activity. Starting with the contact list compiled earlier and likely resources

identified in the literature, a list of potential data sources was created. This list included

individuals from special interest groups in the construction industry, independent researchers, the

U. S. military, public housing authorities (PHAs), and other government agencies. To ensure a

comprehensive search, individuals who were contacted were asked to identify possible data
2-6

sources or individuals who might lead to a data source. If a potential new source was identified,

then the individual or organization was added to the list. This was continued until no new

individuals were identified.

Telephone calls were made to each individual on the list. During the course of the

conversation, the scope of the project was conveyed, emphasizing strongly the need to find data

that could directly relate lead exposure or contamination to a specific R&R activity. During the

phone interview, a determination was made whether the recommended data source was

representative of a renovation and remodeling activity. Generally, data collected when abatement

techniques were employed was not considered representative of the exposure that may occur

during "typical" R&R activity. [It is recognized that what constitutes "typical" R&R is currently

under revision, owing primarily to the issuance of OSHA's Interim Final Rule for Lead Exposure

in Construction (29 CFR 1926.62), which became effective during the term of this study.] 

Exceptions were allowed for some abatement activities, such as exterior work and encapsulation,

since these activities are very similar to R&R activities. If there was any doubt as to the

applicability of the data, the person was asked to send the data with some documentation if

possible. A determination was made whether to include the data after the data collection methods

were more closely reviewed. This ensured that a potential data source was not missed because of

miscommunication or misunderstanding. Those individuals with data that fit well into the scope

of the study were asked to send the data in whatever format was convenient, with documentation

whenever possible. All data were compiled into a common data set so that summaries could be

made.

More than 40 individuals and organizations were contacted. However, very few renovation

and remodeling data sources were uncovered. A large body of information covers specific

activities and the lead exposure associated with these activities when abatement techniques are

employed, but very few sources collected information during activities that resemble or actually

are R&R settings. For instance, abatement data from several PHAs were available, but because

many of the abatement projects were sponsored by HUD grants, HUD’s guidelines on abatement

(which include extensive worker and occupant protection measures and cleanup) were followed. 

Some of the activities that very closely resemble renovation and remodeling activities, even when

abatement guidelines are followed, include interior and exterior encapsulation, component

replacement, and some surface preparation. Whenever possible, these activities were extracted

from the abatement studies and included in the data base.

Several potential data sources reported monitoring data that could not be related to specific

activities or to R&R activities that were conducted on surfaces coated with lead-based paint. As

a result, these data could not be placed in an appropriate context in this study and therefore were

not included in the data base. Other contacts have confirmed the lack of lead exposure data

related to renovation and remodeling. One military official, representing a data source included in

Table 2-1, stated that before their study in 1992, they could not find any data related specifically

to R&R. 
2-7

Table 2-1 lists several characteristics of the potential data sources identified. Of the 18

identified sources, the results from 10 studies were received. Of those 10, eight had information

that related exposure to a particular R&R activity. These eight data sources are discussed in

Section 8E of Chapter 8.

Table 2-1. Potential Sources of Existing Data Associating Lead Exposure With a Particular

Renovation and Remodeling Activity

Identified Data Sources Activities Sources Identified

Number of

National Association of Home Builders (NAHB) 2 # Demolition

# Window Replacement

Private Environmental/

Abatement Contractors

# Component Removal

# Window Replacement

# Carpet Removal 4

# Demolition

# Surface Preparation

Public Housing Authorities (PHAs) # Kitchen Remodeling 5

# Surface Preparation

# Exterior work

National Institute of Occupational Safety and # Various R&R activities

Health (NIOSH) # Cleanup 2

California Department of Health;

New York State Department of Health;

Massachusetts Department of Environmental

Health

# Surface Preparation: Sanding and

Scraping 3

# Window Replacement

U. S. Military 2

# Surface Preparation: Sanding, Scraping,

Power Sanding

# Cleanup

# Exterior Component Installation

# Interior Component Removal

# Painting

In general, data provided by the PHAs were not representative of typical R&R or were not

available to the study. Much of the PHA data were collected in an abatement setting that was not

representative of typical R&R. Because much of the abatement work was contracted out, the

data did not reside with the PHAs. The need to obtain data from contractors greatly diminished

the potential for collecting PHA data. Only one PHA contractor provided data to this study. 

The data identified and obtained from sources other than a PHA tended to be more closely

related to R&R activities. The individuals contacted were very much aware of the potential

problems of lead exposure to R&R workers and were sensitive to the issues involved in locating

data specific to R&R. Several good prospects were developed through these individuals, and

potentially informative data sets were obtained.

2.5 SUMMARY

Available information on the lead hazards associated with R&R activities other than paint

removal is very limited. Despite a comprehensive literature search and hundreds of phone calls to

individuals very familiar with lead issues and policies, little information was uncovered. Only
2-8

eight sources were found to contain data on lead exposure related specifically to R&R activities. 

The data collected from these other sources are summarized and discussed in Section 8E of

Chapter 8. 

Two additional studies were identified that were in the planning stages at the time the EFSS

was conducted: 1) a study sponsored by a state government agency (with support of a HUD

grant) of surface preparation using dry scraping, heat guns, and torches, and 2) a study sponsored

by the NIOSH of the renovation and remodeling of post offices and General Accounting offices

throughout the U.S. These studies have the potential to provide additional useful data for

investigating the relationship between lead exposure and R&R.
3-1

3.0 QUALITY ASSURANCE

In the EFSS, as in any environmental sampling program, a variety of sources of error

exists that could potentially affect the quality of the study results. A careful assessment of

these sources of error was made, and quality control measures were implemented to help

minimize their effects. The most important quality control measure was the Quality Assurance

Project Plan (QAPjP). The QAPjP is intended to document the entire process involved in

executing the field program, along with appropriate quality assurance measures. QAPjPs were

prepared for the carpet removal and window replacement phases, and an addendum was

prepared for the CED phase. The entire project team contributed to the QAPjPs, which were

reviewed and approved by the EPA/OPPT technical staff and Quality Assurance Officer. 

Subjects covered in the QAPjP include:

! Project overview.

! Project organization and management structure, including organization and

personnel responsibilities, and personnel qualifications.

! Study objectives including chemical data quality objectives.

! Method selection and analytical method performance including objectives and

specifications for precision, accuracy, and verification and validation.

! Sampling plan including sampling frame construction, screening protocols, unit

selection criteria, field QC samples, and sample size determination.

! Analysis plan including data review and transfer procedures, data quality

assessment, and statistical analysis procedures.

! Sample collection procedures, including specification of the field sampling team,

determination of sampling locations, and sampling schedule, transfer and storage

procedures.

! Sample identification, tracking, and handling.

! Sampling equipment, including equipment performance requirements, preventive

maintenance, corrective actions, contamination avoidance, and equipment

calibration.

! Sample preparation procedures.

! Data processing procedures, including storage, transfer, tracking, and outlier

detection procedures.

! Specification of all data collection forms.
3-2

! Health and safety procedures, including Human Subjects Review.

! Audit requirements, including system, performance evaluation, and data audits,

and audit reporting and corrective action.

! Reporting requirements.

The QAPjPs may be referenced for additional details on any of the above subjects. 

Appendix B in Volume II of this report documents data processing procedures followed

in this study and presents results of the outlier detection analyses and decisions. Only one

outlier in the three phases of the EFSS study was deleted from the statistical analysis as

documented in Appendix B.

Appendix D in Volume II presents the results of analysis of quality control samples

collected in the study including field blanks and field side-by-side samples. In all three phases

of the EFSS, the results of analyzing initial calibration verification and continuing calibration

verification samples in each instrumental analysis batch were within the protocol criteria of

+10%. This indicates that the analytical instrument was properly calibrated for all of the

sample analyses. Tables D-3a through D-3c in Appendix D report the status of meeting data

quality objectives within batches in the carpet removal, window replacement, and CED

phases, respectively. 
4-1

4.0 STUDY DESIGN FOR THE ENVIRONMENTAL

FIELD SAMPLING STUDY (EFSS)

The purpose of the EFSS was to assess the lead exposure and lead disturbance associated

with various types of R&R activities through environmental measurements of lead in air and dust.

The EFSS consisted of four phases of data collection that either addressed a specific type

of R&R activity or a group of activities. These phases were:

1. An information-gathering phase, to uncover the current body of information

concerning lead exposure associated with renovation and remodeling and to analyze

environmental lead exposure data collected in other studies that investigated

exposures associated with specific R&R target activities, or with large R&R projects

2. A carpet removal phase, to investigate lead exposure associated with carpet

removal activities

3. A window replacement phase, to investigate lead exposure associated with window

replacement activities 

4. A controlled, experimentally designed (CED) phase, to investigate lead exposure

associated with several R&R activities (large structure removal, small surface

disruption, HVAC repair, generic R&R activities) that are difficult to isolate in an

actual R&R job or are components of larger R&R activities.

The first phase was described in Chapter 2. In the other three phases, the same sampling and

laboratory analysis protocols were applied to environmental samples from various media. This

chapter presents common elements of the study design for these three phases. Chapter 8 presents

details on the specific implementation of the general study design.

4.1 OBJECTIVES OF THE EFSS

Technical objectives for the R&R study were presented in Section 1.1 of Chapter 1. The

primary technical objectives of the EFSS were to characterize the: 

1. Personal exposure to airborne lead for workers during the performance of different

R&R target activities and combinations of activities, and determine if worker

exposure to airborne lead during those activities exceeds 50 μg/m [the OSHA 3

permissible exposure limit (PEL)]. 

2. Airborne lead levels in areas adjacent to the activity area (the area -- room, floor,

etc. -- in which the R&R activity took place) for selected R&R activities.

3. Amount of lead disturbed that settles on building surfaces within a specified period

following completion of the R&R activity. 
4-2

4. Extent that lead disturbance and exposure are affected by various factors such as

distance from the activity and pre-activity measures of lead contamination in the

building. 

Some secondary objectives of interest related to sampling methodology were incorporated into

selected phases of the EFSS to aid in refining the design of this study. The secondary objectives

are discussed in Section 4.3 and in greater detail in Chapter 7.

4.2 ENVIRONMENTAL SAMPLING

Although the activities, buildings, and, in some instances, types of samples differed for

each category of activities, the design and protocol for all environmental sampling were similar.

In general, for each monitored R&R activity, buildings containing lead-based paint suitable

for typical application of the activity were selected. Buildings were selected based on

predetermined screening criteria, as discussed in Chapter 5, that included taking X-ray

fluorescence (XRF) and/or inductively coupled plasma (ICP) samples on painted surfaces in

selected rooms of the unit. 

Environmental measurements of lead were taken before, during, and after conducting the

target activity. The measurements taken in the EFSS included:

1. Personal Air Samples. Measures of airborne lead concentrations at a fixed flow

rate within each worker's personal breathing zone were collected by taking air

samples through a cassette filter mounted to the worker's lapel. An air sampler

pump was used to take the sample. The activity period was defined for each specific

R&R activity, but generally included immediate preparation for the activity, activity

conduct, and cleanup. For each worker, average exposure over the duration of the

activity period was calculated in μg/m .3

2. Room (Ambient) Air Samples. Ambient air samples were collected for selected

activities in areas adjacent to the activity. Adjacent areas were used to address the

levels at which occupants might be exposed to airborne lead in other parts of the

building while conducting the activity. 

3. Settled Dust Samples. Settled dust samples were taken either from stainless steel

dustfall collectors (see Section 4.3) or from selected areas such as floors, window

sills, window wells, and carpets. Samples were collected at varying distances from

the surfaces disturbed by the activity. Lead loadings from settled dust samples were

measured as indicators of the amount of lead disturbed by the activity and made

available as a potential exposure to occupants. Further discussion on the sampling

methodology for settled dust samples is provided in Section 4.6 below.

It was not possible to obtain a statistically based, representative sample of the exposed

populations or the defined jobs, because of recruitment difficulties in obtaining "real-world" R&R
4-3

jobs as they are currently being conducted, cost constraints, and the wide variety of work

practices and building characteristics. Consequently, the EFSS focused on characterizing "case

studies" that were deemed "reasonably representative" (i.e., not atypical) of general R&R work as

it is currently conducted. Two different approaches were taken to characterize these case studies:

1. Monitoring "real-world" R&R jobs as they occurred in the field 

2. Monitoring controlled, experimentally designed simulations of specified renovation

and remodeling activities in vacant buildings. 

In the first approach, an attempt was made to select R&R jobs (case studies) that did not appear

atypical of general R&R work currently being conducted. These jobs needed to have high

potential for lead contamination because of the age of the building, presence of lead-based paint,

and types of activities being conducted. 

In the second approach, the design team specified the type, quantity, and characteristics of

activities to be conducted in dwellings in the field. Experienced R&R workers, contracted to

perform the work, simulated target activities and generic R&R tasks (e.g., cutting and drilling) so

that measurements could be taken of lead disturbance associated with these tasks. The generic

tasks are often components of any number of R&R target activities and provide an indication of

potential hazards associated with many different R&R jobs. 

Details of the sampling plan and design for each R&R activity or task monitored are

presented in Chapter 8 with the discussion of each phase of the EFSS.

4.3 EVALUATION OF SAMPLING METHODOLOGY

The EFSS was designed to measure lead disturbance and lead exposures associated with

specific short-term R&R activities. Sampling methodologies commonly used in occupational

studies, clearance testing, risk assessment, and previous abatement studies were employed

whenever possible in this study. In the case of settled dust, however, a different method of

characterizing the amount of lead disturbed by a specific activity was employed. Post-activity and

pre-activity measurements on building surfaces are commonly compared in lead contamination

studies in buildings. The alternative method involves placing one-square-foot stainless steel plates

on the floor immediately before the start of an activity at varying distances from the activity area. 

These plates are referred to as stainless steel dustfall collectors (SSDCs). Settled dust samples

are collected from these plates at a specified period of time after completion of the activity. 

Interest in evaluating the sampling methodology introduced additional objectives into the

early phases of the study. Those objectives were to:

! Compare results from the sampling methodology using SSDCs to results from the

sampling methodology employing pre- and post-activity floor samples
4-4

! Compare results from settled dust samples collected one hour following completion

of an activity with results from settled dust samples collected two hours after

completion of an activity

! Compare results from settled dust samples collected using vacuum techniques with

results from samples collected using wipe techniques.

To assess the first objective, SSDCs were placed next to the post- and pre-activity floor

samples at all locations in the carpet removal phase, and at two out of three sampling locations in

each unit in the window replacement phase. The second objective was assessed by placing two

SSDCs side by side at all locations in the carpet removal phase, and at one out of three locations

in each unit in the window replacement phase. One side-by-side sample was collected

approximately one hour after completion of the activity and the other approximately two hours

after completion of the activity. The third objective was assessed by additional side-by-side

samples at two out of three sampling locations in each unit in the carpet removal phase and at a

total of 12 sampling locations during interior demolition work in the controlled, experimentally

designed (CED) phase. Results pertaining to sampling methodology evaluation are discussed in

Chapter 7.

4.4 HUMAN SUBJECTS REVIEW

All aspects of the field work involved in the EFSS were documented and submitted to

both the contractors' and EPA's Human Subjects Review Committees for review and approval. 

All procedures complied with the requirements of the human subjects committees. 

4.5 DATA GAPS AND LIMITATIONS OF THE R&R STUDY

Due to the broad scope of the EFSS and the R&R study as defined by Title X legislation,

combined with time and budget constraints, recruitment difficulties, and human subjects concerns,

insufficient information was available to make inferences on certain areas of interest to the study. 

Data gaps that remain include:

1. Information on the relationship between R&R and occupants' (children's) 

blood-lead concentrations. The combination of environmental measurements and

worker blood-lead concentrations was expected to provide sufficient exposure

information to address regulatory needs. However, the blood-lead concentrations of

R&R workers were very low, while the amount of lead released to the environment

was very high. These conflicting outcomes imply that measuring environmental lead

levels might be an inadequate surrogate for measuring human blood-lead levels. 

This, combined with difficulties in determining a health-based standard for

acceptable environmental lead levels, places more importance on the relationship

between R&R and occupant exposure as measured by blood-lead concentrations. 

Therefore a follow-on study will be conducted to evaluate the impact of the conduct

of R&R activities on elevated blood-lead concentrations in children. This study will
4-5

be conducted jointly with the University of Wisconsin and the State of Wisconsin

Public Health Department.

2. Exposure of people other than occupants and workers was not assessed. Other

potentially exposed populations include workers' families and residents of

neighboring buildings. 

It is important to note the limitations of the data collected in the EFSS:

1. The EFSS field monitoring work represents a series of case studies that were not

selected by a random sampling scheme. Generalizing the results of the EFSS to a

broader population must be based on a qualitative assessment of how representative

the case studies are of that population. However, no reason was uncovered to

believe that the case studies were atypical of general R&R work as it is conducted in

an unregulated environment containing high levels of lead-based paint. 

2. Measurements of lead distributed into the occupants' environments were

collected before cleanup. The effect of different cleanup methods was measured

for two target activities in the EFSS, and data were collected in the WCBS on

typical cleanup methods employed by R&R workers. However, additional

information on the extent of typical cleanup would be useful. 

3. The focus of the data collected in the EFSS was on target housing. Exposure

differences between building environments from a lead abatement perspective are

discussed in EPA's proposed rule 40 CFR Part 745, "Requirements for Lead-Based

Paint Activities," where an argument is made that public buildings and target

housing represent similar exposure environments. However, there are no data at

this time to assess whether environmental exposures monitored in target housing are

representative of environmental exposures encountered in public or commercial

buildings.

Further discussion of limitations on inferences drawn from the results of the EFSS are

presented in the discussion of overall results in Chapter 9.

4.6 SAMPLING AND ANALYTICAL METHODS

During the course of the EFSS, field sampling activities were conducted to monitor a

variety of renovation and remodeling activities. The following categories of field samples were

collected during the study:

! Wipe sampling of settled dust

! Vacuum sampling of settled dust

! Personal exposure samples

! Area airborne dust samples

! Paint chip samples
4-6

! Plaster samples.

The following two sections discuss the sampling and analytical methods applied to the

above categories of samples. Further details on sampling and analytical methods can be found in

the QAPjP.

4.6.1 Sampling Methods

Wipe Samples of Settled Dust

Wipe samples of settled dust were collected from the SSDCs, as well as directly from

other horizontal sampling surfaces (e.g., HVAC ducts). All wipe samples were collected using

commercially available, premoistened disposable wipes (Wash-a-bye BabyTM). The protocol for

collecting a wipe sample is as follows:

! Don a clean pair of powderless vinyl gloves.

! Open the lid of the wipes container and remove several wipes. Discard the initial

wipes removed, and use the next wipe from the container to collect the sample.

! Place the wipe flat on the sample surface. (Note that in some cases the sample

surface was a 1-ft steel template; in other cases, the surface was a ventilation duct, 2

etc.)

! Using an open flat hand with the fingers together, wipe the marked surface in an

overlapping "S" pattern. The initial pattern should be from side to side and then

from front to back so that the entire sample collection area is covered.

! When sampling small areas (i.e., less than 1-ft ), the wipe should be folded in half 2

with the sample side folded in. Repeat the wiping procedure within the defined

surface area.

Vacuum Sampling of Settled Dust

Special equipment is employed for collecting vacuumed settled dust. The vacuum

sampling equipment included a modified HVS3 cyclone dust collector and a Red-Devil® portable

vacuum (Figure 4-1). The cyclone dust collector has an output nozzle on the top, which is

connected to the portable vacuum, and an inlet on the side, which is connected to a tygon

"collection" tube. The bottom segment of the cyclone dust collector is conical in shape, with

internal threads at the narrow end of the case to accommodate the sample collection bottle. A

Teflon sealing ring forms the joint between the cyclone top and bottom segments. A cyclone

4-8

dust collector has advantages over a dust collector that uses a filter. The collection bottle

eliminates the need for pre- and post-weighing and conditioning of the filter, and has a larger

capacity. The protocol for collecting a vacuumed settled dust sample is as follows:

! Place a clean grey PVC transition piece onto the tangential inlet of the cyclone head.

! Position the cyclone in a vertical position and securely screw the sampling collection

bottle into the lower threaded end of the cyclone.

! Insert the proper end of the collection tube into the grey transition piece. Attach the

vinyl tubing to the sampler case's 3/4-inch inlet.

! Run an extension cord from the nearest 110-V AC outlet (or generator) to the

designated sampling location and plug in the portable vacuum.

! Turn on the pump and vacuum the sample area in overlapping passes (i.e., at least

50% overlap), initially left to right, then front to back over the entire designated

area. Repeat vacuuming pattern for two minutes.

! When vacuuming is complete, turn off the vacuum and keep cyclone vertical. Raise

the humidity within the cyclone by slowly blowing three breaths into the grey

transition piece. Tap the cyclone case three times to dislodge any remaining debris.

! While keeping the cyclone vertical, unscrew the dust collection bottle from the

cyclone and recap the dust collection bottle.

Exposure Samples

Personal exposure monitoring to airborne lead was conducted using NIOSH method 7300. 

The personal sampler, illustrated in Figure 4-2, pulls air across sample media at a known sample

flow rate. The flow rate of the sampling pumps is set between 1 and 4 liters per minute, with a

preference for 4 liters per minute. The exact flow rate is determined during calibration procedures

that are performed before and after each sampling period. The protocol for collecting personal

exposure samples is as follows:

! Samples are collected by using a battery operated pump (Gilian HFS 113 and 513)

attached to a tygon tubing with the sample media attached to the opposite end of the

tubing.

! Don clean vinyl gloves. Remove inlet and outlet plugs from an unused 0.8 μ, 37

mm mixed cellulose ester filter cassette. Attach the tygon tubing to the sample

media by inserting a nipple into the open end of the tubing (i.e., the end opposite of

that attached to the sampling pump) and inserting the nipple into the outlet opening

of the cassette.

4-10

! Mount the sampler at the waist using the belt clip attached to the sampler. Clip the

filter cassette to the worker's lapel (make sure that the cassette remains in the

worker's breathing zone), making sure to secure the tubing to the worker in a

manner such that is does not interfere (e.g., tape the tubing to the worker's back). 

The inlet of the filter cassette should be positioned slightly downward to avoid dust

from passively falling into the cassette.

! Turn the sampling pump on and record time.

! When sampling is complete, turn the sampling pump off and record time. Cap the

inlet and outlet plugs of the cassette.

Area Airborne Dust Samples

Area exposure monitoring to airborne lead was conducted using Gilian AirCon High

Volume samplers. The ambient air sampler, illustrated in Figure 4-2, has a flow rate set at rates

up to 12.5 liters per minute. The exact flow rate is determined during calibration procedures that

are performed before and after each sampling period. The protocol for collecting area airborne

dust samples is as follows:

! Set up tripod at sample location and set pump on floor under tripod.

! Don clean vinyl gloves. Remove inlet and outlet plugs from an unused 0.8 μ, 37

mm mixed cellulose ester filter cassette. Mount the filter cassette to the tripod mast

at breathing-zone height (approximately five feet above the floor). Attach the tygon

tubing to the sample media by inserting a nipple into the open end of the tubing (i.e.,

the end opposite of that attached to the sampling pump) and inserting the nipple into

the outlet opening of the cassette.

! Turn the sampling pump on and record the time.

! When sampling is complete, turn the sampling pump off and record the time. Cap

the inlet and outlet plugs of the cassette.

Paint Chip Samples

The protocol for collecting a paint chip at a sampling location is as follows:

! Don a clean pair of disposable leather gloves.

! Using a cutting tool, score the perimeter of the area to be removed.
4-11

! Affix a tray, paper funnel, or equivalent collection device directly below the

sampling location. Begin removing the paint from the substrate. If possible, peel

the paint off of the substrate by sliding the blade along the score and underneath the

paint. Remove all paint down to the bare substrate and transfer to the collection

container.

Plaster Samples

Samples are collected from painted surfaces to characterize lead levels in surfaces about to

be demolished or disturbed during renovation and remodeling activities. When collecting plaster

samples, the selection of the surface to be sampled is important. Deteriorated plaster can become

crumbly, increasing the potential for sample contamination. For example, when chipping into a

wall the plaster can easily become pulverized and fall to the floor. It is best to select a firm, rigid

surface and collect the plaster sample in accordance with the following steps:

! Don a clean pair of disposable vinyl gloves.

! Select the surface and area to be sampled (do not outline the sample area with any

type of marker, pen, pencil, etc.).

! Affix a tray, paper funnel, or equivalent collection device directly below the

sampling location. Note that because of the relative mass of the plaster compared to

the collection device, the person collecting the sample or an assistant may need to

support the device.

! Using a chisel and hammer, carefully break through the surface of the sample area.

! Begin removing the plaster by gently prying it away from the surface being sampled.

! Allow the plaster sample to drop into the collection device. As mentioned

previously, the collection device may need to be supported at this time.

! Carefully transfer the plaster sample from the collection device into a sample bottle. 

Cap the sample bottle.

4.6.2 Analytical Methods

Analysis procedures used in the EFSS study were as follows:

! Settled dust, vacuum samples: Digested using a modified version of EPA SW-846

Method 3050. Analyzed using a modified version of EPA SW-846 Method 6010A,

Inductively Coupled Plasma (ICP).
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! Settled dust, wipe samples: Digested using a modified version of EPA SW-846

Method 3050. Analyzed using a modified version of EPA SW-846 Method 6010A,

Inductively Coupled Plasma (ICP).

! Air, personal exposure samples: Digested and analyzed using a modified version of

EPA SW-846 Method 3050. 

! Air, area airborne samples: Digested and analyzed using a modified version of EPA

SW-846 Method 3050. 

! Paint chip samples: Digested using a modified version of NIOSH Method 7082. 

Analyzed using a modified version of EPA SW-846 Method 6010A.

Primary instrumentation for the analysis of vacuumed dust and dust wipe samples was an

Inductively Coupled Plasma—Atomic Emission Spectrometer (ICP-AES). A Thermo-Jarrell Ash

simultaneous ICP was utilized for this analysis effort. Primary instrumentation for the analysis of

personal exposure and area airborne samples was a Varian SpectrAA 300Z graphite furnace

atomic absorption spectrometer (GFAAS).

More details on the analytical method, including protocols, are provided in the study's

QAPjP.
5-1

5.0 OVERVIEW OF RECRUITMENT IN THE EFSS 

The study objectives and design, discussed in the preceding chapters, defined three basic

criteria for the recruitment process:

1. The workers monitored and the R&R activities performed must be typical of general

R&R work as it is currently being conducted.

2. The buildings undergoing R&R must be representative of typical target housing or

public and commercial buildings and must contain interior lead-based paint.

3. Recruitment and subsequent study procedures must meet all requirements specified

by EPA, Battelle, and MRI's Human Subjects Committees.

Reasons for the first criterion, including reasons for the decision not to monitor abatement

work, were presented in Chapter 2. The decision to monitor R&R workers conducting activities

typical of general unregulated R&R work was reinforced during the recruitment process;

contractors repeatedly expressed the opinion that R&R work being conducted by government

contractors who take extensive precautions against lead exposure is not representative of much of

the R&R work being conducted by R&R contractors focused on the private sector. Our

definition of "typical unregulated R&R work" did allow inclusion of a worker who takes personal

precautions during the R&R activity, such as wearing a respirator or protective clothing. 

However, we did not include dust reduction measures normally encountered in abatement work,

such as:

! Misting surfaces that will be disturbed

! Using plastic to enclose surfaces to be removed

! Using negative air or tools with HEPA vacuum attachments.

The second recruitment criterion was chosen to help focus the study on the most likely

environments for a lead exposure problem, while ensuring that buildings selected were not

atypical of the environments defined by the scope of the study. The screening of candidate

buildings included testing for lead-based paint using XRF methods and/or ICP analysis on paint

chip samples to measure lead concentrations (mg/cm ) on painted surfaces. The XRF testing was 2

intended for screening purposes only. Details on the minimum levels of lead-based paint required

for including a building in the study are presented in the QAPjP. In general, all sites included in

the study had extensive lead-based paint, and the XRF results were used along with other criteria

(such as the size and overall condition of the building) to choose between candidate sites. XRF

results were not used in any subsequent statistical analysis. Where measurement of the paint in

the substrate being disturbed was required, paint chip samples were collected at the time of the

R&R activity.

The third criterion, compliance with Human Subjects Committee guidance, affected

separate phases of the study differently. In the carpet removal and window replacement phases,

where R&R jobs already planned in the marketplace were being recruited, the primary Human
5-2

Subjects requirements were that the study not alter any of the work that was to be monitored and

that workers and residents sign approved informed consent forms. In the CED phase, on the

other hand, Human Subjects guidance required that the work be conducted by contractors with

experience in worker protection practices, an OSHA-certified respirator program in place, and

who agreed to follow the OSHA lead standard for the construction industry (29 CFR 1926.62). 

In addition, for the CED phase, buildings where the work was to be conducted were required to

be scheduled for subsequent demolition, gutting and complete restoration, or complete abatement

and clearance testing before reoccupancy.

Multiple approaches were taken in the attempt to recruit the "real-world" R&R

contractors and workers. These included newspaper ads, telephone solicitation, letters, flyers,

contact with unions, trade organizations, government agencies, and ongoing R&R programs, and

targeting schools and other institutions that were suspected to have reason to be interested in the

lead problem. A telephone script was composed that attempted to:

! allow R&R workers to understand the benefit of the study

! reduce their liability concerns

! stress that their participation would not disrupt the job or their normal work practice

in any way.

Attempts were made to recruit contractors directly as well as indirectly through the individuals

hiring the job or through union participation. Workers and contractors were offered

compensation for any inconvenience resulting from participation in the study.

Overall, recruitment of "real-world" non-abatement R&R jobs for participation in this

study was time consuming, cost intensive, and very problematic. The primary reasons for this

difficulty were:

1. Liability concerns. The fear of being held liable by workers, homeowners, the

public, EPA, OSHA, or NIOSH was the single biggest disincentive to participation

in the study. Very early in the recruitment process, one carpet removal contractor

told us "one lawsuit could put me out of business." This concern was repeated

often. Larger institutions often appeared reluctant to lose the protection that was

perceived to come with ignorance. The attempt to recruit the maintenance staffs of

several institutions was unsuccessful for this reason.

2. Negative reactions to EPA and OSHA. Many contractors expressed concerns that

their participation would result in either a fine from OSHA for working incorrectly,

or concerns about newly mandated requirements that they did not want or did not

feel were justified. The president of a window replacement firm with offices in

Wisconsin wrote,
5-3

"A concern I have with the methodology of your study, is that new Federal

rules will be formulated based upon your study. Your study as presently

designed is not representative of the type of window replacements we do. In

fact, the vast majority of window replacements are done without disturbing

the original window frame."

 

3. Contractors, agencies and individuals too busy to participate. Many individuals

we spoke with would not even take the time to fully listen to the description of the

study before stating, "I'm too busy and don't have time for this now." Contractors

who seemed receptive but too busy to talk at the time of the first call were sent a

letter describing the study and then called back at a later date. In general, first

refusals were seldom converted by a letter or a follow-up phone call.

4. Difficulty in recruiting a "contracted job." A unique challenge to this recruitment

effort was that it was not single individuals or organizations being recruited

ultimately but rather contracted R&R jobs. This required coordination and

recruitment of two parties and the ability to firmly determine schedules so sampling

could be arranged. The inconvenience involved was often perceived by those

recruited to outweigh any advantages to participation including the compensation

offered.

5. No match for the unit or work requirements. Many contractors did not work in

the older buildings (>50 years old) we required or did not meet phase-specific

requirements such as full replacement of wood windows.

6. Failure to find lead-based paint after a building was recruited. In the recruitment

of large R&R projects and potential CED sites, a high ratio of buildings screened did

not contain appreciable amounts of lead-based paint. Six units that were eventually

used in the CED phase had sufficient interior lead-based paint, but seven other units

that were more than 50 years old did not contain sufficient lead-based paint

anywhere in the interior of the building.

The recruitment difficulties led to more emphasis on the CED phase of the study where

the recruitment effort became one of locating vacant buildings and cooperative owners rather than

willing contractors. Details of the recruitment process, results obtained, and lessons learned are

presented below. 

5.1 DETAILS AND RESULTS OF THE RECRUITMENT PROCESS

The details and results of the recruitment process are presented below for each of four

study phases, in chronological order. Results of one phase were used to formulate the strategy

and effort for subsequent phases. 
5-4

5.1.1 Carpet Removal

The first four homes in the carpet removal phase were located in the Oakland, California,

area. They were selected through cooperation of the Alameda County, California, Planning

Department, Housing and Community Development Program. The four dwelling units were

already scheduled for lead-paint abatement with removal of the carpets planned as the first activity

in the abatement process. The Alameda County agency also provided floor plans and existing

XRF sampling results for these units. Representatives of the study field team visited each unit to

perform a visual survey and found them adequate for study participation. 

The Alameda County agency also recruited the R&R contractor who performed all carpet

removal activities for the four units. The contractor was subject to regulations imposed by

Alameda County in such areas as waste disposal, worker safety, and contamination control of

residential belongings. There was no requrirement specifically to minimize dust generation (e.g.,

misting the carpet).

The attempt to select four additional homes in another city proved much more

problematic. Initially, contractors advertising in St. Louis and Kansas City, Missouri, were

contacted by phone. They all declined to participate in the study, primarily due to liability

concerns. Next, fliers were placed in home-improvement stores and government agencies and

trade union representatives were contacted. Finally, newspaper advertisements were placed in St.

Louis newspapers offering an incentive to homeowners replacing their own carpet, and providing

a toll-free number to call.

This last recruitment step provided additional candidate homes rather easily. The

homeowners did not express anything in the way of liability concerns, fear of EPA, NIOSH, or

OSHA, or conflicting business interests. Also, the homeowners considered the monetary

incentive as a positive motivating factor, while the contractors considered it insignificant. 

Recruitment of resident-workers enabled the study to include data on carpet removal performed

by nonprofessionals. The candidate homes were classified according to the following criteria:

! Age of dwelling unit (priority given to homes built before 1940)

! Availability of dwelling unit to the study

! Length of time since carpet was installed (priority given to carpet in place for at

least 8 years)

! Lead-based paint in the dwelling unit (unit has not recently undergone lead

abatement).

Study recruiters narrowed the field to eight promising candidates, and the field team and an XRF

contractor performed XRF and visual surveys during scheduled screening visits. Based on the

findings of the screenings, study statisticians then selected four units for the study.
5-5

5.1.2 Window Replacement

The initial approach to identify and recruit individuals performing window replacement

work or having this type of work done in their homes was to place advertisements in newspapers

in Baltimore, Maryland, and St. Louis, Missouri. The EPA-approved ads described the study,

solicited participants (homeowners or contractors), offered an incentive, and listed a toll-free

number to call. This method of recruiting was abandoned rather quickly because there was

virtually no response. In contrast to the carpet removal phase, no homeowners performing the

work themselves were uncovered.

The next step was telephone soliciation by trained recruiters using an EPA-approved

script. They solicited window installation companies and contractors in thirteen selected U.S.

cities. The cities were Baltimore, Hartford, Boston, Columbus, St. Louis, Youngstown, New

Haven, Washington D.C., Newark, Cincinnati, Chicago, Milwaukee, and Cleveland. Most

companies and contractors contacted were listed in municipal telephone directories. Additional

contacts included trade organizations, unions, large and small licensed window installation firms,

independent contractors, business owners, and home owners. Although this recruitment

technique yielded the largest number of contacts (more than 800), it was largely unsuccessful.

Only five individuals were willing to participate in the study: three contractors and two

building owners. All five were located in Columbus, OH; our assessment is that all five were

influenced to participate in the study because of Battelle's involvement in the study and their

reputation in the Columbus area. In fact, one of the window installation companies, which

located two of the four homes eventually enrolled, wanted to participate so that it could advertise

its participation in a study with Battelle as a way to enhance business. 

The four homes eventually selected for the study were identified by three professional

contractors as candidate study units. Two contractors were general building contractors, and one

was a specialized window removal/installation contractor. Representatives of the field sampling

team visited each eligible unit to conduct a visual survey and to supervise an XRF screening of

painted window components. Information from this screening visit was used to determine

whether the unit would be selected for the study, and if so, which of three windows would be

considered for environmental sampling. The four study units were located in the Ohio cities of

Piketon, Columbus, Richwood, and Plain City.

5.1.3 Large Projects

From a design perspective, there was significant interest in obtaining a large R&R project

involving multiple activities conducted simultaneously. A sampling plan was developed for

monitoring such a project. However, this project could not be accomplished in the time frame

available to the study.

The recruitment effort for finding a large R&R project was extended to the following

potential candidate sources:
5-6

1. Large public facilities such as hospitals, universities, and schools

2. Military bases and state and federal agencies controlling government buildings

3. Solicitation of help from national trade unions.

In general, individuals contacted for the large R&R project were more receptive than

those contacted in the window replacement recruitment effort. Most quickly understood the

study and were in agreement with its purpose. However, a major problem for almost all large

R&R projects was that final approval for participation did not rest with a single individual or

department. Typically, several levels of approval were required including that of the legal, health

and safety, and facilities departments.

For example, one month-long solicitation of a large university had resulted in approvals

from the Environmental Safety and Health Department, university lawyers, and Board of

Trustees, but a lack of final approval because of the concerns and narrower interests of the

Facilities Department. In large institutions, including universities, there appears to be concern

about disclosing a lead problem.

Trade unions cooperated in recruitment efforts to identify eligible jobs and contractors. 

The United Brotherhood of Carpenters (UBC) alone sent over 2,000 letters to its local chapters

and district councils soliciting their help in locating jobs. The only solid prospect from this effort

was a seminary in Ohio. Although the seminary was more than 60 years old, no lead paint was

found in the interior. 

Failure to locate a suitable large project led the project team to abandon the effort in favor

of the use of hired contractors performing simulated R&R work in the CED phase.

5.1.4 CED Phase

Recruitment for the CED phase was more successful than recruitment of "real-world"

jobs. The fact that contractors would be hired to do the work meant that basically only vacant

buildings needed to be found. Public housing authorities, government and private agencies were

willing to offer candidate buildings. Although many buildings were not suitable because they

were too deteriorated, sufficient numbers of vacant, but habitable buildings were located for the

CED phase. This phase of the study was conducted in Baltimore, Maryland, and Denver,

Colorado.

In Baltimore, a number of row houses scheduled for "gut rehab" were recruited from a

private developer. During initial site visits, some of the dwellings were determined to be in such

poor condition that they could be excluded from the study. Three buildings were in habitable

condition, but one was found to contain an insufficient amount of lead-based paint during the

XRF screening. The other two were enrolled in the study. The contractor employed in Baltimore

met all study requirements and had many years of general construction and R&R experience

before concentrating on lead abatement work.
5-7

Buildings in Denver were recruited through the cooperation of Denver Housing Authority

(DHA). This agency identified eligible vacant buildings scheduled for subsequent abatement or

"gut rehab." CED activities were conducted in four different buildings. All activities were

conducted by DHA maintenance staff with experience in general R&R tasks as well as in lead

abatement.

A summary of the recruitment effort and results for each phase of the EFSS is presented in

Table 5-1. 

5.2 GENERAL CHARACTERISTICS OF THE WORKERS AND UNITS RECRUITED

This section presents a general description of the workers and buildings (units) included in

the three phases of the EFSS. Further details on specific unit characteristics for a given study

phase are included in Chapter 8.

5.2.1 Worker Characteristics

The workers performing R&R activity in the EFSS differed in many aspects, including

experience in performing the activity, awareness of potential lead hazards associated with the

activity, and the level of protection from exposure. Following the R&R activity at each study unit

in the carpet removal and window replacement phases, field team representatives interviewed the

R&R workers to characterize the type of worker participating in this phase. The worker survey

collected information on such items as experience level, familiarity with the hazards associated

with lead exposure, and opinion on how typical the activity has been at a site compared to similar

jobs. Results of this survey were used only to characterize the workers participating in this study. 

They cannot be used to make inferences on the general population of R&R workers. 

Carpet Removal

In the carpet removal phase, the four Alameda County, CA, units had professional carpet

removal workers who were employees of an R&R contractor with experience in dealing with

environmental hazards such as lead contamination. Approximately 25% of the R&R jobs

performed by this contractor involved carpet removal, and approximately 30% of the jobs

consisted of lead-based paint abatement. In this study, the contractor's employees wore Tyvek

suits and respirators when performing carpet removal in each unit. The workers were aware of

various precautionary measures to reduce dust generation, although the only such measure taken

in this study was using plastic sheeting to cover occupant belongings and seal off nonactivity

areas. 

The owner of the contracting company in Alameda County, who had more than 35 years

of R&R experience, participated in carpet removal in one unit and was monitored for personal

exposure. The four other workers for this contractor had from 3 months to 15 years of

experience in R&R and in carpet removal specifically. 
5-8

Table 5-1. Summary of Recruitment Efforts and Results in the EFSS

Carpet Removal Phase

Target for No. of

Recruitment Method Contacts Results

Government agencies Personal and inter-organizational contacts;

and contractors telephone calls >10 4 units

Contractors Telephone calls with predetermined script >100 No success

Contractors N/A No success Fliers posted in retail outlets frequented by

R&R contractors

Homeowners 4 units Newspaper advertisements with cash Ads placed in

incentive two cities

Window Replacement Phase

Government agencies >10 Personal and inter-organizational contacts; for nontelephone calls abatement

No success

work

Contractors or Newspaper advertisements with cash Ads placed in

homeowners incentive two cities No success

Contractors >800 4 units Telephone calls with guided script and

follow-up letters

CED Phase

Government agencies All required

and special interest >10 units

groups obtained

Personal and inter-organizational contacts;

telephone calls

Universities, hospitals,

government agencies Telephone calls with guided script >50 Several leads

Large R&R Projects(1)

Government agencies for nonand trade unions abatement Personal and inter-organizational contacts >20

No success

work

Universities, hospitals, Telephone calls with guided script and

contractors follow-up letters >400 No success

Workers/contractors No success Letters sent to locals of United Brotherhood >2000

of Carpenters letters

 This study phase could not be accomplished in the time frame of this study. (1)
5-9

In contrast, the carpet removal workers in the four St. Louis, MO, area units were all

nonprofessional residents or helpers. The residents usually had no previous awareness of

potential lead exposure in performing carpet removal, and they only had informal previous

experience in performing R&R activities. Only two resident-workers in one unit identified

themselves as ex-R&R professionals or self-employed professionals, with less than 15% of their

experience in carpet removal and no experience in lead decontamination areas. Therefore, the St.

Louis workers were less experienced in performing carpet removal activity and in handling

potential lead contamination resulting from the activity.

Window Replacement

Workers participating in the window replacement phase were professional contractors

experienced in window replacement. The workers in three of the four study units claimed that

window replacement was the only R&R activity they performed, while the workers in the fourth

unit claimed that window replacement activities constituted 50% of their R&R work. The R&R

experience of the workers ranged from 1.5 to 27 years. Window replacement experience ranged

from 1.5 to 16 years. 

None of the workers in the window replacement phase had any experience in abatement

work. Only two workers at one unit claimed to be aware of any potential risk for lead exposures

during window replacement; none of the workers took any precautions to reduce lead exposure.

CED Phase

Unlike the carpet removal and window replacement phases, contractors in the CED phase

were hired by the EFSS study team to perform the specified activities at a study unit. All workers

in the CED phase were professional lead abatement workers. Full worker precautions were

taken, but no effort was made to reduce dust generated by the activity. The contractors were

instructed to do the assigned jobs in a manner typical of general R&R work in an unregulated

environment. 

5.2.2 Unit Characteristics

All eight study units in the carpet removal phase were occupied, single-family residences. 

Carpet removal was performed in a portion of a given unit. Two of the four units in the window

replacement phase were occupied single-family residences. The other two units were occupied,

but the floors on which the window replacement activity took place had been vacant and

neglected for some time. The CED phase included two vacant row houses in Baltimore,

Maryland, and four single-family homes in Denver, Colorado. All units in the CED phase were

scheduled for demolition, abatement, or gutting/restoration in the near future.

The study units had varying degrees of lead paint contamination and differed in their

overall observed levels of cleanliness. In addition, the amount and type of dust generated during a

specific R&R activity often differed from one unit to another. For example, workers in one unit

of the carpet removal phase reported excessive dust generation from disintegrated carpet padding,
5-10

while carpet in another unit contained considerable surface debris. The discussion of results for

each phase in Chapter 8 presents additional details and demographic information on the study

units.

5.2.2.1 Comparability with Units from Previous Studies

This section compares the pre-activity lead levels of the recruited study units in the carpet

removal and window replacement phases to the pre-activity lead levels in other studies. Table 5-2

contains summaries of dust-lead loadings across EFSS units as well as for units from other

studies. Lead loadings are from dust samples collected from floors, window sills, and window

wells. Besides the carpet removal and window replacement phases, the following studies are

represented in Table 5-2:

! The HUD Abatement Demonstration Study (U.S. Dept. of HUD; 1990)

! The HUD National Survey of Lead-Based Paint in Housing (U.S. EPA, 1995)

! Two Kennedy-Krieger studies on abatement/maintenance methods (Farfel and

Chisolm, 1990; Farfel and Chisolm, 1991).

The HUD Abatement Demonstration ("HUD Demo") Study assessed the costs and shortterm efficacy of alternative methods of lead-based paint abatement. A total of 172 dwelling units

in seven metropolitan areas were abated in the FHA portion of the HUD Demo study. The HUD

Demo statistics in Table 5-2 represent loadings from wipe samples taken in these units as part of

post-abatement clearance procedures.

The HUD National Survey estimated the incidence of lead-based paint in U.S. public and

privately-owned housing. Table 5-2 includes statistics on lead loadings from 182 privately-owned

units from the National Survey, partitioned into two groups according to lead levels from XRF

testing.

The Kennedy-Krieger Institute studies examined the effect of different types of

abatement/maintenance methods on dust and blood lead levels. In the first study, 53 units were

earmarked for traditional abatement practices and 18 for modified abatement practices. These

units had multiple interior surfaces with lead-based paint and at least one child with elevated

blood lead levels. The second study considered experimental abatement practices in six older row

homes with multiple lead-based paint hazards. In Table 5-2, the geometric means of preabatement lead loadings for the Kennedy-Krieger studies are summarized for three groups of units

in the following order: traditional practice units, modified practice units, and experimental

practice units.
5-11

Table 5-2. Descriptive Statistics for Pre-Activity Lead Loadings on Floors, Window Sills,

and Window Wells in the EFSS, with Comparison to Levels Observed in

Previous Abatement Studies

Study # Samples Dev. (μg/ft ) (μg/ft ) (μg/ft ) (1)

Log Std. 25th Percentile Geometric Mean 75th Percentile 22 2

Floor Dust Lead Loadings

EFSS Carpet Removal Phase 32 1.91 2.61 14.7 49.0

EFSS Window Replacement Phase 39 3.26 28.4 637 9,120

HUD Demonstration 1026 1.53 23.6 66.0 185

National Survey(2) High XRF 234 1.82 0.70 2.40 8.23

Low XRF 304 1.61 0.22 0.64 1.91

Kennedy-Krieger studies 82 288 (3)

280 251

70 520

Window Sill Lead Loadings

EFSS Carpet Removal Phase 16 2.32 88.8 418.0 2740

HUD Demonstration 783 1.79 26.7 89.10 297

National Survey(2) High XRF 123 2.64 1.42 8.40 49.7

Low XRF 126 2.13 0.37 1.57 6.59

Kennedy-Krieger studies 95 1,800 (3)

249 1,340

34 4,610

Window Well Lead Loadings

EFSS Window Replacement Phase 11 0.94 54,700 135,000 296,000

HUD Demonstration 756 1.93 138 506 1,860

National Survey(2) High XRF 56 2.28 47.4 220 1,020

Low XRF 38 2.46 3.27 17.2 90.4

Kennedy-Krieger studies 37 18,300 (3)

150 15,500

28 29,400

Data for the EFSS phases reflect all regular and QC side-by-side samples collected prior to R&R activity. (1)

HUD Demonstration data represent post-activity clearance results for units in the FHA portion of the study.

"High XRF" entries reflect readings for units with at least one interior and one exterior XRF reading (2)

exceeding 10 mg/cm . "Low XRF" entries reflect readings for units where all XRF readings were below 1.0 2

g/cm .2

The first two entries in each cell reflect pre-abatement readings from homes where traditional and modified (3)

abatement procedures, respectively, were to be employed (Farfel and Chisolm, 1990). The third entry in

each cell reflects pre-abatement readings in units from Farfel and Chisolm, 1991.
5-12

Compared to units in the HUD Demo study, the units in the carpet removal phase had

generally lower lead loadings in floor dust, but higher lead loadings in window sills. The units in

the window replacement phase had higher lead loadings in floor dust, and much higher lead

loadings in window wells. It should be noted, however, that all floor samples collected in the

window replacement phase were within 6 feet of a window, possibly accounting for the high lead

loadings from floors. Also, the data for the HUD Demo study primarily represented post-activity

sampling after cleanup procedures.

The two EFSS study phases had considerably higher lead loadings than National Survey

units. However, the "blue nozzle" vacuum sampler used to collect dust samples in the National

Survey was shown to be approximately five times less efficient than the wipe and vacuum

sampling techniques used in the HUD Demo and the EFSS. Consequently, reported results may

be lower than what would have been observed using more efficient sampling techniques.

The Kennedy-Krieger results are higher than all other study results except those from the

window replacement phase. 

In general, the variability observed was similar across all studies. From Table 5-2 one can

conclude that the observed lead levels in carpet removal units were not atypical of inhabited units

with lead contamination. Units included in the window replacement phase, on the other hand, had

relatively high levels of pre-activity lead contamination, especially in the window wells. These

levels were high in both the vacant and occupied activity areas.
6-1

6.0 DATA ANALYSIS OVERVIEW

As introduced in Chapter 1, the technical objectives of the R&R study were to characterize

lead exposure to workers conducting R&R activities in contaminated housing, investigate how

these workers disturb lead and create a lead-based paint hazard to occupants or other exposed

individuals, and provide technical input and recommendations for developing guidelines and

regulations on lead exposures resulting from R&R activities. This chapter presents an overview

of those data analysis objectives and approaches that were consistent across the EFSS phases and

that addressed these technical objectives. 

6.1 DATA ANALYSIS OBJECTIVES

Data summaries and statistical analyses were centered around data analysis objectives

established for the EFSS. The data analysis objectives address the overall objectives of the EFSS

(presented in Chapter 1). The study phases shared many of the same data analysis objectives. 

These objectives are categorized below according to the goal which they satisfy.

A. Characterize Lead Disturbance and Potential Lead Exposure

! Characterize average personal exposure levels of airborne lead for workers over the

duration of a given R&R activity and determine if these levels exceed 50 μg/m (the 3

OSHA Permissible Exposure Limit (PEL))

! Characterize lead loadings and concentrations within samples of dust that settles on

flat surfaces (e.g., floors, window sills) within a specified period during and following

completion of R&R activities.

Carpet removal and window replacement phases only:

! Characterize airborne dust lead levels in rooms adjacent to "activity rooms" (rooms

in which the R&R activity occurs) while the activity is in progress.

In a separate evaluation:

! Determine the effect that typical cleanup procedures have on lead loadings in settled

dust that remains following the activity as a lead exposure to occupants.

B. Assess Factors or Measurements Related to Lead Disturbance

! Characterize the extent to which lead disturbance and exposure are affected by

indicators of lead contamination in the dwelling unit, extent of exposure to the

activity, and building characteristics. (Depending on the study phase, indicators

include lead loadings in settled dust existing prior to the start of activity, available

lead loadings on painted surfaces disrupted by the activity, distance of sample

location from the activity, type of substrate disturbed, and elapsed time in which the

activity took place.)
6-2

! Quantify the components of total variability in lead measurements taken within

samples of various media. (Variance components could constitute variability

attributable to sampling across different dwelling units, sampling from different

locations or workers within the same unit, or sampling from different areas within the

same location.)

The following data analysis objectives, grouped as a third category, were devised to provide

information to aid in the design and development of future lead exposure studies: 

C. Evaluate Different Media and Methods as Indicators of Lead Exposure

Carpet removal and window replacement phases only:

! Compare settled dust lead loadings on stainless steel dustfall collectors (SSDCs)

introduced prior to the start of activity with baseline-adjusted settled dust lead

loadings directly from the floor surface

! Compare lead loadings from settled dust samples collected one hour following

completion of activity with loadings from samples collected at two hours following

completion of activity

! Compare lead loadings from settled dust samples collected using vacuum techniques

with loadings for samples collected using wipe techniques

! Examine correlations between lead measurements among different collection media.

CED phase only:

! Investigate the potential for cross-contamination between activities.

Data analyses addressing the first three objectives within Category C provide information to

evaluate competing sampling methodologies as presented and analyzed in Chapter 7. The

remaining objectives are addressed by the analyses presented in Chapter 8 for each R&R activity.

6.2 APPROACH TO DATA ANALYSIS

Most of the data analysis objectives and the approaches taken to analyzing the data were

consistent across the study phases. Data analysis in the EFSS was centered on characterizing the

distributions of lead levels in various media affected by each of the target R&R activities. 

Variability in lead measurements was characterized as a function of sampling from different units,

from different locations/workers with a unit, and from different areas within the same location. 

The extent of correlation present between lead loadings in settled dust and personal/ambient air

lead levels, and between lead exposure and building and activity characteristics, was investigated. 

All statistical analyses and data summaries were performed using Versions 6.03 and 6.08 of the

SAS System. ®
TLA ' total lead across all cassettes at a unit for a worker

(duration of task)@(flow rate)

6-3

Lead levels as determined from analytical methods performed on the environmental field

samples were expressed in terms of loadings and/or concentrations. For personal air and ambient

air cassette samples, lead levels were expressed as concentration of lead per cubic meter of air

sampled (μg/m ). For each settled dust sample, lead loadings expressed the amount of lead (μg) 3

per unit area (square foot) sampled. For the purposes of this study, dust lead loading provides a

measure of the total amount of lead disturbed in a specified area by the studied R&R activity. For

vacuum dust samples, lead concentration was also reported, representing lead amounts (μg) per

unit weight (g) of dust. However, while lead concentration in dust provides information to

characterize the nature of the exposure and to provide insight into appropriate avoidance or

cleanup practices, concentration data provide no indication of the total amount of lead disturbed

by the activity. Because the primary objective of the study was to characterize the amount of lead

disturbed and the potential human exposure associated with an activity, loadings were emphasized

in the statistical evaluation of lead disturbance in each phase of the EFSS. For settled dust

samples, statistical comparisons and modeling were performed on loadings, while only data

summaries were performed on concentrations and physical sample weights. For personal and

ambient air samples, statistical analysis was performed on the reported lead concentrations.

Personal exposure monitoring during R&R activity provides data on the amount of lead per

volume of air sampled within the breathing zone of a monitored worker. These data represent

average exposures over the duration of an activity period and are referred to in this document as

task-length averages (TLA) (in μg lead per cubic meter of air). Exposure data are calculated from

the amount of lead collected within the sample cassette(s), the duration of monitoring, and the air

pump flow rate. The TLA for a worker performing a given R&R activity at a study unit is

calculated as follows:

This approach to calculating the TLA for personal exposure monitoring was followed in each

study phase of the EFSS.

6.2.1 Common Approaches Taken Within Each Study Phase

Log Transformations

Throughout the EFSS, analysis of lead loading or concentration data was performed after

taking a natural-logarithm (or "log") transformation of the data. In many standard statistical

inference procedures, the assumption of normally distributed data is necessary to make accurate

inferences on the central tendency and variability within the data distribution. In this setting, lead

loadings and concentrations appeared to originate from skewed distributions. The arithmetic

mean is heavily influenced by large data values in the upper tail of the distribution, and therefore

may not be an appropriate representation of the central tendency of the data. However,

distributions of the log-transformed data more closely resembled a normal distribution (as

determined through normal probability plots and results of the Shapiro-Wilk test for normality). 
6-4

In such a situation, if the arithmetic mean of the log-transformed data is calculated and then

exponentiated, the result (called the "geometric mean") is an estimate of the median of the

distribution of untransformed data. Thus, due to lognormality, the geometric mean is an estimate

of the central tendency of the distribution and is more robust to outliers than the arithmetic mean. 

As a result, summaries of lead loadings and concentrations within each phase are based on

geometric means and on variability associated with log-transformed data. These summaries,

which also include minimum and maximum observed data values, are presented in tabular form

within Appendix A.

Pearson Correlation Coefficients

The Pearson correlation coefficient was calculated to quantify the extent to which linear

relationships were present between a pair of measurements. Values of the correlation coefficient

close to one indicates a positive correlation, while values near -1 represent negative correlation. 

Statistical tests for nonzero correlation were executed to determine whether the coefficient differs

significantly from zero at the 0.05 level. 

Statistical Modeling

Statistical models were fitted to lead levels in various media to evaluate the effects of

external factors (called covariates) on these data. For example, models within the carpet removal

phase included the effects of pre-activity lead loadings in the carpet and on the floors. F-tests

were performed to determine whether specific covariates had statistically significant effects on the

modeled data at the 0.05 level. Statistical models were also fit that included exclusively random

effects, such as a dwelling unit effect, to determine the contribution to overall variability in the

study data which could be explained by these effects. Further detail on the approach to statistical

modeling is presented in Appendix C. In some instances, small numbers of data points restricted

the extent to which model effects could be characterized within statistical models.

Fitting linear statistical models to log-transformed data affects how the modeling results are

interpreted relative to the untransformed data. In this study, the modeled data (i.e., logtransformed data) are expressed as a linear combination of fixed and random factors. Therefore,

the models are considered "additive" models relative to the log-transformed data. However, by

exponentiating both sides of the model equation, one sees that the models express the

untransformed data as a multiplicative function of the model effects. That is, the effect of a single

factor is measured by its multiplicative influence on the untransformed data, and comparisons

among factor effects are expressed in terms of ratios of geometric means rather than as

differences in arithmetic means.

Boxplots

In each study phase, results of data analysis were summarized in tabular and graphical form. 

Graphical displays were used to ease interpretation and comparison among sample types. Twodimensional scatterplots illustrate correlations present among pairs of measurements and portray
6-5

Figure 6-1. Example of a Boxplot

data values across the study by study unit and location within unit. Boxplots display percentiles

and other statistics, as well as extreme data points, in the form presented in Figure 6-1.

The lower and upper limits of the "box" portion of the boxplot represent the 25th and 75th

percentiles, respectively, of the observed data distribution. The length of the box represents the

data's interquartile range (IQR), or the difference between the 25th and 75th percentiles, which is

an indicator of data variability. The horizontal line within the box is the 50th percentile, or

median. The diamond symbol is the arithmetic mean. Vertical lines extend from the top (or

bottom) of the box to the value of the most extreme data point which falls within 1.5 IQRs from

the box. Each data point extending from 1.5 to 3.0 IQRs from the box is plotted with a "+"

symbol, while each data point extending beyond 3.0 IQRs from the box is plotted with a "*"

symbol.

6.2.2 Estimating Lead Disturbance in a 6' x 1' Gradient Region

In this study, a statistic was developed to characterize lead disturbance (and potential

exposure to occupants) associated with a specific R&R activity. Taking into account the

relationship between the amount of lead in the environment and the distance from the activity, this

statistic estimated the amount of lead exposed (or disturbed) along a 6-foot line (lead gradient)

emanating from the activity source. For each activity, a statistical model (Lead = "e ) was ß@distance

fitted to express lead levels in settled dust as a function of distance from activity. Details on the

model fitting process are provided in Section C.5 of Appendix C. An example of the fitted model

is given in Figure 6-2.
6-6

Figure 6-2. Portrayal of Model Predicting Lead Exposure as a Function of Distance from

R&R Activity

From this model, lead exposure for an activity is quantified by calculating the area under the

fitted curve from 0 to 6 feet from the activity. This measure represents an estimate of the amount

of lead present in a 6-foot by 1-foot column extending from the activity (Figure 6-2). Throughout

the report, this measure will be referred to as the amount of lead in a 6' x 1' gradient region. The

6-foot distance was selected based on distance considered in the sampling design. For each

activity, uncertainty in the amount of lead within a 6-foot by 1-foot column was expressed by

calculating an approximate 95% confidence interval on the estimated amount.

Two alternative calculations to characterizing lead disturbance and potential exposure to

occupants were considered but not implemented in this study: 1) a weighted combination of

estimated lead amounts at one and six feet from the activity, and 2) total volume of lead exposed

within a hypothetical (6 by 12 foot) area adjacent to the activity. The development of a 

weighting scheme for the 1- and 6-foot estimates involved assumptions about potential cleanup

activities and occupant behavior. For example, is a greater exposure potential posed by lead six

feet away from the activity than lead one foot away? Given the limited existing information upon

which to base such assumptions, this calculation was rejected. The total volume measure would

have provided an interesting measure of lead exposure but required assumptions about the

character of the dust dispersion resulting from the activity. For example, would dust generated by

sawing through plaster disperse symmetrically from the cutting area? What would be the shape of

the response surface that would characterize dispersion over a two-dimensional area? Since the
6-7

EFSS was not designed to assess such questions, these assumptions would have been based on

field experiences and mathematical convenience, and therefore this estimation scheme was

rejected. 

6.2.3 Significant Digits 

Laboratory results from the chemical analyses of samples collected in this study were

reported to five significant digits. However, the precision of most analytical methods employed in

the analyses would suggest that the analytical data have less than five significant digits. 

Therefore, all results in this report are reported to three significant digits. Descriptive statistics

and results reported in tables in the Appendices present all digits as calculated.
7-1

7.0 METHODOLOGY ISSUES AND RESULTS

As discussed in Section 4.3, the method used in the EFSS for obtaining settled dust samples

from floors differs from the standard "pre- versus post-activity sample" method taken in previous

studies. In the EFSS, stainless steel dustfall collectors (SSDCs) were placed on the floor

immediately before the start of an activity, and a single dust sample was collected from each

SSDC at specified time points following conclusion of the activity. An investigation was

conducted to evaluate the different approaches to collecting dust samples, relative to their ability

to recover and estimate lead loadings in settled dust. This chapter presents the findings of this

evaluation.

Section 7.1 compares lead loadings from SSDC dust samples versus those from paired dust

samples taken via the standard method of sampling directly from the floor surface (post- minus

pre-activity). Section 7.2 evaluates the amount of time necessary to allow lead-dust to settle

following conclusion of the activity before sample collection. Lead loadings of SSDC samples

collected via vacuum techniques are compared to those collected via wipe techniques in Section

7.3. Finally, Section 7.4 addresses differences in lead loadings between adjacent ("side-by-side")

samples, and how these differences may indicate whether taking the first sample unduly influences

the outcome associated with the second sample.

7.1 STAINLESS STEEL DUSTFALL COLLECTORS VS. POST- MINUS PRE-ACTIVITY FLOOR

DUST METHOD

In the carpet removal and window replacement phases of the EFSS, two competing

approaches to measuring the lead disturbed by the R&R activity were compared. Both

approaches yielded estimates of lead levels in dust that settled on floors during the activity and up

to one hour following the activity's completion. The protocols for the sampling approaches, both

employing vacuum dust sampling techniques, were as follows:

! Post- minus pre-activity floor: Collect two samples directly from the floor surface,

where one sample was taken immediately prior to start of the activity (baseline) and

the other was taken at one hour following the activity's conclusion from an area

adjoining the first sample area. Dust lead levels are estimated by subtracting the preactivity result from the post-activity result.

! Stainless steel dustfall collectors (SSDC): Place a clean, uncontaminated SSDC on

the floor surface immediately prior to start of the activity, and collect one dust

sample from the SSDC surface at one hour following the activity.

The first sampling approach (floor dust) has been taken in a number of previous programs to

measure settled dust levels resulting from some activity. The second approach (the SSDC)

addresses the same objective, but does not require an adjustment for a baseline level, thereby

using only one dust sample rather than two to estimate lead levels. For this reason, it was

expected that variability attributable to spatial trends and biases, sampling, and analysis would be

reduced by use of the SSDCs. 
7-2

Figure 7-1. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples 2

Versus the Difference in Loadings Between Post-Activity and Pre-Activity Floor

Dust Samples in the Carpet Removal Phase

In both the carpet removal and window replacement phases, each sampling location

containing a SSDC for post-activity dustfall sampling also contained two one-square-foot areas

for pre- and post-activity floor dust sampling. Plots of the SSDC lead loadings versus the postminus pre-activity floor dust loadings at the same location indicate that loadings from the postminus pre-activity floor dust method cover a much larger range than the SSDC lead loadings. 

The plot for carpet removal is shown in Figure 7-1. Figures 7-2 and 7-3 show the plot for

window replacement samples collected at zero feet and six feet from the window, respectively. 

Figures 7-1 and 7-3 show the large discrepancy in the variability between SSDC and floor

samples. The range of post- minus pre-activity floor loadings required the horizontal axes of

these plots to be broken to more clearly illustrate all the data.

Additional plots of the observed SSDC sample loadings and post- minus pre-activity floor

loadings are found in Figure 7-4 for carpet removal and Figures 7-5a and 7-5b for window

replacement. These plots illustrate the difference in magnitude of variability between the two

sampling methods on a unit-by-unit basis. It should be noted that the variability observed in the

EFSS for side-by-side floor samples is similar to what has been observed in previous studies. 

EPA's Comprehensive Abatement Performance Study (CAPS) (Battelle, 1994) estimated the log

standard deviation of for floor side-by-side sample loadings to be 0.93, similar to that observed in

the EFSS. NIOSH's Ohio University study reported coefficients of variation over 50 percent for

side-by-side wipe samples, again indicating high expected variability (NIOSH, 1993). Moreover,

from a statistical standpoint, it is expected that variability would be reduced when using the SSDC

methodology, since the SSDC method involves the variability of a single measurement
7-3

Figure 7-2. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples 2

Versus the Difference in Loadings Between Post-Activity and Pre-Activity Floor

Samples Taken Zero Feet from the Windows in the Window Replacement Phase

Figure 7-3. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples 2

Versus the Difference in Loadings Between Post-Activity and Pre-Activity Floor

Samples Taken Six Feet from the Windows in the Window Replacement Phase
7-4

Figure 7-4. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, and 2

the Difference in Loadings Between Post- and Pre-Activity Floor Dust Samples in

the Carpet Removal Phase

Figure 7-5a. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, 2

and the Difference in Loadings Between Post- and Pre-Activity Floor Samples,

Collected at Zero Feet from the Windows in the Window Replacement Phase
7-5

Figure 7-5b. Lead Loadings (μg/ft ) for 1-Hour Stainless Steel Dustfall Collector Samples, 2

and the Difference in Loadings Between Post- and Pre-Activity Floor Samples,

Collected at Six Feet from the Windows in the Window Replacement Phase

rather than the additive variability of a linear combination of two measurements. The SSDC also

eliminates the possibility of negative values (post minus pre) that can occur with side-by-side

samples but are not reasonable estimates of the amount of lead disturbed by an activity.

Preference for using the SSDC approach over the post- minus pre-activity floor approach is

further supported by the high linear correlation between the lead loadings from SSDC dust

samples and the lead concentrations from worker personal air samples. A correlation of 0.98 was

observed between these two measurements in the carpet removal phase, and a correlation of 0.94

was observed in the window replacement phase. Both correlations were higher than the

corresponding correlations between personal exposure concentrations and post-activity floor

loadings. These findings, presented in more detail in Chapter 8, support the hypothesis that the

SSDC approach yields a better measure of the lead disturbed by the R&R activity than the postminus pre-activity floor approach. 

In summary, the SSDC methodology was judged to be superior to the post- minus preactivity floor sample approach for the following reasons: 

1. The SSDC method exhibited less variability, consistent with expectations from

previous experience and statistical theory.

2. The SSDC method does not produce negative estimates of the amount of lead

disturbed by an activity.
7-6

For these reasons, a decision was made to base estimates of the amount of lead disturbed by a

specific R&R activity on the results of samples taken from SSDCs. As a result of this decision,

only the SSDC method for estimating the lead generated by an R&R activity was used in the third

phase of the EFSS, the Controlled Experimentally-Designed (CED) phase.

7.2 STAINLESS STEEL DUSTFALL COLLECTORS: COLLECTING SAMPLES 1 HOUR VS. 2

HOURS AFTER R&R ACTIVITY

When defining the post-activity settled dust sampling approach, the study team had limited

information available in assigning a wait time to allow sufficient fallout of lead dust prior to

sample collection. Preliminary calculations based on particle physics indicated that roughly 90%

of lead particles greater than five μm that are disturbed as a result of R&R activity should settle

within one hour, even in turbulent air situations. As a result, the one-hour post-activity settled

dust sample from SSDCs was chosen as a reasonable indicator of lead disturbance in the R&R

study. However, it was of interest to test whether a one-hour wait was adequate, or whether

allowing a longer period of time for dust to settle would result in significantly higher lead

loadings. Therefore, at selected floor locations in the carpet removal and window replacement

phases, two SSDCs were placed side-by-side. One SSDC was sampled at one-hour post-activity,

and the other at two-hours post-activity. The lead loadings between the side-by-side samples

were compared to determine the magnitude of additional dustfall that occurs over a period of two

hours compared to one hour.

Figure 7-6 presents a scatterplot of the difference in loadings between the paired two-hour

and one-hour samples versus the difference in elapsed wait time between the two samples. Due to

the pace of the field activity and the number of samples collected, samples could not be taken

exactly at the time they were scheduled following the activity. At a given location, the difference

in elapsed wait times between the one-hour and two-hour samples ranged from 20 to 72 minutes;

most time differences ranged from 40 to 60 minutes. Figure 7-6 indicates no apparent increasing

trend in the differences in lead loadings as the difference in elapsed wait time increases (fitted

regression lines were not significantly different from the horizontal line at difference = 0). In fact,

the differences in sample results for three of the four sample pairs with the largest elapsed wait

times are close to zero. However, the plot does show that in 24 of the 36 paired samples (67%)

the two-hour sample loading is larger than the one-hour sample loading. In only one sample pair

does the one-hour loading exceed the two-hour loading by greater than 50 μg/ft , while the two- 2

hour loading exceeds the one-hour loading by greater than 50 μg/ft for ten pairs. Since an effect 2

of the exact sampling time cannot be detected, a simple categorical classification of results into

one-hour and two-hour samples was maintained.

Figure 7-7 is a log-log scatterplot showing the relationship between the paired two-hour

and one-hour lead loadings among the study units in the carpet removal and window replacement

phases. The solid line within the plot corresponds to equality between the two responses. This

plot further illustrates that two-thirds of the sample pairs had higher lead loadings for the twohour sample compared with the adjoining one-hour sample. This outcome supports the

hypothesis that loadings tend to increase during the additional hour wait. Based on the analysis of

pre/post floor dust samples, one might anticipate that much of the difference between the

adjoining one-hour and two-hour sample results is due to spatial variability. However, a strong 
7-7

Figure 7-6. Difference in Loadings Between Two-Hour and One-Hour SSDC Samples (TwoHour Minus One-Hour) Versus the Difference in Elapsed Wait Times Between

the Two Samples, for Carpet Removal (c) and Window Replacement (w) Phases

Figure 7-7. Two-Hour SSDC Lead Loadings Versus One-Hour SSDC Loadings for the Carpet

Removal (c) and Window Replacement (w) Phases
7-8

linear relationship, though not centered around the line of equality, was observed between the two

results in Figure 7-7. The Pearson correlation was 0.85 between the one- and two-hour lead

loading results (after taking logarithms). As a result, the extent of differences between adjoining

one- and two-hour lead loadings appears to be consistent across the range of observed data, with

higher readings associated with the two-hour results.

To further characterize the statistical relationship between the one-hour and two-hour lead

loadings from adjoining sample areas, a paired t-test was performed to determine whether the

difference in the log-transformed loadings at a location was significantly different from zero (or

equivalently, that the ratio of untransformed loadings at a location was significantly different from

one). Data were pooled across the carpet removal and window replacement phases for this test. 

The p-value resulting from the paired t-test was 0.008, indicating that the difference in the log

lead loadings between one- and two-hour lead loadings was highly significant statistically. Similar

results occurred when the Wilcoxon signed-rank nonparametric test was applied. These results

are equivalent to concluding that the geometric mean of the ratio of 2-hour to 1-hour lead

loadings is significantly different from one. The estimated geometric mean is 1.57, which is an

estimate of the median ratio. Therefore, there is statistical evidence that waiting two hours after

an activity leads to increased lead loadings. Since statistical comparisons between activities within

the EFSS were based only on one-hour dustfall measurements (Chapters 8 and 9), effects due to

elapsed wait times do not enter into the comparisons.

7.3 COLLECTING SAMPLES VIA VACUUM TECHNIQUES VS. WIPE TECHNIQUES

For a given R&R activity, lead loadings from dustfall samples collected via vacuum

techniques were used to statistically characterize lead disturbance and potential lead exposure to

occupants. Using pre-moistened wipes to collect settled dust samples is a competing sampling

collection procedure that was employed in previous lead exposure characterization studies. The

vacuum and wipe sampling techniques from SSDCs were compared within the EFSS by analyzing

data from paired dust samples, where one sample in each pair was collected from an SSDC using

wipe techniques and the other from an adjoining SSDC using vacuum techniques. Paired

vacuum/wipe sampling was performed for carpet removal and for the demolition of plaster walls

within the CED phase. Differences between paired vacuum and wipe results were statistically

analyzed across the two activities.

In the carpet removal phase, two pairs of vacuum/wipe samples were collected within each

of the eight study units, providing 16 sample pairs. All 32 samples were collected from locations

immediately adjacent to rooms where carpet removal activity occurred. In the CED phase, 12

pairs of vacuum/wipe samples were collected following wall demolition within the two Baltimore

units. These pairs were collected at distances ranging from 6 to 10 feet from the demolished wall

one hour following conclusion of the R&R activity.
7-9

Figure 7-8. Plot of Lead Loadings for Paired Vacuum/Wipe Samples at Each Location and

Study Unit in the EFSS

The scatterplot in Figure 7-8 includes lead loadings for dust samples within the

wipe/vacuum sample pairs in the carpet removal and CED phases. Results from the same pair are

plotted immediately above and below each other. The extent of a linear relationship between the

(log-transformed) wipe and vacuum sample results within a pair is illustrated in Figure 7-9, where

wipe loadings are plotted versus vacuum loadings.

The correlation coefficient between (log-transformed) vacuum and wipe sample results in

Figure 7-9 is 0.83, which is highly significantly different from zero (p=0.0001). Thus, as

expected, a strong positive relationship exists between log-transformed vacuum and wipe loadings

at a given location. 

For the carpet removal phase, both wipe and vacuum loadings appear to have similar

variability and cover approximately the same ranges (the stars in Figure 7-9). However, in the

CED phase, variability among vacuum sample loadings was substantially higher than for wipe

sample loadings. This is evident in Figure 7-9, where the CED data (the circles) cover a wider

range horizontally than vertically. This result may indicate that wipe sampling is less sensitive

than vacuum sampling in environments with considerable amounts of dust, especially in situations

where the wipes may become saturated with dust.
ln(loadingvacuum) ' ln(") % $ln(loadingwipe) % error

7-10

Figure 7-9. Plot of Wipe Sample Loading Versus Vacuum Sample Loading for Paired

Samples in the EFSS

The solid line in Figure 7-9 represents the line of perfect agreement between wipe and

vacuum sample results. In the carpet removal phase, 11 of the 16 pairs (69%) had higher loadings

for the wipe sample than for the vacuum sample. For 10 of these 11 pairs, the vacuum sample

loadings were less than 30 μg/ft . In the CED phase, 6 of 12 pairs had higher results for the wipe 2

sample, as vacuum samples were more highly variable in both directions from the median of the

wipe loading data. Generally, vacuum and wipe sample loadings were higher in the CED phase

than the carpet removal phase, as seen in Figure 7-8. This figure also suggests that wipe methods

may provide higher recoveries at low loadings, whereas vacuum methods may provide higher

recoveries at high loadings.

To statistically characterize the relationship in dust lead loadings between adjoining wipe

and vacuum samples collected one hour post-activity, a statistical model was fitted to the data in

Figure 7-8 (data from 28 vacuum/wipe pairs). The statistical model assumes that this relationship

is log-linear:

where " and $ are unknown parameters. Statistical methods took into account that loadings for

both sample types are subject to error. If " and $ both equal one, then the log-loading for the

vacuum sample differs from the log-loading for the adjoining wipe sample by random error. If "

is not equal to one, then the vacuum log-loading is consistently different from the wipe logloading by an amount equal to ln("). If $ is not equal to one, the extent of the difference between

the two results changes with the magnitude of the measurements.
7-11

The estimate of $ in the above model was 1.04, with a standard error of 0.14. Thus, $ was

declared not significantly different from one (p=0.79), concluding that any difference between the

wipe and vacuum loadings was assumed constant across the observed measurements. The

estimate of " was 0.88, with an approximate 95% confidence interval of (0.57, 1.35). This

estimate is less than one, reflecting the decreased vacuum sample loadings relative to the wipe

sample loadings, as seen primarily in the carpet removal data. However, its 95% confidence

interval contains 1.0, implying that the estimate is not significantly different from one at the 0.05

level. Therefore, there is no statistical evidence (given the observed data) that the results for

paired wipe and vacuum samples differ significantly.

7.4 COMPARING RESULTS BETWEEN SIDE-BY-SIDE SAMPLES

In each of the three R&R phases (carpet removal, window replacement, and CED phases),

additional lead dust samples were collected from areas adjoining "regular" sample areas at

selected sampling locations. These samples, simulating field duplicates, were labeled "side-byside" samples, and were taken from floors and SSDC surfaces. Because the sample areas between

a regular and side-by-side sample were adjoining, and the same sampling technique was used to

collect both samples, any spatial variability between the two sample results was assumed to be

minimized. Also, both samples were collected within a few minutes of each other at specified

times during the activity process. As a result, one expects any differences between the two results

to reflect only variability in the sample collection and measurement processes. However, in the

summary and analysis of loading data obtained from vacuum dust sampling, the first sample

collected within a pair had consistently higher results than the second sample collected.

Figure 7-10 presents a log-log scatterplot of loadings between the first sample collected

versus the second sample collected for each regular/side-by-side pair collected in the study, when

vacuum sampling techniques were used. The majority of points in this plot fall above the 45E line,

indicating that the first sample collected in a pair was consistently higher than that of the second

sample collected.

For settled dust loadings, concentrations, and physical sample weights, Tables D-2a

through D-2c in Appendix D (one table for each study phase) list the results of regular and sideby-side sample pairs as well as the differences in results between two samples in a pair. Results

are listed according to whether the sample was collected from a floor or SSDC surface, and 

whether the sample was collected pre- or post-activity. In each of these breakdowns, loadings for

the first sample collected were larger than for the second sample collected in a majority of the

sample pairs. 

To test the hypothesis that the results for the first sample taken from two adjoining sample

areas were significantly different from results for the second sample taken, two statistical tests

were performed. First, a binomial test was performed to test whether the percentage of sample

pairs having larger results in the first sample collected was significantly different from 50%. Next,

a Wilcoxon signed-rank test was performed to determine whether the first result minus the second

result (i.e., the differences in Tables D-2a through D-2c) was significantly different from 
7-12

Figure 7-10. Lead Loadings for Adjoining Samples Collected via Vacuum Techniques

(Sample Collected First Versus Sample Collected Second)

zero. The results of these tests are included in Table 7-1, where symbols indicate whether

statistical significance was observed at the 0.05 level. Significance was seen for sample loadings

in pooled sample pairs for the carpet removal and window replacement phases, as well as across

all phases. Significance was not as apparent for sample concentrations and weights. A lack of

significance in some cases may be the result of low statistical power to detect differences, due to

the small sample size.

As a result of the investigation of side-by-side data in the EFSS, it is hypothesized that

taking a vacuum dust sample may bias lead loadings that exist in adjoining areas. This conclusion

affects the interpretation of side-by-side vacuum sampling designs that are applied to simulate

field duplicates or to observe pre- and post-activity lead levels. However, a more detailed study

that solely addresses this hypothesis is necessary to make such a conclusion with sufficient

confidence.
7-13

Table 7-1. Percentage of Sample Pairs (Regular and Side-by-Side QC Samples) Where

Result for the First Sample Collected Was Different From the Result for the

Second Sample Collected (Vacuum Samples Only)

Phase Activity) Activity) (Post-Activity) All Samples

Floor Samples (Pre- Floor Samples (Post- SSDC Samples(1)

Sample Loadings

Carpet Removal 62.5% (5/8) 75.0% (6/8) 68.8% (11/16) 68.8%* (22/32)  

Window 66.7% (2/3) 100% (3/3) 100% (3/3) 88.9%* (8/9)

Replacement



CED --- --- 55.6% (5/9) 55.6% (5/9)

All Phases 63.6% (7/11) 81.8% (9/11) 67.9% (19/28) 70.0%* (35/50)  

Sample Concentrations

Carpet Removal 62.5% (5/8) 50.0% (4/8) 56.3% (9/16) 56.3% (18/32)

Window 100% (3/3) 33.3% (1/3) 33.3% (1/3) 55.6% (5/9)

Replacement

All Phases 72.7% (8/11) 45.5% (5/11) 52.6% (10/19) 56.1% (23/41) 

Sample Weights

Carpet Removal 50.0% (4/8) 75.0% (6/8) 68.8% (11/16) 65.6% (21/32)

Window 0.0% (0/3) 100% (3/3) 66.7% (2/3) 55.6% (5/9)

Replacement

All Phases 36.4% (4/11) 81.8% (9/11) 68.4% (13/19) 63.4% (26/41)

 * Percentage is significantly different from 50% at the 0.05 level by the binomial test.

  Results of the first sample taken are significantly different from the results of the second sample taken, at

the 0.05 level according to the Wilcoxon signed rank test.

Stainless steel dustfall collectors (1)
8-1

8.0 STUDY RESULTS FOR INDIVIDUAL PHASES

This chapter presents the results of data summary and statistical analysis of environmental

exposure data collected in the EFSS. Each phase in the EFSS was a substudy in itself, with

specific sampling designs and data organization. Consequently, the study designs and results for

each phase are presented as stand-alone sections, as follows: 

Section 8A — Carpet removal phase

Section 8B — Window replacement phase

Section 8C — Controlled, Experimentally-Designed (CED) phase.

Data summaries and statistical analyses in these three sections were centered around data

analysis objectives (see Section 6.1) established for the EFSS. Analysis to address objectives on

sampling methodology evaluation was presented in Chapter 7.

Two additional sections in this chapter document other types of data collected and/or

summarized to address issues concerning study objectives:

Section 8D — Cleanup Investigation. Determine the effects associated with two types

of post-activity cleanup procedures on reducing settled dust lead levels

following R&R activity.

Section 8E — Data from Other Sources. Summarize data obtained from other extant

sources that relate R&R activities to lead exposures.

The appendices to this report (Volume II) provide supporting information to the main

results presented in this chapter. Supporting information includes additional data summaries and

detailed discussion of statistical methods.
8-2

8A-1.0 STUDY DESIGN IN THE CARPET REMOVAL PHASE

Chapter 4 presented aspects of the EFSS study design that were common across all

phases. This section presents specific details of the study design as it was applied in the carpet

removal phase. This section also presents characteristics of the eight dwelling units monitored in

this phase.

8A-1.1 SAMPLING DESIGN FOR THE CARPET REMOVAL PHASE

The sampling design for the carpet removal phase was developed to address the objectives

presented in Section 6.1. Table 8A-1 presents the proposed types and numbers of environmental

field samples (both regular and QC samples) collected within each dwelling unit. These samples

included the following:

! Personal exposure samples taken during the activity

! Ambient air samples taken during the activity

! Settled dust samples taken before the activity from the carpet to be removed

! Settled dust samples taken before and after the activity from floor and window sill

surfaces

! Settled dust samples taken following completion of the activity from stainless steel

dustfall collectors (SSDCs) placed on the floor immediately prior to the activity. 

Three vacuum dust samples were collected prior to the start of the activity from the carpet

to be removed. The Battelle field team leader selected the sample locations from the entire area

of carpet to be removed, in an attempt to represent average carpet debris across the activity area

in the unit. Areas with unusually high amounts or types of debris were not considered. A given

dust sample was collected from a total area defined by a 1-ft steel template, and lead content of 2

all these samples was used as a covariate in the statistical analysis to predict lead exposure which

can result from carpet removal.

Dust samples from floors and SSDCs were collected at three distinct locations in each

unit. The locations (labeled L1, L2, L3) were in "adjacent areas" or areas outside of, but at the

entrance to, an activity room. The sampling plan called for the three locations to be randomly

distributed among adjacent areas throughout the unit; however, the locations were also dictated

by logistical constraints, such as the ability of adjacent areas to accommodate the total area

required for dust sampling (from 5 to 8 square feet). Sampling locations were partitioned into

five, six, or eight subareas, each one square-foot in area, as illustrated in Figure 8A-1. A single

settled dust sample was collected from each subarea at a specific time during the activity.
8-3

Table 8A-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed in

the EFSS Carpet Removal Phase Within Each Study Unit

Regular Samples

When Sample # Samples

Was Taken Sample Collection Method Sample Type/Location Proposed (1)

Pre-activity

Vacuum Settled dust (Window sill) 2

Settled dust (Floor) 3

Settled dust (Carpet surface) 3

Ambient air pump Ambient air 1

During activity Personal air pump Personal air (R&R workers) 2

Ambient air pump Ambient air (adjacent room) 2

1-hr. Postactivity

Vacuum Settled dust (SSDC) 3

Settled dust (Floor) 3

Settled dust (Window sill) 2

Wipe Settled dust (SSDC) 2

2-hr. Postactivity Vacuum Settled dust (SSDC) 3

Total 26

Field QC Samples

When Sample # Samples

Was Taken Sample Collection Method Sample Type/Location Proposed (1)

Pre-activity Wipe Field blank 1

Vacuum

SBS settled dust (Floor) 1

Field blank 1

Personal air pump Field blank 1

Ambient air pump Field blank 1

1-hr. Postactivity

Vacuum

SBS settled dust (Floor) 1

SBS settled dust (SSDC) 1

Wipe SBS settled dust (SSDC) 1

2-hr. Postactivity Vacuum SBS settled dust (SSDC) 1

Total 9

 SSDC = stainless steel dustfall collector (1)

SBS = sample taken side-by-side with a regular sample

Immediately prior to the start of carpet removal, the field team collected one vacuum dust

sample within a one-square-foot area of the floor surface in each of the three sampling locations

designated in Figure 8A-1. The field team also collected one vacuum dust sample from one-half

of each of two window sills located in activity rooms. Lead content of these floor and window sill

dust samples represented baseline levels which were compared to lead levels in samples taken

upon completion of carpet removal from areas adjoining the pre-activity sample areas. 
8-4

Location L1: Cell #1 Cell #2 Cell #3

Floor vacuum Stainless steel Stainless steel

(Pre-activity) surface -- vacuum surface -- 

(1 hr. post-activity) wipe (1 hr. postactivity)

Cell #4 Cell #5

Floor vacuum Stainless steel

(1 hr. post- surface -- vacuum

activity) (2 hr. post-activity)

Location L2: Cell #1 Cell #2 Cell #3

Floor vacuum Stainless steel Stainless steel

(Pre-activity) surface -- vacuum surface -- 

(1 hr. post-activity) wipe (1 hr. postactivity)

Cell #4 Cell #5 Cell #6

Floor vacuum Stainless steel Stainless steel

(1 hr. post- surface -- vacuum surface -- wipe (1

activity) (2 hr. post-activity) hr. post-activity)

(side-by-side)

Location L3:

Cell #1 Cell #2 Cell #3 Cell #4

Floor vacuum Floor vacuum Stainless steel Stainless steel

(Pre-activity) (Pre-activity) surface -- vacuum surface -- vacuum (1

(side-by-side) (1 hr. post-activity) hr. post-activity)

(side-by-side)

Cell #5 Cell #6 Cell #7 Cell #8

Floor vacuum Floor vacuum Stainless steel Stainless steel

(1 hr. post- (1 hr. post-activity) surface -- vacuum surface -- vacuum (2

activity) (2 hr. post-activity) hr. post-activity)

(side-by-side) (side-by-side)

Note: Due to space considerations, no wipe samples were taken at location L3. In shaded subareas,

dust samples were taken directly from the uncarpeted floor surface.

Figure 8A-1. Three Settled Dust Sampling Locations at Adjacent Areas Within Each Unit,

and the Types of Regular and QC Samples Collected Within Each Location, in

the Carpet Removal Phase
8-5

One pre-activity ambient air sample was taken to obtain an estimate of baseline airborne lead. 

Because the ambient air samples took two hours to collect, the pre-activity ambient air sample

was sometimes taken on the day prior to carpet removal.

Personal and ambient air samples were collected during carpet removal activities. Personal

exposure sampling was conducted on up to two R&R workers per dwelling unit to measure lead

levels in air within the workers' breathing zones while they were performing carpet removal. 

Ambient air samples were collected in two rooms adjacent to the activity to measure lead levels in

air dust that could be inhaled by others present. 

When possible, doors to rooms where ambient air samples were being collected were

closed while carpet removal was being performed.

Post-activity sampling included settled dust samples from floors, window sills, and SSDCs

positioned immediately prior to the start of the activity. At one hour following completion of all

carpet removal activities, vacuum dust samples were collected from the remaining halves of the

two window sills where pre-activity dust samples were collected. Vacuum dust samples were

collected at three floor sampling locations one hour following the activity. Samples were taken

from the floor surface and from a SSDC adjacent to the pre-activity vacuum floor dust sample

area (as indicated in Figure 8A-1). 

To compare results between wipe and vacuum sampling protocols, dust samples from

SSDCs were collected at one hour following conclusion of carpet removal. These samples were

taken from locations L1 and L2 (see Figure 8A-1) using wipe sampling techniques. To evaluate

whether there was an increase in lead "fallout" in settled dust after waiting two hours rather than

one hour, dust samples were collected from SSDCs in each sample location (Figure 8A-1) using

vacuum techniques. All three samples were taken at two hours following the activity from areas

adjoining the one-hour post-activity vacuum sample area. The results of these additional samples

are presented in Chapter 7.

Table 8A-1 specifies 35 environmental samples in each dwelling unit, nine of which were

field quality control (QC) samples. One field blank was taken prior to the start of carpet removal

for every sampling medium (vacuum dust, wipe dust, personal air, ambient air) to determine the

extent of contamination present during sample collection. At one settled dust sampling location

(L3), side-by-side vacuum dust samples were taken from the floor surface and from SSDCs to

allow sampling and measurement error to be characterized.

The number of samples made it was impossible to collect all settled dust samples at

precisely the time at which they were to be collected (i.e., at one hour or two hours following

completion of carpet removal). The time period for settled dust sample collection ranged from 15

minutes before to 40 minutes after the scheduled time. 
8-6

Air samples were taken at relatively high flow rates (20 L/min for ambient air samples and 5

L/min for personal air samples) in the carpet removal phase. To make these rates more

compatible with NIOSH specifications, the rates were lowered to 12.5 L/min and 4 L/min,

respectively, in later phases of the EFSS. In addition, ambient and personal air samples taken in

the carpet removal phase were collected open-faced (with the entire inlet section of the cassette

assembly removed), in contrast to the NIOSH standard method (used in later phases of the EFSS)

of removing only the inlet plug. The fact that different results could be obtained from the two

methods should be considered when interpreting the results.

More details on the sampling design, including the protocols used to collect the samples,

are given in the Quality Assurance Project Plan.

8A-1.2 UNIT CHARACTERISTICS

Field sampling in the carpet removal phase took place in eight occupied dwelling units. 

Table 8A-2 provides information on these units, including the days on which carpet removal and

field sampling were performed, the rooms from which carpet was removed, and the approximate

square footage of carpet removed.

Details on the recruitment of the units are presented in Chapter 5. Table 5-2 in Chapter 5

contains summaries of pre-activity dust lead loadings from floors and window sills in these units. 

Chapter 5 also contains discussions of worker characteristics. It should be noted that carpet

removal was conducted by professional abatement workers in the four Alameda County units and

by homeowners in the four St. Louis units. While the work practice of these two types of

workers may differ, they reflect the wide variety of workers conducting R&R activities.

Table 8A-2. Dwelling Units Included in the EFSS Carpet Removal Phase

Study Date of Type of R&R feet of carpet removed is in

Unit ID Activity Unit Description Workers parentheses)

Activity Areas (approx. square

1-01 06/22/93 Two-story house; Prof. Living Room (260)

Oakland, CA; Contractor Dining Room (143)

100 years old; Hall (floor 1) (90)

peeling ext. paint; Stairway (60)

rehabbed 15 yrs ago; Hall (floor 2) (72)

1-02 06/23/93 Basement apartment; Prof. Living Room (162)

Oakland, CA; Contractor Bedroom #1 (127)

100 year-old building; Bedroom #2 (149)

Int. walls 10 yrs old;

Frequent flooding

Across from highway;

1-03 06/24/93 Single-story house; Prof. Living Room (212)

Oakland, CA; Contractor Hallway (34)

50 years old;

peeling ext. paint;
Table 8A-2. Dwelling Units Included in the EFSS Carpet Removal Phase (Continued)

Study Date of Type of R&R feet of carpet removed is in

Unit ID Activity Unit Description Workers parentheses)

Activity Areas (approx. square

8-7

1-04 06/25/93 Two-story duplex; Prof. Living Room (256)

Alameda, CA; Contractor Dining Room (206)

75 years old; Stairway (170)

Little soil covering; Hall (level 2)(100)

2-01 07/13/93 Three-story house; Nonprof. Family Room (224)

St. Louis, MO; Resident Bedroom #1 (224)

90 years old;

R&R work in progress (2nd floor

family room);

2-02 07/15/93 Two-story house; Nonprof. Living Room (168)

Webster Groves, MO; Resident Dining Room (144)

50 years old; Stairway (120)

2-03 07/14/93 Two-story house; Nonprof. Living Room (210)

St. Louis, MO; Resident Dining Room (180)

96 years old;

Brick exterior;

2-05 07/16/93 Two-story house; Semiprof. Office (120)

St. Louis, MO; Resident Bedroom (120)

60 years old; Hall (floor 1) (21)

Brick exterior;

8A-2.0 STUDY RESULTS FOR THE CARPET REMOVAL PHASE

This chapter presents the results of the statistical analysis of environmental sample data

from the carpet removal phase of the EFSS study. 

Analytical data were available for statistical analysis from all environmental field samples

that were collected in the study. Table 8A-1 specifies 35 samples to be collected in each of the

eight study units, for a total of 280 samples. Of these proposed samples, 278 were successfully

collected. The two uncollected samples were personal air samples from units 2-03 and 2-05,

where both units had only a single worker conducting carpet removal activity. In addition, two

cassette samples were necessary to monitor personal air over the entire carpet removal activity for

both workers in unit 1-01 and for the single worker in unit 2-03. This resulted in three additional

samples collected making analytical data available for 281 regular and QC field samples in the

carpet removal phase. A summary of the samples collected and data received is displayed in

Table CR-1 of Appendix A.

This section presents results and conclusions of the statistical analysis of data from the

carpet removal phase. It is organized according to data analysis objectives (see Section 6.1). 

Supporting discussion and materials are included as Appendices A through D. 
8-8

8A-2.1 CHARACTERIZE LEAD DISTURBANCE AND POTENTIAL LEAD EXPOSURE

Tables CR-2a through CR-6b in Appendix A contain summaries of lead concentrations in

personal and ambient air samples, and physical sample weights, lead loadings, and sample lead

concentrations in dust samples. The summaries, presented for each study unit as well as for the

entire carpet removal phase, include the arithmetic and geometric means, the standard deviation of

the log-transformed data, and the minimum and maximum observed values. As discussed in

Chapter 6, statistical analysis of dust lead levels focused primarily on log-transformed lead

loadings, or the amount of lead per unit surface area sampled. 

The lead disturbance and exposure data observed in the carpet removal phase are

characterized below, according to the sample type or component sampled.

8A-2.1.1 Personal Worker Exposures

The duration of carpet removal activity (and of personal air monitoring) across the workers

in this phase ranged from 46 to 173 minutes, with an arithmetic mean of 92 minutes. Total

activity monitored included preparation, carpet removal, disposal, and cleanup (if any). 

Monitoring occurred for two workers in six of the eight units, and for one worker in each of the

remaining two units, resulting in 14 estimates of personal air lead concentration. The two

workers who worked alone in a unit had the longest durations of personal air monitoring in the

study (155 and 173 minutes). 

The amount of lead collected within the sample cassette(s), the air pump flow rate, and the

duration of monitoring were used to calculate a given worker's task-length average (TLA)

personal air lead concentration in μg/m . The concentrations, each representing instrument data 3

above the detection limit, are plotted in Figure 8A-2 for each study unit. A worker's TLA

exposure represents average exposure over the duration of performing the activity.

A boxplot of TLA lead concentrations is included as the rightmost boxplot in Figure 8A-3. 

Descriptive statistics on personal air lead concentrations are displayed in Tables CR-2a and CR-2b

in Appendix A.

Four of the 14 monitored workers (29%) had TLA lead exposures above the OSHA PEL

of 50 μg/m . These four results occurred for the two workers in unit 1-01 (results of 51.3 and 3

59.9 μg/m ) and for the two workers in unit 1-04 (results of 128 and 221 μg/m ). Activity in both 3 3

of these units took more than 90 minutes per worker, and the carpets were visually observed as

excessively dirty. In contrast, the TLA lead exposure among the other six study units ranged

from 0.86 to 8.44 μg/m , well below the OSHA PEL. 3

The arithmetic mean of the 14 worker TLA lead exposures was 35.9 μg/m . However, 3

because the data are more closely characterized by a lognormal distribution than a normal

distribution, the geometric mean of 8.44 μg/m is considered a better representation of the data, 3

as it estimates the median (or central tendency) of the data distribution.
8-9

Figure 8A-2 illustrates that the range of TLA lead concentration data across the different

units is greater than the range of data within a unit. This result is further investigated in Section

8A-2.2.4. 

8A-2.1.2 Potential Occupant Exposures to Airborne Lead

Within each unit, one pre-activity ambient air sample and two during-activity ambient air

samples were collected in the carpet removal phase. Each sample was collected for a 120-minute

duration (±4 minutes). The amount of lead collected within the sample cassette, the air pump

flow rate, and the duration of monitoring were used to calculate lead concentration in μg/m air 3

for each sample. The lead concentrations are plotted in Figure 8A-4 for each study unit. 

Boxplots of pre-activity and during-activity ambient air lead concentrations are included in Figure

8A-3. Descriptive statistics on ambient air lead concentrations are displayed with those for the

personal worker exposure concentrations in Tables CR-2a and CR-2b of Appendix A. All

instrument data on ambient air samples were reported above the detection limit.

The leftmost boxplot in Figure 8A-3 illustrates the range of lead concentrations in ambient

air observed during pre-activity periods within each unit. The concentrations were approximately

symmetric about the arithmetic mean of 0.10 μg/m , ranging from 0.05 to 0.17 μg/m . The 3 3

relatively low unit-to-unit variability in these concentrations indicates that the eight study units

were relatively homogeneous in their baseline airborne lead levels. Thus, no baseline adjustment

was made to the during-activity ambient air concentration prior to statistical analysis.

The lead concentrations for ambient air samples collected during carpet removal activity,

summarized by the center boxplot within Figure 8A-3, ranged from 0.06 to 13.4 μg/m with a 3

geometric mean of 0.33 μg/m . The maximum reading of 13.4 μg/m , flagged by statistical outlier 3 3

tests (Appendix B), was more than twice that of the next largest reading (5.36 μg/m ). The 3

ambient air samples associated with the two largest concentrations were collected within the same

two units where the largest worker personal exposure concentrations were observed. However,

the other two ambient air concentrations observed in these units were comparable to

concentrations in the other units. 

As illustrated in the center boxplot of Figure 8A-3, the arithmetic mean for during-activity

ambient air lead concentrations (1.48 μg/m ) was heavily influenced by the two largest 3

concentrations. The geometric mean of 0.33 μg/m , more representative of the data than the 3

arithmetic mean, was approximately three times higher than the geometric mean for the baseline

(pre-activity) concentrations. However, such low levels as observed here imply that the difference

is likely of little practical significance.

For one study unit, the geometric mean ambient air lead concentration during carpet

removal was less than the unit's baseline concentration. In contrast, three study units had

geometric means exceeding ten times their respective baseline concentrations. 
8-10

Figure 8A-2. Scatterplot of Task-Length Average Personal Exposure Lead Concentrations

(μg/m air) for Each Worker Within Each Study Unit in the Carpet Removal 3

Phase

Figure 8A-3. Boxplots of Lead Concentrations (μg/m air) for Personal Exposure and 3

Ambient Air Samples in the Carpet Removal Phase
8-11

Figure 8A-4. Scatterplot of Ambient Air Lead Concentrations (μg/m air) Within Each 3

Study Unit in the Carpet Removal Phase

8A-2.1.3 Lead Disturbance and Potential Occupant Exposure to Lead In Dust

In the carpet removal phase, settled dust was collected from three types of flat surfaces to

characterize lead disturbance and potential occupant exposures to lead in dust. The three surface

types, and when they were sampled, were as follows:

! floor surfaces in adjacent rooms, sampled pre- and post-activity

! SSDCs in adjacent rooms, placed immediately prior to activity and sampled postactivity

! window sills in activity rooms, sampled pre- and post-activity.

The results of analysis on settled dust samples taken from the three surface types are summarized

below.

8A-2.1.3.1 Vacuum Dust Samples Taken Pre- and Post-Activity from Floor Surfaces

Vacuum dust samples were collected from one-square-foot areas on floor surfaces prior to

the start of the activity and one hour following completion of the activity. One pre-activity and

one post-activity sample were taken from adjoining areas in three distinct locations in each unit

(Figure 8A-1). Each location was immediately adjacent to an activity room. The difference in
8-12

lead levels between the adjoining (or paired) pre- and post-activity samples within each location

was an estimate of lead exposure in settled dust generated by carpet removal activity.

Results of vacuum floor dust sampling (physical sample weight, lead loading, and lead

concentration) are summarized in Tables CR-3a through CR-3d in Appendix A. Appendix A also

includes boxplots of lead loadings and concentrations (Figures CR-1a and CR-1b for pre-activity

vacuum floor samples; Figures CR-2a and CR-2b for post-activity vacuum floor samples). The

geometric mean sample weight increased fourfold from pre- to post-activity (from 0.03 to 0.12 g),

while the geometric mean lead concentration more than doubled (from 475 to 1080 μg/g). Larger

increases in geometric mean were observed for lead loadings, which increased nine times (from

14.4 to 130 μg/ft ) from pre- to post-activity. These increases are equivalent to the geometric 2

mean of the ratio of post-activity to pre-activity results at a given sample location.

Lead loading was the measurement of most interest to compare between adjoining pre- and

post-activity samples. Lead loadings at a given sample location were expected to increase as a

result of the activity. However, at five of the 24 sample locations in the study, lower lead

loadings were reported for the post-activity sample than for the adjoining pre-activity sample. 

This result indicates that spatial variability and/or measurement (analytical) error were

considerable for lead loadings on floors. A plot of the difference in loadings between post- and

pre-activity samples for each study unit was presented in Figure 7-4 of Chapter 7.

Section 7.1 of Chapter 7 gives an evaluation of the relative merit of using paired pre-/postactivity floor samples versus single samples from SSDCs to measure the amount of lead disturbed

during carpet removal. This evaluation concluded that results for dustfall samples from SSDCs

were less variable and more highly correlated with results from other sampling media, and were

thereby preferred over the pre-/post-activity floor dust results to characterize lead levels. SSDC

results are given in the next subsection.

8A-2.1.3.2 Vacuum Dust Samples from Stainless Steel Dustfall Collectors. 

In addition to the floor dust samples described above, vacuum dust samples were taken

from SSDCs as an alternative measure of lead disturbance. At each floor sample location (Figure

8A-1), a single settled dust sample was collected one hour following completion of carpet

removal activities from a SSDC placed adjacent to the post-activity floor dust sample area. 

For this phase and the window replacement phase, other SSDCs were placed at each floor sample

location to address sampling methodology issues. The results of samples from SSDCs taken two

hours following completion of carpet removal were presented in Section 7.2 of Chapter 7, where

they were compared with the one-hour results. In Section 7.3 of Chapter 7, the one-hour postactivity vacuum results were compared with the wipe dust sampling results from adjoining sample

areas. These two sections also provide additional summary and display of the results presented

herein.

Tables CR-4a through CR-4d in Appendix A present a summary of the results of vacuum

dust sampling from SSDCs one hour following completion of carpet removal activities. Boxplots

of lead loadings and concentrations within one-hour post-activity dustfall collectors samples are
8-13

also included as Figures CR-2a and CR-2b, respectively, in Appendix A. These lead loadings

ranged from 2.61 (the detection limit) to 621 μg/ft , with a geometric mean of 24.3 μg/ft . A plot 2 2

of the loadings on a unit-by-unit basis is presented in Figure 7-4 in Section 7.1.

8A-2.1.3.3 Vacuum Dust Samples from Window Sill Surfaces Taken Pre- and Post-Activity. 

Similar to the floor dust sample approach presented in Section 8A-2.1.3.1, pre- and postactivity dust sampling was performed on two window sill surfaces per unit. The window sill was

located in a room where carpet removal activity took place. One-half of the window sill area was

sampled for settled dust prior to the start of carpet removal activities, and the other half was

sampled one hour following completion of these activities. These sample results provided

information on lead exposures in settled dust within an activity room.

Tables CR-5a through CR-5d of Appendix A present data summaries for the pre- and postactivity window sill dust samples. Also in Appendix A are boxplots of lead loadings and

concentrations for pre-activity window sill dust samples (Figures CR-1a and CR-1b) and for postactivity window sill dust samples (Figures CR-2a and CR-2b). All window sill dust samples taken

in this study contained detectable amounts of lead.

Across all samples, the geometric mean loadings on window sills increased from pre- to

post-activity by approximately 58% (from 418 to 661 μg/ft ), a smaller percentage increase than 2

the 800% increase observed within floor dust. However, for each of these measures, the

geometric means at pre- and post-activity were higher for window sills than for floors. The larger

data values for window sills (pre-activity) may be one reason for the smaller percentage increases

associated with window sills over floor surfaces.

Three of the eight study units had geometric mean values of less than one for the ratio of

post- to pre-activity lead loadings on window sills. This indicates that, similar to the finding for

floor dust loadings, spatial variability and/or analytical error associated with window sill lead

loadings were considerable.

8A-2.2 ASSESS FACTORS OR MEASUREMENTS RELATED TO LEAD DISTURBANCE

In order to characterize the statistical relationship between lead exposure in various media

and potential predictors of this exposure, as well as to quantify the various components of total

variability in lead exposures, statistical models were developed and fitted to lead measurements

obtained in the carpet removal phases. The models were fit to data across all study units using

analysis of variance (ANOVA) techniques.

Sections 8A-2.2.1 through 8A-2.2.3 present the results of fitting log-linear models to

predict lead measurements from a series of selected covariates. These covariates included preactivity lead loadings in the carpet removed, pre-activity lead loadings on floors and window sills,

and the duration of activity. The models test whether a change in the value of a specific covariate

significantly affects (in a multiplicative fashion) the value of the lead measurement being

predicted. The forms of these statistical models are found in Section C.1 of Appendix C.
8-14

The approach to characterizing variance components associated with a specific type of lead

measurement involves fitting the same models described in the previous paragraph, with only the

random effects associated with each variance component represented in the model (i.e., covariates

are excluded). These models are documented in Section C.2 of Appendix C. When estimable

based on the data, variance components in the model include variability associated with sampling

from different study units ("unit-to-unit" variability), variability associated with sampling multiple

locations or workers within a given unit ("within-unit" or "location-to-location" variability), and

variability associated with taking samples from multiple areas within the same location ("withinlocation" or "replicate-to-replicate" variability). Results of estimating variance components are

found in Section 8A-2.2.4.

It should be noted that the model fittings in this section were performed on small numbers

of data points having relatively high variability. Therefore, tests for significant covariate effects

tended to have low power.

8A-2.2.1 Personal Worker Exposures

Model (CPT-1) in Section C.1 of Appendix C was fitted to 14 log-transformed lead

concentrations (μg/m ) from samples collected through personal air monitoring of R&R workers 3

during carpet removal activities. These data were plotted in Figure 8A-2 and represent average

exposure over the duration of performing an activity. Covariates in the model included:

! geometric mean lead loading in the removed carpet for the unit

! geometric mean pre-activity lead loading on floor surfaces in adjacent rooms of the

unit

! geometric mean pre-activity lead loading on window sill surfaces in activity rooms of

the unit

! amount of time that carpet removal took place in the unit.

Each of the coefficients associated with the above four (log-transformed) covariates was not

significantly different from 0 at the 0.05 level, indicating no evidence exists that these covariates

have a significant effect on personal worker exposure. This result could be due to high variability

observed in the data, relative to the small sample size.

8A-2.2.2 Potential Occupant Exposures to Airborne Lead

Model (CPT-2) in Section C.1 of Appendix C was fitted to log-transformed lead

concentrations (μg/m ) in air within adjacent rooms, obtained from ambient air monitoring during 3

carpet removal activities. The sixteen data points obtained from this phase are plotted in Figure

8A-4. Covariates in the ambient air model included:
8-15

! geometric mean lead loading in the removed carpet for the unit

! geometric mean pre-activity lead loading on floor surfaces in adjacent rooms of the

unit

! geometric mean pre-activity lead loading on window sill surfaces in activity rooms of

the unit

! amount of time that carpet removal took place in the unit

! pre-activity ambient air lead concentration in the unit.

Each of the coefficients associated with the above five (log-transformed) covariates was not

significantly different from 0 at the 0.05 level. Thus, no significant effect on log-lead

concentration in ambient air was observed for these covariates, relative to the small sample size

and the level of variability in the data. 

8A-2.2.3 Predicting Lead Disturbance and Potential Occupant Exposures to Lead in Dust

Modeling results are presented in the following subsections for models fitted to lead

loadings from floor, SSDC, and window sill dust-fall samples. The form of each model, and

estimates of model parameters that result from mixed-model analysis of variance, are found in

Section C.1 of Appendix C.

8A-2.2.3.1 Vacuum Dust Samples Taken Post-Activity from Floor Surfaces

Model (CPT-3) in Section C.1 of Appendix C was fitted to one-hour post-activity lead

loading data (μg/ft ) from floor surfaces in adjacent rooms. The covariates used to predict these 2

lead loadings included:

! geometric mean lead loading in the removed carpet for the unit

! pre-activity lead loading on the floor surface adjoining the post-activity sampling area

! geometric mean pre-activity lead loading on window sill surfaces in activity rooms of

the unit

! amount of time that carpet removal took place in the unit.

None of the above covariates were found to be significantly associated with post-activity

floor lead loading at the 0.05 level when the model was fitted to the study data. 
8-16

8A-2.2.3.2 Vacuum Dust Samples from Stainless Steel Dustfall Collectors

As with lead loadings from floor surfaces, Model (CPT-3) in Section C.1 of Appendix C

was fitted to one-hour post-activity lead loading data (μg/ft ) from SSDCs in adjacent rooms. At 2

the 0.05 significance level, similar results were observed with SSDC samples as with the floor

dust samples: none of the covariates were significantly associated with SSDC lead loadings. 

8A-2.2.3.3 Vacuum Dust Samples Taken Post-Activity from Window Sill Surfaces

Similar to Model (CPT-3), Model (CPT-4) in Section C.1 of Appendix C was fitted to onehour post-activity lead loading data (μg/ft ) from window sill surfaces in activity rooms. The 2

covariates used to predict these lead loadings included:

! geometric mean lead loading in the removed carpet for the unit

! pre-activity lead loading on the window sill surface adjoining the post-activity

sampling area

! geometric mean pre-activity lead loading on floor surfaces in adjacent rooms of the

unit

! amount of time that carpet removal took place in the unit.

The coefficient associated with lead loading in the adjoining pre-activity window sill sample

was significantly different from 0 at the 0.05 level (p=0.044). The estimate of this coefficient was

positive, indicating that high lead loadings in the pre-activity sample were associated with high

lead loadings in the post-activity sample from the adjoining sample location. None of the other

covariates were found to be significantly associated with post-activity window sill lead loading at

the 0.05 level. 

8A-2.2.4 Estimating Variance Components 

The sampling design for the carpet removal phase directed that samples be collected over

multiple study units, multiple locations (or workers) within a study unit, and multiple areas within

selected locations (i.e., side-by-side QC samples). In this way, key sampling components of total

data variability could be isolated and characterized. Therefore, when estimable, the magnitudes of

the following variance components were estimated using random-effects analysis of variance:

! "unit-to-unit" variability

! "location-to-location" (or worker-to-worker) variability within a unit

! "replicate-to-replicate" variability within a location.

Variance components were estimated for the following lead measurements:

! pre-activity floor dust lead loadings
8-17

! pre-activity window sill dust lead loadings

! 1-hour post-activity floor dust lead loadings

! 1-hour post-activity window sill dust lead loadings

! 1-hour post-activity SSDC vacuum lead loadings

! 1-hour post-activity SSDC wipe lead loadings

! 2-hour post-activity SSDC vacuum lead loadings

! during-activity ambient air lead concentrations

! TLA personal exposure lead concentrations.

Replicate-to-replicate variability could only be estimated for lead loadings on floors and SSDCs as

these were the only sample types where side-by-side QC samples were taken.

It is assumed that total variability is the sum of the variabilities associated with the above

three components. Any additional variance components are confounded within one or more of

these components. 

Table 8A-3 contains the estimated total variability in log-transformed lead measurements,

plus estimates of the variance components, for each sample type. The results represent variability

in the log-domain, so they are expressed in log units. 

The estimated variance components for the settled dust sample types in Table 8A-3 (i.e.,

the first seven rows of the table) were obtained from fitting a random effects analysis of variance

model (Model (C-2) of Appendix C) to data from regular and side-by-side QC samples. Results

for these sample types indicate that the estimated total variability was approximately one-third to

one-half of the estimated mean of the log-transformed measurements. For pre-activity floor and

window sill dust samples and post-activity window sill dust samples, the majority of total

variability in the data was attributed to results from different units. Variable results in side-by-side

2-hour dustfall collector dust samples led to high replicate-to-replicate variability for this sample

type. For the post-activity floor dust and 1-hour post-activity dustfall collector dust samples

(both vacuum and wipe), more variability was attributed to differing sampling locations within a

unit than to any other variance component.

Nearly all of the variability in log-transformed personal air lead concentrations was

attributable to variability across the different study units. This indicates that workers involved in

carpet removal at a given site are exposed to similar lead levels within their breathing zones. In

contrast, almost two-thirds of the total variability in ambient air concentrations was attributable to

differences between the two samples within a study unit.
8-18

Table 8A-3. Estimates of Total Variability and its Estimable Components in LogTransformed Lead Measurements by Sample Type for the Carpet Removal

Phase

Sample Type Measurement F (F ) unit (F ) location (F ) (1)

Model-Estimate Total Location-to- Replicate-toof Mean Log Variability : Unit-to-unit location within a replicate within a (2)

Square Root of

Estimated

(3)

tot

Square Roots of Estimated Variance Components(4)

U LR

Pre-Activity Floor Dust 2.69 1.99 1.76 (79%) 0.00 (0.0%) 0.92 (21%)

Pre-Activity Window Sill

Dust 6.03 2.39 2.21 (85%) 0.92 (15%) ---

1-hr Post-Activity Floor

Dust 4.92 1.71 0.82 (23%) 1.30 (57%) 0.76 (20%)

1-hr Post-Activity Window

Sill Dust 6.49 2.28 1.90 (70%) 1.25 (30%) ---

1-hr Post-Activity SSDC

Dust (vacuum) 3.08 1.49 0.74 (25%) 1.02 (47%) 0.79 (28%)

1-hr Post-Activity SSDC

Dust (wipe) 3.33 1.47 0.68 (22%) 1.14 (60%) 0.63 (18%)

2-hr Post-Activity SSDC

Dust (vacuum) 3.43 1.53 0.94 (38%) 0.00 (0.0%) 1.20 (62%)

Personal air 2.02 1.77 1.73 (95%) 0.39 (5%) ---

Ambient air -1.12 1.60 0.97 (37%) 1.26 (63%) ---

SSDC = Stainless steel dustfall collectors. (1)

Estimates of the intercept term from the random effects model. (2)

Total variability = F = F + F + F , where these parameters were estimated from the random effects model using (3) 2 2 2 2 tot U L R

restricted maximum likelihood. 

Number in parentheses is the percent of total variability (F ) represented by the given variance component (the square (4) 2

tot

of the tabled value).

8A-2.3 EVALUATE DIFFERENT MEDIA AND METHODS AS INDICATORS OF EXPOSURE

To quantify the extent of linear relationship between lead exposure estimates from

different sample types and sample collection approaches, Table 8A-4 presents Pearson correlation

coefficients among pairs of ten variables that measure lead loadings in various media through the

study. These variables include:

! pre-activity dust lead loadings on floors, window sills, and carpet

! 1-hour post-activity dust lead loadings on floors and window sills (collected via

vacuum), and SSDCs (collected via vacuum and wipe)

! 2-hour post-activity dust lead loadings on SSDCs (collected via vacuum)

! lead concentrations in personal air and ambient air samples collected during carpet

removal activity.
8-19

For each variable, the geometric mean was calculated for each of the eight study units. Pearson

correlation coefficients were calculated on these geometric means for each pair of variables. Note

that low correlation between two variables does not necessarily mean that no relationship exists

between them, but rather that the relationship is not linear in nature.

Correlations of greater than 0.9, indicating a high positive linear relationship, were

observed in lead loadings between the following pairs of dust collection methods: 

! SSDCs sampled at one-hour post-activity using wipe techniques versus the same

sampling approach using vacuum techniques

! SSDCs sampled at one-hour post-activity using wipe techniques versus SSDCs

sampled at two-hours post-activity using vacuum techniques

! SSDCs sampled using vacuum techniques at one-hour post-activity versus that taken

at two-hours post-activity.

 Table 8A-4. Pearson Correlations of Geometric Mean Lead Loadings Between Pairs of (1)

Sample Types and Approaches in the Carpet Removal Phase 

Sample Type Floor Sill Removed Floor Sill Air Exposure (2) Wipe Vacuum Vacuum

Pre-Activity Post-Activity Air

Window to be Window Ambient Personal 1 hr. 1 hr. 2 hr.

Carpet S.Steel Dustfall Collector

Pre-Act.

Floor 1.00 -0.06 0.72 0.42 0.20 -0.30 -0.26 -0.27 -0.41 -0.33

Pre-Act.

Window Sill 1.00 -0.33 -0.21 0.77 -0.14 -0.14 -0.03 0.32 -0.23

Pre-Act

Carpet 1.00 0.34 -0.35 -0.30 -0.23 -0.29 -0.21 -0.18

Post-Act.

Floor 1.00 -0.14 0.70 0.70 0.73 0.41 0.67

Post-Act.

Window Sill 1.00 -0.14 -0.09 -0.06 0.08 -0.25

1-hr. PostActivity 1.00 0.98 0.99 0.72 0.97

SSDC (wipe)

1-hr. PostActivity 1.00 0.97 0.77 0.98

SSDC (vac.)

2-hr. PostActivity 1.00 0.78 0.95

SSDC (vac.)

Ambient

Air 1.00 0.78

Correlations calculated on geometric means calculated for each study unit (n=8). All correlations greater than 0.71 are (1)

significantly different from zero at the "=0.05 level.

SSDC = Stainless steel dustfall collectors. (2)
8-20

In addition, correlations of greater than 0.9 were observed between personal worker exposure

lead concentrations and dustfall lead loadings obtained from the following sampling approaches:

! SSDCs sampled at one-hour post-activity using wipe techniques

! SSDCs sampled at one-hour post-activity using vacuum techniques

! SSDCs sampled at two-hours post-activity using vacuum techniques.

One expected to see high correlations between one-hour and two-hour post-activity dust sample

results and between vacuum and wipe dust sample results. However, the high correlation

between personal worker exposure and loadings in dust on SSDCs indicated that samples

collected from the dustfall collectors may contain more information on lead exposed by carpet

removal than do pre- versus post-activity floor dust samples. 

Correlations between post-activity floor dust lead loadings and other loadings from dust

collection methods were in the range of 0.7. While these correlations were lower than that

documented in the previous paragraph, they were still significantly different from 0 at the 0.05

level. Significant correlation was also observed between personal worker and ambient air

concentrations (0.78).

Correlations between pre-activity dust lead loadings from carpet to be removed and the

other variables were quite low and generally not significantly different from zero. Pre-activity

lead loadings versus post-activity lead loadings from adjoining sampling locations had moderately

positive correlation: 0.42 for floors and 0.77 for window sills.

8A-2.4 SUMMARY OF RESULTS

Following are the major results of the R&R carpet removal phase:

! Lead concentrations in personal air samples exceeded the OSHA PEL (50 μg/m ) in 3

four of the 14 workers sampled and in two of the eight study units. Other than these

four results, personal air lead concentrations were less than 10 μg/m . The dominant 3

variance component of these data appeared to be the result of sampling in different

study units. 

! Lead concentrations in ambient air samples collected during carpet removal activity

ranged from 0.06 to 3.38 μg/m , with a geometric mean of 0.33 μg/m . 3 3

! The difference in lead loadings from vacuum floor dust samples taken pre- and postactivity had high variability in this study. In contrast, lead loadings from SSDC

samples had substantially lower variability. In addition, SSDC lead loadings had a

very high correlation with personal exposure lead concentrations. This indicates that

the dustfall collectors may be a more accurate and precise measure of the lead

disturbed by carpet removal than the difference in pre- and post-activity floor dust

samples.
8-21

! Within the vacuum floor dust samples, the geometric mean lead loadings increased

nine times (from 14.4 to 130 μg/ft ) from pre- to post-activity. However, a wide 2

range of values, including negative results, was observed in post- minus pre-activity

floor dust lead loadings at a given location (-195 to 6130 μg/ft ). 2

! Lead loadings from SSDC samples ranged from 2.61 to 621 μg/ft , with a geometric 2

mean of 24.3 μg/ft . High unit-to-unit variability was observed with these data. 2

! Generally, the covariates considered in the statistical modeling to predict logtransformed lead loadings in various sample types were not significant at the 0.05

level, partially due to the small sample sizes considered. Pre-activity lead loadings on

window sills had a significant effect (at the 0.05 level) on post-activity window sill

lead loadings.

! Significantly positive linear correlation was observed between personal worker

exposure concentrations and dust sample loadings from SSDCs, whether wipe or

vacuum techniques were used. This implies that, for carpet removal, dustfall samples

may provide some information on potential lead concentrations in personal exposure

samples from workers, and vice versa.
8-22

8B-1.0 STUDY DESIGN IN THE WINDOW REPLACEMENT PHASE

Chapter 4 presented aspects of the EFSS study design that were common across all

phases. This section presents specific details of the study design as it was applied in the window

replacement phase.

8B-1.1 SAMPLING DESIGN FOR THE WINDOW REPLACEMENT PHASE

The sampling design for the window replacement phase was developed to address each of

the objectives presented in Section 6.1. Table 8B-1 presents the proposed types and numbers of

environmental field samples (both regular and QC samples) collected within each of four dwelling

units. The types of samples included the following:

! Personal exposure samples taken during the activity 

! Ambient air samples taken during the activity 

! Settled dust samples taken before the activity from the wells of three windows to be

removed

! Paint chip samples taken after the activity from interior and exterior components of

three removed windows

! Settled dust samples taken before and after the activity from floor surfaces at

varying distances from three windows to be removed

! Settled dust samples taken following completion of the activity from stainless steel

dustfall collectors (SSDCs) placed on the floor immediately prior to the activity

adjacent to and at 6 feet from each of three windows to be removed. 

In addition to these sample types, plastic tarpaulins were to be placed on the ground

directly beneath the three selected windows on the exterior of the unit, in order to collect dust

and other settled matter which settles on the exterior ground as a result of window replacement. 

However, exterior dust samples collected from these tarpaulins were archived for future

analysis and, therefore, were not included in the analysis in this phase.

In each unit, three windows slated to be removed were considered as the basis for each of

the settled dust and paint chip sample types. The windows were selected to represent all

approaches to window replacement, all types of windows being replaced, and the various lead

levels which could be encountered in the activity at the given unit. In addition, windows were

selected based on logistic issues, such as the availability of floor surface at specified distances

from the window for settled dust sampling. Figure 8B-1 displays the layout of settled dust

sampling locations at each selected window. 
8-23

Table 8B-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed in

the EFSS Window Replacement Phase Within Each Study Unit

Regular Samples

When Sample Sample Collection Number

Was Taken Method Sample Type/Location Proposed (1)

Pre-Activity Vacuum Settled dust (Window well) 3

Settled dust (Floor) 9

Ambient air pump Ambient air 1

During Personal air pump Personal air (R&R workers) 2

Activity Ambient air pump Ambient air (Adjacent room) 2

1-hr. Post- Vacuum Settled dust (Floor) 9

Activity Settled dust (SSDC) 6

2-hr. Post- Vacuum Settled dust (SSDC) 1

Activity

30-min. Post- Tarpaulin Debris deposit (Exterior) 3

Activity

(2)

Post-Activity Chipping Paint chip (Interior Window Sash) 3

Paint chip (Exterior Window Sash) 3

 TOTAL 42

Field QC Samples

When Sample Sample Collection Number

Was Taken Method Sample Type/Location Proposed (1)

Pre-Activity Vacuum SBS settled dust (Floor) 1

Field blank 1

Ambient air pump Field blank 1

Personal air pump Field blank 1

1-hr. Post- Vacuum SBS settled dust (Floor) 1

Activity SBS settled dust (SSDC) 1

 TOTAL 6

 (1) SSDC = stainless steel dustfall collector.

 SBS = sample taken side-by-side with a regular sample.

 (2) Samples archived; no analysis performed on these samples.

Immediately prior to the start of each window replacement, the field team collected one

vacuum dust sample within a one-square-foot area in each of the three floor sampling locations

represented by "P/P" in Figure 8B-1. The three locations are at 0, 3, and 6 feet perpendicular to

the window. Lead content within a pre-activity floor dust sample represented a baseline lead level

at the given location. 
P/P SSDC

Tarp

SSDC

3'

6'

(Not to interfere

with R&R workers)

Exterior

Interior

Activity Window

P/P = locations where pre- and post-activity dust samples were taken from the floor surface.

SSDC = locations where stainless steel dustfall collectors were positioned.

P/P

P/P

8-24

 Figure 8B-1. Settled Dust Sampling Locations at a Selected Window in the Window

Replacement Phase

A pre-activity ambient air sample was taken to obtain an estimate of baseline airborne lead

in the unit. As the ambient air samples took two hours to collect, the pre-activity ambient air

sample was sometimes taken on the day prior to window replacement.

Also prior to window replacement activities, the field team collected a vacuum dust sample

from the window wells of the selected windows. This sample was taken to assess the level of

available lead in dust from the given window, for a statistical evaluation of settled dust lead levels

resulting from the activity.

To evaluate how lead disturbance resulting from window replacement is associated with

lead levels in paint, paint chip samples were taken from the interior and exterior components of

the three windows being monitored. These samples were taken after the window was removed.

During window replacement activities, personal and ambient air samples were collected. 

Personal exposure sampling was conducted on up to two R&R workers per dwelling unit to
8-25

measure lead levels in air within the workers' breathing zones while they were performing window

replacement. Ambient air samples were collected in two rooms adjacent to one or more "activity

rooms" (i.e., rooms where window replacement took place) to measure lead levels in air dust that

could be inhaled by others present. No window replacement took place in rooms where ambient

air sampling occurred. When possible, doors to rooms where ambient air samples were being

collected were closed while window replacement was being performed.

Post-activity samples were taken of settled dust from floors and from one-square-foot

SSDCs positioned immediately prior to the start of the activity. At one hour following

completion of all window replacement activities (including cleanup), one vacuum dust sample was

collected in each of the three "P/P" sampling locations in Figure 8B-1, from an area adjacent to

the pre-activity vacuum floor dust sample area at that location. Results from this sample were

adjusted for the pre-activity sample result at that location. Also at one-hour post-activity, one

vacuum dust sample was collected from a SSDC positioned at 6 feet perpendicular to the

window.

A SSDC was also placed as close to each selected window as possible without disrupting

the normal activity of the R&R workers. To represent a "worst-case" scenario, a vacuum dust

sample was to be taken from this dustfall collector one hour following window replacement but

prior to the start of cleanup, or immediately prior to cleanup if the delay factor was unrealistic.

Finally, to determine whether lead "fallout" in settled dust increased after two hours

following the activity compared to one hour, a second SSDC was placed 6 feet from one of the

three selected windows in a unit. This SSDC was positioned adjoining the SSDC for the onehour post-activity vacuum sample. A vacuum dust sample was collected two hours following the

activity and cleanup. Results of comparison between one-hour and two-hour post-activity sample

lead loadings are found in Chapter 7. 

The nature of the field work and the number of samples made it impossible to collect a

sample at precisely one hour or two hours following completion of window replacement. Settled

dust samples were collected in a time frame spanning 15 minutes before to 40 minutes after the

scheduled time. Analysis of the effect of the time of sampling on the lead loading results was

given in Section 7.2 of Chapter 7.

Of the 48 environmental samples specified in Table 8B-1 within each dwelling unit, six were

field quality control (QC) samples. One field blank was taken prior to the start of window

replacement for every sampling medium (vacuum dust, personal air, ambient air) to determine the

extent to which contamination was present during sample collection. At one window, side-byside vacuum dust samples were taken from the floor surface and from a SSDC at 6 feet from the

window to allow sampling and measurement error to be characterized and variability in results

between two adjoining sample areas to be observed.

More details on the sampling design, including the protocols used to collect the samples,

are found in the Quality Assurance Project Plan.
8-26

8B-1.2 UNIT CHARACTERISTICS

Table 8B-2 lists the four dwelling units included in the window replacement phase, the

activity dates, and the rooms ("activity areas") within each unit that contained the three windows

selected for environmental sampling. The activity areas in two units were occupied, while the

activity areas of the other two units (Units 3-01 and 4-01) had been vacant and neglected for

some time.

Table 5-2 in Chapter 5 contains summaries of pre-activity lead loadings in these units. 

Chapter 5 also contains discussion of worker characteristics.

Table 8B-2. Dwelling Units Included in the EFSS Window Replacement Phase

Study Date of Type of R&R Activity

Unit ID Activity Unit Description Workers Areas (1) (2)

1-01 8/24/93 Two-story house; Professional Den

Piketon, OH; Contractor Kitchen

100 years old; Bathroom

new siding;

1968 remodeling;

2-01 9/14/93 Two-story house; Professional 2 Bedrooms

Columbus, OH; Contractor Hall

no age estimate;

peeling ext. paint;

3-01 9/15/93 One-story business; Self-Employed Large Room

Richwood, OH; Professional

150 years old;

brick/wood/concrete

exterior; activity area vacant

4-01 12/22/93 Second-floor apt.; Self-Employed 2 Living Rooms

Plain City, OH; Professional Bedroom

100 years old;

peeling ext paint; 

activity area vacant

All windows to be removed had painted wood frames. (1)

Except for unit 3-01, one window within each specified room (activity area) was selected for (2)

monitoring dustfall and paint lead levels. Other windows may also have been replaced within

these rooms. Unit 3-01 was not divided into rooms, so all three selected windows were in the

same large room.
8-27

8B-2.0 STUDY RESULTS FOR THE WINDOW REPLACEMENT PHASE

This chapter presents the results of the statistical analysis of environmental sample data

from the window replacement phase of the EFSS.

Analytical data were available for statistical analysis from all environmental field samples

that were collected in the window replacement phase. Table 8B-1 specifies 48 samples from each

of the four study units, for a total of 192 samples. Of these proposed samples, 186 were

successfully collected. The 6 uncollected samples included three tarpaulin samples and three floor

dust samples. In each unit, it was necessary to replace cassette samples during personal air

monitoring, resulting in additional cassette samples for analysis. One cassette had to be replaced

during ambient air sampling in unit 2-01 when a failed air pump was replaced, resulting in an

additional area air cassette sample. One additional tarpaulin sample and one additional exterior

paint chip sample were collected at unit 2-01, and one additional two-hour post-activity SSDC

sample at 6 feet from the window was collected at unit 3-01. (This latter sample was eliminated

from the statistical analysis because the SSDC was not placed until after cleanup). Analytical data

were available for a total of 193 regular and QC field samples in the window replacement phase. 

A summary of the samples collected and data received is displayed in Table WR-1 of Appendix A.

This section presents results and conclusions of the statistical analysis of data from the

window replacement phase. It is organized according to the method of organizing statistical

objectives given in Section 6.1. Supporting discussion and materials are included as Appendices

A through D. 

8B-2.1 CHARACTERIZE LEAD DISTURBANCE AND POTENTIAL LEAD EXPOSURE

Tables WR-2A through WR-6b in Appendix A contain summaries of lead concentrations

in personal and ambient air samples, and physical sample weights, lead loadings, and lead

concentrations in dust and paint chip samples. The summaries, presented for each study unit as

well as for the entire window replacement phase, include the arithmetic and geometric means, the

standard deviation of the log-transformed data, and the minimum and maximum observed values. 

As discussed in Chapter 6, statistical analysis of dust lead levels focused primarily on logtransformed lead loadings, or the amount of lead per unit surface area sampled. 

The lead disturbance and exposure data observed in the window replacement phase are

characterized below, according to the sample type or component sampled. Summaries are

presented for personal exposure, area air, and dustfall samples. Paint chip sample results are

summarized in Tables WR-6a and WR-6b, and Figure WR-3 of Appendix A.

8B-2.1.1 Personal Worker Exposures

The duration of personal air monitoring across the workers in this study ranged from 181

to 492 minutes, with an arithmetic mean of 335 minutes. Monitoring was started immediately

before area preparation began, and it continued through window replacement, disposal, and

cleanup activities (if any). Two workers were monitored in each of the four study units, resulting
8-28

in eight estimates of average personal air lead concentrations (in μg lead/m of air) over the 3

duration of activity (referred to as task-length averages (TLA)).

The task-length average lead concentrations from the personal air monitors are plotted for

each study unit along with lead concentrations from ambient air monitors in Figure 8B-2. All

concentrations represent instrument data above the detection limit. Descriptive statistics on

personal air lead concentrations are displayed in Tables WR-2a and WR-2b in Appendix A.

Figure 8B-2. Task-Length Average Personal Air Lead Concentrations, and Ambient Air

Sample Lead Concentrations, Within Each Study Unit in the Window

Replacement Phase

None of the eight monitored workers had personal air levels above the OSHA PEL of 50

μg/m . Personal air lead concentrations among the four study units ranged from 2.41 to 44.3 3

μg/m , with a geometric mean of 7.48 μg/m . 3 3

Figure 8B-2 illustrates that the variability among TLA personal exposure data from

different units is greater than the variability among the two data points within a unit, indicating

that workers within a unit are exposed to similar levels of lead while workers in different units are

generally exposed to much different levels of lead. Further statistical investigation of these two

components of variability is presented in Section 8B-2.2.4.
8-29

8B-2.1.2 Potential Occupant Exposures to Airborne Lead

In each study unit, one ambient air sample was collected prior to the activity and two

ambient air samples were collected during the window replacement activity. Pre-activity samples

were collected over a 120-minute interval (±4 minutes), except for one unit in which the sample

was collected over a 100-minute period. The sampler flow rate for pre-activity ambient air

samples was 12.5 L/min in three of the four units. In the fourth unit (4-01), which had no

electricity, a personal exposure sampler with a flow rate of 4 L/min was used. The ambient air

samples obtained during the window replacement activities were collected over intervals ranging

from 256 minutes to 486 minutes. The flow rates for all 8 activity samples were approximately

4 L/min.

The amount of lead collected within the sample cassette, the air pump flow rate, and the

duration of monitoring were used to calculate lead concentration in μg/m air for each sample (see 3

Figure 8B-2). Descriptive statistics on ambient air lead concentrations are displayed with the

personal worker exposure lead concentrations in Tables WR-2a and WR-2b of Appendix A. All

instrument data on ambient air samples were reported above the detection limit.

Figure 8B-2 illustrates the range of ambient air data observed during pre-activity periods

within each unit. Ambient air samples had lead levels that ranged from 0.10 to 2.86 μg/m . The 3

highest level occurred in the unit where the air flow rate was lowest. Lead levels for ambient air

samples collected during window replacement activity ranged from 0.29 to 4.16 μg/m , with a 3

geometric mean of 1.16 μg/m . The two highest ambient air levels were collected in the same unit 3

where the personal air levels were the greatest.

8B-2.1.3 Lead Disturbance and Potential Occupant Exposure to Lead in Dust

In the window replacement phase, settled dust was collected from three types of flat

surfaces to characterize lead disturbance and potential hazards to occupants from lead in dust. 

These three surface types, and when they were sampled in the study, were as follows:

! floor surfaces, sampled pre- and post-activity

! stainless steel dustfall collectors (SSDCs), placed immediately prior to activity and

sampled post-activity

! window wells in activity rooms, sampled pre-activity.

Dust samples from each surface type were collected on and in the vicinity of three windows being

removed. Section 8B-1 provides more detail about the sampling procedures, including the

locations and timing of each sample collected. 

The results of analysis on settled dust samples taken from each of the above three surface

types are summarized below.
8-30

8B-2.1.3.1 Vacuum Dust Samples Taken Pre- and Post-Activity from Floor Surfaces

Vacuum dust samples were collected from one-square-foot areas on floor surfaces prior to

the start of activity and at one hour following completion of activity. Sample locations were at 0,

3, and 6 feet from a window being removed. At each location, one pre-activity and one postactivity sample were taken from adjoining areas (Figure 8B-1). For each distance, results of

vacuum dust sampling (physical sample weight, lead loading, and lead concentration) directly

from the floor surface are summarized by unit and across all units in Tables WR-3a through WR3l in Appendix A. Boxplots of lead loadings and concentrations are included in Figures WR-1a

and WR-1b for pre-activity vacuum floor samples and in Figures WR-2a and WR-2b for postactivity vacuum floor samples.

Figure 8B-3 shows a scatterplot of the post-activity lead loadings versus the pre-activity

floor lead loading at the same window. The plotting symbols indicate the distance from the

window at which the samples were collected. Chapter 7 indicated that 9 of the 35 pre/post

sample pairs (non-QC samples) had lower lead loadings reported for the post-activity sample,

reflecting high spatial variability and/or analytical error in the data. The geometric mean lead

loadings (across all units) for regular and side-by-side QC samples taken pre- and post-activity

were 1920 and 3910 μg/ft at 0 feet, 491 and 1290 μg/ft at 3 feet, and 334 and 878 μg/ft at 6 22 2

feet, respectively. Thus, in spite of high variability, the geometric means of the lead loadings

(plotted in Figure 8B-4) indicate that there is a two- to three-fold increase in the lead loadings

from pre- to post-activity samples. These results confirm the expectation that the settled dust lead

loading decreases (for both pre-activity and post-activity samples) as the distance from the

window increases, implying that proximity to the window influences baseline lead loadings as well

as the post-activity loadings.

8B-2.1.3.2 Vacuum Dust Samples from Stainless Steel Dustfall Collectors

In addition to the floor dust samples described above, vacuum dust samples were taken

from SSDCs as an alternative measure of lead disturbance. Immediately prior to the start of

window replacement, SSDCs were placed at 0 feet and at 6 feet from each window to be

removed, and dust samples were collected from them at one hour post-activity. At one window,

an additional SSDC was placed at 6 feet for sampling at two hours post-activity. 

Tables WR-4a through WR-4d in Appendix A summarize physical weights, lead loadings,

and lead concentrations in samples from SSDCs collected at one hour and two hours following

completion of window replacement activities. The two-hour post-activity sample results were

compared with the one-hour results in Section 7.2 of Chapter 7. Also in Appendix A, boxplots of

lead loadings and concentrations for the one-hour post-activity dustfall collector samples are

presented in Figures WR-2a and WR-2b, respectively.
0 

1500 

3000 

4500 

1 3 6 

Distance from Window (ft)

1910 

491 

334 

3910 

1290 

878 

Pre-Activity Post-Activity

8-31

Figure 8B-3. Lead Loadings for Post-Activity Versus Pre-Activity Floor Samples at 0, 3,

and 6 Feet from the Windows

Figure 8B-4. Geometric Mean Lead Loadings from Floor Surfaces as a Function of Distance

from the Window
8-32

Lead loadings from dust collected on the SSDCs at 0 feet from the windows ranged from

3100 to 331,000 μg/ft , with a geometric mean of 24,700 μg/ft . At 6 feet from the windows, the 2 2

lead loadings among regular and side-by-side QC samples ranged from 15.4 to 4160 μg/ft , with a 2

geometric mean of 241 μg/ft .2

As discussed in Chapter 7, the SSDC method yields a better measure of lead disturbed by

the window replacement activity than the difference between post- and pre-activity lead loadings. 

Therefore, the SSDC measurements were used in creating an estimate of the lead disturbed by

window replacement that takes into account the "dustfall gradient," or the decrease in dust-lead as

distance from the activity increases. As introduced in Chapter 6, the dustfall gradient is

characterized by estimating the amount of lead (in μg) that settles within a 6-foot by 1-foot

rectangular region lying perpendicular to the window. Section C.5 of Appendix C presents the

approach to obtaining this estimate, its variability, and associated 95% confidence intervals. 

Table 8B-3 presents estimates of the average amount of lead disturbed in the 6-foot by 1-

foot gradient. The table contains estimates across all units and for each unit. The average

estimated lead disturbed across all four units was 46,300 μg, with a 95% confidence interval of

(251; 92,300) μg. These results were obtained by a single fitting of the model in Section C.5 of

Appendix C to all dust-lead results across all units. Average total lead estimates for the

individual units ranged from 15,500 μg to 96,000 μg. Because only three data points per unit

were available to calculate average lead amounts, the results for individual units were based on

calculating a separate estimate of lead disturbance in the 6-foot by 1-foot gradient calculated for

each of the three windows in a unit and averaging these three estimates. This difference in

method from the approach used when considering all units did not allow confidence intervals to

be calculated for the individual units.

Table 8B-3. Estimates of the Average Amount of Lead Disturbed by Window Replacement

Activity in a 6' by 1' Rectangular Region Perpendicular to the Window

Unit ID Gradient (μg) Lower Upper

Lead Disturbed in a 6' by 1' 95% Confidence Interval (μg)

All 4 units 46,300 251 92,300

1-01 15,500

2-01 51,800

3-01 96,000

4-01 66,000

Note: The methods for calculating lead amounts within each unit was slightly different from the method used to calculate

average lead amount across all units.

Further discussion of the dustfall gradient approach to comparing lead exposures among various

activities is given in Chapter 9.
8-33

8B-2.2 ASSESS FACTORS OR MEASUREMENTS RELATED TO LEAD DISTURBANCE

To characterize the statistical relationship between lead exposure in various media and

external predictor variables, as well as unit-to-unit and within-unit variability in the lead exposure

data, statistical models were developed and fitted to lead loading data in this phase using analysis

of variance (ANOVA) techniques. The models were fitted to lead loading data across all study

units.

Appendix C contains a detailed presentation of the statistical models, including tables of

the parameter estimates and their standard errors. Models are fit to the personal-air, ambient-air,

and SSDC sample results as well as to the estimates of lead disturbed in a 6-foot by 1-foot

gradient from a removed window. Because pre-activity floor lead loadings often exceed postactivity floor loadings, floor loading data were not modeled. Covariates considered include lead

loadings from all of the pre-activity samples (floor dust, window well dust, and paint chip) taken

during the window replacement phase.

 In the window replacement phase, model fittings were performed on relatively small

numbers of data points. Thus, only one or two covariates were considered at any one time in

modeling lead loadings. In addition, because the few data points had relatively high variability,

the tests for significant covariate effects tended to have low power. Therefore, findings of

statistically insignificant results may indicate no effect or merely little power to detect the effect. 

Conversely, the relatively large number of separate model fittings required by the small number of

data points leads to a concern over the effect of multiple tests on the true significance level of

statistically significant parameters. Due to the exploratory nature of the model fitting in this

phase, alpha levels for statistical significance were not adjusted for the effect of multiple tests.

ANOVA models also characterized error in log-transformed lead loading data from three

sources: unit-to-unit variability, within-unit (window-to-window) variability, and replicate-toreplicate variability at a window. Unit-to-unit variability is estimable because sampling was done

at four study units. Within-unit variability is estimable because samples were collected at three

windows within each study unit. For some sample types, replicate-to-replicate variability,

representing variability in sampling at the same physical location, was estimable due to taking two

side-by-side samples at the same distance from a window. 

A summary of the results of pre-activity vacuum dust samples from window well surfaces

is presented in Section 8B-2.2.1. Results of the model fits on during- and post-activity sample

data are presented in Section 8B-2.2.2. In addition, the relationship between dustfall lead

loadings and the distance from the windows is examined using the results obtained from SSDCs. 

The results of fitting the model relating lead exposure to distance are contained in Section 8B2.2.3. Estimates of variance components for the log-loading data are presented in Section 8B2.2.4. 
8-34

8B-2.2.1 Vacuum Dust Samples from Window Well Surfaces Taken Pre-Activity

Pre-activity vacuum dust samples were collected from the window wells selected in each

unit. The samples were collected to help characterize the units with respect to the lead levels

found prior to window replacement activities, and to use as potential predictors of lead exposure

resulting from window replacement.

Tables WR-5a and WR-5b in Appendix A present data summaries for the pre-activity

window well dust samples. One sample was eliminated from the statistical analysis because its

observed lead concentration and loading were judged to be outliers (significantly smaller than and

inconsistent with the results of the other window well samples). Summary statistics shown in

Tables WR-5a and WR-5b are calculated both with and without the outlier. Figures WR-1a and

WR-1b in Appendix A compare the lead loadings and concentrations, respectively, of the preactivity window-well samples with the pre-activity floor samples using boxplots.

The lead loadings of the window well dust samples ranged from 26,800 to 415,000 μg/ft2

(after removal of the outlier), with a geometric mean of 135,000 μg/ft .2

8B-2.2.2 Lead Disturbance as a Function of Pre-Activity Lead Loadings

Model (C-1) presented in Section C.1 of Appendix C was fitted to data from the following

sample types collected during or after window replacement activities:

! lead concentrations in personal exposure samples

! lead concentrations in ambient air samples 

! lead loadings in SSDC dust samples.

In addition, Model (C-1) was fitted to the estimated amount of lead disturbed in a 6-foot by 1-

foot gradient, discussed in Section 8B-2.1.3.2. Each fit of these models contained random effects

representing unit-to-unit and within-unit variability (no side-by-side QC sample results were

included), as well as one of the following fixed covariates:

#1. pre-activity lead loading on floor surfaces at 0 feet from the window.

#2. pre-activity lead loading on floor surfaces at 3 feet from the window.

#3. pre-activity lead loading on floor surfaces at 6 feet from the window.

#4. pre-activity lead loading on window well surfaces.

#5. lead loadings within paint chips collected from the interior sash/frame of the window.

#6. lead loadings within paint chips collected from the exterior sash/frame of the

window.

#7. pre-activity ambient air lead concentrations.

Table 8B-4 summarizes the approach to fitting Model (C-1), indicating those covariates whose

effects on the data were significant at the 0.05 level. Model (C-1) takes the form of models (WR1) through (WR-5) when fitting to a specific data type (Table C-2 of Appendix C). Only one of

the covariates was consistently significant when modeling the different sample types: pre-activity
8-35

lead loading on floor surfaces at 3 feet from the window (covariate #2). Ambient air lead

concentrations during the activity were significantly associated with pre-activity floor lead

loadings at each distance from the windows, indicating that ambient air results were likely

dominated by the pre-activity level of dirtiness existing within the study units. 

Table 8B-4. Results of Tests for Significant Covariates in the Model Fitting to Lead

Loading Data in the Window Replacement Phase

Modeled Data (Table C-2 of Appendix C) Models

Models Fitted the 0.05 Level in the Fitted

Covariates Significant at

Personal exposure Model (WR-1) fit seven times, each

sample concentrations considering one of the seven covariates. Covariate #2

Ambient air sample

concentrations (during Covariates #1, #2, #3

activity)

Model (WR-2) fit six times, each

considering one of covariates #1 to #6,

with covariate #7 always included in the

model.

SSDC dust-lead sample Model (WR-3) fit six times, each

loadings at 0 feet from considering one of covariates #1, #2, #4, Covariate #2

window #5, #6, #7.

SSDC dust-lead sample

loadings at 6 feet from None

window

Model (WR-4) fit six times, each

considering one of covariates #2 to #7.

Estimated lead amount

in 6'x1' gradient from Covariate #2

window

Model (WR-5) fit seven times, each

considering one of the seven covariates.

The significance levels for the tests of significant covariate effects were not adjusted for the large

number of tests performed in this exercise. 

More detailed results of the model fittings are presented in Section C.1 of Appendix C.

8B-2.2.3 Lead Disturbance as a Function of Distance from the Windows

Lead disturbance resulting from renovation and remodeling activities was expected to vary

with the distance from the activity. Field sampling within the window replacement phase of the

EFSS was designed so that this relationship could be explored. Floor dust samples were collected

(pre- and post-activity) at 0, 3, and 6 feet from the windows being replaced. SSDCs were placed

at 0 and 6 feet from the same windows. The sample results can be used to determine how lead

loadings change over distance.
8-36

In Section 8B-2.1.3.1, a summary of the results of the pre-activity and post-activity floor

dustfall samples was presented. The difference between post- and pre-activity floor lead loadings

represented lead disturbance resulting from window replacement activities. These observed

differences were not well-behaved: nine of the 35 differences were negative, and the variability of

the differences was very large (Figure 8B-3). 

Figures 8B-5a and 8B-5b are plots of the lead loadings from pre-activity and post-activity

floor dust samples, respectively, versus the distance from the windows at which the samples were

collected. The plotting symbols indicate the unit from which the samples were collected. Lines

are drawn connecting observations taken at the same window. In both cases, measured lead

loadings tended to decrease as distance from the windows increased. Figure 8B-5c plots the

difference in lead loadings between adjoining post- and pre-activity floor samples versus the

distance at which the samples were collected. This figure clearly shows the effect of the negative

differences and the large variability in the differences. For this reason, statistical models in the

previous section were not fitted to floor sample lead loadings. 

Figure 8B-6 is a plot of lead loadings for the one-hour post-activity samples taken from

SSDCs versus the distance from the windows at which the samples were collected. Although

only two distances per window were considered, this figure indicates that lead loadings from

SSDC dustfall samples have a more consistent decreasing trend in the lead loading as the distance

from the window increases, compared to trends seen in the other plots for floor dustfall samples. 

Model (C-3) in Section C.3 of Appendix C was fitted to evaluate the relationship between

one-hour post-activity lead loading data (μg/ft ) from SSDCs and distance from the window being 2

removed. The estimated slope parameter associated with distance was -0.732, which was

statistically significantly different than 0 at the 0.0001 level. This result indicates that as one

moves one foot farther away from the window, the log-transformed lead loading decreases by

approximately 0.732, or the untransformed lead loading is reduced by approximately (1-e ) * -0.732

100% = 52%. 

 Because of the significant distance effect on SSDC lead loadings, it was decided that the

amount of lead disturbed in a 6-foot by 1-foot gradient extending from the window would be a

better overall estimate of the lead disturbed by window replacement activities than estimates made

at a single distance.
8-37

Figure 8B-5a. Lead Loadings (μg/ft ) for Pre-Activity Floor Samples Versus Distance from 2

the Windows at Which the Samples Were Taken

Figure 8B-5b. Lead Loadings (μg/ft ) for Post-Activity Floor Samples Versus Distance from 2

the Windows at Which the Samples Were Taken
8-38

Figure 8B-5c. Lead Loadings (μg/ft ) for Differences Between Adjoining Post-Activity and 2

Pre-Activity Floor Samples Versus Distance from the Windows at Which the

Samples Were Taken

Figure 8B-6. Lead Loadings (μg/ft ) for One-Hour Post-Activity SSDC Samples Versus 2

Distance from the Windows at Which the Samples Were Taken
8-39

8B-2.2.4 Estimating Variance Components 

The sampling design for the window replacement phase specified sample collection over

multiple study units, multiple locations (or workers) within a study unit, and that settled dust

samples be taken in multiple areas within locations (i.e., side-by-side QC samples). This design

provided for key sampling components of total data variability to be isolated and characterized. 

Therefore, when estimable, the magnitudes of the following variance components were estimated

for several sample types (where appropriate) using random-effects analysis of variance:

! "unit-to-unit" variability

! "location-to-location" (or worker-to-worker) variability within a unit (window-towindow)

! "replicate-to-replicate" variability within a location.

Variance components were estimated for the following lead measurements:

! pre-activity floor dust lead loadings (separately at 0, 3, 6 feet)

! post-activity floor dust lead loadings (separately at 0, 3, 6 feet)

! 1-hour post-activity SSDC vacuum lead loadings (separately at 0, 6 feet)

! pre-activity window well dust lead loadings 

! paint chip lead loadings (separately for interior, exterior)

! personal air lead concentrations

! pre-activity ambient air lead concentrations

! during-activity ambient air lead concentrations

! lead amounts in a 6' x 1' gradient.

Replicate-to-replicate variability could only be estimated for the lead measurements in the first

three items listed, because these were the only sample types where side-by-side QC samples were

taken.

It is assumed that total variability is the sum of the variabilities associated with the three

components listed above. Any additional variance components are confounded within one or

more of these components. 

Model (C-2) presented in Section C.2 of Appendix C was fitted to the lead measurements

to estimate the variance components for the various sample types. Table 8B-5 contains the

estimated total variability in these (log-transformed) measurements, plus estimates of the

components of the total variability. The results represent variability in the log-domain, so they are

expressed in log units. 
. Estimates of Total Variability and its Estimable Components in Log-Transformed Lead Measurements

By Sample Type in the Window Replacement Phase

Sample Type Measurement Variability : F Unit-to-unit (F ) a unit (F ) a location (F ) (1)

Model Estimate Square Root of Location-to- Replicate-toof Mean Log Estimated Total location within replicate within

(2) (3)

tot

 Square Roots of Estimated Variance Components(4)

UL R

 at 0 feet 7.56 3.92 3.46 (77.8%) 1.52 (15.0%) 1.05 (7.2%) at 3 feet 6.04 3.43 3.23 (88.6%) 0.68 (3.9%) 0.94 (7.5%) at 6 feet 5.79 3.36 3.21 (91.5%) 0.60 (3.2%) 0.78 (5.4%) (5)

t at 0 feet 8.27 3.26 2.90 (79.0%) 1.05 (10.4%) 1.06 (10.5%)t at 3 feet 7.11 2.66 2.38 (80.4%) 0.31 (1.4%) 1.13 (18.2%)t at 6 feet 6.76 3.27 3.11 (90.8%) 0.73 (5.0%) 0.67 (4.2%) (5)

SSDC Dust (vacuum) at 0 feet 10.1 1.67 0 (0%) 1.52 (83.7%) 0.67 (16.3%)SSDC Dust (vacuum) at 6 feet 5.4 1.86 1.14 (37.6%) 0.93 (24.8%) 1.14 (37.5%) (5)

w Well 11.5 1.54 0.99 (41.6%) 1.17 (58.4%) ---

0.79 2.54 2.46 (93.5%) 0.65 (6.5%) ---

2.40 1.50 1.02 (46.5%) 1.10 (53.5%) ---

2.01 1.26 1.11 (77.6%) 0.60 (22.4%) ---

nt air -1.21 1.58 1.33 (71.4%) 0.84 (28.6%) ---

ent air 0.15 0.86 0.72 (69.5%) 0.47 (30.5%) ---

ot Gradient 10.8 1.56 0 (0%) 1.56 (100%) ---

less steel dustfall collectors. 

e intercept term from the random effects model. 

y = F = F + F + F , where these parameters were estimated from the random effects model using restricted maximum likelihood. tot U L R 2 222

entheses is the percent of total variability (F ) represented by the given variance component (the square of the tabled value). 2tot

amples were included with the floor dust and SSDC dust samples when estimating variance components. 
8-41

For pre-activity and post-activity floor samples at all three distances, over 75% of

variability in the lead loadings was attributed to results from different units; there was no clear

pattern in the within-unit and replicate-to-replicate variabilities. For samples collected from

SSDCs, the results were mixed: at 6 feet from the windows, all three sources of variability made

roughly equal contributions to the total variability; at 0 feet from the windows, within-unit

variability was about five times as large as the replicate-to-replicate variability. The total

variability of both pre-activity and post-activity floor sample data exceeds that of the SSDC

samples.

The estimated within-unit variance of window well loadings was about 1.5 times as large

as the estimated unit-to-unit variance. The unit-to-unit variance among the interior paint-chip

loadings was 14 times greater than the within-unit variability, while the unit-to-unit and withinunit variabilities were roughly equal for exterior paint chip loadings. The unit-to-unit variability in

log-transformed personal air lead concentrations was four times greater than the within-unit

variability, indicating that workers involved in window replacement at a given site are exposed to

similar lead levels within their breathing zones. The results for ambient air samples are similar to

those of personal exposure samples, with the unit-to-unit variability 2.5 times greater than withinunit variability for both pre-activity and post-activity samples.

8B-2.3 CORRELATIONS BETWEEN LEAD IN DIFFERENT SAMPLE MEDIA

To quantify the extent of the linear relationship between lead exposure estimates from

different sample types and sample collection approaches, Pearson correlation coefficients were

calculated among pairs of twelve variables that measure lead levels in various media through the

study. The variables of interest include:

! pre-activity dust lead loadings on floors (0, 3, 6 feet)

! pre-activity dust lead loadings on window wells

! 1-hour post-activity dust lead loadings on SSDCs (0, 6 feet)

! 2-hour post-activity dust lead loadings on SSDCs (6 feet)

! estimates of total lead disturbed in a 6-foot by 1-foot gradient 

! lead concentrations in personal air and ambient air samples collected during window

replacement activity

! lead loadings in interior and exterior paint chips from window sashes and frames.

Post-activity floor dust lead loadings were not included in this analysis because of the previous

decision to use SSDC measurements as the preferred indicator of lead generated in settled dust by

the activity (see Chapter 7). For each variable, the geometric mean of the observed data was

calculated for the four study units. The estimated total lead in the 6-foot by 1-foot gradient was
8-42

calculated as discussed in Section 8B-2.1.3.2. Pearson correlation coefficients associated with

these geometric means were calculated for each pair of variables. Table 8B-6 presents these

correlations. A low correlation between two variables does not necessarily imply the lack of a

relationship, as the relationship may not be linear in nature or the sample size may have not have

been large enough to detect such a relationship.

Because each of the correlations was calculated using only four observations, only

correlations that are greater than 0.95 are statistically significantly different from 0 at the 0.05

level. Correlation coefficients greater than 0.9 are statistically significantly different from 0 at the

0.10 level. 

Table 8B-6 shows several strong correlations that are of particular interest:

! The strong correlations between personal air lead concentrations, lead loadings in

one-hour post-activity SSDC samples at 0 feet from the windows, ambient air lead

concentrations, and the estimated lead amount disturbed in a 6-foot by 1-foot

gradient indicate a probable relationship between a worker's exposure and the lead

generated as a potential exposure to occupants. This suggests that a single medium

may be considered in future studies as an indicator of both worker exposure and

potential occupant exposure

! The strong correlation between dust lead loadings from pre-activity floor samples at 0

feet from the windows and lead loadings in interior paint chip samples suggests that

the high levels of lead in dust on the floor near the windows may be due to high levels

of lead in paint on the interior surfaces of the windows rather than from lead tracked

or blown into the unit.

A strong correlation between personal worker lead concentrations and post-activity SSDC lead

loadings was also noted in the carpet removal phase. While correlation between personal worker

exposure, floor dust loadings, and ambient air concentrations was somewhat lower in the carpet

removal phase than that observed for window replacement, the small numbers of data points may

imply no statistical difference between phases.

8B-2.4 SUMMARY OF RESULTS

Following is a summary of the major results observed in the EFSS window replacement

phase:

! None of the lead concentrations within personal air samples exceeded the OSHA PEL

of 50 μg/m . Personal air lead concentrations ranged from 2.41 to 44.3 μg/m with a 3 3

geometric mean of 7.48 μg/m . Estimated variability in these data were primarily the 3

result of sampling in different study units. 
6. Pearson Correlation Coefficients of the Geometric Mean Lead Loadings Between Pairs of Sample (1)

Types and Approaches in the Window Replacement Phase

D=0 D=3 D=6 Well Chip Ext. Chip Int. D=1 D=6 D=6 Air Exp. Gradient

Pre Floor Pre Floor Pre Floor Window Paint Paint SSDC SSDC SSDC Ambient Personal Lead

(2)

1-Hr. 1-Hr. 2-Hr. 6' x 1'

1.00 0.847 0.999 0.129 -0.495 0.903 0.463 0.744 0.836 0.420 0.420 0.655

1.00 0.827 0.267 -0.174 0.754 0.829 0.292 0.416 0.832 0.838 0.892

1.00 0.119 -0.511 0.902 0.433 0.767 0.855 0.387 0.386 0.632

1.00 0.769 -0.296 0.618 0.101 -0.050 0.452 0.327 0.662

1.00 -0.772 0.395 -0.513 -0.664 0.309 0.214 0.271

1.00 0.260 0.596 0.762 0.302 0.360 0.402

1.00 -0.110 -0.062 0.978 0.941 0.961

1.00 0.972 -0.229 -0.264 0.169

1.00 -0.141 -0.147 0.202

1.00 0.991 0.901

1.00 0.851

alculated on geometric means calculated for each study unit (n=4). All correlations greater than 0.95 are significantly different from zero at the

nce from window (in feet).
8-44

! Lead concentrations within ambient air samples collected during window replacement

activity ranged from 0.29 to 4.16 μg/m with a geometric mean of 1.16 μg/m . 3 3

! The difference in lead loadings from floor dust samples taken pre- and post-activity

had high variability in this study. Across all floor dust samples, the geometric mean

lead loading increased from 2.0 to 2.6 times from pre- to post-activity at the various

distances from the window. Some pre-activity sample lead loadings were actually

larger than the loadings in the adjoining post-activity samples.

! Lead loadings from SSDC samples had substantially lower variability than the

difference between post- and pre-activity floor lead loadings. This indicates that the

SSDC method may yield a more accurate and precise measure of the lead disturbed

by window replacement than the difference in pre- and post-activity floor dust

samples. The geometric mean of the lead loadings collected from SSDCs one hour

after completion of the window replacement was 24,700 μg/ft at 0 feet from the 2

window and 241 μg/ft at 6 feet from the window, indicating the significant effect of 2

distance from the activity on observed load levels. An estimate of the total amount

of lead disturbed in a 6-foot by 1-foot gradient was calculated for each window. The

estimate of the average amount of lead disturbed in a 6-foot by 1-foot gradient for

window replacement activities in this study was 46,200 μg. 

! Of the covariates providing information on pre-activity lead levels, only the preactivity lead loadings on floor surfaces at 3 feet from the window was consistently

significant at the 0.05 level when modeling during- and post-activity lead disturbance

in various media. Small sample size, high variability and multiple model fittings make

these results very tenuous, however, and only exploratory in nature.

! The strong correlations between the lead loadings from personal worker exposure

samples, one-hour post-activity SSDC samples at 0 feet from the windows, area air

samples, and the estimated lead disturbed in a 6-foot by 1-foot gradient indicates a

probable relationship between a worker's exposure and the lead generated as a

potential exposure to the occupants. 
8-45

8C-1.0 STUDY DESIGN IN THE CED PHASE

This section presents the study design for the Controlled Experimentally-Designed (CED)

phase of the EFSS study. The primary objective of this phase was to estimate lead disturbances

and potential lead exposures associated with several target R&R activities and generic activities

which are difficult to isolate in an actual R&R job or are ingredients to larger R&R activities. In

addressing this objective, the CED phase offered a controlled, simulated R&R environment in

which R&R activities of interest were performed and environmental samples were collected.

The activities in the CED phase were classified into one of the following three primary

categories:

1. simulated R&R target activities (e.g., demolition)

2. generic R&R tasks (e.g., drilling and sawing)

3. a positive control activity (paint removal, for comparison purposes).

The components of each activity category are discussed in Section 8C-1.1. 

The CED phase was conducted using skilled R&R workers and laborers who were

familiar with protective measures and methodologies used in the lead-abatement industry. These

R&R workers were contracted by the project team to perform the designated R&R tasks within

each study component, and they were instructed to perform the tasks as they are typically

conducted in an unregulated environment. The workers were protected according to the

procedures approved by the human subjects review committees of Battelle, MRI, and EPA.

The CED phase consisted of three "case studies" (or "sites"), each constituting one or

more related vacant buildings slated for subsequent gutting, gut rehab, or complete abatement and

clearance testing before reoccupancy. Two sites, each consisting of a single row house, were

located in Baltimore, Maryland. The third site consisted of a group of four dwelling units in

Denver, Colorado. It was expected that the unique characteristics of each site would cause

slightly differing approaches to applying the overall study and sampling design for each activity

occurrence. This was reflected in the decision to develop a separate sampling plan for each site. 

Nevertheless, for the most part, the different R&R tasks within each study component were able

to be replicated across sites and were often replicated within sites. This allows for an assessment

of not only the potential lead exposure associated with each different CED activity, but also of the

variance components associated with the measures of those lead exposures.

8C-1.1 SAMPLING DESIGN FOR THE CED PHASE

The carpet removal and window replacement phases of the EFSS study (Sections 8A and

8B) were designed as observational studies in which only the types and locations of the samples

were specified in the sampling design. In contrast, the CED phase, as its title suggests, was

designed to control not only the type and location of samples, but also the type and conduct of

R&R activity.
8-46

The sections which follow contain discussions of the two aspects of the sampling design

for the CED phase: descriptions of the activities that were included in the study, and the types

and locations of samples that were collected to monitor lead exposure as a result of performing

the activities.

8C-1.1.1 CED Activities

As mentioned above, three primary categories of R&R activities were included in the CED

phase: simulated R&R target activities, generic R&R activities, and a positive control activity.

In an attempt to replicate each R&R activity across the different "sites" in the study, the

actual work that was to be performed as part of the activity was defined prior to the start of data

collection. Because each study site was unique, separate test plans for each study site were also

prepared that presented specifications of where, when, and how each activity was to be performed

at each of the three sites. Following is a general description of activities conducted within each

activity category in the CED phase (more detailed descriptions are provided in the CED QAPjP

addendum).

Category #1: Simulated R&R Target Activities

1. Demolition. In each study unit, three large structure removal activities were planned. 

These activities consisted of demolishing one or more walls in the study units. In

most cases, a single plaster wall was removed. However, in some situations, one or

more walls consisting of drywall, wood, or plaster were removed. Removal of walls

that separated rooms were limited to one room, and the activity was planned so that

there was no damage to the wall of the room backing the wall that was demolished. 

Removal of exterior walls was planned so that there was no damage to the underlying

structure of the wall (usually brick). In all cases, the end result of the demolition was

to be an exposed wall structure completely ready for the installation of new drywall.

2. HVAC Removal. In each study unit, one HVAC repair/ replacement activity was

planned. This activity consisted of removing several sections of the HVAC

ductwork. The activity was designed to prepare the HVAC system for the

installation of new ductwork. (Actual HVAC removal was performed only at the

Baltimore units).

3. Small Surface Disruption. The CED QAPjP Addendum lists several examples of

activities that fit into the category of small surface disruptions. The activity that was

chosen for the CED phase was Door Modification. This activity consisted of two

subtasks -- trimming wood from the edge of an existing door (and sanding it

smooth), and drilling a hole for installation of a doorknob -- which were designed to

mimic actual work that might be performed as part of an R&R job. Two door

modification activities were scheduled for each unit. Because it was expected that

the time required to perform the modification of a single door would be too short to

provide for reasonable samples, several doors were included in the door modification
8-47

activity. The activity consisted of trimming an inch from one end of the door (top or

bottom), drilling a hole for a doorknob, and trimming an inch from the other end of

the door. The choice of tools for performing this activity was left to the discretion of

the worker. (Note: When this activity was conducted in the field, workers lost track

of the number of doors modified. Therefore, exposure results are presented as a

generic R&R task involving cutting and sanding rather than as an example of the

small surface disruption target activity.)

Category #2: Generic R&R Activities

An objective of the CED phase was to determine lead exposures associated with several

generic components of larger R&R activities. The planned generic activities were as follows: 

1. Sawing. The sawing activities involved making a series of fifteen parallel cuts (5 feet

in length) into either plaster or wood substrates using either a rough blade or a fine

blade. Four activities were planned, using each combination of substrate and blade. 

The cuts into plaster walls were separated by three inches in the vertical direction,

and the cuts into wood baseboards removed from walls were made at one-inch

intervals.

2. Drilling. The drilling activities involved drilling a lattice of holes into either plaster

or wood substrates using either a small or large drill bit. Four activities were

planned, using each combination of substrate and drill bit. Wood drilling was done

into walls (when available) or into doors, and plaster drilling was done into walls. 

The lattice of holes for all drilling activities was 3 feet wide and 2 feet high (or viceversa). With the small drill bit, holes were drilled every inch in both horizontal and

vertical directions (925 holes), and with the large drill bit, holes were drilled every 3

inches (117 holes).

3. Building Component Removal. The CED QAPjP Addendum recognized the

possibility of monitoring additional R&R activities if the opportunity presented itself. 

In the first dwelling unit in Denver, different building components needed to be

removed prior to conducting R&R activities on them. This opportunity allowed the

removal of lead-painted wood trim, baseboards, doors, and door-jams to be

monitored in this unit as a simulated R&R target activity. 

4. Cleanup. Cleanup activity was monitored by personal air concentrations only (as

opportunity allowed). New filter cassettes were inserted in the personal exposure

monitors at the start of cleanup activity, so that cleanup exposures could be clearly

separated from exposures resulting from the earlier R&R activity.

The first two activities also provided a basis for comparison of different tools and different

substrates with regard to their effect on lead exposure. 
8-48

Category #3: Positive Control Activity

Paint removal was conducted at each CED study unit. This activity was performed at

one location per unit where two or three windows were available. Potential lead exposure

associated with paint removal has been studied and cited in the literature in detail; thus paint

removal acted as a positive control activity to which results of the other CED activities could be

compared. Paint was removed from the windows using abrasive techniques, thereby acting as a

"worst-case" positive control. Half of the available area had paint removed by hand scraping

and sanding while the remaining portion had paint removed using power sanding. 

In all activities performed in the EFSS, vacuum attachments were not used on any tools. 

In addition, no dust reduction methods, such as wetting, misting, or negative air, were employed.

Before any of the activities at a given building were performed, the building was prepared

according to normal abatement procedures, including creation of a decontamination area, tool

cleanup area, sealing of floors and rooms with poly, and other safety and activity preparations.

8C-1.1.2 Sample Types and Locations

The inclusion of different R&R activities at different sites in the CED phase required some

flexibility in sampling plans across activities and sites. In general the sampling plan for the

collection of environmental field samples was consistent within each type of CED activity. 

Wherever possible, sampling was done in a consistent manner across CED activities. This section

presents the sampling plan and protocols that were consistent across activities and sites. Table

8C-1 presents the specific implementation of the sampling plan for each site and activity in the

CED phase.

The primary types of samples taken in the CED study included the following:

! Personal exposure samples taken during the activity

! Paint chip samples taken before the activity from plaster and painted-wood

surfaces disturbed by the activity

! Plaster samples taken before the activity from plaster walls used for the activity, to

measure the amount of lead in the substrate which can be disturbed during the

activity

! Settled dust samples taken via wipe techniques from HVAC components, to

measure the amount of lead which can be disturbed during HVAC removal

! Settled dust samples taken via vacuum or wipe techniques following completion of

the activity from stainless steel dustfall collectors (SSDCs) placed on the floor

immediately prior to the activity, and at areas adjacent to and at varying distances

away from the activity. 
8-49

Table 8C-1. Sampling Design for Each CED Activity Within Each Study Unit

City/

Building No./ Room Samples

Activity No. Activity Day/Time Worker Description Collected

Baltimore Drilling Wood Day 1-1 1A South Basement 1 Personal Exposure

Building 1 925 Holes with 1⁄4" Bit 07:16 - 08:10 5 Settled Dust

Activity 1 1 Paint Chip

Baltimore Drilling Plaster Day 1-2 1A 2nd Floor Bathroom 1 Personal Exposure

Building 1 925 Holes with 1⁄4" Bit 10:17 - 11:42 5 Settled Dust

Activity 2 1 Paint Chip/1 Plaster

Baltimore Drilling Wood Day 1-1 1B North Basement 1 Personal Exposure

Building 1 117 Holes with 1" Bit 15:34 - 15:54 5 Settled Dust

Activity 3 1 Paint Chip

Baltimore Drilling Plaster Day 1-2 1B North Bedroom 1 Personal Exposure

Building 1 117 Holes with 1" Bit 10:34 - 10:51 2nd Floor 5 Settled Dust

Activity 4 1 Paint Chip/1 Plaster

Baltimore Sawing Plaster Day 1-1 1B Foyer 1 Personal Exposure

Building 1 40 Feet with Circular Saw 08:04 - 08:34 5 Settled Dust

Activity 5 1 Paint Chip/1 Plaster

Baltimore Sawing Wood Day 1-1 1B South Bedroom 1 Personal Exposure

Building 1 75 Feet with Circular Saw 14:28 - 15:14 3rd Floor 5 Settled Dust

Activity 6 (Rough Blade) 2 Paint Chip

Baltimore Door Modification Day 1-2 1A North Bedroom 1 Personal Exposure

Building 1 08:08 - 09:39 3rd Floor 5 Settled Dust

Activity 7 2 Paint Chip

Baltimore Sawing Wood Day 1-1 1B South Bedroom 1 Personal Exposure

Building 1 75 Feet with Circular Saw 09:04 - 09:38 3rd Floor 5 Settled Dust

Activity 9 (Smooth Blade) 2 Paint Chip

Baltimore Door Modification Day 1-1 1A North Bedroom 1 Personal Exposure

Building 1 Doors from Baltimore(2) 14:18 - 15:30 3rd Floor 5 Settled Dust

Activity 10 2 Paint Chip

Baltimore HVAC Removal Day 1-2 1B 1C Basement 2 Personal Exposure

Building 1 08:24 - 08:46 10 Settled Dust

Activity 11 4 Interior Duct Wipes

Baltimore Abrasive Paint Removal Day 1-2 1A 1B South Bedroom 3 Personal Exposure

Building 1 14:30 - 15:53 2nd Floor 8 Settled Dust

Activity 12 3 Paint Chip

Baltimore Demolition of East Wall Day 1-3 1A 1B 1C Living Room 3 Personal Exposure

Building 1 08:12 - 08:41 10 Settled Dust 

Activity 13 1 Paint Chip/1 Plaster

Baltimore Demolition of West Wall Day 1-3 1A 1B North Bedroom 2 Personal Exposure

Building 1 09:34 - 11:28 2nd Floor 10 Settled Dust

Activity 14 1 Paint Chip/1 Plaster

Baltimore Demolition of Closet Day 1-3 1A 1B Basement 2 Personal Exposure

Building 1 13:37 - 14:01 10 Settled Dust

Activity 15 2 Paint Chip/1 Plaster

Baltimore Drilling Wood Day 1-3 1A North Bedroom 1 Personal Exposure

Building 1 925 Holes with 1⁄4" Bit 15:18 - 15:59 3rd Floor 5 Settled Dust

Activity 81 1 Paint Chip

Baltimore Drilling Plaster Day 1-1 1A 2nd Floor Bathroom 1 Personal Exposure

Building 1 925 Holes with 1⁄4" Bit 08:33 - 08:48

Activity 82
Table 8C-1 (Continued)

City/

Building No./ Room Samples

Activity No. Activity Day/Time Worker Description Collected

8-50

Baltimore Drilling Wood Day 2-1 2A Kitchen 1 Personal Exposure

Building 2 925 Holes with 1⁄4" Bit 09:11 - 10:34 5 Settled Dust

Activity 1 1 Paint Chip

Baltimore Drilling Plaster Day 2-1 2A Bathroom 1 Personal Exposure

Building 2 925 Holes with 1⁄4" Bit 11:00 - 12:23 3rd Floor 5 Settled Dust

Activity 2 1 Paint Chip/1 Plaster

Baltimore HVAC Removal Day 2-1 2B 2C Front Bedroom 2 Personal Exposure

Building 2 14:30 - 15:44 2nd Floor 5 Settled Dust

Activity 3 3 Interior Duct Wipes

Baltimore Drilling Wood Day 2-1 2A Kitchen 1 Personal Exposure

Building 2 117 Holes with 1" Bit 13:42 - 14:02 5 Settled Dust

Activity 4 1 Paint Chip

Baltimore Drilling Plaster Day 2-1 2A Bathroom 1 Personal Exposure

Building 2 117 Holes with 1" Bit 15:05 - 15:26 3rd Floor 5 Settled Dust

Activity 5 1 Paint Chip/1 Plaster

Baltimore Sawing Wood Day 2-1 2B Rear Bedroom 1 Personal Exposure

Building 2 75 Feet with Circular Saw 08:23 - 08:52 3rd Floor 5 Settled Dust

Activity 6 (Rough Blade) 2 Paint Chip

Baltimore Door Modification Day 2-1 2A Center Bedroom 1 Personal Exposure

Building 2 08:08 - 09:39 3rd Floor 5 Settled Dust

Activity 8 3 Paint Chip

Baltimore Sawing Plaster Day 2-1 2A Bathroom 1 Personal Exposure

Building 2 47.5 Feet with Sawzall 15:37 - 15:59 2nd Floor 5 Settled Dust

Activity 9 1 Paint Chip/1 Plaster

Baltimore Sawing Wood Day 2-1 2B Rear Bedroom 1 Personal Exposure

Building 2 75 Feet with Circular Saw 11:06 - 11:35 2nd Floor 5 Settled Dust

Activity 10 (Smooth Blade) 2 Paint Chip

Baltimore Door Modification Day 2-1 2B Rear Dining Room 1 Personal Exposure

Building 2 12:59 - 13:42 1st Floor 5 Settled Dust

Activity 11 3 Paint Chip

Baltimore Abrasive Paint Removal Day 2-2 2A 2B Front Bedroom 3 Personal Exposure

Building 2 08:14 - 10:24 3rd Floor 8 Settled Dust

Activity 12 3 Paint Chip

Baltimore Demolition of Day 2-3 2B 2C Bathroom 2 Personal Exposure

Building 2 North and South Walls 07:43 - 09:21 2nd Floor 8 Settled Dust 

Activity 13 3 Paint Chip/1 Plaster

Baltimore Demolition of Day 2-2 2A 2B Bathroom 2 Personal Exposure

Building 2 North and South Walls 13:15 - 14:02 3rd Floor 8 Settled Dust

Activity 14 2 Paint Chip/2 Plaster

Baltimore Demolition of East Wall Day 2-2 2A 2B Kitchen 2 Personal Exposure

Building 2 10:30 - 11:37 8 Settled Dust

Activity 15 2 Paint Chip/1 Plaster

Denver Building Component Day 3-1 3A 3B Front and Center 2 Personal Exposure

Building 3 Removal 09:11 - 11:52 Bedrooms 5 Settled Dust

Activity 1 12:59 - 13:58

Denver HVAC Sampling Day 3-1 MRI Attic 5 Interior Duct Wipes

Building 3 09:41 - 10:00

Activity 2

Denver Demolition of West Wall Day 3-1 3A 3B Kitchen 2 Personal Exposure

Building 3 14:16 - 15:47 6 Settled Dust

Activity 3 1 Paint Chip/1 Plaster
Table 8C-1 (Continued)

City/

Building No./ Room Samples

Activity No. Activity Day/Time Worker Description Collected

8-51

Denver Demolition of Day 3-2 3A 3B Bathroom 2 Personal Exposure

Building 3 East and West Walls 10:20 - 11:59 6 Settled Dust

Activity 4 2 Paint Chip/2 Plaster

2 Pre-Activity Dust

Denver Abrasive Paint Removal Day 3-2 3A 3B South Dining Room 2 Personal Exposure

Building 3 13:07 - 14:45 12 Settled Dust

Activity 5 4 Paint Chip

2 Pre-Activity Dust

Denver Drilling Wood Day 3-3 3B Unit(1) 1 Personal Exposure

Building 4 925 Holes with 1⁄4" Bit 09:14 - 09:37 5 Settled Dust

Activity 6 1 Paint Chip

Denver Drilling Wood Day 3-3 3B Unit(2) 1 Personal Exposure

Building 4 117 Holes with 1" Bit 09:44 - 09:53 5 Settled Dust

Activity 7 1 Paint Chip 

Denver Sawing Wood Day 3-3 3A Unit(4) 1 Personal Exposure

Building 4 75 Feet with Circular Saw 10:52 - 11:56 5 Settled Dust

Activity 9 (Smooth Blade) 2 Paint Chip

Denver Door Modification Day 3-3 3D Unit(1) 1 Personal Exposure

Building 4 13:20 - 14:32 5 Settled Dust

Activity 10 3 Paint Chip

Denver Door Modification Day 3-3 3A Unit(2) 1 Personal Exposure

Building 4 13:11 - 14:30 5 Settled Dust

Activity 11 3 Paint Chip

Denver HVAC Sampling Day 3-2 MRI Basement 5 Interior Duct Wipes

Building 5 10:55 - 11:16

Activity 12

Denver HVAC Sampling Day 3-4 MRI Basement 4 Interior Duct Wipes

Building 6 10:55 - 11:16

Activity 13

Denver Drilling Plaster Day 3-3 3B Center Bedroom 1 Personal Exposure

Building 6 925 Holes with 1⁄4" Bit 14:50 - 15:06 5 Settled Dust

Activity 14 1 Paint Chip/1 Plaster

Denver Demolition of Day 3-4 3A 3B 3C Dining Room 3 Personal Exposure

Building 6 East and West Walls 8:58 - 9:46 6 Settled Dust

Activity 15 2 Paint Chip/2 Plaster

Unlike the carpet removal and window replacement phases, ambient air samples were not

collected in the CED phase because (1) multiple simulated activities being conducted in a single

building did not allow for suitable adjacent non-activity areas, and (2) ambient air samples in

previous phases had low lead levels. 

Personal exposure sampling was conducted on each participating R&R worker to measure

lead concentrations in air within the workers' breathing zones while they were performing the

activities. Personal exposure monitoring started immediately prior to the beginning of the activity,

and stopped as soon as the activity was completed. 
8-52

Dust samples from SSDCs were collected approximately one hour after the completion of

each activity. Times could not be exactly one hour after completion of the activity because the

number of samples per activity was too great to allow simultaneous collection.

At selected locations within the Baltimore units, dustfall samples were taken from SSDC

surfaces via wipe techniques, in support of an EFSS study objective to compare results between

vacuum and wipe collection techniques. These wipe samples were collected adjacent to vacuum

sample areas. Comparisons of wipe and vacuum sample results were found in Section 7.3 of

Chapter 7.

Before CED field work started, a work plan was developed that assigned locations to each

CED activity to be conducted at a given site. An approximate spot was chosen where the activity

was to be performed (designated the activity area). Locations for dustfall samples were also

determined.

Table 8C-1 presents the proposed types and numbers of environmental field samples

collected during the CED field study. The major difference in sampling plans for the different

CED activities was in the layout of the settled dust sampling locations. For most of the CED

activities (drilling, sawing, door modification, and HVAC removal) the layout was fairly

consistent. One sample site was located adjacent to the surface being disrupted, and 4 others

located in a symmetric pattern at approximately 4-6 feet away from the surface being disturbed. 

The layout for settled dust samples planned for the paint removal activity was similar, but

included more sample locations. The sampling design for the demolition activities did not include

any settled dust sample located adjacent to the surface being demolished due to the amount of

debris distributed adjacent to the surface.

In addition to the environmental field samples associated with CED activities, several field

quality control (QC) samples were included in the sampling design. Field blank samples were

taken for three types of samples: personal exposure, dust wipe, and dust vacuum. Field blanks

were collected at the beginning of each day for the type of sample that was scheduled to be

collected. Personal exposure and settled dust field blank samples were to be collected on each

day of work; wipe blank samples were to be collected only on the days when the HVAC activity

was to be performed.

More details on the sampling design, including the protocols used to collect the samples,

are found in the Quality Assurance Project Plan.

8C-2.0 STUDY RESULTS 

This chapter presents the results of the statistical analysis of environmental sample data

from the CED phase of the EFSS. 
8-53

8C-2.1 STRUCTURE OF CED DATA

The purpose of the statistical analysis is to evaluate the lead disturbance and lead exposure

that results from performing some prescribed R&R activity on a lead-contaminated component. 

The models that were selected for presentation allow for comparison of different R&R activities

on the basis of lead exposure for workers and lead disturbance and potential exposure to

occupants.

All of the samples and their associated measurements in the CED phase can be identified

by activity, dwelling unit, subunit (i.e., room or portion of a room) within dwelling unit, and

replicate. As a result, an experimental unit (EU ) is defined as the occurrence of activity (i) ijk

within subunit (k) of dwelling unit (j). Each environmental field sample collected during the CED

phase can be linked to one or more experimental units.

The following paragraphs describe the variables or responses included in the statistical

analysis.

Activity. As discussed in Section 8C-1.2.1, the following eight different R&R activities

were investigated during the CED phase:

1. Drilling into wood or plaster surfaces using a small or large drill bit

2. Sawing into wood or plaster surfaces using a coarse or smooth blade

3. Abrasive Sanding and Scraping of a painted wood surface

4. Door Modification on wood doors

5. Building Component Removal of wood baseboards, doorjambs, etc.

6. Demolition of plaster and wood walls

7. HVAC removal in houses with interior lead-based paint

8. Cleanup after R&R activities.

The first six activities were performed on components that were covered with lead-based paint. 

The components were identified and confirmed as containing lead-based paint prior to the study

using a portable XRF analyzer. 

Personal Exposure Monitor. During the eight activities, workers who performed the

activity were monitored for exposure to airborne lead using personal air pumps. Total

activity monitoring included the entire length of the activity and tool cleanup. For each

worker, the amount of lead collected within the sample cassette(s), the duration of the

monitoring, and the air pump flow rate were used to calculate the worker's task-length

average (TLA) lead exposure in μg/m . As discussed in Chapter 6, a natural log- 3

transformation was applied to each TLA for use as a response variable in the statistical

models.

PEM = Personal exposure monitor result (μg/m ) measured on the l worker during ijkl

3 th

the occurrence of activity (i) within subunit (k) of dwelling unit (j).
8-54

Settled Dust. Prior to each CED activity, a number of SSDCs were placed on the floor at

predetermined distances from the center of the activity. These plates were used to collect

the fallout of dust and debris generated by each occurrence of an R&R activity. 

Approximately one hour after the completion of an activity, the dust located within each

plate was collected and then analyzed for lead. Since each SSDC had a surface area of

one square foot, the results of the settled dust field samples are reported as a dust-lead

loading in units of μg/ft . As discussed in Chapter 6, a natural log-transformation was 2

applied to each settled dust loading for use as a response variable in the statistical models. 

In addition to the dust-lead loading, each SSDC has an associated distance, which

measures how far away each dust collector was placed from the surface being disturbed

during the activity.

Dust = Dust lead loading result (μg/ft ) measured on the l SSDC from the ijkl

2 th

occurrence of activity (i) within subunit (k) of dwelling unit (j).

Distance = Distance from the activity of the l SSDC from the occurrence of activity ijkl

th

(i) within subunit (k) of dwelling unit (j).

During the demolition, abrasive sanding, and component removal activities, some SSDC's

were placed in adjacent pairs in an effort to assess side-by-side variability within settled

dust results. For the demolition activity in particular, some of the side-by-side paired

samples were sampled using both dust vacuum and dust wipe collection methodologies. 

With the exception of the demolition side-by-side vacuum/wipe samples, all other settled

dust samples from the CED phase were collected using the vacuum methodology.

Pre-Activity Lead Levels. To understand factors that may affect the potential lead

exposure that results from performing an R&R activity on a lead-contaminated

component, it is important to also characterize the amount of lead that was on the surface

of each disturbed surface prior to the activity. Thus, for each R&R activity, at least one

field sample was collected to characterize the pre-activity lead level. For activities which

disturbed lead-painted surfaces, the pre-activity lead level was measured using paint chip

samples and reported in units of mg/cm . For the HVAC removal activity, a number of 2

dust wipe samples were taken from the interior of the duct-work to characterize the preactivity lead levels. The pre-activity dust wipe samples for the HVAC removal activity are

reported in units of μg/ft .2

Paint = Lead in paint result (mg/cm ) measured on the l surface during the ijkl 

2 th

occurrence of activity (i) within subunit (k) of dwelling unit (j).

HVAC Wipe = Lead in wipe sample (μg/ft ) obtained from the interior of the l duct jkl 

2 th

surface during the occurrence of the HVAC removal activity within

subunit (k) of dwelling unit (j).

For R&R activities which disturbed lead-painted plaster, additional pre-activity samples of

the plaster were collected and archived for possible future analysis.
8-55

 Table 8C-2 summarizes the number of field samples collected and available for statistical

analysis for the CED phase:

 Table 8C-2. Number of Field Samples Collected and Available for Analysis

in the CED Phase

Activity Exposure Exposure Dust Dust Wipe Activity Activity

Type Substrate Units Monitor Vacuum Paint Dust

Personal Settled Settled Pre Pre

Drilling Plaster 6 6 24 0 5 0

Wood 7 7 35 0 7 0

Sawing Plaster 2 2 10 0 2 0

Wood 6 6 30 0 12 0

Sanding Wood 3 9 28 0 10 2

Door

Modification Wood 6 6 30 0 17 0

Removal Wood 1 2 5 0 0 0

HVAC Duct 2 4 15 0 0 7

Demolition Plaster 9 20 51 12 16 2

Cleanup Plaster 4 4 0 0 0 0

Wood 2 2 0 0 0 0

8C-2.2 CHARACTERIZING LEAD DISTURBANCE AND POTENTIAL LEAD EXPOSURES

The lead disturbance and exposure data observed in the CED phase are characterized

below, according to the sample or exposure type considered.

For each worker, the amount of lead collected within the sample cassette(s), the duration

of the monitoring, and the air pump flow rate were used to calculate the worker's 

task-length average (TLA) lead exposure in μg/m . A discussion of the relationship between a 3

TLA and an 8-hour time-weighted average (TWA), on which the OSHA PEL is based, is given in

Section 9.1.2 of Chapter 9.

8C-2.2.1 Personal Worker Exposures

In the CED phase, each worker was monitored for airborne lead exposure for the duration

of each R&R task. Duration was defined as the time it took a worker to complete the task and

clean his tools. The duration of CED phase activities ranged from 9 to 185 minutes. Table 8C-3

gives a summary of task duration for each CED activity under investigation.

Figure 8C-1 is a plot of the task-length average personal exposure lead concentrations

(μg/m ), or average exposures over the duration of activity, for each CED activity type. In this 3

plot, a horizontal line is drawn at 50 μg/m , which represents the OSHA PEL for lead exposure 3
8-56

during an assumed eight hours of exposure per day. This plot demonstrates that all CED

activities, with the exception of the drilling activities, HVAC removal, and cleanup of plaster,

 resulted in most worker TLAs above the OSHA PEL. All worker TLAs were at or above the

OSHA PEL for cleanup of wood, door modification, wood component removal, abrasive sanding,

and sawing activities. Nineteen of twenty TLAs were above the OSHA PEL for demolition. In

contrast, for drilling activities, all worker TLAs except one were at or below the OSHA PEL. 

Further summary of the data in Figure 8C-1 can be found in Table CED-1 of Appendix A.

Random-effects model (CED-1) in Appendix C was fit separately to the TLA personal

exposure concentrations for each combination of target activity and substrate, in order to

characterize four components of variability in the log-transformed TLA concentrations. These

variance components are:

! unit to unit variability, or variability resulting from sampling from different study units

! variability resulting from performing the activity at different subunits within a study

unit

! variability among different workers

! replication variability, including measurement error.

 Table 8C-3. Task Length for Each Combination of Target Activity and Substrate in the

CED Phase

Activity Duration Duration Duration

Type Substrate n (minutes) (minutes) (minutes)

Average Minimum Maximum

Drilling Plaster 6 40 15 85

Wood 7 36 9 83

Sawing Plaster 2 19 16 22

Wood 6 41 14 77

Sanding (Hand) 6 63 58 75

Sanding (Power) 3 39 22 64 Wood

Door Wood 6 68 43 91

Removal Wood 2 160 135 185

HVAC Duct 4 48 21 74

Demolition Plaster 20 61 25 99

Cleanup Plaster 4 49 14 129

Wood 2 15 12 18

(1)

 The second-highest duration was 27 minutes. (1)
8-57

Figure 8C-1. Scatterplot of Personal Exposure Loadings by Task Type and Unit ID

Table 8C-4 displays model estimates of the geometric means and variance components

(standard deviations) of worker personal exposure to airborne lead for each CED activity,

resulting from fitting model (CED-1). The actual number of variance components that can be

estimated from the CED data is different for each target activity and is based on the number of

observations per target activity and the CED experimental design. For example, if only two

observations of worker exposure to airborne lead are available, we can only estimate the

geometric mean and residual standard deviation for the given activity. 

Table 8C-5 displays estimates of the 50th, 75th, and 95th percentiles of the distribution of

personal exposure concentrations for each target activity, with approximate 95% confidence

intervals. The approaches for calculating the percentiles and confidence intervals are found in

Appendix C. Figure 8C-2 presents a graphical display of the estimated 75 percentile (and th

associated confidence interval). The vertical line in this figure represents the OSHA PEL of 50

μg/m . Results such as these percentiles, with their estimates of variability, can be used to 3

compare potential lead exposures for R&R workers across activities.
8-58

Table 8C-4. Model Estimates of the Geometric Mean and Standard Deviation of Variance

Components of Worker Personal Exposure to Airborne Lead (Task Length

Average) for Each CED Activity Based on a Variance Components Model of

log(PEM ) ijkl

Activity Substrate Samples from Model (F ) (F ) (F ) (F )

Number Geometric Mean Worker-to- Task-to-Task

of Estimated Residual Worker Unit-to-Unit Within Unit

Error

(1)

Worker Unit Task(Unit)

Drilling Plaster 6 6.76 0.313 0.434

Wood 7 15.1 1.29 0.000

Sawing Plaster 2 110 1.11

Wood 6 546 0.380 0.000

Sanding (Hand Wood 6 254 0.589 0.000 0.860

Sanding (Power) 3 571

Door Modification Wood 6 590 0.847 0.896

Component Wood 2 344 0.0451

Removal

HVAC Duct 4 49.6 0.101 0.147

Demolition Plaster 20 108 0.475 0.463 0.451

Cleanup Plaster 4 24.5 0.550

Wood 2 102 0.205

 Standard deviation of the log transformed data (expressed in log measurement units). (1)

Table 8C-5. Estimates of the 50th, 75th, and 95th Percentiles for Worker Personal

Exposures, Along With 95% Confidence Intervals, by Activity in the CED

Phase

Activity Substrate Samples Estimate 95% C.I. Estimate 95% C.I. Estimate 95% C.I.

Number

of

50th Percentile 75th Percentile 95th Percentile

(μg/m ) (μg/m ) (μg/m ) 3 33

Drilling Plaster 6 6.76 (3.00, 15.3) 9.70 (5.71, 40.3) 16.3 (9.47, 226)

Wood 7 15.1 (4.57, 50.2) 36.3 (13.8, 214) 127 (42.9, 2490)

Sawing Plaster 2 110 (0.01, 2.32x10 ) 232 (11.9, 2.40x10 ) 681 (149, 2.15x10 )

Wood 6 546 (366, 813) 705 (518, 1300) 1020 (726, 2890)

6 13 27

Sanding (Hand) 6 254 (23.7, 2720) 513 (150, 63800) 1410 (447, 2.03x10 )

Sanding (Power) 3 571 (42.9, 7600) 1150 (286, 170000) 3170 (940, 5.03x10 ) Wood

7

7

Door

Modification Wood 6 590 (93.5, 3730) 1360 (410, 35200) 4480 (1300, 1.89x10 )6

Component

Removal Wood 2 344 (229, 516) 354 (314, 995) 370 (348, 3680)

HVAC Duct 4 49.6 (11.4, 216) 56.0 (37.7, 3070) 66.6 (53.0, 588000)

Demolition Plaster 20 108 (26.6, 435) 185 (95.7, 5500) 403 (186, 542000)

Cleanup Plaster 4 24.5 (10.2, 58.7) 35.5 (19.9, 159) 60.5 (34.0, 925)

Wood 2 102 (16.2, 646) 118 (67.9, 12800) 143 (108, 4.89x10 )6
8-59

Figure 8C-2. 75th Percentile and Associated 95% Confidence Interval for Personal

Exposure to Airborne Lead (μg/m ) from Each Combination of CED Activity 3

and Substrate 

The results presented in Table 8C-4 demonstrate that for R&R activities that are

performed on both wood and plaster surfaces in the CED phase, the estimated median worker

exposure (as given by the geometric mean) is much higher for wood surfaces. This trend is

consistent for the drilling, sawing, and cleaning activities, and is possibly attributable to a higher

concentration of lead in paint on wood surfaces. Table 8C-6 provides parameter estimates (in the

log domain) for the effect of a wood substrate on personal exposure levels when performing

the same activity on wood versus plaster surfaces. These results are based on fitting Model

(CED-2) in Appendix C. (Note that the estimates are similar to, but not in complete

correspondence with those obtained from the geometric means in Table 8C-4. This difference is

caused by fitting different models to the data.)
 A small number of settled dust samples were collected from the SSDC's using wipe sampling. These wipe sampling *

results were not utilized in the determination of potential occupant exposures. They were used only for the vacuum/wipe

methodology comparisons presented in Chapter 7.

8-60

Table 8C-6. Estimates of the Increase in Personal Air Exposures that are Attributable to a

Substrate Effect (Wood versus Plaster) in the CED Phase

Activity Wood Over Plaster Estimate Freedom from Zero Rather Than Plaster

Parameter

Estimates of Multiplicative Increase

Increase in P-Value in PEM Results When

log(PEM ) Standard Degrees for Test of the Activity is ijkl

Associated with Error of of Significance Performed on Wood

Drilling 0.798 0.529 8 0.17 2.2

Sawing 1.60 0.465 4 0.03 5

Cleanup 1.70 0.248 2 0.02 5.5

The interpretation of the estimated increase in log(PEM ) with wood versus plaster ijkl

substrates is multiplicative. The final column in Table 8C-6 shows that drilling into wood results

in a 2.2 fold increase in the personal exposure level over drilling into plaster, while a 5 fold

increase in wood over plaster is seen with sawing, and a 5.5 fold increase in wood over plaster is

seen during cleanup. The increases associated with the latter two activities are significant at the

0.05 level.

8C-2.2.2 Lead Disturbance and Potential Occupant Lead Exposure

SSDC Approach to Settled Dust Sampling

Immediately prior to the occurrence of each CED activity, a number of SSDCs were

placed at various distances away from the surface about to be disrupted. These SSDC's measured

one square foot in area, and were designed to collect the fallout of dust and debris generated

during an R&R activity. 

Approximately one hour following the conclusion of each CED activity, the settled dust

and debris were collected from each SSDC through vacuum sampling, and then chemically

analyzed for lead. As discussed in Section 8C-2.1, each settled dust sample has an associated *

measure of the lead-loading in units of micrograms of lead per square foot (μg/ft ) and a measure 2

of distance from the activity. Distance for each settled dust sample was measured as how far

away (in feet) its SSDC was from the nearest surface that was disturbed during the activity.

The goal of the statistical analysis of settled dustfall lead-loadings is to characterize the

potential lead exposure to occupants from dust and debris generated by each CED activity. The

settled dustfall loadings from each CED activity represent the amount of lead generated by the

performance of the activity at varying distances away from the surface being disturbed.
8-61

For most of the CED activities (drilling, sawing, door modification, and HVAC removal)

the placement of SSDC's was fairly consistent, with one SSDC adjacent to the surface being

disrupted, and four other SSDC's placed in a symmetric pattern at approximately 4-6 feet away

from the nearest surface. The adjacent SSDC was expected to capture the fallout of both large

debris and dust generated by each activity, while the other four plates were expected to capture

mostly dust and smaller airborne particles. The sampling design for the abrasive sanding activity

was similar, but included more SSDCs. The sampling design for demolition activities did not

include any SSDC's located adjacent to the surfaces being demolished, for two reasons: (1) they

would have been an obstacle to the workers, and (2) the expected amount of large debris in a

sample collected by an adjacent SSDC would have been difficult to chemically analyze. 

Relating Lead Loadings in Settled Dust to Distance from Activity

Exploratory analysis of the settled dustfall results demonstrated an approximate linear

relationship between log-transformed lead loadings and distance from the activity. Model (CED3) in Appendix C was fitted separately to log-lead loading data for each experimental unit (i.e.,

activity/unit/subunit combination) to estimate this linear relationship to distance. This model took

the form

log(dust) = $ + $ Distance + error. 0 1

Averages of the parameter estimates for each activity/substrate combination are given in Table

C-8 of Appendix C.

For most experimental units, the slope estimate within Model (CED-3) was negative,

which implied two things:

1. The highest settled dust lead-loading results are associated with SSDC's that are

positioned adjacent to the surface being disrupted. 

2. The amount of lead found on each SSDC diminishes exponentially with respect to

distance, at a rate determined by the slope parameter.

After Model (CED-3) estimated the relationship between lead loading and distance from

activity for each experimental unit, it was then necessary to summarize these results across all

experimental units. Two different models, a two-stage model and a population model, were

examined to summarize the relationship across experimental units. The two models produced

similar results. (Details concerning the choice of model are provided in of Appendix C). 

Therefore we chose to focus our conclusions on the population model, given by Model (CED-5)

in Appendix C. This model was fit separately for each combination of activity and substrate, to

model lead-loading as a function of distance.
8-62

Estimating Lead Disturbance Within a 6' x 1' Gradient

As stated earlier, the goal of the statistical analysis of settled dust lead-loadings is to

determine the potential occupant exposure to lead that results from each CED activity. The result

of fitting the population model (CED-5) to lead loading data allows us to estimate an overall

average curve which explains the average amount of lead in settled dust that is expected to occur

at varying distances for each activity, and the components of variation about that curve. For a

given activity (i), the population average response curve has the following form:

Lead in dust (μg/ft ) = exp($ )@ exp($ @ Distance) 2

0i 1i

By integrating the area underneath the estimated curve for Activity (i) from 0 to 1 foot,

we obtain the expected lead-loading of an SSDC located adjacent to the surface of activity (i)

(denoted by "[0-1] foot SSDC"). Similarly, by integrating the area underneath the estimated

curve for activity (i) from 5 to 6 feet, we obtain the expected lead-loading of an SSDC located 5-

6 feet from the surface of activity (i) (denoted by "[5-6] foot SSDC"). The measure used to

characterize lead disturbance and potential exposure to occupants for each CED activity is the

amount of lead in a 6-foot by 1-foot gradient region, which is obtained by integrating the area

underneath the estimated curve from 0 to 6 feet.

Table 8C-7 displays the parameter estimates (and associated standard errors) for the

population average lead loading curve, and the calculated average lead loadings ([0-1] foot

SSDC, [5-6] foot SSDC, and 6-foot by 1-foot gradient; and associated standard errors) for each

CED activity. The average lead loadings are relative to the total amount of activity performed in

the CED phase. The standard errors of the average lead loadings for each activity were calculated

by using the Delta Method (Bishop, Fienberg, and Holland, 1975), which is based on asymptotic

normal theory. However, the sample sizes (number of experimental units) within each CED

activity are small, making these estimates only approximate. Details of the statistical

methodology are presented in Section C.5 of Appendix C.

The estimated 6-foot by 1-foot gradient lead loadings for each CED activity are displayed

in Figure 8C-3.

The estimated [0-1] foot SSDC and [5-6] foot SSDC loadings have different interpretations

with respect to each CED activity. The [0-1] foot SSDC loading is representative of the amount

of lead that is likely to fall directly underneath the surface being disrupted, while the [5-6] foot

SSDC is more representative of the amount of lead that becomes airborne in dust and small

particles. By comparing the estimates of the [0-1] foot SSDC to estimates for the entire gradient,

we can gain some perspective on the amount of lead disturbed that is likely to stay localized,

versus the amount of lead that is likely to become airborne for each activity. For example,

approximately 80% of the lead in the gradient remains localized in the [0-1] foot area for the two

drilling activities, while only 33% stayed localized in the abrasive sanding activity. Thus, a higher

percentage of the lead disturbed becomes airborne when performing abrasive sanding in

comparison to drilling. This type of information may be useful in the design of final cleanup

procedures for R&R workers to help protect occupants from lead exposure.
8-63

Figure 8C-3. Estimated Lead Fallout Gradient in Settled Dust from 0 to 6 Feet Away from

the Edge of the Activity Space

Table 8C-7. Estimates of Lead Disturbance for Each CED Activity Based on the

"Population" Random Effects Modeling of Settled Dust Lead-Loading

Results(1)

Target of $ $ Mean (μg/ft ) Mean (μg/ft ) (μg/6 ft )

Activity (i) Substrate EU 's (se($ )) (se($ )) (Standard Error) (Standard Error) (Standard Error)

Number [0-1] Foot SSDC SSDC Mean

ijk

0i

0i

1i

1i

2

[5-6] Foot 6'×1' Gradient

2 2

Drilling Plaster 4 10.5 -1.67 17400 4.08 21400

(1.10) (0.344) (17500) (5.40) (20600)

Drilling Wood 7 12.9 -1.47 205000 130 266000

(0.602) (0.121) (116000) (51.9) (143000)

Sawing Plaster 2 11.2 -0.929 50000 480 82300

(1.20) (0.247) (55700) (330) (81400)

Sawing Wood 6 12.6 -0.668 223000 7900 449000

(0.474) (0.117) (97500) (3450) (167000)

Abrasive 11.5 -0.341 85500 15500 257000

Sanding (0.737) (0.047) (62800) (11500) (188000) Wood 3

Door 11.1 -0.417 54000 6700 145000

Modification (0.707) (0.094) (36300) (2630) (82700) Wood 6

HVAC 8.08 -0.375 2690 414 7710

Removal (2.21) (0.226) (5690) (516) (14100) Duct 2

Demolition Plaster 9 8.77 -0.263 5690 1530 19500

(0.839) (0.071) (4630) (948) (14300)

 Lead in Dust (μg/ft ) = exp ($ ), exp ($ Distance). (1) 2

0i 1i
8-64

The above results are based on the total amount of activity performed in the CED phase. 

To facilitate comparability in results across phases, this analysis was repeated after adjusting the

amount of each activity to a "real-world" standard. The results of the standardized analysis are

found in Section 8C-2.2.3.

Exposure Potential for Wood Versus

Plaster Components in Drilling and Sawing

The estimated results of the lead disturbed in the 6-foot by 1-foot gradient region suggest

that CED activities which disturb lead-painted wood surfaces have higher loadings than activities

which disturb lead-painted plaster surfaces. This trend for the gradient lead loading is consistent

with the results from the personal exposure monitoring results. Table 8C-8 presents the results of

fitting statistical Model (CED-6) in Appendix C to estimate differences in slopes and intercepts

that result in considering wood substrate over plaster substrate. Results are presented for drilling

and sawing activities. 

Although the differences in parameter estimates between wood and plaster surfaces are

not statistically significant at the 0.05 level, they suggest the following:

! the positive increase in the intercept term suggests that the amount of lead found

directly underneath a wood surface is greater than that for a plaster surface.

! the slight positive increase in the slope term, coupled with the negative slope estimates

for both wood and plaster, suggests that the exponential decline in lead amounts with

respect to distance is slower with wood than with plaster surfaces.

Table 8C-8. Estimates of the Log Increase in Intercept and Slope for the Relationship

Between log (Dust ) and Distance that are Attributable to a Substrate ijkl ijkl

Effect (Wood versus Plaster)

Activity Parameter Versus Plaster Error Freedom P-Value (1)

Parameter Estimates of

the Increase in Parameter Degrees

Estimates for Wood Standard of 

Drilling Intercept 2.54 1.18 9 0.06

Slope 0.133 0.321 9 0.69

Sawing Intercept 1.35 1.34 6 0.35

Slope 0.271 0.254 6 0.33

"Intercept" represents the baseline increase in log(Dust) associated with disturbing wood (1)

substrate versus plaster substrate. "Slope" represents the amount this baseline increase is

inflated by moving 1-foot closer to the activity. 
8-65

Another method of interpreting the substrate effect within these two CED activities is to

examine the differences between the 6-foot by 1-foot gradient lead loading estimates for wood

versus plaster. Table 8C-9 presents estimates of the log-transformed gradient region loadings

(and associated standard errors) for each substrate, along with the corresponding two-sample

t-test statistic. The lead gradient loadings are transformed to the natural log scale in an effort to

improve the assumption of normality that is required by the two-sample t-test. 

Table 8C-9. Estimated Differences in the 6' × 1' Lead Loading Gradient Attributable to a

Substrate Effect (Wood verses Plaster)

Wood Plaster

CED log(6' × 1' Gradient) log(6' × 1' Gradient) Degrees of

Activity (Std. Error.) (Std. Error.) t-Statistic Freedom P-value (1)

Drilling 2.29 5.0 0.07 12.5 9.97

(0.54) (0.96)

Sawing 1.61 1.3 0.31 13.0 11.3

(0.37) (0.99)

 Determined by Satterthwaite's approximation. (1)

While the observed difference between wood and plaster results were not statistically

significant at the 0.05 level, the power of the test is limited by the small sample sizes.

The estimated positive differences in measures of potential occupant exposure (intercept,

slope, and lead loading gradient) between wood and plaster surfaces for these two activities might

be attributable to the fact that the concentration of lead in paint on wood surfaces is generally

higher than the concentration of lead in paint on plaster surfaces. This issue will be further

investigated in Section 8C-2.3.2.

8C-2.2.3 Adjusting Estimates of Lead Disturbance for the Amount of R&R Activity

The generic activities of sawing and drilling, as designed in the CED phase, were not

intended to reflect sawing or drilling activities to the extent that they are performed in the R&R

industry. Rather, they were intended to provide sufficient activity to allow for estimating a task

length average worker exposure, as well as estimating the lead disturbed by the specified amount

of activity. However, the measure of the amount of lead disturbed by a CED activity is directly

related to the amount of activity performed. As a result, it is desirable to express settled dustfall

relative to a "standard unit of activity". 

As they exist in this study, the simulated target activities of demolition and HVAC duct

removal represent a "real-world" standard unit of activity. For demolition, the standard unit of

activity is the demolition of interior wall(s) in a single room of a building. For HVAC work, the

standard is the removal of all duct work in a single room of a building. As a result, the unit of

activity will not be adjusted for these two task activities. In contrast, because the generic

activities of drilling and sawing, as conducted in this study, were not judged to be a reasonable
8-66

representation of any "real-world" R&R activity, the amount of lead disturbed will be adjusted to

a "standard unit" of activity for these activities. For drilling, this standard unit represents 10 small

holes or 1 large hole. For sawing, this standard unit represents 1 linear foot cut. Subsequent

estimates of the average amount of lead disturbed by that activity can then be interpreted as the

amount of lead disturbed per unit activity.

Two activities could not be considered when defining standard units of activity. The

positive control activity, abrasive sanding, was conducted primarily to obtain personal worker

exposure measurements for comparison to other activities and cannot be accurately quantified

according to the "amount of activity." Likewise, the door modification task was originally

designed as a repeated task for a specified amount of time out of concern over obtaining

detectable levels of airborne lead exposure. Therefore, neither of these two tasks can be

adequately defined per unit of activity and are not included in the adjusted results. 

Table 8C-10 presents the amount of lead in the [0-1] foot SSDC, [5-6] foot SSDC, and

6-foot by 1-foot gradient region for the "standard unit of activity" for each CED activity in which

a standard unit of activity could be determined. Figure 8C-4 demonstrates the amount of lead in

the gradient region per standard unit of activity. Note that by comparing Table 8C-7 with Table

8C-10, and Figure 8C-3 with Figure 8C-4, one can observe how adjusting for the "standard unit

of activity" qualitatively affects the comparison of lead disturbance across different activities. 

Lead disturbance resulting from demolition and HVAC removal is more substantial relative to

other activities when these other activities are adjusted for the amount of activity performed. 

Table 8C-10. Estimates of the Potential Occupant Lead Exposure for Each CED Activity

Relative to a Standard Unit of Activity(1)

CED Standard Unit Intercept Slope (μg/ft ) Mean (μg/ft ) Mean (μg/6 ft ) Mean 

Activity (i) Substrate of Activity $ $ (Std Error) (Std Error) (Std Error)

Estimated Estimated [0-1] Ft SSDC [5-6] Ft SSDC 6' × 1' Gradient

0i 1i

22 2

Drilling Plaster 10 1⁄4" Holes 5.85 -1.68 168 0.04 207

or a 1" Hole (1.05) (0.343) (163) (0.05) (191)

Drilling Wood 10 1⁄4" Holes 8.25 -1.47 2000 1.27 2590

or a 1" Hole (0.605) (0.120) (1140) (0.49) (1400)

Sawing Plaster 1 Linear Foot 7.53 -0.947 1200 10.6 1970

(1.59) (0.305) (1780) (6.63) (2560)

Sawing Wood 1 Linear Foot 8.31 -0.668 2970 105 5990

(0.474) (0.117) (1300) (46.0) (2230)

Demolition Plaster 1 Room 8.78 -0.263 5690 1530 19500

(0.839) (0.071) (4640) (948) (14300)

HVAC Duct 1 Room of 8.08 -0.375 2690 414 7710

Removal System Duct Work (2.21) (0.226) (5700) (516) (14100)

 Lead in Dust = exp($ ) exp($ Distance) (1)

0i 1i
8-67

Figure 8C-4. Estimated Lead Fallout Gradient in Settled Dust, From 0 to 6 feet Away From

the Edge of the Activity Space - Adjusted to the "Standard Unit of Activity"

8C-2.3 FACTORS OR MEASUREMENTS RELATED TO LEAD DISTURBANCE

8C-2.3.1 Pre-activity Measures of Lead Contamination

This section provides descriptive characterizations on the three types of pre-activity sample

media considered in the CED phase. These characterizations include distributional qualities,

descriptive summaries and plots for paint chip samples, dust wipe samples from HVAC systems,

and pre-activity dust vacuum samples. Tables of descriptive summaries in this section present

number of observations, arithmetic and geometric means, log standard deviation and minimum

and maximum values.

8C-2.3.1.1 Results of Paint Chip Samples

A total of 62 paint chip samples were collected during the CED phase prior to the

occurrences of those activities which disturbed lead-painted surfaces. The lead loading (mg/cm )2

for each paint chip sample was calculated by dividing the measurement of lead in the sample (mg

lead) by the area of the sample in square centimeters. Table 8C-11 provides descriptive statistics

on the distribution of paint chip lead loadings from samples collected from within each CED

activity. The number of samples listed in Table 8C-11 total 69 (instead of 62) because samples

were collected from building components disturbed by more than one CED activity. Table 8C-12

provides descriptive statistics for the distribution of paint chip lead loadings based on substrate

(wood vs. plaster). 
8-68

Table 8C-11. Descriptive Summaries of Paint Chip Lead Loadings (mg/cm ) from Samples 2

Collected Within Each Activity in the CED Phase

Task Type Number Mean Mean Dev. Value Value

Arithmetic Geometric Log Std. Minimum Maximum

Demolition 16 5.24 0.840 3.22 0.0002 17.7

Door/Wood 17 8.78 4.90 1.50 0.0587 28.7

Drill/Plaster 5 3.18 0.639 2.54 0.0130 12.7

Drill/Wood 7 7.38 5.51 1.08 0.519 13.4

Sand 10 10.4 5.03 1.61 0.285 39.9

Saw/Plaster 2 2.11 0.0401 6.58 0.0004 4.21

Saw/Wood 12 7.26 4.06 1.71 0.0266 19.5

Table 8C-12. Descriptive Summaries of Paint Chip Lead Loadings (mg/cm ) by Substrate 2

in the CED Phase 

Substrate Number Arithmetic Geometric Log Std. Minimum Maximum

Mean Mean Dev.(1) Value Value

Wood 44 8.65 4.87 1.48 0.0266 39.9

Plaster 18 4.78 0.397 3.63 0.0002 17.7

Exploratory plots are included in Figures 8C-5 and 8C-6. Figure 8C-5 is a plot of lead

loadings in paint chip samples, identified by the activity which disrupts the surface. This plot

demonstrates the variability for paint chip samples within each CED activity. Figure 8C-6 is a

scatterplot of paint chip lead-loadings separated by substrate (wood vs. plaster), with different

symbols representing different dwelling units. Although the geometric means for paint chip

loadings from wood and plaster surfaces were an order of magnitude apart, this plot indicates that

the difference in paint chip lead loadings between wood and plaster surfaces was primarily the

result of the difference in only one unit (Baltimore Unit 1) .

The differences in geometric mean loadings for paint chip samples collected from wood

versus those collected from plaster (Table 8C-12) may help to explain the higher personal

exposure and settled dust lead loadings observed for activities that disturb wood surfaces

compared to plaster-disturbing activities. This issue is examined further in Section 8C-2.3.2.
8-69

Figure 8C-5. Scatterplot of Paint Chip Loadings by Task/Unit in the CED Phase

Figure 8C-6. Scatterplot of Paint Chip Loadings by Substrate in the CED Phase
8-70

8C-2.3.1.2 Results of Dust Wipe Samples from HVAC Systems 

A total of 21 wipe samples were collected from HVAC systems in the CED phase. Seven

wipe samples were taken from the HVAC systems in the two Baltimore housing units prior to

removing portions of these systems. The remaining 14 HVAC wipe samples were collected from

the HVAC systems from three housing units in Denver, where no HVAC removal was performed. 

Table 8C-13 presents the descriptive summaries on lead loadings for HVAC samples across units

and within each unit. Geometric means suggest lead loadings in the Denver units (units 3 through

5 in Table 8C-13) were lower than the corresponding lead loadings in the Baltimore units.

Table 8C-13. Descriptive Statistics for HVAC Wipe Sample Lead Loadings Across and

Within Units in the CED Phase

Unit ID N (μg/ft ) (μg/ft ) Std. Dev. (μg/ft ) (μg/ft )

Arithmetic Mean Geometric Mean Log Minimum Value Maximum Value 2 2 22

All 21 5870 2900 1.28 205 30900

1 4 17900 14800 0.784 4880 30900 (1)

2 3 6940 6880 0.168 5800 8120 (1)

3 5 2060 2040 0.184 1610 2650

4 5 1060 709 1.04 205 2140

5 4 3850 2700 1.01 1000 8280

 Samples taken before HVAC removal activities (Baltimore dwelling units). (1)

The loading data summarized in Table 8C-13 are plotted in Figure 8C-7. This plot

illustrates the variability within and between housing units. It should be noted that the unit with

the lowest lead loadings contained an HVAC system attached to a furnace that was installed in

1985. These results provide an estimate of the amount of lead dust present in an HVAC system

that could be made available for human exposure if the system is disturbed.

8C-2.3.1.3 Results of Dust Vacuum Samples (Pre-Activity in Denver)

Only four pre-activity settled dust samples were collected from window sills and shelves

during the CED phase. These samples were taken from the same dwelling unit. Two samples

were taken before a demolition activity, and two samples were taken before an abrasive sanding

activity. Table 8C-14 presents the loadings and concentrations for these four samples.
8-71

Figure 8C-7. Lead Loadings Within Wipe Dust Samples Collected from Inside HVAC

Ductwork

 Table 8C-14. Pre-activity Settled Dust Results (Lead Loading and Sample Concentration)

from Window Sills and Shelves in the CED Phase

Activity Surface (μg/ft ) (μg/g)

Loading Concentration 2

Sanding

Window Sill 9730 31600

Window Sill 825 3240

Demolition

Window Sill 29100 19000

Lower Shelf 129 431

8C-2.3.2 The Relationship Between Airborne Lead, Lead in Settled Dust, and Paint Lead

Levels

In the previous sections, two hypotheses were made based on the outcome of statistical

analysis that investigated the relationship between airborne lead, lead in settled dust, and paint

lead levels:
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1. Within a given CED activity, the observed substrate (wood vs. plaster) differences in

personal exposure and settled dust results can be attributed to differences in substrate

paint loadings.

2. The estimated lead loading in the [5-6] foot SSDC is representative of airborne dust

and smaller particles, while the estimated lead loading in the [0-1] foot SSDC is more

representative of larger debris that fell directly from the disturbed surface.

In this section, the validity of these two interpretations is tested by considering how paint lead

loadings affect observed substrate differences, how [5-6] foot SSDC results are correlated with

personal exposure results, and how [0,1] foot SSDC results are correlated with paint lead

loadings. 

The Effect of Paint Loadings

If the first hypothesis is valid, then adding a fixed effect for paint lead loadings to the

statistical models that characterize personal exposure and settled dust lead loadings should

substantially reduce any remaining substrate effect on these data. Tables 8C-15 (personal

exposure concentrations) and 8C-16 (settled dust lead loadings) summarize the estimated

substrate effects before and after adjusting for paint lead loadings, and are obtained by fitting

Models (CED-7) and (CED-8) in Appendix C, respectively. 

Table 8C-15. Estimated Substrate Effect on Log-Transformed Personal Exposure

Concentrations (log(PEM)), Before and After Adjusting for Paint Lead

Loading, in the CED Phase

Activity Loadings? Parameter Estimate Error Freedom P-Value

Model Adjusted Degrees

for Paint Lead Standard of (1) (2)

Drilling

Unadjusted Wood vs. Plaster 0.798 0.529 8 0.17

Adjusted Wood vs. Plaster 0.374 0.602 7 0.55

Paint 0.109 0.0642 7 0.13

Sawing

Unadjusted Wood vs. Plaster 1.60 0.465 4 0.03

Adjusted Wood vs. Plaster 1.56 0.597 3 0.08

Paint 0.00888 0.0606 3 0.89

Indicates whether an effect for paint lead loading is included in the model. (1)

"Wood vs. Plaster" represents the increase in log(PEM) associated with disturbing wood substrate versus plaster (2)

substrate. "Paint" represents the increase in log(PEM) associated with a unit increase in paint lead loading.

The results in Table 8C-15 show that by including the effect of paint lead loading into the

model, the magnitude of the multiplicative substrate effect in the drilling activity has been reduced

from a 2.2 to a 1.45 fold increase when drilling into wood versus drilling into plaster (e = 2.2, 0.798

e = 1.45). However, the increases are not statistically significant at the 0.05 level given the 0.374

observed data and sample sizes. Essentially no reduction in the multiplicative substrate effect

occurs from adjusting the model for the sawing activity. 
8-73

The results presented in Table 8C-16 demonstrate that adjusting for the effect of paint

lead-loading causes a large reduction in the substrate effect on the intercept term. The substrate

effect for the slope of distance remains relatively stable between the two models. Moreover, the

paint lead loading effect is statistically significant (p=0.03) for both activities, while the effects of

wood versus plaster substrates are not.

Table 8C-16. Estimated Substrate Effect on Settled Log-Transformed Dust (log(Dust)),

Before and After Adjusting for Paint Lead Loading, in the CED Phase

Activity Loadings? Parameter Estimate Error Freedom P-Value

Model

Adjusted for Degrees

Paint Lead Standard of (1) (2)

Drilling

Unadjusted Intercept 2.54 1.18 9 0.06

Distance 0.133 0.321 9 0.69

Adjusted Distance 0.160 0.412 9 0.71

Intercept 0.730 1.329 8 0.60

Paint 0.258 0.114 33 0.03

Sawing

Unadjusted Intercept 1.35 1.34 6 0.35

Distance 0.271 0.254 6 0.33

Adjusted Intercept 0.594 1.359 5 0.68

Distance 0.268 0.278 6 0.37

Paint 0.148 0.066 24 0.03

Indicates whether an effect for paint lead loading is included in the model. (1)

"Intercept" represents the baseline increase in log(Dust) associated with disturbing wood substrate versus plaster (2)

substrate. "Distance" represents the amount this increase in inflated by moving one foot closer to the activity. "Paint"

represents the increase in log(Dust) associated with a unit increase in paint lead loading.

Overall, the data collected in the CED phase is not sufficient to reach a conclusion on

whether the difference in lead paint concentration is responsible for differences in lead loadings

observed between activities performed on wood and plaster.

The Difference Between [0-1] Foot and [5-6] Foot Samples

If the second hypothesis is valid, then it is reasonable to assume that the estimated [5-6]

foot SSDCs would be positively correlated with worker personal exposure result within each

experimental unit, while the estimated [0-1] foot SSDCs would be positively correlated with the

observed average paint lead loadings from within each experimental unit. The estimated [0-1] and

[5-6] ft SSDCs within each experimental unit are calculated by integrating the area underneath the

exponentiated regression lines from 0 to 1 feet and 5 to 6 feet, respectively, based on parameter

estimates from Model (CED-3) in Appendix C.
8-74

Table 8C-17 gives the estimated correlations between PEM , 6-foot by 1-foot lead ijk

loading gradient , [0-1] foot SSDC , [5-6] foot SSDC , and Paint , where "ijk" represents the ijk ijk ijk ijk

same experimental unit. Values above the diagonal are based on the original scale, and values

below the diagonal are based on the log-transformed values within each experimental unit.

Table 8C-17. Correlations of PEM Lead Concentrations, Settled Dust Lead Loadings, and

Paint Lead Loadings, Within an Experimental Unit, in the CED Phase 

PEM Gradient SSDC SSDC Paint ijk

6' × 1' [0-1] Foot [5-6] Foot

ijk ijk ijk ijk

PEMijk 0.35 0.25 0.46 0.26

Gradientijk 0.39 0.98 0.42 0.14

[0-1]SSDCijk 0.28 0.98 0.25 0.09

[5-6]SSDCijk 0.83 0.46 0.32 0.23

Paintijk 0.21 0.38 0.32 0.25

Note: Correlations above the diagonal are based on untransformed data. Correlations below the diagonal are based on logtransformed data.

The above correlation table shows that the log(PEM) concentrations are most highly

correlated with the log lead amounts in the [5-6] foot region. This result supports the contention

that the estimated lead loading in the [5-6] foot SSDC is representative of airborne dust and

smaller particles. A high correlation (0.98) is also observed between the log lead amount within

the 6-foot by 1-foot dust gradient and the log lead amount within the [0-1] foot SSDC region on

both the log-transformed and untransformed scale, indicating that the gradient measure is being

driven primarily by the high lead loading levels observed near the point of activity. 

8C-2.4 THE POTENTIAL FOR CROSS CONTAMINATION WITHIN R&R FIELD STUDIES

The experimental design of the CED phase specified several different R&R activities

within the same housing unit. Additionally, there were potentially two different CED activities

being conducted simultaneously (in different rooms) at any given time. Thus, it is possible that

the measures of potential lead hazard associated with one CED activity were cross-contaminated

by lead generated by another CED activity. This possibility was recognized in the experimental

design of the CED phase, and was made even more apparent during an activity in which a worker

cut into plaster with a circular saw causing plaster dust to be distributed throughout the dwelling

unit. The following precautionary measures were taken to minimize the effects of cross

contamination on the study results:

1. In preparation for the CED activities, the floors in each room were sealed with clear

plastic sheeting (held down with duct tape). This was done to reduce the effects of

settled dust that was present in the housing units prior to the CED phase.
8-75

2. Whenever possible, the entrances and exits to a room in which a CED activity was

performed were sealed off with clear-plastic. This precautionary measure was used

to minimize the effects of cross contamination from one activity to another.

3. If there was any visible dust present in a room prior to the occurrence of a CED

activity, the entire room was HEPA-vacuumed and wet-wiped prior to the start of

the activity.

4. Tools that were used during a CED activity were cleaned appropriately following the

completion of that activity to reduce the potential for cross-contamination from one

activity to another.

We can assess the effect of cross-contamination on the results of the CED phase through

an investigation of some specific settled dust lead loading results in two ways:

1. One of the CED activities (drilling into wood) was performed on the same surface

twice. The first occurrence of this activity was performed directly before the sawing

into plaster activity. The settled dust samples from this first occurrence (collected

after the sawing into plaster) were very likely to contain settled dust and debris from

both the drilling into wood and the sawing into plaster. The second occurrence of

the drilling activity was isolated from all other activities. Thus, a comparison

between these two occurrences will give us an assessment of the extent of cross

contamination that had occurred during the sawing into plaster. These data were

investigated by comparing the two regression lines which predicted log(Dust ) as a ijkl

function of distance. The two intercept estimates were 10.4 and 13.5 while the slope

estimates were -1.19 and -1.73. There was no statistically significant difference

between the two regression lines at the 0.05 level of significance. 

2. The third floor of the first housing unit had two bedrooms whose entrances were

separated by a narrow hallway. Two activities (sawing wood and door modification)

were performed simultaneously, one in each bedroom. The entrances to each

bedroom were sealed using the clear-plastic doorways. An SSDC was placed in the

hallway that separated these two bedrooms just prior to the start of these two

activities. This settled dust sample was specifically designed to measure the amount

of lead that is likely to escape through the clear-plastic doorways. The lead loading

on this SSDC was 432 μg/ft .2

In the first assessment, we find that the fallout of fine dust and debris from the sawing/plaster

activity did not add a significant amount of lead to the settled dust samples in the drilling wood

activity. The second assessment demonstrates that a substantial amount (432 μg/ft ) of lead may 2

escape the protective containment barriers. We feel that some of the lead that settled on this

SSDC is attributable to the lead that was carried out into the hallway on the clothing of the

workers. We also feel that it is unlikely that a substantial amount of lead-contaminated dust

would have exited through the plastic doorway from one room and entered through the plastic

doorway of another room during the course of the study.
8-76

Clearly the potential for cross-contamination of environmental field samples existed in the

CED phase. Given the substantial amount of lead disturbed by the CED activities under

investigation, it is unlikely that the amount of cross-contamination that occurred during the CED

phase had a qualitative impact on the overall results. 

8C-2.5 DISCUSSION OF THE RESULTS OF THE CED PHASE

Table 8C-18 presents estimates of observed lead levels associated with worker personal

exposure and lead in settled dust, for each CED activity. The model estimate of the geometric

mean of the personal exposure lead concentrations, and the estimated amount of lead in settled

dust within a 6-foot by 1-foot region from the activity are summarized in this table.

The major result of the CED phase becomes clear when studying Table 8C-18:

The amount of lead disturbed by the

CED activities was substantial.

 Table 8C-18. Statistical Estimates, with Standard Errors, of Worker Personal Exposure to

Airborne Lead, and 6' × 1' Gradient Dustfall Lead Amounts for Each CED

Activity 

Activity Substrate (with LOG Standard Error) (with Standard Error)

Model Estimates

Geometric Mean of PEM Lead Amount in 6' x 1'

Concentration (μg/m ) Gradient (μg) 3 (1) (2)

Target Activities in the CED Phase

Demolition Plaster 108 (0.325) 19500 (14300)

HVAC Removal Dust 49.6 (0.116) 7710 (14100)

Generic R&R Tasks

Door Modification Wood 590 (0.574) 145000 (82700)

Sawing Wood 546 (0.155) 449000 (167000)

Sawing Plaster 110 (0.783) 82300 (81400)

Drilling Wood 15.1 (0.489) 266000 (143000)

Drilling Plaster 6.76 (0.255) 21400 (20600)

Abrasive Sanding Wood 254 (0.424) (Hand) 257000 (188000)

571 (0.602) (Power)

Component Removal Wood 344 (0.0319) --

Cleanup Wood 102 (0.145) --

Cleanup Plaster 24.5 (0.275) --

Geometric mean results from exponentiating the estimated intercept term of Model (CED-1) in Appendix C. The log (1)

standard error is associated with the intercept estimate. These estimates are also found in Table 8C-4.

Lead amount is estimated by fitting Model (CED-5) to SSDC settled dust lead loadings, then integrating under the curve (2)

from 0 to 6 feet distance. This approach is detailed in Section 8C-2.3.2 and Appendix C.
8-77

The estimated geometric mean worker personal exposure to airborne lead over the duration

of activity was above the OSHA PEL of 50 μg/m in every CED activity with the exception of 3

drilling into either plaster or wood, HVAC removal, and cleaning up after activities which

disturbed lead painted plaster. The average lead-loading in the gradient region was greater than

1000 μg/ft for all CED activities as they were performed. 2

Secondary results of the CED phase are:

1. CED activities which disturb lead-painted wood surfaces are generally associated

with higher personal exposure to airborne lead and higher lead levels in settled dust

when compared to CED activities which disturb lead painted plaster surfaces. This

effect is confounded with the fact that wood surfaces generally had higher

concentrations of lead-based paint in comparison to plaster surfaces.

2. Settled dust found in interior HVAC duct work had high levels of lead. This lead can

be exposed to workers and occupants if the HVAC systems are disturbed.
8-78

8D-1.0 INTRODUCTION AND OBJECTIVES OF THE CLEANUP INVESTIGATION 

As presented in Section 1.1, one of the primary technical objectives of the R&R study was

to determine the extent to which R&R workers disturb lead and create a lead-based paint

exposure to occupants or other exposed individuals while conducting R&R activities. The three

study phases of the EFSS (Sections 8A through 8C) collected lead loading data from settled dust

samples before cleanup in support of this objective. These data do not address the extent to

which typical cleanup procedures reduce lead levels in dust that settles following the activity. In

response to this concern, the EFSS included the design and conduct of a field study addressing the

effect of typical cleanup procedures on potential occupant lead exposures.

The EFSS cleanup investigation had the following technical objectives:

! Compare post-activity lead loading results within settled dust collected before

cleanup versus results in dust collected after cleanup, and determine how the

outcome of the comparison is a function of the cleanup method used.

! Characterize lead loadings in settled dust that is likely to remain after R&R work and

typical cleanup procedures are completed.

The cleanup investigation in the EFSS was designed as an independent follow-on to the

CED study phase presented in Section 8C. As in the CED phase, the cooperation of the Denver

(CO) Housing Authority (DHA) was solicited to provide vacant housing units for conducting

simulated R&R activities in a controlled environment. An apartment complex previously used in

the CED phase (and thereby screened for the presence of lead-based paint hazards) was the site

for the cleanup investigation. As they did in the CED phase, the DHA provided trained abatement

workers to conduct the R&R activities in these units. The workers used the same protocols

established for the CED study phase.

8D-2.0 STUDY DESIGN IN THE CLEANUP INVESTIGATION

To address the objectives for the cleanup investigation, the study design considered two

different methods of cleanup that were applied after performing two different types of generic

R&R activities. The two cleanup methods were selected as those typically used by many R&R

workers:

! dry (broom) sweeping, and

! use of an industrial non-HEPA vacuum cleaner (Shop-Vac®).

The cleanup procedures were performed as if the R&R worker had completed carpentry work in a

private residence and wanted to clean the work area prior to the completion of the job.

The two R&R activities, both conducted on wood door surfaces covered with lead-based

paint, were:
8-79

! drilling (using a 1⁄4" drill bit), and

! abrasive (power) sanding.

Protocols for conducting these activities were the same as those used in the CED phase (see

Section 8C-1.1.1). Each activity was scheduled to be no longer than one hour in duration. Each

combination of R&R activity and cleanup method was replicated three (3) times, for a total of

twelve (12) field study experiments. These experiments were labeled "experimental units".

As a means of minimizing cross-contamination across units, the study directed that the

twelve experimental units be conducted in separate apartments within the complex. However, as

only nine apartments were made available to this study, four of the experimental units were

conducted in different rooms of a single apartment, while the remaining experimental units were

conducted in separate apartments. Other precautionary measures taken to minimize crosscontamination from other sources included:

! The floors, vents, and entrances of the activity room were sealed with clear plastic

sheeting (held down with duct tape), to reduce the effects of settled dust present in

the apartment prior to the investigation and to minimize the transfer of dust from one

activity room to another.

! To characterize the level of any potential contamination that could have resulted

from the demolition of buildings within the complex that occurred simultaneously

with the investigation, two paired dust-vacuum samples were collected from SSDCs

that were left overnight in previously unused activity rooms.

As was the practice throughout the EFSS, no attempt was made to minimize dust generation

during the activity.

8D-2.1 SAMPLING DESIGN IN THE CLEANUP INVESTIGATION

The sampling design of the cleanup investigation was established to characterize the

following:

! levels of lead in the paint on surfaces disturbed by the R&R activity

! lead loadings in dust that settles following completion of the R&R activity, taken at

varying distances from the activity both prior to and following cleanup

! lead loadings in dust that settles up to one day following the activity and cleanup

! how lead loadings differ between dust-vacuum samples and dust-wipe samples

! how lead loadings differ between dust-vacuum samples taken at adjacent locations

("side-by-side").
8-80

Within an experimental unit, an area was identified where the specified R&R activity and

subsequent cleanup method would be performed. The door on which the activity would be

performed was confirmed to contain lead-based paint by use of a portable X-ray fluorescence

(XRF) analyzer. In addition, a single paint chip was taken from the door surface for laboratory

analysis to more accurately characterize lead levels in the paint that would be disturbed as a result

of the activity.

Immediately prior to the start of the activity within an experimental unit, a clean 4'x8'

piece of new linoleum sheeting (mounted on plywood) was placed on the floor at the base of the

activity. The linoleum represented a pristine floor surface that became contaminated only by the

conduct of the R&R activity. The design associated with collecting settled dust samples from the

linoleum surface is presented in Figure 8D-1.

Approximately one hour after the completion of the activity, but prior to the start of

cleanup, dust-vacuum samples were collected from three one-square-foot areas of the linoleum

surface, each at a specified distance from the activity (0, 3, and 6 feet). The three samples

represented the total amount of lead that was disturbed by the activity and settled at the given

distances from the activity.

After the three pre-cleanup dust samples were collected, the linoleum surface was cleaned

by the method assigned to the experimental unit. Then, six additional one-square-foot areas were

identified on the linoleum surface from which post-cleanup settled dust samples were collected

(Figure 8D-1). Four of the six samples consisted of two pairs of dust-vacuum/dust-wipe samples

(i.e., one sample within the pair collected by vacuum techniques, the other collected by wipe

techniques), where the two samples within a pair were taken from adjoining locations (i.e., sideby-side). The remaining two samples were a side-by-side pair of dust-vacuum samples. Wipe

samples were taken in order to compare results to lead clearance testing standards. Once the

post-cleanup dust samples were taken, two stainless steel dustfall collectors (SSDCs) were placed

on the linoleum surface. A dust-vacuum sample was collected from each SSDC on the morning

of the next day. These samples were taken to characterize the amount of airborne lead that is

likely to settle after cleanup has been performed.

Table 8D-1 presents the proposed types and numbers of environmental field samples (both

regular and QC samples) collected within each experimental unit in the cleanup investigation. 

Methods used to collect paint and dust samples followed the same field sampling protocols

applied throughout the R&R study.

8D-3.0 STUDY RESULTS FOR THE CLEANUP INVESTIGATION

Analytical data were available for statistical analysis from all environmental field samples

that were collected in the cleanup investigation. These data included lead loadings in paint chip

samples (expressed in mg/cm ) and settled dust samples (expressed in μg/ft ). Data are 2 2

summarized by sample type and collection method in Tables Cl-1 through Cl-4 in Section A.4 of

Appendix A.
0'

1'

2'

3'

4'

5'

6'

7'

8'

PRE POST POST SSDC

(V) (W)

PRE POST POST

(V) (V)

PRE POST POST SSDC

(V) (W)

DOOR WALL

1' 2' 3' 4'

8' x 4'

new linoleum

surface

Note: Positioning of samples within a given distance from activity differed among the experimental units.

Legend: 

=

=

=

=

Pre-cleanup dust-vacuum sample location

Post-cleanup dust-vacuum sample location

Post-cleanup dust-wipe sample location

Next-day SSDC dust-vacuum sample location

PRE

POST

SSDC

(V)

POST

(W)

8-81

Figure 8D-1. Settled Dust Sampling Locations Specified by the Sampling Design for the

Cleanup Investigation
8-82

Table 8D-1. Numbers and Types of Environmental Samples (Regular and QC) Proposed in

the EFSS Cleanup Investigation

Regular Samples

When Sample Was Sample Collection Proposed per Number

Taken Method Sample Type/Location Exp. Unit Proposed

Number Total

(1)

Pre-Activity Chipping Paint chip (wood door) 1 12

Post-Activity, Pre- Settled dust (linoleum

Cleanup surface) Vacuum 3 36

Post-Cleanup Settled dust (linoleum Vacuum 4 48 surface)

Wipe 2 24 Settled dust (linoleum

surface)

Next Day Vacuum Settled dust (SSDC) 2 24

TOTAL 12 144

Field QC Samples

When Sample Was Sample Collection Frequency of Total

Taken Method QC Sample Type Sampling Number

Proposed

Pre-Activity or Pre- 1 per activity

Sampling day Paint Chip Field blank 3

Vacuum Field blank 4 1 per vacuum

sampling day

Wipe Field blank 3 1 per wipe

sampling day

TOTAL 10

See Figure 8D-1 for position of dust-vacuum and dust-wipe sample locations relative to the R&R activity. (1)

8D-3.1 LEAD LEVELS IN PAINT TO BE DISTURBED

To characterize lead levels in paint to be disturbed as a result of R&R activity, paint chip

samples were taken from each of the twelve wood doors on which the activities would take place. 

Three paint chip results were associated with each of the four combinations of activity and

cleanup method, one result for each time the activity/cleanup combination was performed in this

investigation. The measured lead levels in paint chips are summarized in Table Cl-1 of Appendix

A (Section A.4). The combination with the highest observed lead levels in paint was abrasive

sanding/vacuum cleanup, where all three lead levels exceeded 12 mg/cm . For drilling/vacuum 2

cleanup and abrasive sanding/broom sweeping, two of the three paint chip lead results exceeded

1.0 mg/cm . Only one of the three results exceeded 1.0 mg/cm for drilling/broom sweeping. 2 2

Even in situations where low results were observed, however, conduct of the activity resulted in

high levels of lead in post-activity settled dust samples as illustrated in Table Cl-2 in Appendix A

and discussed below. 
8-83

8D-3.2 PRE- VERSUS POST-CLEANUP RESULTS

In characterizing the difference in post-activity settled dust lead loadings between pre- and

post-cleanup, loadings from post-cleanup dust-wipe samples were compared to the pre-cleanup

dust-vacuum samples at a given distance from the activity. Wipe samples rather than vacuum

samples were chosen to characterize post-cleanup lead loadings, as only small amounts of dust

tended to remain following cleanup. Wipe sampling techniques are typically more efficient at

measuring lead loadings from smooth surfaces with small amounts of dust, while vacuum

techniques are more appropriate when large amounts of dust are to be collected. This is evident

from Table Cl-3 in Appendix A (Section A.4), where dust-wipe lead loadings were consistently

higher than vacuum-wipe lead loadings at the same distance from the activity for the less-dirty

drilling activity, while the highest lead loadings among the more-dirty abrasive sanding activity

were observed among vacuum-dust samples.

For each target activity and cleanup method, Table 8D-2 presents the geometric mean lead

loading in pre-cleanup dust-vacuum samples, along with the average ratio of post-cleanup dustwipe sample loading to the pre-cleanup sample loading observed on the same surface at the same

distance from the activity. At each distance, pre-cleanup loadings tended to be higher for abrasive

sanding than for drilling. Reasons for this finding could include higher lead loadings in the paint

associated with abrasive sanding activities, as well as differences in the activities. At the zero-feet

distance, post-cleanup lead loadings averaged one percent or less of the corresponding precleanup lead loadings for each activity and cleanup method. Based on results of a paired t-test on

log-transformed lead loadings, these declines are statistically significant at the 0.05 level. In

contrast, little if any reduction is observed at the six-feet distance. For all but abrasive

sanding/vacuum cleanup, the average ratio of post-cleanup to pre-cleanup results on the same

floor surface exceeded one. In each case, however, the paired t-test results indicated that the

average ratio did not statistically differ from one. This implies that the cleanup methods

conducted in this investigation do little to cause statistical changes in dust lead levels at this

distance. Therefore, one can conclude that the efficiency of cleanup, as measured by a percent

reduction of lead loadings in remaining dust, declines as distance from the activity increases. 

This conclusion holds for both activities considered in the investigation, even though pre-cleanup

lead loadings tended to be higher for one activity.

The same statistical methods used in the CED phase to characterize lead levels in settled

dust were applied in the cleanup investigation for both pre-cleanup and post-cleanup sample lead

loadings. This approach involved fitting a regression model for each combination of R&R activity

and cleanup method to express log-transformed lead loadings as a function of distance from

activity and experimental unit. A form of the "population" random effects model (model 
log(Dust(ij)kl) ' $0(ij) % $1(ij)

Distance(ij)kl % R0(ij)k % R1(ij)kDistance(ij)kl % Q

(ij)kl ,

8-84

Table 8D-2. Geometric Mean of Pre-Cleanup Lead Loadings, and the Average Ratio of Postto Pre-Cleanup Lead Loadings on the Same Floor Surface 

R&R Activity Method (Pre-Cleanup) Floor Surface Cleanup) Floor Surface

Cleanup Mean Loading Lead Loadings on a Loading (Pre- Lead Loadings on a

0 Feet from Activity 6 Feet from Activity

Geometric Post- to Pre-Cleanup Mean Post- to Pre-Cleanup

Average Ratio of Geometric Average Ratio of

Drilling Broom 26,700 0.013 65.0 3.65 *

Drilling Vacuum 73,500 0.008 146 1.12 *

Abrasive Sanding Broom 653,000 0.007 1380 1.77 *

Abrasive Sanding Vacuum 203,000 0.010 491 0.69 *

 Note: Geometric means in this table are rounded to three significant figures.

 The average difference (taken across experimental units) between (log-transformed) post-cleanup result and *

pre-cleanup result on a given floor surface is significantly different from 0 at a 0.05 level.

(CED-5) of Appendix C) was fit separately for pre- and post-cleanup sample lead loadings and for

each combination of activity (i) and cleanup method (j):

where

Dust is the dust lead loading (μg/ft ) measured on the l sample from the k (ij)kl

2 th th

occurrence of activity i and cleanup method j

Distance is the distance (ft) from the activity of the l sample from the k occurrence (ij)kl

th th

of activity i and cleanup method j

$0(ij) is the baseline average log-loading for samples associated with activity i and

cleanup method j

$ is the slope relating log-loading to distance from activity for samples 1(ij)

associated with activity i and cleanup method j

R is a random effect which represents how the baseline average log-loading 0(ij)k

for the k occurrence of activity i and cleanup method j differs from the th

overall average $0(ij)

R is a random effect which represents how the slope associated with the k 1(ij)k

th

occurrence of activity i and cleanup method j differs from the overall slope

$1(ij)

e is the error term. (ij)kl
Lead&loading(μg/ft 2

) ' exp($0(ij)) @ exp($1(ij)Distance)

8-85

The goal of fitting this model to the observed dust-lead loading data was to estimate average lead

loading in settled dust, expressed as a function of distance from the activity. A curve quantifying

this relationship was determined for each combination of activity and cleanup method, and for

pre- and post-cleanup lead loadings. The curve expresses (untransformed) average lead-loadings

as follows:

where the slope and intercept terms were estimated from the model fit. By integrating the area

underneath this curve from distance=0 to 1 foot, we obtain the expected lead-loading of an area

within one foot of the activity. Similarly, by integrating this curve from distance=5 to 6 feet, we

obtain the expected lead-loading of an area located 5-6 feet from the activity. The measure that

was chosen in the R&R study to represent lead disturbance and the potential hazard to occupants

from lead in settled dust is the lead loading within a 6-foot by 1-foot gradient region extending

from the activity. This measure was determined by integrating the area underneath the estimated

curve from distance=0 to 6 feet. See Section C.5 of Appendix C for more detailed discussion of

the gradient lead-loading.

The estimated average pre- and post-cleanup lead loadings from 0-1 feet and 5-6 feet from

the activity, and the estimated gradient lead loading are presented in Table 8D-3 for each

combination of activity and cleanup method. Also included in this table are the standard errors

associated with these estimates, which were obtained by the Delta Method (Bishop, Fienberg, and

Holland, 1975) (see Section C.5 of Appendix C). It should be noted that while the sample sizes

(i.e., number of experimental units) within each activity/cleanup method combination are relatively

small, the Delta Method is based in asymptotic normal theory. As a result, the standard errors are

likely only rough approximations.

The estimated lead loadings in the 0-1 foot area and 5-6 foot area have different

interpretations. The 0-1 foot area loading is representative of the amount of lead that is likely to

fall directly underneath the surface being disrupted, while the 5-6 foot area loading is more

representative of the amount of lead that becomes airborne in dust and small particles and settles

at a distance from the activity. By comparing these two estimates, one gains some perspective on

the amount of disturbed lead that is likely to stay localized, versus the amount that is likely to

become airborne.

For both activities in the cleanup investigation, approximately 65% of the lead in the

gradient settled within one foot of the activity, even though higher lead loadings (both pre- and

post-cleanup) were associated with abrasive sanding than with drilling. Therefore, while

differences in lead loadings may exist among the activities, the relative distribution of lead within

6 feet of the activity was consistent. This type of information may be useful in the design of final

cleanup procedures for R&R workers to minimize occupant exposures resulting from the activity.
8-86

Table 8D-3. Estimated Lead Loadings (μg/ft , with Standard Errors) for Pre- and Post- 2

Cleanup, and Percent Reduction from Pre- to Post-Cleanup Periods, As

Estimated from Statistical Modeling Procedures

R&R Method of Collection 6'×1' Gradient 0 to 1 foot from from Activity

Activity Cleanup (Post-Activity) (μg/6ft ) Activity (μg/ft ) (μg/ft )

Time of Sample 5 to 6 feet

Lead Loadings

2 22

Drilling Broom Pre-Cleanup 22,400 (27,900) 14,200 (18,400) 94 (128)

Post-Cleanup 885 (661) 166 (122) 130 (99)

% Reduction 96.0% 98.8% (38.3%)

Drilling Vacuum Pre-Cleanup 54,300 (126,000) 35,100 (86,400) 197 (243)

Post-Cleanup 1450 (1250) 361 (382) 147 (94)

% Reduction 97.3% 99.0% 25.4%

Abrasive Broom Pre-Cleanup 305,000 (608,000) 196,000 (426,000) 1155 (1738)

Sanding

Post-Cleanup 5800 (6350) 1070 (1120) 865 (999)

% Reduction 98.1% 99.5% 25.1%

Abrasive Vacuum Pre-Cleanup 269,000 (566,000) 171,000 (365,000) 1129 (2101)

Sanding

Post-Cleanup 3350 (1240) 809 (282) 357 (192)

% Reduction 98.8% 99.6% 68.4%

On an average basis across the investigation, Table 8D-3 shows that for both activities and

under both cleanup methods, post-cleanup lead loadings were more than 95% reduced from precleanup levels over the entire gradient region, as well as within one foot of the activity. However,

at 6 feet from the activity, only marginal reductions in lead loadings were observed on a

percentage basis. There is evidence from Table 8D-3, however, that vacuum cleanup methods

may perform better than dry sweeping methods at the 6-foot distance when considering the

percent reduction in lead loadings from pre- to post-cleanup. These results were consistent for

both activities and with the results of the paired analysis summarized in Table 8D-2.

8D-3.3 POST-CLEANUP RESULTS

Post-cleanup lead loadings for samples collected by wipe sampling techniques were used

to characterize the amount of lead remaining following the activity and cleanup to which

occupants may be exposed. Wipe sample results were directly comparable to the EPA interim

health-based standard of 100 μg/ft . As a result, wipe sample results were more relevant than 2

vacuum sample results for making conclusions on lead levels relative to potential occupant

exposure.
8-87

As seen in Tables 8D-2 and 8D-3, post-cleanup lead loadings were substantially reduced

from pre-cleanup levels. However, the post-cleanup values often remained above EPA's internal

health-based standard of 100 μg/ft , even at 6 feet from the activity. For both cleanup methods, 2

post-cleanup lead loadings tended to be higher for the abrasive sanding activity than for the

drilling activity. From these results, one may conclude that the typical cleanup methods

considered in this investigation reduce available lead loadings on surfaces, but potentially more

efficient methods (or repeated applications of the typical methods) are necessary to clean surfaces

to meet indicated standards.

8D-3.4 NEXT-DAY SSDC LEAD LOADING RESULTS

To characterize the amount of airborne lead that settles after cleanup, dust-vacuum

samples were collected the morning following activity and cleanup from two SSDCs positioned

on the linoleum surface upon conclusion of cleanup. The SSDCs were placed at 0 and 6 feet from

the activity (see Figure 8D-1). Table Cl-4 of Appendix A (Section A.4) provides descriptive

statistics of dust lead loading at both distances for each combination of activity and cleanup

method. The lead levels in these samples were low to moderate; the geometric mean exceeded

100 μg/ft in only one situation (abrasive sanding, broom sweeping, at 5-6 foot distance). 2

Interpreting the results of the next-day SSDC dust samples was complicated by the

potential for contamination by sources other than the R&R activity, such as the demolition of

neighboring buildings within the apartment complex. To characterize the amount of

contamination from outside sources, four vacuum samples were collected from SSDCs that were

left overnight in previously unused activity rooms. The lead loadings in these four samples ranged

from 28.0 to 311 μg/ft . Because these samples show high potential for cross-contamination from 2

outside sources, it is possible that lead levels in the next-day SSDC dust samples were affected by

these sources. However, the settled dust results from pre- and post-cleanup samples were likely

not affected by outside sources, as they were collected within one hour of activity or cleanup.

8D-3.5 CONCLUSIONS

The following conclusions can be made as a result of the findings determined from the

cleanup investigation:

! Both cleanup activities considered in this investigation led to substantial reductions

in lead loadings in settled dust. This result was more apparent immediately adjacent

to the activity, where post-cleanup lead loadings were more than 95% reduced from

pre-cleanup levels. However, the efficiency of cleanup declined as distance from

the activity increased. The extent of decline in efficiency, however, was more

apparent for dry sweeping methods than for vacuum cleanup methods.
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! For purposes of planning cleanup strategies, it was determined that approximately

65% of the lead in the estimated 6-foot by 1-foot gradient for both activities settled

within one foot of the activity. This result held regardless of the magnitude of lead

loadings existing within 6 feet of the activity.

! Despite performing the cleanup procedure, post-cleanup lead loadings were

observed to exceed EPA's internal health-based standard of 100 μg/ft , even at 6 2

feet from the activity. Post-cleanup lead loadings tended to be higher for the

abrasive sanding activity than for the drilling activity for both cleanup methods. As

a result, potentially more efficient cleanup methods (or repeated applications of the

methods considered in this investigation) are necessary to clean surfaces to at or

beyond indicated standards, despite the marked decrease in lead loadings that can

result from conducting cleanup procedures.
8-89

8E-1.0 DESCRIPTION OF RELEVANT DATA LOCATED FROM OTHER SOURCES

The approach taken to uncover other extant sources of data that relate R&R activities to

lead exposures is discussed in detail in Section 2.4 of Chapter 2. 

The minimum requirements for accepting a source of extant data as applicable to the

objectives of the EFSS included the following:

1. The source needed to provide data related to activities that can be considered

representative of renovation and remodeling work as it is currently being conducted

in an unregulated environment.

2. The source needed to provide either task-length personal exposure measurements

or settled dust measurements related to a well-specified R&R target activity,

generic task, or combination of R&R activities.

3. The activities needed to be conducted in an environment with lead-based paint

present. (Specifically, the lead in paint chips measurements from surfaces in the

activity area needed to be above 0.5% by weight or 1.0 mg/cm .) 2

4. The sampling and analysis methods needed to follow standard protocols and meet

minimum quality assurance standards.

Eight studies were identified as having collected data that met these requirements. The

studies included data on cleanup, component removal, demolition, exterior siding, surface

preparation, and window replacement. Surface preparation was the only activity not monitored in

the EFSS for which sufficient data are available from other sources to allow for estimating

average exposure levels. All studies collected task length personal exposure data and provided

information on lead levels in paint on surfaces to be disturbed by the activity. In addition, one

study included data from settled dust samples collected on 1 ft tiles. Descriptions of the eight 2

sources of data are given below: 

CONSAD Research Corporation

Under contract with OSHA, CONSAD Research Corporation in Pittsburgh, Pennsylvania,

collected personal exposure data from a series of construction projects throughout the United

States. The exposure information was collected to provide data for OSHA's Interim final

standard for lead in construction. The documented studies ranged from large industrial paint

removal projects to residential window replacement. Three studies, performed between March

1991 and January 1993, involved R&R activities targeted in the EFSS. The first study involved

surface preparation — removing lead-based paint from metal door jams and from walls and

ceilings by dry scraping. The second study, characterized as component removal, documented the

removal of interior wood trim using a hammer and claw-bar. The third study monitored the

demolition of interior walls and ceilings in a home using hammers and claw-bars. These studies

were performed in situations which reflected a typical R&R setting. Although some of the
8-90

workers were familiar with lead-dust minimization practices, no such practices were used during

the monitored studies.

NIOSH, Ohio University Cleanup

During a three-day period in early May 1992, NIOSH conducted a comparison study of

lead paint cleanup methods on the campus of Ohio University in Athens, Ohio. The building in

which the study was conducted was built in 1873, had been unoccupied for many years, and had

much loose and peeling paint on the walls. Although the study was classified by NIOSH as a

study of cleaning methods, it is considered a combined study of both surface preparation and

cleanup relative to the EFSS definition of target activities. Three methods of surface preparation

and cleaning were compared:

! dry scraping followed by dry broom sweeping

! misting painted surfaces with water and scraping (wet scraping) followed by highefficiency particulate air-filtered (HEPA) vacuuming

! wet scraping followed by HEPA vacuuming, with a HEPA-filtered air-filtration

device (AFD) placed in the room to exhaust room air to the outside.

Eighteen rooms were cleaned by three crews of two workers, with each crew employing the three

cleaning methods in two rooms each. All the work was performed on one day. All 18 rooms had

detectable lead concentrations in paint chips, but nine did not have mean levels above the federal

lead-based paint criterion of 0.5% lead by weight. The nine that did have lead levels in paint chips

above 0.5% had levels ranging from 2.8% - 19% lead by weight (NIOSH, Ohio University, May

1993). Since the building as a whole was considered to be highly contaminated with lead, all

results were included in the analysis. 

To compare the personal exposure data collected in the Ohio University study to data

from the EFSS, the three cleaning methods were subsetted into two categories: dry methods and

wet methods. The dry methods included only the dry scraping with dry sweeping, while the wet

methods included wet scraping followed by HEPA vacuuming, as well as wet scraping followed

by HEPA vacuuming and use of a negative-air AFD. 

National Association of Home Builders (NAHB)

The National Association of Home Builders (NAHB) provided personal exposure

information for a case study of the airborne lead produced when painted wooden shingles were

removed from a garage in Atlantic City, New Jersey. The garage had two layers of shingles, with

only the top layer painted with lead-based paint. For approximately three hours, a home owner

removed shingles from a 260 square-foot section of his garage using a flat pry bar to remove the

shingles and a hammer to remove the nails. During the process, some of the shingles split,

causing dust to be generated. While only one personal exposure data point was reported for this
8-91

activity, this is the only source of information on the possible lead exposures generated when

exterior siding is removed.

New York State Department of Health

This study was conducted by the New York State Department of Health in Albany, New

York, during February 1994. The purpose of the study was to characterize the personal

exposures residential house painters encounter while performing various R&R activities. The

activities monitored included manual scraping with a putty knife, manual sanding, and window

removal, with many of the activities occurring both inside and outside of the homes. The

activities were classified into R&R target activities as follows: manual scraping and manual

sanding as surface preparation (exterior and interior), and window removal as window

replacement. 

One of the two personal exposure samples collected during window replacement was

taken in an environment where the lead concentration in paint chips was reported as 0.22%. 

However, the corresponding personal exposure result was 151 μg/m , indicating significant 3

exposure even in the absence of high levels of lead in the paint (New York SDH, February 1994). 

Because of the information on potential lead exposure offered by this sample, the result was

included in the analysis despite the lead concentration in paint chips being below 0.5%.

NIOSH, Cincinnati - "People Working Cooperatively"

From June 1993 through June 1994, NIOSH recorded the personal exposures of

individuals working in the "People Working Cooperatively" program in Cincinnati, Ohio. The

workers in this program provide home repair, emergency repair, and weatherization services to

low-income elderly, disabled, and other qualified single-family homeowners. In this study, the

homes visited were generally built before 1960. Target R&R activities for which personal

exposures were observed included exterior wet and dry scraping and window replacement. The

exterior wet and dry scraping activities were considered representative of surface preparation. 

Reported data for other target activities, such as demolition, were excluded from analysis because

the lead concentration in paint chips was either not reported or less than 0.5%. 

U.S. Army Environmental Hygiene Agency

The U.S. Army Environmental Hygiene Agency conducted a study of lead exposure levels

generated by five different surface preparation methods performed over a five-day period in April

1992. The study was conducted in four military buildings in Maryland scheduled to be

demolished: three housing buildings and one office building. During the five-day period, personal

exposure levels were collected from six maintenance workers on three-hour shifts, using one of

five surface preparation methods. The surface preparation methods were wet scraping, dry

scraping, wet wire brushing, dry wire brushing, and metal wheel brushing. The purpose of the

study was to evaluate lead exposures generated by the different surface preparation methods and

to determine whether regulations needed to be implemented to prevent high exposures. In order

to compare results with the EFSS, the results from this study were identified by sample method
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(wet/dry) and location (interior/exterior). The metal wheel brush method was categorized as a

dry interior method.

U.S. Air Force

The Occupational and Environmental Health Dictorate of Armstrong Laboratory, Brooks

Air Force Base, Texas, conducted a study to determine if R&R work performed on Air Force

Military Family Housing (MFH) resulted in personal air exposures above the OSHA action level

of 30 μg/m . R&R work was performed on three Air Force bases throughout the country. The 3

activities performed were characterized as renovation, maintenance, and deleading. Deleading

activities were classified as component removal, since the actual deleading of the components was

performed off-site, and the exposure samples were collected while the components were being

removed. During the study, more than 200 personal air samples were collected. Unfortunately,

most of the personal exposure samples were associated with activity areas in which levels of lead

in paint chips were not above 0.5% concentration by weight or 1 mg/cm . This eliminated over 2

75% of the available data points according to the minimum acceptance criteria stated earlier. 

Activities observed for samples that did meet these criteria were classified into targeted R&R

activities as follows:

! Cleanup: Renovation cleaning

! Component Removal: Renovation baseboard removal and door frame removal

! Exterior Surface Preparation: Exterior renovation by hand sanding and scraping 

! Interior Surface Preparation: Interior maintenance hand sanding and scraping and

renovation hand sanding. 

Massachusetts Department of Health

The Massachusetts Department of Health, Childhood Lead Poisoning Prevention

Program, conducted a study in 1993 and 1994 to assess worker exposure to lead during surface

preparation activity. This activity prepared surfaces for abatement by encapsulation. Personal air

samples and dust wipe samples were collected at four housing units during interior surface

preparation, using both dry and wet methods. Dry methods included dry sanding and/or scraping

and feathering of edges by hand sanding, followed by a wash down with tri-sodium phosphate

(TSP). Wet methods included misting of the surface during sanding and/or scraping and

feathering of edges by hand sanding, followed by a wash down with TSP. A total of 25 specific

individual tasks were monitored, with one personal exposure sample taken for each task. Of

these, five had results less than the limit of detection (LOD), which ranged from 30 μg/m to 90 3

μg/m . The very high LODs for these samples were a combination of low sample volume and 3

relatively high instrument LODs. Because the range of possible values for these samples was so

large, it was felt that they contained no quantitative information on worker exposures, an opinion

shared also by the Massachusetts field team industrial hygienist and the laboratory chemist. 

Therefore, these five results were not included in any analysis of the data.
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In addition to the task-length average (TLA) worker exposure samples, settled dust

samples were collected from 1 ft ceramic tiles. At all units, three tiles were placed in the center 2

of the activity room and sampled for settled dust by wipe methodology at three times: prior to

start of the surface preparation activity, immediately after activity, and at least ten hours after the

activity. In three of the four units, an additional tile was placed in the center of the room after

completion of the activity and cleanup by HEPA vacuuming. A wipe dust sample was collected

from this tile approximately ten hours after placement. In one unit, one additional tile was placed

in each of two adjacent non-activity rooms after completion of the surface preparation activity and

HEPA vacuuming. These two tiles were sampled approximately ten hours after placement. 

Table 8E-1 contains a summary of the target activities, lead percentages in paint, XRF

measurements, average task lengths, percent of personal exposure samples above the detection

limit, and the personal exposure sample sizes for each of the eight studies. Also included are

whether the activities took place inside or outside of the building, and whether wet or dry

methods were used.

Table 8E-1. Summary of the Presence of Lead-Based Paint, Task Lengths, Personal

Exposure Sample Sizes, and Percent of Personal Exposure Samples Above

Detection Limit by Study and Target Activity

Study Activity Method Paint Lead (mg/cm ) (minutes) Limit (N)

Target Location/ Average % XRF Length Detection Size

Lead Levels in Paint Personal Exposure Monitoring(1)

2

Average % Samples

Task Above Sample

CONSAD Demolition Interior/Dry 13.0 --- 178 100 2

Component Removal Interior/Dry 0.52 --- 252 100 5

Surface Preparation Interior/Dry 0.53 --- 430 100 4

NIOSH, OU Cleanup/Surface Prep Interior/Dry 3.2 --- 27 100 12

Cleanup/Surface Prep Interior/Wet 4.8 --- 33 100 24

NAHB Exterior Siding Exterior/Dry 2.69 --- 137 0 1

New York Interior/Dry 6.2 --- 152 100 1

Window Replacement Interior/Dry 3.2 --- 139 100 2

Surface Preparation Exterior/Dry 11.6 --- 240 100 5

NIOSH,

Cincinnati

Window Replacement ---/Dry 15.7 --- 181 100 8

Surface Preparation Exterior/Dry 20.4 --- 265 100 15

Exterior/Wet 5.3 --- 329 100 7

U.S. Army

Hygiene Surface Preparation

Interior/Dry 5.6 --- 168 100 8

Interior/Wet 2.0 --- 170 67 15

Exterior/Dry 4.25 --- 184 0 12

Exterior/Wet 3.18 --- 182 0 12

Brooks AFB

Cleanup Interior/Dry 0.83 4.3 43 0 3

Component Removal Interior/Dry 0.92 4.2 75 38 8

Surface Preparation Exterior/Dry 8.2 9.8 246 17 6

Interior/Dry 1.9 5.2 198 20 15

Massachusetts

DPH Surface Preparation Interior/Dry --- 6.6 101 100 3

Interior/Wet --- 9.8 109 100 17

 Only data included in data analyses within this section are included in summaries within this table. (1)
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8E-2.0 SUMMARY OF PERSONAL WORKER EXPOSURE DATA FROM OTHER

SOURCES 

Summary statistics of personal exposure data from the other data sources are listed in

Table 8E-2 according to specific R&R activities and tasks. For comparison purposes, summary

statistics are also included for data collected in the EFSS. In calculating summary statistics for

this table, all sample results reported below the limit of detection were set to one-half the LOD. 

(Setting not-detected results to 0 or to the LOD had a negligible effect on the calculated summary

statistics.) All results represent task length averages (TLAs) in μg/m . 3

8E-2.1 COMPARISON OF PERSONAL WORKER EXPOSURE DATA FROM OTHER

SOURCES WITH EFSS RESULTS

Window Replacement

Figure 8E-1 presents personal worker exposure results for window replacement from the

NIOSH-Cincinnati study, the New York State Department of Health study, and the EFSS. The

NIOSH and EFSS results, both based on eight monitored workers, were very similar. In contrast,

the two workers monitored in the New York study have much higher exposures, both more than

twice the OSHA permissible exposure limit (PEL) of 50 μg/m . The New York data are in line 3

with the estimated distribution of exposures for window replacement from the EFSS data (as

presented in Table 9-1 of Chapter 9), and therefore indicate that the potential for achieving lead

exposures above the OSHA PEL during window replacement activities is not negligible. 

Demolition

Figure 8E-2 compares personal worker exposures during demolition for the CONSAD

study and the EFSS. During the CONSAD study, two samples were collected using a Marple

Cascade Impactor, which involves a series of filters that separate particles by particle size. The

average estimated exposure using this collection method was 976 μg/m , which was much higher 3

than the levels associated with two study samples collected using a 37 mm filter and NIOSH

protocol 7300. Because CONSAD reports that their experience indicates that the impactor

collection method tends to produce higher results (for which they have no explanation), the

impactor results were not included in Table 8E-2 or Figure 8E-2. 

Component Removal

Personal worker exposure estimates associated with component removal are presented in

Figure 8E-3 for the Brooks AFB study, CONSAD study, and the EFSS. The activity in all three

studies included removing lead-painted wood trim, baseboards, doors and door jams. The EFSS

results are markedly higher than those obtained in the Brooks AFB and CONSAD studies. 

Personal exposure results from the Brooks AFB study (over all monitored activities) tend to be

low compared to data from other studies (see Table 8E-2). This might be related to

characteristics of the military family housing in which the monitoring took place in that study. 

The average lead concentration in paint chips in both the CONSAD study and the Brooks AFB
8-95

study was low: 0.92% and 0.52% lead by weight respectively. In contrast, lead loading

associated with component removal activities in the EFSS averaged 7.4 mg/cm , and the activities 2

were conducted by two workers in a home that had been vacant for some time. However, this

alone does not explain such high exposure levels in the EFSS.

Table 8E-2. Summary of Personal Worker Exposure Levels as Measured by a Task Length

Average (μg/m ) for the Other Sources of Data and for Data From the EFSS 3

Study Method N Mean TLA Mean TLA Dev Value Value

Location/ Arithmetic Geometric Std Minimum Maximum

Log

R&R Target Activities

Window

Replacement

New York 2 144 144 0.07 137 151

NIOSH, Cincinnati 8 6.81 5.44 0.72 2.00 16.0 ---

EFSS 8 14.0 7.48 1.19 2.41 44.4

Demolition Interior/Dry

CONSAD 2 271 166 1.52 56.5 485

EFSS 20 153 107 0.74 33.6 947

Surface

Preparation

Brooks AFB 6 5.50 2.82 1.48 0.50 10.0

Exterior/Dry

New York 5 29.8 24.7 0.68 12.0 63.0

NIOSH, Cincinnati 15 27.8 9.16 1.84 0.20 120

U.S. Army Hygiene 12 All < LOD All < LOD --- All < LOD All < LOD

Brooks AFB 15 8.07 2.69 1.48 0.50 40.0

New York 1 1270 1270 --- 1270 1270 Interior/Dry

CONSAD 4 12.5 11.7 0.43 6.98 17.3

U.S. Army Hygiene 8 94.1 72.5 0.82 23.0 190

Massachusetts DPH 3 2000 605 1.77 70 5350

NIOSH, Cincinnati 7 17.4 6.75 1.71 0.70 63.0

Exterior/Wet

U.S. Army Hygiene 12 All < LOD All < LOD --- All < LOD All < LOD

U.S. Army Hygiene 15 88.3 22.0 2.28 < 2.00 280 Interior/Wet

Massachusetts DPH 17 254 164 0.98 40 820

Exterior NAHB Exterior/Dry 1 All < LOD All < LOD --- All < LOD All < LOD

Siding

Generic R&R Tasks

Cleanup Interior/Dry EFSS - Plaster 4 27.701 24.5 0.55 14.6 53.3

Brooks AFB 3 All < LOD All < LOD --- All < LOD All < LOD

EFSS - Wood 2 103.44 102 0.21 88.5 118

Component

Removal

Brooks AFB 8 9.06 6.28 0.91 < 2.00 30.0

CONSAD 5 7.54 7.47 0.15 5.96 8.78 Interior/Dry

EFSS 2 344.01 344 0.045 333 355

Combination R&R Tasks

Cleanup/ NIOSH, OU 12 100.0 83.1 0.65 29.0 205

Surface

Preparation

Interior/Dry

NIOSH, OU 24 48.7 27.3 1.03 5.00 360 Interior/Wet

Note: Observations less than the detection limit were set to one-half the level of detection (LOD) for this summary.
0 

20 

40 

60 

80 

100 

120 

140 

160 

New York NIOSH, Cincinnati R&R/EFSS

144 

5.44 7.48 

0 

50 

100 

150 

200 

CONSAD R&R/EFSS

166 

107 

8-96

Figure 8E-1. Comparison of Geometric Mean Task-Length Average Personal Worker

Exposures (μg/m ) for the EFSS and Other Data Sources During Window 3

Replacement

Figure 8E-2. Comparison of Geometric Mean Task-Length Average Personal Worker

Exposures (μg/m ) for the EFSS and Other Data Sources During Demolition 3
0 

50 

100 

150 

200 

250 

300 

350 

400 

Brooks AFB CONSAD R&R/EFSS

6.28 7.47 

344 

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

8-97

Figure 8E-3. Comparison of Geometric Mean Task-Length Average Personal Worker Lead

Levels (μg/m ) for the EFSS and Other Data Sources During Component 3

Removal 

Cleanup Activities

Personal worker exposures related to cleanup activity from the Brooks AFB study are

compared to EFSS results in Figure 8E-4. Only data for the CED phase of the EFSS (not the

cleanup investigation) are included in Figure 8E-4. The Brooks AFB study results are much

lower than the EFSS, especially concerning cleanup following activities that disturb wood

surfaces. All three data points entering into Figure 8E-4 for the Brooks AFB study represent

results below the detection limit.

Cleanup/Surface Preparation Combinations

As discussed in Section 8E-1.1, the NIOSH-Ohio University study contains task-length

average personal worker exposures for tasks that were a combination (according to definitions

established in the R&R study) of surface preparation and cleanup. Figure 8E-5 presents personal

worker exposure estimates for dry scraping and broom sweeping in the NIOSH study compared

to cleanup results from the Brooks AFB study and the EFSS, and to interior dry surface

preparation results from the Brooks AFB, CONSAD, U.S. Army, and Massachusetts studies. 

The results from the combined activity in the NIOSH study appear reasonable when compared to

the set of results for each individual activity.
0 

20 

40 

60 

80 

100 

120 

Brooks AFB R&R/EFSS R&R/EFSS

4.80 

24.5 

102

Plaster

Wood

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

0 

200 

400 

600 

800 

1000 

1200 

1400 

CONSAD U.S. Army R&R/

2.69 11.7 

1270* 

72.5 

605 

83.1 

4.80 24.5 

Plaster 102 

Wood

|---------------- Surface Preparation -----------------| |---------- Clean - up ----------|

Hygiene EFSS

R&R/ AFB EFSSNIOSH

OU

Mass.

DPH

Brooks

AFB

New York* 

*Sample Size = 1.

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

8-98

Figure 8E-5. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

During Cleanup and Dry Interior Surface Preparation for Various Studies

Compared to the Combination Activities of the NIOSH-OU Study

Figure 8E-4. Comparison of Geometric Mean Task-Length Average Personal Worker Lead

Levels (μg/m ) for the EFSS and Other Data Sources During Cleanup Activities 3
0 

200 

400 

600 

800 

1000 

1200 

1400 

Brooks AFB CONSAD New York U.S. Army Hygiene Mass DPH

2.70 11.7 

1270* 

72.5 

605 

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

*Sample Size = 1.

8-99

Figure 8E-6. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m ) for 3

Other Data Sources During Dry Interior Surface Preparation

8E-3.0 RESULTS OF THE ANALYSIS OF SURFACE PREPARATION DATA FROM

OTHER SOURCES

No data were collected in the EFSS on exposures related to surface preparation activities,

partly because data were expected to be available from other sources. Six such data sources were

located, and summary results from these sources were included in Table 8E-2 of Section 8E-2.0. 

Surface preparation methods in each study were subdivided into interior and exterior surface

preparation and wet and dry methods. In general, the surface preparation activity consisted of

sanding, scraping, and cleaning activities. However, the extent to which each of these generic

activities was performed differed among the studies. This reflects an inherent difficulty in defining

surface preparation, which may range from very slight touch-up of surfaces in overall good

condition to heavy scraping and sanding of surfaces in poor condition. The wide variety of

activity that may be included under surface preparation is reflected in the variability in exposure

estimates from the different studies. 

Figures 8E-6 through 8E-9 summarize personal worker exposure results from the six

studies, with one figure for each of the four combinations of interior and exterior surface

preparation and wet and dry methods. The variability in results between studies is most

pronounced in Figure 8E-6 for interior surface preparation using dry methods. A large number of

factors may be contributing to this variability based on documentation of the individual studies

and results obtained in the EFSS. The factors include the concentration of lead in the paint being

disturbed, the condition of the paint, the percent of total activity time spent sanding or scraping,

the size and air-flow characteristics of the activity room, the equipment used, personal work

habits, and small numbers of samples.
0 

30 

60 

90 

120 

150 

180 

U.S. Army Hygiene Mass DPH

22.0 

164 

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

0 

5 

10 

15 

20 

25 

30 

Brooks AFB New York NIOSH, Cincinnati U.S. Army Hygiene

2.82 

24.7 

9.16 

1.00 

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

8-100

Figure 8E-7. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m ) for 3

Other Data Sources During Wet Interior Surface Preparation

Figure 8E-8. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m ) for 3

Other Data Sources During Dry Exterior Surface Preparation 
0 

1 

2 

3 

4 

5 

6 

7 

NIOSH, Cincinnati U.S. Army Hygiene

6.75 

1.00 

Note: All sample results reported below the limit of detection (LOD) were set to one-half the LOD.

8-101

Figure 8E-9. Geometric Mean Task-Length Average Personal Worker Exposures (μg/m )3

for Other Data Sources During Wet Exterior Surface Preparation 

8E-3.1 ANALYSIS TO ESTIMATE AVERAGE PERSONAL WORKER EXPOSURE LEVELS

ACROSS STUDIES FOR SURFACE PREPARATION

Meta-analytic statistical methods are used to summarize data across studies when only

summary statistics are available. Using this approach, an estimate of the mean personal worker

exposure from surface preparation and a measure of the variability about the mean are obtained

for each study and combined to form an overall mean exposure level, taking into account both

within-study and between-study components of variation. As the raw data were available for all

studies identified in the search for other data sources, within-study and between-study variability

were estimated directly from the raw data and incorporated into overall mean exposure level

estimates and associated confidence intervals. Other meta-analysis issues and concerns that were

addressed included:

1. The assumption that the studies are a random sample from a population of studies. 

The validity of confidence intervals based on a random-effects analysis depends on

this assumption. The studies included were judged to be independent and

representative of exposures during different occurrences of surface preparation.

2. The lack of bias (e.g., publication bias) in selection of studies to be included. All

identified studies with relevant data were included in the analysis.
8-102

3. An assessment of the quality of individual studies. Each study was assessed from a

quality assurance standpoint (use of standard protocols, a certified laboratory,

experienced study personnel, etc.) and determined to meet minimum quality

assurance standards.

The statistical analysis to estimate overall mean exposure levels across studies was

conducted only on data from dry methods for two reasons: (1) these data were considered

representative of surface preparation as it is currently being conducted in an unregulated

environment, and (2) insufficient data existed for the wet methods. 

Summary statistics for the data used in estimating overall mean worker exposure levels for

interior and exterior dry surface preparation are presented in Table 8E-3. The results of the U.S.

Army study of exterior dry surface preparation showed all twelve personal exposure observations

below the limit of detection (LOD). In order to more accurately represent the variability of

measurements less than the LOD in that study and the other studies, all measurements less than

the LOD in any study were simulated by generating a random deviate from a uniform distribution

on the interval (0, LOD). The assumption of a uniform distribution assigns equal probability to

any value below the LOD, and allows for a measure of variability based on that assumption. This

approach to handling non-detected results differs from the approach used to obtain summaries in

earlier tables and figures in this section, where the result was replaced by one-half the detection

limit.

Table 8E-3. Summary Statistics for Data Used in the Statistical Analysis of the Surface

Preparation Data (Dry Methods Only)

Location Study (μg/m ) of TLA Deviation N

Geometric Mean Log Standard 3

Exterior

Brooks AFB 1.94* 1.77* 6

New York 24.7 0.68 5

NIOSH, Cincinnati 9.16 1.83 15

U.S. Army Hygiene 0.89* 0.56* 12

Interior Massachusetts DPH 605 2.17 3

Brooks AFB 2.25* 1.61* 15

CONSAD 11.7 0.43 4

New York 1270 --- 1

U.S. Army Hygiene 72.5 0.82 8

* For observations less than the limit of detection (LOD), random deviate(s) generated from a uniform

distribution on the interval (0, LOD) were used to calculate these statistics. 

Model (OS-1) in Section C.7 of Appendix C was fitted to the log transformed lead

concentrations (μg/m ) from individual personal worker exposure samples collected in each of the 3

studies listed in Table 8E-3. Model (OS-1) was fitted separately for interior and exterior dry

surface preparation. Further details on the statistical model are provided in Section C.7 of

Appendix C. 
0.1 1.0 10.0 100.0 

Geometric Mean (ug/m3)

Brooks AFB

New York

NIOSH, Cincinnati

U.S. Army Hygiene

Overall

8-103

Figure 8E-10. Comparison of Results from Statistical Analysis of Geometric Mean Task

Length Average Personal Worker Exposures (μg/m ) for Exterior Surface 3

Preparation: Overall Mean Estimate and Individual Study Mean Exposures

with 95% Confidence Bounds 

Table 8E-4 displays model estimates of the geometric means, 95% confidence intervals on

the geometric mean, and variance components (standard deviations) of worker personal exposures

for interior and exterior dry surface preparation, resulting from fitting model (OS-1). While the

geometric mean exposure is much higher for interior dry surface preparation, the 95% confidence

intervals indicate that the two estimates do not differ statistically. The nature of the diverse

results across studies for interior dry surface preparation is noted by a large study-to-study

variability compared to worker-to-worker variability.

Table 8E-4. Model Estimates of the Geometric Mean, 95% Confidence Interval and

Standard Deviation of Variance Components of Worker Personal Exposures

(Task Length Average in μg/m ) for Interior and Exterior Dry Surface 3

Preparation

Location Studies Samples from Model Geometric Mean (F ) (F )

Number of of PEM Mean Estimates Interval of Study to Study Worker to Worker

Total Number Geometric 95% Confidence

Square Root of Estimated

Variance Components

Study Worker

Interior 5 31 58.2 (2.27, 1490) 2.49 1.40

Exterior 4 38 4.33 (.407, 46.0) 1.41 1.40

To investigate the nature of study-to-study differences, Figures 8E-10 and 8E-11 provide

a comparison of the individual study estimates and associated confidence intervals with the overall

estimate and its confidence interval for interior and exterior dry surface preparation, respectively. 
0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0 1000000.0 

Geometric Mean (ug/m3)

Brooks AFB

CONSAD

U.S. Army Hygiene

Mass DPH

New York *

Overall

* Sample Size = 1.

8-104

Figure 8E-11. Comparison of Results from Statistical Analysis of Geometric Mean Task

Length Average Personal Worker Exposures (μg/m ) for Interior Surface 3

Preparation: Overall Mean Estimate and Individual Study Mean Exposures

with 95% Confidence Bounds 

8E-3.2 SETTLED DUST SAMPLES IN THE MASSACHUSETTS DEPARTMENT OF HEALTH

STUDY ASSOCIATED WITH SURFACE PREPARATION

As described in Section 8E-1.0, the Massachusetts study also collected settled dust

samples from 1-ft ceramic tiles that were placed in rooms (activity areas) where surface 2

preparation was being conducted, at various times in the study. Five types of ceramic tile

samples, all using wipe collection methods, were collected in the Massachusetts study:

1. Tiles placed in the activity area and sampled before the activity started (pre-activity)

2. Tiles placed in the activity area before the activity started and sampled immediately

following the activity (during activity; sampled 0 hrs post)

3. Tiles placed in the activity area before the activity started and sampled at least 10

hours after the activity was finished (during activity; sampled 10 hrs post)

4. Tiles placed in the activity area after all surface preparation activity was finished and

after the area was HEPA vacuumed. These were sampled at least 10 hours later (after

activity and cleanup; sampled 10 hrs post)
8-105

5. Tiles placed in rooms adjacent to the activity area after all surface preparation activity

was finished and after the activity area was HEPA vacuumed. These were sampled at

least 10 hours later (after activity and cleanup; adjacent area). 

Samples of type 4 above (after activity and cleanup; sampled 10 hours post) were collected in

only three of the four study units. Samples of type 5 above (after activity and cleanup; adjacent

area) were collected in only one of the four study units. Like the settled dust samples in the

EFSS, the first three types of samples in the Massachusetts study provide an estimate of the total

amount of lead disturbed by the activity and made available in the occupant's environment before

cleanup. The last two sample types, however, represent lead exposures that may be expected to

settle and remain in an occupant's environment after cleanup.

Results for 13 of 51 settled dust samples collected in the Massachusetts study were

reported as right-censored data (such as "> 2000 μg/ft "). These represented samples in which 2

the dilution process was terminated, since a right-censored result already indicated an

unacceptable amount of lead for the purposes of that study. These results are included as the

right-censored value in the summary statistics presented below. For this reason, inferences

concerning average differences between sample type 2 (during activity; sampled 0 hrs post) and 3

(during activity; sampled 10 hrs post), should not be made based on these summary statistics since

many of these sample types were right-censored. For example, the samples for one room resulted

in a measurement of > 120,000 μg/ft for the type 2 sample and > 42,100 μg/ft for the type 3 2 2

sample, obviously providing no information or misleading information on the difference between

the two samples.

The wipe dust sample results from this study are quantitatively comparable to vacuum

dust sample results obtained in the EFSS for other R&R activities using stainless steel dustfall

collectors. The difference in sampling methodology (wipe versus vacuum) as well as the fact

some data values were right-censored, as discussed below, should be taken into account in any

such comparison. 

Summary statistics for the different types of settled dust samples for interior dry and wet

surface preparation are given in Table 8E-5 below. These results indicate extremely high lead

levels in dust that settles during and up to 10 hours following the activity. While dust that settles

after activity and cleanup has much lower lead levels (interior/wet methods), these levels tend to

remain over the EPA interim health-based standard of 100 μg/ft .2

Field personnel in the Massachusetts study estimated that most activity areas (rooms)

were small, approximately 10 by 10 feet or 12 by 12 feet. All tiles were placed in the center of an

activity area when possible. (Some activity areas such as hallways had different placement.) The

tile samples may roughly be considered to represent samples collected, on average, 3 feet from the

source of activity. 
8-106

Table 8E-5. Summary Statistics for the Different Types of Settled Dust Samples Collected

in the Massachusetts DOH Study for Interior Dry and Wet Surface Preparation

Method Sample N Right-Censored % < LOD (μg/ft ) (μg/ft ) (μg/ft )

Type of % Reported as Geometric Mean Minimum Maximum 2 22

Interior/ 3 33 0 7980 980 > 120,000

Dry

#1 Pre-activity 3 0 0 15.5 12.5 17.6

#2 During Activity;

Sampled 0 Hrs Post

#3 During Activity;

Sampled 10 Hrs Post 3 33 0 5960 990 > 42,100

Interior/ Sampled 10 Hrs Post

Wet

#1 Pre-activity 10 0 10 13.7 3.7 66.1

#2 During Activity;

Sampled 0 Hrs Post 10 60 0 1270 380 > 2,000

#3 During Activity; 10 50 0 1230 391 > 2,000

#4 After Activity and

Cleanup; Sampled 10 10 0 0 162 53.2 615

Hrs Post

#5 After Activity and

Cleanup; Adjacent Area 2 0 0 194 110 342

* Sample may have been contaminated as the surface preparation worker used this area to sharpen his scraper with a

grinder intermittently throughout the activity.

Note: 1. Samples reported as less than the limit of detection (LOD) were included in the analysis using one-half the LOD.

2. Samples reported as "greater than" a specified value (i.e. right-censored) were included in the analysis at the

right-censored value.
9-1

9.0 OVERALL RESULTS

Chapter 8 in this report discussed lead disturbance and exposure results specific to

individual activities and tasks monitored in the EFSS or in other studies. These results were

presented to address the three sets of data analysis objectives presented in Section 6.1:

Objective A Characterize lead disturbance and potential lead exposures

Objective B Assess factors or measurements related to lead disturbance 

Objective C Evaluate different media as indicators of lead exposure.

This chapter presents overall lead exposure and disturbance results across all activities. The

content of the chapter is related to the three sets of objectives described below.

Objective A

! key summary statistics for each activity characterizing lead exposure and disturbance,

and graphs and tables allowing for comparisons across activities

! a methodology for constructing 8-hour time-weighted average exposure for different

worker groups

! a methodology for adjusting estimates of the amount of lead deposited in settled dust to

a "standard unit" of activity

Objective B

! an assessment across activities of the observed effect of predictor variables (such as a

measure of the amount of lead in the paint) on lead disturbance and exposure

Objective C

! the extent of agreement between results collected from different media (air and settled

dust).

Observed limitations and data gaps related to addressing the above objectives with the collected

data are also presented in this chapter.

9.1 CHARACTERIZE LEAD DISTURBANCE AND POTENTIAL LEAD EXPOSURES

The type of environmental data collected in this study varied to some degree from one

R&R activity to another. All activities, however, included data on:

! personal air lead exposure monitored during the activity
9-2

! lead in settled dust disturbed by the activity and collected from stainless steel dust

collectors (SSDCs) after completion of the activity. 

These measures represent the primary raw data used in summarizing results. The personal air

monitoring results estimate airborne exposure for R&R workers performing the activity. The

dust-lead levels generated by the activity reflect the amount of lead disturbed by the activity and

distributed in the living or working environment of the occupants.

9.1.1 Personal Worker Exposures

Table 9-1 presents summary statistics characterizing the distribution of task-length average

(TLA) personal worker lead concentrations (μg/m ), or average exposure over the duration of 3

performing the activity, for all monitored target activities and generic tasks. Results presented

include the 50th, 75th and 95th percentiles of the distribution. As a measure of uncertainty, a

two-sided 95% confidence interval about each estimated percentile was calculated for each

activity. These intervals permit an assessment of whether there is a statistical difference from a

specified level (e.g., the OSHA permissible exposure limit) or a statistical difference between the

different activities. The estimates and confidence intervals are based on the assumption that the

logarithms of the air lead concentrations within each activity are normally distributed. The

components of measured variation were taken into account in the confidence interval calculations

to deal with correlations among the measures. The method of calculation of the estimates and

associated confidence intervals varies, depending upon the number of components of variation

assumed. The methods are presented in Section C.6 of Appendix C. Results for dry surface

preparation, both interior and exterior, are based on the data collection from other sources as

discussed in Section 8E of Chapter 8. All other results are based on data collected in the EFSS.

Note that paint removal by abrasive sanding is included in Table 9-1 in two forms: sanding

with a power tool and sanding by hand. Paint removal was conducted as part of the Controlled,

Experimentally-Designed (CED) phase for use as a positive control measure against which to

compare personal exposure levels from other activities, since health effects associated with paint

removal have been previously documented (as discussed in Chapter 2).

Table 9-1 presents TLAs which are not directly comparable to the eight-hour timeweighted averages (TWAs) on which OSHA exposure limits are based. Section 9.1.2 includes a

detailed discussion of the relationship between TLAs and TWAs. 

Figure 9-1 illustrates a ranking of worker personal exposure across activities based on the

75th percentile of TLAs. A pair of activities with non-overlapping confidence intervals can be

judged to have significantly different 75th percentiles.

From Figure 9-1, it appears that the activities roughly form three groups: the four activities

with the highest 75th percentiles, the five with the lowest, and the middle four. The four highest

are generally distinguishable from the five lowest, with the middle four overlapping both groups. 

The 75th percentiles for the four highest activities, along with demolition, are all significantly

above the OSHA PEL of 50 μg/m .3
9-3

Table 9-1. Estimated Percentiles and Confidence Intervals of Personal Worker Exposures

Measured by a Task Length Average for R&R Activities and Tasks

Estimated 95% Estimated 95% Estimated 95%

50th Confidence 75th Confidence 95th Confidence

Percentile Interval Percentile Interval Percentile Interval

TLA for 50th TLA for 75th TLA for 95th

(μg/m ) Percentile (μg/m ) Percentile (μg/m ) Percentile 33 3

R&R Target Activities

Carpet Removal 7.54 (1.74, 32.6) 24.9 (7.37, 208) 138 (34.0, 4680)

Window

Replacement 7.48 (1.13, 49.3) 17.5 (5.13, 488) 59.2 (16.7, 28500)

Demolition 108 (26.6 435) 185 (95.7, 5500) 403 (186, 542000)

HVAC 49.6 (11.4, 216) 56.0 (37.7, 3070) 66.6 (53.0, 588000)

Dry Surface

Preparation 58.2 (2.27, 1490) 398 (38.8, 88700) 6350 (473, 1.1x10 ) (1)

(Interior)

8

Dry Surface

Preparation 4.33 (.408, 46) 16.5 (3.81, 1930) 114 (19.2, 1.45x10 ) (1)

(Exterior)

6

Generic R&R Tasks

Door

Modification 590 (93.5, 3730) 1360 (410, 35200) 4480 (1300, 1.89x10 )6

Sawing into

Wood 546 (366, 813) 705 (518, 1300) 1020 (726, 2890)

Sawing into (11.9,

Plaster 2.40x10 ) 110 (0, 2.32x10 ) 232 681 (149, 2.15x10 ) 6 13

27

Drilling into

Wood 15.1 (4.57, 50.2) 36.3 (13.8, 214) 127 (42.9, 2490)

Drilling into

Plaster 6.76 (3.00, 15.3) 9.70 (5.71, 40.3) 16.3 (9.47, 226)

Sand - Hand 254 (23.7, 2720) 513 (150, 63800) 1410 (447, 2.03x10 )7

Sand - Power 571 (42.9, 7600) 1150 (286, 170000) 3170 (940, 5.03x10 )7

Summary of data collected from other sources. Surface preparation consisted of a wide variety (1)

of activities including wet and dry scraping, feathering of edges, and wet and dry sanding to

prepare a surface for repainting.
9-4

Figure 9-1. Ranking of R&R Activities and Tasks Based on the Estimated 75th Percentile of Worker Expos

Task Length Average
9-5

Table 9-2. The Percent of Workers Whose TLA Personal Air Lead Concentration Would

Exceed the OSHA PEL (50 μg/m ), as Estimated from the Observed 3

Distributions of TLAs in this Study

Number of Estimated Percent of 95% Confidence Interval

Workers Workers Who Will Have for the Estimated Percent

Monitored a TLA Above the OSHA of Workers Above the

(N) PEL (50 μg/m ) OSHA PEL 3

R&R Target Activities

Carpet Removal 14 14% (3% - 43%)

Window Replacement 8 7% (0% - 50%)

Demolition 20 83% (40% - 99%)

HVAC Removal 4 48% (10% - 90%)

Dry Surface Prep. (Interior) 31 52% (23% - 80%) (1)

Dry Surface Prep. (Exterior) 38 11% (0% - 49%) (1)

Generic R&R Tasks

Door Modification 6 98% (58% - 100%)

Sawing into Wood 6 99% (99% - 100%)

Sawing into Plaster 2 76% (15% - 99%)

Drilling into Wood 7 18% (4% - 51%)

Drilling into Plaster 6 0% (0% - 21%)

Sanding (Hand) 6 94% (41% - 100%)

Sanding (Power) 3 99% (48% - 100%)

Based on data from other sources. Surface preparation consisted of a wide variety of activities including wet and dry (1)

scraping, feathering of edges, and wet and dry sanding to prepare a surface for repainting.

Table 9-2 presents estimates of the percentage of workers who would exceed the OSHA

PEL of 50 μg/m if the activity were repeatedly executed under similar conditions of this study, 3

and 95% confidence intervals for this estimate, for each R&R activity and task.

9.1.2 Conversion of Task Length Averages (TLAs) into 8-Hour Time Weighted Averages

(TWAs) 

The personal worker exposure data summarized above was collected as task length

averages (TLAs) for specific R&R activities in accordance with the focus of the EFSS on

activities rather than worker groups. The advantage of reporting TLAs for a variety of R&R
75th Percentile 8&hour TWA ' (75th Percentile TLA) ( (# Hours Conducted)

8

9-6

activities is that TLAs can be used to estimate 8-hour time weighted averages (TWAs) for any of

the numerous R&R worker groups, once a profile of the activities that a worker group performs

is determined. Therefore, the EFSS has provided the components for constructing worker

exposure estimates based on profiles for a wide variety of worker groups. On the other hand, the

amount of activity being performed in a normal 8-hour workday must be taken into account when

comparing lead exposures across R&R activities or tasks, or when comparing exposures of

individual R&R activities or tasks to OSHA standards which are based on an 8-hour TWA. For

the purpose of evaluating and ranking activities, the TLA is equivalent to an 8-hour TWA only if: 

1. the task is expected to be performed for eight hours in a day 

2. the rate of exposure (μg/m ) for eight hours of activity is equal to the rate measured 3

in a shorter time period.

To further illustrate, the 75th percentile of TLA exposures for drilling into wood is estimated to

be 36 μg/m (Table 9-1). However, if this activity were only conducted for 1/4 hour in an eight- 3

hour work shift, and the exposure in the remaining 7-3/4 hours was zero, then a corresponding 8-

hour TWA calculated according to OSHA specifications would be reduced by a factor of 32,

resulting in an 8-hour TWA of approximately 1 μg/m . 3

Figure 9-2 is presented to help the reader assess the conversion of the TLA to an 8-hour

TWA for each activity. This figure presents the 75th percentile of an 8-hour TWA, expressed as

a function of the 75th percentile of the TLAs and the length of the activity or task. This

relationship is given by the following formula: 

(Note that any summary statistic of the estimated TLAs, not just the 75th percentile, could have

been used for this illustration.) This formula, as mentioned above, assumes a constant rate of

exposure during conduct of the activity, regardless of the length of the activity, as well as zero

exposure when the activity is not being conducted. This is consistent with how 8-hour TWAs are

currently calculated by OSHA. Each hypothetical 8-hour TWA in Figure 9-2 depends only on the

amount of the specified activity assumed to be conducted in an 8-hour workday. Figure 9-2

indicates that just one hour of sanding or sawing into wood (and seven hours of no exposure)

would result in the 75th percentile of 8-hour TWAs being greater than the OSHA PEL (50 μg/m )3

for those activities. On the other hand, eight hours of drilling, carpet removal, exterior surface

preparation, or window replacement would still not result in the 75th percentile of 8-hour TWAs

being greater than the OSHA PEL.
9-7

Figure 9-2. Hypothetical 8-Hour Time-Weighted Average Worker Exposures for Each Activity/Task and fo

Durations
j TLAi ( Amti

8

(705(.5) % (36.3(.25) % (17.5(6) % (0(1.25)

8 ' 58.3 μg/m3

.

9-8

Figure 9-2 demonstrates the effect of the amount of activity conducted on an 8-hour TWA

when a worker performs only one type of activity in a day that causes lead exposure. In the more

common occurrence of different activities being conducted in a single work day, an estimated 8-

hour TWA can be constructed by averaging the TLAs for each activity, where each TLA is

weighted by the duration of activity. Let TLA represent the TLA for the i activity conducted in i

th

an 8-hour work day, and Amt the time in hours for which the activity was conducted. Then the i

8-hour TWA is estimated by:

For example, suppose a certain R&R worker group typically conducts the following activities for

the specified period of time:

Activity Time Conducted

Sawing into Wood 1/2 hour

Drilling into Wood 1/4 hour

Window Replacement 6 hours

No exposure activities 1-1/4 hour

Then by Table 9-1, the 75th percentile of the 8-hour TWA for this worker group would be

estimated by:

9.1.3 Limitations of the Data and Additional Information Required for an

Exposure Assessment for Workers 

Section 4.5 of Chapter 4 presents a general discussion of the limitations of the data

collected in the EFSS from a standpoint of representativeness and completeness. In order to

conduct a more complete exposure assessment of different worker groups than what could be

performed in the EFSS, the following additional information is required: 

1. To what extent are the activities in question performed during R&R operations?

This addresses the TLA versus TWA issue discussed above. The percentage and

length of time R&R workers perform the studied activities must be characterized. In

addition, the percentage and types of R&R workers that perform each of these

activities must also be determined. 
9-9

2. How frequently are R&R operations conducted in lead-contaminated

environments? The HUD National Survey of Lead-Based Paint in Housing (U.S.

EPA, 1995) estimated that 64 million homes built before 1980 contain lead-based

paint. The issue is how frequently do different R&R worker groups work in these

residences or other lead-contaminated buildings. 

Information was collected in the WCBS data collection effort of the R&R study to address

these questions and is presented in the WCBS technical report.

9.1.4 Summary Statistics for Lead Disturbance and Potential Exposure to Occupants

The potential lead exposure to occupants resulting from a specific R&R activity or task

was characterized by estimating the average amount of lead disturbed (or deposited) by the

activity along a 6-foot line (lead gradient) emanating from the activity. For each activity, a model

of dust-lead level as a function of distance from activity was fitted to lead loading data from

SSDCs (Model (C-3) of Appendix C). The average amount of lead exposed was estimated by

determining the area under the fitted curve from 0 to 6 feet from the activity. This measure is

equivalent to estimating the average amount of lead exposed in a 6-foot by 1-foot gradient region

extending from the activity. The uncertainty associated with this estimate is assessed by

calculating an approximate 95% confidence interval. Further details on the gradient region are

presented in Chapter 6 and Section C.5 of Appendix C. In contrast to the characterization of

personal worker exposures in Table 9-1, the 75th percentile and 95th percentile of the distribution

of estimates of lead disturbed were not estimated because of the minimal number of data points

and the amount of variability in the distribution. 

For the majority of R&R activities, settled dust samples were collected from SSDCs

placed directly adjacent to the activity and at specified distances away from the activity. The

samples taken from SSDCs located directly adjacent to the activity captured the fallout of both

large debris and dust generated by an activity. Samples that were collected from SSDCs located

further away from the activity were expected to capture mostly dust and smaller airborne

particles.

For the majority of activities, the estimated 6-foot by 1-foot gradient lead loading

represents the average total amount of lead that is expected to settle in a 6-foot by 1-foot region

extending lengthwise away from the component being disturbed. However, this estimate has a

slightly different interpretation for carpet removal and demolition, as explained below.

The layout of settled dust sampling locations in the carpet removal activity only included

samples located adjacent to the surface being disturbed. This made it impossible to determine the

functional relationship between settled dust and distance. In all other activities studied, the

average lead loading decreased with increasing distance away from the activity. The most

conservative estimate of the functional relationship would assume that the amount of lead would

stay constant across the 6-foot by 1-foot region. Therefore, the (conservative) estimated average

gradient lead loading for carpet removal represents the amount of lead found in the 6-foot by

1-foot region assuming that the distribution of lead across that region is uniform.
9-10

The layout of settled dust sampling locations in the demolition activity excluded samples

adjacent to the activity (due to the large amount of debris), but did include several samples at

varying distances away from the activity. Therefore, we are able to determine the functional

relationship between settled dust and distance for the demolition activity, but this relationship

does not take into account the amount of lead that settles at a location directly adjacent to the

activity. Since the settled dust samples associated with the demolition were all located at a

distance from the activity space, the estimated 6-foot by 1-foot gradient lead loading in the

demolition activity is interpreted as being the amount of lead found in the 6-foot by 1-foot region

that was airborne in dust and smaller particles, rather than the total amount of lead disturbed.

9.1.4.1 Adjustment to a Standard Unit of Activity

The R&R activities monitored in the EFSS consisted of a number of different target

activities as well as several generic activities. In all cases, the estimate of the amount of lead

disturbed in a 6-foot by 1-foot gradient region is highly dependent on the amount of activity

conducted. In the case of the generic activities (sawing and drilling), the amount of activity was

not intended to reflect normal levels of sawing or drilling that are performed in the R&R industry. 

Rather, they were intended to provide sufficient activity to allow for estimating a TLA worker

exposure as well as the lead disturbed by the specified amount of activity. Therefore, the amount

of lead in the gradient region was adjusted to a "standard unit of activity". The standard unit of

activity selected for each studied activity does not represent an "average" amount of activity. 

Rather, the estimated amount of lead was scaled to a unit of activity that seems reasonable for a

"real world" R&R activity. Moreover, the scaling seeks to produce estimates of disturbed lead

amounts which may be readily re-scaled by the reader. For example, in the CED phase, sawing

entailed cutting 75 linear feet of surface. The chosen standard unit of activity, on the other hand,

is 1 linear foot, which may be more easily rescaled. 

The choice of the standard unit of activity for all activities except window replacement and

carpet removal is discussed in Section 8C-2.3.3 of Chapter 8 and presented in Table 9-3. The

standard unit of activity for window replacement is one window. The standard unit of activity for

carpet removal is 100 ft . Table 9-3 presents estimates of the amount of lead disturbed in the 2

gradient region for the standard unit of activity for each R&R activity except abrasive sanding and

door modification, where no standard unit of activity could be determined. Figure 9-3 depicts the

lead loading gradient for activities as conducted in the EFSS. Figure 9-4 depicts the lead loading

gradient for the standard unit of activity.

Note that the gradient lead loading for window replacement, demolition, and HVAC

removal remain unchanged between Figures 9-3 and 9-4. This is due to the fact that these

activities, as performed in the EFSS, already represented the "standard unit of activity." 

Otherwise, the chosen amount of activity has a considerable effect on estimates of the amount of

lead disturbed in the gradient region.
9-11

Figure 9-3. Estimated Distribution of Dust Lead in a 6' x 1' Gradient for Various Target

Activities and Tasks, Based on Total Amount of Activity Performed in the EFSS

Figure 9-4. Estimated Distribution of Dust Lead in a 6' x 1' Gradient for Various Target

Activities and Tasks, Based on Performing the Standard Unit of Activity
9-12

Table 9-3. Estimated Lead Amounts (μg) Distributed Within a 6' x 1' Gradient

Region, with Standard Errors and 95% Confidence Intervals, in the

EFSS

Standard Mean Lead Amount Mean Lead Amount Mean Lead Amount

Unit of (Std Error) (Std Error) (Std Error)

Activity [95% CI] [95% CI] [95% CI]

6'×1' Gradient [0-1] ft SSDC [5-6] ft SSDC

R&R Target Activities

Carpet 100 ft of

Removal* Carpet ---

2 102* 16.9

(37.2) (6.2)

[46.3, 223] [7.7, 37.1]

Window

Replacement 1 Window (20900) (13000) (217)

46300 26000 482

[17100, 125000] [8730, 75000] [179, 1300]

Demolition* 1 Room (14300) (948)

19500* 1530

[3610, 106000] [366, 6390] ---

HVAC Removal 1 Room (14100) (5700) (515)

7710 2690 414

[0, 9.09×10 ] [0, 1.24×10 ] [0, 3.1×10 ] 13 15 9

Generic R&R Tasks

Drilling into

Plaster 10 Holes (191) (163) (0.05)

207 168 0.04

[11, 3900] [8, 3680] [0.00, 2.81]

Drilling into

Wood 10 Holes (1400) (1140) (0.49)

2590 2000 1.27

[690, 9740] [497, 8030] [0.50, 3.26]

Sawing into

Plaster 1 foot (2560) (1780) (6.6)

1970 1210 10.6

[0, 3.04×10 ] [0, 1.6×10 ] [0, 29600] 10 11

Sawing into

Wood 1 foot (2230) (1300) (46)

5990 2980 105

[2300, 15600] [967, 9150] [34, 324]

* 6' x 1' gradient lead loading calculated differently as explained in text.

Figure 9-5 illustrates, for each generic R&R task, the estimated increase in lead disturbed

as a function of the amount of activity performed. The amount of activity performed is presented

as a multiplicative increase in the standard unit of activity. For example, the standard unit of

activity for drilling is specified as 10 holes. The x-axis in Figure 9-5 ranges from a multiplicative

increase of 1 (i.e., the standard unit amount of activity) through a multiplicative increase of 20. 

For drilling, this range corresponds to 10 to 200 holes. Figure 9-5 makes an assumption that the

amount of lead disturbed in the gradient region is related in a multiplicative fashion to the amount

of activity performed. 
9-13

Figure 9-5. Estimated 6' x 1' Gradient Lead Amounts as a Function of Increases in the Standard Unit of A

Generic R&R Task 
9-14

9.1.5 Estimated Effect of Clean-up on the Total Lead Disturbed 

Section 8D of Chapter 8 presents the design and results of an EFSS investigation on how

typical post-R&R activity cleanup procedures (dry broom sweeping, vacuuming with ShopVac®) contribute to reducing lead loadings in settled dust to which occupants can be exposed. 

This investigation was conducted to provide additional information on procedures that can

potentially affect lead exposures to occupants during R&R activities.

Two R&R activities (drilling, abrasive sanding) were considered in the cleanup

investigation, each conducted on wood door surfaces covered with lead-based paint. Settled dust

samples were collected at pre- and post-cleanup within each incidence of activity and cleanup.

The results indicated that both cleanup methods performed well in reducing lead loadings in the

dirtiest areas for the two activities being considered. On average, for each activity and cleanup

method, the post-cleanup lead loading was no more than one percent of the pre-cleanup lead

loading among dust deposited immediately adjacent to the activity (i.e., within one foot), where

approximately 65% of the total lead loading within six feet of the activity existed. However, the

extent of decline in lead loadings was less pronounced when the distance from the activity

approached six feet, where less dust is generated, or where some cross contamination from

cleanup closer to the activity may be taking place. Some evidence was observed that vacuum

cleanup methods may be more effective than broom sweeping in reducing lead levels at the 6-foot

distance, although any difference between pre- and post-cleanup results at the six-foot distance

was not statistically significant.

In addition to evaluating the efficacy of cleanup methods based on the percentage

reduction from pre-cleanup levels, it is also useful to examine whether levels remaining after

cleanup satisfy current clearance testing criteria. In summarizing lead loadings associated with

post-cleanup dust samples, the cleanup investigation determined that in most instances, postcleanup levels remained above EPA interim health-based standards of 100 μg/ft . This result was 2

evident throughout the six-foot region extending from the activity. 

The results of the cleanup investigation showed that cleanup methods available to most

workers can substantially reduce the lead exposures that result from R&R activities. However,

the effort put into conducting these methods can influence the extent to which any remaining lead

levels are below pre-determined clearance standards. 

9.1.6 Limitations of the Data on Lead Disturbance and Additional Information Required for

an Exposure Assessment for Occupants

Section 4.5 of Chapter 4 presents a general discussion of the limitations of the data

collected in the EFSS from a standpoint of representativeness and completeness. In order to

conduct a more complete exposure assessment for occupants, the following additional information

is required:
9-15

1. To what extent are the activities in question performed during R&R operations?

Information collected in the WCBS to address this question is discussed in the

WCBS technical report and also presented in Table 8 of the R&R Summary Report.

2. What work practices and clean-up activities are regularly employed at R&R

operations? Work practices, such as installing polyurethane sheeting to collect the

dust generated, and the extent of clean-up will determine the amount of lead

disturbed that is actually left in the occupants environment after completion of "realworld" R&R jobs. Information collected in the WCBS to address this question is

discussed in the WCBS technical report and also presented in Table 8 of the R&R

Summary Report.

3. To what degree does environmental lead contamination in a building translate

into an adverse health effect for occupants? An important question is how

environmental lead levels relate to human lead exposures. In the case of exposures

caused by an R&R activity, the additional consideration of the nature of a "transient"

exposure versus a long-term exposure will also need to be taken into account in

assessing occupant health effects.

9.2 ASSESSING FACTORS OR MEASUREMENTS RELATED TO LEAD DISTURBANCE

Two primary factors may be expected to affect lead exposure or lead disturbance resulting

from an R&R activity:

1. The amount of activity performed

2. The amount of lead contamination in the activity area.

Section 9.1 discussed ways to adjust the measurements of lead exposures and disturbances

for the amount of R&R activity that was performed. The adjustment is based on a simple

multiplicative model that implies, for example, performing twice as much activity will result in

twice as much lead disturbance. This assumed model was offered as a way of interpreting the

results pertaining to lead exposure and lead disturbance, and was not verified using data from the

study.

In contrast, the relationship between the amount of lead contamination in the activity area

and associated lead exposure and disturbance from the activity was examined in detail using data

from the study. Several statistical models were applied to data from the EFSS to investigate the

relationship between measures of lead exposure and disturbance, and different measures of lead

contamination in the activity area. The measures of lead contamination in the activity area

included pre-activity measures of lead in the following sample media: paint chip, ambient air, and

settled dust on floors, carpets, window sills and furnace ductwork. Not all sample media were

collected for each activity. In general, no strong statistical relationships with these lead

contamination measures were revealed by this investigation as indicated by Tables 8A-4, 8B-4,

and 8C-16 in Chapter 8. We attribute this lack of statistically significant results to two factors:
9-16

1. It is difficult to characterize the amount of lead contained in the component(s) being

disturbed by an activity. For example, many different lead-containing components

may be disturbed during carpet removal including; lead dust from the carpet, the

floor underneath the carpet, walls, window sills and wells, and lead paint from the

baseboard.

 2. The combination of small sample size and large variability in the measures of lead

disturbance resulted in low power to investigate this relationship.

The lack of a significant statistical relationship imposes a limitation on the interpretation of both

the worker and occupant exposure measures, in that it is not yet possible to adjust these exposure

measures for the amount of lead contained in the components being disturbed.

9.3 EVALUATING DIFFERENT MEDIA AS INDICATORS OF EXPOSURE

A strong linear relationship appears to exist between measures of airborne lead and

measures of lead in settled dust generated by the different R&R activities (as described in Chapter

8). In the carpet removal phase and the window replacement phase, positive correlation

coefficients of 0.98 and 0.94 respectively were found between settled dust measurements (1 hr.

SSDC vacuum samples located adjacent to the activity) and personal exposure measurements. In

the CED phase of the study, a correlation coefficient of 0.83 was found between personal

exposure measurements and estimated settled dust lead loadings located at six feet away from the

activity.

Despite the strong linear relationships that were found between lead in settled dust

measurements and personal exposure measurements, each individual R&R activity must be

studied in greater detail in order to evaluate the mechanism by which it can result in lead exposure

for either workers or occupants. For example, in the window replacement phase, window

replacement resulted in low levels of worker exposure and high levels of potential occupant

exposure. This phenomenon may be related to two different factors:

1. The percentage of time that the workers actually spend removing the windows (i.e.,

disturbing the lead contaminated components) in this activity is very small, while the

amount of lead disturbed by this activity is quite high.

2. The windows remained open for periods of time when the worker was not in the

room. During these periods of time, pre-activity or activity generated lead

contaminated dust may have been blown around the rooms under investigation,

resulting in the high levels of lead in settled dust. 

Caution must therefore be exercised before using airborne lead to predict occupant exposures or

lead in settled dust to predict worker exposures. 
10-1

10.0 CONCLUSIONS 

The conclusions presented in this section are based solely on the results of the EFSS

component of the R&R study. The R&R Summary Report integrates the results of the WCBS

with those of the EFSS to allow additional conclusions to be drawn concerning worker and

occupant exposures. Conclusions for the EFSS are related to three topical categories: exposure

assessment, recruitment, and sampling methodology. The major conclusions of the EFSS are

stated below.

EXPOSURE ASSESSMENT

1. The amount of lead distributed into the environment by all monitored target

activities and generic R&R tasks, with the exception of drilling into plaster and

exterior surface preparation, was substantial enough to indicate at least

occasional worker exposure above the OSHA PEL.

2. The EFSS provides exposure estimates for each studied target activity and

generic R&R task. These estimates can be combined with worker profile

information to characterize worker exposure associated with various worker

groups.

3. The EFSS provides estimates of the amount of lead disturbed and distributed in

the living or working environment of the occupants for each studied target

activity and task. These estimates can be combined with information on the types

and durations of activities conducted, the types of work practices and clean-up

activities and the link between environmental measurements and an adverse

health effect to characterize occupant exposures associated with R&R activities

and worker groups. 

RECRUITMENT

1. Recruitment of unregulated contractors for participation in a study that monitors

their "real-world" work is very problematic and must be carefully considered in

any future study design. 

SAMPLING METHODOLOGY

1. The stainless steel dustfall collector (SSDC) methodology represents a viable

alternative for measuring exposures due to a short-term activity with noted

advantages over the previous method of taking pre- and post-activity floor

samples.

2. Evidence suggests that lead disturbed by a specific activity and distributed in the

air continues to settle to the ground for a period longer than one hour.

3. It is possible that the order in which the samples are collected in side-by-side

settled dust samples affects the lead loading results. 
11-1

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David C. Cox & Associates, "Applicability of RCRA Disposal Requirements to Lead-Based

Paint Abatement WastesSDraft Report to USEPA," October 1992.
11-2

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50272-101

REPORT DOCUMENTATION 1. REPORT NO. 2. 3. Recipient's Accession No.

PAGE EPA 747-R-96-007

4. Title and Subtitle 5. Report Date

Lead Exposure Associated with Renovation and Remodeling Activities: Environmental Field May 1997 

Sampling Study Volume I: Technical Report

6.

7. Author(s) 8. Performing Organization Rept. No.

Menkedick, J.R., Menton, R.G., Constant, P., Lordo, R.A., Strauss, W.J.

9. Performing Organization Name and Address 10. Project/Task/Work Unit No.

 Battelle Memorial Institute and Midwest Research Institute

 505 King Avenue 425 Volker Boulevard

 Columbus, Ohio 43201-2693 Kansas City, Missouri 64110

 

11. Contract(C) or Grant(G) No.

(C) 68-D5-0008

(G)

12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered

 U.S. Environmental Protection Agency

 Office of Pollution Prevention and Toxics

 401 M Street, S.W.

 Washington, D.C. 20460

 Technical Report 

14.

15. Supplementary Notes

In addition to the authors listed above, the following key staff members were major contributors to the study: Halsey Boyd, David

Burgoon, Beth Burkhart, Paul Feder, Pam Hartford, Mary Kayser, Steve Naber, Nick Sasso, and Shawn Shumaker of Battelle; and Jack

Balsinger, Derrick Bradley, John Jones, and Gary Wester of MRI.

16. Abstract (Limit 200 words)

The U.S. Environmental Protection Agency, in response to the Residential Lead Based Paint Hazard Reduction Act of 1992 (Title X),

conducted a study of lead exposure associated with renovation and remodeling (R&R) activities. This report presents the results of a

literature review and one of the principle data collection efforts of the study: the Environmental Field Sampling Study (EFSS). The EFSS

collected 90 personal air samples and 556 settled dust samples to assess potential exposure to workers and occupants from selected R&R

activities. Task length average exposures measured by personal air samplers on R&R workers were greater than 100 μg/m3 for paint

removal, interior demolition, and sawing, and greater than 49 μg/m3 for interior surface preparation and central heating system

maintenance/repair. Lead loadings from stainless steel dust collectors were measured as indicators of the amount of lead disturbed and

made available by the R&R activity for exposure to occupants. With the exception of carpet removal and drilling into plaster, all activities

monitored in the EFSS deposited significant amounts of lead, ranging from 218 μg/ft2 for sawing lead-painted plaster to 42,900 μg/ft2 for

paint removal. Other exposure modifiers, as well as sampling methodology issues, are discussed in the report.

17. Document Analysis 

a. Descriptors

Lead-based paint, lead hazards, renovation and remodeling, field study, wipe and vacuum dust-lead sampling, dust-lead, personal

exposure samples, worker certification, dustfall sampling

b. Identifiers/open-ended Terms

Lead, renovation and remodeling, worker exposure, Title X, dustfall 

c. COSATI Field/Group

18. Availability Statement 19. Security Class (This Report) 21. No. of Pages

Release Unlimited

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