United States
Environmental Protection
Agency
EPA-600/R-97-137
December 1997
«?EPA Research and
Development
RESULTS OF A PILOT FIELD STUDY
TO EVALUATE THE EFFECTIVENESS
OF CLEANING RESIDENTIAL HEATING
AND AIR CONDITIONING SYSTEMS AND
THE IMPACT ON INDOOR AIR QUALITY
AND SYSTEM PERFORMANCE
Prepared for
Office of Radiation and Indoor Air
Prepared by
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
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(Phase read Inslructions on the reverse before comp ||| ||][ || [|||| ||||||| | j| || 11
J. REPORT NO. 2.
EPA-600/R-97-137
PB98-142011
4, T.TLE and subtitle Results of a Pilot Field Study to Eval-
uate the Effectiveness of Cleaning Residential Heating
and Mr-Conditioning Systems and the Impact on In-
door Air Quality and System Performance
5. REPORT DATE
December 1997
6. PERFORMING ORGANIZATION CODE
7. author(s) Fortmann and C.Gentry (A cur ex), and
K.Foarde and D. VanOsdell (RTI)
8. PERFORMING ORGANIZATION REPORT NO.
9, PERFORMING ORGANIZATION NAME AND AOORESS .
Acurex Environmental Corp., PC Box 13109, RTP, NC
27709; and Research Triangle Institute, PO Box
12194, RTP, NC 27709
10. PROGRAM ELEMENT NO.
11- CONTRACT/GRANT NO.
68-D4-0005/2-030 (Acurex)
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; FY95-FY96
14. SPONSORING AGENCY CODE
EPA/600/13
IS. SUPPLEMENTARY NOTES AppCD project officer ^ Rusgell M. Kulp, MaQ DrOP 54, 919/
541-7980.
16. abstract xhe report discusses and gives results of a pilot field study to evaluate the
effectiveness of air duct cleaning (ADC) as a source removal technique in residential
heating and air- conditioning (HA C) systems and its impact on airborne particle,
fiber, and bioaerosol concentrations. Data were also collected to assess the poten-
tial impact of cleaning on performance of the air handler and cooling system, The
study was conducted at EPA's Indoor Air Quality Test House and eight occupied
homes in the Research Triangle Park area of North Carolina. Week-long studies at
each home involved background air monitoring and sampling, cleaning of the HAC
system, and post-cleaning monitoring and sampling. Measurement parameters inclu-
ded airborne particle, fiber, and fungi concentrations; microbiological and dust de-
position sampling in the supply and return air ducts; various system related para-
meters including air flow, static pressure, temperature, and relative humidity; and
environmental parameters indoors and outdoors. Study results are presented on the
effectiveness of ADC, its impact on selected indoor air quality parameters, and an
assessment of its impact on system performance. Recommendations are provided on
future research needs.
17. KEY WORDS AND DOCUMENT ANALYSIS
a, DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c, COSATl Field/Group
Pollution
Cleaning
Ducts
Heating
Air Conditioning
Residential Buildings
Pollution Control
Stationary Sources
Indoor Air
13 B
13H
13 K
13A
13 M
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
228
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse
merit or recommendation for use.
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FOREWORD
The €. S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites and groundwater; and prevention and
control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost- effective environmental
technologies; develop scientific and engineering information needed by EPA to
support regulatory and policy decisions; and provide technical support and infor-
mation transfer to ensure effective implementation of environmental regulations
and strategies.
This publication has been produced as part of the Laboratory's strategic long-
term research plan. It is published and made available by EPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients.
E. Timothy Cppelt, Director
National Risk Management Research Laboratory
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ABSTRACT
The mechanical cleaning of heating, ventilating, and air conditioning (HVAC) systems, often referred
to as air duct cleaning (ADC), involves the physical removal of particulate matter and debris from air
distribution systems and air handler components. In recent years there has been a substantial increase in the
number of companies offering services for ADC of air conveyance systems in large buildings and in
residences. Despite some claims that ADC improves indoor air quality (IAQ) and reduces heating and
cooling energy costs, there is little published research data on the effectiveness of HVAC system cleaning or
its impact on IAQ and energy use for residential heating and air conditioning (HAC)systems, A research
program has been initiated by the U.S. Environmental Protection Agency (EPA) National Risk Management
Research Laboratory (NRMRL) Air Pollution Prevention and Control Division (APPCD) in conjunction with
the National Air Duct Cleaners Association (NADCA) to evaluate the effectiveness of HAC system cleaning
and its impact on IAQ and system performance in residential buildings.
To evaluate the effectiveness of HAC system cleaning in residences and its impact on IAQ and
system performance, a pilot field study was conducted in the Research Triangle Park area of North Carolina
during the summer of 1996. Participants were recruited into the study who had central (whole-house) cooling
systems and forced air distribution systems. The study was performed at die unoccupied EPA Indoor Air
Quality Test House and eight occupied houses that were purposefully selected, A week-long study was
performed at each home. Background air monitoring and sampling were performed for three days, then the
systems were professionally cleaned by NADCA. Cleaning of the air distribution ducts and air handler
components was performed using methods and equipment commonly used in the ADC industry, and accepted
for use by NADCA in this study. No proprietary methods or truck mounted systems were used in the study.
Source removal was performed by mechanical cleaning and chemical biocides were not used in the study.
Monitoring was performed again for two to four days following cleaning. Pre- and post-cleaning
measurements of particulate matter in the ducts was performed to assess duct cleaning effectiveness.
Measurements were also performed throughout the study period at each house to assess the impact of
cleaning on HAC system performance.
The results of the study demonstrated that the mechanical cleaning methods commonly used in the
HVAC system cleaning industry effectively removed particulate and fiber contamination from the system,
thus removing one potential source of particulate air contaminants in the study homes. Dust (particulate and
fibrous) levels on surfaces in the supply air ducts prior to cleaning ranged from an average of 1.5 to 26.0 g/m2
at the nine houses. Dust levels were higher in the return air ducts, ranging from an average of 5.3 to 35.1
g/m2. Post-cleaning dust levels ranged from 0.06 to 1.97 g/m2 and the average was 0.43 g/m2 for 58 samples
collected from the surfaces of supply and return ductwork with a medium volume dust sampler developed
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specifically for this study. Dust levels measured on duct surfaces with the NADCA Standard 1992-01
vacuum sampler method met the criterion of 1.0 mg/100 cm2 for demonstrating cleaning effectiveness at all
study homes.
Hie impact of mechanical cleaning without the use of chemical biocides on the levels of bacteria in
samples collected from the surfaces of the HAC system was highly variable. Bacterial pre-cleaning surface
levels in the ducts ranged from 5 to 1100 cfu/cm2 in the supply side and from 5 to 2300 cfii/cm2 in the return,
with a mean of less than 200 cfu/cm2 in most homes. Mean concentrations of bacteria in samples collected
from surfaces of return ducts were lower after cleaning in six of seven houses with return duct samples. But
the bacteria levels were lower in surface samples from the supply ducts in only four of the occupied homes
and the pre-cleaning versus post-cleaning difference was generally small.
Fungal levels on HAC system duct surfaces were generally higher than bacterial levels. Mechanical
cleaning without the use of chemical biocides had the most impact on the ducts with the highest levels of
fungi and noticeably reduced the level of fungi on ductwork surfaces in most houses.
There was no apparent relationship between levels of dust collected from surfaces of furnishings in the
study homes and the levels of dust measured on surfaces of the HAC system ductwork. There was also little
correlation between surface microbial loads and dust levels measured in the houses.
Indoor respirable (PM2 5) and inhalable (PM10) particle mass concentrations were low at the houses,
ranging from 4.2 to 32.7 ng/m3, consistent with results from past studies in houses without tobacco smoking
or other major sources. Differences in airborne concentrations of particle mass in the two size fractions
between pre-cleaning and post-cleaning periods were highly variable. There was no trend related to HAC
system cleaning. Comparison of indoor and outdoor particle mass concentrations suggested that the outdoor
concentrations had a substantial impact on indoor concentrations. Continuous measurements of particle
concentrations (particles/m3) also demonstrated the strong impact of outdoor concentrations. The study
results suggest that although the source of particulate matter in the HAC system was effectively removed, the
magnitude of the impact of HAC system cleaning on particle concentrations could not be quantitatively
determined due to the presence of other indoor sources, occupant activity, and the impact of outdoor particle
sources.
Airborne fiber concentrations were low at all houses, precluding an assessment of the impact of HAC
system cleaning on this parameter. Measurements of fibers with a continuous optical monitor suggested that
HAC system cleaning reduced airborne fiber concentrations at the EPA IAQ Test House and the house that
had the highest levels of fibers in the ductwork based on visual observation. There was no substantial effect
on fungal bioaersol concentrations following the mechanical cleaning of the HAC system without use of
chemical biocides.
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Measurements of parameters related to performance of the HAC system suggested that cleaning may
improve system performance. HAC system cleaning generally resulted in increased air flows in the system.
Air flows measured in the house at supply registers and difiusers increased 4 to 32% at eight of the houses.
The current to the air handler blower motor increased after cleaning at all houses where the measurement was
performed. Using data collected in the study for HAC system parameters, calculations were made to
determine the enthalpy across the cooling coil and to estimate the total heat removed by the coil for the two
houses that had the largest increase in return air flows. The estimated increase in the amount of heat removed
by the cooling coil was 14 and 23%, suggesting that there would be increased overall system efficiency.
Results of the study demonstrated that methods commonly used in the HVAC system cleaning industry
effectively removed particulate and fibrous materials from the HAC systems in the study homes. The
medium volume dust sampler developed for this study was shown to be an effective tool for quantitatively
assessing HAC system cleaning effectiveness. Measurements of HAC system parameters suggest that
cleaning should have a positive impact on energy use. But the impact could not be quantified in this study
due to the limited number of study homes and short duration of the study at each home. Neither the short-
term integrated sampling methods nor the continuous air monitoring methods could be used to assess the
impact of HAC system cleaning on airborne particulate or fiber concentrations due to the presence of other
indoor air contaminant sources. The results for the assessment of the impact of HAC system on IAQ
parameters, therefore, were inconclusive. Additional research using alternative methods would be helpful.
Further research would also help to quantify the impact of HAC system cleaning on energy use. The report
also suggests research on a number of other HVAC cleaning issues.
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Table of Contents
Section Page
ABSTRACT ii
LIST OF FIGURES viii
LIST OF TABLES ix
ACKNOWLEDGMENTS x
1.0 INTRODUCTION 1
1.1 Background ... 1
1.2 Study Objectives 2
1.3 Overview of the Study 3
2.0 SUMMARY AND CONCLUSIONS .4
2.1 Summary 4
2.2 Conclusions 9
3.0 RECOMMENDATIONS FOR FUTURE RESEARCH , 10
4.0 STUDY METHODS 12
4.1 Participant Recruitment and Selection Methods 12
4.2 Sample Collection and Analysis Methods 14
4.2.1 Measurement of Dust Levels in Ducts 15
4.2.2 Continuous Particle Monitoring Methods 17
4.2.3 Integrated Particle Sampling Methods 18
4.2.4 Fiber Monitoring and Sampling Methods 18
4.2.5 Fungal Air Sampling Methods 19
4.2.6 Microbial Surface Sampling Methods 21
4.2.7 Interior Surface Dust Sampling Method 22
4.2.8 Measurements in the Air Conveyance System 22
4.2.9 Temperature, Relative Humidity, and C02 Measurements 23
4.3 Survey Instruments and Data Collection Tools 23
4.4 Field Protocol 24
4.4.1 Sampling Locations 24
4.4.2 Protocol for Data Collection at Each Home 25
4.5 Initial Testing at the EPA Indoor Air Quality Test House 25
4.6 HAC System Cleaning Methods 27
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5,0 RESULTS AND DISCUSSION 28
5.1 Participant Recruitment and Screening Results 28
5.2 Characteristics of the Nine Study Homes 31
5.3 Description of the HAC System and HAC System Cleaning Methods 33
5.3.1 EPA Indoor Air Quality Test House 35
5.3.2 House Number 1 36
5.3.3 House Number 2 38
5.3.4 House Number 3 39
5.3.5 House Number 4 40
5.3.6 House Number 5 42
5.3.7 House Number 6 43
5.3.8 House Number 7 45
5.3.9 House Number 8 46
5.4 Duct Dust and Microbial Surface Loading Measurements 47
5.4.1 Duct Dust Mass Measurements Pre- and Post-Cleaning 48
5.4.2 Microbial Surface Loading Measurement Results 54
5.4.3 Surface Dust Samples 59
5.5 Measurement Results for Selected Indoor Air Quality Parameters 59
5.5.1 Respirable and Inhalablc Particle Mass Concentrations 60
5.5.2 Particle Concentrations Measured With Real-Time Monitors 65
5.5.2.1 Results of Climet Measurements 66
5.5.2.2 Measurement Results for the LAS-X 81
5.5.3 Concentrations of Airborne Fibers in the Study Homes 94
5.5.3.1 Test House SEM Results 98
5.5.3.2 House 1 SEM Results 98
5.5.3.3 House 2 SEM Results 98
5.5.3.4 House 3 SEM Results 98
5.5.3.5 House 4 SEM Results 99
5.5.3.6 House 5 SEM Results 99
5.5.3.7 House 6 SEM Results 99
5.5.3.8 House 7 SEM Results 99
5.5.3.9 House 8 SEM Results 99
5.5.4 Fungi Air Samples 100
5.5.5 Comparison oflAQ Measurement Results With Duct Dust Levels ,101
5.6 Heating and Cooling System Measurement Results 103
5.6.1 System Air Flow Rates 103
5.6.2 Measurements of Static and Differential Pressures 105
5.6.3 Air Handler Unit Blower Motor Current Readings 107
5.6.4 Coolant Line Temperatures 108
5.6.5 Estimates of Changes in Cooling Coil Heat Transfer Efficiency .... 108
5.7 Evaluation of Study Design, Field Protocol, and Test Methods 110
6.0 QUALITY ASSURANCE/QUALITY CONTROL 113
6,1 Quality Control Samples 113
6.1.1 Field Blanks 113
6.1.2 Method Precision and Bias 115
6.1.2.1 Method Precision 115
6.1.2.2 Method Bias 117
6.2 Method Performance 118
6.3 Data Completeness 119
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7.0 REFERENCES
121
APPENDIX A - Initial Evaluation of Methods for Sampling Dust From Heating, Ventilating, and Air
Conditioning System (Duct) Components - Interim Data Summary Report A-l
APPENDIX B - Floor Plans, HAC Diagrams, and HAC Equipment List
for the Study Homes B-1
APPENDIX C - Results for Samples of Dust Collected in the HAC at Nine Study Homes C-l
APPENDIX D - Results for Microbiological Samples Collected at the Nine Study Homes D-l
APPENDIX E - Climet Measurement Results for Particles in the Size Fraction
>5.0 pmDiameter E-l
APPENDIX F - Mean Concentrations of Particles in 16 Size Fractions Measured with the LAS-X
Pre- and Post-HAC Cleaning F-l
APPENDIX G - Results of Scanning Electron Microscopy Analyses of Samples Collected at the
Nine Study Homes G-l
Vll
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List of Figures
Title Page
Figure 5-1. Airborne particle concentrations in the >0,5 pm size fraction at the
Test House . .71
Figure 5-2. Airborne particle concentrations in the >0.5 pm size fraction at House 1 72
Figure 5-3. Airborne particle concentrations in the >0.5 pm size fraction at House 2 ...... 73
Figure 5-4. Airborne particle concentrations in the >0.5 pm size fraction at House 3 .74
Figure 5-5. Airborne particle concentrations in the >0.5 pm size fraction at House 4 75
Figure 5-6. Airborne particle concentrations in the >0,5 pm size fraction at House 5 76
Figure 5-7. Airborne particle concentrations in the >0,5 pm size fraction at House 6 77
Figure 5-8. Airborne particle concentrations in the >0.5 pm size fraction at House 7 .78
Figure 5-9. Airborne particle concentrations in the >0.5 pa size fraction at House 8 79
Figure 5-10. Airborne particle concentrations in the >5.0 pm size fraction at House 4 82
Figure 5-11. Airborne particle concentrations in the >5.0 pm size fraction at House 7 83
Figure 5-12a. Airborne particle concentrations measured with the LAS-X, Test House and
Houses 1-4 (0.1-1.0 pm) 84
Figure 5-12b. Airborne particle concentrations measured with the LAS-X, Houses 5-8
(0.1-1.0 pm) 85
Figure 5-12c. Airborne particle concentrations measured with the LAS-X, Test House and
Houses 1-4 (1.0 - >7,5 pm) 86
Figure 5-12d. Airborne particle concentrations measured with the LAS-X, Houses 5-8
(1.0->7.5 pm) ...87
Figure 5-13a. Mean particle concentration ratios measured with the LAS-X for
eight houses (0.1 - 0.75 pm) 89
Figure 5-13b. Mean particle concentration ratios measured with the LAS-X for
eight houses (0.75 - >7.5 pm) 90
Figure 5-14. LAS-X aerosol spectrometer measurement results at House 1 91
Figure 5-15. LAS-X aerosol spectrometer measurement results at House 5 92
Figure 5-16. LAS-X aerosol spectrometer measurement results at House 8 93
Figure 5-17. FAM-1 fiber measurement results at House 6 96
Figure 5-18. FAM-1 fiber measurement results at House 8 97
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List of Tables
Title Page
Table 4-1. Measurement Parameters and Methods 16
Table 4-2. Protocol For Week-long Studies at Each Home 26
Table 5-1. Characteristics of the Nine Study Homes 32
Table 5-2. Dust Levels Measured with the MVDS in the HAC System of Study Homes ... 49
Table 5-3. Comparison of Residual Duct Dust Mass Measurements With the MVDS
and the NADCA Vacuum Methods Following HAC System Cleaning .... 51
Table 5-4. Results of Duplicate Duct Dust Measurements With the MVDS 53
Table 5-5. Results of the Evaluation of Brushing Versus Air Washing — 54
Table 5-6, Results of Surface Samples of Bacteria in the Supply and Return Ducts 56
Table 5-7. Results of Surface Samples of Fungi in the Supply and Return Ducts 57
Table 5-8. Results of Surface Samples at the IAQ Test House 58
Table 5-9. Results of Measurements of Surface Dust on Furnishings 60
Table 5-10. PM2, Measurement Results 61
Table 5-11. PM10 Measurement Results 62
Table 5-12. Trends in Particle Concentrations and Indoor/Outdoor Ratios 64
Table 5-13. Mean Concentrations of Particles Greater Than 0.5 jim Pre- and Post-
HAC System Cleaning 67
Table 5-14. Mean Concentrations of Particles Greater Than 5.0 nm Pre- and Post-
HAC System Cleaning 69
Table 5-15. Airborne Fiber Concentrations in the Study Homes 95
Table 5-16. Fungal Air Sample Results 101
Table 5-17. Comparison of Duct Dust Levels and Airborne Particle Concentrations
Prior to HAC System Cleaning 102
Table 5-18. Supply and Return Air Flow Rates 104
Table 5-19. Static and Differential Pressure Measurements 106
Table 5-20, Air Handler Blower Motor Current Measurement Results 107
Table 5-21. Coolant Line Temperature Measurements 109
Table 6-1. Data Quality Indicator Goals For Parameters Measured in the Project 114
Table 6-2. Results of Duplicate Duct Dust Measurements With the MVDS 115
Table 6-3. Summary of Data Completeness 120
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ACKNOWLEDGMENTS
The success of this project was the result of the work and input of a number of people. The
authors wish to acknowledge the efforts of all those who contributed to the design, implementation,
analysis, and reporting of this study.
Overall project goals were provided by Russell Kulp with the assistance of Marc Menetrez and
the Ventilation Research Team of the Air Pollution Prevention and Control Division of the U.S.
Environmental Protection Agency (EPA) National Risk Management Research Laboratory,
The project was a joint effort of the EPA and the National Association of Air Duct Cleaners
(NADCA) under the Cooperative Research and Development Agreement (CRADA) File Number
0129-96. Robert Krell served as the Project Manager for NADCA.
A number of staff members of Acurex Environmental assisted the authors on the technical
activities of the project. Sam Brubaker assisted in preparation and calibration of the instrumentation
used in the study. He also played a key role in the field data collection effort. Laura Beach provided
support on quality assurance activities.
Staff of Research Triangle Institute were responsible for collection and analysis of the
microbiological samples. Eric Meyers was responsible for collecting the field samples.
Representatives of the National Air Duct Cleaners Association were responsible for cleaning the
heating and air conditioning air conveyance systems at the nine study homes. Tim Hebert, the
Principal Investigator for NADCA, provided the required logistics support and excellent technical
input to the study in addition to his efforts on the cleaning of the systems. He was assisted by Charles
Cochrane, Bob Krell, Tim Bray, Frank Copeland, Tom Gwaltney, and Tom Yacobellis.
Equipment for cleaning the heating and air conditioning systems in the homes during this study
was provided by manufacturers and distributors. Their support was important to the success of the
project.
The authors would like to thank all of the homeowners who responded to the request for study
participants. We would especially tike to thank the eight homeowners who were selected for the study
and allowed us to enter their homes numerous times for collection of samples and information. Their
participation has enabled us to meet the study objectives and has helped us gain a better
understanding of the air conveyance system cleaning and its impact on indoor air quality and system
performance.
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1.0 INTRODUCTION
Source removal cleaning of heating and air conditioning (HAC) systems, also referred to as air duct
cleaning (ADC), involves the physical removal of particulate and fibrous matter and debris from air
distribution systems and air handler components. ADC services are offered for all types of buildings,
including residences. There is currently little published research data on the effectiveness of air duct cleaning
or its impact on indoor air quality (IAQ) and energy use for residential heating and cooling (HAC) systems.
A research program has been initiated by the U.S. Environmental Protection Agency (EPA), National Risk
Management Research Laboratory (NRMRL), Air Pollution Prevention and Control Division (APPCD) in
conjunction with the National Air Duct Cleaners Association to evaluate the effectiveness of HAC system
cleaning and its impact on IAQ in residential dwellings.
1.1 Background
In recent years there has been a substantial increase in the number of companies offering ADC services.
The services are offered for large heating, ventilating, and air conditioning (HVAC) systems in office
buildings, public access buildings, health care facilities, and special use facilities. The services are also being
offered for residential HAC systems. Some advertisements claim that air duct cleaning will improve IAQ,
reduce allergies, and lower energy costs, and improve system performance. There is little published research
data on which to base a decision on when a system should be cleaned or on its effect on either system
performance or IAQ.
A recent research project to evaluate ADC involved testing at 33 homes in Montreal, Canada (Fugler and
Auger, 1994). Cleaning was performed by commercial companies using (1) portable vacuum cleaners and
brushes, (2) portable vacuums and compressed air, (3) truck-mounted vacuum systems, or (4) truck-mounted
vacuum and "skipper ball" to dislodge duct dust. Measurements were made of blower fan current and voltage,
static pressure, air flow rates, airborne particle concentrations, and airborne bacteria and mold levels. The
results of the study were inconclusive. The measurements in the study were of such limited scope that it is
difficult to draw conclusions from the study. The authors reported that air flows did not change significantly
due to cleaning. But, air flow rates before and after cleaning were measured at a subset of only three supply
registers and the authors admit that damper settings may have changed following cleaning. Airborne dust
levels measured at supply registers did not change significantly after cleaning. Sampling for airborne
particulate was limited to collection of very short-term samples before and after cleaning. Data were only
used for samples collected at the ducts. Data were not used on room concentrations because the authors
believed occupant movement around the samplers invalidated the test results. The study results indicated a
decrease in the concentration of microorganisms (fungi and bacteria) on surfaces of just over 50% of the
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ducts sampled. There was also a decrease in airborne concentrations of bacteria and fungi although the
decrease was not statistically significant.
Another recent study involved ADC at eight residences (Ahmad et al., 1994). The researchers observed
that short-term airborne particles levels increased during cleaning. They observed lower airborne particle
levels after cleaning. They also reported that bioacrosol concentrations were lower after cleaning.
In a literature survey presented in the Air Infiltration Review (AIVC, 1993), it was reported that Pejtersen
et al. evaluated the effect of cleaning of the HVAC system on occupants' perceptions on indoor air quality and
concluded that cleaning tends to improve indoor air quality. The survey also states that Pjnakka and Jyrkiinen
reported that particle concentrations in indoor air were three times higher during cleaning than after cleaning.
The literature survey includes data showing that the average surface dust mass in supply ducts was 6.8,10.6
and 18.2 g/m2 in three studies of schools and office buildings.
With the exception of these studies, little is known about the impact of ADC on IAQ and system
performance in residences. This is of particular concern because the typical homeowner may not have
adequate knowledge about the HAC system to determine whether cleaning should be performed. As discussed
by O'Neil and Kulp (1995), the potential economic and public health reasons are significantly sufficient to
warrant research on HAC system cleaning.
1.2 Study Objectives
The objectives of this project included the following:
* Evaluate sampling and analysis methods that may be used to quantitatively assess the effectiveness
of cleaning (source removal) of non-porous ductwork and components of residential HAC systems,
• Evaluate monitoring, sampling, and analysis methods to determine if the methods can be used to
quantitatively assess the impact of source removal from HAC systems on airborne particulate and
fiber concentrations,
* Collect information on the effectiveness of currently available cleaning methods for removal of dust
and debris from air conveyance systems in residences,
• Collect information on the impact of ADC on airborne particulate and fiber concentrations in
residences,
* Collect information on the impact of cleaning on the performance of the air conveyance system in
residences,
• Evaluate the impact of the type of duct material and duct configuration on HAC system cleaning
methods, and
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* Collect information that can be used to develop a research strategy for further assessing the
effectiveness and impact of HAC system cleaning in residential and non-residential buildings,
1.3 Overview of the Study
To evaluate the effectiveness of HAC system cleaning in residences, a pilot field study was conducted in
the Research Triangle Park area of North Carolina during the summer of 1996. Participants were recruited
into the study who had central (whole-house) cooling systems and forced air distribution systems. The goal
was to obtain eight study homes with a variety of duct material types and configurations. A week-long study
was performed at each home. Background monitoring mid sampling of airborne particles and fibers were
performed for three days, then the air conveyance system was professionally cleaned NADCA. Cleaning of
the air distribution ducts and air handler components was performed by source removal practices commonly
used in the HVAC system cleaning industry. Cleaning involved use of high volume vacuum (negative air)
systems, brashes, forced-air nozzles, and hand vacuuming. Specific cleaning methods varied according to the
type of duct materials, duct configurations, and accessibility. Monitoring and air sampling were performed for
at least two days following cleaning. Pre- and post-cleaning measurements of particulate matter in the ducts
was performed to assess duct cleaning effectiveness. Measurements were also performed to assess the impact
of ADC on air handler performance. Prior to the field study, testing was performed at the un-occupied EPA
IAQ Test House (TH) in Cary, NC to evaluate the impact of ADC under more controlled conditions and to
evaluate the test protocol and methods for the field study.
To accomplish the objectives of this project, the following work activities were performed;
* Participants were recruited for the study and an initial screening questionnaire was completed to
collect information for selecting participants,
* An initial screening visit was made at potential study homes to assess the type of duct materials,
duct configuration, accessibility for cleaning, relative level of dust and debris in the ducts, and factors
related to logistics for participation in the field study,
* Methods and protocols for collection of dust samples from the ducts, for continuous air
monitoring, integrated air sampling, and other data collection at the homes were finalized based on
results from previous testing in a pilot scale test facility (VanOsdell et al., 1997),
* Instrumentation was calibrated and prepared for the field study,
* Study protocols, test methods, and analysis methods were evaluated during the initial cleaning
experiment at the TH,
* The field study was performed at eight occupied homes,
* Sample analysis was performed, and
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• Data processing, validation, and analysis were performed for preparation of this final report.
This report presents the results of the field study. The results presented in this report represent an initial
effort to obtain a better understanding of HAC system cleaning procedures, their advantages and limitations,
cleaning effectiveness, and the impact of system cleaning on selected IAQ parameters (particles, fibers, and
bioaerosols) and the performance of heating and cooling systems in residences. The research project was, of
necessity, limited in scope. Because of the limited number of homes sampled, statistical analyses could not be
performed to determine the significance of the results. However, the results show trends that may be useful in
assessing the impact of system cleaning. The results provide information that can be used to formulate and
develop future research programs in this area, both as they relate to residential dwellings and large buildings.
2.0 SUMMARY AND CONCLUSIONS
Results of the study are summarized below. Conclusions supported by the study are provided in the
following subsection.
2.1 Summary
• The heating and air conditioning system, including the ductwork, air handling unit (AHU), and
associated components, were cleaned at the EPA Indoor Air Quality Test House and eight occupied field
study homes by professional HVAC system cleaning contractors representing NADCA, Inc. The systems
were cleaned by practices commonly used in the HVAC system cleaning industry and accepted by NADCA
for this study. No proprietary methods were used. Truck-mounted systems were not used in the study.
Source removal involved mechanical cleaning. Chemical biocides were not used in this study.
• Various parameters related to indoor air quality and performance of the HAC system were measured for
two to four days prior to cleaning and again during a two to four day period following cleaning. The IAQ
parameters measured included particle mass concentrations (PM2 5 and PM10), particle concentrations
(partieles/m3), fiber concentrations, and airborne fungi concentrations. Parameters related to the performance
of the AHU included air flows for the supply and return air, static and differential pressures, coolant line
temperatures, AHU blower motor current, supply and return temperature and relative humidity (RH), and
system on-time. Additionally, temperature and RH were measured indoors and outdoors,
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• To assess the effectiveness of HAC system cleaning, the levels of dust (particulate and fibrous
combined) were measured in the supply and return ducts prior to, and following, HAC system cleaning using
a medium volume dust sampler (MVDS) developed for this study (Fortmann 1996c). Microbial loading on
duct surfaces was evaluated using a vacuum/filter method for collection of samples from a defined area.
* Eight owner-occupied homes were purposefully selected for the study, which was conducted in the
Research Triangle Park area of North Carolina during the summer of 1996. Selection of the homes was based
on the type of ductwork materials, the configuration of the HAC system, potential complexity of cleaning,
and the relative amount of dust and debris in the system. The homes cleaned include single-story, split-level,
and two-story homes. The AHU and most of the ductwork were located in a crawl space under the house at
six of the eight occupied field study houses. Additionally, monitoring and HAC system cleaning were
performed at the unoccupied EPA Indoor Air Quality Test House.
• Dust levels in the ducts prior to HAC system cleaning ranged from a mean concentration in the supply
ductwork of 1.48 to 26,03 g/m2 at the nine houses. The mean dust level in the return air ducts of the nine
homes was substantially higher, ranging from 5.26 to 35.11 g/m2. Samples of dust were collected from the
surface of the cooling coil at some homes, but the vacuum sampler method was not effective for the coil
surface. Visual inspection of cooling coils was more useful for assessing the relative amount of material on
the surface.
* The equipment, methods, and cleaning practices employed in this study were effective for removing dust
and debris from the HAC system. Visual inspection indicated that the dust and debris were effectively
removed. Dust samples collected with the MVDS demonstrated that the residual dust after cleaning ranged
from 0.06 to 1.97 g/m2. For all 58 samples collected in the supply and return air ductwork after cleaning the
HAC system at the nine study homes, the mean was 0.43 ± 0.34 g/m2,
• Measurements of residual dust on ductwork surfaces after HAC system cleaning with the NADCA
Standard 1992-01 vacuum method ranged from 0,01 to 0.36 mg/100 cm2, meeting the NADCA criterion that
residual dust must be less than 1.0 mg/100 cm2 to demonstrate that the cleaning was effective. Side-by-side
measurements with the NADCA vacuum method and the MVDS, which was developed for this study, showed
that the collection efficiency of the MVDS was higher than the NADCA method. If the MVDS is used for
post-cleaning dust sampling, the results suggest that the criterion for demonstrating that source removal
cleaning is effective should be higher, probably 5 mg/100 cm2.
* The impact of mechanical cleaning without the use of chemical biocides on the levels of bacteria in
samples collected from the surfaces of the HAC system was highly variable. Bacterial pre-cleaning surface
levels in the ducts ranged from 5 to 1100 cfu/cm2 in the supply side and from 5 to 2300 cfu/ctrr in the return,
with a mean of less than 200 cfu/cm2 in most homes. Mean concentrations of bacteria in samples collected
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from surfaces of return ducts were lower after cleaning in six of seven houses with return duct samples. But
the bacteria levels were lower in surface samples from the supply ducts in only four of the occupied homes
and the pre-cleaning versus post-cleaning difference was generally small.
• Mechanical cleaning without the use of chemical biocides had the most impact on fungi levels in surface
dust at the homes with the highest fungi concentrations in the dust. HAC system cleaning reduced the levels
of fungi in samples collected from HAC system surfaces in most homes, although the magnitude of the
impact varied.
• There was little correlation between surface microbial loads and dust levels measured in the houses. This
was unexpected because usually dust or dirt and microorganism levels correlate well. It may be that the
composition of duct dust in this study had a high level of debris which would effectively dilute the microbial
concentrations as measured per surface area.
• Indoor respirable (PM2 5) and inhalable (PM,0) mass concentrations in 24-hr integrated samples, were
generally low at the houses, ranging from 4.2 to 32.7 ng/m3, The concentrations were consistent with data
previously reported for homes without smoking or other major indoor particle sources (Wallace, 1996).
• Indoor respirable (PM2 5) and inhalable (PM,n) particle concentrations in air samples collected after HAC
system cleaning were not substantially different from the samples collected prior to HAC system cleaning.
The ratio of the post-cleaning concentrations to the pre-cleaning concentrations of respirable particles
measured indoors was greater than 1.0 at seven of the nine houses. At all but one of these seven houses, die
post-/pre-c!eaning ratio was also greater than 1.0 for the outdoor respirable particle concentrations. The post-
cleaning/pre-cleaning ratios of PM10 concentrations indoors and outdoors followed similar, but less clear
trends. The measurements of respirable and inhalable particle mass concentrations indoors and outdoors
suggest that, during this study, the indoor concentrations were strongly impacted by outdoor concentrations.
They may also have been impacted by occupant activity and other indoor sources.
• Measurements of particle concentrations (particles/m3) indoors with a two-channel laser particle counter
and a 16-channel laser aerosol spectrometer also did not show substantial differences in airborne particle
concentrations before and after HAC system cleaning. The mean concentrations of particles in a >0.5 fim size
fraction measured indoors following HAC system cleaning were lower only at the Test House and at two of
the eight field study houses. The post-cleaning/pre-cleaning ratio was near 1.0 at two houses, but higher than
1.0 at the other four occupied field study homes. Measurement results at two houses that were cleaned on the
same week and located across the street from each other suggest that the outdoor particle levels had a strong
impact on indoor particle concentrations. At these houses indoor particle concentrations increased on the
same days of the week following cleaning, even though AHU operation patterns and occupant activities
differed dramatically at the two houses. The data suggest that changes in airborne particle concentrations as a
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result of HAC system cleaning may not be measurable with the methods used in this study due to the presence
of other sources of particles indoors, including outdoor sources and occupant activity, and temporal
variability of particle concentrations.
* Comparison of the level of dust measured in the supply and return ductwork and the airborne particle
concentrations and particle mass concentrations prior to HAC system cleaning did not show any substantial
relationship.
* Concentrations of airborne fibers were low at all homes, precluding an assessment of the impact of HAC
system cleaning on airborne liber concentrations. Measurements with a continuous optical monitor suggest
that HAC system cleaning reduced airborne fiber concentrations at the Test House and at a house that had
heavy deposits of fibers visible in the ductwork prior to cleaning. But the data set is insufficient to draw any
conclusions.
«Mechanical cleaning of the HAC system without the use of chemical biocides did not appear to impact
fungal bioaerosol concentrations at the nine study homes; With the exception of one house, there was no
substantial difference between the pre-cleaning and post-cleaning bioaerosol samples. Similar to the
particulate measurements, the failure to determine a difference in concentrations before and after cleaning
may be related to the presence of other sources and the variability of airborne concentrations of fungi,
* Measurements of parameters related to performance of the HAC system suggest that cleaning had a
positive impact on system performance. Cleaning of the HAC system generally resulted in increased air flow
to the house. Supply air flows increased between 4 to 32% at eight houses based on measurements at the floor
registers and diffusers in the house. Some of this increase in supply air flow rates may have been attributable
to minor repairs of leaks in the ducts and at loose floor boots of supply registers. Return air flows measured
at the return air grilles in the house increased 14 and 38% at two houses, but were not substantially different
after cleaning at the other seven houses. Because of the small sample size (nine houses), the limited number
of measurements, and the short duration of the study period at each house, the magnitude of the impact of
HAC system cleaning could not be quantified in this study.
* AHU blower motor current increased after HAC system cleaning at the four field study houses where
measurements were performed. Static pressure increased in the return air ductwork at the six houses with
complete measurements. The increase in blower motor current and increase in static pressure in the return
ducts suggest improved system performance. There was no clear trend for changes in static pressure in the
supply ducts or the differential pressures across the coil. Coolant line surface temperatures did not provide
useful information,
* Example engineering calculations made to estimate the change in heat transfer for the cooling coil
following HAC system cleaning suggest that HAC system cleaning may improve system performance. Using
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data for House 5, which had a 38% increase in return air flow, and House 6, which had a 14% increase in
return air flow, the estimated increase in heat transfer for the cooling coils was 14% at House 5 and 23% at
House 6. Changes of this magnitude would likely result in improved overall system efficiency. However, the
data from this study are inadequate to calculate overall system efficiency.
• Cleaning of the HAC system in the study homes, which had floor areas of 1500 to 2000 ft2, was
accomplished by two to three workers during an eight to ten hour period. This level of effort was required to
adequately clean and inspect all supply and return grills, the air handler components, and the ductwork. To
effectively clean all surfaces required a combination of cleaning methods, including hand vacuuming, and
routine inspection and re-cleaning, as required.
• A limited scope evaluation of the impact of brushing on HAC system cleaning demonstrated that
airwashing alone with the ductwork under negative pressure removed a substantial amount of the dust in the
ductwork, but that brushing in conjunction with airwashing was required to clean the ductwork effectively.
The data suggest that airwashing alone may not effectively remove contaminants from HAC systems.
• Many of the heating and air conditioning systems at the occupied homes of the study had design and
maintenance deficiencies that would be expected to result in significant energy losses, and in some cases,
might result in adverse impacts on occupant comfort and indoor air quality. External insulation on ductwork
was deteriorated or inadequate in many cases. Duct leakage was substantial at some homes. Loose floor
boots and poor ductwork construction were observed at many of the homes. Internal fibrous glass duct liner
in the AHU supply plenums and in bullhead plenums were contaminated with fungal growth at some of die
homes.
• Most homeowners that participated in the study had limited knowledge about their AHU and ductwork.
They could not provide accurate information about the HAC system during participant screening and were
unaware .of deficiencies in their system. Homeowners whose condensate drain lines were improperly installed
or not working properly were either unaware of the problem or not concerned. Homeowners were generally
not aware of the significant impact of deteriorating external insulation or duct leakage on energy costs for
heating and cooling. They were generally not aware of design deficiencies or obvious maintenance problems.
• Potential participants had difficulty providing accurate information about their air handlers and dud
systems during the screening phase of participant recruitment because of a lack of knowledge about their
systems. This had an impact on the recruiting and screening effort. They also had little knowledge about HAC
system cleaning methods and practices. The results of this study suggest that homeowners will require a
substantial amount of educational material related to residential heating and cooling systems and the air
conveyance system in addition to material about HAC system cleaning methods in order to make informed
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decisions about when to have HAC system systems cleaned, how to select a qualified HAC system cleaning
contractor, and how to evaluate the work performed. .
2.2 Conclusions
• The results of the nine home pilot study demonstrated that mechanical cleaning methods and equipment
commonly used by HVAC system cleaning contractors effectively removed particulate and fibrous contamination
from the HAC systems, thus removing one source of particulate contamination in the study homes,
* The impact of HAC system cleaning on bacteria levels on surfaces of HAC systems was variable in the
study. However, the impact of HAC system cleaning on bacterial contamination on surfaces was not fully
evaluated in this study because chemical biocides, which are frequently used by HVAC system cleaning
contractors, were not used at the study homes.
• Mechanical cleaning without use of chemical biocides had the greatest impact on fungi concentrations in
surface dust samples at the homes with the highest fungal levels in the duct. The levels of fungi in surface
samples were lower following HAC system cleaning at most of the homes.
* The impact of HAC system cleaning on airborne particle concentrations, airborne fiber concentrations,
and bioaerosols could not be determined in this study. There was no clear trend in the changes in
concentrations after HAC system cleaning. The study results suggest that because of the presence of other
indoor sources, occupant activity, outdoor contaminant sources, and temporal variability in particle
concentrations, it will be difficult to detect changes resulting from HAC system cleaning by air sampling and
monitoring methods.
* Measurements of HAC system-related parameters at the study homes suggest that HAC system cleaning
may improve HAC system performance. This was indicated by increased air flows and AHU blower motor
current Due to the limited scope of this study, the magnitude of the impact of HAC system cleaning could not
be quantified.
• The medium volume dust sampler developed for this study was demonstrated to be an effective tool for
quantitatively assessing HAC system cleaning effectiveness.
»The study results demonstrated that neither the short-term integrated air sampling methods nor the
continuous air monitoring methods could be used to assess the impact of HAC system cleaning on airborne
particulate or fiber concentrations due to the contribution from other contaminant sources and temporal
variability of air contaminant concentrations.
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3.0 RECOMMENDATIONS FOR FUTURE RESEARCH
The results of this study were useful as the first phase for evaluating the impact of HAC system
cleaning on selected IAQ parameters and performance of air conveyance systems in homes. Because of the
limited scope of the current study, the statistical significance of the results could not be determined. However,
the study results will be useful in developing a strategy for future research on HAC system cleaning. Based on
the results of this study, the following recommendations are made:
• An alternative approach should be developed for determining the impact of HAC system cleaning on
airborne particle, fiber, and bioaerosol concentrations. The results of this study show that changes in airborne
concentrations of air contaminants that may result from HAC system cleaning can not be determined by either
integrated short-term sampling or continuous monitoring methods used in this study for pre- and post-
cleaning measurements of airborne particle mass, particle counts, fiber concentrations, or bioaerosol
concentrations. An alternative technical approach may require other instrumentation, long-term monitoring,
and more comprehensive measurements. Testing in homes with higher dust levels in the HAC system may
make it easier to measure changes in air contaminant concentrations due to HAC system cleaning. Longer
term studies are required to distinguish between the impact of cleaning and occupant activities on indoor air
contaminant concentrations.
• Testing to assess the impact of HAC system cleaning on indoor air quality parameters should be
performed in test facilities where human activity and indoor sources can be controlled and well-documented.
Tests should be performed in the new Pilot Scale HAC Test Facility (PSTF) at EPA to determine how HAC
system cleaning affects IAQ parameters in the short- and long-term. Tests can also be conducted at the EPA
Indoor Air Quality Test House, which provides a realistic test system where indoor sources of particles and
fibers can be controlled and documented.
• Additional testing should be performed in the PSTF at EPA to determine the impact of HAC system
cleaning on the performance of the HAC system. Improved air handler/condenser efficiency may be the most
significant impact of HAC system cleaning. It is important to determine the magnitude of the effect, the
potential energy savings, and the pay-back period for HAC system cleaning costs. If significant energy
savings can be demonstrated that warrant the costs of cleaning, any coincidental improvement in indoor air
quality, even if it can not be demonstrated, may be a no-cost benefit. The new PSTF is ideally suited for this
type of testing because the cooling coil can be artificially loaded with varying levels of dirt and fiber and the
required parameters can be measured accurately and precisely over extended time periods.
• Research is needed to systematically and quantitatively measure fungal emissions under a variety of
environmental conditions to allow informed assessments of the significance of surface microbial
measurements. A commonly advertised justification for residential HAC system cleaning is to reduce and
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control allergies, many of which are related to fungal contamination. Emissions from fungal HAC system
contamination have been shown (Morey and Williams, 1991) to have a direct impact on indoor
biocontamination.
• Research should be undertaken to evaluate the short and long-term efficacy of biocides and encapsulants
used following HAC system cleaning over a reasonable range of HAC system environmental conditions.
HAC system cleaning was found in many cases to significantly reduce the levels of surface microbial
contamination in the tested duct systems. The most important issue with regard to HAC system cleaning,
however, is the prevention of microbial regrowth on cleaned HAC system surfaces. Biocides and/or
encapsulants are sometimes recommended and used on microbially contaminated HAC system systems to
contain debris and prevent regrowth.
• Research should be performed to evaluate cleaning of other types of duct surfaces in addition to the
galvanized sheet metal surfaces, that were the focus of this study. Many HVAC system cleaning contractors
claim to be able to clean duct systems with internal fibrous glass liner. The cleaning methods, effectiveness,
the impact of HAC system cleaning on the duct materials, and the impact on indoor air quality, specifically
airborne fiber concentrations, should be evaluated.
* A test method needs to be developed to quantitatively measure the mass of dirt and fiber on porous
surfaces. Both a research method and a practical field method are required. The method must have a
sufficiently high collection efficiency without removing fibers and liner material from surfaces that have been
cleaned.
* Research on HAC system cleaning effectiveness and its impact on IAQ and energy use should be
expanded to include the systems in large buildings. The impact of HAC system cleaning may be much more
significant in large buildings because of the higher cooling loads and energy costs. Many buildings have
significant indoor sources of particles and fibers that accumulate in the HAC system. Initial studies should
focus on only a few buildings and involve long-term measurements prior to, and following, cleaning to obtain
accurate data on IAQ and HAC system performance.
• Additional research is recommended to develop a system for determining when HVAC system cleaning
should be performed in various types of buildings and HVAC systems. Criteria need to be developed so that
building owners and operators can make an informed decision on when to have the HVAC system cleaned.
~ Information needs to be provided to homeowners to assist them in determining when to have their
residential HAC system cleaned, how to select a cleaning contractor, and how to evaluate the work that was
done. The EPA has already started work on an informational brochure for this purpose. Results of the
participant screening process and interaction with the homeowners participating in this study, suggest that
homeowners have limited knowledge about heating and cooling systems and ductwork. The informational
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brochure should include educational material on the HAC system as well as detailed information about HAC
system cleaning methods and the potential benefits.
~ Although this study has focused on the effectiveness and impact of HAC system cleaning, a reactive
approach to duct contamination problems, research is needed to develop effective strategies for preventing
contamination of heating, ventilating, and air conditioning (HVAC) systems with particulate, fibrous,
microbiological, and volatile organic contaminants. This research may include studies of various filtration
technologies and practices, evaluation of HVAC designs and equipment, research on controlling humidity
levels and condensation problems, and developing guidance for building owners and HVAC operators.
4.0 STUDY METHODS
This section describes the methods used in the field study including participant recruitment, participant
selection, the field study protocol, and the sample collection and analysis methods.
4.1 Participant Recruitment and Selection Methods
The study involved testing at the U.S. EPA Indoor Air Quality Test House located in Cary, NC and eight
occupied homes located in the Research Triangle Park area of North Carolina (Raleigh, Cary, Apex, Durham,
and Chapel Hill). The eight homes included in the study were purposefully selected; they were not selected at
random. The following criteria were used to determine the eligibility of potential study participants:
• The participant must own the home,
* There may not currently be smoking of tobacco products in the home, and
• The home must have a central cooling system with forced air distribution that was expected to be used
during the study.
Homes were not used in the study where smoking of tobacco products occurred indoors because the high
emissions of particles from environmental tobacco smoke would make it difficult to interpret particle
monitoring and sampling data. Because the study was conducted in the summer, homes had to have a central
cooling system that the occupants intended to use during the study period.
A number of criteria were considered for selection of the homes, including the following:
Characteristics of the HVAC
(1) Type of duct materials
(2) Level of particulate matter arid debris in the ductwork
(3) Accessibility of the ducts for cleaning (i.e., difficulty of cleaning)
Age of the ductwork and air handler
History of duct cleaning
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Type of heating system (heat pump, gas furnace, oil, electric heating coils)
Type of cooling system (central, window/wall, natural ventilation)
Size of system (heating/cooling capacity, fan speed or duct air velocity)
Number of main and branch ducts
Configuration of ducts
Type of particulate filter used in the system
Characteristics of the Occupants
Number of adults
Number of children
Number of pets (eats or dogs)
Type of cooking range
Extent of cooking performed (average number of meals/week with range)
Other sources (e.g., hobbies performed indoors)
Ventilation habits - Extensive window openings vs. year-around closed windows
Reported complaints about dust problems
Characteristics of the Structure (Home)
Age of the home
Size (ft2)
Number of floors
Sub-structure (slab-on-grade, crawl space, or basement)
Location (inner city, suburban, rural)
Type of yard (grass, dirt)
Amount of dust on indoor surfaces
In consultation with the EPA Project Manager, items 1 through 3 listed above were defined as the primary
selection criteria. Many of the other parameters listed may have an impact on the first three criteria,
particularly with respect to the level of dust and debris in the air conveyance system, but were determined not
to be primary criteria for selecting the study homes. The goal was to obtain homes with different types of
duct materials, including: (1) un-lined galvanized ducts, (2) internally lined (fibrous glass duct lining), non-
microbially contaminated ducts, and (3) flexible ducts. In consultation with the NADCA representatives
performing the HAC system cleaning, it was determined that participant homes could have only one air
handler. Large homes with two air handlers could not be cleaned in one day, which was essential to meet the
requirements of the monitoring and sampling schedule. To the extent possible, homes were selected that had
differing amounts of dust and debris in the ducts. The level of dust and debris in the ducts was determined by
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visual inspection and by collection of duct dust samples using the MVDS during the initial screening visit.
Homes were selected that had varying levels of complexity of duct materials and configurations so that HAC
system cleaning effectiveness could be evaluated under a variety of conditions.
Homes with fiberboard duct materials were not included in the study due to the difficulty of cleaning and
the potential for damaging internal surfaces of the ducts. Homes with internally-lined (insulated) ducts were
to be included in the study if there was no visible indication of fungal contamination or historical information
that would indicate potential microbial contamination of the duct liner. These homes were not included in the
study because the current EPA recommendations are that microbial-contaminated fibrous glass duct liner be
replaced rather than cleaned (U.S. EPA, 1991). Homes with known or suspected microbial contamination of
un-lined galvanized ducts were included in the study because there are accepted methods for cleaning them
(NADCA, 1992; NADCA, 1995).
Potential candidate homeowners were initially screened by telephone using a 42 question Participant
Screening Questionnaire. The questionnaire was designed to first determine eligibility, then to collect
information on the home, air conditioning system, and the occupants in order to assess their potential
suitability for use in the study. Information collected with the screening questionnaire was used to select
eight candidates for the second phase of screening, a visit to the house.
Each of the candidate homes was visited to verify eligibility for the study, to determine the type of duct
material, to inspect the air handler and ductwork, and to assess the level of dust and debris in the ducts. The
Acurex Environmental principal investigator visited all of the homes so that the suitability of the homes could
be compared. Responses to the screening questionnaire were verified during the visit and additional
information was collected on the characteristics of the heating and cooling system and the ducts in the home,
Components of the HAC system were inspected to assess the level of dust and debris in the system. At some
homes, samples of dust in the HAC system were collected using the MVDS from the supply and return ducts
if access could be obtained through return air grilles, existing access panels, or duct end caps. In most homes,
the level of dust was assessed by visual inspection only.
A number of homes were determined to be ineligible or unsuitable for the study during the site visits.
When this occurred another home was selected and visited. A total of 19 homes were visited in order to select
eight homes for the study. The homes were ranked according to suitability for die study based on the
selection criteria. Recommendations were provided to the EPA Project Manager who approved final selection
of the homes. A second visit was made to some of the homes selected for the study so that a NADCA
representative could inspect the house and the HAC system in order to prepare for cleaning, including
selection of cleaning methods and equipment.
4.2 Sample Collection and Analysis Methods
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A number of parameters were measured at each home during the study. Measurements were made using
continuous (real-time) monitors for particles, fibers, and environmental parameters; integrated sampling
methods for particles, fibers, and bioaerosols; and bulk sampling methods for dust and fungi in the HAC
system. The measurement parameters and sampling and analysis methods are summarized in Table 4-1 and
described below. The protocol for sampling is described in a following sub-section.
The primary contaminants measured at the study homes were particles, fungi, and fibers. Both real-time
monitoring and integrated sampling methods were used for particle measurements.
4,2,1 Measurements of Dust Levels in Ducts
The level of dust in ducts (g/m2) was determined by collection of dust samples at selected locations with
the MVDS and the NADCA vacuum method. The MVDS, fitted with a brush, was the primary sampling
method for all HAC system surfaces. The NADCA method was used only for collection of post-cleaning
samples from galvanized steel surfaces because that is the only application for which it was developed.
4.2.1.1 NADCA Standard Method 1992-01
The NADCA Standard Method 1992-01 is described in the document entitled, Mechanical Cleaning of
Non-Porous Air Conveyance System Components (NADCA, 1992), The hardware for the method consists
of a vacuum pump operated at 10 L/min, a filter cassette, and a template for sampling. The 3 7-mm diameter
plastic filter cassette is used as the nozzle. The same pump and rotameter as used for the MVDS were used to
collect NADCA vacuum method samples. A flow control valve was placed in-line to control the flow to 10
L/min. The purpose of the method is to document the effectiveness of cleaning of non-porous ducts. In this
study, the NADCA Standard Method 1992-01 was used only for post-cleaning measurements on galvanized
ducts to document cleaning effectiveness; it was not used for pre-cleaning measurements.
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Table 4-1. Measurement Parameters and Methods8
Parameter
Sampling Method
Instrumentation
Analysis Method
Particle count, > 0.5 nm
Continuous (10 min avg)
Climet CI-4100
Optical (scattered light) -
Particle count, > 5.0 nm
Continuous (10 min avg)
Climet CI-4100
Optical (scattered light)
Particle counts (16 channels)
Continuous (60 min avg)
LAS-X
Laser aerosol spectrometer
PM2 5 mass
Integrated (24 hr)
Impactor/filter/pump
Gravimetric
PM10mass
Integrated (24 hr)
Impactor/filter/pump
Gravimetric
Fiber count
Integrated (24 hr)
Filter/pump
PCM and SEM
Fiber count
Semi-continuous (100 min avg)
MIEFAM-1
Optical (scattered light)
Bioaerosol (fungi)
Integrated (60 min)
Matson-Garvin slit to agar
Culture/microscopy
concentration
impactor
Temperature
Continuous
IAQDS
Solid state sensor
Relative humidity
Continuous
IAQDS
Thin-film capacitance
Carbon dioxide
Continuous
IAQDS
NDIR
Air flow rate (HAC system)
Manual
Omega HH-30
Vane anemometer
Temperature (HAC system)
Continuous
IAQDS
RTD
Relative humidity (HAC
Continuous
IAQDS
Thin-film capacitance
system)
Static pressure (HAC system)
Manual
AirData ADM-860
Capacitance
Differential pressure (HAC
Continuous
IAQDS
Capacitance sensor
system)
Blower on-time (HAC system)
Continuous
IAQDS
Pressure switch
Blower current (HAC system)
Manual
Fluke 32 meter
Current measurement
Surface dust
Pump/filter
MVDS - filter
Gravimetric
Duct dust mass
Manual
MVDS - filter
Gravimetric
Duct dust mass
Manual
NADCA method
Gravimetric
Microbial loading
Manual
Pipet tip sampler, filter, swab
Plate counting
"Abbreviations = IAQDS: Indoor Air Quality Data Station; PCM: Phase Contrast Microscopy; SEM: Scanning Electron Microscopy; NDIR: Non-
dispersive infrared analyzer; RTD: Resistance Temperature Device; MVDS: Medium volume dust sampler;
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4.2.1.2 Medium Volume Dust Sampler (MVDS)_
A medium volume vacuum method was developed for this project. The sampler consisted of the following
components:
• Thomas Model 2I07CA20A dual diaphragm vacuum pump with nominal free air flow of 50 L/min,
• Gelman Model 2220 stainless steel 47 mm diameter in-line low pressure filter holder,
• Whatman EPM 2000,47 mm, high-volume air sampling filters rated at 99,997% retention for 0,3 |im
dioctyl phthalate (DOP),
• Brooks rotameter, 0-50 L/min range, placed in-line; calibrated with a wet test meter
• Nozzle with brush - nylon bristle brush, oval shaped, with an opening of approximately 18 mm X 10
mm, with 10 mm long nylon bristles (Source; Enervae Battery-Powered Vacuum Cleaner).
The sampler was operated at 40 L/min. The brush was used for all sample collection during the study.
Previous testing at the RTI pilot scale test facility showed that the use of the brush was essential for
acceptable collection efficiency (VanOsdell et ai, 1997). The sampler was used with a 10 cm X 10 cm
square template. Sampling was performed by making multiple passes across the entire surface of the
template in both directions. There was not a standard set of passes made; the surface was brushed until
visual observation indicated that no additional dust could be collected.
The performance of the MVDS was evaluated in a previous laboratory study. Using artificially-loaded
duct surfaces, the MVDS fitted with the nozzle had a collection efficiency of greater than 90%. Results of the
evaluation are included as Appendix A to this report.
4.2.2 Continuous Particle Monitoring Methods
The Climet CI-4100 was used to monitor particle concentrations (particles/m3) throughout the test period
at each house. The instrument was operated with a 10-min averaging time and data were logged with the EPA
Indoor Air Quality Data Station (IAQDS) equipped with the Blue Earth data acquisition system. Although
the Climet CI-4100 collects data in both a greater than 0.5 jim size fraction and a greater than 5.0 |im size
fraction only one channel of data can be output to a data logger. The >0.5 jim size fraction data were
recorded with the IAQDS. The Climet has internal data storage capability for both size fractions, but only
200 data sets can be stored in memory. The data for the >0.5 jim size fraction recorded with the IAQDS was
the primary data set collected in the field study. However, each time the technician visited a stuffy house to
change filter media, he downloaded the data from the Climet, Because visits were made to the houses on two
days during each study to change filter media and for the HAC system cleaning, a reasonable amount of data
was obtained for the > 5.0 nm size fraction;
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Two Climets were placed in the primary living area. One was placed at a representative, well-mixed
location in the room at a height between 1 and 2 meters above the floor to monitor airborne particle
concentrations. The other monitor was placed within one meter of a supply air diffuser that served the room
in an attempt to gain better resolution of changes in concentrations of particulate matter delivered to the room
from the HAC system, rather than due to occupant activities in the room. A third Climet was placed in a
different room of the house. The sampling locations are described below and are indicated on floor plans
included as Appendix B to this report.
The real-time measurements of particle number concentrations were augmented by use of a LAS-X laser
aerosol spectrometer. The instrument was collocated with the Climet used to measure room air
concentrations. The instrument was used for measuring particle concentrations in the size fraction of 0.1 to
7.5 :m geometric diameter. Data were recorded with a laptop computer via an RS-232 connection.
4.2.3 Integrated Particle Sampling Methods
In addition to the real-time monitoring, integrated samples of PM,0 and PM2 5 mass were collected during
selected time periods, as described below. Samples were collected with size selective impactors developed at
Harvard University. The impactors are currently being used in both the EPA Office of Research and
Development (ORD) Large Buildings Study (Fortmann et al., 1994; U.S. EPA, 1994) and in the EPA Indoor
Environment Division's Building Assessment and Survey Evaluation (BASE) program (Girman et al., 1995;
U.S. EPA, 1994). The impactors collect particulate matter in the less than 10 pm diameter and less than 2.5
Hm diameter size fractions on Teflon filters. The samples were collected using pumps that operate at 20
L/min, which provided sufficient mass over a 24-hr sampling period for accurate and precise gravimetric
measurements. Mass determinations were made on the EPA Cahn microbalance located in the EPA Annex
following standard filter conditioning and weighing procedures developed for the EPA Large Building Study.
The microbalance has a resolution of 1 ng. Sample collection and analysis followed procedures developed for
other indoor air sampling projects and are described in the Standard Operating Procedures for the ORD Large
Building Study (Acurex, 1994).
4.2.4 Fiber Monitoring and Sampling Methods
Fiber concentrations were monitored continuously at one study home each week using the MIE FAM-1
Fibrous Aerosol Monitor. The monitoring principal of the instrument is light scattering. It was placed in the
primary living area for measurement of ambient room air concentrations. An integration time of 100 minutes
was used providing a detection limit of approximately 0.0005 fiber/cm3. Data from the instrument were
output to the MIE PDL-10 data logger for continuous recording.
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Integrated samples of airborne fibers were collected according to the NIOSH Method 7400, Asbestos and
Other Fibers by PCM (NIOSH, 1994), Samples were collected on 25 mm cellulose ester membrane filters
(0,8 nm pore diameter) housed in a conductive cowl. A nominal sample volume of 2800 liters was collected
over a 24-hour time period. Total fiber concentrations were determined in accordance to the NIOSH Method
7400 B counting rules. The NIOSH method, with analysis by phase contrast microscopy (PCM) measures
libers with a diameter greater than 0.25 and length greater than 5.0 jim. The samples were analyzed at the
laboratory of the R.J. Lee Group (Manassas, VA). One filter collected prior to cleaning and one collected
following cleaning were selected from each house for analysis by scanning electron microscopy (SEM) to
identify the composition of the fiber and particles in the samples, particularly the types of fibers (e.g., fiber
glass, cellulose fibers, hair).
4.2.5 Fungal Air Sampling Methods
Bioaerosol samples (fungi only) were obtained directly from within supply ducts in the primary and
secondary rooms which were sampled for particles in the field test houses. These samples were obtained
directly from the ventilation supply ducts to prevent room contamination from affecting the results, as
explained below. In addition, a room (not duct) bioaerosol fungal sample was obtained near the optical
particle counters. In the houses with secondary supply registers in the ceiling (upstairs), a room sample was
taken in place of the supply. Bioaerosol samples were not collected outdoors during the study because
outdoor air data were not required to meet study objectives. Because the bioaerosol samples were obtained
directly from within the supply ducts before and after cleaning, the impact of HAC system cleaning could be
assessed. The one sample collected in the room was intended to identify gross contamination indoors and
allow for comparison of samples collected from the ducts with the room air. This sample measured the
reservoir of indoor airborne fungal contamination that would be recirculated by the HAC system.
The bioaerosol samples were obtained at each test site with either Mattson-Garvin stit-to-agar samplers
operated over 60-minute periods or 1-stage Andersen cascade samplers operated for 10 minutes. Jensen
(1992) have shown that the results from a 1-stage Andersen are comparable to those from a Mattson-Garvin.
Three samplers were operated simultaneously, two in the ducts and one in the room, or one in the duct and
two in the room depending upon the secondary supply. The bioaerosol samplers, as configured for the in-
duct sampling, drew air from the supply ducts at 28.3 L/min through a sample probe allowing a broad range
of airborne particles to be impacted upon the surface of an agar plate. The sample probe was 108 cm in
overall length, with a conical duct sampling nozzle of 3.5 cm internal diameter (ID) at the inlet and tapered to
0.5 cm (Mattson-Garvin) or 0.9 cm (1-stage Andersen) ID tubing in its 5.5 cm length. The duct sampling
nozzle was placed vertically about 10 -15 cm into the supply duct, and the tubing formed a smooth U-shape
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from the nozzle to the fixture and adapter on the sampler inlet. It was placed into the supply duct to reduce
mixing with room air during the brief blower shutdowns described below. The duct sampling nozzle inlet
diameter provided a sampling velocity of 0.51 m/s (100 ft/min). The poor flow development at air duct
supply diffiisers (usually close to duct elbows), the need to keep sample lines short, and the fact that
unsteady-state flow (blower on/off, as described below) was inherently non-isokinetic limited the value of
isokinetic sampling. Thus the same nozzle was used at all sites. Additional details of the sampling method
can be found in Field Microbiological Investigation of Ventilation System Cleaning: Project Work/QA
Plan (RTI, 1996). When configured for room air samples, the sample probe was not used and air was drawn
directly into the slit from the room.
Routine microbiological emissions from undisturbed HVAC systems are normally low because the
emissions are usually caused by disturbances. Thus duct sampling in a period of fully established flow might
give low values that did not represent the overall emissions rate. On the other hand, tapping the duct
generally provides very high bioaerosol counts that are also not representative. The normal disturbances in
an HVAC system are the blower coming on and off and the consequent flow changes and duct movement.
Thermal and humidity changes can also change emission rates, but cannot be simulated in the short time
period available. To measure the emissions under conditions representative of normal operation (without
actively disturbing the microorganisms) while obtaining enough emission to potentially detect the effect of
HAC system cleaning, the blower was cycled on and off four times during the 60 min sampling period.
The supply duct sampling procedure was predicated on the use of a central forced-air ventilation system,
set in air conditioning (AC) mode, and using a conventional thermostat. The procedure was as follows:
1) Prepare the bioaerosol sampler to begin sampling, but do not start the system.
2). Five minutes before starting to sample, put the HVAC system in manual mode with the thermostat set
to a high enough temperature to prevent the AC from operating. The blower will be on most of the
time with brief shutdowns.
3) Remove the supply duct diffuser and position the microbiological sampler nozzle approximately 10 -
15 cm into the supply duct, facing into the air, and centered in the air flow.
4) Start sampling with the HVAC blower having been on (and the cooling coil off) for at least 5 minutes.
All three samplers were started within 30 s of each other. Record the start time and run a stopwatch
during the period.
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5) After 5 sampling minutes and with the sampler remaining on, turn the blower off. Continue sampling.
After about 30 seconds, turn the blower back on. This will cause the system to shift slightly as the
pressure changes, and may dislodge some particles.
6) After 20 sampling minutes, repeat the shut-off cycle (Step 4).
7) After 35 sampling minutes, repeat the shut-off cycle (Step 4).
8) After 50 sampling minutes, repeat the shut-off cycle (Step 4) for the fourth and last time.
9) Stop sampling after 60 minutes, turning the samplers off in the same order they were turned on.
10) Return the HVAC system to its normal operating mode.
The pre-cleaning bioaerosol samples were obtained before any portion of the air handler had been
disturbed except by normal operation, usually the day before duct cleaning. The post-cleaning bioaerosol
samples were collected at least 24 hours following the duct cleaning. Samples were not collected during HAC
system cleaning because the activity in the home and duct agitation were expected to generate a microbial
aerosol that would not be indicative of actual conditions.
4,2.6 Microbial Surface Sampling Methods
The primary microbial measurement was of the culturable microbial surface loading, expressed as colony
forming units (CFU) per cm2. Samples of deposited materials within a template defined area of 10 cm2 were
obtained by two techniques:
1) Suctioned at 10 L/min through a sterile pipet tip nozzle directly into a filter cassette, from which they
were eluted, and plated onto Tiypicase Soy Agar (TSA) and Sabourauds Dextrose Agar (SDA) for
analysis.
2) Collected with a sterile swab that had been wetted in a saline solution. The sample was then eluted
into a saline solution and plated onto TSA and SDA for analysis.
For both methods, the samples plated onto SDA were evaluated for fungal growth and the TSA plates for
bacterial growth. The methods are described in Air Conveyance System Cleaning Pilot System
Development, Characterization, and Operation: Project Work and QAPlan (RT1,1995) and Field
Microbiological Investigation of Ventilation System Cleaning: Project Work/QA Plan (RTI, 1996).
These measurements were conducted near where the dust mass loading measurements were made to permit
evaluation of the correlation between dust mass and microbial populations. Duplicate vacuum and swab
samples were collected in most cases to allow comparison of the two methods. A sample was considered a
duplicate when collected using the same access port, near the primary sample, and visually similar in loading.
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While the use of swabs to obtain surface samples is a traditional technique for non-porous surfaces, its use
cm rough-surfaced or porous materials cannot be quantitative because contact between the swab and the
surface is imperfect. The vacuum technique was developed for improved efficiency on porous materials.
During operation of the HAC system pilot unit (VanOsdell et al., 1997), the vacuum technique was found to
be more generally applicable on duct liners.
Because duct dust deposits vary non-uniformly in the relatively small residential ducts, duplicate tests
provide a measure of dust non-uniformity as much or more than of measurement variability.
4.2.7 Interior Surface Dust Sampling Method
In an attempt to assess the level of dust on surfaces in the home, a possible factor that may be related to
dust levels in the ducts, samples of dust were collected from two locations in the home. The samples were
collected from surfaces such as the top of book shelves, kitchen cabinets, etc. The sample was collected from
a 100 cm2 area using a template and the MVDS. Samples were collected on filters and the mass weighed.
Filters were weighed using the EPA balance with a resolution of 0.1 mg located in the controlled environment
weighing facility.
4.2.8 Measurements in the Air Conveyance System
A number of measurements were made in the air conveyance system to assess the impact of HAC system
cleaning on the performance of the system. The measurement parameters selected for this study may serve as
indicators of the impact of HAC system cleaning. The technical approach for this study was to perform
measurements prior to and following cleaning of the system to determine relative differences between pre-
and post-cleaning periods. During design of the field protocol, it was determined that quantitative
measurements of changes in energy usage due to HAC system cleaning could not be accomplished within the
scope of this study. Such measurements are complex, costly, and require extended measurement periods.
Measurements of the impact of HAC system cleaning on energy usage in a controlled test environment may
provide more accurate results than field measurements.
Temperature and relative humidity were measured in the main supply duct and the return duct by inserting
probes into the ducts at locations downstream of the coil where the air was expected to be relatively well-
mixed. The temperature and RH sensors were interfaced to an IAQDS that was placed in the basement, crawl
space, or other appropriate location near the air handler and ducts. A 10-min averaging time was used for
recording the data.
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Differential pressure across the coil was measured throughout the study. Pitot tubes were installed
upstream and downstream of the coil and connected to a sensor. Data were output to the IAQDS for
continuous logging. Static pressures in the supply and return ducts were measured manually with an AirData
micromanometer on two days prior to cleaning and again following cleaning.
The amount of time that the air conditioning systems operated during the monitoring period was
determined by installing a sail switch into the duct. Percent on-time was logged with the IAQDS.
AC current for the air handler fan motor was measured manually pre- and post-cleaning using a Fluke 32
digital (clamp-on) meter. Measurements were to be made twice before and twice after cleaning of the HAC
system. In some cases, the measurements could not be made because of the configuration of the wiring
harness or access problems.
The temperatures of the coolant lines were measured as an indicator of the performance of the cooling
system. Solid state temperature sensors were attached to the coolant lines at a location as close as possible to
the coil and wrapped with foam insulation. Temperatures were logged throughout the study period with the
IAQDS.
To assess the impact of HAC system cleaning on air flow rates in the system, volumetric air flows were
measured at all air supply registers and return registers in the home. Measurements of air velocity were made
with an Omega HH-30 digital meter/vane anemometer and the registers were measured to calculate
volumetric air flows. To perform the measurements of the supply air flows the vane anemometer was placed
on the front of supply diffusers. Measurements were made at two to four locations on each register to obtain
an average air flow rate. On return air grilles, measurements were made at twelve to 16 locations. The exact
number of locations was determined by the register size and air flow characteristics.
4.2.9 Temperature, Relative Humidity, and Carbon Dioxide Measurements
Temperature, relative humidity, and carbon dioxide concentrations were monitored continuously at one
location in the primary living area of the home and at an outdoor location. The parameters were monitored
with a solid state temperature sensor and a thin film capacitance relative humidity sensor. Data were logged
continuously with the IAQDS; ten minute average readings were recorded. These were not considered to be
critical parameters, but were collected to aid in the interpretation of the data, if required.
4.3 Survey Instruments and Data Collection Tools
Two survey instruments were used during the study at each home to collect information about the home,
the heating and cooling system, and occupant activities. The first survey instrument was the EPA/Acurex
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Environmental Air Duct Cleaning Field Research Study - Study Home and Heating and Air Conditioning
System Documentation Log. This survey included three sections:
• Characteristics of the Home,
• Characteristics of the Heating and Cooling Systems, and
• Occupant Activities and Air Contaminant Sources in the Home
Detailed information was collected on the air conditioning system(s) in the home and the air conveyance
system, including system age, manufacturer, size, etc.. Information about the home and occupant activities
was fairly detailed in an attempt to identify factors that may be related to dust levels in the duets.
The second survey instrument was the Participant Daily Activity Log. This survey instrument was used
by study participants to document activities in and around the heme during the monitoring week that may
have impacted particle and fiber levels in the home. The activity log was designed to be as simple to
complete as possible to maximize the response rate and the accuracy of the entries. The Log was set-up in a
daily log format that included activities such as opening of windows, number of people in the home during 1-
hour blocks, presence of pets in the home, cooking, hobbies, etc.
4,4 Field Protocol
The protocol for the field study involved week-long study periods at each home. In some cases, the study
period was extended beyond one week to collect additional data with the continuous particle monitors.
Monitoring and sampling occurred outdoors and at multiple locations indoors.
4.4.1 Sampling Locations
There were four primary locations for sample collection at each home. The primary sampling location was
a primary living area in the home, which may have been a living room, family room, dining room, TV room,
or den. Samplers were placed at a location in the room expected to provide representative measurement
results. The exact location was determined by the available space for placing the instruments. The monitors
and sampling ports were placed at a height between 1 and 2 meters above the floor and were at least 0,5 m
from a wall whenever possible. Integrated samples for particles and fibers were performed in the same room
at a location near the continuous monitors.
A Climet was placed in a second room in the house for continuous measurement of particle concentrations.
Integrated samples of particles and fibers were also collected at this location. In a two-story home, the
"second room" was on a different floor than the primary sampling location if it was feasible to route the
Climet output signal cable to that location from the primary monitoring area. In a single-story home, the
second room was a room that was not used extensively. Monitoring was not performed in the kitchen,
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bathrooms, closets, or other rooms that may have atypical or sporadic particle sources. The indoor sampling
locations are indicated on floor plans included as Appendix B to the report.
The third monitoring location was outdoors. Temperature and relative humidity were recorded outdoors.
Integrated particle and fiber samples were collected outdoors simultaneously with the collection of indoor air
samples. Meteorological date were not collected at the houses.
The fourth monitoring location was the air conveyance system. Locations of the measurements were
described above.
4.4.2 Protocol for Data Collection at Each Home
The schedule for performing the monitoring study at each home and the list of technician activities are
summarized in Table 4-2, The table summarizes the activities for a home set up on a Saturday. Week-long
studies were performed at two houses each week. The schedule for the second home was staggered by one
day. Homes were always cleaned on Tuesday and Wednesday. HAC system cleaning was always completed
in one day. With the exception of the continuous fiber monitor, sufficient instrumentation was available for
measurement of all parameters at the two houses. The original protocol involved instrument set-up and
retrieval on Saturdays and Sundays. This approach was taken to improve access to the study homes.
However, it was not necessaiy to set up and retrieve instrumentation at all homes on the weekends. When
possible, these activities were performed during the week and the study period was extended at the homes,
The initial testing at the EPA IAQ Test House was performed in May, 1996. The field studies at the eight
occupied homes were performed during the June to August, 1996 period, the period of peak cooling
requirements in North Carolina.
4.5 Initial Testing at the EPA Indoor Air Quality Test House
The first house studied was the EPA Indoor Air Quality Test House in Gary, NC, The study at the Test
House was a pre-test of the technical approach and methods to be used for the eight occupied homes. The
procedures were similar to those described above, except that a larger number of samples were collected and
continuous monitoring was performed for a longer period. The modifications to the protocol for die Test
House was as follows:
• Real-time (continuous) monitoring was performed for 5 days prior to and 5 days following cleaning of
the HAC system,
• Three sequential 24-hour integrated samples of PM25> PM10, and fibers were collected prior to and
following cleaning (compared to two samples pre- and post-cleaning in the field study).
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The results of the study at the Test House were analyzed and evaluated to determine if changes should be
made in the technical approach or the methods for monitoring and sampling.
Tabic 4-2. Protocol for Week-long Studies at Each Home
Day/Time
Activity
Saturday
0900 - 1600
Set up instrumentation at house in living area, outdoors, and HAC system; set up integrated
samplers and program to start Sunday at 0900; collect room surface dust samples; measure
supply and return air flow rates; measure static pressures and other HAC system parameters
Sunday
.
No technician activities at house; automated fiber and particle samplers run
Monday
0800 -1200
Retrieve filter media; start second set of integrated samples; download LAQDS and Climet
data; repeat manual measurements of HAC system parameters (air flows, static pressure, fan
current); collect microbiological samples
Tuesday
0800
Retrieve integratedparticle and fiber samples;
0800
Coordinate with NADCA on duct dust sampling locations and cleaning protocol
0900
Collect pre-cleaning duct dust and microbiological samples from supply and return
1000 - 1600
Perform duct cleaning
1630
Collect post-cleaning duct dust and microbiological samples from supply and return
1730
Set up particle and fiber samplers to start on Wednesday at 0900
Wednesday
No technician activities at house; automated fiber and particle samplers run; HAC system
cleaning being performed at other house studied that week
Thursday
0800- 1200
Retrieve filter samples; replace filter media; start second set of integrated samples; download
IAQDS and Climet data; perform manual measurements of HAC system parameters; collect
microbiological samples
Friday
No technician activity at house
Saturday
0800 -1200
Download IAQDS and Climet data; retrieve filters; perform manual measurements of HAC
system parameters; take down instrumentation
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4.6 HAC System Cleaning Methods
The air conveyance systems at the EPA Indoor Air Quality Test House and the eight field study homes
were all cleaned by representatives of N ADC A, The principal investigator for the NADCA team was present
for the HAC system cleaning at all houses and was responsible for scheduling and on-site coordination of the
cleaning activities. Cleaning team consisted of two to four NADCA representatives. During the study, six
different NADCA representatives assisted in cleaning at various houses,
HAC system cleaning was performed practices and equipment commonly used in the HVAC cleaning
industry. No proprietary equipment or methods were used in the study. All homes were cleaned using
portable equipment. Vacuum trucks were not used in the study. Specific equipment used at each house
varied according to the type and configuration of the HAC system and is described in Section 5.3 The
following equipment was used in the study:
Vacuum Collection
* Advance Containment Systems, 2801 Unit
* Meyer Machine & Equipment, General Collector Vacuum
* Nilcro Industries, 15-gal wet/dry HEPA vacuum
Agitation
* Vac Systems Industries, VIS 15,20, and 25 feet RSBS cable-drive rotary brush system
* Meyer Machine & Equipment, Viper pneumatic air whip system
«Abatement Industries forward and reverse skipper snakes
* Portable pressure washer, 1100 psi, 0.75 gallon/min
* Pressurized air source (minimum of 135 psi @ 10 cfin)
Wet Cleaning
* Acti-Kleen used for cooling coils
* Simple Green and power washer used for registers, difTuscrs, and grilles
Inspection
* UEMSI Chaser CCTV Video Inspection System
* Inspection mirrors and flashlights
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5.0 RESULTS AND DISCUSSION
This section describes the results of the field study. It includes a discussion of the participant selection
process and the results of the screening process used to select the eight occupied homes for the study. The
characteristics of the EPA Indoor Air Quality Test House and the eight occupied homes studied in the project
are described in the second subsection. Results of the measurements performed in the field study are
described in the following subsections. The final subsections include an evaluation of the sampling and
analysis methods used in this pilot study and observations made during the study related to the HAC system
cleaning methods, the condition of HAC system components in the study hones, and other factors that may
have impacted the research results,
5.1 Participant Recruitment and Screening Results
The participant recruitment and selection procedures generally were effective in identifying potential
participants and recruiting them into the program. Solicitation of participants from the research organizations
involved in the study - Acurex Environmental Coip. and the Research Triangle Institute - worked well,
resulting in a set of participants who were highly cooperative and provided a high level of access to their
homes. There was some difficulty identifying the type of materials used for the ductwork in homes of people
that responded to the solicitation for participants. This was because most homeowners were not
knowledgeable about their heating and cooling systems and the HAC system. They had difficulty describing
the type of ductwork and were usually not aware of what type of HAC system components that they had.
This resulted in a slight increase in the screening effort in the form of follow-up telephone calls and a greater
number of initial visits to potential participant homes than initially planned.
As described in Section 4.0, participants were recruited into the study by placing a "call for participants"
on the Acurex Environmental office E-mail system and in the weekly newsletter published by the Research
Triangle Institute. This approach was used because it was the most cost-effective method to obtain potential
participants. It was also felt that employees of the two research institutions were likely to provide a higher
level of cooperation and access to their homes because of their understanding of the technical aspects of this
research project and the logistics associated with field monitoring studies. However, the study was not
limited only to employees of the two organizations. Employees of the two organizations were encouraged to
have their friends, family, and neighbors respond to the advertisement.
The first step in the participant recruiting process was to have the potential participant provide responses
to a screening questionnaire. The Participant Screening Questionnaire, published in the Project Test Plan
(Fortmann, 1996a), included three questions to establish eligibility for the study and 39 questions to collect
information on the Characteristics of the Home, Characteristics of the Heating and Cooling System, and
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Characteristics of the Occupants and Activities. Participants that called the Acurex Environmental office in
response to the advertisement provided responses to the screening questionnaire which was completed by an
Acurex Environmental staff member.
Hie screening questionnaire provided critical information for selection of study homes. There was no
difficulty establishing eligibility for the study; respondents provided the information needed to establish that
the participant owned the hone, that there was no smoking of tobacco products in the home at the time, and
that they had a central air conditioning system that they intended to use during the study period. Respondents
could also provide responses to the seven questions on the Characteristics of the Home, including size of the
home, number of floors, age of the home, etc.. Respondents could also provide accurate answers to questions
in the section on Characteristics of the Occupants and Activities. The section included questions about the
number of occupants, pets, cooking activities, use of windows for ventilation, and perceptions about dust
levels in the home. The section of the screening questionnaire that respondents had difficulty providing
answers was Characteristics of the Heating and Cooling System. This section contained 18 questions about
the heating and cooling system that were critical for the initial selection of homes for the study. It included
questions related to the age and type of heating and cooling systems, age of the ductwork and the materials of
construction of the ducts, type of filters in the system, location of supply diffusers and return air grilles, and
other HAC system-related questions. Many of the respondents knew the type of heating system (gas, heat
pump, etc.) and the approximate age of the heating and cooling system. They also could provide reasonably
accurate information on the location and type of filter used in the system. Information was also generally
adequate on the locations of supply diffusers, return air grilles, and the air handler. The two areas in which
the respondents generally could not provide accurate information was on the type of ducts installed in the
home and an assessment of how dirty the system was. It was not surprising that respondents did not know
the extent of dust in the system. Most respondents did not have the expertise to make this assessment.
Furthermore, the fact that the potential participants responded to the advertisement suggested that they
thought their HAC system needed cleaning. In general the respondents thought they had moderate, heavy, or
excessive dirt and debris in their ducts.
Potential participants had the most difficulty responding to the question "Do you know what type of ducts
are installed in the house?" The options included, galvanized metal ducts, galvanized metal ducts with
flexible ducts to the rooms, galvanized metal ducts lined with insulation on the inside, duct board (also
known as flberboard, i.e. not metal), and other. Many respondents did not know what types of ducts were
in the home. Some knew that the main ducts were galvanized metal, but were not sure what type of ducts
went to the room supply diffusers. Practically none of the 65 respondents knew whether they had ducts
internally lined with fibrous glass duct liner. Generally, respondents did not know what duct liner was. The
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failure to be able to collect accurate information on the type of ducts in the home resulted in a large number of
follow-up calls and more initial screening visits to the homes than planned. It is anticipated that in any study
of this type it would be difficult to obtain accurate information about the types of ducts because most people
are not knowledgeable about duct materials. Furthermore, in the area where the study was performed, most
ductwork is in a crawl space under the home. The average homeowner avoids entering the crawl space and is
not familiar with the HAC system components. Slightly better information might have been obtained if an
additional question had been included that asked if the ducts in the crawl space were insulated on the outside.
This may have helped identify systems with intemally-lined ducts.
Sixty-five people responded to the call for participants. Of those, five were determined to be ineligible
due to smoking or not being homeowners. Of the remaining 60 homes, nine were large homes with two air
handlers. As described in Section 4, homes with two air handlers were excluded from the study because it
was not feasible to clean the entire HAC system in one day, a requirement for the field monitoring schedule.
Four homes had ducts intemally-lined with fibrous glass duct liner, but three of the homes had two air
handlers and could not be used in the study. One home had a single air handler with internally-lined ducts,
but inspection of the ducts indicated that there was substantial fungal contamination in the system, making it
ineligible for the study. Three homes had HAC system' with components constructed of fibrous duct board.
These homes were not included in the study.
The second phase of the participant selection process was a review of the screening questionnaires and
selection of eight candidate homes that appeared to fit the selection criteria and that provided a range of duct
types Mid configurations. Because respondents generally did not know the type of ducts in their home it was
first necessary to make follow-up telephone calls or E-mail inquiries to nearly half of the respondents in an
attempt to collect better information on the duct materials. Based on that information, eight candidate homes
were selected for site visits. When the plan for recruitment of participants was developed, it was anticipated
that visits would need to be made to 12 to 16 homes in order to identify eight for the study. A total of 19 site
visits were performed for the study.
The initial visit to the house was performed by the principal investigator of the project. The objectives of
the initial visits were to verify the eligibility of the participant, inspect the HAC system to determine if it met
study requirements, and assess the level of dust in the system. Eligibility of the home was easily verified.
Responses to the screening questionnaire were verified during the visit and additional information was
collected related to the air handler and air conveyance system. Information collection during the visit
confirmed that responses to the questionnaire about the home, the occupants, and occupant activities were
generally accurate. But the information provided by the potential participant about the HAC system during
the screening interview was frequently not accurate.
30
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During the initial site visit, the air handler and ducts were inspected to assess the relative level of dust in
the system. This was generally accomplished using an inspection mirror or fiberscope. The return ducts were
inspected at the return air grilles in the home and at the air handler. Supply ducts were inspected from the
supply diffusers, via existing access panels, by removing end caps from ducts, and in some cases by
disconnecting feeder ducts from the main supply trunks. This approach generally was adequate to obtain a
qualitative assessment of duct dust levels. No access holes were cut into the ducts during the initial visit.
Where access to the ducts permitted, samples of duct dust were collected with the MVDS for a quantitative
assessment. This information was useful, but was not a primary determinant in the final selection of homes
for the study. The qualitative information from visual inspections was sufficient to rank homes based on the
relative amounts of dirt and debris in the HAG system.
Following the initial visits, the homes were ranked according to suitability for the study based on the
selection criteria. Recommendations were made to the EPA project officer, who made a final decision on the
homes to be used in the study. Following selection of the homes, return visits were made to most of the
homes with representatives ofNADCA who evaluated the duct configuration and materials in order to
prepare for the cleaning.
5.2 Characteristics of the Nine Study Homes
The characteristics of the study homes are summarized in Table 5-1. The first home studied in the project
was the EPA Indoor Air Quality Test House located in Caiy, NC. This small ranch-style house is unoccupied
and unfurnished. It is used by the EPA to study a wide range of indoor air quality issues. The use of the
home in the study provided an opportunity to perform a pre-test of the field measurement protocols Mid a
location to evaluate the monitoring and sampling instrumentation in a semi-controlled environment. The
house also provided an opportunity to evaluate cleaning methods for fibrous glass duct liner (FGDL), The
duct system in the house consists of a single internally-lined galvanized steel supply trunk that extends 19
feet (5.8 m) in one direction from the air handler and 12 feet (3.7 m) in the other direction. Eleven flexible
feeder ducts connect to the main supply trunk. Due to previous condensate drainage problems, the FGDL
was contaminated with fungal growth. The fungal contamination was present at the time of cleaning.
31
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Table 5-1. Characteristics of the Nine Study Homes
No.
City
House
Age
Duct
Age
AH
Age
Duct
Materials
House
Size
(ft2)
No. of
Floors
No. of
Adults
No. of
Children
Pets
Notes
TH
Caiy
20'
20*
20"
Fibrous duct
. liner and flex
1305
1
0
0
0
Unoccupied EPA Indoor Air Quality Test
House; AH in crawl space
1
Raleigh
22
22
22
All
galvanized
1520
1
2
2
1 cat
Air handler (AH) in crawl space;
condensate drain plugged
2
Raleigh
18
18
0.5
Galvanized
supply; flex
return
1450
1
2
0
0
Ranch style home; new air handler
installed in Feb, 96; AH in crawl space;
homeowner planned to get ducts cleaned
3
Apex
10
10
10
All flex
1980
2
2
2
0
All flexible ducts with distribution
plenum boxes with fibrous glass duct;
AH in low crawl space
4
Apex
9
9
9
All flex
2000
2
2
2
2 dogs
All flexible ducts with distribution
plenum boxes with fibrous glass duct;
AH in crawl space
5
Cary
28
_«
_*
All
galvanized
1955
1.5
2
2
1 cat
Split level house; AH in crawl space;
condensate drain improperly installed; not
draining; dryer vented to crawl space
6
Durham
25
25
¦
Galvanized
and flex
1000
1.5
3
0
2 dogs
2 cats
Split level; mix of un-lined galvanized
and flex ducts; AH in unoccupied
basement; easy cleaning access
7
Chapel
Hill
26
26
26
All
galvanized
2000
2
2
2
0
Complaints of dust from supply; AH in
crawl space
8
Durham
35
35
All
galvanized
1500
2
2
2
1 cat
AH in full unheated basement
a Accurate information unavailable. Age of Test House believed to be 15 to 20 years. In cases where information was unavailable, inspection of the
ductwork suggests that ducts are same age as house, but age of air handler is unknown.
-------
The other eight homes in the study were occupied by the owners at the time of the study. All homes were
occupied by two adults, except House No. 6 which was occupied by three adults. The number of occupants
was not a selection criterion and it turned out that six of the eight houses were occupied by two adults and
two children. Cats and/or dogs were present in five of eight homes.
As shown in Table 5-1, the homes ranged in size from 1000 to 2000 ft2 (93 to 186 m2). The homes were
9 to 28 years old. Two houses were single level ranch-style homes with a crawl space under the entire house
and two were split-level homes. House No. 5 had a crawl space under approximately half of the house. Some
of the ducts in the house were in the crawl space and some were in the ceiling of the Iowa-level of the house.
House No. 6 was a split level house in which a previous owner had converted the original crawl space to an
unfinished basement in which the air handler was located. In this house some ducts were in the unfinished
basement and others were in the ceiling of the finished lower level. Four houses were two stories with ducts
for the first floor in the crawl space and ducts for the second floor located in the attic. In all homes, except
House No. 2, the ducts appeared to be the original installed at the time of construction. At House No. 2, the
air handler and return air ducts had been replaced approximately six months before the study. The HAC
system in House Nos. 3 and 4, which were located in the same development and were similar in construction,
were all flexible ducts. The supply ducts were connected via internally-lined (FGDL) distribution boxes.
House No, 6 had a combination of galvanized steel ducts and flexible ducts. All other houses had all
galvanized duct systems, consisting of externally-insulated rectangular supply ducts with round galvanized
steel feeder ducts to the rooms. Additional description of the houses is included in the following subsection.
5,3 Description of the HAC System and the HAC System Cleaning Methods
During the field study, each of the houses was visited by the Acurcx Environmental project director, the
field technicians, staff from EPA, and two to four NADCA representatives responsible for performing the
HAC system cleaning. During the visits, a number of observations were made relating to the design,
construction, operation, and maintenance of the air conveyance system at the house. On the day that cleaning
was performed, the HAC system components were inspected as part of the cleaning process. During the
study, numerous instances of poor design and poor maintenance of the HAC system were observed. At house
1, for example, the condensate drain was plugged, resulting in intrusion of water into the air handler. This
had apparently been a problem for an extended period of time because the air handler frame was rusty and
badly corroded. At House 5, the condensate drain line was not installed properly and had insufficient vertical
drop for use as a gravity drain system. As a result, the water was not draining. Installation of a drain pump
would be required to correct the problem. During the first visit to House 7, the principal investigator found
that one of the branch feeder ducts had broken away from the main supply trunk; the branch trunk was on the
33
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floor of the crawl space and air was blowing out of the supply trunk. At House 5, there was a large gap in the
supply trunk where it connected to the air handler plenum box, resulting in large energy losses to the crawl
space. This unit also had an access plate on the supply duct that was originally taped onto the side of the
duct, but had fallen off. A number of the deficiencies in the systems would impact the performance of the
HAC system and the energy use, as described above. Some deficiencies might adversely impact indoor air
quality and occupant comfort and health. At House 3, mice had eaten through the flexible duct. There were
large pieces of fiberglass insulation that the mice had collected as nesting material. Some of it had blown to
the floor registers. In this system, there were mice feces and seed shells throughout the system, including
deposits on ceiling diffiisers on the second floor. At House 7, condensate drain problems resulted in water
damage to the fibrous glass liner in the air handler plenum box. Upon opening the box, the fibrous glass liner
was found to be contaminated with fungal growth. Other deficiencies impacted the effectiveness of the HAC
system cleaning. There were numerous cases of panned return air plenums. The wood, gypsum board, and
other surfaces were more difficult to clean than sheet metal duct, At Houses 5 and 6, the stairwell served as
the return plenum. Not only was the design conducive to heavy dust and debris deposits in the return because
there were no filters on the grilles, but the plenums were difficult to clean. In general, the homeowners were
not aware of design deficiencies or maintenance problems. They were usually not aware of the significant
impact that duct leakage and deteriorating insulation would have on energy costs for operating the system.
This was normally the result of a lack of knowledge about residential heating and cooling systems and not a
lack of concern.
The HAC system was cleaned by representatives of NADCA with methods and commercially-available
equipment commonly used in the HVAC cleaning industry. No proprietary equipment or methods were
employed during this study. The vacuum collectors were portable units; vacuum trucks were not used in the
study. Cleaning of the HAC system at the study homes generally involved work by two to four cleaning
personnel during a six to ten hour period. The cleaning involved removal of all supply registers and diffusers
and return air grilles. The floor boots were hand vacuumed at all homes. The panned return air plenums were
also hand vacuumed. The systems were zoned as required for cleaning. A substantial effort was expended on
cleaning of the AHU components. The blower was removed from the AHU for cleaning at all houses.
Cooling coils were wet-cleaned in place. During cleaning there was a high level of visual inspection to insure
that the components of the system were cleaned effectively. Visual inspection was normally performed with
mirrors and flashlights. Use of a remote video camera provided improved inspection capabilities particularly
in systems with long ducts and extensive bends and transitions.
The Mowing sub-sections contain a brief summary of the characteristics of the air conveyance system
and the methods used for cleaning the HAC system at the study homes. To the extent possible, deficiencies
34
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in the systems that may have impacted energy use, indoor air quality, or HAC system cleaning effectiveness
are highlighted. Ratings of characteristics such as duct integrity are subjective.
5.3.1 EPA Indoor Air Quality Test House
Pate Cleaned:
NAPCA Personnel.
House Design:
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan:
May 21,1996
TH.BK, CC
Single story ranch
Drain Line:
Humidifier:
Contamination:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Hallway closet
Vertically-mounted; DX cooling; gas heating; blow-through fan
Visible dust
Coating of dust on fan blades
Standing water; not draining completely; on-going problems with condensate in
the supply plenum at the time of cleaning; pan was not fitting properly on one
end; fan was blowing water out of pan into the supply duct
Working properly
None
Water damaged fibrous glass insulation was contaminated with mold growth;
insulation was removed, discarded, and replaced with new insulation
Ducts in crawl space; floor registers; panned in supply air (S/A) plenum in
kitchen and bathrooms
Galvanized sheet metal, rectangle trunk duct, internal fibrous glass liner;
flexible ducts to room difTusers
Some rust in areas with previous water damage from condensate drain problem;
insulation at bottom of S/A plenum was saturated with water from condensate
drain pan
Visible debris at floor boots, assorted debris; internal fibrous glass duct liner
heavily contaminated with fungal growth throughout supply trunk; fungal
contamination in flexible ducts
35
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Return Ductwork:
Location:
Duct Type:
Integrity:
Filter:
Contamination:
Ductwork in attic; return grille in hall ceiling adjacent to air handling unit
Flexible duct
Acceptable condition
Located in ceiling return grille; standard low-efficiency; clean
Visible dust; visible fungal contamination
Environmental Observations:
Crawl Space - Polyethylene sheet on dirt floor; mold odor
House Interior Conditions - House unfurnished; all carpeted; carpet requires cleaning; mold odor
HAC System C Ironing
Due to the degraded and contaminated condition of the fibrous glass duetliner, NADCA personnel
recommended either replacing the duct or re-surfacing the duct liner to prevent further degradation. However,
this was not done so that the contaminated duct could be used for additional research in the future. The
fibrous glass duct liner was power brushed with nylon brushes, air washed, and visually inspected while kept
under negative pressure from an Advanced Containment Systems (ACS) 2801 collector vacuum with HEPA
filtration. Parts of fibrous glass liner were hand brushed and hand vacuumed. Flexible return air duct
removed, discarded, and replaced with new duct. All flexible ducts to room supplies were removed and
replaced with new ducts because of extensive mold contamination in the HAC system which made them un-
eleanable. AHU plenum hand vacuumed with attachments on a portable HEPA-filtered canister vacuum. AC
coil was wet cleaned with Acti-KJeen. Visual inspection performed with fiber scope.
5.3.2 House Number 1
Date Cleaned:
NADCA Personnel:
House Design:
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower;
Drain pan:
June 11,1996
TH, BK, TY
Single story ranch
Crawl space
Horizontally-mounted; DX cooling; electric heating; draw-through fan
Visible debris
Coating of dust on fan blades, along with some oil from motor shaft
Standing water with debris and slime
36
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Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Return Ductwork:
Location:
Duct Type:
Integrity:
Filter:
Contamination:
Not draining; plugged, although AHU equipped with condensate pump that was
working; condensate draining out of supply plenum onto crawl space floor
One-fourth inch of wet dirt in the supply plenum; mole crickets and bugs
impaled on heating coil; dead bugs throughout AHU
None
Duets in crawl space; floor supply registers, except two sidewall registers in
sunken living area
Galvanized sheet metal, rectangle trunk duct; round branch ducts to rooms;
externally insulated
Limited amount of rust/corrosion at floor boots, otherwise acceptable condition;
external insulation deteriorated and needed replacement
Crusty coatings at floor boots, assorted debris including toys, crayons, hair, etc.;
overall the system was considered to be very dirty
(I) Kitchen wall; (2) hallway ceiling
(1) Wall board/sheetmetal to flexible duct; (2) flexible duct
Normal
Located in return air grilles; high-efficiency, washable; moderately dusty
Dust and hair coating throughout return system
Environmental Observations:
Crawl Space - Loose dirt on crawl space floor; no polyethylene covering on crawl space dirt floor
House Interior Conditions - Below average housekeeping; carpet heavily soiled; surfaces of furnishings dusty
HAC System Cleaning Methods:
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually inspected while
kept under negative pressure from a Meyers General collector vacuum without HEPA filtration. Return air
boxes and AHU plenum were hand vacuumed with attachments on a portable HEPA-filtered canister vacuum.
AC roil was wet cleaned and condensate drain line was blown free of debris with pressurized air. Meyers
General vacuum located near crawl space door.
37
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5.3.3 House Number 2
Pats Cleaned:
NADCA Personnel:
House Pesig":
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan;
Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Return Ductwork:
Location:
June 12,1996
TH, BK, TY
Single story ranch
Crawl space
Horizontally-mounted; DX cooling; electric heating; draw-through fan
Light debris, new coil (less than one year old)
Light coating of dust on fan blades
Moderate standing water
Working properly
AHU less than one year old; moderate dust present
None
Ducts in crawl space; floor supply registers
Galvanized sheet metal, rectangle trunk duct; round ducts to room diffusers
Acceptable condition
Moderate surface contamination at floor boots and trunk duct
Two return grilles: (1) in entry hallway, (2) in main hallway; both R/A were
panned
Duct Type; Galvanized sheet metal and flexible duct
Integrity: Normal
Filter: In return air grilles; high-efficiency panel type media filters; moderate dust
Contamination: Coating of dust throughout the return system
Environmental Observations:
Crawl Space - Loose dirt on crawl space floor; no polyethylene covering on crawl space dirt floor
House Interior Conditions - Housekeeping above average; mostly wall-to-wall carpeting
HAC System Cleaning Methods:
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually inspected while
kept under negative pressure from a Meyers General collector vacuum without HEPA filtration. Meyers
General located behind house at crawl space door. Panned in R/A plenums and AHU were hand vacuumed
38
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with attachments on a portable HEPA-filtered canister vacuum. Flexible return duct was contact-vacuumed.
Cooling coil was wet cleaned with Aeti-Klccn. Simple Green used to clean registers and grilles.
5.3.4 House Number 3
Pate Cleaned:
NAPCA Fcrgpnncl:
House Design:
June 25,1996
TH, BK
Two-story
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan:
Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Crawl space
Horizontally-mounted; DX cooling; gas heating; blow-through fan; internal
insulation poorly installed
Visible debris
Moderate coating of dust on fan blades, along with some oil from motor shaft
Some standing water
Working properly
Substantial amount of loose fiberglass, rodent feces, sunflower seed hulls,
peanuts hulls, and other debris from mice that had inhabited system
Add-on unit located in supply plenum; severe mineral build-up; assorted slime
and debris in unit
First floor ducts in crawl space; floor supply registers on first floor; ceiling
diffusers on second floor; ducts in attic
All flexible duct with bullhead plenums, internally-lined; volume dampers for
balancing
NADCA personnel recommended replacement of the entire duct system due to
poor design and installation. There was substantial deterioration of portions of
round flexible duct material which needed replacement; volume dampers
inoperable because of poor design and installation; bullhead plenums had
significant air leakage.
39
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Contamination:
Excessive contamination throughout the system including rodent droppings,
rodent's nesting material consisting of the fiberglass insulation, and sunflower
seed hulls. Also construction material was left in the ductwork, dust
accumulation, and other debris. Insulated round ducts had visible condensation
and mold growth on the outside.
Return Ductwork:
Location:
Duct Type:
Integrity:
Filters:
Contamination:
Two R/A grilles: (1) living room wall on first floor; (2) hallway wall on second
floor
Flexible duct
NADCA personnel recommended replacement of the entire return duct system
due to the poor condition and poor installation, Duct was severely degraded at
connection to air handler
In return air grilles; washable, high-efficiency, panel type; moderate dust level
Heavy dust coating throughout the return air system.
Environmental Observations:
Crawl Space - Loose dirt on crawl space floor; no polyethylene covering over dirt floor of crawl space
House Interior Conditions - Above average housekeeping
HAC System Cleaning Methods:
Flexible ductwork was power brushed with nylon brushes and air washed while kept under negative
pressure from a Meyers General collector vacuum without HEPA filtration. Meyers General vacuum
collector located outside at the crawl space access door. Return air plenums and AHU were hand vacuumed
with attachments on a portable HEPA-filtered canister vacuum. Cooling coil and humidifier unit were wet
cleaned using Acti-Kleen.
S3S House Number 4
Date Cleaned: June 26,1996
NADCA Personnel: TH, BK
House Design: Two-story
HAC System Description:
Air Handling Unit:
Location: Crawl space
40
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Type:
Cooling Coils:
Blower:
Drain pan:
Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Return Ductwork:
Location:
Horizontally-mounted; DX cooling; gas heating; blow-through fan; insulation
poorly installed
Visible debris
Coating of dust on fan blades, along with some oil from motor shaft
Some standing water
Operational, but not completely draining the pan
Moderate dust; some mold growth on internal insulation at supply plenum
None
First floor ducts in crawl space; floor supply registers on first floor; ceiling
diffusers on second floor; ducts in attic
All flexible duct with bullhead plenums, internally-lined; volume dampers for
balancing
Poor desip and installation; deterioration of portions of round flexible duct
material which needed replacement in both attic and crawl space; volume
dampers inoperable because of poor design and installation; bullhead plenums
had significant air leakage; NADCA personnel recommended replacement of
parts of the duct system
Visible dirt and dust throughout the system including pet hair and debris
Two return air grilles: (1) Living room wall on first floor; (2) ceiling on second
floor
Flexible duct
NADCA personnel recommended partial replacement of the duct system
In return air grilles; standard low-efficiency fiberglass panel type; heavy dust
loading on both filters; upstairs filter did not fit
Dirt and dust coating throughout return system
Environmental Observations:
Crawl Space - No polyethylene covering of loose dirt on crawl space floor
House Interior Conditions - Average housekeeping; two dogs kept in house
HAC System Cleaning Methods:
Flexible ductwork was power brushed with nylon brushes and air washed while kept under negative
pressure from a Meyers General collector vacuum without HEPA filtration. Meyers General located outside
Duct Type:
Integrity:
Filter:
Contamination:
41
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near crawl space access door. Return air plenums and AHU were hand vacuumed with attachments on a
portable HEPA-fdtered canister vacuum. Cooling coil and humidifier unit were wet cleaned.
5.3.6 House Number 5
Date Cleaned: July 16,1996
NAPCA Personnel: th, bk, cc, fc
House Design: Split-level ranch
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan:
Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Return Ductwork:
Location:
Duct Type:
Integrity:
Crawl space
Horizontally-mounted; DX cooling; gas heating; blow-through fan
Visible debris
Heavy coating of dust on fan blades
Over one inch of standing water; water carry over into supply plenum
Improper design; not working; condensate drain improperly routed (inadequate
drop for gravity drain); requires installation of a condensate drain pump
Heavy deposits of dust and fibers in system
None
Floor registers on main level and upstairs; ceiling diffusers in lower level rooms;
ducts in crawl space and in ceiling of lower level rooms
Galvanized sheet metal; rectangular trunk duct; round branches to rooms;
deteriorated external insulation
Duct design had excessive right angle turns/transitions throughout system; one
main supply trunk had large separation at connection to supply plenum of air
handler resulting in large losses of air from system
Moderate surface contamination throughout system; considerable debris in trunk
duct
Two return air plenums: (1) In stairwell from entry to first level; (2) in stairwell
from first level to second level; grilles in all stair risers; no filters at grilles;
stairwell serves as panned R/A plenum
Galvanized sheet metal
Access difficult under stairwell; return not well sealed; not insulated
42
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Filter: In air handier at blower; old, low-efficiency fiber mat filter; heavily-loaded with
dirt; poor fit
Contamination: Dust and debris coating throughout return system
Environmental Observations:
Crawl Space - No polyethylene covering over loose dirt on crawl space floor.
House Interior Conditions - Average housekeeping; downstairs lower level den with visible dust on
surfaces; dryer was venting into the crawl space near the return duct; strong odor detected at the AHU, but
source was not identified
HAC System Cleaning Methods.
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually monitored via a
UEMSI portable cctv video inspection system while kept under negative pressure from a Meyers General
collector vacuum without HEPA filtration. Meyers General vacuum collector located outside near crawl
space access door. Return air plenum and AHU were hand vacuumed with attachments on a portable HEPA-
filtered canister vacuum. Cooling coil was wet cleaned using Acti-Kleen.
5,3,7 House Number 6
Date Cleaned: July 17,1996
NAPCA Personnel: TH,BK,CC,FC
House Design: Split-level ranch with original crawl space under entry level excavated and
converted to an unfinished basement
HAC System Description:
Air Handling Unit:
Location: In unfinished basement
Type: Vertically-mounted; DX cooling; gas heating; blow-through fan
Cooling Coils: Visible debris, slime
Blower: Moderate coating of dust on fan blades
Drain pan: Standing water; water cany over into supply plenum; visible microbial
contamination; excessive condensation on exterior of supply plenum ductwork
Drain Line: Not working properly; standing water
Contamination: Moderate levels of dust and fibers in system; slime in drain pan
43
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Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
Return Ductwork:
Location:
Humidifier was not working; had heavy mineral deposits and microbial
contamination; removed and not replaced
Floor registers on main level and upstairs; ceiling diffuscrs in lower level rooms;
ducts in crawl space and in ceiling of lower level rooms
Predominantly galvanized sheet metal; rectangular trunk duct; round branches to
rooms; some flexible branch ducts
Acceptable; insulation not complete on all exposed components (e.g., at
transitions)
Moderate surface contamination throughout system
Duct Type:
Integrity:
Filter;
Contamination:
Two return air plenums: (I) In stairwell from first level to second level; grilles in
stair risers; no filters at grilles; panned stairwell R/A plenum; (2) in sidewall in
lower level bedroom
Galvanized sheet metal
Acceptable
One in return air grille in lower level bedroom was standard low-efficiency
fiberglass with heavy dust loading; second one in air handler near blower that
owner did not know was present and had excessive dirt loading on it
Dust and debris coating throughout return air system
Environmental Observations:
House Interior Conditions - Housekeeping below average; visible dust on surfaces; heavy fungal
contamination on walls in upstairs bathroom
HAC System Cleaning Methods:
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually monitored via a
UEMSI portable cctv video inspection system while kept under negative pressure from a Advanced
Containment Systems 2801 collector vacuum with HEP A filtration located in unfinished basement. Return
air plenums and AHU were hand vacuumed with attachments cm a portable HEPA-filtered canister vacuum.
Cooling coil was wet cleaned.
44
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53.8 House Number 7
Date Cleaned: July 30,1996
NADCA Personnel: TH, BK, TB, TG
House Design: Two-story
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan:
Drain Line:
Contamination:
Humidifier:
Supply Ductwork
Location:
Duet Type:
Integrity:
Contamination:
Return Ductwork:
Location:
Duct Type:
Integrity:
Filter:
Contamination:
Crawl space
Horizontally-mounted; DX cooling; gas heating; draw-through fan
Visible debris
Moderate coating of dust on fan blades
Standing water; water carry over into supply plenum; internal fibrous glass liner
in supply plenum box contaminated with fungal growth
Not working properly; standing water
Moderate levels of dust and fibers in system; internal liner of supply plenum
contaminated with mold growth
None
Floor registers on main level; ceiling diffusers on second level
Galvanized sheet metal; rectangular trunk duct; round branches to rooms; supply
plenum box with internal fibrous glass liner
One supply branch duct had disconnected from the main trunk and fallen off:
system very leaky; external insulation that was deteriorated; fibrous glass duct
liner in supply plenum box contaminated with fungal growth
Moderate surface contamination throughout system; limited construction debris;
contaminated fibrous glass liner in supply plenum box
One grille in wall hallway under stairs near entry; R/A plenum was panned in; no
return from second floor
Galvanized sheet metal
Panned in R/A plenum; return not well sealed
Located in return air grille; standard low-efficiency fiberglass; moderate dust
Dust and debris coating throughout return system
45
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Environmental Observations:
Crawl space - No polyethylene covering on loose dirt in crawl space floor
House Interior Conditions - Housekeeping average to above averageHAC System Cleaning Methods:
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually inspected while
kept under negative pressure from a Meyers General collector vacuum without HEPA filtration. Meyers
General vacuum collector located outside near access door for crawl space. Return air plenums and AHU
were hand vacuumed with attachments on a portable HEPA-filtered canister vacuum. Cooling coil was wet
cleaned with Acti-Kleen. Supply plenum liner was removed and replaced with new insulation after cleaning.
5.3.9 House Number 8
Date Cleaned: July 31,1996
NADCA Personnel: TH, BK, TB, TG
House Design: Two-story with full, parti ally-finished basement
HAC System Description:
Air Handling Unit:
Location:
Type:
Cooling Coils:
Blower:
Drain pan:
Drain Line:
Contamination:
Humidifier:
Supply Ductwork:
Location:
Duct Type:
Integrity:
Contamination:
46
Basement
Vertically-mounted; DX cooling; oil-fired heating; blow-through fan
Heavy accumulation of dust and debris; significant blockage; cooling coil was
"A" coil; cooling coil was add-on to the AHU
Moderate coating of dust on fan blades
Standing water; some debris; slime in drain pan; poor access
Working, but not completely draining pan; drain line routed to basement floor
drain
Heavy deposits of dust and fibers in system; coil very dirty; slime in drain pan
None
Floor registers on both levels; ducts exposed in basement; some ducts in finished
ceiling of basement; all ducts went up exterior walls to second floor
Galvanized sheet metal; rectangular trunk duct; round branches to rooms
Generally good; two supply diffuser boots pulling away from basement ceiling
(nails loose)
Heavy surface contamination (dirt, dust, hair) throughout system; substantial
amount of fibers, probably cat hair, visible in ducts
-------
Return Ductwork:
Location:
(1) Sidewall floor grille in dining room; (2) sidewall floor grille in living room;
no return from second floor
Galvanized sheet metal; undersized
Moderate leakage, but in finished, conditioned basement
Located in air handler at blower; low-efficiency fiberglass; poor fit
Duct Type:
Integrity:
Filter;
Contamination: Heavy accumulation of dust in return system; highest dust levels in return of the
Environmental Observations:
House Interior Conditions - Housekeeping average; visible mold growth on floor joists in basement
HAC System Cleaning Methods:
Metal ductwork was power brushed with silica-carbide brushes, air washed, and visually inspected while
kept under negative pressure from a Meyers General collector vacuum without HEPA filtration. Meyers
General located outside near basement door. Return air plenums and AHU were hand vacuumed with
attachments on a portable HEPA-filtered canister vacuum. Cooling coil was wet cleaned.
S.4 Duct Dust and Microbial Surface Loading Measurements
The amount of dust in the supply and return ducts was measured at each home by collection of dust
samples with the MVDS, Dust was defined as the material that could be collected with the MVDS and
includes both particulate matter and fibers. Large pieces of debris, such as pencils, construction debris, and
parts of toys, were not collected with the MVDS. Obtaining access to the ducts was the most difficult aspect
of sample collection. In general, samples were collected only where easy access could be obtained without
disrupting the dust deposits in the ducts. Samples were collected in the return ducts near the return air grilles
and near the air handler. At the return air grilles, the technician reached into the duct as far as possible to
collect the sample. At the air handler, the access panel was removed for the blower and samples were
collected from the return air duct as far away from the access panel as possible. In both cases, the duct was
visually inspected with a mirror and flashlight in an attempt to identify a sampling location with
representative deposits of duct dust. In the supply side, access was gained in three ways. End caps were
removed from the main trunk duct or at distribution boxes. In some cases, feeder ducts were disconnected
from the main trunk in order to collect samples from the main trunk or from the feeder duct. The feeder ducts
were also disconnected near the supply register at some homes in order to collect samples. The third, and
least preferred method, was to cut access panels into the supply trunks to gain access for sampling. The
problem associated with this approach was that the process of cutting the galvanized steel metal resulted in
eight field study homes
47
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metal shavings in the duct. These could be easily observed with proper lighting, but it was necessary to reach
into the duct to access sampling locations without metal shavings. In one home, a short section of a main
supply trunk was removed to facilitate sampling.
A limited number of dust samples were collected with the NADCA method in the homes that had
galvanized steel ducts. Samples were collected only after HAC system cleaning to verify cleaning
effectiveness, as recommended in NADCA Standard 1992-01.
Samples were also collected in the ducts for determination of the culturable microbial surface loading in
the supply and return ducts. Samples were collected using the same access method as die dust samples, as
described in Section 4.0.
5.4.1 Duct Dust Mass Measurements Pre- and Post-Cleaning
The results of the duct dust measurements with the MVDS at the nine homes are summarized in Table 5-2.
The complete data set is included in Appendix C. The mean and standard deviation are presented for the total
number of samples (indicated as N) collected in the supply and all samples collected in the return. The
minimum and maximum duct dust concentrations are also included in the table to show the range of
concentrations. A limited number of samples collected from the foil liner of the air handler and the cooling
coil are also included in the table.
The mean dust mass in the supply ducts of the nine homes prior to HAC system cleaning ranged from 1.48
g/m2 at House 4 to 26.03 g/m2 at House 8. The second highest mean dust mass in the supply ducts was 8.62
g/m2 at House 1. The mean was less than 3.4 g/m2 at the other six houses. As shown in the table, the
maximum dust mass concentrations and the standard deviations were highest for Houses I and 8. The high
dust mass levels at House 8 were consistent with visual observations; House 8 was considered to have the
"dirtiest" ducts by all staff who inspected the ducts at the study homes.
Pre-cleaning dust levels were substantially higher in the return ducts than in the supply ducts. The mean
duct dust levels in the returns ranged from 5.26 to 35.11 g/m2. The maximum mass measured was 51.1 g/m2
in the return duct immediately upstream of the filter located adjacent to the air handler blower in House 8.
Samples collected from the foil liner of the air handler or the cooling coil were in the same range as
samples collected in the supply ducts. The number of samples collected from die air handler foil liner and
cooling coils was lower than planned. In some cases, access was limited, precluding easy collection of
samples. There were also logistical difficulties as three technicians and up to three NADCA staff worked
48
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Table 5-2. Dust Levels Measured with the MVDS in the HAC System of Study Homes
Duct Dust Mass (g/m2)
Summary
Supply
Return
Air Handler*
House
Statistic
Pre-
Post-
Prc-
Pest-
Pre- Post-
TH
Mean
2.33
0.74
_b
le
NS NS
Std, Dev
1.61
0.37
-
-
Min
0.80
0.27
-
-
Max
4.66
1.24
-
-
N
6
6
-
-
1
Mean
8,62
0.30
19.83
0.58
1.7 NS
Std, Dev
10.60
0,09
6.60
0.06
2.35' 0.29c
Min
0.51
0.24
26.30
0.54
Max
26.30
0.41
13.10
0.63
N
5
5
3
2
2
Mean
3.37
0.21
24.13
0,44
NS 0.18=
Std. Dev
2.09
0.08
23.52
0.23
Min
2.12
0.16
7.50
0.28
Max
5.79
0.30
40.80
0.60
N
3
3
2
2
3
Mean
1.91
0.25
7.80
0.28
1.57 0.19
Std. Dev
1.05
0.09
5.30
0.12
0.72c -d
Min
0.54
0.16
2.62
0.19
Max
3.00
0.35
13.15
0.42
N
4
3
3
3
4
Mean
1.48
0.27
7.89
0.12
0.46 0.10
Std. Dev
0.29
0.11
2.35
0.08
i.sr o,i2c
Min
1.27
0.19
6.22
0.06
Max
1.69
0.34
9.55
0.17
N
2
2
2
2
5
Mean
2.28
0.59
11.34
1.11
2.24c 0.13c
Std. Dev
0.48
0.39
0.21
1,22
Min
1.94
0.32
11,19
0.25
Max
2.62
0.87
11.49
1.97
N
2
2
2
2
6
Mean
2.30
0.18
5.26
0.15
NS NS
Std. Dev
0,26
0.00
1.69
0.04
Min
2.00
0.18
3.62
0.12
Max
2.45
0.18
6.99
0.19
N
3
2
3
3
7
Mean
3.34
0.50
12.91
0.32
6.18 0.25
Std. Dev
1.79
0.17
5.48
0.03
2.38c -,i
Min
1.24
0.37
9,03
0.30
Max
5.93
0,69
16.78
0.34
N
6
3
2
2
8
Mean
26.03
0.79
35.11
0.39
5.48' -d
Std. Dev
8.41
0.35
13.85
0.28
Min
16.39
0.44
26.59
0,19
Max
36.07
1.13
51.10
0.59
N
4
3
3
2
* Single samples were collected from the foil liner or cooling coil (not mean of replicates)
b Return air duct replaced; no samples collected
c Coiling coil samples d Coiling coil could not be sampled post-cleaning because it was wet
NS: No sample collected due to logistical or access problems
49
-------
on the system. However, the samples from the foil liner were not considered to be critical because the dust
deposit on the air handler liner was generally not representative of the rest of the ductwork. Dust samples
were not collected from all cooling coils prior to cleaning. But this was not critical to interpretation of the
results. During the study, it was observed that dust could not be efficiently collected from the cooling coils
with the MVDS prior to cleaning. Dust and fibers impacted on the coil and in the coil "fins" remained after
sampling. This was especially obvious at House 8, where the cooling coil was very dirty. Post-cleaning
samples could not be collected at every home because the cooling coil was still wet following cleaning.
Results of this study suggest that quantitative measurements of dust on coils will be difficult to perform both
prior to, and following, HAC system cleaning. The performance of the MVDS has not been evaluated for
sampling from coils and is not likely to be highly efficient. Visual observation of dust and fibers on coils is
probably adequate for comparisons between houses.
The post-cleaning measurement results presented in Table 5-2 show that the cleaning methods were
generally veiy effective for removing dust from the HAC system components. The mean residual dust
measured with the MVDS from supply ducts after HAC system cleaning ranged from 0.18 to 0.79 g/m2, In
the return ducts the mean residual dust mass following cleaning ranged from 0.15 to 1.11 g/m2. For all post-
cleaning samples collected at the nine homes, the dust mass ranged from 0.06 to 1.97 g/m2. The reader is
cautioned that interpretation of the mean results should be made considering the limited number of samples
used to calculate the mean. Only two or three samples each were collected from the supply and return
following cleaning, as indicated by "N" in the table. For example, the highest mean levels of residual dust
were measured in the return and supply ducts at House 5. However, as shown by the Minimum and
Maximum values presented in the Table, for both the supply and return, one sample was less than 0.32 g/m2,
but the other sample was substantially higher. Post-cleaning measurements for samples from the air handler
foil liner and cooling coils were in the same range as those collected from supply and return duct surfaces.
Samples of duct dust were also collected with the NADCA vacuum method following cleaning of the HAC
system. Collocated samples were collected with the NADCA and the MVDS methods in order to compare
the two methods under field conditions. Results of the comparison are presented in Table 5-3. The NADCA
standard units of mg/100 cm2 are used in the table. The NADCA results ranged from 0.01 mg/100 cm2 to
0.36 mg/100 cm2 (0.001 to 0.036 g/m2). In all cases, the samples met the NADCA criterion of 1.0 mg/100
cm2 as a verification that the surfaces were effectively cleaned. Collocated measurements with the MVDS
ranged from 1.6 to 11.3 mg/100 cm2 (0.16 to 1.13 g/m2).
50
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Table 5-3. Comparison of Residual Duct Dust Mass Measurements With the MVDS and the NADCA
Vacuum Methods Following HAC System Cleaning
mg/100 cm2
House
Location
NADCA
MVDS
TH
__a
-
1
Main Supply Trunk
2.4
Main Supply Trunk - Site 2
0.12
4.1
2
Main Supply Trunk
0.36
1.8
Main Supply Trunk - Duplicate
0.34
1.6
3
-
4
_a
-
5
Main Supply Trunk
0.30
3.2
Main Supply Trunk - Duplicate
0.32
3.2
Return Duct
0.35
2.5
6
Main Supply Trunk
0.27
1.8
Main Supply Trunk - Duplicate
0.24
2.3
Return Duct
0.27
1.9
7
Main Supply Trunk - Left
0.08
6.9
Main Supply Trunk - Right
0.13
4.4
Main Supply Trunk - Right - Dup.
0.13
8.0
Return Duct at Grille
0.01
3.4
8
Main Trunk-Right
0.07
11.3
Main Trunk-Right - Duplicate
0.06
6.3
Main Supply Trunk Near End Cap
0.03
4.4
Return Duct
0.05
1.9
a No samples; ducts internally lined or flexible duct
b Invalid sample
Although both visual observations and MVDS measurements indicated that the cleaning methods
effectively removed particulate and fibrous material from the surfaces of HAC system components, there was
always residual dust that could be collected with the MVDS method following cleaning. As shown in Table
5-2, the residual dust measurements in the supply and return ducts ranged from 0.06 to 1.97 g/m2. A total of
37 post-cleaning samples were collected from surfaces in the supply ductwork at the nine homes in the study.
The mean "residual dust" after cleaning for the 37 samples was 0.448 ± 0.030 g/m2. For the 21 post-cleaning
samples collected in the return ducts, the mean was 0.401 ± 0.400 g/m2. The mean for all 58 post-cleaning
samples was 0.431 ± 0.337 g/m2 (4.3 mg/100 cm2). The MVDS was specially developed for this study and
51
-------
has a higher collection efficiency due to the higher air flow rate and use of a brush on the nozzle. The data
from this study demonstrate that the NADCA Standard 1992-01 criterion of 1.0 nig/100 cm2 to document the
effectiveness of cleaning should only be applied to samples collected with the Standard 1992-01 vacuum test
method. The criterion of 1.0 mg/100 cm2 is not appropriate for samples collected with the MVDS sampling
method. Results from this study and from measurements performed in the Pilot Air Conveyance System
tests performed prior to the field study (VanOsdell et al., 1997), suggest that a criterion approximately 5
mg/100 cm2 (0.5 g/m2) may be more appropriate for samples collected with the MVDS.
Duplicate measurements were collected at a number of locations with both the NADCA vacuum method
and the MVDS. Results for the NADCA method are presented above in Table 5-3. As shown in the Table,
the precision of the method was very good. Results of duplicate measurements with the MVDS are presented
in Table 5-4. The table includes duplicates for pre-cleaning samples, listed first for each house and having
concentrations generally above 0.5 g/m2, and post-cleaning samples. Twenty-one of the 28 sets of collocated
samples have a relative standard deviation below 25 percent. Five sets of duplicates with a RSD greater than
25% were post-cleaning samples.
At Houses 6,7, and 8, additional duct dust samples were collected to evaluate the effect of brushing
versus airwashing only. After collecting the initial pre-cleaning sample, the vacuum system was attached to
place the duct section under negative air pressure, then the section of duct was cleaned by high pressure air
washing only with pressure ranging from 135 to 165 pounds per square inch (psi) and without mechanical
brushing. An "after air-washing" sample was then collected. The duct was then cleaned with a rotary brush
and airwashed again to remove the loosened dust, A final post-cleaning sample was then collected. The
results of these tests are summarized in Table 5-5. At all three houses, the airwashing procedure removal a
substantial amount of loose dust from the surface of the duct as indicated by the difference between the Initial
sample and the After Airwash sample. Brushing followed by airwashing removed substantially more;
brushing was necessary to effectively clean the surface. Although the testing was limited in scope, it clearly
indicates the importance of brushing for cleaning duct surfaces.
52
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Table 5-4. Results of Duplicate Duct Dust Measurements With The MVDS
g/m2
House
Location
Primary
Duplicate
Mean
S.D
%RSD
TH
Supply"
0.80
1.09
0.94
0.20
22
1
Supply*1
10.80
11.89
11.85
0.06
L
Supply15
26.28
100.72
63.65
52.64
83
Return*
0.24
0,25
0.25
0.007
3
2
Supply*5
2.22
2.73
2.48
0.36
15
Supply4
0.18
0.16
0.17
0.01
1
3
Return15
13.15
16.54
14,85
2.40
16
Supply
0,54
0.34
0,44
0.14
32
Supply"
0.19
0.26
0.23
0.05
22
Return8
0.42
0.37
0.40
0.04
9
4
Supply8
1.27
1.47
1.37
0.14
10
Returnb
6,22
5.11
5.67
0.78
14
Duct Liner"
1.62
1.55
1.59
0.05
3
Supply*
0.34
0.12
0.23
0.16
80
5
Supply*1
2.62
2.52
2,57
0.07
3
Returnb
11.49
10.47
10.98
0.72
7
Supply8
0.32
0.23
0.28
0.06
23
Return8
1.97
0.59
1.28
0.98
76
6
Supply*1
2.00
2.03
2.02
0.2
1
Return15
3.62
6.52
5.07
2.05
40
Return8
0.18
0.23
0.21
.04
17
7
Supply"
4.22
5.07
4.65
0,60
13
Returob
9.03
11.66
10.35
1.86
18
Supply8
0.44
0.80
0.62
0.25
41
8
Supply1*
36.07
45.98
41.03
7.01
17
Supply"
1.13
0.63
0.88
0,35
40
Supply8
0.80
0.65
0.73
0.11
15
Return*
0.19
0.26
0.23
0.05
22
¦ Post-cleaning surface dust samples
b Pre-cleaning surface dust samples
53
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Table 5-5. Results of the Evaluation of Brushing Versus Air Washing
House
Location
g/m2
Initial*
After Airwash
Final
6
Main Trunk Near End Cap
2.00
0.73
0.18
Main Trunk Near Middle
2.45
1.17
0.18
Return Duct Near AH
24.11
1.10
0.13
7
Main Supply Trunk
5.93
3.23
0.69
8
Main Supply Trunk - Right
36.07
2.09
0.63
Main Supply Trunk - Left
28.85
4.09
0,65
" Initial = Prior to cleaning; After Airwash = After airwashing, but prior to brushing; Final = After brushing
followed by airwashing
5.4.2 Microbial Surface Loading Measurement Results
The results of the microbial surface sampling are summarized in Tables 5-6,5-7, and 5-8. The tables
present the mean concentration measured at multiple locations in the ducts. Samples were generally collected
from the bottom surface of the ducts. The number of locations at which samples were collected is indicated
as "N" in the table and the minimum and maximum concentrations are also presented. Results are presented
for both the supply side and return ducts prior to, and following, HAC cleaning. The complete data set is
included in Appendix D. Table 5-6 shows results of the bacterial sampling in Houses 1 through 8. The
results of the surface fungal sampling in the eight field study houses are presented in Table 5-7, The data
from the EPA Indoor Air Quality Test House, presented in Table 8, have been separated from the field study
homes because the ducts at the test house were lined with fibrous glass duct liner, while the other eight houses
had galvanized steel or flexible ducts. As discussed in Section 4.2.6, two different methods were used to
collect surface samples from the ducts, a vacuum method and a swab method. The development and use of
these two methods was discussed in depth in the Air Conveyance System Cleaning Pilot System
Development, Characterization, and Operation: Project Work and QA Plan (RTI, 1995) and Field
Microbiological Investigation of Ventilation System Cleaning: Project Work/QAPlan (RTI, 1996). For
the hard surface galvanized steel, little difference was anticipated between the results of these two methods;
therefore, the data from both the swab and the vacuum methods have been combined. However, differences
are anticipated in the results using the two methods for the porous materials. Therefore, only the vacuum
results are summarized from the test house,
54
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As can be seen in Table 5-6, the bacteria levels in samples collected from the duct surfaces prior to HAC
system cleaning were generally low. No unusual or unexpected bacteria were isolated from any of the
samples. The highest levels of bacteria were isolated from House 4 in the pre-clcaning return duct samples.
As indicated by the standard deviation and minimum and maximum values in the tables, the concentrations of
bacteria in the surface samples were also highly variable.
The impact of mechanical cleaning of the HAC system without use of chemical biocides on ductwork
surfaces following cleaning was variable and the results are inconclusive. There were some differences
between the pre-cleaning and post-cleaning samples in both the supply and return ducts. However, there was
no clear trend. Although the mean bacteria concentrations decreased following cleaning of the supply ducts at
four homes, there were high concentrations of bacteria in the post-cleaning supply duct samples at the other
four homes. For samples collected from the return ducts, the post-cleaning concentrations were lower at
seven of eight homes. At the three homes with the highest pre-cleaning mean concentration (houses 2,4, and
6,), the post-cleaning concentrations were substantially lower. It is not evident why the impact of cleaning on
return ducts would differ from that on supply ducts. The results, therefore, are generally inconclusive with
regarding to evaluating the impact of mechanical cleaning on bacterial surface loading. Chemical biocides are
frequently applied to surfaces following mechanical cleaning. But because chemical biocides were not used
in this study, evaluation of the practice of applying biocides following cleaning could not be evaluated.
55
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Tabic 5-6. Results of Surface Samples of Bacteria in the Supply and Return Ducts
Cfu/cm2
SUPPLY
RETURN
House
Summary Statistic
Pre-clean
Post-clean
Pre-clean
Post-clean
1
Mean
166
266
20
a
StdDev
379
311
21
Min
5
5
5
js
Max
1100
760
35
a
N
8
8
2
2
Mean
36
28
235
20
StdDev
17
37
134
7
Min
10
5
140
15
Max
55
95
330
25
N
6
6
2
2
3
Mean
11
14
78
8
StdDev
9
8
10
6
Min
5
5
70
5
Max
25
20
90
15
N
4
4
2
2
4
Mean
120
365
1233
33
StdDev
134
482
1007
14
Min
25
25
300
25
Max
350
1200
2300
50
N
4
4
2
2
5
Mean
SI
20
26
13
StdDev
146
27
25
12
Min
5
5
5
5
Max
300
60
60
30
N
4
4
4
4
6
Mean
14
73
143
8
StdDev
11
63
100
6
Min
5
5
5
5
Max
30
140
270
20
N
6
6
6
6
7
Mean
404
85
128
278
StdDev
341
112
103
385
Min
25
5
55
5
Max
800
250
200
550
N
4
4
2
2
8
Mean
64
53
83
53
StdDev
69
75
60
55
Min
5
5
5
5
Max
150
200
150
100
N
6
6
4
4
* No sample collected
-------
Table 5-7. Results of Surface Samples of Fungi in the Supply and Return Ducts
Cfu/cm2
SUPPLY
RETURN
House
Summary Statistic
Pre-clean
Post-clean
Pre-clean
Post-clean
1
Mean
35700
1206
2650
a
StdDev
86642
1546
3041
JH
Min
1900
25
500
_a
Max
250000
4700
4800
J1
N
8
8
2
2
Mean
9217
138
280
153
Std Dev
6367
248
57
152
Min
1200
10
240
45
Max
19000
640
320
260
N
6
6
2
2
3
Mean
4604
740
22333
147
StdDev
3423
750
5508
51
Min
20
100
16000
90
Max
8300
1700
26000
190
N
4
4
2
2
4
Mean
73400
15890
850
617
Std Dev
69366
15935
304
375
Min
500
950
650
250
Max
160000
36000
1200
1000
N
4
4
2
2
5
Mean
35
46
58
71
StdDev
50
52
35
53
Min
5
5
25
15
Max
110
120
90
140
N
4
4
4
4
6
Mean
113
61
613
7
StdDev
89
59
998
4.
Min
15
5
20
5
Max
250
130
2600
15
N
6
6
6
6
7
Mean
1089
49
2200
23
Std Dev
1879
68
283
25
Min
15
10
2000
5
Max
3900
150
2400
40
N
4
4
2
2
8
Mean
63
7
196
10
StdDev
56
4
101
6
Min
25
5
75
5
Max
170
15
320
15
N
6
6
4
4
a No sample collected
57
-------
Table 5-8. Results of Surface Samples at the IAQ Test House
f!fii/em2
SUPPLY
RETURN"
Organism
Summary Statistic
Pre-clean Post-clean
Pre-clean Post-clean
FUNGI
Mean
StdDev
Min
Max
N
81250 4853
112964 2743
13000 810
250000 6900
4 4
-
BACTERIA
Mean
StdDev
Min
Max
N
37 295
55 593
5 5
100 1500
4 7
* Return duct was removed and replaced with new duct; no samples collected
A summary of the results of the surface fungi sampling is presented in Table 5-7, The mean colony
forming units (cfus) of fungi isolated per cm2 in the pre-cleaning supply samples ranged from 35 to 73,400;
while in the return, they ranged from 58 to 22,300. In Houses 1,2, and 4, considerably higher numbers of
fungi were isolated from the supply side samples, while in House 3, more fungi were isolated from the return.
For the rest of the houses, the levels were similar and demonstrated considerable overlap in the minimum and
maximum numbers of cfus isolated. Mechanical cleaning without use of chemical biocides resulted in a
reduction of fungi in the surface samples at all houses except House 5, which had low levels of fungi in the
surface samples. There was a large change in concentrations between the pre-cleaning and post-cleaning
samples at some of the study homes. But the variability of the fungi surface sample concentrations was large,
as indicated in Table 5-7 by the standard deviation, making it difficult to assess the significance of the impact
of mechanical cleaning of the HAC system on fungi levels on the surfaces. As noted above, chemical
biocides, although frequently used by HVAC system cleaning contractors, were not used or evaluated in this
study.
The results of the surface sampling in the EPA IAQ Test House are summarized in Table 5-8. When
interpreting the results of measurements at the test house, it should be noted that the cleaning procedures
employed at the house were probably not typical of what would be used by HVAC system cleaning
contractors faced with the situation at the house. The supply duct at the Test House was internally-lined with
fibrous glass duct liner that had become heavily contaminated with fungal growth due to previous problems
with the condensate drain pain and intrusion of water into the supply duct Pre-cleaning sampling showed
58
-------
that fungal levels on the supply duct liner were high (Table 5-8). No return microbiological samples were
collected; the flexible return duct in the house was removed and replaced as part of the HAC system cleaning
process. There were large variations in fungal cfu/cm2 between sample locations as indicated by the large
standard deviation for the four samples collected. Following mechanical cleaning of the internally-lined
supply ducts, the level of fungi isolated from the surface samples was substantially less than in the pre-
cleaning samples. However, there were still high levels of organisms in the post-cleaning surface samples,
relative to the levels observed in the galvanized and flexible ducts in most of the other study homes (Table 5-
7). The predominant fungi isolated from the pre-cleaning samples were yeasts; while few were isolated from
the post-cleaning samples. The samples of bacteria collected after cleaning were highly variable, as indicated
by the standard deviation. The levels after cleaning were higher than prior to cleaning.
The typical practices for cleaning and remediation of internally-lined ducts with fungal contamination
would be to either (1) remove and replace the entire fibrous glass duct liner or (2) to apply an encapsulant.
generally one containing a biocide, to the surface of the duct liner. Because of the research nature of this
study and the desire to use the Test House facility for further HAC system cleaning research, neither practice
was implemented during this study. Testing of encapsulants and biocides is planned as part of future testing.
Therefore, the results of measurements from the Test House should not be used to evaluate the impact of
HAC system cleaning on fungal or bacterial contamination on duct surfaces.
5.4.3 Surface Dust Samples
On the day that the sampling and monitoring instrumentation was set up at each house, two dust samples
were collected with the MVDS from surfaces of furnishings in the home. The objective of collecting these
samples was to assess whether there was a relationship between surface dust samples and levels of dust in the
HAC system. Results of the surface dust sample measurements are presented in Table 5-9. Surface dust
levels were generally below 0.5 g/m2. The levels were above 1.0 g/m2 only at House No. 5. There was no
apparent relationship between the levels of dust on the surfaces of furnishings and the amount of dust
measured in either the supply or the return ducts of the HAC system. The surface dust levels were lowest at
House No. 8, which had the highest dust levels in the HAC system.
5.5 Measurement Results for Selected Indoor Air Quality Parameters
Air monitoring and sampling were performed at each study home prior to, and following, HAC system
cleaning in an attempt to determine whether the cleaning had short-term impacts on IAQ parameters. The
parameters measured included particles, fibers, and fungi. Measurements were made using continuous
monitoring instrumentation for particles and by collection of integrated samples. The results are described
and discussed in the following sub-sections.
59
-------
Table 5-9. Results of Measurements of Surface Dust on Furnishings
House
R/m2
Surface Dust
Duct Dust (Avg)
Site 1
Site 2
Supply
Return
TH
0.44
0.15
2.33
1
0.53
0.37
8.62
19.83
2
0.45
0.26
3.37
24.13
3
0.38
0.39
1.91
7.80
4
0.65
0.44
1.48
7.89
5
1.30
1.70
2.28
11.34
6
0.51
0.18
2.30
5,26
.7
0.13
0.08
3.34
12.91
8
ND
0.05
26.03
35.11
" ND: Not detected above detection limit
5.5.1 Respirable and Inhalable Particle Mass Concentrations
Respirablc particles, defined as particles with a mean diameter less than 2.5 |im (PMZS), and inhalable
particles, defined as particles with a mean diameter less than 10 pm (PM10), were collected using size-
selective impactors. Two sequential 24-hr samples were collected prior to HAC system cleaning and two 24-
hr samples were collected following cleaning. The post-cleaning samples were started on the morning of the
day following HAC system cleaning to avoid the impact of the activities on the day of cleaning which may
have affected particle concentrations due to opening of windows and doors, as well as high human activity in
the home. The objective was to determine if HAC system cleaning had a short-term impact cm particle levels
in the home. Samples were also collected outdoors for comparison.
Concentrations of PM2 5 are presented in Table 5-10 for pre- and post-cleaning samples. Concentrations
of PMI0 are presented in Table 5-11. In both tables, data are presented for outdoors and for the two indoor
locations (primary and secondary). The concentrations of both PM25 and PM,0 indoors are low and are
typical of concentrations measured indoors if there is no tobacco smoking (Wallace, 1996).
60
-------
Table 5-10. PM25 Measurement Results
3
Pre-Clcaning
pfc
Post-Cleaning
Sample
Sample
Sample
Sample
Post/
House
Location
1
2
Mean*
SD"
1
2
Mean
SD
Pre
TH
Outdoor
23.4
23.1
23.3
0.2
18.4
22.5
20.4
2.9
0.88
Primary
7.7
7.3
7.5
0.3
10.4
10.3
10.3
0.1
1.37
Secondary
6.9
8.6
7.8
1.2
10.4
11.1
10.8
0.5
1.38
1
Outdoor
5.0
12.2
8.6
5.1
_b
28.1
28.1
-
3.27
Primary
5.4
7.5
6.5
1.5
12.6
17.9
15,3
3.7
2.36
Secondary
5.2
7.3
6.3
1.5
13.6
18,4
16.0
3.4
2.56
2
Outdoor
11.7
11.5
11.6
0.1
25.4
33.2
29.3
5.5
2.53
Primary
7.0
16.5
11.8
6.7
13.6
20.1
16.9
4,6 .
1.43
Secondary
6.6
14.3
10.5
5.4
14.7
18.8
16.8
2.9
1.60
3
Outdoor
36.4
33.6
35.0
2.0
21.6
28.9
25,3
5.2
0.72
Primary
17.2
15.8
16.5
1.0
11.0
15.5
13,3
3.2
0.80
Secondary
17.1
16.2
16.7
0.6
10.2
14.4
12.3
3.0
0.74
4
Outdoor
25.8
23.4
24.6
1.7
26.7
40.9
33.8
10.0
1.37
Primary
12.2
11.4
11.8
0.6
19.2
32.1
25.7
9,1
2.17
Secondary
10.1
11.4
10.8
0.9
14.4
29.3
21.9
10.5
2.03
5
Outdoor
18.3
10.4
14.4
5.6
22.6
23
22.8
0.3
1.59
Primary
6.6
4.7
5.7
1.3
10.3
10.2
10.3
0.0
1.81
Secondary
5.2
5.2
5.2
0.0
9.8
11.5
10.7
1.2
2.05
6
Outdoor
11
18.5
14.8
5.3
24.2
19
21.6
3.7
1.46
Primary
7.3
5.6
6.5
1.2
8.7
4.9
6.8
2.7
1.05
Secondary
10.4
6.1
8.3
3,0
8.9
7.7
8.3
0.8
1.01
7
Outdoor
_b
21.3
21.3
-
8.5
16.5
12.5
5.7
0.59
Primary
11.2
12.1
11.7
0.6
8.2
8.8
8.5
0.4
0.73
Secondary
11,4
11.1
11.3
0.2
6.6
8.7
7.7
1.5
0.68
g
Outdoor
Jb
13.7
13.7
-
14.7
20.1
17.4
3.8
1.27
Primary
17.3
5.3
11.3
8,5
-C
13.2
13.2
-
1.17
Secondary
10.6
4.7
7.7
4.2
8.2
13.6
10.9
3.8
1.42
1 Mean and Standard Deviation for two samples
b Sample lost due to power failure
e Sample not valid
61
-------
Table 5-11. PM, 0 Measurement Results
iie/m3
Pre-Cleaning
Post-Cleaning
Sample
Sample
Sample
Sample
Post/
House
Location
1
2
Mean8
SD°
1
2
Mean
SD
Pre
TH
Outdoor
28.3
27.9
28.1
0.3
23.3
28.8
26.1
3.9
0.93
Primary
13.1
9.1
11.1
2.8
24.4
33.7
29.0
6.6
2.61
Secondary
9.5
9.5
9.5
0.0
9.3
19.1
14,2
6.9
1.49
J
Outdoor
11.7
17.1
14.4
3.8
_b
33.8
33.8
-
2.35
Primary
10,7
10.6
10.7
0.0
21.3
22.9
22.1
1.1
2.08
Secondary
8.0
9.2
8.6
0.8
17.0
20.3
18.7
2.3
2.17
2
Outdoor
15.5
21.9
18.7
4.5
29.5
36.1
32.8
4,7
1.75
Primary
8.1
22.3
15.2
10.0
15.8
22.6
19.2
4.8
1.26
Secondary
7.6
16.6
12.1
6.4
7.9
18.2
13.1
7.3
1.08
3
Outdoor
41.8
42.4
42.1
0.4
22.3
34.7
28.5
8.8
0,68
Primary
16.5
18.8
17.7
1.6
16,1
18.6
17,4
1.8
0.98
Secondary
17.9
19.8
18.9
1.3
13.4
18.9
16.2
3.9
0.86
4
Outdoor
29.9
27.6
28.8
1.6
34.1
48.9
41.5
10.5
1.44
Primary
14.7
16.5
15.6
1.3
26.9
40,2
33.6
9.4
2.15
Secondary
13.6
11.6
12.6
1.4
11.9
10,1
11.0
1.3
0.87
5
Outdoor
20.2
17.8
19.0
1.7
26.8
33,7
30.3
4.9
1.59
Primary
7.2
12,8
10.0
4.0
14.2
13
13.6
0.8
1,36
Secondary
6.8
10.6
8.7
2.7
14.4
13.2
13.8
0.8
1.59
6
Outdoor
17.4
29.3
23.4
8.4
16.3
24.9
20.6
6.1
0.88
Primary
11.6
9
10.3
1.8
12.6
6.7
9,7
4.2
0.94
Secondary.
_b
9.7
9.7
-
_b
8.4
8.4
-
0.87
7
Outdoor
_b
26.2
26.2
-
19.0
23.0
21.0
2.8
0,80
Primary
13.1
15.5
14.3
1.7
11.0
11.7
11.4
0.5
0.79
Secondary
12.5
13.8
13.2
0.9
11.3
11.3
11.3
0.0
0.86
8
Outdoor
_b
26.2
26.2
-
19.0
25.1
22.1
4.3
0.84
Primary
14.6
7.1
10.9
5.3
8.0
17.4
12.7
6.6
1.17
Secondary
13.7
17.7
15.7
2.8
10.4
16.9
13.7
4.6
0.87
* Mean and Standard Deviation for two samples
b Sample lost due to power failure
62
-------
Indoor concentrations of PM2 S were in the range from 5.2 to 32.1 pg/m3. PM10 concentrations ranged
from 6,7 to 40.2 ng/m3. The highest indoor concentrations were measured at House No. 4 in the post-
cleaning samples. The outdoor air concentrations measured at the house were also the highest during the
study. As shown in Table 5-10, the concentrations of PM2 5 were similar at the primary and secondary
locations indoors for both pre-cleaning and post-cleaning samples. The concentrations were more variable
for the two indoor locations for PMI0. For example, at House No. 4, the concentrations of PM,0 in post-
cleaning samples were three to four times higher in the secondary location than in the primary location. This
was an upstairs location near the bedrooms of the two children whose activity may have impacted airborne
levels of the larger particles.
Interpretation of the PM25 and PM,0 results is difficult because the concentrations of PM,0 and PM1S
outdoors will have an impact on indoor concentrations. Because the outdoor concentrations varied over the
course of the week-long study, it is difficult to determine if changes in indoor concentrations after cleaning
are the result of HAC system cleaning or due to changes in outdoor concentrations or changes in occupant-
activities. In Tables 5-10 and 5-11, the final column is the ratio of the mean post-cleaning concentration
divided by the mean pre-cleaning concentration at each sampling location at each house. If the indoor ratio is
less than one, it may mean that HAC system cleaning resulted in lower airborne particle concentrations
However, interpretation of the data is complicated if the outdoor concentration also went down during the
post-cleaning period. The post/pre-cleaning change is depicted qualitatively in Table 5-12 to show the
trends. For example, at House 1, the higher indoor post-cleaning concentrations were coincident with higher
concentrations outdoors. But at House 3, despite the fact that the outdoor concentrations of PM2S and PM10
were lower in the post-cleaning period, the indoor concentrations were similar during the pre- and post-
cleaning periods.
Another way to evaluate the relationship between indoor and outdoor concentrations is to compare the
indoor/outdoor ratios (I/O), also presented in Table 5-12. Interpretation of the indoor/outdoor ratios is
complex. If the I/O ratio is lower in the post-cleaning sample, this would suggest that the HAC system
cleaning resulted in lower airborne particle concentrations if the infiltration of particles into the home from
outdoors occurred at the same rate during the post-cleaning period as in the pre-cleaning period. This
assumption may be valid for PM25. To fully evaluate the I/O, the following cases need to be examined:
»If the concentration of particles in the indoor air is reduced due to HAC system cleaning and the outdoor
concentration and infiltration rate are the same before and after cleaning, then the I/O should be lower in the
post-cleaning period. House 6 represents the only case where this occunred, and only for PM2 s.
63
-------
Table 5-12. Trends in Particle Concentrations and Indoor/Outdoor Ratios
Concentration
Indoor/Outdoor Ratio
Chang
m,
PM,0
PM
House
Location
Pre
Post
Pre
Post
TH
Outdoor
=
=
Primary
H
H
0.32
0.51
0.40
1,12
Secondary
H
H
0.33
0.53
0.34
0.55
1
Outdoor
H
H
Primary
H
H
0.75
0.54
0.74
0.65
Secondary
H
H
0.73
0.57
0,60
0,55
2
Outdoor
H
H
Primary
H
=
1.01
0.58
0.81
0.59
Secondary
H
=
0.90
0.57
0.65
0.40
3
Outdoor
L
L
Primary
=
=
0.47
0.52
0.42
0.61
Secondary
_
m.
0,48
0.49
0.45
0,57
4
Outdoor
H
H
Primary
H
H
0,48
0.76
0.54
0.81
Secondary
H
SB
0.44
0.65
0.44
0.27
5
Outdoor
H
H
Primary
H
H
0.39
0.45
0.53
0.45
Secondary
H
H
0.36
0.47
0.46
0.46
6
Outdoor
=
=
Primary
=
=
0.44
0.31
0.44
0.47
Secondary
=
=
0.56
0.38
0.42
0.41
7
Outdoor
L
L
Primary
L
L
0.55
0.68
0.55
0.54
Secondary
L
L
0.53
0.61
0.50
0.54
8
Outdoor
H
L
Primary
=
H
0.82
0.76
0.41
0.58
Secondary
sr
L
0.56
0.63
0.60
0.62
: lower
concentration in post cleaning period; = not substantially different between pre- and post-cleaning periods
64
-------
• If the outdoor concentration is higher in the post-cleaning period, an I/O of greater than 1.0 may result
from the increased infiltration of particles from outdoors, masking a reduction of particles due to HAC
system cleaning.. If the I/O ratio was equal or less than 1.0, there may have been an impact of HAC system
cleaning on particle concentrations, but the magnitude of the effect can not be determined because the
contribution from outdoors can not be quantified. At Houses 1 and 2 the post-cleaning ratios are somewhat
lower than the pre-cleaning ratios, which may indicate an effect of HAC system cleaning, if one assumes that
the particle infiltration rate was the same in both the pre- and post-cleaning periods. At Houses 4 and 5, the
higher outdoor concentration in the post-cleaning period did not result in a substantial lowering of the I/O
ratio indoors in the post-cleaning period.
* If the outdoor concentration of particles is less in the post-cleaning period, a I/O greater than one
suggests that there was not a substantial effect of HAC system cleaning on particle concentrations. But I/O
ratios less than one do not necessarily mean there was an effect. At House 7, for example, the post-cleaning
ratio was 0.68 at the primary location. This was higher than the pre-cleaning ratio, suggesting no effect from
HAC system cleaning.
Results of the PM2 S and PM,0 data collected by the integrated sampling method are inconclusive with
respect to the impact of HAC system cleaning on indoor air particle mass concentrations It appears that the
integrated particle mass data are not useful to assess whether HAC system cleaning has an impact on
rcspirable and inhalable particle concentrations. Not only is there no clear trend, but there is insufficient data
to determine what is a significant difference when comparing I/O ratios. It appears that the impact of outdoor
particle concentrations and occupant activity on indoor particle mass concentrations may be so substantial
that, even though the source of particles in the HAC system is effectively removed, changes in airborne
particle mass concentrations due to HAC system cleaning can not be detected because of the other particle
sources and temporal variability of particle concentrations.
The impact of HAC system cleaning on airborne particle concentrations is further evaluated in the
following subsection.
5.5.2 Particle Concentrations Measured With Real-Time Monitors
Particle concentrations were measured during the entire study period at each house with Climet CI-4100
Laser Particle Counters and a LAS-X Laser Spectrometer. The results of the measurements are described in
this section.
65
-------
5.5.2.1 Results of Qimet Measurements
Climets were located in a primary living area of the house and a secondary, lesser used room. Additionally, a
Climet was placed near a supply diffiiser in the primary living area in an attempt to gain better resolution of the
particle concentrations related to the HAC system operation as compared to that in the room where occupant
activity may have had a significant impact on airborne concentrations. Particles were measured in the >0.5 jim
diameter size range and in the >5.0 jun size range.
The differences in the concentration of particles in the size fraction greater than 0.5 (xm between pre- and post-
cleaning periods are summarized in Table 5-13. The table presents the mean concentration and the standard
deviation for the entire period prior to HAC system cleaning compared to the mean for the entire period following
HAC system cleaning. The duration of the periods were not necessarily the same. The ratio of the post-cleaning to
pre-cleaning periods is presented in the last column of the table. Results are presented for measurements in the
primary monitoring location at 1.1 m above the flow, for the Climet located next to a supply diffiiser in that room,
and for the secondary monitoring location in the house. The data do not include the measurements on the day of
cleaning because particle concentrations on that day would be atypical due to the high level of activity and open
doors and windows.
Mean particle concentrations at the nine homes of the study ranged from 0.49 to 22.88 million particles per m3.
The concentrations were generally similar for die three monitoring locations in each home. At House 3 and 6, the
concentrations were somewhat higher for the monitor placed at the supply diffuser. It should be noted that the
concentrations of particles were highly variable during both the pre- and post-cleaning periods, as indicated by the
large standard deviation. The concentrations of particles >0.5 pm were lower during the period following HAC
system cleaning at the test house and at two of the field study homes (Houses 3 and 8). At Houses 4 and 7, the
concentrations were nearly the same in the pre- and post-cleaning periods. At houses 1,2,5, and 6 the average
particle concentrations were higher in the post-cleaning period.
In Table 5-13, the houses are separated by double lines, indicating that two houses were studio! each week,
beginning with houses 1 and 2. There is a clear trend evident in Table 5-13 for the Post/Pre-cleaning ratio.
Houses, that were studied on the same week showed similar changes in concentration between pre- and post-
cleaning periods. The Post/Pre-cleaning ratio was higher at both houses 1 and 2, cleaned on the same week.
Houses 7 and 8, cleaned cm a different week, had a ratio of less than 1.0. Although this could be strictly
coincidence, the trend suggests that the indoor concentration changes during the study week were a function of the
outdoor concentrations. Particle concentrations woe not measured continuously outdoors. The data for the
integrated samples of PM2 5 and PM,0 can be used to assess differences in indoor and outdoor particle
concentrations and differences between pre- and post-cleaning periods. Tables 5-10 and 5-11 in Section 5.5.1
show the results of integrated samples. For the PM2 5 size fraction, outdoor particle mass was higher in the post-
cleaning period than in the pre-cleaning period at houses 1,2,4,5,6, and 8, Houses 1,2,5, and 6 are the same
houses that had higher particle concentrations measured with the Climet in the post-cleaning period.
66
-------
Table 5-13. Mean Concentrations of Particles Greater Than 0.5jim Pre- and Post-HAC System Cleaning
Particles X 106/m3
Pre-Cleanine"
Post-Clcanineb
Post/
House
Location
Mean0
SDC
Mean
SD
Pred
TH
Primary
6.97
4.06
4.68
4.25
0.67
Primary - Supply
e
-
4.15
3.41
Secondary
5.90
3.66
4.51
2.11
0.77
1
Primary
5.60
2.75
9.87
3.59
1.76
Primary - Supply
3.48
2.52
8.48
3.22
2.44
Secondary
2.07
2.03
7.52
3.22
3.63
2
Primary
7,21
3,68
14.02
0.49
1.94
Primary - Supply
8.90
1.78
13.92
0.41
1.56
Secondary
9.03
3.13
14.18
6.91
1.57
3
Primary
16.01
6.61
13.08
7,16
0.82
Primary - Supply
22.88
8.60
19.14
10.69
0.84
Secondary
17.05
5.26
12.22
5.52
0.72
4
Primary
10.98
4,70
11.27
4.54
1.03
Primary - Supply
10.41
5.64
11.61
4.20
1.12
Secondary
8.32
4.46
6.92
1.46
0.83
5
Primary
3.52
2.56
6.80
3.98
1.93
Primary - Supply
3.53
1.61
6.31
3.52
1.79
Secondary
3.97
1.35
6.60
2.97
1.66
6
Primary
5.06
4.86
7.11
4.88
1.41
Primary - Supply
7.39
5.30
9.66
4.85
1.31
Secondary
4.85
4,81
3.94
2.61
0.81
7
Primary
8.07
6.57
7.78
3.62
0.97
Primary - Supply
7.45
5.99
7.21
3.32
0.97
Secondary
6.32
5.55
6.40
3.32
1.01
8
Primary
20.15
8.77
16.35
9.11
0.81
Primary - Supply
_r
-
21.17
10.69
_r
Secondary
15.09
6.70
12.84
6.90
0,85
a Mean of concentration for entire period prior to 6:00 a.m. on day of cleaning
b Mean of concentration for entire period from 6:00 a.m. on day following cleaning to end of study period
0 Mean and standard deviation for entire period
d Ratio of the means
8 Data lost due data logger problem
f Data lost due to power failure
67
-------
At house 8, the first pre-cleaning PM2 s sample was lost due to a power failure so the basis for comparing
pre- and post-cleaning periods is poor. It should also be noted from Table 5-10 that at all houses, except the
Test House, when outdoor PM2 5 was higher outdoors in the post-cleaning period, it was also higher indoors
in the post-cleaning period, PM]0 mass was also measured outdoors during the study. As shown in Table 5-
11, PM,0 was higher outdoors in the post-cleaning period at Houses 1,2,4, and 5. Houses 1,2, and 5 were
houses with higher particle concentrations measured with the Climet in the post-cleaning period. As was the
case for PM25, when outdoor PM10 was higher in the post-cleaning period, the indoor PM10 was also higher in
the post-cleaning period. The only exception was in the secondary room at House 4.
The results of the measurements of particles >0.5 pm with the Climets are inconclusive with respect to
determining the impact of HAC system cleaning on indoor air particle concentrations for this size fraction.
The data suggest that the impact of the outdoor particle concentrations may be so substantial that the impact
of HAC system cleaning on airborne particle concentrations can not be detected. The impact of outdoor
particles on indoor concentrations is substantial according to calculations performed by Wallace (1996) in his
review of indoor particles. In his evaluation of the impact of outdoor particles on indoor particle mass
concentrations, he estimated that for a home with no indoor sources and a typical air exchange rate of
approximately 0.75 h"1, the fine particle mass concentration indoors would be about 65% of the outdoor value
at equilibrium while coarse particles would be about 43% of the outdoor value. However, he noted that the
indoor concentrations are rarely this low because there are indoor sources. Referring back to Table 5-8,
which has the Indoor/Outdoor ratios for the particle mass measurements, it can be seen that indoor/outdoor
ratios of PM25 were less than 0.65 for many of the samples. The significance of this observation is not
obvious.
Data from the Climet for the greater than 5.0 pm size fraction were downloaded from the Climet's internal
storage whenever the technician visited a house. Because of the frequency of the visits, a relatively complete
data set was obtained. Mean concentrations of particles >5.0 pm were also calculated for pre- and post-
cleaning periods and are presented in Table 5-14.
The mean concentrations of particles >5.0 pm ranged from 0.006 to 0.346 million per m3 (6,000 to
346,000/m3). As shown by the standard deviation, the concentrations varied substantially during the periods.
The concentrations measured at the three monitoring locations at each home did not differ substantially,
except at House 5, where the concentration in the second room was substantially higher both pre- and post-
HAC system cleaning. There was no clear trend in the change between pre- and post-cleaning, as indicated
by the Post/Pre-cleaning ratios. Of the six field study houses with data for the >5.0 pm fraction, three had
lower post cleaning concentrations, one was nearly the same, and the other two were higher. Comparison of
the data for the > 5.0 pm size fraction and the > 0.5pm size fraction shows no apparent relationship between
the Post/Pre ratios for the two size fractions.
68
-------
Table 5-14. Mean Concentrations of Particles Greater Than 5.0|im Pre- and Post-HAC System Cleaning
Particles X 10s/m3
Prc-Clcanine"
Post-Cleaning
Post/
House
Location
Mean®
SDC
Mean
SD
Pred
TH
Primary
0.044
0.123
0.058
0.207
1.30
Primary - Supply
_e
-
0.080
0.240
_e
Secondary
0.037
0.093
0.023
0.073
0.62
1
Primary
_e
-
_e
-
_e
Primary - Supply
e
-
e
-
__e
Secondary
-
-
je>
2
Primary
-e
-
J9
-
-
Primary - Supply
__e
-
-
_e
Secondary
-
-
3
Primary
0.011
0.023
0.016
0.020
1.50
Primary - Supply
0.014
0.020
0.020
0.024
1.39
Secondary
0.015
0.018
0.013
0.021
0.85
4
Primary
0.020
0.051
0.016
0.029
0.82
Primary - Supply
0.014
0.037
0.010
0.018
0,69
Secondary
0.017
0.024
0.029
0.025
1.76
5
Primary
_r
-
0.019
0.031
j
Primary - Supply
0.017
0.031
0.013
0.025
0.76
Secondary
0.346
0.051
0.303
0.033
0.88
6
Primary
0.025
0.066
0.027
0.049
1.09
Primary - Supply
0.028
0.078
0.030
0.047
1.08
Secondary
0.023
0.071
0.031
0.051
1.31
7
Primary
0.010
0.019
0.010
0.014
0.94
Primary - Supply
0.006
0.010
0.005
0.007
0,93
Secondary
0.008
0.018
0.008
0.011
0.92
8
Primary
0.008
0.024
0.016
0.040
2.19
Primary - Supply
j
-
0.028
0.053
_f
Secondary
0.013
0.074
0.018
0.059
1.40
" Mean concentration for entire period prior to 6:00 a.m. on day of cleaning
b Mem concentration for entire period from 6:00 a.m. on day following cleaning to end of study period
c Mean and standard deviation
d Ratio of the means
e Insufficient data available; not downloaded with sufficient frequency
f Data lost due to downloading error
69
-------
Comparing the particle concentration data based solely on the mean and standard deviation for the pre-
and post-cleaning periods does not present the entire picture. The time variations in the particle
concentrations should be assessed to determine if there are activities or conditions in the home during the
study that may have impacted the particle concentrations. Figures 5-1 through 5-9 depict the variation in the
concentrations of particles in the >0,5 nm size fraction measured with the Climet in the primary living area in
each home during the study. In the following figures, it should be noted that there are periods when the
particle concentrations exceed the full-scale output capability of the Climet. These periods are indicated in
the figures by flat peaks. This was a limitation of the analog output of the Climet To the extent possible,
data that was over-range was replaced with data that was directly downloaded from the Climet's internal data
logger. However, this was not possible in all cases. The patterns of the particle concentrations in these
figures can be summarized as follows:
* Test House - High concentrations were observed on the Saturday before cleaning due to technician
activity in the house, but concentrations were lower on Sunday and Monday even though there was also
technician activity in the house in the morning on those days. Although particle concentrations were elevated
during the period of cleaning due to the high level of activity and open doors, the concentrations dropped
rapidly after the air handler was turned on. There was no indication of elevated particle concentrations
immediately after cleaning. During the period following HAC system cleaning there were periods of elevated
particle concentrations associated with technician activity in the house. But particle concentrations were
generally low overnight.
• House 1 - During the study, the house was occupied by one adult, who worked during the evening, and
two children during the day-time periods. The other adult in the home worked during the day and was home
with the children in the evening. In the pre-cleaning period, there were periods of elevated particle
concentrations. But the post-cleaning period had substantially higher peak concentrations that exceeded the
range of the IAQDS data logger. The elevated concentrations during the post-cleaning period occurred for
extended durations relative to the pre-cleaning period. Overnight particle concentrations were higher in the
post-cleaning period.
70
-------
45000000
Test House
Climet: >0.5um
40000000 -
35000000
30000000 -
25000000 --
Pre-Clearilng
20000000 -
Cleaning day
15000000 -
10000000 -•
5000000 -
o
(N
O
O
O
CM
O
CM
O
CM
O
©
CN
Fri Sat Sun Mon Tues Wed Thur Frt Sat
Figure 5-1. Airborne particle concentrations in the >0.5 p.m size fraction at the Test House
71
-------
45000000
40000000
35000000
House 1
Climct: >0.5 urn
30000000
E 25000000
Cleaning Day
Pre-Qeanuig
Post-Cleaning
n 20000000
15000000
10000000
Sat
Sun
Mon
Tue
Wed
Thar
Fri
Sal
Rgure 5-2. Airborne particle concentrations in the >0.5 jim size fraction at House 1
72
-------
45000000
40000000
House 2
Cliinet: >0.5um
35000000
30000000
25000000
Pre-Cleaning
20000000
15000000
10000000
5000000
0
o
o
o
o
Sun Mon Tues Wed Thur Fri Sat
Figure 5-3. Airborne particle concentrations in the >0.5 size fraction at House 2
73
-------
House 3
Climet; >A,5um
Post-Cleaning
45000000
Cleaning Day
40000000
Pre-Cleaning
30000000
I 20000000
S.
15000000
10000000
5000000
OCNOCJOCNOCM
Sun Mon Tues Wed
Wed
Figure 5-4, Airborne particle concentrations in the >0.5^m size fraction at House 3
74
-------
45000000
House 4
Climet: >0.5um
35000000
Geaning Day
Post-Clean ing
25000000 -
20000000 -
15000000 --
10000000 --
5000000 --
r>4
O
o
p
M
O
O
o
o
Sun Mon Tuc Wed Thur l-'ri Sat Sun Moti Tuc Wed
Figure 5-5. Airborne particle concentrations in the >0.5 jim size fraction at House 4
75
-------
45000000
House 5
Climet: >0.5um
40000000 --
35000000 •
30000000 - ¦
15000000 ••
5000000 -¦
0.5 size fraction at House 5
76
-------
45000000
40000000
35000000
J 25000000 ¦
8
Cleaning day
¦
30000000
-Yc-cleanmg
20000000 •
15000000
10000000
5000000
House 6
Climet: >().5um
Post-cleaning
jh^sJ
¦ft 00 -<3 90 *0
i—I—I—H-i—I—i—I—i—I—I
\QOCSOOC\Q0Qv£*OO*£3OC>tQOQ*O
Mon
Tue
Wed
Thur
Fd
Sat
Sun
Mon
Tue
Wed
Figure 5-7, Airborne particle concentrations in the >0.5 jim size fraction at House 6
77
-------
45000000
40000000
35000000
30000000
.6 25000000-
V
*3
1 20000000
a,
House 7
Oimet: >0.5uin
Pre-cle&ning
Cleaning day
Post-cleaning
15000000
10000000
5000000
Moil
Tue
Wed
Thur
Fri
Sat
Sun
Mon
Tue
Wed
Fibure 5-8. Airborne particle concentrations in the >0.5 gm size fraction at House 7
78
-------
45000000
35000000
30000000
E 25000000
1
20000000
15000000 •
10000000
5000000
House 8 /
Climet: >0.5um
-cleaning
Cleaning day
Post-clean «ig
Wed
Thur
Fri
Sat
Figure 5-9. Airborne particle concentrations in the >0.5 size fraction at House 8
79
-------
• House 2 - This house was monitored on the same week as house one. It was cleaned on Wednesday.
The house was occupied by two adults, who were both out of the house, at work, during the week days.
Particle concentrations were elevated on Sunday when the occupants were at home and the instrumentation
was set up. But the levels fell on Monday and Tuesday. There was an increase in particle concentrations on
the Tuesday prior to cleaning. Particle concentrations increased substantially on the day of cleaning,
exceeding the IAQDS full-scale range. The particle concentrations stayed above the full-scale range for
nearly the entire post-cleaning monitoring period, even though the occupants were gone during the day. The
reason for these high concentrations is not known.
• House 3 - Particle concentrations were substantially lower in the first four days after cleaning but
increased Sunday through Tuesday due to either higher outdoor concentrations or increased occupant activity.
Results at House 4 suggest the change was due to outdoor concentration increases.
• House 4 - This house was located across the street from House 3, It was cleaned on Wednesday. The
changes in concentration after cleaning are similar to those at House 3. The concentrations after cleaning
were initially lower than during the pre-cleaning period, but on Sunday and Monday the concentrations were
substantially elevated, the same as at House 3. This suggests that the post-cleaning increases at both houses
3 and 4 were due to higher outdoor concentrations.
• House 5 - This house was available for monitoring over a longer period both before and after HAC
system cleaning. The occupants were not in the home from Thursday until Monday evening. Their return to
the house and increased activity is indicated by increased particle concentrations on Monday. After cleaning,
the particle concentrations dropped rapidly. During the following days, there were elevated concentrations
during the day, which dropped overnight when there was no activity. The changes suggest that particle
concentrations were highly impacted by occupant activity.
• House 6 - Prior to cleaning there were short periods of high concentrations, but following cleaning there
were extended periods with high concentrations. The high concentrations occurred on the weekend when
there were periods of high activity in the home. It should be noted that particle concentration, although high
on the day of cleaning, dropped rapidly after the air handler was returned to service.
• House 7 - The house was occupied by two children who were in the home most of the time and two
adults who worked during the day. There was no substantial difference in the peak concentrations or the
variation in the particle concentrations between the pre- and post-cleaning periods.
• House 8 - Only a limited amount of data could be collected at this house because a thunderstorm
occurred that resulted in a power failure while the occupants were gone on the weekend prior to cleaning.
Although the average concentration was lower after cleaning, the peak concentration was high on the last day
of the study. The impact of HAC system cleaning on particle concentrations at this house can not be
determined.
80
-------
In addition to the data for particles >0.5 jim, data were collected for the >5.0 p.m fraction with the Climet,
Data were not available for all houses or all time periods. Time-series plots of the data for the 5.0 jjm size
fraction are included in Appendix E of this report. Figures 5-10 and 5-11 present examples of the data. At
House 4 (Fig. 5-10), the concentrations of particles on the day following cleaning were similar, or higher, to
the concentrations measured prior to cleaning and on the day of cleaning. The low concentrations on Sunday,
Monday, and Tuesday following cleaning reflect the fact that the homeowners and children left for vacation
and were not present in the home. Figure 5-11 shows the results at a home occupied throughout the period by
two adults and two children. There is no indication during the first two days following HAC system cleaning
that the concentrations of particles >5.0 (4m are substantially lower than prior to cleaning
A review of the changes in concentrations over the monitoring periods at the study houses suggests the
following:
* On the day of cleaning the particle concentrations were elevated in the home, most likely due to increased
activity by the duct cleaners and the research team. But soon after the air handler was returned to service, the
concentrations dropped rapidly. There was no indication that particle concentrations increased in the home
immediately following cleaning due to a "burst" of residual dust from the system.
• The continuous monitoring data show substantial temporal variability in indoor particle concentrations.
Changes in indoor concentrations at Houses 3 and 4 suggest that outdoor air particle concentrations had a
substantial impact on indoor air concentrations. Both the continuous air monitoring data and integrated mass
concentration data suggest that outdoor particle sources, indoor particle sources other than the HAC system,
and occupant activity may have such a high impact on indoor particle concentrations that the impact of
mechanical cleaning of the HAC system on indoor particle concentrations may not be detectable using these
monitoring and sampling methods. Assessment of the impact of HAC system cleaning on indoor air quality
parameters is further complicated by the normal temporal variability of indoor air contaminant
concentrations.
53.2.2 Measurement Results for the LAS-X
The LAS-X measures particle counts in sixteen channels from 0.1 jim to 7.5 jim diameter. Measurements
were made throughout the study period at each home. The means and standard deviations of concentrations
of particles in each of the 16 size fractions were calculated for the pre- and post-cleaning periods. The means
for each size fraction are depicted in Figures 5-12 (a, b, c, and d). The mean and standard deviations for all
periods at all houses are included in Appendix F to this report.
81
-------
600000
House 4
Cliaict >5.0 urn
400000
Post-cleaning
iOOOOG*
o
©
©
©
o
©
o
©
o
o
©
Sun Mon Tue Wed Thur Fri Sat Sun Mon Tuc Wed
Figure 5-10. Airborne particle concentrations in the >5.0 size fraction at House 4
82
-------
600000
House 7
Climet: >5.0 um
500000-
Clauiingdty
100000-
CM O
^
CM O
o
CM
O
CM
O
CM
O
o
CM
O
O
CM
«r*
Men Tue Wed Thur Fri Sat Sun Mon Tuc Wed
Figure 5-11. Airborne particle concentrations in the >5.0 um size fraction at House 7
83
-------
300000000
250000000"
200000000 -
150000000-
100000000
50000000-
LASX Aerosol Spectrometer
Average: Pre vs. Post Cleaning
0,1-1,0 um
pre post pre post pre post pre post
TH 1 2 3
House ID
¦ 0.10-0.12
¦ 0.12-0.15
O 0.15-0.20
0 0.20-0.25
¦ 0.25-0.35
¦ 0.35-0.45
¦ 0.45-0.60
B 0.60-0.75
¦ 0.75-1.0
pre
post
Figure 5-12a. Airborne particle concentrations measured with the LAS-X
84
-------
300000000
250000000
200000000
150000000
100000000
50000000
0 *
LASX Aerosol Spectrometer
Average: Pre vs. Post Cleaning
01-10
.riBTfabBa.ii.
¦ 0.10-0.12
¦ 0.12-0.15
~ 0.1S-0.20
B 0.20-0.25
¦ 0.25-0.35
¦ 0.35-0.45
¦ 0.45-0.60
B 0.60-0.75
¦ 0.75-1.0
pre post pre pest pre post
5 6 7
pre
post
House ID
Figure 5-12b. Airborne particle concentrations measured with the LAS-X
85
-------
7000001
¦ 1.0-1.5 j
¦ 1.5-2.0 |
S 2.0-3.0 1
LASX Aerosol Scctrometcr
AvBCflgfci PfB VS. Post
1.0->7.5 urn
600000
¦ 4.5-6.0
¦ 6.0-7.5
¦ >7.5
500000
¦i
8. 300000
3
200000
100000
post
i
A
post
post
post
post
pre
pre
pre
pre
pre
TH 1 2 3 4
House ID
Figure 5-12c. Airborne particle concentrations measured with the LAS-X
86
-------
700000
600000
500000
¦I 400000
m
£
"o
« 300000
200000
100000
0
LASX Aerosol Spectrometer " 1520
.Average: Pre vs. Post Cleaning D 20_3a
1.0 ->7.5 ym 03.0-4.5
¦ 4.5-6.0.
B 6,0-7.5
¦ >7.5
House ID
Figure 5-12d. Airborne particle concentrations measured with the LAS-X
87
-------
For particles in the size ranges from 0.1 to 1.0 pm diameter, there was no clear trend in the
differences in the mean concentrations between the pre- and post-cleaning periods. Post-cleaning
concentrations were generally lower at the Test House and House 1. But for the other houses, the
concentrations were similar or higher. For the large size fractions (1.0 to 7,5 pm), post-cleaning
concentrations were lower at Houses 1,2, and 6. At the other bouses they were similar or higher. The ratio
of the mean concentrations in the post-cleaning period divided by the pre-cleaning mean concentrations are
presented in Figure 5-13 (a and b). It should be noted that the ratios were not available for House 7.
Post/pre-cleaning ratios were not included in the figure for the EPA IAQ Test House because the house is un-
occupied and the changes in particle concentrations may not be the same as at the occupied field study homes.
For the particle size fractions less than 0.60 pm, the post/pre-cleaning ratio was generally above 1.0, except
at House I. Houses 4 and 5 generally had the highest ratio in these size categories. House 5 had consistently
higher ratios. The differences between the other houses are probably not significant because the post/pre-
cleaning ratios are based on the mean concentration during the period and particle concentrations were highly
variable as indicated in the table included in Appendix F. In the particle size fractions from 0.60 to 1.5 pm,
House 5 continues to stand out as the house with the highest ratio. For the large size fractions, the ratio
continues to be higher for House 5 than for most of the other houses. This is not inconsistent with the activity
in the house during the study. Due to a family emergency, the occupants left the home on the day that the
instrumentation was set-up and there were no occupants in the home during almost all of the pre-cleaning
period; they returned on the evening prior to HAC system cleaning. However, the two adults and two
children did occupy the home during the entire post-cleaning period. The dramatic differences in activity in
the home between the pre- and post-cleaning periods apparently had a significant impact on the
concentrations of particles in the home and the post/pre-cleaning ratio. The data from this home provide
further indication that occupant activity and other sources in the home mask any changes in airborne particle
concentrations that may result from HAC system cleaning.
The other house with high post/pre-cleaning ratios is House 8. The differences between this house
and the other houses is particularly dramatic for the size fractions greater than 1.0 pm. This house had the
highest levels of dust in the ducts. At this house the occupants were gone on the Sunday and Monday prior to
cleaning, but were in the home all of the rest of the week. This appears to be another case where the activity
of the occupants is the strongest impact parameter. It is not clear why the post/pre-cleaning ratios are so high
for the 1.0 to 6.0 pm size fractions.
Examples of LA S -X measurement results are presented in Figures 5-14,5-15, and 5-16.
88
-------
LAS-X Aerosol Spectrometer
£ 2.00
0.1-0.75 urn
o o
Size fraction (urn)
Figure 5-13a Mean particle concentration ratios measured with the LAS-X for eight houses
89
-------
LAS-X Aerosol Spectrometer
0.75 - >7.5 um
¦ 6
0. 3,00
Size Fraction (um)
Figure 5-13b. Mean particle concentration ratios measured with the LAS-X for eight houses
90
-------
250000000
200000000
J 150000000
o5
«
13
g, 100000000
House 1
LAS-X Spectrometer
0.1-0.75 um
50000000'/
Cleaning day
1,10-0.12
>12-0.15
1.15-0.20
1.20-0.25
.25-0.35
1.35-0.45
1,45-0.60
1.60-0.75
Post-Cleaning
Pre-CIeaning
Sat
Sun
Mon
Tues
Wed
Thur Fri
450000
400000
350000
300000
PH
£
250000
*3
*f 200000
a
Cu
150000
100000
50000
0
7£ um
Cleaning day
0.75-1.0
1.0-1.5
1.5-2.0
2.0-3.0
3.0-4.5
4,5-6.0
6.0-7.5
>7,5
Post-cleaning
eaning
\ J
y,sruirf
Figure 5-14, LAS-X aerosol spectrometer measurement results at House 1
91
-------
100000000
90000000
80000000•
70000000•
60000000 -
50000000¦
40000000•
30000000 -
20000000 *
10000000 -
0
Pre-
cleaning |
House 5
LAS-X Spectrometer
0.1-0.75 urn
0.10-0.12
0.12-0.15
0.15-0.20
0.20-0.25
0.25-0.35
0.35-0.45
0,45-0.60
0,60-0.75
Post-cleaning
h
'Ai.
Thur
2000000-
1800000"
1600000-
1400000-
% 1200000-
•ft
¦S 1000000-
tJ
S. 800000-
Cleaning day
1 i 1
Pre- I
cleaning |
House 5
LAS-X Spectrometer
0.75- >7.5 urn
Post-cleaning
600000
400000
200000
¦ 0.60-0.75
0.75-1.0
¦ 1.0-1.5
1.5-2.0
2.0-3.0
3.0-4.5
4.5-6.0
6.0-7.5
>7.5
vD
I pyifir i
so o
Mon
Tue
Wed
Thur
Fri
Sat
Sun
Figure 5-15. LAS-X aerosol spectrometer measurement results at House 5
92
-------
250000000
200000000
£ 150000000
u
'€
«
n. 100000000
50000000
0.10-0.12
0.12-0.15
0.15-0.20
0.20-0.25
0,25-0.35
0.35-0.45
0.45-0.60
0.60-0.75
House 8
LAS-X Spectrometer
0.1-0.75um
Cleaning day
Post-cleaning
Pre-cleaning
1200000
1000000
800000
E
v 600000
400000
i
O.
House 8
LAS-X Spectrometer
0.75 - >7.5 urn
Pre-cleaning
200000
Cleanjng dqy
© e* ©
(Ml
Sat Sun
C4 o
Mon
0.75-1.0
1.0-1.5
1.5-2.0
2.0-3.0
3.0-4.5
4.5-6.0
6.0-7
>7.5
Post-cleaning
Tues
Wed
Thur
f v /»x !
'|T • **n ijt
Fri
Figure 5-16. LAS-X aerosol spectrometer measurement results at House 8
93
-------
5.5.3 Concentrations of Airborne Fibers in the Study Homes
Concentrations of airborne fibers were collected indoors and outdoors at each home using an integrated
sampling method Samples were collected for sequential 24-hr periods on two days prior to, and two days
following, HAC system cleaning. The results are presented in Table 5-15. The concentrations of airborne
fibers were low at all of the study homes in both pre- and post-cleaning samples. Fibers were rarely detected
in outdoor samples and with one exception (House 4, post-cleaning), the concentrations were near the
detection limit. The indoor concentrations ranged from less than 0.001 fiber/cm3, the minimum detection
limit, to 0.007 fibers/cm5 in two pre-cleaning samples at the Test House. Fibers were detected in one or more
samples at all homes, regardless of whether there were any pets in the home. This was not surprising because
all homes contain fibers due to the presence of furnishings and carpets. There was no relationship between
the presence of pets and the number of samples in which fibers were detected or the concentrations of fibers
in the samples. The concentrations of fibers measured at the study homes were too low and too variable to
draw any conclusions about the impact of HAC system cleaning on airborne fiber concentrations.
Airborne fiber concentrations were also measured with a "real-time" optical monitor, the MIE Fibrous
Aerosol Monitor, at four of the homes. The results are also presented in Table 5-15. Plots of the
concentrations at two houses are depicted in Figures 5-17 (House 6) and 5-18 (House 8). The mean fiber
concentrations measured with the FAM-1 after HAC system cleaning were lower at the LA.Q Test House, but
the standard deviation was large and there was a limited data set due to problems with the instrument at the
Test House. At House 6, the mean concentration in the post-cleaning period was higher because
concentrations of fibers were high on the last two days of the study from Saturday evening to Sunday
afternoon. The source of the fibers was not determined. The high concentrations at House 8 during the pre-
cleaning period may be related to the presence of a long-haired cat in the home. The home also had the
highest levels of fibers in the ducts based on visual observation. The concentrations were substantially lower
after HAC system cleaning. The concentrations of fibers measured with the FAM-1 in the pre-cleaning
period were substantially higher than those measured with the integrated sampling method. The samples
were collected in the same room as the continuous monitor. The reason for the discrepancy between the
results with the two measurement methods is not known.
One sample from the pre-cleaning set and one sample from the post-cleaning set at each study home were
analyzed by SEM to characterize the types of particles and fibers in the samples. The primary purpose of the
analysis was to identify the types of fibers in the air samples. However, because fiber concentrations were
low, there were few fibers to identify. The results are included in Appendix G and summarized below.
94
-------
Table 5-15 Airborne Fiber Concentrations in the Study Homes
fibers/cm3
Pre-Cleaning
Post-Cleaning
House
Location
Sample 1'
Sample 2
FAM-lb
Sample 1
Sample 2
FAM-1
TH
Outdoor
ND*
ND
0.002
ND
Primary
0.007
0.002
0.0130
0,001
ND
0.0020
Secondary
0.007
ND
ND
0.003
1
Outdoor
ND
ND
ND
0.001
Primary
0.004
SEMd
SEM
e
Secondary
0,005
0.001
0,006
0.003
2
Outdoor
ND
ND
ND
ND
Primary
0.003
SEM
SEM
j
Secondary
0.003
0.003
0.008
0.003
3
Outdoor
ND
ND
ND
ND
Primary
ND
SEM
SEM
0.001
Secondary'
ND
0.001
0.001
0.001
4
Outdoor
ND
ND
ND
0.005
Primary
0.003
SEM
SEM
0.002
0,0035
Secondary
0.004
0.002
0.006
0.001
5
Outdoor
0.002
ND
ND
e
Primary
ND
SEM
SEM
0.004
Secondary
ND
0.008
ND
0,003
6
Outdoor
ND
ND
ND
ND
Primary
0.001
SEM
0.0007
SEM
ND
0.0081
Secondary
0.002
0.002
0.003
0.001
Duplicate
-
0.00 i
0.001
7
Outdoor
ND
ND
0.001
ND
Primary
0.003
SEM
SEM
0.002
Secondary
0.003
0.002
0.002
0,001
8
Outdoor
0.001
0.001
0.058
ND
ND
0.0010
Primary
0.001
SEM
SEM
ND
Secondary
ND
0.001
0.001
0.002
* Two 24-hr integrated samples collected pre- and post-cleaning
b Mean concentration measured during the period with the FAM-1; monitored at one house each week
c ND: Concentration less than minimum detection limit of 0.001 fibers/cm3
d One sample analyzed by scanning electron microscopy, but fibers not quantified
* Sampling pump failed
f No sample collected
* Data logger problem; data lost
95
-------
0.06 -
0.05
0.04
0.03
0.02 -
O.OI
Pre-cleaning
»Ai i i iaiA a o A-
h frh
Cleaning day
Post-cleaning
House 6
FAM-1
As h N i "O >->i
Fri
Sat
Sun
Mon
Tue Wed
Thur Fri
Sat
Sun
Mon
Figure 5-17. FAM-1 fiber measurement results at House 6
96
-------
Cleaning day
House 8
FAM-I
Pre-c leaning
Post-cleaning
Fri
Sat
Sun
Mon
Tue
-AA ^
Wed
Thur
Fri
A
Sat
Figure 5-18, FAM-1 fiber measurement results at House 8
97
-------
5.5.3.1 Test House SEM Results
Similar particles and fibers were observed in the pre- and post-cleaning samples. The samples contained
the following types of particles and fibers:
• SiIicon(Si)/aluminum (Al)-rich particles (clay minerals) - major contribution
• Copper (Cu)-rieh particles - moderate contribution
• Si-rich particles (quartz) - minor contribution
• Calcium (Ca)/sulfur (S)-rich particles - minor contribution
• Iron (Fe)-rich particles - minor contribution
• Cellulose fibers - minor contribution
• Fibrous glass - minor contribution
5.5.3.2 House 1 SEM Results
Particles observed in the pre-cleaning sample included the following:
• Carbon (C)-rich particles (Combustion material) - 85% of particles
• SiIicon(Si)/aluminum (Al)-rich particles (clay minerals) -10% of particles
• Miscellaneous (Earth crustal materials) - 5% of particles
The % of the sample in these categories are estimates. Fibers were not observed in the sample.
In the post-cleaning sample, the particles were 100% carbon-rich particles
5.5,33 House 2 SEM Results
Particles observed in the pre-cleaning sample were reported as 100% carbon rich particles (carbonaceous
fragments). In the post-cleaning sample, 95% of the particles were carbon-rich and 5% were miscellaneous
(earth crustal materials). No fibers were observed.
5.5.3.4 House 3 SEM Results
The laboratory reported that the pre-cleaning sample contained primarily carbonaceous particles with a
minor amount of earth crustal particles (Si/Al-rich and Si-rich particles). The post-cleaning sample consisted
mainly of C-rich particles that were flakes. The sample also contained pollen, mold, earth crustal materials,
and feldspar.
98
-------
5.5,3 J House 4 SEM Results
The laboratory reported that the pre-clcaning sample contained primarily carbon-rich particles that were
predominantly flakes with a morphology similar to that of skin. They also reported cellulose fibers, earth
crustal materials, and carbon spheres that may have been mold. The post-cleaning sample had the same C-
rich flakes plus Si/Al-rich, Si-rich, and Ca-rich particles. Pollen and molds were not observed in the post-
cleaning sample.
5.5.3.6 House 5 SEM Results
The laboratory reported that the pre-cleaning sample contained primarily carbon-rich particles that were
predominantly skin flakes. Ca/S particles that were likely gypsum were identified in the sample. They also
reported cellulose fibers, wood, salt, and earth crustal materials. The post-cleaning sample had similar
particles plus pollen.
5.5.3.7 House 6 SEM Results
The laboratory reported that the pre-cleaning sample contained primarily carbon-rich particles that were
dominantly skin flakes. The sample also contained Ca/S particles that were likely gypsum, cellulose fibers,
earth crustal materials and pollen. The post-cleaning sample had similar particles and fibers.
5.5.3 J House 7 SEM Results
The laboratory reported that the majority of particles in the pre-cleaning sample were skin flakes/animal
dander. A minor amount of cellulose material was reported. They also reported various earth crustal
materials, pollen, and salt. The post-cleaning sample contained moderate amounts of skin flakes and earth
crustal materials plus cellulose materials, pollen, and other particles.
5.5.3.9 House 8 SEM Results
Hie laboratory reported that the majority of particles in the pre-cleaning sample were skin flakes/animal
dander. A minor amount of cellulose material was reported. They also reported various earth crustal
materials, fly ash, pollen, and salt. The post-cleaning sample contained moderate amounts of Si/Mg-rich
flakes that were probably talc. The sample also included skin flakes and earth crustal materials plus pollen,
and other particles. No fibers were observed in samples from this house even though there was a long-hair
cat, there were heavy accumulations of fibers in the ductwork, and the fiber concentrations measured with the
FAM-1 were the highest in the study.
99
-------
The results from the SEM analyses suggest that the airborne particles are typical of indoor air samples,
consisting of earth crustal materials, carbonaceous particles, pollens, molds, skin flakes, some fibers, and
particles from building products (gypsum) and consumer products (talc). The reader is encouraged to review
the complete results included as Appendix D, which also includes micrographs of selected particles,
5.5.4 Fungi Air Samples
The results of the bioaerosol sampling for fungi before and after cleaning at all nine houses are found in
Table 5-16. The goal of the bioaerosol sampling was to collect a snapshot in time both pre- and post-
cleaning of the airborne fungal levels. Bioaerosol sampling provides short-term samples and over the course
of time the levels in a building may vary substantially. Therefore, the conclusions that can be drawn are
limited.
The results of the two sampler measurements either from the rooms or die supply have been averaged and
the means are shown in the Table 5-16. As discussed previously, in the houses where the secondary supply
was located in the ceiling, a second room sample was collected in its place. This includes houses 3,4, and 5.
The levels of fungal bioaerosols in the supply samples and room samples were essentially the same with two
exceptions, in both the Test House and House 5, the levels of airborne fungi were more than three times
higher in the room than in the duct. While all of the numbers in House 5 are very tow and probably not a
concern, in the Test House the room had 300 cfu/m3 compared to 113 cfu/m3 in the duels. The full
significance of this result cannot be evaluated with so few samples, but it is interesting to note. Also of
interest is the level of fungi in House 2, The numbers of fungi isolated both in the supply ducts and in the
room are considerably higher than those in the other houses. The high levels can be attributed to a burst of
Penicillium spp. in the first 20 minutes of sampling. Approximately 90% of the of the organisms on the
three plates were Penicillium spp, and 90% of those occurred in the first 20 minutes of sampling. In other
words, 900 out of 1000 Penicillium spp on the plates were collected in the first 20 minutes. If those 900 are
subtracted, the fungal aerosol levels drop to 130 cfu/m3. This level in similar to the levels measured at the
other houses.
100
-------
Table 5-16. Fungal Air Sample Results
Cfu/m3
Supply Duct8
Room
House
Pre-Cleaning
Post-Cleaning
Pre-Cleaning
Post-Cleaning
TH
113
93
400
214
1
146
91
146
113
2
646
200
663
117
3
107
100
168
93
4
300
300
159
270
5
14
2
51
80
6
68
58
90
93
7
49
34
128
70
8
74
84
78
70
* Mean of measurements in supply ducts serving the primary and secondary sampling locations (rooms),
except at houses 3,4, and 5, where supply duct measurements were made only in the primary room.
Mechanical cleaning of the HAG system without the use of chemical biocides die not appear to impact
fungal bioaerosol concentrations. A comparison of fungal bioaerosol levels demonstrated no notable
difference between the numbers of fungi collected during pre-cleaning and those collected post-cleaning,
except for House 2. The decrease from 650 cfu/m3 to 200 cfu/m3 in the supply and 170 cfu/m3 in the room at
House 2 would probably be considered substantial. However, as discussed previously the high levels on all
three samples can be attributed to a single burst in the first 20 minutes of sampling. When the organisms
responsible for the burst are removed from the calculation, the fungal cfu levels were 130 cfu/m3, a value
lower than either the supply or the room post-cleaning levels. The significance or source of that burst cannot
be determined with the limited sampling performed in this study.
5.5.5 Comparison of IAQ Measurement Results With Duct Dust Levels
One of the questions routinely raised is when should an air conveyance system be cleaned. It was beyond the
scope of this study to address that issue in a quantitative manner. However, one factor that might be considered in
making a decision regarding HAC system cleaning would be the level of dust in the system This could be a
critical parameter if there was a relationship between duct dust levels and the indoor air quality parameters such as
airborne particle and fiber concentrations. This study facilitated a limited assessment of the relationship of duct
dust levels and airborne particle concentrations. Results of the duct dust measurements and airborne particle
concentrations during the pre-cleaning period are summarized in Table 5-17.
101
-------
Table 5-17. Comparison of Duct Dust Levels and Airborne Particle Concentrations Prior to HAC System
Cleaning
Duct Dust (g/m2)
Airborne Particle Mass (pg/m3)
Airborne
Particles
House
Supply
Return
PM,0"
pm7<»
X 106/m3a
TH
2.33
_b
11.1
7.5
6.97
1
8.62
19.83
10.7
6.5
5.6
2
3.37
24.13
15.2
11.8
7.21
3
1.91
7.80
17.7
16.5
16.01
4
1.48
7.89
15.6
11.8
10.98
5
2.28
11.34
10.0
5.7
3.52
6
2.30
5.26
10.3
6.5
5.06
7
3.34
12.91
14.3
11.7
8.07
8
26.03
35.11
10.9
11.3
20.15
a Mean concentrations for the period prior to HAC system cleaning
b No measurements in the return
Mean dust levels ranged from 1,5 to 26 g/m2 in the supply ducts and from 5,2 to 35 g/m2 in the return.
Mean PM2 5 and PM19 concentrations in the pre-cleaning period ranged from only 5.7 to 17.7 ng/m3 and do
not appear to be related to the dust levels in the ducts. For the mean airborne particle concentrations in the
>0.5 jim fraction there does not appear to be a strong relationship with duct dust levels, although the highest
concentration of particles was measured in the house with the highest duct dust levels, House 8. Although the
data set is very limited, a regression analysis for the eight field study homes gave a correlation coefficient (r2)
of 0.644 for airborne particle concentrations (particles X lOVm3) versus duct dust levels in the return ducts.
Examination of the data for bacteria and fungi in the surface samples (Tables 5-6 and 5-7) fail to show
any relationship between levels of the microbials and the duct dust levels. The highest bacteria levels were
measured at Houses 4,5, and 1, but these houses did not have the highest duct dust levels. Fungi levels in
surface samples were highest at Houses 1 and 4 in the supply and House 3 in the return. But these are not the
houses with the highest duct dust levels. The fungi levels were relatively low at House 8, the house with the
highest duct dust levels.
No statements can be made about the relationship of airborne fiber concentrations and duct dust levels,
Airborne fiber concentrations were low and the fiber content of the duct dust samples was not determined.
102
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5.6 Heating and Cooling System Measurement Results
Measurements were made of a number of parameters related to the heating and cooling system at each
study home prior to, and following, HAC system cleaning in an attempt to determine the impact of the HAC
system cleaning. The parameters measured included air flow rates, static pressures in the supply and return
ducts, differential pressures, coolant line temperatures, and air handler blower current Additionally,
temperature and relative humidity were measured in the supply and return ducts and system operating
durations were measured. The intent of the measurements was to identify trends and indications of improved
HAC system performance. It was determined during development of the study design, that quantitative
determination of changes in overall system efficiency would be difficult within the scope of this study.
Results of the measurements are reported below and estimates of the change in heat removal by the cooling
coil are provided for two homes that had large changes in air flow rates.
5,6.1 System Air Flow Rates
Air flow rates were measured with a vane anemometer at each supply register and each return air grille in
the homes. Multiple measurements were made on each diffuser and grill to obtain accurate flows across the
surface. Measurements were made on two days prior to cleaning and on two days following cleaning.
The supply and return air flow rates are summarized in Table 5-18. The volumetric air flow from the
supply registers and diffusers was higher at all houses except House 2. Hie change in flow ranged from -3.7
to 17.0%. Although the number of measurements was too small to make a statistical estimate of the
significance of the differences between pre- and post-cleaning measurements, the standard deviation shows
that the differences are not likely to be significant for changes of less than 10%. Air flows in the supply did
increase by over 10% at Houses 1,4,5, and 8.
Return air flows increased at six of the nine study homes. Based on the standard deviation, the change is
expected to be significant only at Houses 5 and 6, which had increases of 37.6 and 14.1 %.
Although the data are not conclusive due to the small sample size and the limited number of
measurements, they do suggest that HAC system cleaning increased air flows to some extent.
One of the limitations of the data collected in this study was that the measurements were performed at the
supply registers and diffusers and at the return air grilles in the house. This approach was taken because it
was recognized that measurements of air flow rates in the supply ducts would be difficult for residential
systems. The supply ducts in the study homes typically consisted of two branch ducts off the air handling
unit supply plenum. Take-offs for the branch (feeder) ducts to the roams were often located very
103
-------
Table 5-18, Supply and Return Air Flow Rates
House
m3/hr
Supply
Return
Pre-
Post-
% Change*
Pre-
Post-
% Change8
TH
Avgb
1883
1987
+5.5
2084
2109
+1.2
SDb
30
26
14
26
1
Avg
1304
1449
+11.1
2041
1971
-3.4
SD
6
53
50
46
2
Avg
1837
1769
-3.7
1791
1685
-5.9
SD
46
57
42
75
'3
Avg
1923
2108
+9.6
2322
2394
+3.1
SD
1
241
139
15
4
Avg
1734
1943
+12.0
2301
2440
+6.0
SD
3
94
213
57 •
5
Avg
1072
1415
+32
1025
1410
+37.6
SD
30
34
28
25
6
Avg
1541
1606
+4.2
1310
1495
+14.1
SD
187
37
62
39
7
Avg
2022
2181
+7.9
1987
1966
-1.1
SD
66
100
25
38
8
Avg
1450
1697
+17.0
1559
1692
+8.5
SD
11
80
198
177
* % Change = (Post-cleaning average - pre-cleaning average)/pre-cleaning average X 100
b Average and Standard Deviation for two pre-eleaning and two post-cleaning measurements
104
-------
close to the supply plenum which would have made it difficult to make accurate measurements of air flow
rates by traverses of the ducts with pitot tubes or hot-wire anemometers. Measurements of air flow rates at
the first home of the study, the EPA IAQ Test House (Table 5-18), showed that measurements of air flow
rates at supply registers and the return grille could be performed with good precision as indicated by the low
standard deviation and acceptable accuracy as demonstrated by the good mass balance between the supply
and return. However, as shown in the table, the measurements were not as good at other houses, as indicated
by the large standard deviation for some homes and the poor mass balance in some cases. The reason for the
large standard deviations at some homes is not known. The poor mass balance is most likely attributable to
air leakage in either the supply or return air ductwork. The leakage can not be accounted for in these
measurements. It should also be noted that some of the increase in the supply air flow may have been
attributed to remediation of minor deficiencies in the ductwork at some houses. For example, at House 8, a
floor boot for the kitchen supply register was loose and re-attached on the day of HAC system cleaning. At
House 7, a branch duct had fallen off the main supply trunk and was taped on to the duct, resulting in
substantial leakage. After cleaning, the amount of leakage was reduced by a better repair of the problem.
Because the return air flows were measured at the return air grilles in the houses, the measurement results
do not account for duct leakage, which was probably significant for some of these systems. As a result, the
air flow measurement results from the study may not be an accurate measurement of the air flow through the
air handler. To obtain that measurement value, air flow rates should have been measured by a traverse of the
return air duct near the AHU. In most cases, there was sufficient length of straight return duct such that a
measurement location could have been identified that had reasonably well-established flow. In future testing
of this type, this measurement should be made in addition to the measurements at the return air grilles.
5.6,2 Measurements of Static and Differential Pressures
Static pressures were measured in the supply and return ducts on two days prior and two days following
HAC system cleaning. Differential pressure across the coil was measured continuously and data recorded
with the IAQDS. Results of the measurements are presented in Table 5-19. The static pressure in the supply
ducts increased at some houses, but decreased at others; there was no clear trend in the changes. The pre-
clcaning static pressure in the supply duct at House 5 was substantially lower than the post-cleaning
measurement because of two large leaks in the supply side of the system. An access panel on the AHU
supply plenum was loose and there was a major leak where the supply trunk was connected to the AHU
supply plenum. The access panel was fixed and, although the leakage at the supply trunk was not completely
corrected, the amount of leakage was reduced after HAC system cleaning.
105
-------
Table 5-19. Static and Differential Pressure Measurements
Supply-Static Pressure
(inches of H,0)
Return-Static Pressure
(inches ofH,0)
Differential Pressure (inches
offtO)
House
Pre-
Post-
%
Change
Pre-
Post-
%
Change
Pre-
Post-
%
Change
TH
0.130
0.105
-19.2
-0.380
-0.370
-2.6
0.510
0.520
2.0
1
0.092
JBt
-
-0.220
J*
-
0.311
0.311
0
2
0.057
Jl
-
-0.133
¦
-
0.189
0.145
-23.3
3
0.289
0.282
-2.4
-0.476
-0.587
23.3
0.772
0.866
12.2
4
0.416
0.385
-7.5
-0.380
-0.508
33.7
0.200
0.200
0.0
5
0.055b
0.129
134.5
-0.129
-0.203
57.4
0.200
.270
35.0
6
0.092
0.094
1.6
-0.169
-0.219
29.6
0.290
0.314
8.3
7
0.044
0.050
13.6
-0.168
-0.190
13.1
0,226
0.236
4.4
8
0.125
0.096
-23.2
-0.145
-0.159
9.7
0.274
0.259
-5,6
1 No measurement taken
b Static pressure was low due to high air leakage rates at a loose access panel aid a seam in the supply trunk
that had broken away from the AHU supply plenum
The static pressure increased in the return air duct at the six occupied field study homes where
measurements were made. Post-cleaning measurements were not made at the first two houses of the field
study due to technician error. The increased static pressure was consistent with increased air flows measured
in the returns at the six houses, except for House 7 where there was no apparent increase in air flows
measured at the return air grille in the house.
The differential pressure increased by 5% or more following HAC system cleaning at three houses, was
not substantially different at five houses, and decreased substantially at one house. The results are not easily
explained. The AHU at House 2 was less than one year old and there was only a light coating of dust on the
cooling coil. But, based on visual observation, the cooling coil at House 8 was excessively dirty, with
substantial blockage of the coil due to dirt and fibers. These two houses represented the extreme cases;
debris and dirt levels were reasonably similar for the cooling coils at the other seven houses.
106
-------
5.6.3 Air Handler Unit Blower Motor Current Readings
The AHU blower motor current was measured at five of the nine houses twice before and twice after HAC
system cleaning using a clamp-on meter. Measurements were not made at the first two houses due to
technician error. Measurements were not made at Houses 4 and 5 due to problems accessing the wiring
harness for the blower motor. Results for the measurements are presented in Table 5-20. With the exception
of the measurements at the Test House, the AHU blower motor current readings were higher following HAC
system cleaning. The increase would represent an increase in power to the blower motor which would be
expected if the air flow rate increased due to cleaning. The current readings provide an indication that HAC
system cleaning had a positive impact on the performance of the air conveyance system.
It would have also been useful in this study to have measured the current for the compressor. During
future testing to assess the impact of HAC system cleaning on system performance and energy use, it will be
useful to make more comprehensive measurements over longer time periods.
Table 5-20. Air Handler Blower Motor Current Measurement Results
House
Amps
Pre-Cleaning
Post-Cleaning
TH
4.0
4.0
1
a
a
2
a
a
3
5.7
5.9
4
a
a
5
a
a
6
5.5
5.7
7
7.1
7.3
8
4.3
4.6
* Measurements not performed due to access problems or configuration/routing of wiring harness
107
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5.6.4 Coolant Line Temperatures
Relative coolant temperatures were measured by attaching a solid state temperature sensor to the surface
of the coolant lines. The sensor was then wrapped with insulation. Results of the measurements are
presented in Table 5-21. The temperatures of the coolant lines at the inlet to the cooling coil were not
substantially different in the pre- and post-cleaning time periods if the large standard deviations are
considered. The temperatures of the coolant line at the outlet from the cooling coil were lower after HAC
system cleaning at six of the seven houses with complete data sets, but the differences between pre- and post-
cleaning periods were small except at House 3. Lower temperatures in the coolant line at the outlet of the
cooling coil would be indicative of increased heat transfer if the cooling coil was more efficient due to HAC
system cleaning. The results, therefore, provide an indication that HAC system cleaning may improve
cooling coil efficiency.
The measurement of temperatures on the surfaces of the coolant lines were useful only for assessing the
relative difference between pre- and post-cleaning periods. As can be seen in the table, some of the
temperatures measured on the coolant inlet line are higher than would be expected. Placement of the sensors
on the coolant lines was difficult and it was difficult to insulate the sensors properly. Although the
measurement was useful because it provided an indication that the coolant temperatures in the outlet from the
cooling coil were lower after HAC system cleaning, the measurement had little quantitative value. To be
useful, and to obtain the level of accuracy and precision needed for this parameter, the temperatures of the
refrigerant need to be measured in the transfer lines and the flow rate of the refrigerant should be measured.
This was not feasible in this field study, but could be done in the Pilot HAC system Test Facility or at the
EPA IAQ Test House.
5.6.5 Estimates of Changes in Cooling Coil Heat Transfer Efficiency
Temperature and relative humidity were measured in both the supply and return ducts at a location as
close as possible to the AHU where the air was expected to be well-mixed. The measurement results for
those parameters are not included in this report, but are available fa* the purposes of data interpretation and
further data analysis. As described previously, the study design did not include measurements that could be
used to quantitatively assess changes in overall system efficiency. However, the air flow data, AHU blower
motor current measurement data, and the supply aid return temperature and RH data were used to determine
the change in enthalpy across the cooling coil and to estimate die total heat removed by the cooling coils for
two of the study houses. Houses 5 and 6 were selected for this exercise because they had the largest change
in return air flows following cleaning. House 5 had a 38% increase in the return air flow and House 6 had a
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14% increase. To make the estimates, steady-state values for temperature and relative humidity and the
average air flows were plotted on a psychometric chart and the enthalpy values were determined. At House 5,
the estimated heat transfer for the cooling coil was 15,505 Btu/hr prior to HAC system cleaning and 17,720
Btu/hr following cleaning, which represents a 14% increase. At House 6, the post-cleaning estimate was
21,041 Btu/hr, a 23% increase over the pre-cleaning estimate of 17,046 Btu/hr,
Table 5-21. Coolant Line Temperature Measurements
House
Inlet'
Outlet
b I
Pre
Post
Pre
Post
TH
Mean
17.6
18.8
21.3
19.8
SD
0.3
0.2
2.8
1.7
1
Mean
11.5
7.1
28.6
25.7
SD
5.0
6.7
4.1
5.6
2
Mean
19.8
19.3
25.5
25.3
SD
1.5
1.3
2.7
2.2
3
Mean
10.8
9.25
32.7
23.5
SD
3.5
2.1
2.9
1.0
4
Mean
11.8
13.3
21.3
20.0
SD
4.7
3.8
2.9
2.4
5
Mean
c
C
C
SD
6
Mean
20.5
21.0
21.0
22.2
SD
1.4
0.5
0.9
0.4
7
Mean
19.4
18.3
24.1
23.6
SD
2.2
2.4
0.2
0.2
8
Mean
_d
7.4
j
21.3
SD
1.7
2.4
* Mean and standard deviation for entire pre-cleaning to 6:00 a,m, on day of cleaning
b Mean and standard deviation for period from 6:00 a.m. on the day following cleaning until end of
monitoring period
c Data lost due to instrument failure Data lost due to power failure
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Without knowing the amount of power consumed by the condensing unit, the overall improvement in
efficiency can not be calculated for the system. However, the increased rate of heat transfer would support an
increased overall system efficiency. The higher rate of heat removal would also shorten the cycle times of the
system, which would offset minor increases in power consumption by the fan and condensing unit.
5.7 Evaluation of Study Design, Field Protocol, and Test Methods
As described in previous sections, the study was designed as a pilot study to evaluate the effectiveness of
current HAC system cleaning methods, collect an initial data set on the impact of HAC system cleaning on
indoor air quality and system performance, evaluate methods and test protocols for assessing HAC system
cleaning effectiveness and its impact, and to collect information that could be used to develop and refine a
research strategy for further evaluation of HAC system cleaning in residential and non-residential dwellings.
The study methods and protocols successfully addressed those objectives. It was recognized early in the
study design stage that a nine-home pilot study would not provide sufficient data for statistical analyses or for
making definitive conclusions on the impact of HAC system cleaning. However, the assumption was that the
a population of nine homes would be sufficient to identify trends in pre-cleaning versus post-cleaning
samples of the measurement parameters. Analysis of the data does not indicate clear trends for the IAQ
measurement parameters, but the data for the HAC system performance parameters are encouraging because
they suggest that HAC system cleaning may improve system performance. The lack of conclusive results to
document changes in indoor air quality parameters due to HAC system cleaning, although disappointing,
should not be considered a negative result. On the contrary, the data collected in the study suggest that short-
term sampling and monitoring of particles, bioaerosols, and fibers are unlikely to be useful for determining
whether HAC system cleaning has an impact on either short-term or long-term indoor air quality parameters.
The study results suggest that a technical approach involving this type of monitoring will not be useful
because are there too many sources of particles indoors, particularly the occupants and the outdoor sources,
and that temporal variability of particle concentrations make it difficult to discern an effect of HAC system
cleaning on indoor air quality. New approaches need to be considered to evaluate the impact of HAC system
cleaning.
The methods far measurement of IAQ parameters used in the study generally worked well. The integrated
sampling method for PM2 5 and PMI0 is a well-documented method used extensively in indoor air quality
monitoring projects. The 20 L/min sampling rate of the method provides adequate mass over eight to 24
hour sampling periods for accurate and precise gravimetric measurements. No problems were encountered
with this method during the study.
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The measurements of particle concentrations with the Climet optical particle counters provided useful data
on temporal variations in particle concentrations. The instrument is limited by the fact that data can only be
output for one of the two size fractions for which data are collected. Because of the limited internal storage
capacity, it is necessary to make frequent visits to test sites to download the data if data are required for both
channels. In this study, data for the >0.5 size fraction were recorded with the Blue Earth data logger in
the IAQDS. However, because of the configuration of the interface between the Climet and the Blue Earth,
the full scale output of the Climet could not be recorded with the IAQDS. The interface needs to be evaluated
to determine how to resolve this problem for future field monitoring studies.
The LAS-X generally worked well during the study. There were some problems with the RS-232
interface and the direct data dump to the computer. These problems need to be resolved.
The integrated sampling method used for fibers is a well-documented NIOSH method. Fiber
concentrations were low during the study and the precision of the method could not be evaluated with the data
from the study. The MIE FAM-1 fiber monitor was particularly troublesome during this study. There were
problems with the data logger during the study. These problems need to be resolved before the instrument is
used in other monitoring programs. The performance of the instrument needs to be evaluated. Although the
instrument may be useful for pre- and post-cleaning comparisons, the performance of the instrument for
different types of fibers, different fiber lengths, and low fiber concentrations is not well-documented.
The methods used for collection of bioaerosols are frequently-used methods. No problems were
encountered with these methods. The surface sampling methods for microbiologicals also worked well.
The MVDS worked well for collection of dust samples from the ductwork when it was fitted with the
brush attachment. The collection efficiency of the prototype model was evaluated and found to be highly
efficient on non-porous surfaces for loose dust. The collection efficiency of the MVDS with the brush
attachment has not been documented for the type of dust that occurs in "real" ductwork. However, based on
visual observation, the sampler is highly efficient. Because the method is used primarily for comparison of
pre- and post-cleaning samples, quantitative measures of collection efficiency may not be required. The
MVDS does not collect dust efficiently from cooling coils based on visual observations during the study. A
new method needs to be developed if quantitative measurements of dust on cooling coils are required.
The methods used to measure HAC system parameters worked reasonably well during the study, but
should be improved if the measurements are required in future studies. The measurements of air flow rates
with the vane anemometer at supply registers, diffusers, and return air grilles worked well. Measurements at
the EPA IAQ Test House showed that the precision of the method can be quite good. Poorer precision at
some houses is likely due to highly non-uniform air flow at some registers and diffusers. Measurements of air
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flow rates at the supply registers and return air grilles should be supplemented with measurements of air flow
in the return duct near the AHU by a pitot tube traverse method. The latter measurement will provide a better
estimate of the "system" air flow through the AHU. Measurements at registers and grilles in the house do not
account for the leakage in the supply and return air ducts.
Measurements of static pressures and differential pressure are relatively straight forward and easy to
accomplish. The sensor used to measure differential pressure had a full-scale range of 0.5 inches of H20,
which was inadequate at House 3. Different sensors may be needed for some systems.
Current measurements are also relatively easy to perform. In this study, measurements were not made at
some homes because the wiring was inaccessible or in a wiring harness. Generally, the measurements can be
performed. It may have been useful to measure the current for the compressor. This measurement should be
considered in future studies.
Relative differences in coolant temperatures between pre- and post-cleaning periods were determined by
measuring the temperature on the outside surface of the coolant inlet and outlet lines. This method did not
work well. The temperature sensors were difficult to attach and difficult to insulate. The method may be
useful for obtaining "indications" of relative changes in large field studies. If this measurement parameter is
required, the method needs to be refined and a different type of sensor should be used that is easier to attach.
For accurate and precise measurements, the refrigerant temperature and pressure should be measured in the
refrigerant lines.
In future studies to assess the impact of HAC system cleaning on system performance and energy use,
more comprehensive measurements of HAC system parameters should be performed over longer time
periods. These measurements will require installation of meters and measurement devices into the system
and collection of data with data acquisition systems.
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6.0 QUALITY ASSURANCE/QUALITY CONTROL
Quality control and qualify assurance activities were implemented in the project according to guidelines in
the Work Assignment Quality Assurance Project Plan (QAPP) entitled, Quality Assurance Project Plan for
the Pilot Field Study to Evaluate the Effectiveness of Cleaning Air Conveyance Systems and the Impact on
Indoor Air Quality in Residences (Fortmann, 1996b) and the Field Microbiological Investigation of
Ventilation System Cleaning: Project Work/QA Plan (RTI, 1996).
Quality control samples, including blanks and duplicates, were analyzed as part of this study. In addition,
quality control procedures were included in the sampling and analysis phases of this study. During the initial
testing at the EPA Indoor Air Quality Test House, the Acurex Environmental Quality Assurance Officer
performed a systems audit. Based on the audit, some modifications were made to test protocols and methods
and corrective action was taken as appropriate.
To the extent possible, the methods used in this study were standardized methods or methods for which
performance has been well-documented. Some methods, such as the collection of dust from the surfaces of
ductwork were developed for this project. Data quality indicator goals for the project are listed in Table 6-1.
6.1 Quality Control Samples
Quality control samples consisted of blanks and duplicates.
6.1.1 Field Blanks
Field blanks for particles and fibers consisted of filters not used for sampling but handled in the same
manner as those used for field sampling. Filters were placed in petri dishes, earned to the field but not used,
returned to the laboratoiy, and conditioned at constant temperature and relative humidity in the EPA weighing
facility along with the field samples. The filters were weighed in batches with the field samples. For fibers,
die blanks were submitted to the laboratory blind and analyzed with the field samples. Blanks for microbial
samples consisted of cassettes and swabs carried to the field but not used.
Six filters were submitted to the laboratory as blanks for fiber analysis. The results reported for all six
filters were <0.001 fibers/cm3, the minimum detection limit for the method.
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Table 6-1. Data Quality Indicator Goals For Parameters Measured in the Project
Measurement Parameter
Bias (%)
Precision (%)
Completeness (%)
Duct dust - MVDS
45 - 125"
±25
>90
Duct dust - NADCA vacuum method
>75'
±20
>90
Microbial areal density - filter
80-120
±20
>90
Microbial areal density - swab
90-110
±20
>90
Bioaerosol measurement (cfu/m3)
80 -120
±20
>90
PM10 mass (pg/m3)
75 - 125b
±25
>90
PM2 5 mass (pg/m3)
75 -125b
±25
>90
Fine particle concentration (Climet)
C
±25d
>90
Fine particle concentration (LAS-X)
c
± 25
>90
Fiber concentration (integrated samples)
a
±45*
>90
Fiber concentration (FAM-1 monitor)
NDr
±25r
>90
Temperature
±1.0 C
± 1.0 »C
>90
Relative humidity
± 5% RH
± 5
>90
Differential pressure
±25
±25
>90
Air flow rate (volumetric)
±20b
±20b
>90
* Percent Recovery
b Based on EPA Large Building Studies QAPP
c Bias has not been determined for the instrument; measurement results were used to determine relative
differences pre- and post-cleaning
d Based on limited measurements in a pilot scale test facility at Research Triangle Institute
* NIOSH Method 7400 B counting rules; Method 7400 states that overall accuracy of the method has not
been determined. Precision DQI is as stated in Method 7400 for fiber counts
f Manufacturer does not specify accuracy; precision based on manufacturer's estimates for 0.1 fiber/cm5 and
100 min sampling time
Nine filters were submitted to the laboratory for gravimetric analysis. Tare weights and final weights were
determined for each filter. The measurements gave mass concentrations of 4,12,4,10,7,5,4,2, and 12 pg
per filter. The average for the nine blanks was 6.7 pg/filter, For a 24 hour sample at a concentration oflO
pg/m3, the mass on the filter would be 288 pg. The average error contributed by a blank value of 6,7
pg/filter for the two weighings (tare and final) would be approximately 2 percent
Field blanks for microbial sampling and analysis methods included SDA cassettes, TSA cassettes, and
swabs. For the six SDA cassettes, two samples had one colony count, but the other four had no counts. The
TSA field blanks included one sample with one background count and five samples with no colonies. On 16
swab field blanks, only one sample had detectable colonies (four); all other samples had no background
contamination.
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6,1.2 Method Precision and Bias
6.1.2.1 Method Precision
Duplicate samples of duct dust were collected with the MVDS at all houses to assess the precision of the
method. The results, presented previously in Table 5-4 are repeated here in Table 6-2,
Table 6-2. Results of Duplicate Duct Dust Measurements With The MVDS
g/m2
House
Location
Primary
Duplicate
Mean
S.D
%RSD
TH
Supply
0.80
1.09
0.94
0.20
22
1
Supply
10. BO
11.89
11.85
0.06
1
Supply
26.28
100.72
63.65
52.64
83
Return
0.24
0.25
0.25
0.007
3
2
Supply
2.22
2,73
2.48
0.36
15
Supply
0.18
0.16
0.17
0.01
1
3
Return
13.15
16.54
14.85
2.40
16
Supply
0.54
0.34
0,44
0,14
32
Supply
0.19
0.26
0.23
0.05
22
Return
0.42
0.37
0.40
0.04
9
4
Supply
1.27
1.47
1.37
0.14
10
Return
6.22
5.11
5.67
0.78
14
Duct Liner
1.62
1.55
1.59
0.05
3
Supply
0.34
0,12
0.23
0.16
80
5
Supply
2.62
2.52
2.57
0.07
3
Return
11.49
10.47
10.98
0.72
7
Supply
0.32
0.23
0.28
0.06
23
Return
1.97
0.59
1,28
0.98
76
6
Supply
2.00
2.03
2.02
0.2
1
Return
3.62
6.52
5.07
2.05
40
Return
0.18
0.23
0.21
.04
17
7
Supply
4,22
5.07
4.65
0.60
13
Return
9.03
11.66
10.35
1.86
18
Supply
0,44
0.80
0.62
0.25
41
8
Supply
36.07
45.98
41.03
7.01
17
Supply
1.13
0.63
0.88
0.35
40
Supply
0.80
0.65
0.73
0.11
15
Return
0.19
0.26
0.23
0.05
22
115
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The percent relative standard deviation for the duplicate dust samples ranged from 1 to 80%. Twenty-one
of the 28 duplicates met the data quality indicator goal of ± 25%. Five sets of duplicates with a %RSD
greater than 25% were post-cleaning samples with low dust mass concentrations. In spite of the fact that the
dust deposits were generally not uniformly distributed, the precision of the method was quite good.
Results for duplicate samples collected with the NADCA vacuum method were presented in Table 5-3.
The following summarizes the results:
Primary fg/m21 Duplicate (Wm2) %RSD
0.036 0.034 3.5
0.030 0.032 4.6
0.027 0.024 8.3
0.013 0.013 0
0.007 0.006 10.8
All of the duplicates met the data quality indicator goal of ± 20%.
Duplicates of each microbiological surface measurement were obtained by collecting swab and vacuum
samples on co-located sites except in the Test House where the swab method was not appropriate for the
porous fiberglass duct liner surface. All measurement results are included in Appendix D. The data from
each house were treated as replicates across all samples because the variability between sampling locations in
the ducts was similar to the variability between co-located measurements with the two sampling methods.
The results presented previously in Tables 5-6 and 5-7, therefore, are representative of the replicates. As
shown in these tables, four to eight locations were sampled in the supply ducts and two to six locations were
sampled in the return ducts at each house. For bacteria samples, the relative standard deviation ranged from
13 to 228% for samples collected at all of the locations at a house. For fungi samples, the relative standard
deviation ranged from 13 to 243%. Review of the data in Appendix D shows that the relative standard
deviation for the samples collected at the same location with the two methods are in a similar range. For most
sampling locations, the precision goal of ± 20% could not be met due to the non-uniform distribution of the
contaminants in the HAC system.
Duplicates for PM25 and PM10 were collected at the EPA IAQ Test House and at House 5. Samples were
collected side-by-side at the primary sampling location in the home. The results were as follows;
Hwse
Parameter
Primarv ffie/m3')
Duplicate
%RSD
TH
pm2.
7.4
7.3
1.0
TH
PM.o
9.8
9.1
5.2
5
PM25
6.6
4.7
23.4
5
PM)0
14.2
13.0
6.2
116
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The four duplicates met the data quality indicator goal for the method of ± 25%.
Duplicate fiber samples were collected at the Test House and House 6. At House 5, the concentrations in
both samples were 0.001 fibers/cm3, the minimum detection limit of the method. At the Test House, the
pump failed for the duplicate sample.
The precision of measurements with continuous monitors was not determined during this study due to
limitations of resources.. Data quality indieator(DQI) goals for these measurements were based on
manufacturer's specifications and historical data for the instruments. For temperature and relative humidity
sensors, the performance was checked at each house by comparison during setup with an aspirated
psychrometer. The sensors were used only if they met the DQI goals for bias. But sufficient instrumentation
was not available to co-locate continuous monitors to measure precision on a continuous basis.
6,1.2.2 Method Bias
Hie performance of the MVDS for collection of dust (particulate and fibrous materials) was evaluated in
the laboratory prior to the field study. Results of the methods evaluation are presented in Appendix A. The
collection efficiency of the MVDS with its specially designed nozzle was determined by applying known
quantities of particulate matter to galvanized steel sheets, then samples were collected from the surface, The
collection efficiency was determined to be 97.6 ± 1.8% for collection of newly-deposited dust from the sheet
metal surface. Following the initial evaluation in the laboratory, visual observations during tests to the RTI
Pilot Scale Test Facility (VanOsdell et al., 1997) indicated that the collection efficiency was not as goal for
particle deposits that had been conditioned by exposure to high relative humidity. As a result, the sampler
was modified to include a brush attachment to improve the collection efficiency. The collection efficiency
with the brush was not quantified prior to the field study. Additional testing will be performed to obtain
estimates of the collection efficiency of the sampler with the brush attachment. For the purposes of this
study, which were to compare the amount of particulate and fibrous material on the duct surfaces before and
after cleaning, quantitative estimates of method bias are not critical to interpretation of the data.
The NADCA method was used according to the procedures outlined in the NADCA Standard 1992-01
(NADCA, 1992). The bias of the method when used under field conditions was not determined in this study.
The bias of the integrated sampling method used to measure mass concentrations of PM2 5 and PM,0 was
not determined in this study due to resource limitations. The method has been accepted for use in the BASE
program (U.S. EPA, 1994) and the EPA Large Building Studies Program (Fortmann et al., 1994). Because
the data collected by the method was use for comparison of particle mass concentrations before and after
HAC system cleaning, not for the purpose of exposure assessment, quantitative estimates of the method bias
are not critical for the purposes of this study.
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Bias of the method used to collect microbiological contaminants from surfaces of the HAC system can not
be directly evaluated because there is not a standard reference duet surface material or a standard sampling
method for comparison. Measurements in this study were used to compare concentrations on surfaces before
and after HAC system cleaning. Assuming that the bias is relatively constant, data for this study can be used
for comparative purpose. The data have not been used to estimate exposure or risk.
Bias of the bioaerosol measurements with the Mattson-Garvin sampler were not determined during this
study. Such a determination was beyond the scope of this study. Jensen (1992) have shown that the
Mattson-Garvin bioaerosol sampler used in this study measured concentrations approximately 10 to 13%
below a reference sampler for two target organisms.
6.2 Method Performance
Method performance was documented by performing calibrations of continuous monitoring
instrumentation prior to the field study and by quality control procedures implemented during the study. All
Climet CI-4100 optical particle counters used in the study were sent to the manufacturer for calibration prior
to the study. Calibration certificates are on file. There was no method available to check performance of the
instruments during the field monitoring program. One of the two LAS-X Aerosol Spectrometers used in the
study was sent to the manufacturer for routine maintenance and calibration prior to the study. The
comparability of the other LAS-X used in the study was determined by collocating the instruments and
collecting monitoring data for a 16-hour test period. The average percent difference in the readings between
the two instruments during a 38 hour monitoring period were calculated as the average reading of the recently
calibrated monitor minus the average of the other monitor, divided by the average reading of the recently
calibrated monitor. The results were as follows:
Size Fraction
% Difference
Size Fraction
% Difference
0.1-0.12
63
1.0-1.5
9
0.12-0.15
5
1.5-2.0
-47
0.15-0.20
25
2.0-3.0
12
0.20 - 0.25
1
3.0-4.5
-26
0.25 - 0.35
110
4.5 - 6.0
-35
0.35 - 0.45
-6
6.0 - 7.5
-46
0.45 - 0.60
21
>7.5
-59
0.60 - 0.75
-54
0.75 -1.0
25
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With the exception of the 0.1-0.12,0.25-0.35,0.60-0.75, and >7.5 jim channels, the instruments were in
good agreement. Because the instrument was used primarily for comparison of pre-cleaning and post-
cleaning concentrations, the performance was considered acceptable. The instrument should be re-calibrated
prior to use in other studies. Temperature, relative humidity, carbon dioxide, and pressure sensors in the
IAQDS' were calibrated prior to the study. At the time of set-up at each house, the reasonableness of carbon
dioxide readings were assessed. Differential pressure readings with the IAQDS were compared to
measurements with a calibrated Air Data ADM-860. Indoor and outdoor temperature readings with the
IAQDS were compared to readings with an aspirated psychrometer.
Gravimetric measurements were performed at the controlled weighing facility located in the EPA Annex in
Research Triangle Park, NC. The balances were certified by the EPA during the twelve months prior to use
in this study. Weighings were performed according to standard operating procedures developed for the
EPA/ORD Large Building Study (Aeurex, 1994) and include daily QC check filters and calibrated class S
weights.
6.3 Data Completeness
The goal for data completeness was collection of greater than 90% of the planned samples. The data
completeness is summarized in Table 6-3. The completeness goal was met for all sample types collected by
integrated or grab sampling methods.
The goal for completeness of data collection with the continuous monitors was also >90 %. Data
completeness for continuous monitoring of particle concentrations with the Climet CI-410G was greater than
90% at all houses except House 8 where much of the pre-cleaning data were lost due to a power failure at the
house. Data were greater than 90% complete for measurements with the LAS-X at all houses except House
7, where the pre-cleaning data were lost due to a computer problem. Problems with the data logger for the
MIE FAM-1 fiber monitor occurred frequently; less than 90% of the planned data were collected. Data
collection for differential pressures, coolant temperatures, supply and return temperature and relative
humidity, ambient temperature and relative humidity indoors and outdoors were > 90% complete at all but
House 8, where the power failure occurred. Static pressure measurements were completed for 32 of the 36
planned measurement periods. Measurements of AHU blower motor current were completed for only 20 of
the 36 planned measurement periods. Measurements of supply and return air flow rates were completed for
all of the 36 planned measurement periods.
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Table 6-3, Summary of Data Completeness
Sample Type
Samples Collected/Number Planned
Field Samples
Duplicates
Blanks
Duct Dust - MVDS
121/81"
28/18
0/0b
Duct Dust - NADCA
12/10
5/5
0/0b
Duct Surface - Bacteria
130/72'
8/8
Duct Surface - Fungi
130/72'
_<5
8/8
PMj 5
104/108
2/2
3/3
PMI0
103/108
2/2
3/3
Bioaerosols
36/36
0/0
12/12
Fibers
105/108
2/2
6/6
* Number planned was minimum; actual number changed due to different types of ductwork and accessibility
b PM blanks and check filters served as weighing blanks for all gravimetric analyses
c Duplicates consisted of side-by-side samples collected with a swab method and a vacuum method, results of
which were reported as field samples
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7.0 REFERENCES
Acurex, 1994. QRD Large Building Study - Standard Operating Procedures. Acurex Environmental
Corporation, Prepared for the U.S. Environmental Protection Agency, Office of Research and
Development, Research Triangle Park, NC under Contract No. 68-D4-0015, October 1994.
Ahmad, I., Tansel, B., and Mitrani, J. 1994, Effectiveness of HVAC Sanitation Processes in Improving
Indoor Air Quality. Technical Publication No. 113, Florida International University, Miami, FL.
AFVC, 1993. Duct Cleaning - A Literature Survey, Air Infiltration Review, vol. 14, No. 4, Air Infiltration
and Ventilation Centre, Coventry, U.K., September 1993.
Fortmann, R., Clayton, R., Highsmith, V.R., and Nelson, C.J. 1994. The U.S. EPA/ORD Large Buildings
Study - Results of the Initial Survey of Randomly Selected GSA Buildings, in the Proceedings of the
1994 U.S. EPA/A&WMA International Symposium on Measurement of Toxic and Related Air
Pollutants. Durham, NC, Air and Waste Management Association, Pittsburgh, PA.
Fortmann, R., 1996a. Pilot Field Study to Evaluate the Effectiveness of Cleaning Air Conveyance Systems
and the Impact on Indoor Air Quality in Residences - Final Test Plan. Prepared for the U.S.
Environmental Protection Agency, Air Pollution Prevention and Control Division, Office of Research
and Development, Research Triangle Park, NC, under Contract No. 68-D4-0005, Work Assignment
No. 1-030, May 1996.
Fortmann, R., 1996b. Quality Assurance Project Plan for the Pilot Field Study to Evaluate the Effectiveness
of Cleaning Air Conveyance Systems and the Impact on Indoor Air Quality in Residences - Final Test
Plan. Prepared for the U.S. Environmental Protection Agency, Air Pollution Prevention and Control
Division, Office of Research and Development, Research Triangle Park, NC, under Contract No. 68-
D4-0005, Work Assignment No. 1-030, May 1996.
Fortmann, R.. 1996c. Standard Operating Procedure for Collection of Duct Dust Samples with the
Environmental Protection Aeencv/Acurex Environmental Dust Sampler fMVDS). Prepared for the
U.S. Environmental Protection Agency, Air Pollution Prevention and Control Division, Office of
Research and Development, Research Triangle Park, NC, under Contract No. 68-D4-0005, Work
Assignment No. 1-030, May 1996.
Fugler, D. and Auger, M. 1994. A First Look at the Effectiveness of Residential Duct Cleaning, Proceedings
of the 87th Annual Meeting and Exhibition. Air and Waste Management Association, Pittsburgh, PA.
121
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Girman, J.R., Womble, S.E., and Ronca, E.L. 1995. Developing Baseline Information on Buildings and
Indoor Air Quality (BASE "94): Part II - Environmental Pollutant Measurements and Occupant
Perceptions, Proceedings of the International Conference on Healthy Buildings in Mild Climate,
Healthy Buildings '95. September 1995, University of Milano, Milano, Italy.
Jensen, S., 1992. Evaluation of Eight Bioaerosol Samplers Challenged with Aerosols of Free Bacteria,
American Industrial Hygiene Association Journal. 53:660-667.
Morey, P.R. and Williams, C.M. 1991. Is Porous Insulation Inside a HVAC System Compatible With a
Healthy Building? Proceedings of the IAQ '90 Conference on Healthy Buildings, American Society
of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, GA.
NADCA, 1992. Mechanical Cleaning of Non-Porous Air Conveyance System Components. NADCA
Standard 1992-01, National Air Duet Cleaners Association, Washington, DC.
NADCA, 1995. Introduction to HVAC System Cleaning Services: A Guideline for Commercial Consumers.
National Air Duct Cleaners Association, Washington, DC,
NIOSH, 1994. Method 7400 - Asbestos and Other Fibers hv PCM. NIOSH Manual of Analytical Methods,
Fourth Edition, National Institute for Occupational Safety and Health, Cincinnati, OH.
O'Neil, M. and Kulp, R. 1997. Research Agenda on Duct Cleaning, Proceedings of the 2nd Biennial
Engineering Solutions to Indoor Air Duality Prohlems. July 1997, Research Triangle Park, NC. Air &
Waste Management Association. Pittsburgh, PA.
RTI, 1995, Air Conveyance System Cleaning Pilot System Development, Characterization, and
Operation: Project Work and QA Plan, Prepared for the U.S. Environmental Protection Agency, Air
Pollution Prevention and Control Division, Office of Research and Development, Research Triangle
Park, NC, under EPA Contract No. CR-822870.
RTI, 1996. Field Microbiological Investigation of Ventilation System Cleaning: Project Worh'QA Plan,
Prepared for the U.S. Environmental Protection Agency, Air Pollution Prevention and Control
Division, Office of Research and Development, Research Triangle Park, NC, under EPA Contract No.
CR-822870.
Environmental Protection Agency, Office of Air and Radiation, Washington, DC, and U.S.
Department of Health and Human Services, National Institute for Occupational Safety and Health,
Washington, DC. Available from the U.S. Government Printing Office, ISBN 0-16-035919-8.
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Buildings. Office of Research and Development and Office of Air and Radiation, U.S. Environmental
Protection Agency, Washington, DC, June 1, 1994.
VanOsdell, D., Foarde, K., and Fortmann, R., 1997. Phase I Pilot Air Conveyance System Design. Cleaning,
and Characterization. EPA-600/R-97-066 (NTIS PB97-189682). U.S. Environmental Protection
Agency, Research Triangle Park, NC.
Wallace, L, 1996. Indoor Particles : A Review. Journal of the Air & Waste Management Association
46:68-126.
123
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APPENDIX A
INITIAL EVALUATION OF METHODS FOR SAMPLING DUST FROM
HEATING, VENTILATING, AND AIR-CONDITIONING SYSTEM
(DUCT) COMPONENTS
INTERIM DATA SUMMARY REPORT
Prepared by
Roy Fortmann
Acurex Environmental Corporation
Research Triangle Park, NC 27709
Prepared for
Russell N. Kulp, Project Officer
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
Prepared under
EPA Contract No. 68-D4-0005
Work Assignment No. 1-042
Acurex Environmental Project No. 8842
A-1
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1.0 INTRODUCTION
The cleaning of heating, ventilating, and air-conditioning (HVAC) systems, also referred
to as air duct cleaning, involves the physical removal of particulate matter and debris from air
distribution systems and air handler components. There is currently little published research data
on the effectiveness of air duct cleaning or its impact on indoor air quality and energy use for
residential heating and cooling systems. A research program has been initiated by the U.S.
Environmental Protection Agency (EPA) National Risk Management Research Laboratory
(NRMRL) Air Pollution Prevention and Control Division (APPCD) to evaluate the effectiveness
of HVAC cleaning and its impact on indoor air quality (IAQ) in residential buildings.
To evaluate the effectiveness of ACS cleaning, measurements will be performed to
determine the mass of particulate matter in ducts and on other components of the ACS prior to,
and following, cleaning. The National Air Duct Cleaners Association (NADCA) has published a
Vacuum Test Method for documenting the effectiveness of cleaning galvanized ducts (NADCA
1992-01, Mechanical Cleaning of Non-Porous Air Conveyance System Components), but the
method was not developed to measure dust levels prior to cleaning. The method is also applicable
only to non-porous duct materials, Other methods are required for determining the effectiveness
of cleaning of other types of duct materials, including fiberglass insulated ducts, fiberboard, and
insulated flexible ducts.
The objective of the testing described in this report was to develop a method for collection
of dust (particulate and fibrous matter) from porous and non-porous surfaces. The method
needed to be applicable for collection of high levels of dust prior to HVAC cleaning and for
collection of low levels of residual dust on surfaces following HVAC cleaning. Acurex
Environmental, in support of the EPA research program, has performed testing to evaluate
methods that can be used to sample dust from surfaces of various non-porous and porous ducts
that are used in residential systems. The NADCA vacuum method was evaluated to determine if
it could be used for the proposed field study even though it had not been developed for collection
of high levels of dust or for collection from porous surfaces. Because it was not applicable for the
purposes of this research program, an alternative method was developed and evaluated. This is an
interim report that summarizes the results of the laboratory testing of the methods. Additional
evaluation of the methods was performed during testing in a pilot-scale residential-sized
ventilation system.
A - 2
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2.0 DESCRIPTION OF THE METHODS EVALUATED
The three methods selected for testing are described below,
2.1 NADCA Standard Method 1992-01
The NADCA Standard Method 1992-01 is described in the document entitled,
Mechanical Cleaning of Non-Porous Air Conveyance System Components. The hardware for the
method consists of a vacuum pump operated at 10 L/min, a filter cassette, and a template for
sampling. The 37-mm diameter plastic filter cassette is used as the nozzle. The area of the
nozzle, therefore is 10.75 cm2; at a flow rate of 10 L/min, the velocity at the face of the nozzle
during sampling would be 15 .5 cm/s, which is relatively low. The method is based on sampling a
100 cm2 area, as defined by a template, Mid gravimetric determination of the dust collected on
either matched weight filters or tared filters. According to the method, the weight of debris
collected by the NADCA Vacuum Test should not exceed 1.0 mg/100 cm2 after cleaning of a
non-porous duct.
2.2 Acurex/EPA Medium Volume Sampler
A medium volume vacuum method was developed for this project. The sampler consists
of the following components:
• Thomas Model 2107CA20A dual diaphragm vacuum pump with nominal free air
flow of 50 L/min,
• Gelman Model 2220 stainless steel 47 mm diameter in-line low pressure filter
holder,
• Whatman EPM 2000,47 mm, high-volume air sampling filters rated at 99.997%
retention for 0,3 |im DOP, and
• Nozzle developed by Acurex Environmental - stainless steel, 30 mm X 3 mm inlet
(0.9 cm2 face area of nozzle).
The prototype nozzle used in the tests described in this report was designed to optimize
collection efficiency by using a small inlet area, a small dead volume in the nozzle, and stainless
steel to reduce deposition of particles to the nozzle due to electrostatic forces, At 20 L/min, the
velocity through the nozzle under free flow conditions would be 370 cm/s. Data reported below
are for the final prototype nozzle, unless indicated otherwise.
2.3 High Volume Sampler
The high volume vacuum sampler with a cyclone for sample collection is the High Volume
Furniture Sampler manufactured by CS3, Inc.. The sampler has been used in a number of EPA
A - 3
-------
studies for collection of lead, polyaromatic hydrocarbons, pesticides, and other contaminants from
carpets and textile furnishings.
The sampler consists of a Dirt Devil Can Vac with a theoretical flow rate of 20 efm, a
cyclone for particle collection, a collection jar, flow controller, magnehelic gauge, associated
tubing, and nozzle. During evaluations with this system a number of nozzles were evaluated. For
sampling dust from flexible duct, a round, nominal 3-inch diameter, nozzle with a brush was used.
3.0 TEST PROCEDURES
Methods evaluations were performed by depositing known amounts of particulate matter
on pieces of duct materials, then performing sampling with the test equipment to determine the
collection efficiency. The dust used for all methods evaluations was from a single lot of dust that
had been collected from air conveyance systems during cleaning by a local company. Because the
source of the dust, and its composition, was unknown, it could potentially include spores of
microbiological organisms. Therefore, the first step in preparation of the dust was to sterilize it
by steam autoclaving to reduce the hazard associated with handling of the dust. The dust was
then passed through a 42 mesh sieve (0.139 inch, 354 jim diameter opening) to remove fibers and
large particles.
The initial work performed for the methods evaluation was development of a method to
obtain uniform deposition of dust on the surfaces. The first method consisted of deposition of the
dust over a large test area using a small sieve. Dust was placed into the sieve which was gently
tapped while moving it across a known area of the substrate. To assess the uniformity of
deposition on the surface, tared paper coupons were placed at random locations on the surface.
Following dust application, the coupons were weighed and the loading on the surface was
determined by difference between the tared coupons and the coupons with dust deposited on
them. With this method, it was difficult to obtain uniform dust deposition; the coefficient of
variation for six coupons was generally 20 to 40%. To obtain a more accurate measurement of
the amount of dust loaded on a given surface, a second method was employed. This involved
weighing a known mass of dust, placing it in the sieve, and applying it to a 100 cm2 area on the
surface using the same template that was used for sampling. The template was left in place, then
the same area was sampled.
It should be noted that particles were deposited on the test surfaces by tapping the sieve
above the surface. No attempt was made after depositing the particles to embed them into the
porous substrates. The particle deposit on the substrates should, therefore, represent deposits
that would be most easily removed during HVAC cleaning.
A-4
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A template was used to define the sampling area for dust collection with the NADCA
method and the Acurex/EPA medium volume sampling method. The template, which is the one
recommended for the NADCA Vacuum Test Method, consists of a 15 mil thick piece of plastic
with two 2 cm X 25 cm channels for sampling. The template is depicted in the NADCA method.
The tests were performed on the following duct materials:
• Galvanized duct, standard rectangular duct material
• Coated duct liner, Owens-Corning Aeroflex Plus Edge Coated Duct Liner, Type
150
Fiberboard, CertainTeed, Ultra*Duct Fiber Glass Duct Board Systems, and
• Insulated flexible duct, Thermoflex, M-KC, 6-inch
All test substrates were purchased from local suppliers. Detailed specifications for the
materials will be included in the final report.
The evaluations were performed to obtain data for the collection efficiency and precision
of the methods. Selected methods were applied to the galvanized duct, coated duct liner, and the
fiberboard to determine the applicability of the methods to the different surface materials. The
tests were generally performed in triplicate. The NADCA method is not suitable for sampling
from flexible duct and was not evaluated. The test matrix, showing the test methods and the
materials tested is presented in Table 3-1,
Table 3-1 Test Matrix For Validation of Dust Sampling Methods in the Pilot Scale Tests
Test Nos.
HVAC Component Materials
NADCA
1992-01
EPA/Acurex
Dust Sampler
High Volume
Surface
Samnler
1,4,7,11
Galvanized duct
X
X
X
2,5,8
Coated duet liner
X
X
a
3,6,9
Fiberboard
X
X
ji
7,8,10
Insulated flexible duct
X
X
"Initial tests were performed with the high volume sampler, but the amount of mass of duet liner coating
fragments or fibers collected was too high for practical application of this method to the substrate
A - 5
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4.0 TEST RESULTS
The following sections describe the collection efficiency and precision of each method for
the various duct materials.
4.1 NADCA Method
The NADCA method was evaluated at dust loadings of approximately 3 mg/ 100cm2, a
level three times the value considered as acceptable for demonstrating cleaning effectiveness, and
at levels of 7 to 34 mg/100 cm2. Results for the lowest loading, 3 mg/100 cm2, on galvanized
duct are presented in Table 4-1. Collection efficiency averaged 47% for the three replicate
samples. The precision of the method was good, however, with a coefficient of variation of 2%.
Results for the initial evaluation of the NADCA method at dust loadings on galvanized
duct of approximately 7 to 17 mg/lOOcm2 are summarized in Table 4-2. The collection efficiency
for the NADCA method ranged from 60 to 120%, with an average collection efficiency of 92%.
The collection efficiency of 60% may be an outlier resulting from non-uniform distribution of the
test dust on the metal surface. The precision of the method was ± 22%, which was acceptable
considering that some of the variability was associated with the non-uniformity of particle
deposition on the surface due to the particle deposition method used to create the test substrate.
Additional tests on galvanized duct were conducted with higher particle loading on the
test substrates. The higher deposition rates were closer to those expected to be used in the pilot
scale ventilation system tests and encountered in residences to be included in the field study.
Results for these tests are also presented in Table 4-2. At an average loading of 27 mg/100 cm2
on galvanized duct, the collection efficiency was 70 ± 19%. The coefficient of variation for dust
collection was 27%. However, because the dust was not uniformly deposited on the surface (the
coefficient of variation for the six coupons used to determine dust loading on the surface was
23%), most of the variation observed for the NADCA method is likely to be a function of the
variation in the dust deposit. The collection efficiency of 70% would be considered acceptable as
a field method, although, as described below, the alternative method developed by the EPA was
considered more appropriate for the research program and the NADCA vacuum method
ultimately was not used for pre-cleaning sample collection in the field study.
A - 6
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Table 4-1 Results for Initial Tests With The NADCA Method For Dust Sampling From
Galvanized Duct Surfaces With Low Dust Loading
Substrate
Replicate
Loading
(mg/100 cm2)
Dust Collected
(mg/100 cm2)
Collection
Efficiency (%)
Galvanized
1
2.9
1.4
48.3
2
2.9
1.4
46.7
3
3.0
1.4
46.7
Average
47.2 ±0.9
Table 4-2 Results for Initial Tests With The NADCA Method For Dust Sampling From
Galvanized Duct Surfaces With High Dust Loadings
Substrate
Replicate
Loading
(mg/100 cm2)
Dust Collected
(mg/100 cm2)
Collection
Efficiency (%)
Galvanized -Medium
dust loading
1
8,5 ± 3.1
7.2
84.7
2
8.5 ±1.7
8.2
96.5
3
16.8 ±5.6
10.2
60.4
4
8.5 ± 1.2
8.5
100
5
7.4 ±2.8
9.0
120
Average - Medium
Loading
92.3 ±21.9
Galvanized - Heavy
dust loading
1
15.5
57
2 ,
J&
16.5
60
3
J1
24.9
91
Average - HeavyLoading
27.2 ±6.3
19.0 ±5.2
69.6 ±19.0
A - 7
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4.2 Acurex/EPA Medium Volume Sampling Method
Results for tests with the Medium Volume Sampling Method operated at an air flow rate
of 20 L/min are presented in Table 4-3 for galvanized duct, duct liner, and fiberboard substrates.
Collection efficiency was high for the galvanized duct material, averaging 94% for the three
replicates. The precision of the sampling method was excellent, with a coefficient of variation of
only 3.3%. The method was not as effective for collection of dust from coated duct liner or
fiberboard. The recovery efficiency for dust from coated duct liner was 72% if the estimated mass
of background debris was subtracted. The mass of background debris, which may consist of
fragments of the duct liner coating, fibers, or dust already on the surface of the liner as received
from the manufacturer, was estimated by sampling a 100 cm2 area on the surface of the test
substrate on which dust was not deposited. The precision of the method for duct liner was good,
with a coefficient of variation of 7%. Only an average of 63% of the applied dust could be
recovered from fiberboard with the medium volume sampling method if the estimated mass of
background debris was subtracted. As shown in the table, the mass of background material
collected, which consisted primarily of fibers, was high, representing nearly a third of the total
mass collected. The mass of dust recovered was consistent with visual observations of the areas
sampled, on which dust could still be observed after cleaning,
A second series of tests was conducted with the medium volume sampling method at an
air flow rate of 40 L/min. These tests were performed in an attempt to improve collection
efficiency from the porous materials. Tests were also performed using a small nozzle fitted with a
brush to collect dust from flexible ducting.
Results of the tests performed with an air flow rate of 40 L/min are presented in Table 4-4.
As shown in the table, the collection efficiency of the medium volume sampling method
was higher at 40 L/min than at 20 L/min for all three test surfaces. For the galvanized duct
surface there was not a substantial difference. Collection efficiency was greater than 90% both at
20 L/min and 40 L/min. However, for the other two test surfaces, the higher air flow rate
resulted in a substantial improvement in the collection efficiency. For coated duct liner, the
collection efficiency for the dust was 86% with at 40 L/min compared to 72% at 20 L/min. For
the fiberboard, the collection efficiency was 76% at 40 L/min versus 63% at 20 L/min. For all
three surfaces, the precision of the method was excellent, with coefficients of variation of less
than 10 %.
As described in the following section, the high volume sampler had excellent collection
efficiency for dust in flexible duct. However, the medium volume system with a small nozzle
would be attractive for use in field studies due to its smaller size and lighter weight. A small
nozzle would also facilitate easier access to flexible duct. Therefore, the medium volume sampler
was evaluated with a small nozzle fitted with a brush. The method was found to work well, with
an average collection efficiency of 97% and coefficient of variation of 3%, as shown in Table 4-5.
A - 8
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Table 4-3 Results for the Acurex/EPA Medium Volume Sampling Method Operated at 20 L/min for Dust Sampling From Duct
Surfaces
Substrate
Test
No.
Rep.
Loading
(mg/100 cm2)
Total Mass
Collected"
(mg/100 cm2)
Background Mass
Collected15
(mg/100 cm2)
Total Mass Recovery
(%)
Dust Collection
Efficiency0 (%)
CV (%)d
Galvanized
4
a
30.0
28.2
e
94
94
4
b
30.1
27.2
_e
90
90
4
c
29.7
28.7
97
97
Averagef
4
29.9 ±0.2
93.7 ±3.1
93.7 ±3.1
3.3
Duct Liner
5
a
32.2
25.1
0.1
78
78
5
b
20.0
20.3
1.0
71
68
5
c
31.6
22.4
0.3
72
71
Averagef
5
31.3 ± 1.1
80.3 ±2.1
72.1 ±5.3
7.4
Fiberboard
6
a
31.9
20.0
6.7
84
63
6
b
30.9
22.1
6.9
94
72
6
c
29.3
15.7
5.7
73
54
Averagef
6
30.7 ± 1.3
83.5 ± 10.4
62.6 ±9.0
14.4
8 Total mass collected may consist of dust deposited plus fiber, duct liner materials, or other debris on the surface of the substrate
b Mass collected from the substrate prior to deposition of the test dust
c % Recovery of dust loaded on surface (estimated mass of background debris subtracted from the total mass collected)
d % Coefficient of variation
' Background sample not collected
fAverage for three replicate
-------
Table 4-4 Results for the Acurex/EPA Medium Volume Sampling Method Operated at 40 L/min for Dust Sampling From Duct
Surfaces
Substrate
Test
No.
Rep.
Loading
(mg/100 cm2)
Total Mass
Collected"
(mg/100 cm2)
Background Mass
Collectedb
(mg/100 cm2)
Total Mass Recovery
(%)
Dust Collection
Efficiency0 (%)
CV (%)d
Galvanized
7
a
30.0
29.0
0
97
97
7
b
30.8
29.7
0
96
96
7
c
30.9
30.8
0
100
100
Average'
7
97.6 ±1.8
97.6 ±1.8
1.9
Duct Liner
8
a
30.1
28.0
1.9
93
87
8
b
30.1
28.5
1.5
95
90
8
c
30.2
26.0
1.7
86
80
Average®
8
91.3 ±4.7
85.6 ±4.7
5.5
Fiberboard
9
a
30.0
30.0
7.0
100
77
9
b
30.0
30.0
8.2
100
69
9
c
30.0
37.7
13.0
126
82
Average*
9
30.7 ± 1.3
109 ± 15
76.1 ±6.5
8.6
" Total mass collected may consist of dust deposited plus fiber, duct liner materials, or other debris on the surface of the substrate
b Mass collected from the substrate prior to deposition of the test dust
c Recovery (%) of dust loaded on surface (estimated mass of background debris subtracted from the total mass collected)
d Coefficient of variation (%)
e Average for three replicate
-------
Table 4-5 Results for Tests With The Medium Volume Method For Dust Sampling From Flexible
Duct Surfaces
Substrate
Replicate
Loading
(mg/100 cm2)
Dust Collected
(mg/100 cm2)
Collection
Efficiency (%)
Flexible Duct
1
30.2
30.1
100
2
30.1
28.3
94
3
30.7
30.2
98
Average
97.4 ±3.0
4.3 High Volume Sampling Method
Results for the high volume sampling method are presented in Table 4-6. The collection
efficiency for dust deposited in flexible duct average 96% at a loading of 29 mg/100 cm2 and 99%
for a loading of 14.7 mg/100 cm2. For both tests, the precision was excellent.
The high volume sampling method was also evaluated for its applicability to galvanized
duct, coated duct liner, and the fiberboard. The method was not suitable for any of the three
substrates because of the high flow rate. With the galvanized duct material, the sampler drew
dust from under the template, resulting in collection efficiencies of greater than 100%. For duct
liner, the sampling method collected 4.3 mg/100 cm2 of background material (dust, fibers, and
coating fragment s) from clean, unused duct liner. The sampler collected 18 mg/100 cm2 of fibers
from fiberboard that had no dust deposited on it. Because of the very high mass of background
material collected, the sampler was considered unsuitable for these substrates.
5.0 SUMMARY AND RECOMMENDATIONS
' The following observations were made during the laboratory testing:
* Collection efficiency for the NADCA method used to sample dust from galvanized
duct was approximately 50% at a loading of 3 mg/100 cm2. At loadings of approximately 8
mg/100 cm2, the collection efficiency was good, with acceptable precision. At loadings of
approximately 27 mg/100 cm2, the collection efficiency was 70% and the coefficient of variation
was 27%. Visual observations indicated that some particulate matter is lost from the sampler as it
is removed from the template when sampling from surfaces with high dust loading. Therefore,
although the sampling method has acceptable collection efficiency and precision, an alternative
method is recommended for the proposed research studies to evaluate cleaning of air conveyance
systems.
A- 11
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Table 4-6 Results for High Volume Method For Dust Sampling From Duct Surfaces
Substrate
Test
No.
Rep.
Loading
(mg/100 cm2)
Dust Collected
(mg/100 cm2)
Dust Collection
Efficiency (%)
c:v (%r
Flexible
Duct
7
a
29.3
28.9
99
7
b
30.0
27.5
92 .
7
c
29.2
28.3
97
Average1"
7
29.5 ± 0.4
96 ± 3.6
3.8
Flexible
Duct
8
a
14.7
14.3
97
8
b
14.7
14.7
100
8
c
14.8
14.6
99
Average1*
14.7 ±0.02
98.7 ±1.5
1.5
* Coefficient of variation
b Average for three replicates
The NADC A method will be suitable for verifying the effectiveness of cleaning of
galvanized ducts, but it should not be used in this program to determine dust levels
in ducts prior to cleaning or for use on porous surfaces because the method was
not developed for those applications.
The Acurex/EPA medium volume sampling method, operated at 20 L/min with a
specially designed nozzle, had a collection efficiency of 94% for galvanized duct
loaded with 30 mg/100 cm2 of dust. Collection efficiencies were 72% and 63%,
respectively, for coated duct liner and fiberboard if the estimated mass of
background debris was subtracted. When operated at 40 L/min, the collection
efficiencies were substantially improved and are acceptable for use in the planned
testing. Collection of background material from the test substrates represents a
problem for quantifying dust levels under field conditions. This problem needs to
be further addressed in the pilot scale ventilation system tests.
The medium volume dust sampler was evaluated in this study under laboratory
conditions using freshly deposited particulate matter on porous and non-porous
surfaces. Although the tests demonstrate that the method has potential application
for sample collection under field conditions, additional testing should be performed
A- 12
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in ducts where dust deposits have accumulated over long time periods and have
been subjected to environmental conditions that may cause the dust to adhere more
strongly to the duct surfaces. Under field conditions it may be necessary to use a
nozzle with a brush attachment to obtain high collection efficiencies.
Both the medium volume and high volume sampling methods provided excellent
collection efficiency for dust deposited in flexible duct.
The high volume sampling method does not appear to be suitable for galvanized
duct, coated duct liner, or fiberboard using the current sampling protocol.
A-
13
-------
APPENDIX B
FLOOR PLANS, HAC DIAGRAMS, AND HAC EQUIPMENT LIST
FOR THE STUDY HOMES
Hate
Florr plans are sketches and not drawn to exact scale.
Sampling locations are indicated on the floor plan as (1) the primary site and (2) the second
location in the home.
The outdoor location was generally more than 10 meters away from the house.
Diagram of the duct layout is not to an exact scale.
Numbers on HAC layout diagram indicate sampling locations in the ducts that are described
below the diagram.
B-l
-------
PATIO
MASTER
BATH
FAMILY
ROOM
MASTER
BEDROOM
BATHROOM
CL
CL
CLOSET
CLOSET
AHU
LIVING
ROOM
BEDROOM
BEDROOM
1 PRIMARY SITE
2 SECONDARY SITE
3 OUTDOOR SITE
1 MAIN TRUNK-LEFT BACK SHORT OF FIRST FEEDER DUCT
2 MAIN TRUNK - LEFT BACK JUST PAST FIRST FEEDER DUCT
3 MAIN TRUNK - RIGHT FRONT NEAR THIRD FEEDER DUCT
4 MAIN TRUNK- RIGHT FRONT NEAR SECOND FEEDER DUCT
5 MAIN TRUNK - RIGHT FRONT NEAR PLENUM BOX
6 MAIN TRUNK-NEAR LEFT END CAP
Test house
B-2
-------
!
[
FAMILY
ROOM
[
/
( LAUNDRY f
ROOM 1
' '
DINING vrrrxTTTXT
ROOM KITCHEN
RETURN
GRILL
MASTER
BATH
CUD
BATHROOM
V
J
MASTER
BEDROOM
(D
LIVING
ROOM
11111
— CEILING
RETURN
CL
y
STORAGE f
BEDROOM
i-—i
| CLOSET |
/
\
u
3
u
CHILDREN'S
BEDROOM
E=r
1 PRIMARY SAMPLING SITE
2 SECONDARY SAMPLING SITE
3 OUTDOOR SAMPLING SITE
15"0 RETURNS
10 xl2
6"0 TYP
1 FAMILY ROOM SUPPLY (IN HOUSE BY GRJLL)
2 MAIN TRUNK-RIGHT END CAP
3 FEEDER DUCT-TO CHILDREN'S BEDROOM
4 MAIN TRUNK - CENTER BY AHU
5 FEEDER DUCT - TO STORAGE BEDROOM
6 RETURN ATJBLOWER
7 RETURN FROM KITCHEN (IN HOUSE BY GRILL)
8 RETURN FROM CEILING
9 AHU FOIL LINER (IN HOUSE BY GRILL)
10 COOLING COIL
1
B-3
-------
PATIO
MASTER
BEDROOM
•/"
BEDROOM
MASTER
BATH
\ «
) s
u
BATHROOM
y
SLIDING DOOR
KITCHEN
0 DEN
CLOSET
¦RETURN
GRILLS
BEDROOM
LIVING
ROOM
DINING
ROOM
1 PRIMARY SAMPLING SITE
2 SECONDARY SAMPLING SITE
3 OUTDOOR SAMPLING SITE
10"xl2'
AHU
IS" RETURNS
1 MAIN TRUNK - LEFT CENTER
2 MAIN TRUNK-RIGHT CENTER
3 MAIN TRUNK-NEAR LEFT END CAP
4 RETURN - AT GRILL IN HALL (INSIDE HOUSE)
5 RETURN - NEAR AHU
6 COOLING COIL
House 2
B-4
-------
t®
PATIO
1/2 U
BATH
EATING
AREA
KITCHEN
CD
DINING
ROOM
1 PRIMARY SAMPLING SITE
3 OUTDOOR SAMPLING SITE
SUN ROOM
RETURN -
GRILL
MASTER
BATH
LIVING
ROOM
MASTER
BEDROOM
TO
UPSTAIRS
^RETURN
TO
UPSTAIRS
SUPPLY \
RETURN
PLENUM
BOX
6"bTYP
1 MAIN FLEXIBLE TRUNK
2 GALVANIZED PLENUM BOX
3 FLEX DUCT FROM DINING ROOM TO SECOND GALVANIZED PLENUM BOX
4 FLEX DUCT TO LIVING ROOM
5 FLEX DUCT AT PLENUM BOX
6 FLEX DUCT FROM LIVING ROOM
7 FLEX DUCT AT UPSTAIRS RETURN AIR GRILL
8 FOIL LINER
9 COOLING COIL
House 3 first floor
B-5
-------
i-ATTIC ACCESS
BEDROOM
CLOSET
SINKS
BATHROOM Q
OPEN TO LIVING ROOM
RETURN GRILL
BEDROOM
BEDROOM
ATTIC
2 SECONDARY SAMPLING SITE
PLENUM
\BOX
DUCT
FROM
CRAWL
SPACE
House 3 second floor
B-6
-------
(D)
MAW
ROOM
RETURN
GRILL 1
PATIO
x /-
KITCHEN
LAUNDRY
CO
O
FOYER
Z-
1 PRIMARY SAMPLING SITE
3 OUTDOOR SAMPLING SITE
j!
[Jbathroom
> HALL /
FAMILY
ROOM
®A® ©@
•OE3
TO
SECOND
FLOOR
|~Y) SUPPLY i
RETURN
6 uTYP
1 FLEX TO LIVING ROOM
2 FLEX TO SECOND FLOOR
3 FLEX FROM FIRST FLOOR
4 FLEX AT UPSTAIRS RETURN AIR GRILL
5 FOIL LINER
6 COOLING COIL
7 GALVANIZED PLENUM BOX DUCT LINER
House 4, first floor
B-7
-------
CLOSET \
BATHROOM
CLOSET
CLOSET
CEILING
RETURN
GRILL
MASTER
BEDROOM
BEDROOM
2 SECONDARY SAMPLING SITE
FROM
FIRST
FLOOR
PLENUM
BOXES
House 4, second floor
B-8
-------
PATIO
DINING
ROOM
KITCHEN
CEILING •
1 PRIMARY SAMPLING SITE
2 SECONDARY SAMPLING SITE
3 OUTDOOR SAMPLING SITE
r
CEILING
LAUNDRY
ROOM
CLOSET
BATHROOM
CEILING
J
OFFICE/
FAMILY
ROOM
CEILING
(D
J
WALL
AHU
RETURNS FROM
' UNDER STAIRS
/ 12" 0
TO UPSTAIRS /
1 MAIN TRUNK-RIGHT SIDE
2 MAIN TRUNK - LEFT SIDE
3 GALVANIZED DUCT NEAR AH - RIGHT SIDE
4 GALVANIZED DUCT NEAR AHU-BACK SIDE
5 COOLING COIL
House 5, first floor
B-9
-------
MASTER \
BATHROOM
BATHROOM
CLOSET
EXTRA
BEDROOM
MASTER
BEDROOM
CLOSET
CLOSET
CHILD'S
BEDROOM
House 5, second floor
B-10
-------
CARPORT
I
i
1
I
I
I
I
I
GALVANIZED ROUND
.WITH INSULATION
FROM
STAIRS
RETURN
FROM
BEDROOM
1 FLEX DUCT-LAUNDRY ROOM
2 MAIN TRUNK-NEAR END CAP
GALVANIZED ROUND
WITH NO INSULATION
3 MAIN TRUNK - NEAR MIDDLE
4 GALVANIZED DUCT UPSTREAM OF FILTER
5 FLEX DUCT UNDER STAIRS
6 AT BEDROOM RETURN GRILL
7 GALVANIZED DUCT NEAR AHU
= BASEMENT REGISTER FROM CEILING
= = = SPLIT-LEVEL REGISTER FROM FLOOR
-------
CEILING CEILING
BATH
BEDROOM
RETURN
GRILL
CEILING
LAUNDRY
ROOM
CLOSET
_V
House 6, basement
B-J2
-------
CD (
PATIO
^ J
\ 1
1
LAUNDRY (1
ROOM
KITCHEN TABLE
BATHROOM [
OFFICE |
/
FAMILY
ROOM
«=>
•
' (,
UPSTAm* ^ A
/ © I © I \
/ \y—^(D X.
/ RETURN
1 MAIN TRUNK-LEFT AT DISCONNECT
2 MAIN TRUNK - LEFT AT DISCONNECT NEAR FEEDER DUCT
3 PLENUM BOX - RIGHT SIDE
4 MAIN TRUNK-LEFT
5 MAIN TRUNK-TO UPSTAIRS
6 MAIN TRUNK-TRANSITION
7 GALVANIZED DUCT UPSTREAM OF AHU
8 GALVANIZED DUCT UPSTREAM OF RETURN AIR GRILL
House 7, first floor
B-13
-------
CLOSET
0 i
i—i
\ BATH
(=3
BATHROOM
I CLOSET |
BEDROOM J]
\
0
MASTER
BEDROOM
D
,
f
CO
S
D
CLOSET
—
0
BEDROOM
House 7, upstairs
B44
-------
€D|
BEDROOM
CLOSET
SZS
BATHROOM
KITCHEN
y
RETURN
n LIVING
U ROOM
'1
""^RETURN
DINING
ROOM
1 PRIMARY SAMPLING SITE
3 OUTDOOR SAMPLING SITO
MASTER UPSTAIRS
BEDROOM BATHROOM"
KITCHEN
FIRST
FLOOR
BEDROOM
- FIRST
FLOOR
®
UPSTAIRS
BEDROOM
60TYP
DIKING
ROOM
1 MAIN TRUNK-NEAREND CAP
2 MAIN TRUNK-NEAR CENTER
3 MAIN TRUNK - RIGHT OF DISCONNECT
4 MAIN TRUNK-LEFT OF DISCONNECT
5 AT DINING ROOM RETURN GRILL
6 ATAHU
? GALVANIZED DUCT - RIGHT BRANCH
8 COOLING COIL
House 8, first floor
B-15
-------
MASTER
BEDROOM
BATHROOM
/
\
CLOSET
\
/
n nctrr
BEDROOM
CLOSET
2 SECONDARY SAMPLING SITE
House 8, second floor
B-16
-------
House #
Heatina
Coolina
Compressor
1
manf
Inner City Products
Trane
Cumbertand
model tt
NHGK075AF01
EAHB300
OAUA-252A
type
oas
vertical coif
power
75,000 BTU
1/5 hp
year
2
M&nf
Trane
Trane
Trane Heat Pump XE1000
model #
TWH024B140A1
TWR024C100A1
type
electric
A type coil
power
1/4 hp
1/4 hp
1/8 hp
year
Feb-96
Feb-96
Aug-94
3
manf
Trane
(unaccessible)
Trane
model #
BLH100E948H0
BTB736A100A4
type
Gas
vertical
power
100,000 BTU
R22 4lbs 6 oz, 1/4 hp
year
1983
Jun-86
4
manf
Trane
(unaccessible)
Trane
model#
THP100A948A0
BTB730A100BD
type
Gas
Vertical
power
100,000 BTU 1/3 hp
R22 3lbs 5 oz. 1/4 hp
year
Jyl-86
5
man!
(unaccessible)
(unknown)
Trane XL1200
model ft
TTX736A100A2
type
sas
power
R22 Bibs 2 oz, 1/5 hp
year
Mar-89
6
manf
Essex
General Electric
ARCO Aire
model#
SX242NBRF
5KCP39KG5607S
RCF030GBA
type
gas
A type coil
power
1/3 hp
R22 4lbs 6oz, 1/3 hp
year
7
manf
Magic Chef
Amana
model#
GBA125D-9
CR3-1.
type
gas
vertical
power
125,000 BTU
R22 24,7 oz
year
1983
8
manf
Sears 600 series
Sears
Trane XE900
model #
743812
814381
TTD730B100A1
type
oil
A type coil(add on)
power
R22 4!bs Soz, 1/5 hp
year
Jan-53
Mar-89
B-17
-------
APPENDIX C
RESULTS FOR SAMPLES OF DUST COLLECTED IN THE HAC
AT NINE STUDY HOMES
Test House
i
ACS Duct Dust Mass
s
Pre Cleanina
Post Cleanina
g/m2
Supply
Main Trunk-Left Back Short of First Feeder Duct
0.96
0.47
Main Trunk-Left Back Just Past First Feeder Duct
1.81
0.58
Main Trunk-Right Front Near Third Feeder Duct
4.66
1.24
Main Trunk-Right Front Near Second Feeder Duct
L 3.97
0.78
Main Trunk-Right Front Near Plenum Box
1.80
0.27
Main Trunk Near Left End Cap
0.80
1.09
1
Avg:
2.33
0.74
Standard Deviation
1.61
0.37
i ;
Duplicates | ;
Main Trunk Near Left End Cap
1.09
0.79 s
I
a - Sampled with nozzle attachment I
C-l
-------
House No. 1
ACS Duct Dust Mass
Pre Clean ina
Post Cleanina
g/nf
Supply
Feeder Duct from Family Room
2.99
0.25
Main Trunk Near Right End Cap
10.80
0.24
Feeder Duct to Children's Bedroom
2.50
Main Trunk Near Air Handler
0.51
0.41
Feeder Duct to Storage Bedroom
26.28
Avg:
8.62
0.30
Standard Deviation
10.62
0.10
Return
At Air Handler
20.17
0.63
At Kitchen Return Grill
26.25
At Ceiling Return Grill
13.07
0.54
Avg:
19.83
0.58
Standard Deviation
6.60
0.06
Air Handler
Foil Liner
1.70
Cooling Coil
2.35
0.29
Duplicates i
Main Trunk Near Right End Cap | 11.89 I 0.25
Feeder Duct to Storage Bedroom j 100.72 j
C-2
-------
House No, 2
ACS Duct Dust Mass
Pre Cleanina
Post Cleanina
g/m2
Supply
Main Trunk-Left Center
2.22
0.18
Main Trunk-Right Center
5.79
0.16
Main Trunk Near Left End Cap
2.12
0.30
Avg:
3.38
0.21
Standard Deviation
2.09
0.08
•
Return
At Air Handler
7.50
0.28
At Return Grill in Hall
40.76
0.60
Avg:
24.13
0.44
Standard Deviation
23.52
0.23
Air Handler
Cooling Coil
0.20
Duplicates
Main Trunk-Left Center
2.73
0.16
-------
House No. 3
j
ACS Duct Dust Data
\
Pre Cleanina [ Post Cleanina
g/m2
Supply
Main Flexible Trunk
3,00 0.19
Galvanized Plenum Box
2.35 0.35
Flex Duct from Dining Room to Second Galvanized Plenum Box
1.74
Flex Duct to Living Room
0.54 0.21
Avg:
Standard Deviation
1.91 0.25
1.05 0.09
Return
Flex Duct at Plenum Box
7.50 0.23
Flex Duct from Living Room
13.15 0.42
Flex Duct at Upstairs Return Air Grill
2.62 0.19
Avg:
7.76 0.28
Standard Deviation
5.27 0.12
Air Handler
Foil Liner
1.57 0.19
Cooling Coil
0.72
Duplicates
Main Flexible Trunk
0.26
Flex Duct to Living Room
0.34
Flex Duct from Living Room
16.54 , 0.37
C-4
-------
House No. 4
ACS Duct Dust Data
Pre Cleanina
Post Cleanina
g/m2
Supply
Flex Duct to Living Room
1.69
0.19
Flex Duct to Second Floor
1.27
0.34
Avg:
1.48
0.26
Standard Deviation
0.30
0.11
Return
Flex Duct from First Floor
6.22
0.17
Flex Duct at Upstairs Return Air Grill
9.55
0.06
Avg:
7.89
0.11
Standard Deviation
2.35
0.08
Air Handler
Foil Liner
0.46
Cooling Coil
1.81
0.12
Duct Liner
Galvanized Plenum Box Duct Liner
1.62
0.10
Galvanized Plenum Box Duct Liner Duplicate
1.55
Duplicates
Flex Duct to Second Floor
1.47
0.12
Flex Duct from First Floor j 5.11 |
C-5
-------
House No. 5
ACS Duct Dust Data
Pre Cleaning
Post Cleanina
g/m2
Supply
Main Trunk-Right Side
2.62
0.32
Main Trunk-Left Side
1.94
0.87
Avg;
2.28
0.59
Standard Deviation
0.48
0.39
Return
Galvanized Duct Near Air Handler-Right Side
11.49
1.97
Galvanized Duct Near Air Handler-Back Side
11.19
0.25
Avg:
11.34
1.11
Standard Deviation
0.21
1.22
Air Handler
Cooling Coil
2.24
0.13
Dupl i cates
Main Trunk-Right Side
2.52
0.23
Galvanized Duct Near Air Handler-Right Side
10.47
0.59
C-6
-------
House No. 6
ACS Duct Dust Data
Pre Cleanlna
Post Cleanino
g/m2
Supply
Flex Duct in Laundry Room
2.45
Main Trunk Near End Cap
2.00
0.18
Main Trunk Near Middle
2.45
0.18
Avg:
2.30
0.18
Standard Deviation
0.25
0.00
Return
Galvanized Duct Upstream of Filter
3.62
0.19
Flex Duct Under Stairs j
5.18
0.12
At Bedroom Return Grill j
6,99
Galvanized Duct Near Air Handler |
0.13
Avg.)
5.26
0.15
Standard Deviation
1.69
0.04
1
i
Duplicates 1 |
Main Trunk Near End Cap j
2.03 !
Main Trunk Near Middle 1
0,23
Galvanized Duct Upstream of Filter j
6.52 ;
C-7
-------
House No. 7
ACS Duct Dust Data
Pre Cleanina
Post Cleanina
g/m2
Supply
Main Trunk Left at Disconnect
5.93
Main Trunk Left at Disconnect Near Feeder Duct
2.01
Plenum Box-Right Side
4.22
0.44
Main Trunk Left
2.24
0.69
Main Trunk to Upstairs
1.24
Main Trunk Transition
4.39
0.37
Avg;
3.34
0.50
Standard Deviation
1.79
0.17
Return
Galvanized Duct Upstream of Air Handler
9.03
0.30
Galvanized Duct at Upstairs Return Air Grill
16.78
0.34
Avg:
12.91
0.32
Standard Deviation
5.48
0.03
Air Handler
Foil Liner
6.18
0.25
Cooling Coil
2.38
Duplicates
Plenum Box-Right Side
5.07
0.80
Galvanized Duct Upstream of Air Handler
11.66
C-8
-------
House No. 8
ACS Duct Dust Data
Pre Cleanina
Post Cleanina
g/m2
Supply
Main Trunk Near End Cap
22,81
0.44
Main Trunk Near Center
16.39
Main Trunk-Right of Disconnect
36.07
1.13
Main Trunk-Left of Disconnect
28.85
0.80
Avg:
26.03 I 0.79
Standard Deviation
8.41 ; 0.35
Return
I
At Dining Room Return Grill
27.64 0.59
At Air Handler
51.10 0.19
Galvanized Duct-Right Branch
26.59 |
I
Avg:
35.11 0.39
Standard Deviation
13.86 0.28
Air Handler
Cooling Coil Upstream
5.48
Cooling Coil Downstream
0.41 ;
i
[
i
Duplicates
Main Trunk-Right of Disconnect
45.98 ! 0.63
Main Trunk-Left of Disconnect
0.65
At Air Handier
0.26
C-9
-------
APPENDIX D
RESULTS FOR MICROBIOLOGICAL SAMPLES COLLECTED
AT THE NINE STUDY HOMES
Description of the Tables
TSA cassettes and swabs were used for measurement of bacteria concentrations in dust
collected from the surfaces of supply and return ducts.
The TSA cassette vacuum method samples and the TSA swab samples were co-located
measurements at each location listed in the column "samp loc."
SDA cassettes and swabs were used for measurement of fungi concentrations in dust
collected from the surfaces of supply and return ducts.
The SDA cassette vacuum method samples and the SDA swab samples were co-located
measurements at each location listed in the column "samp loc."
The SDA-m/g samples listed in the table are the air samples collected for determination of
fungi concentrations, reported as cfu/m3.
D-I
-------
RAWFIELD.XLS Testhouse
project: 5973-005
|
sampling date*. 5/27/96
1
description: preclean and postelean counts for sampling test house
I
rti/emp a
counts (amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp#
counts
amt plated
total vol
recip dil
cfti/cm*
SDA cassettes - preclean
SDA swabs - preclean
M8646
49
0.1
5
1000
245,000
sup/fdr #1
M8665
68
0.1
5-
100
34,000
M8647
76
0.1
5
100
38,000
sup/fdr#10
M8666
147
0.1
5
10
7,350
M8648
48
0.1
5
100
24,000
sup/fdr 04
M8667
40
0.1
5
10
2,000
M8649
26
0.1
5
100
13,000
sup/fdr #8
SDA cassettes - postelean
SDA swabs - postelean
M8650
113
0.1
5
10
5,650
sup/fdr #1
M8668
108
0.1
5
10
5,400
M8651
138
0.1
5
10
6,900
sup/fdr #4
M8669
92
0.1
5
1
460
M8652
12
0,1
5
100
6,000
sup/fdr #10
M8670
57
0.1
5
100
28,500
M8653
161
0.1
5
1
805
sup/fdr fix
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm*
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm3
TSA cassettes - preclean
TSA swa
3S - prec
ean
M8646
20
0.1
5
1
100
sup/fdr #1
M8665
0.5
0.1
5
1
3
M8647
TNTC
0.1
5
1
na
sup/fdr #10
M8666
0.5
0.1
5
1
3
M8648
0.5
0.1
5
1
3
sup/fdr #4
M8667
0.5
0.1
5
1
3
M8649
0.5
0.1
5
I
3
sup/fdr #8
TSA cassettes - postelean
TSA swa
>s - postelean
M8650
2
0.1
5
10
100
sup/fdr #1
M8668
29
0.1
5
I
145
M8651
30
0.1
5
10
1500
sup/fdr #4
M8669
1
0.1
5
1
5
MS652
TNTC
0.1
5
1
na
sup/fdr #10
M8670
2
0.1
5
1
10
M8653
0.5
0.1
5
1
3
sup/fdr fix
project: 5973-005
sampling date: 5/27/96
description: preclean and postelean counts for sampling test house
|
rti/emp #| counts
time (min)
mVmin
cfu
cfu/m3
SDA - m/g
preclean
M8660
195
60
0.028
3
116
M8661
186
60
0.028
3
111
M8662
668
60
0.028
11
398
•
SDA - m/g
postelean
M8697
360
60
0.028
6
214
M8698
131
60
0.028
2
78
M8699
183
60
0.028
3
109
D-2
-------
House 1
project: 5973-005
I
sampling date: 6/10/96, 6/11/96,6/13/96
I
description: preclean and postclean counts for sampling House 1
rti/emp
counts
amt plated
total vol
recip dil
cfa/cm2
samp loc
rti/emp i
counts
amt plated
total vo!
recip dil
cfu/cm2
SDA cassettes - preclean
SDA swi
lbs - preclean
M8707
50
0.1
5
1000
250000
sup/fdr#l
M8732
141
0.1
5 -
10
7050
M8708
229
0.1
5
10
11450
sup/trnk #2
M8733
121
0.1
5
10
6050
M8709
84
0.1
5
10
4200
sup/tmk #3
M8734
59
0.1
5
10
2950
M8710
37
0.1
5
10
1850
sup/tmk #4
M8735
45
0.1
5
10
2250
M8711
95
0.1
5
10
4750
return
M8736
10
0.1
5
10
500
den diff
M8742
38
0.1
5
1000
190000
*
SDA cassettes - postclean
SDA swabs - postclean
M8712
22
0.1
5
10
1100
sup/fdr#l
M8737
8
0.1
5
1
40
M8713
93
0.1
5
10
4650
sup/tmk #2
M8738
34
0.1
5
10
1700
M8714
23
0.1
5
10
1150
sup/trnk #3
M8739
5
O.i
5
1
25
M8715
17
o.i-
5
10
850
sup/trnk #4
M8740
6
0.1
5
1
30
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
TSA cassettes - preclean
TSA swa
>s - prec
ean
M8707
3
0.1
5
1
15
sup/fdr#l
M8732
1
0.1
5
1
5
M8708
5
0.1
5
1
25
sup/tmk #2
M8733
1
0.1
5
1
5
M8709
23
0.1
5
1
115
sup/tmk #3
M8734
22
0.1
5
10
1100
M8710
6
0.1
5
1
30
sup/tmk #4
M8735
6
0.1
5
1
30
M8711
7
0.1
5
1
35
return
M8736
0.5
0.1
5
I
3
den diff
M8742
13
0.1
5
10
650
TSA cassettes - postclean
TSA swa
js - postclean
M8712
151
0.1
5
1
755
sup/fdr#l
M8737
0.5
0.1
5
1
3
M8713
47
0.1
5
1
235
sup/tmk #2
MS 73 8
15
0.1
5
10
750
M8714
21
0.1
5
1,
105
sup/tmk #3
M8739
24
0.1
5
1
120
M8715
2
0.1
5
1
10
sup/tmk #4
M8740
26
0.1
5
1
130
project: 5973-005
sampling date: 6/10/96,6/11/96, 6/13/96
description: preclean and postclean counts for sampling House 1
rti/emp #
counts
time (min)
mVmin
cfu
cfii/m3
SDA - mJg
preclean ¦
M8703
246
60
0.028
4
146
M8704
276
60
0.028
5
164
M8705
214
60
0.028
4
127
SDA - m/g
postclean
M8757
190
60
0.028
3
113
M8758
149
60
0.028
2
89
M8759
156
60
0.028
3
93
D-3
-------
House 2
project: 5973-005
sampling date: 6/11/96,6/14/96
description: preclean and postclean counts for sampling House 2
rti/emp it
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
SDA cassettes -
sreclean
SDA swabs - preclean
MS717
64
0.1
5
1
320
return#!
M8743
47
0.1
5 -
1
235
M8718
24
0.1
5
10
1200
sup/tmk #2
M8744
136
0.1
5
10
6800
M8719
176
0.1
5
10
8800
sup/tmk #3
M8745
279
0.1
5
10
13950
M8720
382
0.1
5
10
19100
sup/trnlc #4
M8746
110
0.1.
5
10
5500
SDA cassettes -
jostclean
SDA swabs - postclean
M8721
9
0.1
5
1
45
return #1
M8747
52
0.1
5
1
260
M8722
2
0.1
5
1
10
sup/tmk #2
M8748
18
0.1
5
1
90
M8723
3
0.1
5
1
15
sup/trnk #3
M8749
128
0.1
5
1
640
M8724
2
0.1
5
1
10
sup/trnk #4
M8750
13
0.1
5
1
65
•
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm*
TSA cassettes -
jreclean
TSA swabs - preclean
M8717
28
0.1
5
1
140
return #1
M8743
65
0.1
5
1
325
M8718
9
0.1
5
1
45
sup/trnk #2
M8744
9
0.1
5
1
45
M8719
2
0.1
5
1
10
sup/tmk #3
M8745
4
0.1
5
1
20
M8720
il
0.1
5
1
55
sup/tmk #4
M8746
8
0.1
5
1
40
TSA cassettes - postclean
TSA swabs - postclean
M8721
3
0.1
5
1
35
return #1
M8747
5
0.1
5
1
25
M8722
1
0.1
5
1
5
sup/trnk #2
M8748
19
0.1
5
1
95
M8723
1
0.1
5
1
5
sup/trnk #3
M8749
9
0.1
5
1
45
M8724
0.5
0.1
5
1 3
sup/trnk #4
M8750
2
0.1
5
1
10
project: 5973-005
sampling date: 6/11/96,6/14/96
.. 1
description: preclean and postclean counts for sampling House 2
rti/emp #
counts
time (min)
mVmin
cfu
cfu/m3
SDA-m/g
preclean
M8753
1113
60
0.028
19
663
M8754
1030
60
0.028
17
613
M8755
1142
60
0.028
19
680
•
SDA - m/g
postclean
M8763
196
60
0.028
3
117
M8764
291
60
0.028
5
173
M8765
380
60
0.028
6
226
D-4
-------
House 3
project: 5973-005
sampling date: 6/24/96, 6/25/96, 6/27/96 |
description: preclean and postclean counts for sampling House 3
rti/emp
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp
counts
amt plated
total vol
recip dil
cfu/cmJ
SDA cassettes - preclean
SDA swabs - preclean
MS773
513
0.1
5
10
25650
ret plenum
M8797
192
0.1
5-
10
9600
M8774
492
0.1
5
10
24600
ret flex
M8798
312
0.1
5
10
15600
M8775
154
0.1
5
10
7700
sup/fdr
M8799
76
0.1
5
10
3800
M8776
165
0.1
5
10
8250
sup plenum
M8800
45
0.1
5
1
225
M8777
64
0.1
5
10
3200
sup/fdr
M8801
4
0.1
5
1
20
SDA cassettes - postclean
SDA swa
js - postclean
M8778
37
0.1
5
1
185
ret plenum
M8802
21
0.1
5
10
1050
M8779
18
0.1
5
1
90
ret flex
M8803
32
0.1
5
1
160
M8781
34
0.1
5
10
1700
sup/fdr
M8804
28
0.1
5
10
1400
M8780
20
0.1
5
1
100
sup plenum
M8805
97
0.1
5
10
4850
M8782
52
0.1
5
1
260
sup/fdr
M8806
47
0.1
5
1
235
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
TSA cassettes - preclean
TSA swa
bs - prec
ean
M8773
15
0.1
5
1
75
ret plenum
M8797
20
0.1
5
1
100
M8774
14
0.1
5
1
70
ret flex
M8798
18
0.1
5
1
90
M8775
0.5
0.1
5
1
3
sup/fdr
M8799
5
0.1
5
1
25
M8776
0.5
0.1
5
1
3
sup plenum
M8800
17
0.1
5
1
85
M8777
1
0.1
5
1
5
sup/fdr
M8801
3
0.1
5
1
15
TSA cassettes - postclean
TSA swa
3S - postclean
M8778
3
0.1
5
1
15
ret plenum
M8802
6
0.1
5
1
30
M8779
0.5
0.1
5
1
3
ret flex
M8803
0.5
0.1
5
1
3
M8781
4
0.1
5
1
20
sup/fdr
M8804
4
0.1
5
1
20
M8780
4
0.1
5
1,
20
sup plenum
M8805
1
0.1
5
1
5
M87S2
0.5
0.1
5
1
3
sup/fdr
M8806
0.5
0.1
5
1
3
project: 5973-005
sampling date: 6/24/96, 6/25/96, 6/27/96
description: prec
ean and postclean counts for sampling House 3
rti/emp #
counts
time (min)
m'/min
cfu
cfu/m'
SDA - m/g
preclean •
M8769
30
10
0.028
3
107
M8770
49
10
0.028
5
175
M8771
45
10
0.028
5
161
SDA - m/g
postclean
N48822
26
10
0.028
3
93
M8823
28
10
0.028
3
100
M8824
30
10
0.028
3
107
D-5
-------
House 4
project: 5973-005 j
sampling date: 6/25/96, 6/28/96
description: preclean and postclean counts for sampling House 4
rti/emp
counts
amt plated
total vol
recip dil
cfu/cma
samp loc
rti/emp M
counts
amt plated
total vol
recip dil
cfu/cmJ
SDA cassettes - preclean
SDA swabs - preclean
M8783
14
0.1
5
1
700
ret/fix
M8807
24
0.1
5 -
1
1200
M8784
13
0.1
5
1
650
ret/plenum
M8808
8
0.1
5
1
400
M8785
10
0.1
5
1
500
sup/fdr
M8809
90
0.1
5
1
4500
M8786
324
O.i
5
10
162000
sup/plenum
M8810
347
0.1
'5
10
173500
M8787
184
0.1
5
10
92000
sup/fdr
M8811
228
0.1
5
10
114000
SDA cassettes - postclean
SDA swabs-postclean
M8788
0.5
0.1
5
10
250
ret/fix
M8812
12
0.1
¦5
1
€00
M8789
2
0.1
5
10
1000
ret/plenum
M8813
13
0.1
5
1
650
M8790
71
0,1
5
10
35500
sup/fdr
M8814
15
0.1
5
10
7500
ME791
60
0.1
5
10
30000
sup/plenum
M8815
35
0.1
5
10
17500
M8792
99
0.1
5
1
4950
sup/fdr
M8816
19
0.1
5
1
950
kitchen reg
M8821
17
0.1
5
1
850
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm5
TSA cassettes - preclean
TSA swa
js - prec
ean
M8783
21
0.1
5
1
1050
ret/fix
M8807
45
0.1
5
1
2250
M8784
6
0.1
5
1
300
ret/plenum
M8808
16
0.1
5
1
800
M8785
0.5
0.1
5
1
25
sup/fdr
M8809
7
0.1
5
1
350
M8786
2
0.1
5
1
100
sup/plenum
M8810
16
0.1
5
1
800
M8787
0.5
0.1
5
1
25
sup/fdr
M8811
2
0.1
5
1
100
TSA cassettes - postclean
TSA swabs - postclean
M8788
0.5
0.1
5
1
25
ret/fix
M8812
1
0.1
5
1
50
M8789
0.5
0.1
5
1
25
ret/plenum
M8813
4
0.1
5
1
200
M8790
0.5
0.1
5
1.
25
sup/fdr
M8814
6
0.1
5
1
300
• M8791
5
0.1
5
1
250
sup/plenum
M8815
4
0.1
5
I
200
M8792
1
0,1
5
1
50
sup/fdr
M8816
23
0.1
5
1
1150
kitchen reg
M8821
1
0.1
5
1
50
project: 5973-005
sampling date: 6/25/96, 6/28/96
description: preclean and postclean counts for sampling House 4
rti/emp #| counts
time (min)
mVmin
cfu
cfu/m*
SDA - m/g
preclean
M8817
55
10
0.028
6
196
M8818
84
10
0.028
8
300
M8819
34
10
0.028
3
121
SDA - m/g
postclean
M8828
88
10
0.028
9
314
M8829
84
10
0.028
8
300
M8830
63
10
0.028
6
225
D-6
-------
House 5
project; 5973-005 |
sampling date: 7/15/96, 7/16/96, 7/18/96
description: preclean and postciean counts for sampling House 5
|
rti/emp #| counts
amt plated
total vol
recip dil
cfu/cm1
samp Ioc
rti/emp #
counts
amt plated
total vo
recip dil
cfu/cm2
SDA cassettes - preclean
SDA sws
is - preclean
M8838
17
0.1
5
1
85
return flex
M8863
5
0.1
5-
1
25
M8839
18
0.1
5
1
90
ret plenum
M8864
6
0.1
5
1
30
M8840
22
0.1
5
1
110
sup plenum
M8866
4
0.1
5
1
20
M8841
1
0.1
5
]
5
sup/fdr #4
M8867
0.5
0.1
5
1
3
fan blade
M8865
21
0.1
5
10
1050
SDA cassettes - postciean
SDAswa
js - postciean
M8842
3
0.1
5
I
15
return flex
M8868
10
0.1
5
1
50
M8843
16
0.1
5
1
80
ret plenum
M8869
27
0.1
5
1
135
M8844
9
0.1
5
1
45
sup plenum
M8871
24
0.1
5
1
120
M8845
3
0.1
5
1.0E+0
1.5E+1
sup/fdr #4
M8872
1
0.1
5
1
5
fan blade
M8870
0.5
0.1
5
1
3
•
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cmJ
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm1
TSA cassettes - preclean
TSA swa
bs - prec
ean
M8838
6
0.1
5
1
30
return flex
M8863
12
0.1
5
1
60
M8839
2
0.1
5
1
10
ret plenum
M8864
1
0.1
5
1
5
M8840
3
0.1
5
1
15
sup plenum
M8866
6
0.1
5
10
300
M8841
1
0.1
5
1
5
sup/fdr #4
M8867
1
0.1
5
1
5
fan blade
M8865
20
0.1
5
10
1000
TSA cassettes - postciean
TSA swa
3S - postciean
M8842
0.5
0.1
5
1
3
return flex
M8868
6
0.1
5
1
30
M8843
1
0.1
5
1
5
ret plenum
M8869
2
0.1
5
1
10
M8844
2
0.1
5
1
10
sup plenum
M8871
12
0.1
5
1
60
M8845
0.5
0.1
5
I
3
sup/fdr #4
M8872
1
0.1
5
1
5
fan blade
M8870
2
0.1
5
1
10
project: 5973-005
sampling date: 7/15/96
description: preclean and postciean counts for sampling House 5
rti/emp #
counts
time (min)
m'/min
cfu
cfu/m'
SDA - m/g
preclean .
M8834
63
60
0.028
1
38
M8835
24
60
0.028
0
14
M8836
107
60
0.028
2
64
SDA - m/g postciean
M8891
89
60
0.028
1
•53
M8892
3
60
0.028
0
2
M8893
179
60
0.028
3
107
D-7
-------
House 6
project: 5973-005 |
sampling date: 7/16/96, 7/17/96,7/19/96
description: preclean and postclean counts for sampling House 6
-
rti/emp H
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vo
recip dil
cfu/cm2
SDA cassettes - preclean
SDA sws
>s - preclean
M8846
4
0.1
5
1
20
return# I
M8873
51
0.1
5 -
10
2550
M8847
24
0.1
5
1
120
ret/flx #2
M8874
35
0.1
5
1
175
M8848
21
0.1
5
1
105
return #3
M8875
13
0.1
5
10
650
M8849
10
0.1
5
1
50
sup/fdr #4
M8876
3
0.1
5
1
15
M8850
32
0.1
5
1
160
sup/fdr #5
M8877
10
0.1
5
1
50
M8851
29
0.1
5
1
145
sup/tmk #6
M8878
50
0.1
5
1
250
SDA cassettes - postclean
SDA swa
)s - postclean
M8854
26
0.1
5
1
130
sup/trnk #6
M888I
18
0.1
5
I
90
M8855
0.5
0.1
5
I
3
sup/fdr #5
M8882
4
0.1
5
1
20
M8857
3
0.1
5
1
15
return #3
M8888
1
0.1
5
1
5
M8858
1
0.1
5
1
5
ret/flx #2
M8889
0.5
0.1
5
1
3
M8859
0.5
0.1
5
1
3
return #1
M8890
1
0.1
5
1
5
SDA cassettes - after air wash
SDA swa
3S - after air wash
M8852
10
0.1
5
1
50
sup/trnk #6
M8879
8
0.1
5
1
40
M8853
2
0.1
5
1
10
sup/fdr #5
M8880
5
0.1
5
1
25
M8856
10
0.1
5
1
50
return #3
M8887
5
0.1
5
1
25
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
TSA cassettes - preclean
TSA swabs - prec
ean
M8846
1
0.1
5
1
5
return#!
M8873
29
0.1
5
1
145
M8847
9
0.1
5
1
45
ret/flx #2
M8874
39
0.1
5
1
195
M8848
38
0,1
5
1
190
return #3
M8875
54
0.1
5
1
270
M8849
2
0.1
5
1
10
sup/fdr #4
M8876
2
0.1
5
1
10
M8850
0.5
0.1
5
1
3
sup/fdr #5
M8877
1
0.1
5
1
5
M8851
6
0.1
5
1.
30
sup/trnk #6
M8878
5
0.1
5
1
25
•
TSA cassettes - postclean
TSA swabs - postclean
M8854
21
0.1
5
1
105
sup/trnk #6
M8881
28
0.1
5
1
140
M8855
1
0.1
5
1
5
sup/fdr #5
M8882
7
0.1
5
1
35
M8857
1
0.1
5
1
5
return #3
M8888
0.5
0.1
5
1
3
M8858
0.5
0.1
5
1
3
ret/flx #2
M8889
1
0.1
5
1
5
M8859
1
0.1
5
1
5
return #1
M8890
4
0.1
5
1
20
TSA cassettes - after air wash
TSA swa
js - after air wash
M8852
1 | 0.1 j 5
1
5
sup/tmk #6
M8879
5
0.1
5
1
25
M8853
2 | 0.1 5
1
10
sup/fdr #5
M8880
1
0.1
• 5
1
5
M8856
0.5 0.1 5
i
3
return #3
M8887
6
0.1
5
1
30
I 1
D-8
-------
House 6
project: 5973-005
sampling date: 7/16/96,7/19/96
description: prec
ean and postclean counts for sampling House 6
rti/'emp # counts
time (min)
m'/min
cfu
cfu/m3
SDA - m/g
preclean
M8883
152
60
0,028
3
90
-
M8884
108
60
0.028
2
64
MS885
120
60
0.028
2
71
SDA - m/g postclean
M8897
156
60
0.028
3
93
M8898
95
60
0.028
2
57
M8899
101
60
0.028
2
60
D-9
-------
House 7
project: 5973-005
sampling date: 7/30/96
description: prec
can and postclean counts for sampling House 7
rti/emp
counts
amt plated
total vol
reeip dil
cfu/cmJ
samp loc
rti/emp
counts
amt plated
total vo!
recip di
cfu/cmJ
SDA cassettes - preclean
SDA sws
tbs - preclean
M8963
12
0.1
5
1
60
ret plenum
M8993
3
0.1
5-
1
15
M8964
48
0.1
5
10
2400
return #2
MS994
4
0.1
5
100
2000
M8965
22
0.1
5
1
110
sup/fdr #3
M8995
3
0.1
5
1
15
M8966
29
0.1
5
100
14500
sup plenum
M8996
86
0.1
5
100
43000
M8967
77
0.1
5
10
3850
sup/tmk #5
M8997
65
0.1
5
1
325
SDA cassettes - postclean
SDA swabs - postclean
M8968
86
0.1
5
1
430
ret plenum
M8998
4
0.1
5
1
20
M8969
8
0.1
5
1
40
return #2
M8999
0.5
0.1
5
1
3
M8970
3
0.1
5
1
15
sup/fdr #3
M9000
2
0.1
5
1
10
M8971
2
0.1 •
5
1
10
sup plenum
M9001
3
0.1
5
1
15
M8972
3
0.1
5
10
150
sup/tmk #5
M9002
4
0.1
5
1
20
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm*
TSA cassettes - preclean
TSA swa
5s - prec
ean
M8963
5
0.1
5
1
25
ret plenum
M8993
9
0.1
5
10
450
M8964
4
0.1
5
10
200
return #2
M8994
11
0.1
5
1
5,5
M8965
5
0.1
5
1
25
sup/fdr #3
M8995
11
0.1
5
10
550
M8966
0.5
0.1
5
1
3
sup plenum
M8996
16
0.1
5
10
800
MS967
48
0.1
5
1
240
sup/trnk #5
M8997
16
0,1
5
10
800
TSA cassettes - postclean
TSA swa
3S - postclean
M8968
37
0.1
' 5
10
1850
ret plenum
M8998
41
0.1
5
10
2050
M8969
0.5
0,1
5
1
3
return #2
M8999
11
0.1
5
10
550
M8970
5
0.1
5
10
250
sup/fdr #3
M9000
11
0.1
5
1
55
M8971
1
0.1
5
10
50
sup plenum
M9001
9
0.1
5
10
450
tM8972
0.5
0.1
5
1
3
sup/tmk #5
M9002
6
0.1
5
1
30
project: 5973-005
sampling date: 7/29/96, 8/1/96
description: preclean and postclean counts for sampling House 7
rti/emp #
counts
time (min)
m'/min
cfu
cfu/m3
SDA - m/g
preclean •
M8903
215
60
0.028
4
128
M8904
92
60
0.028
2
55
M8961
73
60
0.028
1
43
SDA - m/g postclean
M9021
117
60
0.028
2
70
M9022
97
60
0.028
2
58
M9023
18
60
0.028
0
11
D-10
-------
House 8
project: 5973-005 |
J
sampling date: 7/30/96,7/31/96
¦ description: preclean and postclean counts for sampling House 8
rti/emp
counts
amt platec
total vo
recip dil
cfu/cm1
samp loc
rti/emp
counts
amt platec
total vo!
recip dil
cfu/cm2
SDA cassettes - preclean
SDA swabs - preclean
M8973
41
0.1
5
1
205
return #1
M9003
15
0.1
5 -
1
75
M8974
16
0.1
5
1
80
sup/tmk #2
M9004
6
0.1
5
1
30
M8975
35
0.1
5
1
175
return #3
M9005
63
0.1
5
1
315
M8976
34
0.1
5
1
170
sup/tmk #4
M9006
7
0.1
5
1
35
M8977
7
0.1
5
1
35
sup/tmk #5
M9007
5
0.1
5
I
25
coil drain
M9008
13
0.1
5
10
650
coil
M9009
32
0.1
5
10
1600
SDA cassettes - postclean
SDA swa
5S - postclean
M8978
OS
0.1
5
1
3
return#!
M9010
3
0.1
5
1
15
M8979
0.5
0.1
5
1
3
sup/tmk #2
M901I
1
0.1
5
1
5
M8980
0.5
0.1
5
1
3
return #3
M9012
3
0.1
5
1
15
M8981
0.5
0.1
5
1
3
sup/tmk #4
M9017
1
0.1
5
1
5
M8982
3
0.1
5
1
15
sup/tmk #5
M9018
0.5
0.1
5
I
3
coil drain
M90I9
14
0.1
5
1
70
coil
M9020
1
0.1
5
1
5
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm2
samp loc
rti/emp #
counts
amt plated
total vol
recip dil
cfu/cm3
TSA cassettes - preclean
TSA swabs - preclean
M8973
2
0.1
5
10
100
return M1
M9003
3
0.1
5
10
150
M8974
3
• 0.1
5
10
150
sup/tmk #2
M9004
3
0.1
5
10
150
M8975
0.5
0.1
5
1
3
return #3
M9005
15
0.1
5
1
75
M8976
1
0.1
5
10
50
sup/trnk #4
M9006
0,5
0.1
5
1
3
M8977
5
0.1
5
1
25
sup/trnk #5
M9007
0.5
0.1
5
1
3
coil drain
M9008
2
0.1
5
10
100
coil
M9009
6
0.1
5
10
300
TSA cassettes - postclean
TSA swabs - postclean
M8978
0.5
0.1
5
1
3
return #1
M9010
2
0.1
5
10
100
M8979
0.5
0.1
5
1
3
sup/trnk #2
M9011
8
0.1
5
1
40
M8980
0.5
0.1
5
1
3
return #3
M9012
2
0.1
5
10
100
M8981
3
0.1
5
1
15
sup/tmk #4
M9017
4
0.1
5
10
200
M8982
0.5
0.1
5
1
3
sup/trnk #5
M9018
1
0.1
5
10
50
•
coil drain
M9019
3
0.1
5
10
150
coil
M9020
1
0.1
5
10
50
D-l ]
-------
House 8
project: 5973-005
j
sampling date; 7/30/96, 8/2/96
(
description: preclean and postclean counts for sampling House 8
rti/emp#
counts
time (min)
mVmin
Cfti
cfu/m3
SDA - m
precl
ean
M9013
131
60
0.028
2
78
M9014
116
60
0.028
2
69
M9015
134
60
0.028
2
80
SDA-m/g postc
ean
M9027
117
60
0.028
2
70
M9028
138
60
0.028
2
82
1
M9029
144
60
0.028
2
86
1
D-l 2
-------
APPENDIX E
CLIMET MEASUREMENT RESULTS FOR PARTICLES
IN THE SIZE FRACTION > 5.0 fim DIAMETER
Note
Data were not downloaded from the Cliraet for the > 5.0 jam size fraction
at Houses 1 and 2
E-l
-------
1000000
Test House
Climet: |>5.0 um
900000
800000 -
Pre-Cleaning
Post-Cleaning
Cleaning day
700000 -
600000
500000 -
400000 --
300000
200000 -
100000
o
o
o
5.0 um size fraction at Test House
-------
600000
m
500000
400000 --
n
E
| 300000
ti
Q.
200000
100000
House 3
Climet: >5.0 um
Cleaning Day
Pre-CIeaning
Post-Cleaning
Sun
Mon
Tues
(N o 5.0 um size fraction at House 3
-------
tn
i
600000
500000
400000
¦g 300000
c
5.0 um
Sun
Mon
Tue
Post-cleaning
Cleaning day
Wed
Thur
Fri
Sat
Sun
Mon
Tue
Wed
Figure 5-10. Airborne particle concentrations in the >5.0 um size fraction at House 4
-------
600000
House 5
Climet: >5.0 um
500000
400000 -
Cleaning Day
E
% 300000
'€
Q.
Pre-Cleaning
Post-Cleaning
200000
100000 -
(N0(N0(N0(N0(N0(N0(N05.0 um size fraction at House 5
-------
600000
House 6
Climet: >5.0 um
500000 -
Cleaning Day
400000 -
m
G
% 300000
t
Q.
Pre Clean
Post-Cleaning
200000 -
100000 -
oo
VO
00
vo
00
00
vo
00
vo
00
oo
vo
00
Mon Tue Wed Thur Fri Sat Sun Mon Tue Wed
Airbrone particle concentrations in the >5.0 um size fraction at House 6
-------
600000
m
-ij
500000 -
400000
300000
tS
rt
Q.
200000
100000
Cleaning day
Pre-cleaning
House 7
Climet: >5.0 um
Post-cleaning
i—l—h
CM
Sun
H—I—I—I—*
3 CM O
v—
Mon
CM
Tue
Wed
Figure 5-11. Airbrone particle concentrations in the >5.0 um size fraction at House 7
-------
600000
House 8
Climet: >5.0 um
500000
Pre-Cleaning
Post-Cleaning
400000
Cleaning Day
rn
E
^ 300000 -
'£
Q.
200000 --
100000 -
-I-
5.0 um size fraction at House 8
-------
APPENDIX F
MEAN CONCENTRATIONS OF PARTICLES IN 16 SIZE FRACTIONS MEASURED
WITH THE LAS-X PRE- AND POST-HAC CLEANING
Lasx Data
Pftreetat X lo'/m1
Uleron*
T(MtNeu»*
IMJ
Pi*
Avg:
106.145
129-&33
134 802
84.111
54,205
20.715
7J390
0.144
0.07S
0.040
0.010
0.007
0-003
0.001
0.000
0.001
SUDtv.
4.544
1.847
2588
2.321
2.511
0.845
0.855
0.016
0.017
0.016
0.005
Q.005
0.801
0.000
0.000
0.000
Po
-------
APPENDIX G
RESULTS OF SCANNING ELECTRON MICROSCOPY ANALYSES OF SAMPLES
COLLECTED AT THE NINE STUDY HOMES
G-l
-------
Log of SEM Samples
House Pre-Cleaning Sample Post-Cleaning Sample
TH AEFJB0021 AEFIBQ033
1 AEFIB0049 AEFTO0059
2 AEFIB0055 AEEffi0063
3 AEFIB0072 AEFIB0080
4 AEFJB0077 AEFB0081
5 AEFBO097 AEFTB0100
6 AEFIB0108 AEFIB0109
7 AEFIBOI25 AEFIB0127
8 AEFIB0133 AEFIB0136
G-2
-------
RJ LeeGroup, Inc.
350 Hochberg Road • Monroeville, PA 15146
412/325-1776 • FAX 412/733-1799
June 17,1996
Mr. Cary P. Gentry
Acurex Environmental, Inc.
P.O. Box 13109
Research Triangle Park, NC 27709
RE: Analysis of MCE Filters
RJ Lee Group Project No. AOW605190
Dear Mr. Gentry:
Enclosed are the results of the analyses of the two MCE filters which we received on June 3,1996
(reference your Chain of Custody dated May 31,1996). The samples were identified by you as
AEFXB0021 and AEFXB0033 and were assigned RJ Lee Group Sample Nos. 609237 and 609238,
respectively.
The purpose of this investigation was to characterize the air filter particulate paying particular
attention to the fibrous material. Manual scanning electron microscopy (SEM) was the method
used. The as-received samples were previewed using a stereo optical microscope. One half of
each filter was attached to an SEM stub using carbon tape and given a thin coating of . carbon by
evaporative deposition to prevent charging during analysis.
Light Microscopy - General Appearance
The cassette contained an MCE filter with a moderate loading (heavier loading toward the center) of
brown-to-black particulate.
MSEM Evaluation
Estimated
Particle Type Comments Contribution*
Si/Al-rich particles Clay minerals (some associated with Major
Ca/S-rich or Fe-rich particles)
Cu-rich particles 1-4 [im, commonly spheres Moderate
Si-rich particles Quartz (2-10 Jim) Minor
Ca/S-rich particles 1
Fe-rich particles
Cellulose Trace
Fibrous glass 1 observed (50 (im x 1 pun) Trace
* Definitions for acronyms, "Estimated Contribution" and the elemental names for the symbols listed in this report
can be found on the page 3.
G-3
Monroeville, PA ~ San Leandro, CA * Washington, DC * Houston, TX * Richland, WA
-------
Mr. Gary P. Gentry
RJ Lee Group Project No. AOW605190
June 17, 1996
Page 2
Sample AF,H'i B0Q33 (RJLee Grow Sample No.609238)
Light Microscopy - General Appearance
The cassette contained an MCE filter with heavy loading of brown-to-black particulate.
MSEM Evaluation
Particle Type
Si/Al-rich particles
C-rich particles
Cellulose
Ca/S-rich particles
Fe-rich particles
Ti-rich particles
Pb
Cu
Comments
Clay minerals (some associated with
Fe-rich particles up to 25 pro.) A
few spheres were observed,
Blocky in shape (up to 10 |im). A
few spheres and 1 skin flake was
observed.
2-5 Jim
2-5 nm
2 |im
1 particle observed (1 pm)
Estimated
Contribution
Major
Moderate
Trace
Trace
Trace
Trace
Trace
Trace
The overall composition of the two samples was similar, but Sample AEFIB0033 was
considerably heavier in loading and consisted of larger particulate (up to 25 jim was common).
The major component-in both samples was Si/Al-rich particles (see Figure 1). Copper particles
were commonly observed in AEFIB0021 but were rarely observed in sample AEFEB0033 (see
Figure 2). Representative images of Si-rich and Ca/S-rich particles are shown in Figures 3 and 4,
respectively. Other than cellulose, fibers were not common in either sample but one fibrous glass
was observed in sample AEFIB0021 (see Figure 5), and a rock wool and manmade fiber were
observed in AEFIB0033.
These results are submitted pursuant to RJ Lee Group's current terms and conditions of sale,
including the company's standard warranty and limitation of liability provisions. No responsibility
or liability is assumed for the manner in which the results are used or interpreted. Unless notified
to return the samples covered by this report, RJ Lee Group will store them for a period of thirty
(30) days before discarding.
Should you have any questions regarding this information, please do not hesitate to contact me.
Sincerely,,
Stephen K. Kennedy, Ph.D
Senior Geologist
Environmental Services
SKKtdls
Attachments
G-4
-------
Mr. Gary P. Gentry
RJ Lee Group Project No. AOW605190
June 17, 1996
Page 3
Acronyms
Definitions
EDS Energy dispersive spectroscopy
MSEM Manual scanning electron microscopy
pm Micrometers
Chemical Element1?
AI Aluminum
C Carbon
Ca Calcium
Cu Copper
Fe Iron
Pb Lead
S Sulfur
Si Silicon
H Titanium
Estimated Contribution
Major Estimated to comprise > 40 percent of the sample by number
Moderate Estimated to comprise between 20 and 40 percent of the sample by number
Minor Estimated to comprise between 5 and 20 percent of the sample by number
Trace Estimated to comprise < 5 percent of the sample by number
G-5
-------
ACUREX ENVIRONMENTAL, INC.
RJ Lee Group Project No. AOW605190
Figure 1. Representative backscattered electron image and EDS spectrum of Si/Al-rich particle
%
MM I«M4k
g.v' 4.','^'1 'i1.'1 u.v' iiv1 M'.v1 1 uv1 y.u,
r:\nKNAouiixrv3tm.fir
SCrratlN «r Or%u» in;
Figure 2. Representative backscattered electron image and EDS spectrum of Cu particle
G-6
-------
ACUREX ENVIRONMENTAL, INC.
RJ Lee Group Project No. AOW6Q5190
•>* iotx,
gSB:
frwjwr
l«ntjNupiMnr
•¦n»l«_nunb«r<
Count* urs-rz?
m.
I i 11 IT
' 4,1' ' [l'?T,VJ1 'IV 1 U V 1UV1 U.V 1 UV ' UV'k.W
SVfMXIH Mr <*HU tmm «rm* t992
Figure 4. Representative backscattered electron image and EDS spectrum of Ca/S-rich particle
G-7
-------
ACUREX ENVIRONMENTAL, INC,
RJf Lee Group Project No. AOW605190
AnalvfitJIal** M/M/M Cwimil'
tmtmmmt" far-frcmat ttn H- P:M*WN*CVJlDPs2t?»S.IIF
ft/ B ZEPPELIN MP
-------
RJ LeeGroup, Inc.
350 Hochberg Road • MonroevMle, PA 15146
412/325-1776 • FAX 412/733-1799
June 27,1996
Mr. Gary Gentry
Acurex Environmental, Inc.
P.O. Box 13109
Research Triangle Park, NC 27709
RE: Characterization of Four Polycarbonate Filter Samples
RJ Lee Group Project No. AOW606118
Dear Mr. Gentry:
Enclosed you will find a summary of the analytical results for the four air samples that you recently
sent us (reference your Laboratory Request dated June 21,1996). The samples were identified as
follows:
Acurex Environmental RJ Lee Group
Sample id Sample No.
49 609343
55 609344
59 . 609345
63 609346
The purpose of this investigation was to characterize material collected on the sampling cassettes by
manual scanning electron microscopy (MSEM). MSEM distinguishes among different particle
types based on morphology and elemental composition utilizing backscattered electron imaging
(BSI) and energy dispersive spectroscopy (EDS). In the BSI mode, higher atomic number
elements generate more backscattered electrons than do lower atomic number elements resulting in
a brighter image for heavier materials. Elemental composition of each species can be obtained
utilizing (EDS) techniques. Sample preparation involved mounting a portion of the filter onto an
SEM stub and coating it with a thin layer of carbon by evaporative depositiorrunder vacuum.
Acurex Environmental Sample No. 49 (R.T Lee Group Sample No.6ft9343^
Particle Type Comments Estimated Contribution
C-rich particles Combustion Material 85%
Si/Al-rich Feldspar 10%
Miscellaneous Earth Crustal Materials 5%
The bulk of the particulate on the filters was carbon-rich particles. These particles were dominantly
spheres <1 pmin diameter. Minor sulfur was associated with these spheres suggesting formation
from a combustion source (see Figure 1). Feldspars were present "as >2 jim particles and
miscellaneous particulate consisted of earth crustal materials (see Figures 2 and 3).
G-9
Monroeville, PA • San Leandro, CA • Washington, DC * Houston, TX « Richland, WA
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW606118
June 27,1996
Page 2
Acurex Environmental Sample No, 55 (RJ Lee Group Sample No.609344)
Particle Type Comments Estimated Contribution
C-rich particles Carbonaceous Fragments 100%
Only carbonaceous particles were present on this filter. Hie sample was composed of particles
similar to plant and insect fragments (see Figures 4 and 5), a few less than 1 jim spheres, and
miscellaneous carbon particles. Carbonaceous spheres (<1 pQ) consisted of approximately 5% of
the bulk particulate. TTiis sample also contained the lightest particle loading of the four samples.
Acurex Environmental Sample No. 59 CRT Lee Group Sample No, 6093451
Particle Type COTOgnt? Estimated Contribution
C-rich particles Carbonaceous Fragments 100%
Sample 609245 contained carbon-rich particles consisting of plant and animal fragments and other
miscellaneous carbon particles. Figures 6 and 7 show the typical carbonaceous fragments
observed within the sample. A few carbon spheres without sulfur were observed.
Acurex Environmental Sample No. 63 (R.T Lee Group Sample No.60934<^
Particle Type Comments Estimated Contribution
C-rich particles Combustion Material 95%
Miscellaneous Earth Crustal Materials 5%
The majority of this sample consisted of >1 (ixn spheres with minor sulfur contents suggesting a
combustion source. Figure E shows a cellulose particle (left) and a wood fragment (right).
Figure 9 is a carbon-rich phase abundant within the carbon-rich particles. Miscellaneous particles
consisted of feldspars and other earth crustal particles.
These results are submitted pursuant to RJ Lee Group's current terms of sale, including the
company's standard warranty and limitation of liability provisions and no responsibility or liability
is assumed for the manner in which the results are used or interpreted.
Should you have any questions regarding this information, please do nqt hesitate to contact John
Johns before 3:00 p.m. or me after 3:00 p.m.
Sincerely,
Steve Badger
Project Manager
Environmental Services
SB:dls
Attachments
G-10
-------
Figure t
15000X i : 1 2.0 um
150.
100.
50.
'I, tl^tl .kill ^1 *'*- ¦ -J
G-ll
-------
Figure 2 (EDSofiigtit pirlicle)
2.0 urn
G-12
-------
Figure 4
G-13
-------
Figure G
0 1 2 3 ,4 5 6 7 8 9 10
- •¦•"V'.'-v'- ¦ - y- *>• '
G-14
-------
Figure S
G-15
-------
RJ LeeGroup, Inc.
350 Hochberg Road • Monroeville, PA 15146
July 15 1996 412/325-1776 • FAX 412/733-1799
Mr. Gary Gentry
Acurex Environmental, Inc.
4915 Prospectus Dr.
Durham, NC 27713
RE; Characterization of Four Air Samples
RJ Lee Group Project No. AOW607044
Dear Mr. Gentry:
Enclosed you will find a summary of the analytical results for the filter samples that you recently
sent us (reference your Laboratory Request dated July 8,1996). Hie samples were identified as
follows: .
Acuiex RJ Lee Group
Sample ID Sample No,
AEFIB0077 609423
AEFIB0081 609424
AEFEB0072 609425
AEFEB0080 609426
The purpose of this investigation was to characterize material collected on four 37 mm
polycarbonate filters by manual scanning electron microscopy (MSEM). MSEM distinguishes
among different particle types based on morphology and elemental composition utilizing
backscattered electron imaging (BSI) and energy dispersive spectroscopy (EDS). In the BSI
mode, higher atomic number elements generate more backscattered electrons than do lower atomic
number elements resulting in a brighter image for heavier materials. Elemental composition of each
species can be obtained utilizing (EDS) techniques. Sample preparation involved mounting a
portion of the filter onto an SEM stub and also by shaking fine particulate matter and fibers from
the filter onto carbon tape which was attached to a SEM stub. The stubs were coated with a thin
layer of carbon by evaporative deposition under vacuum.
Sample ID AEFIBfl077 fRT Lee Croup Sample ID 609423^
Particle Type Comments Estimated Contribution*
C-rich Flakes, Cellulose Major
Si-rich Quartz Minor
Si/Al-rich Feldspar Trace
C-rich Plant Fragments Trace
C-rich Pollen Trace
C-rich Mold Trace
* Definitions for acronyms, "Estimated Contribution" and the elemental names for the symbols listed in this report
can be found on page 4,
G-16
Monroevilie, PA • San Leandro, CA • Washington, DC. ~ Houston, TX • Richland, WA
-------
Mr. Gaiy Gentry
RJ Lee Group Project No, AOW607044
July 15,1996
Page 2
The majority of the particulate on this filter was carbon-rich. These carbon-rich particles were
dominantly flakes with a morphology similar to that of skin (see Figure 1). Cellulose fibers
typically possessed lengths of less than 40 pm. Earth crustal materials such as quartz (see
Figure 2) and feldspar particles were less than 10 Jim in diameter. Carbon spheres of less than
3 Jim were observed in trace amounts and resembled mold.
Sample TP AEFIB0081 fRJ Lee Group Samnle ID 6094241
Particle Type , Comments Estimated Contribution
C-rich Flakes, Cellulose Major
Si/Al-rich Feldspar Moderate
Si-rich Quartz Minor
Ca-rich Trace
Carbonaceous particles composed the majority of this sample and earth crustal particles were found
in moderate concentrations in the less than 5 |im sized particles. Si-rich particles were less than
10 jim in size. Pollen and mold particles were not observed on this sample.
Sampie ID AEFIB0072 fRJ Lee Group Sample ID 609425^
Particle Type Comments Estimated Contribution
C-rich Flakes, Cellulose Major
Si/Al-rich Feldspar Minor
Si-rich Quartz Minor
C-rich Pollen Trace
C-rich Mold Trace
C/S/Ca-rich <3 fim Spherical Particles Trace
Ca/S-rich Trace
Fe-rich Trace
Al/P/Cl-rich Trace
The majority of this filter consisted of carbonaceous particles with a minor amount of earth crustal
particles (Si/Al-rich and Si-rich particle types).
Sample ID AEFIB0080 (R.T Lee Group Sample ID 609426)
Particle Tvpe
Comments
Estimated Contribution
C-rich
Flakes, Cellulose
Major
Si/Al-rich
Feldspar
Moderate
C-rich
Pollen
Trace
C-rich
Mold
Trace
C-rich
Possilble Toner Dust
Trace
Si/Mg-rich
Trace
Si/Ca-rich
Trace
Si-rich
Trace
Ca/Mg-rich
Trace
G-17
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW6O7044
My 15, 1996
Page 3
Carbon-rich particles were the major particle type observed on this filter and consisted dominantly
of flakes (see Figure 3). Feldspars were found in moderate concentrations and were less than
10 Jim in diameter. Nearly spherical pollen grains were in the less than 12 Jim particle fraction and
less than 5 |mi carbon-rich particles were molds (see Figure 4).
These results are submitted pursuant to RJ Lee Group's current terms and conditions of sale,
including the company's standard warranty and limitation of liability provisions. No responsibility
or liability is assumed for the manner in which the results are used or interpreted. Unless notified
in writing to return the samples covered by this report, RJ Lee Group will store the samples for a
period of thirty (30) days before discarding.
Should you have any questions regarding Ms information, please do not hesitate to contact John
Johns or me.
Steve Badger
Project Manager
Environments Services
SRB:dls
c: J. C. Johns
Sincerely,
G-18
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW607044
July 15, 1996
Page 4
Definitions
Acronyms
EDS Energy dispersive spectroscopy
MSEM Manual scanning electron microscopy
pm Micrometers
Chemical Elements
A1 Aluminum
C Carbon
Ca Calcium
CI Chlorine
Fe Iron
Mg Magnesium
P Phosphorous
S Sulfur
Si . Silicon
Estimated Contribution
Major Estimated to comprise > 40 percent of the sample by number
Moderate Estimated to comprise between 20 and 40 percent of the sample by number
Minor Estimated to comprise between 5 and 20 percent of the sample by number
Trace Estimated to comprise < 5 percent of the sample by number
G-19
-------
(U Lee Group Project No, AOW6O7044
0 12 3 ; 4^- 5 B 7 e . S 10 i
" '• ' "¦ _ ' ' ' --S
Figure 1
Figure 2
G-20
-------
RJ Lee Group Project No, AOW607044
Figure 4
G-21
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RJ LeeGroup, Inc.
1QQ, 350HochbergRoad • Monroeville, PA 15146
August /, iyy& 412/325-1776 . FAX 412/733-1799
Mr. Gary Gentry
Acurex Environmental, Inc.
P.O. Box 13109
Research Triangle Park, NC 27709
RE: Characterization of four polycarbonate filter samples
RJ Lee Group Project No. AOW607198
Dear Mr. Gentry:
Enclosed you will find a summary of the analytical results for the air samples that you recently sent
us (reference your Laboratory Request dated July 30, 1996). The samples were identified as
follows:
' Acurex Environmental Sample ID RJ Lee Orwp Sample JD
0097 609667
0100 609668
010E 609669
0109 609670
The purpose of this investigation was to characterize material collected on the polycarbonate filters
by manual scanning electron microscopy (MSEM). MSEM distinguishes among different particle
types based on morphology and elemental composition utilizing secondary electron imaging (SEI),
backscattered electron imaging (BEI) and energy dispersive spectroscopy (EDS). SEI is used to
obtain a three dimensional image of the specimen. In the BEI mode, higher atomic number
elements generate more backscattered electrons than do lower atomic number elements resulting in
a brighter image for heavier materials. Elemental composition of each species can be obtained
utilizing (EDS) techniques. Sample preparation involved mounting a portion of the filter onto an
SEM stub and coating it with a thin layer of carbon by evaporative deposition under vacuum.
Acurex Environmental. Inc. No. 0097 (RJ Lee Group Sample No.609667)
Particle Type Comments Estimated Contribution
C-rich flakes Skin Flakes Major
C-rich fibers Cellulose Minor
Si/Al-rich Earth Crustal (Feldspars and Clays) Minor
Si-rich Quartz Trace
Ca/S-rich Gypsum Trace
C-rich Wood Trace
K/Cl-rich Salt Trace
Fe-rich Trace
The majority of the particulate on the filter was carbon-rich particles. These particles were
dominantly skin flakes with diameters typically less than 50 microns and cellulose (see Figure 1).
Earth crustal particles were typically less than 15 microns in diameter. Ca/S-rich particles were
less than 5 microns in diameter and were likely gypsum, a common building material.
G-22
Monroevilie, PA • San Leandro, CA • Washington^ IXJ * Houston, TX • Richland, WA
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW607198
August 7,1996
Page 2
Acurex Environmental. Tne. No. 0100 (RJLee Group Sample No.609668)
Particle Type Comments Estimated Contribution
C-rich flakes
C-rieh fibers
Si/Al-rich
Si-rich
Ca-rich
Skin Hakes
Cellulose
Earth Crustal (Feldspar and Clay)
Quartz
Major
Minor
Minor
Trace
liace
The dominant particle types on this filter were skin flakes, cellulose, and earth crustal particles.
The skin flakes were typically less than 50 microns in diameter and earth crustal particles were less
than 15 microns in diameter. Trace amounts of pollen (12-15 micron diameters) were identified as
spherical carbon-rich particles.
Acurex Environmental. Inc. No. 0108 (RJ Lee Group Sample No. 609669)
Particle Type
Comments
Estimated Contribution
C-rich flakes
C-rich fibers
Si/Al-rich
Si/Mg-rich
Al/P/Cl-rich
Si-rich
Ca/S-rich
C-rich
Fe-rich
Skin Flakes
Cellulose
Earth Crustal (Feldspar and Clay)
Quartz
Gypsum
Pollens
Major
Minor
Minor
Minor
Minor
Trace
Trace
Trace
Trace
The particulate on this filter was dominantly skin flakes. Si/Mg-rich (Figure 2) and Al/P/Cl-rich
particles (Figure 3) were not found on the filters 0097 and 0100. Also, Al/P/Cl-rich particles were
not found on any of the other filters. The Si/Mg-rich particles were less than 30 microns in
diameter and the Al/P/Cl-rich particles were less than 15 microns in diameter. The origin the
Si/Mg-rich and Al/P/Cl-rich particles is unknown,
Acurex Environmental Inc. No. 0109 (RJLee Group Sample No.60967Q)
Particle Type Comments Estimated Contribution
C-rich flake Skin Flake Major
C-rich fiber Cellulose Minor
Si/Al-rich Earth Crustal (Feldspar and Clay) Minor
Si/Mg-rich Minor
Si-rich Quartz Trace
C-rich Pollen Trace
C-rich Mold Trace
Fe-rich Trace
The majority of this sample consisted of skin flakes. Si/Mg rich particles were less than 30
microns in diameter. Pollen particles (Figure 4) were 10 to 14 microns in diameter.
G-23
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW607198
August 7,1996
Page 3
These results are submitted pursuant to RJ Lee Group's current terms of sale, Including the
company's standard warranty and limitation of liability provisions and no responsibility or liability
is assumed for the manner in which the results are used or interpreted.
Should you have any questions regarding this information, please do not hesitate to contact me.
Sincerely,
Steve Badger
Project Manager
Environmental Services
SB:skd
Attachments
0-24
-------
RJ Lee Group No. AOW607I98
G-25
-------
351
Figure 3
1 2 3 4 5 6,7 8 8
Figure 4
G-26
-------
RJ Lee Group, Inc.
350 Hochberg Road « Monroe ville, PA 15146
412/325-1776 • FAX 412/733-1799
August 20,1996
Mr. Gary Gentry
Acurex Environmental, Inc.
P.O. Box 13109
Research Triangle Park, NC 27709
RE: Characterization of Four Polycarbonate Filter Samples
RJ Lee Group Project No. AOW608055
Dear Mr. Gentry:
Enclosed you will find a summary of the analytical results for the four air samples that you
recently sent us (reference your Laboratory Request dated August 6,1996). The samples
were identified as follows:
Acurex RJ Lee Group
Sample ID Sample Nq.
AEFTO0133 609689
AEF3B0125 609690
AEFIB0127 609691
AEEB0136 609692
The purpose of this investigation was to characterize material collected on the polycarbonate
filters by manual scanning electron microscopy (MSEM). MSEM distinguishes among
different particle types based on morphology and elemental composition utilizing secondary
electron imaging (SEI), backscattered electron imaging (BEI) and energy dispersive
spectroscopy (EDS). SEI is used to obtain a three dimensional image of the specimen. In
the BEI mode, higher atomic number elements generate more backscattered electrons than
do lower atomic number elements resulting in a brighter image for heavier materials.
Elemental composition of each species can be obtained utilizing (EDS) techniques. Sample
preparation involved mounting a portion of the filter onto an SEM stub and coating it with a
thin layer of carbon by evaporative deposition under vacuum.
Acurex Sample ID: AEFEB0133 (RJ Lee Group Sample No.609689)
Particle Tvpe
Comments Estimated Contribution
Si/Mg-rich flakes
Talc
Major
C-rich flakes
Skin flakes/animal dander
Moderate
Si/Al-rich particles
Earth crustal (feldspar & clays)
Minor
Si-rich fibers
Glass fibers
Trace
Ca/S-rich particles
Gypsum (<10 jtm)
Trace
Al/P/Cl-rich particles
<3|imin size
Trace
Ca-rich particles
<5 nm in size
Trace
Cu-rich particles
"<3 |um in size
Trace
Fe-rich particles
<5 |im in size
Trace
G-27
Monroe ville, PA « San Leandro, CA • Washington, OG « Houston, TX • Richland, WA
-------
Mr, Gary Gentry
RJ Lee Group Project No, AOW608055
August 20,1996
Page 2
The majority of the particulate matter detected on tills sample were Si/Mg-rich flakes
predominantly 10 to 20 pm in size. The element chemistry and flake-like morphology is
similar to that of talc (see Figure 1). A moderate amount of carbon-rich flakes with a size
ranging from 20 to 50 pm were observed and were identified as skin flakes/animal dander
(see Figure 2). Earth crastal particles were detected in minor amounts and were less than
10 pm in size.
Acurex Sample TP: AEFTB0125 Ml Lee Group Samnte No.60969m
Particle Type Comments Estimated Contribution
C-rich particles Skin flakes/animal dander Major
Si/Al-rich particles Earth crastal (feldspar & clays) Minor
C-rich particles Cellulose Minor
Si/Al-rich spheres Fly ash Trace
C-rich particles Pollen Trace
K/Cl-rich particles Salt Trace
Cr-rich particles -20 pa in size Trace
Fe-rich particles ~10 pm in size Trace
Ca/Si-rich particles ~5 pm in size Trace
Al/P/Cl-rich particles -10 pm in size Trace
Fe/Zn-rich particles ~5 pm in size Trace
The majority of the particulate matter associated with this sample were skin flakes/animal
dander with a size range from 10 to 80 jim. A minor amount of earth crastal material with
a size of less than 10 pm was detected. A minor amount of cellulose material was observed
and was approximately 20 to 30 pro in size.
Acurex Sample ID: AEFIB0127 (RJ Lee Group Sample No.609691)
Particle Type Comments Estimated Contribution
C-rich flakes Skin flakes/animal dander Moderate
Si/Al-rich particles Earth crustal (feldspar & clays) Moderate
C-rich particles Cellulose Minor
Cu-rich particles <1 pm in size Minor
C-rich particles Pollen Trace
Si-rich particles -10 pm in size .Trace
Ca-rich particles <5 pm in size Trace
Fe-rich particles <5 pm in size Trace
This sample contained a moderate amount of skin flakes/animal dander which ranged from
20 to 80 pm in size. A moderate amount of earth crastal material was also detected. These
particles were predominately less than 10 pm in size (see Figure 3). Cellulose fibers and
flakes of various sizes (possibly paper) were observed. A minor amount of copper-rich
particles with a somewhat spherical morphology and less than 1 pm in size were also
detected.
G-28
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW608055
August 20,1996
Page 3
Acurex Sample, TP: AEFTB0136 (R.J Is* Grout, Sample No.609692)
Particle Type
Si/Mg-rich flakes
C-rich flakes
Si/Al-rich particles
C-rich particles
Ca-rich particles
Cu-rich particles
Comments
Estimated Contribution
Talc Moderate
Skin flakes/animal dander Moderate
Earth crastal (feldspar & clays) Minor
Pollens Trace
-10 ^tm in size Trace
<1 pa in size Trace
The sample contained a moderate amount of Si/Mg-rich flakes with a size range of
JO to 30 jam. The flake-like morphology and elemental chemistry suggests talc particles.
Skin flakes/animal dander were also observed in moderate amounts ranging from 20 to 75
Mm in size.
These results are submitted pursuant to RJ Lee Group's current terms of sale, including the
company's standard warranty and limitation of liability provisions and no responsibility or
liability is assumed for the manner in which the results are used or interpreted.
Should you have any questions regarding this information, please do not hesitate to contact
Steve Badger or me.
Sincerely,
John C. Johns
Project Manager
Environmental Services
JCJ:dls
Attachments
G-29
-------
Mr. Gary Gentry
RJ Lee Group Project No. AOW608055
August 20,1996
Page 4
Acronyms
EDS
MSEM
juim
Definitions
Energy dispersive spectroscopy
Manual scanning electron microscopy
Micrometers
Chemical Elements
M
C
Ca
CI
Cr
Cu
Fe
K
Mg
p
S
Si
Zn
Aluminum
Carbon
Calcium
Chlorine
Chromium
Copper
Iron
Potassium
Magnesium
Phosphorus
Sulfur
Silicon
Zinc
Estimated Contribution
Major Estimated to comprise > 40 percent of.the sample by number
Moderate Estimated to comprise between 20 and 40 percent of the sample by number
Minor Estimated to comprise between 5 and 20 percent of the sample by number
Tfcace Estimated to comprise < 5 percent of the sample by number
G-30
-------
2700X *
-t 10.0 um
Si
200.
I*!"1-'' •y
-JL. -_,
0 1 2 3 4 5 6 7 8 9 10
Figure 1
G-31
-------
i
f
\
\C
2500x ¦ ' 10.0 urn
0 1 2 3 4 5 6 7 8 9 10
Figure 2
G-32
-------
6000X ^
* 5.0 cirn
Si
300.
Figure 3
G-33
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