EPA/600/R-97/034
Jure 1997
Field and Laboratory Evaluations of a
Real-Time PAH Analyzer
by
Mukund Ramamurthi and Jane C. Chuang
Battelle Memorial Institute
505 King Avenue
Columbus, Ohio 43101-2693
Contract 68-DO-0007
Work Assignment 42
Project Officer
Nancy K. Wilson
Air Exposure Research Division
National Exposure Research Laboratory
Research Triangle Park, North Carolina 27711
National Exposure Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Printed on Recycled Paper
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EPA DISCLAIMER
The information in this document has been funded wholly or in part by the United
States Environmental Protection Agency under Contract 68-DO-0007 to Battelle Memorial
Institute. It has been subject to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or .recommendation for use.
BATTELLE DISCLAIMER
This report is a work prepared for the United States Environmental Protection Agency
by Battelle Memorial Institute. In no event shall either the United States Environmental
Protection Agency or Battelle Memorial Institute have any responsibility or liability for any
consequences of any use, misuse, inability to use, or reliance upon the information contained
herein, nor does either warrant or otherwise represent in any way the accuracy, adequacy,
efficacy, or applicability of the contents hereof.
u
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FOREWORD
The mission of the National Exposure Research Laboratory (NERL) is to provide
scientific understanding, information and assessment tools that will quantify and reduce the
uncertainty in EPA's exposure and risk assessments for environmental stressors. These
stressors include chemicals, biologicals, radiation, and changes in climate, land use, and water
use. The Laboratory's primary function is to measure, characterize, and predict human and
ecological exposure to pollutants. Exposure assessments are integral elements in the risk
assessment process used to identify populations and ecological resources at risk. The EPA
relies increasingly on the results of quantitative risk assessments to support regulations,
particularly of chemicals in the environment. In addition, decisions on research priorities are
influenced increasingly by comparative risk assessment analysis. The utility of the risk-based
approach, however, depends on accurate exposure information. Thus, the mission of NERL is
to enhance the Agency's capability for evaluating exposure of both humans and ecosystems
from a holistic perspective.
The National Exposure Research Laboratory focuses on four major research areas:
predictive exposure modeling, exposure assessment, monitoring methods, and environmental
characterization. Underlying the entire research and technical support program of the NERL is
its continuing development of state-of-the-art modeling, monitoring, and quality assurance
methods to assure the conduct of defensible exposure assessments with known certainty. The
research program supports its traditional clients Regional Offices, Regulatory Program
Officer, ORD Offices, and Research Committees and "ORD's Core Research Program in the
areas of health risk assessment, ecological risk assessment, and risk reduction.
Human exposure to air pollutants, including volatile compounds and semivolatile
organic compounds such as the polycyclic aromatic hydrocarbons, is an area of concern to
EPA because of their possible carcinogenicity or other toxicity. These compounds originate
from industial processes and combustion. They are present in a variety of outdoor and indoor
microenvironments. The efforts described in this report provide an important contribution to
our capability for measuremnt and evaluation of human exposure to air toxics.
Gary J. Foley
Director
National Exposure Research Laboratory
m
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ABSTRACT
This study is a follow-up to previous work conducted at Battelle for the purpose of
evaluating the Gossen PAS lOOOi (and the more recent Model 10021) for real-time analysis of
particulate PAH in indoor air. Specific tasks conducted as part of this work included further
tests of the response of the analyzer to a number of 2- to 4-ring PAH and benzene vapors at
high and low relative humidity levels, and an evaluation of the noise and ozone output of the
analyzer. The analyzer did not respond to PAH and benzene vapors in all except for two
cases; in these two cases, it is suspected that the response observed is related to the
adsorption of the specific PAH vapor on particle surfaces, rather than to the vapor itself.
The noise level from the analyzer was below the NC-35 criterion except at frequencies of
1000-3000 Hz where the levels approached the NC-40 criterion. Only small emissions of
ozone were measured from the operation of the analyzer.
In addition to the above tasks, a cigarette smoke generator was developed for field
evaluations of the PAH analyzer. Despite the inherent variability in the cigarette combustion
process, the smoke generator could be used in the reasonably reproducible manner to verify
operation of a PAH analyzer in the field.
The effect of elevated or depressed temperature and humidity operating conditions on
the response of the PAH analyzer was also studied. These operating conditions were not
found to have a significant impact on the response of the analyzer to a cigarette smoke
aerosol equilibrated at the test temperature. As a matter of research interest, it. was found
that the response of an analyzer operated at typical indoor temperature and humidity
conditions (20"C, 40% R.H.) to a cigarette smoke test aerosol increased as a function of the
sampled air temperature.
IV
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The aerosol transmission efficiency through the PAH analyzer was also determined for
monodisperse particle sizes over the size spectrum, 0.034 - 0.32 /xm. The results suggested
that the current sampling configuration of the analyzer results in substantial aerosol losses at
small particle sizes and is not conducive to representative aerosol sampling, particularly for
particle sizes <0.10 pm. A modified sampling configuration was developed and tested.
The modified analyzer had a transmission efficiency of >90% over the entire size spectrum.
Field tests in several indoor microenvironments did not indicate any deleterious effects on the
performance of the analyzer due to the modification in sampling configuration.
As a continuation of work conducted previously, a systematic study of the response of
the analyzer to laboratory generated non-PAH aerosols was also conducted. The response of
the analyzer was determined using monodisperse test aerosols of several inorganic (sodium
chloride, ammonium sulfate) and organic substances (phthalic anhydride, di-octyl phthalate)
generated from nebulizing both water and iso-propyl alcohol solutions of these substances.
The results suggest that the response is due to contaminant(s) present in the solvent that
become deposited on the surface of the test aerosol during the droplet drying process. The
origin and identity of the contaminants could not be determined.
This work also included a small pilot study conducted concurrently with a PAH in
house dust study that was the focus of a separate EPA Work Assignment. In the pilot study,
fine particle (<2.5 /tm) PAH concentrations were sampled using an integrated filter-XAD
resin sampling train and analyzed by an established GC/MS technique. These concentrations
were then compared with the average response of a PAH analyzer collocated with the
integrated sampler. The results obtained were consistent with those obtained in our previous
evaluation study of the PAH analyzer. The measured fine-particle PAH concentrations were
between one-fifth and two-times the PAH concentration calculated from the analyzer's
average responses asssuming a calibration constant of 3000 ng/m3/pAmp.
This report is submitted in fulfillment of Contract No. 68-DO-0007 (WA 42) by
Battelle under the sponsorship of the U.S. Environmental Protection Agency. It covers the
period between June 1992 and September 1993. Work was completed as of September 1993.
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CONTENTS
Foreword iii
Abstract iv
Figures viii
Tables xii
Acknowledgment > ix
1. Introduction 1
2. Conclusions 3
3. Recommendations 5
4. Experimental Procedure 6
PAH Analyzer to 2- to 4-Ring PAH Vapors 6
Noise and Ozone Output of the PAH Analyzer 8
A Cigarette Smoke Generator For Field Evaluations
of the PAH Analyzer 9
Effect of Operating Environment on PAH Analyzer Response 16
Aerosol Transmission Efficiency Through the PAH Analyzer
and Modification in Sampling Configuration 19
PAH Analyzer Response to Non-PAH Laboratory Test Aerosols ... 24
Field Study and Intercomparisons 25
5. Results and Discussions 28
PAH Analyzer Response to 2- to 4-Ring PAH Vapors 28
Noise and Ozone Output of the PAH Analyzer 30
A Cigarette Smoke Generator for Field Evaluations of
the PAH Analyzer 36
Effect of Operating Environment on PAH Analyzer Response 42
Aerosol Transmission Efficiency Through the PAH Analyzer
and Modifications in Sampling Configuration 49
PAH Analyzer Response to Non-PAH Laboratory
Test Aerosols 59
Field Study and Intercomparisons 64
References 84
Appendix A 86
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FIGURES
Number
Page
4.1 Schematic of the vaporizer used to generate PAH vapors
in the chamber 7
4.2 Schematic of the locations of the PAH analyzer selected
for O3 monitoring , JQ
4.3 Schematic diagram of the various components of the
cigarette smoke generator designed for field evaluations
of the PAH analyzer -. 12
4.4 Schematic of the control (front) panel of the
cigarette smoke generator 13
4.5 Schematic of the test set-up used in the laboratory
evaluations of the cigarette smoke generator 15
4.6 Schematic of the test set-up used in the
temperature/humidity tests 17
4.7 Schematic of the monodisperse aerosol generation system
used to evaluate the PAH analyzer 20
4.8 Schematic layout of the PAH analyzer showing the various
sampling locations used in the aerosol transmission efficiency
** 23
4.9 Schematic of the PAH air sampling train used in the
pilot field study 26
5.1 PAH analyzer and CNC response profiles (upper graph) during
the addition of phenanthrene,. pyrene and fluoranthene vapors
to the atmospheric chamber; lower graph shows the PAH vapor
concentration profiles 29
vin
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FIGURES (continued)
Eags
Number
5.2 Noise spectrum measured at a distance of 1 m from the PAH
analyzer; also shown are the noise spectra represented by
various noise criteria 31
5.3 Comparison of the noise levels resulting from operation of
the PAH (1-m distance) analyzer with typical indoor
annoyance levels 33
5.4 Profiles of the response of the CNC and the PAH analyzer to
cigarette smoke generated in five consecutive runs 38
5.5 Scatter-plot of pairs of PAH analyzer response and CNC number
concentrations from five consecutive cigarette burn runs 39
5.6 Frequency distribution of PAH analyzer responses over the
12-15 min test intervals in each of the five cigarette runs.
Also shown is the frequency distribution for the composite of
data from all five runs 40
5.7 Response of the PAH analyzer to a temperature-equilibrated
cigarette smoke aerosol under baseline test conditions 44
5.8 Response of the PAH analyzer to a high temperature-
equilibrated cigarette smoke aerosol 46
5.9 Response of the PAH analyzer to a low temperature-
equilibrated cigarette smoke aerosol 47
5.10 Comparison of the response of the PAH analyzer as a function
of particle number concentration to cigarette smoke aerosol at
various sampled air temperatures 48
5.11 Results of aerosol transmission efficiency tests conducted
with monodisperse NaCl test aerosols 50
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FIGURES (continued)
Number
Eagfi
5.12 Response profile as a function of time for each of the three
PAH analyzers and the number concentration measured by
the CNC - first test conducted in Battelle's cafeteria
(smoking environment) .......... , 53
5.13 Response profile as a function of time for each of the three
PAH analyzers and the number concentration measured by
the CNC second test conducted in Battelle's cafeteria
(smoking environment) , 55
5,14 Response profile as a function of time for each of the three
PAH analyzers and the number concentration measured by
the CNC cigarette smoking in close proximity to samplers;
conducted subsequent to second test hi Battelle's cafeteria 57
5.15 Calculated increase in analyzer response as a result of the
modification in sampling configuration; top graph represents
the sampling period shown in Figure 5.13; the bottom graph
refers to the sampling period shown in Figure 5.14 58
5.16 Normalized PAH analyzer response to monodisperse test
aerosols of various substances generated from nebulizing
water and IPA solutions; also shown is surface area as a
function of particle size 61
5.17 Response of the PAH analyzer during the 24-h sampling period
in H01RS . 75
5.18 Response of the PAH analyzer during the 24-h sampling period
in H02RN 1 76
5.19 Response of the PAH analyzer during the 24-h sampling period
in H03RN 77
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FIGURES (continued)
Number Eagg
5.20 Response of die PAH analyzer during the 24-h sampling period
in H04RS 78
5.21 Response of the PAH analyzer during the 24-h sampling period
in H05RS 79
5.22 Response of the PAH analyzer during the 24-h sampling period
in H06RS . 80
5.23 Response of the PAH analyzer during the 24-h sampling period
in H07RN .81
5.24 Response of the PAH analyzer during the 24-h sampling period
in H08RN 82
XI
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TABLES
Number
4.1 Summary of chamber conditions during the PAH
vapor response tests ....... . ..................... ...... 9
4.2 Electrostatic classifier operating parameters ..................... 21
5.1 Ozone concentrations measured at various locations near the
PAH analyzer and in indoor air ............................ 34
5.2 Characteristics of the log-normal frequency distributions
of PAH analyzer response to cigarette smoke in five
consecutive cigarette burns ............................... 41
5.3 Measured PAH and alkylated PAH concentrations in the air
in home H01RS ............................... . ...... 65
5.4 Measured PAH and alkylated PAH concentrations in the air
in home H02RN ..... ................................ 66
5.5 Measured PAH and alkylated PAH concentrations in the air
in home H03RN ..................................... 67
5.6 Measured PAH and alkylated PAH concentrations in the air
in home H04RS ......................... ............. 68
5.7 Measured PAH and alkylated PAH concentrations in the air
in home H05RS ...................................... 69
5.8 Measured PAH and alkylated PAH concentrations in the air
in home H06RS ...................................... 70
5.9 Measured PAH and alkylated PAH concentrations in the air
in home H07RN ..................................... 71
Xll
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TABLES (Continued)
Number
5.10
5.11
5.12
Measured PAH and alkylated PAH concentrations in the air
in home H08RN
Measured PAH and alkylated PAH concentrations in the
field blank sample
Comparison of fine particulate-bound PAH concentrations
measured from the integrated samplers and corresponding
average responses from the PAH analyzer
72
73
83
Xlll
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ACKNOWLEDGEMENT
The authors are grateful to Dr. Nancy K. Wilson, Project Manager of the U.S.
Environmental Protection Agency, for her invaluable advice during this investigation.
Technical assistance provided by David B. Davis, Patrick J. Gallahan, Donald V. Kenny,
Larry W. Miga, Jan Satola and Dr. Chester W. Spicer of Battelle is also greatly appreciated.
xiv
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SECTION 1
INTRODUCTION
The real-time PAH analyzer evaluated in this study was a Model PAS lOOOi
Photoelectric Aerosol Sensor manufactured by Gossen, GmbH (Erlangen, Germany) and
obtained in the United States with ancillary data acquisition software from Eco Chem
Technologies, Inc. (West Hills, CA). Two newer versions, Model 1002i, of the PAH
analyzers were purchased from Eco Chem and were also evaluated in this study. The PAH
analyzer is based on the principle of photoelectric ionization of PAH adsorbed on the surface
of aerosol particles1"4, and is discussed in detail in an earlier Battelle study report5.
The earlier evaluation study conducted by Battelle5 showed that the PAH analyzer is
capable of providing a real-time (<5 sec) response that is correlated with indoor fine
particulate-phase PAH (<2.5 /tm), and does not respond to 2-ring PAH vapors. The PAH
analyzer did, however, show a small but non-negligible response to non-PAH, sodium
chloride (NaCl) test aerosol. These results suggested that the PAH analyzer had the potential
for screening and semi-quantitative measurement of human exposure to PAH in indoor and
ambient air, and as an indicator of activities that lead to PAH exposure. Further, the results
from the previous evaluation study suggested the need for additional investigations to obtain a
better understanding of the nature of operation and response of the PAH analyzer.
Accordingly, the following six major objectives were established for this follow-up
evaluation study: (1) to determine whether the PAH analyzer responds to a number of
different 2- to 4-ring PAH vapors, (2) to measure the noise and ozone (O3) output of the
PAH analyzer, (3) to develop a cigarette smoke generator capable of use in field evaluations
of the PAH analyzer, (4) to determine the effects of operating environment, specifically
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temperature and humidity, on the .response of the analyzer, (5) to systematically investigate
aerosol transmission through the various components of the PAH analyzer and to evaluate if
transmission efficiency can be improved through modifications in the analyzer's sampling
flow path, (6) to further investigate the previously identified (but unexplained) response of
the analyzer to non-PAH aerosols, and (7) to conduct a field study to compare the PAH
analyzer's response with PAH concentrations determined by air sampling followed by
GC/MS analysis.
The above objectives were accomplished in this study in seven separate and
corresponding tasks, summarized as follows:
Task 1: PAH analyzer response to 2- to 4-ring PAH vapors
Noise and ozone output of the PAH analyzer
A cigarette smoke generator for field evaluations of the PAH analyzer
Effect of operating environment on PAH analyzer response
Aerosol transmission efficiency through the PAH analyzer and
modifications in configuration
PAH analyzer response to non-PAH laboratory test aerosols
Field study and intercomparisons
Task 2:
Task 3:
Task 4:
Task 5:
Task 6:
Task?:
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SECTION 2
CONCLUSIONS
The conclusions from each task of this study are summarized as follows:
Task 1: The PAH analyzer does not yield a response to 2- to 4-ring PAH vapors
including naphthalene, 1-methylnaphthalene, chloronaphthalene,
phenanthrene, and fluoranthene. A small signal (0.008 p Amp) was
observed for pyrene vapor at 3 ppb, when 50-60 particle/cc were also in
the chamber. This response, however, is probably due to the condensation
of vapor-phase pyrene on particle surfaces.
Task 2: The noise level from the PAH analyzer was generally below the NC-35
criterion, except at frequencies of 1000, 2000, and 4000 Hz where the
noise level were close to NC-40 criterion. The sound level from the PAH
analyzer is between the levels in typical private homes and those typically
recorded in large offices. The operation of PAH analyzer did not result in
a significant contribution to indoor O3 concentrations.
Task 3: The cigarette smoke generator designed and fabricated is capable of
providing field verifications of the performance of PAH analyzers.
Despite the inherent variability in the cigarette combustion process, the
smoke generator elicits a reasonably characteristic frequency distribution of
PAH analyzer during a cigarette test. Parameters that characterize this
frequency distribution can then be compared with nominal ranges to verify
operation in the field. Additionally, the response of the analyzer was
found to be well-correlated with the number concentration of the cigarette
smoke.
Task 4: Elevated or depressed temperature and humidity operating conditions do
not have a significant impact on the response of the PAH analyzer to a
cigarette smoke aerosol equilibrated at the test temperature. The response
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of an analyzer operated at typical room conditions does appear to increase,
relative to particle number concentration, as a function of the sampled air
temperature. The mechanism for this increase in the response is not
clearly established at the current time.
Task 5: Aerosol transmission efficiency tests showed that the PAH analyzer, in its
original design configuration, had significant aerosol losses in the sUicone
tubing and Electrofilter, particularly at particle sizes < O.lpm in diameter
where aerosol transmission efficiency was <70%. A modified
configuration, consisting of by-passing the Electrofilter and using stainless
steel tubing provided > 90% transmission efficiency for all test aerosols,
ranging in monodisperse size from 0.034 - 0.32 /*m. Field trials in
various indoor environments indicated no deleterious effects on overall
analyzer performance as a result of the modified design configuration.
Under typical indoor conditions in both ETS and non-ETS environments,
an improvement in the sensitivity of the analyzer was also observed.
Task 6: The analyzer's response to non-PAH test aerosols, normalized to aerosol
number concentration, was proportional to particle surface area for sodium
chloride, ammonium sulfate and phthalic anhydride aerosols generated
from drying nebulized water solutions of the respective compounds. The
response was reproducible and largely consistent between the different test
aerosols. The analyzer's corresponding response to phthalic anhydride and
di-octyl phthalate aerosols generated from drying nebulized iso-propyl
alcohol (IPA) solutions was considerably smaller and did not exhibit as a
strong a proportionality with test aerosol surface area. These results
suggest that the analyzer's response may be related to contaminants in the
solvents (water or IP A) used to make the nebulized solutions. These
contaminants may be deposited on the surface of the test aerosol when the
solvent evaporates from the nebulized droplets, thereby causing the
observed analyzer response. A definite determination of the nature and
origin of this contamination could not be achieved in this study.
Task 7: Fine particle PAH concentrations in indoor air, measured from integrated
sampling and GC/MS analysis, from eight homes ranged from 27 to
120 ng/m3. These measured PAH concentrations were within one-fifth to
two-times of the average responses of the PAH analyzer. The PAH
analyzer's average response in these tests was calculated using the
manufacturer's suggested calibration constant of 3000 ng/m3 per pAmp of
electrometer signal.
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SECTION 3
RECOMMENDATIONS
Our recommendations, based on the results obtained in this study are as follows:
(1) The current sampling configuration employed in the PAH analyzer is not conducive to
representative aerosol sampling. A modified sampling configuration has been
developed and tested in this work. The modification consists of by-passing the
Electrofilter in the analyzer and using a stainless steel tube to replace the silicone
tubing presently in the analyzer. Field tests have demonstrated that no deleterious
effects arise from the modification. We recommend that the analyzer be modified for
use in indoor particulate PAH monitoring/screening applications. Some additional
work may be necessitated by the modification, including the development of a revised
calibration factor. Establishment of revised baseline parameters for field verification
using the cigarette smoke generator will also be necessary.
(2) The observed response of the PAH analyzer to laboratory generated non-PAH aerosols
may be further studied using test aerosols generated using alternative approaches that
. do not involve spray drying. For example, sulfate aerosols could be generated in a
smog chamber or (non-combustion) "smoke" could be generated from chemical
reactions. The aerosols generated from these methods may be more similar to the
aerosols present in indoor air than those generated by spray drying.
(3) We also recommend that a study be conducted to determine the indirect (+S9) and
direct (-S9) mutagenicity of the air sampling extracts generated from this study. Since
we used less than 10% of each sample extract for PAH analysis, the remaining sample
extract can be used for bioassay analysis. We propose to determine the residue weight
of each sample extract and then develop a dose level for each sample extract for
bioassay. Each sample will be solvent exchanged into dimethylsulfide (DMSO) at a
designated dose level and then submitted for bioassay. The mutagenicity assays will
then be compared with the measured PAH concentrations an the PAH analyzer's
response. The results will provide us with information on whether the analyzer can be
used as an indicator of mutagenic activity in the air.
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SECTION 4
EXPERIMENTAL PROCEDURE
PAH ANALYZER RESPONSE TO
2- TO 4-RING PAH VAPORS
This task involved spiking target chemicals into a 17 m3 environmental chamber,
monitoring the spiked chemical vapors in the chamber by a Trace Atmosphere Gas Analyzer
(TAGA) mass spectrometer, monitoring the particle concentration using a condensation
nucleus counter (CNC), and sampling the spiked chemical vapors by the PAH analyzer.
The following PAH compounds were tested in the chamber experiments: benzene,
p-dichlorobenzene, naphthalene, 1-methylnaphthalene, 1-chloronaphthalene, indene,
quinoline, phenanthrene, fluoranthene, and pyrene. An aliquot of each of these chemicals,
other than 3- to 4-ring PAH was injected either as neat chemical or dissolved in
dichloromethane (DCM) and injected into the chamber through a heated injection port. For
the 3- to 4-ring PAH compounds, phenanthrene, fluoranthene, and pyrene, a standard
solution of each compound was prepared in hexane, The standard solution was injected into
the chamber through a Battelle-developed vaporizer, shown schematically in Figure 4.1.
Prior to injection of each compound, the chamber was flushed with purified air. AADCO
zero air was used for all of the tests. Sampling lines connected the chamber to (1) the
TAGA for monitoring the vapor concentration of the spiked chemicals in the chamber, (2)
the PAH analyzer for sampling chamber air containing the PAH vapor, and (3) a TSI
Model 3020 condensation nucleus counter (CNC) for monitoring the particle number
concentrations in the chamber. The TSI Model 3020 CNC has a particle size range of
sensitivity of 0.01 - 0.5
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The TAGA was equipped with an atmospheric pressure chemical ionization (APCI)
source, operated in the single mass spectrometry mode (MS) utilizing selected ion
monitoring. The chamber air was sampled by the TAGA at a flow rate of IS L/min. In the
tests with benzene, quinoline, and 2-ring PAH, the TAGA used the ambient water vapor in
the air to form protonated water clusters which then protonated the compound of interest.
The protonated molecular ions (M+l+) of each spiked chemical were monitored in the
TAGA by the first quadrupole (Ql) mass analyzer, and all ions passed the second (Q2) and
the third (Q3) «iass analyzers.
In order to increase the sensitivity of the TAGA for the 3- to 4-ring PAH, benzene was
used as the reagent gas and the mode of ionization was via charge exchange for these tests6.
The molecular ions, (M+), of each spiked 3- to 4-ring PAH were monitored in the TAGA by
the first quadrupole (Ql) mass analyzer, and all ions passed the second (Q2) and third (Q3)
mass analyzers. Individual standards of each PAH were prepared in hexane and injected into
the TAGA airstream via the vaporizer described above. The response factor (response =
average ion counts per second/unit of concentration) for each chemical was determined from
analyses of the standard solutions. The concentration of the spiked chemical in the chamber
air was then determined based on the response factor. Table 4.1 summarizes the chamber
conditions for each test.
NOISE AND OZONE OUTPUT
OF THE PAH ANALYZER
The noise measurements were conducted in a basement of a home to obtain the lowest
possible background noise levels. Noise measurements were conducted at distances of one
and two meters from an operating PAH analyzer and flat-weighted octave-band sound
measurements were conducted at frequencies ranging from 30 - 16,000 Hz for comparisons
with the NC-35 criterion. Noise measurements using an A-weighted network were also made
to more closely reflect human audiometric responses.
8
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TABLE 4.1. SUMMARY OF CHAMBER CONDITIONS DURING THE PAH
VAPOR RESPONSE TESTS.
Test No.(«>
1
2
3
4
5
6
7
8
9
10
Spiked Chemical
Benzene
p-Dichlorobenzene
Naphthalene
1-Methylnaphthalene
1-Chloronaphthalene
Indene
Quinoline
Phenanthrene
Fluoranthene
Pyrene
Humidity
%
80
80
80
80
80
80
80
34
34
34
Temperature
°C
25
25
25
25
25
25
25
24
24
24
Measured
Concentration
ppb
500
300
300
300
1,000
400
40
15
1.3
3.8
(a) The particle counts in the chamber for these tests ranged from 50-90 particles/cc.
To determine if operation of the PAH analyzer contributes significantly to ozone (O3)
levels in air, the O3 concentration was monitored at various distances and locations around
the PAH analyzer using an U.V. Photometric O3 analyzer (Thermo Electron Instruments,
Model 49). Figure 4.2 shows a schematic of the locations of the PAH analyzer selected for
O3 monitoring.
A CIGARETTE SMOKE GENERATOR
FOR FIELD EVALUATIONS OF THE
PAH ANALYZER
The evaluations to be conducted of the PAH analyzer using the aerosol generator were
to be limited to verifying the general operation of a PAH analyzer unit in the field. Thus,
the aerosol generator was required to be portable, self-contained and of minimum complexity
to permit use by a field technician. The most convenient means of generating a PAH aerosol
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Figure 4.2 Schematic of the locations of the PAH analyzer selected for O, monitoring.
10
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for field evaluation of the PAH analyzer is through the combustion of a cigarette. A portable
and self-contained cigarette smoke generator was therefore designed and fabricated in this
task.
Figure 4.3 is a schematic diagram of the various components of the cigarette smoke
generator. All internal components of the smoke generator are housed in a compact metal
box enclosure having a size of 11 "(D) x 8"(H) x 10"(W). Several key components are
placed outside the box enclosure and form the control panel of the aerosol generator. These
components include four air flow rotameter, a cigarette combustion chamber, power control
switch and outlet for the cigarette smoke output, as shown schematically in Figure 4.4.
As shown in Figure 4.3, the cigarette smoke generator uses a pump (Air Cadet, Inc.
Model 400-1911) to provide the air flow necessary for cigarette combustion, smoke dilution
and carrier air. Air is drawn from outside the box enclosure through a silica gel column
where it is dried." The air flow output from the pump is split into two streams. Each stream
passes through a carbon filter (Balston, Inc., Model DAU) and a paniculate filter cartridge
(Balston, Inc., Model DFU) for removal of organic vapors and particles. One of the two
streams is metered by a rotameter, labeled as A in Figure 4.3, and provides carrier air at a
nominal flow rate of 5 1pm. The other stream is further split into two streams each of which
are metered by a rotameter. These rotameters, labeled B and C in Figure 4.3, provide
combustion air and mixing (or dilution) air, respectively. Air from rotameter B at a nominal
flow rate of 70 cc/min enters a cylindrical cigarette combustion chamber (aluminum; 114"
o.d. x 5V4" long, placed outside the box enclosure). Inside the combustion chamber, a
cigarette held securely in a holder bums continuously using the air flow from rotameter B.
Smoke from the burning cigarette is carried through the cigarette and out of the combustion
chamber where it enters a mixing chamber (aluminum; 4" o.d. x 8" long; with a removable
end cap). In the mixing chamber, the cigarette smoke mixes with air from rotameter C
flowing at a nominal rate of 2.5 1pm.
11
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AIR IN
SUCA
GB.
CARBON PARTCULATE
0-100 CC/MIN
ROTAMETER
CAPSIZE
CIGARETTE COMBUSTION
CHAMBER
0-5LPM
ROTAMETER
=> (A)
BOX ENCLOSURE
ROTAMETTERS
(A) Carrier Air; 0 - 5 Ipm; set to 5 Ipm nominal
(B) Cigarette Smoke Combustion Air; 0 -100 cc/min; set to 70 cc/min nominal
(C) Mixing Air; 0 - 5 Ipm; set to 2.5 Ipm nominal
(D) Calibration Smoke Feed; 0-50 cc/min; set to 25 cc/min nominal
Figure 4.3. Schematic diagram of the various components of the cigarette smote
generator designed for field evaluations of the PAH analyzer.
12
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CARRIER CIGARETTE
AIR
AIR
CALBRAT1ON MXING
SMOKE AIR
FEED
CIGARETTE
COMBUSTION
CHAMBER
Figure 4.4. Schematic of the control (front) panel of the cigarette smoke generator.
13
-------
The diluted cigarette smoke exits the mixing chamber through a single port with two
flow paths. The major flow path passes through an adjustable ball valve and a HEP A
capsule filter (Gelman, Inc., Model 12144) where the cigarette smoke is filtered before the
air flow is vented. The other flow path passes through rotameter D at a nominal flow late of
25 cc/min. This small fraction of cigarette smoke from the mixing chamber enters the
carrier flow stream from rotameter A. Carrier air flow mixed with cigarette smoke aerosol
is then available for sampling by the PAH analyzer. Other particle sensing instruments such
as a Condensation Nucleus Counter (CNC) can also sample the cigarette smoke output.
A series of laboratory tests was conducted to evaluate the cigarette smoke generator
and to determine an optimum set of operating parameters. The nominal rotameter flow rates
shown in Figure 4.3 were derived from these tests.
The response of the PAH analyzer to cigarette smoke is determined largely by the
concentration of cigarette smoke in the air sampled by the PAH analyzer. The cigarette
smoke concentration in the carrier air is a function of the four rotameter flow settings. A
PAH analyzer response of 0.3-1 pA was established as the design target for field evaluation
purposes. The cigarette smoke concentration required for this range Of PAH analyzer
response was men obtained by selecting an appropriate combination of the four air flow
rates.
The test set-up used in the laboratory evaluations is shown schematically in Figure 4.5.
Cigarette smoke from the generator was sampled simultaneously by the PAH analyzer and a
TSI Model 3020 CNC. The response of both instruments was recorded using a datalogger
(Rustrak Inc., Model Ranger II) at 10 second intervals for the duration of each cigarette
bum. A single cigarette burn ran for a period of about 12-15 minutes.
Research cigarettes from the University of Kentucky were used in the tests. A few
runs were also conducted using a commercial brand (BASIC) of cigarettes. However, the
smoke particle concentrations from the combustion of commercial cigarettes were found to be
14
-------
GOSSEN
PAS 10001
CIGARETTE
SMOKE
GENERATOR
-5.0 Ipm
-3 Ipm
_v. Excess
Vent
-0.3 Ipm
TSI
3020 CNC
Figure 4.5 Schematic of the test set-up used in the laboratory evaluations of the
cigarette smote generator.
15
-------
significantly more variable than those from the research cigarettes. Specifically, high particle
number concentration peaks of short time duration were frequently observed from the
commercial cigarettes; such peaks were relatively infrequent from the research cigarettes.
A series of tests were conducted using the cigarette smoke generator. Initially, the net
charge on the cigarette smoke aerosol was determined using the electrometer in the PAH
analyzer (Electrofilter and UV lamp OFF; see Chuang and Ramamurthi, 1993).
Subsequently,- the response of a fully-functional PAH analyzer to test aerosols generated
using the smoke generator was determined in a series of repetitive tests.
EFFECT OF OPERATING ENVIRONMENT
ON PAH ANALYZER RESPONSE
The temperature/humidity tests were conducted in a systematic manner using the
cigarette smoke generator set-up described above and a laboratory environmental test
chamber. A schematic diagram of the experimental test set-up used in the
temperature/humidity tests is shown in Figure 4.6. The environmental test chamber was
maintained at three different conditions during the tests: 20*C, 50% R.H.; 45*C, 30%
R.H.; and 3"C, 80% R.H. The aerosol output of the cigarette smoke generator was
transported into the chamber where it first passed through a cylindrical tube (14 in. long, 1
in. i.d.), half-filled with silica gel, lying on its side in the chamber. As the cigarette smoke
aerosol flow passed over the silica gel it was de-humidified to prevent condensation of water
vapor in the transport lines. Note that although the carrier air used in the cigarette smoke
generator is dried by passage through a silica gel column prior to use, water vapor absorbed
in the tobacco can enter the flow stream as a result of the combustion of the cigarette.
The de-humidified aerosol flow then passed through a 12 ft. long copper coil for
temperature equilibration. Upon exiting the copper coil the aerosol flow was split into three
portions, one was drawn by the PAH analyzer, the other by a TSI Model 3020 Condensation
Nucleus Counter (CNC), and the third consisting of excess air was exhausted in a ventilated
16
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Cigarette Smoke
Generator
Exhaust
Insulated lines
Gossen PAS
(outside chamber;
room temperature)
Environmental Test Chamber
Controlled temperature and humidity
Silica gel drying
tube
Datalogger
Copper
coil
i Gossen PAS
* (inside chamber)
Figure 4.6 Schematic of the test set-up used in the temperature/humidity tests.
17
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hood. The CNC was always operated outside the chamber, while the PAH analyzer was
operated either inside or outside the chamber for comparative analyses. All aerosol flow
transport lines outside the chamber to the CNC and PAH analyzer (the latter when operated
outside the chamber) were insulated with polyurethane foam tube-sheathing. The residence
time of the cigarette smoke aerosol inside the chamber was on the order of about 2 seconds.
A datalogger was used to record the data collected from the tests, consisting of the particle
concentration (CNC) and analyzer signal (PAH analyzer) readings recorded at 10 second
intervals over run durations of 10-15 minutes each. Each run corresponded to the duration
of a single cigarette burn in the smoke generator and 2-3 runs (or burns) were conducted in
each of the test configurations described below.
Three sets of experiments were conducted :
Baseline Tests:
The base-line response of the PAH analyzer and CNC to de-humidified cigarette smoke
aerosol was determined by equilibrating the aerosol at a temperature of 20"C. The PAH
analyzer was also equilibrated by operation inside the chamber at 20 *C and 50% R.H. for ~2
hours prior to the tests.
Low-Temperature Tests:
The low temperature tests consisted of two parts: In the first, the PAH analyzer and
the CNC were operated outside the test chamber at room temperature (~25'C, 60% R.H.) and
sampled smoke aerosol equilibrated at a temperature of 3*C. In the second part, the PAH
analyzer was placed inside the chamber at 3*C and 80% R.H. and operated for a period of
about 2 hours before sampling the low temperature-equilibrated cigarette smoke aerosol.
High-Temperature Tests:
The high temperature tests were conducted using the two-part procedure described
above for the low temperature tests. The cigarette smoke aerosol was equilibrated at a
temperature of 45 *C. When operated inside the chamber, the PAH analyzer was equilibrated
18
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at 45 *C and 30% R.H. for about 2 hours prior to sampling the high temperature-equilibrated
aerosol.
AEROSOL TRANSMISSION EFFICIENCY
THROUGH THE PAH ANALYZER AND
MODIFICATIONS IN SAMPLING CONFIGURATION
Aerosol transmission efficiency tests were conducted using monodisperse sodium
chloride (NaCl) test aerosols. A schematic diagram of the experimental test set-up is shown
in Figure 4.7. A polydisperse NaCl aerosol was generated using a constant output atomizer7
and a concentration of 1.0 g NaCl// in water. The polydisperse aerosol generated from the
atomizer has a log-normal droplet distribution, with dm~ 0.65 fim and
-------
as
£
I:
I
2
i
3?
1
u
§
t^
*
a
S
[L,
20
-------
TABLE 4.2 ELECTROSTATIC CLASSIFIER OPERATING PARAMETERS
Folydisperse and
Monodisperse Flow
Rates (1pm)
4.0
4.0
4.0
4.0
4.0
Sheath and
Excess Flow
Rates (Ipm)
20
20
20
20
10
Collector Rod
Voltage
(V)
467
12%
3600
10000
10000
Monodisperse
Particle Size
G*m)
0.034
0.06
0.11
0.20
0.32
Prior to conducting aerosol transmission efficiency tests, the performance of the EC
was verified using sub-micron Poly-Styrene Latex (PSL) test aerosols of sizes 0.06 /*m and
0.10 urn. The PSL aerosols were generated by nebulizing suspensions of monodisperse PSL
spheres in water. Performance verification experiments consisted of verifying that the
theoretically expected set of EC operating conditions (flows, collector rod voltage) indeed
resulted in the presence of the PSL test aerosol in the monodisperse flow output from the
EC. Presence of PSL aerosol in the monodisperse flow output was detected using the TSI
Model 3020 Condensation Nucleus Counter (CNC).
In addition to these verification experiments, a series of experiments was also
conducted to calibrate the CNC. The CNC requires periodic calibration with a monodisperse
test aerosol because of possible degradation of the photodetector and optics (TSI Model 3020
Instruction Manual). To calibrate the CNC, the test set-up in Figure 4.7 was used to
generate monodisperse NaCl test aerosols of 0.05 /xm diameter. The singly charged
monodisperse aerosol output of the EC was sampled by the CNC and an Aerosol
Electrometer (AE) (TSI Model 3068). Using different amounts of dilution air, monodisperse
particle concentrations in the range 1,000 - 225,000 particles/cm3 were generated. The AE
is a primary standard and its current (pA) readout allowed calculation of the particle number
concentration based on the flow rate through the electrometer. The CNC was accordingly
21
-------
calibrated by adjusting the span and zero potentiometers to provide a number concentration
display consistent with the calculated concentration from the AE. Corrections for
interference from multiply charged particles were included in performing the CNC
calibration.
The calibrated CNC was then used in tests to determine the aerosol transmission
efficiency of the PAH analyzer. As indicated in the schematic in Figure 4.7, the
monodisperse aerosol output of the EC was neutralized, diluted as necessary and passed into
a mixing chamber. The neutralized test aerosol was then sampled out of the chamber and
through the PAH analyzer using a pump external to the analyzer. The internal PAH analyzer
pump was not utilized in the tests because of its inability to maintain a constant flow under
the conditions of a positive pressure of 4-10 cm. H2O in the mixing chamber. A number of
aerosol transmission tests were also conducted using singly-charged aerosols; the mixing
chamber was not employed in these tests to minimize particle losses.
Flow through the PAH analyzer was maintained at 4.01pm using a metering valve and
was continuously monitored using a mass flowmeter. The CNC sampled the aerosol either
immediately upstream of the PAH analyzer inlet or from a specific sampling location inside
the PAH analyzer. Care was taken to use matched lengths of tubing to connect the CNC to
the two sampling locations; all tube lengths were kept to a minimum and metal tubing was
used throughout the test set-up. Figure 4.8 is a schematic of the sampling locations within
the PAH analyzer used in the aerosol transmission efficiency tests.
Modifications in sampling configuration were made in the PAH analyzer as a result of
the findings of the aerosol transmission efficiency tests. Specifically, the Electrofilter (EF)
in the PAH analyzer was by-passed and stainless steel tubing was used to connect the inlet of
the analyzer directly to the inlet of the UV ionization chamber. A series of tests were then
conducted with the modified analyzer, with the following objectives:
Test 1: Determine aerosol transmission efficiency through the modified analyzer.
22
-------
Inlet
Electrically
isolated
Connector
! ON/OFF!
PAH ANALYZER
_T
Etectrofilter(ESPh|-+465V
Photo-ionization\
chamber; UV \uvump ;oN/OFFj
Electrometer
Pump
Response
Figure 4.8 Schematic layout of the PAH analyzer showing the various sampling
locations used in the aerosol transmission efficiency tests.
23
-------
Test 2: Determine if the modified PAH analyzer is subject to errors from the
presence of non-electrically neural aerosols in typical indoor
microenvironments.
Test 3: Compare the response of the modified PAH analyzer to a collocated
original, un-modified PAH analyzer.
PAH ANALYZER RESPONSE TO NON-PAH
LABORATORY TEST AEROSOLS
The tests conducted in this follow-up study of the response of the PAH analyzer to
laboratory-generated test aerosols consisted of a more detailed and systematic version of
similar experiments conducted in the previous evaluation study5. Specifically, the
monodisperse aerosol generation scheme described in Section 4.5 was used to generate test
aerosols of various substances. The response of the PAH analyzer a function of
monodisperse particle size and number concentration was then determined using the test
aerosols.
Test aerosols were generated from the following solutions:
Sodium chloride in water
Ammonium sulfate in water
Phthalic anhydride in water
Phthalic anhydride in iso-propyl alcohol
Di-octyl phthalate in iso-propyl alcohol
The five monodisperse aerosol sizes shown in Table 4.2 were used in the experiments with
each test aerosol.
24
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FIELD STUDY AND
INTERCOMPARISONS
A small pilot field study was conducted in eight houses in Columbus, Ohio during
April, 1993. Four smokers' houses and four non-smokers' houses were selected. The
selection process of the sample houses was conducted as part of a separate and concurrent
EPA study (Work Assignment 35)9. Overall, indoor air in each house was sampled as part
of this study (Work Assignment 42) and house dust, entryway soil, pathway soil, and
foundation soil were sampled under the other study (Work Assignment 35).
An integrated indoor air sampler10 and the PAH analyzer were placed in parallel in
either the living room or family room of each house. The PAH analyzer was set up with its
inlet at about the same height and about 1 foot from the inlet of the indoor air sampler. The
sampling train for the indoor sampler consisted of the following components (listed in the
order of air flow), impactor-denuder-quartz fiber filter and XAD-2 trap, which was designed
to collect fine paniculate (<2.5 /*m) PAH in the sampled air stream. Figure 4.9 illustrates
the sampling train schematically. The impactor used in the train was an URG, Inc. Model
200-30 impactor with a characteristic aerodynamic particle cut-off diameter of 2.5 pm
(dp-50 percent collection efficiency) at a flowrate of 20 L/min11. The impactor was
operated with the impaction frit coated with silicone grease and removed all particles greater
than 2.5 ftm in aerodynamic diameter from the flow stream.
A Battelle Medium Volume Compound Annular Denuder (MVCAD)12, coated with
silicone grease using a procedure described previously13, was placed downstream of the
impactor to remove vapor-phase PAH from the air stream sampled. The MVCAD has been
demonstrated in previous studies to be highly efficient in removing vapor-phase PAH from
indoor air at the flow rates employed, while maintaining essentially 100% transmission of
fine particles in the dp <2.5 urn size range13. The fine paniculate PAH penetrating the
denuder was collected on a quartz fiber filter, with the XAD-2 resin trap downstream of the
filter used to trap PAH volatilized from paniculate PAH collected on the filter during the
25
-------
ami
URG, Inc. 2.5 \an cut
impactor (silicone coated
impaction plate)
Compound
Annular Denuder
-(Battelle MVCAD)
Silicone-coated for
PAH vapor removal
Quartz Fiber
Filter (47 mm)
XAD-2 resin
trap
Fine Particle-Bound (<2.5 pm) PAH:
Combined analysis of filter arid XAO trap
(XAD trap for PAH volatilized from particles
collected on filter)
Figure 4.9 Schematic of the PAH air sampling train used in the pilot field study.
26
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sampling period. Prior to sampling, the clean filter and clean XAD-2 trap, the impactor, and
the MVCAD were prepared by the respective methods developed by Battelle11'12. The
sampling flow rate through the sampling train was controlled at 20.0 ± 0.21pm using a
pump and a metering valve and was monitored continuously by an in-line mass flow meter.
Indoor air was sampled for a period of 24 hours at each house.
After 24-h sampling, the filter and XAD-2 trap was removed from the train and sent
back to Battelle for analysis. The corresponding filter and XAD-2 samples were combined
and extracted with DCM by the Soxhlet technique. The DCM extract was concentrated by
Kuderna-Danish (K-D) evaporation, and analyzed by gas chromatography/mass spectrometry
(GC/MS) for 2- to 7-ring PAH and their alkylated PAH.
A Finnigan TSQ-45 GC/MS/MS operated in GC/MS mode and an INCOS 2300 data
system were employed. The MS was operated in selected ion monitoring (SIM) mode.
Peaks monitored were the molecular ion peaks and characteristic fragmentation ion peaks.
The GC column was a fused silica capillary column (30 m x 0.25 mm; 0.25 pm film
thickness, Supelco). The GC temperature was held at 70°C for 2 min, programmed to
290°C at 8°C/min. Each sample extract was analyzed twice once for parent PAH analysis
and again for alkylated PAH analysis. Identification of the target analyte was based on the
GC retention time relative to the corresponding internal standards (phenanthrene-d10 and
9-phenylanthracene). Quantification of target analyte was based on comparisons of the
respective integrated ion current response of the target ion with that of the corresponding
internal standard, with the average response factor for each target analyte generated from
standard analyses14. Quantification of alkylated PAH was based on the average response
factor of the respective parent PAH.
27
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SECTIONS
RESULTS AND DISCUSSION
PAH ANALYZER RESPONSE TO
2- TO 4-RING PAH VAPORS
The objective of this task was to verify that the PAH analyzer does not respond to
PAH vapors as reported by Eco Chem Technologies, Inc. In our previous evaluation study5,
we demonstrated that the PAH analyzer did not respond to benzene and 2-ring PAH vapor at
room temperature (25°C) and low humidity conditions (9% R.H.). In the current study,
tests were conducted for ten chemicals including benzene, and 2- to 4-ring PAH (see
Table 4.1) at higher chamber humidity (34 to 80% R.H.) and room temperature (24-25°C)
conditions.
The tests conducted in this study also showed no PAH analyzer response to
vapor-phase PAH in all except two cases. In one case where a response was observed
(~0.2 p Amp) for indene, a substantial particle concentration of -50,000 particles/cc was
measured in the chamber suggesting that the observed PAH analyzer response was due to the
adsorption of vapor-phase indene onto particle surfaces. The particle formation observed
was traced to the polymerization of the aged indene liquid used in the test, as described in
the Merck Index.
In the other case, a small signal (0.008 p Amp) was observed at a pyrene vapor
concentration of 3.8 ppb, with a corresponding particle concentration in the chamber of 60-
75 particles/cm3. A detailed presentation of the results of the latter test, which also included
the addition of phenanthrene and fluoranthene vapors, is shown in Figure 5.1. The upper
graph in Figure 5.1 shows the response of the PAH analyzer and the CNC to air sampled
28
-------
PAH Analyzer Response (pA)
g S S
PAH Vapor Concentration from TAGA
(ppb)
§
1
8
o
. o
f o
(qdd)
VOV1 UJQJJ uoiiEJiuaouoo jodeA HVd
29
-------
from the test chamber as a function of time after the addition of phenanthrene, pyrene
and fluoranthene vapors. The lower graph in the figure shows the vapor concentration of
each of these vapors in the chamber as measured by the TAGA.
The results in Figure 5.1 clearly demonstrate that no response was observed from the
PAH analyzer to air containing 10 ppb of phenanthrene vapor. However, in the next phase
of the test, when pyrene vapor was added to the chamber, a very small but clearly
observable response was observed from the PAH analyzer. The response profile as a
function of time corresponding very closely with the pyrene vapor concentration profile, and
exhibited a similar decay as the concentration profile. This small response is likely a result
of the condensation of pyrene on existing particles in the chamber because of its low
saturation vapor pressure. About 60-75 particles/cm3 were present in the chamber during the
tests. The addition to the chamber, in the final phase of the test, of fluoranthene vapor did
not elicit a response from the PAH analyzer at levels up to 1.5-2.0 ppb of the PAH vapor.
In summary, the PAH analyzer did not yield any response for vapors of benzene, and
2- to 4-ring PAH at room temperature under both low and high humidity (9 to 80% relative
humidity).
NOISE AND OZONE OUTPUT OF
THE PAH ANALYZER
The objective of this task was to determine the noise and ozone output from the
operation of the PAH analyzer. Figure 5.2 shows the noise levels at various frequencies
measured at a distance of one meter from the PAH analyzer and the corresponding levels
represented by the NC-30, NC-40, and NC-50 criteria. As shown in Figure 4.1, the noise
levels from the PAH analyzer were generally below the NC-35 criterion except at
frequencies of 1,000, 2,000, and 4,000 Hz where the noise levels were close to the NC-40
criterion. The increased sound levels at these frequencies are most likely due to the
high-pitched sound emitted by the mini-pump in the PAH analyzer. The measured sound
30
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Noise Spectrum for
PAH Analyzer
100 1000 10000
Frequency (Hz)
100000
NO 30
IMC-40
NIC-50
PAH Analyzer
Figure 5.2 Noise spectrum measured at a distance of 1 m from the PAH analyzer; also
shown are the noise spectra represented by various noise criteria.
31
-------
levels did not drop off significantly at a distance of two meters from the analyzer compared
with the measured level at a distance on one meter.
Figure 5.3 shows a comparison of the A-weighted noise levels measured at a distance
^ » - - ' -,!-» * . j_ * k- *># it-:.-i. **.'. .--.-.,»*" ,» j, ' '". -U ,_#?.- --.: >* t .':-;:>- ','^'ti- ^i*., "' *w»V s^-A-Ml^l'i",* V.-V, KfW^,, » K;---*, "vi^i ,*"'* t*
of one meter from the PAH analyzer and the corresponding levels typically present in various
" . * ---*** ,-»* .[Li » -i-- -,.. -u-^i »-,j*. us. A *C1v .. ... .Wkji* ->,. .^,.^ ;.*,.-,,*< i'. 4.' 1J » *- ,,~*,i^V.i.- «f *- "- '.V ^7'A*»,i-w ' i . » ' -,7* T -t . ,, L-» . ,
indoor micrpenvironments. The sound level from the operation of the PAH analyzer is in
between that found in typical private homes and large offices.
. w- - -_ -* *.. -"-' i»* .- , . in, A, j. - . _,: ,.j.-..» . Jf-,. <«, S-»B, ,»i«^kj*<;;r ;»,. ,_,, ,,.;.:
Ozone (O3) concentrations were also monitored at various locations from the PAH
. - '- , - ^ ,. " «,-.,.!. ;. .,.».,«. f, - *r u, iff »!'** *nr.». *«, .,,*h, .,.«-. B^i >* .*,. w< «**! n -&»H~ -JL-^WH, r< f JiL-..^^Vf-^Js.-* - i : .*, , ^ -!li,,.', *-»» (r»ft '. :, ~fl^ ,
analyzer when the analyzer was in pperatipn (see Figure 4.2). Table 5.1 summarizes the §3
i i i « -i . w *" ^
measured concentrations at these various locations. As shown in Table 5.1, the operation of
S'jt * . *V r -.,-.'., .*...*..«. ,«-.,.. J> =_ « a. n.,** .j.m.J "«*««*.* »,« 1 JS'*>' * fc' KWi'l-H, "' s ** A!jM *.*»>. ' iV « .r. ^. iff 6J*,i.".11 ».. JT^, ..-. ^v.' . . ' ",*i "i '
the PAH analyzer did yield slightly higher O3 cpneenfrations ([1^-180 ppb), than tiipje
typically found indoor air, at location $. ]Lpcatipn 6 is located at thf upper left corner of the
instrument (see Figure 4.2), and in close proMmity to tiie analyzer's pump outlet. Ho,weyer,
the O3 concentrations decreased to typical indoor levels (20 ppb) at distance of 1 inch
** - ... ~ ..* -- - -^ .-.-...-.. 4. - .Jf.'^M,,, * .._., *j^ ,,,« . ^iu.^ > " vu, ^ rrJCT., V it.,, u-hrf^^A/.j.-..^!. C* IT. ...ivfe^,
above location 6, suggesting that the overall ozone emission ratg is npt yery significant. The
O3 concentrations measured at other locations were generally within thp range of ipdopr O3
levels. Therefore, we conclude that the pperatipn of the PAH analyzer in indoor
environments will not contribute significantly to indoor O3 levels.
32
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Auditoria
Private Home
PAH Monitor
Large Office
COMPARISON OF PAH
MONITOR vs INDOOR
NOISE ANNOYANCE
LEVELS
A-weighted
Sound Level
(dB)
Figure 5.3 Comparison of the noise levels resulting from operation of the PAH
(1-m distance) analyzer with typical indoor annoyance levels.
33
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TABLE 5.1. OZONE CONCENTRATIONS MEASURED AT VARIOUS
LOCATIONS NEAR THE PAH ANALYZER AND IN INDOOR AIR
Location
Room air 2 ft from case
Instrument turned on
12 inches from case
Position #1
To position "#2
To position #3
To position #4
To position #5
Back to position #4
To position #6
To position #7
To 12 inches from case
Turned instrument around
12 inches from case
To position #1
To position #2
To position #3
To position #4
To position #5
To position #6
To position #7 -
To position #8
Back to position #6
Moved sampling line closer to opening in case
Concentration, ppb
9.2
9.8
9.7
40,3
13.6
15.0
159.2
38.7
98.0
31.3
9.4
11.3
15.9
20.9
18.0
23.1
101.4
153.3
160.9
29.1
38.4
185.5
(continued)
34
-------
TABLE 5.1. (continued)
Location
Concentration, ppb
Turned off hoods and air conditioning to stop
air movement in room
6 inches from case opposite top
6 inches above top and side
To 3 niches
To 1 inch
1 inch above and 1 inch from side
Below and under 1/2 inch
To position #6 under lip
Hoods and air conditioning back on
To position #6
To 1 inch above position #6
To room air 2 feet from case
To another part of room away from instrument
To outside air
179.8
21.3
24.9
33.9
42.9
35.7
19.2
116.6
118.5
189.0
22.2
20.3
21.0
53.3
35
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A CIGARETTE SMOKE GENERATOR FOR
HELD EVALUATIONS OF THE PAH ANALYZER
The purpose of this task was to design, fabricate and test a cigarette smoke generator
capable of use in field evaluations of the Gossen PAS Model 1000L A standard protocol
describing the application of the aerosol generator for field evaluation of the PAH analyzer
was also developed. The evaluations to be conducted of the PAH analyzer using the aerosol
generator were to be limited to verifying the general operation of a PAH analyzer unit in the
field. Thus, the aerosol generator was required to be portable, self-contained and of
minimum complexity to permit use by a field technician.
Since the PAH analyzer could potentially respond to an electrically charged (net
charged) aerosol as well as particulate PAH, an initial series of exploratory tests was
conducted with the output of the smoke generator. In the first series of tests, the PAH
analyzer was operated in a mode where the Electrofilter and UV lamp were both turned off
(see Chuang and Ramamurthi, 1993 for details). In this mode, the PAH analyzer is
essentially an aerosol electrometer and measures the net charge on the sampled aerosol. The
response of the PAH analyzer in this mode to sampled cigarette smoke aerosol was at all
times within 0.000 ± 0.005 pA. This result indicates that the cigarette smoke output from
the smoke generator is essentially net neutral in charge. In a second series of tests, the
electrofilter was turned on but the UV lamp remained off. In this mode, some fraction of
the charged particles are removed by the electrofilter but no photoemission can occur within
the PAH analyzer. Again, the response of the PAH analyzer electrometer was within 0.000
± 0.005 pA at all times. This result indicates that the operation of the PAH analyzer
electrofilter does not cause a net charge to form in the sampled cigarette smoke aerosol. The
zero response of the PAH analyzer in both these test modes confirmed the acceptability of
the smoke output for evaluating the response of the PAH analyzer to particulate PAH.
36
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Cigarette smoke from the smoke generator was then used in a series of tests with the
PAH analyzer in its normal operating mode. The results of these runs, conducted using the
optimized set of flow rates, are presented in Figure 5.4. The figure shows the responses of
the CNC and PAH analyzer in five consecutive runs using research cigarettes burnt in the
smoke generator. Figure 5.4 reveals that the cigarette combustion process results in a time-
varying smoke concentration. This variability in the smoke concentration is to a large extent
a result of the inherently uneven process of cigarette combustion. The cigarette bum rate
may be affected by a number of parameters such as tobacco packing density and humidity.
In addition, the use of rotameters limits the degree of control on the air flows through the
smoke generator. However, rotameters were the only practical option available to us in
developing an economical and portable smoke generator. Thus, the degree of stability in
cigarette smoke concentration shown in Figure 5.4 is probably the best that can be achieved
without adding to the complexity of the smoke generator or its operating requirements.
The results in Figure 5.4 also show that the response of the PAH analyzer is well
correlated with the number concentration indicated by the CNC. Figure 5.5 is a scatter-plot
of pairs of PAH analyzer response and CNC particle concentration data from the five runs
discussed earlier. The best-fit, log-linear correlation between the two instrument responses is
indicated by the equation shown in Figure 5.5. The fit to the data of the log-linear
relationship and the calculated correlation coefficient are also shown in the figure.
Field evaluations of the PAH analyzer are likely to be conducted without the
availability of a CNC to measure the number concentration of the cigarette smoke.
Therefore, an alternative means of analyzing the PAH analyzer response data was also
sought. Figure 5.6 shows a frequency distribution of PAH analyzer responses over each of
the 12-15 min. test intervals in the five cigarette runs. The frequency distribution is shown
in Figure 5.6 using 10 response intervals of equal size on a logarithmic scale spanning the
range 0.01-2.0 pA. The frequency distributions for the five separate runs shown in
Figure 5.6 reveal that the responses of the PAH analyzer are log-normally distributed within
each run. Also shown in Figure 5-6 is the frequency distribution of data set deriving from
37
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Run 1
Run2
Run 3
Run 4 "~
""'"''" Run 5
12000 -\
Figure 5.4. Profiles of the response of the CNC and the PAH analyzer to cigarette smoke
generated in five consecutive runs.
38
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10
1
IS
I
0.1-
0.01
1.46
PAS [pA]» 1.38E-06* CNC Iparticles/cm*3]
Tests conducted at
room temperature: 25*C
1000
10000
Number Concentration
CNC Reponse
(particles/cmA3)
100000
Figure 5.5. Scatter-plot of pairs of PAH analyzer response and CNC number concentrations
from five consecutive cigarette burn runs.
39
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RunS
Composite
0.013 0.022 0.038 0.064 0.11 0.18 I 0.31 0.53 030 1.53 (mid-points)
PAS Response JpA]
Intervals shown on a log-scale
Figure 5.6. Frequency distribution of PAH analyzer responses over the 12-15 min test
intervals in each of the five cigarette runs. Also shown is the frequency distribution for the
composite of data from all five runs.
40
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compositing the data from the five individual runs. The composite frequency distribution is
also seen to have a log-normal characteristic. This characteristic feature of the PAH
analyzer response may be used to verify the operation of a PAH analyzer tested in the field
using the smoke generator.
A log-normal frequency distribution is well characterized by a geometric mean
response (r_) and geometric standard deviation (
-------
Table 5.2 indicates that the responses of the PAH analyzer in the multiple cigarette
smoke tests are characterized by geometric mean and standard deviation parameters that are
consistent within a narrow range of values. This result suggests that PAH analyzer responses
obtained in field evaluations with the smoke generator can be characterized by their
geometric distribution parameters and compared with the parameter ranges shown in
Table 5.2 to verify proper operation. A standard protocol for operating and maintaining the
smoke generator is provided in Appendix A of this report.
EFFECT OF OPERATING ENVIRONMENT
ON PAH ANALYZER RESPONSE
The purpose of the tests conducted in this task of the study was to evaluate the
performance of the Gossen, PAS lOOOi under operating conditions of high and low
temperature and relative humidity. The motivation for these tests was the need to establish
the potential effects of operating conditions on the response of the PAH analyzer to
particulate-phase PAH. Investigation of such effects is particularly important in regard to the
possible application of the PAH analyzer in indoor/outdoor environments, where a wide
range of temperature and humidity conditions may be encountered.
As discussed in Section 4.4, the tests were conducted in three steps:
Step 1 Baseline Tests
The base-line response of the PAH analyzer and CNC to de-humidified cigarette
smoke aerosol was determined by equilibrating the aerosol at a temperature of 20"C.
The PAH analyzer was also equilibrated by operation inside the chamber at 20"C and
50% R.H. for 2 hours prior to the tests.
Step 2 Low-Temperature Tests
The low temperature tests consisted of two parts: In the first, the PAH analyzer and
the CNC were operated outside the test chamber at room temperature (~25*C, 60%
R.H.) and sampled smoke aerosol equilibrated at a temperature of 3*C. In the second
part, the PAH analyzer was placed inside the chamber at 3*C and 80% R.H. and
operated for a period of about 2 hours before sampling the low temperature-
equilibrated cigarette smoke aerosol.
42
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Step 3 High-Temperature Tests
The high temperature tests were conducted using the two-part procedure described
above for the low temperature tests. The cigarette smoke aerosol was equilibrated at
a temperature of 45 *C. When operated inside the chamber, the PAH analyzer was
equilibrated at 45*C and 30% R.H. for about 2 hours prior to sampling the high
temperature-equilibrated aerosol.
The results from the data collected at each test configuration were evaluated in two
different respects ~ (a) impact of temperature and humidity operating conditions on PAH
analyzer response and (b) impact of sampled air temperature on PAH analyzer response.
The impact of elevated and depressed temperature and humidity operating conditions
(3*C/80% R.H., and 45'C/30% R.H.) on PAH analyzer response was studied as follows.
For each test temperature (high or low), the response of the PAH analyzer as a function of
the particle concentration of the temperature-equilibrated smoke aerosol was compared
between the test configuration where the PAH analyzer was operated inside the chamber and
the configuration where the PAH analyzer was operated outside the chamber (at room
temperature).
The impact of the sampled air temperature on PAH analyzer response was evaluated
by comparing the response of the PAH analyzer (as a function of number concentration) to
the various temperature-equilibrated smoke aerosols when operated inside the chamber at the
three different test conditions, 25'C (baseline), 3'C (low-temperature), and 45*C (high
temperature).
Figure 5.7 shows the results of the baseline configuration tests conducted with the
PAH analyzer inside the environmental test chamber at 20"C and 50% R.H., sampling de-
humidified and temperature-equilibrated cigarette smoke aerosol. The results show the
response of the PAH analyzer in pice-Amperes [pA] as a function of the particle
concentration measured by the CNC [particles/cm3] for three separate runs. The response is
observed to be log-linear and reasonably correlated within each run, as well as between the
various independent runs. The increasing scatter at higher particle concentrations may be
43
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PAS RESPONSE AT ROOM TEMPERATURE CONDITIONS
(2Q'C)
Environmental Test Chamber
Conditions: 20°C, 50% R.H.
-J- ..'.....'.....'.. ' ' ' L.
10000
Particle Concentration
CNC Reponse
(particles/cmA3)
100000
Figure 5.7. Response of the PAH analyzer to a temperature-equilibrated cigarette smoke
aerosol under baseline test conditions.
44
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due to differences in aerosol composition (and PAH content) that result from variations in
combustion conditions within and between each cigarette.
Figure 5.8 shows the results of the high temperature tests conducted at chamber
conditions of 45 *C and 30% R.H. The data shown in the figure are differentiated between
those obtained in a configuration where the PAH analyzer was inside the chamber and those
where the PAH analyzer was outside the chamber (at room temperature) but sampled the
same high temperature-equilibrated aerosol. As Figure 5.8 shows, the data are essentially
indistinguishable suggesting that the operating conditions do not have an observable impact
on the response of the PAH analyzer.
Figure 5.9 shows the results of the low temperature tests conducted at chamber
conditions of 3*C and 80% R.H. The data shown in the figure are again differentiated
between those obtained in a configuration where the PAH analyzer was inside the chamber
and those where the PAH analyzer was outside the chamber (at room temperature) but
sampled the same low temperature-equilibrated aerosol. Figure 5.9 shows that the data from
the two configurations are generally similar, although seemingly less uniform compared with
the data from the high temperature tests shown in Figure 5.8. The conclusion that the
operating conditions do not have an observable impact on the response of the PAH analyzer
appears to be largely applicable in this case also.
The results in Figures 5.8 and 5.9 thus suggest that the temperature and humidity
conditions under which the PAH analyzer is operated do not significantly impact the response
of the PAH analyzer to temperature-equilibrated smoke aerosols at elevated and depressed
temperatures.
The data in Figures 5.7 5.9 can be further used in conducting an analysis of the
impact of sampled air temperature on the response of the PAH analyzer a function of the
smoke aerosol concentration. This analysis is presented in Figure 5.10, which shows the
PAH analyzer response as a function of particle concentration at each of the three test
temperatures, 20'C, 45 *C, and 3*C. The best-fit response lines from logarithmic regression
45
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PAS RESPONSE AT HIGH TEMPERATURE CONDITIONS
(45'C]
_1 1 I
1000
LEGEND
PAS inskte high temperature chamber
O High temperature equilibrated aerosol
(PAS at room temperature)
Environmental Test Chamber
Conditions; 45 "C, 3Q% R
10000
Particle Concentration
CNC Reponse
(particles/cmA3)
100000
Figure 5.8. Response of the PAH analyzer to a high temperature-equilibrated
cigarette smoke aerosol.
46
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1000
PAS RESPONSE AT LOW TEMPERATURE CONDITIONS
(3 «C)
0 o
o*
o 9
O
LEGEND
PAS inside low temperature chamber
O Low temperature equilibrated aerosol
(PAS at room temperature)
Environmental Test Chamber
Conditions: 3 °C, 80% R.H.
10000
Particle Concentration
CNC Reponse
(parti cles/cmA3)
100000
Figure 5.9 Response of the PAH analyzer to a low temperature-equilibrated
cigarette smoke aerosol.
47
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10
1"
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0.1-
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PAS RESPONSE TO CIGARETTE SMOKE AEROSOLS
EQUILIBRATED AT VARIOUS TEMPERATURES
1000
10000
Particle Concentration
CMC Reponse
(particles/cmA3)
LEGEND
20 *C
O 45 »C
+ 3'C
100000
Figure 5.10 Comparison of the response of the PAH analyzer as a function of particle
number concentration to cigarette smoke aerosol at various sampled air temperatures.
48
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analysis are shown in Figure 5.10 for each of the three data sets, together with the individual
regression coefficients for each temperature. Figure S.10 appears to indicate a noticeably
increasing PAH analyzer response as a function of sampled air temperature; the increase in
the response function is most pronounced at the elevated air temperature of 45'C, although a
slight increase in the response function at 20*C compared with 3"C is also perceived.
Possible explanations for the increase in the PAH analyzer response as a function of
the sampled air temperature can only be surmised currently. The residence time (-2 seconds)
of the smote aerosol within the elevated or depressed temperature environment is probably
too short for a significant degree of intra-particle and particle-vapor phase redistribution of
PAH. More likely to be responsible for the effects observed may be the decrease in the
ionization energy required at higher temperatures for photoemission of electrons from the
PAH molecules. This decrease in the ionization energy barrier at higher air temperatures
may then have resulted in a greater efficiency of photoemission and consequently a larger
electrometer response from the PAH analyzer.
AEROSOL TRANSMISSION EFHCIENCY
THROUGH THE PAH ANALYZER AND
MODIFICATIONS IN SAMPLING CONFIGURATION
Aerosol transmission efficiency through the PAH analyzer was determined using
monodisperse NaCl test aerosols of five different sizes: 0.034 /tm, 0.06 ftm, 0.10 jtm,
0.20 /zm and 0.32 pm. The CNC was used to determine the number concentration at the
sampling inlet of the PAH analyzer and downstream at various selected sampling locations
within the PAH analyzer. Figure 5.11 is a summary of the overall results of the aerosol
transmission efficiency experiments.
Figure 5.11 shows the particle penetration (or transmission) for both charged (+1)
and neutralized test aerosols from the sampling inlet to the electrometer inlet (see Figure 4.4
for a schematic of the PAH analyzer). The results demonstrate that the Electrofilter in the
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modified configuration using metal tubing can provide a substantial improvement over the
transmission efficiency of the current sampling configuration in the analyzer.
In order to verify that the modification does not result in deleterious effects on
analyzer performance, a series of tests were conducted. The main issue addressed was the
question of whether the modified configuration is subject to errors from the presence of non-
electrically neutral aerosols in typical indoor environments. As a corollary, the expected
increase in PAH analyzer response due to the increased transmission of sampled aerosols was
also to be addressed.
The experiments to address these issues were conducted in Battelle's Cafeteria. The
cafeteria is a smoking environment (until 9/30/93) and the experiments were conducted as
follows:
Three PAH analyzers were collocated with a CNC in the first series of tests, and
operated as follows: Unit #1 analyzer was a modified configuration with the UV
lamp ON; Unit #2 analyzer was a modified configuration with the UV lamp
OFF; Unit #3 analyzer was an original configuration with the UV lamp OFF.
In the second series of tests, the three PAH analyzers and the CNC were again
collocated in the cafeteria with the following operating parameters: Unit #1
analyzer was a modified configuration with the UV lamp ON; Unit #2 analyzer
was a modified configuration with the UV lamp OFF; Unit #3 analyzer was an
original configuration with the UV lamp ON.
The results of the first series of tests are shown in Figure 5.12, which shows the
response profile as a function of time for each of the three PAH analyzers and the number
concentration measured by the CNC. The response of Unit #1 tracked closely with the
particle concentration measured by the CNC, and was consistent with the presence of
smokers in the cafeteria at different times during the sampling period. The response profiles
of Units #2 and #3 were very similar and were almost always between 0.000 ±0.003 pA,
with maximum observed responses of +0.009 and -0.003 pA. This result indicates that non-
51
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Particle Concentration
(number/cm3)
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-electrically neutral aerosols do not have a significant presence in typical indoor air, and
neither is there a significant presence of gaseous ion non-neutrality. Compared with the
response of the operating (modified) PAH analyzer (Unit #1), the background electrometer
response of the modified analyzer Unit #2 (UV OFF) was negligible. These results suggest
that the modified configuration would not be subject to significant errors from the presence of
non-electrically neutral aerosols in typical indoor environments. Further, the Etectrofilter in
the original configuration PAH analyzer is only partially efficient for particle sizes
>0.06 /*m and cannot guarantee a zero electrometer baseline either.
The results from the second series of tests are shown in Figures 5-13 and 5-14. The
top graph in both figures shows the response profiles as a function of time for the two
operating (UV ON) analyzers - Unit # 1 with the modified configuration and Unit #3 with
the original sampling configuration. The middle graph is a trace of the response of Unit #2
with the modified configuration and the UV lamp OFF - an indication of the baseline
electrometer response of the modified configuration analyzers. The bottom graph is a trace
of the particle concentration measured by the CNC during the course of the two tests.
Figure 5.13 reports the data collected during 2 hours of sampling through the lunch
hour from 11:10 a.m. to 1:10 p.m. in the cafeteria. Figure 5.14 reports data collected
during a subsequent sampling period of 15 minutes during which a cigarette was smoked in
close proximity to the location of the three PAH analyzers and the CNC.
The results shown in Figure 5.13 reveal that under conditions of high particle loading
(30,000 - 100,000 particles/cm3) and presence of ETS from continual smoking activities in
the microenvironment, the modified PAH analyzer had a consistently higher response than
the original configuration PAH analyzer. This result is consistent with the higher
transmission efficiency of the modified configuration. Throughout the sampling period
shown in Figure 5.14 the response from Unit #2, a modified analyzer with UV OFF, was
less than ±0.005, a negligible fraction of the response of the operating modified analyzer,
Unit #1.
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The results in Figure 5.14 for the short duration test conducted with cigarette smoking
in close proximity to the analyzers were similar to the responses observed during the longer
sampling period. In this case, however, a larger baseline electrometer response was
observed from Unit #2 (modified, UV OFF) during several brief periods in the test. This
result is consistent with the presence of freshly generated combustion aerosols. However,
the magnitude of charge on the nbn-electrically neutral aerosol is extremely small compared
with the photoionization response and was under 2-5% at all times. Also, the baseline
electrometer response is extremely transitory and is consistent with the rapid neutralization in
the air of the charged aerosols. Thus, even under worst-case conditions and high particle
loadings, the modified configuration analyzer does not appear to suffer any negative
consequences as a result of by-passing the Electrofilter.
The results of the experiments shown in Figures 5.13 and 5.14 were also used to
determine the percentage increase in analyzer response resulting from the modification. This
increase in analyzer response is shown graphically in Figure 5.15. The top graph in the
figure refers to the two-hour sampling period in Figure 5.13, while the bottom graph refers
to the 15 minute sampling period in Figure 5.14. The result from the top graph
demonstrates that under typical indoor conditions, there is about a 25-30% increase in
analyzer response. The graph at the bottom of Figure 5.15 indicates that during the period
of close proximity cigarette smoking, the modified analyzer continued to yield a higher
response on average than the original analyzer. Short periods during which the original
analyzer had a higher response are probably due to non-homogeneous smoke concentrations
in the sampling environment. A systematic comparison of the response of the modified and
original analyzers using the cigarette smoke generator could not conducted within the time
constraints of this study.
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PAH ANALYZER RESPONSE TO NON-PAH
LABORATORY TEST AEROSOLS
Tests with non-PAH NaCl test aerosols in the previous evaluation study5 had found
that the PAH analyzer had a small, but not insignificant, response to these test aerosols. In
our earlier study, the non-PAH response tests were conducted using polydisperse NaCl
aerosols of three different count median diameters (CMD), 0.04 pm, 0.08 /tm and 0.15 /xm
and a log-normal standard deviation of crg2.0. The aerosols were generated by nebulizing
solutions of appropriate concentrations of sodium chloride in water and drying the nebulized
droplets to form the solid NaCl test aerosol.
The response of the PAH analyzer to these non-PAH aerosols varied linearly with
particle number concentration for each polydisperse aerosol5. In addition, the response was
proportional to the size of the test aerosol, i.e., the 0.15 pan CMD polydisperse aerosol
resulted in a higher response, normalized to particle number concentration, than the 0.08 /*m
CMD aerosol which in turn resulted in a higher response than the 0.04 tim CMD aerosol.
The normalized response to the 0.04, 0.08 and 0.15 pm CMD aerosols was approximately
0.009, 0.015 and 0.036 pA, respectively, for 10,000 particles of each test aerosol entering
the PAH analyzer. Note that these response rates are normalized to the number
concentration entering the PAH analyzer; since different sizes of particles entering the
analyzer have different transmission efficiencies (see Figure 5.11), the relationship between
analyzer response and particle size is somewhat convoluted. In addition, since the test
aerosols were not monodisperse (of a single particle size), it was difficult to interpret the
precise relationship of the response with particle size.
Considering these difficulties with interpreting the results of the previous study, we
attempted to obtain the response of the PAH analyzer for various monodisperse particle sizes
spanning the size range typical of indoor aerosols, 0.01 - 0.5 /tm. We selected the same five
monodisperse particle sizes used in the aerosol transmission efficiency tests (see Table 4.2),
58
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namely, 0.034, 0.06, 0.10, 0.20, 0.32 pm. Also in order to by-pass the issue of particle
size dependent transmission efficiency through the PAH analyzer, particle concentration
measurements were made at the inlet of the electrometer (see Figure 4.8). The response of
the PAH analyzer to each monodisperse test aerosol was normalized to the number
concentration measured at this location.
A number of different aerosols were used to test the PAH analyzer, as discussed in
Section 4.6. Prior to testing the response of the PAH analyzer, each monodisperse aerosol
was first sampled by the analyzer with the UV lamp OFF. The electrometer response in this
operating condition was checked to be within 0.000 ±0.005 pA, to ensure that the test
aerosol was electrically net-neutral. The subsequent analyzer response with the UV lamp
operational could then be ascribed completely to photoionization effects. This check-out
procedure was found to be essential since aerosols emerging immediately from a Kr-85
neutralizer may not be electrically neutral. We found that the use of the mixing chamber
was very helpful in allowing the aerosols to become net electrically neutral, probably because
it allowed a longer time period from the time the aerosol exited the neutralizer to when it
entered the analyzer.
For all the test aerosols the response of the PAH analyzer varied linearly with particle
number concentration at each monodisperse particle size. This result is consistent with mat
obtained in our previous study, and is further evidence that the response is due to
photoionization effects. The response of the PAH analyzer to the various test aerosols can
also be compared as a function of particle size, aerosol material and nebulizing solvent.
Figure 5.16 is a comprehensive summary of the results of the response tests. The figure
shows, for each type of aerosol generated, the PAH analyzer response normalized to the
number of particles entering the electrometer. The figure also shows the surface area (in
/im2) as a function of particle size over the size range of the tests.
As shown in Figure 5.16, the most obvious result from the tests is that for sodium
chloride and ammonium sulfate aerosols, both generated from water solutions, the
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normalized responses as function of particle size are almost identical (within experimental
error) to each other. In addition, the normalized response correlates very well with the
particle surface area. This result is further evidence that the response is a surface
phenomenon and is due to photoionization of substance or substances unknown deposited on
the surface of the aerosols. The fact that identical responses are observed for both sodium
chloride and ammonium sulfate aerosols confirms our earlier suspicions5 that the response is
related to contaminants. The normalized response is also consistent with the results obtained
from the previous study for polydisperse aerosols, after corrections for size-dependent
transmission efficiency are considered.
To further investigate the origin of the response, phthalic anhydride test aerosols were
generated from a water solution. The normalized response to this aerosol, shown in
Figure 5.16, is similar in magnitude to the sodium chloride/ammonium sulfate response,
although a little more scatter in the data is observed. The lack of a higher response indicates
that the response from sodium chloride and ammonium sulfate is not due to phthalic
anhydride contamination. Phthalic anhydride is a common contaminant found in paniculate
air samples analyzed for PAH using conventional GC/MS methods. The selection of phthalic
anhydride for these tests was motivated by the supposition that it was the contaminant
causing the photoionization response observed in laboratory non-PAH aerosols.
In a final series of tests, phthalic anhydride and di-octyl phthalate (DOP) aerosols
were generated from iso-propyl alcohol (IPA) solutions. The results from these experiments,
shown in Figure 5.16, revealed that the normalized response to these test aerosols was less
than the corresponding responses from aerosols generated from water solutions. In
particular, the comparison of responses from phthalic anhydride aerosols generated from IPA
and water solutions showed that the IPA-generated aerosols had a substantially lower (note
the logarithmic response scale in Figure 5.16) response than the water-generated aerosol.
The response from the DOP aerosol was even lower and more scattered. One key difference
between DOP and the other test aerosols is that DOP is a liquid aerosol at room temperature
conditions, while the others are solid aerosols.
61
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The difference in analyzer response depending on whether the aerosols were generated
from water or from IP A solutions suggests that photoionization is occurring due to the
presence of contamination in the solvent. As the nebulized droplets are dried, the
contamination in the solvent may be deposited on the surface of the particle. In fact, the
drying process may be concentrating the contaminants on the particle surface as the solvent
evaporates from the surface.
Distilled, deionized (10I8M-ohm) water and analytical grade IPA were used to prepare
all solutions used in the experiments it is therefore difficult to theorize on the origin of the
contamination. Most likely, however, the contamination is organic in nature and is
ubiquitous. The PAH analyzer was also tested by nebulizing and drying blank solutions of
both IPA and water no response was observed in either case. This result is consistent
with a surface-based photoionization mechanism. Without the presence of a non-volatile
substance in the solution, there is no surface for the contaminant(s) to be deposited. If the
contaminant is non-volatile, the blank solution would have resulted in ultrafine particles,
probably < 0.015 pan in diameter with insufficient surface area for a response from the
analyzer. If the organic contaminant is semi-volatile, the lack of particle surfaces from the
blank solution may have resulted in the contaminant being present completely in the vapor
phase.
A final noteworthy observation in this regard is the typical response of the PAH
analyzer under "clean" (non-ETS) conditions in indoor air. Under these conditions, and at a
particle concentration of 10,000 - 15,000 particles/cm3, the analyzer response is usually less
than 0.02 - 0.03 pA. The typical indoor aerosol under clean (no paniculate source)
conditions has a particle size CMD of 0.15-0.3 /tm. Based on the sodium
chloride/ammonium sulfate responses in Figure 5.16, the background photoionization
response under typical clean indoor air conditions should be > 0.1 pA. Clearly, such a large
response is not observed. This inconsistency suggests that the laboratory generated non-PAH
aerosol are somehow artificially enriched in the non-PAH contaminant(s) that are causing the
observed photoionization response. To determine how much of the typical response in
62
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indoor air is due to non-PAH contaminants will therefore require the knowledge of the nature
of the contaminant. Also, a more sophisticated aerosol generation technique would be
required that better emulates the indoor aerosol while ensuring the absence of PAH.
FIELD STUDY AND
INTERCOMPARISONS
The objectives of the pilot field study were to (1) conduct a field evaluation of the
performance of the PAH analyzer and (2) compare the measured particle-bound (<2.5 /tin)
PAH concentrations from the integrated indoor sampler and GC/MS analysis with the
average responses of the PAH analyzer during the corresponding 24-h sampling periods.
The PAH analyzer was found to operate in a very satisfactory manner throughout the study.
The unit was portable, and easy to set up in the house for operation by one person. None of
the residents voiced any complaints regarding the unit's operation.
The measured concentrations for individual PAH and alkylated PAH compounds from
the eight sample homes are summarized from Tables 5.3 through 5.10. The measured PAH
concentrations in the field blank sample is given in Table 5.11. The field blank consisted of
a clean filter and XAD-2 trap which were taken to House H03RN and placed on the
sampling train without sampling. The filter and XAD-2 trap were then transported back to
Battelle for analysis. The field blank contained trace amounts of 2- to 4-ring PAH. The
measured PAH concentrations reported in Tables 5.3 through 5.10 were corrected for the
PAH concentrations in the field blank. Note that the reported concentrations only represent
the fine particulate-bound (<2.5 /im) PAH concentrations. As described in Section 4.7, the
impactor-denuder sampling train removes coarse particles >2.5 jtm in aerodynamic diameter
in the impactor, with vapor-phase PAH being subsequently removed by the denuder.
The fine particulate-bound PAH concentrations in indoor air were higher in the
smokers' houses than that in the non-smokers' houses. Among the eight houses, the highest
PAH concentrations in indoor air were found in house H06RS. In this house, a total of
63
-------
TABLE 5.3 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H01RS.
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Melhylphenanthrene isomers
C2-alkyIphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA<'>
NA<*>
13
NA<*>
23
1.3
14
2.0
3.3
1.8
0.33
0.087
0.15
0.27
<0.03
0.18
0.43
0.42
0.46
0.21
0.23
0.28
0.070
0.063
62
(a) Not applicable, due to interference compounds from the denuder tube.
64
-------
TABLE 5.4 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H02RN
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indenofl ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a, hjanthracene
Coronene
Sum of PAH
NA<*>
NA<*>
9.6
NA<*>
NA<*>
NA<*>
18
1.2
6.8
2.0
1.9
1.7
0.22
0.060
2.12
0.17
<0.03
<0.03
0.21
0.24
0.15
<0.03
0.16
0.12
0.056
0.045
43
. (a) Not applicable, due to interference compounds from the denuder tube.
65
-------
TABLE 5.5 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H03RN
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoianthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA«
NA<*>
8.4
NA<*>
NA«
NA«
16
0.92
7.8
1.4
0.79
0.66
0.15
0.052
0.053
0.12
<0.03
<0.03
0.27
0.16
0.21
<0.03
0.071
0.090
<0.03
<0.03
37
(a) Not applicable, due to interference compounds from the denuder tube.
66
-------
TABLE 5.6 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H04RS
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA<*>
NA«
8.8
NA<«>
NA<»>
NA<*>
30
1.7
16
3.8
3.9
3.2
0.40
0.11
0.26
0.19
<0.03
<0.03
0.23
0.27
0.32
<0.03
0.31
0.19
0.062
0.11
70
(a) Not applicable, due to interference compounds from the denuder tube.
67
-------
TABLE 5.7 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H05RS
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA<«>
16
NA<*>
NA
35
1.5
19
8.7
3.6
2.9
0.47
0.22
0.22
0.37
<0.03
0.062
0.29
0.27
0.36
0.16
0.45
0.28
0.086
0.043
90
(a) Not applicable, due to interference compounds from the denuder tube.
68
-------
TABLE 5.8 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H06RS
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthiene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c »d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a, h]anthracene
Coronene
Sum of PAH
NA<»>
NA(a>
30
NA<*>
NA(a)
55
2.3
50
4.5
4.4
3.7
0.85
0.57
0.21
0.39
<0.03
0.076
0.35
0.26
0.36
0.65
0.48
0.35
0.094
0.052
150
(a) Not applicable, due to interference compounds from the denuder tube.
69
-------
TABLE 5.9 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H07RN
Compound
Concentration, ng/m3
Naphthalene
Accnaphthene
Acenaphthylene
Biphenyl
Mcthylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA<»>
NA<*>
6.0
NA(a>
NA<*>
NA<*>
16
0.61
1.6
5.2
1.6
1.3
0.16
<0.03
<0.03
0.050
<0.03
<0.03
0.065
0.040
0.041
<0.03
0.068
0.046
<0.03
<0.03
33
(a) Not applicable, due to interference compounds from the denuder tube.
70
-------
TABLE 5.10 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE AIR IN HOME H08RN
Compound
Concentration, ng/m3
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl isomers
Fluorene
Phenanthrene
Anthracene
Methylphenanthrene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
Methylpyrene isomers
C2-alkylpyrene isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methylbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyrene
Methylbenzofluoranthene isomers
Indeno[l ,2,3-c,d]pyrene
Benzo[g,h,i]perylene
Dibenzo[a,h]anthracene
Coronene
Sum of PAH
NA<«>
7.0
NA<»>
NA(*>
NA<*>
32
1.5
7.8
2.4
1.7
1.3
0.18
<0.03
0.63
0.10
<0.03
<0.03
0.16
0.24
0.24
<0.03
0.075
0.065
<0.03
<0.03
55
(a) Not applicable, due to interference compounds from the denuder tube.
71
-------
TABLE 5.11 MEASURED PAH AND ALKYLATED PAH CONCENTRATIONS IN
THE FJELDrBLANK SAMPLE
.Compound
Concentration, n
Naphthalene
Acenaphthene
Acenaphthylene
Biphenyl
Methylbiphenyl jsomecs
Huorene
Phenanthrene
Anthracene
Methylphenanthrjene isomers
C2-alkylphenanthrene isomers
Fluoranthene
Pyrene
MethyjipyTene isomers
C2-alkylpjoBne isomers
Benz[a]anthracene
Chrysene
Cyclopenta[c,d]pyrene
Methyjbenz[a]anthracene isomers
Benzofluoranthenes
Benzo[e]pyrene
Benzo[a]pyxene
Methylbenroflupranthene isomers
Indeno[l ,2,3-e,d]pyrene
Benzo[g,h,i]perylene
Dibenzofa, h]anthracene
Coronene
Sum of PAH
2.3
0.59
0.12
0.79
<0.03
1^
2.9
0.15
0.047
C0.03
0.26
0.18
<0.03
<0.03
<0.03
0.057
<0.03
<0.03
<0,03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
8.9
(a) Assume the total sample volume is 25 m3
72
-------
seven cigarettes were smoked during the 24-h sampling period. The numbers of cigarettes
smoked were three (3) in H01RS, two (2) in H04RS, and five (5) in H05RS.
Note that in Tables 5.3 - 5.11, the concentrations of a few volatile PAH such as
naphthalene, biphenyl acenaphthene, and fluorene could not be accurately measured.
Off-gassing of volatile chemical species from the silicone grease used to coat the impactor and
the denuder apparently occurred during sampling, causing these species to be collected in the
filter/XAD-2 trap. These species interfered with the quantification of the above-mentioned
volatile PAH. Since most of these volatile PAH are present almost exclusively in the vapor
phase10'11, they are not expected to contribute significantly to the fine particle-bound PAH
concentrations.
The response of the PAH analyzer as a function of time during the corresponding
24-h sampling period in each house is shown in Figure 5.16 through 5.23. As shown in
these figures, the responses of the PAH analyzer in non-smokers' houses were less than
0.1 p Amp. Higher responses were observed in the smokers' houses. Note that house
H07RN is equipped with a high performance paniculate filter and would consequently have
low particle concentrations in indoor air. In this house, the PAH analyzer did not have a
response during most the 24-h sampling period, as shown in Figure 5.22.
The PAH analyzer's response as a function of time in each sample home was
averaged to provide an average response over each sampling period (in pAmp). The average
PAH analyzer response for each sample home was then converted to an average PAH
concentration (ng/m3) by using the conversion factor of 3,000 ng/m3/p Amp provided by
Gossen, GmbH and Eco Chem Technologies, Inc. These average PAH concentrations were
then compared with the fine particle PAH concentrations measured from GC/MS analysis of
the corresponding integrated samples.
73
-------
HO IRS PAH
ANALYZER DATA
PAH
SIGNAL
(pAmp)
300
600 900
TIME (minutes)
1200 1500
Figure 5.17 Response of the PAH analyzer during the 24-h sampling period in H01RS.
74
-------
0.1
0.08
0.06-
PAH
SIGNAL
(pAmp)o.o4
0.02-
0
H02RN PAH
ANALYZER DATA
300 600 900 1200 1500
TIME (minutes)
Figure 5.18 Response of the PAH analyzer during the 24-h sampling period in H02RN.
75
-------
H03KNP&H
AMALYZER DAfA
0.06
0.04--
PAH
SIGNAL
(pAmp)
0.02-
300 600 900 1200 1500
TIME (minutes)
Figure 5.19 Response of the PAH analyzer during the 24-h sampling period in H03RN.
76
-------
0.2
0.16--
0.12
PAH
SIGNAL
(pAmp) o.os
0.04-
H04RS PAH
ANALYZER DATA
300
600
900
1200 1500
TIME (minutes)
Figure 5.20 Response of the PAH analyzer during the 24-h sampling period in H04RS.
77
-------
0.8
0.6--
PAH
SIGNAL
(pAmp)
0.4-
0.2--
0-
H05RS PAH
ANALYZER DATA
0 300 600 900 1200 1500
TIME (minutes)
Figure 5.21 Response of the PAH analyzer during the 24-h sampling period in H05RS.
78
-------
H06RS PAH
ANALYZER DATA
0.8
0.6--
PAH
SIGNAL
(pAmp)
0.4-
0.2--
300
600 900
TIME (minutes)
1200 1500
Figure 5.22 Response of the PAH analyzer during the 24-h sampling period in H06RS.
79
-------
0.01
0.01-
PAH
SIGNAL'
(pAmp)
0.01
0-
0-
o
H07RNPAH
ANALYZER DATA
n
300 600 900 1200 1500
TIME (minutes)
Figure 5.23 Response of the PAH analyzer during the 24-h sampling period in H07RN.
80
-------
0.1
0.08-
PAH
SIGNAL
(pAmp)
0.06
0.04--
0.02--
0
0
H08RN PAH
ANALYZER DATA
300
600
900
TIME (minutes)
1200 1500
Figure 5.24 Response of the PAH analyzer during the 24-h sampling period in H08RN.
81
-------
Table 5.12 summarizes the sum of the measured fine particle-bound concentrations of
individual PAH and alkylated PAH compounds (referred to as fine particle PAH) and the
average PAH analyzer-based concentration. The measured fine particle PAH concentrations
were about one-half to two-times of the average PAH concentrations from the PAH analyzer
in non-smokers' houses. In the smokers' houses, the measured PAH concentrations ranged
from 0.28 to 1.3 times of the average PAH concentrations of the PAH analyzer.
TABLE 5.12 COMPARISON OF FINE PARTICULATE-BOUND PAH
CONCENTRATIONS MEASURED FROM THE
INTEGRATED SAMPLERS AND CORRESPONDING
AVERAGE RESPONSES FROM THE PAH ANALYZER
House Codew
Fine Particle PAH
Measured00
Concentration, ng/m3
Average PAH Analyzer-Based(c)
Concentration, ng/m3
H01RS
H02RN
H03RN
H04RS
H05RS
H06RS
H07RN
H08RN
62
42
37
70
90
150
33
55
220
76
45
53
240
300
ND
35
(a) In H01RS, H01R refers to the house code, and S refers to a smoker's house. In
H02RN, H02 refers to the hose code and N refers to a non-smoker's house.
(b) Measured concentration is the sum of individual PAH concentrations determined from
GC/MS analysis of the combined filter and XAD-2 trap from the integrated sampler
equipped with an impactor and denuder upstream of the filter and XAD-2 trap.
(c) A conversion of 3,000 ng/m3/p Amp was used to calculate the average PAH
concentration from the PAH analyzer's average response during each 24-h sampling
period.
(d) ND denotes not detected.
82
-------
iCES
(1) Burtscher, H. Schemer, L., Siegmann, H.C., Schmitt-Ott, A. and Federer, B.
Probing aerosols by photoelectric chargin. J. Appl. Phys. 53(5), 3787, 1982.
(2) Burtscher, H., Niessner, R. and Schmitt-Ott, A. In-situ detection by photoelectron
emission of PAH enriched on particle surfaces, in Aerosols: Science, Technology,
and Industrial Applications of Airborne Particles. Edited by Liu, B. et al.,
Elsevier, New York, 1984, p. 443.
(3) Niessner, R. The chemical response of the photo-electric aerosol sensor (PAS) to
different aerosol systems. J. Aerosol Sci., 17(4), 705, 1986.
(4) McDow, S.R., Giger, W., Burtscher, H., Schmitt-Ott, A., Siegmann, H.C.
Polycyclic aromatic hydrocarbons and combustion aerosol photoemission, Atmos.
Env. 24A(12), 2911, 1990.
(5) Chuang, J.C. and Ramamurthi, M. Evaluation of a Gosson, GmbH Model PAS
lOOOi photoelectric aerosol sensor for real-time PAH analyzering, Final Report,
EPA Contract Number 68-DO-0007, Work Assignment 13, 1992.
(6) Lane, D.A., Sakuma, T., Ouan, E.S.K. Real-time analysis of gas phase polycyclic
aromatic hydrocarbons using mobile atmospheric pressure chemical ionization mass
spectrometer system, Reprinted from Polynuclear Aromatic Hydrocarbons: Fourth
International Symposium on Analysis, Chemistry, and Biology, Battelle Press,
Columbus, Ohio, 1980.
(7) Liu, B. Y.H. and Lee, K. An aerosol generator of high stability, Amer. Ind. Hyg.
Assoc., December 1965, p.861.
(8) Liu, B.Y.H. and Pui, D.Y.H. A sub-micron aerosol standard and the primary,
absolute calibration of the Condensation Nucleus Counter, J. Colloid Int. Sci.,
47:155, 1974.
(9) Chuang, J.C., Callahan, P.J., Katona, V., and Gordon, S.M. Develop and
evaluate monitoring methods for polycyclic aromatic hydrocarbons in house dust
and track-in soil, Final Report, EPA Contract Number 68-DO-0007, Work
Assignment 35, 1993.
(10) * Wilson, N.K., Chuang, J.C., Kuhlman, M.R., Mack, G.A., and Howes, Jr., J.E.
A quiet sampler for the collection of semivolatile organic pollutants in indoor air,
Environ. Sci. and Technol., 23(9), 1112, 1989.
83
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(11) U.S. EPA. Compendium Chapter JP-9, Determination of Reactive Acidic and
Basic Gases and Participate Matter in Indoor Air, Atmospheric Research and
Exposure Assessment Laboratory, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, 1989.
(12) Coutant, R.W., Callahan, P.J., and Chuang, J.C. Development of an efficient
compound annular denuder for determining indoor phase distributions of
semivolatile organic compounds, EPA Contract No. 68-02-4127, 1989 Final
Report.
(13) Coutant, R.W., Callahan, P.J., Kuhlman, M.R., and Lewis, R.G. Design and
performance of a high-volume compound annular denuder, Atmos. Environ., 23,
2205, 1989.
(14) Chuang, J.C., Gregory, A.M., Kuhlman, M.R., and Wilson, N.K. Polycyclic
aromatic hydrocarbons and their derivatives in indoor and outdoor air in an eight-
home study, Atmos. Environ. 25B(3), 319, 1991.
84
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APPENDIX A
SMOKE GENERATOR STANDARD PROTOCOL
The following step-wise procedure should be followed when using the cigarette
smote generator for field (or laboratory) evaluation of a Gossen PAS Model lOOQi. The
procedure assumes that the smoke generator is in working order and all regular maintenance
requirements as outlined subsequently have been fulfilled.
EXPERIMENTAL
1.
2.
Turn the power switch on the smoke generator to ON; the noise of the pump should be
heard immediately and several of the rotameter should register some amount of air flow.
Pull the cigarette combustion chamber tube away from the front panel so that the
cigarette holder is disconnected from the tube. A silicone gasket on the outer rim of the
cigarette holder provides the seal with the tube; vacuum grease on the gasket will help to
make disassembly and re-assembly of the tube easier.
3. Insert a University of Kentucky research cigarette into the cigarette holder. The
cigarette will most likely be only loosely held by the holder. A small piece of thin
tissue or laboratory wipe wrapped around the end of the cigarette inserted into the holder
will help to make a snug fit. Insert about a % of an inch of the cigarette into the holder.
4. Re-assemble the cigarette combustion chamber.
5. After waiting about 30 seconds for the system to re-equilibrate, check and set the
various flows to the nominal levels stated in Figure 1. If the Calibration Smoke Feed
flow is not sufficient, the adjustable needle valve inside the box enclosure may need to
be closed further. Looking at the box from the front-right hand side, the needle valve is
closed further by clock-wise rotation of the screw using an appropriately sized screw-
driver. Do not tighten the screw by more than V4-V4 rotation each time. Close the
valve to the extent necessary to be able to maintain a steady flow of 25 cc/min through
the Calibration Smoke Feed rotameter.
6.
Connect a W" diameter tube to the Smoke Outlet on the front panel of the smoke
generator. Connect the other end of the tube to a tee connector. The PAS can be
connected to one of the other two openings of the tee connector. The third opening
should be connected to a tube that appropriately vents the excess air flow. Note that the
excess air will contain a low but odorous concentration of cigarette smoke. A
datalogger is extremely useful to record the response of the PAS to the cigarette smoke
generated in the test. The datalogger should be set to record data at 10 second intervals
over a test duration of 15 minutes. Do not start data acquisition at this point, however.
85
-------
6. After setting the flows as specified, disassemble the Cigarette Combustion Chamber
again by pulling the tube outward. Using a butane lighter, light about a % of an inch of
the cigarette at the opposite end from the cigarette holder. Ensure that the end is
completely on fire, including the tobacco in the middle. The process of lighting the
cigarette may take up to 10 seconds. It is extremely important to light the cigarette
well, otherwise it WILL get extinguished. A butane lighter is also highly recommended,
as it is very difficult to accomplish a good starting burn using a match.
7. After lighting the cigarette, reassemble the Cigarette Combustion Chamber.
8. Pay dose attention to the Calibration Smoke Feed fotameter readout. It should rise
from near zero back up to the initial setting of 25 cc/min within about 20 seconds. If
necessary adjust the rotameter valve to obtain the required flow rate.
9. Start acquiring PAS response data with the datalogger when all this flows are at or within
10% of their required values.
10. Continue to monitor the flows for the next 12-15 minutes, making minor adjustments as
necessary. The Cigarette Smoke Combustion Air and Calibration Smoke Feed flows
will tend to fluctuate. Some amount of variability in these two flows is unavoidable. It
is satisfactory if the Combustion Air flow remains in the range of 60-75 cc/min and the
Smoke Feed is within 20-30 cc/min.
11. Keep a close watch on the PAS response, particularly within the first 2-3 minutes of the
test. If the response falls to zero and does not change for more than 30-45 seconds, the
cigarette has become extinguished. It is then necessary to abort the test. Cease data
acquisition, and remove the unburnt cigarette inside the combustion chamber. Replace
with a new cigarette and re-start the process. The likely causes of a cigarette becoming
extinguished are: (a) cigarette not adequately lit at the start; (b) cigarette not held snugly
by the holder; (c) cigarette was bumped when the Combustion Chamber was
reassembled; (d) Combustion Air was insufficient.
If the PAS response is continuously below 0.05 pA during a test and opening the
Combustion Chamber during the run reveals that the cigarette is burning, then improper
function of the PAS may be indicated. To confirm that the PAS is not functioning
properly, check that the smoke generator's flows are at their nominal values and that
flow paths to the PAS are correctly connected.
12. After a data acquisition period of 12-15 minutes, terminate data acquisition.
Disassemble the Combustion Chamber and remove the burning cigarette. Extinguish the
cigarette and dispose appropriately.
13. If no further tests are to be conducted, allow about 10 minutes for the Mixing Chamber
to flush completely before powering off the smoke generator.
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DATA ANALYSIS
1. Transfer the data from the datalogger to a computer data file and import the file into a
spreadsheet. The data should consist of a series of rows of PAS response in pA. There
will be approximately 72-90 responses for each run, assuming that data were collected
every 10 seconds over a period of 12-15 minutes.
2. Calculate the geometric mean response and the geometric standard deviation of the data
collected in each run. Compare these calculated values with those obtained in laboratory
tests with the PAS, as shown in Table 1.
The geometric mean response, rg, is calculated as:
rg = exp [-
S tar,
] ,
where rt is the PAS response for the r* data point of a total of n data points.
The geometric standard deviation, ag, is calculated as:
3.
where rg is as calculated above.
If possible, plot a frequency distribution of the PAS responses in each run. Use the
same number of bins (10) and logarithmic range of 0.01-2.0 pA as in Figure 6.
Compare these results with those in Figure 6 obtained from laboratory tests with the
PAS.
If only a qualitative analysis is desired, then review the general range of the PAS
responses, and compare them with the range of responses observed in the laboratory
tests, as shown in Figure 4. The PAS response typically varies between 0.1 and 1.0 pA,
with an average value of about 0.25-0.35 pA. The presence of peaks and valleys in the
response curve as a function of time is also indicative of typical performance of the
PAS.
If the PAS response is continuously below 0.05 pA during a test and the smoke
generator was operating properly according to all flow and cigarette burn sight
indicators, then it may be concluded that the PAS is not functioning correctly. The PAS
may then need to be removed from the field site and further laboratory tests conducted
to determine the origin of the problem.
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SMOKE GENERATOR MAINTENANCE
The smoke generator requites regular maintenance for a few components. These
components are listed below and estimated intervals for replacement or service are provided.
1. Needle valve - the adjustable needle valve needs to cleaned periodically since it
becomes clogged with cigarette smoke residue from the air that passes through it en
route to the capsule filter. The needle valve should be cleaned at least every 20
cigarettes. To clean the valve, remove it from its location, open the valve to a
completely open position and clean the passage using a wire brush and soap water or, if
available, isopropyl alcohol (IPA). Air-dry the valve before replacing it in the flow
path.
2. Calibration Smoke Feed Rotameter (0-50 cc/min) the interior channel of the rotameter
and float need to be cleaned periodically as they become coated and/or clogged with
smoke residue from the highly concentrated smoke aerosol flowing through the
rotameter. The two components should be cleaned about every 20-30 cigarettes. To
clean the rotameter, follow the procedures provided in the rotameter instruction manual.
3. The silica gel in the drying column will need to be replaced periodically. The indicating
variety of silica gel should help to determine when to replace with fresh gel.
4. The carbon and paniculate filter cartridges inside the box enclosure should be replaced
approximately every 100 cigarettes. At the same time as these filters are replaced, the
capsule filter should also be replaced.
SMOKE GENERATOR COMPONENTS
The following is a list of key replaceable components within the smoke generator. The
manufacturer and/or vendor for each component is also listed. Note that the listings are only
indicative of the particular components used currently in the smoke generator and are not
meant to be exclude other alternative models or manufacturers. Replacement components
from other manufacturers or vendors may be equally suitable in some cases.
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Component
Pump
Rotameter
Cartridge Filters
HEPA Capsule
Filter
Model Number
Model 400-1911
Models:
RMA-151-SSV
(5-50 cc/min)
RMA-150-SSV
(5-100 cc/min)
RMA-26-SSV
(0.5-5 1pm)
Models:
DFU 9933-05-AQ
DAU 9933-05-000
Model 12144
Description
Air Cadet
vacuum/pressure
pump; 1100
cu.in./min
capacity; vacuum
oil-free
Rate-Master
Flowmeters - 2"
scale; Stainless-
steel metering
valve
Particulate and
Carbon disposable
cartridge filters
HEPA Capsule
filter; 0.3 pm
Versapor; %" NPT
'inlet/outlet
Manufacturer/Vendor and
Approximate Cost
Barnant Company
28 W 092 Commercial Ave
Harrington IL 60010
1-800-637-3739
$98
Dwyer Instruments, Inc.
P.O. Box 373, Michigan City, IN 46360
(219) 872-9141
Flowmeters range from $20-$30
depending on model
Balston Filter .Systems
703 Massachusetts Avenue, Box C
Lexington, MA 02173
1-800-343-4048
Model DFU: $97/box of 10
Model DAU: $168/box of 10
Gelman Sciences
600 Wagner Road, Ann Arbor, MI
48106
Available from Fisher Scientific, Fisher
Catalog No. 09-743-28; $42
89
&U.S. GOVERNMENT PRINTING OFFICE: 1997 - S49-OOI/60M4
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