EPA-600/3-77-119
October 1S77
INTERNATIONAL CONFERENCE OK OXIDANTS, 1976 —
ANALYSIS OK EVIDENCE £NL VIEWPOINTS
Part VII. The Issue of Oxidant/Ozone Measurement
J.N. Pitts, Jr.
Statewide Air Pollution Research Center
University of California
Fiverside, California
Contract No. DA-7-2142A
G. Su
Department of Natural Resources
State of Michigan
Lansing, Michigan
Contract No. DA-7-2044A
Project Officer
Basil Dirdtriades
Environmental Sciences Research Laboratory
Research Triangle tark. North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
In general, the texts of papers included in this report have been repro-
duced in the fo^u submitted by the authors.
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ABSTRACT
In recognition of the important and somewhat controversial nature of the
oxidant control problem, the U.S. Environmental Frjtection Agency (EPA)
organized and conducted a 5-day international Conference in September 19"?6.
The more than one hundred presentations and dis>" ussion:- at the Conference
revealed the existence of several issues and prompted the- EP7i to sponsor a
follow-up review/analysis effort. The follow-up effort wa« designed to review
carefully and impartially, to analyze relevant evidence and viewpoints reported
at the International Conference (and elsewhere), and to attempt to resolve
some of the oxidant-related scientific issues. The review/analysis was con-
ducted by experts (who did not work for the RPA or for industry) of widely
recognized competence and experience in the area of photochemical pollution
occurrence and control.
The issue of oxidant/ozone measurement is disc i-^sed in Part VII by James
N. Pitts, Jr. of the Statewide Air Pollution Research Center, University of
California at Riverside, arid George Su of tne State of Michigan Department of
Natural Resources in Lansing. Analytical measurement techniques are compar- d
and recommendations for improvements are made.
ill
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CONTENTS
ABSTRACT iii
INTRODUCTION 1
B. Dimitriades and A.P. Altshuller
THE ISSUE OF OXIDANT/OZONE MEASUREMENT .
B. Dimitriades and A.P. Altshuller
REVIEW AND ANALYSIS 7
J.N. Pitts, Jr.
REVIEW AND ANALYSIS 15
G. Su
REFERENCES 19
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ACKNOWLEDGMENTS
These contracts were jointly funded by the Office of Research and Devel-
opment (Environmental Sciences Research Laboratory) and the Office of Air
Quality Planning and Standards.
The assistance of the technical editorial staff of Northrop Services,
Inc. (under contract 68-02-2566) in preparing these reports is gratefully
acknowledged.
VI
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INTRODUCTION
Basil Dimitriades and A. Paul Altshullur
In recognition of the important and somewhat controversial nature of the
oxidant control problem, the U.S. Environmental Protection Agency vEPA) organ-
ized and conducted a 5-day International Conference in September 1976. The
one hundred or so presentations and discussions at the Conference revealed the
existence of several issues and prompted EPA to sponsor a followup review/
analysis effort. Specifically, this followup effort is to review carefully
and impartially and analyze relevant evidence and viewpoints reported at the
International Conference (and elsewhere) and to attempt to resolve some of the
oxidant-related scientific issues. This review/analysis effort has been con-
tracted by EPA to scientists (who do not work for EPA or industry) with exten-
sive experience and expertise in the area of photochemical pollution occur-
rence and control. The first part of the overall effort, performed by the EPA
Project Officer and reported in a scientific journal (1), was an explanatory
analysis of the problem and definition of key issues, as viewed within the
research component of EPA. The reports of the contractor expert/reviewer
groups offering either resolutions of those issues or recommendations for
additional research needed to achieve such resolutions are presented in the
volumes composing this series.
This report presents the reviews/analyses prepared by the contractor
experts on the issue of oxidant/ozone measurement. In the interest of com-
pleteness the report will include also an introductory discussion of the
issue, taken from Part I. The reviews/analyses prepared by the contractor
experts follow, along with the expert's comments on each other's reports.
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THE ISSUE OF OXIDANT/OZONE MEASUREMENT
Basil Dimitriades and A. Paul Altshuller
Recent studies have resulted in some disconcerting evidence regarding the
performances of the various oxidant/ozone measurement methods in existence (2-
5). All potassium iodide (KI) procedures for either measuring ambient oxi-
dant/ozone or for calibrating oxidant/ozone measurement methods were found to
disagree with each other; the disagreement varied in degree depending on study
or analyst. There was also disagreement between certain KI procedures and the
more ozone-specific chemiluminescence and ultraviolet (UV) photometry methods.
It is generally agreed that part of the disagreement is caused by the usual
precision and accuracy errors associated with the various procedural steps and
part with the difference in response specificity among the various methods.
Thus, all KI methods show response to ozone (O,.) as well as to all vapors
capable of oxidizing iodide ions or reducing iodine. Since these vapors and
O do not all cause equivalent responses, it follows that the KI measurement
reflects not only the concentration but also the compositon — to the extent
that such composition varies — of the responding vapor mixture. Further, the
expected differences in response specificity are larger between the KI methods
and the chemiluminescence and UV methods.
In the face of these differences in precision, accuracy, and response
specificity among the various oxidant/ozone measurement methods, the obvious
question relevant to this analysis is whether these imperfections in the
analytical method invalidate any component of the oxidant control strategy.
To explore this question, the functional relationship between the analytical
method for oxidant/ozone and the oxidant control strategy, first, needs to be
clarified.
Of the various components of the current oxidant control strategy the
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only one linked to the analytical method for oxidant/ozone is that related to
the calculation of emission control requirements. Such calculation requires
that the following three entities be defined:
• present air quality (PAQ), i.e., second highest 1-hour oxidant/ ozone
in the reference year,
• desired air quality (DAQ), i.e., the National Ambient Air Quality
Standard (NAAQS) for oxidant/ozone (0.08 ppm O ), and
• a quantitative relationship between air quality and emission rates.
Of these, PAQ and DAQ are obviously the entities specifically linked to
the oxidant/ozone measurement method. The preceding question, therefore, is
now reduced to whether the analytical method imperfections invalidate (a) the
PAQ data, and (b) the NAAQS for oxidant/ozone. Each of these two cases is
examined separately.
To explore the impact of the analytical method imperfections upon the PAQ
data, it might be useful to break down the impact of such imperfections into
two parts: the impact arising from the usual precision and accuracy errors of
the methods, and the impact arising from the nonspecificity of response. The
precision/accuracy errors vary depending on (a) the method (e.g, KI methods,
chemiluminescence, or UV photometry) and (b) the entity to be measured. To
explain the latter, the magnitude of the precision/accuracy error is greater
when the entity to be measured (i.e., PAQ) is expressed in terms of a single
datum (e.g., second highest value) out of a population of data, than when it
is the population average. Note, however, that the criterion for selecting
the "second highest concentration" or the "average concentration" (or any
other concentration) as the entity to be measured, is not the magnitude of the
analytical error; rather, it is the health effects of oxidant/ozone. EPA has
interpreted the health effects evidence available to mean that oxidant-related
air should be defined in terms of a "highest" or "second highest" rather than
"average" oxidant/ozone concentrations. Whether this interpretation of the
health effects of oxidants/ozone is correct or not is outside the scope of
this analysis. Thus, in the light of this discussion, the first specific
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question that needs to be answered is:
1. Do the precision/accuracy errors invalidate the Federal reference
method for oxidant/ozone? If yes, what method should be chosen
instead?
The impact upon PAQ data of errors related to the specificity of response
is far more complex than that of the precision/accuracy errors. The main
complication arises from the rational requirement that the method measure that
or those chemical species that have been found to have adverse health effects.
However, since an important part of the health effects evidence is of epidemi-
ological nature, those species could not have been specified unequivocally.
This problem was circumvented by devising and using the concept of "surrogate"
species, that is, species believed to represent those with the adverse effects.
EPA initially proposed to promulgate that "oxidants" as measured by a specified
KI method be used as the surrogate species; in the final promulgation, "oxi-
dants" as measured by a (more ozone-specific) chemiluminescence method was
pronounced the surrogate species. Rationally, measurement of PAQ by the
chemiluminescence method should give lower results than by any KI method.
However, there have been reports to be contrary. In the light of this latter
dispute, and of the fact that the intended use of all methods is to measure
surrogate species, the relevant question that must be answered next is:
2. Do the response-specificity errors invalidate the Federal reference
method for oxidant/ozone? If yes, what method should be chosen
instead?
The preceding two paragraphs dealt with the impact of the analytical
method imperfections upon the PAQ data. The remaining discussion will deal
with the impact upon the NAAQS for oxidant/ozone. The first obvious and
direct question to be asked here is:
3. Do the imperfections of the analytical methods for oxidant/ozone
invalidate the air quality standard for oxidant/ozone?
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Following is a proposed answer to this question, and the reviewer judg-
ment called for is on the correctness or incorrectness of this proposed
answer.
The answer to this question, to a large degree, depends on the evidence
and reasoning underlying the development of the air quality standard for
oxidant/ozone. The underlying evidence is known to consist of associations
between adverse effects and concentrations of "oxidants" measured by a variety
of analytical methods. It should be noted that a major part of this associa-
tive evidence is not of a cause-effect nature. This means that the oxidant
species responsible for the adverse effects could not have been unequivocally
specified, which in turn means that the air quality standard did not have to
be defined in terms of one or more specified oxidant species. Thus, the
standard could be defined in terms of surrogate species, that is, in terms of
a "response" given by any "oxidant" measurement method. In conclusion then,
the validity of the qualitative definition of the NAAQS for oxidant/ozone
should not be questioned.
The quantitative part of the (air quality) standard (i.e., the "0.08
ppm") can only be a result of analysis and interpretation of the health
evidence available. Apparently the judgments made by the EPA experts with
respect to the severity of the health effects and to the safety margin required
were such that they justified use of the 0.08-ppm limit as measured by a
specified analytical method (Federal Reference Method). These judgments may
or may not be sound. However, this clearly pertains to another issue, namely
the issue of health justification of the NAAQS-oxidant/ozone, and not to the
issue of oxidant/ozone measurement. In conclusion, again, the imperfections
of the analytical methods do not invalidate the 0.08-ppm of the oxidant/ozone
standard, or, to put it differently, cannot have a much different impact on
the validity of a higher or lower standard.
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REVIEW AND ANALYSIS
James N. Pitts, Jr.
The following remarks deal specifically with questions raised on the
issue of oxidant/ozone measurement in "Part I: Definition of Key Issues"
taken from "An Analysis of the Evidence/Viewpoints Presented at the Inter-
national Conference on Oxidant Problems."
As requested, these comments focus entirely on problems raised by the
differences in precision, accuracy, and response specificity among the various
oxidant/ozone measurement methods, and address "the obvious question relevant
to this analysis is whether these imperfections in analytical method invalidate
any component of the oxidant control strategy." The statements are the views
of this reviewer and do not reflect the view of the Statewide Air Pollution
Research Center (SAPRC) or agencies sponsoring its research.
Before specifically dealing with questions of measurement, it should be
pointed out that establishment of air quality criteria for photochemical
oxidant and reevaluation of the present air quality standard (AQS) involve
questions not only about the precision and accuracy of the monitoring tech-
niques for oxidant/ozone but also about the errors involved in measuring
health effects. That is, when discussing the AQS it must be kept in mind that
dose-response functions will contain errors not only in the "dose" but also in
the determination of the human response to the pollutant. Clearly the errors
in the latter may far exceed the errors involved in analytical measurements of
the dose.
Let us now turn to the first question raised in this section of the issue
paper:
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1. "Do the precision/accuracy errors invalidate the Federal reference
method for oxidant/ozone? If yes, what method should be chosen instead?"
Based on the weight of available evidence from a variety of sources, not
only those presented at the International Conference on Photochemical Oxidant
Pollution, but also on a series of studies conducted in other laboratories, it
is this reviewer's opinion that the answer to this question is a qualified
Yes.
In light of the intensive efforts directed to this question over the last
several years by a variety of investigators, and because the results have been
well reported, it seems unnecessary to go into detail here to justify this
position. Indeed, a relevant discussion of the problem was given by Mr. Roger
Strelow, Assistant Administrator for Air and Waste Management of the EPA, in
his memo of December 18, 1975, to EPA Regional Administrators entitled "Errors
in Ozone/Oxidant Monitoring System." This letter well summarizes the problem
and seems definitive up to that time.
In terms of calibration of ozone monitoring apparatus, I would recommend
either the UV method or gas phase titration. These techniques seem in excel-
lent agreement, not only with each other but also with calibrations performed
using infrared spectroscopy.
In terms of ambient air monitoring both the ultraviolet (UV) and chemilu-
minescent techniques seem acceptable, although somewhat expensive. There are,
however, several relevant points made in the "Definition of Key Issues" on the
use of such specific techniques, which are worth keeping in mind when answering
this question. Thus both the UV and chemiluminescent instruments measure
ozone specifically and do not measure ozone plus the "surrogate species"
associated with it in "photochemical oxidant." The latter, i.e., "oxidant,"
may (or may not) produce health effects significantly greater than just 0 in
air. This point will be raised in more detail in the answer to the second
question.
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A second problem involves the rather high costs and complexity of UV and
chemiluminescent instrumentation relative to typical potassium iodide (KI)
analyzers. However, such considerations as to cost and complexity are beyond
the scope of this discussion.
Finally, one must be concerned not just with the accuracy and precision
of the calibration of various types of instruments but also with the overall
accuracy and precision of analysis (either of specific ozone or of total
oxidant) when the instrument is operating in the field under ambient conditions
and is subject to all the "environmental" stresses present during actual air
monitoring operations. This fact was well pointed out in Mr. Strelow's memo
when he stated:
Recently, the National Bureau of Standards (NBS) and EPA conducted a
joint collaborative test designed to study the overall performar. -" of
typical ozone/oxidant monitoring systems in actual field use. These
tests were conducted using an ozone generator designed by NBS capable o
producing ozone at various concentrations. Field operators experienced
in the use of the FRM for ozone were randomly selected to participate in
the experiment. Ten generators were checked by the NBS laboratory, and
the generated ozone concentrations were assayed by the NBKI procedure and
verified by use of a gas-phase titration (GPT) procedure, another scien-
tifically acceptable way to measure ozone. These generators were then
shipped to ten different locations with instructions for the operators to
prepare their monitoring instruments as they normally would, and then to
measure the output from the ozone generator. Upon completion of the
testing, the ten generators were returned to NBS where confirmation was
made that generator performance had not varied during shipment to and
from the field.
The surprising results from the joint collaborative study revealed
that the monitoring system as a whole, (NBKI calibration procedure,
chemiluminescence monitor, and operator performance) consistently have a
significant negative bias (i.e., indicated an ozone concentration less
than the NBS determined output of the generator). Also there were wide
variations between the performance of the systems from the different
field locations, with an average percentage difference between the
observed generator output and the NBS determined output ranging between
16 and 30 percent over the range of concentrations investigated. Thus
while the NBKI calibration method has been shown to have a positive bias
under ideal conditions, the collaborative study indicates that the
collective performance of the NBKI procedure, the chemiluminescent
monitor, and the average field operator results in a significant and
variable negative bias in the monitoring data. Unfortunately this study
did not address errors in the individual components of the overall system.
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Tests similar to those cited by Mr. Strelow should also be carried out in
the field with analytical systems employing UV monitors, as pointed out
above. Of course, this a,ay already have been done, and if so it will be
interesting to see the results.
It is perhaps worth reemphasizing that wet KI monitors actually measure
photochemical oxidant; they are not specific for ozone. Thus approximately
15% of the nitrogen dioxide (NO,,) and of the peroxyacetyl nitrate (PAN) present
in photochemical smog will be read as oxidant. Conversely, any sulfur dioxide
(SO ) in the air will lower the total oxidant readings, and with 100% efficiency.
In this regard the statement in Part I, "rationally, measurement of PAQ
by the chemiluminescent method should give lower results than by any KI
method," is not strictly correct. For example, if a significant amount of SO
is present along with ozone in ambient air, and only small amounts of NO. are
present the chemiluminescent instrument would, in fact, read higher than the
KI instrument. It is my understanding that this situation does in fact occur
in certain areas. Also, I understand that for certain KI instruments "scrub-
bers" are provided to remove the SO .
While on the subject, it seems to this reviewer that oxidant measurements
in the archival data banks throughout the country should be corrected for
positive interference if NO is present (ambient concentrations of PAN are
generally low enough relative to ozone that the correction for PAN is minor)
and for negative interference if significant levels of SO coexist with the
O . Also, old data should be carefully screened to see if the appropriate
correction from phenolphthalein to KI has been made.
Despite certain problems with the KI method, it seems important for at
least two reasons to retain a wet KI oxidant monitoring instrument along with
specific instruments for O , NO , and SO (as well as others) in air monitoring
J ^ ^
stations throughout the U.S. and, and indeed, the world. Thus, millions of
data have been accumulated over the last two decades of measurements of oxidant
ambient air quality. It would be a shame not to continue using the relatively
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inexpensive KI technique as a "backup" and so that one can directly correlate
(admittedly with appropriate corrections) current and future ambient air data
for oxidant/ozone with those obtained, for example, in the 1960s.
A second, and related, point is that despite problems with accuracy and
precision the wet KI method does give some indication of the concentration not
only of ozone but also of associated surrogate species that may have health
effects. This point has been raised earlier.
Thirdly, it is my understanding that most, if not all, of the data that
were used to generate the dose-response functions, upon which health effects
of photochemical oxidant were based (i.e., in the Air Quality Criteria Docu-
ment) and upon which the present air quality standard is based, were carried
out using a wet method for total oxidant. Therefore, if the response portion
of dose-response functions is based upon data for humans in which, for example,
a KI method was used to determine the exposure of a person to oxidant, then
the dose portion of that curve should be conducted either with the same type
of instrumentation or at least instrumentation that can be reliably related to
that used in the response portion (of course, with appropriate correction
factors).
Questions of the latter type obviously involve the analytical techniques
by which the effects of oxidant on humans were elucidated by medical research-
ers in the past. As stated earlier, this reviewer is not competent to judge
the validity of such health effects studies. However, he urgently recommends
that a panel of medical experts, including several chemists familiar with the
analytical techniques used for oxidant measurements some years ago when these
health effects studies were carried out, be assembled to examine this entire
question very critically, before a decision is made on the validity of the
present AQS for oxidant.
For example, in the Air Quality Criteria Document for Photochemical
Oxidant, apparently the Pasadena asthmatic studies were discussed on the
assumption that the oxidant levels were measured by the phenolphthalein
method. Therefore, apparently these levels were divided by two to convert
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them to equivalent potassium iodide values. It is my understanding from
Professor Edgar Stephens of SAPRC that, "It has since been established that
the original study was not done against phenolophthalein but against KI (L.A.
style) so this division by two was improper."
This referee is not qualified to comment on this particular issue but
Professor Stephens is, and he raises a very interesting point. Indeed, it is
precisely this kind of analysis of "historical" analytical and medical data by
a combined panel of experts, as suggested earlier, that is much needed.
2. "Do the response-specificity errors invalidate the Federal Reference
Method for oxidant/ozone? If yes, what method should be chosen instead?"
This reviewer is not sure of the intent or thrust of this question. As
suggested in the earlier discussion, if one measures photochemical oxidant in
ambient air with instruments specific for ozone but conducts health effects
studies in which total oxidant is measured, then the answer to Question 2 is
Yes. That is, humans may react in one way to the surrogate mixture defined as
"photochemical oxidant" and quite differently to exposures to simulated
atmospheres containing only ozone. Thus, if health effects studies are to be
based on exposures of humans to ozone alone, then the KI Federal reference
method that measures oxidant may be invalid in this context. In short, the
analytical monitoring techniques used to determine human exposure to ozone or
oxidant in the laboratory must be entirely consistent with analytical monitor-
ing techniques used to determine human exposure to ozone or oxidant in real
ambient air.
3. "Do the imperfections of the analytical methods for oxidant/ozone
invalidate the air quality standard for oxidant/ozone?"
As we have seen, the answer to Question 3 can be Yes or No, depending on
the situation. The answer is No if self-consistent measures for determining
the levels of exposures of humans to ozone or oxidant in both the laboratory
and in ambient air are employed by local, state, and federal agencies and by
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researchers in other organizations (including industry and universities) who
are involved with establishing dose-response effects. If there has not been
internal consistency between all investigators involved in establishing dose-
response functions and in interpreting previously established functions of
this type, then the answer is clearly Yes; the air quality standard for
oxidant/ozone will be invalid.
Finally, let us examine the concluding statement on the issue of oxidant/
ozone measurement:
In conclusion, again, the imperfections of the analytical methods do
not invalidate the 0.08-ppm part of the oxidant/ozone standard, or, to
put it differently, cannot have a much different impact on the validity
of a higher or lower standard.
This statement may or may not be correct. If, for example, the correc-
tions made to convert ozone levels measured years ago by the phenolphthalein
technique to the potassium iodide method were incorrect, this could have an
impact on the validity of a higher or lower AQS for oxidant/ozone. Therefore,
such a statement has to be examined very carefully.
Actually, it is this researcher's impression, strictly as a non-expert in
the health effects area, that the major question dealing with the accuracy of
the present air quality standard for oxidant lies in assessing the magnitude
of the errors associated with the determination of human response to oxidant/
ozone rather than with the analytical method used for establishing ozone or
photochemical oxidant concentrations. That is, assuming that in the Federal
reference method there may be errors in accuracy and precision up to perhaps
30% (and this is just an assumption, not necessarily a fact), it is this
reviewer's feeling that such an error may be relatively small compared to
errors associated with the establishment of the health impact of photochemical
oxidant or ozone on man. Of course, this is the point made initially in this
critique. It should be stressed, however, that even if this is true it should
not be used as an excuse to tolerate inaccurate or imprecise techniques for
measuring levels of oxidant/ozone in simulated or real atmospheres.
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REVIEW AND ANALYSIS
George Su
I have reviewed the papers by Paur, Stevens, and Flamm (2); Hodgeson,
Hughes, Schmidt, and Bass (3); Paur et al. (4); DeMore et al. (5); and Neal et
al. H>). Data from all but the last paper presented convincing evidence that
the neutral buffered KI method as it is used now is inaccurate and gives
values generally high by as much as 30%. Furthermore, they showed that the
long path UV photometric and gas phase titration calibration methods are in
good agreement with each other, and are good, valid methods for calibration
and should not have problems with reproducibility. However, DeMore et al.
suggested that the UV photometric method (published in ASTM) should be the
"preferred primary standard" because the gas phase titration method at the
time was considered to be "less well established." Both methods are specific
for ozone. I have but one minor reservation regarding these papers — the
concentrations studied are mostly above the 0.1 ppm level. I would have
preferred to see a few more concentrations below 0.1 ppm, which is where most
oxidant concentrations are observed.
I am convinced that the neutral buffered KI method is not acceptable
because it gives irreproducible results as well as excessively high levels.
Our own laboratory indicates that this method varies as much as 10 to 30%; and
apparently it was recognized by Boyd et al. (Analytical Chemistry) as far back
as 1970 that the neutral buffered system tends to release excessive amounts of
iodine, thereby causing the high readings. Hodgeson et al. also reported a
time-dependence factor over a 30-minute period for color development for the
neutral buffered KI method. In our own laboratory, we see no time dependence
within a 30-minute period. Again, discrepancies of this type between labora-
tories underscored the difficulties with the neutral buffered KI method.
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The boric acid KI method appears extremely promising and would not re-
quire highly sophisticated and expensive instrumentation as in the case of UV
photometry and gas phase titration. Obviously, this metnod deserves more
intensive studies and experimentation and, if proven to be as accurate and
reproducible as it apparently is in these studies, then it, along with the UV
photometry and gas phase titration, should be promulgated as reference methods.
Personally, I am in favor of gas phase titration as a calibration method
for our own laboratory for several reasons:
It can also be used, with minor changes, to calibrate NO analyzers
(already promulgated).
The NO analyzer and the ozone meter required in this calibration
X
system can also be used for monitoring when not being used as a
primary calibration unit.
The long path UV photometry requires considerable lab space and may
be more difficult to operate in our laboratory.
We have already requisitioned a gas phase titration system for calibra-
tion of our ozone meters, in spite of the fact that this method has not been
officially promulgated, because we are convinced of the validity of this
method and that, even if it were not promulgated as a reference or equivalent
method, this calibration system can still be used to calibrate our NO analyers.
The paper comparing chemiluminescent and KI methods seems to me to be of
little value. The authors observed higher ozone than total oxidant, which by
definition should be impossible because ozone is only part of the total oxi-
dant. The KI method is well documented to almost always read higher than the
chemiluminescence method.
I suspect that the reason for the lower total oxidant reading is the
chromium trioxide scrubber that is used with the Beckman Acralyzer using the
neutral buffered KI method. Tne only merit I see in this paper is that it
points out once again the difficulties involved in using the neutral buffered
KI method.
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In summary, based on the data presented in these papers, I am satisfied
that both the UV photometry and the gas phase titration methods are valid and
should be accepted by EPA as reference calibration methods. The neutral
buffered KI method should be withdrawn as a reference method.
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REFERENCES
1. Dimitriades, B., and A.P. Altshuller. International Conference on Oxidant
Problems: Analysis of the Evidence/Viewpoints Presented. Part I.
Definition of Key Issues. J. Air Poll. Control Assoc., 27 (4):299-307,
1977.
2. Paur, R.J., R.K. Stevens, and D.L. Flamm. Status of Calibration for
Ozone Monitors. International Conference on Photochemical Oxidant Pollu-
tion and Its Control, Proceedings. 1:67-72. EPA-600/3-77-001a. Environ-
mental Protection Agency, Research Triangle Park, N.C., 1977.
3. Hodgeson, J.A., E.E. Hughes, W.P. Schmidt, and A.M. Bass. Methodology
for Standardization of Atmospheric Ozone Measurements. International
Conference on Photochemical Oxidant Pollution and Its Control, Proceed-
ings. 1:3-12. EPA-600/3-77-001a. Environmental Protection Agency,
Research Triangle Park, N.C., 1977.
4. Paur, R.J., R.E. Baumgardner, W.A. McClenny, R.K. Stevens. Status of
Methods for Calibration of Ozone Monitors. Ln D.F. Adams and L.H. Keith
(ed.) Preprints of Papers Presented at the 171st National Meeting. Vol.
16, No. 1. American Chemical Society, Division of Environmental Chemistry.
1976.
5. DeMore, W.B., T.C. Romanovsky, M. Feldstein, W.J. Hamming, and P.K.
Mueller. Interagency Comparison of lodometric Methods for Ozone Deter-
mination. In_ Calibration in Air Monitoring. ASTM STP 598, p. 131-143.
American Society for Testing and Materials, Philadelphia, Pa., 1976.
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Neal, R., R. Severs, L. Wenzel, and K. MacKenzie. Simultaneous Chemilu-
minescent Ozone and KI Oxidant Measurements in Houston, Texas, 1975.
Ozone/ Oxidants — Interactions with the Total Environment. APCA Specialty
Conference (Southwest Section), Proceedings. p. 180-188. Air Pollution
Control Association, Pittsburgh, Pa., 1976.
20
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TECHNICAL REPORT DATA
(Please read Iiiuiiiclions on the »vi i rsc hi Inn-i omph
1 REPORT NO.
EPA-600/3-77-119
RECIPIENTS ACCiSSIO^NO,
4 TITLE AND SUBTITLE
INTERNATIONAL CONFERENCE ON OXIDANTS, 1976 -
ANALYSIS OF EVIDENCE AND VIEWPOINTS
Part VII. The Issue of oxidant/ozone Measurement
7 AUTHOR(S)
1. James N. Pitts, Jr.
2. George Su
DATE
6 PERFORMING ORGANIZATION CODE
8 PERFORMING ORGANIZATION REPORT NO
9 PERFORMING ORGANIZATION NAME AND ADDRESS
1. Univ. of California, Riverside, CA
2. Dept. of Natural Resources, Lansing, MI
MO, PROGRAM CLEMENT NO
1AA603 AJ-13 (FY-76)
11 CONTRACT.GRANT NO
1. DA-7-2142A
! 2. DA-7-2044A
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory - RTF, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13 TYPE OF REPORT AND PERiOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
Partially funded by the Office of Air Quality Planning and Standards.
16. ABSTRACT
In recognition of the important and somewhat controversial nature of the
oxidant control problem, the U.S. Environmental Protection Agency (EPA)
organized and conducted a 5-day International Conference in September 1976.
The more than one hundred presentations and discussions at the Conference
revealed the existence of several issues and prompted the EPA to sponsor a
follow-up review/analysis effort. The follow-up effort was designed to review
carefully and impartially, to analyze relevant evidence and viewpoints reported
at the International Conference (and elsewhere), and to attempt to resolve
some of the oxidant-related scientific issues. The review/analysis was con-
ducted by experts (who did not work for the EPA or for industry) of widely
recognized competence and experience in the area of photochemical pollution
occurrence and control.
The issue of oxidant/ozone measurement is discussed in Part VII by James
N. Pitts, Jr. of the Statewide Air Pollution Research Center, University of
California at Riverside, and George Su of the State of Michigan Department of
Natural Resources in Lansing. Analytical measurement techniques are compared
and recommendations for improvements are made.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
* Air pollution
* Ozone
* Measurement
b. IDENTIFIERS/OPEN ENDED TERMS •-. COSATI I icld/Group
13B
07B
3. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19 SECURITY CLASS I'lhis Rt-pom
UNCLASSIFIED
20 S E C U R! T Y C L ASS i This pane/
UNCLASSIFIED
21. NO OF PAGES
27
22 PRICE
EPA Form 2220-1 (9-73)
21
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