.ugust 2lri4- | www.epa.gov/or
United States
Environmental Protection
Agency
Decontamination of a
Mock Office Using
Chlorine Dioxide Gas
Office of Research and Development
National Homeland Security Research Center
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EPA/600/R-14/208
August 2014
Decontamination of a Mock Office
Using Chlorine Dioxide Gas
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
11
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Disclaimer
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development's (ORD's) National Homeland Security Research Center (NHSRC), funded and
directed this work through Contract Number EP-C-09-027 with ARCADIS Inc. This report has
been peer and administratively reviewed and has been approved for publication as an EPA
document. The views expressed in this report are those of the authors and do not necessarily
reflect the views or policies of the Agency. Mention of trade names or commercial products does
not constitute endorsement or recommendation for use of a specific product.
Questions concerning this document or its application should be addressed to:
Joseph Wood
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Mail Code E343-06
Research Triangle Park, NC 27711
919-541-5029
in
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Acknowledgments
Contributions of the following individuals and organization to this report are gratefully
acknowledged:
United States Environmental Protection Agency (EPA)
Worth Calfee
Shawn Ryan
Peer reviewers
Marissa Mullins, EPA Office of Emergency Management
Eugene Rice, EPA Office of Research and Development, National Homeland Security
Research Center
Doris Betancourt, EPA Office of Research and Development, National Risk Management
Research Laboratory
ARCADIS
IV
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Executive Summary
The U.S. Environmental Protection Agency's (EPA's) Homeland Security Research Program
(HSRP) is helping protect human health and the environment from adverse impacts resulting
from the release of chemical, biological, or radiological agents. As part of the HSRP, EPA is
investigating the effectiveness and applicability of technologies for homeland security (HS)-
related applications. The purpose of this investigation was to determine the efficacy of using
relatively low levels of chlorine dioxide (CICh) gas for inactivating Bacillus anthracis (causative
agent for anthrax) surrogate spores in an office environment. Previous tests and actual
fumigations using high levels of CICh (e.g., 1000 - 3000 parts per million) have demonstrated its
efficaciousness, but the use of high CICh levels also comes with drawbacks such as issues with
material compatibility and generation technology capacity.
Demonstration of successful decontamination efficacy with CICh gas at concentrations lower
than what has been used previously would allow for a greater number of vendors to participate in
remediation efforts following a large anthrax spore release. That is, vendors with technologies
that produce CICh, but perhaps at relatively lower generation rates, would still be able to meet
the target fumigation concentration within a large building. The objective of this study was to
provide an understanding of the performance (i.e., efficacy) of low level CICh gas to guide its
use and implementation in HS applications for hard-to-decontaminate materials such as those
found in an office. In the assessment of options for decontamination following an intentional
release of B. anthracis spores, it is important to know what operational factors can impact the
decontamination efficacy.
This investigation initially focused on decontamination tests at bench scale using small coupons
inoculated with spores of B. subtilis and then fumigated inside a glove box. These small scale
tests were then followed by pilot-scale tests using a mock office set up within a large
decontamination chamber. Tests were conducted with varying operational parameters (e.g., CICh
concentration and contact time), to assess the effect of these parameters on decontamination
efficacy. Various types of microbiological assays were used extensively to characterize spore
levels before and after treatment with low level CICh, including surface sampling, biological
indicators (Bis), bioaerosol measurements, reference measurement coupons, and others.
Thirteen pilot-scale tests were conducted with spores of B. atrophaeus, a microorganism
previously verified as an appropriate surrogate for B. anthracis in CICh decontamination studies.
Spores were disseminated into the mock office as a dry powder. The effectiveness of the low
level C1O2 treatment was characterized in a number of ways, e.g., in terms of the number of
spores recovered from surfaces following decontamination; the number of samples in which
spores were not detected; and in terms of log reduction (LR). LR was determined based on the
difference between the number of bacterial spores (as colony forming units, or CPU) recovered
from the office before and after decontamination. In five of the tests, computers were included
within the mock office to assess the impact of low level CICh fumigation on sensitive electronics.
Summary of Results
Small scale tests
Tests were conducted in a glove box with CICh concentrations of either 100 or 200 ppm, with
contact times ranging from 2-12 hours. The coupon materials used were wood, concrete, carpet,
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painted drywall paper, and galvanized metal. The results showed that low level CICh fumigation
was effective (> 6 LR) for nearly every condition tested except for the wood coupons at 200 ppm
(although all LR results were greater than 5). In the majority of the tests, greater than 7 LR was
obtained and/or all spores were completely inactivated. In every test with concrete and painted
drywall paper, the spores were completely inactivated (no viable spores were detected), while for
wood, there were no tests in which spores were completely inactivated.
Mock office efficacy results
The majority of the mock office tests used relatively low levels of CIChgas (100-300 ppm),
although a few tests were conducted at 750 ppm or higher to allow for comparison of results
from previous studies. Contact times ranged from 3-24 hours. The RH was generally well
controlled, and with the exception of one test, ranged from 74-78 %. Actual average
temperatures for the tests ranged from 22-29 °C (72-84 °F).
The average spore loadings for the mock office, prior to decontamination, ranged from 4.89 -
7.21 log CPU/square foot (ft2; 77,625 - 16.2 million CFU/ft2). Overall average spore loadings for
the office following C1O2 treatment ranged from -0.01 to 2.24 log CFU/ft2 (1 - 174 CFU/ft2), and
generally correlated (0.62) with pre-decontamination spore loadings. The post-decontamination
spore loading correlation with pre-decontamination loading was apparent for specific surfaces
within the office, as well as for the average loadings for the entire office. For example, Test 4,
with only a 228 ppm CICh average level and 4 hour contact time, resulted in highest number of
post-decontamination surface samples in which no spores were detected (96%) for the study, but
also had the second lowest average office spore loading prior to decontamination. Post-
decontamination spore levels in the office air ranged from approximately 1 to 80 CFU/cubic
meter (m3). Additionally, post-decontamination average spore surface levels were well
correlated (0.74) with the post-decontamination spore levels in the air.
The study demonstrates that decontamination efficacy levels between 5 to > 6 LR are achievable
using relatively low levels of CICh, depending on the pre-decontamination spore levels and other
factors. While none of the mock office tests resulted in overall average office LR values of
greater than 6, there were several office tests in which spores were not detected from nearly all of
the surfaces sampled, with corresponding LR levels > 6. Although the results for the small scale
coupon tests are comparable to the mock office tests, it is difficult to make direct comparisons
for the two scales of testing. Differences in materials, spore deposition methods, spore loadings,
sampling procedures, surface sample size, etc., make direct comparisons difficult since these
could affect efficacy results.
Biological indicators (Bis) were one of the assays used to assess effectiveness of the
fumigation in inactivating bacterial spores. The Bis were comprised of nominally 106 spores of
B. atrophaeus inoculated onto stainless steel discs and wrapped in Tyvek envelopes. The Bis
were placed at five locations within the office and collected after fumigation and analyzed to
determine whether any of the Bis exhibited growth of bacteria, i.e., survival of any spores. The
results showed that every BI exposed to CICh in the mock office tests was inactivated. This
general result is consistent with other tests that have shown that the spore populations on Bis are
typically much easier to inactivate than spores associated with coupons from building materials
or actual environmental surfaces.
VI
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Impact on computer functionality
Fumigation at approximately 200 ppm CICh for 6 or 8 hours and at approximately 300 ppm
for 4 hours showed no measureable change in the function of the computers over the course of a
year.
Implications of study
The study has demonstrated the potential of using relatively low levels of CICh gas, accompanied
by longer contact times, for effective decontamination of surfaces and spaces contaminated by
anthrax spores. However, this decontamination approach may be better suited for areas that are
not heavily contaminated, i.e., that have spore loadings less than 5 log CFU/ft2 and/or that do not
contain significant quantities of porous materials such as carpet and wood. Further research is
recommended to find efficacious low concentration conditions for heavily contaminated surfaces
and for difficult to decontaminate materials.
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Contents
Disclaimer iii
Acknowledgments iiv
Executive Summary v
Abbreviations/Acronyms x
1.0 Introduction 1
2.0 Summary of Test Procedures 3
2.1 Small Scale Chamber Tests 3
2.2 Mock Office Procedures 4
3.0 Quality Assurance/Quality Control 12
3.1 Sampling, Monitoring, and Equipment Calibration 12
3.2 Acceptance Criteria for Critical Measurements 13
3.3 Data Quality 15
4.0 Results and Discussion 17
4.1 Small Scale Coupon Decontamination Results 17
4.2 Office Decontamination Results 18
4.3 Impacts on Computer Functionality 24
5.0 Summary and Conclusions 25
6.0 References 27
Appendix A. Detailed Microbiological and Decontamination Results 29
Appendix B. Detailed Analyses for PC Doctor Results 44
Figures
Figure 2-1 Photograph of Portion Of Mock Office Showing Furniture and Sample Grids 6
Figure 3-1 Field Blank (FB) Test Sample Results by Surface Sample 16
Figure B-l Average PC Doctor Score Over Time 47
Tables
Table 2-1 Summary of Sample Methods and Assays 7
Table 2-2 Sampled Material Surfaces for Mock Office Configuration 8
Table 3-1 Sampling and Monitoring Equipment Calibration Frequency 12
Table 3-2 Analysis Equipment Calibration Frequency 12
Table 3-3 Summary of QA/QC Checks 14
Table 4-1 Summary of Decontamination Efficacy Results for Small Chamber Tests 18
Table 4-2 Summary of Fumigation Conditions for Mock Office Tests 19
Table 4-3 Summary of Decontamination Results for Mock Office Tests 20
Table 4-4 Correlation of Fumigation Parameters and Decontamination Results 21
Table 4-5 Decontamination Results for Coupons Placed in Mock Office 23
Table 4-6 Total Computer "Fail" Results over Year-Long Test Period 24
Table A-l Test 3 Detailed Results 30
Table A-2 Test 5 Detailed Results 31
Table A-3 Test 4 Detailed Results 32
Table A-4 Test 6 Detailed Results 33
viii
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Table A-5 Test 14B Detailed Results 34
Table A-6 Test 8B Detailed Results 35
Table A-7 Test 16 Detailed Results 36
Table A-8 Test 11 Detailed Results 37
Table A-9 Test 13 Detailed Results 38
Table A-10 Test 17 Detailed Results 39
Table A-11 Test 15 Detailed Results 40
Table A-12 Test 18 Detailed Results 41
Table A-13 Test 19 Detailed Results 42
Table A-14 Detailed Coupon Efficacy Results 43
Table B-l PC Doctor Tests 44
Table B-2 Total Fail Results for Year Long Test Period 48
Table B-3 Total Fail Results with Pre-Existing Failures Removed 48
Table B-4 Vulnerable Subsystems 49
IX
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Abbreviations/Acronyms
AKA
ATCC
B. anthracis
B. atrophaeus
BI
BOTE
B. subtilis
°C
CPU
C1O2
cm
COMMANDER
DAS
ELPI
EPA
FB
ft
g
H2O2
HEPA
hr
HS
HSRP
L
LR
m3
mm
MDI
mg
min
mL
ND
NHSRC
ORD
PBST
PCI
ppm
QA
QAPP
QC
RH
RMC
Also known as
American Type Culture Collection
Bacillus anthracis (Ames strain)
Bacillus atrophaeus
Biological Indicator
Bio-Response Operational Testing and
Evaluation
Bacillus subtilis (ATCC 19659)
degree(s) Celsius
colony forming unit(s)
chlorine dioxide
centimeter(s)
Consequence Management and
Decontamination Evaluation Room
Digital Acquisition System
Electrical Low Pressure Impactor
U.S. Environmental Protection Agency
field blank
feet/foot
gram(s)
hydrogen peroxide
High efficiency particulate air
hour(s)
homeland security
Homeland Security Research Program
liter(s)
Logic reduction
cubic meter(s)
millimeter
Metered Dose Inhaler
milligram(s)
minute
milliliter(s)
microliter(s)
not detected
National Homeland Security Research
Center
Office of Research and Development
phosphate buffered saline with Tween
Peripheral Component Interconnect
part(s) per million
quality assurance
quality assurance project plan
quality control
relative humidity
Reference Material Coupon
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SCADA Supervisory Control and Data Acquisition
ISA Triptic Soy Agar
USB Universal Serial Bus
VHP® Vaporized Hydrogen Peroxide ®
XI
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1.0 Introduction
The U.S. Environmental Protection Agency's (EPA's) Homeland Security Research Program
(HSRP) is helping protect human health and the environment from adverse impacts resulting
from the release of chemical, biological, or radiological agents. With an emphasis on
decontamination and consequence management, water infrastructure protection, and threat and
consequence assessment, the HSRP is working to develop tools and information that will help
detect the intentional introduction of chemical or biological contaminants in buildings, water
systems, or the outdoor environment; contain these contaminants; decontaminate buildings,
water systems or the outdoor environment; and facilitate the treatment and disposal of materials
resulting from remediation activities. As part of the above effort, and in response to the needs of
the HSRP's Program Office partners, EPA investigates the effectiveness and applicability of
technologies for homeland security (HS)-related applications by developing test plans,
conducting tests, collecting and analyzing data, and preparing peer-reviewed reports. All
evaluations are conducted in accordance with quality assurance (QA) protocols to ensure that
data of known and high quality are generated.
In the event of a large urban release of B. anthracis spores, extensive resources would be
required in the recovery effort, and the number of private decontamination contractors available
may not be sufficient to respond to the decontamination needs (Krauter and Tucker 2011).
Chlorine dioxide (CICh) fumigation was used to decontaminate four buildings following the
Amerithrax incident (Canter 2005), and has been identified as an option for the decontamination
of large indoor civilian areas following an aerosol release of B. anthracis spores over a wide
urban area (Campbell et al. 2012). But because CICh gas concentrations at 10% or above tend to
be unstable, and attempts to store the gas in compressed form have been unsuccessful, it must be
generated at the point of use (Wood and Martin 2009).
A primary factor affecting the feasibility of using CICh fumigation to successfully decontaminate
a large building contaminated with B. anthracis spores is the target CICh concentration. The
C1O2 generation technology must be capable of producing CICh at a high enough rate to achieve
the relatively high target concentration in the structure within a reasonable amount of time, while
overcoming the loss of gaseous CICh due to building air leakage and withdrawal, material
demand, and chemical decomposition (US EPA 2008). For example, it was determined in a field
study that a CICh generation rate of- 54 kg/hr would be needed to achieve 1,500 ppm CICh in a
9,900 m3 building (Wood and Martin 2009). With this in mind, there may be only a few
companies in the US with the technology capable of generating CICh at such high rates.
Historically, CICh fumigation for decontamination of buildings contaminated with B. anthracis
spores has been performed with relatively high levels of CICh. Following the Amerithrax
incident, three of the four anthrax contaminated buildings that were fumigated with CICh were
done so using a target CICh concentration of 750 ppm, with a dwell time of 12 hours (US EPA
2005), while the fourth building (American Media Inc., located in FL) was fumigated at 3000
ppm for 3 hours (US EPA 2012 A). Fumigating with CICh at 3000 ppm for 3 hours was also
used at the full-scale Bio-Response Operational Testing and Evaluation (BOTE) field test (US
EPA 2013). Further, many laboratory (bench-scale) studies reported in the peer reviewed
literature on the sporicidal efficacy of C1O2 gas have been conducted with C1O2 at levels
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typically around 1000 ppm or higher; see for example Rastogi et al. (2009); Jeng and
Woodworth (1990); and Han et al. (2003).
In contrast, the study presented in this report focused primarily on using CICh at relatively low
concentrations but with longer contact times. Demonstration of successful decontamination
efficacy with CICh gas at concentrations lower than what has been used previously would allow
for a greater number of vendors to participate in remediation efforts following a large anthrax
spore release. That is, vendors with technologies that produce CICh, but perhaps at relatively
lower generation rates, would still be able to meet the target fumigation concentration within a
large building. Lower levels of CICh gas would also presumably have less detrimental impacts
on materials.
This investigation focused initially on proof of concept decontamination tests at bench scale
using small coupons placed inside a small chamber (modified glovebox). Six tests were
conducted, using target CICh concentrations of either 100 or 200 ppm, with contact times ranging
from 2-12 hours. The coupon materials used included wood, concrete, carpet, painted drywall
paper, and galvanized metal.
These small scale tests were then followed by pilot-scale tests using a mock office set-up in a
large decontamination chamber. The majority of the mock office tests used relatively low levels
of CIChgas (100-300 ppm), although a few tests were conducted at 750 ppm or higher to allow
for comparison of results from previous studies. The mock office tests involved extensive
surface sampling and other microbiological assays. A portion of the mock office tests included
the use of computers to assess the impact of low level CICh fumigation on sensitive electronics.
Some of the mock office tests (during the latter portion of the study) also included the use of
small coupons of different materials, to compare decontamination efficacy results between the
coupons and surfaces within the office.
Decontamination efficacy tests were conducted with spores of Bacillus subtilis in the small scale
tests, and with B. atrophaeus (a variant of B. subtilis) in the pilot-scale tests. Both
microorganisms have been demonstrated as appropriate surrogates for B. anthracis in
decontamination studies using C1O2 gas (US EPA 2012B; US EPA 2013).
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2.0 Summary of Test Procedures
2.1 Small-Scale Chamber Tests
Decontamination tests with CICh gas were first conducted at small scale in an opaque exposure
chamber (317 L) (Model 830-ABC, Plas-Labs, Inc., Lansing, MI), modified to maintain and
control a leak-free fumigation atmosphere inside the exposure chamber, and to allow for the
periodic addition and removal of coupons during fumigation.
Chlorine dioxide was generated using a ClorDiSys GMP CICh generator and first routed to a
mixing chamber to maintain a CICh level at 750 ppm. When the concentration in the exposure
chamber was below the set-point (e.g., 100 or 200 ppm), a solenoid valve directed the 750 ppm
C1O2 gas from the mixing chamber into the exposure chamber. Relative humidity (RH) inside
the exposure chamber was controlled by a custom-built data acquisition system (DAS), using a
Vaisala RH/temperature sensor (Model HMD40Y; Helsinki, Finland) to provide a signal used in
a feedback loop. Humid air was supplied as needed using a gas humidity bottle (Fuel Cell
Technologies, Inc. Model LF-HBA, Albuquerque, NM) heated to 140 °F. Temperature was
controlled if necessary by circulation of cooling water through radiators located within the
exposure chamber. A fan was used inside the exposure chamber to provide internal mixing.
Additional details on the CICh generator and measurements, and temperature and RH
measurements, are presented below in Section 2.2 as well as in another reference (Wood et al.
2010).
Spores of Bacillus subtilis were used in the small scale tests as a surrogate for B. anthracis (US
EPA 2012B), and were applied to small coupons (18 mm diameter) as an aerosol using a metered
dose inhaler (MDI) provided by the Edgewood Chemical and Biological Center. The coupons
were made from wood, concrete, carpet, painted dry wall paper, and galvanized metal. Further
details on the spores, the MDI deposition method, coupons, and the spore extraction and
counting methods are described elsewhere (Lee et al. 2011). The target dose for each coupon
was 107 to 108 colony forming units (CFU).
Six small-scale fumigation tests were conducted as follows: (1) place the appropriate coupons for
the test in the exposure chamber and seal the chamber airlock; (2) establish the target
temperature (24 ± 2°C) and RH (75± 5 %); (3) charge the chamber with CICh to achieve the
target concentration (either 100 or 200 ppm ± 10 % of target value); (4) maintain the target
concentration, temperature, and RH for the specified time (note: time zero is defined as the time
at which the target concentration was achieved in the chamber); (5) aerate the chamber for a
defined length of time and until a safe CICh concentration is achieved in the chamber; and (6)
open the chamber and remove the coupons, placing them in the appropriate sample packaging
containers. Coupons were also removed through the airlock (without affecting the chamber
conditions) at intermittent time points in the fumigation cycle.
One Petri dish was used to contain a stainless steel stage holding a negative (blank) coupon and
five replicate coupons for each material and time point. The Petri dish was transferred to the test
chamber, and the cover was removed to allow exposure. Once a given time point was reached,
the dish was transferred out of the chamber using the air lock. The decontaminated coupons
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were then returned to the Biocontaminant Laboratory for analysis as soon as possible. Test
coupon CPU quantification and decontamination efficacy were determined as described by
Meyer et al. (2013). Briefly, efficacy for the small coupon tests is reported in terms of logio
reduction (LR), and was calculated as the mean of the logio CPU counts for the control coupons
minus the mean of the logio CPU counts for the test coupons.
2.2 Mock Office Procedures
2.2.1 Biological Agent and Dissemination
The test organism for the mock office study was Bacillus atrophaeus (American Type Culture
Collection (ATCC) 9372), in a dry spore form mixed with silicon dioxide particles (e.g., as a
powder). B. atrophaeus was formerly known as B. subtilis var niger and also Bacillus globigii,
and was used as a surrogate for B. anthracis in all three decontamination test rounds (including
C1O2 fumigation) in Phase 1 of the BOTE study (US EPA 2013). The bacterial spores were
obtained from the U.S. Army Dugway Proving Grounds, and prepared by Dugway as reported in
Brown et al. (2007A).
For each experiment, spores were released into the large decontamination chamber using ~ 0.2 g
of the preparation, or approximately 2.0 x 1010 CPU. Ten L/min of clean, dry air was supplied to
a fluidized bed aerosol generator (TSI Inc., Model 3400A, Shoreview, MN) loaded with the
spore preparation, and run for 30-60 minutes. An Electrical Low Pressure Impactor (Model
ELPI, Dekati, Ltd., Tampere, Finland) was used to monitor aerosol levels in the chamber in real
time, to ensure proper functionality of the aerosol generator, bacterial spore release, and the
deposition process. The fluidized bed was placed on a small table 1.27 m off the floor in the
chamber, between two large mixing fans, and a perforated diffusion shield was placed over the
fluidized bed to ensure uniform aerosol dissemination. Following release, the spores were
allowed to settle overnight onto mock office surfaces within the decontamination chamber.
2.2.2 Decontamination chamber and test environment
All tests were conducted in the COnsequence MANagement and Decontamination Evaluation
Room, or COMMANDER. COMMANDER consists of a stainless steel-lined inner chamber
built specifically for decontamination testing, with internal dimensions of approximately 3.4 m
wide, 2.5 m deep, and 2.8 m high. At the entrance to the chamber is an airlock compartment,
and enclosing the chamber and airlock is an exterior steel shell. All three components are kept
under cascading slight negative pressure (most negative within the inner chamber) with the use
of separate air streams with valve controls on the inlet and outlet of each. Air entering the
decontamination chamber passes through a high efficiency particulate air (FtEPA) filter, and
exhaust air from the decontamination chamber is ducted to an activated carbon bed and HEPA
filter prior to release to the facility exhaust system. Fans were used inside the chamber to
provide internal mixing during fumigation. The inner chamber inlet and outlet duct fans were
turned off during fumigation, and the inlet duct valve was closed, but the outlet valve was left
open to maintain a negative pressure inside the chamber. Further details and a diagram of
COMMANDER can be found elsewhere (Wood et al. 2013).
Within the chamber, temperature, RH, air pressures, flow rates, and air duct valves are controlled
and/or their data logged continuously using a supervisory control and data acquisition (SCADA)
system. The RH and temperature within the decontamination chamber were measured with a
4
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temperature and RH transmitter (Vaisala Inc., Model HMD40Y; Helsinki, Finland). This
instrument was calibrated prior to each test by comparing its RH data with known RH values
generated in the sealed headspace above individual saturated solutions of various salt
compounds. The RH meters were replaced if calibration criteria could not be met. Temperature
within the chamber was monitored but not controlled, and varied from 25-30 °C. The target RH
for all tests was 75%; the chamber RH was increased as needed through the use of a custom-
fabricated steam injection unit.
The test chamber facility is equipped with a vaporous hydrogen peroxide (VHP®) generator
(STERIS Corporation, Model 1000 ED, Mentor, OH), and was used to sterilize (i.e., reset) the
chamber and airlock prior to each test. The reset fumigation was typically conducted using a
hydrogen peroxide (EbCh) concentration of 250-400 ppm for 4-6 hours. Hydrogen peroxide
levels within the chamber were measured with an electrochemical sensor (Model B12, Analytical
Technology Inc., Collegeville, PA, USA). This sensor is connected to the SCADA and used to
verify that sterilization cycle conditions were met, and that after chamber aeration, levels are low
enough for reentry.
2.2.3 Mock office description
The stainless steel surfaces of the decontamination chamber were covered by materials typical of
an indoor office setting. The floor was covered with plywood and then industrial carpet tiles
(Beaulieu Solutions, P/N 6579-8586-1200-AB). The rear and side walls were framed and faced
with 1.27 cm thick drywall (GoldBond, P/N GB4080-0800). The drywall was patched with joint
compound (USG Sheetrock, P/N 380119048) and joint tape (USG Sheetrock, P/N 382199010)
according to typical building practices, then primed (Kilz, P/N 20005) and painted (Behr, P/N
105001). At the top of the walls, a drop ceiling was installed and consisted of acoustic ceiling tile
panels (Armstrong, P/N SCI 135c) and two plenum grilles to enable conditioning of the interior
chamber air using the existing RH and temperature controls. The chamber was furnished with
office equipment consisting of a laminated desk, an office chair, a file cabinet, pin cushion
screen, books/catalogues, and a computer with monitor and keyboard. See Figure 2-1 for a
photograph of a corner of the office, showing furniture and sample grid markings.
2.2.4 ClOi generation and measurement methods
Chlorine dioxide was generated using a Model GMP (ClorDiSys, Lebanon, NJ). The generator
passes 2 percent chlorine gas in nitrogen through cartridges containing solid sodium chlorite and
other proprietary ingredients. The system includes a photometric detector for continuous
measurement (a data point collected every 10 sec) of CICh, and a feedback loop is used to
maintain the chamber at the set-point concentration. The generator was located inside the airlock
during operation but had a gas sampling line to withdraw air samples from the center of the
interior chamber. Chlorine dioxide levels within the chamber as measured by the generator were
verified using a wet chemistry method, with gas samples collected every 120 min and routed to
impingers containing a solution of potassium iodide phosphate buffer. This impinger liquid was
then analyzed for CICh via titration with sodium thiosulfate. Additional details on the
generation and measurement methods are described elsewhere (Wood et al. 2010).
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Figure 2-1. Photograph of Portion of Mock Office Showing Furniture and Sample Grids
2.2.5 Test sequence
The general sequence of events for each test was as follows:
1. Target surfaces and equipment were arranged in the chamber as needed and the chamber
airlock was sealed.
2. The decontamination chamber was reset using a hydrogen peroxide vapor decontamination
cycle, then aerated.
3. The chamber was entered and surfaces sampled to determine background levels of any
residual contamination; these samples are referred to as field blanks (FB) or "reset" levels.
(Bacterial spore sampling and analytical methods discussed below.)
4. B. atrophaeus spores were then disseminated into the chamber/mock office using the
fluidized bed aerosol deposition technique and allowed to settle overnight.
5. The chamber was entered a second time and surfaces sampled to determine the initial levels
of spores (positive controls).
6. Temperature monitoring began and 75% RH was established within the chamber.
7. The chamber was charged with CICh to achieve the target concentration.
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8. The target concentration and RH were maintained for the specified contact time (Note: Time
zero is defined as the time at which the target concentration was achieved in the chamber.).
9. The chamber was aerated until CICh concentration was below 0.5 ppm in the chamber.
10. The chamber was entered a third time and sampled after fumigation (test samples).
2.2.6 Bacterial spore sampling and analysis
Numerous microbiological samples and assays were used to characterize bacterial spore presence
or absence in the mock office for each experiment (115 total for each test). Samples were
collected following the reset, dissemination of spores, and post-decontamination with CICh.
Samples or assays were either quantitative (providing a numerical result) or qualitative
(indicating either presence or absence of bacterial growth). The use of material coupons began
about halfway through the study. Laboratory blanks of items such as growth media and sampling
materials were also employed in each experiment to check for aseptic conditions. A summary of
the number and type of samples/assays for each experiment is shown in Table 2-1. Each sample
or assay is further described in the narrative below.
Table 2-1. Summary of Sample Methods and Assays
Sample or Assay type
Surface sampling with wipes or
"vacuum socks"
Surface sampling with swabs
Air samples
Reference measurement coupons
Biological indicators
Material coupons
Total
# samples
post reset
(field blanks)
10
1
3
14
# samples post
dissemination of
spores (positive
controls)
25
1
1
6
3
12
48
# samples post
decontamination
25
3
1
1
5
18
53
Bacterial spore samples were collected from surfaces with methods based on the use of wipes,
swabs, or hand-held vacuums equipped with a collection sock (referred to as "vacuum sock").
The wipe and vacuum sock samples were extracted and the recovered viable spores were
quantified, while the swab samples were analyzed qualitatively for growth. A summary of the
surfaces sampled within the mock office and method used is listed in Table 2-2 below. A total of
25 quantitative surface samples were collected in the office to characterize the spore loading
(positive controls), and a total of 25 quantitative samples taken after CICh decontamination (test
samples). A total of 10 field blank samples were collected for each test as well (one wipe or
vacuum sock sample for each surface). The selection of sampling method for each surface type
was based on previous spore sampling studies (Brown et al. 2007A; Brown et al. 2007B; Brown
et al 2007C.
-------
Table 2-2. Sampled Material Surfaces for Mock Office Configuration
Material Surface
Keyboard
Carpet
Ceiling Tile
Office Chair Seat
Office Chair back
Catalog
Pin cushion screen
Desk Table
Filing cabinet
Painted Drywall
Electrical socket
faceplate
Computer chassis
Keyboard
Sample
technique
Vacuum sock
Vacuum sock
Vacuum sock
Vacuum sock
Vacuum sock
Vacuum sock
Vacuum sock
Wipe
Wipe
Wipe
Swab
Swab
Swab
Surface area
per sample
(cm2)
564
929
929
465
465
97
929
929
1022
929
NA
NA
NA
Number of
positive
controls and
post-decon
samples per
test
1
5
3
2
2
1
3
2
1
5
1
1*
1*
Number of
field blanks
1
1
1
1
1
1
1
1
1
1
0
0
0
*The computer chassis and keyboard were swab sampled only following decontamination; NA = not applicable
The sampling locations for the wall, table, ceiling, and floor were determined using a grid
approach (e.g., sample template), similar to the method as described in Wood et al. (2013).
Smaller or larger size templates were used for the sampling of other surfaces to ensure a
consistent sample size. Wipe samples were collected using c. 26 cm2 gauze wipes (Kendall #
8402; Covidien, Inc., Mansfield, MA, USA); further details on the wipe pattern, wetting agent,
and procedures for extraction of spores from the wipes can be found elsewhere (Calfee et al.
2012). Vacuum sock sampling (sock filtration kit (Midwest Filtration, p/n FAB-20-01-001 A;
Model Omega, Atrix International, Inc., Burnsville, MN) and methods used to extract spores
from vacuum socks followed protocols outlined by Brown et al. (2007C).
Following spore extraction procedures, the liquid solution used to extract spores from each wipe
or vacuum sock sample was 10-fold serially diluted and plated. When fewer than 30 CFU were
detected on plates from undiluted extract, a portion of the remaining extraction solution was
filter plated using one or two larger volumes of the extract. Plates were incubated for 18-24
hours at 35 ± 2 °C, and then colonies were counted. Further details on these laboratory analysis
and plating techniques are described elsewhere (Calfee et al. 2012).
Total recovery (CFU quantity) for a surface sample was then calculated using equation 2-1.
Briefly, the average number of colonies for the triplicate plates is multiplied by the reciprocal of
the dilution (for which CFU counts that ranged between 30-300); then dividing by the plated
volume (0.1 mL for standard plating, or the volume(s) of extraction liquid that was filter plated,
-------
typically between 1-9 mL); and then multiplying by the total volume of the liquid used to extract
spores from wipe or sock sample (typically 10 mL). The CPU loading for a particular sample
was adjusted for the surface area sampled to arrive at a CPU count per square foot. When a filter
plate for a particular post-decontamination (or blank) sample had no CPU detected, a CPU value
of 0.5 CPU count was assigned to the filter. As an example, if no spores were detected on a filter
from a sample in which 4 mL (out of 10 mL total extraction liquid) were filter plated, the sample
itself would be assigned a value of 1.25 CPU.
CPU/unit area = (C/I)*D*V/A (2-1)
Where:
C = Counts per plate;
/ = Volume of solution plated (mL);
D = Dilution factor (e.g., 1000 for a 1000:1 dilution, or 1 for filter plate);
V = Volume of extraction solution (mL): and
A = Area sampled
One swab sample was collected from the electrical socket faceplate following spore
dissemination (prior to decontamination), as a positive control. Three swab samples were
collected in the office following decontamination: the electrical socket face plate, computer
chassis, and keyboard. Swab samples were used due to the complexity of the surface and were
collected following protocols by the US Centers for Disease Control and Prevention (2012) using
Bactiswabs™ (Remel, Lenexa, KS). The swab samples were used to evaluate only the presence
or absence of spores before and after decontamination. Following the collection of sample, each
swab was then streak plated on a TSA plate and incubated at a 35 °C ± 2 °C for at least 18 hours
and checked for growth of the target organism.
Reference material coupons (RMCs) were also used to determine spore deposition, but without
the need for surface sampling. The RMCs were 50 mm x 25 mm pre-sterilized rectangles of
stainless steel placed throughout the chamber, with spores recovered from the RMCs directly by
extraction in 50 mL conical vials (to avoid any bias from sampling methods). The RMCs were
placed at six locations within the office: on the keyboard, in the center of the chair, on top of the
filing cabinet, in the corner of the floor, and on a wall. Two RMCs were placed inside the
computer chassis, with one recovered before and one RMC recovered after fumigation. The
RMCs have a dog ear, which points up on the outward- facing surface, to allow for aseptic pick
up. RMC CPU loadings were quantified using the same techniques as described for the small
coupons in Section 2.1.
The presence of aerosolized spores in the chamber was measured using a ViaCell (Zephon,
Ocala, PL, USA) bioaerosol collection cassette, sampling at a rate of 15 L/min. An air sample
was taken during surface sampling operations. Air sampling typically lasted for two hours; air
samples were withdrawn near the center of the mock office. Further details on this method and
analysis are found elsewhere (Calfee et al. 2012). Results for this type of sample are presented
in CFU/m3 air.
-------
Bis were another assay used to assess effectiveness of the CICh fumigation in inactivating
bacterial spores. The Bis were comprised of nominally 106 spores of B. atrophaeus inoculated
onto stainless steel discs, and wrapped in Tyvek envelopes. The Bis were obtained from Mesa
Labs (Model 1-61 COST, Lakewood, CO) and placed inside the computer chassis, inside the filing
cabinet, on the pincushion screen, on the carpet floor, and on the desk table following positive
control sampling. The five test Bis were collected after fumigation and analyzed according to
manufacturer instructions to determine whether any of the Bis exhibited growth of bacteria
(survival of any spores). Three positive control Bis (not exposed to CICh) were also used in each
test.
During the latter half of the study, the mock office tests included the use of small coupons so that
results for the coupons could be compared to efficacy results based on surface sampling data
within the office, as well as the small chamber coupon data. Coupons were made from ceiling
tile, carpet, and painted wallboard paper. The 18 mm material coupons were inoculated with B.
atrophaeus with MDIs using the methods described in Section 2.1 of this report. Two inoculum
levels, roughly IxlO4 and 1 x 107 CPU per coupon, were used. One inoculated coupon per
target inoculum level and one sterile coupon of each material type were placed in three different
locations inside COMMANDER following positive control office sampling. Thus a total of 18
test coupons were used for each experiment (3 materials x 3 office locations x 2 inoculum
levels). Two coupons, inoculated first and last, of each inoculum and material type, were not
fumigated and served as positive controls. The CPU levels on the coupons were quantified as
described in Section 2.1
2.2.7 Spore deposition and decontamination efficacy characterization
Spore deposition (i.e., pre-decontamination, positive control spore levels) was quantified by
taking the logarithm 10 of the CPU count for each wipe or vacuum sample (on a square foot
basis), and then calculating the mean and standard deviation of the log values (the mean of a
series of log values is equivalent to the log of the geometric mean for the same series) is for the
pre-decontamination samples for each particular location. Post-decontamination results are
presented in terms of spore recovery as well, and were calculated in the same manner as the pre-
decontamination results. Results are also presented in terms of decontamination efficacy, which
was quantified in terms of LR. The LR was calculated as the mean of the log values for each
positive control sample location CPU count minus the mean of the log values for each test
sample location CPU count. We occasionally report results by noting whether the average LR
for a particular coupon or surface test is > 6.0, since a decontaminant that achieves > 6 LR is
considered effective as a sporicidal decontaminant (US EPA 2010). We note, however, that
while a decontamination efficacy > 6 LR may be considered "effective" when reporting test
results, in an actual B. anthracis release event, the goal for decontamination would be to
minimize the number of recoverable spores, regardless of LR. Hence we also report results in
terms of the number of samples in which spores were not detected, discussed next.
When a filter plate for a particular post-decontamination (or blank) sample had no CPU detected,
the sample was scored qualitatively as "non-detect" (ND). The number of post-decontamination
surface samples (out of 25 for a given COMMANDER test) that were found to have no spores
detected is reported in the Results section. This approach also characterizes the effectiveness of
the C1O2 treatment, consistent with previous decontamination studies (US EPA 2013). When no
spores were detected for a sample, this result implied the highest decontamination efficacy
10
-------
quantifiable and achievable, and the LR was reported as > the positive control recovery minus
the recovery from the test sample (calculated based on imputing a 0.5 CPU value on the filter
plate, and adjusting for the filter plate volume; see Sub-section 2.2.6).
2.2.8 Procedures for Assessing Impact of ClOi on Computer Operation
For five fumigation tests, three additional computers were installed in the mock office to assess
the impact of low level CICh fumigation on the functionality of the computers. The computer
equipment used and tested included a Dell OptiPlex 780 Desktop Computer; a Dell 21.5 inch
Flat Panel Monitor; a USB keyboard and mouse; and computer and monitor power cords and
connecting analog video cable. Three computers were on and idle in each of the five tests.
Three positive control computers (not exposed to CICh) were also evaluated for functionality.
Before and after fumigation, computer functionality was evaluated using a software diagnostic
tool to determine the number of computer component failures. The post-fumigation analysis was
conducted monthly for a period of one year following the fumigation date. During the one year
period, all equipment was stored in an indoor office/laboratory environment with logged
temperature and RH. A 5 day, 8-hour workweek was simulated by load-testing software (Burnln
Test, Passmark Software Pty Ltd.) for the computer systems between evaluations. Refer to
Appendix B for further details on the methods used to assess computer functionality.
11
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3.0 Quality Assurance/Quality Control
Quality assurance/quality control (QC) procedures were performed in accordance with the
Quality Management Plan (QMP) and the test/QA Plan. The QA/QC procedures and results are
summarized below.
3.1 Sampling, Monitoring, and Equipment Calibration
Approved operating procedures were used for the maintenance and calibration of all laboratory
equipment. All equipment was verified as being certified calibrated or having the calibration
validated by the EPA's Metrology Laboratory at the time of use. Standard laboratory equipment
such as balances, pH meters, biological safety cabinets and incubators were routinely monitored
for proper performance. Calibration of instruments was done at the frequency shown in Tables 3-
1 and 3-2. Any deficiencies were noted. Any deficient instrument was adjusted to meet
calibration tolerances and recalibrated within 24 hours. If tolerances were not met after
recalibration, additional corrective action was taken, possibly including recalibration or/and
replacement of the equipment.
Table 3-1. Sampling and Monitoring Equipment Calibration Frequency
Equipment
Calibration/Certification
Expected Tolerance
Meter box
Volume of gas is compared to NIST-
traceable dry gas meter annually
±2%
Flow meter
Calibration using a flow hood and a
Shortridge manometer
±5%
RH and temperature
sensor
Compare RH to 3 calibration salts once a
week; thermistor (for temperature) part of
RH sensor and calibrated by manufacturer
±5%
Stopwatch
Compare against NIST Official U.S. time at ±1 min/30 days
http://nist.time.gov/timezone.cgi?Eastern/d/-
5/java once every 30 days
12
-------
Table 3-2. Analysis Equipment Calibration Frequency
Equipment
Pipettes
Incubator
Thermometers
Scale
Calibration
Frequency
Annually
Annually
Before each
use
Calibration
Method
Gravimetric
Compared to NIST-
traceable
thermometer
Compared to Class
S weights
Responsible
Party
External
Contractor
Metrology
Laboratory
Laboratory staff
Acceptance
Criteria
± 1 % target
value
±0.2°C
±0.01 % target
3.2 Acceptance Criteria for Critical Measurements
QA/QC checks associated with this project were established in the QAPP. A summary of these
checks is provided in Table 3-3.
13
-------
Table 3-3. Summary of QA/QC
Matrix
C1O2
measurement
Negative Test
Coupon
Samples
(swabs, wipe,
or vacuum
sock)
Negative
Material
Coupon
Samples
(swabs, wipe,
or vacuum
sock)
Positive Test
Coupon
Samples
(swabs, wipe,
or vacuum
sock)
Test Coupon
Samples
(wipe or
vacuum sock)
Chamber RH
Control
Computers
Measurement
Wet
chemistry
impinger
method
CPU
CPU
CPU
CPU
RH
Computer
functionality
per
PC-Doctor®
Checks
QA/QC Check
Validation of
generator
reading
Field Blank
Biocontaminant
Material Blanks
ofPBST*,
dilution tubes,
and plating
beads
(check that
plating materials
are not
contaminated)
Positive Controls
(inoculated w/
spores, but not
subject to any
treatment)
Agreement of
triplicate plates
of single coupon
at each dilution
2-point
calibration
Act as a baseline
for comparison
of fumigated
computers
Frequency
Once per
hour
One per
sample type
per
sampling
event
3 per each
material
used, daily
Up to 5 per
material per
test
Each
sample
Once per
day
In triplicate,
monthly
Acceptance
Criteria
±35% of
generator
reading
OCFU
OCFU
5E6 to 5E7
CFU
Each CFU
count must
be within
100% of
the other
two
replicates
±5%
NA
Corrective
Action
Change
generator
cartridges if
necessary
Revise
handling
procedures;
investigate
for sources of
contamination
Investigate
sterilization
procedure;
investigate
sources of
contamination
Assess
deposition or
sampling
protocol
Replate or
filter samples
Replace
Vaisala
sensor
NA
* Phosphate Buffered Saline with Tween® 20.
14
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3.3 Data Quality
Temperature and RH measurement devices were maintained within the calibration tolerances
found in Table 3-1. Fumigant concentrations were sampled using impingers and the impinger
liquid was analyzed using wet chemistry techniques. These values were all within the acceptance
criterion ±35 % of C1O2 generator readings.
Designated surfaces were sampled prior to biological exposure to test the effectiveness of the
reset. Figure 3-1 shows the total number of occurrences each sample surface/location showed B.
atrophaeus CFU or non-target contamination prior to spore dissemination (after reset) for the
entire test matrix of 13 tests. (Non-target contamination, when present, was typically white,
glossy colonies easily distinguishable from the orange colored B. atrophaeus colonies.) With the
exception of the filing cabinet and pin cushion, all test surfaces had a non-zero negative sample
at least once during the project. Refer to Appendix A for further information regarding which
surface(s) for each test were found to have target spores present following the reset.
For the majority of tests there was either no contamination found or only one surface was found
to have target spores present following the reset. The maximum number of surfaces that were
positive following the reset was four, which occurred in Test 11. In most cases in which surfaces
were positive for spores following the reset, the actual number of spores detected per sample was
less than 5 CFU using filter plating techniques.
Although the intention was to minimize the presence of contamination from the field blanks after
reset, the levels are considered minor and not expected to impact results of the study. Spores
present in the sampling field after sterilization could be indicative of cross-contamination during
sampling, confounding post-fumigation results of the same order of magnitude. However, most
likely they could be representative of an inadequate sterilization cycle. Once we switched to a
more robust reset cycle (400 ppm for 6 hours) for use in the latter half of the study,
contamination generally decreased.
15
-------
Negative Test Coupon Samples
18. atrophaeui
i Contamination
Figure 3-1. Field Blank Test Sample Results by Surface Sample
16
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4.0 Results and Discussion
4.1 Small Scale Coupon Decontamination Results
A summary of the results (in terms of LR) for the small scale coupon tests is shown in Table 4-1.
Contact times for the fumigations ranged from 2 to 12 hours.
Fumigation with CICh was effective (> 6 LR) for nearly every condition tested except for the
wood coupons at 200 ppm (all contact times), and galvanized metal at 100 ppm, 2 hours. (For
wood coupons at the 200 ppm condition, average surface loadings of detectable viable spores
were reduced by a minimum of 5 log CFU as a result of the decontamination process.) In the
majority of the small coupon tests, spore loadings were reduced by more than 7 log. For
example, in every test with concrete and painted drywall paper, the spores were completely
inactivated, while for wood there were no tests in which the spore population was completely
inactivated.
We note that in some cases, a higher dosage of CICh resulted in an ostensibly lower LR result for
the same material. For example, the LR for wood at 100 ppm, 8 hours (800 ppm-hour dose) was
6.61, while the LR at 200 ppm for 6 hours (1,200 ppm-hour dose) was 5.23. While appearing to
have a higher LR at a lower dose, the results are not significantly different (MS Excel t-test). For
this case, the lack of statistical significance may be due to the relatively variable results obtained
for wood (compare standard deviations of efficacy results among the materials in Table 4-1),
which in turn is most likely due to the complex, porous nature of this material affecting spore
recovery. (However, one other explanation for the apparent difference in results for the wood
coupons at the two different concentrations may be due to the complex (non-linear) inactivation
kinetics (Ryan et al. 2014)). In particular, it was noted that when fumigating with CICh, the time
required to achieve successful fumigation was determined to be independent of the fumigant
concentration (Rastogi et al. 2010).
These small scale coupon test results suggest that low levels of CICh gas may be a viable option
for the decontamination of materials contaminated with anthrax spores, given there is sufficient
contact time, RH and temperature. In many of the tests, relatively high efficacy was achieved at
the first time point tested (2 or 4 hours), masking any potential effect of contact time. Of the
materials tested, wood was the most difficult to decontaminate. Based on these proof of concept
results, the study moved forward with the large scale office testing in COMMANDER.
17
-------
Table 4-1. Summary of Decontamination Efficacy Results for Small Chamber Tests*
ClOi level Wood Concrete Painted Industrial Galvanized
and contact drywall carpet metal
time (hr) paper
100 ppm
2hr
4hr
6hr
8hr
10 hr
12 hr
6.61±0.90
6.67± 1.45
7.14±1.10
> 7.67 ±0.23
>7.68 ±0.23
>7.68± 0.23
>7.88±0.29
>7.88±0.29
>7.88±0.29
7.72±0.51
7.77±0.16
7.67±0.47
5. 71 ±0.30
7.49 ±0.39
6.76 ±0.74
6.33±0.33
200 ppm
2hr
4hr
6hr
8hr
10 hr
5.4±1.51
5.23±0.95
5.35±0.92
>7.66±0.36
>7.60±0.36
>7.59±0.36
> 7.69±0.48
>7.71±0.48
>7.71±0.48
> 7.76± 0.42
7.54±0.51
> 7.78± 0.42
7.54 ±0.47
>7.81±0.12
>7.81±0.12
7.66 ±0.35
* Results reported as average LR ± SD; results presented as > indicate complete inactivation of spores (no spores detected). Blank table cells
indicate material not tested at that condition
4.2 Office Decontamination Results
4.2.1 Test Matrix Summary and Fumigation Conditions for Mock Office Tests
A summary of the fumigation conditions for each mock office decontamination test is shown in
Table 4-2. These values include the target and actual levels for CICh concentration, contact time,
RH, and temperature. Except as noted in the table, all fumigations had a target RH of 75 % and
a target temperature of 25 °C. Also shown in the table is the charge time, which is the time
required to achieve the target concentration within the chamber.
The RH was generally well controlled, and with the exception of one test, ranged from 74-78 %.
In Test 15, a malfunction occurred with the humidification control system, and resulted in an
average RH level of 88%. Actual average temperatures for the COMMANDER tests ranged
from 22-29 °C.
Target C1O2 levels ranged from 100 - 3,000 ppm, with contact times ranging from 3-24 hours.
Actual C1O2 levels were generally within ± 10% of target values, with the exception of some of
the initial tests (e.g., Test 5). In addition, we were unable to achieve 3,000 ppm when this was
used as a target level (Tests 15 and 18), possibly because the C1O2 generator had inadequate
18
-------
generation capacity to overcome the large chamber volume and material demand from the office
materials (an issue discussed in Section 1 of this report).
Table 4-2. Summary of Fumigation Conditions for Mock Office Tests
Test#
3
5
4
6
14B
19
8B
16
11
13
17
15
18
Target cone.
and contact
time
100 ppm, 8
hours
100 ppm, 12
hours
200 ppm, 4
hours
200 ppm, 6
hours
200 ppm, 8
hours
200 ppm, 8
hours
300 ppm, 4
hours
300 ppm, 24
hours
750 ppm, 12
hours
1000 ppm, 9
hours
1000 ppm, 12
hours
3000 ppm, 6
hours
3000 ppm, 3
hours
Actual mean
CICh level
(ppm)
129± 19
166± 67
228± 18
214±32
215±34
198± 26
326± 19
327± 27
703± 157
943± 59
1021±35
956 ±3 10
2567± 177
Actual
contact time
(hours)
8
12.2
4
6
8
8
4
24.8
12
9.2
12
7
3
Actual mean
RH%
74.7
75.2
75.7
74.5
75.2
76.7
76.6
75.3
75.7
78.2
75.2
87.8
75.4
Actual mean T
(°C)
28.8
22.9
29.0
27.7
23.8
21.5
29.9
25.6
25.2
23.8
23.3
28.7
24.2
C1O2
charge
time
(min)
4
46.6
22
11
8
10
30.5
12.3
41
80
76
49
275
4.2.2 Quantitative surface and air sampling results for office
A summary of the overall decontamination results for the mock office tests is shown in Table 4-
3. The results presented include average office spore levels before and after decontamination
with C1O2, in log CFU/ft2, for each test. In addition to these quantitative results,
decontamination effectiveness is characterized qualitatively in terms of the number of office
surface samples (out of 25 per test) in which there were no spores detected after filter plating
(designated as non-detect, or ND). Lastly, spore concentration in the air, before and after
decontamination, is also shown in Table 4-3. Further details of these results, including the spore
levels for each particular office surface, for each test, before and after decontamination, are
found in Appendix A.
19
-------
Table
Test
#
3
5
4
6
14b
19
8b
16
11
13
17
15
18
4-3. Summary of Decontamination Results For Mock
Actual
Mean CICh
level (ppm)
129± 19
166± 67
228± 18
214±32
215±34
198± 26
326± 19
327± 27
703± 157
943± 59
1021±35
956* ±3 10
2567± 177
Contact
time
(hours)
8
12
4
6
8
8
4
24
12
9
12
6
o
J
Avg. spore
office
loading log
CFU per sq
ft, prior to
decontamina
tion
5.68±0.59
6.39±0.75
5.35±0.70
4.89±0.74
7.01±0.61
5.73 ±0.72
5.89±0.63
6.63±0.71
6.61±0.58
7.21±0.40
6.58±0.51
7.01±0.51
6.82±0.56
Avg. spore
loading, log
CFU per sq
ft, post
decontamin
ation
1.43±1.21
2.24± 1.77
-0.01±0.36
0.14±0.46
1.55±0.78
0.17±0.48
0.62± 0.60
1.32± 1.25
0.66± 0.67
1.33±0.65
0.70± 0.84
1.02 ±0.88
1.21±0.40
Number
of post
decon
office
samples
that
were
ND (out
of 25)
9
4
24
22
9
22
12
14
12
16
19
19
24
Office Tests
Number
of post
decon
swab and
RMC
samples
ND (out of
4)
4
1
4
4
4
4
3
3
3
2
3
4
4
CFU/m3
air
pre decon
2,590
23,500
243
3,860
19,800
3,830
1,670
60,000
14,600
37,900
21,900
35,500
27,100
CFU/m3
air post
decon
9.65
80
21.7
5.69
62.5
2.14
10.5
29.5
10.9
43.4
1.44
10.5
5.88
• *Test conducted at 85% RH
The average spore loadings for the mock office, prior to decontamination, ranged from 4.89 -
7.21 log CFU/ft2. These levels were in proximity to our target range of 5-7 log CFU/ft2. As
expected, the spore loadings prior to decontamination for horizontal surfaces within the office
(e.g., desk table, but excluding ceiling tiles) were approximately 0.5 log CFU/ft2 higher than the
vertical surfaces (e.g., office walls), while the ceiling tile levels were generally approximately
0.5 log CFU/ft2 lower than the vertical surfaces.
Overall average spore loadings for the office following decontamination ranged from -0.01 to
2.24 log CFU/ft2. (A negative log value implies a spore loading < 1.0 CFU/ft2).
The most difficult office objects to decontaminate (had the highest spore loading following
decontamination, or had the fewest samples that were non-detect for the study) were the
horizontal surfaces (excluding the ceiling tiles). For example, there were only two tests in which
no spores were detected on the laminated desktop following C1O2 fumigation. Items such as the
walls and ceiling, with the lowest pre-decontamination spore levels, had the highest number of
tests in which no spores were detected on their surfaces post-decontamination.
In an effort to assess the importance of various fumigation and related parameters on overall
decontamination efficacy, we conducted correlations (Pearson's r) of these data for each test
using MS Excel. The results are presented in Table 4-4. The results of this analysis show a mild
correlation of 0.62 between pre-and post-decontamination spore levels.
20
-------
Table 4-4. Correlation of Fumigation Parameters and Decontamination Results
Parameter 1
Pre -decontamination spore surface loading
Average CICh concentration
C1O2 concentration * contact time
Post-decontamination spore surface loading
Pre -decontamination spore surface loading
Number of post-decontamination surface
samples that were negative
Pre -decontamination spore surface loading
Number of post-decontamination surface
samples that were negative
Number of post-decontamination surface
samples that were negative
Parameter 2
Post-decontamination spore surface
loading
LR
LR
Post-decontamination spore air
levels
Pre-decontamination spore air levels
LR
Pre-decontamination spore surface
loading on RMCs
Number of post-decontamination
swab and RMC samples that were
negative
Number of post-decontamination
coupons (mock office tests) that
were negative
Correlation
(r)
0.62
0.46
0.64
0.74
0.69
0.46
0.90
0.56
0.56
For the overall study, Test 4, with only a 228 ppm CICh average level and 4 hour contact time,
resulted in the highest number of surface samples post-decontamination that were negative (24
out of 25, or 96 %). This test also had lowest quantity of recovered spores following
decontamination, and also had the second lowest spore loading prior to decontamination. The
average post-decontamination spore level for Test 4 was determined to be approximately 1
CFU/ft2, calculated from the assumption that the ND samples had a level of 0.5 CPU on the filter
plate.
The direct effect of spore loading on efficacy may also be viewed by comparison of the results
for Tests 14B and 19, which had similar fumigation parameters (~ 200 ppm CIChfor 8 hours).
The number of non-detects for Test 19 was much higher (22, compared to 9 for Test 14B), while
the pre-decontamination spore loading for Test 19 was over 1 log CFU/ft2 lower than for Test
14B.
Test 18, which had the highest overall average CICh concentration (2,567 ppm), also resulted in
24 of 25 samples that were non-detect. However, the average spore loading following
decontamination was 1.21 log CFU/ft2 (or 16 CFU/ft2). (This relatively mid-level spore loading
following decontamination, associated with a high number of non-detects, is due to the variable
detection limits.) Depending on the surface area sampled and the extraction liquid volume filter
plated, a non-detect (on a filter plate, assumed to be 0.5 CFU; refer to Section 2.2.6) result could
correspond to between 0.5 to 20 CFU/ft2.
The result of decontaminating with a high level of CICh for a short contact time is comparable to
other studies that have generally shown high efficacy (or relatively low levels of CFU post-
decontamination) with 3,000 ppm CICh, but not complete decontamination (i.e., not all samples
21
-------
were non-detect). See for example US EPA (2013) and Rastogi et al. (2009). The comparability
of results between the present study high CICh test and these other tests provides some
verification of the methods used in the present study.
Because of the variation in pre-QCh spore loadings and other parameters (e.g., concentration)
associated with conducting large-scale tests, it becomes difficult to directly assess the effect of
these parameters on outcome. For this reason, the correlations were performed. As shown in
Table 4-4, the product of CICh concentration times contact time (dose) had the highest
correlation (r = 0.64) with decontamination efficacy. The fumigation parameter CICh
concentration, by itself, had a correlation of 0.46 with LR. That concentration by itself had a
lower correlation than dose was not unexpected, owing to the importance of time in microbial
inactivation. Other typical fumigation parameters such as RH and temperature were not assessed
for correlation, since these parameters remained fairly constant throughout the study.
While the results of the office tests are comparable to the small scale coupon tests presented in
Section 4.1, it is difficult to make direct comparisons for the two scales of testing. Differences in
materials, spore deposition methods, spore loadings, sampling procedures, surface sample size,
etc., make direct comparisons difficult since these could affect efficacy results. For example,
while nearly every LR result in the small scale tests was greater than 6, none of the mock office
tests resulted in overall LR values of greater than 6; refer to Appendix A. However, there were
several office tests in which a number of surfaces were decontaminated with LR > 6. For
example, the filing cabinet and wallboard were decontaminated with LR greater than 6 in eight
different tests.
One other possible source that could contribute to some of difference in results for the small and
large scale tests is the resuspension of spore particles that occurred during sampling of the mock
office. Post-decontamination sampling activities conducted in the confined office space may
have reaerosolized any viable spores remaining on surfaces (such as carpet), due to tracking of
personnel and movement of equipment. (Indeed, carpet was one of the more difficult materials to
decontaminate in the office.) The results of the post-decontamination spore levels in the air are
shown in Table 4-3, and range from approximately 1 to 80 CFU/m3. Post-decontamination
average spore surface levels are well correlated (0.74) with the spore levels in the air.
4.2.3 RMC and swab results
The average pre-decontamination spore loadings in the office, as determined by surface
sampling, were highly correlated with pre-decontamination spore loadings on the RMCs. As
noted in Table 4-4, the correlation for these two parameters was 0.90. The average RMC spore
levels for a particular test were generally higher than the average loading determined by surface
sampling, in terms of log CFU/ft2. This result is consistent with the expected higher spore
recoveries obtained through direct extraction of materials versus the extraction of spores
recovered from surface sampling matrices such as wipes or vacuum socks. Typical differences
between RMC levels and surface sampling levels were less than 0.5 log CFU/ft2. Refer to
Appendix A for detailed RMC results for each test.
One swab sample was collected from the electrical outlet faceplate for each test (post-spore
dissemination, i.e., prior to decontamination), and for every test, the result was positive for
growth. Following decontamination, there were three office surfaces (faceplate, keyboard, and
computer chassis) that were sampled with a swab for qualitative results. In addition, an RMC
22
-------
was located inside a computer to assess the post decontamination result. The results for these
samples, in terms of the number (out of four per test) that were completely inactivated after
decontamination (e.g., no growth shown for swab samples; no spores detected from RMC), are
also shown in Table 4-3. The number of post-decontamination swab or RMC samples that were
negative had a 0.56 correlation coefficient with the number of post decontamination samples
determined by surface sampling that were negative.
4.2.4 Coupon results
The decontamination results for the ceiling tile, carpet, and painted wallboard mock office
coupon tests are summarized in Table 4-5, in terms of the number of coupons (out of 18) that
were completely decontaminated (no detectable spores, i.e., "non-detect") during each test.
These results are compared to the COMMANDER surface sampling results to provide context
and have a correlation coefficient of 0.56.
In addition, of the three materials used for coupons in the mock office tests (carpet, wallboard
paper, ceiling tile), the carpet material had the highest number of coupons that had detectable
spores following decontamination. This result is consistent with the small chamber tests (Table
4-1), in which the carpet coupons were more difficult to decontaminate than the wallboard paper
coupons. Please see Table A-14 in Appendix A for additional details on the results of these
coupon tests.
Table 4-5. Decontamination Results for Coupons Placed in Mock Office
Test#
Actual Mean
CICh level
(ppm)
14b 215±34
19 198±26
16 327± 27
17 1021±35
15 956 ±3 10
18 2567± 177
Contact
time
(hours)
8
8
24
12
6
o
J
Number of post
decon coupons
that were non
detect (out of 18)
15
17
10
18
18
17
Number of post
decon office
samples that were
non detect (out of
25)
9
22
14
19
19
24
4.2.5 BI results
All of the positive control Bis (those not exposed to CICh) from every experiment tested positive
for growth, as expected. None of the Bis exposed to CICh in any of the mock office tests (five
Bis were used per test) exhibited growth. While inactivating all of the Bis in the whole
experimental program demonstrates the general concept and utility of using low levels of CICh,
many of the actual surfaces within the office still contained viable spores. This general result is
23
-------
consistent with other tests (Rastogi et al. 2010) that have shown that the spore populations on Bis
are typically much easier to inactivate than spores associated with coupons from building
materials or actual environmental surfaces.
4.3 Impacts of Low level ClOi fumigation on computer operation
A summary of the results for assessing the impacts of CICh fumigation on computer functionality
over the period of a year is presented in Table 4-6. The results are presented in terms of the
number of component failures, for both the test and control computers. Some of these failures
were present before exposure to any CICh fumigation, and so can be ruled out as an effect of
fumigation. Table 4-6 shows the results with pre-existing component failure results removed.
Fumigation at approximately 214 and 211 ppm CICh for 6 or 8 hours (Tests 6 and 7,
respectively) and at approximately 303 ppm CICh for 4 hours (Test 8) showed no measureable
change on the function of the computers. The effects of the 12 hour, 166 ppm CICh (Test 5) and
the 8 hour, 297 ppm CICh (Test 9) fumigation are more difficult to interpret. In both those cases,
at least one computer performed as well as or better than the control computers, and at least one
computer performed worse. See Appendix B for further details on the methods and results.
Table 4-6. Total Computer "Fail" Results over Year-Long Test Period
Computer A
Computer B
Computer C
No CICh
(control
computers)
7
6
0
214 ppm,
6.0 hr.
(Test 6)
0
0
0
166 ppm,
12.2 hr.
(Test 5)
15
36+42a
7
211 ppm,
8.0 hr.
(Test 7)
4
1
3
303 ppm,
4.3 hr.
(Test 8)
2
3
1
297 ppm,
8.3 hr.
(Test 9)
30
0
0
a = This computer did not record the results of 42 tests for one test day
24
-------
5.0 Summary and Conclusions
Extensive testing was conducted in this study to assess the feasibility of using relatively low
levels of C1O2 gas for decontamination of materials and volumetric spaces contaminated with B.
anthracis spores. While levels of CICh in the range of 1000-3000 ppm have previously been
demonstrated to be mostly effective against B. anthracis spores, levels of CICh on the order of
100-300 ppm (with accompanying longer contact times) have not been investigated. If CICh
fumigation at these lower concentrations were to be proven effective, vendors with technologies
that produce CICh, but perhaps at relatively lower generation rates, would still be able to meet
these lower target fumigation concentrations within a large building or other space needing to be
decontaminated. This would allow for a greater number of vendors to participate in remediation
efforts following a large anthrax spore release in an urban area.
To initially prove the concept, small chamber fumigation tests were conducted using 18 mm
diameter coupons of wood, concrete, drywall, carpet, and galvanized metal, with spores
deposited onto the coupons using MDIs. Several tests were conducted at either 100 or 200 ppm
C1O2, with contact times ranging from 2-12 hr, but with all fumigations conducted at room
temperature and RH of 75 %. These small scale tests did indeed demonstrate conditions in
which the low levels of CICh were effective (> 6 LR) against the B. anthracis surrogate for all
the materials tested.
After successful completion of the small scale tests, pilot-scale tests were conducted inside a
mock office environment. To our knowledge, this portion of the study is the first of its kind, in
terms of the number of tests conducted at near-full-scale, using CICh fumigation. All tests were
conducted with B. atrophaeus spores, a long-used surrogate for testing CICh efficacy against B.
anthracis spores. Spores were disseminated into the office as a dry powder to simulate a realistic
release scenario. The study involved extensive surface sampling and other microbiological
assays, employing sampling techniques that would be used in response to an actual anthrax
incident. A portion of the mock office tests included the use of computers, to assess the impact
of low level CICh fumigation on sensitive electronics and functionality. While the focus of the
study was to use relatively low levels of CICh gas (100-300 ppm), a few tests were conducted at
750 ppm or higher to allow for comparison of results from previous studies. As with the small
scale tests, all of the mock office fumigations had a target RH of 75 % and a target temperature
of 25 °C.
The average office pre-decontamination spore levels ranged from 4.89 - 7.21 log CFU/ft2, near
our target of 5-7 log CFU/ft2. Overall average spore loadings for the office following CICh
treatment ranged from -0.01 to 2.24 log CFU/ft2, and generally correlated (0.62) with pre-
decontamination spore loadings. The correlation was apparent for specific surfaces within the
office, as well as for the overall average spore loadings in the office. For example, the most
difficult office objects to decontaminate were the horizontal surfaces such as the desk table and
carpet, which also tended to have the highest pre-decontamination spore loadings. Finally, post-
decontamination spore levels in the office air ranged from approximately 1 to 80 CFU/m3, and
correlated (0.74) with the post-decontamination spore surface levels.
The mock office portion of the study demonstrated that relatively high decontamination efficacy
(approximately 5 to > 6 LR) can be achieved using relatively low levels of CICh, depending on
the pre-decontamination spore levels and other conditions. For example, Test 4, with only a 228
ppm C1O2 average level and 4 hour contact time, resulted in the lowest quantity of spores
25
-------
recovered following decontamination (calculated to be approximately 1 CFU/ft2, based on
assuming 0.5 CPU were recovered from ND samples). Correspondingly, this test also had the
highest number of surface samples post-decontamination that were negative (24 out of 25, or 96
%) for the test program, and had the second lowest average office spore loading prior to
decontaminati on.
Relative to comparing the results of the office tests to the initial small scale coupon tests, while
nearly every LR result in the small scale tests was greater than 6, none of the mock office tests
resulted in overall average office LR values of greater than 6. Nevertheless, there were several
office tests in which a number of surfaces were ND for spores and were decontaminated with LR
> 6. For example, the filing cabinet and wallboard were decontaminated with LR greater than 6
in eight of 13 different tests. In any event, it is difficult to make direct comparisons for the two
scales of testing, since differences in materials, spore deposition methods, spore loadings,
sampling procedures, surface sample size, etc., could affect efficacy results.
Every BI exposed to CICh in all the mock office tests in which they were used was inactivated,
demonstrating the general concept and utility of using low levels of CICh. However, many of the
actual surfaces within the office still presented viable spores following decontamination. This
general result is consistent with other tests that have shown that the spore populations on Bis are
typically much easier to inactivate than spores associated with coupons from building materials
or actual environmental surfaces. The general conclusion here is that Bis that remain viable after
C1O2 treatment would be a good indication that the CICh fumigation failed. However, Bis that
have been inactivated following CICh treatment do not necessarily imply that the fumigation was
successful.
Fumigation at approximately 200 ppm CICh for 6 or 8 hours and at approximately 300 ppm CICh
for 4 hours showed no measureable change in the functionality of the computers.
The study has demonstrated the potential of using relatively low levels of CICh gas, accompanied
by longer contact times, for effective decontamination of surfaces and spaces contaminated by
anthrax spores. However, this decontamination approach may be better suited for areas that are
not heavily contaminated, i.e., that have spore loadings less than 5 log CFU/ft2 and/or that do not
contain significant quantities of porous materials such as carpet and wood. Further research is
recommended to find efficacious low concentration conditions for heavily contaminated surfaces
and for difficult to decontaminate materials.
26
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6.0 References
Brown, G. S., Betty, R.G., Brockmann, I.E., Lucero, D.A., Souza, C.A., Walsh, K.A., Boucher,
R.M., Tezak, M., Wilson, M.C. and Rudolph, T. (2007A) Evaluation of a wipe surface sample
method for collection of Bacillus spores from nonporous surfaces. Appl Environ Microbioll?>. 3:
706-710.
Brown, G. S Betty, R.G., Brockmann, I.E., Lucero, D.A., Souza, C.A., Walsh, K.A., Boucher,
R.M., Tezak, M., Wilson, M.C., Rudolph, T., Lindquist, H.D. and Martinez, K.F. (2007B)
Evaluation of rayon swab surface sample collection method for Bacillus spores from nonporous
surfaces." JApplMicrobiol 103.4: 1074-1080.
Brown, G. S., Betty, R.G., Brockmann, J.Z., Lucero, D.A., Souza, C.A., Walsh, K.S., Boucher,
R.M., Tezak, M.S., and Wilson, M.C. (2007C) Evaluation of vacuum filter sock surface sample
collection method for Bacillus spores from porous and non-porous surfaces. JEnvironMonit 9.7:
666-671.
Calfee, M. W., Ryan, S.P., Wood, J.P., Mickelsen, L., Kempter, C., Miller, L., Colby, M.,
Touati, A., Clayton, M., Griffm-Gatchalian, N., McDonald, S. and Delafield, R. (2102)
Laboratory evaluation of large-scale decontamination approaches. J Appl Microbiol 112.5: 874-
882.
Campbell, C.G., Kirvel, R.D., Love, A.H., Bailey, C.G., Miles, R., Schweickert, J., Sutton, M.,
and Raber, E. (2012) Decontamination after a release of B. anthracis spores. Biosecur.
Bioterror. 10:1, 108-122.
Canter, D. A. (2005) Remediating anthrax-contaminated sites: learning from the past to protect
the future. Chem. Health Safety 12:13-19.
Han, Y., Applegate, B., Linton, R.H. and Nelson, P.E. (2003) Decontamination of Bacillus
thuringiensis spores on selected surfaces by chlorine dioxide gas. J Environ Health 66.4: 16-21.
Jeng, D. K. and Woodworm, A.G. (1990) Chlorine dioxide gas sterilization under square-wave
conditions. Appl. Environ. Micro. 56.2: 514-519.
Krauter, P., Tucker, M. (2011) A biological decontamination process for small, privately owned
buildings. Biosecur. Bioterror. 9, 301-309.
Lee, S., Ryan, S.P., Snyder, E. (2011) Development of an aerosol surface inoculation method for
bacillus spores. Appl Environ Microbiol 77(5): 163 8-1645.
Meyer, K.M., Calfee, M.W., Wood, J.P., Mickelsen, L., Attwood, B., Clayton, M., Touati, A.
and Delafield, R. (2013) Fumigation of a laboratory-scale HVAC system with hydrogen peroxide
for decontamination following a biological contamination incident. J Appl Microbiol 116.3: 533-
541.
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Rastogi, V. K., Wallace, L. Ryan, S.P., and Martin, B. (2009) Quantitative method to determine
sporicidal decontamination of building surfaces by gaseous fumigants, and issues related to
laboratory-scale studies. Appl EnviroMicro 75.11: 3688-3694.
Rastogi, V. K., Ryan, S.P., Wallace, L., Smith, L.S., Shah, S.S. and Martin, G.B. (2010)
Systematic evaluation of the efficacy of chlorine dioxide in decontamination of building interior
surfaces contaminated with anthrax spores. Appl Environ Micro 76.10; 3343-3351.
Ryan, S.P., Lee, S.D., Calfee, M.W., Wood, J.P., McDonald, S., Clayton, M., Griffm-Gatchalian,
N. Effect of inoculation method on the determination of decontamination efficacy against
Bacillus spores. World JMicrobiolBiotechnolDOI 10.1007/sl 1274-014-1684-2.
US Centers for Disease Control and Prevention (2012) Emergency Response Resources,
Surface sampling procedures for Bacillus anthracis spores from smooth, non-porous
surfaces
http://www.cdc.gov/niosh/topics/emres/surface-sampling-bacillus-anthracis.html accessed May
9,2014.
U.S. EPA (2005). Compilation of available data on building decontamination alternatives.
Washington, DC, EPA/600/R-11/012.
US EPA (2008) Material demand studies: interaction of chlorine dioxide gas with building
materials. EPA/600/R-08/091.
US EPA (2010) Determining the efficacy of liquids and fumigants in systematic decontamination
studies for Bacillus anthracis using multiple test methods. EPA/600/R-10/088.
US EPA (2012 A) Anthrax spore decontamination using chlorine dioxide.
http://www.epa.gov/pesticides/factsheets/chemicals/chlorinedioxidefactsheet.htm. Accessed
March 27 2014.
US EPA (2012 B). Inactivation of Bacillus anthracis spores in soil matrices with chlorine
dioxide gas, EPA/600/R/12/517.
U.S. EPA (2013). Bio-response operational testing and evaluation (BOTE) project - Phase 1:
Decontamination assessment. Washington, DC, EPA/600/R-13/168.
Wood, J.P. and Martin, G.B. (2009) Development and field testing of a mobile chlorine dioxide
generation system for the decontamination of buildings contaminated with Bacillus anthracis. J
Hazard Mater 164:2-3: 1460-1467.
Wood, J.P., Ryan, S.P., Snyder, E.G., Serre, S.D., Touati, A., and Clayton, M.J. (2010)
Adsorption of chlorine dioxide gas on activated carbons. J Air & Waste Manag Assoc 60.8: 898-
906.
Wood, J.P., Calfee, M.W., Clayton, M., Griffm-Gatchalian. N/. Touati, A. and Egler, K. (2013)
Evaluation of peracetic acid fogging for the inactivation of Bacillus spores. J Hazard Mater,
250-251:61-67.
28
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Appendix A
Detailed Microbiological and Decontamination Results
29
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Table A-l. Test 3 Detailed Results
Office Surface or Object
ClOzPPM
target = 100
Contact
time =8
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qua), results
catalog
keyboard
chair back
chair seat G
pin cushion screen
ceiling tile
carpet
desktop G
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
2.05E+05
1.93E+06
4.69E+04
5.48E+05
2.63E+05
1.42E+05
2.59E+05
3.11E+06
7.67E+05
2.48E+06
5.68
1.42E+06
3.59E+05
1.66E+02
1.27E+02
5.71E+02
9.65E+01
8.09E-01
2.27E+00
1.12E+02
8.10E+02
l.OOE+00
l.OOE+00
1.43
2.19E+02
1.91E+02
ND
ND
4.25
9
electrical socket swab
keyboard swab
computer swab
G
NG
NA
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
2.59E+00
ND
9.65E-03
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
6.68E+05
1.34E+06
3.57E+04
1.46E+05
1.88E+06
1.10E+06
5.66
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
NA= not available. ND=not detected
30
-------
Table A-2. Test 5 Detailed Results
Office Surface or Object
ClOzPPM
target = 100
Contact
time =12
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard G
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
2.19E+05
8.03E+06
1.08E+05
3.93E+06
7.80E+06
7.88E+05
2.97E+06
1.68E+07
2.59E+06
1.35E+07
6.39
7.59E+06
3.50E+06
6.00E+00
7.90E+02
3.17E+02
1.67E+03
9.06E+00
1.45E+00
1.56E+03
1.06E+04
4.85E+01
l.OOE+03
2.24
2.61E+03
1.25E+02
4.15
4
electrical socket swab
keyboard swab
computer swab
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
2.35E+01
7.10E+00
8.00E-02
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
9.49E+06
3.90E+06
5.03E+06
3.08E+06
1.12E+07
6.86E+06
6.77
3.28E+03
Note: all data in CPU/ ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
31
-------
Table A-3. Test 4 Detailed Results
Office Surface or Object
ClOzPPM
target = 200
Contact
time =4
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
6.18E+04
2.66E+06
3.55E+05
1.73E+06
9.00E+04
9.46E+04
2.54E+05
1.05E+06
7.60E+04
1.97E+04
5.35
9.62E+05
1.74E+05
6.00E+00
9.40E-01
3.11E+00
1.21E+00
6.32E-01
6.12E-01
6.21E-01
5.81E-01
5.82E-01
5.01E-01
-0.01
1.64E+00
1.44E+00
ND
ND
ND
ND
ND
ND
ND
ND
ND
5.36
24
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
2.43E-01
ND
2.17E-02
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
8.35E+03
2.88E+03
1.44E+03
4.32E+03
1.15E+03
1.22E+07
4.05
ND
Note: all data in CPU/ ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
32
-------
Table A-4. Test 6 Detailed Results
Office Surface or Object
ClOzPPM
target = 200
Contact
time =6
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat G
pin cushion screen
ceiling tile
carpet G
desktop G
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
5.76E+03
1.53E+05
1.29E+04
4.73E+05
2.57E+05
8.61E+03
3.70E+04
4.26E+05
1.34E+05
3.39E+05
4.89
2.39E+05
1.35E+05
5.78E+00
9.80E-01
1.21E+00
1.21E+00
6.06E-01
1.02E+00
7.36E-01
1.46E+01
6.56E-01
6.27E-01
0.14
3.99E+00
8.24E-01
ND
ND
ND
ND
ND
ND
ND
ND
4.76
22
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
3.86E+00
ND
5.69E-03
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
2.81E+05
1.56E+06
1.26E+03
1.13E+05
3.13E+05
5.65E+05
5.17
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
33
-------
Table A-5. Test 14B Detailed Results
Office Surface or Object
ClOzPPM
target = 200
Contact
time =8
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop G
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
1.34E+06
3.97E+07
3.90E+06
4.39E+06
l.OOE+07
1.86E+06
1.44E+07
9.68E+07
1.29E+07
3.99E+07
7.01
3.27E+07
8.93E+06
2.34E+01
1.70E+02
2.00E+01
7.00E+01
l.OOE+01
4.33E+01
2.87E+02
4.66E+02
1.80E+00
5.15E+00
1.55
1.70E+02
1.06E+01
ND
ND
5.46
9
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
1.98E+01
6.25E-02
viacell FB (CPU/sample) ND
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
2.09E+07
2.21E+07
1.13E+07
1.08E+07
7.94E+07
4.12E+07
7.38
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
34
-------
Table A-6. Test 8b Detailed Results
Office Surface or Object
ClOzPPM
target = 300
Contact
time =4
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet G
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
1.32E+05
2.90E+06
5.12E+04
1.85E+06
1.35E+06
4.00E+05
4.42E+05
4.56E+06
8.25E+05
2.62E+06
5.89
2.08E+06
7.42E+05
1.14E+01
8.23E+00
5.23E+00
1.26E+01
4.52E+00
5.88E-01
1.84E+01
1.33E+01
6.44E-01
6.18E-01
0.62
1.08E+01
3.47E+00
5.27
12
electrical socket swab
keyboard swab
computer swab
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
1.67E+00
ND
1.05E-02
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
1.70E+06
5.80E+06
1.10E+06
1.93E+06
5.54E+06
2.68E+06
6.42
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
35
-------
Table A-7. Test 16 Detailed Results
Office Surface or Object
ClOzPPM
target = 300
Contact
time =24
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
9.70E+05
1.40E+06
2.40E+06
8.17E+06
3.19E+06
2.16E+05
6.23E+06
2.98E+07
1.27E+07
4.78E+07
6.63
1.57E+07
6.10E+06
5.82E+00
1.48E+02
4.63E+00
8.13E+00
6.06E-01
3.74E+00
4.34E+02
1.12E+03
5.96E-01
7.98E+02
1.32
4.19E+02
1.94E+00
ND
ND
ND
ND
5.31
14
electrical socket swab
keyboard swab
computer swab
NA
NG
G
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
6.01E+01
1.43E+01
2.95E-02
Ref Measurement Coupons
wall
2.55E+06
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
5.26E+06
2.20E+07
3.11E+07
1.16E+07
7.01
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
36
-------
Table A-8. Test 11 Detailed Results
Office Surface or Object
ClOzPPM
target = 750
Contact
time =12
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back G
chair seat G
pin cushion screen
ceiling tile
carpet
desktop G
drywall G
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
5.82E+06
3.86E+06
1.15E+06
6.61E+06
2.64E+06
3.30E+05
1.03E+07
2.74E+07
1.56E+06
1.82E+07
6.61
1.20E+07
1.79E+06
1.16E+01
1.94E+01
2.32E+00
2.91E+00
5.90E-01
1.42E+00
2.22E+01
4.90E+01
6.30E-01
4.64E+00
0.66
1.83E+01
1.18E+00
5.95
12
electrical socket swab
keyboard swab
computer swab
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
1.46E+01
1.12E+00
1.09E-02
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
5.17E+06
3.24E+06
2.13E+07
6.90E+06
5.85E+06
3.86E+06
6.79
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
37
-------
Table A-9. Test 13 Detailed Results
Office Surface or Object
ClOzPPM
target = 1000
Contact
time =9
VHP® Pre-decon
reset spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
G 3.13E+06
2.28E+07
9.52E+06
3.60E+07
1.69E+07
G 4.09E+06
G 3.17E+07
4.40E+07
1.63E+07
3.22E+07
7.21
2.83E+07
1.42E+07
1.44E+02
3.29E+01
2.00E+01
8.00E+01
l.OOE+01
l.OOE+01
5.00E+01
5.43E+01
7.08E-01
1.24E+01
1.33
6.23E+01
1.02E+01
ND
ND
ND
ND
5.88
16
electrical socket swab
keyboard swab
computer swab
G
NG
G
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
3.79E+01
1.73E+02
4.34E-02
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
2.44E+07
9.26E+06
1.09E+07
4.70E+07
4.06E+07
3.04E+07
7.36
3.65E+01
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
38
-------
Table A-10. Test 17 Detailed Results
Office Surface or Object
ClOzPPM
target = 1000
Contact
time =12
VHP® Pre-decon
reset spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
3.60E+06
1.05E+06
2.88E+06
2.23E+06
2.18E+06
l.OOE+06
7.44E+06
3.65E+07
2.63E+06
1.82E+07
6.58
1.15E+07
2.57E+06
1.84E+02
2.01E+00
1.22E+00
1.22E+00
8.28E-01
l.OOE+01
l.OOE+01
6.53E+01
5.62E-01
6.18E+00
0.70
4.47E+01
8.70E-01
ND
ND
ND
ND
5.88
19
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
2.19E+01
ND
1.44E-03
Ref Measurement Coupons
wall
inside computer
4.45E+07
7.69E+06
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
1.32E+07
1.33E+07
1.91E+07
7.21
7.83E+01
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
39
-------
Table A-ll. Test 15 Detailed Results
Office Surface or Object
CIO2 PPM Contact
target = 1000 time =6
*85% RH
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
4.30E+06
3.88E+06
4.27E+06
2.15E+07
9.55E+06
1.98E+06
1.07E+07
8.37E+07
9.44E+06
4.83E+07
7.01
2.87E+07
7.75E+06
1.73E+02
1.96E+00
2.00E+01
2.00E+01
l.OOE+01
l.OOE+01
1.60E+01
2.03E+02
6.82E-01
5.15E-01
1.02
6.91E+01
1.02E+01
ND
ND
ND
ND
ND
5.99
19
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
3.55E+01
1.05E-02
viacell FB (CPU/sample)
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
5.33E+06
6.51E+06
13818000
15414000
19173000
33600000
7.11
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
40
-------
Table A-12. Test 18 Detailed Results
Office Surface or Object
ClOzPPM
target = 1000
Contact
time =12
VHP®
reset
Pre-decon
spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back G
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
3.97E+06
7.80E+06
7.98E+06
3.55E+06
5.38E+06
9.85E+05
1.24E+07
1.10E+08
1.47E+07
1.74E+06
6.82
2.33E+07
9.37E+06
1.92E+02
1.65E+01
2.00E+01
2.00E+01
l.OOE+01
l.OOE+01
l.OOE+01
l.OOE+01
l.OOE+01
9.28E+00
1.21
4.30E+01
1.33E+01
ND
ND
ND
ND
ND
ND
ND
ND
ND
5.61
24
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
2.71E+01
ND
5.88E-03
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
1.23E+07
8.23E+06
8.40E+06
7.77E+06
1.07E+07
1.10E+07
6.98
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
41
-------
Table A-13. Test 19 Detailed Results
Office Surface or Object
ClOzPPM
target = 1000
Contact
time =12
VHP® Pre-decon
reset spore levels
Post-decon
spore levels
Post-decon
qual. results
catalog
keyboard
chair back
chair seat
pin cushion screen
ceiling tile
carpet
desktop
dry wall
filing cabinet
log of geo. mean; log reduction
Total # surface samples (out of
25) = ND
avg horiz surf (excl. ceiling tile)
avg vert surf
7.87E+05
2.06E+06
1.73E+05
6.34E+05
5.94E+05
1.29E+04
1.96E+05
4.62E+06
6.98E+05
2.32E+06
5.73
1.77E+06
4.88E+05
1.13E+01
9.97E-01
1.50E+00
1.34E+00
1.23E+00
6.00E-01
6.15E-01
1.10E+01
7.16E-01
6.40E-01
0.17
4.32E+00
1.15E+00
ND
ND
ND
ND
ND
ND
ND
5.56
22
electrical socket swab
keyboard swab
computer swab
G
NG
NG
NG
viacell air sample (CPU/liter)
viacell FB (CPU/sample)
3.83
ND
2.14E-03
Ref Measurement Coupons
wall
inside computer
corner of floor
center of chair
keyboard
filing cabinet
inside computer post -test
log of geo mean RMC
6.26E+05
1.08E+06
9.03E+05
6.26E+05
1.82E+06
1.80E+06
6.02
ND
Note: all data in CPU/ft2, except swabs and VHP® reset samples (Growth, No Growth); air samples (CPU/liter)
ND=not detected
42
-------
Table A-14. Detailed Coupon Efficacy Results
14B 15 16 17 18 19
Pre- Pre^Pre-Pre^ Pre^ Pre-
decon Post decon Post decon Post decon Post decon Post decon Post
log decon log decon log decon log decon log decon log decon
CPU result CPU result CPU result CPU result CPU result CPU result
value value value value value value
CT
3.8
ND
3.3
ND
4.1
1
3.3
ND
3.4
ND
3.1
ND
Carpet
4
ND
3.7
ND
4.5
2
3.4
ND
3.2
ND
2.8
ND
WB
3.5
ND
3.2
ND
3.9
1
3.1
ND
2.8
1
2.7
ND
CT
7.3
ND
6.9
ND
7.0
ND
7.0
ND
7.1
ND
6.9
ND
Carpet
7.2
3
7.4
ND
7.2
3
7.2
ND
6.9
ND
7.2
1
WB
6.6
ND
6.7
ND
6.8
3
6.6
ND
6.9
ND
6.0
ND
CT = ceiling tile; WB = painted wallboard paper; ND = no spores detected on any of the 3 coupons tested
If an integer is listed in a "Post decon" column, this reflects number of coupons out of three that had detectable
spores.
43
-------
Appendix B
Detailed Analyses for PC Doctor® Results
PC-Doctor® Service Center™ 7.5 is commercially available software designed to diagnose and
detect computer component failures. A complete list of the PC-Doctor® Service Center™ 7.5
diagnostic tests is shown in Table Bl.
Table Bl. PC- Doctor Tests
Test
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Test Description
Verify System Information List
RTC Rollover Test
RTC Accuracy Test
Advanced Pattern Test
Bit Low Test
Bit High Test
Nibble Move Test
Checkerboard Test
Walking One Left Test
Walking One Right Test
Auxiliary Pattern Test
Address Test
Modulo20 Test
Moving Inversion Test
Windows Memory Test
Register Test
Level 2 Cache Test
Math Register Test
M MX Test
SSE Test
SSE2 Test
SSE3 Test
SSSE3 Test
SSE4.1 Test
Tested Subsystem
SYSTEMS DETECTION
System Board
System Board
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
2048 MB DDR3-SDRAM (1333 MHz)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
44
-------
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
SSE4.2 Test
Stress Test
Multicore Test
Checksum Test
Pattern Test
Thermal Cycle Test
Shader Rendering DX10 Test
Wireframe Shader Rendering Test
Shader Rendering Test
GPU Pipeline Data Test
Transformation and Lighting Stress Test
Fixed Transformation and Lighting Test
Primary Surface Test
Non-Local Video Memory Test
Local Video Memory Test
SMART Status Test
SMART Short Self Test
SMART Extended Self Test
SMART Conveyance Self Test
Linear Seek Test
Random Seek Test
Funnel Seek Test
Surface Scan Test
CD Linear Seek Test
CD Random Seek Test
CD Funnel Seek Test
CD Linear Read Compare Test
CD Audio Test
CD-R Read Write Test
CD-RW Read Write Test
DVD+R Read Write Test
DVD-RW Read Write Test
DVD Linear Seek Test
DVD Random Seek Test
DVD Funnel Seek Test
DVD Linear Read Compare Test
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
Intel(R) Core(TM) 15-2500 CPU @
3.30GHZ (CPU:0)
CMOS
CMOS
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
Intel(R) HD Graphics Family
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
OS- C: (WDC WD2500AAKX-753CA1 )
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
HL-DT-ST DVD+-RW GH70N
AVI Test
61
AVI Interactive Test
45
-------
62
Monitor Interactive Test
DELL E1911 (Generic PnP Monitor)
63 Keyboard Interactive Test
HID Keyboard Device
64
Mouse Interactive Test
HID-Compliant Mouse
65
Network Link Test
Intel(R) 82579LM Gigabit Network
Connection
66 TCP/IP Internal Loopback Test
Intel(R) 82579LM Gigabit Network
Connection
67 Network External Loopback Test
Intel(R) 82579LM Gigabit Network
Connection
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
Configuration Test
PCI Express Status Test
PCI Express Status Test
PCI Express Status Test
Standby Test
Hibernation Test
Internal Register Test
Internal Control Signals Test
Internal Send and Receive Test
Internal Register Test
Internal Control Signals Test
Internal Send and Receive Test
USB Port Test
Rough Audio Test
Sound Interactive Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
PCI Bus
High Definition Audio Controller
Intel(R) 6 Series/C200 Series Chipset
Family PCI Express Root Port 1 - 1C10
Intel(R) 6 Series/C200 Series Chipset
Family PCI Express Root Port 3 - 1C14
Standby/Hibernate
Standby/Hibernate
I ntel(R) Active Management
Technology - SOL (COM3)
I ntel(R) Active Management
Technology - SOL (COM3)
I ntel(R) Active Management
Technology - SOL (COM3)
Communications Port (COM1)
Communications Port (COM1)
Communications Port (COM1)
USB Port Test
Realtek High Definition Audio
Realtek High Definition Audio
USB Hub 1
USB Hub 2
USB Test Key
Dell USB Entry Keyboard
USB Optical Mouse
USB Storage Device
USB Storage Device
USB Storage Device
USB Storage Device
USB Storage Device
USB Storage Device
USB Storage Device
46
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The PC-Doctor® Service Center™ 7.5 protocol was developed to have an industry-accepted
standard method of determining pass versus failure of the computer subsystems. PC-Doctor®
Service Center™ 7.5 functionality testing was conducted on each computer pre-fumigation, one
day post-fumigation, then monthly for the next year with exceptions due to budget constraints.
This testing provided valuable information about the extent and time dependence of the
degradation of these computers following the various fumigation scenarios. All computers were
kept under ambient laboratory conditions, in which humidity was not strictly controlled.
When conducting a functionality test on a computer, if any particular sub-system check (out of
the 94 performed) failed the first time, the computer was tested a second time to correct for
possible human error. A test that failed the second time was labeled "Fail". If the test failed the
first time but passed the second time, it was labeled "Pass2". There were certain instances when
the computer did not allow certain tests to be run. These were listed as "False-Fail", because
though the test was not run, it was considered a failure since the test should have been able to
run. For tabulation, a score of 1,000 was assigned to each "Fail" and "False-Fail", while a
"Pass2" received a score of 1. Some test dates have a total of only 93 tests; in this case, the
results were not manually recorded due to operator error. There was no score assigned to known
operator error. During each pre- and post-fumigation testing period, a total PC-Doctor® score was
the sum of the scores from each of the 94 tests. A score of 0 indicated a computer that passed all
tests, while a score of 94000 would indicate a computer that failed all tests.
4000
3500
3000
Average PC-Doctor Score by Fumigation Test
(-500 values were from tests not performed)
I Fumigation C6
I Fumigation C5
Fumigation C7
I Fumigation C8
Fumigation C9
CONTROL
Months After Fumigation
Figure B1. Average PC-Doctor Score overtime*.
*Computer B (JW08) value for Month 0 Fumigation C5 removed in this graph as an outlier
Figure Bl shows the average score of three replicate computers for each month. Some computers
were not tested each month, and they were assigned a value of-500 in Figure 1 to distinguish a 0
(All pass) from a null value (not performed). Table B2 provides a total of all incidents of PC-
Doctor® Service Center™ 7.5 tests that received a "Fail." For each test condition, the results are
shown for each of the computers that underwent year-long testing.
47
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Table B2. Total "Fail" Results For Year-Long Test Period
Fumigation
Technology
Computer A
Computer B
Computer C
None
7
6
0
200 ppmv
C1O2, 6 hr.
(C6)
1
0
0
100 ppmv
C1O2, 12
hr.
(C5)
15
36+42a
7
200 ppmv
C1O2, 8
hr.
(C7)
4
3
5
300 ppmv
C1O2, 4
hr.
(C8)
2
3
22b
300 ppmv
C1O2, 8
hr.
(C9)
30
0
27b
a = This computer did not record the results of some tests for one test day
b = This computer never detected two USB ports, which therefore always failed. This was a preexisting condition.
Some of these failures were present before the fumigation, and so can be ruled out as an effect of
fumigation. Table B3 shows the results from Table B2, with pre-existing results removed.
Table B3. Total "Fail" Results with Pre-Existing Failures Removed
Fumigation
Technology
Computer A
Computer B
Computer C
None
7
6
0
200 ppmv
C1O2, 6 hr.
(C6)
0
0
0
100 ppmv
C1O2, 12
hr.
(C5)
15
36+42a
7
200 ppmv
C1O2, 8
hr.
(C7)
4
1
3
300 ppmv
C1O2, 4
hr.
(C8)
2
3
1
300 ppmv
C1O2, 8
hr.
(C9)
30
0
0
a = This computer, JW08, did not record the results of 42 tests for one test day
Fumigation at 200 ppmv CICh for 6 or 8 hours (C6 and C7) and 300 ppmv CICh for 4 hours (C8)
had no measureable effect on the function of the computers. The effects of the 12 hour 100 ppmv
C1O2 (C5) and the 8 hour 300 ppmv CICh (C9) fumigation are more difficult to interpret. In both
cases, at least one computer performed as well as or better than the control computers, and at
least one computer performed worse. With such a small sample size, it is impossible to say with
any statistical certainty that poorer performance was a result of the exposure to fumigation
conditions.
Table B4 lists of all failures as a function of subsystem. The failures are dominated by USB
failures, which, as stated before, do not seem to be a result of fumigation, given that they were
present before fumigation.
48
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Table B4.
Test
Number
41
42
43
47
48
52
53
54
55
56
63
65
67
72
73
80
81
82
92
94
95
96
Vulnerable Subsystems
Test Description
SMART Short Self Test
SMART Extended Self Test
SMART Conveyance Self Test
Surface Scan Test
CD Linear Seek Test
CD Audio Test
CD-R Read Write Test
CD-RW Read Write Test
DVD+R Read Write Test
DVD-RW Read Write Test
Keyboard Interactive Test
Network Link Test
Network External Loopback
Test
Standby Test
Hibernation Test
USB Port Test
Rough Audio Test
Sound Interactive Test
USB Status Test
USB Status Test
USB Status Test
USB Status Test
Total
Pass2
4
4
1
9
4
1
0
2
16
9
5
9
1
1
1
1
1
Number
Fail
2
3
3
3
1
7
0
0
15
2
0
1
1
2
3
18
2
0
1
0
0
7
of Events
False
Fail
7
1
28
61
*Computer B (JW08) value for Month 0 Fumigation C5 removed in this table as an outlier
49
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United States
Environmental Protection
Agency
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
Office of Research and Development (8101R)
Washington, DC 20460
Official Business
Penalty for Private Use
$300
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