National Survey of Lead and Allergens in Housing 

Volume I: Analysis of Lead Hazards 

FINAL REPORT 

Revision 7.1 

October 31, 2002 

Prepared for: 

Office of Healthy Homes and Lead Hazard Control 

U.S. Department of Housing and Urban Development 

451 7th Street, N.W. 

Washington, D.C. 20410 

Project Officers: 

Warren Friedman, Ph.D., CIH 

Joey Zhou, Ph.D. 

Prepared by: 

Westat, Inc. 

1650 Research Boulevard 

Rockville, MD 20850 

Robert P. Clickner, Ph.D. 

David Marker, Ph.D. 

Susan M. Viet, Ph.D., CIH 

John Rogers 

Pamela Broene 

This work was conducted under HUD Contract Number C-OPC-21356. 

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Table of Contents 

Chapter Page

EXECUTIVE SUMMARY ................................................................................................................. ES-1 

1. INTRODUCTION .........................................................................................................1-1 

 1.1 Background........................................................................................................1-1 

 1.2 Survey Objectives...............................................................................................1-3 

 1.2.1 Technical Note on the Survey Weights....................................................1-4 

 1.3 Report Organization ...........................................................................................1-4 

2. SURVEYED HOUSING POPULATION........................................................................2-1 

3. LEAD-BASED PAINT (LBP) HAZARDS IN HOUSING ..............................................3-1 

 3.1 Definition of Significant Lead-Based Paint (LBP) Hazards..................................3-1 

 3.2 Prevalence of Significant Lead-Based Paint Hazards in Housing..........................3-2 

 3.3 Prevalence of Lead-Related Occupations or Hobbies ......................................... 3-11 

4. LEAD-BASED PAINT (LBP) IN HOUSING .................................................................4-1 

 4.1 Prevalence of Lead-Based Paint .........................................................................4-1 

 4.2 Prevalence of Deteriorated Lead-Based Paint .....................................................4-8 

 4.3 Paint Lead Loadings in Housing........................................................................ 4-10 

4.4 Comparison of Prevalence of Lead-Based Paint (LBP) 

 to the 1990 LBP Survey ............................................................................. 4-14 

 4.5 Amount of Lead-Based Paint in Housing........................................................... 4-17 

5. DUST LEAD IN HOUSING...........................................................................................5-1 

 5.1 Prevalence of Dust Lead in Housing....................................................................5-1 

 5.2 Dust Lead Loadings in Housing ..........................................................................5-3 

 5.3 Association between Interior Dust Lead Hazards and Interior LBP Condition .... 5-19 

6. RESIDENTIAL SOIL LEAD .........................................................................................6-1 

 6.1 Prevalence of Residential Soil Lead Over All Sampled Locations.........................6-1 

 6.2 Association Between Soil Lead and Exterior Paint Condition...............................6-6 

 6.3 Prevalence of Bare Soil Lead in Children’s Play Areas ........................................6-8 

 6.4 Prevalence of Bare Soil Lead in the Rest of the Yard......................................... 6-11 

 6.5 Comparison of Prevalence of Soil Lead to the 1990 LBP Survey ....................... 6-13 
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7. QUALITY OF THE NATIONAL SURVEY DATA .......................................................7-1 

 7.1 Statistical Concepts and Terminology .................................................................7-1 

 7.2 Potential for Nonresponse Bias ...........................................................................7-2 

 7.2.1 Analysis of Completion and Response Rates...........................................7-2 

7.2.2 Comparison of “Hard to-Recruit” Versus 

 “Easy-to-Recruit” HUs ....................................................................7-7 

 7.2.3 Completion Rates in the Play Area Subsample........................................7-8 

 7.3 Quality of Field Data Collection and Analysis ................................................... 7-10 

 7.3.1 Field Data Collection ........................................................................... 7-10 

 7.3.2 Laboratory Quality Control Samples .................................................... 7-13 

 7.3.3 Laboratory Selection Quality Assurance............................................... 7-14 

 7.4 Paint Testing Quality Assurance....................................................................... 7-14 

List of Appendices 

APPENDIX A SELECTED ADDITIONAL TABLES AND FIGURES .......................................... A-1 

APPENDIX B COMPARISON OF PROTOCOLS FOR THE HUD 1990 SURVEY 

 OF LEAD-BASED PAINT (LBP) AND THE HUD NATIONAL 

 SURVEY OF LEAD AND ALLERGIES IN HOUSING ................................... B-1 

APPENDIX C CORRECTING FOR CLASSIFICATION BIAS DUE TO MEASUREMENT 

 ERROR ............................................................................................................ C-1 

APPENDIX D CALCULATION OF SOIL RELATED ESTIMATES............................................. D-1 

List of Tables 

Table ES.1 Summary Estimates of Prevalence of Lead-Based Paint and Lead-Based 

 Paint Hazards ........................................................................................................ ES-2 

Table ES.2 Type of Lead-Based Paint Hazard ................................................................................ ES-3 

Table 2.1 Characteristics of the Survey Population, with Comparisons to the American 

 Housing Survey (AHS) and the Current Population Survey (CPS) .............................2-4 

Table 3.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, 

 by Selected Characteristics........................................................................................3-5 

Table 3.2 Prevalence of Significant Lead-Based Paint (LBP) Hazards by Location in 

 the Building ..............................................................................................................3-8

Table 3.3 Prevalence of Significant Lead-Based Paint (LBP) Hazards in Housing Units 

 with a Child Under 6 years of Age by Type of Hazard...............................................3-9 
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Table 3.4 Prevalence of Significant Lead-Based Paint (LBP) Hazards in Housing Units by 

 Type of Hazard and HU Age................................................................................... 3-10 

Table 3.5 Prevalence of Housing Units with Selected Lead-Related Characteristics........................ 3-12 

Table 3.6 Prevalence of Selected Lead-Related Characteristics in Homes with Significant 

 Interior LBP Hazards.................................................................................................... 3-12 

Table 4.1 Prevalence of Lead-Based Paint (LBP) by Selected Housing Unit (HU) 

 Characteristics..........................................................................................................4-4 

Table 4.2 Prevalence of Lead-Based Paint (LBP) by Location in the Building..................................4-7 

Table 4.3 Prevalence of Deteriorated and Significantly Deteriorated Lead-Based Paint 

 (LBP) by Location in the Building.............................................................................4-8 

Table 4.4 Distribution of Housing Units (HUs) with Deteriorated and Significantly 

 Deteriorated Lead-Based Paint (LBP) by Construction Year......................................4-9 

Table 4.5 Distribution of Paint Lead Loading by Location in the Building ..................................... 4-11 

Table 4.6 Distribution of Paint Lead Loading by Location in the Building and 

 Construction Year................................................................................................... 4-12 

Table 4.7 Estimated Empirical Distribution Parameters of Paint Lead Loadings by 

 Interior Component Types....................................................................................... 4-13 

Table 4.8 Estimated Empirical Distribution Parameters of Paint Lead Loadings by 

 Exterior Component Types...................................................................................... 4-13 

Table 4.9 Percentage of Components with Lead-Based Paint by Component Type 

 And HU Age........................................................................................................... 4-14 

Table 4.10 Estimated Empirical Distribution Parameters of Paint Lead Loadings by Room 

 Type....................................................................................................................... 4-14 

Table 4.11 Comparison of the Prevalence of Lead-Based Paint to the 1990 LBP Survey.................. 4-15 

Table 4.12 Amount of LBP by Painted Component ......................................................................... 4-18 

Table 5.1 Prevalence of Housing Units with a Dust Lead Hazard Somewhere in the Home...............5-2 

Table 5.2 Distribution of Maximum Dust Lead Loadings in Housing Units by Surface....................5-5 

Table 5.3 Distribution of Average Dust Lead Loadings in Housing Units by Surface .......................5-7 

Table 5.4 Distribution of Dust Lead Loading by Room and Surfaces...............................................5-9 

Table 5.5a Maximum Floor Dust Lead Loading by Year of Construction ........................................ 5-11 

Table 5.5b Maximum Window Sill Dust Lead Loading by Year of Construction ............................. 5-12 

Table 5.5c Maximum Window Trough Dust Lead Loading by Year of Construction ....................... 5-13 

Table 5.6a Maximum Floor Dust Lead Loadings by Household Income .......................................... 5-14 

Table 5.6b Maximum Window Sill Lead Dust Loadings by Household Income................................ 5-15 

Table 5.6c Maximum Window Trough Lead Dust Loadings by Household Income.......................... 5-19 

Table 5.7 Estimated Empirical Distribution Parameters of Dust Lead Loadings by 

 Surface Types......................................................................................................... 5-19 

Table 5.8 Association Between Dust Lead Hazards and Presence and Condition of 

 Interior Lead-Based Paint........................................................................................ 5-20 

Table 5.9 Association Between Floor Dust Lead Loadings and Presence of Interior 

 Lead-Based Paint.................................................................................................... 5-21 

Table 5.10 Association Between Window Sill Dust Lead Loadings and Presence of Interior 

 Lead-Based Paint.................................................................................................... 5-22

Table 6.1 Distribution of Maximum Bare Soil Sample Lead Concentrations (All Sampled 

 Locations) ................................................................................................................6-3
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Table 6.2 Distribution of Maximum Bare Soil Sample Lead Concentrations (All Sampled 

 Locations) ................................................................................................................6-4

Table 6.3 Estimated Empirical Distribution Parameters of Soil Lead Concentrations by 

 Sample Site ..............................................................................................................6-6 

Table 6.4 Association Between Bare Soil Lead Concentration and Presence of 

 Significantly Deteriorated Exterior LBP, All Sampled Locations................................6-7 

Table 6.5 Distribution of Maximum Soil Lead Concentrations in Children’s Play Areas ..................6-9 

Table 6.6 Distribution of Maximum Soil Lead Concentration in Children’s Play Areas, 

 by Construction Year.............................................................................................. 6-10 

Table 6.7 Association Between Bare Soil Lead Concentration and Presence of 

 Significantly Deteriorated Exterior LBP, in Children’s Play Areas........................... 6-11 

Table 6.8 Distribution of Maximum Bare Soil Lead Concentrations in the 

 Rest of the Yard...................................................................................................... 6-12 

Table 6.9 Distribution of Maximum Bare Soil Lead Concentrations in the Rest of the 

 Yard, by Construction Year .................................................................................... 6-13 

Table 6.10 Comparison of the Prevalence of Lead-Contaminated Bare Soil in the 

 National Survey and the 1990 LBP Survey.............................................................. 6-14 

Table 7.1 Completion Rates by 1990 Census Block Group Characteristics......................................7-6 

Table 7.2 Mean Percents for Completed and Noncompleted Housing Units by 1990 

 Census Block Group Characteristics .........................................................................7-7 

Table 7.3 Comparison of “Easy-to-Recruit” Respondents Versus “Hard-to-Recruit” 

 Respondents by Reported Housing Characteristics.....................................................7-8 

Table 7.4 Completions in Play Area Subsample ............................................................................ 7-10 

List of Figures 

Figure 3.1 Prevalence of Housing Units (HUs) with Significant LBP Hazards...................................3-4

Figure 4.1 Prevalence of Lead-Based Paint by Selected Housing Unit Characteristics .......................4-2 

Figure 4.2 Prevalence of HUs with LBP by Construction Year & Presence of Children < 6...............4-3

Figure 4.3 Prevalence of Lead-Based Paint by Location in the Building ............................................4-7 

Figure 4.4 Presence and Condition of LBP by Construction Year.................................................... 4-10 

Figure 5.1 Dust Lead Hazards by Construction Year........................................................................5-2 

Figure 5.2 Dust Lead Hazards by Household Income........................................................................5-3 

Figure 5.3 Distribution of Maximum Floor Dust Lead Loadings.......................................................5-4 

Figure 5.4 Distribution of Maximum Window Sill Dust Lead Loadings............................................5-4 

Figure 5.5 Association Between Dust Lead Loading on Floors and Window Sills............................ 5-10 

Figure 5.6 Box Plots for Dust Lead Loadings by Room.................................................................. 5-17 

Figure 5.7 Box Plots for Dust Lead Loadings by Surface ............................................................... 5-18 

Figure 5.8 Association Between Dust Lead Hazards and Condition of Interior 

 Lead-Based Paint.................................................................................................... 5-20

Figure 6.1 Distribution of Maximum Bare Soil Lead Concentrations ................................................6-2 

Figure 6.2 Box Plots for Lead in Soil Samples by Sample Site..........................................................6-5 
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Figure 6.3 Association Between Lead in Bare Soil and Significantly Deteriorated Exterior 

 Lead-Based Paint......................................................................................................6-8

Figure 6.4 Distribution of Maximum Bare Play Area Soil Lead Concentrations ................................6-9 
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EXECUTIVE SUMMARY 

The National Survey of Lead and Allergens in Housing (NSLAH) was conducted under the 

sponsorship of the Department of Housing and Urban Development (HUD) and the National Institute of 

Environmental Health Sciences (NIEHS) to assess children's potential household exposure to lead and 

allergens. The NSLAH measured the levels of lead in dust, soil, and paint, the prevalence of hazardous levels 

of lead, and levels and patterns of various indoor allergens in dust in homes. Volume I includes the findings 

for lead hazards, and describes lead levels in dust, soil, and paint in the nation’s housing by age, type, 

geographical location, and exposed populations. This Executive Summary refers to the standards of HUD’s 

“Lead Safe Housing Rule” (24 CFR 35 Subparts B-R)1

 on Federally-owned and -assisted housing with 

thresholds from the EPA "Rule: Identification of Dangerous Levels of Lead" (40 CFR Part 745)2

. 

Results: Extent of Lead-Based Paint and Lead-Based Paint Hazards in Housing 

An estimated 38 million3

 homes (40 percent of all homes) in the United States have lead-based 

paint somewhere in the building. Of these, 20 million homes have lead-based paint present on both interior 

and exterior surfaces, 9 million homes have lead-based paint only on the interior, and another 9 million homes 

have lead-based paint only on the exterior. 

Although a large number of homes have lead-based paint, most of them have relatively small 

surface areas of it. The average home with lead-based paint has an estimated 259 square feet of interior leadbased paint and 996 square feet of exterior lead-based paint. For comparison, a room 10 feet by 12 feet with 

an 8 foot ceiling has a wall area of 352 square feet. 

An estimated 24 million (26 percent) homes have significant lead-based paint hazards somewhere 

in the building or on the premises; this is consistent with earlier HUD estimates of 24 million homes.4

 Based 

on the HUD Lead Safe Housing Rule, a home is said here to have a significant lead-based paint hazard if one 

 

1

 Title 24 of the Code of Federal Regulations, Part 35 was issued September 15, 1999 in Volume 64 of the Federal Register, pages 50140-50231, and 

became effective September 15, 2000. It implemented sections 1012 and 1013 of the Residential Lead-Based Paint Hazard Reduction Act of 1992, which 

is Title X of the Housing and Community Development Act of 1992 (P.L. 102-550). A copy is available on the Internet at www.hud.gov/offices/lead. 

2

 Issued January 5, 2001 in Volume 66 of the Federal Register, pages 1206-1240, and became effective on March 6, 2001. 

3

 The 95 percent confidence intervals for the estimates are presented in the main body of the report. 

4

 President's Task Force on Environmental Health Risks and Safety Risks to Children, 2000. Eliminating Childhood Lead Poisoning: A Federal Strategy 

Targeting Lead-Based Paint Hazards (Report and Appendix). Washington, D.C.:U.S. Department of Housing and Urban Development and U.S. 

Environmental Protection Agency. 
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or more of the following conditions exists: lead-based paint with deterioration larger than de minimis levels 

specified in the Lead Safe Housing Rule,5

 dust lead loadings at or above specified thresholds on floors or 

window sills;6

 bare soil in children’s play areas above specified thresholds; or more than 9 square feet of bare 

soil in the rest of the yard with lead concentrations at or above specified thresholds.7

Of the 16.4 million homes with one or more children under age 6, an estimated 4.2 million (25 

percent) have significant lead-based paint hazards. Of all 4.8 million homes with household incomes under 

$30,000 and one or more children under age 6, an estimated 1.2 million (25 percent) have significant leadbased paint hazards. Thus, one in four homes with young children among the residents have significant leadbased paint hazards. Table ES.1 summarizes these basic estimates of the prevalence of lead-based paint and 

significant lead-based paint hazards. 

Table ES.1 Summary Estimates of Prevalence of Lead-Based Paint and Lead-Based Paint Hazards 

Housing Unit Characteristica

Number of 

Housing Units 

(millions) 

Number of 

Housing Units 

with Lead-Based 

Paint 

(millions) 

Number of 

Housing Units 

with Significant 

Lead-Based Paint 

hazards 

(millions) 

Total housing units 95.7 37.9 24.0 

One or more children under age 

6 

16.4 5.3 4.2 

One or more children under age 

6, less than $30,000/year 

household income 

4.8 1.4 1.2 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

 

5

 The de minimis levels for LBP deterioration are in Section 35.1350(d) of the Lead Safe Housing Rule. These levels are: deterioration of more than 20 

square feet (exterior) or 2 square feet (interior) of LBP on large surface area components (walls, doors) or deterioration of more than 10% of the total 

surface area of interior small surface area components types (window sills, baseboards, trim). These are the same levels used in the U.S. Environmental 

Protection Agency’s lead hazard standards rule implementing the Toxic Substance Control Act’s Section 403. 

6

 The floor and window sill dust lead loading thresholds are dust on floors with greater than or equal to 40 μg/ft2 lead and dust on window sills with greater 

than or equal to 250 μg/ft2

 lead. They are in the HUD Lead Safe Housing rule and in the EPA Rule Identification of Dangerous Levels of Lead; 40 

CFR Part 745, January 5, 2001. 

7

 The thresholds for bare, lead-contaminated soil are more than 9 square feet of bare soil with a lead concentration greater than or equal to 1,200 ppm lead, 

or 400 ppm for bare soil in an area frequented by a child under the age of 6 years. These thresholds are in the HUD Lead Safe Housing Rule. 
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Of the 24 million homes with significant lead-based paint hazards, an estimated 15 million have 

interior dust lead hazards, 14 million have deteriorated lead-based paint at or above de minimis levels and 6 

million have soil lead hazards, as displayed in Table ES.2. 

Table ES.2 Type of Lead-Based Paint Hazard 

Number of Housing Units

(millions) 

Percentage of 

Housing Units Type of Hazard a

Estimate 95% CIb Estimate 95% CI 

Significantly Deteriorated lead-based 

paint 

13.63 10.9 – 16.3 14 11-17 

Interior lead-contaminated dust 15.47 13.0 – 18.0 16 14-19 

Lead-contaminated soil 6.46 3.1 – 9.8 7 3-10 

Any lead-based paint hazard 24.03 21.3 – 26.7 25 22-28 

a All percentages are calculated with total housing units (95,688,000) as the denominator; percentages may not total 100% due to 

rounding. b

 95% CI = 95 percent confidence interval. 

Dust lead levels above the Lead Safe Housing Rule’s standards are associated with the presence 

of interior lead-based paint. An estimated 29 million homes have some interior lead-based paint, of which 39 

percent have dust lead levels above the Lead Safe Housing Rule’s standards. In contrast, only 6 percent of the 

67 million homes without interior lead-based paint have dust levels above the Lead Safe Housing Rule’s 

standards. 

Soil lead levels above the Lead Safe Housing Rule’s standards are associated with the presence 

of deteriorated exterior lead-based paint. Homes with deteriorated exterior lead-based paint above de minimis

levels are six times more likely to have soil lead hazards than are homes free of such deteriorated lead-based 

paint. 

This most recent HUD survey shows that the number of housing units with lead-based paint has 

declined from 64 million in 1990 to 38 million ten years later. On the other hand, the prevalence of homes 

with deteriorating lead-based paint increased slightly, from 19% to 22%. 

Survey Design and Methodology 

The principal lead-related purpose of the NSLAH was to develop a scientific description of the 

existing lead levels in paint, dust, and soil in the nation’s housing. Additional objectives were to obtain data to: 
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(1) estimate the number and percent of homes with dust and soil lead levels above selected thresholds; (2) 

identify sources of lead in dust in housing, e.g., paint and soil; (3) permit future analyses of lead hazard 

control strategies and costs, e.g., quantities of deteriorated painted surfaces; and (4) permit future analyses for 

regulation, policy, and guidance that minimize regulatory and program implementation burden. 

The target population included approximately 96 million homes, of the 112 million total homes in 

the nation, including single- and multi-family buildings and manufactured housing units, e.g., mobile homes 

and trailers. Homes built in all age categories were included. Vacant housing, group quarters, and hotels and 

motels were excluded for reasons of difficulties gaining cooperation. Housing where children were not 

permitted to live, e.g., elderly care facilities, were excluded because the primary interest was in children’s 

exposure to lead. Thus, 16 million units out of 112 million total units were excluded from this survey. 

The main field survey was conducted in 1998-1999, with an augmentation of the soil sampling in 

2000 to include additional play area samples. A nationally-representative sample of 1,984 homes was drawn 

from 75 clusters (each a metropolitan statistical area (MSA) or a group of counties that have a minimum 

population of 15,000) called primary sampling units (PSUs). A total of 831 eligible homes were recruited and 

completed the survey. 

Four rooms were randomly selected for environmental sample collection and testing from each of 

four room types: kitchen, common living areas, bedrooms (preferably those occupied by children), and other 

rooms. In each of these four rooms floor, window sill, and window trough dust samples were collected, 

painted surfaces were measured for lead content, and the condition of painted surfaces was assessed. Outside 

the building, soil samples were taken and exterior painted surfaces were tested. A floor dust sample was 

collected in the interior common area of multi-family buildings. 

Measurements of lead in paint were made by State- or EPA-certified lead-based paint inspectors 

using an XRF analyzer and a protocol based on HUD's 1997 Guidelines’ inspection procedure.8

 The 

instrument model used does not require making substrate corrections, nor have an inconclusive range, both of 

which involve destructive sampling of painted surfaces. One XRF reading was made per painted component 

in each room, approximately in the center of a randomly selected quadrant of the total building component 

surface area. 

 

8

 HUD 1539-LBP. Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing, Chapter 7. U.S. Department of Housing and 

Urban Development, Washington, D.C.
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Single wipe dust samples were collected by the technique described in ASTM E 1728-95.9 Floor 

dust samples were collected in the center of the largest open floor area in the room. The floor samples in the 

major entrance and interior common area were collected approximately six inches away from the center of the 

doorway. One-square-foot templates were used for floor samples. Window sill and trough samples were 

collected from a random, openable window in each selected room. The entire area was wiped for window sill 

and trough samples (up to two square feet). All dust samples were analyzed by flame atomic absorption 

spectrophotometry, using the Environmental Protection Agency’s (EPA’s) SW-846 method 3050 digestion 

method and the American Industrial Hygiene Association’s Environmental Lead Laboratory Accreditation 

Program (ELLAP) proficiency testing procedures. The laboratory that performed the analysis was NLLAP – 

recognized for dust lead analyses. 

Soil sampling was conducted in accordance with core sampling procedures described in ASTM E 

1727-95.10 Only the top one-half inch of each soil core, i.e., that portion most accessible to children, was 

included in the sample. Where necessary, grass or leaf covering was gently removed before taking the core. 

Soil samples were taken outside the building at the major entrance, and along the dripline and mid-yard area of 

two sides of the building. Soil samples were collected from children’s play areas in a subsample of 375 

homes. Soil samples were analyzed by inductively-coupled plasma atomic emission spectroscopy, using the 

SW-846 digestion method and the ELLAP proficiency testing procedures. The laboratory that performed the 

analysis was NLLAP – recognized for dust lead analyses. 

 

9

 ASTM E 1728-95. (1995b). Standard practice for the field collection of settled dust samples using wipe sampling methods for lead determination by 

atomic spectrometry techniques. American Society for Testing and Materials, West Conshohocken, PA. 

10 ASTM E 1727-95. Standard practice for the field collection of soil samples for lead determination by atomic spectrometry techniques. American 

Society for Testing Materials, West Conshohocken, PA.

1. INTRODUCTION 

The National Survey of Lead and Allergens in Housing (NSLAH) was conducted under the 

sponsorship of the Department of Housing and Urban Development (HUD) and the National Institute of 

Environmental Health Sciences (NIEHS) to assess children's potential household exposure to lead and 

allergens, i.e., to estimate the levels of lead in dust, soil, and paint, the prevalence of hazardous levels of lead, 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 1-2 October 31, 2002 

and levels and patterns of various indoor allergens (allergy-inducing substances) in dust in homes. Combining 

the goals of HUD and NIEHS into a single survey saved significant public funds, reduced the survey response 

burden on the public, and substantially reduced the time required to obtain the data needed by both agencies 

for their ongoing primary and secondary prevention activities. 

This report, Volume I, includes the findings for lead hazards, and describes lead levels in dust, 

soil, and paint in the nation’s housing by age, type, geographical location, and exposed populations. In 

addition, the report estimates the number and percent of homes with dust and soil lead levels above selected 

thresholds, especially thresholds in HUD’s Lead Safe Housing Rule (24 CFR Part 35 Subparts B-R, 

Requirements for Notification, Evaluation and Reduction of Lead-Based Paint Hazards in Federally Owned 

Residential Property and Housing Receiving Federal Assistance, effective September 15, 2000), and EPA's 

Final Rule: Identification of Dangerous Levels of Lead (40 CFR 745), effective March 6, 2001. 

1.1 Background 

Lead is a toxin that affects the central nervous system and is particularly damaging to the 

developing nervous system of young children and fetuses. High blood lead levels can result in convulsions, 

mental retardation, and even death. Research has shown that even low lead levels can have serious health 

consequences. These include reduced intelligence and short-term memory, slower reaction times, poorer handeye coordination, reduced height, hearing problems, and numerous behavioral problems.11

Although there are many sources of lead in the environment, including drinking water, food, 

emissions from gasoline combustion, and industrial emissions, it is clear that lead-based paint (LBP) plays a 

major role in high blood lead levels among children today. Research indicates that dust and soil are the most 

significant pathways for children's lead exposure, and that LBP is the major important source of household 

dust lead.12,13

The fundamental purpose of the Residential Lead-Based Paint Hazard Reduction Act of 1992, 

which is Title X of the Housing and Community Development Act of 1992 (P.L. 102-550) is prevention, i.e., 

 

11 National Academy of Sciences (1993). Measuring lead exposure in infants, children, and other sensitive populations. National Academy Press, 

Washington, DC. 

12 Bornschein, R., Hammond, P.B., Dietrich, et al. (1985a). The Cincinnati prospective study of low-level lead exposure and its effects on child 

development: Protocol and status report. Environ. Res. 38:4-18. 

13 Bornschein, R., Succop, P., Dietrich, et al. (1985b). The influence of social and environmental factors on dust lead, hand lead, and blood lead 

levels in young children. Environ. Res. 38:108-118. 
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to find and mitigate LBP hazards in homes before children are poisoned. In Sections 1051 and 1052(10), 

Congress required HUD to conduct research on risk reduction strategies from household-based lead exposure, 

and to assess the effectiveness of lead hazard evaluation activities, respectively. The NSLAH was undertaken 

to provide current information needed for regulatory and policy decisions and for assessment of the 

effectiveness of lead hazard reduction strategies, e.g., lead information disclosure during housing sale or lease 

transactions and certification of LBP professionals. 

In 1989-1990, HUD sponsored a national survey of LBP in housing (referred to as the 1990 LBP 

Survey). The primary objective of that survey was to estimate the prevalence of LBP in housing - not to 

address the presence of lead-based hazards in the housing.14 Since 1990, there have been advances in the 

understanding of the sources and pathways of lead transport and exposure, advances in the protocols for 

collecting samples of paint and dust for lead contamination, and improvements in the understanding of the 

susceptibility of children to the effects of lead exposure in the intervening years. For example, it is now 

understood that lead-contaminated house dust from LBP is most often the primary lead hazard for 

children.15,16,17 Also, HUD now recommends, and HUD and EPA require in their regulations, the use of dust 

wipe sampling as opposed to the vacuum sampling employed in the 1990 LBP Survey. In addition, the 1990 

survey data are dated because the housing stock has continued to evolve as older houses are renovated, 

repaired, and/or demolished. Thus, it may not serve as an appropriate estimate for evaluation of current LBP 

hazard reduction strategies. Finally, the 1990 LBP Survey excluded certain housing categories such as 

manufactured housing, and housing built after 1979 (i.e., after the Consumer Product Safety Commission’s 

ban on lead-containing residential paint went into effect). 

The NSLAH has updated HUD's 1990 LBP Survey and will enable an assessment of progress in 

making the U.S. housing stock lead-safe. Further, it provides current baseline information needed for 

regulatory and policy decisions and for assessment of the effectiveness of lead hazard reduction strategies 

currently under development. 

 

14 In Title X of the Housing and Community Development Act of 1992 (P.L. 102-550), the term “lead-based paint hazard” means any condition that 

causes exposure to lead from lead-contaminated dust, lead-contaminated soil, lead-contaminated paint that is deteriorated or present in accessible surfaces, 

friction surfaces, or impact surfaces that would result in adverse human health effects as established by the appropriate Federal agency. 

15 Clark, S., Bornschein, R., Succop, P., et al. (1985). Conditions and type of housing as an indicator of potential environmental lead exposure and 

pediatric blood lead levels. Environ. Res. 38, pp. 46-53. 

16 Centers for Disease Control and Prevention (1991). Preventing Lead Poisoning in Young Children. Centers for Disease Control and Prevention, U.S. 

Department of Health and Human Services, Atlanta, GA. 

17 Lanphear, B.P., et al. (1995). The Relation of Lead-Contaminated House Dust and Blood Lead Levels Among Urban Children, Final Report. Report 

to the U.S. Department of Housing and Urban Development. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 1-4 October 31, 2002 

1.2 Survey Objectives 

HUD’s principal lead-related purpose for the NSLAH was to develop a scientific description of 

the existing lead levels in dust, soil, and paint in the Nation’s housing. In addition, the survey of lead hazards 

in homes collected data to: 

i. Estimate the number and percent of homes with dust and soil lead levels above 

selected thresholds. 

ii. Identify likely sources of lead in dust in housing, e.g., paint and soil. 

iii. Permit future analyses of lead hazard control strategies and costs, e.g., quantities 

of deteriorated painted surfaces. 

iv. Permit future analyses for regulation, policy, and guidance that minimize 

regulatory and program implementation burden. 

In order to meet the survey objectives, a nationally-representative sample of 1,984 housing units 

(HUs) was drawn from 75 clusters called primary sampling units (PSUs).18 A general three-stage sample 

design was utilized to accomplish these goals as efficiently as possible. A total of 831 eligible HUs were 

recruited into the survey. In each recruited HU, samples of dust and soil were collected and painted surfaces 

were tested. (See Volume II: Design and Methodology for details on design and data collection protocols.) 

1.2.1 Technical Note on the Survey Weights and Estimation Procedure 

Paint lead measurements, dust samples, and general area soil samples were collected from all 831 

homes in the sample. In contrast, data on the presence of children’s play areas and play area soil samples 

were collected from a nationally representative statistical subsample of 375 homes in the sample. 

Consequently, two sets of survey sampling weights have been developed: one for the full sample of 831 

surveyed homes; and one for the subsample of 375 homes with play area soil lead data. The construction of 

these weights is described in Volume II. Both sets of weights are unbiased; they will both produce unbiased 

national estimates to characterize the target population of all 95.7 million occupied housing units in the U.S. 

where children are permitted to live. However, the play area subsample, being smaller, produces wider 

confidence intervals than the full sample. To minimize the impact of this fact and produce the most efficient 

 

18 A PSU is a metropolitan statistical area (MSA), county, or cluster of counties that have a minimum population of 15,000 and do not cross Census region 

boundaries. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 1-5 October 31, 2002 

possible estimates, the following procedure was adopted. Data from all 831 homes were used to estimate 

paint, dust, and non-play-area soil lead hazards; then data from the 375 home subsample were used to estimate 

the added number of homes with only play area soil lead hazards. Further details on this estimation procedure 

are provided in Appendix D. 

1.3 Report Organization 

The report for the NSLAH consists of two volumes: Volume I presents the major lead hazard 

findings. Volume II presents the survey design and methodology. 

There are seven chapters in Volume I, including this introduction. Descriptions of each chapter 

are as follows: 

 Chapter 2 describes the population surveyed and compares the survey population to 

Current Population Survey (CPS) and American Housing Survey (AHS) populations. 

 Chapter 3 presents the estimates of the prevalence of significant LBP hazards in housing, 

based on the findings presented in Chapters 4, 5, and 6 for paint, dust, and soil, 

respectively. The association between lead in each of the matrices (paint, dust, soil) is 

presented, as well as the prevalence of lead-related occupations and hobbies among 

housing residents. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 1-6 October 31, 2002 

 Chapter 4 presents the estimates of the prevalence and amount of LBP and deteriorated 

LBP in housing, including paint lead loadings in housing.19 Relevant estimates are 

compared with the findings of the 1990 LBP Survey. 

 Chapter 5 presents the estimates of the prevalence of lead-contaminated dust in housing, 

including the dust lead loadings and the association between interior dust lead and LBP 

condition. Relevant estimates are compared with the findings of the 1990 LBP Survey. 

 Chapter 6 presents the estimates of the prevalence of residential soil lead, including soil 

lead concentrations and the association between soil lead and exterior LBP condition. 

Relevant estimates are compared with the findings of the 1990 LBP Survey. 

 Chapter 7 examines the quality of the data and the resulting quality of projected national 

estimates. The chapter addresses nonresponse rates and provides a summary of field data 

collection quality control activities. Classification bias due to measurement error is 

discussed in Appendix C. 

 

19 Throughout the volume, the concepts of lead loading and lead concentration are used. Lead in paint and dust are reported as loadings (mass of lead per 

unit area of surface), while lead in soil is reported as a concentration (mass of lead per unit mass of soil). For paint, lead loading is the number of 

milligrams of lead per square centimeter of painted surface (mg/cm2

). For dust, lead loading is the number of micrograms of lead per square foot of 

wiped surface (μg/ft2

). Soil is reported as the number of micrograms of lead per gram of soil (μg/g), equivalent to parts per million (ppm). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 2-1 October 31, 2002 



2. SURVEYED HOUSING POPULATION 

The National Survey of Lead and Allergens in Housing (NSLAH) population included the 

national housing stock of permanently-occupied, noninstitutional housing units (HUs), including multi-family 

buildings and manufactured HUs, i.e., mobile homes and trailers. Homes built in all age categories in all 50 

states and the District of Columbia were included. Homes built before 1978 were included to update and 

expand upon the findings of the 1990 LBP Survey. Homes built in 1978 or after were included to verify the 

assumption that newer homes have minimal lead hazards, based on the 1978 ban of lead-based paint (LBP) for 

residential use. Vacant housing, group quarters, hotels and motels, military bases, and short-term housing 

were excluded because of difficulties gaining cooperation and are consistent with exclusions under the Lead 

Safe Housing Rule. Housing where children were not permitted to live, e.g., elderly care facilities, were 

excluded because the primary interest of the survey was in children’s exposure to lead and allergens. 

However, a home was not excluded simply because a child was not currently residing in the home at the time 

of the survey. With these exclusions, the eligible national housing stock consisted of approximately 96 million 

housing units. 

A nationally-representative sample of 1,984 HUs was drawn from 75 clusters called primary 

sampling units (PSUs).20 A total of 831 eligible HUs were recruited and completed the survey. Table 2.1 

presents the national estimates for selected characteristics of the survey population, including geographic 

region, year of construction, degree of urbanization, presence of children under age 6 and age 18, tenure, 

income, poverty, government support, race, and ethnicity.21 All estimates presented are weighted national 

estimates as discussed in Volume II. Chapter 7 and Appendix C of this volume presents an extensive 

discussion of the potential effect of nonresponse bias. 

One important measure of the representativeness of the NSLAH is to examine how the 

distributions of the housing characteristics, socioeconomic and demographic factors compare to national 

distributions. National distributions were obtained from the 1997 American Housing Survey (AHS) and the 

1998 and 1999 Current Population Surveys (CPS). The weighted percent distribution of the NSLAH sample 

 

20 A PSU is a metropolitan statistical area (MSA), county, or cluster of counties that have a minimum population of 15,000 and do not cross Census region 

boundaries. 

21 Cross comparisons of two variables, e.g., Region by Construction Year and Poverty by Urbanization, result in cells containing 30 or fewer HUs. 

Caution is recommended in the interpretation of these results. 
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WESTAT 2-2 October 31, 2002 

by race, ethnicity, income, presence of a child under 18,22 Census region, year of construction, single family 

vs. multi-family, metropolitan status, and tenure (owned vs. rented) were compared with that of the available 

AHS and CPS data.23

The 95 percent confidence intervals for the NSLAH sample estimate were found to contain the 

AHS or CPS estimate for most of the available statistics. Slight differences in estimates were observed as 

follows: 

 The 1997 AHS estimate of 35 percent of all homes being in the South is slightly 

lower than the survey estimate of 36 percent to 39 percent of all homes being in the 

South. 

 The 1997 AHS estimate of 37 percent of all homes having children under age 18 is 

slightly lower than the survey estimate of 38 percent to 39 percent of all homes. 

 The 1998 CPS estimate of 26 percent of all household incomes falling in the $0-

19,999 range is slightly higher than the survey estimate of 17 percent to 24 percent 

of all households in this income range. 

 The 1998 CPS estimate of 85 percent of all households not in poverty is slightly 

higher than the survey estimate of 77 percent to 83 percent of all households not in 

poverty. 

A few items should be noted which affect the comparability of the estimates and may explain the 

above observed differences. The first is that the target population for the National Survey excludes housing 

that excludes children, whereas the AHS and CPS estimates include such housing. Second, the cut-offs used 

for defining urbanization were not exactly the same for the NSLAH and the CPS. The NSLAH used a cut-off 

of 2,100,000 while the CPS used 2,500,000. Third, for the income and poverty comparisons, the CPS uses 

the family size and income to determine poverty status, whereas the NSLAH has used household size and 

income.24 The NSLAH estimates of any particular income class are also deflated due to the 9 percent of 

respondents whose income level is unknown. Similarly, there are 6 percent of respondents whose poverty 

status is unknown. Fourth, race and ethnicity are based on the youngest household member for the NSLAH, 

 

22 While we were most interested in children under the age of six years for lead, we were also interested in all children up to age 18 for allergen exposures. 

Comparative data from the AHS are only available for children under age 18 in the household. For the same reason, post-stratification for this survey was 

based on children under age 18. 

23 If AHS or CPS data are not listed in Table 2.1, e.g., for Government Support, they were not available in these sources. 

24 Family size includes all related people living in a housing unit. Household size includes all people living the housing unit, whether or not they are 

related to each other. Thus household size tends to be larger than family size. The 1999 CPS reports an average household size of 3.17 and an average 

family size of 2.62. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 2-3 October 31, 2002 

while the AHS bases these data on the first householder identified over the age of 18. Fifth, the most recent 

AHS available is for 1995 and 1997, thus the AHS data are slightly out of date as compared to the NSLAH. 

Finally, there is a small amount of sampling error in both the AHS and CPS estimates, and in the standard 

error estimates for all three surveys. The standard error for both AHS estimates (percent of homes in the 

south, percent of homes with children under age 18) is approximately 0.25%.25 The difference between the 

NSLAH and AHS estimates is still statistically significant for both variables. CPS standard errors are of a 

comparable magnitude to those for the AHS (similar sample sizes and designs) and also do not affect the 

statistical significance of the results. 

 

25 American Housing Survey 1997, Appendix D, http://www.census.gov/hhes/www.housing/ahs/meth.html. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 2-4 October 31, 2002 

Table 2.1 Characteristics of the National Survey Population, with Comparisons to the American 

Housing Survey (AHS) and the Current Population Survey (CPS) 

HU Characteristic National Survey Estimates HUs in 

sample 

AHS 

(1997) 

CPS 

(1998-99)c

 Estimate 

(000) 

Estimate 

(%)a

Lower 95% 

CIb (%) 

Upper 95% 

CI (%) 

 

Total Housing Unitsd 95,688 100% 831 

Region: 

Northeast 19,290 20% 19% 22% 155 20% 

Midwest 22,083 23% 22% 24% 196 24% 

South 35,474 37% 36% 39% 277 35% 

West 18,841 20% 18% 21% 203 21% 

Construction year: 

1978-1998 29,774 31% 30% 32% 220 30% 

1960-1977 27,874 29% 28% 30% 267 30% 

1940-1959 20,564 21% 20% 23% 186 20% 

Before 1940 17,476 18% 17% 20% 158 20% 

Region by 

Construction year: 

 

Northeast 19,290 20% 19% 22% 155 20% 

1978-1998 4,358 5% 3% 6% 30 3% 

1960-1977 3,754 4% 3% 5% 30 5% 

1940-1959 4,261 5% 4% 5% 36 4% 

Before 1940 6,917 7% 6% 8% 59 7% 

Midwest 22,083 23% 22% 24% 196 24% 

1978-1998 4,801 5% 4% 6% 41 6% 

1960-1977 6,283 7% 6% 7% 55 7% 

1940-1959 5,899 6% 5% 7% 47 5% 

Before 1940 5,101 5% 5% 6% 53 6% 

South 35,474 37% 36% 39% 277 35% 

1978-1998 14,447 15% 14% 17% 95 14% 

1960-1977 11,261 12% 11% 12% 96 12% 

1940-1959 6,320 7% 6% 7% 57 6% 

Before 1940 3,445 4% 3% 4% 29 4% 

West 18,841 20% 17% 21% 203 21% 

1978-1998 6,169 6% 5% 8% 54 8% 

1960-1977 6,536 7% 6% 7% 85 7% 

1940-1959 4,124 4% 3% 6% 47 4% 

Before 1940 2,013 2% 1% 3% 17 2% 

Urbanization:26 1999 

MSA equal to or above 

 2 million population 

26,814 28% 24% 32% 276 30% 

MSA below 2 million 

 Population 

45,753 48% 43% 53% 417 47% 

Non-MSA 23,121 24% 19% 30% 138 23% 

 

26 The cut-off used with survey data was actually metropolitan statistical areas (MSAs) of 2,100,000 while the available CPS cut-off is 2,500,000. This 

difference in definitions explains the slight discrepancy in the findings. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 2-5 October 31, 2002 

Table 2.1 Characteristics of the Survey Population, with Comparisons to the American Housing 

Survey (AHS) and the Current Population Survey (CPS) (continued) 

HU Characteristic National Survey Estimates HUs in 

sample 

AHS 

(1997) 

CPS 

(1998-99)3

 Estimate 

(000) 

Estimate 

(%) 

Lower 95% 

CI (%) 

Upper95% 

CI (%) 

 

One or more children 

under age 6: 

16,402 17% 15% 19% 184 17% 

Refusal/Don’t Knowe 352 5 

One or more children 

under age 18: 

36,994 39% 38% 39% 398 37% 

Refusal/Don’t Know 290 3 

Housing Unit Type: 

Single family 82,651 86% 84% 89% 705 88% 

Multi-family 13,037 14% 11% 16% 126 12% 

Tenure: 1999 

Owner-occupied 66,232 69% 65% 73% 539 67% 

Renter-occupied 29,074 30% 27% 34% 289 33% 

Refusal/Don’t Know 381 3 

Household Income 

 ($30,000): 

 1998 

Less than $30,000/year 33,830 35% 30% 41% 309 40% 

Equal to or more than 

 $30,000/year 

56,111 59% 54% 63% 482 60% 

Refusal/Don’t Know 5,747 40 

Household Income 

 ($20,000): 

 1998 

$0-19,999/year 19,359 20% 17% 24% 189 26% 

$20-39,999/year 25,855 27% 23% 31% 228 27% 

$40-59,999/year 19,316 20% 16% 25% 152 19% 

Equal to or more than 

 $60,000/year 

22,890 24% 20% 28% 203 28% 

Refusal/Don’t Know 8,268 59 

Government Support: 

Government support 4,809 5% 3% 7% 54 

No Government support 86,070 90% 88% 92% 733 

Refusal/Don’t Know 4,809 5% 44 

Poverty: 1998 

In poverty 13,221 14% 11% 16% 137 15% 

Not in poverty 76,336 80% 77% 82% 651 85% 

Refusal/Don’t Know 6,130 6% 43 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 2-6 October 31, 2002 

Table 2.1 Characteristics of the Survey Population, with Comparisons to the American Housing 

Survey (AHS) and the Current Population Survey (CPS) (continued) 

HU Characteristic National Survey Estimates HUs in 

sample 

AHS 

(1997) 

CPS 

(1998-99)3

 Estimate 

(000) 

Estimate 

(%) 

Lower 95% 

CI (%) 

Upper95% 

CI (%) 

 

Poverty by 

Urbanization: 

 

MSA equal to or above 

2 million population 

26,814 28% 24% 32% 276 

In poverty 2,962 3% 2% 4% 35 

Not in poverty 22,005 23% 19% 27% 226 

Refusal/Don’t 

Know 

1,847 2% 15 

MSA below 2 million 

population 

45,753 48% 43% 53% 417 

In poverty 6,996 7% 5% 9% 75 

Not in poverty 35,786 37% 34% 41% 323 

Refusal/Don’t 

Know 

2,971 3% 19 

Non-MSA 23,121 24% 19% 30% 138 

In poverty 3,264 3% 2% 5% 27 

Not in poverty 18,544 19% 14% 25% 102 

Refusal/Don’t 

Know 

1,313 1% 9 

Race: 

White 77,005 80% 78% 83% 622 83% 

African American 10,365 11% 9% 13% 116 12% 

Otherf 6,571 7% 5% 8% 77 6% 

Refusal/Don’t Know 1,746 2% 16 

Ethnicity: 

Hispanic/Latino 7,434 8% 6% 10% 86 9% 

Not Hispanic/Latino 87,008 91% 88% 93% 736 91% 

Refusal/Don’t Know 1,246 1% 9 

a All percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. b CI = 95% confidence interval for the estimated number or percent. c Current Population Survey (CPS) data was taken from either 1998 or 1999 CPS, as indicated by the boldface year at the top of 

each section of the column. d “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. e Refusals and “don’t know” responses by survey respondents. f “Other” race includes Asian, American Indian or Alaskan Native, Native Hawaiian or other Pacific Islander, and more than one 

race. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-1 October 31, 2002 

3. LEAD-BASED PAINT (LBP) HAZARDS IN HOUSING 

Chapter 3 presents the estimates of the prevalence of lead-based paint (LBP) hazards in housing, 

based on the findings presented in Chapters 4, 5, and 6. The associations between lead in each of the matrices 

(paint, dust, soil) are presented. In addition, the prevalence of lead-related behaviors, occupations, and 

hobbies among housing residents is presented. No comparison is made with the dust lead findings of the 1990 

LBP Survey because the concept of hazard from the earlier survey is not comparable to the definitions in use 

today. The effect of measurement error on the estimates is discussed in Appendix C. 

3.1 Definition of Significant Lead-Based Paint (LBP) Hazards

Under Title X, a LBP hazard is defined as “any condition that causes exposure to lead from leadcontaminated dust; bare, lead contaminated soil; LBP that is deteriorated; or LBP present on accessible 

surfaces, friction surfaces, or impact surfaces.” Because the data collection protocol of the NSLAH was not 

designed as a conventional risk assessment due to the statistical and operational considerations discussed 

below, this report defines significant lead-based paint (LBP) hazards based on the HUD Lead Safe Housing 

Rule (24 CFR 35.1320) and EPA Lead Hazards Identification Rule (40 CFR 745.65). If any of the following 

situations exist at any location in a home, a significant LBP hazard exists in the home under this definition: 

 Deteriorated LBP - LBP with deterioration larger than the de minimis levels per 

Section 35.1350(d) of the Lead Safe Housing rule - deterioration of more than 20 

square feet (exterior) or 2 square feet (interior) of LBP on large surface area 

components (walls, doors), or damage to more than 10% of the total surface area 

of interior small surface area components (window sills, baseboards, trim).27 LBP 

is defined as any paint or other surface coating (e.g., varnish, lacquer, or 

wallpaper over paint) that contains lead equal to or greater than 1.0 mg/cm2

); or 

 Lead-contaminated dust - Dust on floors with greater than or equal to 40 μg/ft2

lead, dust on window sills with greater than or equal to 250 μg/ft2 lead28; or 

 Lead-contaminated bare soil – More than 9 square feet of bare soil with a lead 

concentration greater than or equal to 1,200 ppm, or 400 ppm for bare soil in an 

area frequented by a child under the age of 6 years. 

 

27 Intact LBP present on accessible surfaces, friction surfaces, or impact surfaces were not included in the definition of LBP hazard for the estimates 

presented in this report because this information was not specifically collected for each component.

28 Window trough dust is not considered in the definition of a LBP hazard under the HUD Lead Safe Housing Rule. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-2 October 31, 2002 

It is important to note the distinctions between the significant LBP hazards defined here, 

and the LBP hazards as defined in the EPA Lead Hazards Identification Rule, which does not specify 

de minimis levels for deteriorated LBP and non-play area bare soils. In addition, the significant LBP 

hazards for dust and soil as used in this report, although applying the same numerical thresholds of 

the EPA Lead Hazards Identification Rule, are based on the maximum dust lead and soil lead 

measurements, while the EPA thresholds are based on the average dust lead and soil lead 

measurements. 

The NSLAH used a statistically-based sampling strategy in order to obtain statistically 

valid national estimates. The NSLAH took fewer measurements in a home than a full risk assessment 

because of the statistically-based strategy of maximizing the number of housing units tested (to yield 

the most representative national prevalence estimates with the resources available), and HUD's 

intention to minimize the burden on occupants of the housing units being tested. The subset of rooms 

and components within each home was randomly selected and evaluated in the NSLAH so that all 

work - including allergen sampling - could be completed in a 2-to-3 hour period in each home. For 

the same reasons, the survey did not assess chewable surfaces, friction surfaces, or impact surfaces 

as required for conventional risk assessments. In summary, the statistical nature, operational 

constraints, and objectives of the NSLAH required defining significant LBP hazards in the manner 

shown above. 

Under this definition, a home is described as having significant LBP hazards somewhere in the 

home if any significant LBP hazard exists at any location in the home. All tables and figures on housing units 

with significant LBP hazards in this report use this definition. 

3.2 Prevalence of Significant Lead-Based Paint Hazards in Housing 

An estimated 24 million (±3 million29) or 25 percent (±3%) of housing units in the United States 

have significant LBP hazards. Figure 3.1 presents the number of housing units with significant lead-based 

paint hazards by selected characteristics, including the presence of a resident child under six years of age, 

housing unit age30, measures of household income, race, and ethnicity. Table 3.1 presents the number and 

 

29 All confidence intervals are at the 95% level for the estimated number or percent. 

30 In the interpretation of the data by housing unit age, it is important to keep the source of the data in mind. Residents were asked the year their home was 

constructed. If a resident could not report the exact year, he/she was asked to report the construction year in ranges: 1978-1998, 1960-1977, 1946-

1959, 1940-1945, and 1939 or before. Over 40% of respondents provided the construction year of their home in this secondary manner. For the 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-3 October 31, 2002 

percentage of housing units with significant lead-based paint hazards by a much wider range of housing unit 

and household characteristics. 

Homes in Northeastern and Midwestern states are more likely to have significant LBP hazards 

than homes in Southern or Western states. An estimated 40 percent (±10%) of homes in the Northeast have 

significant LBP hazards, while the estimates are 17 percent (±4%) and 15 (±6%) percent for homes in the 

South and West, respectively. Older homes are more likely to have significant LBP hazards than newer 

homes. An estimated 8 percent (±4%) of homes built between 1960 and 1977 have significant LBP hazards, 

but the percentage increases to 43 percent (±10%) for homes built between 1940 and 1959, and to 68 percent 

(±11%) for homes built before 1940. A similar pattern of results was found for homes with children under 

age 6 categorized by age of construction. 

 purposes of the data analyses in this report, the midpoints of the ranges were assigned as the year of construction, viz., 1988, 1968, 1953, 1943, and 

1922, respectively. The year 1922 is not the midpoint of the pre-1940 range; it is the median construction year for pre-1940 housing, according to the 

1995 AHS. For these reasons, housing unit age is reported in the four ranges given in Table 3.1; finer breakdowns should be interpreted cautiously. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-4 October 31, 2002 

Figure 3.1 Prevalence of Housing Units (HUs) with Significant LBP Hazards 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

80,000

85,000

90,000

95,000

100,000

All Occupied HU's

With Children Under Age 6

Built: 1978-1998

1960-19771940-1959

Before 1940

In Poverty

Income < $30k/year

Income $30k/year or More

African American

Hispanic/Latino

Number of Housing Units (000)

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

Total Housing Units (000)

Upper 95% CI

Lower 95% CI

HU's with LBP Hazards
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-5 October 31, 2002 

Table 3.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, by 

Selected Characteristics 

HUD Lead Safe Housing Rule: Significant LBP Hazardsa

Characteristic All HUs

(000)b

No. of HUs with Significant 

LBP Hazards (000) 

Percent of HUs with 

Significant LBP Hazards 

(%)c

HUs in 

Sample

 Estimate Lower 

95% CId

Upper 

95% CI Estimate Lower 95% CI 

Upper 

95% CI 

Total Occupied HUs 95,688 24,026 21,307 26,746 25% 22% 28% 831 

Region: 

Northeast 19,290 7,679 5,748 9,611 40% 30% 50% 155 

Midwest 22,083 7,250 6,402 8,097 33% 29% 37% 196 

South 35,474 6,191 4,964 7,419 17% 14% 21% 277 

West 18,841 2,906 1,856 3,956 15% 10% 21% 203 

Construction Year: 

1978-1998 29,774 1,042 169 1,915 3% 1% 6% 220 

1960-1977 27,874 2,340 1,445 3,235 8% 5% 12% 267 

1940-1959 20,564 8,826 6,720 10,933 43% 33% 53% 186 

Before 1940 17,476 11,818 10,045 13,591 68% 57% 78% 158 

Region by Construction 

Year: 

 

Northeast 

HUs built 1978-1998 4,358 76 0 225 2% 0% 5% 30 

HUs built 1960-1977 3,794 1,478 348 2,609 39% 9% 69% 31 

HUs built 1940-1959 4,221 3,089 2,179 3,999 73% 52% 95% 35 

HUs built before 1940 6,917 5,957 5,187 6,728 86% 75% 97% 59 

Midwest 

HUs built 1978-1998 4,801 533 0 1,134 11% 0% 24% 41 

HUs built 1960-1977 6,283 1,771 872 2,670 28% 14% 42% 55 

HUs built 1940-1959 5,899 4,785 4,011 5,559 81% 68% 94% 47 

HUs built before 1940 5,101 4,658 3,888 5,429 91% 76% 100% 53 

South 

HUs built 1978-1998 14,447 1,197 0 2,436 8% 0% 17% 95 

HUs built 1960-1977 11,261 1,914 1,216 2,612 17% 11% 23% 96 

HUs built 1940-1959 6,320 3,431 2,329 4,532 54% 37% 72% 57 

HUs built before 1940 3,445 3,065 2,676 3,453 89% 78% 100% 29 

West 

HUs built 1978-1998 6,169 225 0 473 4% 0% 8% 54 

HUs built 1960-1977 6,536 1,414 816 2,011 22% 12% 31% 85 

HUs built 1940-1959 4,124 2,866 1,715 4,017 69% 42% 97% 47 

HUs built before 1940 2,013 1,437 376 2,498 71% 19% 100% 17 

Urbanization 

MSA >= 2 million 

population 

26,814 6,793 4,978 8,609 25% 19% 32% 276 

MSA =< 2 million 

population 

45,753 10,232 8,171 12,293 22% 18% 27% 417 

Non-MSA 23,121 7,001 3,848 10,153 30% 17% 44% 138 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-6 October 31, 2002 

Table 3.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, by 

Selected Characteristics (continued) 

HUD Lead Safe Housing Rule: Significant LBP Hazards1

Characteristic All HUs

(000)2

No. of HUs with Significant 

LBP Hazards (000) 

Percent of HUs with 

Significant LBP Hazards 

(%)3

HUs in 

Sample

 Estimate Lower 

95% CI4

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI 

One or More Children 

Under Age 6: 

 

All HU ages 16,402 4,155 2,948 5,363 25% 18% 33% 184 

HUs built 1978-1998 5,847 <58g - - <1g - - 56 

HUs built 1960-1977 5,098 469 0 940 9% 0% 18% 61 

HUs built 1940-1959 3,055 1,732 1,088 2,375 57% 36% 78% 40 

HUs built before 1940 2,401 1,955 1,190 2,720 81% 50% 113%h 27 

Housing Unit Type: 

Single family 82,651 21,584 18,974 24,194 26% 23% 29% 705 

Multi-family 13,037 2,442 1,208 3,676 19% 9% 28% 126 

Tenure: 

Owner-occupied 66,232 15,305 13,191 17,419 23% 20% 26% 539 

Renter-occupied 29,074 8,721 6,583 10,859 30% 23% 37% 289 

Refusal/Don’t Knowe 381 3 

Household Income: 

Less than $30,000/year 33,830 12,007 9,336 14,679 35% 28% 43% 309 

Equal to or more than 

 $30,000/year 

56,111 10,464 8,250 12,678 19% 15% 23% 482 

Refusal/Don’t Know 5,747 40 

One or More Children 

Under Age 6: 

 

All Income Categories 16,402 4,155 2,948 5,363 25% 18% 33% 184 

Less than $30,000/year 4,791 1,201 600 1,801 25% 13% 38% 61 

Equal to or more than 

 $30,000/year 

11,236 2,860 1,763 3,957 25% 16% 35% 117 

Refusal/Don’t Know 375 6 

Government Support: 

Government support 4,809 805 275 1,335 17% 6% 28% 54 

No government support 86,070 22,198 19,252 25,144 26% 22% 29% 733 

Refusal/Don’t Know 4,809 44 

Poverty: 

In Poverty 13,221 4,976 3,458 6,494 38% 26% 49% 137 

Not in Poverty 76,336 16,576 13,598 19,555 22% 18% 26% 651 

Refusal/Don’t Know 6,130 43 

Poverty by Urbanization: 

MSA equal or above 2 

 Million population 

 

In poverty 2,962 1,205 735 1,674 41% 25% 57% 35 

Not in poverty 22,005 7,758 5,957 9,559 35% 27% 43% 226 

MSA below 2 million

 Population 

 

In poverty 6,996 3,795 2,248 5,341 54% 32% 76% 75 

Not in poverty 35,786 12,455 9,722 15,188 35% 27% 42% 323 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-7 October 31, 2002 

Table 3.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, by 

Selected Characteristics (continued) 

HUD Lead Safe Housing Rule: Significant LBP Hazards1

Characteristic All HUs

(000)2

No. of HUs with Significant 

LBP Hazards (000) 

Percent of HUs with 

Significant LBP Hazards 

(%)3

HUs in 

Sample

 Estimate Lower 

95% CI4

Upper 

95% CI Estimate Lower 95% CI 

Upper 

95% CI 

Non-MSA 

In poverty 3,264 1,362 310 2,414 42% 9% 74% 27 

Not in poverty 18,544 8,684 5,071 12,297 47% 27% 66% 102 

Refusal/Don’t Know if in 

 Poverty 

6,131 43 

Race: 

White 77,005 19,089 16,475 21,703 25% 21% 28% 622 

African American 10,365 2,969 1,807 4,131 29% 17% 40% 116 

Otherf 6,571 1,496 672 2,321 23% 10% 35% 77 

Refusal/Don’t Know 1,746 16 

Ethnicity: 

Hispanic/Latino 7,434 2,399 1,235 3,564 32% 17% 48% 86 

Not Hispanic/Latino 87,008 21,196 18,674 23,719 24% 21% 27% 736 

Refusal/Don’t Know 1,246 9 a

 Significant LBP hazard as defined in text and HUD Lead Safe Housing Rule. 

b

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

c

 All percentages are calculated with the “All HUs” column in each row used as the denominator. 

d

 CI = 95% confidence interval for the estimated number or percent. 

e

 Refusals and “don’t know” responses by survey respondents. 

f

 “Other” race includes Asian, American Indian or Alaskan Native, Native Hawaiian or other Pacific Islander, and more than one 

race. 

g

 No 1978-1988 housing units with one or more children < 6 years old in this sample have lead-based paint hazards. 

h

 Upper 95% CI value > 100% reflects uncertainty in number of housing units in first data column. 

More homes with lower income occupants have significant LBP hazards than homes where 

occupants have higher incomes. An estimated 35 percent (±8%) of households with less than $30,000/year 

income have significant LBP hazards, compared with 19 percent (±4%) of households in the $30,000/year or 

above income level. 

Government-supplied housing may have fewer lead-based paint hazards than housing without 

Government support. An estimated 17 percent of Government-supported housing had significant lead-based 

paint hazards, compared to 26 percent of housing without Government support. 

Table 3.2 presents the number of homes with significant LBP hazards by location in the 

building–either interior or exterior, or both. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-8 October 31, 2002 

Table 3.2 Prevalence of Significant Lead-Based Paint (LBP) Hazards by Location in the Building 

HUD Lead Safe Housing Rule: Significant LBP Hazards 

LBP Hazard Location Number of HUsa (000) Percent of HUsb HUs in 

Sample 

Estimate Lower 

95% CIc

Upper 

95% CI Percent Lower 95% CI 

Upper 

95% CI 

Interior only 8,823 6,439 11,207 9% 7% 12% 63

Both Interior and Exterior 8,869 6,634 11,104 9% 7% 12% 99

Exterior only 6,334 4,741 7,928 7% 5% 8% 48

Anywhere 24,026 21,307 26,746 25% 22% 28% 210

No Significant LBP Hazard 71,661 68,498 74,825 75% 72% 78% 621

Total HUs 95,688 100% 831 a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. c

 CI = 95% confidence interval for the estimated number or percent. 

Table 3.3 presents data for the presence of significant LBP hazards in homes by type of hazard, 

for all homes in the National Survey’s target population and for homes with one or more children under the 

age of 6 years. The percentages for each “All HUs” row of Table 3.3 show the percent of all HUs with the 

component of significant LBP hazard, while the percentages in each “HUs w/Child Under 6” row of Table 3.3 

show the percent of all HUs with a child under age 6 with that component of significant LBP hazard. 

Table 3.4 breaks out the data in Table 3.3 for all HU’s by construction year. All three 

components of significant lead-based paint hazards show the same pattern of substantially greater prevalence 

of hazards among older housing units, especially pre-1940 homes. For all housing unit ages, soil lead hazards 

have the lowest prevalence. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-9 October 31, 2002 

Table 3.3 Prevalence of Significant Lead-Based Paint (LBP) Hazards in Housing Units with a Child 

Under 6 Years of Age by Type of Hazard 

HUD Lead Safe Housing Rule: Significant LBP Hazards 

Type of Hazard Number of HUsa

 (000) Percent of HUsb (%) 

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Significantly Deteriorated Lead 

Based Paint 

 

All HUs 13,634 10,928 16,341 14% 11% 17% 

HUs w/ Child Under 6 2,519 1,715 3,324 15% 10% 20% 

Interior Lead Dust 

All HUs 15,468 12,982 17,954 16% 14% 19% 

HUs w/ Child Under 6 2,634 1,587 3,681 16% 10% 22% 

Lead Contaminated Soil 

All HUs 6,460 3,122 9,799 7% 3% 10% 

HUs w/ Child Under 6 1,511 0 3,108 9% 0% 19% 

Any LBP Hazard 

All HUs 24,026 21,306 26,746 25% 22% 28% 

HUs w/ Child Under 6 4,155 2,948 5,363 25% 18% 33% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 Percentages are calculated with total housing units (95,688) or with housing units with a child under age 6 (16,402) as the 

denominator, as applicable.

c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-10 October 31, 2002 

Table 3.4 Prevalence of Significant Lead-Based Paint (LBP) Hazards in Housing Units by Type of 

Hazard and Housing Unit Age 

HUD Lead Safe Housing Rule: Significant LBP Hazards 

Type of Hazard Number of HUsa

 (000) Percent of HUsb (%) 

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Significantly Deteriorated Lead 

Based Paint 

Built 1978-1998 83 0 240 0% 0% 1%

Built 1960-1977 610 91 1,128 2% 0% 4%

Built 1940-1959 5,190 3,367 7,013 25% 16% 34%

Built Before 1940 7,752 6,029 9,475 44% 34% 54%

Interior Lead Dust 

Built 1978-1998 959 98 1,821 3% 0% 6%

Built 1960-1977 1,943 1,173 2,714 7% 4% 10%

Built 1940-1959 4,665 3,181 6,150 23% 15% 30%

Built Before 1940 7,735 5,982 9,489 44% 34% 54%

Lead Contaminated Soil 

Built 1978-1998 0 0 0 0% 0% 0%

Built 1960-1977 130 0 263 0% 0% 1%

Built 1940-1959 2,562 0 3,830 12% 0% 19%

Built Before 1940 3,867 254 4,741 22% 1% 27%

Any LBP Hazard 

Built 1978-1998 1,042 169 1,914 3% 1% 6%

Built 1960-1977 2,340 1,445 3,235 8% 5% 12%

Built 1940-1959 8,826 6,364 10,932 43% 31% 53%

Built Before 1940 11,818 9,688 13,591 68% 55% 78% a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. b

 Percentages are calculated with housing units built in that time period as the denominator. 

c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-11 October 31, 2002 

3.3 Prevalence of Lead-Related Occupations or Hobbies 

Table 3.5 presents the number and percent of all U.S. households in which at least one occupant 

engages in a lead-related occupation or hobby. Data for home cleanliness and clutter categories are also 

presented. Table 3.6 presents the same data for homes with significant LBP hazards. As described below, all 

of these estimates are likely to overstate the number of households that may have contributions to lead in dust 

from these behaviors. 

An estimated 24 percent (±3%) of households report that at least one occupant engages in a listed 

lead-related occupation, e.g., construction or renovation work, lead industry work, automotive repair or 

radiator work, or firing range work31. This may be elevated above the actual estimate of people who may 

bring lead home due to the fact that many people in the construction business only work with new construction 

or in projects which that do not involve disturbing LBP, dust-lead hazards or soi6l-lead hazards. Similarly, a 

person working in a lead-related industry may have an administrative position and have no lead exposure at 

all. 

An estimated 41 percent (±5%) report that at least one occupant engages in a potentially leadrelated hobby at home, e.g., making bullets or sinkers, furniture or home renovation, stained glass, pottery, or 

making jewelry.32 Among homes with significant LBP hazards, 31 percent (±8%) report that at least one 

occupant engages in a potentially lead-related hobby. These may be high estimates of the number of homes 

where lead dust is actually generated since some of these people may generally or always use lead-free 

materials in their hobbies. 

Home cleanliness has been associated with lead dust levels.33 About half of all homes were found 

to be clean (59%) and organized (43%), using the criteria in this survey. Homes with significant LBP hazards 

in their interiors were generally somewhat less clean and organized; the percentage of clean homes is 36%, 

 

31 A respondent was considered to be engaged in a lead-related occupation if they worked on any of the following activities in the previous six months: 

building demolition, paint removal (including sanding or scraping), plumbing, sandblasting, battery manufacturing or salvage work, explosive or 

ammunition work, foundry work, glass work, lead smelter work, oil refinery work, car radiator repair, making or splicing cable, work at a firing range or 

police work, welding or torch cutting, or other lead-related industry work. 

32 A respondent was counted as engaged in a potentially lead-related activity at home if they had participated in any of the following activities in the 

previous six months: make bullets or fishing sinkers, paint cars or bicycles, reload bullets, target shoot, hunt, remove paint from any part of the house, 

remove paint from furniture, sand or paint any part of the house, solder pipes or metal, solder electronic parts, use artists’ paint (jewelry, pictures), work 

with stained glass, or work with pottery or glazes. However, painting and renovation work on homes built after 1978 were excluded from these 

estimates. 

33 NCLSH (1998). Evaluation of the HUD Lead-Based Paint Hazard Control Grant Program, Fifth Interim Report, March 1998, Prepared for the U.S. 

Department of Housing and Urban Development by the National Center for Lead-Safe Housing.
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 3-12 October 31, 2002 

23% lower than the general population, and the percentage of organized homes is 28%, 15% lower than the 

general population. 

Table 3.5 Prevalence of Housing Units with Selected Lead-Related Characteristics 

Lead Related Behavior Number of HUs (000)a

 Percent of HUs (%)b HUs in 

Sample 

Estimatec Lower 

95% CId

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Lead Related Occupation 22,673 19,732 25,615 24% 21% 27% 203 

Lead Related Hobby 39,281 35,020 43,543 41% 36% 46% 347 

Cleanliness 

House Appears Clean 56,058 51,887 60,228 59% 54% 63% 462 

Some Evidence of Cleaning 25,347 21,417 29,277 26% 22% 31% 237 

No Evidence of Cleaning 9,646 7,577 11,714 10% 8% 12% 86 

Clutter 

Clutter Organized 41,158 37,650 44,666 43% 40% 46% 347 

Average Amount of Clutter 38,601 35,663 41,539 40% 37% 43% 336 

No Organization 11,045 8,859 13,231 12% 9% 14% 100 

Total HUs 95,688 831 a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. 

c

 Estimates are based on the full weighted sample. 

d

 CI = 95% confidence interval for the estimated number or percent. 

Table 3.6 Prevalence of Selected Lead-Related Characteristics in Homes with Significant Interior 

LBP Hazards

Lead Related Behavior Number of HUs (000)a

 Percent of HUs (%)b HUs in 

Sample 

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Lead Related Occupation 4,990 3,195 6,785 28% 18% 38% 45 

Lead Related Hobby 5,485 4,043 6,926 31% 23% 39% 57 

Cleanliness 

House Appears Clean 6,360 4,030 8,691 36% 23% 49% 60 

Some Evidence of Cleaning 6,757 5,221 8,294 38% 30% 47% 63 

No Evidence of Cleaning 3,258 1,646 4,870 18% 9% 28% 28 

Clutter 

Clutter Organized 5,041 3,052 7,029 28% 17% 40% 44 

Average Amount of Clutter 7,899 6,386 9,412 45% 36% 53% 77 

No Organization 3,436 1,911 4,961 19% 11% 28% 30 

Total HUs 17,692 162 a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units with significant interior LBP hazard (18,827) as the denominator. 

Percentages may not total 100% due to rounding. 

c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-1 October 31, 2002 

4. LEAD-BASED PAINT (LBP) IN HOUSING 

Chapter 4 presents estimates of the prevalence, location, and amount of lead-based paint (LBP) 

and deteriorated LBP in housing, including paint lead loadings in housing. Relevant estimates are compared 

with the findings of the 1990 LBP Survey. 

Under the HUD Lead Safe Housing Rule (24 CFR 35 Subparts B-R), LBP is defined as any 

paint or other surface coating (e.g., varnish, lacquer, or wall-paper over paint) that contains lead equal to or 

greater than 1.0 mg/cm2

. The estimates for deteriorated LBP and significantly deteriorated LBP are presented 

in Section 4.2. Under the Lead Safe Housing Rule, LBP is considered to be deteriorated if there is any 

deterioration. It is considered to be significantly deteriorated if the deterioration exceeds the de minimis

thresholds given in the definition of a significant LBP hazard presented in Chapter 3. 

4.1 Prevalence of Lead-Based Paint 

An estimated 38 million (±3 million34) or 40 percent (±4%) of housing units (HUs) in the United 

States have LBP on either the interior or exterior painted surfaces, or both. Figures 4.1 and 4.2 present the 

percentage of housing units with LBP by selected characteristics, including presence of children under age 6, 

geographic region, housing unit type, tenure, race, and year of construction35. Table 4.1 presents the number 

and percentage of housing units with LBP by a much wider range of housing unit and household 

characteristics. 

The data suggest that homes in northeastern and midwestern states are more likely to have LBP 

than homes in southern or western states. An estimated 55 percent and 53 percent of homes in the Northeast 

and Midwest have LBP, while the estimates are 27 percent and 32 percent for homes in the South and West, 

respectively. This finding can be explained by the fact that the housing stock in the Northeast and Midwest is 

older. 

 

34 All confidence intervals are at the 95% level for the estimated number or percent. 

35 In the interpretation of the data by housing unit age, it is important to keep the source of the data in mind. Residents were asked the year their home was 

constructed. If a resident could not report the exact year, he/she was asked to report the construction year in ranges: 1978-1998, 1960-1977, 1946-

1959, 1940-1945, and 1939 or before. Over 40% of respondents provided the construction year of their home in this secondary manner. For the 

purposes of the data analyses in this report, the midpoints of the ranges were assigned as the year of construction, viz., 1988, 1968, 1953, 1943, and 

1922, respectively. The year 1922 is not the midpoint of the pre-1940 range; it is the median construction year for pre-1940 housing, according to the 

1995 AHS. For these reasons, housing unit age is reported in most tables in the four ranges given in Table 3.1; finer breakdowns should be interpreted 

cautiously. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-2 October 31, 2002 

0%

10%

20%

30%

40%

50%

60%

All HU's

HU's/Kids<6

HU's/Kids<6/<$30k

Northeast

Midwest

West

South

Single Family

Multi-family

Renter-Occupied

Owner-Occupied

White

Others

Percent of HU's

Figure 4.1 Prevalence of LBP by Selected Housing Unit Characteristics 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-3 October 31, 2002 

Figure 4.2 Prevalence of HUs with LBP by Construction Year & Presence of Children <6 

As expected, older homes are more likely to have LBP than newer homes. An estimated 24 

percent (+6%) of homes built between 1960 and 1977 have LBP, but the percentage increases to 69 percent 

(+9%) for homes built between 1940 and 1959, and to 87 percent (+5%) for homes built before 1940. Table 

4.1 indicates that 5 to 8 percent of homes built after 1977 have LBP. This estimate is likely to be somewhat 

high, for two reasons. First, housing unit age is based on the residents’ reports. Some residents, especially 

renters, may have reported their homes as being newer than they actually are. There were a few homes in the 

survey in which an examination of all of the data collected from a home presented a picture that suggested that 

the home may be older than reported by the respondent. Even so, in no case was the respondent’s reported age 

overridden in the analyses. Second, most of the homes in the sample built after 1977 that had LBP had only 

one or two components measured with LBP. In approximately one-third of these homes, the substrate of the 

one painted component in the home may have interfered with the reading (these included painted metal, 

ceramic, or stone substrates which may contain lead, but paint was not scraped to measure bare substrate for 

this purpose).36

 

36 The XRF analyzer used for the study corrected for substrate interferences, but any actual lead in the substrate would be measured. 

0

10

20

30

40

50

60

70

80

90

100

All HUs Children<6

HUs (%)

<1940

1940-59

1960-77

1978-98
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-4 October 31, 2002 

Table 4.1 Prevalence of Lead-Based Paint (LBP) by Selected Housing Unit (HU) 

Characteristics 

HU Characteristic Number of HUs with LBP 

(000) 

Percent of HUs with LBP 

(%)a

HUs in 

All HUs Sample

(000) Estimate Lower 

95% CIb

Upper 

95% CI

Estimate Lower 

95% CI

Upper 

95% CI 

Total Housing Unitsc 95,688 37,897 34,521 41,272 40% 36% 43% 831 

Region: 

Northeast 19,290 10,600 8,306 12,895 55% 46% 64% 155 

Midwest 22,083 11,748 10,546 12,950 53% 48% 59% 196 

South 35,474 9,607 7,762 11,451 27% 22% 32% 277 

West 18,841 5,942 4,747 7,137 32% 25% 38% 203 

Construction Year: 

1989-1998 10,378 514 - 1,444 5% 0% 14% 61 

1978-1988 19,397 1,517 549 2,485 8% 3% 13% 159 

1960-1977 27,874 6,577 4,875 8,280 24% 18% 30% 267 

1940-1959 20,564 14,171 12,203 16,139 69% 60% 77% 186 

Before 1940 17,476 15,117 13,532 16,702 87% 82% 91% 158 

Region by Construction Year: 

Northeast 

HUs built 1978-1998 4,358 76 0 225 2% 0% 5% 30 

HUs built 1960-1977 3,794 1,478 348 2,609 39% 9% 69% 31 

HUs built 1940-1959 4,221 3,089 2,179 3,999 73% 52% 95% 35 

HUs built before 1940 6,917 5,957 5,187 6,728 86% 75% 97% 59 

Midwest 

HUs built 1978-1998 4,801 533 0 1,134 11% 0% 24% 41 

HUs built 1960-1977 6,283 1,771 872 2,670 28% 14% 42% 55 

HUs built 1940-1959 5,899 4,785 4,011 5,559 81% 68% 94% 47 

HUs built before 1940 5,101 4,658 3,888 5,429 91% 76% 100% 53 

South 

HUs built 1978-1998 14,447 1,197 0 2,436 8% 0% 17% 95 

HUs built 1960-1977 11,261 1,914 1,216 2,612 17% 11% 23% 96 

HUs built 1940-1959 6,320 3,431 2,329 4,532 54% 37% 72% 57 

HUs built before 1940 3,445 3,065 2,676 3,453 89% 78% 100% 29 

West 

HUs built 1978-1998 6,169 225 0 473 4% 0% 8% 54 

HUs built 1960-1977 6,536 1,414 816 2,011 22% 12% 31% 85 

HUs built 1940-1959 4,124 2,866 1,715 4,017 69% 42% 97% 47 

HUs built before 1940 2,013 1,437 376 2,498 71% 19% 100% 17 

Urbanization: 

MSA equal or above 2 

 million population 

26,814 9,681 7,550 11,812 36% 30% 42% 276 

MSA below 2 million 

 Population 

45,753 17,390 14,026 20,754 38% 32% 44% 417 

Non-MSA 23,121 10,826 7,458 14,193 47% 35% 59% 138 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-5 October 31, 2002 

Table 4.1 Prevalence of Lead-Based Paint (LBP) by Selected Housing Unit (HU) 

Characteristics (continued) 

HU Characteristic Number of HUs with LBP (000) Percent of HUs with LBP (%)a HUs in 

All HUs Sample

(000) Estimate Lower 

95% CIb

Upper 

95% CI 

Estimate Lower 

95% CI 

Upper 

95% CI 

One or More Children 

Under Age 6:

 

All HU Ages 16,402 5,328 4,048 6,609 32% 26% 39% 184 

HUs built 1978-1998 5,847 202 0 436 3% 0% 7% 56 

HUs built 1960-1977 5,098 876 416 1,337 17% 8% 26% 61 

HUs built 1940-1959 3,055 1,997 1,341 2,654 65% 44% 87% 40 

HUs built before 1940 2,401 2,253 1,426 3,079 94% 59% 100% 27 

Housing Unit Type: 

Single family 82,651 34,081 30,874 37,289 41% 37% 45% 705 

Multi-family 13,037 3,815 2,470 5,160 29% 20% 39% 126 

Tenure: 

Owner-occupied 66,232 25,172 22,400 27,943 38% 35% 41% 539 

Renter-occupied 29,074 12,409 9,538 15,281 43% 35% 50% 289 

Refusal/Don’t Knowd 381 3 

Household Income: 

Less than $30,000/year 33,830 15,007 11,604 18,411 44% 37% 52% 309 

Equal to or more than 

 $30,000/year 

56,111 20,815 17,745 23,885 37% 32% 42% 482 

Refusal/Don’t Know 5,747 40 

One or More Children 

Under Age 6: 

 

All Income Categories 16,402 5,328 4,048 6,609 32% 26% 39% 184 

 Less than $30,000/year 4,791 1,375 784 1,965 29% 16% 41% 61 

 Equal to or more than 

 $30,000/year 

11,236 3,820 2,579 5,061 34% 23% 45% 117 

 Refusal/Don’t Know 375 6 

Government Support: 

Government support 4,809 1,741 678 2,805 36% 16% 56% 54 

No government support 86,070 33,871 30,681 37,062 39% 36% 43% 733 

Refusal/Don’t Know 4,809 44 

Poverty by Urbanization: 

MSA equal or above 2 

 Million population 

 

In poverty 2,962 1,205 735 1,674 41% 25% 57% 35 

Not in poverty 22,005 7,758 5,957 9,559 35% 27% 43% 226 

MSA below 2 million

 Population 

 

In poverty 6,996 3,795 2,248 5,341 54% 32% 76% 75 

Not in poverty 35,786 12,455 9,722 15,188 35% 27% 42% 323 

Non-MSA 

In poverty 3,264 1,362 310 2,414 42% 9% 74% 27 

Not in poverty 18,544 8,684 5,071 12,297 47% 27% 66% 102 

Refusal/Don’t Know if in 

 Poverty 

6,131 43 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-6 October 31, 2002 

Table 4.1 Prevalence of Lead-Based Paint (LBP) by Selected Housing Unit (HU) 

Characteristics (continued) 

HU Characteristic Number of HUs with LBP (000) Percent of HUs with LBP (%)a HUs in 

All HUs Sample

(000) Estimate Lower 

95% CIb

Upper 

95% CI 

Estimate Lower 

95% CI 

Upper 

95% CI 

Race: 

White 77,005 30945 28,037 33853 40% 37% 44% 622 

African American 10,365 4,228 2,767 5,689 41% 30% 52% 116 

Othere 6,571 1,913 1,015 2,811 29% 17% 41% 77 

Unknown 1,746 16 

Ethnicity: 

Hispanic/Latino 7,434 3,329 2,044 4,614 45% 31% 59% 86 

Not Hispanic/Latino 87,008 33,830 30,436 37,223 39% 35% 42% 736 

Refusal/Don’t Know 1,246 9 

a

 All percentages are calculated with the “all HUs” on the left most column of each row as the denominator. 

b

 CI = 95% confidence interval for the estimated number or percent. 

c

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

d

 Refusals and “don’t know” responses by survey respondents. 

e

 “Other” race includes Asian, American Indian or Alaskan Native, Native Hawaiian or other Pacific Islander, and more than one 

race. 

An estimated 5.3 million (±1.3 million) or 32 percent (± 6%) of homes with children under the 

age of 6 years have lead-based paint, although children are eligible to live in all of the estimated 38 million 

homes with lead-based paint. Homes with children under age 6 showed the same relationship between HU age 

and the presence of LBP as do all homes. 

The differences among LBP prevalence by urbanization, single family versus multi-family 

housing, occupant status, household income, race, ethnicity, and poverty crossed with urbanization do not 

appear to be significant in that the confidence intervals overlap. Likewise, there were no differences in LBP 

prevalence when one or more children under age 6 was crossed by construction year. 

Figure 4.3 and Table 4.2 present the number of homes with LBP by location in the building – 

either interior or exterior, or both. About one-half of homes with lead-based paint have it on both interior and 

exterior surfaces (21% of all homes, or 53% of homes with LBP anywhere in the building). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-7 October 31, 2002 

Table 4.2 Prevalence of Lead-Based Paint (LBP) by Location in the Building 

LBP Location Number of HUsa with LBP (000) Percent of HUs with LBP (%)b HUs in 

Sample

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Interior Only 8,609 6,102 11,116 9% 6% 12% 77 

Both Interior and Exterior 20,260 17,961 22,558 21% 19% 24% 181 

Exterior Only 9,028 6,535 11,521 9% 7% 12% 80 

Subtotal – LBP anywhere 

 in Building 

37,897 34,521 41,272 40% 36% 43% 338 

No LBP in Building 57,791 54,624 60,959 60% 57% 64% 493 

Total HUs 95,688 100% 831 a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. c

 CI = 95% confidence interval for the estimated number or percent. 

Figure 4.3 Prevalence of Lead Based Paint (LBP) by Location in the Building 

Numbers of Estimated Number of Housing Units

No LBP in Building

57,791

Exterior LBP Only

9,028

Interior LBP Only

8,609

Both Interior and 

Exterior LBP

20,260
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-8 October 31, 2002 

4.2 Prevalence of Deteriorated Lead-Based Paint 

Although there are many homes with LBP, the condition of the paint is important in determining 

whether a hazard exists. Except during renovations, maintenance, or other activities that could disturb it, 

intact lead-based paint is believed to pose little immediate risk to occupants. However, significantly 

deteriorated lead-based paint may present an immediate danger to occupants, especially to young children. 

Table 4.3 presents the number and percentage of HUs with deteriorated LBP and significantly deteriorated 

LBP by location in the building - either interior or exterior, or both.

Table 4.3 Prevalence of Deteriorated and Significantly Deteriorated Lead-Based Paint (LBP) by 

Location in the Building 

Deteriorated LBP 

Location Number of HUsa

 with 

Deteriorated LBP (000) 

Percentb of HUs with 

Deteriorated LBP(%) 

HUs in 

Sample

 Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Interior Only 4,180 2,851 5,509 4% 3% 6% 39 

Both Interior and Exterior 6,236 4,661 7,811 7% 5% 8% 62 

Exterior Only 7,009 4,922 9,097 7% 5% 10% 61 

Total with Deteriorated LBP 17,425 14,816 19,735 18% 15% 21% 162 

No Deteriorated LBP 78,263 75,953 80,572 82% 79% 84% 669 

TOTAL 95,688 100% 831 

Significantly Deteriorated LBP 

Location Number of HUsa

 with Significant 

Deteriorated LBP (000) 

Percentb

 of HUs with 

Significant Deteriorated 

LBP(%) 

HUs in 

Sample

 Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI

Upper 

95% CI 

Interior Only 2,629 1,692 3,566 3% 2% 4% 28 

Both Interior and Exterior 3,487 2,132 4,842 4% 2% 5% 34 

Exterior Only 7,518 5,357 9,679 8% 6% 10% 65 

Total with Significantly 

Deteriorated LBP 

13,634 10,928 16,341 14% 11% 17% 127 

No Significantly Deteriorated LBP 82,053 79,347 84,760 86% 83% 89% 704 

TOTAL 95,688 100% 831 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 Percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. c

 CI = 95% confidence interval for the estimated number or percent. 

An estimated 17 million (±2 million) or 18 percent (±3%) of housing units in the United States 

have deteriorated LBP. The deteriorated LBP is only on the exterior for approximately 40 percent of the 

homes with deteriorated LBP. An estimated 14 million (±3 million) or 14 percent (±3%) of housing units in 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-9 October 31, 2002 

the United States have significantly deteriorated LBP. Roughly 55 percent of these homes have significant 

deterioration only on exterior surfaces. Twenty percent of these homes have the significantly deteriorated LBP 

only on interior surfaces. 

Table 4.4 presents the number and percentage of housing units with deteriorated and significantly 

deteriorated LBP by construction year. The data suggest that older homes are more likely to have deteriorated 

LBP than newer homes. Only 3% of homes built between 1960 and 1977 have deteriorated LBP, but the 

percentage increases to 32% for homes built between 1940 and 1959, and to 56% for homes built before 1940. 

Only 2% of homes built between 1960 and 1977 have significantly deteriorated LBP, but the percentage 

increases to 25% for homes built between 1940 and 1959, and to 44% for homes built before 1940. 

Table 4.4 Distribution of Housing Units (HUs) with Deteriorated and Significantly 

Deteriorated Lead-Based Paint (LBP) by Construction Year 

Deteriorated LBP 

Construction Year Total HUs 

(000)b

Number of HUs with 

Deteriorated LBP (000)

Percent of HUs with 

Deteriorated LBP (%)a

 Estimate Lower 

95% CIc 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 29,774 139 0 330 0% 0% 1% 

1960-1977 27,874 910 235 1,586 3% 1% 6% 

1940-1959 20,564 6,510 4,603 8,418 32% 22% 41% 

Before 1940 17,476 9,866 8,111 11,620 56% 46% 66% 

Total HUs 95,688 17,425 15,222 19,628 18% 16% 21% 

Significantly Deteriorated LBP 

Construction Year Total HUs 

(000)b

No. of HUs with Significantly 

Deteriorated LBP (000)

Percent of HUs with Significantly 

Deteriorated LBP (%)a

 Estimate Lower 

95% CIc 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 29,774 83 0 238 0% 0% 1% 

1960-1977 27,874 610 97 1,122 2% 0% 4% 

1940-1959 20,564 5,190 3,387 6,993 25% 16% 34% 

Before 1940 17,476 7,752 6,048 9,456 44% 35% 54% 

Total HUs 95,688 13,635 9,893 16,582 14% 10% 17% 

a

 Percentages may not total 100% due to rounding. 

b “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-10 October 31, 2002 

Figure 4.4 is a bar chart that summarizes the above survey data on deteriorated and significantly 

deteriorated LBP by construction year. It graphically displays the downward trends in the prevalence of LBP 

in homes and of damaged LBP in homes. 

Figure 4.4. Presence and Condition of LBP by Construction Year 

-

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

22,000

24,000

26,000

28,000

30,000

32,000

Before 1940 1940-1959 1960-1977 1977-1998

HU Construction Year

Number of HU's (000)

Significant Deterioration

De minimis Deterioration

Undamaged LBP

No LBP

4.3 Paint Lead Loadings in Housing 

Table 4.5 presents the distribution of the highest lead paint loading by location in the building for 

selected thresholds: 0.3, 0.6, 0.8, 1.0, 1.3, 4.0, and 10.0 mg/cm2

. By definition, paint with less than 1.0 

mg/cm2

 is not LBP; thus, the first four categories represent paint that is considered not to be LBP. The 

majority of the surfaces did not contain lead-based paint: in 70 percent of HUs the highest interior readings, 

and in 69 percent of HUs the highest exterior readings, were below 1.0 mg/cm2

. Fourteen percent of HUs had 

at least one paint sample with 10 mg/cm2

 or more of lead-based paint. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-11 October 31, 2002 

Table 4.5 Distribution of Paint Lead Loading by Location in the Building 

Maximum Paint Interior (% HUs)a

 Exterior (% HUs) Anywhere (% HUs) 

Lead Loading in 

HUc

Estimate Lower 

95% CIb

Upper 

95% CI

Estimate Lower 

95% CI 

Upper 

95% CI

Estimate Lower 

95% CI

Upper 

95% CI

GT 0 mg/cm2 100% 100% 100% 100% 100% 

GE 0.3 mg/cm2 51% 47% 55% 42% 39% 46% 62% 58% 67% 

GE 0.6 mg/cm2 37% 34% 39% 35% 32% 38% 47% 44% 50% 

GE 0.8 mg/cm2 31% 29% 34% 32% 29% 36% 42% 39% 45% 

GE 1.0 mg/cm2 30% 27% 33% 31% 27% 34% 40% 36% 43% 

GE 1.3 mg/cm2 26% 24% 29% 29% 26% 33% 36% 33% 40% 

GE 4.0 mg/cm2 17% 14% 20% 18% 15% 22% 24% 20% 27% 

GE 10.0 mg/cm2 9% 7% 12% 10% 8% 13% 14% 11% 17% 

TOTAL HUs 100% 100% 100% 

a All percentages are calculated with total housing units (95,688) as the denominator. “Housing units” include permanently 

occupied, noninstitutional housing units in which children are permitted to live. b CI = 95% confidence interval for the estimated number or percent. c GT equals “greater than.” GE equals “greater than or equal to.”

Table 4.6 presents the distribution of paint lead loadings by location in the building and 

construction year for the selected thresholds. This clearly demonstrates the effectiveness of the reduction from 

1940 to 1980 in the amount of lead added to commercial residential paint. An estimated 87 percent of housing 

reported as built before 1940 had at least one paint lead measurement somewhere in the house at 1.0 mg/cm2

, 

or above. This decreased to 24 percent of housing reported as built between 1960 and 1977, and to 7 percent 

of housing reported as built since 1978. The same pattern holds for very high lead levels, with 55 percent of 

pre-1940 homes having some lead above 10 mg/cm2

 but only 1 percent for post-1977 housing.37

 

37 It should be noted that the 1 percent of homes built in 1978-1998 with a maximum paint lead loading above 10.0 mg/cm2

 may be a result of respondent 

error in reporting the date of home construction. The year reported by the respondent was never overridden. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-12 October 31, 2002 

Table 4.6 Distribution of Paint Lead Loading by Location in the Building and Construction Year 

Percent of HUs with LBPa,b

Largest Paint Lead Loading in 

the Housing Unit Year of Construction 

 1978-1998 1960-1977 1940-1959 Before 1940 Subtotal 

Interior

GT 0 mg/cm2 100% 100% 100% 100% 100% 

GE 0.3 mg/cm2 23% 39% 77% 91% 51% 

GE 0.6 mg/cm2 9% 21% 59% 83% 37% 

GE 0.8 mg/cm2 6% 16% 48% 80% 31% 

GE 1.0 mg/cm2 4% 16% 46% 79% 30% 

GE 1.3 mg/cm2 3% 12% 41% 72% 26% 

GE 4.0 mg/cm2 1% 6% 19% 60% 17% 

GE 10.0 mg/cm2 1% 2% 7% 38% 9% 

Exterior

GT 0 mg/cm2 100% 100% 100% 100% 100% 

GE 0.3 mg/cm2 11% 31% 69% 81% 42% 

GE 0.6 mg/cm2 7% 18% 64% 76% 35% 

GE 0.8 mg/cm2 4% 16% 61% 73% 32% 

GE 1.0 mg/cm2 3% 13% 59% 72% 31% 

GE 1.3 mg/cm2 3% 11% 56% 71% 29% 

GE 4.0 mg/cm2 0% 6% 28% 56% 18% 

GE 10.0 mg/cm2 0% 2% 10% 41% 10% 

Anywhere in Building

GT 0 mg/cm2 100% 100% 100% 100% 100% 

GE 0.3 mg/cm2 30% 57% 89% 95% 62% 

GE 0.6 mg/cm2 15% 31% 80% 89% 47% 

GE 0.8 mg/cm2 10% 26% 70% 88% 42% 

GE 1.0 mg/cm2 7% 24% 69% 87% 40% 

GE 1.3 mg/cm2 5% 18% 65% 84% 36% 

GE 4.0 mg/cm2 1% 10% 34% 73% 24% 

GE 10.0 mg/cm2 1% 3% 14% 55% 14% a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live.

b GT equals “greater than.” GE equals “greater than or equal to.”

Tables 4.7 and 4.8 present selected parameters of the distributions of paint lead loadings by 

interior and exterior component types. Tables 4.7 and 4.8 do not include the geometric means and standard 

deviations because of the large number of zero XRF readings. All of the distributions in Tables 4.7 and 4.8 

are right-skewed and cannot be fitted by normal distributions. A better model would be the lognormal 

distribution. Appendix C presents a discussion of fitting models to these data. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-13 October 31, 2002 

Table 4.7 Estimated Empirical Distribution Parameters of Paint Lead Loadings by Interior 

Component Types 

Walls, Floors, 

Ceilings Windows Doors Trim Other 

mg/cm2 mg/cm2 mg/cm2 mg/cm2 mg/cm2

Arithmetic Mean 0.2 0.9 0.5 0.5 0.4 

Arithmetic Standard Deviation 1.5 3.4 2.5 2.3 2.6 

25th Percentile 0.0 0.0 0.0 0.0 0.0 

Median 0.0 0.0 0.0 0.0 0.0 

75th Percentile 0.0 0.1 0.0 0.0 0.0 

90th Percentile 0.1 1.3 0.4 0.2 0.2 

95th Percentile 0.3 6.0 1.9 1.4 0.5 

Number of Readings 14,876 5,513 4,596 2,578 2,686 

Table 4.8 Estimated Empirical Distribution Parameters of Paint Lead Loadings by Exterior 

Component Types 

Walls Windows Doors Trim Porch Other 

mg/cm2

 mg/cm2 mg/cm2 mg/cm2 mg/cm2 mg/cm2

Arithmetic Mean 0.9 2.5 1.2 1.1 1.1 1.6 

Arithmetic Standard Deviation 3.4 6.2 4.4 4.5 3.9 5.1 

25th Percentile 0.0 0.0 0.0 0.0 0.0 0.0 

Median 0.0 0.0 0.0 0.0 0.0 0.0 

75th Percentile 0.1 1.7 0.1 0.1 0.1 0.3 

90th Percentile 1.9 7.7 2.4 1.8 2.2 3.3 

95th Percentile 4.8 15.3 7.4 5.4 7.8 10.7 

Number of Readings 2,008 781 1,398 446 698 250 

Table 4.9 summarizes the data on LBP by component type from a different perspective; it 

presents the percentage of components with LBP by component type and housing unit age. Table 4.9 shows 

the expected trends and differences: exterior components are more likely to be leaded than interior 

components; interior walls are least likely to have LBP; and older homes have more LBP than newer homes. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-14 October 31, 2002 

Table 4.9 Percentage of Components with Lead-Based Paint by Component Type and HU Age 

Component Type Year of Construction 

 All Years 1978-1998 1960-1977 1940-1959 Before 1940

Interior Walls, Floors Ceilings 2% 0% 1% 2% 7% 

 Windows 9% 1% 2% 6% 21% 

 Doors 7% 0% 1% 7% 22% 

 Trim 5% 0% 2% 4% 15% 

 Other 4% 0% 1% 2% 12% 

 All Components 30% 4% 16% 46% 79% 

Exterior Walls 14% 0% 9% 18% 34% 

 Windows 25% 0% 12% 30% 41% 

 Doors 15% 2% 5% 29% 33% 

 Trim 11% 3% 8% 16% 24% 

 Porch 15% 1% 7% 25% 28% 

 Other 18% 0% 8% 37% 37% 

 All Components 31% 3% 13% 59% 72% 

Table 4.10 presents selected parameters of the distributions of paint lead loading by interior 

rooms and for all exterior surfaces. Paint lead loadings are higher on exterior surfaces than on interior 

surfaces. Differences between average paint lead loadings in interior rooms are small compared to differences 

between component types within rooms (see Table 4.7). 

Table 4.10 Estimated Empirical Distribution Parameters of Paint Lead Loadings by Room Type 

Kitchen Living 

Room 

Bed Room Other 

Room 

Exterior 

mg/cm2

 mg/cm2 mg/cm2 mg/cm2 mg/cm2

Arithmetic Mean 0.5 0.4 0.4 0.4 1.3 

Arithmetic Standard Deviation 2.3 2.3 2.3 2.3 4.4 

25th Percentile 0 0 0 0 0 

Median 0 0 0 0 0 

75th Percentile 0.1 0 0 0 0.2 

90th Percentile 0.4 0.2 0.2 0.2 2.7 

95th Percentile 1.7 0.8 1 0.8 7.8 

Number of Readings 7127 7375 8053 7387 5581 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-15 October 31, 2002 

4.4 Comparison of Prevalence of Lead-Based Paint (LBP) to the 1990 LBP Survey 

Table 4.11 compares the prevalence of LBP and deteriorated LBP found in the NSLAH 

(restricted to pre-1980 construction) with the prevalence found in the 1990 LBP Survey, which was similarly 

restricted38. The NSLAH shows fewer total homes built before 1980. This is partly due to the fact that 

housing where children could not live was excluded from the current survey. There has also been a loss of 

homes built before 1980 due to demolition. 

 

Table 4.11 Comparison of the Prevalence of Lead-Based Paint1

 to the 1990 LBP Survey 

1990 LBP Survey Current NSLAH 

(Pre-1980 HUs) 

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent 

(%) 

Total HUs Built Before 1980 77,177 100% 68,756 100% 

 HUs with LBP 64,059 83% 34,195 50% 

 Interior LBP 48,986 63% 26,184 38% 

 Exterior LBP 56,495 73% 27,373 40% 

HUs with Deteriorated LBPa 14,354 19% 14,962 22% 

 Interior Deteriorated LBP 5,596 7% 7,281 11% 

 Exterior Deteriorated LBP 9,657 13% 11,784 17% 

a Deteriorated LBP is defined in the 1995 HUD Guidelines (Guidelines for the Evaluation and Control of Lead-Based 

Paint Hazards in Housing, HUD 1539-LBP, Washington, D.C.) for the NSLAH, and as 5 square feet or more of 

deteriorated LBP for the 1990 survey. 

A lower percentage of pre-1980 homes were found with LBP during the current NSLAH (50% 

versus 83% found in 1990). This was not unexpected because there has been renovation, remodeling, 

demolition, and paint removal activities in the intervening years. 

The number of homes with LBP was expected to decrease between 1990 and 1999, primarily due 

to demolition, renovation and remodeling of older homes. For homes built around the same time, the 

percentage of homes with LBP was also expected to decrease between 1990 and 1999, primarily due to 

renovation and remodeling of older homes. However, the difference between the 1990 and 1999 survey 

estimates of the number and percentage of homes with LBP is greater than might be expected from these 

sources. Factors that might explain the differences include: 

 Demolition. Demolition of older homes reduces the number of homes with LBP 

over time. 

 

38 A comparison of the protocols for the two surveys is presented in Appendix B. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-16 October 31, 2002 

 Renovation, Remodeling, and Remediation. Removal of surfaces with LBP 

during renovation and remodeling reduces both the number and percentage of homes 

with LBP. Covering (encapsulating) surfaces with LBP reduces the quantity of lead 

directly accessible to occupants and reduces the XRF reading on the surface. The 

lower XRF readings result in fewer homes classified as having LBP. Although 

additional coats of paint are expected to reduce XRF readings, the effect of painting 

is expected to be small. 

 XRF Models. XRF measurements from the 1999 survey are more precise than 

those from the 1990 survey. The less precise XRF instrument used in the 1990 

survey was more likely to misclassify a surface as having LBP and thus increases the 

estimated number of surfaces with LBP. 

 XRF Calibration Procedures. The calibration of the XRF instrument used for the 

1990 survey was checked at paint loadings of 0.6 and 3.0 mg lead per sq.cm. The 

1990 XRF readings were recalibrated based on these checks. The calibration of the 

XRF instrument used for the 1999 survey was checked at paint loadings of 0.0 and 

1.0 mg lead per sq.cm. The difference in the calibration procedures and the 

assumptions required for the re-calibration of the 1990 XRF readings have an 

unknown effect of the estimated number of homes with LBP. 

 Sample Design. The two surveys used slightly different criteria and sampling 

methods for selecting the sampled homes. The primary difference being that the 

1999 survey excluded homes where children were excluded, some of which may 

have been included in the 1990 survey. 

 Within-home Data Collection Procedures. The two surveys had different criteria 

and procedures for within-home data collection. The 1999 survey collected 

measurements in more rooms within the sampled homes than the 1990 survey (4 to 6 

rooms vs. 2 rooms). Within the sampled rooms the 1999 survey also collected more 

measurements. The larger number of measurements in the 1999 survey would tend 

to increase the number of homes classified as having LBP, other factors being equal, 

contrary to the observed decrease. 

Approximately the same percentage of pre-1980 homes with LBP had deteriorated LBP in both 

surveys (22% versus 19% found in 1990). The slight increase in the percentage of homes with deteriorated 

LBP was expected, because these homes are now nine years older. In addition, the definitions of deteriorated 

LBP were different for the two studies. In the 1990 LBP Survey, deteriorated interior LBP was defined as 

more than 5 square feet of deteriorated interior lead-based paint, with a similar definition for exterior leadbased paint. Table 4.11 defines deteriorated LBP for the NSLAH according to the 1995 Guidelines

(Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing). For these reasons, 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-17 October 31, 2002 

Table 4.11 does not attempt to present comparisons with respect to significantly deteriorated LBP; the 

concepts of deterioration above de minimis levels were different in 1990 and 1999. 

4.5 Area of Lead-Based Paint in Housing 

Table 4.12 presents estimates of the areas of surfaces with LBP by architectural component type. 

An estimated 7.4 billion square feet of painted interior surfaces are covered with LBP. This represents 2 

percent of the area of painted interior surfaces in all homes. Although 2 percent of paint on walls, floors, and 

ceilings is lead-based, the area of these LBP-coated components accounts for 67 percent of all interior 

surfaces with LBP. Conversely, paint on window and door system components is more likely to contain LBP, 

but the total surface area of LBP on these components is only 21 percent of the area of all interior painted 

surfaces. 

An estimated 29.2 billion square feet of painted exterior surfaces are covered with LBP. This 

represents 22 percent of the area of painted exterior surfaces in all homes. Wall siding accounts for most 

(67%) of the surface area of LBP. 

Although a large number of homes have LBP, most of them have relatively small areas of LBP. 

The average home with LBP has 259 square feet of interior LBP and 996 square feet of exterior LBP. 39

 

39 For comparison, a room 10 feet by 12 feet with an 8 foot ceiling has a wall area of 352 square feet and a combined wall, ceiling and floor area of 592 

square feet. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 4-18 October 31, 2002 

Table 4.12 Area of LBP by Painted Component 

Component National Total Amount of LBP Average Amount LBP Per 

Housing Unit with LBP 

 Millions of sq. ft. Percent of All Paint 

on Component 

(square feet) 

INTERIOR: 

Wall, Floor, Ceiling 4,993 2% 173 

Window 687 9% 24 

Door 911 6% 32 

Trim 499 5% 17 

Cabinets, Chimney, Beams 388 2% 13 

TOTAL 7,448 2% 259 

EXTERIOR: 

Wall 26,706 18% 912 

Window 365 28% 12 

Door 446 14% 15 

Trim 556 12% 19 

Porch 1,086 21% 37 

TOTAL 29,159 22% 996 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-1 October 31, 2002 

5. DUST LEAD IN HOUSING 

Chapter 5 presents estimates of the prevalence of lead-contaminated dust in housing, including 

the dust lead loadings and the association between interior dust lead and exterior LBP condition. No 

comparison is made with the dust lead findings of the 1990 LBP Survey because the vacuum technique 

employed in the earlier study is not comparable to the wipe technique used in the NSLAH. 

5.1 Prevalence of Dust Lead in Housing 

Table 5.1 presents the prevalence of all homes and homes with one or more children under 6 

years of age with a dust lead hazard somewhere in the home,40 as defined by the HUD Lead Safe Housing Rule 

(24 CFR 35 Subparts B-R). The HUD Lead Safe Housing Rule defines a dust lead hazard as greater than or 

equal to 40 μg/ft2

 lead on floors or 250 μg/ft2 lead on window sills. There is no longer a hazard level defined 

for dust lead on window troughs. The earlier HUD 1995 Guidelines considered lead in dust to be a hazard 

when dust on floors had greater than 100 μg/ft2

 lead, dust on window sills had greater than 500 μg/ft2 lead, or 

dust on window troughs had greater than 800 μg/ft2

 lead. As discussed in Section 3.1 a housing unit is 

considered to have a dust lead hazard if a dust lead hazard exists at any of the sampled locations in the 

housing unit. In contrast, the EPA Lead Hazards Identification Rule considers a housing unit to have a dust 

lead hazard if the average of the samples exceeds the relevant 

Using the HUD Lead Safe Housing Rule definition of dust lead hazard, an estimated 16 percent 

(+2%41) of all homes have a dust lead hazard somewhere in the home, and 3 percent (+1%) of all homes have 

both a child under 6 years of age and a dust lead hazard. 

Figures 5.1 and 5.2 present the percentage of homes with dust lead hazards by surface – floor 

and window sill – and by housing unit age and household income. The expected gradient with housing unit 

age is seen in Figure 5.1. Both figures show that window sills have the greater prevalence of dust lead 

hazards. 

 

40 The maximum lead dust loading on any surface tested (floor, window sill, and window trough) in the home was used to determine whether a dust lead 

hazard existed. 

41 All confidence intervals are at the 95 percent level for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-2 October 31, 2002 

Table 5.1 Prevalence of Housing Units with a Dust Lead Hazard Somewhere in the Home 

HU Categorya Number of HUs (000) Percent of HUs(%)b

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

HUs with Lead Dust Hazard 15,468 12,982 17,954 16% 14% 19% 

HUs with Children Under 6 

Years and Lead Dust Hazard 

2,634 1,586 3,682 16% 11% 20% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) or HUs with resident children under age 6 (16,402) as the 

denominator. c

 CI = 95% confidence interval for the estimated number or percent. 

Figure 5.1 Dust Lead Hazards by Construction Year 

0

5

10

15

20

25

30

35

40

45

Floor Window Sill

HUs (%)

Average

<1940

1940-59

1960-77

1978-98
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-3 October 31, 2002 

Figure 5.2 Dust Lead Hazards by Household Income 

5.2 Dust Lead Loadings in Housing 

Figures 5.3 and 5.4 present the distribution of maximum (within housing unit) dust lead loadings 

on floors and window as histograms. Tables 5.2 and 5.3 present information on maximum and average dust 

loadings, respectively, by surface. 

Table 5.2 presents the distribution of maximum dust lead loadings by surface (floor, window sill, 

and window trough) for all U.S. homes in the target population, for selected threshold values. As with Table 

5.1, the estimates are based on the maximum dust lead loading in the home for the particular surface. 

Only an estimated 6 percent of all homes have maximum floor dust lead loadings above the HUD 

Lead Safe Housing Rule standard of 40 μg/ft2

.

42 More homes have a window sill lead dust hazard than have a 

floor dust hazard. An estimated 14 percent of all homes have sill dust lead loadings above the HUD Lead Safe 

Housing Rule standard hazard of 250 μg/ft2

.

43

 

42 The average analytical detection limit for each wipe sample was 3.5 μg. While detection limits for each surface are area dependent, this corresponds to a 

detection limit of 3.5 μg/ft2

 for a one square foot floor sample, 7 μg/ft2 for a typical 3 inch by 24 inch sill sample, or 8 μg/ft2 for a typical 1 inch by 18 inch 

trough sample. 

43 From Table 5.2a, the percent of homes with sill dust loadings above 250 μg/ft2 equals [100% (all homes) - 82% (homes with lead in sill dust below 250 

μg/ft2

) - 2% (homes with missing data) - 2% (homes with no sills)] = 14%. 

0

5

10

15

20

25

Floor Window Sill

HUs (%)

<$30K/Year

>=$30K/Year
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-4 October 31, 2002 

Figure 5.3 Distribution of Maximum Floor Dust Lead Loadings 

Figure 5.4 Distribution of Maximum Window Sill Dust Loadings 

0

10

20

30

40

50

<LOD LOD-5 5-10 10-20 20-40 40-100 >100

Dust Lead Loadings (μg/sq ft)

HUs (%)

0

10

20

30

40

50

60

70

<LOD LOD-125 125-250 250-500 >500

Dust Lead Loadings (μg/sq ft)

HUs (%)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-5 October 31, 2002 

Table 5.2 Distribution of Maximum Dust Lead Loadings in Housing Units by Surface 

Maximum Dust Lead Loading 

in HU (μg/sq ft) Number of HUs (000)a

 Percent of HUs (%)b

 Estimate Lower 

95% CId

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Floors:c

LT LODe 38,369 34,302 42,436 40% 36% 44% 

GE LOD 57,196 53,147 61,244 60% 56% 64% 

GE 5 28,200 24,920 31,481 30% 26% 33% 

GE 10 15,964 13,141 18,787 17% 14% 20% 

GE 20 8,989 6,871 11,108 9% 7% 12% 

GE 40 5,495 3,770 7,220 6% 4% 8% 

GE 100 2,426 1,470 3,382 3% 2% 4% 

Missingf 123 0% 

Window Sills: 

LT LOD 9,602 7,326 11,879 10% 8% 13% 

GE LOD 82,134 78,850 85,418 86% 83% 88% 

GE 125 20,338 17,590 23,085 21% 19% 24% 

GE 250 13,439 11,516 15,362 14% 12% 16% 

GE 500 9,042 7,136 10,949 10% 8% 12% 

No sill present in HUg 2,221 848 3,594 2% 1% 4% 

Missingf 1,731 2% 

Window Troughs: 

LT LOD 374 0 799 0% 0% 1% 

GE LOD 72,638 67,107 78,169 76% 70% 82% 

GE 800 21,210 16,489 25,931 22% 17% 27% 

No trough present in HU 7,318 5,176 9,459 8% 5% 10% 

Missingf 15,358 16% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) as the denominator. 

c

 Floors include both carpeted and uncarpeted floors. 

d

 CI = 95% confidence interval for the estimated number or percent. 

e

 LT equals “less than.” GE equals “greater than or equal to.” LOD equals “limit of detection.” 

f Missing means that the floor, sill, or trough was present, but that no lead value is available (either the sample was not collected, 

e.g., due to inaccessibility or respondent refusal, or the laboratory did not submit a value). g No sill/trough present” means that there was no sill or trough in the HU, e.g., windows were flush with the wall, or awning 

windows were installed. 

Table 5.3 presents the distribution of average dust lead loadings by surface (floor, window sill, 

and window trough) for all U.S. homes in the target population, for selected threshold values. The average 

dust loading for each surface was determined by simply adding floor, window sill, or window trough dust 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-6 October 31, 2002 

loadings for each room sampled in each HU and dividing by the number of rooms sampled (unweighted 

average).44 

The same trends are observed in Table 5.3 for average dust lead loadings as for the distribution 

of maximum dust lead loadings in Table 5.2. However, Table 5.3 shows that fewer homes have carpeted floor 

dust lead hazards than uncarpeted floor dust hazards (i.e., carpeted floors have lower dust lead loadings – as 

indicated by the results of the wipe sampling employed in the survey). In fact, the regression modeling 

suggested that lead loadings on carpeted surfaces were approximately 25 percent lower than smooth and 

cleanable surfaces and 75 percent lower than uncarpeted surfaces that were not smooth and cleanable (see 

Figure C.7)45

 

44 For averaging floor samples, only carpeted floor samples and uncarpeted floor samples were combined for the respective average (carpeted or 

uncarpeted). 

45 The regression modeling also suggested that homes with no evidence of cleaning had higher floor and window dust lead loadings (see Figure C.7 and 

Figure C.9). Higher window dust lead loadings were suggested for rented homes as compared to owned homes, surfaces that were not smooth and 

cleanable as compared to smooth surfaces, and windows with vinyl mini-blinds as compared to those without vinyl mini-blinds (see Figure C.9). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-7 October 31, 2002 

Table 5.3 Distribution of Average Dust Lead Loadings in Housing Units by Surface 

Average Dust Lead Loading 

in HU (μg/sq ft) Number of HUs (000)a

 Percent of HUs (%)b

 Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Floors (Uncarpeted): 

LT LODd 51,252 47,180 55,323 54% 49% 58% 

GE LOD 40,529 36,366 44,693 42% 38% 47% 

GE 5 17,291 13,855 20,727 18% 14% 22% 

GE 10 8,512 6,348 10,676 9% 7% 11% 

GE 20 4,843 3,263 6,423 5% 3% 7% 

GE 40 2,449 1,414 3,484 3% 2% 4% 

GE 100 966 239 1,694 1% 0% 2% 

No Uncarpeted 3,907 4% 

Floors (Carpeted): 

LT LODd 66,628 63,563 69,694 70% 67% 73% 

GE LOD 21,356 18,700 24,012 22% 20% 25% 

GE 5 5,806 4,073 7,540 6% 4% 8% 

GE 10 2,374 1,488 3,261 3% 2% 3% 

GE 20 1,368 674 2,061 1% 1% 2% 

GE 40 298 0 634 0% 0% 1% 

GE 100 59 0 190 0% 0% 0% 

No Carpeted 7,704 8% 

Window Sills: 

LT LOD 12,800 10,201 15,399 13% 11% 16% 

GE LOD 78,936 75,462 82,410 83% 80% 85% 

GE 125 13,875 11,717 16,033 15% 12% 17% 

GE 250 8,287 6,636 9,938 9% 7% 10% 

GE 500 4,900 3,611 6,190 5% 4% 7% 

No sill present in HUe 2,221 848 3,594 2% 1% 4% 

Missingf 1,731 2% 

Window Troughs: 

LT LOD 663 52 1,274 1% 0% 1% 

GE LOD 72,349 66,714 77,985 76% 70% 81% 

GE 800 16,395 12,827 19,964 17% 13% 21% 

No trough present in HU 7,318 5,176 9,459 8% 5% 10% 

Missing 15,358 16% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 All percentages are calculated with total housing units (95,688) as the denominator. 

c CI = 95% confidence interval for the estimated number or percent. d

 LT equals “less than.” GT equals “greater than.” LOD equals “limit of detection.” 

e

 “No sill/trough present” means that there was no sill or trough in the HU, e.g., windows were flush with the wall, or awning 

windows were installed. f

 Missing means that the floor, sill, or trough was present, but that no lead value is available (either the sample was not collected, 

e.g., due to inaccessibility or respondent refusal, or the laboratory did not submit a value). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-8 October 31, 2002 

Table 5.4 presents the distribution of dust lead loadings by room type and surface for selected 

threshold values. The vast majority of floors had undetectable levels of dust lead. About 1 percent of rooms 

had dust lead levels above the HUD Lead Safe Housing Rule standard for floors. Five percent of rooms had 

dust lead levels above the HUD Lead Safe Housing Rule standard for window sills. 

Figure 5.5 presents a scatter plot of the window sill dust lead loadings against the floor dust lead 

loadings. Each point in Figure 5.5 represents the floor and window dust lead loadings from the same room in 

the same housing unit. The figure shows evidence of a moderate positive correlation between the dust lead 

loadings on these two neighboring surfaces. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-9 October 31, 2002 

Table 5.4 Distribution of Dust Lead Loading by Room and Surfaces 

Dust Lead Kitchens Living Rooms Bedrooms Other Rooms 

Loading 

(μg/sq ft)a 

Number of 

Rooms 

(000)b

Percent 

of Rooms 

(%)c

Number of 

Rooms 

(000) 

Percent 

of Rooms 

(%) 

Number of 

Rooms 

(000) 

Percent 

of Rooms 

(%) 

Number of 

Rooms 

(000) 

Percent 

of Rooms 

(%) 

Floorsd

LT LODe 63,244 66% 98,433 78% 170,153 78% 231,924 73%

GE LOD 31,633 33% 26,732 21% 45,915 21% 84,438 27%

GE 5 14,062 15% 9,863 8% 19,340 9% 34,291 11%

GE 10 5,568 6% 4,287 3% 10,612 5% 18,933 6%

GE 20 2,571 3% 1,824 1% 4,175 2% 10,626 3%

GE 40 712 1% 880 1% 1,593 1% 7,477 2%

GE 100 335 0% 170 0% 1,354 1% 785 0%

Missingf 488 1% 1,737 1% 1,002 1% 2,594 1%

Total Rooms 95,365 100% 126,902 100% 217,069 100% 318,956 100%

Window Sills

LT LOD 23,001 24% 29,378 23% 38,394 18% 44,841 14%

GE LOD 50,393 53% 72,154 57% 140,748 65% 141,008 44%

GE 125 7,037 7% 10,937 9% 20,393 9% 23,472 7%

GE 250 4,329 5% 6,731 5% 11,075 5% 17,156 5%

GE 500 2,455 3% 4,386 4% 6,661 3% 10,096 3%

Missing 3,870 4% 5,462 4% 17,993 8% 16,321 5%

No Sills 18,102 19% 19,907 16% 19,934 9% 116,785 37%

Total Rooms 95,365 100% 126,902 100% 217,069 100% 318,956 100%

Window Troughs

LT LOD 3,293 4% 4,125 3% 5,211 2% 6,657 2% 

GE LOD 49,962 52% 64,827 51% 122,752 57% 119,236 37% 

GE 800 9,249 10% 12,795 10% 23,268 11% 21,487 7% 

Missing 16,542 17% 27,537 22% 57,738 27% 58,044 18% 

No Trough 25,568 27% 30,413 24% 31,368 15% 135,019 42% 

Total Rooms 95,365 100% 126,902 100% 217,069 100% 318,956 100% a

 In this table, maximum loading is not applicable as only one dust sample was collected from each surface in each room. 

v

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

c

 All percentages are calculated with total rooms of that type as the denominator. 

d

 Floors include both carpeted and uncarpeted floors. 

e LT equals “less than.” GE equals “greater than or equal to.” LOD equals “limit of detection.” f Missing means that the floor, sill, or trough was present, but that no lead value is available (either the sample was not collected, 

e.g., due to inaccessibility or respondent refusal, or the laboratory did not submit a value). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-10 October 31, 2002 

Figure 5.5 Association Between Dust Lead Loading on Floors and Window Sills 

Tables 5.5a through 5.5c present the distributions of floor, window sill, and window trough dust 

lead loadings, respectively, by selected thresholds and by year of construction. It is evident that older homes 

have considerably more dust lead than newer homes. The percentage of homes over the HUD Rule standard 

of 40 μg/ft2

 for floor dust (Table 5.5a) increases from less than 1 percent for post-1977 homes to 16 percent 

0.01

0.1

1

10

100

1000

10000

100000

0.1 1 10 100 1000 10000 100000

Floor Lead Loading (μg/sq ft)

Window Sill Lead Loading (μg/sq ft)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-11 October 31, 2002 

for pre-1940 homes. The percentage of homes over the sill dust standard (Table 5.5b) steadily increases from 

4 percent for post-1977 homes to 14 percent for 1940-1959 homes to 40 percent for pre-1940 homes. 

Table 5.5a Maximum Floor Dust Lead Loading by Year of Construction 

Maximum Floor Dust Year of Construction 

Lead Loading(μg/sq ft)a 1978-1998 1960-1977 1940-1959 Before 1940 

Number 

(000) 

Percent 

(%)b

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent

(%) 

LT LODc Number HUsd 17,487 59% 13,006 47% 5,667 28% 2,208 13% 

 Lower 95% CIe 15,646 53% 10,272 38% 4,076 20% 782 4% 

 Upper 95% CI 19,329 65% 15,740 56% 7,257 35% 3,635 21% 

GE LOD Number HUs 12,241 41% 14,868 53% 14,820 72% 15,268 87% 

 Lower 95% CI 10,419 35% 12,454 44% 12,770 65% 13,008 79% 

 Upper 95% CI 14,064 47% 17,281 62% 16,869 80% 17,527 96% 

GE 5 Number HUs 3,233 11% 4,968 18% 8,753 43% 11,245 64% 

 Lower 95% CI 2,285 8% 3,567 13% 7,060 35% 9,635 55% 

 Upper 95% CI 4,181 14% 6,370 23% 10,446 50% 12,855 73% 

GE 10 Number HUs 1,153 4% 2,488 9% 4,938 24% 7,386 42% 

 Lower 95% CI 370 1% 1,607 6% 3,447 17% 5,802 33% 

 Upper 95% CI 1,935 7% 3,369 12% 6,428 31% 8,970 52% 

GE 20 Number HUs 97 0% 1,112 4% 2,784 14% 4,996 29% 

 Lower 95% CI 0 0% 516 2% 1,283 6% 3,759 22% 

 Upper 95% CI 267 1% 1,708 6% 4,286 21% 6,234 35% 

GE 40 Number HUs 97 0% 588 2% 1,967 10% 2,843 16% 

 Lower 95% CI 0 0% 216 1% 718 4% 1,989 11% 

 Upper 95% CI 267 1% 961 4% 3,215 16% 3,698 21% 

GE 100 Number HUs 97 0% 280 1% 935 5% 1,114 6% 

 Lower 95% CI 0 0% 0 0% 121 1% 587 3% 

 Upper 95% CI 267 1% 640 2% 1,750 9% 1,642 9% 

Missing Number HUs 0 0% 0 0% 77 0% 0 0% 

a

 Floors include both carpeted and uncarpeted floors. 

b All percentages are calculated with total housing units (95,688) as the denominator. c

 LT equals “less than.” GE equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

e

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-12 October 31, 2002 

Table 5.5b Maximum Window Sill Dust Lead Loading by Year of Construction 

Maximum Floor Dust Year of Construction 

Lead Loading(μg/sq ft)a 1978-1998 1960-1977 1940-1959 Before 1940 

Number 

(000) 

Percent 

(%)b

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent

(%) 

LT LODc Number HUsd 6,196 21% 1,924 7% 1,074 5% 408 2% 

 Lower 95% CIe 4,270 14% 826 3% 277 1% 0 0% 

 Upper 95% CI 8,122 27% 3,021 11% 1,871 9% 835 5% 

GE LOD Number HUs 21,823 73% 24,729 89% 18,779 91% 16,803 96% 

 Lower 95% CI 19,833 68% 22,996 84% 16,956 87% 15,103 93% 

 Upper 95% CI 23,814 79% 26,462 94% 20,602 96% 18,503 99% 

GE 125 Number HUs 1,806 6% 4,097 15% 5,407 26% 9,028 52% 

 Lower 95% CI 578 2% 2,444 9% 3,954 19% 7,196 42% 

 Upper 95% CI 3,033 10% 5,749 21% 6,860 33% 10,861 61% 

GE 250 Number HUs 1,029 4% 1,755 6% 3,712 18% 6,943 40% 

 Lower 95% CI 139 1% 1,086 4% 2,556 12% 5,476 31% 

 Upper 95% CI 1,919 7% 2,424 9% 4,867 24% 8,410 48% 

GE 500 Number HUs 447 2% 747 3% 2,869 14% 4,980 29% 

 Lower 95% CI 0 0% 274 1% 1,779 9% 3,712 21% 

 Upper 95% CI 1,024 3% 1,219 4% 3,959 19% 6,247 36% 

Missing Number HUs 299 1% 851 3% 361 2% 220 1% 

No sills Number HUs 1,456 5% 371 1% 349 2% 45 0% 

 Lower 95% CI 456 2% 0 0% 0 0% 0 0% 

 Upper 95% CI 2,456 8% 762 3% 730 4% 143 1% 

a Missing means that the sill was present, but that no lead value is available (either the sample was not collected, e.g., due to

inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No sill present” means that there was no sill in 

the HU, e.g., windows were flush with the wall, or awning windows were installed. b All percentages are calculated with total housing units (95,688) as the denominator. c

 LT equals “less than.” GT equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

e

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-13 October 31, 2002 

Table 5.5c Maximum Window Trough Dust Lead Loading by Year of Construction 

Year of Construction 

1978-1998 1960-1977 1940-1959 Before 1940 

Maximum Window Trough 

Dust Lead Loading (μg/sq ft)a

Number 

(000) 

Percent 

(%)b

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent

(%) 

Number 

(000) 

Percent

(%) 

LT LODc Number HUsd 280 1% 94 0% 0 0% 0 0% 

Lower 95% CIe 0 0% 0 0% 0 0% 0 0% 

Upper 95% CI 681 2% 235 1% 0 0% 0 0% 

GE LOD Number HUs 20,969 70% 20,319 73% 16,406 80% 14,943 86% 

 Lower 95% CI 17,718 60% 17,730 64% 14,638 73% 13,192 80% 

 Upper 95% CI 24,221 81% 22,909 82% 18,174 86% 16,694 91% 

GE 800 Number HUs 2,252 8% 3,788 14% 6,286 31% 8,883 51% 

Lower 95% CI 1,032 4% 2,504 9% 4,500 21% 7,084 41% 

Upper 95% CI 3,473 12% 5,072 18% 8,073 40% 10,683 61% 

Missing Number HUs 4,184 14% 5,885 21% 2,966 14% 2,322 13% 

No troughs Number HUs 4,341 15% 1,576 6% 1,191 6% 210 1% 

Lower 95% CI 2,380 8% 732 3% 368 2% 0 0% 

Upper 95% CI 6,301 21% 2,419 9% 2,014 10% 451 3% 

a Missing means that the trough was present, but that no lead value is available (either the sample was not collected, e.g., due to 

inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No trough present” means that there was no 

trough in the HU, e.g., windows were flush with the wall, or awning windows were installed. b All percentages are calculated with total housing units of that age as the denominator. c

 LT equals “less than.” GT equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live 

e

 CI = 95% confidence interval for the estimated number or percent. 

Tables 5.6a through 5.6c present floor, window sill, and window trough dust loading 

distributions by household income level. There are some significant differences shown in the table. A greater 

percent of homes in the higher income level have lower lead dust loadings. For example, 47 percent of higher 

income homes have lead dust loadings on floors below the limit of detection, while only 29 percent of homes in 

the lower income level have loadings below the limit of detection. Only 1 percent of homes in the higher 

household income level exceed 100 μg/ft2 floor dust lead loading, while 5 percent of lower income level homes 

exceed this loading. Similar trends are observed for window sill and trough dust loadings. 

Although the data have not been presented, there were no apparent differences between 

urbanization categories and dust lead loadings. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-14 October 31, 2002 

Table 5.6a Maximum Floor Dust Lead Loadings by Household Income 

Maximum Floor Dust 

Lead Loading(μg/sq ft)a Household Income 

Less than $30,000/year Equal to or above $30,000/year 

 Number (000) Percent (%)b Number (000) Percent (%) 

LT LODc Number HUsd 9,747 29% 26,508 47% 

Lower 95% CIe 6,944 23% 22,360 42% 

 Upper 95% CI 12,550 35% 30,657 53% 

GE LOD Number HUs 24,038 71% 29,525 53% 

 Lower 95% CI 19,932 65% 26,065 47% 

 Upper 95% CI 28,143 77% 32,985 58% 

GE 5 Number HUs 13,364 40% 13,215 24% 

 Lower 95% CI 10,562 32% 10,859 20% 

 Upper 95% CI 16,166 47% 15,571 27% 

GE 10 Number HUs 8,276 25% 6,792 12% 

 Lower 95% CI 6,219 19% 5,052 9% 

 Upper 95% CI 10,332 30% 8,532 15% 

GE 20 Number HUs 4,282 13% 4,135 7% 

 Lower 95% CI 3,117 9% 2,782 5% 

 Upper 95% CI 5,447 17% 5,488 10% 

GE 40 Number HUs 2,819 8% 2,170 4% 

 Lower 95% CI 1,710 5% 924 2% 

 Upper 95% CI 3,927 12% 3,415 6% 

GE 100 Number HUs 1,637 5% 435 1% 

 Lower 95% CI 728 2% 57 0% 

 Upper 95% CI 2,546 8% 813 1% 

Missing Number HUs 46 0% 77 0% 

a Missing means that the sill or trough was present, but that no lead value is available (either the sample was not collected, e.g., 

due to inaccessibility or respondent refusal, or the laboratory did not submit a value). b All percentages are calculated with total housing units in that income class as the denominator. c

 LT equals “less than.” GT equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

e

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-15 October 31, 2002 

Table 5.6b Maximum Window Sill Lead Dust Loadings by Household Income 

Household Income 

Less than $30,000/year Equal to or Above $30,000/year Window Sill Dust Lead 

Loading(μg/sq ft)a

Number (000) Percentb

 Number (000) Percent 

LT LODc Number HUsd 1,448 4% 7,111 13% 

Lower 95% CIe 376 1% 5,291 9% 

 Upper 95% CI 2,520 7% 8,931 16% 

GE LOD Number HUs 29,948 89% 47,597 85% 

 Lower 95% CI 24,656 84% 42,665 81% 

 Upper 95% CI 35,241 93% 52,528 89% 

GE 125 Number HUs 10,322 31% 8,865 16% 

 Lower 95% CI 7,909 26% 6,896 13% 

 Upper 95% CI 12,735 36% 10,835 19% 

GE 250 Number HUs 7,671 23% 4,772 9% 

 Lower 95% CI 5,776 18% 3,611 7% 

 Upper 95% CI 9,565 28% 5,933 11% 

GE 500 Number HUs 4,395 13% 3,893 7% 

 Lower 95% CI 2,943 9% 2,773 5% 

 Upper 95% CI 5,846 17% 5,014 9% 

Missing Number HUs 1,137 3% 594 1% 

No sills Number HUs 1,297 4% 809 1% 

 Lower 95% CI 250 1% 151 0% 

 Upper 95% CI 2,345 7% 1,466 3% 

a Missing means that the sill or trough was present, but that no lead value is available (either the sample was not collected, e.g., 

due to inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No sill/trough present” means that there 

was no sill or trough in the HU, e.g., windows were flush with the wall, or awning windows were installed. b All percentages are calculated with total housing units in that income class as the denominator. c

 LT equals “less than.” GT equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

e

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-16 October 31, 2002 

Table 5.6c Maximum Window Trough Lead Dust Loadings by Household Income 

Maximum Window Trough Dust 

Lead Loading(μg/sq ft)a Household Income 

Less than $30,000/year Equal to or Above $30,000/year

 Number (000) Percentb Number (000) Percent 

LT LODc Number HUsd 59 0% 315 1% 

Lower 95% CIe 0 0% 0 0% 

 Upper 95% CI 180 1% 723 1% 

LT 800 Number HUs 25,985 77% 42,253 75% 

 Lower 95% CI 21,486 70% 37,300 69% 

 Upper 95% CI 30,485 84% 47,205 81% 

GE 800 Number HUs 9,449 28% 10,623 19% 

 Lower 95% CI 6,742 20% 8,067 15% 

 Upper 95% CI 12,156 36% 13,179 23% 

Missing Number HUs 5,624 17% 8,788 16% 

No troughs Number of HUs 2,162 6% 4,755 9% 

 Lower 95% CI 869 3% 3,009 5% 

 Upper 95% CI 3,456 10% 6,501 12% 

a Missing means that the sill or trough was present, but that no lead value is available (either the sample was not collected, e.g., 

due to inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No sill/trough present” means that there 

was no sill or trough in the HU, e.g., windows were flush with the wall, or awning windows were installed. b All percentages are calculated with total housing units in that income class as the denominator. c

 LT equals “less than. “GE equals “greater than or equal to.” LOD equals “limit of detection.”

d

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. e

 CI = 95% confidence interval for the estimated number or percent. 

Figure 5.646 shows the distribution of the dust lead loadings by room type: kitchen, common 

living area, bedroom, and other room. For these four room types, both floor dust and window dust have been 

combined. Dust loadings for the main entrance are also shown in the figure, but these are only floor loadings 

since no data were collected from main entrance windows. Figure 5.7 shows the distribution of the dust lead 

measurements by surface and carpet. In both figures, the distributions are extremely right-skewed. Except for 

troughs, none of the boxes extend above 40 μg/ft2

, which means that the 75thpercentile is less than 40 μg/ft2. 

However, there are dust lead loadings well above 10,000 μg/ft2. On troughs, they extend above 100,000 

μg/ft2. 

Table 5.7 presents selected parameters of the distributions of dust lead loadings by surface types, 

corresponding to the boxplots in Figure 5.7. Table 5.7 also presents geometric means and standard deviations. 

 

46 Dust lead loading data is presented in box plot form. Each box plot shows a univariate data distribution, for example, the dust samples collected from a 

specific location (e.g., entrance floor). The box in the box plot represents the middle 50 percent of the data; the bottom of the box gives the 25th percentile; 

the top of the box gives the 75th percentile, and the horizontal line inside the box gives the median or 50th percentile. The vertical lines extending from the 

top and bottom of the box reach to the largest and smallest observations, respectively, except for outliers. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-17 October 31, 2002 

The distributions in Table 5.7 are all right-skewed, so that they are not normally distributed. A better model 

would be the lognormal distribution. Appendix C includes a discussion of distributional models for these data. 

Figure 5.6 Box Plots for Dust Lead Loadings by Room 

a

 The first four plots include floor and window loadings. Main entrance only includes floors since no data were collected from 

main entrance windows. b

 The box in the box plot represents the middle 50 percent of the data; the bottom of the box gives the 25th percentile; the top of 

the box gives the 75th percentile, and the horizontal line inside the box gives the median or 50th percentile. The vertical lines 

extending from the top and bottom of the box reach to the largest and smallest observations, respectively, except for outliers.

0.01

0.1

1

10

100

1000

10000

100000

1000000

Kitchen Living Room Bedroom Other Room Main Entrance

(Only Floors)

Room Type

Dust Lead Loading (

μg/sq ft)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-18 October 31, 2002 

Figure 5.7 Box Plots for Dust Lead Loadings by Surface 

a

 The box in the box plot represents the middle 50 percent of the data; the bottom of the box gives the 25th percentile; the top of 

the box gives the 75th percentile, and the horizontal line inside the box gives the median or 50th percentile. The vertical lines 

extending from the top and bottom of the box reach to the largest and smallest observations, respectively, except for outliers.

0.01

0.1

1

10

100

1000

10000

100000

1000000

All Floors Carpeted Floors Non-Carpeted

Floors

Window Sills Window Troughs

Surface

Dust Lead Loading (

μg/sg ft)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-19 October 31, 2002 

Table 5.7 Estimated Empirical Distribution Parameters of Dust Lead Loadings by Surface Types 

Floors Window Sills Window Troughs 

μg/ft2 μg/ft2 μg/ft2

Arithmetic Mean 13.6 194.9 1,990.9 

Arithmetic Standard Deviation 483.5 1682.7 12,086.5 

Geometric Mean 1.1 9.4 96.4 

Geometric Standard Deviationa 3.8 9.3 14.4 

25th Percentile .375 2.0 18.0 

Median 0.9 8.3 89.1 

75th Percentile 2.0 37.13 462.0 

90th Percentile 6.0 172.8 2,824.2 

95th Percentile 13.2 524.9 6,974.6 

Number of Samples 3,894 2,302 1,607 

a The geometric standard deviation is computed as exp(s), where s is the arithmetic standard deviation of the natural logarithms of 

the loadings (see, e.g., Gilbert, R. O. (1987) Statistical Methods for Environmental Pollution Monitoring, Van Nostrand 

Reinhold Company New York). b For this table, values below 0.375 were set equal to 0.375, which is 1⁄4 of the limit of detection.

5.3 Association between Interior Dust Lead Hazards and Interior LBP Condition 

Figure 5.8 presents the prevalence of interior dust lead hazards in relation to the condition of the 

interior LBP. Table 5.8 presents further details on these estimates. Dust lead hazards are more likely to exist 

in homes with deteriorated LBP. An estimated 61 percent (+20%) of homes with significantly deteriorated 

LBP have lead dust hazards, while only 33 percent (+7%) of homes with LBP in good condition have lead dust 

hazards. Only 6 percent (+2%) of homes with no interior LBP have lead dust hazards. Although it appears 

from the data that the presence of LBP, especially significantly deteriorated LBP, contributes to higher dust 

lead hazard, there are additional sources of lead in the environment to account for dust lead in homes with no 

lead-based paint. 

Table 5.8 also allows one to compare the relative risks (95 percent confidence intervals on that 

risk are not shown in the table) of interior lead dust hazards associated with different paint conditions. The 

presence of significantly deteriorated LBP makes a house 1.8 (+0.5) times as likely to have an interior lead 

dust hazard compared to a house where the LBP is in good condition, and 10.0 (+1.9) times as likely as a 

house without LBP. Even a house with LBP in good condition is 5.4 (+0.8) times as likely to have interior 

lead dust hazards as one without any LBP. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-20 October 31, 2002 

Figure 5.8 Association Between Dust Lead Hazards and Condition of Interior Lead-Based Paint 

Table 5.8 Association Between Dust Lead Hazards and Presence and Condition of Interior LeadBased Paint 

No LBP on 

Interior or 

Exterior 

No Interior LBP Interior LBP in 

Good Condition

Significantly 

Deteriorated 

Interior Dust Lead Hazards Interior LBP 

Number 

(000) 

Percent

(%) 

Number 

(000) 

Percent

(%) 

Number 

(000) 

Percent

(%) 

Number 

(000) 

Percent

(%) 

Estimatea 55,105 95% 62,752 94% 15,244 67% 2,389 39%

Lower 95% CIb 51,893 90% 60,141 90% 12,633 56% 1,565 26%

None Present 

Upper 95% CI 58,318 100% 65,363 98% 17,855 78% 3,213 53%

Estimate 2,686 5% 4,068 6% 7,508 33% 3,727 61%

Lower 95% CI 1,372 2% 2,584 4% 6,024 26% 2,505 41%

Some Present 

Upper 95% CI 4,001 7% 5,552 8% 8,992 40% 4,949 81%

Total HUs 57,791 100% 66,820 100% 22,752 100% 6,116 100% a

 Estimate is either the number of permanently occupied, noninstitutional housing units (000) in which children are permitted to 

live, or the percentage of total housing units. b CI = 95% confidence interval for the estimated number or percent.

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

No LBP on Interior or Exterior No Interior LBP Interior LBP in Good

Condition

Significantly Deteriorated LBP

Number of Housing Units (000)

Interior Dust Lead Hazards

No Interior Dust Lead Hazards
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-21 October 31, 2002 

Tables 5.9 and 5.10 present data on the association between floor and sill dust lead loadings and 

the presence of interior lead-based paint. Both tables show a positive relationship between the presence of 

interior lead-based paint and dust lead levels. Housing units with some interior LBP are twice as likely to 

have floor dust, and three times as likely to have window sill dust, above hazardous levels compared to 

housing units without LBP. 

Table 5.9 Association Between Floor Dust Lead Loadings and Presence of Interior Lead-Based 

Paint 

Interior Lead Based Paint 

None Present Some Present Maximum Floor Dust Lead 

Loading (μg/sq ft)a

Number (000) Percent (%)b

 Number (000) Percent (%) 

LT LODc Number HUsd 32,873 34% 5,496 6% 

Lower 95% CIe 29,475 31% 3,529 4% 

 Upper 95% CI 36,270 38% 7,463 8% 

GE LOD Number HUs 33,824 35% 23,372 24% 

 Lower 95% CI 30,086 31% 19,997 21% 

 Upper 95% CI 37,561 39% 26,748 28% 

GE 5 Number HUs 12,242 13% 15,958 17% 

 Lower 95% CI 9,835 10% 13,372 14% 

 Upper 95% CI 14,650 15% 18,544 19% 

GE 10 Number HUs 6,003 6% 9,961 10% 

 Lower 95% CI 4,238 4% 7,615 8% 

 Upper 95% CI 7,768 8% 12,307 13% 

GE 20 Number HUs 2,493 3% 6,496 7% 

 Lower 95% CI 1,606 2% 4,661 5% 

 Upper 95% CI 3,381 4% 8,331 9% 

GE 40 Number HUs 1,666 2% 3,830 4% 

 Lower 95% CI 993 1% 2,378 3% 

 Upper 95% CI 2,338 3% 5,281 6% 

GE 100 Number HUs 1,122 1% 1,304 1% 

 Lower 95% CI 419 0% 654 1% 

 Upper 95% CI 1,825 2% 1,954 2% 

Missing Number HUs 123 

a

 Missing means that the sill or trough was present, but that no lead value is available (either the sample was not collected, e.g., 

due to inaccessibility or respondent refusal, or the laboratory did not submit a value). b All percentages are calculated with total housing units as the denominator. c LT equals "less than." GE equals "greater than or equal to." LOD equals "limit of detection." d "Housing units" include permanently occupied, noninstitutional housing units in which children are permitted to live. e CI = 95% confidence interval for the estimated number or percent.
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 5-22 October 31, 2002 

Table 5.10 Association Between Window Sill Dust Lead Loadings and Presence of Interior 

Lead-Based Paint 

Interior Lead Based Paint 

None Present Some Present Maximum Window Sill Dust Lead 

Loading (μg/sq ft)a

Number (000) Percent (%)b

 Number (000) Percent (%) 

LT LODc Number HUsd 8,728 9% 874 1% 

Lower 95% CIe 6,544 7% 187 0% 

 Upper 95% CI 10,912 12% 1,562 2% 

GE LOD Number HUs 54,454 57% 27,680 29% 

 Lower 95% CI 51,195 54% 24,515 26% 

 Upper 95% CI 57,713 60% 30,845 32% 

GE 125 Number HUs 6,553 7% 13,785 14% 

 Lower 95% CI 5,043 5% 11,177 12% 

 Upper 95% CI 8,063 8% 16,393 17% 

GE 250 Number HUs 3,434 4% 10,005 11% 

 Lower 95% CI 2,193 2% 8,096 9% 

 Upper 95% CI 4,675 5% 11,914 13% 

GE 500 Number HUs 1,498 2% 7,544 8% 

 Lower 95% CI 651 1% 5,770 6% 

 Upper 95% CI 2,346 3% 9,318 10% 

No sill present in HUa Number HUs 2,043 0% 178 0% 

Missing Number HUs 1,595 136 

a

 Missing means that the sill was present, but that no lead value is available (either the sample was not collected, e.g., due to 

inaccessibility or respondent refusal, or the laboratory did not submit a value). b All percentages are calculated with total housing units as the denominator. c LT equals "less than." GE equals "greater than or equal to." LOD equals "limit of detection." d "Housing units" include permanently occupied, noninstitutional housing units in which children are permitted to live. e CI = 95% confidence interval for the estimated number or percent.
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-1 October 31, 2002 

6. RESIDENTIAL SOIL LEAD 

Chapter 6 presents estimates of the prevalence of soil lead by lead concentration, and the 

association between soil lead concentration and exterior lead-based paint condition. Relevant estimates are 

compared with the findings of the 1990 LBP Survey. The prevalence of soil lead hazards in housing is 

presented in Chapter 3. Since soil lead hazards include lead in soil in children’s play areas, most estimates in 

this Chapter are based on the subsample of 375 homes with data on the presence or absence of children’s play 

areas in the yards and on the extent of soil lead hazards in children’s play areas. A few tables in this chapter 

are independent of the presence or absence of lead-contaminated soil in children’s play areas; such tables are 

therefore based on the full sample and have a footnote indicating that the basis is the full sample.

6.1 Prevalence of Residential Soil Lead Over All Sampled Locations 

A composite soil sample was collected at each of five sites on the property of each dwelling unit: 

1) near the most commonly used entrance, 2) the dripline and 3) the mid-yard line of the wall with the main 

entrance, and 4) the dripline and 5) mid-yard line of a second, randomly-selected wall. The main entrance 

sample was a composite sample of two cores from the main entrance area. The dripline and mid-yard samples 

on each wall were composite samples from three locations along the length of the sample site. In addition, soil 

samples were collected from children’s play areas for a subsample of homes. At each of these homes, up to 

four samples were collected from children’s play equipment, when present; otherwise, one sample was 

collected from an area of the yard identified as being where children play. The tables in this section and in 

Section 6.2 are based on the lead concentration data from all of these soil samples, referenced as “all sampled 

locations.” Section 6.3 then presents data on soil lead concentrations in children’s play areas, while Section 

6.4 presents corresponding data for the “rest of the yard,” i.e., areas not identified as children’s play areas. 

Figure 6.1 and Table 6.1 present the distribution of maximum bare soil lead concentrations. 

Figure 6.1 presents a histogram of the distribution, while Table 6.1 presents the number and percentage of 

HUs by selected soil lead concentration thresholds: 0, 20, 50, 200, 400, 1,200, 1,600, 2,000, and 5,000 ppm. 

Figure 6.1 and Table 6.1 include bare soil from all sampled locations, both play areas and all other locations. 

An estimated 58 percent (±8%) of homes have soil lead levels above the limit of detection.47 An estimated 10 

 

47 The sample limit of detection for this study was determined to be 20 ppm by testing four distinct soil types from among the study samples in accordance 

with EPA SW 840 Method 3050 procedures. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-2 October 31, 2002 

percent (±4%)48 of homes have soil lead levels above 400 ppm, and 7% (±4%) have soil lead levels above 

1,200 ppm. Only 3 percent of homes were found to have soil lead above 2,000 ppm. The maximum soil 

values for each HU have been used in Table 6.1. The effect of using the average soil lead for each HU would 

drive the distribution towards the lower thresholds, i.e. more homes have lower average soil lead 

concentrations. 

Care is to be exercised in comparing the tables in this Chapter with Table 3.3, which tabulate the 

prevalence of soil lead hazards. The tables in this chapter present the distribution of residential soil lead 

concentrations at selected locations, while soil lead hazards are defined in terms of soil lead concentrations in 

two types of locations. Specifically, a housing unit is defined to have a soil lead hazard if soil lead 

concentrations exceed 400 ppm in play areas or exceed 1,200 ppm in the rest of the yard. Thus, the tables in 

this section do not directly compare with Table 3.3. 

Figure 6.1 Distribution of Maximum Bare Soil Lead Concentrations 

 

48 All confidence intervals are at the 95 percent level for the estimated number or percentage. 

0

10

20

30

40

50

<20 20-50 50-200 200-400 400-1200 1200-1600 1600-2000 2000-5000 >5000

Lead Concentrations (ppm)

HUs (%)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-3 October 31, 2002 

Table 6.1 Distribution of Maximum Bare Soil Sample Lead Concentrations (All Sampled 

Locations) 

Bare Soil Lead Number of HUs (000)a Percent of HUs (%)b

 

Estimate 

Lower 

95% CIc

Upper 

95% CI Estimate 

Lower 

95% CI 

Upper 

95% CI 

GEd0 ppm 77,888 72,054 83,722 81% 75% 88% 

GE 20 ppm 55,114 47,348 62,881 58% 50% 66% 

GE 50 ppm 40,023 31,365 48,680 42% 33% 51% 

GE 200 ppm 15,299 11,626 18,971 16% 12% 20% 

GE 400 ppm 9,996 6,398 13,594 10% 7% 14% 

GE 1,200 ppm 6,271 2,733 9,809 7% 3% 10% 

GE 1,600 ppm 3,900 1,670 6,131 4% 2% 6% 

GE 2,000 ppm 3,124 827 5,420 3% 1% 6% 

GE 5,000 ppm 1,580 0 3,309 2% 0% 4% 

No Bare Soil 15,413 9,789 21,037 16% 10% 22% 

No Soil 2,242 330 4,154 2% 0% 4% 

Missinge 145 0 527 0% 0% 1% a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b All percentages are calculated with total housing units (95,688) as the denominator. c

 CI = 95% confidence interval for the estimated number or percent. 

d GE equals “greater than or equal to.” e

 “Missing” means that soil was present, but that no lead value is available (either the sample was not collected, e.g. due to 

inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No soil” means that there was no soil on the 

property to sample. 

Table 6.2 presents the number and percentage of housing units by construction year for selected 

soil lead concentration thresholds for bare soil only, again for all sampling locations. As seen above for all 

soil, as the soil lead threshold increases, the number of newer homes meeting the criteria for bare soil 

decreases faster than the older homes. In fact, practically no newer homes (1960-1998) have lead in bare soil 

above 1,200 ppm, and less than 4 percent have soil lead above 400 ppm.49 Thus, the data suggest that older 

homes have higher bare soil lead levels than new homes. Since the amount of lead added to commercial 

residential paint declined from 1940 to 1980, these observations are not unreasonable, and have been reported 

by others.50 

 

49 Even fewer homes will have greater than 9 square feet of bare soil above 400 ppm or 2,000 ppm (soil lead hazard as specified in the Lead Safe Housing 

Rule). 

50 Francek, M. (1992.) Soil lead levels in a small town environment: A case study from Mt. Pleasant, Michigan. Environmental Pollution 76. pp. 251-

257. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-4 October 31, 2002 

Table 6.2 Distribution of Maximum Bare Soil Sample Lead Concentration by Construction Year 

(All Sampled Locations) 

Bare Soil Lead 

Concentration 

Number of HUs (000)a Percent of HUs (%)b

 Before 

1940 

1940 - 

1959 

1960 – 

1977 

1978 - 

1998 

Before 

1940 

1940 - 

1959 

1960 - 

1977 

1978 - 

1998 

GEc 0 ppm 12,015 16,843 23,185 25,845 69% 82% 83% 87% 

GE 20 ppm 12,015 15,404 17,345 10,350 69% 75% 62% 35% 

GE 50 ppm 11,193 12,789 10,437 5,603 64% 62% 37% 19% 

GE 200 ppm 7,243 6,073 1,793 190 41% 30% 6% 1% 

GE 400 ppm 5,148 3,736 1,111 0 30% 18% 4% 0% 

GE 1,200 ppm 3,386 2,886 0 0 19% 14% 0% 0% 

GE 1,600 ppm 2,006 1,894 0 0 12% 9% 0% 0% 

GE 2,000 ppm 1,320 1,804 0 0 8% 9% 0% 0% 

GE 5,000 ppm 1,106 475 0 0 6% 2% 0% 0% 

Missingd 145 0 0 0 1% 0% 0% 0% 

No Bare Soil 4,313 2,762 4,613 3,724 25% 13% 17% 13% 

No Soil 1,003 939 95 205 6% 5% 0% 1% 

Total 17,476 20,544 27,893 29,774 100% 100% 100% 100% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b All percentages are calculated with total housing units of that age as the common denominator. c GE equals “greater than or equal to.” d Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). 

“No soil” means that there was no soil on the property to sample. 

Figure 6.2 presents a series of boxplots51 showing the distribution of soil lead concentrations at 

each of the seven sample sites. The last two boxplots represent only the data collected during the 

supplemental data collection from play areas. As with paint lead and dust lead loadings, soil lead 

concentrations are extremely skewed with over three-fourths of the samples under 200 ppm, but some samples 

are well above 1,000 ppm. 

Table 6.3 presents selected parameters of the distributions of soil lead concentrations by sample 

sites, corresponding to the first five boxplots in Figure 6.2. Table 6.3 also presents geometric means and 

standard deviations. As with the distributions of paint lead loadings and dust lead loadings, the distribution of 

soil lead concentrations is right-skewed. Thus, a normal distribution would not be a suitable model for the 

distribution. A lognormal distribution would be a more suitable distribution. Appendix C includes a 

discussion of modeling these data. 

 

51 Soil lead concentration data is presented in box plot form. Each box plot shows a univariate data distribution, for example, the soil samples collected 

from a specific location (e.g., main entry). The box in the box plot represents the middle 50 percent of the data; the bottom of the box gives the 25th

percentile; the top of the box gives the 75th percentile; and the horizontal line inside the box gives the median or 50th percentile. The vertical lines 

extending from the top and bottom of the box reach to the largest and smallest observations, respectively, except for outliers. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-5 October 31, 2002 

Figure 6.2 Box Plots for Lead in Soil Samples by Sample Site 

a

 The box in the box plot represents the middle 50 percent of the data; the bottom of the box gives the 25th percentile; the top of 

the box gives the 75th percentile, and the horizontal line inside the box gives the median or 50th percentile. The vertical lines 

extending from the top and bottom of the box reach to the largest and smallest observations, respectively, except for outliers. b

 “Wall 1” refers to the main entrance wall and “Wall 2” refers to the second, randomly-selected wall. 

1

10

100

1000

10000

100000

Main Entry Wall 1

Dripline

Wall 2

Dripline

Wall 1

Midyard

Wall 2

Midyard

Play area Under Play

Equipment

Soil Sample Location

Soil Lead Concentration (ppm)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-6 October 31, 2002 

Table 6.3 Estimated Empirical Distribution Parameters of Soil Lead Concentrations by Sample 

Site 

Main Entry Wall 1 

Dripline 

Wall 2 

Dripline 

Wall 1 

Midyard 

Wall 2 

Midyard 

ppm ppm ppm ppm ppm 

Arithmetic Mean 234.8 242.9 404.1 87.3 123.4 

Arithmetic Standard Deviation 1,094.4 817.6 1,612.7 194.7 360.4 

Geometric Mean 43.3 44.5 49.0 28.1 29.9 

Geometric Standard Deviationa 5.6 5.8 6.8 4.3 4.9 

25th Percentile 12.1 11.4 10.8 7.8 8.5 

Median 40.2 38.8 40.3 27.0 29.1 

75th Percentile 133.4 130.7 165.4 76.3 74.2 

90th Percentile 433.5 553.5 712.5 209.0 277.0 

95th Percentile 1,005.8 1,110.8 1,444.5 411.3 538.8 

Number of Samples 707 704 704 723 728 

a The geometric standard deviation is computed as exp(s), where s is the arithmetic standard deviation of the natural logarithms of 

the concentrations (see, e.g., Gilbert, R. O. (1987) Statistical Methods for Environmental Pollution Monitoring, Van Nostrand 

Reinhold Company New York). For the calculations of the geometric mean and standard deviation, zero and negative values 

were set to 5.

6.2 Association between Bare Soil Lead and Exterior Paint Condition 

Table 6.4 and Figure 6.3 show the association between bare soil lead concentration and the 

condition of the exterior LBP. Higher bare soil lead concentrations occur for homes with deteriorated LBP. 

An estimated 56 percent (±8%) of homes with intact or minimally-deteriorated LBP have bare soil lead above 

20 ppm, while 73 percent (±19%) of homes with significantly deteriorated LBP have bare soil levels above 20 

ppm. Only 4 and 2 percent of homes free of significantly deteriorated LBP have bare soil lead levels above 

1,200 and 2,000 ppm, respectively, while 24 and 13 percent of homes with significantly deteriorated LBP have 

bare soil lead levels above 1,200 and 2,000 ppm, respectively. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-7 October 31, 2002 

Table 6.4 Association Between Bare Soil Lead Concentration and Presence of Significantly 

Deteriorated Exterior LBP (All Sampled Locations) 

Bare Soil Lead

Housing Units without 

Any Exterior LBPa,b

Housing Units without 

Significantly Deteriorated 

Exterior LBPa,b

Housing Units with 

Significantly Deteriorated 

Exterior LBPa,b

 

Percent

Lower 

95% CIc

Upper 

95% CI Percent

Lower 

95% CI

Upper 

95% CI Percent

Lower 

95% CI

Upper 

95% CI

GEd0 ppm 83% 78% 88% 83% 77% 88% 73% 55% 92% 

GE 20 ppm 49% 41% 56% 56% 48% 63% 73% 54% 92% 

GE 50 ppm 28% 20% 36% 38% 30% 47% 67% 51% 83% 

GE 200 ppm 5% 1% 9% 13% 9% 17% 39% 19% 58% 

GE 400 ppm 3% 0% 5% 8% 5% 11% 30% 11% 49% 

GE 1,200 ppm 1% 0% 3% 4% 2% 7% 24% 7% 41% 

GE 1,600 ppm 1% 0% 3% 2% 1% 4% 17% 4% 30% 

GE 2,000 ppm 1% 0% 2% 2% 0% 4% 13% 2% 24% 

GE 5,000 ppm 0% 0% 0% 1% 0% 2% 8% 0% 17% 

Missinge 0% 0% 0% 30% 0% 0% 1% 0% 5% 

No Bare Soil 14% 10% 19% 15% 11% 20% 22% 3% 41% 

No Soil 3% 0% 6% 2% 0% 4% 4% 0% 9% 

Total 100% 100% 100% 

a “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. b The denominators for the percentages are 66,032,000 HUs without any exterior LBP, 84,215,000 HUs without significantly 

deteriorated exterior LBP, and 11,473,000 HUs with significantly deteriorated exterior LBP. c

 CI = 95% confidence interval for the estimated number or percent. 

d

 GE equals “greater than or equal to.” e Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). “

No soil” means that there was no soil on the property to sample. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-8 October 31, 2002 

Figure 6.3 Association Between Lead in Bare Soil and Deteriorated Exterior Lead-Based 

Paint 

6.3 Prevalence of Bare Soil Lead in Children’s Play Areas 

Table 6.5 presents the number and percentage of housing units with bare soil lead in children’s 

play areas above selected concentration thresholds: 0, 20, 50, 200, 400, 1,200, 1,600, 2,000, and 5,000 ppm. 

Figure 6.4 presents the point estimates as a histogram. An estimated 51 percent (±6%) of homes have bare 

soil lead levels in play areas above the limit of detection.52 An estimated five percent (±3%) of homes with 

play areas have soil lead levels above 400 ppm, while an estimated two percent (±2%) of homes have play 

area soil lead levels above 2,000 ppm. 

Where more than one soil sample was collected from children’s play areas at a home, the 

maximum soil value for housing unit has been used in Table 6.5. The effect of using the average soil lead for 

each housing unit would drive the distribution towards the lower thresholds, i.e. more homes would have lower 

soil lead concentrations.

 

52 The sample limit of detection for this study was determined to be 20 ppm by testing four distinct soil types from among the study samples in accordance 

with EPA Method 3050 procedures. 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

GE 0 GE 20 GE 50 GE 200 GE 400 GE 1,200 GE 1,600 GE 2,000 GE 5,000

Bare Soil Lead Concentration (ppm)

Percent of Housing Units

Housing Units without Any Exterior LBP

Housing Units without Significantly Deteriorated Exterior LBP

Housing Units with Significantly Deteriorated Exterior LBP
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-9 October 31, 2002 

Figure 6.4 Distribution of Maximum Bare Play Area Soil Lead Concentration 

Table 6.5 Distribution of Maximum Soil Lead Concentrations in Children’s Play Areas

 Number of HUs (000)a Percent of HUs (%)b 

Bare Play Area Soil 

Lead 

HUs in 

Estimate Sample 

Lower 

95% CIc

Upper 

95% CI Estimate 

Lower 

95% CI 

Upper 

95% CI 

GEd0 ppm 76,404 69,826 82,982 80% 73% 87% 294 

GE 20 ppm 49,019 42,946 55,092 51% 45% 58% 209 

GE 50 ppm 28,878 25,828 31,929 30% 27% 33% 127 

GE 200 ppm 10,849 7,899 13,800 11% 8% 14% 101 

GE 400 ppm 4,856 2,096 7,616 5% 2% 8% 84 

GE 1,200 ppm 2,493 458 4,529 3% 1% 5% 82 

GE 1,600 ppm 2,078 92 4,063 2% 0% 4% 80 

GE 2,000 ppm 1,777 0 3,871 2% 0% 4% 77 

GE 5,000 ppm 380 0 1,231 0% 0% 1% 1 

No play area 12,368 6,659 18,077 13% 7% 19% 53 

Missinge 6,916 1,862 11,969 7% 2% 13% 23 

Total 95,688 100% 375 a

 “Housing units” are permanently occupied, noninstitutional residential units in which children are permitted to live. 

b All percentages are calculated with total housing units (95,688) as the denominator. c

 CI = 95% confidence interval for the estimated number or percent. 

d GE equals “greater than or equal to.” e

 Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). “

No soil” means that there was no soil on the property to sample. 

0

10

20

30

40

50

<20 20-50 50-200 200-400 400-1200 1200-1600 1600-2000 2000-5000 >5000

Lead Concentrations (ppm)

HUs (%)
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-10 October 31, 2002 

Table 6.6 presents the number and percentage of housing units with bare soil lead concentration 

in children’s play areas by selected thresholds, by housing unit construction year. In general, as the soil lead 

threshold increases, the number of homes meeting the criteria decreases as the housing unit age increases. In 

fact, nearly all newer homes (1960-1998) have bare play area soil lead below 400 ppm. Thus, the data 

suggest that older homes have higher bare play area soil lead concentrations than new homes. Since the 

amount of lead added to commercial residential paint declined from 1940 to 1980, these observations are not 

unreasonable, and have been reported by others.53 

Table 6.6 Distribution of Maximum Soil Lead Concentrations in Children’s Play Areas, by 

Construction Year 

 Number of HUs (000)a Percent of HUs (%)b

Bare Soil Lead 

Concentration 

Before 

1940 

1940 – 

1959 

1960 – 

1977 

1978 – 

1998 

Before 

1940 

1940 – 

1959 

1960 - 

1977 

1978 – 

1998 

GEc0 ppm 14,641 15,953 22,536 23,275 84% 78% 81% 78% 

GE 20 ppm 14,552 13,074 13,238 8,155 83% 64% 48% 27% 

GE 50 ppm 12,562 8,920 4,733 2,664 72% 43% 17% 9% 

GE 200 ppm 6,508 2,804 320 1,217 37% 14% 1% 4% 

GE 400 ppm 3,325 1,469 62 0 19% 7% 0% 0% 

GE 1,200 ppm 1,498 995 0 0 9% 5% 0% 0% 

GE 1,600 ppm 1,082 995 0 0 6% 5% 0% 0% 

GE 2,000 ppm 872 905 0 0 5% 4% 0% 0% 

GE 5,000 ppm 380 0 0 0 2% 0% 0% 0% 

No Play Area 613 102 3,410 2,790 13% 22% 7% 13% 

Missingd 2,222 4,489 1,947 3,710 4% 1% 12% 9% 

Total 17,476 20,544 27,893 29,774 100% 100% 100% 100% 

a “Housing units” are permanently occupied, noninstitutional housing units in which children are permitted to live. b All percentages are calculated with total housing units of that age as the common denominator. c GE equals “greater than or equal to.” d Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). “

No bare soil” means that there was no bare soil in children’s play areas on the property to sample. 

Table 6.7 shows the association between bare play area soil lead concentration and the condition 

of the exterior LBP. Higher bare soil lead concentrations occur in play areas for homes with significantly 

deteriorated LBP. An estimated 46 percent (±7%) of homes with intact or minimally-deteriorated LBP have 

bare play area soil lead above 20 ppm, while 89 percent (±11%) of homes with significantly deteriorated LBP 

have bare soil levels above 20 ppm. Only three percent (±3%) of homes with intact or minimally-deteriorated 

LBP have bare play area soil lead levels above 400 ppm, while 18 percent (±12%) of homes with significantly 

deteriorated LBP have bare soil lead levels above 400 ppm.

 

53 Francek, M. (1992.) Soil lead levels in a small town environment: A case study from Mt. Pleasant, Michigan. Environmental Pollution 76. pp. 251-

257. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-11 October 31, 2002 

Table 6.7 Association Between Bare Soil Lead Concentration and Presence of Significantly 

Deteriorated Exterior LBP, in Children’s Play Areas 

Bare Play Area Soil 

Lead 

Housing Units without Significantly 

Deteriorated Exterior LBP (%)a,b

Housing Units with Significantly Deteriorated 

Exterior LBP (%)a,b

 

Estimate 

Lower 

95% CIc

Upper 

95% CI Estimate 

Lower 

95% CI 

Upper 

95% CI 

GEd0 ppm 79% 71% 86% 90% 79% 100% 

GE 20 ppm 46% 39% 53% 89% 77% 100% 

GE 50 ppm 24% 20% 29% 73% 55% 91% 

GE 200 ppm 8% 4% 12% 35% 17% 53% 

GE 400 ppm 3% 1% 6% 18% 6% 30% 

GE 1,200 ppm 1% 0% 3% 13% 2% 24% 

GE 1,600 ppm 1% 0% 3% 11% 0% 23% 

GE 2,000 ppm 1% 0% 2% 10% 0% 23% 

GE 5,000 ppm 0% 0% 0% 3% 0% 11% 

No Play Areas 14% 7% 20% 7% 0% 17% 

Missinge 8% 2% 14% 3% 0% 7% a “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. b Percentages are calculated with the number of HUs with and without significantly deteriorated LBP, 11,472 and 84,216, 

respectively, as the denominators. c CI = 95% confidence interval for the estimated number or percent. d GE equals “greater than or equal to.” e Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). “

No soil” means that there was no soil on the property to sample. 

6.4 Prevalence of Soil Lead in the Rest of the Yard 

Table 6.8 presents the number and percentage of housing units with soil lead in the rest of the 

yard -- i.e., areas not identified as children’s play areas -- above selected concentration thresholds: 0, 50, 200, 

400, 1,200, 1,600, 2,000, and 5,000 ppm. An estimated 75 percent (±6%) of homes have bare soil lead levels 

in the rest of the yard above the limit of detection.54 An estimated 10 percent (±4%) of homes have soil lead 

levels above 1,200 ppm in the rest of the yard, while an estimated 6 percent (±2%) of homes have soil lead 

levels above 2,000 ppm. 

 

54 The sample limit of detection for this study was determined to be 20 ppm by testing four distinct soil types from among the study samples in accordance 

with EPA Method 3050 procedures. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-12 October 31, 2002 

Table 6.8 Distribution of Maximum Soil Lead Concentrations in the Rest of the Yard

Soil Lead Concentration Number of HUs (000)a Percent of HUs (%)b

 

Estimate 

Lower 

95% CIc

Upper 

95% CI Estimate 

Lower 

95% CI 

Upper 

95% CI 

HUs in 

Sample 

GEd 0 ppm 90,348 87,218 93,479 94% 91% 98% 323 

GE 20 ppm 71,537 65,843 77,230 75% 69% 81% 258 

GE 50 ppm 54,250 48,525 59,976 57% 51% 63% 162 

GE 200 ppm 27,353 25,438 29,267 29% 27% 31% 116 

GE 400 ppm 19,709 16,109 23,310 21% 17% 24% 70 

GE 1,200 ppm 9,939 6,435 13,444 10% 7% 14% 53 

GE 1,600 ppm 6,220 4,034 8,407 7% 4% 9% 49 

GE 2,000 ppm 5,905 3,727 8,083 6% 4% 8% 38 

GE 5,000 ppm 2,987 1,548 4,427 3% 2% 5% 17 

No Soil/No Bare Soile 2,310 366 4,254 2% 0% 4% 9 

Missinge 3,029 693 5,365 3% 1% 6% 12 

Total 95,688 100% 375 

a

 “Housing units” are permanently occupied, noninstitutional residential units in which children are permitted to live. 

b All percentages are calculated with total housing units (95,688) as the denominator. c

 CI = 95% confidence interval for the estimated number or percent. 

d GE equals “greater than or equal to.” e

 Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). “

No soil” means that there was no soil in the rest of the yard to sample. “No bare soil” means there was no bare soil in the rest 

of the yard. 

Table 6.9 presents the number and percentage of housing units with soil lead concentration in the 

rest of the yard by selected thresholds, and by housing unit construction year. In general, as the soil lead 

threshold increases, the number of homes meeting the criteria decreases as the housing unit age increases. In 

fact, nearly all (91%) homes built between 1960 and 1977 have bare soil lead concentrations below 400 ppm 

in the rest of the yard. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-13 October 31, 2002 

Table 6.9 Distribution of Maximum Soil Lead Concentrations in the Rest of the Yard, by 

Construction Year 

Number of HUs (000)a Percent of HUs (%)b Bare Soil Lead 

Concentration Before 

1940 

1940 - 

1959 

1960 - 

1977 

1978 - 

1998 

Before 

1940 

1940 – 

1959 

1960 - 

1977 

1978 – 

1998 

GEc0 ppm 15,858 19,372 26,950 28,168 91% 94% 97% 95% 

GE 20 ppm 15,858 18,947 24,151 12,581 91% 92% 87% 42% 

GE 50 ppm 15,350 17,492 13,509 7,900 88% 85% 48% 27% 

GE 200 ppm 13,051 9,524 4,430 348 75% 46% 16% 1% 

GE 400 ppm 11,255 5,960 2,410 84 64% 29% 9% 0% 

GE 1,200 ppm 6,326 2,926 686 0 36% 14% 3% 0% 

GE 1,600 ppm 4,245 1,289 686 0 24% 6% 3% 0% 

GE 2,000 ppm 3,929 1,289 686 0 23% 6% 3% 0% 

GE 5,000 ppm 1,891 865 231 0 11% 4% 1% 0% 

No Soil/No Bare Soile 1,211 939 160 0 7% 5% 1% 0% 

Missingd 407 233 783 1,606 2% 1% 3% 5% 

Total 17,476 20,544 27,893 29,774 100% 100% 100% 100% 

a “Housing units” are permanently occupied, noninstitutional housing units in which children are permitted to live. b All percentages are calculated with total housing units of that age as the common denominator. c GE equals “greater than or equal to.” d Missing means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent refusal). e “

No soil” means that there was no soil in the rest of the yard to sample. “No bare soil” means there was no bare soil in the rest 

of the yard. 

6.5 Comparison of Prevalence of Soil Lead to the 1990 LBP Survey 

Table 6.10 compares the prevalence of soil lead found in the NSLAH with the prevalence of soil 

lead found in the 1990 LBP Survey. The estimate of homes reported for the NSLAH have been limited to 

those with 500 ppm55 soil lead or greater and to homes built before 1980 for comparability to the 1990 LBP 

Survey protocols and findings (see Appendix B for a comparison of the protocols for the two studies). 

Statistical comparison shows no significant difference in the prevalence of soil above or below 500 ppm in the 

two studies. 

 

55 At the time the 1990 LBP survey was conducted, 500 ppm was the guideline in EPA's Interim Guidance on Establishing Soil Lead Cleanup Levels at 

Superfand Sites, September 7, 1989 (OSWER Directive #9355-4-02). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT 6-14 October 31, 2002 

Table 6.10 Comparison of the Prevalence of Lead-Contaminated Bare Soil in the NSLAH and the 1990 

LBP Survey 

1990 LBP Survey 

(pre-1980 HUs) 

Current NSLAH 

(pre-1980 HUs) 

Number 

(000) 

Percent 

(%) 

Number 

(000) 

Percent 

and (CI) a (%)

HUs with Bare Soil Lead 

Above 500 ppm 

15,699 20% 15,909 23% 

(19-27%) 

HUs with Bare Soil Lead 

Equal to or Below 500 ppm 

61,478 80% 50,290 73% 

(70-77%) 

No Bare Soil -- -- 2,557 4% 

Total 77,177 100% 68,756 100% 

a

 CI = 95% confidence interval for the estimated percent.
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-1

7. QUALITY OF THE NATIONAL SURVEY DATA 

Chapter 7 examines the quality of the data and the resulting quality of projected national 

estimates. The greatest source of error (in the statistical sense) in the NSLAH estimates is sampling error – 

as discussed in Volume II, Chapter 2. This chapter addresses two additional important potential sources of 

error – nonresponse bias and measurement bias – and discusses their effects on the national estimates of the 

prevalence of lead-based paint (LBP), lead in dust, and lead in soil.56

The chapter concludes with a summary of the data collection quality assurance activities, 

including results of telephone verification, field team audits, field dust and soil quality control samples, 

laboratory performance on dust and soil quality control samples, and paint testing quality control. 

7.1 Statistical Concepts and Terminology 

There are two broad types of error in survey estimates: sampling error and nonsampling error: 

 Sampling error: Sampling error arises from surveying a random sample rather 

than a complete census of all housing units (HUs). It is a function of the sample 

size and sample design. Different samples of the same size drawn using the same 

sample design will yield varying estimates of the population parameters. This 

variation about the true population parameter is the sampling error. 

 Nonsampling error: Nonsampling errors arise from a number of sources, 

including differential response rates from different demographic groups, types of 

HUs, and geographical areas; unknown differences between the respondents and 

nonrespondents; differences between the sample frame and the target population; 

some types of processing and data reduction techniques; and classification bias 

due to measurement error inherent in XRF and laboratory instrumentation and 

variation in a measured parameter across a surface and among rooms. 

Throughout the report, the term weight has been used in conjunction with the sampled HUs, 

rooms, and surfaces. It is important that these terms be understood. 

 

56 Another source of error in the survey is response bias, i.e., how correct was the information provided by the respondents? Significant information 

obtained from respondents included year of construction (HU age) and age of children. These data were not verified by other means and are thus 

associated with an unknown amount of error. However, the overall distribution of HU age and age of children reported by survey respondents were 

consistent with study expectations (see Volume II, Chapter 2), indicating no systematic bias in these responses. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-2

 Housing Unit (HU) weight: The HU weight is the number of HUs in the target population 

that a single HU in the survey represents. The weight is calculated by taking the inverse of the 

probability of selection for that unit. Thus, if the probability of selection is 0.01, the sample 

weight is 100. With multi-stage samples, the overall probability of selection is the product of 

the conditional probabilities of selection at each stage. HU weights for this survey reflect 

nonresponse adjustments and post-stratification to the 1997 American Housing Survey (AHS) 

housing unit totals by Census region, HU age category, and presence of children under age 

18. 

 Room weight: The room weight is the number of rooms in the target 

population that a single room in the survey represents. Room weights were 

determined by dividing the post-stratified HU weights by the probability of room 

selection based on the inventory of all rooms in each HU. A nonresponse 

adjustment was then made to account for noncompleted rooms. A room was only 

considered to be complete if some environmental samples and data were collected 

in the room. 

 Component weight: The component weight is the number of components in 

the target population that a single component tested in the survey represents. For 

most lead samples, the component weight equaled the nonresponse-adjusted room 

weight. There were two exceptions: 1) XRF measurements on windows and 

doors, and 2) window dust samples. For these components, a sample of one door 

or window per room was selected. To complete component weights for these 

components, the nonresponse-adjusted room weights were divided by the 

component probability of selection, i.e., the inverse of the total number of doors 

or windows in the room. 

7.2 Potential for Nonresponse Bias 

The objective of the nonresponse analysis was to estimate the potential impact of survey 

nonresponse on the estimated prevalence of LBP in housing. To accomplish this, three analyses were 

conducted. First, the weighted distribution of the NSLAH sample was compared and found to be 

comparable with the AHS and CPS (this analysis was presented in Chapter 2). Second, an analysis of 

completion rates was performed to look for correlates with nonresponse. Third, the survey estimates for the 

“hard-to-recruit” and HUs that initially refused (proxies for the nonrespondents) were compared with 

estimates from HUs that were relatively easy to recruit and had no history of refusal. 

7.2.1 Analysis of Completion and Response Rates 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-3

An analysis of completion rates was conducted for the entire sample of 1,984 fielded HUs. 

The analysis looked at the relationship between completion rates and factors such as age of housing, race, 

ethnicity, geographic location, income, tenure, and presence of multi-family housing. Given that these data 

were generally not available at the individual HU level for the noncompletes, data for the block group to 

which the HU belonged was used for the entire sample, with the exception of HU age. The housing unit 

age reported by respondents was used when available, which was the case for approximately one-half of the 

HUs. The source of the block group data was the 1990 Census. Completion rates were also compared for 

HUs receiving an advance letter addressed to "Current Resident" and HUs receiving a letter addressed to a 

household member. 

The completion rates for the analysis were calculated as the weighted proportion of the HUs 

sampled that completed both screener and data collection, or else were found to be ineligible. Ineligibles 

were considered to be screener completes in the sense that their eligibility status was determined during the 

screener. For a large proportion of the sample (39%), eligibility could not be determined, usually because 

contact could not be made. Most nonresponse occurred at the screener stage and resulted in unknown 

eligibility status. Of the 1,984 HUs sampled, 831 completed both the screener and data collection and 229 

were found to be ineligible. Of the remaining 924 that did not complete the data collection, 149 were 

eligible and another 775 were of unknown eligibility. Thus, there were 1,060 completes and 924 

noncompletes overall. The overall unweighted completion rate for the survey was 53.4 percent; the overall 

weighted completion rate was 53.1 percent. 

Formulas for unweighted screener and data collection completion rates are given below, along 

with the eligibility rate, refusal rate, and overall response rate. The overall completion rate is calculated as 

the product of the completion rate at each stage. 57

59%

1,984

943 229 100% x 

# fielded

# screener completes # ineligible Screener completion rate 100% x = + = + =

90%

1,172

1,060 100% x 

# eligible completing screener # ineligible

# eligible completing data collection # ineligible Data collection completion rate 100% x = = +

+ =

 

57 In the data collection completion rate, the ineligible cases are included in both numerator and denominator. If the ineligible cases are not included, 

the data collection completion rate drops from 90 to 88 percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-4

The overall response rate measures the response among eligible HUs. The number of eligible 

nonrespondents must be estimated because eligibility cannot usually be established for households that 

don’t complete the screener. It is assumed that the eligibility rate among HUs whose eligibility is unknown 

is the same as for HUs that did complete the screener. The eligibility rate among HUs that completed a 

screener was 81 percent. The refusal rate is the rate of refusal among HUs where contact was established. 

(Numerous attempts were made to gain cooperation. Among respondents, two-thirds cooperated on the 

first or second attempt. While the average number of attempts to complete was 2.6, some housing units 

didn’t cooperate until the eleventh attempt.) HUs that were vacant or couldn't be located, that had no one 

at home, that were in a locked, gated community where access couldn't be gained, or that couldn't otherwise 

be contacted were subtracted from the total sample size of 1,984 in the denominator. The overall response 

rate for the survey was 51.7 percent. 

 Eligibility Rate # Eligible 943 100% x 100% x 81%

# Eligible # Ineligible 943 229 = == + +

 Refusal Rate # of refusals 564 100% x 100% x 34.5%

# contacted 1,634 = ==

 Overall Response Rate # eligible completing data collection 100% x 

# eligible completing data collection # eligible nonrespondents = +

 831 51.7%

831 (149 .81*775) = = + +

Overall completion rates by Census Division and block group characteristics such as 

race/ethnicity, housing age, and type of housing are presented in Table 7.1. Mean percents for several 

characteristics by completion status are given in Table 7.2. For housing age, the predominant building age 

category for the block group was assigned to the HU, except when HU age was available from survey 

respondents. It is important to keep in mind that (with the exception of HU age) the characteristics apply 

only to the block group in which the HU is located, and may not apply to the HU itself. The associations 

between completion status and these characteristics were tested using chi-square and t-tests that take into 

account the HU weights and the survey design. 

Significant associations were found between completion status and percents Hispanic and 

African American, percent below the federal poverty level, housing age, and tenure (see Table 7.2). 
National Survey of Lead Final Report, Vol. I 

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WESTAT October 31, 2002 7-5

Different completion rates for groups within a category cannot always be explained, but could be due to 

factors such as the use of incentives, attitudes of householders, etc. In Table 7.1, the highest response rates 

were found among HUs in block groups with 30 percent or more Hispanic population, 30 percent or more 

in poverty, and in newer housing (1978 or later). The differences in response rates are substantial for these 

characteristics, ranging from 9 to 14 percentage points or more (possibly a function of the $200 incentive 

having greater value for these households). This means that if the lead outcome variables are correlated 

with any of these characteristics (such as housing age), a greater potential for nonresponse bias would exist 

had these characteristics not been used in adjusting for nonresponse at the screener and data collection 

stages. Nonresponse adjustment factors were calculated within cells defined by the block group percent of 

low-income population, percent of Hispanic or African American population, and percent of pre-1940 and 

pre-1960 housing. In addition, the nonresponse-adjusted HU weights were poststratified to 1997 AHS 

housing unit totals by Census region, housing unit age, and presence of a child under 18. Use of the final 

adjusted weights in all analyses therefore greatly reduces this potential bias in estimates for the national 

housing stock. 

The presence or absence of a household member name on the advance letter was also 

significantly correlated with completion rates. For HUs located in higher income block groups (i.e. fewer 

than 30 percent of the households are below the federal poverty level), the response rate for HUs with a 

name on the advance letter was significantly lower (p = .01) than for HUs receiving a letter addressed to 

"Current Resident" (48% vs. 56%). For HUs located in lower income block groups (i.e. more than 30 

percent of the households are below the federal poverty level), however, the completion rates were not 

significantly different. 

Response rates for the play areas sample were also calculated using the above formula. 

Weighted and unweighted response rates were examined in the same manner, but given the smaller sample 

size the characteristics were restricted to Census Region, building age category, and soil lead. The national 

response rate for the play areas survey was 79.5 percent weighted and 78.0 percent unweighted (higher 

than the national survey since we were returning to previously willing HUs). For each subset, the response 

rate remained between 71 and 85 percent. None of the response rate differences observed for the play areas 

survey were statistically significant at the alpha = .10 level. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-6

Table 7.1 Completion Rates by 1990 Census Block Group Characteristics 

 Unweighted Weighted P-Value for 

1990 Census 

Block Group Characteristic 

Number of 

HUs 

Completion 

Rate 

Completion 

Rate 

Chi-square 

testa

Census Division 

New England 102 52% 53% 0.42 

Middle Atlantic 289 53% 49% 

East North Central 289 49% 46% 

West North Central 181 55% 55% 

South Atlantic 326 52% 53% 

East South Central 144 53% 54% 

West South Central 208 56% 58% 

Mountain 136 57% 58% 

Pacific 309 56% 57% 

% Hispanic Population 

Less than 30% Hispanic 1832 52% 52% 0.005 

30% or more Hispanic 152 65% 65% 

% African American Population 

Less than 30% African American 1731 52% 53% 0.08 

30% or more African American 253 60% 59% 

% Population in Poverty 

Less than 30% in Poverty 1796 53% 52% 0.04 

30% or more in Poverty 188 60% 61% 

% Multi-family Housing Units (5+) 

Less than 30% Multi-family HUs 1522 53% 53% 0.42 

30% or more Multi-family HUs 462 56% 55% 

Age of Housing Unitb 

Pre-1940 456 48% 45% <0.001 

1940 – 1959 363 59% 60% 

1960 – 1977 806 47% 45% 

1978 and later 359 70% 74% 

a Chi-square test between completion rate and housing characteristic - takes into account the HU weights and sample design. b Reported HU age used when available for HUs completing screener. 
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WESTAT October 31, 2002 7-7

Table 7.2 Mean Percents for Completed and Noncompleted Housing Units by 1990 Census Block 

Group Characteristics 

1990 Census Block Group Mean of Characteristic 

Characteristic Completes Noncompletes 

P-value for t-test between 

completes and noncompletesa

Percent HUs Pre-1940b 18% 25% 0.001 

Percent Population below Poverty Level 12% 11% 0.080 

Percent Multi-Family HUs (5+) 17% 16% 0.535 

Percent Multi-Family HUs (20+) 7% 7% 0.908 

Percent HUs Owned 63% 66% 0.042 

Percent Population: African American 11% 8% 0.006 

Percent Population: Hispanic 8% 5% 0.005 

a The test takes into account the HU weights and sample design. b HU age reported by respondents was used when available for HUs completing screener. 

7.2.2 Comparison of “Hard-to-Recruit” Versus “Easy-to-Recruit” HUs 

Lead measurements were not available for the HUs whose occupants refused to participate in 

the survey or who could not be contacted, so it is not possible to know how their participation would have 

changed the estimates of lead prevalence in housing. However, if the HUs that initially refused but later 

cooperated (or those HUs requiring several attempts to complete the screener) are similar to the survey 

nonrespondents, they may be considered as a proxy group for the nonrespondents. If they are significantly 

different, this may indicate the likely direction of the nonresponse bias in the lead prevalence estimates. 

The initial refusals were compared with HUs with a history of no refusal. HUs requiring 4 or 

more attempts to complete the screener were also compared with those requiring 3 or fewer attempts. The 

number of attempts was split at 3-4 for two reasons. Two-thirds of respondents cooperated on the first or 

second attempt and the average number of attempts to complete was 2.6. The comparisons were made for 

four key statistics and by the housing characteristics recorded by the interviewer. The statistics were 1) the 

presence of LBP anywhere in the home, 2) the presence of deteriorated LBP anywhere in the home, 3) 

presence of LBP hazard anywhere in the home, and 4) the presence of a soil lead hazard. The housing 

characteristics were the respondent's race/ethnicity, household income, tenure, building age, and presence of 

a child under 18. Comparison of whether or not the household had initially refused (or required more than 

three attempts to obtain a completed screener) and these characteristics is presented in Table 7.3. 
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WESTAT October 31, 2002 7-8

Table 7.3 Comparison of “Easy-to-Recruit” Respondents Versus “Hard-to-Recruit” Respondents 

National Survey Estimates

Initial 

Refusal 

(%) 

p-valuea

More than 3 Attempts 

to Complete Screener 

(%) 

p-valuea

Presence of LBP anywhere in HU 

Yes 9.2 0.60 17.3 0.67 

No 10.0 15.1 

Presence of Significantly Deteriorated LBP 

anywhere 

 

Yes 6.0 0.05 12.8 0.29 

No 10.4 16.7 

Presence of Significant LBP Hazard in HU 

Yes 5.6 0.0007 15.8 0.84 

No 11.6 16.5 

Presence of Soil-Lead Hazard 

Yes 8.7 0.85 6.2 0.29 

No 9.9 16.7 

Ethnicity 

Hispanic 10.7 0.78 9.6 0.14 

Non-Hispanic 9.7 16.8 

Race 

White 10.2 0.38 16.9 0.12 

African American 6.7 11.7 

Asian, Pacific Islander, Hawaiian, 8.9 14.4 

American Indian, Other 

Presence of Child under 18 

Yes 9.9 0.85 15.1 0.31 

No 9.5 16.6 

Year of Construction 

Pre-1940 7.2 0.22 18.6 0.18 

1940 – 1959 6.1 11.5 

1960 – 1977 12.1 13.3 

1978 or later 11.4 20.2 

Tenure (moved up to be w/hsg info) 

Owned 11.2 0.03 15.8 0.15 

Rented 6.3 16.8 

Type of Housing 

Single-family 10.3 0.02 15.4 0.58 

Multi-family 5.8 19.9 

Household Income 

Less than $30,000 4.7 <0.0001 12.3 0.03 

$30,000 or More 11.7 17.8 

Household Income 

Less than $20,000 4.7 0.05 11.1 0.02 

$20,000 - $39,999 6.8 15.6 

$40,000 - $59,999 10.9 16.8 

$60,000 and over 13.5 18.9 

Poverty 

Below Poverty Level 4.6 0.003 9.9 0.005 

At or Above Poverty Level 9.8 17.0 a Chi-square test of association between Ease of Recruitment and Reported Housing Characteristics.
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-9

Table 7.3 shows that poorer households were much less likely to have an initial refusal, and 

required fewer attempts to obtain a completed screener. This is consistent with earlier analysis showing 

higher response rates for lower income households. It could be that the monetary incentive was more 

effective among lower income households in improving response rates, or that higher income HUs were 

more difficult to contact. 

Table 7.3 also shows that households with LBP, significantly deteriorated LBP, significant 

LBP hazard, or soil lead hazard were just as likely to require more than three attempts to complete the 

screener as those without these lead characteristics. While households with LBP or soil hazards were just 

as likely to initially refuse as other households, those with significantly deteriorated LBP or LBP hazards 

were significantly more likely to initially refuse than those without these characteristics. This could be due 

to the fact that more lower income homes participated in the survey and lower income homes are more 

likely to have these characteristics. 

The nonresponse analysis shows that the households that responded were more likely to be 

located in densely Hispanic and low income areas, and to be renters as opposed to home owners. They are 

also more likely to live in newer housing (post-1977). 

If the initial refusals who agreed to cooperate are representative of nonrespondents, there 

would be a potential for bias in unweighted estimated prevalence of HUs with deteriorated LBP or LBP 

hazards. This means that there would be a potential for bias in the estimated prevalence of HUs with an 

LBP hazard. However, this was partially corrected by using race/ethnicity, low-income indicators, and 

building age in making nonresponse adjustments to the HU weights. The weighting adjustments do not 

eliminate nonresponse bias completely, but they do reduce it when variables that are correlated with both 

the response rates and propensity to have a lead hazard are used in the nonresponse adjustments. 

Comparison of the nonresponse-adjusted and poststratified weighted distribution of housing from the 

National Survey with the AHS and CPS in Table 2.1 show that the weighted National Survey sample 

matches the national housing distribution closely. These results suggest that there is probably not a serious 

nonresponse bias in the weighted estimates of lead hazard prevalence. 

7.2.3 Completion Rates in the Play Area Subsample 

In the play area subsample, 40 of the 75 PSU’s were selected and all previously completed 

homes were selected for revisiting. There were 481 homes in the 40 PSU’s. Table 7.4 displays the yield in 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-10

this subsample. In the play area subsample, 78 percent of the homes were completed, either with the 

collection of a play area soil sample, or the determination that one was not necessary. 

Table 7.4. Completions in Play Area Subsample 

Result Number of HUs Percent of HUs 

Complete, no soil sample needed 178 37% 

Complete, new soil sample collected 197 41% 

Total completes 375 78% 

No contact made with respondent 54 11% 

Refusal 12 2% 

Demolished 1 0% 

Vacant 27 6% 

Other 12 2% 

Total Housing Units 481 100% 

7.3 Quality of Field Data Collection and Analysis 

Quality assurance was integrated into all components of the study, including a defensible 

study design, experienced project personnel, utilization of well-planned, detailed and tested protocols for all 

aspects of data collection, thorough study-specific training of experienced field staff, electronic sample and 

data management, and ongoing communication between individuals responsible for each stage of the study. 

These procedures are described in detail in Volume II, Chapter 6. 

Four types of replicate sampling were conducted to estimate measurement error: replicate 

XRF testing of one random component per room, replicate dust sampling of one surface per home, replicate 

soil sampling at a different sample site at every third home, and replicate room sampling at a subset of 

homes. The analyses utilizing these replicate data and resultant measurement error estimates are presented 

in Appendix C. 

This section summarizes the results of the various activities focussed at ensuring quality of 

the field data collection and laboratory analysis of the environmental samples. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-11

7.3.1 Field Data Collection 

A number of procedures were instituted to ensure quality of the field data collection, including 

a manual edit of all data and samples by the field team, review by the Field Supervisor upon return of the 

data to Westat headquarters, and reconciliation of any errors with the field team prior to submission of any 

samples to the laboratory. In addition, random telephone verification and field team audits were conducted; 

dust sample material screens were analyzed; and dust blanks and spike samples and blind soil reference 

samples were included in the sample stream. 

 Telephone Verification of Data Collection 

The Field Director contacted a random subsample of 82 (10%) households by telephone to 

verify the team’s activities and conduct and to validate selected information from the data forms. No field 

problems were identified by this process. 

In addition to the random verification process, a number of respondents and potential 

respondents utilized the toll-free phone number, or the HUD phone number, to ask questions, verify the 

survey, and express concerns. All questions or concerns were answered or addressed by the Field Director 

or HUD. 

 Random Field Audits 

The QA Officer or designee, and HUD and NIEHS representatives, conducted random field 

audits at 31 households to verify that the protocols were followed and data collection was accurate and 

complete. In addition to the field audits, the QA Officer conducted 17 telephone audits to ascertain the 

team members’ understanding of the protocols, especially when more than two months had elapsed between 

assignments. Problems noted during these audits were corrected directly with the individual team members. 

In addition, the results of audits were immediately relayed to the Field Office. As appropriate, all field 

staff were notified by memo of any issues identified with the protocols. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-12

 Lead Dust Wipe Sample Collection 

 Lead Dust Wipe Materials Screens 

The purpose of a materials screen was to verify that the various sampling supplies to be used 

in the field did not have lead contamination. Two screens were prepared and analyzed for every lot of wipe 

materials and sample tubes before being used in the study. The analyses showed that all material screens 

had below 1.5 μg lead.58

 Field Blank Wipes 

One field blank wipe was prepared for each HU at a specified random sample location where 

another wipe sample was collected. All field blanks were below 50 μg lead/wipe, as specified in HUD 

Guidelines. Most field blanks (98+% of all field blanks) had lead levels below the detection limit for the 

analytical run (approximately 3.5 μg lead/wipe). Of 15 field blanks with lead values above 3.5 μg 

lead/wipe, only one blank had more than 20 μg lead/wipe; this wipe had 43 μg lead and was collected in a 

home with elevated window sill and trough lead dust levels. Data from this home were used in the survey 

since the blank was still below the 50 μg guideline. 

 Reference (Spike) Sample Dust Wipes 

Reference wipe samples were made in advance of the fieldwork by placing a known quantity 

of National Institute of Standards and Technology’s Standard Reference Material (NIST SRM) 1579a on 

the same wipe material used in the study. The reference wipes were labeled like a regular sample so that 

the laboratory was blinded to fact that these were quality control samples. The Field Office inserted one 

reference wipe sample with each group of 50 samples before sending samples to the laboratory. A total of 

206 reference wipes, ranging from 21 to 516 μg lead/wipe, were submitted over the course of the study. 

The average reference sample recovery was 96% (range from 83% to 115%) with a standard deviation of +

5.25 percent. With a few exceptions, all sample recoveries were within the HUD Guidelines acceptable 

range of 80 to 120 percent. The laboratory was requested to re-analyze those batches with values outside 

acceptable limits. Recoveries were acceptable on the second run (see Section 6.7 of Volume II) and the 

second set of data was used for the entire batch of samples. 

 

58 EPA’s National Lead Laboratory Accreditation Program (NLLAP) requires wipes to be used in the field to have less than 5 μg lead/wipe. 
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and Allergens in Housing Analysis of Lead Hazards 

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 Soil Quality Control Samples 

 Reference Soil Samples 

Reference soil samples were purchased before the fieldwork began. The Field Office labeled 

and included one reference sample with each group of samples from every three households (approximately 

one sample in ten). A total of 83 soil reference samples were submitted to the laboratory. The average 

recovery was 104% (range 84% to 121%) with a standard deviation of + 8.04 percent. Two analytical 

batches contained a reference sample with a recovery of 121%, exceeding the control limits of 80 to 100 

percent. The laboratory was requested to re-analyze these batches. Recoveries were acceptable on the 

second run (see Section 6.9, Volume II) and the second set of data was used for the entire batch of samples. 

Two types of reference soil samples were used: urban soil provided by University of 

Cincinnati (640, 3,132, and 6,090 ppm lead), and NIST SRM 2709 (San Joacquin soil, 18.9 ppm lead) and 

SRM 2711 (Montana soil, 1,162 ppm lead). It is interesting, but not unexpected, that the average recovery 

of 89% for the NIST Montana soil was lower than the average of 105% for the urban soils. Lead in urban 

soils tends to be from more leachable sources (i.e. paint, past automobile emissions, industrial facilities).59

7.3.2 Laboratory Quality Control Samples 

Each laboratory provided quality assurance procedures during the selection and qualification 

process. These approved procedures (outlined in the National Survey’s Protocol and Sample Design 

Report, June, 1999) were adhered to for all study samples. In general, the laboratories performed 

instrumental and duplicate quality control analyses, as required by ASTM E 1613-94 and the American 

Industrial Hygiene Association’s Environmental Lead Laboratory Accreditation Program (ELLAP) Quality 

Manual and Policies, to ensure that the original calibration solutions were accurate, the instruments were 

properly zeroed, instrumental drift was not excessive, and carryover between samples did not occur. These 

included duplicate injections of the same sample, method blanks, and spiked samples at a minimum 

frequency of five percent of the samples. 

 

59 Personal communication with Sandy Roda, Director, Hematology and Environmental Laboratory, University of Cincinnati. 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT October 31, 2002 7-14

7.3.3 Laboratory Selection Quality Assurance 

The laboratories used for analysis of dust and soil samples, respectively, were recognized by 

the EPA under its National Lead Laboratory Accreditation Program (NLLAP) for those analyses 

throughout the laboratory qualification and performance phases of the National Survey. This recognition 

provided assurance of the quality of laboratory performance of lead analyses and reporting. In addition, 

the laboratories were accredited by the American Industrial Hygiene Association; this accreditation 

provided a separate assurance of the quality of laboratory management and performance of environmental 

analyses and reporting. 

7.4 Paint Testing Quality Assurance 

Calibration of the XRF analyzer was performed before and after testing in every home. In no 

case was the instrument used if the calibration criteria were not met, i.e. the analyzer read 0.0 mg/m2 on the 

0.0 film and between 0.9 and 1.2 mg/m2 on both the front and back of the 1.0 film. In addition, the average 

of three readings on the front of the 1.0 film was between 0.9 and 1.2 mg/m2

. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-1 October 31, 2002 

APPENDIX A 

Selected Additional Tables and Figures 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-2 October 31, 2002 

Figure A.1 Prevalence of Significant LBP Hazards, Soil Lead Threshold at 2,000 ppm and 

at 1,200 ppm 

0

5,00010,00015,00020,00025,00030,000

All Occupied Housing Units

Midwest

West

Built 1960-1977

Built Before 1940

Income < $30,000/year

African American Household

Households with Children < 6 Years Subpopulation of Housing Units

Housing Units (000) with Significant LBP Hazards

2,000 ppm

1,200 ppm
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-3 October 31, 2002 

Table A.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, by 

Selected Characteristics, for Alternative Soil Lead Threshold of 2000 ppm 

HUD Lead Safe Housing Rule: Significant LBP Hazardsa

Characteristic All HUs

(000)b

No. of HUs with Significant 

LBP Hazards (000) 

Percent of HUs with 

Significant LBP Hazards 

(%)c

HUs in 

Sample

 Estimate Lower 

95% CId

Upper 

95% CI Estimate Lower 95% CI 

Upper 

95% CI 

Total Occupied HUs 95,688 25,517 20,410 30,623 27% 21% 32% 375 

Region: 

Northeast 19,290 8,260 5,904 10,616 43% 31% 55% 95 

Midwest 22,083 7,606 5,691 9,521 34% 26% 43% 102 

South 35,474 6,082 3,161 9,003 17% 9% 25% 111 

West 18,841 3,569 1,003 6,135 19% 5% 33% 67 

Construction Year: 

1978-1998 29,774 425 0 1,222 1% 0% 4% 88 

1960-1977 27,874 2,843 317 5,370 10% 1% 19% 111 

1940-1959 20,564 10,501 7,996 13,006 51% 39% 63% 97 

Before 1940 17,476 11,747 8,771 14,723 67% 50% 84% 79 

Urbanization 

MSA >= 2 million 

population 

26,814 6,793 4,978 8,609 25% 19% 32% 276 

MSA =< 2 million 

population 

45,753 10,232 8,171 12,293 22% 18% 27% 417 

Non-MSA 23,121 7,001 3,848 10,153 30% 17% 44% 138 

One or More Children 

Under Age 6: 

 

All HU ages 16,402 5,652 3,758 7,546 34% 23% 46% 83 

HUs built 1978-1998 5,847 364 0 1,127 6% 0% 19% 25 

HUs built 1960-1977 5,098 371 0 987 7% 0% 19% 20 

HUs built 1940-1959 3,055 2,662 1,554 3,770 87% 51% 123% 22 

HUs built before 1940 2,401 2,255 502 4,007 94% 21% 167% 16 

Housing Unit Type: 

Single family 82,651 23,204 17,794 28,614 28% 22% 35% 319 

Multi-family 13,037 2,313 0 5,143 18% 0% 39% 56 

Occupant Status: 

Owner-occupied 62,232 16,013 12,647 19,380 26% 20% 31% 254 

Renter-occupied 29,074 9,503 5,906 13,100 33% 20% 45% 119 

Refusal/Don’t Knowe 381 2 

Household Income: 

Less than $30,000/year 33,830 13,998 8,938 19,057 41% 26% 56% 145 

Equal to or more than 

 $30,000/year 

56,111 10,060 7,151 12,970 18% 13% 23% 211 

Refusal/Don’t Know 5,747 19 

One or More Children 

Under Age 6: 

 

All Income Categories 16,402 5,652 3,758 7,546 34% 23% 46% 83 

Less than $30,000/year 4,791 1,646 0 3,460 34% 0% 72% 28 

Equal to or more than 

 $30,000/year 

11,236 4,006 1,797 6,214 36% 16% 55% 52 

Refusal/Don’t Know 375 3 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-4 October 31, 2002 

Table A.1 Prevalence of Housing Units with Significant Lead-Based Paint (LBP) Hazards, by 

Selected Characteristics, for Alternative Soil Lead Threshold of 2000 ppm 

(continued) 

HUD Lead Safe Housing Rule: Significant LBP Hazardsa

Characteristic All HUs

(000)b

No. of HUs with Significant 

LBP Hazards (000) 

Percent of HUs with 

Significant LBP Hazards 

(%)c

HUs in 

Sample

 Estimate Lower 

95% CId

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI 

Government Support: 

Government support 4,809 822 10 1,634 17% 0% 34% 25 

No government support 86,070 23,571 19,114 28,028 27% 22% 33% 327 

Refusal/Don’t Know 4,809 23 

Poverty: 

In Poverty 13,221 5,053 2,542 7,565 38% 19% 57% 54 

Not in Poverty 76,336 18,669 14,396 22,942 24% 19% 30% 300 

Refusal/Don’t Know 6,130 21 

Race: 

White 77,005 19,164 14,972 23,356 25% 19% 30% 285 

African American 10,365 2,317 665 3,969 22% 6% 38% 45 

Otherf 6,571 2,631 0 5,734 40% 0% 87% 35 

Refusal/Don’t Know 1,746 10 

Ethnicity: 

Hispanic/Latino 7,434 3,635 700 6,569 49% 9% 88% 31 

Not Hispanic/Latino 87,008 20,841 16,734 24,948 24% 19% 29% 337 

Refusal/Don’t Know 1,246 7 

a

 Significant LBP hazard as defined in text and HUD Lead Safe Housing Rule. 

b

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

c

 All percentages are calculated with the “All HUs” column in each row used as the denominator. 

d

 CI = 95% confidence interval for the estimated number or percent. 

e

 Refusals and “don’t know” responses by survey respondents. 

f

 “Other” race includes Asian, American Indian or Alaskan Native, Native Hawaiian or other Pacific Islander, and more than 

one race. 

Table A.2 Prevalence of Significant Lead-Based Paint (LBP) Hazards by Location in the Building, 

for Alternative Soil Lead Threshold of 2000 ppm 

HUD Lead Safe Housing Rule: Significant LBP Hazards 

LBP Hazard Location Number of HUsa (000) Percent of HUsb HUs in 

Sample 

Estimate Lower 

95% CIc

Upper 

95% CI Percent Lower 95% CI 

Upper 

95% CI 

Interior only 10,861 6,865 14,857 11% 7% 16% 47 

Both Interior and Exterior 7,965 4,891 11,040 8% 5% 12% 39 

Exterior only 6,690 3,635 9,745 7% 4% 10% 29 

Anywhere 25,517 20,440 30,594 27% 21% 32% 115 

No Significant LBP Hazard 70,171 65,094 75,248 73% 68% 79% 260 

Total HUs 95,688 100% 375 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-5 October 31, 2002 

b All percentages are calculated with total housing units (95,688) as the denominator. Percentages may not total 100% due to 

rounding. c

 CI = 95% confidence interval for the estimated number or percent. 

Table A.3 Prevalence of Significant Lead-Based Paint (LBP) Hazards in Housing Units with a 

Child Under 6 Years of Age by Type of Hazard, for Alternative Soil Lead Threshold of 

2000 ppm 

HUD Lead Safe Housing Rule: Significant LBP Hazards 

Type of Hazard Number of HUsa

 (000) Percent of HUsb (%) 

Estimate Lower 

95% CIc

Upper 

95% CI Estimate Lower 

95% CI 

Upper 

95% CI 

Significantly Deteriorated Lead 

Based Paint 

 

All HUs 14,124 10,666 17,582 15% 11% 18% 

HUs w/ Child Under 6 3,521 1,576 5,467 21% 10% 33% 

Interior Lead Dust 

All HUs 16,794 12,169 21,420 18% 13% 22% 

HUs w/ Child Under 6 3,637 1,636 5,638 22% 10% 34% 

Lead Contaminated Soil 

All HUs 5,572 2,487 8,657 6% 3% 9% 

HUs w/ Child Under 6 1,419 0 3,057 9% 0% 19% 

Any LBP Hazard 

All HUs 25,517 20,410 30,623 27% 21% 32% 

HUs w/ Child Under 6 5,652 3,758 7,546 34% 23% 46% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b

 Percentages are calculated with total housing units (95,688) or with housing units with a child under age 6 (19,577) as the 

denominator, or as applicable. c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-6 October 31, 2002 

Table A.4a Distribution of Single Family Housing Units (SFHUs) with Deteriorated or 

Significantly Deteriorated Paint, by Construction Year 

Deteriorated Paint 

Construction Year

Total 

SFHUs 

(000)a

Number of SFHUs with 

Deteriorated Paint (000)

Percent of SFHUs with 

Deteriorated Paint (%)b

 Estimate Lower 

95% CIc 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 5,231 2,628 7,835 20% 10% 30% 

1960-1977 22,657 7,992 5,573 10,410 35% 25% 46% 

1940-1959 18,497 11,987 9,643 14,331 65% 52% 77% 

Before 1940 15,148 11,518 10,049 12,986 76% 66% 86% 

Total SFHUs 82,651 36,728 27,893 45,562 44% 34% 55% 

Significantly Deteriorated Paint 

Construction Year

Total 

SFHUs 

(000)

No. of SFHUs with Significantly 

Deteriorated Paint (000)

Percent of SFHUs with 

Significantly Deteriorated Paint 

(%)

 Estimate Lower 

95% CI

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 3,403 1,629 5,176 13% 6% 20% 

1960-1977 22,657 6,606 4,291 8,922 29% 19% 39% 

1940-1959 18,497 9,426 7,240 11,611 51% 39% 63% 

Before 1940 15,148 9,365 7,527 11,203 62% 50% 74% 

Total SFHUs 82,651 28,800 20,686 36,913 35% 25% 45% 

a

 “Single family housing units” include permanently occupied, noninstitutional single family housing units in which children 

are permitted to live. b

 Percentages are calculated with total housing units (95,688) or with housing units with a child under age 6 (19,577) as the 

denominator, or as applicable. c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-7 October 31, 2002 

Table A.4b Distribution of Single Family Housing Units (SFHUs) with Deteriorated or 

Significantly Deteriorated Unleaded Paint, by Construction Year 

Deteriorated Unleaded Paint 

Construction Year

Total 

SFHUs 

(000)a

Number of SFHUs with 

Deteriorated Unleaded Paint (000)

Percent of SFHUs with 

Deteriorated Unleaded Paint (%)b

 Estimate Lower 

95% CIc 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 5,149 2,525 7,773 20% 10% 29% 

1960-1977 22,657 7,081 4,873 9,289 31% 22% 41% 

1940-1959 18,497 5,748 4,076 7,420 31% 22% 40% 

Before 1940 15,148 2,824 1,828 3,819 19% 12% 25% 

Total SFHUs 82,651 20,802 13,303 28,301 25% 16% 34% 

Significantly Deteriorated Unleaded Paint 

Construction Year

Total 

SFHUs 

(000)2

No. of SFHUs with Significantly 

Deteriorated Unleaded Paint (000)

Percent of SFHUs with 

Significantly Deteriorated 

Unleaded Paint (%)1

 Estimate Lower 

95% CI3 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 3,320 1,521 5,119 13% 6% 19% 

1960-1977 22,657 5,997 3,752 8,241 26% 17% 36% 

1940-1959 18,497 4,658 3,107 6,209 25% 17% 34% 

Before 1940 15,148 2,250 1,274 3,225 15% 8% 21% 

Total SFHUs 82,651 16,225 9,654 22,795 20% 12% 28% 

a

 “Single family housing units” include permanently occupied, noninstitutional single family housing units in which children 

are permitted to live. b

 Percentages are calculated with total housing units (95,688) or with housing units with a child under age 6 (19,577) as the 

denominator, or as applicable. c

 CI = 95% confidence interval for the estimated number or percent. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-8 October 31, 2002 

Table A.4c Distribution of Single Family Housing Units (SFHUs) with Deteriorated and 

Significantly Deteriorated Lead-Based Paint (LBP) by Construction Year 

Deteriorated LBP 

Construction Year Number of SFHUs with 

Deteriorated LBP (000)

Percent of SFHUs with 

Deteriorated LBP (%) Total 1

SFHUs 

(000)2

Estimate Lower 

95% CI3 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 83 0 238 0% 0% 1% 

1960-1977 22,657 910 242 1,579 4% 1% 7% 

1940-1959 18,497 6,239 4,319 8,159 34% 23% 44% 

Before 1940 15,148 8,694 7,107 10,281 57% 47% 68% 

Total SFHUs 82,651 15,926 11,668 20,257 19% 14% 25% 

Significantly Deteriorated LBP 

Construction Year No. of SFHUs with Significantly 

Deteriorated LBP (000)

Percent of SFHUs with 

Significantly Deteriorated LBP 

(%)1

Total 

SFHUs 

(000)2

Estimate Lower 

95% CI3 

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

1978-1998 26,349 83 0 238 0% 0% 1% 

1960-1977 22,657 610 97 1,122 3% 0% 5% 

1940-1959 18,497 5,002 3,193 6,811 27% 17% 37% 

Before 1940 15,148 7,115 5,605 8,626 47% 37% 57% 

Total SFHUs 82,651 12,809 8,894 16,797 15% 11% 20% 

a

 “Single family housing units” include permanently occupied, noninstitutional single family housing units in which children 

are permitted to live. b

 Percentages are calculated with total housing units (95,688) or with housing units with a child under age 6 (19,577) as the 

denominator, or as applicable. c

 CI = 95% confidence interval for the estimated number or percent. 

Table A.5 Estimated Number of Housing Units with Lead-Based Paint on Windows 

 Number of Housing Units with LBP 

Windows (000) 

HU Characteristic Estimate Lower 95% 

CI 

Upper 95% 

CI 

HUs in 

Sample 

All Housing Units 18,222 15,688 20,757 165 

Construction Year: 

1978-1998 290 0 711 2 

1960-1977 2,092 1,251 2,933 20 

1940-1959 4,733 3,202 6,264 41 

Before 1940 11,108 9,298 12,917 102 

Occupied by Children Under Age 6 2,826 1,661 3,991 32 

Household in Poverty 3,547 2,324 4,771 36 

Household in Poverty, Resident Children 

Under Age 6 

569 169 969 7 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-9 October 31, 2002 

Table A.6 Estimated Number of Windows with Lead-Based Paint and in Housing Units with 

 Lead-Based Paint on Windows 

 Number of Windows with 

Lead-Based Paint 

(Average/HU)a

Number of Painted 

Windows 

(Average/HU) 

Total Number of Windows 

(Average/HU) 

HU Characteristic Estimate Lower 

95% CI

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI Estimate Lower 95% CI

Upper 

95% CI

All Housing Units 7.7 6.2 9.3 13.9 12.1 15.7 15.0 13.3 16.8

Construction Year: 

1978-1998 3.5 0.0 7.9 7.2 3.9 10.4 7.2 3.9 10.4

1960-1977 5.6 3.4 7.8 14.0 8.1 20.0 14.4 8.5 20.3

1940-1959 6.5 4.2 8.7 12.8 10.6 15.0 14.0 12.0 16.1

Before 1940 8.7 6.9 10.6 14.5 12.5 16.5 15.7 13.8 17.7

Occupied by Children 

Under Age 6 

12.7 8.0 17.5 20.4 14.5 26.3 21.8 16.2 27.4

Household in Poverty 4.3 2.7 6.0 7.9 5.9 9.9 9.4 8.1 10.7

Household in Poverty, 

Resident Children Under 

Age 6 

4.8 0.7 8.8 9.8 7.8 11.9 9.8 7.8 11.9

a

 Entries are average number of windows per housing units, averaged over the housing units with LBP on windows.

Table A.7 Distribution of Maximum Soil Sample (Bare and Covered) Lead Concentrations, All 

Sampled Locations 

Bare Soil Lead Number of HUs (000)a Percent of HUs (%)b

 

Estimate 

Lower 

95% CIc

Upper 

95% CI Estimate 

Lower 

95% CI 

Upper 

95% CI 

GEd0 ppm 93,111 91,090 95,131 97% 95% 99% 

GE 20 ppm 74,621 68,764 80,478 78% 72% 84% 

GE 50 ppm 56,266 49,840 62,693 59% 52% 66% 

GE 200 ppm 29,234 28,240 30,228 31% 30% 32% 

GE 400 ppm 20,390 17,032 23,748 21% 18% 25% 

GE 1,200 ppm 11,145 7,580 14,709 12% 8% 15% 

GE 1,600 ppm 7,426 5,289 9,563 8% 6% 10% 

GE 2,000 ppm 6,809 4,535 9,084 7% 5% 10% 

GE 5,000 ppm 2,987 1,548 4,427 3% 2% 5% 

No Bare Soil 335 0 960 0% 0% 1% 

No Soil 2,242 330 4,154 2% 0% 4% 

Missinge 95,688 a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b All percentages are calculated with total housing units (95,688) as the denominator. c

 CI = 95% confidence interval for the estimated number or percent. 

d GE equals “greater than or equal to.” e

 “Missing” means that soil was present, but that no lead value is available (either the sample was not collected, e.g. due to 

inaccessibility or respondent refusal, or the laboratory did not submit a value). “

No soil” means that there was no soil on the 

property to sample. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT A-10 October 31, 2002 

Table A.8 Distribution of Maximum Soil Sample (Bare and Covered) Lead Concentrations by 

Construction Year, All Sampled Locations 

Soil Lead 

Concentration 

Number of HUs (000)a Percent of HUs (%)b

 Before 

1940 

1940 - 

1959 

1960 - 

1977 

1978 - 

1998 

Before 

1940 

1940 - 

1959 

1960 - 

1977 

1978 - 

1998 

GEc 0 ppm 16,328 19,605 27,608 29,569 93% 95% 99% 99% 

GE 20 ppm 16,328 19,279 25,238 13,776 93% 94% 91% 46% 

GE 50 ppm 15,820 17,670 14,092 8,684 91% 86% 51% 29% 

GE 200 ppm 13,314 9,950 4,495 1,476 76% 48% 16% 5% 

GE 400 ppm 11,613 6,283 2,410 84 67% 31% 9% 0% 

GE 1,200 ppm 6,536 3,922 686 - 37% 19% 3% 0% 

GE 1,600 ppm 4,455 2,284 686 - 26% 11% 3% 0% 

GE 2,000 ppm 3,929 2,194 686 - 23% 11% 3% 0% 

GE 5,000 ppm 1,891 865 231 - 11% 4% 1% 0% 

Missingd 145 - 190 - 1% 0% 1% 0% 

No soil 1,003 939 95 205 6% 5% 0% 1% 

Total 17,476 20,544 27,893 29,774 100% 100% 100% 100% 

a

 “Housing units” include permanently occupied, noninstitutional housing units in which children are permitted to live. 

b All percentages are calculated with total housing units of that age as the common denominator. c GE equals “greater than or equal to.” d

 “Missing” means that soil was present, but that no lead value is available (usually due to inaccessibility or respondent 

refusal). “No soil” means that there was no soil on the property to sample. 
APPENDIX B 

Comparison of Protocols 

for the 

HUD 1990 Survey of Lead-Based Paint (LBP) in Housing 

and the 

HUD National Survey of Lead and Allergens in Housing 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT B-2 October 31, 2002 

Comparison of Protocols for the HUD 1990 Survey of Lead-Based Paint (LBP) in Housing 

and the HUD National Survey of Lead and Allergens in Housing

Area HUD National Survey of Lead-Based Paint 

in Housing 

HUD National Survey of Lead and 

Allergens in Housing 

Types/numbers of housing 

units selected for the 

survey and whose data 

were available to the 

TSCA Section 403 risk 

analysis 

284 housing units selected from occupied, 

permanent, non-institutional housing in the 

48 coterminous states built prior to 1980 and 

having the potential for containing children. 

(These units were all privately-owned. While 

publicly-owned units were also selected for 

the survey, data for these units are not 

considered in this summary.) 

831 housing units selected in a threestage stratified random sample from 

occupied, permanent, noninstitutionalized housing having the 

potential for containing children. 75 

primary sampling units (PSUs). 

Breakdown of selected 

units by year built 

Pre-1940: 27% 

1940-1959: 31% 

1960-1979: 42% 

Post-1979: 0% 

Pre-1940: 18% 

1940-1959: 22% 

1960-1977: 29% 

Post-1977: 31% 

Dates of environmental 

sampling 

November 1989 to March 1990 August 1998 to February 1999, and from 

July to August 1999 

Selecting rooms for 

environmental sampling 

Telephone household interview provided 

information on rooms. One room was selected 

for sampling in each of the following strata: 

 Wet room -- rooms containing plumbing 

(e.g., kitchen, bathroom, laundry room, 

utility room) 

 Dry room -- all rooms not classified as 

wet rooms 

 Main entryway (floor dust samples only) 

Room Inventory Form from the 

Screening/Recruiting Questionnaire was 

used to obtain information on rooms. 

One room was randomly selected for 

sampling in each of the following four 

strata: 

 Kitchen

 Common living area (e.g., living 

room, den, family room) 

 Bedroom in which one or more 

children aged 17 years or younger 

regularly slept, or any regularlyoccupied bedroom if no such 

children lived in the unit 

(occasionally, two such bedrooms 

were selected) 

 Other random room among the 

remaining rooms in the housing 

unit. (Note: Two rooms were 

randomly selected from this stratum 

if the stratum contained at least six 

rooms.) 

 Main entry (floor dust only)

 Interior common area (multi-family 

dwellings, floor dust only)

Method of assigning 

sampling weights 

Weights reflect the various stages of 

sampling. Total of the sampling weights 

Weights reflect the various stages of 

sampling. Total of the sampling weights 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT B-3 October 31, 2002 

Area HUD National Survey of Lead-Based Paint 

in Housing 

HUD National Survey of Lead and 

Allergens in Housing 

equaled the estimated number of housing 

units with children under age 7 years 

(13,912,000, as estimated by the 1987 AHS). 

Total of the sampling weights within a given 

census region equaled the estimated number 

of units with children under age 7 years in the 

census region. 

within a given census region equals the 

estimated number of units in the census 

region. 

Method for taking dust 

samples for lead analysis 

Blue Nozzle vacuum (a few wipe samples 

were also collected). Sampling house dust for 

lead: basic concepts and literature review.

(1995). EPA 747-R-95-007. 

Wipes, collected in accordance with 

ASTM E1728-95, Practice for the field 

determination of settled dust samples 

using wipe sampling methods for lead 

determination by atomic absorption 

spectrometry techniques.

Number and location of 

floor-dust samples per 

room 

One sample from each selected room 

(location not dictated in the protocol) 

One sample from each selected room, 

generally taken from the center of the 

largest open area of the room. 

Window sill/trough dust 

sampling approach 

A window was selected within each selected 

room according to a ranking scheme. 

Sampling was performed from both the sill 

and trough of the selected window until 

enough dust was collected or until the entire 

sill or trough was vacuumed. 

Entire sill and trough sampled from a 

random window in the selected room. 

Trough definition included sliders. 

Number and location of 

sill and trough dust 

samples per room 

One sample from the sill and one sample 

from the trough of the selected window in the 

selected wet room and dry room 

One sample from the sill and one sample 

from the trough of the selected window 

in each selected room 

Method of analyzing dust 

samples 

Graphite Furnace Atomic Absorption 

Spectroscopy (GFAA) (with EPA SW-846 

digestion method) 

Flame Atomic Absorption Spectrometry 

(FAAS) using NIOSH method 7082 

Digestion method: modification of EPA 

SW-846 Method 3050 or ASTM ES 36-

94 (hot-plate digestions utilizing nitric 

acid and/or perchloric acid and/or 

hydrogen peroxide). Method same as 

used in proficiency testing within the 

Environmental Lead Laboratory 

Accreditation Program (ELLAP). 

Soil sampling approach One composite sample of up to 3 core samples 

(the latter two taken within 20 inches of the 

first), each taken at a depth of 10 cm, was 

collected at each of the following locations: 

entryway, drip-line, and remote area (i.e., an 

area halfway between the unit and its property 

boundary, or within 25 feet of the unit, 

whichever was less). 

Two sides of the unit were selected for 

soil sampling: the side containing the 

major entryway (Wall 1) and a second, 

randomly-selected side (Wall 2). 

Samples were collected from the top 0.5 

inches of soil at the following three sites: 

 Main entry - a single sample from 

Wall 1 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT B-4 October 31, 2002 

Area HUD National Survey of Lead-Based Paint 

in Housing 

HUD National Survey of Lead and 

Allergens in Housing 

 Foundation/drip-line - one sample 

from each of Walls 1 and 2, each 

sample being a composite of 3 core 

subsamples taken within 3 feet of 

the foundation 

 Mid-yard area - one sample from 

each of Walls 1 and 2, each sample 

being a composite of 3 core 

subsamples taken midway between 

the drip-line and boundary of the 

housing unit property. 

 Play Area – one composite sample 

from bare soil under each unit of 

fixed play equipment. 

Soil samples were collected in 

accordance with core sampling 

procedures based on ASTM E1727-95 

(described in the HUD Guidelines and in 

EPA’s Residential Sampling for Lead: 

Protocols for Leaded Dust and Soil 

Sampling). Samples were collected from 

bare soil when possible. If no bare soil 

existed, samples were collected from 

covered surfaces if possible. 

Method of analyzing soil 

samples 

ICP-AES (with SW-846 digestion method) ICP-AES using NIOSH method 7082 

Digestion method: modification of SW846 Method 3050 or ASTM ES 36-94 

(hot-plate digestions utilizing nitric acid 

and/or perchloric acid). Method same as 

used in proficiency testing within the 

Environmental Lead Laboratory 

Accreditation Program (ELLAP). 

Handling dust-lead and 

soil-lead measurements 

below the detection limit 

As log-transformed lead amounts are reported 

in the database, only positive measurements 

are represented. No indication is given as to 

when data may have been truncated due to 

being below detection limits. 

The final results as reported by the 

instrument are recorded in the database 

(i.e., not-detected results are not 

censored), along with detection limits. 

Method for taking paintlead measurements Spectrum analyzer XRF instrument (single 

60-second spectrum reading measurement 

using a 40 millicurie cobalt source). 

Measurements were adjusted to statistically 

correct for measurement bias. 

Spectrum analyzer XRF analyzer (fullperiod readings with a 20-second 

minimum in accordance with the 

applicable HUD-approved Performance 

Characteristic Sheet .) 

Approach to selecting 

interior painted 

Painted surfaces were categorized into the 

following four strata: 

The following painted components were 

measured for lead in each selected room: 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT B-5 October 31, 2002 

Area HUD National Survey of Lead-Based Paint 

in Housing 

HUD National Survey of Lead and 

Allergens in Housing 

components for paint-lead 

measurements 

 Walls/ceilings/floors 

 Metal substrate 

 Non-metal substrate 

 Other surfaces 

Five painted components were selected 

randomly for testing in each of the selected 

wet and dry rooms, one from each stratum 

along with a fifth selected randomly from 

among all strata. In addition, up to two 

purposive measurements were taken from 

paint anywhere in the unit that may be 

suspected to contain lead. 

 All four major walls 

 Ceiling 

 Door of major entryway 

 Window selected for dust sampling 

 Baseboard 

 Floor 

 Up to two other painted surfaces: 

Technician choice based on surfaces 

containing deteriorated paint or 

friction areas. 

Approach to selecting 

exterior painted 

components for paint-lead 

measurements 

Painted surfaces were categorized into the 

following four strata: 

 Wall (randomly-selected) 

 Metal substrate within the selected wall 

 Non-metal substrate within the selected 

wall 

 Other surfaces within the selected wall 

Five painted components were selected 

randomly for testing from the side of the unit 

containing the selected wall, one from each 

stratum along with a fifth selected randomly 

from among all strata. In addition, up to two 

purposive measurements were taken from 

paint anywhere on the exterior of the unit that 

may be suspected to contain lead. 

Painted siding was measured for lead 

levels on each exterior wall. In addition, 

the following painted components were 

measured for lead on a random wall: 

 Miscellaneous trim (2 

measurements) 

 Window 

 Door of major entryway – wall 

independent. 

 Porch and railing – wall 

independent 

 Up to two other painted surfaces 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-1 October 31, 2002 

APPENDIX C 

Correcting for Classification Bias Due to Measurement Error 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-2 October 31, 2002 

CORRECTING FOR CLASSIFICATION BIAS DUE TO MEASUREMENT ERROR 

Homes were classified as having LBP and lead hazards based on the XRF readings of paint 

and the analysis of dust and soil samples. Random variation associated with instrument or laboratory 

measurement, sample collection, and random selection of sampling locations, can induce a classification 

bias resulting in a bias in the estimated prevalence of HUs with LBP and lead hazards. In addition, paint 

and dust measurements were made in a sample of rooms – not all rooms. Under this protocol, it is possible 

for a home to have LBP or a LBP dust hazard in the unsampled rooms and non-lead-based paint and/or no 

dust-lead hazard in the sampled rooms. Such HUs would be incorrectly classified as not having LBP 

and/or LBP hazards (false negatives). For this report, measurement error refers to the combined effect of 

instrument or laboratory measurement variation, sampling variation, spatial variation, and the incomplete 

sampling of rooms on the important survey estimates. 

The specific procedures, equations, and justification for the measurement error correction are 

presented in Appendix C of Volume II. The findings for the measurement error analyses for paint, dust, 

and soil are discussed below in Sections 7.3.1 through 7.3.3 below. The measurement error adjusted 

values (lead loading or concentration) have, to the extent possible, the same distribution as the true lead 

loading or lead concentration values, without the effect of measurement error. The measurement error 

corrected values are a weighted average of the observed measurements and predicted values from a 

regression model. Calculating the weights requires modeling the magnitude of the measurement error 

variance and the regression error variance. Replicate measurements were used to estimate the measurement 

error variance. 

Note that this analysis used preliminary data from the main survey. The analysis did not 

include data from the follow-on play area survey. In addition, minor revisions or corrections to the data 

may have been made since the analysis was performed. As a result, summary statistics from the 

measurement error analysis may not agree with those in other sections of the report. Nevertheless, the 

effects of measurement error are expected to similar in the preliminary and final data. 

C.1 Measurement Error - Paint XRF Measurements 

XRF readings to measure paint lead loading were taken on painted surfaces within the 

sampled rooms and on accessible exterior surfaces on two sides of the building to assess the lead loading in 

paint. The measurement error adjustment procedures were first applied to the interior XRF readings. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-3 October 31, 2002 

Because the measurement error adjusted XRF values were very close to the original interior XRF readings, 

it was considered unnecessary to apply a measurement error adjustment to the exterior XRF readings. 

For the measurement error analysis for paint lead measurements, the objective was to 

determine the number and percentage of homes with LBP. A surface with LBP is a surface with an 

average lead loading across the surface of 1.0 mg/cm2

 or greater when tested with an XRF analyzer. The 

instrument calculates its best internal estimate of the lead loading, which it rounds to the nearest 0.1 

mg/cm2

 for display. Therefore, to classify surfaces in an equivalent manner, the error corrected XRF 

readings were rounded to the nearest tenth unit for classifying surfaces.60 The classification of surfaces as 

having or not having LBP is used to classify homes as having or not having LBP. 

The measurement error adjustment procedure assumes that the distribution of the true paint 

lead loading around the average for similar homes and the distribution of the measurement error are 

normal. This assumption provided a relatively poor description of the XRF readings due to the presence of 

many zero XRF readings and long tails in the XRF distribution (the measurement error adjustment results 

are expected to be sensitive values in the tails of the distribution). As a result, the measurement error 

adjustment for paint lead loadings should be considered approximate, at best. Additional research into the 

measurement error of the XRF instrument and the distribution of paint lead loading across components 

would be required to improve the measurement error adjusted values. 

Figure C.1, which shows a scatter plot of replicate XRF readings, helps to illustrate the 

distribution of the XRF readings. The original XRF reading is on the horizontal axis and the replicate 

reading is on the vertical axis. Three situations occur. The first is where both XRF readings are zero (72.3 

percent of the replicate pairs) - these pairs provide essentially no information about measurement error. 

The second case is where one of the two readings is zero (12.4 percent of the replicate pairs) - these pairs 

fall on the axes. Lastly, there is the case where both XRF readings are non-zero (15.3 percent of the 

replicate pairs) – these generally fall on the diagonal in Figure C.1. For these points, the differences 

between the replicate XRF readings have an approximately normal distribution as assumed by the 

measurement error correction procedure. 

The XRF variation among all surfaces within a home increases with the average XRF reading 

within the home. This suggests that the measurement error will also increase with the paint lead loading on 

 

60 Rounding to the nearest tenth unit for classifying surfaces is equivalent to classifying a surfaces as having LBP if the average lead loading across the 

surface is 0.95 or greater. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-4 October 31, 2002 

a component. Surfaces with lead loading near zero will have relatively precise measurements and we 

expect that large differences between replicate readings when one reading is zero will be relatively rare. 

However, there are many surfaces for which one reading is zero and the other paired reading is relatively 

large (may be due to two different parts of a component having very different paint lead loadings).61 

Figure C.1 Original and Replicate XRF Readings on the Same Component 

-2 -1 0 1 2 3 4 5 6 7 8 9 10 15 20 30 40 50

50

40

30

20

15

10

9

8

7

6

5

4

3

2

1

0

-1

-2

Original XRF Reading

Replicate XRF Reading

Note: The axes use the transformed scale used for analysis (see Equation 9 in Appendix C, Volume II). 

For the measurement error adjustment, homes in which all XRF readings were zero or 

negative (162 HUs) were assumed to have no paint lead. The remaining homes were used in the 

 

61 Whatever the explanation for the pattern in the data, the patterns are not consistent with the assumptions behind the measurement error adjustment. 

Since no consistent pattern was found that would provide a better model, the measurement error adjustment as described in Appendix C (Volume II) 

was applied to the data. The results provide one estimate of the effect of measurement error on the assessment of the number of homes with LBP. 

However, other assumptions or other modeling approaches may provide very different estimates of the magnitude of the effect of measurement error. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-5 October 31, 2002 

measurement error analysis. For those homes, the model used to predict paint lead loadings had factors for 

housing unit ID, room type, year of construction, and interactions of year of construction by substrate, 

component, and percent deteriorated paint. A preliminary analysis suggested that the relationship between 

paint deterioration and XRF reading was not linear. To make the relationship closer to linear, the cube of 

the percent deterioration was used in the model. A further analysis of the relationship would be necessary 

to provide a better model. 

The regression analysis predicts the approximate median of the interior paint lead loading. 

Figure C.2 shows the relative median paint lead loading estimated from regression, by construction year 

category and component substrate. Figure C.3 shows the relative differences in median paint lead loading 

associated with combinations of construction year and region of the country. Figure C.4 and 7.5 shows the 

relative differences in the median paint lead loading versus component type, room type, component 

condition, metro status, presence of pets, overall home cleanliness, and the number of days the air 

conditioning was used in the last month. Because the assumptions behind the measurement error analysis 

provide a poor description of the XRF measurements, the patterns illustrated in Figures 7.2 to 7.5 should 

be considered suggestive of, rather than descriptive of, patterns in the population. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-6 October 31, 2002 

Figure C.2 Predicted Relative Median Paint Lead Loading by Construction Year of the Home 

and Substrate (based on regression model) 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

1750-1939 1940-1959 1960-1977 1978-1998

Relative Median Paint Lead Loading, mg/cm2 (See text)

Drywall Metal Other Paneling Plaster Wallpaper Wood
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-7 October 31, 2002 

Figure C.2 shows that interior paint lead loadings are highest in the oldest homes and lowest 

in the newest homes. The patterns for paint lead loading on specific substrates also generally decrease with 

the age of the home. The paint lead loadings are highest on wood surfaces in the oldest homes. For 

components with drywall, paneling, metal, plaster, wallpaper, and wood substrates, the median paint lead 

loading is low (less than 0.05 mg/cm2

) for homes built since 1960. However, median paint lead loading on 

other substrates (such as brick, concrete, stone, and vinyl) are higher for homes built in the 1960 to 1977 

period. 

Figure C.3 shows that the highest predicted median paint lead loading is found in homes built 

before 1960 in the northeast US and in homes built before 1940 in the southern US.62 

Figure C.3 Predicted Relative Median Paint Lead Loading by Construction Year of the Home 

and Region (based on regression model) 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

1750-1939 1940-1959 1960-1977 1978-1998

Year of Construction

Relative Median Paint Lead Loading, mg/cm2 (See text)

Midwest Northeast South West

 

62 Care should be taken when comparing these data to tables presented in Chapter 4. For example, a home was included in Table 4.1 if any one 

component had LBP. Values plotted in Figures 7.2 through 7.5 represent the predicted median paint loadings in the home (i.e., for all components). 

Thus, while Table 4.1 shows that 53% of homes in the Midwest have LBP, Figure C.3 shows that the median lead loading for all components is 

lowest for homes in the Midwest. This could be due to there being fewer components with LBP or the lead content of individual components could 

be lower in Midwest homes. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-8 October 31, 2002 

Figure C.4 shows that higher paint lead loadings are generally found on doors, window jambs 

and window sashes. There are relatively small but significant differences in the paint lead loading among 

rooms of different types. After accounting for other factors, paint lead loadings are generally higher in 

children’s bedrooms and in kitchens. 

Figure C.4 Predicted Relative Median Paint Lead Loading by Component Type and Room Type 

(based on regression model) 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Baseboard

Ceiling

Door jambEntry door

Miscelaneous

Wall

Window apron

Window jamb

Window sash

Window sill

Adult bedroom

Bathroom

Child bedroom

Kitchen

Living room

Other

Relative Median Paint Lead Loading, mg/cm2 (See text)

Component Room type
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-9 October 31, 2002 

Figure C.5 shows that higher paint lead loadings are generally found on components that were 

judged to be in fair condition as opposed to intact or poor condition. However, relatively few surfaces were 

judged to be in fair condition. Small but significant differences were associated with metro status (lower 

paint lead loading in non-MSAs), presence of pets (lower in homes with pets), overall cleanliness, and days 

using air conditioning in the last month.

Figure C.5 Predicted Relative Median Paint Lead Loading by Component Condition, Metro 

Status, Presence of Pets, Overall Cleanliness, and Air Condition Use in the Last 

Month (based on regression model) 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Intact

Fair

Poor

Missng

MSA>1MMSA<1M

nonMSA

Pets

No pets

Appears clean

Some cleaning

No cleaning

Unknown

zero

1 to 9

10 to 1920 to 30

31 days

Relative Median Paint Lead Loading, mg/cm2 (See text)

Component

condition Metro status

Currently

pets Cleanliness

Days using AC

in last month

As part of the exploratory analysis to identify the model for the data, such additional variables 

as tenure and race were considered and not found to be significant predictors. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-10 October 31, 2002 

The measurement error adjustment procedure identified approximately 30 percent of the XRF 

readings as outliers. Outliers are those measurements that are more than 2.5 standard deviations above or 

below the mean of the non-outliers. In this case, the measurement error procedure makes a conservative 

adjustment. The non-outlier data were assumed to have a normal error distribution, however, the 

distribution of the residuals had a tight distribution in the center and very long tails, inconsistent with the 

normal distribution assumption. The resulting estimate of the error variance was very small, resulting in 

almost no estimated effect of measurement error. Using the measurement error procedure in Appendix C 

(Volume II), the measurement error adjusted paint lead loadings are essentially equal to the XRF readings. 

Additional work would be required to develop a better model for the XRF readings and other assumptions 

might provide a significantly different assessment of the effects of measurement error. 

The tentative results from the measurement error analysis are that the interior XRF readings 

provide a reasonable measure of the paint lead loading for many surfaces. For the remaining surfaces that 

look like outliers when judged relative to a normal distribution, the effect of measurement error is difficult 

to assess. We believe that similar conclusions are likely to apply to exterior surfaces; however, no 

measurement error adjustment was attempted for the exterior surfaces. 

C.2 Measurement Error – Dust Lead Measurements 

Dust samples were taken at all surveyed homes from the floor at the main entrance and from 

the floors, window sills, and window troughs of the sampled rooms. Separate measurement error 

adjustments were performed for the floor and window dust samples. 

Floor Dust Lead Loading 

The model for predicting floor dust lead loading included factors for household ID (as a class 

variable), surface characteristics at the sample location, and the interaction of the type of floor cover and 

year of construction. The measurement error adjustment procedures excluded three percent of the floor 

dust measurements as outliers. The regression analysis predicts the approximate median of the floor dust 

lead loading. 

Figure C.6 shows the relative median floor dust lead loading estimated from regression, by 

construction year category and type of floor cover in the sampled room. The predicted median floor dust 

lead loadings were highest for the oldest homes and decrease for homes constructed more recently. The 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-11 October 31, 2002 

floor lead loading was generally higher in rooms with no floor covering than in rooms with wall-to-wall 

carpets. Rooms with some floor covering had floor dust loadings similar to or somewhat greater than in 

rooms with wall-to-wall carpets, and lower than rooms with no floor covering. The floor lead loadings for 

the unknown floor cover category represent primarily the floor dust lead loadings for the main entrance 

(94% of the data in the unknown category, as this information was not recorded). The dust lead loading at 

the main entrance was similar to dust lead loading from other rooms that have no floor covering. 

Figure C.6 Predicted Relative Median Floor Dust Lead Loadings by Construction Year 

Category and Floor Cover in the Sampled Room (based on regression model) 

0

1

2

3

4

5

6

7

1750-1939 1940-1959 1960-1977 1978-1998

Construction Year Category

Relative Median Floor Lead Loading, 

μg/ft2 (see text)

No floor cover

Some floor cover (area rug, mat, etc.)

Wall-to-wall carpet

Unknown (primarily main entrance samples) 

Floor cover in sampled room
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-12 October 31, 2002 

Figure C.7 shows the relative median floor dust lead loading estimated from regression, by 

home cleanliness, household income, and surface sampled. Dust lead loadings were on average higher in 

lower income homes, and in homes that show no evidence of cleaning (a small minority of all homes).63 

Dust lead loadings were also higher on hard surfaces that were not smooth and cleanable (a small minority 

of all surfaces), perhaps because these surfaces are more difficult to clean or perhaps because they collect 

dust faster between cleanings. Carpets had lower lead loading than smooth and cleanable surfaces, using 

the wipe sampling methods employed. 

Figure C.7 Predicted Relative Median Floor Dust Lead Loadings by Cleanliness, 

Household Income, and Surface Condition (based on regression model) 

0

1

2

3

4

5

6

7

Appears clean

Some evidence of

cleaning

No evidence of

cleaning

Unknown

up to 30K

30K or over

Carpeted

Smooth and

cleanable

Hard but not

smooth/cleanable

Unknown

Relative Median Dust Lead Loading, 

μg/ft2 (see text)

Overall Household Cleanliness Household Income Surface Condition at Sample 

Location

 

63 These results suggest that cleaning activity will generally affect dust lead loading. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-13 October 31, 2002 

As part of the exploratory analysis to identify the model for the data, additional variables were 

considered and not found to be significant predictors. In particular, the type of room (bedroom, bathroom, 

kitchen, etc.) and presence of pets were not significant. 

Figure C.8 shows the cumulative distribution of the maximum floor dust lead loading at 

homes. The figure shows three cumulative distributions: 

1. The maximum of the floor dust lead loading measurements at a home (bottom thin 

black line). 

2. The maximum measurement error adjusted floor dust lead loading across the 

sampled rooms (top gray line). 

3. The maximum measurement error adjusted floor dust lead loading across all 

rooms, sampled and unsampled (middle thick black line). 

The difference between the first (bottom thin black) and second (top gray) curves shows the 

effect of the measurement error adjustment on the classification of the measured surfaces. The difference 

between the second (top gray) and the third (middle thick black) curves illustrates the effect of random 

selection of rooms on the classification of homes. Measurement error tends to increase the number of 

homes, and incomplete sampling of rooms tends to decrease the number of homes, classified as having 

maximum floor dust lead loading above a selected value. For the floor data, these effects partially cancel 

out so that the number of homes classified as having floor lead over a specified value using either the 

maximum adjusted lead loading value or the maximum observed measurements is similar. The difference 

between the first (bottom thin black) and the third (middle thick black) curves illustrates the combined 

effect of doing both the measurement-error adjustment and unsampled-room adjustment. 

Using the measurement error corrected values, an estimated four percent of homes (about 4 

million homes) have floor dust lead loadings of 40 μg/ft2

 or more in one or more rooms. This is about one 

percent fewer homes than estimated using the actual floor dust measurements. 

Figure C.8 Cumulative Distribution of the Maximum Floor Dust Lead Loading for Homes 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-14 October 31, 2002 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 10 100 1000

Floor dust lead loading (μg/ft2)

Percent of homes with lower floor dust lead loadings

Measurements Adjusted for measurement error Adjusted for unsampled rooms

Window Dust Lead Loading 

Window dust samples were taken from randomly selected windows in the sampled rooms 

within surveyed homes. For the measurement error correction, one objective was to estimate the number of 

rooms having or not having average window sill dust lead loading and average window trough dust lead 

loading less than a selected value. A second objective was to estimate the number of homes with average 

room window sill and window trough dust lead loading less than a selected value in all rooms. The first 

objective required estimating lead loadings for the missing values and adjusting for measurement error. 

The second objective also required adjusting for the unknown lead loading in the unsampled rooms. 

Scatter plots of the data showed that the log transformed window sill and trough 

measurements are linearly related, with the ratio of the trough to sill lead loading being roughly constant at 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-15 October 31, 2002 

about 11. The proximity of the sill to the trough suggests that the similar factors may affect the lead 

loading at these two locations. Therefore, the analysis below used both the window sill and window trough 

dust lead loadings in the same model for calculating the measurement error adjustment. Because the log 

transformation was used, the model assumes that the same factors predict the relative sill and trough lead 

loadings and that the ratio of the sill to trough lead loading was constant across homes. Although a 

separate measurement error adjustment could have been performed separately for sill and trough 

measurements, this combined approach was expected to provide a similar adjustment. The measurement 

error adjustment procedures excluded three percent of the floor dust measurements as outliers. 

Two models were fit to the data. One was used for predicting window dust lead loading in 

homes with at least one window lead loading measurement. A second model was used to predict window 

dust lead loading for homes with no window dust lead loading measurements in the data files. The 

predictors in each model are presented in Table C.1. 

Table C.1 Regression Model Used for Different Categories of Homes 

Category of 

homes 

Number 

of homes 

Factors for predicting window dust lead loading 

I. Homes with no 

window dust 

samples 

17 Sample location (sill or trough), year of construction, 

tenure, race category of occupants, overall household 

cleanliness as judged by the interviewer, and room type. 

II. Homes with at 

least one 

window dust 

sample 

808 Sample location (sill or trough), household ID (as a class 

variable), surface characteristics at the sample location, 

whether the window has a vinyl mini-blind, and room type. 

Figure C.9 shows the relative differences in median window dust lead loading associated with 

different levels of sample location (sill or trough), year of construction, tenure, race category, overall 

household cleanliness, surface characteristics, room type, and presence of vinyl mini-blinds. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-16 October 31, 2002 

Figure C.9 Predicted Median Window Dust Lead Loading by Various Factors (based on regression 

model) 

0

200

400

600

800

1000

1200

Some evidence of cleaning

Window sill

Window trough

1750-19391940-19591960-19771978-1998

Privately owned

Publically owned

Rented

 African American

Other/Unknown

White

Appears clean

No evidence of cleaning

Unknown

Adult bedroo

m

Bathroo

m

Child bedroo

m

Kitchen

Living room

Other

Unknown

Smooth and cleanable

Not smooth/cleanable

No vinyl mini-blinds

Vinyl mini-blinds

Unknown

Relative Median Dust Lead Loading,

μg/ft2 (see text)

Sample

location

Construction

date

Tenure Race

 category

Overall Household

Cleanliness

Room type Sample

surface

Vinyl miniblinds

The predicted median window dust lead loading is much higher in the window trough than on 

the window sill. Lead loading is highest for the oldest homes and lower for homes constructed more 

recently. The window lead loading is generally higher for rented homes than in private owned homes and 

higher in homes with African American residents and in homes with residents of other races. The small 

number of homes that have no apparent indication of cleaning have higher window dust lead loadings than 

homes that were classified as showing some evidence of cleaning or appearing clean. Although most rooms 

had similar window dust lead loading measurements, measurements were somewhat higher in adult 

bedrooms and “Other” rooms (rooms not classified as kitchen, living room, or bedroom). Samples from 

window surfaces that were not smooth and cleanable had higher lead loading than samples from smooth 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-17 October 31, 2002 

and cleanable surfaces. Finally, windows with vinyl mini-blinds had somewhat higher dust lead loading 

than windows without vinyl mini-blinds. Differences for other window coverings were not statistically 

significant. 

Figure C.10 shows the cumulative distribution of the maximum window sill dust lead loading 

within homes. The figure shows four cumulative distributions: 

1. The maximum of the window dust lead loading measurements within a home (thin 

black line). 

2. The maximum of the window dust lead loading measurements or predicted values 

for missing data (also a thin black line). 

3. The maximum measurement-error-adjusted window dust lead loading across the 

sampled rooms (thick gray line). 

4. The maximum measurement-error-adjusted window dust lead loading across all 

rooms, sampled and unsampled (thick black line). 

For various reasons, such surfaces being inaccessible, data were not available for some 

window surfaces. The first curve assumes that the lead loading on all surfaces with missing data is 

negligible. As a result of the measurement error adjustment, predicted values are available for all surfaces. 

For surfaces with no data, the predicted values were used. The second curve, to the right of the first curve, 

shows the cumulative distribution of the best estimate of the lead loading on all window surfaces, i.e., the 

measurement on surfaces with data and the predicted values on surfaces with no measurements. The 

predicted values are referred to as imputed values. The imputation generally affects the lower portion of 

the distribution. 

The third curve shows the distribution of the measurement error adjusted estimates. Since 

measurement error will generally increase the maximum within-home measurements, the effect of the 

measurement error correction is to slightly reduce estimated maximum within-home window dust lead 

loading. The fourth curve shows the cumulative distribution of the measurement error corrected 

measurements after accounting for the incomplete sampling of rooms. These values will be referred to as 

the adjusted values. The primary difference between the maximum of the observed window sill dust lead 

loading measurements and the final adjusted maximum in each home is due to the incomplete sampling of 

rooms. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-18 October 31, 2002 

Using the adjusted values, a predicted 19 percent of homes (18 million homes) have a window 

sill dust lead loading of at least 250 μg/ft2

 in at least one room. This is about five percent more homes than 

estimated using the actual measurements. A predicted 22 percent of homes (21 million homes) have a 

window trough dust lead loading of at least 800 μg/ft2

 in at least one room. This is about 20 percent more 

than estimated using the actual measurements. 

Figure C.10 Cumulative Distribution of the Maximum Within-Home Window Sill Dust Lead Loading 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 10 100 1000 10000 100000

Maximum within-home window sill dust lead loading (μg/ft2)

Percent of homes

Measurements Measurements + imputed values

Adjusted for measurement error Adjusted for measurement error and unsampled rooms 
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and Allergens in Housing Analysis of Lead Hazards

WESTAT C-19 October 31, 2002 

Figure C.11 shows the cumulative distribution of the maximum window trough dust lead 

loading within homes. The figure shows four cumulative distributions for the measurements (thin upper 

thin black line), the measurements plus imputed values (lower thin black line), the measurement error 

corrected values for the sampled rooms (gray line) and the final adjusted values that account for the 

incomplete sampling of rooms 

Because there were many surfaces for which window trough data could not be obtained, there 

are relatively large differences between the distributions for the measurements and the measurements with 

imputed values. As with the window sill lead loading, the measurement error adjustment for the available 

measurements makes only a small difference compared to the effect of missing data and the incomplete 

sampling of rooms. 

Figure C.11 Cumulative Distribution of the Maximum Within-Home Window Trough Dust Lead 

Loading 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 10 100 1000 10000 100000 1000000

Maximum within-home window trough dust lead loading (μg/ft2)

Percent of homes

Measurements Adjusted for measurement error and unsampled rooms 

Also adjusted for unsampled rooms Measurements + imputed values
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and Allergens in Housing Analysis of Lead Hazards

WESTAT C-20 October 31, 2002 

C.3 Measurement Error – Soil Lead Measurements 

Soil samples were taken at all surveyed homes at the major entrance and along the dripline 

and midyard of two sides of the home, if soil was present. For the soil measurement error correction, the 

objective was to determine the number and percentage of homes with average soil lead concentrations 

above a selected value at the three sample sites - midyard, dripline, and main entrance.64 Note that this 

analysis was performed on preliminary data, before the play area survey samples were collected. 

Table C.2 describes the regression model used for different categories of homes. 

 For Category I homes, there was no soil at any of the three sample sites, and so 

no model was required. This situation occurred if all areas of the yard were 

covered with concrete, asphalt, or rock. Also, a specific sample site could have 

no soil if the site did not exist (for example, the dripline and the property line 

coincided so that there was no midyard sample site). 

 For Category II homes, at least one of the sample sites had soil, but there were 

no soil lead measurements for the home. This situation could arise if the 

respondent denied permission to collect soil samples, or if adverse conditions 

existed, such as an ongoing storm, frozen ground, the presence of a dog, or 

large rocks mixed in with the soil. The measurement error corrected soil lead 

concentrations are the predicted values from the regression model. 

 For Category III homes, all soil measurements were equal to zero. While the 

sample detection limit was determined to be 20 ppm, the laboratory provided an 

estimate of the soil lead for all samples with levels below the detection limit. 

However, negative laboratory estimates were reported as zero. The 

measurement error corrected soil lead concentrations are assumed to be less 

than the detection limit. 

 For Category IV homes, some or all of the soil measurements were equal to a 

non-zero value (i.e., a value at or more than the detection limit). These values 

were used to predict soil lead concentrations for the category IV and category 

II homes. 

 

64 The average of the available midyard and average of available dripline samples were used for the measurement error analysis, regardless of which 

side of the house they were collected. That is, separate assessments were not made for midyard and dripline areas on each side of the home. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-21 October 31, 2002 

Table C.2 Regression Model Used for Different Categories of Homes 

Category of homes Number 

of 

homes 

Model for measurement error corrected soil 

concentrations 

I. Homes with no soil at any 

sample site 

45 Not applicable. 

II. Homes with soil, but no 

soil measurements 

8 Log transformed soil lead concentration = a 

mean for each combination of construction 

year category and soil sample location and a 

mean for each combination of construction 

year category and region. 

III. Homes with all soil lead 

measurements equal to 

zero (therefore no 

within-home variation) 

33 All measurements assumed to be less than the 

detection limit.

IV. Homes with soil lead 

measurements, some or 

all of which are nonzero 

745 Log transformed soil lead concentration = a 

mean for each combination of construction 

year category and soil sample location, a mean 

for each combination of construction year 

category and region, and a mean for each 

home 

The regression analysis predicts the approximate median of the soil lead concentrations. 

Figures C.12 and C.13 show the relative median soil lead concentration for homes within each construction 

year category by sample location and region. As expected, older homes have higher soil lead 

concentrations. Concentrations are also higher on average in the northeast region and lower in the western 

region of the country. Soil lead concentrations are higher on average at the dripline sample location and 

lower at the midyard sample location. The measurement error adjustment procedures excluded three 

percent of the floor dust measurements as outliers. 

As part of the exploratory analysis to identify the model for the data, additional variables were 

considered. In particular, orientation of the side of the building (north, east, south, or west) and ground 

cover (bare soil, grass, ivy, moss, mulch, and other or unknown) were examined. Neither the side of the 
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and Allergens in Housing Analysis of Lead Hazards

WESTAT C-22 October 31, 2002 

house on which the samples were taken nor the ground cover was a significant predictor of soil lead 

concentrations, after adjusting for the effects of year of construction, region, and sample location. 

Figure C.12 Predicted Relative Median Soil Lead Concentrations by Construction Year Category 

and Sample Location (based on regression model) 

0

50

100

150

200

250

300

350

400

450

1750-1939 1940-1959 1960-1977 1978-1998

Year built category

Relative Estimated median soil lead concentration

Main entry

Midyard 

Dripline 
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and Allergens in Housing Analysis of Lead Hazards

WESTAT C-23 October 31, 2002 

Figure C.13 Predicted Median Soil Lead Concentrations by Construction Year Category and 

Region (based on regression model) 

0

50

100

150

200

250

300

350

400

450

1750-1939 1940-1959 1960-1977 1978-1998

Year built category

Relative Estimated median soil lead concentration

Midwest

Northeast

South

West

Figure C.14 shows the cumulative distribution of the maximum soil lead concentration at 

homes. The figure shows three cumulative distributions: 

 The maximum of the soil lead measurements at a home (bottom thin black line). 

 The maximum within each home of the average soil lead measurements at the entrance, 

dripline, and midyard (middle gray line). 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards

WESTAT C-24 October 31, 2002 

 The maximum measurement error corrected soil lead measurements (top thick black 

line). 

Figure C.14 Cumulative Distribution of the Maximum Soil Lead Concentration for All Homes 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

10 100 1000 10000 100000

Maximum soil lead concentration

Percent of homes

Measurement

Mean measurement by location

Adjusted measurements

Note: Play area soil sample results were not included in the analysis for Figure C.14. Thus, data may vary 

slightly from that presented in Chapter 6. 

The difference between the first and second curves shows the effect of taking replicate soil 

measurements (i.e. more than one sample for a given sample location at a home). As more measurements 

are taken, it is more likely that a sample will be taken which has an unusually high measurement (either due 

to laboratory variation or due to sampling a small area with a locally high concentration). The second 

curve is most comparable to the third curve. The difference between the second and the third curve is due 

to the measurement error correction. The fact that the third (measurement error corrected) curve is to the 
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and Allergens in Housing Analysis of Lead Hazards

WESTAT C-25 October 31, 2002 

left of the other curve is because, after correcting for measurement error, the percentage of homes judged to 

have soil lead concentrations above any selected value is decreased. 

Using the measurement error corrected values, an estimated 5.6 percent of homes with soil 

(about 5.3 million homes) have soil lead concentrations above 1,200 ppm in one or more of the sampling 

locations (dripline, midyard, and main entrance). This is about two million fewer homes than estimated 

using the observed soil lead measurements. Even fewer homes have maximum soil lead concentrations over 

1,200 ppm on bare soil. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT D-1 October 14, 2002 

APPENDIX D 

Calculation of Soil Related Estimates 
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and Allergens in Housing Analysis of Lead Hazards 

WESTAT D-2 October 14, 2002 

CALCULATION OF SOIL RELATED ESTIMATES 

In the main survey, soil samples were collected near the main entrance, along the drip line and in the midyard on the side of the house with the main entrance, and along the dripline and in the mid-yard on a second 

randomly selected side of the home. In a follow-on survey of children's play areas involving a subset of the 

homes in the main survey, residents were asked where children play around the home. If there was play 

equipment at the home or soil samples were not previously collected in children's play areas, additional soil 

samples were collected at the home in a follow-up visit. In the play area survey, soil samples were 

collected from below play equipment and from areas designated by the respondent as children's play areas. 

The main survey has data from 831 homes. The follow-on survey has information on 375 homes. Details 

of the survey procedures are described in the Design and Methodology report. 

The tables in this report are based on data from the 831 homes whenever possible. However, for estimates 

involving soil in children's play areas, data was only available from 375 homes. Therefore, estimates not 

involving soil were based on the main survey data. Estimates involving only soil were based on the play 

area survey data. For estimates that involve both soil data and data from other locations, such as the 

number of homes with significant lead-based paint (LBP) hazards, estimates from the main survey were 

combined with estimates from the play area survey, as described below. 

To construct estimates of significant LBP hazards using as much of the data as possible the following 

procedure was used. Estimates of the number of homes with significant LBP hazards due to paint, dust, 

and soil sources other that play soil were calculated from the 831 homes from the main survey. Estimates 

of the number of homes with significant LBP hazards due only to soil hazards in play areas were calculated 

from the 375 homes in the play area survey. These two estimates were added together to obtain the 

combined estimate of the number of homes with significant LBP hazards from any source. 

For example, the estimated number of homes with a significant LBP hazard is 24,026 thousand. This is the 

sum of 23,312 thousand homes with paint hazards, dust hazards, or soil lead hazards in non-play areas 

(based on data from 831 homes) and 714 thousand homes with significant LBP hazards in play areas only 

(based on data from 375 homes). 

The variance of the combined estimate depends on the portion of the estimate contributed by the two data 

sources, the variance of each estimate, and the correlation between the estimates. Calculation of the 

variance of the combined estimate is difficult because the correlation is difficult to estimate. However, the 

estimate from the main survey contributes 97% of the combined estimate. As a result, the variance of the 

combined estimate is primarily due to uncertainty in the estimate from the main survey. Therefore, the 

confidence intervals in the tables involving lead hazards, are based on the confidence intervals calculated 

from the main survey. The resulting confidence interval will tend to underestimate the true variance by a 

small amount. Thus, the confidence intervals for the number of homes are calculated as follows: 

1) The confidence interval and estimate for the number of homes with significant LBP hazards in all 

but play soil are calculated from the main survey data. 

2) The estimate for the number of additional homes with a significant LBP hazards in only the play 

soil is calculated from the play survey data. 
National Survey of Lead Final Report, Vol. I 

and Allergens in Housing Analysis of Lead Hazards 

WESTAT D-3 October 14, 2002 

3) The estimate from the play survey data is added to the estimate from the main survey to get the 

combined estimate, and 

4) The estimate from the play survey data is added to the confidence limits for the estimate from the 

main survey to approximate the confidence limits for the combined estimate.