AN EVALUATION OF THE EFFICACY OF THE LEAD HAZARD REDUCTION TREATMENTS
PRESCRIBED IN MARYLAND ENVIRONMENTAL ARTICLE 6-8

# FINAL REPORT

**SUBMITTED TO:**

**BALTIMORE CITY HEALTHY START, INC.**

**BALTIMORE CITY HEALTH DEPARTMENT-LEAD ABATEMENT ACTION PROGRAM**

**BALTIMORE, MARYLAND**

**PREPARED BY:**

**NATIONAL CENTER FOR HEALTHY HOUSING**

**(formerly the National Center for Lead-Safe Housing)**

**COLUMBIA, MARYLAND**

**JANUARY 24, 2002**

**(revised April 30, 2002)**

TABLE OF CONTENTS

ABSTRACT 1

EXECUTIVE SUMMARY 2

I. INTRODUCTION 11

A.  Background and Purpose of this Study 11

B.  Specific Research Aims and Report Objectives 12

II\. STUDY DESIGN AND SAMPLE COLLECTION PROCEDURES 14

> A. Overview of the Study Design 14
>
> B. Recruitment and Enrollment Process 15

C.  Selection Criteria for Enrolled Units 15

D.  Data Collection Forms and Protocols 16

E.  Dust Lead Sampling Protocols 18

F.  Visual Assessment Protocols 20

III\. LABORATORY ANALYSIS PROCEDURES 21

IV\. QUALITY ASSURANCE AND QUALITY CONTROL 22

> A. Laboratory Quality Assurance and Quality Control 22
>
> 1\. Quality Control Spiked Dust Wipe Sample Results 22
>
> 2\. Quality Control Field Blank Dust Wipe Sample Results 22
>
> 3\. Procedures for Dust Wipe Sample Results that Were At or Below
> Laboratory Report Limits 22
>
> B. Performance Audit of Field Data Collection Activities 23
>
> C. Data Audit and Data Completeness 23

V. DATA PROCESSING AND STATISTICAL ANALYSIS PROCEDURES 24

> A. Data Entry and Processing 24
>
> B. Data Summary and Statistical Analysis 24

VI\. ENROLLMENT RESULTS BY PHASE 24

VII\. PRE-INTERVENTION RESULTS 25

> A. Results of Visual Assessment of Baseline Characteristics and
> Conditions 25

1.  Baseline Physical Characteristics 25

2.  Baseline Exterior Building and Interior Unit Condition 27

> B. Results of Pre-Intervention *Composite* and *Single Surface* Dust
> Sampling 30
>
> 1\. Pre-Intervention *Composite* Results 30
>
> 2\. Pre-Intervention *Single Surface* Results 32
>
> 3\. Comparison of Pre-Intervention *Single Surface* Results with
> Clearance Standards/Guidance 34

VIII\. IMMEDIATE POST-INTERVENTION
RESULTS...........................................35

> A. Results of Immediate Post-Intervention *Composite* and *Single
> Surface* Dust Sampling................... 35

1.  Immediate Post-Intervention *Composite* Results 35

2.  Reduction in *Composite* Results from Pre- to Immediate Post-

> Intervention 37

3.  Units Having an Increase in *Composite* Dust Lead Loadings from Pre-
    to Immediate Post-Intervention 39

4.  Immediate Post-Intervention *Single Surface* Results 40

5.  Reduction in *Single Surface* Results from Pre- to Immediate
    Post-Intervention 42

6.  Units Having an Increase in *Single Surface* Dust Lead Loadings from
    Pre- to Immediate
    Post-Intervention..................................................45

7.  Comparison of Immediate Post-Intervention *Single Surface* Results
    with Clearance Standards/Guidance 46

B. Results of Immediate Post-Intervention Visual Assessments 48

1.  Types of Immediate Post-Intervention "Failures" 49

2.  Number of Rooms with "Failures" at Phase II 52

3.  Type of Contractor and Number of "Failures" at Immediate Post-
    Intervention 52

C. Description of and Factors Affecting Costs 54

> D. Description of Statistical Modeling Through Immediate
> Post-Intervention 56
>
> 1\. Predicting Dust Lead Loading at Immediate Post-Intervention 56
>
> 2\. Predicting Dust Lead Loading "Failures" at Immediate
> Post-Intervention 57

1.  Predicting Immediate Post-Intervention Visual Assessment "Failures"
    58

IX\. ONE-YEAR POST-INTERVENTION (PHASE III) RESULTS 58

A. Physical Characteristics and Baseline Condition of Enrolled Units
Having One-Year Post-intervention Data 58

1.  Baseline Physical Characteristics for Enrolled Units Having One-Year
    Post-Intervention Data 58

2.  Baseline Exterior Building and Interior Unit Conditions for One-Year
    Post-Intervention Units 59

3.  Pre-Intervention Dust Lead Loadings for the 73 One-Year
    Post-Intervention Units 61

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B.  One-Year Post-Intervention *Composite* and *Single Surface* Dust
    Sampling

> Results 64

1.  Summary of One-Year Post-Intervention *Composite* Dust Sampling

> Results 64

2.  Change in *Composite* Results from Pre- to One-Year
    Post-Intervention 66

3.  Units Having an Increase in *Composite* Dust Lead Loadings from Pre-
    to One-Year Post-Intervention 68

4.  Summary of One-Year Post-Intervention *Single Surface* Results 69

5.  Change in Single Surface Results from Pre- to One Year Post-

> Intervention 69
>
> 6\. Units Having an Increase in *Single Surface* Dust Lead Loadings
> from Pre-to One-Year Post Intervention 73
>
> 7\. Comparison of One Year Post Intervention Results with Clearance
> Standards/Guidance 74

C. Results of One-Year Post-Intervention Visual
Assessment........................\...74

1.  Types of One-Year Post-Intervention "Failures" 75

2.  Magnitude of One-Year Post-Intervention "Failures" 76

3.  Rooms with One-Year Post-Intervention "Failures" 78

4.  Type of Contractor and Number of One-Year Post-Intervention

> "Failures" 79

D. Follow-Up Data Summary for One-Year Post-Intervention (Form 06) 80

E. Statistical Modeling Results for One-Year Post-Intervention 80

1.  Predicting Dust Lead Loading at One-Year Post-Intervention 80

2.  Predicting One-Year Post-Intervention Dust Lead Loading Exceedances
    of Standards 81

3.  Predicting One-Year Post-Intervention Visual Assessment "Failures"
    82

X. SUMMARY OF TWO-YEAR POST-INTERVENTION RESULTS 82

A. Two-Year Post-Intervention Dust Sampling Results 82

1.  Summary of Two-Year Post-Intervention *Composite* Results 82

2.  Change in *Composite* Results from Pre- to Two-Years Post-

> Intervention 83

3.  Change in *Composite* Results from One-Year to Two-Years
    Post-Intervention 84

B. Results of Two-Year Post-Intervention Visual Assessment 84

XI\. SUMMARY AND DISCUSSION OF FINDINGS 85

> A. Summary and Discussion of Findings Through Immediate
> Post-Intervention 85

1.  Comparison of Pre- and Immediate Post-Intervention Dust Lead Loading
    Results 85

2.  Immediate Post-Intervention Visual Assessment Results 87

3.  Cost Data Analysis Results 88

> B. Summary and Discussion of Findings Through Two-Years
> Post-Intervention 89

1.  Comparison of Pre-Intervention and One-Year Post-Intervention Dust
    Lead Loading Results 89

2.  One-Year Post-Intervention Visual Assessment Results 90

3.  Comparison of Pre-Intervention and Two-Year Post-Intervention Dust
    Lead Loading Results 91

> C. Comparing the Efficacy of the Prescribed Lead Hazard Reduction
> Treatments Both With and Without Window Replacement 91

XII\. CONCLUSIONS AND RECOMMENDATIONS 92

A. Conclusions 92

B. Recommendations 97

TABLES

Table 1: Data Collection Form Type and Usage 17

Table 2: Dust Wipe Sample Results Below Reporting Limits or Reported As
Zero 23

Table 3: Dwelling Unit Baseline Characteristics - Pre-Intervention
Assessment 27

Table 4: Units with Exterior Building Deterioration -- Pre-Intervention
Assessment 28

Table 5: Number of Exterior Baseline Building Deterioration Items --
Pre-Intervention Assessment 28

Table 6: Units with Interior Dwelling Unit Deterioration --
Pre-Intervention Assessment 29

Table 7: Number of Interior Dwelling Unit Deterioration Items --
Pre-Intervention

Assessment 30

Table 8: Pre-Intervention *Composite* Sample Dust Lead Loading 31

Table 9: Pre-Intervention *Single Surface* Sample Dust Lead Loading 33

Table 10: Immediate Post-Intervention *Composite* Sample Dust Lead
Loading 36

Table 11: Percent Reduction in Pre- to Immediate Post-Intervention
*Composite*

Dust Lead Loadings 38

Table 12: Micrograms Per Square Foot Reduction in Pre- to One-Year
Post-Intervention

*Composite* Dust Lead Loadings 38

Table 13: Number and Percent of Units Having an Increase in *Composite*
Dust Lead Loadings from Pre- to Immediate Post-Intervention 40

Table 14: Immediate Post-Intervention *Single Surface* Dust Lead Loading
Results 41

Table 15: Percent Reduction in Pre- to Immediate Post-Intervention
*Single Surface* Dust Lead
Loadings..............................................................................43

Table 16: Micrograms Per Square Foot Reduction in Pre- to Immediate
Post-Intervention *Single Surface* Dust Lead
Loadings...................................................\...44

Table 17: Number and Percent of Units Having an Increase in *Single
Surface* Dust Lead Loadings from Pre- to Immediate
Post-Intervention..................................46

Table 18: Immediate Post-Intervention *Single Surface* "Clearance
Failures" -- *Floors* 47

Table 19: Immediate Post-Intervention *Single Surface* "Clearance
Failures" -- *Interior Window Sills* 47

Table 20: Immediate Post-Intervention *Single Surface* "Clearance
Failures" -- *Window
Troughs*......................................................................................48

Table 21: Number of Immediate Post-Intervention Visual Assessment
"Failures" Per

Unit..........................................................................................49

Table 22: Immediate Post-Intervention Visual Assessment for Lead Hazard
Reduction Treatment "Failures" 50

Table 23: Reporting Frequency of Specified Types of Treatment "Failures"
at Immediate Post Intervention 51

Table 24: Mean Number of Rooms per Unit with Specified Immediate
Post-Intervention Visual Assessment "Failures" by Treatment Group 53

Table 25: Mean Number of Immediate Post-Intervention "Failures" per Unit
by Type of
Contractor...................................................................................53

Table 26: Description of Lead Hazard Reduction Costs 55

Table 27: Mean Lead Hazard Reduction Costs by Contractor Type 56

Table 28: Dwelling Unit Baseline Characteristics for One-Year
Post-Intervention Units 59

Table 29: Baseline Exterior Building Deterioration Summary for One-Year
Post-Intervention Units 60

Table 30: Number of Baseline Interior Dwelling Unit Deterioration Items
for One-Year Post-Intervention Units 60

Table 31: Summary of Baseline Interior Dwelling Unit Deterioration Items
for One-Year Post-Intervention Units 61

Table 32: Number of Baseline Interior Dwelling Unit Deterioration Items
for One-Year Post-Intervention Units 61

Table 33: Pre-Intervention *Composite* Sample Dust Lead Loading for
One-Year Post- Intervention Units 62

Table 34: Pre-Intervention *Single Surface* Sample Dust Lead Loading for
One-Year Post-Intervention Units 63

Table 35: One-Year Post-Intervention *Composite* Sample Dust Lead
Loadings 65

Table 36: Percent Reduction in Pre- to One-Year Post-Intervention
*Composite* Dust Lead Loadings 67

Table 37: Micrograms Per Square Foot Reduction in Pre-to One-Year
Post-Intervention Composition Dust Lead Loadings 68

Table 38: Number and Percent of Units Having an Increase in *Composite*
Dust Lead Loadings from Pre-to One-Year Post-Intervention 68

Table 39: One-Year Post-Intervention *Single Surface* Sample Dust Lead
Loadings 70

Table 40: Percent Reduction in Pre-to One-Year Post-Intervention *Single
Surface* Dust Lead Loadings 72

Table 41: Micrograms Per Square Foot Reduction in Pre- to One-Year
Post-Intervention *Single Surface* Dust Lead Loadings 73

Table 42: Number and Percent of Units Having an Increase in *Single
Surface* Dust Lead Loadings from Pre- to One-Year Post-Intervention 73

Table 43: Percentage of LHR + W Units with One-Year Post-Intervention
*Single Surface* Dust Lead Loadings Exceeding Clearance Standards 74

Table 44: Number of One-Year Post-Intervention Visual Assessment
"Failures" Per Unit 75

Table 45: One-Year Post-Intervention Visual Assessment "Failures" 76

Table 46: Reporting Frequency of Specified Types of One-Year
Post-Intervention Visual Assessment "Failures" 77

Table 47: Mean Number of Rooms Per Unit with Specified One-Year
Post-Intervention Visual Assessment "Failures" by Treatment Group 79

Table 48: Mean Number of One-Year Post-Treatment "Failures" Per Unit by
the Type of Contractor 80

Table 49: Two-Year Post-Intervention *Composite* Sample Dust Lead
Loadings 83

Table 50: Median Percent Reductions and Absolute Reduction in Pre- to
Two-Year Post-Intervention Composite Dust Lead Loadings 84

Table 51: Reporting Frequency of Specified Types of Two-Year
Post-Intervention Visual Assessment "Failures" 85

Table 52: Summary of Pre- and Immediate Post-Intervention Dust Lead
Loading Results by Assigned Treatment Group and Sampling Method 86

Table 53: Percentage of Units with One-Year Post-Intervention *Single
Surface* Clearance "Failures" 87

Table 54: Summary of Pre- and One-Year Post-Intervention Dust Lead
Loadings Results by Assigned Treatment Groups and Sampling Method 89

Table 55: Percentage of Units with One-Year Post-Intervention *Single
Surface* Clearance "Failures" 90

Table 56: Summary of Pre- and Two-Years Post-Intervention Composite Dust
Lead Loading Results by Assigned Treatment Group and Sampling Method 91

Table 57: Median Percent Reductions in Dust Lead Loadings from Pre-to
One-Year Post-Intervention for LHR, LHR + W, and Baltimore Round One HUD
Evaluation Units 94

Table 58: One-Year Post-Intervention "Failure" of HUD Clearance
Standards for LHR + W and Baltimore Round One HUD Evaluation Units Based
on *Single Surface* Sampling 95

Table 59: Median Percent Reductions in Composite Dust Lead Loadings from
Pre- to Two- Years Post-Intervention for LHR and LHR + W Units 95

Table 60: Median Percent Reduction in Lead Loadings from
Pre-Intervention to Immediate Post-Intervention for LHR, LHR + W, and
Baltimore Round One HUD Evaluation Units 96

Table 61: Immediate Post-Intervention Clearance "Failure" Rates for LHR,
LHR + W, and Baltimore Round One HUD Evaluation Units 96

FIGURES

Figure 1: Type of Building -- Pre-Intervention Assessment 26

Figure 2: Year Building Constructed -- Pre-Intervention Assessment 26

Figure 3: Pre-Intervention *Composite* Sample Dust Lead Loading Box Plot
32

Figure 4: Pre-Intervention *Single Surface* Sample Dust Lead Loading Box
Plot 34

Figure 5: Immediate Post-Intervention *Composite* Sample Dust Lead
Loading Box Plot 37

Figure 6: Pre- and Immediate Post-Intervention *Composite* Sample Dust
Lead Loading for LHR and LHR+W Units (Logarithmic Scale) 39

Figure 7: Immediate Post-Intervention *Single Surface* Sample Dust Lead
Results Loading

> Box Plot 42

Figure 8: Pre- and Immediate Post-Intervention *Single Surface* Sample
Dust Lead Loading for LHR and LHR+W Units (Logarithmic Scale) 45

Figure 9: Percentage of Units Having Specified Number of Rooms Per Unit
with Immediate Post-Intervention Visual Assessment "Failures" 52

Figure 10: Pre- and One-Year Post-Intervention *Composite* Sample Dust
Lead Loading Box Plot 66

Figure 11: Pre- and One-Year Post-Intervention *Single Surface* Sample
Dust Lead Loading Box Plot 71

Figure 12: Percentage of Units Having Specified Number of Rooms Per Unit
with One-Year Post-Intervention Visual Assessment "Failures" 78

APPENDICES

Appendix A: Data Collection Forms

Appendix B: Laboratory Analytical Procedures and QA/QC Summary

Appendix C: Physical Characteristics of Enrolled Buildings/Dwellings --
Detailed Listing

Appendix D: Baseline Exterior Building and Interior Dwelling Conditions
-- Detailed Listing

Appendix E: Composite Dust Lead Loading (µg/ft^2^) Results -- Detailed
Listing

Appendix F: Single Surface Dust Lead Loading (µg/ft^2^) Results --
Detailed Listing

Appendix G: Complete List of Visual Assessment "Failures"-by Type of
Failure and Assigned Treatment Group

Appendix H: Risk Reduction and Window Replacement Costs -- Detailed
Listing

Appendix I: Statistical Data for Models Predicting Dust Lead Loading at
Clearance, Dust Lead Loading "Failures" and Post-Intervention Visual
Assessment "Failures"

Appendix J: Description of the Relationship Between Single Surface and
Composite Dust Sample Results

# ABSTRACT

This report measured the degree to which housing is made lead-safe under
Maryland's lead law (Maryland Environmental Article 6-8). Baltimore City
housing units were enrolled into one of two categories. The Lead Hazard
Reduction (LHR) category included 57 units that underwent the minimum
set of treatments required by the statute, and the Lead Hazard Reduction
plus Windows (LHR+W) category included 64 units in which windows were
replaced as well. Upon completion of the work and as required by the
law, all units received a visual inspection, but not clearance dust
testing, by Maryland accredited independent Lead Paint Visual Inspection
Contractors. A second team of trained and certified lead-based paint
risk assessors performed a visual assessment and conducted clearance
dust testing for study purposes. Any deficiencies identified by the
study-related visual assessment were corrected.

The study results show that dust lead loadings decreased by 70 to 99
percent between pre- and immediate post-intervention. However, had
clearance testing been required by the statute, 46 percent, 8 percent
and 27 percent of units would have "failed" clearance based on floor,
window sill and window trough clearance standards of 100 µg/ft^2^, 500
µg/ft^2^ and 800 µg/ft^2^, respectively. In addition, over 90 percent of
units had one or more treatment "failures" based on the study-related
confirmatory visual assessments conducted by the second team of
lead-based paint risk assessors. In order to ensure that units are safe
for children, this study recommends clearance dust testing and more
rigorous oversight of independent Lead Paint Visual Inspection
contractors who conduct visual inspections.

**EXECUTIVE SUMMARY**

Working with the U.S. Department of Housing and Urban Development's
(HUD's) Office of Healthy Homes and Lead Hazard Control (OHHLHC),
Baltimore City's Healthy Start Program and the Baltimore City Health
Department's Lead Abatement Action Program (LAAP), the National Center
for Lead-Safe Housing (the Center) designed this study to evaluate the
efficacy of a prescribed set of "lead hazard reduction treatments" found
in Maryland's lead law, Maryland Environmental Article 6-8 (EA 6-8) in
reducing dust lead loadings.

In this study, pre- and immediate post-intervention dust sampling and
visual assessment tools were utilized to determine the efficacy of the
law's requirement that, upon completion of the prescribed treatments,
only an independent visual inspection is needed to determine whether a
treated rental housing unit visually "passes" or "fails" the prescribed
standard.[^1] One-year post-intervention dust sampling and visual
assessment tools were then utilized to evaluate the continued
effectiveness of treatments prescribed and performed under EA 6-8. The
extent to which lead hazards were decreased immediately following
treatment is discussed, primarily by comparing pre- with immediate
post-intervention dust lead loadings on floors, window sills and window
troughs in a set of rooms where young children were likely to play, eat
or sleep. This report also documents the extent to which lead dust
re-accumulated on various surfaces over a one-year period after
completion of the treatments, primarily by comparing one-year
post-intervention dust lead loadings on floors, window sills and window
troughs with pre-intervention dust lead loadings. Limited data for a
two-year post-intervention period are also discussed.

LAAP inspectors, who were trained and certified as lead-based paint risk
assessors, recruited property owners or managers to enroll their rental
housing units in this study. To be enrolled, a unit had to be located in
Baltimore City, constructed prior to 1950, vacant at intervention and
structurally sound as determined by a LAAP screening inspection. A
structurally deficient unit could be accepted into the study at a later
date if the owner corrected observed deficiencies. (Information on
pre-program repairs was not collected as part of the study.) Enrolled
units were assigned into two treatment categories: (1) units that
underwent EA 6-8's prescribed treatments (referred to as "LHR units");
and (2) units that underwent these treatments plus window replacement
(referred to as "LHR+W units"). The owner prepared work specifications
for the lead hazard intervention, according to EA 6-8's prescribed
treatment requirements. LAAP inspectors then conducted a
pre-intervention walk-through inspection, during which, in accordance
with study protocols, they collected composite and single surface dust
wipe samples from floors, window sills and window troughs in specific
rooms, using HUD wipe sampling methods. During subsequent phases, in
accordance with study protocols, LAAP inspectors visited units to
collect composite and single surface samples from the same surfaces,
rooms and locations that were sampled at pre-intervention.

All samples were analyzed for total lead by laboratories participating
in EPA's National Lead Laboratory Accreditation Program (NLLAP) and
proficient in the Environmental Lead Proficiency Analytical Testing
Program (ELPAT). Study protocols included laboratory and field quality
assurance/quality control procedures. Field audits and data audits were
also routinely performed.

The Center was responsible for all data entry and processing. All study
data were transmitted into and maintained in Jetform's FormFlow software
program. Statistical analyses were performed using a SAS Institute
program, which also generated reports and tables. A Crystal Reports
software package was also used to generate certain reports.

# Results Through Immediate Post-Intervention

A total of 177 units (91 LHR and 86 LHR+W) underwent complete
pre-intervention baseline visual assessments. Pre-intervention composite
dust samples were collected in 148 of the 177 units[^2] and single
surface dust samples were collected in 98 units. The EA 6-8 prescribed
lead hazard reduction treatments were completed in 121 units (57 LHR and
64 LHR+W). A full immediate post-intervention study assessment was
performed in these units, including a visual assessment by LAAP
inspectors, collection of cost and concurrent work data and dust
testing. Immediately after treatment, both the LHR and the LHR+W units
experienced substantial reductions in dust lead loadings on all surfaces
(see Table E-1 on page 4). Using either of the dust sampling methods,
immediate post-intervention dust lead loadings on bare floors of LHR
units were generally similar to those on bare floors of LHR+W units.
However, as expected, immediate post-intervention dust results for
window sills and troughs in LHR units were significantly higher than
those in LHR+W units.

Despite the significant median decreases in dust lead loadings between
pre- and immediate post-intervention, data in Table E-2 (on page 4) do
show that some units experienced increases in dust lead loadings between
these two phases. The percentage of LHR+W units that underwent an
increase was generally lower than that of LHR units and was comparable
to that of Baltimore HUD units.

**Table E-1: Median Percent and µg/ft^2^ Reductions in Pre- to Immediate
Post-Intervention Dust Lead Loadings for LHR, LHR+W and Baltimore Round
One HUD Evaluation Units^b^**

+-----------------+----------------+----------------+-----------------+
| **Surface Type  | ##             | ###            | #####           |
| and Sample      | #### LHR Media | ### LHR+W Medi | # Balt. HUD Med |
| Type**          | n % Reduction  | an% Reduction  | ian% Reduction  |
|                 |                |                |                 |
|                 | **(& Median    | **(& Median    | **(& Median     |
|                 | µg/ft^2^       | µg/ft^2^       | µg/ft^2^        |
|                 | Reduction)**   | Reduction)**   | Reduction)**    |
+-----------------+----------------+----------------+-----------------+
| [Bare           | 85% (147       | 89% (225       | NA^a^           |
| Floor           | µg/ft^2^)      | µg/ft^2^)      |                 |
| s]{.underline}: |                |                | 95% (265        |
|                 | 70% (99        | 88% (226       | µg/ft^2^)       |
| Composite       | µg/ft^2^)      | µg/ft^2^)      |                 |
|                 |                |                |                 |
| Single Surface  |                |                |                 |
+-----------------+----------------+----------------+-----------------+
| [Interior       | 94% (1,686     | 99% (2,596     | NA^a^           |
| window          | µg/ft^2^)      | µg/ft^2^)      |                 |
| sill            |                |                | \>99% (2,492    |
| s]{.underline}: | 84% (497       | 99% (2,516     | µg/ft^2^)       |
|                 | µg/ft^2^)      | µg/ft^2^)      |                 |
| Composite       |                |                |                 |
|                 |                |                |                 |
| Single Surface  |                |                |                 |
+-----------------+----------------+----------------+-----------------+
| [Window         | 95% (9,708     | \>99% (11,284  | NA^a^           |
| Trough          | µg/ft^2^)      | µg/ft^2^)      |                 |
| s]{.underline}: |                |                | 99% (3,591      |
|                 | 94% (4,111     | 99% (12,022    | µg/ft^2^)       |
| Composite       | µg/ft^2^)      | µg/ft^2^)      |                 |
|                 |                |                |                 |
| Single Surface  |                |                |                 |
+-----------------+----------------+----------------+-----------------+

^a^NA=not applicable. Composite dust samples were not taken in the
Baltimore Round One HUD Evaluation units.

^b^Single surface dust data were compared to data obtained from
Baltimore City housing units enrolled in Round I of the National
Evaluation of HUD's OHHLHC's Lead Hazard Control Grant Program. These
units underwent interventions similar to those of the LHR+W units, and
more intensive than those of the LHR units.

Table E-2: Number and Percent of Units Having an Increase in Dust Lead
Loadings from Pre- to Immediate Post-Intervention

+------------------+----------------+---------------+----------------+
| **Surface Type   | # LHR          | **LHR+W**     | **Baltimore    |
| and Sample       |                |               | HUD Units**    |
| Type**           |                |               |                |
+------------------+----------------+---------------+----------------+
| [Bare            | 6/49 (12%)     | 3/56 (5%)     | NA             |
| Floo             |                |               |                |
| rs]{.underline}: | 4/16 (25%)     | 4/63 (6%)     | 12/278 (4%)    |
|                  |                |               |                |
| Composite        |                |               |                |
|                  |                |               |                |
| Single Surface   |                |               |                |
+------------------+----------------+---------------+----------------+
| [Interior window | 4/52 (8%)      | 2/62 (3%)     | NA             |
| sil              |                |               |                |
| ls]{.underline}: | 2/16 (12%)     | 1/62 (2%)     | 2/277 (1%)     |
|                  |                |               |                |
| Composite        |                |               |                |
|                  |                |               |                |
| Single Surface   |                |               |                |
+------------------+----------------+---------------+----------------+
| [Window          | 3/52 (6%)      | 1/62 (2%)     | NA             |
| Troug            |                |               |                |
| hs]{.underline}: | 2/16 (12%)     | 1/62 (2%)     | 13/273 (5%)    |
|                  |                |               |                |
| Composite        |                |               |                |
|                  |                |               |                |
| Single Surface   |                |               |                |
+------------------+----------------+---------------+----------------+

Although EA 6-8 does not require clearance dust testing in connection
with the prescribed treatments, post-intervention results were compared
with clearance standards to assess the extent to which the treatments
produced dust results sufficient for safe occupancy of the treated units
and the extent to which the prescribed independent visual inspection
provided a sufficient level of risk reduction. When applying these
clearance standards to immediate post-intervention individual single
surface dust results, an appreciable number of units had at least one
floor, window sill or window trough dust lead result that exceeded the
Maryland and HUD/EPA guidance/standards at the time of the study (see
Table E-3 on page 5). Assigned treatment group was significantly
associated with post-intervention window sill and trough results
"passing" or "failing" their respective standards but was not
significantly associated with bare floors "passing" or "failing"
standards. Had clearance testing been required, 46 percent of the units
had at least one sample that would have "failed" a floor clearance level
of 100 µg/ft^2^, nine percent had at least one sample that "failed"
interior window sill clearance of 500 µg/ft^2^ and 27 percent had at
least one sample that "failed" window trough clearance of 800 µg/ft^2^.
These are higher "failure" rates than those observed for vacant
Baltimore HUD units enrolled in the HUD National Evaluation (29 percent
for floors, one percent for sills and six percent for troughs).[^3] It
is apparent that dust clearance testing is critical to ensure that
treated dwellings are safe for re-occupancy.

Table E-3: Percentage of Units with Immediate Post-Intervention Single
Surface Clearance "Failures"

  ------------------- ------------ ---------- ------------------- ----------------
                      **Percent of                                
                      Units within                                
                      Specified                                   
                      Category**                                  

  **Surface Type:**   **Floors**              **Interior Window   **Window
                                              Sills**             Troughs**

  **Std/Guidance:**   100         200       500 µg/ft^2^       800 µg/ft^2^
                      µg/ft^2^     µg/ft^2^                       

  **LHR Units**       60%          35%        20%                 50%

  **LHR+W Units**     41%          25%        5%                  19%

  **Total All Units** 46%          28%        8%                  27%
  ------------------- ------------ ---------- ------------------- ----------------

Although statistically significant dust lead loading reductions were
found and each unit passed the independent visual inspection prescribed
by EA 6-8, immediate post-intervention confirmatory visual assessments
conducted by LAAP inspectors yielded a high percentage of units (93
percent) with visual "failures" of one or more of the prescribed lead
hazard reduction treatments (see Table E-4 on page 6).[^4] The three
most common "failures" were: (1) not all paint intact, with some
chipping, flaking and peeling paint remaining (75 percent of all units);
(2) one or more painted doors continuing to rub together and/or bind (43
percent); and (3) visible paint chips and/or debris remaining (38
percent). The "failures" that LAAP inspectors recorded were easily
observed, with a dwelling unit geometric mean of 1 ft^2^ of non-intact
paint reported in LHR and LHR+W units, and dwelling unit geometric means
of 8 and 16 ft^2^ of visible paint chips and debris in LHR and LHR+W
units. It should be noted that the areal density (i.e., depth) and lead
concentration of chips/debris were not measured. The owner corrected
treatment "failures" noted during the immediate post-intervention
sampling visit before tenants moved in. These corrections were
"validated" by LAAP inspectors, who required owners and/or contractors
to complete their work prior to payment.

These results indicate that lead hazard reduction treatments did not
completely meet the EA 6-8 risk reduction standard and more strongly
suggest that the independent visual inspections failed to identify all
lead hazard reduction "failures." Because only five or six independent
inspectors conducted inspections for these study units, this finding
does not necessarily reflect on all other Maryland-certified inspectors.

**^Table\ E-4:\ Number\ of\ Immediate\ Post-Intervention\ Visual\ Assessment\ "Failures"\ Per\ Unit^**a

+-----------------------------------+----------+----------+----------+
| **Number of Immediate             | **LHR**  | *        | **All    |
| Post-Intervention Visual          |          | *LHR+W** | Units**  |
| Assessment "Failures" Per         | **\#     |          |          |
| Unit^b^**                         | Units**  | **\#     | **\#     |
|                                   |          | Units**  | Units**  |
| **(57 LHR units, 64 LHR+W         | **(%     |          |          |
| units)**                          | Units)** | **(%     | **(%     |
|                                   |          | Units)** | Units)** |
+-----------------------------------+----------+----------+----------+
| "0" lead hazard treatment         | 6 (10%)  | 4 (6%)   | 10 (8%)  |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "1" lead hazard treatment         | 7 (12%)  | 26 (41%) | 33 (27%) |
| "failure"                         |          |          |          |
+-----------------------------------+----------+----------+----------+
| "2" lead hazard treatment         | 22 (39%) | 21 (34%) | 44 (36%) |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "3" lead hazard treatment         | 19 (33%) | 9 (14%)  | 28 (23%) |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "4" lead hazard treatment         | 2 (4%)   | 3 (5%)   | 5 (4%)   |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "5" lead hazard treatment         | 1 (2%)   | 0 (0%)   | 1 (1%)   |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+

Source: Form 05

^a^For the purposes of this study, a treatment "failure" was defined as
an observation by the LAAP inspector that one or more of the ten lead
hazard reduction treatments prescribed in the statute had not been fully
completed. "Failures" were counted on a per unit basis. Within each
unit, failures were listed by room ID.

^b^The mean number of "failures" per unit (2.1 for LHR units; 1.7 for
LHR+W units) was significantly associated with assigned treatment group
(p=0.0255).

Various cost data were collected during this study, including
LAAP-approved costs for the prescribed lead hazard reduction treatments,
plus the additional window replacement costs for the LHR+W units.
Owner-estimated turnover costs that would have been incurred even if the
enrolled units had not been subject to the EA 6-8 treatments were also
collected. However, these data were highly subjective and were excluded
from the study. Finally, the type of contractor performing the work and
information on concurrent work was also collected. The median cost for
completing the prescribed treatments in LHR units and LHR+W units was
\$2,154 and \$1,649, respectively. Costs in LHR units were likely higher
because the expense of the prescribed window treatments was included,
while window replacement costs in the LHR+W units were calculated
separately. The median cost of treatment plus window replacement in the
LHR+W units was \$4,348, with an average of 9 to 10 windows being
replaced per unit. Treatment costs were higher than expected for a
typical Baltimore City dwelling and should not be considered average or
representative of all Baltimore City rental unit costs.

For LHR units, the mean costs for for-profit contractors were slightly
higher than those for property owners/employees, while the reverse was
observed for LHR+W units. Concurrent work (e.g., roofing, plumbing,
heating and electrical repairs and replacement of other fixtures and
components) was performed in 17 of the 57 LHR units and in 27 of the 64
LHR+W units.

For each surface type, a backward elimination multiple regression model
was run to identify factors that were significant predictors of
immediate post-intervention dust lead loadings. No significant
predictors were found for bare floors. However, pre-intervention sill
dust lead loadings and the assigned treatment group were found to be
significant predictors of immediate post-intervention sill results. For
window troughs, pre-intervention trough dust lead loadings and the
assigned treatment group were significant predictors of immediate
post-intervention trough results.

Clearance "failures" on bare floors was not modeled since no
relationship was found when attempting to predict dust lead loading at
clearance. For sills and troughs, a logistic regression model was run to
identify factors that are significant predictors of whether units would
have clearance "failures" based on floor, sill and trough standards of
100 μg/ft^2^, 500 μg/ft^2^ and 800 μg/ft^2^, respectively. For sills,
the only variable found to significantly predict immediate
post-intervention clearance "failures" was the percent of windows
replaced out of the total number of windows in a unit. For troughs, the
number of items of exterior building deterioration (yielding more
clearance "failures") and the percent of windows replaced (yielding
fewer clearance "failures") were found to be significant predictors of
clearance "failure" at immediate post-intervention.

A logistic model was employed to identify factors that are significant
predictors of immediate post-intervention visual assessment "failures."
The only variable found to significantly influence visual assessment
"failure" was the number of items of exterior building deterioration
(increasing items yielding more visual assessment "failures").

# Results Through One-Year Post-Intervention

A total of 73 units (36 LHR and 37 LHR+W) were sampled approximately one
year after treatments were completed. LAAP inspectors also performed a
full visual assessment at one year post-intervention, noting any
"failures" that had occurred since their previous visit.

At one-year post-intervention, composite and single surface dust lead
loadings on all surfaces remained well below pre-intervention levels
(see Table E-5). Substantial median percent decreases and median
μg/ft^2^ decreases in dust lead loadings were observed for floors, sills
and window troughs between pre- and one-year post-intervention. Dust
lead loadings on window sills and troughs in LHR units were
significantly higher than those in LHR+W units.

Table E-5: Median Percent (µg/ft^2^) Reductions in Dust Lead Loadings
for LHR, LHR+W and Baltimore Round One HUD Evaluation Units Between
Pre-Intervention and One Year Post-Intervention

+------------------+----------------+-----------------+----------------+
| **Surface Type   | ##             | **LHR+W Median  | **Balt.**      |
| and Sample       | #### LHR Media | % Reduction**   | **HUD Median   |
| Type**           | n % Reduction  |                 | Reduction**    |
|                  |                | **(& Median     |                |
|                  | **(& Median    | µg/ft^2^        | **(& Median    |
|                  | µg/ft^2^       | Reduction)**    | µg/ft^2^       |
|                  | Reduction)**   |                 | Reduction)**   |
|                  |                | **Pre to 1 Year |                |
|                  | **Pre to 1     | Post**          | **Pre to 1     |
|                  | Year Post**    |                 | Year Post**    |
+------------------+----------------+-----------------+----------------+
| [Bare            | 82% (87        | 94% (335        | NA^a^          |
| Floo             | µg/ft^2^)      | µg/ft^2^)       |                |
| rs]{.underline}: |                |                 | 84% (220       |
|                  | NA^b^          | 96% (420        | µg/ft^2^)      |
| Composite        |                | µg/ft^2^)       |                |
|                  |                |                 |                |
| Single Surface   |                |                 |                |
+------------------+----------------+-----------------+----------------+
| [Interior window | 82% (713       | 97% (2,803      | NA^a^          |
| sil              | µg/ft^2^)      | µg/ft^2^)       |                |
| ls]{.underline}: |                |                 | 98% (2,617     |
|                  | NA^b^          | 97% (1,875      | µg/ft^2^)      |
| Composite        |                | µg/ft^2^)       |                |
|                  |                |                 |                |
| Single Surface   |                |                 |                |
+------------------+----------------+-----------------+----------------+
| [Window          | 89% (4,507     | 98% (12,014     | NA^a^          |
| Troug            | µg/ft^2^)      | µg/ft^2^)       |                |
| hs]{.underline}: |                |                 | 90% (3,308     |
|                  | NA^b^          | 99% (16,338     | µg/ft^2^)      |
| Composite        |                | µg/ft^2^)       |                |
|                  |                |                 |                |
| Single Surface   |                |                 |                |
+------------------+----------------+-----------------+----------------+

^a^NA=not applicable. Composite dust samples were not taken in Baltimore
Round I HUD Eval. units.

^b^NA=not applicable. Single surface samples were collected in only 2
LHR unit at one year post-intervention.

One-year post-intervention single surface results for LHR+W units were
compared with clearance standards to assess the extent to which the
treatments continued to produce dust results sufficient for safe
occupancy of the treated units. Insufficient single surface data were
available for LHR units. Less than 20 percent of units had at least one
bare floor, sill, or trough result that exceeded HUD standards (see
Table E-6). The percentages for floors and troughs in LHR+W units were
significantly lower than those found for Baltimore Round I units in the
HUD National Evaluation.

Table E-6: Percentage of Units with One-Year Post-Intervention Single
Surface Clearance "Failures"

  ------------------- ------------ ---------- ------------------- ----------------
                      **Percent of                                
                      Units within                                
                      Specified                                   
                      Category**                                  

  **Surface Type:**   **Floors**              **Interior Window   **Window
                                              Sills**             Troughs**

  **Std/Guidance:**   100         200       500 µg/ft^2^       800 µg/ft^2^
                      µg/ft^2^     µg/ft^2^                       

  **LHR+W Units**     14           11         17                  14

  **Balt. HUD Units** 57           NA         11                  35
  ------------------- ------------ ---------- ------------------- ----------------

Although dust lead loadings remained less than pre-intervention levels
and a large percentage of units had dust lead loadings less than HUD
clearance standards at one year post-intervention, inspections conducted
by LAAP inspectors one year after treatments were first implemented
found that 96% of the 73 units had at least one visual assessment
"failure" (see Table E-7 on page 9). The most common "failures" were the
same as those identified at immediate post-intervention: not all paint
intact (93%), doors continuing to rub (41%) and visible chips or debris
(29%). It should be noted that, for the visible paint chips or debris,
the areal density (i.e., depth) of the chips/debris and the lead
concentration in those chips/debris was not measured. A geometric
mean[^5] of 1 ft^2^ of paint was not intact, 1 ft^2^ of paint chips or
debris remained, and 4 ft^2^ of flooring was not smooth and cleanable.
While these types of problems were reportedly treated after immediate
post-intervention dust samples were collected and visual assessments
were performed, these results are not entirely surprising given that few
units appeared to experience turnover or had further treatments during
the one-year post-intervention period.

For each surface type, a multiple regression model with backward
elimination[^6] was run to identify factors that were significant
predictors of one-year post-intervention dust lead loadings. The only
significant predictor of bare floor dust lead loadings was the percent
of rooms with visual assessment "failures" at one year
post-intervention. Pre-intervention sill dust lead loadings and assigned
treatment group were significant predictors of one-year
post-intervention

sill dust lead loadings. Assigned treatment group was the only
significant predictor of one year post-intervention trough dust lead
loadings.

**Table E-7: Number of One-Year Post-Intervention Visual Assessment
"Failures" Per Unit^a^**

+-----------------------------------+----------+----------+----------+
| **Number of Visual Assessment     | **LHR**  | *        | **All    |
| "Failures" Per Unit**             |          | *LHR+W** | Units**  |
|                                   | **\#     |          |          |
| **(36 LHR units, 37 LHR+W         | Units**  | **\#     | **\#     |
| units)**                          |          | Units**  | Units**  |
|                                   | **(%     |          |          |
|                                   | Units)** | **(%     | **(%     |
|                                   |          | Units)** | Units)** |
+-----------------------------------+----------+----------+----------+
| "0" One-yr post-int visual        | 0        | 3 (8%)   | 3 (4%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "1" One-yr post-int visual        | 8 (22%)  | 13 (35%) | 21 (29%) |
| assessment "failure"              |          |          |          |
+-----------------------------------+----------+----------+----------+
| "2" One-yr post-int visual        | 12 (33%) | 9 (24%)  | 21 (29%) |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "3" One-yr post-int visual        | 11 (31%) | 9 (24%)  | 20 (27%) |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "4" One-yr post-int visual        | 3 (8%)   | 3 (8%)   | 6 (8%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "5" One-yr post-int visual        | 2 (6%)   | 0        | 2 (3%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+

Source: Form 05

^a^For the purposes of this study, a treatment "failure" was defined as
an observation by the LAAP inspector that one or more of the ten lead
hazard reduction treatments prescribed in the statute had not been fully
completed. "Failure" was counted on a per unit basis. Within each unit,
"failures" were listed by room ID.

For floors, sills and troughs, a logistic regression model with backward
elimination^6^ was run to identify factors that were significant
predictors of whether units would have clearance "failures" at immediate
post-intervention based on floor, sill and trough standards of 100
μg/ft^2^, 500 μg/ft^2^ and 800 μg/ft^2^, respectively. For bare floors,
the only significant predictor of one-year post-intervention composite
results exceeding 100 µg/ft^2^ was the year of construction. For sills,
pre-intervention sill dust lead loadings and assigned treatment group
were significant predictors of one-year post-intervention composite dust
lead loadings exceeding 500 µg/ft^2^. For troughs, the only significant
predictor of one-year post-intervention composite dust lead loadings
being above 800 µg/ft^2^ was assigned treatment group.

Finally, a Poisson regression model with backward elimination^6^ was
employed to identify factors that are significant predictors of visual
assessment "failures" at one-year post-intervention. Significant
predictors were lead hazard reduction cost at Phase II, building type,
whether work had been performed during the past year and the estimated
market value of the dwelling.

# Summary of Study Findings

The main findings of this study are that dust lead loadings declined
substantially immediately after EA 6-8 prescribed lead hazard reduction
treatments were implemented. However, many units would not have "passed"
clearance dust tests immediately following treatment had such testing
been required. In addition, the prescribed independent visual
inspections conducted in these units immediately following treatment
generally missed many treatment "failures." At one year
post-intervention, dust lead loadings generally remained very low, with
over 80 percent of units having floor, sill and trough dust lead
loadings that were below clearance standards. However, almost every unit
had at least one visual assessment failure one year after treatment.

Based on study findings, it is recommended that:

-   Appropriate state agencies should increase oversight of independent
    visual inspectors to ensure that such inspectors are performing
    visual inspections in accordance with approved protocols and
    inspector training;

-   Clearance dust testing should be added to the independent visual
    inspection as part of the lead hazard reduction treatment
    requirements of EA 6-8, either by regulation or by amendment to the
    statute;

-   Rental property owners and their crews and independent contractors
    should perform a more intensive final cleaning upon completion of
    the prescribed treatments;

-   More comprehensive window treatments may be needed to ensure that
    interior window sills and troughs do not continue to be an exposure
    source for lead; and

-   Proper adjustment and re-hanging of doors to eliminate friction
    points should be an emphasis of the prescribed treatments.

# INTRODUCTION

## Background and Purpose of this Study

In May 1994, then Maryland Governor William Donald Schaefer signed
comprehensive legislation into law that was designed to further two
primary goals: the prevention of childhood lead poisoning resulting from
deteriorating lead-based paint and the preservation of the state's
affordable rental housing stock. "The Lead Poisoning Prevention
Program," codified variously in the Environmental Article as Section
6-801 et. seq. (EA 6-8), in the Insurance Article as Section 734 et.
seq. and in the Real Property Article as Section 8-208.2 et. seq. of the
Maryland Annotated Code, was to have become effective on October 1,
1994. However, due to inevitable delays in promulgating and implementing
regulations by the Maryland Department of the Environment (MDE), the law
did not become fully effective until February 24, 1996.

EA 6-8 applies to all privately owned rental housing constructed prior
to 1950 (referred to as "target housing" in the law) and, at a property
owner's option, to any residential rental property constructed after
1949 but prior to 1978. The heart of the law is a system and schedule
for reducing lead-based paint hazards at rental unit turnover by meeting
a prescribed "risk reduction standard," as found in Section 6-815. The
standard can be met by performing tests to verify that surface dust lead
loadings in affected property are within acceptable limits or,
alternatively, by performing prescribed "lead hazard reduction
treatments." These treatments include the following:

-   A visual review of all exterior and interior painted surfaces;

-   The removal and repainting of chipping, peeling or flaking paint on
    exterior and interior painted surfaces;

-   The repair of any structural defect that is causing the paint to
    chip, peel or flake that the owner of the affected property has
    knowledge of or, with the exercise of reasonable care, should have
    knowledge of;

-   Stripping and repainting, replacing or encapsulating all interior
    window sills with vinyl, metal or any other material;

-   Ensuring that caps of vinyl, aluminum or any other material are
    installed in all window wells in order to make the window wells
    smooth and cleanable;

-   Except for a treated or replacement window that is free of
    lead-based paint on its friction surfaces, fixing the top sash of
    all windows in place in order to eliminate the friction caused by
    movement of the top sash;

-   Re-hanging all doors necessary in order to prevent the rubbing
    together of a lead-painted surface with another surface;

-   Making all bare floors smooth and cleanable;

-   Ensuring that all kitchen and bathroom floors are overlaid with a
    smooth, water-resistant covering; and

-   HEPA-vacuuming and washing of the interior of the affected property
    with high phosphate detergent or its equivalent.

Lead hazard reduction treatments could be performed by a for-profit
contractor, the property owner and/or his/her employees, or by a
non-profit contractor. Regardless of their affiliation, all individuals
performing risk reduction measures had to meet state and federal lead
training, certification, and licensing requirements.

At each change in occupancy, an owner is required to have the housing
unit inspected to verify that the lead hazard reduction treatments have
been implemented. This is accomplished by having a visual inspection
performed by an independent inspector certified by MDE.

In essence, under EA 6-8, children and their representatives cannot sue
for traditional tort damages for lead poisoning if the rental property
owner has met the risk reduction standard and certain housing unit
registration requirements. Additionally, the owner and/or his or her
property insurer must make a "qualified offer" to a resident child and
his or her legal representative when the child's blood lead level has
exceeded 25 micrograms per deciliter (25 μg/dL) of blood. The qualified
offer is, in effect, a remedial compensation settlement of the child's
potential lead poisoning claim, which is designed to pay for necessary
out-of-pocket medical treatment and relocation costs for the child's
family to move to "lead-safe" housing, up to a combined total of
\$17,000.

Because of this limited tort immunity and concerns over whether the
prescribed lead hazard reduction treatments are protective of children's
health, some critics of EA 6-8 have charged that the failure to require
clearance dust testing upon completion of the treatments constitutes a
major deficiency in the law. Many have questioned whether these
treatments would, in fact, result in safer home environments in the
absence of dust testing. For this reason, there was a need to evaluate
the efficacy of both the prescribed treatments and the independent
visual inspection protocol.

Although the legislature directed the Maryland Lead Poisoning Prevention
Commission to study and collect information on the effectiveness of the
bill's prescribed lead hazard reduction treatments, the legislature did
not specifically earmark funding for such an evaluation. Therefore, the
National Center for Lead-Safe Housing (Center) and the Baltimore City
Healthy Start, Inc. (Healthy Start) elected to independently evaluate
the aforementioned measures through a US Department of Housing and Urban
Development, Office of Healthy Homes and Lead Hazard Control (HUD
OHHLHC) funded research project. Specifically, the Center was funded
under the HUD OHHLHC Lead Hazard Control Round Three Grant to the
Baltimore City Health Department (Grant No. MDLAG0045-95). (Initial
funding received from the Abell Foundation also aided in the development
of this study.) Working with the HUD OHHLHC, Healthy Start and the
Baltimore City Health Department's Lead Abatement Action Program (LAAP),
the Center designed this study and has analyzed all data collected.

# Specific Research Aims and Objectives

The primary goal of this study was to evaluate the efficacy of the EA
6-8 lead hazard reduction treatments, both in units that undergo these
treatments alone and in units in which the treatments plus window
replacement have been carried out. This report documents the extent to
which lead hazards were reduced immediately following treatment,
primarily by comparing the level of lead loading in household dust
collected shortly before the lead hazard reduction intervention with the
level of dust collected immediately after the intervention. This report
also includes a further evaluation of lead treatment efficacy using the
results of dust lead sampling and visual assessments conducted 12 months
post-intervention. Limited data collected at approximately 24 months
post-intervention are also summarized.

Key questions for the study are:

1.  How effective are the prescribed treatments in reducing dust lead
    loading on floors, interior window sills and window troughs (i.e.,
    window wells) to acceptable levels?

    1.  To what extent does lead dust re-accumulate on these surfaces
        over a one- and two-year period after completion of the
        treatments?

    2.  Does the replacement of windows in units that also undergo the
        prescribed treatments result in substantially lower dust lead
        loadings immediately after completion of the treatments?

    3.  Do single surface dust wipe sample and composite dust wipe
        sample results correlate well in measuring dust lead loadings
        both before and after completion of the prescribed treatments?
        (Note: Since this question does not specifically apply to an
        evaluation of EA 6-8, related findings are presented in Appendix
        J and are not discussed in the body of this report.)

    4.  Aside from lead dust sample results, do independent visual
        inspections accurately assess whether the prescribed treatments
        have been completed?

Specific objectives for this report are to:

1.  Describe the physical characteristics and baseline (i.e.,
    pre-intervention) condition of enrolled housing units, including
    dust lead loading on floors, interior window sills and window
    troughs;

2.  Describe the immediate post-intervention condition of the enrolled
    units, including their conformance with the prescribed lead hazard
    reduction treatments and whether they would pass an independent
    visual inspection, the dust lead loading and the number of windows
    replaced in the window replacement subset;

3.  Describe the relationship between baseline building characteristics
    and dwelling unit conditions and the type of lead hazard reduction
    intervention performed (i.e., lead hazard reduction treatments only
    and lead hazard reduction treatments plus window replacement);

4.  Compare the efficacy of the prescribed lead hazard reduction
    treatments and the prescribed treatments plus window replacement in
    reducing dust lead loadings and bringing post-intervention dust lead
    loadings below "clearance" standards established by MDE and by the
    HUD OHHLHC and the US Environmental Protection Agency (EPA) as
    "guidance;"

5.  Describe the dust lead loading data and post-treatment/visual
    inspection data for the enrolled dwelling one and two years after
    completion of the treatments;

6.  Describe the relationship between such factors as type and age of
    building, baseline condition, type of contractor, amount and
    character of any concurrent work, turnover treatment, any notice of
    newly identified lead hazard or of a child with an elevated blood
    lead level and the effectiveness of the treatments, including dust
    lead loading and continued conformance with EA 6-8 standards; and

7.  Quantify any additional effectiveness of window treatment in
    maintaining low dust lead loadings.

Originally, there were plans to compare immediate post-intervention dust
wipe results with those collected at one year post-intervention;
however, visual assessment \"failures\" found at immediate
post-intervention were corrected upon discovery. Therefore, comparison
of immediate post-intervention dust wipe data with one year
post-intervention data is not appropriate.

# STUDY DESIGN AND SAMPLE COLLECTION PROCEDURES

## Overview of the Study Design

LAAP originally planned to enroll 200 housing units in the study,
primarily three-bedroom, two-story single-family rowhouses of
approximately 900 to 1200 square feet located in Baltimore City. One
hundred (100) of these units were to receive the prescribed EA 6-8 lead
hazard reduction treatments (LHR) while the other 100 were to receive
the prescribed lead hazard reduction treatments [plus]{.underline} full
window replacement (LHR+W).

The original goal of 200 study units was increased to 250 units to allow
for an anticipated 20 percent attrition rate per sampling/inspection
phase. However, as a result of difficulties with attracting rental
property owners to the program, suitability of certain units because of
pre-existing conditions (e.g., structural defects), inability of some
property owners to self-finance 20 percent of the lead hazard reduction
measures costs, grant approval delays and other administrative factors,
that goal was reduced to 180 units and then, finally, to 150 units. In
the end, 177 units underwent pre-intervention inspections and 121 units
completed post-intervention inspections, prior to the cut-off date of
October 1, 1999 for completing lead hazard reduction measures in
enrolled units.

LAAP did not specify how the treatments were to be carried out, with the
exception of a model window replacement specification. Instead, property
owners provided LAAP with treatment specifications and cost estimates;
LAAP inspectors then reviewed the specifications and costs, and made
adjustments with the owner's knowledge and consent. All units were
vacant at the time of developing the specifications and costs, and
during performance of the intervention.

LAAP inspectors collected data from enrolled units during four (4)
sampling/inspection phases:

-   Pre-Intervention (Phase I): within four (4) weeks prior to the
    property owner and his/her contractor performing the lead hazard
    control intervention;

-   Immediate Post-Intervention (Phase II): immediately after completion
    of the treatments [and]{.underline} the visual inspection (i.e., no
    more than three days), as performed by an independent inspector
    hired by the owner;

-   One-year post-intervention (Phase III): 12 months post-intervention
    (generally within 6 weeks of the 12-month anniversary); and

-   Two-years post-intervention (Phase IV): 24 months post-intervention
    (generally with 6 weeks of the 24-month anniversary).

At each phase, LAAP inspectors took composite dust samples in all
enrolled housing units. Additionally, single surface samples were taken
in the LHR+W units. LAAP inspectors also performed visual assessments
for dwelling unit conditions at each phase. Finally, cost and concurrent
work information was collected immediately after the intervention.

## 

## Recruitment and Enrollment Process

LAAP was responsible for the recruitment and enrollment of housing units
from within the city of Baltimore. As an incentive to enroll units in
the study, rental property owners would receive 80 percent of the lead
hazard reduction treatment costs in the form of a grant, up to a cap of
\$10,000; the remaining 20 percent would have to be self-funded. This
funding was provided through LAAP's HUD OHHLHC Round III Lead Hazard
Control Grant. A LAAP grant coordinator kept track of owners'
contributions, which had to be received before the unit could go to
settlement.

Participating rental property owners were asked to enroll two (2) units
in the study: a LHR unit and a LHR+W unit. A initial limit of four (4)
enrolled units per owner was eventually lifted, although the goal
remained to keep the ratio of LHR to LHR+W units at one to one for each
participating owner and for the study overall.

In order to qualify for the grant, the property owner had to
substantiate that the unit was registered with MDE (as per EA 6-8
requirements), provide evidence of fire insurance on the unit, produce
documentation of acceptable lead treatment specifications and costs
prior to construction, agree to rent the enrolled unit to low-income
families for a period of five years, maintain rents affordable to
low-income families for the unit, agree to dust testing and visual
assessment of the unit until 24 months post-intervention, and sign a
grant contract. Costs were first estimated by owners or their
representatives, then reviewed by LAAP and revised if spending caps were
exceeded or other deficiencies were noted.

Recruitment efforts did not begin until late 1996. At that point, LAAP
and Center personnel made a presentation to several representatives of
the Property Owners Association of Greater Baltimore. Additionally, a
"notice of funding availability" was published and LAAP asked MDE and a
local childhood lead poisoning prevention advocacy organization for
assistance in directing property owners to the program. In order to
pilot test the data collection forms and protocols, four owners enrolled
two (2) units each, one LHR and one LHR+W, for a total of eight (8)
pilot study units. These owners received full reimbursement of their
treatment costs as an incentive to participate in the pilot.

## Selection Criteria for Enrolled Units

In addition to the aforementioned recruitment and enrollment criteria, a
housing unit had to be located in Baltimore City, constructed prior to
1950, vacant at the time of the intervention and structurally sound, as
determined by a LAAP screening inspection, to qualify for this study.
Only pre-1950 rental units were enrolled since these units were
automatically subject to the law's prescribed risk reduction standard.

Conditions that could exclude a unit from the study included, but were
not limited to:

-   Roof and plumbing leaks;

```{=html}
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```
-   Unsound floor or wall structures;

-   Non-functional baths or kitchens;

-   Non-working utilities, including plumbing, electrical and heating
    systems;

-   Pest and vermin problems;

-   Excessive surface problems, such as holes, cracks, excessive peeling
    paint or plaster deterioration;

-   A property with building code violations;

-   A unit with an existing lead violation when the prescribed lead
    hazard reduction treatments would not satisfy the violation notice;

-   More than 14 windows in the unit;

-   Size of the dwelling unit (e.g., greater than 1200 square feet);

-   Units deemed to be a threat to the safety of LAAP inspectors;

-   Rents to be charged post-intervention that would exceed \$450 per
    month; and

-   Failure to register the unit with MDE, in accordance with the EA 6-8
    requirements.

Eligibility of owners for grant funds and units for enrollment in the
study was sometimes conditional based on the screening inspection. On
occasion, LAAP was able to assist owners with structural issues by
allowing up to \$500 towards increasing structural integrity or fixing
leaks (e.g., toward a new roof). If an owner corrected one or more
observed deficiencies, the unit might be accepted and the owner would
then be required to prepare detailed work specifications for the
intervention, closely following the prescribed lead hazard reduction
treatments. After a final pre-intervention walk-through inspection by
LAAP, the unit would be approved to proceed with construction.
Information on pre-program repairs was not collected as part of this
research study.

A.  **Data Collection Forms and Protocols**

LAAP inspectors were trained by Center personnel to follow the data
collection protocols and complete the eight (8) data collection forms
used for this study (see Table 1 on page 17 and Appendix A).

**Table 1: Data Collection Form Type and Usage**

+-----------------------+----------+----------+----------+----------+
| # Form Name           | #        | # P      | # Ph     | **Phase  |
|                       | Phase I: | hase II: | ase III: | IV:**    |
|                       |          |          |          |          |
|                       | # Pre    | **I      | # 12     | **24 Mo. |
|                       |          | mmediate | Mo. Post | Post**   |
|                       | **Interv | Post**   |          |          |
|                       | ention** |          | ###      | **Interv |
|                       |          | **Interv | ### Inte | ention** |
|                       |          | ention** | rvention |          |
+-----------------------+----------+----------+----------+----------+
| Form 01 -- Building   | X        |          |          |          |
| and Dwelling Unit     |          |          |          |          |
| Information           |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 02 -- Baseline   | X        |          |          |          |
| Dwelling Condition    |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 03 -- Sketch of  | X        |          |          |          |
| Sampling Locations    |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 04A -- Dust      | X        | X        | X        | X        |
| Sample Collection     |          |          |          |          |
| (Composite)           |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 04B -- Dust      | X        | X        | X        | X        |
| Sample Collection     |          |          |          |          |
| (Single Surface)      |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 05 -- Post       |          | X        | X        | X        |
| Treatment             |          |          |          |          |
| Assessment/Visual     |          |          |          |          |
| Inspect.              |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 06 -- Follow-Up  |          |          | X        | X        |
| Questions             |          |          |          |          |
+-----------------------+----------+----------+----------+----------+
| Form 07 --            | \*^a^    | \*^a^    | \*^a^    | \*^a^    |
| De-Enrollment Form    |          |          |          |          |
+-----------------------+----------+----------+----------+----------+

^a^Form 07 was only completed if a unit was de-enrolled from the study.

Form 01 -- *Building and Dwelling Unit Information* was designed to
collect basic information about the type of building (e.g., single
detached, row house, duplex, etc.), year of construction, estimated
market value (obtained directly from the property owner), number of
rooms, bedrooms, windows and approximate square feet of living space.
This form was completed once: during the pre-intervention phase (i.e.,
Phase I).

Form 02 -- *Baseline Dwelling Conditions* was designed to collect
information about obvious exterior building deterioration on roofs,
gutters, downspouts, chimneys, walls and siding, windows and doors,
porches and steps and the foundation, and whether the exterior ground
was contaminated with paint chips. It also was used to collect
information about interior dwelling unit deterioration on walls,
ceilings, doors and trim, floors, heating/cooling and plumbing systems,
interior damage from roof leakage and paint condition. This form was
completed once: during the pre-intervention phase (i.e., Phase I).

Form 03 -- *Sketch of Sampling Locations* was designed to record room
and dust sampling locations on a sketch of each interior floor, which
included room layouts. It was also used to code room numbers for the
purpose of room identification on other forms. Even though this form was
a reference source for room and sample locations during subsequent
inspection/sampling phases, it was completed only once: during the
pre-intervention phase (i.e., Phase I).

Form 04A -- *Dust Sample Collection (Composite)* was designed to record
a variety of data for composite dust samples, including type of surface
sampled (e.g., smooth floors, interior window sills, window troughs),
room and sample locations, dimensions of the surfaces sampled, total
area sampled, sample number, total micrograms of lead per composite
sample and average lead loading results measured as micrograms of lead
per square foot (μg/ft^2^). The form also recorded observations
regarding unit cleanliness and occupancy status. It was completed during
each of the four sampling phases in all units.

Form 04B -- *Dust Sample Collection (Single Surface)* was designed to
record data similar to Form 04A, except that it applied solely to single
surface samples. Originally intended strictly for LHR+W units, Form 04B
was also used for a number of LHR units as well. The form was completed
during each of the four sampling phases.

Form 05 -- *Post Treatment Assessment/Visual Inspection*, a two-page
form, was designed to collect immediate post-intervention information on
whether the unit was LHR or LHR+W and, if the latter, how many windows
were replaced. It also captured information on the type of contractor
performing the work (for-profit, nonprofit or property owner), the cost
of the LHR, the cost of window replacement (if applicable), the
estimated turnover cost of the unit had it not been subject to EA 6-8
lead hazard reduction requirements, concurrent work (if any) performed
by the owner, and dates the work started and was completed. Form 05 also
contained a list of 10 questions designed to determine whether there was
visual evidence that the unit had met the prescribed lead hazard
reduction treatments. For any observed "failure" of a prescribed
treatment, page 2 of the form was used to record the type of "failure,"
room and location, quantity and units of measurement, and LAAP
inspector's notes on the "failure." This form was completed three times:
immediate post-intervention, 12 months post-intervention and 24 months
post-intervention (i.e., Phases II, III and IV).

Form 06 -- *Follow-Up Questions* was designed to collect information
from the property owner about any activities that occurred in the unit
in the 12 and 24-month periods after the intervention. This information
included whether any additional lead hazard reduction treatments were
conducted in the unit, whether the unit had turned over and how many
times, whether a tenant called to report a newly identified lead hazard,
whether the owner was notified of a resident child with an elevated
blood lead level, and whether a "qualified offer" was made to any
resident child with a blood lead level equal to or in excess of 25
μg/dL.

# 

# Dust Lead Sampling Protocols

LAAP inspectors collected all dust wipe samples for this study. These
inspectors were trained and certified as both lead-based paint
inspectors and lead-based paint risk assessors under applicable MDE
regulations.

The dust sampling protocol was designed to yield information on dust
lead loadings from floors (including bare and carpeted floors), interior
window sills and window troughs (also known as window wells or exterior
window sills) using both composite and single surface sampling. Samples
were collected during all four sampling/inspection phases. Originally,
composite dust samples were to have been taken in all enrolled units,
with single surface samples being collected only in the LHR+W units.
However, because of problems with the initial analytical laboratory
selected for this study, single surface samples were also taken as a
precautionary measure in LHR units first inspected during the period
from approximately November 1, 1997 until February 1, 1998, when a new
laboratory was retained to replace the original laboratory.

The HUD wipe sampling method, utilizing moist towellettes placed in
50-milliter (ml) hard shell plastic centrifuge tubes, was initially
employed. Later, after the new analytical laboratory was retained, 125
ml glass jars with plastic lids were used to hold the towellettes.
Plastic templates measuring 8 inches by 9 inches (72 square inches or
one-half square foot total) were secured to bare or carpeted floor
sampling areas. Additionally, plastic templates measuring 2 inches by 18
inches (36 square inches or one-quarter square foot total) were secured
to interior window sills, when possible. All plastic templates were
carefully cleaned between samples. Masking tape was used to define wipe
sampling areas within window troughs and on interior window sills if
templates were impractical. When masking tape was used to define
composite sub-sample areas, care was taken so that each sub-sample area
was within plus or minus 15 percent of other sub-sample areas for a
given composite sample type.

*Composite dust samples* contained no less than two and no more than
four sub-samples and were collected from the following rooms, according
to surface type:

[Bare floor sub-sample locations]{.underline}:

1.  Entryway (just inside the exterior doorway, slightly left of
    center);

2.  Living room/principal play area of children (slightly left of center
    of the exterior doorway);

3.  Kitchen (slightly left of center of the interior doorway); and

4.  Bedroom #1/smallest bedroom (slightly left of center of the
    doorway).

> If any of the above rooms had wall-to-wall carpeting, a separate
> composite sample was created, with sub-samples being collected from
> these carpeted rooms. (As discussed later, very few units had carpeted
> floors. Therefore, sample results for carpeted floors are not further
> discussed in this report.)
>
> [Window sub-sample locations (sill and troughs as separate composite
> samples)]{.underline}:

1.  Living room/principal play area;

2.  Kitchen;

3.  Bedroom #1/smallest bedroom; and

4.  Bedroom #2/next smallest bedroom.

> Window sub-samples were collected from the left half (looking out) of
> each window unit. Only one window per room was sampled, with the
> selected window being sampled during subsequent sampling/inspection
> phases.

*Single surface samples* were collected from the rooms listed below,
according to surface type. All single surface samples were collected to
the right of each defined area as one looks into a given room or out of
a given window.

[Floor sample locations (bare or carpeted)]{.underline}:

1.  Entryway (just inside the exterior doorway);

2.  Living room/principal play area (just inside the exterior doorway);

3.  Kitchen (just inside the interior doorway);

4.  Bedroom #1/smallest bedroom (just inside the interior doorway); and

5.  Bedroom #2/next smallest bedroom (just inside the interior doorway).

### Interior window sill sample locations:

1.  Kitchen; and

2.  Bedroom #1/smallest bedroom.

### Window trough locations:

1.  Living room/principal play area; and

2.  Bedroom #2/next smallest bedroom.

Using Forms 04A and 04B, LAAP inspectors completed laboratory submittal
forms, sent the forms and samples out to the analytical laboratory and
then transcribed dust lead loading results onto the forms after
receiving this information from the lab.

LAAP inspectors also collected field blank samples of both the composite
and single surface type after sampling the final dwelling unit of the
day. Additionally, dust-spiked samples prepared by the University of
Cincinnati, using the National Institute of Standards and Technology
(NIST) Standard Lead Paint Dust, were inserted into the sampling stream
by the inspectors at a rate of one for every 50 single surface samples
and one for every 20 composite samples collected. Each composite field
blank sample and spike sample was comprised of four wipes. The
laboratory was blinded to all spike samples.

# 

# Visual Assessment Protocols

In addition to collecting composite and single surface dust wipe
samples, LAAP inspectors performed visual assessments during all four
sampling/inspection phases.

Pre-intervention visual assessments were accomplished by observing
existing building and dwelling unit conditions for signs of
deterioration followed by completing the questions on Forms 01 and 02.
Also, diagrams of the dwelling unit floor plan were prepared using Form
03. Immediate post-intervention visual assessments required LAAP
inspectors to closely inspect the building and dwelling unit for
completion of the prescribed lead hazard reduction treatments. Utilizing
Form 05, the inspectors would visually assess each room in the unit and
certain portions of the building exterior. Any observed treatment
"failures" would be recorded on the form along with the room in which
the "failure" was found and the amount of and unit of measure for the
"failure" (e.g., 10 square inches of chipping, flaking or peeling paint.

Once lead hazard reduction interventions were complete, and in
anticipation of having an independent inspector perform the prescribed
visual inspection, participating property owners and/or their
contractors would contact LAAP inspectors and advise them that a unit
was ready for dust sampling, visual assessment [and]{.underline} a final
construction walk-through. The LAAP inspectors would then collect
samples and perform the visual assessment, usually immediately after the
independent inspector had inspected the unit for compliance with the
prescribed treatments.

Because the program paid for up to 80 percent of all pre-approved
intervention costs, LAAP inspectors had to perform the walk-through
[after]{.underline} the dust sampling and visual assessment to determine
if the original intervention specifications had been completed. If any
specification was incomplete or improperly performed, the owner and/or
contractor was instructed to finish the work before LAAP would release
its final payment for the intervention.

By following this sequence and protocol, LAAP inspectors sought to avoid
influencing unit conditions that might improve dust sampling and visual
assessment results. The overarching objective was to collect samples and
to visually assess the same conditions that the independent visual
inspector would have observed at the time of his/her compliance
inspection. However, in a handful of units, the LAAP inspectors did not
proceed with the sampling and visual assessment when an obvious
treatment had been missed (e.g., stripping and repainting or replacing a
window sill). In those cases, the inspectors would return after such
missed treatments were completed, obtain dust samples and visually
assess the unit.

As noted above, if the LAAP inspectors found any specification that was
incomplete or improperly performed, the owner and/or contractor was
instructed to finish the work before LAAP would release its final
payment for the intervention. Therefore, the one-year and two-years
post-intervention inspections were checks of how well treatments
remained in place 12 and 24 months, respectively, following the
completion of all immediate post-intervention work.

# LABORATORY ANALYSIS PROCEDURES

As a prerequisite, the analytical laboratory selected to analyze dust
samples for this study had to be recognized by EPA as participating in
the National Lead Laboratory Accreditation Program (NLLAP). The lab had
to show evidence of being proficient in lead analysis under the
Environmental Lead Proficiency Analytical Testing Program (ELPAT). All
dust samples had to be analyzed for total lead as required in the HUD
*Guidelines for the Evaluation and Control of Lead-Based Paint Hazards
in Housing*. Because of problems detected in the analysis of the
composite samples by the first laboratory (designated "Lab A"), a second
laboratory ("Lab B") was hired to replace Lab A as the study laboratory
(see Appendix B for details). Analytical procedures for each laboratory
are provided in Appendix B. Lab B was used for the analysis of all
one-year and two-years post-intervention data.

# QUALITY ASSURANCE AND QUALITY CONTROL

##  A. Laboratory Quality Assurance and Quality Control

1.  ***Quality Control Spiked Dust Wipe Sample Results***

As noted above, LAAP inspectors periodically submitted single surface
and composite spiked dust wipe samples (using the NIST standard) to the
study laboratory. Early in the project, LAAP and the Center noted
deficiencies in composite spike recoveries and other observations that
led LAAP to replace Lab A with Lab B. Samples potentially associated
with Lab A's unacceptable composite spike results were excluded from all
analyses presented in this report. No other samples were excluded on the
basis of QC spike sample results. Spike sample submittal procedures, as
well as details concerning the spike results, are provided in Appendix
B.

2.  ***Quality Control Field Blank Dust Wipe Sample Results***

As noted in Section III.E, composite and single surface field blank dust
wipe samples were prepared by LAAP inspectors and submitted to the
laboratory after sampling the final dwelling unit of the day.

The presence of detectable lead in a field blank sample could suggest
several potential problems: sample collection may have been poorly
conducted (e.g., lead may in fact have been introduced into a sample
container from an inspector's glove, a contaminated sample container, or
from other sources not under experimental control); contamination and
poor sample handling may have occurred at the laboratory; or there may
have been errors in laboratory measurement procedures. For both Lab A
and Lab B, composite and single surface field blank results were
considered acceptable. Therefore, no composite or single surface samples
were excluded from this report based on field blank results. Details
concerning field blank results are provided in Appendix B.

3.  ***Procedures for Dust Wipe Sample Results that Were At or Below
    Laboratory Report Limits***

A high percentage of both composite and single surface dust wipe sample
results were below the reporting limits of both Lab A and Lab B. Lab A's
reporting limits varied from 5 µg/sample to 24 µg/sample, Lab B's single
surface sample reporting limit was 10 µg/sample, and Lab B's composite
sample reporting limit was 20 µg/sample.

Because one of the most important measures of intervention outcome --
the change in dust lead loadings over time -- could be at or below the
laboratory's reporting limits, Lab B supplied the actual machine values
for composite and single surface samples with lead content below
reporting limits. For the few cases in which Lab B reported a machine
value of zero (i.e., the sample's lead content could not be
distinguished from the machine's "background noise"), the zero values
were replaced with the laboratory's reporting limit divided by the
square root of two. Lab A did not supply actual machine values; sample
results reported by this laboratory to be at or below reporting limits
were also replaced with a value calculated by taking Lab A's reporting
limit and dividing it by the square root of two. Based on data shown in
Table 2, a total of 133 results underwent this conversion.

# Table 2: Dust Wipe Sample Results Below Reporting Limits or Reported As Zero^a^

+----------------+------------+-------------+------------+------------+
| ######         | **Pre-Inte | **Immediate | **One-Year | *          |
|                | rvention** | Post-Int    | Post-In    | *Two-years |
| ###### S       |            | ervention** | tervention | post-in    |
| urface Type^b^ | *          |             | Samples**  | tervention |
|                | *Samples** | **Samples** |            | Samples**  |
|                |            |             | **\#       |            |
|                | **\#       | **\#        | Sam        | **\#       |
|                | Sam        | Sa          | ples/Total | Sam        |
|                | ples/Total | mples/Total | (%         | ples/Total |
|                | (%         | (%          | Samples)** | (%         |
|                | Samples)** | Samples)**  |            | Samples)** |
+----------------+------------+-------------+------------+------------+
| [Bare          | 0/148      | 3/108 (3%)  | 3/68 (4%)  | 1/24 (4%)  |
| Floor          | (0.0%)     |             |            |            |
| ]{.underline}: |            | 49/373      | 11/168     | 3/64 (5%)  |
|                | 1/467      | (13%)       | (6%)       |            |
| Composite      | (0.2%)     |             |            |            |
|                |            |             |            |            |
| Single Surface |            |             |            |            |
+----------------+------------+-------------+------------+------------+
| [Window        | 1/152      | 4/116 (3%)  | 0/73 (0%)  | 0/24 (0%)  |
| Sill           | (0.7%)     |             |            |            |
| ]{.underline}: |            | 28/164      | 8/76 (10%) | 0/26 (0%)  |
|                | 1/196      | (17%)       |            |            |
| Composite      | (0.5%)     |             |            |            |
|                |            |             |            |            |
| Single Surface |            |             |            |            |
+----------------+------------+-------------+------------+------------+
| [Window        | 1/152      | 4/116 (3%)  | 0/72 (0%)  | 0/24 (0%)  |
| Trough         | (0.7%)     |             |            |            |
| ]{.underline}: |            | 13/157 (8%) | 1/75 (1%)  | 0/26 (0%)  |
|                | 0/191      |             |            |            |
| Composite      | (0.0%)     |             |            |            |
|                |            |             |            |            |
| Single Surface |            |             |            |            |
+----------------+------------+-------------+------------+------------+
| Total All      | 4/1306     | 101/1034    | 23/532     | 4/188 (2%) |
| Surface Types  | (0.3%)     | (10%)       | (4%)       |            |
| and Sample     |            |             |            |            |
| Types          |            |             |            |            |
+----------------+------------+-------------+------------+------------+

^a^Lab A recorded results below reporting limits and Lab B recorded
results as zero.

^b^Because very few units had carpeted floors, sample results for
carpeted floors were excluded from this study.

A.  **Performance Audit of Field Data Collection Activities**

On six different occasions, Center staff observed LAAP inspectors in the
field collecting single surface and composite dust wipe samples,
performing visual assessments and completing the data collection forms.
LAAP inspectors were critiqued for their adherence to the data
collection protocols and their dust wipe sampling technique. Although
the LAAP inspectors generally performed to expectations, the Center\'s
representatives provided on-site guidance and written recommendations to
improve sampling and data collection.

During several visits to the LAAP office, Center staff reviewed unit
files and other project documentation for completeness and adherence to
the study protocols. Center representatives also made on-site and
written recommendations for improvements during these visits,
particularly regarding tracking of follow-up inspection assignments.

B.  **Data Audit and Data Completeness**

The Center was responsible for auditing all data submitted by LAAP for
correctness, completeness and adherence to the data collection
protocols. After completion by LAAP inspectors, data collection forms
(and laboratory analysis reports) were submitted to the Center for
initial review and, if appropriate, data entry and processing. Center
staff reviewed each form for missing and/or unclear answers and data,
use of proper answer codes and values, insertion of correct laboratory
results and calculation of dust lead loading, and consistency of room
number assignments and sampling locations across the different
sampling/inspection phases. When errors and/or missing information were
detected, the Center would return forms to LAAP, with detailed
instructions for correction or clarification unless questions could be
resolved easily by telephone. LAAP would then make revisions and return
the corrected forms to the Center, which then performed a final audit
before preparing the forms for data entry.

# 

# DATA PROCESSING AND STATISTICAL ANALYSIS PROCEDURES

## Data Entry and Processing

The Center was responsible for all data entry and data processing. An
electronic facsimile, as well as the actual hard-copy version, of each
data collection form was created in Jetform's FormFlow software program.
After receiving the completed field forms from LAAP, the Center's Data
Coordinator would enter data from the field forms directly into the
electronic version of the forms in FormFlow. A hard-copy of the
completed form was then printed out and reviewed for errors and/or
missing information by the Data Coordinator and other Center staff.
After corrections were made and entered into the electronic version of
the form, a revised hard copy of the form, along with the LAAP field
form, was placed in a file folder created for each enrolled unit and
stored at the Center.

C.  **Data Summary and Statistical Analyses**

As noted, all study data were transmitted into and maintained in
FormFlow. Statistical analyses of these data were performed using a SAS
Institute program (Versions 6.12 and 8.0), which also generated reports
and tables. Finally, aside from SAS reports, the Crystal Reports
software package was used to generate other reports by directly
downloading dBase data from FormFlow.

# ENROLLMENT RESULTS BY PHASE

# A total of 177 units underwent pre-intervention inspections and 121 units completed immediate post-intervention inspections prior to the cut-off date of October 1, 1999 for completing lead hazard reduction measures in enrolled units. These 121 units were followed for the 12 and 24 month post-intervention inspections, with a total of 73 having complete one-year post-intervention data collected and a total of 24 having complete two-years post-intervention data. The decrease in units between immediate- and one-year post-intervention was primarily due to the fact that tenants did not move into units until after Phase II, meaning that tenants were likely unaware of the study until LAAP inspectors visited the occupied unit at one-year post-intervention. Tenants' lack of familiarity with the project often meant that they were reluctant to allow access for one-year and two-years post-intervention sampling. Other problems included the growing number of conflicting duties for the LAAP inspectors over the lengthy period of this study and a temporary halt in the data collection while immediate post-intervention results underwent review.

Because so few units had complete two-years post-intervention data, the
major part of this report necessarily focuses on the results of the
first three phases to meet the study objectives. A brief description of
the two-years post-intervention results for the 24 units that had 24
month post-intervention inspections is presented in Section X.

# PRE-INTERVENTION RESULTS

D.  Results of Visual Assessments of Baseline Characteristics and
    Conditions

A total of 177 units (91 LHR and 86 LHR+W) underwent complete
pre-intervention visual assessments using Forms 01, 02 and 03. However,
pre-intervention dust testing was often delayed until the property
owner's project specifications and grant application had been approved
and a final pre-construction "walk-through" was completed. Because some
applications were not approved, this delay resulted in pre-intervention
composite dust samples being obtained from 148 of the 177 units (74 LHR
and 74 LHR+W) and single surface dust samples from 98 units (25 LHR and
73 LHR+W). The number of LHR units having single surface samples
collected was much less than that of the LHR+W units because, as
discussed in Section II.E, single surface samples were originally to be
collected only from LHR+W units. Single surface samples were collected
from LHR units for only a short period of time when laboratory analysis
of composite samples was being investigated by the Center and LAAP (see
Appendix B).

In order to more fully characterize initial building and dwelling unit
conditions, this section summarizes physical characteristics and
baseline condition data for the 177 units for which such data were
collected. Appendix C contains a detailed presentation of physical
characteristics for each enrolled unit. Appendix D presents a complete
list of baseline exterior conditions for each building and of baseline
interior conditions for each unit. Complete pre-intervention dust lead
loading results for composite and single surface samples are provided in
Appendices E and F, respectively.

1.  ***Baseline Physical Characteristics***

A Chi-square test was used to determine if there was a relationship
between pre-intervention housing characteristics and conditions (i.e.,
variables) and assigned treatment groups (i.e., LHR versus LHR+W units).
Such associations may indicate differences in the baseline
characteristics and conditions of LHR versus LHR+W units; these
differences had to be taken into account before the effectiveness of the
lead hazard reduction treatments could be fully evaluated. Variables
having a significant association with treatment group are summarized
below.

**[Building Type]{.underline}.** The majority (71 percent) of the
residential buildings initially enrolled in the study were single-family
rowhouses, which are common in Baltimore City. Building type was not
significantly associated with the assigned treatment group. Other
enrolled building types and their relative percentages as part of total
enrollment are displayed in Figure 1.

![](media/image1.wmf)**Figure 1: Type of Building -- Pre-Intervention
Assessment**

Source: Form 01

Note: Based on Chi-square testing, building type not significantly
associated with assigned treatment group.

**[Building Construction Period]{.underline}.** Many of the residential
buildings in Baltimore City, including 84 percent of those initially
enrolled in the study, were constructed 70 or more years ago. The
largest percentage of enrolled buildings (45 percent) was those built
between 1920 and 1929. Construction period was not significantly
associated with the assigned treatment group. The age/period of
construction for all enrolled buildings is displayed in Figure 2.

**Figure 2: Year Building Constructed -- Pre-Intervention Assessment**

![](media/image2.wmf)

Note: Based on Chi-square testing, construction period not significantly
associated with assigned treatment group.

**[Other Dwelling Unit Baseline Conditions]{.underline}.** In order to
identify important characteristics about initially enrolled dwelling
units, LAAP inspectors collected information about estimated real estate
market value, total number of rooms and bedrooms, number of windows,
including unpainted ones (e.g., vinyl and aluminum replacement windows),
and the size of the interior living space. A t-test was used to test for
significant differences in the mean values for LHR and LHR+W units.
Generally, the LHR and LHR+W units possessed similar characteristics,
the mean values for which are displayed in Table 3. However, the total
number of windows in a dwelling unit was marginally associated with the
assigned treatment group (p-value = 0.0641), with LHR+W units having
slightly more windows. The number of unpainted windows was also
significantly associated with the treatment group assignment
(p-value=0.0088), the mean being higher for LHR units.

**Table 3: Dwelling Unit Characteristics -- Pre-Intervention
Assessment**

+-----------------------------------+----------------+----------------+
| **Dwelling Unit Characteristic**  | **Mean (std.   | **Mean (std.   |
|                                   | deviat.) for   | deviat.) for   |
| **(91 LHR units, 86 LHR+W         | LHR**          | LHR+W**        |
| units)**                          |                |                |
|                                   | **Units**      | **Units**      |
+-----------------------------------+----------------+----------------+
| Estimated market value of         | \$22,500       | \$23,000       |
| dwelling unit^a^                  | (\$10,900)     | (\$12,000)     |
|                                   |                |                |
| (mean rounded to nearest \$100)   |                |                |
+-----------------------------------+----------------+----------------+
| \# of rooms in dwelling unit^a^   | 6 (2)          | 7 (2)          |
+-----------------------------------+----------------+----------------+
| \# of bedrooms in dwelling        | 3 (1)          | 3 (1)          |
| unit^a^                           |                |                |
+-----------------------------------+----------------+----------------+
| \# of windows in dwelling unit^b^ | 9 (3)          | 10 (4)         |
+-----------------------------------+----------------+----------------+
| \# of unpainted windows in        | 1.5 (3)        | 0.5 (2)        |
| dwelling unit^c^ (vinyl,          |                |                |
| aluminum)                         |                |                |
+-----------------------------------+----------------+----------------+
| Approximate square feet of living | 1,100 ft^2^    | 1,100 ft^2^    |
| space^a^                          | (340)          | (380)          |
+-----------------------------------+----------------+----------------+

Source: Form 01

^a^These building condition items not associated with assigned treatment
group based on t-test.

^b^Total number of windows in unit marginally associated with assigned
treatment group based on t-test (p=0.0641).

^c^Number of unpainted windows significantly associated with assigned
treatment group based on t-test (p=0.0088)

2.  ***Baseline Exterior Building and Interior Unit Condition***

**[Baseline Exterior Building Deterioration]{.underline}.** In order to
assess the level of pre-existing building deterioration, LAAP inspectors
performed an exterior visual assessment of enrolled buildings, checking
for seven (7) items considered to serve as obvious signs of
deterioration (see Table 4 on page 28). In general, there were minimal
observed differences between the LHR and LHR+W units with respect to
most of these exterior deterioration variables. For example, 26 percent
of the LHR units had roofs, gutters and downspouts that were either
missing, broken, cracked or had holes and 21 percent of the LHR+W units
had similar deterioration. LHR+W units did, however, differ from LHR
units for one particular item of exterior deterioration: 30 percent of
the LHR+W units versus 13 percent of the LHR units had two or more
windows or doors that were broken, boarded-up or missing. This condition
was highly associated with the assigned treatment group (p-value =
0.006). Given that the LHR+W units were slated to receive new windows as
part of the study, this could explain the difference between the two
treatment groups. Units not randomly assigned to treatment groups could
affect costs.

**Table 4: Units with Exterior Building Deterioration --
Pre-Intervention Assessment**

+-----------------------------------+----------+----------+-----------+
| **Types of Exterior Building      | **LHR**  | *        | **All     |
| Deterioration**                   |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(91 LHR units, 86 LHR+W         | Units**  | **\#     | **\#      |
| units)**                          |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| Roofs, gutters, downspouts --     | 24 (26%) | 18 (21%) | 42 (24%)  |
| missing, broken, holes, cracks    |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Chimney -- cracked, bricks loose  | 2 (2%)   | 2 (2%)   | 4 (2%)    |
| or missing, unstable, out of      |          |          |           |
| plumb                             |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Walls and siding -- large cracks  | 16 (18%) | 14 (16%) | 30 (17%)  |
| or holes, boards or shingles      |          |          |           |
| broken or missing                 |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Windows and doors -- ≥ two        | 12 (13%) | 26 (30%) | 38 (21%)  |
| windows or doors broken, missing, |          |          |           |
| boarded up^a^                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Porch or steps -- major elements  | 12 (13%) | 11 (13%) | 23 (13%)  |
| broken, missing, out of plumb     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Foundation -- major visible       | 2 (2%)   | 2 (2%)   | 4 (2%)    |
| cracks, missing materials,        |          |          |           |
| unsound                           |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Evidence of exterior ground       | 33 (36%) | 30 (35%) | 63 (36%)  |
| contaminated with paint chips     |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^Broken/missing windows & doors significantly associated with assigned
treatment group based on Chi-square test (p=0.006). No other exterior
building deterioration item was associated with treatment group.

The number of observed items of exterior building deterioration in LHR
units was not appreciably different from the number observed in LHR+W
units (see Table 5). There was no significant association between the
number of exterior deteriorations and the assigned treatment group
(p-value=0.95).

**Table 5: Number of Exterior Building Deterioration Items --
Pre-Intervention Assessment**

+-----------------------------------+----------+---------+------------+
| **\# Items of Exterior            | **LHR**  | **      | **All      |
| Deterioration per Building**      |          | LHR+W** | Units**    |
|                                   | **\#     |         |            |
| **(91 LHR units, 86 LHR+W         | Units**  | **\#    | **\#       |
| units)**                          |          | Units** | Units**    |
|                                   | **(%     |         |            |
|                                   | Units)** | **(%    | **(%       |
|                                   |          | U       | Units)**   |
|                                   |          | nits)** |            |
+-----------------------------------+----------+---------+------------+
| "0" items of exterior             | 36 (40)  | 29 (34) | 65 (37)    |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "1" item of exterior              | 28 (31)  | 30 (35) | 58 (33)    |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "2" items of exterior             | 14 (15)  | 15 (17) | 29 (16)    |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "3" items of exterior             | 9 (10)   | 7 (8)   | 16 (9)     |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "4" items of exterior             | 3 (3)    | 4 (5)   | 7 (4)      |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "6" items of exterior             | 1 (1)    | 1 (1)   | 2 (1)      |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+

Source: Form 02

**[Baseline Interior Dwelling Unit Deterioration]{.underline}.** LAAP
inspectors also visually assessed the level of pre-existing interior
dwelling unit deterioration by checking against five (5) evaluation
items. Here, LHR+W units had higher percentages of deterioration than
the LHR units for four (4) of the five (5) items (see Table 6). Most
notably, LHR+W units were more likely than LHR units to have walls,
ceilings, doors and trim that were in need of repair, replacement or
repainting, and floors that were loose, cracked, had missing boards or a
worn finish, or had deteriorated carpeting. Condition of the floors was
significantly associated with the assigned treatment group (p-value =
0.010), while condition of the walls, ceiling, doors and trim was
marginally associated with assigned treatment group (p-value = 0.088). A
slightly higher percentage of LHR+W units had interior deterioration
caused at least in part by disrepair of heating/cooling or plumbing
systems, while slightly more LHR units had interior deterioration caused
by roof leaks. However, neither disrepair of heating/cooling or plumbing
systems nor roof leaks were significantly associated with assigned
treatment group. Both LHR and LHR+W units had a very high percentage of
units (83.5 percent LHR and 88.4 percent LHR+W) with at least one room
having more than 2 ft^2^ of paint deterioration on walls, woodwork,
doors, windows and other painted surfaces. The mean number of rooms with
such paint deterioration was 2.3 rooms in LHR units and 2.6 rooms in
LHR+W units.

**Table 6: Units with Interior Dwelling Unit Deterioration --
Pre-Intervention Assessment**

+-----------------------------------+----------+----------+-----------+
| **Type of Interior Dwelling Unit  | **LHR**  | *        | **All     |
| Deterioration**                   |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(91 LHR units, 86 LHR+W         | Units**  | **\#     | **\#      |
| units)**                          |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| Walls, ceiling, doors and trim -- | 36 (40%) | 45 (52%) | 81 (46%)  |
| cracks, need for repair, replace  |          |          |           |
| or major repainting^a^            |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Floors -- loose, missing or       | 45 (49%) | 59 (69%) | 104 (59%) |
| cracked, finish worn,             |          |          |           |
| deteriorated carpeting^b^         |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Heating/cooling and plumbing --   | 8 (9%)   | 11 (13%) | 19 (11%)  |
| need for extensive repair^c^      |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Interior damage due to roof leak  | 17 (19%) | 14 (16%) | 31 (18%)  |
| -- need for extensive repair^c^   |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Rooms with \>2 ft^2^ of paint     | 76 (84%) | 76 (88%) | 152 (86%) |
| deterioration on walls, woodwork, |          |          |           |
| doors, windows, etc.^c^           |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^Condition of walls, ceilings, doors, & trim marginally associated
with assigned treatment group based on Chi-square test (p=0.088).

^b^Floor condition significantly associated with assigned treatment
group based on Chi-square test (p=0.010).

^c^These interior deterioration items not associated with assigned
treatment group based on Chi-square test.

The total number of observed items of interior deterioration was
significantly associated with the assigned treatment group (p-value =
0.0212). The number of LHR units with at least one observed interior
dwelling unit deterioration item (approximately 76 percent) was lower
than that of LHR+W units (approximately 84 percent) (see Table 7 on page
30). Interestingly, more LHR units (45 percent) than LHR+W units (35
percent) had one item of interior deterioration, but the LHR+W units
were more likely to have two (2) or more items of deterioration.

**Table 7: Number of Interior Dwelling Unit Deterioration Items --
Pre-Intervention Assessment**

+-----------------------------------+----------+----------+-----------+
| **Number of Items of Interior     | **LHR**  | *        | **All     |
| Deterioration per dwelling unit** |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(91 LHR units, 86 LHR+W         | Units**  | **\#     | **\#      |
| units)^a^**                       |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| "0" items of interior             | 22 (24%) | 14 (16%) | 36 (20%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "1" item of interior              | 41 (45%) | 30 (35%) | 71 (40%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "2" items of interior             | 20 (22%) | 29 (34%) | 49 (28%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "3" items of interior             | 7 (8%)   | 11 (13%) | 18 (10%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "4" items of interior             | 1 (1%)   | 2 (2%)   | 3 (2%)    |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^Total number of items of interior deterioration significantly
associated with assigned treatment group based on Chi-square test
(p=0.0212).

E.  **Results of Pre-Intervention Composite and Single Surface Dust
    Sampling**

As noted above, for most of the enrolled units, LAAP inspectors did not
take dust samples when pre-intervention visual assessments were
performed because a number of initially assessed units ultimately were
de-enrolled by the property owners and/or by LAAP before lead hazard
reduction specifications and grant applications were submitted and
approved. Therefore, some units were de-enrolled prior to the collection
of dust samples but after pre-intervention characterizations were done.
To ensure that dust samples were collected no more than four (4) weeks
prior to the intervention, LAAP inspectors typically obtained composite
and single surface samples during a pre-construction walk-through of the
unit with the property owner and, if applicable, the contractor
performing the lead hazard reduction work. For this reason, there are
fewer units having pre-intervention dust sample results (148 units) than
those with visual assessment results (177 units).

1.  ***Pre-Intervention Composite Results***

Composite dust samples were taken from bare floors, interior window
sills, window troughs and, when necessary, carpeted floors in all
enrolled LHR and LHR+W units. Because very few units had carpeted
floors, sample results for carpeted floors were excluded from this
study. A Wilcoxon rank sum test was used to test the equality of the
median dust lead loadings for the assigned treatment group (i.e., LHR
versus LHR+W units). Differences in median pre-intervention dust lead
loadings between the two groups had to be accounted for before the
effectiveness of the lead hazard control treatments could be fully
evaluated.

For the three (3) surface types, the median pre-intervention dust lead
loadings in the LHR+W units exceeded median loadings for the LHR units
(see Table 8 on page 31 and Figure 3 on page 32). These differences were
significant for bare floors (p-value=0.0374), marginally significant for
window troughs (p-value=0.1077), but not significant for interior window
sills (p-value=0.2803). The 5^th^, 25^th^, 75^th^, and 95^th^ percentile
dust lead loadings in the LHR+W units were all higher than those in the
LHR units, in some cases dramatically so.

**Table 8: Pre-Intervention *Composite* Sample Dust Lead Loading**

+--------------------+----------------------+--------------------------+
| **Surface Type**   | **[LHR Dust Lead     | **[LHR+W Dust Lead       |
|                    | Loading              | Loading                  |
|                    | (μg/f                | (                        |
|                    | t^2^)]{.underline}** | μg/ft^2^)]{.underline}** |
|                    |                      |                          |
|                    | *5^th^ Percentile*   | *5^th^ Percentile*       |
|                    |                      |                          |
|                    | 25^th^ Percentile    | 25^th^ Percentile        |
|                    |                      |                          |
|                    | **Median**           | **Median**               |
|                    |                      |                          |
|                    | *75^th^ Percentile*  | *75^th^ Percentile*      |
|                    |                      |                          |
|                    | 95^th^ Percentile    | 95^th^ Percentile        |
|                    |                      |                          |
|                    | **Geometric Mean**   | **Geometric Mean**       |
|                    |                      |                          |
|                    | *95% Confid. Limits* | *95% Confid. Limits*     |
+--------------------+----------------------+--------------------------+
| Bare floors^a,b^   | *22*                 | *39*                     |
|                    |                      |                          |
| (73 LHR units,     | 77                   | 141                      |
|                    |                      |                          |
| 71 LHR+W units)    | **273**              | **333**                  |
|                    |                      |                          |
|                    | *634*                | *1,635*                  |
|                    |                      |                          |
|                    | 5,199                | 23,960                   |
|                    |                      |                          |
|                    | **258**              | **500**                  |
|                    |                      |                          |
|                    | *173; 385*           | *325; 768*               |
+--------------------+----------------------+--------------------------+
| Interior window    | *31*                 | *286*                    |
| sills^a,b^         |                      |                          |
|                    | 631                  | 954                      |
| (74 LHR units,     |                      |                          |
|                    | **1,986**            | **2,780**                |
| 74 LHR+W units)    |                      |                          |
|                    | *8,362*              | *9,545*                  |
|                    |                      |                          |
|                    | 42,619               | 101,200                  |
|                    |                      |                          |
|                    | **1,854**            | **3,153**                |
|                    |                      |                          |
|                    | *1,148; 2,995*       | *2,098; 4 737*           |
+--------------------+----------------------+--------------------------+
| Window             | *67*                 | *740*                    |
| troughs^a,b^       |                      |                          |
|                    | 2,050                | 3,287                    |
| (74 LHR units,     |                      |                          |
|                    | **9,427**            | **10,998**               |
| 74 LHR+W units)    |                      |                          |
|                    | *38,308*             | *90,480*                 |
|                    |                      |                          |
|                    | 260,182              | 447,429                  |
|                    |                      |                          |
|                    | **7,680**            | **16,659**               |
|                    |                      |                          |
|                    | *4,568; 12,911*      | *10,142; 27,365*         |
+--------------------+----------------------+--------------------------+

Source: Form 04A

^a^Approximately 95% of bare floor composites, interior window sill
composites, and window trough composites were comprised of 4
sub-samples; the rest were comprised of either 2 or 3 sub-samples.

^b^ Based on Wilcoxon rank sum tests, pre-intervention dust lead
loadings significantly associated with assigned treatment group for
floors (p=0.0374), marginally associated for troughs (p=0.1077), & not
associated for sills (p=0.2803).

**Figure 3: Pre-Intervention *Composite* Sample Dust Lead Loading Box
Plot**

![](media/image4.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

2.  ***Pre-Intervention Single Surface Results***

As noted in Section II.E, although single surface dust wipe samples were
to be collected only in LHR+W units, both composite [and]{.underline}
single surface samples were collected in certain LHR units from November
1997 until February 1, 1998 due to laboratory analysis concerns. (All
such LHR units dust sampled during that period had the two sample types
collected through Phase II.)

Similar to composites, single surface samples were taken from bare
floors, interior window sills, window troughs in designated rooms.
(There were too few carpeted floor samples to allow full
characterization of this surface type.) There were more LHR+W units (73)
with single surface samples than LHR units (25), but the median dust
lead loading values in the LHR+W units again exceeded those of the LHR
units by a factor of two to three (see Table 9 on page 33 and Figure 4
on page 34). Based on Chi-square testing, these differences were not
significant for bare floors (p-value=0.1176) or window troughs
(p-value=0.2818), but were highly significant for interior window sills
(p-value=0.0036). The 5^th^, 25^th^, 75^th^, and 95^th^ percentile dust
lead loadings were also much higher in the LHR+W units.

The pre-intervention single surface dust sample results for both LHR and
LHR+W units were also compared to pre-intervention single surface dust
data obtained from Baltimore City housing units enrolled in Round I of
the National Evaluation of HUD\'s OHHLHC's Lead Hazard Control Grant
program. These units underwent lead hazard reduction interventions that
were similar to those of the LHR+W units, and more intensive than those
of LHR units. No consistent differences in pre-intervention dust lead
levels were found to exist between the LHR and LHR+W treatment groups
and the Baltimore Round One units, suggesting that the Round One units
could be used to contrast the effectiveness of higher level lead hazard
reduction treatments versus the somewhat lower level EA 6-8 prescribed
treatments. Pre-intervention bare floor dust lead levels for LHR and
LHR+W units were not significantly different than for the Round One
units. But pre-intervention interior window sill lead levels were lower
for LHR units than the Round One units, while LHR+W units had levels
similar to the Round One units. For window troughs, the opposite was
observed. Here, the LHR+W units had significantly higher
pre-intervention dust lead levels than the Round One units.

**Table 9: Pre-Intervention *Single Surface* Sample Dust Lead Loading**

+---------------+----------------+-----------------+------------------+
| **Surface     | **[LHR Dust    | **[LHR+W Dust   | **[Baltimore HUD |
| Type**        | Lead Loading   | Lead Loading    | Units^a^         |
|               | (μg/ft^2^]{    | (μg/ft^2^]      | (µg/ft^2^        |
|               | .underline})** | {.underline})** | )]{.underline}** |
|               |                |                 |                  |
|               | *5^th^         | *5^th^          | *5^th^           |
|               | Percentile*    | Percentile*     | Percentile*      |
|               |                |                 |                  |
|               | 25^th^         | 25^th^          | 25^th^           |
|               | Percentile     | Percentile      | Percentile       |
|               |                |                 |                  |
|               | **Median**     | **Median**      | **Median**       |
|               |                |                 |                  |
|               | *75^th^        | *75^th^         | *75^th^          |
|               | Percentile*    | Percentile*     | Percentile*      |
|               |                |                 |                  |
|               | 95^th^         | 95^th^          | 95^th^           |
|               | Percentile     | Percentile      | Percentile       |
|               |                |                 |                  |
|               | **Geometric    | **Geometric     | **Geometric      |
|               | Mean**         | Mean**          | Mean**           |
|               |                |                 |                  |
|               | *95% Confid.   | *95% Confid.    | *95% Confid.     |
|               | Limits*        | Limits*         | Limits*          |
+---------------+----------------+-----------------+------------------+
| Bare          | *29*           | *58*            | *37*             |
| floors^b^     |                |                 |                  |
|               | 83             | 154             | 130              |
| (25 LHR       |                |                 |                  |
| units,        | **192**        | **338**         | **314**          |
|               |                |                 |                  |
| 73 LHR+W      | *881*          | *986*           | *681*            |
| units)        |                |                 |                  |
|               | 7,225          | 29,258          | 1,955            |
|               |                |                 |                  |
|               | **293**        | **511**         | **292**          |
|               |                |                 |                  |
|               | *140; 611*     | *335; 779*      | *254; 337*       |
+---------------+----------------+-----------------+------------------+
| Interior      | *41*           | *146*           | *223*            |
| window        |                |                 |                  |
| sills^b^      | 186            | 850             | 832              |
|               |                |                 |                  |
| (25 LHR       | **844**        | **2,350**       | **2,510**        |
| units,        |                |                 |                  |
|               | *1,580*        | *7,303*         | *7,228*          |
| 73 LHR+W      |                |                 |                  |
| units)        | 45,179         | 229,108         | 27,470           |
|               |                |                 |                  |
|               | **705**        | **2,830**       | **2,509**        |
|               |                |                 |                  |
|               | *283; 1,755*   | *1,790; 4,475*  | *2,133; 2,950*   |
+---------------+----------------+-----------------+------------------+
| Window        | *329*          | *359*           | *136*            |
| troughs^b^    |                |                 |                  |
|               | 2,253          | 1,949           | 1,070            |
| (25 LHR       |                |                 |                  |
| units,        | **6,135**      | **12,227**      | **3,630**        |
|               |                |                 |                  |
| 72 LHR+W      | *39,954*       | *92,595*        | *13,000*         |
| units)        |                |                 |                  |
|               | 98,100         | 547,652         | 50,000           |
|               |                |                 |                  |
|               | **7,795**      | **13,462**      | **3,451**        |
|               |                |                 |                  |
|               | *3,372;        | *7,910; 22,911* | *2,807; 4,243*   |
|               | 18,020*        |                 |                  |
+---------------+----------------+-----------------+------------------+

Source: Form 04B

^a^Baltimore HUD unit data are from Baltimore Round One housing units
enrolled in the National Evaluation of HUD's Lead Hazard Control Grant
Program. For floors, Baltimore HUD unit data include both interior floor
and entry floor data.

^b^Based on Wilcoxon rank sum tests, pre-intervention single surface
dust lead loadings not associated with assigned treatment group for bare
floors (p=0.1176) or troughs (p=0.2818), but significantly associated
for sills (p=0.0036).

![](media/image5.wmf)**Figure 4: Pre-Intervention *Single Surface*
Sample Dust Lead Loading Box Plot**

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

3.  ***Comparison of Pre-Intervention Single Surface Results with
    Clearance Standards/Guidance***

Comparison of pre-intervention single surface dust sample results for
interior window sills with the Maryland statutory abatement clearance
standard and the joint HUD/EPA guidance clearance standard of 500
μg/ft^2^ yields useful information in terms of statistical association
with higher dust lead loading. Assigned treatment group was found to be
significantly associated with pre-intervention interior window sill dust
lead loading being above or below a standard of 500 μg/ft^2^ (p-value =
0.009). (Note: Similar analyses were performed using clearance standards
for floors and window troughs, but no statistically significant
associations were observed for the assigned treatment group.) In
summary, the results of pre-intervention exterior and interior visual
assessment and composite and single surface dust sampling all indicate
that LHR+W units initially enrolled in the study were in poorer
condition than enrolled LHR units, suggesting that assignment of units
by property owners into these two categories was not random. Paint lead
content was not measured during this study. However, given historical
residential lead paint usage patterns in Baltimore City for housing
units of similar age to those enrolled in the study, it is unlikely that
the lead content of paint in the LHR units was substantially different
from that in the LHR+W units.

I.  **IMMEDIATE POST-INTERVENTION RESULTS**

Of the 148 units that had pre-intervention dust results available, a
total of 121 units (57 LHR and 64 LHR+W) completed lead hazard reduction
treatment interventions and a full immediate post-intervention
assessment, including a visual assessment, collection of cost and
concurrent work information and post-intervention dust testing. Samples
potentially associated with Lab A's unacceptable composite spike sample
results were excluded from all analyses (see Appendix B). The
relationship between these post-intervention factors and the assigned
treatment group (i.e., LHR versus LHR+W units) was examined using a
Chi-square test. A Wilcoxon rank sum test was used to test the equality
of the post-intervention median dust lead loadings for the assigned
treatment group.

A.  **Results of Immediate Post-Intervention Composite and Single
    Surface Dust Sampling**

    1.  ***Immediate Post-Intervention Composite Results***

Immediate post-intervention composite dust samples were taken from the
same surface types and locations as those sampled at pre-intervention
(see Table 10 on page 36 and Figure 5 on page 37). For bare floors,
immediate composite post-intervention median dust lead loadings for LHR
and LHR+W units were not significantly different (p-value=0.6422).
However, as might be expected, immediate post-intervention median dust
lead loadings for sills and troughs were highly associated with assigned
treatment group (p-values=0.0014 and 0.0001, respectively). The LHR+W
units had much lower median dust lead loadings for interior window sills
and window troughs than those in LHR units.

**Table 10: Immediate Post-Intervention *Composite* Sample Dust Lead
Loading**

+----------------+--------------------------+--------------------------+
| **Surface      | **[LHR Composite Dust    | **[LHR+W Composite       |
| Type**         | Lead Loading             | Dust]{.underline}**      |
|                | (                        |                          |
|                | μg/ft^2^)]{.underline}** | **[Lead Loading          |
|                |                          | (                        |
|                | *5^th^ Percentile*       | μg/ft^2^)]{.underline}** |
|                |                          |                          |
|                | 25^th^ Percentile        | *5^th^ Percentile*       |
|                |                          |                          |
|                | **Median**               | 25^th^ Percentile        |
|                |                          |                          |
|                | *75^th^ Percentile*      | **Median**               |
|                |                          |                          |
|                | 95^th^ Percentile        | *75^th^ Percentile*      |
|                |                          |                          |
|                | **Geometric Mean**       | 95^th^ Percentile        |
|                |                          |                          |
|                | *95% Confid. Limits*     | **Geometric Mean**       |
|                |                          |                          |
|                |                          | *95% Confid. Limits*     |
+----------------+--------------------------+--------------------------+
| Bare           | *4*                      | *4*                      |
| floors^a,b^    |                          |                          |
|                | 15                       | 11                       |
| (51 LHR units, |                          |                          |
|                | **27**                   | **29**                   |
| 57 LHR+W       |                          |                          |
| units)         | *71*                     | *58*                     |
|                |                          |                          |
|                | 195                      | 727                      |
|                |                          |                          |
|                | **30**                   | **31**                   |
|                |                          |                          |
|                | *22; 42*                 | *21; 46*                 |
+----------------+--------------------------+--------------------------+
| Interior       | *12*                     | *5*                      |
| window         |                          |                          |
| sills^a,b^     | 27                       | 14                       |
|                |                          |                          |
| (54 LHR units, | **83**                   | **36**                   |
|                |                          |                          |
| 62 LHR+W       | *265*                    | *103*                    |
| units)         |                          |                          |
|                | 1,038                    | 508                      |
|                |                          |                          |
|                | **92**                   | **36**                   |
|                |                          |                          |
|                | *62; 135*                | *25; 53*                 |
+----------------+--------------------------+--------------------------+
| Window         | *12*                     | *14*                     |
| troughs^a,b^   |                          |                          |
|                | 174                      | 30                       |
| (54 LHR units, |                          |                          |
|                | **344**                  | **100**                  |
| 62 LHR+W       |                          |                          |
| units)         | *1,100*                  | *312*                    |
|                |                          |                          |
|                | 15,516                   | 1,282                    |
|                |                          |                          |
|                | **416**                  | **106**                  |
|                |                          |                          |
|                | *251; 690*               | *72; 156*                |
+----------------+--------------------------+--------------------------+

Source: Form 04A

^a^Approximately 95% of bare floor composites, interior window sill
composites, and window trough composites were comprised of 4
sub-samples; the rest were comprised of either 2 or 3 sub-samples.

^b^Based on Wilcoxon rank sum tests, post-intervention composite dust
lead loadings were not significantly associated with assigned treatment
group for bare floors (p=0.6422), but highly associated for sills and
troughs (p=0.0014 and 0.0001, respectively).

**Figure 5: Immediate Post-Intervention *Composite* Sample Dust Lead
Loading Box Plot**

![](media/image6.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

2.  ***Reduction in Composite Results from Pre- to Immediate
    Post-Intervention***

Large median percent decreases and median μg/ft^2^ decreases were
observed when measuring the change from pre to post-intervention dust
lead loading results for composite samples taken from bare floors,
interior window sills and window troughs, with the most dramatic
decreases being observed for sills and troughs (see Tables 11 and 12 on
page 38, and Figure 6 on page 39). The association between the percent
reduction in composite dust lead loadings and the assigned treatment
group was highly significant for interior window sills (p-value=0.0001)
and troughs (p-value=0.0001) but was not significant for bare floors
(p-value=0.2459).

**Table 11: Percent Reduction in Pre- to Immediate Post-Intervention
*Composite* Dust Lead Loadings**

+-------------------------------+------------------+-------------------+
| **Surface Type and            | **LHR Units**    | **LHR+W Units**   |
| Statistic-Composite Dust      |                  |                   |
| Samples**                     | **Pre- to        | **Pre- to Post-** |
|                               | P                |                   |
|                               | ost-Intervention | **Intervention    |
|                               | Percent          | Percent           |
|                               | Reduction**      | Reduction**       |
+-------------------------------+------------------+-------------------+
| [Bare floors (49 LHR, 56      | *70*             | *74*              |
| LHR+W)^a^]{.underline}:       |                  |                   |
|                               | **85**           | **89**            |
| *25^th^ Percentile Percent    |                  |                   |
| Decrease*                     | 93               | 97                |
|                               |                  |                   |
| **Median Percent Decrease**   |                  |                   |
|                               |                  |                   |
| 75^th^ Percentile Percent     |                  |                   |
| Decrease                      |                  |                   |
+-------------------------------+------------------+-------------------+
| [Interior window sills (52    | *78*             | *96*              |
| LHR, 62 LHR+W^a^]{.underline} |                  |                   |
|                               | **94**           | **99**            |
| *25^th^ Percentile Percent    |                  |                   |
| Decrease*                     | 98               | \>99              |
|                               |                  |                   |
| **Median Percent Decrease**   |                  |                   |
|                               |                  |                   |
| 75^th^ Percentile Percent     |                  |                   |
| Decrease                      |                  |                   |
+-------------------------------+------------------+-------------------+
| [Window troughs (52 LHR, 62   | *74*             | *97*              |
| LHR+W)^a^]{.underline}        |                  |                   |
|                               | **95**           | **\>99**          |
| *25^th^ Percentile Percent    |                  |                   |
| Decrease*                     | 98               | \>99              |
|                               |                  |                   |
| **Median Percent Decrease**   |                  |                   |
|                               |                  |                   |
| 75^th^ Percentile Percent     |                  |                   |
| Decrease                      |                  |                   |
+-------------------------------+------------------+-------------------+

Source: Form 04A

^a^Based on Wilcoxon rank sum tests, percent reduction in composite dust
lead loadings was significantly associated with assigned treatment group
for sills (p=0.0001) and troughs (p=0.0001) but not for bare floors
(p=0.2459).

**Table 12: Micrograms Per Square Foot Reduction in Pre- to Immediate
Post-Intervention *Composite* Dust Lead Loadings**

+----------------------------------+-----------------+-----------------+
| **Surface Type and               | **LHR Units**   | **LHR+W Units** |
| Statistic-Composite Dust         |                 |                 |
| Samples**                        | **Pre to        | **Pre to        |
|                                  | Po              | Po              |
|                                  | st-Intervention | st-Intervention |
|                                  | µg/ft^2^        | µg/ft^2^        |
|                                  | Reduction**     | Reduction**     |
+----------------------------------+-----------------+-----------------+
| [Bare floors (49 LHR, 56         | *40*            | *71*            |
| LHR+W)]{.underline}:             |                 |                 |
|                                  | **147**         | **225**         |
| *25^th^ Percentile μg/ft^2^      |                 |                 |
| Decrease*                        | 506             | 807             |
|                                  |                 |                 |
| **Median μg/ft^2^ Decrease**     |                 |                 |
|                                  |                 |                 |
| 75^th^ Percentile μg/ft^2^       |                 |                 |
| Decrease                         |                 |                 |
+----------------------------------+-----------------+-----------------+
| [Interior window sills (52 LHR,  | *415*           | *716*           |
| 62 LHR+W]{.underline}:           |                 |                 |
|                                  | **1,686**       | **2,596**       |
| *25^th^ Percentile μg/ft^2^      |                 |                 |
| Decrease*                        | 8,272           | 7,433           |
|                                  |                 |                 |
| **Median μg/ft^2^ Decrease**     |                 |                 |
|                                  |                 |                 |
| 75^th^ Percentile μg/ft^2^       |                 |                 |
| Decrease                         |                 |                 |
+----------------------------------+-----------------+-----------------+
| [Window troughs (52 LHR, 62      | *1,230*         | *4,254*         |
| LHR+W)]{.underline}:             |                 |                 |
|                                  | **9,708**       | **11,284**      |
| *25^th^ Percentile μg/ft^2^      |                 |                 |
| Decrease*                        | 25,175          | 90,424          |
|                                  |                 |                 |
| **Median μg/ft^2^ Decrease**     |                 |                 |
|                                  |                 |                 |
| 75^th^ Percentile μg/ft^2^       |                 |                 |
| Decrease                         |                 |                 |
+----------------------------------+-----------------+-----------------+

Source: Form 04A

**Figure 6: Pre- and Immediate Post-Intervention *Composite* Sample Dust
Lead Loading for LHR and LHR+W Units (Logarithmic Scale)**

![](media/image7.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

3.  ***Units Having an Increase in Composite Dust Lead Loadings from
    Pre- to Immediate Post-Intervention***

Despite the significant median decreases in dust lead loadings between
pre- and immediate post-intervention, data in Table 13 on page 40 show
that some units experienced increases in dust lead loadings between
these two phases. The percentage of LHR+W units that underwent an
increase was generally lower than that of LHR units.

Table 13: Number and Percent of Units Having an Increase in *Composite*
Dust Lead Loadings from Pre- to Immediate Post-Intervention

+-----------------------+----------------------+-----------------------+
| **Surface Type and**  | # LHR                | **LHR+W**             |
|                       |                      |                       |
| **Sample Type**       |                      |                       |
+-----------------------+----------------------+-----------------------+
| [Bare                 | 6/49 (12%)           | 3/56 (5%)             |
| Floors]{.underline}:  |                      |                       |
+-----------------------+----------------------+-----------------------+
| [Interior window      | 4/52 (8%)            | 2/62 (3%)             |
| sills]{.underline}:   |                      |                       |
+-----------------------+----------------------+-----------------------+
| [Window               | 3/52 (6%)            | 1/62 (2%)             |
| Troughs]{.underline}: |                      |                       |
+-----------------------+----------------------+-----------------------+

4.  ***Immediate Post-Intervention Single Surface Results***

As previously noted, single surface dust samples taken in all 62 LHR+W
units and in 20 LHR units were also included in this sampling subset
(see Table 14 on page 41). With this in mind, although the median
immediate post-intervention single surface dust lead loading for bare
floors in LHR units was higher than that in LHR+W units, this difference
was not significant (p-value=0.2168). However, as might be expected,
single surface immediate post-intervention median dust lead loadings for
sills and troughs were highly associated with assigned treatment group
(p-values=0.0012 and 0.0035, respectively). The LHR+W units had much
lower median dust lead loadings for interior window sills and window
troughs than those in LHR units.

Immediate post-intervention single surface dust sample results for both
LHR and LHR+W units were compared with immediate post-intervention
single surface dust data obtained from Baltimore city housing units
enrolled in Round One of the National Evaluation of HUD OHHLHC's Lead
Hazard Control Grant Program. These units underwent interventions that
were similar to those of LHR+W units and generally more intensive than
those of LHR units. (see Table 14 on page 41 and Figure 7 on page 42).
Median dust lead loading results for bare floors, interior window sills
and window troughs were all much lower in the Baltimore Round One units
than in both the LHR [and]{.underline} LHR+W units. Each surface type
comparison was found to be highly significant (p-value=0.0001 for each).

**Table 14: Immediate Post-Intervention *Single Surface* Dust Lead
Loading Results**

+--------------+---------------+------------------+------------------+
| **Surface    | **[LHR Single | **[LHR+W Single  | **[Baltimore HUD |
| Type**       | Surface Dust  | Surface Dust     | Units Single     |
|              | Lead Loading  | Lead Loading     | Surface Dust     |
|              | (μg/ft^2^)]{  | (μg/ft^2^        | Lead Loading     |
|              | .underline}** | )]{.underline}** | (µg/ft^2^)^a     |
|              |               |                  | ^]{.underline}** |
|              | *5^th^        | *5^th^           |                  |
|              | Percentile*   | Percentile*      | *5^th^           |
|              |               |                  | Percentile*      |
|              | 25^th^        | 25^th^           |                  |
|              | Percentile    | Percentile       | 25^th^           |
|              |               |                  | Percentile       |
|              | **Median**    | **Median**       |                  |
|              |               |                  | **Median**       |
|              | *75^th^       | *75^th^          |                  |
|              | Percentile*   | Percentile*      | *75^th^          |
|              |               |                  | Percentile*      |
|              | 95^th^        | 95^th^           |                  |
|              | Percentile    | Percentile       | 95^th^           |
|              |               |                  | Percentile       |
|              | **Geometric   | **Geometric      |                  |
|              | Mean**        | Mean**           | **Geometric      |
|              |               |                  | Mean**           |
|              | *95% Confid.  | *95% Confid.     |                  |
|              | Limits*       | Limits*          | *95% Confid.     |
|              |               |                  | Limits*          |
+--------------+---------------+------------------+------------------+
| Bare         | *10*          | *6*              | *0.3*            |
| floors^b,c^  |               |                  |                  |
|              | 26            | 20               | 5                |
| (20 LHR      |               |                  |                  |
| units,       | **66**        | **39**           | **15**           |
|              |               |                  |                  |
| 63 LHR+W     | *112*         | *89*             | *35*             |
| units)       |               |                  |                  |
|              | 1217          | 307              | 96               |
|              |               |                  |                  |
|              | **60**        | **43**           | **14**           |
|              |               |                  |                  |
|              | *34; 109*     | *31; 59*         | *12; 16*         |
+--------------+---------------+------------------+------------------+
| Interior     | *14*          | *7*              | *0*              |
| window       |               |                  |                  |
| sills^b,c^   | 33            | 15               | 2                |
|              |               |                  |                  |
| (20 LHR      | **103**       | **29**           | **10**           |
| units,       |               |                  |                  |
|              | *178*         | *51*             | *31*             |
| 62 LHR+W     |               |                  |                  |
| units)       | 961           | 257              | 103              |
|              |               |                  |                  |
|              | **96**        | **32**           | **17**           |
|              |               |                  |                  |
|              | *51; 178*     | *24; 42*         | *15; 20*         |
+--------------+---------------+------------------+------------------+
| Window       | *29*          | *9*              | *0*              |
| troughs^b,c^ |               |                  |                  |
|              | 217           | 32               | 6                |
| (20 LHR      |               |                  |                  |
| units,       | **610**       | **115**          | **38**           |
|              |               |                  |                  |
| 62 LHR+W     | *1,139*       | *347*            | *125*            |
| units)       |               |                  |                  |
|              | 5,071         | 2,262            | 607              |
|              |               |                  |                  |
|              | **460**       | **128**          | **57**           |
|              |               |                  |                  |
|              | *230; 921*    | *79; 207*        | *47; 68*         |
+--------------+---------------+------------------+------------------+

Source: Form 04B

^a^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead Hazard Control Grant Program and were compiled using
initial Phase 2 data (immediate post-intervention). For floors,
Baltimore HUD unit data include both interior floor and entry floor
data.

^b^Based on Wilcoxon rank sum tests, median post-intervention single
surface dust lead loadings with significantly associated with assigned
treatment group for sills (p=0.0012) and troughs (p=0.0035), but not
associated for bare floors (0.2168).

^c^Based on Wilcoxon rank sum tests, median post-intervention single
surface dust lead loadings for Baltimore Round 1 units were
significantly lower than those for study units (p=0.0001 for each
surface type).

**Figure 7: Immediate Post-Intervention *Single Surface* Dust Lead
Loading Results Box Plot**

![](media/image8.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

5.  ***Reduction in Single Surface Results from Pre- to Immediate
    Post-Intervention***

Similar to the composite dust sample results, when single surface sample
pre- to immediate post-intervention dust lead loading results were
compared, substantial median percent decreases and median μg/ft^2^
decreases were observed for bare floors, interior window sills and
window troughs. These reductions were most dramatic for window sills and
troughs and were particularly large in the LHR+W units (see Tables 15
and 16 on pages 43 and 44, respectively, and Figure 8 on page 45). For
each of these surface types, the median percent decrease for LHR+W units
was greater than that for LHR units. The association between the median
percent reduction in single surface dust lead loadings and the assigned
treatment group was highly significant for interior window sills and
troughs (p-values=0.0001 and 0.0057, respectively) but was not
significant for bare floors (p-value=0.1655).

When reductions for LHR and LHR+W units were compared with reductions
for Baltimore Round One HUD Evaluation units, the Round One units had
statistically significant larger decreases for all three surface types,
as measured by median percentage [and]{.underline} actual μg/ft^2^, than
did both LHR and LHR+W units (p-value=0.0001 for all three surface
types).

**Table 15: Percent Reduction in Pre- to Immediate Post-Intervention
*Single Surface* Dust Lead Loadings**

+-------------------------------+----------+------------+------------+
| **Surface Type and            | **LHR    | **LHR+W    | *          |
| Statistic-Single Surface Dust | Units    | Units Pre  | *Baltimore |
| Samples**                     | Pre to   | to         | HUD        |
|                               | I        | Immediate  | Units^a^   |
|                               | mmediate | Post-In    | Pre to     |
|                               | P        | tervention | Immediate  |
|                               | ost-Inte | Percent    | Post-      |
|                               | rvention | R          | Inte       |
|                               | Percent  | eduction** | rvention** |
|                               | Red      |            |            |
|                               | uction** |            | **%        |
|                               |          |            | R          |
|                               |          |            | eduction** |
+-------------------------------+----------+------------+------------+
| [Bare floors (16 LHR, 63      | *24*     | *62*       | *86*       |
| LHR+W)^b^]{.underline}:       |          |            |            |
|                               | **70**   | **88**     | **95**     |
| *25^th^ Percentile Percent    |          |            |            |
| Decrease*                     | 97       | 98         | 98         |
|                               |          |            |            |
| **Median Percent Decrease**   |          |            |            |
|                               |          |            |            |
| 75^th^ Percentile Percent     |          |            |            |
| Decrease                      |          |            |            |
+-------------------------------+----------+------------+------------+
| [Interior window sills (16    | *55*     | *96*       | *98*       |
| LHR, 62                       |          |            |            |
| LHR+W)^b^]{.underline}:       | **84**   | **99**     | **\>99**   |
|                               |          |            |            |
| *25^th^ Percentile Percent    | 95       | \>99       | \>99       |
| Decrease*                     |          |            |            |
|                               |          |            |            |
| **Median Percent Decrease**   |          |            |            |
|                               |          |            |            |
| 75^th^ Percentile Percent     |          |            |            |
| Decrease                      |          |            |            |
+-------------------------------+----------+------------+------------+
| [Window troughs (16 LHR, 62   | *82*     | *96*       | *95*       |
| LHR+W)^b^]{.underline}:       |          |            |            |
|                               | **94**   | **99**     | **99**     |
| *25^th^ Percentile Percent    |          |            |            |
| Decrease*                     | 98       | \>99       | \>99       |
|                               |          |            |            |
| **Median Percent Decrease**   |          |            |            |
|                               |          |            |            |
| 75^th^ Percentile Percent     |          |            |            |
| Decrease                      |          |            |            |
+-------------------------------+----------+------------+------------+

Source: Form 04B

^a^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead Hazard Control Grant Program and were compiled using
initial Phase 2 data (immediate post-intervention) for units that were
vacant at pre-intervention and at immediate post-intervention. For
floors, Baltimore HUD unit data include both interior floor and entry
floor data.

^b^Based on Wilcoxon rank sum tests, the association between the median
percent reduction in single surface dust lead loadings and assigned
treatment group was significant for sills (p=0.0001) and troughs
(p=0.0057), but not significant for bare floors (p=0.1655).

^c^Based on Wilcoxon rank sum tests, Baltimore Round 1 units had
statistically significant larger median percent decreases in dust lead
loadings than did study units in either treatment group (p=0.0001 for
all 3 surface types).

**Table 16: Micrograms Per Square Foot Reduction in Pre- to Immediate
Post-Intervention *Single Surface* Dust Lead Loadings**

+-------------------------------+----------+------------+-------------+
| **Surface Type and            | **LHR    | **LHR+W    | **Baltimore |
| Statistic-Single Surface Dust | Units    | Units Pre  | HUD Units   |
| Samples**                     | Pre to   | to         | Pre to      |
|                               | I        | Immediate  | Immediate   |
|                               | mmediate | Post-In    | Post-       |
|                               | P        | tervention | I           |
|                               | ost-Inte | µg/ft^2^   | ntervention |
|                               | rvention | R          | µg/ft^2^    |
|                               | µg/ft^2^ | eduction** | Reduction** |
|                               | Red      |            |             |
|                               | uction** |            |             |
+-------------------------------+----------+------------+-------------+
| [Bare floors (16 LHR, 63      | *5*      | *97*       | *98*        |
| LHR+W)]{.underline}:          |          |            |             |
|                               | **99**   | **226**    | **265**     |
| *25^th^ Percentile μg/ft^2^   |          |            |             |
| Decrease*                     | 3,027    | 971        | 618         |
|                               |          |            |             |
| **Median μg/ft^2^ Decrease**  |          |            |             |
|                               |          |            |             |
| 75^th^ Percentile μg/ft^2^    |          |            |             |
| Decrease                      |          |            |             |
+-------------------------------+----------+------------+-------------+
| [Interior window sills (16    | *70*     | *752*      | *800*       |
| LHR, 62 LHR+W)]{.underline}:  |          |            |             |
|                               | **497**  | **2,516**  | **2,492**   |
| *25^th^ Percentile μg/ft^2^   |          |            |             |
| Decrease*                     | 9,102    | 8,598      | 7,124       |
|                               |          |            |             |
| **Median μg/ft^2^ Decrease**  |          |            |             |
|                               |          |            |             |
| 75^th^ Percentile μg/ft^2^    |          |            |             |
| Decrease                      |          |            |             |
+-------------------------------+----------+------------+-------------+
| [Window troughs (16 LHR, 62   | *998*    | *1,640*    | *1,020*     |
| LHR+W)]{.underline}:          |          |            |             |
|                               | *        | **12,022** | **3,591**   |
| *25^th^ Percentile μg/ft^2^   | *4,111** |            |             |
| Decrease*                     |          | 131,245    | 12,994      |
|                               | 36,239   |            |             |
| **Median μg/ft^2^ Decrease**  |          |            |             |
|                               |          |            |             |
| 75^th^ Percentile μg/ft^2^    |          |            |             |
| Decrease                      |          |            |             |
+-------------------------------+----------+------------+-------------+

Source: Form 04B

^1^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead Hazard Control Grant Program and were compiled using
initial Phase 2 data (immediate post-intervention). For floors,
Baltimore HUD unit data include both interior floor and entry floor
data.

**Figure 8: Pre- and Immediate Post-Intervention *Single Surface* Dust
Lead Loading for LHR and LHR+W Units (Logarithmic Scale)**

![](media/image9.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

6.  ***Units Having an Increase in Single Surface Dust Lead Loadings
    from Pre- to Immediate Post-Intervention***

Despite the significant median decreases in dust lead loadings between
pre- and immediate post-intervention, data in Table 17 on page 46 show
that some units experienced increases in single surface dust lead
loadings between these two phases. The percentage of LHR+W units that
underwent an increase was generally lower than that of LHR units and was
comparable to that of Baltimore HUD units.

Table 17: Number and Percent of Units Having an Increase in *Single
Surface* Dust Lead Loadings from Pre- to Immediate Post-Intervention

+------------------+----------------+---------------+----------------+
| **Surface Type   | # LHR          | **LHR+W**     | **Baltimore    |
| and Sample       |                |               | HUD Units**    |
| Type**           |                |               |                |
+------------------+----------------+---------------+----------------+
| [Bare            | 4/16 (25%)     | 4/63 (6%)     | 12/278 (4%)    |
| Floo             |                |               |                |
| rs]{.underline}: |                |               |                |
+------------------+----------------+---------------+----------------+
| [Interior window | 2/16 (12%)     | 1/62 (2%)     | 2/277 (1%)     |
| sil              |                |               |                |
| ls]{.underline}: |                |               |                |
+------------------+----------------+---------------+----------------+
| [Window          | 2/16 (12%)     | 1/62 (2%)     | 13/273 (5%)    |
| Troug            |                |               |                |
| hs]{.underline}: |                |               |                |
+------------------+----------------+---------------+----------------+

7.  ***Comparison of Immediate Post-Intervention Single Surface Results
    with Clearance Standards/Guidance***

Under the lead hazard reduction treatment option of EA 6-8, enrolled LHR
and LHR+W units were only required to pass a visual inspection performed
by an independent visual inspector; collection of post-treatment dust
samples and comparison of such results to clearance standards were not
required. However, this study considered clearance dust standards set by
Maryland and by HUD/EPA to assess the extent to which prescribed
treatments produced dust results that were sufficient for safe occupancy
of treated units and to help determine whether the prescribed
independent visual inspection procedure provided a sufficient level of
lead hazard reduction. This comparison to clearance standards is not
required by EA 6-8 and was performed in this study for research purposes
only.

If such testing had been required, for single surface floor dust
samples, 35 percent of the LHR units and 25 percent of the LHR+W units
had at least one floor sample that would have "failed" the Maryland
standard of 200 μg/ft^2^ (see Table 18 on page 47). Sixty (60) percent
of the LHR units and 41 percent of the LHR+W units had at least one
floor sample that would have "failed" the HUD/EPA 1995 guidance[^7] of
100 μg/ft^2^. Assigned treatment group was not significantly associated
with a unit "passing" or "failing" either of these two clearance
standards (p-values=0.4 and 0.14 for clearance standards of 200 and 100
µg/ft^2^, respectively). These are generally higher "failure" rates than
the 29 percent initial floor failure rate observed for vacant Baltimore
Round I units enrolled in the National Evaluation.[^8]

***Table 18: Immediate Post-Intervention Single Surface "Clearance
Failures" --*** Floors

+-------------------------------+------------+-----------+-----------+
| **Immediate Post-Intervention | **LHR**    | **LHR+W** | **All     |
| *Single Surface* Dust Sample  |            |           | Units**   |
| Results -- *FLOOR* "Clearance | **(20      | **(63     |           |
| Failures"^a^**                | units      | units     | **(83     |
|                               | total)**   | total)**  | units     |
|                               |            |           | total)**  |
+-------------------------------+------------+-----------+-----------+
| **\# units (%)  100          | 12 (60%)   | 26 (41%)  | 38 (46%)  |
| μg/ft^2^**                    |            |           |           |
+-------------------------------+------------+-----------+-----------+
| **\# units (%)  200          | 7 (35%)    | 16 (25%)  | 23 (28%)  |
| μg/ft^2^**                    |            |           |           |
+-------------------------------+------------+-----------+-----------+

^a^Clearance "failure" was not significantly associated with assigned
treatment group (p=0.403 and p=0.143 for clearance stds of 200 and 100
µg/ft^2^, respectively)

For single surface interior window sill dust samples, replacement of
windows in the LHR+W units resulted in fewer "clearance failures" (see
Table 19). If clearance testing had been required, 20 percent of the LHR
units and five percent of the LHR+W units had at least one sill sample
that would have "failed" the Maryland and HUD/EPA guidance of 500
μg/ft^2.^ Assigned treatment group was significantly associated with
post-intervention interior window sill dust lead loadings "passing" or
"failing" at 500 µg/ft^2^ (p-value=0.035). These rates are higher than
the one percent sill initial failure rate observed for vacant Baltimore
Round I units enrolled in the National Evaluation.^8^

***Table 19: Immediate Post-Intervention Single Surface "Clearance
Failures" --*** Interior Window Sills

+----------------------------+-------------+------------+-------------+
| **Immediate                | **LHR**     | **LHR+W**  | **All       |
| Post-Intervention *Single  |             |            | Units**     |
| Surface* Dust Sample       | **(20 units | **(62      |             |
| Results -- *INTERIOR       | total)**    | units      | **(82 units |
| WINDOW SILL* "Clearance    |             | total)**   | total)**    |
| Failures"^a^**             |             |            |             |
+----------------------------+-------------+------------+-------------+
| **\# units (%)  500       | 4 (20%)     | 3 (5%)     | 7 (8%)      |
| μg/ft^2^**                 |             |            |             |
+----------------------------+-------------+------------+-------------+

^a^Clearance "failure" was significantly associated with assigned
treatment group (p=0.035).

Again, for single surface window trough dust samples, replacement of
windows in the LHR+W units resulted in a lower percentage of "clearance
failures" (see Table 20 on page 48). Had clearance testing been
required, 50 percent of the LHR units and 19 percent of the LHR+W units
had at least one trough sample that would have "failed" the Maryland and
HUD/EPA guidance standard of 800 μg/ft^2^. Assigned treatment group was
significantly associated with post-intervention window trough dust lead
loadings "passing" or "failing" this standard (p-value=0.007). These
rates are higher than the six percent initial trough failure rate noted
for Baltimore Round I units.^8^

**Table 20: Immediate Post-Intervention *Single Surface* "Clearance
Failures" -- *Window Troughs***

+---------------------------+-----------+-------------+--------------+
| **Immediate               | **LHR**   | **LHR+W**   | **All        |
| Post-Intervention *Single |           |             | Units**      |
| Surface* Dust Sample      | **(20     | **(62 units |              |
| Results -- *WINDOW        | units     | total)**    | **(82 units  |
| TROUGH* "Clearance        | total)**  |             | total)**     |
| Failures"^a^**            |           |             |              |
+---------------------------+-----------+-------------+--------------+
| **\# units (%)  800      | 10 (50%)  | 12 (19%)    | 22 (27%)     |
| μg/ft^2^**                |           |             |              |
+---------------------------+-----------+-------------+--------------+

^a^Clearance "failure" was significantly associated with assigned
treatment group (p=0.007).

B.  **Results of Immediate Post-Intervention Visual Assessments**

As required in EA 6-8, each of the 121 units was independently inspected
and passed the required visual inspection after the prescribed
treatments were completed. As one of the evaluation measures of this
study, LAAP inspectors performed a separate, confirmatory visual
assessment ([not]{.underline} related to the property owner's statutory
requirement for an independent visual inspection) in each unit to
determine if any visible treatment "failures" could be detected. For the
purposes of this study, a treatment "failure" was defined as an
observation by the LAAP inspector that one or more of the ten lead
hazard reduction treatments prescribed in the statute had not been fully
completed. The Maryland statute did not specify a "de minimis" level
above which the treatment was considered a "failure;" therefore, any
observable deficient or missing treatment was classified as a "failure."

A complete list of immediate post-intervention visual assessment
"failures" is presented in Appendix G. Table 21 on page 49 presents the
distribution of treatment "failures" per unit. There were no units
having more than 5 "failures." Notably, the LAAP inspectors found that
51 of the 57 LHR units (89 percent) and 60 of the 64 (94 percent) of the
LHR+W units "failed" the confirmatory visual assessment for at least one
item. This equates to an overall visual assessment "failure" rate of 92
percent for the 121 study units. The owner corrected treatment
"failures" noted during the immediate post-intervention sampling visit
before tenants moved in. These corrections were "validated" by LAAP
inspectors, who required owners and/or contractors to complete their
work prior to payment.

Overall, the likelihood of LHR units having one or more "failures" was
almost the same as that of the LHR+W units. The mean number of "failure"
types per unit for LHR units (2.1) was significantly different and
higher than that for LHR+W units (1.7) (p-value=0.0255). If only
"failure" types applicable to both treatment groups are considered, LHR
units have slightly more mean "failures" (1.8) than LHR+W units (1.6).
However, this difference is not significant (p-value=0.1389).

**Table 21: Number of Immediate Post-Intervention Visual Assessment
"Failures" Per Unit**

+-----------------------------------+----------+----------+----------+
| **Number of Immediate             | **LHR**  | *        | **All    |
| Post-Intervention Visual          |          | *LHR+W** | Units**  |
| Assessment "Failures" Per         | **\#     |          |          |
| Unit^a^**                         | Units**  | **\#     | **\#     |
|                                   |          | Units**  | Units**  |
| **(57 LHR units, 64 LHR+W         | **(%     |          |          |
| units)**                          | Units)** | **(%     | **(%     |
|                                   |          | Units)** | Units)** |
+-----------------------------------+----------+----------+----------+
| "0" lead hazard treatment         | 6 (10%)  | 4 (6%)   | 10 (8%)  |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "1" lead hazard treatment         | 7 (12%)  | 26 (41%) | 33 (27%) |
| "failure"                         |          |          |          |
+-----------------------------------+----------+----------+----------+
| "2" lead hazard treatment         | 22 (39%) | 21 (34%) | 44 (36%) |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "3" lead hazard treatment         | 19 (33%) | 9 (14%)  | 28 (23%) |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "4" lead hazard treatment         | 2 (4%)   | 3 (5%)   | 5 (4%)   |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+
| "5" lead hazard treatment         | 1 (2%)   | 0 (0)    | 1 (1)    |
| "failures"                        |          |          |          |
+-----------------------------------+----------+----------+----------+

Source: Form 05

^a^The mean number of "failures" per unit (2.1 for LHR units; 1.7 for
LHR+W units) was significantly associated with assigned treatment group
(p=0.0255).

1.  ***Types of Immediate Post-Intervention "Failures"***

The most common "failure" was that not all paint was intact after
completion of the prescribed lead hazard reduction treatments (i.e.,
chipping, flaking and/or peeling paint remained) (see Table 22 on page
50). Almost 75 percent of all units (77 percent of the LHR units and 73
percent of the LHR+W units) exhibited evidence of this "failure" type.
Almost 40 percent of all units (44 percent of the LHR units and 33
percent of the LHR+W units) had evidence of visible paint chips and/or
debris remaining. It should be noted that the areal density (i.e.,
depth) and the lead concentration of the chips/debris were not measured.
In 43 percent of all units (49 percent of the LHR units and 38 percent
of the LHR+W units), the treatment "failure" of doors with painted
surfaces continuing to rub together or bind was observed. In 26 percent
of the LHR units, the window trough material (e.g., vinyl or metal) was
not properly attached. Other treatment "failure" types were much less
prevalent. None of the ten types of treatment "failures" were
significantly associated with treatment group based on chi-square
testing.

**Table 22: Immediate Post-Intervention Visual Assessment for Lead
Hazard Reduction Treatment "Failures"**

+-----------------------------------+-----------+----------+----------+
| **Type of Immediate               | **LHR**   | *        | **All    |
| Post-Intervention Visual          |           | *LHR+W** | Units**  |
| Assessment "Failures"^a^**        | **\#      |          |          |
|                                   | Units**   | **\#     | **\#     |
| **(57 LHR units, 64 LHR+W         |           | Units**  | Units**  |
| units)**                          | **(%      |          |          |
|                                   | Units)**  | **(%     | **(%     |
|                                   |           | Units)** | Units)** |
+-----------------------------------+-----------+----------+----------+
| Not all paint intact (chipping,   | 44 (77%)  | 47 (73%) | 91 (75%) |
| peeling or flaking paint remains) |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Visible structural defect that    | 1 (2%)    | 2 (3%)   | 3 (2%)   |
| could cause paint deterioration   |           |          |          |
| remains                           |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If sills stripped/repainted or    | 2 (4%)    | 6 (9%)   | 8 (7%)   |
| replaced, not all treatments in   |           |          |          |
| place                             |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If sills encapsulated with vinyl, | 0 (0%)    | 1 (2%)   | 1 (1%)   |
| metal, etc., not all material is  |           |          |          |
| properly attached^b^              |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If troughs capped with vinyl,     | 15 (26%)  | N/A^c^   | 15       |
| metal, etc., not all material is  |           |          | (12%)^d^ |
| properly attached^b^              |           |          |          |
+-----------------------------------+-----------+----------+----------+
| For windows, not all top sashes   | 0 (0%)    | N/A^c^   | 0 (0)^d^ |
| are fixed in place                |           |          |          |
+-----------------------------------+-----------+----------+----------+
| For doors, painted surfaces       | 28 (49%)  | 24 (38%) | 52 (43%) |
| continue to rub together          |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Some bare floors are not smooth   | 2 (4%)    | 4 (6%)   | 6 (5%)   |
| and cleanable                     |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Not all kitchen and bathroom      | 4 (7%)    | 4 (6%)   | 8 (7%)   |
| floors are overlaid with          |           |          |          |
| water-resistant coverings         |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Visible paint chips or debris     | 25 (44%)  | 21 (33%) | 46 (38%) |
| remains                           |           |          |          |
+-----------------------------------+-----------+----------+----------+

Source: Form 05

^a^None of these "failure" types were significantly associated with the
assigned treatment group (p-values vary from 0.1949 to 0.633).

^b^Properly attached is defined as correctly installed, with caps held
firmly in place with a sufficient number of fittings (e.g., nails) and
with caulking completed.

^c^In LHR+W units, these treatments were not necessary by virtue of the
installation of new vinyl replacement windows with unpainted top sashes
and troughs.

^d^Both values are understated due to the inapplicability of these
treatments for LHR+W units.

The geometric means of "failures" presented in Table 23 on page 51 were
calculated by first summing, within a unit, all reports of a particular
"failure" type having the same measurement units (e.g., ft^2^), then
calculating the geometric mean across dwelling units. These data
indicate that problems recorded by LAAP inspectors were easily observed.
For example, LAAP inspectors reported a dwelling unit geometric mean of
1 ft^2^ of non-intact paint in both LHR and LHR+W units at immediate
post-intervention. This type of "failure" was reported 63 times in 31
LHR units, and reported 78 times in 34 LHR+W units, indicating that this
was a widespread and large problem. "Visible paint chips and debris
remaining" at Phase 2 was also a extensive problem; a geometric mean of
8 ft^2^ of visible chips remained in LHR units and 16 ft^2^ remained in
LHR+W units, with this "failure" being reported 29 times in 19 LHR
units, and 48 times in 21 LHR+W units. As previously noted, the areal
density (i.e., depth) and the lead concentration of these chips/debris
were not measured. "Painted door surfaces rubbing together" was reported
40 times in 28 LHR units and 38 times in 24 LHR+W units, with at least
one door noted as a problem in each report. The status of floors at
Phase 2 was generally less widely reported but nonetheless noteworthy,
with a geometric mean of 4 ft^2^ of bare floors in LHR units and 2 ft^2^
in LHR+W units remaining not smooth and cleanable. A geometric mean of 2
ft^2^ of kitchen or bathroom floors in LHR units and 1 ft^2^ in LHR+W
units were reportedly not overlaid with water-resistant coverings at
immediate post-intervention.

# Table 23: Reporting Frequency of Specified Types of Treatment "Failures" at Immediate Post-Intervention 

+------------+-------+-------+-------+-------+-------+-------+-------+
|            |       | LHR   |       |       | LHR+W |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
| *          | *     | **\#  | *     | *     | **\#  | *     | *     |
| *"Failure" | *Unit | Units | *Repo | *"Fai | Units | *Repo | *"Fai |
| Type**     | of    | with  | rting | lure" | with  | rting | lure" |
|            | Meas  | Spec  | Freq. | Ma    | Spec  | Freq. | Ma    |
| **(57 LHR, | ure** | ified | of    | gnit. | ified | of    | gnit. |
| 64         |       | "Fai  | "Fai  | (     | "Fai  | "Fai  | (     |
| LHR+W)**   |       | lure" | lure" | geom. | lure" | lure" | geom. |
|            |       | Rp    | Type  | mean  | Rp    | Type  | mean  |
|            |       | t'd** | at**  | & 95% | t'd** | at**  | & 95% |
|            |       |       |       | Conf  |       |       | Conf  |
|            |       |       | **Ph  | Limi  |       | **Ph  | Limi  |
|            |       |       | 2**   | ts)** |       | 2**   | ts)** |
+------------+-------+-------+-------+-------+-------+-------+-------+
| Not all    | EA^a^ | 8     | 19    | 2 (1, | 1     | 1     | 1^c^  |
| paint      |       |       |       | 6)    |       |       |       |
| intact     |       |       |       |       |       |       |       |
|            |       |       |       |       |       |       |       |
| (44 LHR,   |       |       |       |       |       |       |       |
| 47 LHR+W)  |       |       |       |       |       |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
|            | LF    | 16    | 30    | 2 (1, | 20    | 27    | 1 (1, |
|            |       |       |       | 4)    |       |       | 2)    |
+------------+-------+-------+-------+-------+-------+-------+-------+
|            | SF    | 31    | 63    | 1     | 34    | 78    | 1     |
|            |       |       |       | (0.2, |       |       | (0.4, |
|            |       |       |       | 1)    |       |       | 3)    |
+------------+-------+-------+-------+-------+-------+-------+-------+
| For doors, | EA^a^ | 28    | 40    | 1 (1, | 24    | 38    | 1 (1, |
| painted    |       |       |       | 2)    |       |       | 2)    |
| surfaces   |       |       |       |       |       |       |       |
| continued  |       |       |       |       |       |       |       |
| to rub     |       |       |       |       |       |       |       |
| together   |       |       |       |       |       |       |       |
| (28 LHR,   |       |       |       |       |       |       |       |
| 24 LHR+W)  |       |       |       |       |       |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
| Some bare  | SF    | 2     | 5     | 4^c^  | 4     | 8     | 2^c^  |
| floors not |       |       |       |       |       |       |       |
| smooth &   |       |       |       |       |       |       |       |
| cleanable  |       |       |       |       |       |       |       |
| (2 LHR, 4  |       |       |       |       |       |       |       |
| LHR+W)     |       |       |       |       |       |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
| Not all    | SF    | 4     | 4     | 2 (1, | 4     | 4     | 1^c^  |
| kitchen &  |       |       |       | 4)    |       |       |       |
| bathroom   |       |       |       |       |       |       |       |
| floors     |       |       |       |       |       |       |       |
| overlaid   |       |       |       |       |       |       |       |
| with       |       |       |       |       |       |       |       |
| water      |       |       |       |       |       |       |       |
| -resistant |       |       |       |       |       |       |       |
| coverings  |       |       |       |       |       |       |       |
| (4 LHR, 4  |       |       |       |       |       |       |       |
| LHR+W)     |       |       |       |       |       |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
| Visible    | EA^b^ | 6     | 25    | 4 (2, | 1     | 1     | 2^c^  |
| paint      |       |       |       | 13)   |       |       |       |
| chips or   |       |       |       |       |       |       |       |
| debris     |       |       |       |       |       |       |       |
| remains    |       |       |       |       |       |       |       |
| (25 LHR,   |       |       |       |       |       |       |       |
| 21 LHR+W)  |       |       |       |       |       |       |       |
+------------+-------+-------+-------+-------+-------+-------+-------+
|            | LF    | 4     | 10    | 21^c^ | 0     | 0     | \--   |
+------------+-------+-------+-------+-------+-------+-------+-------+
|            | SF    | 19    | 29    | 8 (3, | 21    | 48    | 16    |
|            |       |       |       | 19)   |       |       | (6,   |
|            |       |       |       |       |       |       | 42)   |
+------------+-------+-------+-------+-------+-------+-------+-------+

EA=each; LF=linear foot; SF=square foot

^a^For these "failure" types, "each" denotes window components (e.g.,
upper sash, lower sash), door casings, or handrails in need of
re-painting. LF/SF values are not available for these occurrences.

^b^For these "failure" types, "each" denotes a window in need of
re-cleaning.

^c^No 95% confidence limits were calculated due to the small number of
units having this failure reported.

2.  ***Number of Rooms with "Failures" at Phase II***

In general, two to three rooms per unit had treatment "failures;" few
units had "failures" in only one room or in more than four rooms (see
Figure 9).

**Figure 9: Percentage of Units Having Specified Number of Rooms Per
Unit with Immediate Post-Intervention Visual Assessment "Failures"**

![](media/image10.wmf)In the 57 LHR units, considering only those rooms
with "failures" that are applicable to both LHR and LHR+W units, the
mean number of rooms with lead hazard control treatment "failures" was
3.1 rooms per unit, against a mean total number of 6.6 rooms per unit.
In the 64 LHR+W units, the mean number of rooms with "failures" was 2.6
rooms, against a mean total number of 6.7 rooms per unit. This mean
number of rooms with prescribed treatment "failures" was not
significantly associated with the assigned treatment group
(p-value=0.206). Table 24 on page 53 presents data on the mean number of
rooms per unit with a given "failure" type.

3.  ***Type of Contractor and Number of "Failures" at Immediate
    Post-Intervention***

For-profit contractors, the property owner/employees or non-profit
contractors performed lead hazard reduction treatments. (Only five units
were treated by non-profit contractors; therefore, these data are
excluded from the study.) For LHR units, the mean number of "failures"
per unit for for-profit contractor-treated units and property
owner/employee-treated units were 3.3 and 5.5, respectively (see Table
25 on page 53). For LHR+W units, the mean numbers of "failures" per unit
for for-profit contractors and property owners/employees-treated units
were 3.1 and 3.0, respectively. There was no significant association
between the mean number of "failures" per unit and the contractor type
based on a Fisher's Exact Test (p-value=0.4823).

**^Table\ 24:\ Mean\ Number\ of\ Rooms\ Per\ Unit\ with\ Specified\ Immediate\ Post-Intervention\ Visual\ Assessment\ "Failures"\ by\ Treatment\ Group^**a

+----------------------------------+-----------------+-----------------+
| **Type of Immediate              | **LHR**         | **LHR+W**       |
| Post-Intervention Visual         |                 |                 |
| Assessment "Failures"**          | **Mean \#       | **Mean \#       |
|                                  | Rooms**         | Rooms**         |
| **(57 LHR units, 64 LHR+W        |                 |                 |
| units)**                         | **Per Unit**    | **per Unit**    |
|                                  |                 |                 |
|                                  | **(95% Conf.    | **(95% Conf.    |
|                                  | Int.)**         | Int.)**         |
+----------------------------------+-----------------+-----------------+
| Not all paint intact (chipping,  | 1.7             | 1.4             |
| peeling or flaking paint         |                 |                 |
| remains)                         | (1.4; 2.1)      | (1.1; 1.7)      |
+----------------------------------+-----------------+-----------------+
| Visible structural defect that   | 0.02            | 0               |
| could cause paint deterioration  |                 |                 |
| remains                          | (0; 0.05)       | (0; 0.08)       |
+----------------------------------+-----------------+-----------------+
| If sills stripped/repainted or   | 0.05            | 0.2             |
| replaced, not all treatments in  |                 |                 |
| place                            | (0; 0.11)       | (0.07; 0.3)     |
+----------------------------------+-----------------+-----------------+
| If sills encapsulated with       | 0               | 0               |
| vinyl, metal, etc., not all      |                 |                 |
| material is property attached    |                 |                 |
+----------------------------------+-----------------+-----------------+
| If troughs capped with vinyl,    | 0.5             | N/A^b^          |
| metal, etc., not all material is |                 |                 |
| properly attached                | (0.35; 0.7)     |                 |
+----------------------------------+-----------------+-----------------+
| For windows, not all top sashes  | 0               | N/A^b^          |
| are fixed in place               |                 |                 |
+----------------------------------+-----------------+-----------------+
| For doors, painted surfaces      | 0.7             | 0.6             |
| continue to rub together         |                 |                 |
|                                  | (0.5; 0.9)      | (0.4; 0.8)      |
+----------------------------------+-----------------+-----------------+
| Some bare floors are not smooth  | 0.09            | 0.1             |
| and cleanable                    |                 |                 |
|                                  | (0.01; 0.2)     | (0; 0.2)        |
+----------------------------------+-----------------+-----------------+
| Not all kitchen and bathroom     | 0.07            | 0.1             |
| floors are overlaid with         |                 |                 |
| water-resistant coverings        | (0; 0.1)        | (0; 0.1)        |
+----------------------------------+-----------------+-----------------+
| Visible paint chips or debris    | 1.1             | 0.7             |
| remains                          |                 |                 |
|                                  | (0.8; 1.4)      | (0.5; 1.0)      |
+----------------------------------+-----------------+-----------------+

Source: Form 05

^a^Mean number of rooms with prescribed treatment "failures" was not
significantly associated with the assigned treatment group (p=0.206).

^b^In LHR+W units, these treatments were not necessary by virtue of the
installation of new vinyl replacement windows with unpainted top sashes
and troughs.

**Table 25: Mean Number of Immediate Post-Intervention "Failures" per
Unit by the Type of Contractor^a,b^**

  --------------------------------- ------------------- --------------------
                                    **Mean Number of    
                                    Immediate           
                                    Post-Intervention   
                                    "Failures" per      
                                    Unit**              

  **Contractor Type**               **LHR Units**       **LHR+W Units**

  For-profit contractor             3.3                 3.1

  Property owner/employees          5.5                 3.0
  --------------------------------- ------------------- --------------------

Source: Form 05

^a^ Because only a limited number of LHR and LHR+W units (i.e., five
combined) had nonprofit contractors performing the work, the number of
"failures" is not easily compared against for-profit contractors and
property owner/employees work. Therefore, nonprofit contractor data are
not presented in this table.

^b^The mean number of "failures" per unit and contractor type were not
significantly associated (p=0.4823).

# Description of and Factors Affecting Costs

Various cost data were collected during the study, including the
LAAP-approved costs for the prescribed lead hazard reduction treatments,
plus the additional window replacement costs for the LHR+W units. The
study also collected owner-estimated turnover costs that would have been
incurred even if the enrolled units had not been subject to the EA 6-8
risk reduction requirements. However, because these latter data were
based on interviews with property owners and/or their representatives,
they are considered highly subjective and were excluded from this study.
Finally, the study determined what type of contractor (e.g., for profit,
nonprofit or property owner/employee) performed the work and whether any
concurrent work (e.g., roof, plumbing and electrical repairs) was
completed in addition to the lead-related treatments.

The costs presented in this section are those considered to be solely
associated with EA 6-8 prescribed treatments. In other words, measures
that are not otherwise contained in existing housing code provisions
and/or part of a normal rental unit turnover regimen would be included
when determining the incremental cost of complying with the statute. The
measures that are considered unique to EA 6-8 include:

-   Stripping and repainting, replacing or encapsulating all interior
    window sills with vinyl, metal or any other material;

-   Ensuring that caps of vinyl, aluminum or other material are
    installed in all window troughs in order to make the window troughs
    smooth and cleanable;

-   Except for a treated or replacement window that is free of
    lead-based paint on its friction surfaces, fixing the top sash of
    all windows in place in order to eliminate the friction caused by
    movement of the top sash;

-   Re-hanging all doors necessary in order to prevent the rubbing
    together of a lead-painted surface with another surface;

-   Making all bare floors smooth and cleanable; and

-   HEPA-vacuuming and washing of the interior of the affected property
    with high phosphate detergent or its equivalent.

Depending on the nature of certain bathroom and kitchen floor repairs,
another EA 6-8 prescribed treatment that might or might not be
considered extra cost is ensuring that all kitchen and bathroom floors
are overlaid with a smooth, water-resistant covering.

As discussed in Section II.B, participating property owners received up
to 80 percent of their full lead hazard control costs from LAAP in the
form of a loan/grant, subject to a spending cap of \$10,000. The
remaining 20 percent was self-funded. LAAP funding was provided through
the HUD Round III Lead Hazard Control Grant. However, as part of this
study and in order to determine the incremental cost of complying with
EA 6-8, LAAP inspectors reviewed and revised the owners' original lead
hazard reduction costs by subtracting cost items that could be
considered code-related and/or part of normal unit turnover. The most
notable of these is painting, which was often the largest single cost
element. (See Appendix H for the gross lead hazard reduction costs, 80
percent of which were reimbursed by LAAP, and the estimated EA 6-8 lead
hazard reduction treatment costs for each of the enrolled units.)

Based on the LAAP inspectors' estimated EA 6-8 lead hazard reduction
treatment cost calculations, the median cost for completing the
prescribed treatments in LHR units was \$2,154, while for LHR+W the
median cost was \$1,649. The LHR units' median cost is likely higher
than the LHR+W units' median cost because LHR unit costs included the
expense of the prescribed window [treatments]{.underline}, while window
[replacement]{.underline} expenses for LHR+W units were calculated
separately (see Table 26). However, the median total lead cost for LHR+W
units (\$4,348) was over twice that for LHR units (\$2,154), reflecting
the added expense of window replacement.

**Table 26: Description of Lead Hazard Reduction Costs**

+-------------------------------------+---------------+---------------+
| **Lead Hazard Reduction             | # [LHR        | # [LHR+W      |
| Intervention Costs and Window       | ]{.underline} | ]{.underline} |
| Replacement Costs**                 |               |               |
|                                     | ##### 5^t     | ##### 5^t     |
| **(57 LHR units, 64 LHR+W units)**  | h^ Percentile | h^ Percentile |
|                                     |               |               |
|                                     | 25^th^        | 25^th^        |
|                                     | Percent.      | Percent.      |
|                                     |               |               |
|                                     | # Median      | # Median      |
|                                     |               |               |
|                                     | *75^th^       | *75^th^       |
|                                     | Percent.*     | Percent.*     |
|                                     |               |               |
|                                     | 95^th^        | 95^th^        |
|                                     | Percent.      | Percent.      |
+-------------------------------------+---------------+---------------+
| Cost of lead hazard reduction       | *\$820*       | *\$773*       |
| treatments only                     |               |               |
|                                     | \$1,462       | \$1,168       |
|                                     |               |               |
|                                     | **\$2,154**   | **\$1,649**   |
|                                     |               |               |
|                                     | *\$3,015*     | *\$2,212*     |
|                                     |               |               |
|                                     | \$3,920       | \$3,036       |
+-------------------------------------+---------------+---------------+
| Cost of window replacement only     | # *N/A*       | *\$1,625*     |
|                                     |               |               |
|                                     | ##### N/A     | \$2,200       |
|                                     |               |               |
|                                     | # N/A         | **\$2,600**   |
|                                     |               |               |
|                                     | ##### N/A     | *\$3,185*     |
|                                     |               |               |
|                                     | N/A           | \$4,200       |
+-------------------------------------+---------------+---------------+
| Total Lead Costs (lead hazard       | *\$820*       | *\$2,589*     |
| reduction treatments and, if        |               |               |
| applicable, window replacement)     | \$1,462       | \$3,750       |
|                                     |               |               |
|                                     | **\$2,154**   | **\$4,348**   |
|                                     |               |               |
|                                     | *\$3,015*     | *\$5,173*     |
|                                     |               |               |
|                                     | \$3,920       | \$6,458       |
+-------------------------------------+---------------+---------------+

Source: Form 05

Interestingly, when analyzing costs against the type of contractor
performing the lead hazard reduction treatments, for-profit contractors'
mean costs were slightly higher than property owner/employees' mean
costs in LHR units, but lower in LHR+W units (see Table 27 on page 56).

**Table 27: Mean Lead Hazard Reduction Costs by Contractor Type^a^**

+---------------------------------------+--------------+--------------+
| # Contractor Type                     | **LHR Mean   | **LHR+W Mean |
|                                       | Cost**       | Cost**       |
| # (56 LHR, 64 LHR+W)                  | **(std.      | **(std.      |
|                                       | d            | deviat.      |
|                                       | eviat.)^b^** | )^b^**       |
+---------------------------------------+--------------+--------------+
| For-profit contractor (27 LHR, 32     | \$2,405      | \$4,277      |
| LHR+W)                                | (1,196 )     | (1,309 )     |
+---------------------------------------+--------------+--------------+
| Property owner/employees (28 LHR, 28  | \$2,214 (770 | \$4,639      |
| LHR+W)                                | )            | (1,106 )     |
+---------------------------------------+--------------+--------------+

Source: Form 05

^a^Because only a limited number of LHR and LHR+W units (i.e., five
combined) had nonprofit contractors performing the work, the costs are
not easily compared against for-profit contractor and property
owner/employee work. Therefore, nonprofit contractor data are not
presented in this table.

^b^ Mean costs for LHR units were calculated using only the cost of
prescribed lead hazard reduction treatments, while those for LHR+W units
also included additional costs associated with window replacement.

In the LHR+W units, an average of nine (9) to 10 windows were replaced.
(As previously noted, this replacement was not part of the lead hazard
reduction treatments required by the statute.) Replacement windows were
typically double-hung, thermo-pane vinyl units; existing window jambs
and exterior casing were usually wrapped with aluminum coil stock and
any remaining painted components were stabilized and repainted. The
median cost per window replacement was \$275, with a minimum recorded
cost per window of \$220 and a maximum recorded cost per window of
\$357. Additional (i.e., concurrent) work was performed in 17 of 57 LHR
units (29.8 percent) and 27 of 64 LHR+W units (42.2 percent). This work
included roofing, plumbing, heating and electrical repairs and
replacement of other fixtures and components.

For the 57 LHR units, the mean number of days to complete the
intervention was 57.8 days. For the 64 LHR+W units, the mean number of
days to complete the intervention was 56.5 days. These relatively long
periods reflect the fact that many property owners/employees who
performed their own work, and some for-profit and nonprofit contractors,
worked intermittently over time for various reasons. Therefore, these
mean numbers are not representative of the actual uninterrupted time
that would have been needed to complete the prescribed lead hazard
reduction treatments.

A.  **Description of Statistical Modeling Through Immediate
    Post-Intervention**

    1.  ***Predicting Dust Lead Loading at Immediate
        Post-Intervention***

A multiple regression model with backward elimination[^9] was run to
identify which factors would be significant predictors of immediate
post-intervention dust lead loadings. A separate model was run for each
surface type (i.e., bare floors, interior window sills and window
troughs). The dwelling unit average of single surface samples for each
surface type was the dependent variable in each model. Dust lead loading
measurements were log transformed. (Tables of statistical results from
these models are provided in Appendix I.)

The set of possible predictors considered were:

-   Type of building (e.g., rowhouse, more than four units in a
    building, single detached, etc.);

-   Year of construction (e.g., pre-1910, 1910-1919, 1920-1929, etc.);

-   Contractor type (i.e., for-profit, nonprofit, property
    owner/employee);

-   Concurrent work (i.e., yes or no);

-   Treatment group (i.e., LHR or LHR+W);

-   Pre-intervention dwelling unit average of single surface samples
    dust lead loading results for a given surface type (i.e., bare
    floors, interior window sills or window troughs);

-   Number of items of interior dwelling unit deterioration (0-4);

-   Number of items of exterior building deterioration (0-6);

-   Percent of windows replaced out of the total number of windows in a
    dwelling unit;

-   Market value of a dwelling unit (\$);

-   Total lead hazard reduction cost for a dwelling unit, including
    window replacement costs, if applicable (\$); and

-   Interactions of (1) the number of interior dwelling unit
    deterioration items, (2) the number of exterior building
    deterioration items, and (3) pre-intervention dust lead loadings
    with each of the following: concurrent work, percent of windows
    replaced, total lead hazard reduction cost, and assigned treatment
    group.

(Note: The relationship between components of the visual assessment and
immediate post-intervention dust lead loading results was assessed and
found to be non-significant in every case. Hence, these variables were
not included in the models.)

On bare floors, the entire set of possible predictors did not
significantly predict immediate post-intervention floor dust lead
loading (p-value=0.4687). On interior window sills, the variables found
to predict immediate post-intervention dust loading were
pre-intervention interior window sill dust lead loading and treatment
group. The percentage of variation accounted for in immediate
post-intervention dust lead loading by these two variables (i.e., R^2^)
is 27 percent. On window troughs, the variables found to predict
immediate post-intervention dust lead loading were pre-intervention
window trough dust lead loading and treatment group. The percentage of
variation accounted for in immediate post-intervention dust lead loading
by these two variables (i.e., R^2^) is 26 percent.

1.  ***Predicting Dust Lead Loading "Failures" at Immediate
    Post-Intervention***

Separate logistic regression models with backward elimination were
employed to predict whether dwelling units would have clearance
"failures" on bare floors, interior window sills and window troughs
based on standards of 100 µg/ft^2^, 500 µg/ft^2^, and 800 µg/ft^2^,
respectively (see Appendix I). In a logistic model, the outcome of
interest is a binary response variable such as "pass/fail." The same set
of possible predictors that were used in predicting dust lead loading at
immediate post-intervention were also employed for this model, except
that interactions were not included (not appropriate for logistic
models).

Clearance "failure" on bare floors was not modeled since no relationship
was found when attempting to predict floor dust lead loading at
immediate post-intervention. On interior window sills, the only variable
found to significantly predict immediate post-intervention clearance
"failures" was the percent of windows replaced out of the total number
of windows in a dwelling unit. The higher the percentage of windows
replaced, the lower the clearance "failures." On window troughs, the
variables found to predict immediate post-intervention clearance
"failures" were number of items of exterior building deterioration
(increasing number would yield more clearance "failures") and percent of
windows replaced (increasing percent would yield fewer clearance
"failures").

2.  ***Predicting Immediate Post-Intervention Visual Assessment
    "Failures"***

A logistic model with backward elimination was also employed to predict
whether dwelling units would have visual assessment "failures," again
using the same set of possible predictors employed for predicting dust
lead loading at immediate post-intervention and dust lead loading
"failures." The only variable found to significantly influence visual
assessment "failure" was the number of items of exterior building
deterioration; increasing numbers would yield more visual assessment
"failures."

# ONE-YEAR POST-INTERVENTION (PHASE III) RESULTS

On the average, one-year post-intervention visits occurred 55 weeks
after the immediate post-intervention sampling visit, with a minimum of
40 weeks and a maximum of 74 weeks between the two visits. Of the 121
units that had the prescribed lead hazard reduction treatment
interventions and a full immediate post-intervention assessment, a total
of 73 units (36 LHR and 37 LHR+W) completed one-year post-intervention
dust lead sampling and a full one-year post-intervention visual
assessment. The relationship between various one-year post-intervention
factors and the assigned treatment group (i.e., LHR versus LHR+W units)
was examined using various statistical tests.

# 

# Physical Characteristics and Baseline Condition of Enrolled Units Having One-Year Post-Intervention Data

Section V.A and Appendices C and D contain detailed discussions and
lists of the physical characteristics and baseline conditions for the
177 units that underwent complete pre-intervention visual assessments,
including those having one-year post-intervention data. Because these
variables may have influenced one-year post-intervention results, and
because these variables may be different for the smaller one-year
post-intervention dataset of 73 units, this section summarizes baseline
characteristics and conditions, including pre-intervention dust lead
loadings, for the 73 units for which one-year post-intervention data
were collected.

3.  ***Baseline Physical Characteristics for Enrolled Units Having
    One-Year Post-Intervention Data***

The majority (81%) of the 73 one-year post-intervention units were
single-family rowhouses, two were single detached residences, and the
remaining units were present in multifamily buildings (two in duplexes,
one in a two-flat, two in a triplex, and seven in building with more
than 4 units). This grouping is not significantly different from that of
the larger dataset based on Fisher's exact test (p=0.39 and 0.14 in LHR
and LHR+W units, respectively).

Eighty-five percent of the one-year post-intervention units were
constructed 70 or more years ago, with the largest percentage (42%)
built between 1920 and 1929. Controlling for treatment group, this
grouping is not significantly different from that of the larger dataset
discussed in Section VII.A based on Mantel-Haenszel's mean score
statistic (p=0.28). Other baseline dwelling unit characteristics are
summarized in Table 28.

# Table 28: Dwelling Unit Baseline Characteristics for One-Year Post-Intervention Units

+---------------------------------+---------+-------------+-----------+
| #                               | **Mean  | **Mean      | **Mean    |
|                                 | (std.   | (std.       | (std.     |
| # Dwelling Unit Characteristic  | dev     | deviat.)**  | d         |
|                                 | iat.)** |             | eviat.)** |
| **(36 LHR, 37 LHR+W Units)**    |         | **LHR+W     |           |
|                                 | **LHR   | Units**     | **All     |
|                                 | Units** |             | Units**   |
+---------------------------------+---------+-------------+-----------+
| Estimated market value of       | \       | \$24,000    | \$23,700  |
| dwelling unit                   | $23,400 | (14,800)    | (13,600)  |
|                                 | (       |             |           |
| (mean rounded to nearest \$100) | 12,400) |             |           |
+---------------------------------+---------+-------------+-----------+
| \# of rooms in dwelling unit    | 7 (1)   | 7 (1)       | 7 (1)     |
+---------------------------------+---------+-------------+-----------+
| \# of bedrooms in dwelling unit | 3 (1)   | 3 (1)       | 3 (1)     |
+---------------------------------+---------+-------------+-----------+
| \# of windows in dwelling unit  | 10 (3)  | 11 (4)      | 10 (3)    |
+---------------------------------+---------+-------------+-----------+
| \# of unpainted windows in      | 2 (4)   | 1 (2)       | 1 (3)     |
| dwelling unit (e.g., vinyl,     |         |             |           |
| aluminum)                       |         |             |           |
+---------------------------------+---------+-------------+-----------+
| Approximate square feet of      | 1,100   | 1,100 (330) | 1,100     |
| living space                    | (280)   |             | (305)     |
+---------------------------------+---------+-------------+-----------+

4.  ***Baseline Exterior Building and Interior Unit Conditions for
    One-Year Post-Intervention Units***

Baseline exterior building conditions for the 73 one-year
post-intervention units are summarized in Table 29 on page 60, which
lists the seven items checked by the LAAP inspectors on their initial
visit to each unit. Table 30 on page 60 lists the number of observed
items of exterior building deterioration in the 73 one-year
post-intervention units. In general, there were minimal observed
differences in exterior deterioration between the LHR and LHR+W units,
with none of the types of exterior building deteriorations being
significantly associated with assigned treatment group based on Fisher's
exact tests.

Based on Cochran-Mantel-Haenszel statistical testing, the number of
observed items of exterior building deterioration was also not
significantly associated with assigned treatment group (p=0.37; see
Table 30 on page 60). Controlling for treatment group, the 73-unit
one-year post-intervention dataset tended to have more exterior
deteriorations than the larger dataset discussed in Section VII.A.2
based Mantel-Haenszel mean score statistic (p\<0.001).

**Table 29: Baseline Exterior Building Deterioration Summary for
One-Year Post-Intervention**

**Units**

+-----------------------------------+----------+----------+-----------+
| **Types of Exterior Building      | **LHR**  | *        | **All     |
| Deterioration^a^**                |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(36 LHR units, 37 LHR+W         | Units**  | **\#     | **\#      |
| units)**                          |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| Roofs, gutters, downspouts --     | 3 (8%)   | 7 (19%)  | 10 (14%)  |
| missing, broken, holes, cracks    |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Chimney -- cracked, bricks loose  | 1 (3%)   | 1 (3%)   | 2 (3%)    |
| or missing, unstable, out of      |          |          |           |
| plumb                             |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Walls and siding -- large cracks  | 4 (11%)  | 6 (16%)  | 10 (14%)  |
| or holes, boards or shingles      |          |          |           |
| broken or missing                 |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Windows and doors -- ≥ two        | 7 (19%)  | 9 (24%)  | 16 (22%)  |
| windows or doors broken, missing, |          |          |           |
| boarded up                        |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Porch or steps -- major elements  | 2 (6%)   | 4 (11%)  | 6 (8%)    |
| broken, missing, out of plumb     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Foundation -- major visible       | 0        | 1 (3%)   | 1 (1%)    |
| cracks, missing materials,        |          |          |           |
| unsound                           |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Evidence of exterior ground       | 7 (19%)  | 10 (27%) | 17 (23%)  |
| contaminated with paint chips     |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^ Based on Fisher's Exact test, none of the 7 types of exterior
building deterioration were significantly associated with assigned
treatment group (p varied from 0.31 to 1).

**Table 30: Number of Baseline Exterior Building Deterioration Items for
One-Year Post-Intervention Units**

+-----------------------------------+----------+---------+------------+
| **\# Items of Exterior            | **LHR**  | **      | **All      |
| Deterioration per Building^a^**   |          | LHR+W** | Units**    |
|                                   | **\#     |         |            |
| **(36 LHR units, 37 LHR+W         | Units**  | **\#    | **\#       |
| units)**                          |          | Units** | Units**    |
|                                   | **(%     |         |            |
|                                   | Units)** | **(%    | **(%       |
|                                   |          | U       | Units)**   |
|                                   |          | nits)** |            |
+-----------------------------------+----------+---------+------------+
| "0" items of exterior             | 19 (53%) | 15      | 34 (47%)   |
| deterioration                     |          | (40%)   |            |
+-----------------------------------+----------+---------+------------+
| "1" item of exterior              | 12 (33%) | 13      | 25 (34%)   |
| deterioration                     |          | (35%)   |            |
+-----------------------------------+----------+---------+------------+
| "2" items of exterior             | 3 (8%)   | 5 (14%) | 8 (11%)    |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "3" items of exterior             | 2 (6%)   | 1 (3%)  | 3 (4%)     |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+
| "4" items of exterior             | 0        | 3 (8%)  | 3 (4%)     |
| deterioration                     |          |         |            |
+-----------------------------------+----------+---------+------------+

Source: Form 02

^a^Based on Cochran-Mantel-Haenszel test, the number of exterior
deterioration items was not significantly associated with assigned
treatment group (p=0.37).

Baseline interior dwelling unit conditions for the 73 one-year
post-intervention units are summarized in Table 31 on page 61, which
lists the five items checked by LAAP inspectors during their initial
visit to each unit, and in Table 32 on page 61, which lists the number
of observed items of interior unit deterioration in the 73 units. LHR+W
units had higher percentages of interior deterioration than LHR units
for three of the five items. Most notably, LHR+W units were more likely
than LHR units to have walls, ceilings, doors, and trim in need of
repair, replacement or repainting. This type of interior deterioration
was significantly associated with assigned treatment group based on
Fisher's exact testing (p=0.0559). Controlling for treatment group, the
one-year post-intervention dataset did not significantly differ from the
dataset discussed in Section VII.A.2 in terms of the number of interior
deteriorations based on a Mantel-Haenszel mean score statistic (p=0.28).

**Table 31: Summary of Baseline Interior Dwelling Unit Deterioration for
One-Year Post-Intervention Units**

+-----------------------------------+----------+----------+-----------+
| **Type of Interior Dwelling Unit  | **LHR**  | *        | **All     |
| Deterioration**                   |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(36 LHR units, 37 LHR+W         | Units**  | **\#     | **\#      |
| units)**                          |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| Walls, ceiling, doors and trim -- | 10 (28%) | 19 (51%) | 29 (40%)  |
| cracks, need for repair, replace  |          |          |           |
| or major repainting^a^            |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Floors -- loose, missing or       | 21 (58%) | 25 (68%) | 46 (63%)  |
| cracked, finish worn,             |          |          |           |
| deteriorated carpeting            |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Heating/cooling and plumbing --   | 5 (14%)  | 5 (14%)  | 10 (14%)  |
| need for extensive repair         |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Interior damage due to roof leak  | 5 (14%)  | 5 (14%)  | 10 (14%)  |
| -- need for extensive repair      |          |          |           |
+-----------------------------------+----------+----------+-----------+
| Rooms with \>2 ft^2^ of paint     | 27 (75%) | 32 (89%) | 59 (81%)  |
| deterioration on walls, woodwork, |          |          |           |
| doors, windows, etc.              |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^Based on Chi-square testing, deterioration of walls, ceilings, doors
and trim was significantly associated with assigned treatment group
(p=0.0559). None of the other four types of interior deterioration were
associated with treatment group (p varied from 0.47 to 1).

The total number of baseline interior unit deterioration items for the
one-year post-intervention units was not significantly associated with
assigned treatment group (p=0.5956; see Table 32).

**Table 32: Number of Baseline Interior Dwelling Unit Deterioration
Items for One-Year Post-Intervention Units**

+-----------------------------------+----------+----------+-----------+
| **Number of Items of Interior     | **LHR**  | *        | **All     |
| Deterioration per Dwelling Unit** |          | *LHR+W** | Units**   |
|                                   | **\#     |          |           |
| **(36 LHR Units, 37 LHR+W         | Units**  | **\#     | **\#      |
| Units)^a^**                       |          | Units**  | Units**   |
|                                   | **(%     |          |           |
|                                   | Units)** | **(%     | **(%      |
|                                   |          | Units)** | Units)**  |
+-----------------------------------+----------+----------+-----------+
| "0" items of interior             | 11 (31%) | 7 (19%)  | 18 (25%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "1" item of interior              | 13 (36%) | 13 (35%) | 26 (35%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "2" items of interior             | 8 (22%)  | 10 (27%) | 18 (25%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+
| "3" items of interior             | 4 (11%)  | 7 (19%)  | 11 (15%)  |
| deterioration                     |          |          |           |
+-----------------------------------+----------+----------+-----------+

Source: Form 02

^a^Total number of items of interior deterioration was not significantly
associated with assigned treatment group based on
Cochran-Mantel-Haenszel testing (p=0.5956).

5.  ***Pre-Intervention Dust Lead Loadings for the 73 One-Year
    Post-Intervention Units***

**[Pre-Intervention Composite Dust Lead Loadings]{.underline}.**
Composite dust samples were collected from bare floors, interior window
sills, window troughs and when necessary from carpeted floors in all
one-year post-intervention LHR and LHR+W units. Because very few
one-year post-intervention units had carpeted floors, sample results for
carpeted floors were excluded from this report. For the three surface
types, the median pre-intervention dust lead loadings in the LHR+W units
were greater than those in the LHR units (Table 33 on page 62).
Pre-intervention composite dust lead loadings were marginally
significantly associated with assigned treatment group for bare floors
and window troughs (p=0.0676 and 0.0547, respectively) but not for
window sills (p=0.1109). Controlling for treatment group, the 73-unit
one-year post-intervention dataset was not significantly different from
the larger pre-intervention dataset (see Section VII.B.1) in terms of
pre-intervention composite dust lead loadings on bare floors, sills and
troughs (p=0.16, 0.57 and 0.40, respectively).

**Table 33: Pre-Intervention *Composite* Sample Dust Lead Loading for
One-Year**

**Post-Intervention Units**

+------------------+--------------------------+------------------------+
| **Surface Type** | **[LHR Dust Lead Loading | **[LHR+W Dust Lead     |
|                  | (                        | Loading                |
|                  | μg/ft^2^)]{.underline}** | (μg                    |
|                  |                          | /ft^2^)]{.underline}** |
|                  | *5^th^ Percentile*       |                        |
|                  |                          | *5^th^ Percentile*     |
|                  | 25^th^ Percentile        |                        |
|                  |                          | 25^th^ Percentile      |
|                  | **Median**               |                        |
|                  |                          | **Median**             |
|                  | *75^th^ Percentile*      |                        |
|                  |                          | *75^th^ Percentile*    |
|                  | 95^th^ Percentile        |                        |
|                  |                          | 95^th^ Percentile      |
|                  | **Geometric Mean**       |                        |
|                  |                          | **Geometric Mean**     |
|                  | *95% Confid. Limits*     |                        |
|                  |                          | *95% Confid. Limits*   |
+------------------+--------------------------+------------------------+
| Bare floors^a,b^ | *30*                     | *38*                   |
|                  |                          |                        |
| (34 LHR units,   | 64                       | 128                    |
|                  |                          |                        |
| 34 LHR+W units)  | **120**                  | **454**                |
|                  |                          |                        |
|                  | *639*                    | *1,635*                |
|                  |                          |                        |
|                  | 36,400                   | 16,800                 |
|                  |                          |                        |
|                  | **251**                  | **495**                |
|                  |                          |                        |
|                  | *(127; 498)*             | *(263; 933)*           |
+------------------+--------------------------+------------------------+
| Interior window  | *31*                     | *287*                  |
| sills^a,b^       |                          |                        |
|                  | 384                      | 979                    |
| (35 LHR units,   |                          |                        |
|                  | **1,739**                | **2,930**              |
| 37 LHR+W units)  |                          |                        |
|                  | *7,520*                  | *9,920*                |
|                  |                          |                        |
|                  | 32,366                   | 234,305                |
|                  |                          |                        |
|                  | **1,283**                | **3,850**              |
|                  |                          |                        |
|                  | *(592; 2,780)*           | *(1,982, 7,480)*       |
+------------------+--------------------------+------------------------+
| Window           | *67*                     | *1,774*                |
| troughs^a,b^     |                          |                        |
|                  | 2,050                    | 4,610                  |
| (35 LHR units,   |                          |                        |
|                  | **10,219**               | **12,524**             |
| 37 LHR+W units)  |                          |                        |
|                  | *34,648*                 | *128,571*              |
|                  |                          |                        |
|                  | 132,166                  | 447,429                |
|                  |                          |                        |
|                  | **7,070**                | **21,888**             |
|                  |                          |                        |
|                  | *(3,318; 15,065)*        | *(11,578; 41,378)*     |
+------------------+--------------------------+------------------------+

Source: Form 04A, Phase III

^a^Approximately 95% of bare floor composites, interior window sill
composites, and window trough composites were comprised of 4
sub-samples; the rest were comprised of either 2 or 3 sub-samples.

^b^ Based on a Kruskal-Wallis test, median pre-intervention composite
dust lead loadings were marginally significantly associated with
assigned treatment group for bare floors and window troughs (p=0.0676
and 0.0547, respectively) but not for window sills (p=0.1109).

**[Pre-Intervention Single Surface Dust Lead Loadings]{.underline}.**
Single surface dust samples were collected from bare floors, interior
window sills, window troughs and, when necessary, from carpeted floors
in all one-year post-intervention LHR and LHR+W units. Because very few
one-year post-intervention units had carpeted floors, sample results for
carpeted floors were excluded from this report. As previously discussed,
single surface samples were collected in a subset of LHR units. However,
due to budget constraints, LAAP ceased collecting such samples in LHR
units during one-year and two-years post-intervention, but continued to
collect single surface samples in LHR+W units. Therefore,
pre-intervention single surface results are summarized only for LHR+W
units (see Table 34).

**Table 34: Pre-Intervention *Single Surface* Sample Dust Lead Loadings
for One-Year**

**Post-Intervention Units^a^**

+-----------------+-------------------------+--------------------------+
| **Surface       | **[LHR+W Dust Lead      | **[Baltimore HUD         |
| Type**          | Loading                 | Units^b^                 |
|                 | (μ                      | (                        |
|                 | g/ft^2^]{.underline})** | µg/ft^2^)]{.underline}** |
|                 |                         |                          |
|                 | *5^th^ Percentile*      | *5^th^ Percentile*       |
|                 |                         |                          |
|                 | 25^th^ Percentile       | 25^th^ Percentile        |
|                 |                         |                          |
|                 | **Median**              | **Median**               |
|                 |                         |                          |
|                 | *75^th^ Percentile*     | *75^th^ Percentile*      |
|                 |                         |                          |
|                 | 95^th^ Percentile       | 95^th^ Percentile        |
|                 |                         |                          |
|                 | **Geometric Mean**      | **Geometric Mean**       |
|                 |                         |                          |
|                 | *95% Confid. Limits*    | *95% Confid. Limits*     |
+-----------------+-------------------------+--------------------------+
| Bare floors^b^  | *52*                    | *36*                     |
|                 |                         |                          |
| (36 LHR+W       | 154                     | 114                      |
| units; 249 Balt |                         |                          |
| HUD units)      | **440**                 | **289**                  |
|                 |                         |                          |
|                 | *2,296*                 | *629*                    |
|                 |                         |                          |
|                 | 72,761                  | 1,928                    |
|                 |                         |                          |
|                 | **646**                 | **270**                  |
|                 |                         |                          |
|                 | *(319; 1,305)*          | *(231; 317)*             |
+-----------------+-------------------------+--------------------------+
| Interior window | *122*                   | *254*                    |
| sills^b^        |                         |                          |
|                 | 772                     | 909                      |
| (36 LHR+W       |                         |                          |
| units)          | **1,987**               | **2,732**                |
|                 |                         |                          |
|                 | *8,797*                 | *7,142*                  |
|                 |                         |                          |
|                 | 363,045                 | 30,498                   |
|                 |                         |                          |
|                 | **3,498**               | **2,670**                |
|                 |                         |                          |
|                 | *(1,605; 7,622)*        | *(2,222; 3,209)*         |
+-----------------+-------------------------+--------------------------+
| Window          | *381*                   | *136*                    |
| troughs^b^      |                         |                          |
|                 | 2,039                   | 1,300                    |
| (36 LHR+W       |                         |                          |
| units)          | **17,083**              | **3,909**                |
|                 |                         |                          |
|                 | *131,591*               | *14,263*                 |
|                 |                         |                          |
|                 | 547,652                 | 75,911                   |
|                 |                         |                          |
|                 | **17,107**              | **4,114**                |
|                 |                         |                          |
|                 | *(8,079; 36,222)*       | *(3,253; 5,204)*         |
+-----------------+-------------------------+--------------------------+

Source: Form 04B

^a^Only two LHR units had Phase III single surface samples collected;
therefore, no pre-intervention single surface results are presented for
LHR units.

^b^ Baltimore HUD unit data are from Baltimore Round One housing units
enrolled in the National Evaluation of HUD's Lead Hazard Control Grant
Program. Baltimore HUD unit data are for units that were vacant at Phase
I. Both interior floor and entry floor data are included.

^c^Based on Wilcoxon rank sum testing, pre-intervention median single
surface dust lead loadings for floors were marginally significant
(p=0.045), sills were not significantly different(p=0.969) and troughs
were significantly different (p=0.001) from those for Baltimore HUD
units.

Median pre-intervention single surface dust lead loadings on bare floors
and troughs in LHR+W units were greater than those in Baltimore HUD
units, while those on sills in LHR+W units were less than those in
Baltimore HUD units. Looking at other percentile values, it generally
appears that LHR+W units had greater baseline dust lead loadings than
did Baltimore HUD units, implying that LHR+W units were in worse
condition before treatment. However, Wilcoxon rank sum testing indicates
that pre-intervention median single surface dust lead loadings for
floors were marginally significantly different (p-value=0.045), those
for sills were not significantly different (p-value=0.969), and those
for troughs were significantly different (p-value=0.001) from those in
Baltimore HUD units.

A.  **One-Year Post-Intervention *Composite* and *Single Surface* Dust
    Sampling Results**

A complete listing of one-year post-intervention composite and single
surface dust sample results is provided in Appendices E and F,
respectively.

1.  ***Summary of One-Year Post-Intervention Composite Dust Sampling
    Results***

During one-year post-intervention, composite dust samples were taken
from bare floors, interior window sills, window troughs and, when
necessary, carpeted floors in all enrolled LHR and LHR+W units. Because
very few one-year post-intervention units had carpeted floors, sample
results for carpeted floors were excluded from this report. A Wilcoxon
rank sum test was used to test the equality of the median dust lead
loadings for the assigned treatment group (i.e., LHR versus LHR+W
units). Differences in median one-year post-intervention dust lead
loadings between the two groups had to be accounted for before the
continued effectiveness of the prescribed lead hazard reduction
treatments could be fully evaluated.

In both LHR and LHR+W units, one-year post-intervention median composite
dust lead loadings for bare floors were substantially less than the
floor clearance standard of 100 µg/ft^2^; however, 11% of LHR units and
6% of LHR+W units had at least one composite bare floor result above 100
µg/ft^2^. One-year post-intervention median window sill composite
results for both treatment groups were less than 500 µg/ft^2^; however,
47% of LHR units and 11% of LHR+W units had composite sill results above
this level. Median loadings for LHR units were three times higher than
those for LHR+W units. For troughs, one-year post-intervention median
composite dust lead loadings in LHR+W units were also less than the
clearance standard of 800 µg/ft^2^; however, the LHR median trough
result of 1,074 µg/ft^2^ exceeded this clearance standard. Over half
(58%) of LHR units but only 16% of LHR+W units had one-year
post-intervention trough composite results above 800 µg/ft^2^. For the
window surface types, the median one-year post-intervention composite
dust lead loadings in the LHR units substantially exceeded those for the
LHR+W units. Based on Wilcoxon rank sum tests, these differences were
significant for sills and troughs

(p=0.0052 and 0.0025, respectively) but not for bare floors (p=1.0; see
Table 35 and Figure 10 on page 66).

**Table 35: One-Year Post-Intervention *Composite* Sample Dust Lead
Loadings**

+------------------+-------------------------+-------------------------+
| **Surface Type** | **[LHR Dust Lead        | **[LHR+W Dust Lead      |
|                  | Loading                 | Loading                 |
|                  | (μ                      | (μ                      |
|                  | g/ft^2^)]{.underline}** | g/ft^2^)]{.underline}** |
|                  |                         |                         |
|                  | *5^th^ Percentile*      | *5^th^ Percentile*      |
|                  |                         |                         |
|                  | 25^th^ Percentile       | 25^th^ Percentile       |
|                  |                         |                         |
|                  | **Median**              | **Median**              |
|                  |                         |                         |
|                  | *75^th^ Percentile*     | *75^th^ Percentile*     |
|                  |                         |                         |
|                  | 95^th^ Percentile       | 95^th^ Percentile       |
|                  |                         |                         |
|                  | **Geometric Mean**      | **Geometric Mean**      |
|                  |                         |                         |
|                  | *95% Confid. Limits*    | *95% Confid. Limits*    |
+------------------+-------------------------+-------------------------+
| Bare floors^a,b^ | *2*                     | *2*                     |
|                  |                         |                         |
| (35 LHR units,   | 7                       | 11                      |
|                  |                         |                         |
| 33 LHR+W units)  | **22**                  | **20**                  |
|                  |                         |                         |
|                  | *75*                    | *38*                    |
|                  |                         |                         |
|                  | 203                     | 250                     |
|                  |                         |                         |
|                  | **23**                  | **23**                  |
|                  |                         |                         |
|                  | *(14; 38)*              | *(15; 36)*              |
+------------------+-------------------------+-------------------------+
| Interior window  | *1*                     | *9*                     |
| sills^a,b^       |                         |                         |
|                  | 85                      | 29                      |
| (36 LHR units,   |                         |                         |
|                  | **449**                 | **121**                 |
| 37 LHR+W units)  |                         |                         |
|                  | *1,045*                 | *239*                   |
|                  |                         |                         |
|                  | 8,466                   | 1,666                   |
|                  |                         |                         |
|                  | **252**                 | **90**                  |
|                  |                         |                         |
|                  | *(99; 640)*             | *(56; 145)*             |
+------------------+-------------------------+-------------------------+
| Window           | *2*                     | *22*                    |
| troughs^a,b^     |                         |                         |
|                  | 170                     | 118                     |
| (35 LHR units,   |                         |                         |
|                  | **1,074**               | **247**                 |
| 37 LHR+W units)  |                         |                         |
|                  | *11,550*                | *510*                   |
|                  |                         |                         |
|                  | 56,707                  | 1,731                   |
|                  |                         |                         |
|                  | **1,061**               | **242**                 |
|                  |                         |                         |
|                  | *(403; 2,795)*          | *(160; 367)*            |
+------------------+-------------------------+-------------------------+

Source: Form 04A, Phase III

^a^Approximately 85% of bare floor composites, interior window sill
composites, and window trough composites were comprised of 4
sub-samples; the rest were comprised of either 2 or 3 sub-samples.

^b^ Based on Wilcoxon rank sum tests, median one year post-intervention
dust lead loadings for sills and troughs were significantly associated
with assigned treatment group (p=0.0052 and 0.0025, respectively) but
not for bare floors (p=1.0).

**Figure 10: Pre- and One-Year Post-Intervention *Composite* Sample Dust
Lead Loading Box Plot**

![](media/image11.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

2.  ***Change in Composite Results from Pre to One-Year
    Post-Intervention***

Given that all visual assessment "failures" found at immediate
post-intervention were corrected upon discovery and that all immediate
post-intervention samples were collected prior to these corrections, it
is not appropriate to compare immediate post-intervention dust lead
loadings with those measured at one-year post-intervention. However,
comparison of one-year post-intervention results with pre-intervention
results aids in evaluating treatment effectiveness one year after
intervention.

Large median percent decreases and median µg/ft^2^ decreases were
observed when measuring the change from pre to one-year
post-intervention for composite samples taken from bare floors, window
sills and window troughs (see Tables 36 and 37, and Figure 10). Results
indicate that at one-year post-intervention, composite dust lead
loadings on bare floors, sills and troughs in both treatment groups
generally remained well below pre-intervention levels in both treatment
groups. Based on Wilcoxon rank sum testing, the association between the
median percent reduction in median composite dust lead loadings and the
assigned treatment group was significant for window sills (p\<0.0001)
and troughs (p=0.0001) but not for bare floors (p=0.2270).

**Table 36: Percent Reduction in Pre- to One-Year Post-Intervention
*Composite* Dust Lead Loadings**

+--------------------------------+-----------------+------------------+
| **Surface Type and             | **LHR Units**   | **LHR+W Units**  |
| Statistic-Composite Dust       |                 |                  |
| Samples**                      | **Pre to 1-Yr   | **Pre to 1-Yr    |
|                                | Po              | P                |
|                                | st-Intervention | ost-Intervention |
|                                | Percent         | Percent Change** |
|                                | Change**        |                  |
+--------------------------------+-----------------+------------------+
| [Bare floors (34 LHR, 32       | *53*            | *76*             |
| LHR+W)^a^]{.underline}:        |                 |                  |
|                                | **82**          | **94**           |
| *25^th^ Percentile Percent     |                 |                  |
| Reduction*                     | 95              | 98               |
|                                |                 |                  |
| **Median Percent Reduction**   |                 |                  |
|                                |                 |                  |
| 75^th^ Percentile Percent      |                 |                  |
| Reduction                      |                 |                  |
+--------------------------------+-----------------+------------------+
| [Interior window sills (35     | *-45            | *94*             |
| LHR, 37 LHR+W^a^]{.underline}  | (increase)*     |                  |
|                                |                 | **97**           |
| *25^th^ Percentile Percent     | **82**          |                  |
| Reduction*                     |                 | 99               |
|                                | 96              |                  |
| **Median Percent Reduction**   |                 |                  |
|                                |                 |                  |
| 75^th^ Percentile Percent      |                 |                  |
| Reduction                      |                 |                  |
+--------------------------------+-----------------+------------------+
| [Window troughs (34 LHR, 37    | *4*             | *93*             |
| LHR+W)^a^]{.underline}         |                 |                  |
|                                | **89**          | **98**           |
| *25^th^ Percentile Percent     |                 |                  |
| Reduction*                     | 96              | \>99             |
|                                |                 |                  |
| **Median Percent Reduction**   |                 |                  |
|                                |                 |                  |
| 75^th^ Percentile Percent      |                 |                  |
| Reduction                      |                 |                  |
+--------------------------------+-----------------+------------------+

Source: Form 04A

^a^Based on Wilcoxon rank sum tests, although changes in median bare
floor dust lead loadings were not significantly associated with assigned
treatment group (p=0.2246), changes in median sill and trough loadings
were (p\<0.0001 and p=0.0001, respectively).

Based on Wilcoxon rank sum testing, the association between the absolute
reduction in median composite dust lead loadings and the assigned
treatment group was significant for window sills (p=0.0185) and troughs
(p=0.0047) but not for bare floors (p=0.1600) (see Table 37).

**Table 37: Micrograms Per Square Foot Reduction in Pre- to One-Year
Post-Intervention *Composite* Dust Lead Loadings**

+----------------------------------+-----------------+----------------+
| **Surface Type and               | **LHR Units Pre | **LHR+W Units  |
| Statistic-Composite Dust         | to**            | Pre to 1-Yr    |
| Samples**                        |                 | Post-          |
|                                  | **1-Yr          | Intervention** |
|                                  | Po              |                |
|                                  | st-Intervention | **µg/ft^2^     |
|                                  | µg/ft^2^        | Reduction**    |
|                                  | Reduction**     |                |
+----------------------------------+-----------------+----------------+
| [Bare floors (34 LHR, 32         | *35*            | *71*           |
| LHR+W)^a^]{.underline}:          |                 |                |
|                                  | **87**          | **335**        |
| *25^th^ Percentile μg/ft^2^      |                 |                |
| Reduction*                       | 486             | 804            |
|                                  |                 |                |
| **Median μg/ft^2^ Reduction**    |                 |                |
|                                  |                 |                |
| 75^th^ Percentile μg/ft^2^       |                 |                |
| Reduction                        |                 |                |
+----------------------------------+-----------------+----------------+
| [Interior window sills (35 LHR,  | *-25            | *693*          |
| 37 LHR+W)^a^]{.underline}:       | (increase)*     |                |
|                                  |                 | **2,803**      |
| *25^th^ Percentile μg/ft^2^      | **713**         |                |
| Reduction*                       |                 | 9,771          |
|                                  | 6,458           |                |
| **Median μg/ft^2^ Reduction**    |                 |                |
|                                  |                 |                |
| 75^th^ Percentile μg/ft^2^       |                 |                |
| Reduction                        |                 |                |
+----------------------------------+-----------------+----------------+
| [Window troughs (34 LHR, 37      | *2*             | *4,356*        |
| LHR+W)^a^]{.underline}:          |                 |                |
|                                  | **4,507**       | **12,014**     |
| *25^th^ Percentile μg/ft^2^      |                 |                |
| Reduction*                       | 23,385          | 128,550        |
|                                  |                 |                |
| **Median μg/ft^2^ Reduction**    |                 |                |
|                                  |                 |                |
| 75^th^ Percentile μg/ft^2^       |                 |                |
| Reduction                        |                 |                |
+----------------------------------+-----------------+----------------+

Source: Form 04A

^a^Based on Wilcoxon rank sum tests, although changes in median bare
floor dust lead loadings were not significantly associated with assigned
treatment group (p=0.1600), changes in sill and trough loadings were
(p=0.0185 and p=0.0047, respectively).

3.  ***Units Having an Increase in Composite Dust Lead Loadings from
    Pre- to One-Year Post-Intervention***

Despite the significant median decreases in composite dust lead loadings
between pre- and one-year post-intervention, data in Table 38 show that
some units experienced increases in dust lead loadings between these two
phases. Indeed, the findings show that approximately a quarter of LHR
units had an increase in composite dust lead loadings on sills and
troughs during this time period. The percentages of LHR+W units that
underwent an increase were lower than those of LHR units.

Table 38: Number and Percent of Units Having an Increase in *Composite*
Dust Lead

Loadings from Pre- to One-Year Post-Intervention

+--------------------+-----------------------+-------------------------+
| **Surface Type and | # LHR                 | **LHR+W**               |
| Sample Type**      |                       |                         |
+--------------------+-----------------------+-------------------------+
| [Bare              | 3/34 (9%)             | 1/32 (3%)               |
| Fl                 |                       |                         |
| oors]{.underline}: |                       |                         |
+--------------------+-----------------------+-------------------------+
| [Interior window   | 10/35 (28%)           | 1/37 (3%)               |
| s                  |                       |                         |
| ills]{.underline}: |                       |                         |
+--------------------+-----------------------+-------------------------+
| [Window            | 8/34 (24%)            | 0/37 (0%)               |
| Tro                |                       |                         |
| ughs]{.underline}: |                       |                         |
+--------------------+-----------------------+-------------------------+

4.  ***Summary of One-Year Post-Intervention Single Surface Results***

As discussed in Section II.E, single surface samples were collected in a
subset of LHR units. However, due to budget constraints, LAAP ceased
collecting such samples in LHR units during one-year and two-years
post-intervention but continued to collect them in LHR+W units. Samples
were collected in the same locations of LHR+W units that were sampled
during the first two study phases (see Table 39 on page 70 and Figure 11
on page 71). There were too few carpeted floor samples to allow full
characterization of this surface type. The one-year post-intervention
single surface dust sample results for LHR+W units were compared with
one-year post-intervention single surface dust data obtained from
Baltimore City housing units enrolled in the National Evaluation of
HUD\'s Lead Hazard Control Grant program. These units underwent lead
reduction control interventions that were generally similar to those
received by the LHR+W units during this study.

Median single surface one-year post-intervention dust lead loading
results for bare floors and window troughs in LHR+W units were less than
those in Baltimore HUD Evaluation units, while the median single surface
dust lead loading for sills in LHR+W units was slightly higher than that
of Baltimore HUD units. Based on Wilcoxon rank sum tests, these
differences were significant for bare floors (p\<0.0001) and troughs
(p=0.0017) but not for sills (p=0.545). These results are somewhat
surprising given that the HUD Round I units generally underwent similar
lead hazard control treatments as the LHR+W units and given that the
LHR+W units generally had higher pre-intervention dust lead loadings
than the Baltimore Round I units.

5.  ***Change in Single Surface Results from Pre- to One-Year
    Post-Intervention***

Similar to the composite dust lead loading results, substantial median
percent decreases and median µg/ft^2^ decreases in single surface dust
lead loadings were observed for floors, sills and window troughs between
pre- and one-year post-intervention (see Tables 40 and 41 on pages 72
and 73). Based on Wilcoxon rank sum tests, median percent reductions for
bare floors and troughs in LHR+W units were significantly different from
those for Baltimore Round I HUD Evaluation units (p\<0.0001 for both
surface types) but were not significantly different for window sills
(p=0.813). Again, these results are surprising given that LHR+W units
appeared to have larger pre-intervention dust lead loadings and were
treated in a similar manner to HUD Round I units.

**Table 39: One-Year Post-Intervention *Single Surface* Sample Dust Lead
Loadings^a^**

+-----------------+----------------------+----------------------------+
| **Surface       | **[LHR+W Dust Lead   | **[Baltimore HUD Units^b^  |
| Type**          | Loading              | (µg/ft^2^)]{.underline}**  |
|                 | (μg/f                |                            |
|                 | t^2^]{.underline})** | *5^th^ Percentile*         |
|                 |                      |                            |
|                 | *5^th^ Percentile*   | 25^th^ Percentile          |
|                 |                      |                            |
|                 | 25^th^ Percentile    | **Median**                 |
|                 |                      |                            |
|                 | **Median**           | *75^th^ Percentile*        |
|                 |                      |                            |
|                 | *75^th^ Percentile*  | 95^th^ Percentile          |
|                 |                      |                            |
|                 | 95^th^ Percentile    | **Geometric Mean**         |
|                 |                      |                            |
|                 | **Geometric Mean**   | *95% Confid. Limits*       |
|                 |                      |                            |
|                 | *95% Confid. Limits* |                            |
+-----------------+----------------------+----------------------------+
| Bare floors^c^  | *4*                  | *5*                        |
|                 |                      |                            |
| (36 LHR+W       | 11                   | 21                         |
| units)          |                      |                            |
|                 | **20**               | **44**                     |
| (249 Balt Rd I  |                      |                            |
| units)          | *37*                 | *90*                       |
|                 |                      |                            |
|                 | 141                  | 319                        |
|                 |                      |                            |
|                 | **20**               | **42**                     |
|                 |                      |                            |
|                 | *(15; 28)*           | *(36; 48)*                 |
+-----------------+----------------------+----------------------------+
| Interior window | *10*                 | *4*                        |
| sills^c^        |                      |                            |
|                 | 23                   | 18                         |
| (36 LHR+W       |                      |                            |
| units)          | **64**               | **58**                     |
|                 |                      |                            |
| (237 Balt Rd I) | *152*                | *139*                      |
|                 |                      |                            |
|                 | 3,628                | 505                        |
|                 |                      |                            |
|                 | **69**               | **50**                     |
|                 |                      |                            |
|                 | *(41; 118)*          | *(42; 61)*                 |
+-----------------+----------------------+----------------------------+
| Window          | *18*                 | *51*                       |
| troughs^c^      |                      |                            |
|                 | 78                   | 143                        |
| (36 LHR+W       |                      |                            |
| units)          | **211**              | **421**                    |
|                 |                      |                            |
| (242 Balt Rd I) | *391*                | *917*                      |
|                 |                      |                            |
|                 | 1,058                | 2,233                      |
|                 |                      |                            |
|                 | **185**              | **376**                    |
|                 |                      |                            |
|                 | *(122; 282)*         | *(321; 441)*               |
+-----------------+----------------------+----------------------------+

Source: Form 04B

^a^Only two LHR units had Phase III single surface samples collected;
therefore, no comparison with pre-intervention single surface results is
possible.

^b^Baltimore HUD unit data are from Baltimore Round One housing units
enrolled in the National Evaluation of HUD's Lead Hazard Control Grant
Program. Units were vacant at pre-intervention. For floors, Baltimore
HUD unit data include both interior floor and entry floor data.

^c^Based on Wilcoxon rank sum tests, LHR+W median dust lead loadings for
floors and troughs were significantly different from those of Baltimore
Round I units (p\<0.0001 for floors and 0.0017 for troughs) but not for
sills (p=0.545).

**Figure 11: Pre- and One-Year Post-Intervention *Single Surface* Sample
Dust Lead Loading Box Plot**

![](media/image12.wmf)

Note: Bottom whisker=5^th^ percentile; top whisker=95^th^ percentile;
box=25^th^ & 75^th^ percentile; circle=median; triangle = geometric
mean.

**Table 40: Percent Reduction in Pre to One-Year Post-Intervention
*Single Surface* Dust Lead Loadings^a^**

+-----------------------------------+---------------+------------------+
| **Surface Type and                | **LHR+W       | **Baltimore HUD  |
| Statistic-Single Surface Dust     | Units**       | Units^a^ Pre to  |
| Samples**                         |               | 1-Yr Post-       |
|                                   | **Pre to 1-Yr | Intervention     |
|                                   | Post          | Percent          |
|                                   | -Intervention | Reduction**      |
|                                   | Percent       |                  |
|                                   | Reduction**   |                  |
+-----------------------------------+---------------+------------------+
| [Bare floors (36 LHR+W; 249 Balt  | *88%*         | *63%*            |
| HUD)^b^]{.underline}:             |               |                  |
|                                   | **96%**       | **84%**          |
| *25^th^ Percentile Percent        |               |                  |
| Reduction*                        | 99%           | 94%              |
|                                   |               |                  |
| **Median Percent Reduction**      |               |                  |
|                                   |               |                  |
| 75^th^ Percentile Percent         |               |                  |
| Reduction                         |               |                  |
+-----------------------------------+---------------+------------------+
| [Interior window sills (36 LHR+W; | *75%*         | *93%*            |
| 237 Balt HUD)^b^]{.underline}:    |               |                  |
|                                   | **97%**       | **98%**          |
| *25^th^ Percentile Percent        |               |                  |
| Reduction*                        | \>99%         | 99%              |
|                                   |               |                  |
| **Median Percent Reduction**      |               |                  |
|                                   |               |                  |
| 75^th^ Percentile Percent         |               |                  |
| Reduction                         |               |                  |
+-----------------------------------+---------------+------------------+
| [Window troughs (36 LHR+W; 242    | *93%*         | *60%*            |
| Balt HUD)^b^]{.underline}:        |               |                  |
|                                   | **99%**       | **90%**          |
| *25^th^ Percentile Percent        |               |                  |
| Reduction*                        | \>99%         | 98%              |
|                                   |               |                  |
| **Median Percent Reduction**      |               |                  |
|                                   |               |                  |
| 75^th^ Percentile Percent         |               |                  |
| Reduction                         |               |                  |
+-----------------------------------+---------------+------------------+

Source: Form 04B

^a^Only two LHR units had Phase III single surface samples collected;
therefore, no comparison with pre-intervention single surface results is
possible.

^b^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead-Based Paint Grant Program and were compiled using
pre-intervention and one-year post-intervention data and were from units
that were vacant at pre-intervention. For floors, Baltimore HUD unit
data include both interior floor and entry floor data.

^c^Based on Wilcoxon rank sum tests, LHR+W units had significantly
larger median percent decreases in single surface dust lead loadings for
bare floors (p\<0.0001) and troughs (p\<0.0001) than did Baltimore Round
I units; however, median percent decreases in sill loadings were not
significantly different (p=0.813).

**Table 41: Micrograms Per Square Foot Reductions in Pre- to One-Year
Post-Intervention *Single Surface* Dust Lead Loadings^a^**

+-----------------------------------+----------------+-----------------+
| **Surface Type and                | **LHR+W        | **Baltimore HUD |
| Statistic-Single Surface Dust     | Units**        | Units Pre to    |
| Samples**                         |                | 1-Yr Post-      |
|                                   | **Pre to 1-Yr  | Intervention    |
|                                   | Pos            | µg/ft^2^        |
|                                   | t-Intervention | Reduction^b^**  |
|                                   | µg/ft^2^       |                 |
|                                   | Reduction**    |                 |
+-----------------------------------+----------------+-----------------+
| [Bare floors (36 LHR+W; 249 Balt  | *148 µg/ft^2^* | *57 µg/ft^2^*   |
| HUD)]{.underline}:                |                |                 |
|                                   | **420          | **220           |
| *25^th^ Percentile μg/ft^2^       | µg/ft^2^**     | µg/ft^2^**      |
| Reduction*                        |                |                 |
|                                   | 2,396 µg/ft^2^ | 557 µg/ft^2^    |
| **Median μg/ft^2^ Reduction**     |                |                 |
|                                   |                |                 |
| 75^th^ Percentile μg/ft^2^        |                |                 |
| Reduction                         |                |                 |
+-----------------------------------+----------------+-----------------+
| [Interior window sills (36 LHR+W; | *540 µg/ft^2^* | *860 µg/ft^2^*  |
| 237 Balt HUD)]{.underline}:       |                |                 |
|                                   | **1,875        | **2,617         |
| *25^th^ Percentile μg/ft^2^       | µg/ft^2^**     | µg/ft^2^**      |
| Reduction*                        |                |                 |
|                                   | 10,322         | 7,114 µg/ft^2^  |
| **Median μg/ft^2^ Reduction**     | µg/ft^2^       |                 |
|                                   |                |                 |
| 75^th^ Percentile μg/ft^2^        |                |                 |
| Reduction                         |                |                 |
+-----------------------------------+----------------+-----------------+
| [Window troughs (36 LHR+W; 242    | *1,758         | *800 µg/ft^2^*  |
| Balt HUD))]{.underline}:          | µg/ft^2^*      |                 |
|                                   |                | **3,308         |
| *25^th^ Percentile μg/ft^2^       | **16,338       | µg/ft^2^**      |
| Reduction*                        | µg/ft^2^**     |                 |
|                                   |                | 13,283 µg/ft^2^ |
| **Median μg/ft^2^ Reduction**     | 135,512        |                 |
|                                   | µg/ft^2^       |                 |
| 75^th^ Percentile μg/ft^2^        |                |                 |
| Reduction                         |                |                 |
+-----------------------------------+----------------+-----------------+

Source: Form 04B

^a^Only two LHR units had Phase III single surface samples collected;
therefore, no comparison with pre-intervention single surface results is
possible.

^b^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead Hazard Control Grant Program and were compiled using
initial and Phase 4 data (one-year post-intervention) for units that
were vacant at pre-intervention. For floors, Baltimore HUD unit data
include both interior floor and entry floor data.

6.  ***Units Having an Increase in Single Surface Dust Lead Loadings
    from Pre- to One-Year Post-Intervention***

Despite the substantial median decreases in dust lead loadings between
pre and one-year post-intervention, data in Table 42 show that a few
units experienced increases in single surface dust lead loadings between
these two phases. The percentages of LHR+W units that underwent an
increase on floors and troughs were lower than those of Baltimore HUD
units, while the sill percentage was slightly higher than that of
Baltimore HUD units.

Table 42: Number and Percent of Units Having an Increase in *Single
Surface* Dust

Lead Loadings from Pre- to One-Year Post-Intervention

  ----------------------- --------------------- ----------------------------
  **Surface Type and      **LHR+W**             **Baltimore HUD Units**
  Sample Type**                                 

  [Bare                   1/36 (3%)             25/249 (10%)
  Floors]{.underline}:                          

  [Interior window        3/36 (8%)             2/237 (1%)
  sills]{.underline}:                           

  [Window                 2/36 (6%)             28/242 (12%)
  Troughs]{.underline}:                         
  ----------------------- --------------------- ----------------------------

7.  ***Comparison of One-Year Post-Intervention Results with Clearance
    Standards/Guidance***

Under the risk reduction treatment option of EA 6-8, enrolled LHR and
LHR+W units were required only to pass a visual inspection performed by
an independent visual inspector immediately after intervention was
complete. Collection of dust samples and comparison of such results to
clearance standards were not required during any phase. However, this
study considered clearance dust standards set by Maryland and by HUD/EPA
to assess the extent to which prescribed treatments continued to produce
dust results that were sufficient for safe occupancy of treated units
one year after treatments were complete. This comparison to clearance
standards is not required by EA 6-8 and was performed in this study for
research purposes only. Again, only LHR+W units are presented here
because one-year post-intervention single surface data were not
available for the vast majority of LHR units.

One year after interventions were completed, less than 20% of LHR+W
units had single surface dust lead loadings that exceeded clearance
standards for any surface type (see Table 43). At one-year
post-intervention, Baltimore HUD units had a higher percentage of bare
floors and window troughs that exceeded HUD clearance standards of 100
and 500 µg/ft^2^, respectively. Based on Chi-square testing, there is a
significant difference between the clearance exceedance rate for LHR+W
units versus Baltimore HUD units (p\<0.0001 for bare floors, p=0.016 for
troughs). LHR+W units had a higher percentage of units with window sills
above 500 µg/ft^2^; however, there was only a marginally significant
difference based on a Fisher's Exact Test (p=0.096). This is surprising
given the fact that LHR+W units generally had larger pre-intervention
dust lead loadings and treatments that were similar to those of
Baltimore HUD round I units. Visual assessment "failures" reported at
immediate post-intervention that were subsequently repaired may have
contributed to the relatively lower rates for LHR+W units.

**Table 43: Percentage of LHR+W Units with One-Year Post-Intervention
*Single Surface* Dust Lead Loadings Exceeding Clearance Standards^a^**

  ------------------- ------------ ------------ ------------------- ----------------
                      **Percent of                                  
                      Units within                                  
                      Specified                                     
                      Category**                                    

  **Surface Type:**   **Bare                    **Interior Window   **Window
                      Floors**                  Sills**             Troughs**

  **Std/Guidance:**   **100       **200       **500 µg/ft^2^**   **800
                      µg/ft^2^**   µg/ft^2^**                       µg/ft^2^**

  **LHR+W Units (36   5 (14%)      4 (11%)      6 (17%)             5 (14%)
  units)**                                                          

  **Baltimore HUD     143 (57%)    NA           25 (11%)            85 (35%)
  Units^b^ (249                                                     
  units)**                                                          
  ------------------- ------------ ------------ ------------------- ----------------

^a^Only two LHR units had Phase III single surface samples collected;
therefore, no comparison with clearance standards/guidance is possible.

^b^Baltimore HUD unit data are Round I data from the National Evaluation
of HUD's Lead Hazard Control Grant Program and were compiled using
initial and Phase 4 data (one-year post-intervention) for units that
were vacant at pre-intervention. For floors, Baltimore HUD unit data
include both interior floor and entry floor data.

# 

B.  **Results of One-Year Post-Intervention Visual Assessment**

At one-year post-intervention, LAAP inspectors performed another visual
assessment to evaluate the continued effectiveness of treatments one
year after intervention. A complete listing of one-year
post-intervention visual assessment "failures" is provided in Appendix
G. Table 44 presents the distribution of one-year post-intervention
"failures" per unit. There were no units having more than five
"failures." LAAP inspectors found that all 36 LHR units and 34 of the 37
(92%) LHR+W units had at least one visual assessment "failure" one year
after interventions had been completed. This equates to an overall
one-year post-intervention visual assessment "failure" rate of 96% for
the 73 one-year post-intervention units. Landlords were informed of
these "failures" and were provided with recommendations to fix the
problems.

Overall, the likelihood of LHR units having one or more one-year
post-intervention "failures" was almost the same as that of the LHR+W
units. However, t-tests indicate that the mean number of "failures" per
unit for LHR units (2.4) was marginally significantly different from and
higher than that for LHR+W units (1.9) (p=0.0482). If only "failure"
types applicable to both treatment groups are considered, LHR units have
a slightly lower mean number of one-year post-intervention "failures"
per unit (2.2), while the mean for LHR+W units remains almost the same
(1.8); these two means are not significantly different from each other
based on t-tests (p=0.1246).

**Table 44: Number of One-Year Post-Intervention Visual Assessment
"Failures" Per Unit**

+-----------------------------------+----------+----------+----------+
| **Number of One-Year              | **LHR**  | *        | **All    |
| Post-Intervention Visual          |          | *LHR+W** | Units**  |
| Assessment "Failures" Per         | **\#     |          |          |
| Unit^a^**                         | Units**  | **\#     | **\#     |
|                                   |          | Units**  | Units**  |
| **(36 LHR units, 37 LHR+W         | **(%     |          |          |
| units)**                          | Units)** | **(%     | **(%     |
|                                   |          | Units)** | Units)** |
+-----------------------------------+----------+----------+----------+
| "0" 1-yr post-int visual          | 0        | 3 (8%)   | 3 (4%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "1" 1-yr post-int visual          | 8 (22%)  | 13 (35%) | 21 (29%) |
| assessment "failure"              |          |          |          |
+-----------------------------------+----------+----------+----------+
| "2" 1-yr post-int visual          | 12 (33%) | 9 (24%)  | 21 (29%) |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "3" 1-yr post-int visual          | 11 (31%) | 9 (24%)  | 20 (27%) |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "4" 1-yr post-int visual          | 3 (8%)   | 3 (8%)   | 6 (8%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+
| "5" 1-yr post-int visual          | 2 (6%)   | 0        | 2 (3%)   |
| assessment "failures"             |          |          |          |
+-----------------------------------+----------+----------+----------+

Source: Form 05

^a^The mean number of "failures" per unit for LHR units (2.4) was
marginally significantly different from that for LHR+W units (1.9)
(p=0.0482).

1.  ***Types of One-Year Post-Intervention "Failures"***

The most common visual assessment "failure" at one-year
post-intervention was that not all paint was intact after completion of
the lead hazard reduction treatments (i.e., chipping, flaking and/or
peeling paint remained) (see Table 45 on page 76), with over 90% of all
units (94% of LHR units and 92% of LHR+W units) exhibiting this type of
"failure." Over 40% of units (50% of LHR units and 32% of LHR+W units)
had doors with painted surfaces that continued to rub together or bind.
Approximately one-third of all units (33% of LHR units and 24% of LHR+W
units) had visible paint chips and debris in various locations, and over
25% (31% of LHR units and 24% of LHR+W units) had some kitchen and
bathroom floors whose water-resistant coverings were not intact. Other
types of one-year post-intervention visual assessment "failures" were
much less prevalent. Although LHR units had a higher percentage of units
with each of the above-mentioned types of "failures," none of the
"failure" types was significantly associated with assigned treatment
group based on Chi-square tests.

**Table 45: One-Year Post-Intervention Visual Assessment "Failures"**

+-----------------------------------+-----------+----------+----------+
| **Type of One-Year                | **LHR**   | *        | **All    |
| Post-Intervention Visual          |           | *LHR+W** | Units**  |
| Assessment "Failures"^a^**        | **\#      |          |          |
|                                   | Units**   | **\#     | **\#     |
| **(36 LHR units, 37 LHR+W         |           | Units**  | Units**  |
| units)**                          | **(%      |          |          |
|                                   | Units)**  | **(%     | **(%     |
|                                   |           | Units)** | Units)** |
+-----------------------------------+-----------+----------+----------+
| Not all paint intact (chipping,   | 34 (94%)  | 34 (92%) | 68 (93%) |
| peeling or flaking paint remains) |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Visible structural defect that    | 1 (3%)    | 2 (5%)   | 3 (4%)   |
| could cause paint deterioration   |           |          |          |
| remains                           |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If sills stripped/repainted or    | 1 (3%)    | 0        | 1 (1%)   |
| replaced, not all treatments in   |           |          |          |
| place                             |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If sills encapsulated with vinyl, | 0         | 0        | 0        |
| metal, etc., not all material is  |           |          |          |
| properly attached^b^              |           |          |          |
+-----------------------------------+-----------+----------+----------+
| If troughs capped with vinyl,     | 5 (14%)   | NA^b^    | 5 (7)^c^ |
| metal, etc., not all material is  |           |          |          |
| properly attached^b^              |           |          |          |
+-----------------------------------+-----------+----------+----------+
| For windows, not all top sashes   | 0         | NA^b^    | 0        |
| are fixed in place                |           |          |          |
+-----------------------------------+-----------+----------+----------+
| For doors, painted surfaces rub   | 18 (50%)  | 12 (32%) | 30 (41%) |
| together                          |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Some bare floors are not smooth   | 5 (14%)   | 4 (11%)  | 9 (12%)  |
| and cleanable                     |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Not all kitchen and bathroom      | 11 (31%)  | 9 (24%)  | 20 (27%) |
| floors are overlaid with          |           |          |          |
| water-resistant coverings         |           |          |          |
+-----------------------------------+-----------+----------+----------+
| Visible paint chips or debris     | 12 (33%)  | 9 (24%)  | 21 (29%) |
| remains                           |           |          |          |
+-----------------------------------+-----------+----------+----------+

Source: Form 05

^a^Based on Chi-square tests, none of the listed types of visual
assessment "failures" were significantly associated with assigned
treatment group (p varied from 0.127 to 0.689).

^b^In LHR+W units, these treatments were not necessary by virtue of the
installation of new vinyl replacement windows with unpainted top sashes
and troughs.

^c^Value is understated due to the inapplicability of this treatment for
LHR+W units.

2.  ***Magnitude of One-Year Post-Intervention "Failures"***

The magnitude of the above "failures" was evaluated by reviewing notes
that LAAP inspectors recorded about the observed "failures" by room
location and "failure" type, the specific component or surface type that
"failed" in a given room, and their estimated measurement of each
"failure" in units of linear inches, square inches, linear feet, square
feet or "each."

The geometric means of "failures" presented in Table 46 on page 77 were
calculated by first summing, within a unit, all reports of a particular
"failure" type having the same measurement units (e.g., square feet),
then calculating the geometric mean across dwelling units. These data
indicate that problems recorded by LAAP inspectors one year after
treatment were easily observed (see Table 46). For example, LAAP
inspectors reported that a geometric mean of 1 ft^2^ of paint in both
LHR and LHR+W units was not intact at one-year post-intervention. This
type of "failure" was reported 61 times in 23 LHR units and 61 times in
25 LHR+W units, indicating a widespread occurrence. Painted door
surfaces rubbing together was also noted often, reported 22 times in 18
LHR units and 16 times in 12 LHR+W units. The status of floors at
one-year post-intervention is also noteworthy, with a geometric mean of
4 ft^2^ of flooring in both LHR and LHR+W units being not smooth and
cleanable one year after treatments. A geometric mean of 2 ft^2^ of
kitchen and bathroom floors in LHR and LHR+W units had tile or coverings
that were damaged, cracked, or missing. These results are somewhat
surprising considering that these types of problems were reportedly
corrected during the lead hazard reduction intervention or were
corrected when LAAP inspectors discovered such problems during the
visual inspection conducted immediately after treatments were completed.

# Table 46: Reporting Frequency of Specified Types of One-Year Post-Intervention Visual Assessment "Failures"

+------------+------+-------+-------+-------+-------+-------+-------+
|            |      | **    |       |       | **LH  |       |       |
|            |      | LHR** |       |       | R+W** |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
| *          | **   | **\#  | *     | *     | **\#  | *     | *     |
| *"Failure" | Unit | Units | *Repo | *"Fai | Units | *Repo | *"Fai |
| Type**     | of   | with  | rting | lure" | with  | rting | lure" |
|            | M    | Spec  | Freq. | Ma    | Spec  | Freq. | Ma    |
| **(36 LHR, | easu | ified | of    | gnit. | ified | of    | gnit. |
| 37         | re** | "Fai  | "Fai  | (     | "Fai  | "Fai  | (     |
| LHR+W)**   |      | lure" | lure" | geom. | lure" | lure" | geom. |
|            |      | Rp    | Type  | Mean  | Rp    | Type  | mean  |
|            |      | t'd** | at**  | & 95% | t'd** | at**  | & 95% |
|            |      |       |       | Conf  |       |       | Conf  |
|            |      |       | **Ph  | Limi  |       | **Ph  | Limi  |
|            |      |       | 2**   | ts)** |       | 2**   | ts)** |
+------------+------+-------+-------+-------+-------+-------+-------+
| Not all    | E    | 3     | 3     | 1 (1, | 3     | 3     | 2     |
| paint      | A^a^ |       |       | 3)    |       |       | (N    |
| intact     |      |       |       |       |       |       | A)^c^ |
|            |      |       |       |       |       |       |       |
| (34 LHR,   |      |       |       |       |       |       |       |
| 34 LHR+W)  |      |       |       |       |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
|            | LF   | 32    | 94    | 2 (1, | 26    | 82    | 2 (1, |
|            |      |       |       | 3)    |       |       | 3)    |
+------------+------+-------+-------+-------+-------+-------+-------+
|            | SF   | 23    | 61    | 1     | 25    | 61    | 1     |
|            |      |       |       | (0.2, |       |       | (0.2, |
|            |      |       |       | 2)    |       |       | 2)    |
+------------+------+-------+-------+-------+-------+-------+-------+
| For doors, | E    | 18    | 22    | 1 (1, | 12    | 16    | 1 (1, |
| painted    | A^a^ |       |       | 1)    |       |       | 2)    |
| surfaces   |      |       |       |       |       |       |       |
| continued  |      |       |       |       |       |       |       |
| to rub     |      |       |       |       |       |       |       |
| together   |      |       |       |       |       |       |       |
| (18 LHR,   |      |       |       |       |       |       |       |
| 12 LHR+W)  |      |       |       |       |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
| Some bare  | SF   | 5     | 10    | 4 (1, | 4     | 6     | 4     |
| floors not |      |       |       | 21)   |       |       | (N    |
| smooth &   |      |       |       |       |       |       | A)^c^ |
| cleanable  |      |       |       |       |       |       |       |
| (5 LHR, 4  |      |       |       |       |       |       |       |
| LHR+W)     |      |       |       |       |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
| Not all    | LF   | 0     | 13    | 0     | 2     | 3     | 2     |
| kitchen &  |      |       |       |       |       |       | (NA)  |
| bathroom   | SF   | 11    |       | 2 (2, | 8     | 9     |       |
| floors     |      |       |       | 3)    |       |       | 2 (1, |
| overlaid   |      |       |       |       |       |       | 5)    |
| with       |      |       |       |       |       |       |       |
| water      |      |       |       |       |       |       |       |
| -resistant |      |       |       |       |       |       |       |
| coverings  |      |       |       |       |       |       |       |
| (11 LHR, 9 |      |       |       |       |       |       |       |
| LHR+W)     |      |       |       |       |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
| Visible    | E    | 4     | 19    | 6 (4, | 3     | 10    | 5 (2, |
| paint      | A^b^ |       |       | 10)   |       |       | 13)   |
| chips or   |      |       |       |       |       |       |       |
| debris     |      |       |       |       |       |       |       |
| remains    |      |       |       |       |       |       |       |
| (12 LHR, 9 |      |       |       |       |       |       |       |
| LHR+W)     |      |       |       |       |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
|            | LF   | 1     | 2     | 8     | 0     | 0     | NA    |
|            |      |       |       | (NA)  |       |       |       |
+------------+------+-------+-------+-------+-------+-------+-------+
|            | SF   | 7     | 23    | 1     | 6     | 10    | 1     |
|            |      |       |       | (0.1, |       |       | (0.2, |
|            |      |       |       | 9)    |       |       | 4)    |
+------------+------+-------+-------+-------+-------+-------+-------+

EA=each; LF=linear foot; SF=square foot

^a^For these "failure" types, "each" denotes window components (e.g.,
upper sash, lower sash), door casings, or handrails in need of
re-painting. LF/SF values are not available for these occurrences.

^b^For this "failure" type, "each" usually denotes a window with debris
or chips in the well.

^c^No 95% confidence limits were calculated due to the small number of
units having this failure reported.

3.  ***Rooms with One-Year Post-Intervention "Failures"***

In general, three to six rooms per unit (mean 5 rooms for LHR units and
4 rooms for LHR+W units) had visual assessment "failures" at one-year
post-intervention (see Figure 12 on page 74). All LHR units had at least
one room with "failures," while 8% of LHR+W units had no rooms with
"failures." Although no LHR+W units had more than 9 rooms with
"failures," 2% of LHR units had 10 or more rooms with "failures."

**Figure 12: Percentage of Units Having Specified Number of Rooms Per
Unit with One-Year Post-Intervention Visual Assessment "Failures"**

![](media/image15.wmf)

In both LHR and LHR+W units, paint was not intact in an average of 3
rooms per unit (see Table 47 on page 79). For other types of "failures"
(e.g., painted doors rubbing, visible paint chips and debris present), a
given "failure" was generally reported for 1 room per unit.

**Table 47: Mean Number of Rooms Per Unit with Specified One-Year
Post-Intervention Visual Assessment "Failures" by Treatment Group^a^**

+----------------------------------+-----------------+-----------------+
| **Type of Post-Intervention      | **LHR**         | **LHR+W**       |
| Visual Assessment "Failures"**   |                 |                 |
|                                  | **Mean \#       | **Mean \#       |
| **(36 LHR units, 37 LHR+W        | Rooms**         | Rooms**         |
| units)**                         |                 |                 |
|                                  | **Per Unit**    | **per Unit**    |
|                                  |                 |                 |
|                                  | **(95% Conf.    | **(95% Conf.    |
|                                  | Int.)**         | Int.)**         |
+----------------------------------+-----------------+-----------------+
| Not all paint intact (chipping,  | 3.4             | 3.2             |
| peeling or flaking paint         |                 |                 |
| remains)                         | (2.8, 4.0)      | (2.6, 3.8)      |
+----------------------------------+-----------------+-----------------+
| Visible structural defect that   | 0               | 0.1             |
| could cause paint deterioration  |                 |                 |
| remains                          | (0, 0.1)        | (0, 0.2)        |
+----------------------------------+-----------------+-----------------+
| If sills stripped/repainted or   | 0               | 0               |
| replaced, not all treatments in  |                 |                 |
| place                            | (0, 0.1)        |                 |
+----------------------------------+-----------------+-----------------+
| If sills encapsulated with       | 0               | 0               |
| vinyl, metal, etc., not all      |                 |                 |
| material is property attached    |                 |                 |
+----------------------------------+-----------------+-----------------+
| If troughs capped with vinyl,    | 0.2             | NA^a^           |
| metal, etc., not all material is |                 |                 |
| properly attached                | (0, 0.3)        |                 |
+----------------------------------+-----------------+-----------------+
| For windows, not all top sashes  | 0               | NA^a^           |
| are fixed in place               |                 |                 |
+----------------------------------+-----------------+-----------------+
| For doors, painted surfaces      | 0.6             | 0.4             |
| continue to rub together         |                 |                 |
|                                  | (0.4, 0.9)      | (0.2, 0.6)      |
+----------------------------------+-----------------+-----------------+
| Some bare floors are not smooth  | 0.3             | 0.2             |
| and cleanable                    |                 |                 |
|                                  | (0.1, 0.5)      | (0, 0.3)        |
+----------------------------------+-----------------+-----------------+
| Not all kitchen and bathroom     | 0.4             | 0.3             |
| floors are overlaid with         |                 |                 |
| water-resistant coverings        | (0.2, 0.6)      | (0.1, 0.5)      |
+----------------------------------+-----------------+-----------------+
| Visible paint chips or debris    | 1.2             | 0.5             |
| remain                           |                 |                 |
|                                  | (0.8, 1.6)      | (0.3, 0.8)      |
+----------------------------------+-----------------+-----------------+

Source: Form 05

^a^In LHR+W units, these treatments were not necessary by virtue of the
immediate post-intervention installation of new vinyl replacement
windows with unpainted top sashes and troughs.

4.  ***Type of Contractor and Number of One-Year Post-Intervention
    "Failures"***

At immediate post-intervention, lead hazard reduction treatments were
generally performed by for-profit contractors or the property
owner/employees. Only four of the 73 one-year post-intervention units
had been treated by non-profit contractors; therefore, these data are
excluded from this section's discussion. An average of 5.3 "failures"
per unit were observed at one-year post-intervention in LHR units
treated by for-profit contractors, and 6.7 in LHR units treated by the
property owner/employees (see Table 48 on page 80). The mean number of
one-year post-intervention "failures" per unit in LHR+W units treated by
for-profit contractors and property owner/employees was 5.1 and 3.9,
respectively. A Poisson regression model was run to predict the number
of "failures" per unit at one-year post-intervention based on assigned
treatment group, contractor type (for-profit or property
owner/employees), and their interaction. None of the three variables
were significant predictors of the number of visual assessment
"failures" per unit.

**Table 48: Mean Number of One-Year Post-Treatment "Failures" per Unit**

**by the Type of Contractor^a,b^**

  ------------------------------ --------------- ------------------------
                                 **Mean Number   
                                 of "Failures"   
                                 per Unit**      

  **Contractor Type**            **LHR Units**   **LHR+W Units**

  For-profit contractor          5.3             5.1

  Property owner/employees       6.7             3.9
  ------------------------------ --------------- ------------------------

Source: Form 05

^a^ Because only four of the 73 had nonprofit contractors performing the
work, the number of "failures" is not easily compared against for-profit
contractors and property owner/employees work. Therefore, nonprofit
contractor data are not presented in this table.

^b^Based on a Poisson regression model, neither the assigned treatment
group nor the type of contractor nor the interaction of these two
variables were significant predictors of the number of "failures" per
unit at Phase III.

C.  **Follow-Up Data Summary for One-Year Post-Intervention (Form 06)**

Form 06 (Follow-Up Questions) was designed to collect information from
the property owner or his/her designee about any activities that
occurred in the unit in the 12-month period after intervention. Only
four units reportedly had a change in tenancy. And, in general, few
units appear to have had further lead hazard reduction treatments done
during the one-year post-intervention period. During the 12 months prior
to LAAP's one-year post-intervention visit, lead hazard reduction work
was reportedly done in six units, four of which had work done at
turnover. Costs for this lead hazard reduction work ranged from \$100 to
\$2,000 (mean of approximately \$600), with work done one to eight
months before the one-year post-intervention visit. In two units,
tenants reported to the owner that new lead hazards existed; these were
not the same two units that had lead hazard reduction work done but no
work was completed at turnover. There was one unit for which the owner
was notified that a tenant child had a blood lead level between 15 and
24 µg/dl. A qualified offer was made for this case. No owner was
notified that a tenant child had a blood lead level above 25 µg/dl.

# Statistical Modeling Results for One-Year Post-Intervention

1.  ***Predicting Dust Lead Loading at One-Year Post-Intervention***

A multiple regression model with backward elimination was used with
multiple regression to identify factors that are significant predictors
of one-year post-intervention composite dust lead loadings. Composite
dust lead loadings were used instead of single surface results because
composite data were available for all 73 one-year post-intervention
units. A separate model was run for each surface type (i.e., bare
floors, interior window sills and window troughs). Dust lead loading
measurements were log transformed. (Statistical tables resulting from
these models are provided in Appendix I.)

The set of possible predictors considered were:

-   Type of building (e.g., single family or multifamily dwelling);

-   Year of construction (e.g., pre-1920 or 1920-1949);

-   Contractor type (i.e., for-profit, nonprofit, property
    owner/employee);

-   Concurrent work (i.e., yes or no);

-   Treatment group (i.e., LHR or LHR+W);

-   Pre-intervention composite dust lead loading results for a given
    surface type (i.e., bare floors, interior window sills or window
    troughs);

-   Number of items of baseline interior dwelling unit deterioration;

-   Number of items of baseline exterior building deterioration;

-   Percent of windows replaced out of the total number of windows in a
    dwelling unit;

-   Estimated market value of a dwelling unit;

-   Total lead hazard control cost for a dwelling unit, including window
    replacement costs, if applicable;

-   Was work performed during 12-month post-intervention period
    (yes/no);

-   Number of rooms with any visual assessment failures at one-year
    post-intervention; and

-   Interactions of (1) the number of interior dwelling unit
    deterioration items, (2) the number of exterior building
    deterioration items, and (3) pre-intervention dust lead loadings
    with each of the following: concurrent work, percent of windows
    replaced, total lead hazard reduction cost, and assigned treatment
    group.

The only significant predictor of one-year post-intervention bare floor
dust lead loadings was the percent of rooms with visual assessment
\"failures\" at one-year post-intervention (i.e., units with more
one-year post-intervention visual assessment failures were more likely
to have higher one-year post-intervention composite floor dust lead
loadings). The percentage of variation (i.e., R^2^) accounted for in
one-year post-intervention composite dust lead loadings by this variable
is 13%. For interior window sills, the variables found to predict
one-year post-intervention dust lead loadings were pre-intervention sill
dust lead loadings and the assigned treatment group (R^2^=24%) (i.e.,
units with higher pre-intervention sill dust lead loadings were more
likely to have higher one-year post-intervention dust lead loadings, and
LHR units were more likely to have higher sill dust lead loadings than
LHR+W units). The only variable that was predictive of one-year
post-intervention composite dust lead loadings for window troughs was
the assigned treatment group (R^2^=10%) (i.e., LHR units were more
likely to have higher one-year post-intervention composite trough dust
lead loadings than LHR+W units).

1.  ***Predicting One-Year Post-Intervention Dust Lead Loading
    Exceedances of Standards***

Separate logistic regression models with backward elimination were
employed to predict whether dwelling units would have one-year
post-intervention dust lead loadings on bare floors, interior window
sills and window troughs that exceeded standards of 100 μg/ft^2^, 500
μg/ft^2^, and 800 μg/ft^2^, respectively (see Appendix I). The same set
of possible predictors that were used in predicting dust lead loading at
one-year post-intervention were also employed for this model, except
that interactions were not included because they are not appropriate for
logistic models.

For bare floors, the only significant predictor of one-year
post-intervention composite results being above a standard of 100
µg/ft^2^ was the year of construction, with older units more likely to
yield one-year post-intervention floor results above 100 µg/ft^2^. For
window sills, variables found to significantly predict one-year
post-intervention composite dust lead loadings above a standard of 500
µg/ft^2^ were pre-intervention window sill dust lead loadings and
assigned treatment group, with units having higher pre-intervention
composite sill results more likely to have one-year post-intervention
sill results above 500 µg/ft^2^, and LHR units more likely to have
one-year post-intervention sill results above 500 µg/ft^2^ than LHR+W
units. For window troughs, the only predictor of one-year
post-intervention composite dust lead loadings for window troughs was
the assigned treatment group (R^2^=10%), with LHR+W units less likely to
have one-year post-intervention composite trough results above a
standard of 800 µg/ft^2^.

2.  ***Predicting One-Year Post-Intervention Visual Assessment
    "Failures"***

A Poisson regression model with backward elimination[^10] was employed
to predict the number of rooms having a visual assessment "failure"
reported at one-year post-intervention. Again, the same set of possible
predictors employed for predicting one-year post-intervention composite
dust lead loading and one-year post-intervention composite dust lead
loading exceedances of standards were used for this model. Significant
predictors were the total lead hazard reduction cost at immediate
post-intervention (higher costs would yield fewer rooms with
"failures"), building type (single and rowhouses would have more rooms
with "failures" than multifamily buildings), whether work had been
performed in the unit during the previous 12 months (yes would yield
fewer rooms with "failures"), and the estimated market value of the
dwelling (higher market values would yield fewer rooms with "failures").

II. **SUMMARY OF TWO-YEAR POST-INTERVENTION RESULTS**

As discussed in the introduction to Section VI, only 24 units (11 LHR,
13 LHR+W) had complete two-years post-intervention data. Given this
small number of units, rigorous statistical testing is not considered
appropriate. However, this section provides a general summary of the
two-years post-intervention findings.

A.  **Two-Year Post-Intervention Dust Sampling Results**

No single surface samples were collected from any of the 24 units during
two-years post-intervention; therefore, only composite results are
discussed. A complete listing of two-years post-intervention composite
results is provided in Appendix E.

1.  ***Summary of Two-Year Post-Intervention Composite Results***

For bare floors, median composite dust lead loadings for LHR units were
slightly lower than those for LHR+W units. However, for sills and
troughs, LHR+W units had much lower median dust lead loadings than LHR
units (See Table 49 on page 83). Based on Kruskal-Wallis testing,
two-years post-intervention median composite dust lead loadings for
sills and troughs were significantly associated with assigned treatment
group (p=0.0064 and 0.0300, respectively) but not for bare floors
(p=0.7098).

**Table 49: Two-Year Post-Intervention *Composite* Sample Dust Lead
Loadings**

+------------------+-------------------+-------------------------------+
| **Surface Type** | **[LHR Dust Lead  | **[LHR+W Dust Lead Loading    |
|                  | Loading           | (μg/ft^2^)]{.underline}**     |
|                  | (μg/ft^2          |                               |
|                  | ^)]{.underline}** | *Median*                      |
|                  |                   |                               |
|                  | *Median*          | **Geometric Mean**            |
|                  |                   |                               |
|                  | **Geometric       | 95% Confid. Limits            |
|                  | Mean**            |                               |
|                  |                   |                               |
|                  | 95% Confid.       |                               |
|                  | Limits            |                               |
+------------------+-------------------+-------------------------------+
| Bare floors^a,b^ | *19*              | *24*                          |
|                  |                   |                               |
| (10 LHR units,   | **27**            | **18**                        |
|                  |                   |                               |
| 13 LHR+W units)  | (9, 85)           | (10, 30)                      |
+------------------+-------------------+-------------------------------+
| Interior window  | *568*             | *46*                          |
| sills^a,b^       |                   |                               |
|                  | **485**           | **99**                        |
| (10 LHR units,   |                   |                               |
|                  | (199; 1,186)      | (45; 221)                     |
| 13 LHR+W units)  |                   |                               |
+------------------+-------------------+-------------------------------+
| Window           | *1,710*           | *452*                         |
| troughs^a,b^     |                   |                               |
|                  | **3,119**         | **558**                       |
| (10 LHR units,   |                   |                               |
|                  | (779; 12,492)     | (235; 1,329)                  |
| 13 LHR+W units)  |                   |                               |
+------------------+-------------------+-------------------------------+

Source: Form 04A, Phase IV

^a^Approximately 96% of bare floor composites, interior window sill
composites, and window trough composites were comprised of 4
sub-samples; the rest were comprised of 2 sub-samples.

^b^ Kruskal-Wallis test indicates that median sill and trough values
were significantly associated with assigned treatment group (p=0.0064
and 0.0300, respectively) but not the median bare floor value
(p=0.7098).

2.  ***Change in Composite Results from Pre- to Two-Years
    Post-Intervention***

Large median percent decreases were observed when measuring the change
in dust lead loadings from pre to two-years post-intervention for
composite samples taken from bare floors, sills and troughs (Table 50 on
page 84). The association between the percent reduction in
pre-intervention to two-years post-intervention dust lead loadings and
assigned treatment group was significant for window sills (p=0.0008) and
troughs (p=0.0019) but not for bare floors (p=0.2917). Although
pre-intervention window component dust lead loadings for the LHR+W group
were significantly higher than those for LHR units, at two years
post-intervention, the LHR+W group had lower window component dust lead
loadings. Although two-year post-intervention window component dust lead
loadings remained lower than pre-intervention loadings for LHR units,
the wide confidence intervals shown in Table 49 indicate that some
dwellings have rather high loadings two years after treatment.

**Table 50: Median Percent Reductions and Absolute Reductions in Pre- to
Two-Year Post-Intervention *Composite* Dust Lead Loadings**

+---------------------------------------+--------------+--------------+
| **Surface Type and                    | **LHR        | **LHR+W      |
| Statistic-Composite Dust Samples**    | Units**      | Units Pre to |
|                                       |              | 2-Yr         |
|                                       | **Pre to     | Post-        |
|                                       | 2-Yr         | Intervention |
|                                       | Post-        | Reduction**  |
|                                       | Intervention |              |
|                                       | Reduction**  |              |
+---------------------------------------+--------------+--------------+
| [Median Percent Reduction (10 LHR, 13 | *78%*        | *88%*        |
| LHR+W)^a^]{.underline}:               |              |              |
|                                       | **79%**      | **97%**      |
| *Bare Floors*                         |              |              |
|                                       | 39%          | 96%          |
| **Window Sills**                      |              |              |
|                                       |              |              |
| Window Troughs                        |              |              |
+---------------------------------------+--------------+--------------+
| [Median Absolute Reduction (10 LHR,   | *45          | *170         |
| 13 LHR+W^a^]{.underline}              | µg/ft^2^*    | µg/ft^2^*    |
|                                       |              |              |
| *Bare Floors*                         | **1,960      | **2,563      |
|                                       | µg/ft^2^**   | µg/ft^2^**   |
| **Window Sills**                      |              |              |
|                                       | 1,154        | 10,104       |
| Window Troughs                        | µg/ft^2^     | µg/ft^2^     |
+---------------------------------------+--------------+--------------+

Source: Form 04A

^a^ The association between the percent reduction in pre-intervention to
Phase IV dust lead loadings and assigned treatment group was significant
for window sills (p=0.0008) and troughs (p=0.0019) but not for bare
floors (p=0.2917).

3.  ***Change in Composite Results from One-Year to Two-Years
    Post-Intervention***

Of the 24 units having two-years post-intervention data, only 15 (7 LHR
and 8 LHR+W) units had complete one-year post-intervention data. These
numbers were too small to permit a reliable comparison of one-year
post-intervention and two-years post-intervention data to be conducted.
Therefore, these results are excluded from this report.

B.  **Results of Two-Year Post-Intervention Visual Assessment**

Too few visual assessment "failures" were observed in each treatment
group to allow comparison of two-years post-intervention visual
assessment "failures" in LHR versus LHR+W units. Therefore, this
discussion focuses on the 24 two-years post-intervention units as a
whole. A complete listing of two-years post-intervention visual
assessment "failures" is provided in Appendix G. Overall, 90 percent
(22) of the 24 units having two-years post-intervention data had at
least one visible assessment "failure" two years after treatment (Table
51 on page 85). LAAP informed landlords of these "failures" and
recommended that they be repaired.

The most common visual assessment \"failure\" at two-years
post-intervention was that not all paint was intact, with 22 of the 24
units exhibiting this type of \"failure\". The magnitude of this
\"failure\" was similar to that reported at one-year post-intervention:
a geometric mean of 2 ft^2^ of non-intact paint per unit was noted.
Other \"failure\" types were less prevalent. For example, 10 of the 24
units reportedly had at least one door with painted surfaces rubbing
together, while 9 units had some non-intact or damaged kitchen and/or
bathroom floor coverings, with a geometric mean of 2 ft^2^ of such
damage reported. Three to seven rooms per unit had some type of visual
assessment "failure" at two-years post-intervention (mean=5 rooms).

# Table 51: Reporting Frequency of Specified Types of Two-Year Post-Intervention Visual Assessment "Failures"

+--------------------------+-------+--------+--------+---------------+
| **"Failure" Type**       | *     | **\#   | **Rep  | **"Failure"   |
|                          | *Unit | Units  | orting | Magnit.       |
| **(24 units)**           | of    | with   | Freq.  | (Geom. Mean & |
|                          | Meas  | Spe    | of     | 95% Conf.     |
|                          | ure** | cified | "Fa    | Limits)**     |
|                          |       | "Fa    | ilure" |               |
|                          |       | ilure" | Type   |               |
|                          |       | R      | at**   |               |
|                          |       | pt'd** |        |               |
|                          |       |        | **Ph   |               |
|                          |       |        | IV**   |               |
+--------------------------+-------+--------+--------+---------------+
| Not all paint intact (22 | EA^a^ | 2      | 2      | 2 (NA)^c^     |
| units)                   |       |        |        |               |
+--------------------------+-------+--------+--------+---------------+
|                          | LF    | 20     | 58     | 2 (1, 3)      |
+--------------------------+-------+--------+--------+---------------+
|                          | SF    | 15     | 47     | 2 (0.4, 5)    |
+--------------------------+-------+--------+--------+---------------+
| For doors, painted       | EA^a^ | 10     | 12     | 1 (1, 1)      |
| surfaces continued to    |       |        |        |               |
| rub together (10 units)  |       |        |        |               |
+--------------------------+-------+--------+--------+---------------+
| Some bare floors not     | LF    | 1      | 1      | 4 (NA)^c^     |
| smooth & cleanable (4    |       |        |        |               |
| units)                   | SF    | 3      | 3      | 2 (0.4, 14)   |
+--------------------------+-------+--------+--------+---------------+
| Not all kitchen &        | LF    | 2      | 3      | 4 (NA)^c^     |
| bathroom floors overlaid |       |        |        |               |
| with water-resistant     | SF    | 7      | 9      | 2 (1, 4)      |
| coverings (9 units)      |       |        |        |               |
+--------------------------+-------+--------+--------+---------------+
| Visible paint chips or   | EA^b^ | 1      | 4      | 7 (NA)^c^     |
| debris remains (6 units) |       |        |        |               |
+--------------------------+-------+--------+--------+---------------+
|                          | SF    | 5      | 10     | 1 (0, 82)     |
+--------------------------+-------+--------+--------+---------------+

EA=each; LF=linear foot; SF=square foot

^a^For these "failure" types, "each" denotes window components (e.g.,
upper sash, lower sash), door casings, or handrails in need of
re-painting. LF/SF values are not available for these occurrences.

^b^For this "failure" type, "each" usually denotes a window with debris
or chips in the well.

^c^No 95% confidence limits were calculated due to the small number of
units having this failure reported.

III. **SUMMARY AND DISCUSSION OF FINDINGS**

The main findings of this study are that dust lead loadings declined
substantially immediately after EA 6-8 prescribed lead hazard reduction
treatments were implemented and remained well below pre-intervention
levels one year later. However, many study units would not have "passed"
clearance dust samples immediately post-intervention had such testing
been required. The results also suggest that the independent visual
inspections conducted in these units missed many lead hazard reduction
treatment "failures." Although these "failures" were corrected upon
discovery, several visual assessment "failures" were observed one year
after treatment. Details concerning these findings are summarized below.

A.  **Summary and Discussion of Findings Through Immediate
    Post-Intervention**

    1.  ***Comparison of Pre- and Immediate Post-Intervention Dust Lead
        Loading Results***

Both the LHR and LHR+W units were generally in poor condition and
exhibited high dust lead loadings prior to the lead hazard reduction
treatments. LHR+W units had a greater number of items of interior
deterioration and their pre-intervention composite and single surface
dust lead loadings were generally higher than those for the LHR units,
indicating that LHR+W units may have been in poorer condition than LHR
units at baseline. However, after completion of the EA 6-8 prescribed
treatments, both the LHR and LHR+W units experienced substantial
reductions in dust lead loading on floors, interior window sills and
window troughs, as measured by either composite or single surface
sampling methods.

Pre and immediate post-intervention dust lead loading results for
composite and single surface sampling methods are summarized in Table
52.

Table 52: Summary of Pre and Immediate Post-Intervention Dust Lead
Loading Results By Assigned Treatment Group and Sampling Method

+----------------------------------+--------+-------+--------+-------+
| ##                               | *      |       | **L    |       |
| # **Surface Type and Statistic** | *LHR** |       | HR+W** |       |
+----------------------------------+--------+-------+--------+-------+
|                                  | *      | **Sin | *      | **S   |
|                                  | *Compo | gle** | *Compo | ingle |
|                                  | site** |       | site** | Surf  |
|                                  |        | *     |        | ace** |
|                                  |        | *Surf |        |       |
|                                  |        | ace** |        |       |
+----------------------------------+--------+-------+--------+-------+
| [Bare Floors]{.underline}:       | *273*  | *192* | *333*  | *338* |
|                                  |        |       |        |       |
| *Median Pre-Intervention Loading | *      | *     | *      | **    |
| (µg/ft^2^)*                      | *147** | *99** | *225** | 226** |
|                                  |        |       |        |       |
| **Median Pre- to Immed Post-Int  | 27     | 66    | 29     | 39    |
| µg/ft^2^ Decrease**              |        |       |        |       |
|                                  | **     | ***   | **     | ***   |
| Median Immed Post-Int Loading    | *85*** | 70*** | *89*** | 88*** |
| (µg/ft^2^)                       |        |       |        |       |
|                                  |        |       |        |       |
| # *Median Pre- to Imm            |        |       |        |       |
| ed Post-Int* *Percent Decrease*  |        |       |        |       |
+----------------------------------+--------+-------+--------+-------+
| [Interior window                 | *      | *844* | *      | *2    |
| sills]{.underline}:              | 1,986* |       | 2,780* | ,350* |
|                                  |        | **    |        |       |
| *Median Pre-Intervention Loading | **1    | 497** | **2    | **2,  |
| (µg/ft^2^)*                      | ,686** |       | ,596** | 516** |
|                                  |        | 103   |        |       |
| **Median Pre- to Immed Post-Int  | 83     |       | 36     | 29    |
| µg/ft^2^ Decrease**              |        | ***   |        |       |
|                                  | **     | 84*** | **     | ***   |
| Median Immed Post-Int Loading    | *94*** |       | *99*** | 99*** |
| (µg/ft^2^)                       |        |       |        |       |
|                                  |        |       |        |       |
| ######### Median Pre- to         |        |       |        |       |
|  Immed Post-Int Percent Decrease |        |       |        |       |
+----------------------------------+--------+-------+--------+-------+
| [Window Troughs]{.underline}:    | *      | *6    | *1     | *12   |
|                                  | 9,427* | ,135* | 0,998* | ,227* |
| *Median Pre-Intervention Loading |        |       |        |       |
| (µg/ft^2^)*                      | **9    | **4,  | **11   | **12, |
|                                  | ,708** | 111** | ,284** | 022** |
| **Median Pre- to Immed Post-Int  |        |       |        |       |
| µg/ft^2^ Decrease**              | 344    | 610   | 100    | 115   |
|                                  |        |       |        |       |
| Median Immed Post-Int Loading    | **     | ***   | ***\   | ***   |
| (µg/ft^2^)                       | *95*** | 94*** | >99*** | 99*** |
|                                  |        |       |        |       |
| ######### Median Pre- to         |        |       |        |       |
|  Immed Post-Int Percent Decrease |        |       |        |       |
+----------------------------------+--------+-------+--------+-------+

Note: Because a smaller number of LHR units were single surface sampled
both pre and immediate post-intervention, these results are possibly
more uncertain even though they are consistent with single surface
sample results observed for the LHR+W units.

While none of the study units were legally required (under EA 6-8) to
undergo and pass clearance dust testing, all immediate post-intervention
[median]{.underline} *composite* and *dwelling unit average of single
surface* sample dust lead loading values for bare floors, interior
window sills and window troughs were below the Maryland and HUD/EPA
guidance abatement "clearance" standards for such surfaces. However,
when applying these clearance standards to individual *single surface*
dust sample results, an appreciable number of LHR and LHR+W units had at
least one immediate post-intervention floor, interior window sill and/or
window trough dust lead loading value that exceeded the Maryland and
HUD/EPA guidance standards (see Table 53 on page 87). Forty-six (46) and
28 percent of units exceeded floor clearance standards of 100 µg/ft^2^
and 200 µg/ft^2^, respectively. Eight (8) percent of units exceeded the
interior window sill clearance standard 500 µg/ft^2^. Twenty-seven (27)
percent of units exceeded the window trough clearance standard of 800
µg/ft^2^. Assigned treatment group was significantly associated with
immediate post-intervention interior window sill and window trough
results "passing" or "failing" their standards (LHR+W units generally
did better) but was not significantly associated with bare floors
"passing" or "failing" their respective standards. It should be noted
that, had clearance testing been required, single surface dust wipe
results would yield more clearance "failures" than would composite dust
wipe results (see Appendix J for more details).

**Table 53: Percentage of Units with Immediate Post-Intervention *Single
Surface*** Clearance "Failures"

  ------------------- ------------ ---------- ------------------- ----------------
                      **Percent of                                
                      Units within                                
                      Specified                                   
                      Category**                                  

  **Surface Type:**   **Floors**              **Interior Window   **Window
                                              Sills**             Troughs**

  **Std/Guidance:**   100         200       500 µg/ft^2^       800 µg/ft^2^
                      µg/ft^2^     µg/ft^2^                       

  **LHR Units**       60%          35%        20%                 50%

  **LHR+W Units**     41%          25%        5%                  19%

  **Total All Units** 46%          28%        8%                  27%
  ------------------- ------------ ---------- ------------------- ----------------

2.  ***Immediate Post-Intervention Visual Assessment Results***

Although statistically significant dust lead loading reductions from pre
to immediate post-intervention were observed, immediate
post-intervention confirmatory visual assessments performed by the LAAP
inspectors suggest that a high percentage of study units (93 percent of
LHR and LHR+W units combined) had "failures" of one or more of the
prescribed lead hazard reduction treatments and, as such, would have
"failed" to meet the EA 6-8 risk reduction standard. This is noteworthy
since each one of the 121 study units passed the independent visual
inspection conducted shortly before the LAAP confirmatory visual
assessments.

In addition, the reported "failures" were large enough to be easily
observed. For the most commonly reported "failure"---not all paint
intact---a dwelling unit geometric mean of 1 ft^2^ of non-intact paint
was reported in LHR and in LHR+W units. Visible paint chips and debris
remaining at clearance was also quite frequently reported, with a
dwelling unit geometric mean of 8 ft^2^ noted in LHR units and 16 ft^2^
in LHR+W units. Door surfaces continuing to rub together were also
frequently reported at an average of 1 door per unit.

Of these 121 units, 27 percent would have "failed" one (1) of the
prescribed lead hazard reduction treatment types, another 36 percent
would have "failed" two (2) of the prescribed treatment types and an
additional 23 percent would have "failed" three (3) of the prescribed
treatment types. For both LHR and LHR+W units, the most prevalent
"failure" types were: not all paint intact, with some chipping, flaking
and peeling paint remaining (75 percent of all units); one or more
painted doors continuing to rub together and/or bind (43 percent); and
visible paint chips and/or debris remaining (38 percent). Additionally,
in 26 percent of the LHR units, not all window trough cap material was
properly attached.

In those units that "failed" the LAAP inspectors' visual assessment at
immediate post-intervention, considering only those rooms with
"failures" applicable to both LHR and LHR+W units, an average of 3.1
rooms in the LHR units and 2.6 rooms in the LHR+W units had "failures."

These results suggest that, at least for this study group, lead hazard
reduction treatments did not completely meet the prescribed risk
reduction standard and more strongly suggest that the independent visual
inspections conducted in these units failed to identify all lead hazard
reduction treatment "failures," even ones that should have been easily
observed (e.g., 71 ft^2^ of visible chips/debris). Because only five or
six independent inspectors conducted visual inspections in the group of
121 study units, this finding does not necessarily reflect on all other
Maryland-certified inspectors but does indicate that these five or six
inspectors missed important items.

3.  ***Cost Data Analysis Results***

Two factors potentially impacted the lead hazard reduction treatment
costs recorded for the 121 study units:

-   ["Adverse selection" of enrolled units]{.underline}. The majority of
    the study units were in poor condition to begin with (e.g.,
    extensive deferred maintenance resulted in a high degree of interior
    and exterior deterioration), which likely resulted in higher costs.
    Because property owners could receive a grant for up to 80 percent
    of the total lead hazard control costs, they may have deliberately
    enrolled units that needed more extensive work, either due to
    deferred maintenance or the length of time since last rental
    turnover.

-   [Effect of participating in the study]{.underline}. Since property
    owners and contractors were aware that the enrolled units were being
    evaluated for the study, it is possible that extra effort may have
    gone into the lead hazard reduction treatments, thereby potentially
    inflating reported treatment costs. (Interestingly, even if this was
    the case, it was not borne out by the LAAP inspectors' visual
    assessment results.)

Window replacement also added appreciably to the total lead hazard
reduction treatment costs recorded for the LHR+W units. While median
costs for only the prescribed lead hazard reduction treatments were
\$2,154 and \$1,649 for LHR and LHR+W units, respectively, the median
lead treatment [plus]{.underline} window replacement cost for LHR+W
units was \$4,348; this represents an approximate two-fold increase in
the total LHR+W lead costs.

Speculating that the recorded costs were higher than expected for a
typical Baltimore City rental housing unit, Center and LAAP
representatives met with a local rental property owner to discuss his
firm's experience in complying with the EA 6-8 risk reduction standard.
On average, this owner's total expense of performing the prescribed
treatments at first unit turnover costs from \$700 to \$900 per unit.
Subsequent turnover prescribed treatment costs typically run from \$300
to \$400 per unit. The initial expenses that are added to this owner's
normal unit turnover regimen include HEPA vacuuming the entire unit
(\$80), window treatments (\$35 to \$40 per window unit), re-hanging and
re-working doors (\$20 to \$25 per door), and the cost of a visual
inspector (\$35 to \$40 per inspection). According to this owner, normal
unit turnover expenses, exclusive of the required lead-related costs,
can run as high as \$5,000 to \$6,000 per unit, depending on the length
of time the unit has been occupied by one tenant and/or the amount of
tenant-related damage. (The owner counts interior repainting as a normal
turnover expense.)

Considering the factors that potentially inflated recorded costs and
reflecting on the typical experience of a Baltimore City rental property
owner in complying with the statute, the lead hazard reduction treatment
costs recorded by this study should not be considered average and/or
representative of all Baltimore City rental housing units.

## Summary and Discussion of Findings Through Two-Years Post-Intervention

1.  ***Comparison of Pre-Intervention and One-Year Post-Intervention
    Dust Lead Loading Results***

Prior to prescribed lead hazard reduction treatments, both the LHR and
the LHR+W units in the 73-unit dataset (followed through one year) were
generally in poor condition and exhibited high dust lead loadings.
During the one-year post-intervention period, only six (6) of the 73
units reportedly had further lead hazard reduction work done. At
one-year post-intervention, composite dust lead loadings on bare floors,
window sills and window troughs remained far below pre-intervention
levels in both treatment groups. Median percent reductions in composite
dust lead loadings from pre-intervention to one-year post-intervention
on sills and troughs in LHR+W units were significantly different from
and lower than those in LHR units. The median percent reduction in
composite dust lead loadings for bare floors in LHR+W units was about
the same as in LHR units.

At one-year post-intervention, single surface dust lead loadings on
floors, sills and troughs remained far below pre-intervention levels for
LHR+W units, the only treatment group having single surface data at
one-year post-intervention.

Pre and one-year post-intervention dust lead loading results for
composite and single surface sampling methods are summarized in Table
54.

**Table 54: Summary of Pre- and One-Year Post-Intervention Dust Lead
Loading Results By Assigned Treatment Group and Sampling Method**

+----------------------------------+--------+------+--------+--------+
| **Surface Type and Statistic**   | *      |      | **L    |        |
|                                  | *LHR** |      | HR+W** |        |
+----------------------------------+--------+------+--------+--------+
|                                  | *      | **   | *      | **     |
|                                  | *Compo | Sing | *Compo | Single |
|                                  | site** | le** | site** | Sur    |
|                                  |        |      |        | face** |
|                                  |        | **S  |        |        |
|                                  |        | urfa |        |        |
|                                  |        | ce** |        |        |
+----------------------------------+--------+------+--------+--------+
| [Bare Floors]{.underline}:       | *120*  | *NA* | *454*  | *440*  |
|                                  |        |      |        |        |
| *Median Pre-Intervention Loading | **87** | # NA | *      | *      |
| (µg/ft^2^)*                      |        |      | *335** | *420** |
|                                  | 22     | NA   |        |        |
| **Median µg/ft^2^ Reduction**    |        |      | 20     | 20     |
|                                  | ***    | #### |        |        |
| Median 1-Yr Post-Intervention    | 82%*** | #### | ***    | ***    |
| Loading (µg/ft^2^)               |        | # NA | 94%*** | 96%*** |
|                                  |        |      |        |        |
| # *Median Percent Reduction*     |        |      |        |        |
+----------------------------------+--------+------+--------+--------+
| [Interior window                 | *      | *NA* | *      | *      |
| sills]{.underline}:              | 1,739* |      | 2,930* | 1,987* |
|                                  |        | # NA |        |        |
| *Median Pre-Intervention Loading | *      |      | **2    | **1    |
| (µg/ft^2^)*                      | *713** | NA   | ,803** | ,875** |
|                                  |        |      |        |        |
| **Median µg/ft^2^ Reduction**    | 449    | ***N | 121    | 64     |
|                                  |        | A*** |        |        |
| Median 1-Yr Post-Intervention    | ***    |      | ***    | ***    |
| Loading (µg/ft^2^)               | 82%*** |      | 97%*** | 97%*** |
|                                  |        |      |        |        |
| ##                               |        |      |        |        |
| ####### Median Percent Reduction |        |      |        |        |
+----------------------------------+--------+------+--------+--------+
| [Window Troughs]{.underline}:    | *1     | *NA* | *1     | *1     |
|                                  | 0,219* |      | 2,524* | 7,083* |
| *Median Pre-Intervention Loading |        | # NA |        |        |
| (µg/ft^2^)*                      | **4    |      | **12   | **16   |
|                                  | ,507** | NA   | ,014** | ,338** |
| **Median µg/ft^2^ Reduction**    |        |      |        |        |
|                                  | 1,074  | ***N | 247    | 211    |
| Median 1-Yr Post-Intervention    |        | A*** |        |        |
| Loading (µg/ft^2^)               | ***    |      | ***    | ***    |
|                                  | 89%*** |      | 98%*** | 99%*** |
| ##                               |        |      |        |        |
| ####### Median Percent Reduction |        |      |        |        |
+----------------------------------+--------+------+--------+--------+

NA=Not applicable. Single surface samples were collected in only two LHR
units at Phase III; therefore, no single surface results are presented
for LHR units.

For bare floor and sills, one-year post-intervention median composite
dust lead loadings were less than HUD clearance standards of 100 and 500
µg/ft^2^, respectively. Median composite dust lead loadings for troughs
in LHR+W units were also less than the HUD standard of 800 µg/ft^2^, but
the median composite trough result for LHR units exceeded this standard.
At one-year post-intervention, 14% of LHR+W units had at least one
single surface floor dust lead result exceeding a clearance standard of
100 µg/ft^2^, 17% had at least one single surface sill result greater
than 500 µg/ft^2^ and 14% had at least one single surface trough result
above 800 µg/ft^2^ (see Table 55).

Comparison of LHR+W clearance exceedance rates with those of Baltimore
HUD units studied during the National Evaluation yielded some surprising
results. Although LHR+W units appeared to be in worse condition at
baseline and Baltimore HUD units had similar treatments and clearance
testing immediately after intervention, LHR+W units appeared to be in
better condition one year later based on single surface dust wipe
results. This finding is possibly due to the correction of treatment
"failures" in LHR+W units after the immediate post-intervention visit.
Median percent reductions from pre to one-year post-intervention were
generally greater for LHR+W units than for Baltimore HUD units, possibly
due to the worse initial condition of floors and troughs. LAAP reported
that the correction of Phase II treatment "failures" sometimes entailed
re-cleaning if the correction potentially generated dust (e.g., if
painted doors had to be planed).

**Table 55: Percentage of Units with One-Year Post-Intervention *Single
Surface* Clearance "Failures"**

+------------+---------+----------+------------------+----------------+
|            | **      |          |                  |                |
|            | Percent |          |                  |                |
|            | of      |          |                  |                |
|            | Units   |          |                  |                |
|            | within  |          |                  |                |
|            | Sp      |          |                  |                |
|            | ecified |          |                  |                |
|            | Cat     |          |                  |                |
|            | egory** |          |                  |                |
+------------+---------+----------+------------------+----------------+
| **Surface  | **F     |          | **Interior       | **Window       |
| Type:**    | loors** |          | Window Sills**   | Troughs**      |
+------------+---------+----------+------------------+----------------+
| **Std/G    | 100    | 200     | 500 µg/ft^2^    | 800 µg/ft^2^  |
| uidance:** | µ       | µg/ft^2^ |                  |                |
|            | g/ft^2^ |          |                  |                |
+------------+---------+----------+------------------+----------------+
| **LHR+W    | 14%     | 11%      | 17%              | 14%            |
| Units**    |         |          |                  |                |
|            |         |          |                  |                |
| **(36      |         |          |                  |                |
| units)**   |         |          |                  |                |
+------------+---------+----------+------------------+----------------+
| **Balt.    | 57%     | NA       | 11%              | 35%            |
| HUD        |         |          |                  |                |
| Units**    |         |          |                  |                |
|            |         |          |                  |                |
| **(249     |         |          |                  |                |
| units)**   |         |          |                  |                |
+------------+---------+----------+------------------+----------------+

2.  ***One-Year Post-Intervention Visual Assessment Results***

Although immediate post-intervention treatment "failures" were corrected
and one-year post-intervention median composite dust lead loadings in a
majority of units were less than clearance standards, a high percentage
of units (96%) had at least one visual assessment "failure" reported one
year after treatments were completed. These "failures" were widespread,
with non-intact paint reported in 68 units, painted door surfaces
rubbing together in 30 units, visible paint chips and debris in 21
units, deterioration of kitchen and bathroom floor water-resistant
coverings in 20 units, and bare floors not smooth and cleanable in nine
(9) units. Such "failures" tended to be of small magnitude but were
large enough to be easily observed, with geometric means of 1 ft^2^ of
non-intact paint reported per unit, one rubbing painted door problem per
unit, 4 ft^2^ of bare floors that were not smooth and cleanable, 2 ft^2^
of deteriorated kitchen/bathroom floor water-resistant coverings, and 1
ft^2^ of visible paint chips and debris present one year after
interventions. As previously stated, the areal density (i.e., depth) and
lead concentration of chips/debris were not measured. These visual
assessment results suggest that, at least for this study group, lead
hazard reduction treatments did not remain completely intact one year
after lead hazard reduction treatments.

3.  *Comparison of Pre-Intervention and Two-Years Post-Intervention Dust
    Lead Loading Results*

Two years after lead hazard reduction treatments were first performed,
composite dust lead loadings on all surfaces remained well below
pre-intervention levels (Table 56). Of the 24 units having two-years
post-intervention data, only 15 had complete one-year post-intervention
data; therefore, no comparison of one-year post-intervention and
two-years post-intervention data could be made.

**Table 56: Summary of Pre- and Two-Years Post-Intervention
*Composite^a^* Dust Lead**

**Loading Results By Assigned Treatment Group and Sampling Method**

+----------------------------------------+--------------+--------------+
| **Surface Type and Statistic**         | **LHR**      | **LHR+W**    |
+----------------------------------------+--------------+--------------+
| [Bare Floors]{.underline}:             | *139*        | *177*        |
|                                        |              |              |
| *Median Pre-Intervention Loading       | **45**       | **170**      |
| (µg/ft^2^)*                            |              |              |
|                                        | 19           | 24           |
| **Median Pre- to 2-Yr Post-Int         |              |              |
| µg/ft^2^ Reduction**                   | ***78%***    | ***88%***    |
|                                        |              |              |
| Median 2-Yr Post-Intervention Loading  |              |              |
| (µg/ft^2^)                             |              |              |
|                                        |              |              |
| # *Median Pre                          |              |              |
| - to 2-Yr Post-Int Percent Reduction*  |              |              |
+----------------------------------------+--------------+--------------+
| [Interior window sills]{.underline}:   | *2,201*      | *2,930*      |
|                                        |              |              |
| *Median Pre-Intervention Loading       | **1,960**    | **2,563**    |
| (µg/ft^2^)*                            |              |              |
|                                        | 568          | 46           |
| **Median Pre- to 2-Yr Post-Int         |              |              |
| µg/ft^2^ Reduction**                   | ***79%***    | ***97%***    |
|                                        |              |              |
| Median 2-Yr Post-Intervention Loading  |              |              |
| (µg/ft^2^)                             |              |              |
|                                        |              |              |
| ######### Median P                     |              |              |
| re- to 2-Yr Post-Int Percent Reduction |              |              |
+----------------------------------------+--------------+--------------+
| [Window Troughs]{.underline}:          | *3,408*      | *10,900*     |
|                                        |              |              |
| *Median Pre-Intervention Loading       | **1,154**    | **10,104**   |
| (µg/ft^2^)*                            |              |              |
|                                        | 1,710        | 452          |
| **Median Pre- to 2-Yr Post-Int         |              |              |
| µg/ft^2^ Reduction**                   | ***39%***    | ***96%***    |
|                                        |              |              |
| Median 2-Yr Post-Intervention Loading  |              |              |
| (µg/ft^2^)                             |              |              |
|                                        |              |              |
| ######### Median P                     |              |              |
| re- to 2-Yr Post-Int Percent Reduction |              |              |
+----------------------------------------+--------------+--------------+

^a^Single surface samples were not collected in any units at Phase IV;
therefore, no single surface results are presented.

A.  Comparing the Efficacy of the Prescribed Lead Hazard Reduction
    Treatments Both With and Without Window Replacement

When measured by the immediate post-intervention visual assessments
[and]{.underline} composite and single surface dust lead loading
results, pre-intervention lead hazards in the LHR+W units were more
effectively reduced than in the LHR units. Although LHR+W units had more
baseline building and dwelling unit deterioration and higher dust lead
loadings prior to the intervention, these trends were reversed slightly
immediately after treatment. Replacement of windows may account for
these observed immediate post-intervention results, particularly with
respect to interior window sill and window trough dust lead loadings.
This is supported by the results of predictive modeling, which showed
that pre-intervention dust lead loadings on sills and troughs, as well
as treatment group assignment, significantly predicted immediate
post-intervention dust lead loadings on sills and troughs.

At immediate post-intervention, the LHR+W units had fewer lead hazard
reduction treatment visual assessment "failure" types per unit and fewer
rooms per unit with "failures." Also, the mean number of "failure" types
per LHR unit, which was greater than the LHR+W units, was found to be
statistically significant for treatment group assignment (p-value =
0.0255).

For both composite and single surface sampling methods, immediate
post-intervention median bare floor dust lead loading results were
similar for LHR and LHR+W units. However, for interior window sills and
window troughs, both the composite and single surface immediate
post-intervention sample results were significantly associated with the
assigned treatment group, and were substantially lower in the LHR+W
units. This finding indicates that window replacement is much more
effective in reducing lead dust hazards on window surfaces within the
unit immediately after treatment.

Although LHR+W units had more baseline building and dwelling unit
deterioration and higher dust lead loadings than LHR units prior to
intervention, at one-year post-intervention, LHR+W units tended to have
lower dust lead loadings and greater percent reductions in dust lead
loadings on window sills and troughs between pre- and one-year
post-intervention than did LHR units. Little difference in one-year
post-intervention bare floor dust lead loadings, however, was
discernible between the two treatment groups. Replacement of windows
likely accounts for these observed one-year post-intervention results,
as is supported by the results of predictive modeling, which showed that
pre-intervention sill dust lead loadings, as well as treatment group
assignment, significantly predicted one-year post-intervention dust lead
loadings on sills and troughs. Assigned treatment group did not
significantly predict one-year post-intervention bare floor dust lead
loadings; the only significant predictor of one-year bare floor dust
lead loadings was the percent of rooms with visual assessment
"failures."

Although differences in dust lead loadings at one-year post-intervention
were observed, visual assessment "failures" for LHR units were generally
similar to those observed for LHR+W units. While there were marginally
significant differences in the mean number of visual assessment
"failures" per unit for LHR (2.4) versus LHR+W units (1.9) (p=0.0482),
there was no significant association between the types of visual
assessment "failures" and the assigned treatment group and the magnitude
of \"failures\" was generally very similar between the two groups.

These findings indicate that window replacement is more effective in
maintaining lower dust lead loadings on window surfaces within the unit
one year after treatment.

# CONCLUSIONS AND RECOMMENDATIONS

## 

# Conclusions

The primary research goals of this study were to evaluate the efficacy
of the EA 6-8 lead hazard reduction treatments in reducing dust lead
loading, both alone and in combination with window replacement. Overall,
results through immediate post-intervention showed that dust lead
loadings were significantly reduced on floors, interior window sills and
window troughs. Additionally, results through one-year post-intervention
showed that the levels remained low one year after treatment, with over
80 percent of units having floor, sill and trough dust lead loadings
that were below clearance standards. However, immediately after the
treatment intervention, many units would have "failed" clearance dust
testing had it been required in the statute. More importantly, a
substantial number of units "failed" the LAAP inspectors' visual
assessments at immediate post-intervention, despite the fact that each
of the 121 study units passed the prescribed independent inspector's
visual inspection.

By addressing the five (5) key evaluation questions found in Section
II.B, additional conclusions can be made:

1.  How effective are the EA 6-8-prescribed treatments in reducing dust
    lead loading on floors, interior window sills and window troughs to
    acceptable levels?

Although dramatic decreases in dust lead loadings on all surface types
were found immediately post-intervention, remaining dust lead loadings
were high. As discussed in Section I.A, although EA 6-8 does not require
clearance dust testing upon completion of the prescribed treatments,
study results strongly suggest that visual inspections alone, as
performed by independent visual inspectors under current oversight
conditions, are [not]{.underline} sufficient to assure that housing
units will be safe for re-occupancy by families with young children.

Applying the same HUD/EPA guidance clearance standards of 100 μg/ft^2^
for floors, 500 μg/ft^2^ for interior window sills and 800 μg/ft^2^ for
window troughs that were used to determine dust clearance "failures" in
the HUD Lead Hazard Control Grant Program National Evaluation, immediate
post-intervention single surface dust sample "failure" rates were high
in the study units. Forty-six (46) percent of the units had at least one
sample that "failed" floor clearance, eight (8) percent had at least one
sample that "failed" interior window sill clearance and 27 percent had
at least one sample that "failed" window trough clearance. This is a
higher "failure" rate than that observed for vacant Baltimore Round One
units enrolled in the HUD Evaluation (i.e., 29 percent for floors, one
(1) percent for interior window sills and six (6) percent for window
troughs).

HUD recently promulgated a new lead-based paint regulation governing all
pre-1978 housing receiving federal assistance as well as federally owned
housing. The regulation includes new clearance standards applicable to
such housing. Applying these clearance standards of 40 μg/ft^2^ for
floors, 250 μg/ft^2^ for interior window sills and 400 μg/ft^2^ for
window troughs to the immediate post-intervention single surface dust
sample results recorded during this study, 73 percent of the study units
would have had at least one sample that "failed" floor clearance, 15
percent would have had at least one sample that "failed" interior window
sill clearance and 38 percent would have had at least one sample that
"failed" window trough clearance.

Considering that the study units were not randomly selected and that
property owners, contractors and independent visual inspectors were all
presumably aware that the units would undergo dust testing as part of
this study, these high clearance "failure" rates support the need for
clearance dust testing in conjunction with the prescribed treatments.

2.  To what extent does lead dust re-accumulate on these surfaces over a
    one and two-year period after completion of the treatments?

Overall, one-year post-intervention results showed that dust lead
loadings on floors, sills and troughs remained far below
pre-intervention levels. Although one-year post-intervention dust lead
loadings were dramatically less than pre-intervention levels for all
three surface types, several units had floor, sill and trough composite
dust sample results that exceeded HUD clearance standards of 100, 500,
and 800 µg/ft^2^, respectively, and many had visual assessment
"failures" one year after interventions were complete.

Replacement of windows in units that also underwent the prescribed
treatments resulted in substantially lower dust lead loadings on sills
and troughs one year after completion of treatments, but no significant
differences in bare floor dust lead loadings were observed between LHR+W
and LHR units. These results indicate that lead hazard reduction
interventions that include window replacement are more effective than
those that simply treat windows (Table 57).

Table 57: Median Percent Reductions in Dust Lead Loadings from Pre to
One-Year

Post-Intervention for LHR, LHR+W and Baltimore Round One HUD Evaluation
Units

+--------------------+-------------+--------------+-------------------+
| **Surface Type and | ###### LHR  | **LHR+W      | **Balt.**         |
| Sample Type**      |             | Median %     | **HUD^c^ Median % |
|                    | **Median %  | Decline, Pre | Decline, Pre to   |
|                    | Decline,    | to 1-Yr      | 1-Yr Post**       |
|                    | Pre to 1-Yr | Post**       |                   |
|                    | Post**      |              |                   |
+--------------------+-------------+--------------+-------------------+
| [Bare              | 82          | 94           | NA^a^             |
| Fl                 |             |              |                   |
| oors]{.underline}: | NA^b^       | 96           | 84                |
|                    |             |              |                   |
| Composite          |             |              |                   |
|                    |             |              |                   |
| Single Surface     |             |              |                   |
+--------------------+-------------+--------------+-------------------+
| [Interior window   | 82          | 97           | NA^a^             |
| s                  |             |              |                   |
| ills]{.underline}: | NA^b^       | 97           | 98                |
|                    |             |              |                   |
| Composite          |             |              |                   |
|                    |             |              |                   |
| Single Surface     |             |              |                   |
+--------------------+-------------+--------------+-------------------+
| [Window            | 89          | 98           | NA^a^             |
| Tro                |             |              |                   |
| ughs]{.underline}: | NA^b^       | 99           | 90                |
|                    |             |              |                   |
| Composite          |             |              |                   |
|                    |             |              |                   |
| Single Surface     |             |              |                   |
+--------------------+-------------+--------------+-------------------+

^a^NA=not applicable. Composite dust samples were not taken in the
Baltimore Round One HUD Evaluation units.

^b^NA= not applicable. No single surface results are presented for LHR
units because only 2 LHR units had Phase III single surface samples
collected.

^c^Baltimore HUD unit data are from Round I of the National Evaluation
of HUD's Lead-Based Paint Grant Program and were compiled using
pre-intervention and one-year post-intervention data for units that were
vacant before treatment. For floors, both interior and entry data were
included.

At one-year post-intervention, Baltimore Round One HUD Evaluation units
had a significantly higher percentage of bare floor and window trough
results that exceeded HUD clearance standards of 100 and 500 µg/ft^2^,
respectively, indicating that treatments in LHR+W units may have been
"performing better" than those in Baltimore Round One units. This
finding is surprising given the similarity of treatments performed in
the two sets of units (Table 58 on page 95).

# Table 58: One-Year Post-Intervention "Failures" of HUD Clearance Standards for LHR+W 

# and Baltimore Round One HUD Evaluation Units Based on *Single Surface* Sampling

+-----------------+---------------+-----------------+------------------+
| ####            | ###### LHR    | ###### LHR+W    | ###### Baltimore |
| ## Surface Type |               |                 |                  |
|                 | **Units**     | **Units**       | **HUD Units**    |
|                 |               |                 |                  |
|                 | **%           | **%             | **%**            |
|                 | "Failed"^b^** | "Failed"^b^**   |                  |
|                 |               |                 | **"Failed"^b^**  |
+-----------------+---------------+-----------------+------------------+
| Bare Floors^a^  | NA            | 14              | 57%              |
+-----------------+---------------+-----------------+------------------+
| Interior window | NA            | 17              | 11%              |
| sills           |               |                 |                  |
+-----------------+---------------+-----------------+------------------+
| Window Troughs  | NA            | 14              | 35%              |
+-----------------+---------------+-----------------+------------------+

^a^Baltimore Round One HUD evaluation unit floor samples include all
floor surfaces (i.e., bare and carpeted); LHR and LHR+W unit floor
samples are bare floor surfaces only.

^b^ Based on initial clearance testing using clearance standards of 100
μg/ft^2^, 500 μg/ft^2^ and 800 μg/ft^2^, for floors, sill and troughs,
respectively.

Two years after treatments were first performed, composite dust lead
loadings on all surfaces were less than pre-intervention levels (Table
59).

Table 59: Median Percent Reductions in *Composite*^a^ Dust Lead Loadings
from Pre- to

Two-Years Post-Intervention for LHR and LHR+W Units

+--------------------+-----------------------+-------------------------+
| **Surface Type and | ###### LHR            | **LHR+W**               |
| Sample Type**      |                       |                         |
|                    | **Median % Decline,** | **Median % Decline,**   |
|                    |                       |                         |
|                    | **Pre to 2-Yrs Post** | **Pre to 2-Yrs Post**   |
+--------------------+-----------------------+-------------------------+
| Bare Floors        | 78                    | 88                      |
|                    |                       |                         |
| Interior Window    | 79                    | 97                      |
| Sills              |                       |                         |
|                    | 39                    | 96                      |
| Window Troughs     |                       |                         |
+--------------------+-----------------------+-------------------------+

^a^No single surface results are presented because only composite
samples were collected at Phase IV.

3\. Does the replacement of windows in units that also undergo the
prescribed treatments result in substantially lower lead dust loadings
immediately after completion of the treatments?

As discussed in Section VII.E and as summarized in Table 60 on page 96,
although the percent reduction in pre to immediate post-intervention
composite dust lead loadings was similar for the LHR and LHR+W treatment
groups, the median percent reductions in dust lead loadings as measured
by single surface dust sampling were significantly associated with
assigned treatment group for sills and troughs but not for floors. These
reductions imply that lead hazard reduction interventions that include
window replacement are more effective than those that simply treat
windows in lowering window-related dust lead loadings. This conclusion
is further supported by a comparison of study unit data with those of
the Baltimore Round One HUD Evaluation units. In general, Baltimore
Round One units had all windows replaced and the magnitude in dust lead
loading reduction for these units closely matched that of the LHR+W
units.

Table 60: Median Percent Reductions in Dust Lead Loadings from
Pre-Intervention to Immediate Post-Intervention for LHR, LHR+W and
Baltimore Round One HUD Evaluation Units

+-------------------+--------------+--------------+-------------------+
| **Surface Type    | ###### LHR   | **LHR+W**    | **Balt.** **HUD** |
| and Sample Type** |              |              |                   |
|                   | **Median %   | **Median%    | **Median%         |
|                   | Decline**    | Decline**    | Decline**         |
+-------------------+--------------+--------------+-------------------+
| [Bare             | 85 (49       | 89 (56       | NA^a^             |
| Flo               | units)       | units)       |                   |
| ors]{.underline}: |              |              | 95 (278 units)    |
|                   | 70 (16       | 88 (63       |                   |
| Composite         | units)       | units)       |                   |
|                   |              |              |                   |
| Single Surface    |              |              |                   |
+-------------------+--------------+--------------+-------------------+
| [Interior window  | 94 (52       | 99 (62       | NA^a^             |
| si                | units)       | units)       |                   |
| lls]{.underline}: |              |              | \>99 (277 units)  |
|                   | 84 (16       | 99 (62       |                   |
| Composite         | units)       | units)       |                   |
|                   |              |              |                   |
| Single Surface    |              |              |                   |
+-------------------+--------------+--------------+-------------------+
| [Window           | 95 (52       | \>99 (62     | NA^a^             |
| Trou              | units)       | units)       |                   |
| ghs]{.underline}: |              |              | 99 (273 units)    |
|                   | 94 (16       | 99 (62       |                   |
| Composite         | units)       | units)       |                   |
|                   |              |              |                   |
| Single Surface    |              |              |                   |
+-------------------+--------------+--------------+-------------------+

^a^NA=not applicable. Composite dust samples were not taken in the
Baltimore Round One HUD Evaluation units.

When applying the HUD Evaluation clearance standards for floors,
interior window sills and window troughs (100 μg/ft^2^, 500 μg/ft^2^,
and 800 μg/ft^2^, respectively), LHR+W units had fewer single surface
sample clearance "failures" than LHR units. Upon initial clearance
testing, Baltimore Round One HUD Evaluation units had even fewer
"failures" than either LHR+W or LHR study units (see Table 61). (All
Baltimore Round One units that "failed" clearance were re-cleaned and
eventually met clearance standards when re-tested.) Assigned treatment
group was significantly associated with immediate post-intervention
interior window sill and window trough results "passing" or "failing"
their respective standards, but was not significantly associated with
bare floors "passing" or "failing" their standard.

# Table 61: Immediate Post-Intervention Clearance "Failure" Rates for LHR, LHR+W, 

# and Baltimore Round One HUD Evaluation Units

+------------------+-------------+--------------+----------------------+
| ###              | ###### LHR  | ###### LHR+W | ###### Baltimore     |
| ### Surface Type |             |              |                      |
|                  | **Units**   | **Units**    | **HUD Units**        |
|                  |             |              |                      |
|                  | **%         | **%          | **%**                |
|                  | "F          | "            |                      |
|                  | ailed"^b^** | Failed"^b^** | **"Failed"^b^**      |
+------------------+-------------+--------------+----------------------+
| Bare Floors^a^   | 60          | 41           | 29                   |
+------------------+-------------+--------------+----------------------+
| Interior window  | 20          | 5            | 1                    |
| sills            |             |              |                      |
+------------------+-------------+--------------+----------------------+
| Window Troughs   | 50          | 19           | 6                    |
+------------------+-------------+--------------+----------------------+

^a^Baltimore Round One HUD evaluation unit floor samples include all
floor surfaces (i.e., bare and carpeted); LHR and LHR+W unit floor
samples are bare floor surfaces only.

^b^ Based on initial clearance testing using clearance standards of 100
μg/ft^2^, 500 μg/ft^2^ and 800 μg/ft^2^, for floors, sill and troughs,
respectively. All Baltimore HUD units that initially failed were
re-cleaned and eventually met clearance standards upon re-testing.

These results clearly suggest that, as anticipated, the prescribed risk
reduction treatments, when coupled with full window replacement, achieve
greater dust lead loading reductions for interior window sills and
window troughs, as measured immediately after treatment. While the
prescribed EA 6-8 risk reduction window treatments are less costly and
do reduce pre-intervention dust lead levels on interior window sills and
window troughs, such treatments by themselves do not appear to
consistently remedy all lead hazards associated with windows, as
measured by immediate post-intervention dust lead testing. For example,
unless the lower sash is removed, it cannot be completely scraped and
repainted before being reinstalled. Therefore, many layers of built-up
paint might remain, which could result in paint chips being easily
dislodged as soon as the sash is opened or closed, even after the
prescribed window treatments have been performed.

4.  Do single surface dust wipe sample and composite dust wipe sample
    results correlate well in measuring the amount of lead dust both
    before and after completion of the prescribed treatments?

This evaluation question is addressed in Appendix J.

5.  Do independent visual inspections accurately assess whether the
    prescribed treatments have been completed?

The most significant finding of this study is that, based on the LAAP
inspectors' confirmatory visual assessments, 92 percent of the 121 study
units should have "failed" the EA 6-8 immediate post-intervention
independent visual inspection. These "failures" were driven by one or
more of the prescribed lead hazard reduction treatments not being
performed or properly completed, as assessed by the LAAP inspectors. In
addition, the magnitude of these identified "failures" was large,
indicating that most reported "failures" should have been easily
observable to the independent visual inspectors. Considering that each
of the units passed a visual inspection performed by a certified
independent inspector, this result suggests that such independent visual
inspections did not accurately determine whether the prescribed
treatments were met.

While performing their dust sampling and visual assessments, LAAP
inspectors also noted anecdotally that the five or six independent
visual inspectors they observed spent very little time (e.g., five to 10
minutes in many cases) conducting the visual inspections, suggesting
either carelessness or a lack of training in the level of detail needed
to completely visually inspect a unit for compliance with the prescribed
requirements.

# 

# Recommendations

Based on the study findings, the Center makes the following
recommendations:

1.  **Increased oversight of independent visual inspectors by
    appropriate state agency officials is needed to assure that such
    inspectors are performing visual inspections in accordance with
    approved protocols and inspector training.**

The LAAP inspectors' observations suggest that in-field compliance
checks of independent visual inspectors are critical to assuring that
these inspections are properly performed. Frequent oversight evaluations
of the inspectors may be necessary to emphasize regulatory commitment to
proper performance of the visual inspection protocol and to ensure that
fatigue and/or routine does not result in incomplete inspections.
Additionally, state agency officials may want to review and, as
necessary, revise the protocol and training for visual inspectors.

Neither EA 6-8 nor the Code of Maryland Regulations (COMAR) specifies
objective standards defining a visual inspection "success" or "failure."
Further research (outside the scope of this study) is needed to provide
data that would help identify "de minimis" standards for visual
inspections, i.e., in identifying thresholds at which certain observable
conditions (e.g., binding doors) contribute to elevated dust lead
loadings. Until such data are available, visual inspectors should be
trained to consider any easily observed "defect" on the surface types
and components listed in Section 6-815(A)(2) to constitute a "failure,"
especially given that many large and easily observed "failures" remained
in the study units. In particular, attention should be paid to treatment
"failures" of non-intact paint, visible paint chips and debris, and
rubbing of doors.

2.  **Clearance dust testing, upon completion of the prescribed lead
    hazard reduction treatments, should be added to the independent
    visual inspection as part of the lead hazard reduction treatment
    requirements of EA 6-8, , either by regulation or amendment to the
    statute.**

Notwithstanding the "failure" of 92 percent of the independent visual
inspections to accurately determine whether the study units were in
compliance with the risk reduction standard, lead dust sample results
obtained immediately after intervention revealed that a large percentage
of units also had at least one bare floor, interior window sill or
window trough lead dust result that would have "failed" clearance
testing had such a test been required by EA 6-8. This finding confirms
that visual inspections alone do not reveal all lead hazards. Although
dust clearance sampling evaluates dust lead loading only at a single
point in time and may not represent conditions existing throughout a
dwelling unit, such sampling, when performed in conjunction with a
visual inspection, would likely be more effective in determining the
immediate post-intervention status of the unit at the most critical
point: immediately before new tenants assume residency. For these
reasons, it is recommended that, for units in which the owner chooses
the Lead Hazard Reduction treatment option of EA 6-8, a clearance dust
testing requirement be added to the immediate post-intervention
independent visual inspection requirement, either by regulation or by
amendment to the statute. In other words, a "clearance examination,"
including dust testing [and]{.underline} a visual inspection, should be
performed whenever an owner carries out prescribed lead hazard reduction
treatments.

3.  **Rental property owners and their crews and independent contractors
    must perform a more intensive final cleaning upon completion of the
    prescribed lead hazard reduction treatments.**

Dust sample results suggest that final cleaning after completion of the
prescribed treatments was not, in many cases, sufficient to meet
clearance dust standards, had they existed as a requirement in EA 6-8.
It is presumed that those who meet such clearance standards and who pass
the visual inspection are performing adequate cleaning. In the absence
of clearance testing, owners and/or contractors cannot know if dust lead
loading has been reduced below such standards. However, these results
point out that a thorough final cleaning is critical to reducing all
lead hazards. For example, a substantial number of treatment visual
assessment "failures" observed in the study units were due to paint
chips and debris being present even after the lead hazard reduction
treatments had been completed. Owners\' and contractors\' training must
highlight and emphasize proper cleaning techniques to increase the
likelihood that dust lead loading can be reduced even when dust samples
are not taken to confirm the results.

4.  **More comprehensive window treatments may be necessary to assure
    that interior window sills and window troughs do not continue to be
    an exposure source to lead.**

Study results suggest that the window treatments prescribed in the
statute produce reductions in lead dust and debris that may not be
sufficiently protective based on relative percent changes and clearance
"failures," particularly in housing units that are in poor condition.
Study units that underwent full window replacement experienced a larger
reduction in dust lead loading on interior window sills and window
troughs, as measured by both composite [and]{.underline} single surface
sampling results, than the units undergoing just the prescribed window
treatments and associated final cleaning. Also, by applying clearance
lead dust standards for sills and troughs to single surface sample
results, a higher percentage of study units that received just the
prescribed window treatments would have "failed" clearance as opposed to
those units that underwent window replacement. As older window sashes
coated with many layers of lead-based paint continue to rub against the
window jamb, parting bead and stops, paint can chip off and fall onto
the sill and/or trough. Even when paint on window surfaces has been
stabilized, a sill has been stripped and repainted or replaced and a
trough cap has been installed, paint chips and debris can still be
generated due to ongoing friction of the window component surfaces. For
these reasons, appropriate state agency officials should consider
thoroughly reviewing prescribed window treatment specifications for
effectiveness.

The two-year results suggesting that window component dust lead loadings
remain much lower in window replacement units indicates that linking
retreatment to tenant turnover makes more sense than conducting annual
re-inspections.

5.  **More emphasis needs to be placed on properly adjusting and
    re-hanging doors to eliminate friction points.**

Many doors in the study units were still rubbing or binding after the
intervention had been completed. Furthermore, the independent visual
inspectors typically "passed" units in which one or more doors still
required adjusting and re-hanging. Owners and contractors need more
thorough training on how to properly address this prescribed treatment.
Additionally, visual inspectors must be trained to check each door
throughout a unit to make certain that it no longer rubs or binds, or
otherwise causes friction.

[^1]: Ten "lead hazard reduction treatments" are prescribed by the
    standard:

    Visual review of all exterior and interior painted surfaces;

    Removal and repainting of chipping, peeling or flaking paint on
    exterior and interior painted surfaces;

    Repair of any structural defect that is causing paint to chip, peel
    or flake that the owner of the affected property has knowledge of
    or, with the exercise of reasonable care, should have knowledge of;

    Stripping and repainting, replacing or encapsulating all interior
    window sills with vinyl, metal or any other material;

    Ensuring that caps of vinyl, aluminum, or any other material are
    installed in all window wells in order to make the window wells
    smooth and cleanable;

    Except for a treated or replacement window that is free of
    lead-based paint on its friction surfaces, fixing the top sash of
    all windows in place in order to eliminate friction caused by
    movement of the top sash;

    Re-hanging all doors necessary in order to prevent the rubbing
    together of a lead-painted surface with another surface;

    Making all bare floors smooth and cleanable;

    Ensuring that all kitchen and bathroom floors are overlaid with a
    smooth, water-resistant covering; and

    HEPA-vacuuming and washing the interior of the affected property
    with high phosphate detergent or its equivalent.

[^2]: Twenty-nine (29) units were not included primarily because the
    owners' grant applications were not approved.

[^3]: Clearance failure rates for the Baltimore HUD units are based on
    initial clearance testing conducted after treatment.

[^4]: For the purposes of this study, a treatment "failure" was defined
    as an observation by the LAAP inspector that one or more of the ten
    lead hazard reduction treatments prescribed in the statute had not
    been fully completed. Note that the Maryland statute did not specify
    a "de minimis" level above which the treatment was considered a
    failure; therefore, any observable deficient or missing treatment
    was classified as a "failure."

[^5]: Note that these geometric mean values were calculated using only
    values reported for units that had the specified type of "failure"
    reported. Units that did not have the specified type of "failure"
    reported were not included in the calculations.

[^6]: In a multiple regression model with backward elimination, all
    possible predictors of the outcome are initially entered into the
    model. Then hypothesis tests are run to determine if any factors can
    be removed from the predictive equation when the other factors are
    retained. The least significant factor (i.e., the factor with the
    largetst observed significance level) is removed and the process is
    repeated to determine if more factors can be dropped. In a logistic
    model with backward elimination, the outcome of interest is a binary
    response variable (e.g., "pass/fail"). In a Poisson regression model
    with backward elimination, the outcome of interest is a count
    variable (e.g., number of failures). The same backward elimination
    procedure described above for regression modeling was followed for
    both the logistic and the Poisson models.

[^7]: HUD/EPA guidance values of 100 µg/ft^2^ for floors, 500 µgft^2^
    for window sills, and 800 µg/ft^2^ for window troughs were in effect
    during the study period. New standards that became effective in
    September 2000 (40, 250, and 400 µg/ft^2^ were not in effect when
    immediate post-intervention data were collected and are therefore
    not discussed in this report.

[^8]: Clearance failure rates for Baltimore HUD units are based on
    initial clearance testing conducted after treatment, comparing
    results with floor, sill and trough standards of 100, 500 and 800
    µg/ft^2^, respectively.

[^9]: In a multiple regression model with backward elimination, all
    possible predictors of the outcome are initially entered into the
    model. Then hypothesis tests are run to determine if any factors can
    be removed from the predictive equation when the other factors are
    retained. The least significant factor (i.e., the factor with the
    largest observed significance level) is removed, and the process is
    repeated to determine if more factors can be dropped.

[^10]: In a Poisson regression model with backward elimination, the
    outcome of interest is a count variable (e.g., number of failures).