EPA-600/3-75-010a
September 1975
Ecological Research Series
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH series.
This series describes research on the effects of pollution on
humans, plant and animal species, and materials. Problems are
assessed for their long- and short-term influences. Investigations
include formation, transport, and pathway studies to determine the
fate of pollutants and their effects. This work provides the
technical basis for setting standards to minimize undesirable
changes in living organisms in the aquatic, terrestrial and
atmospheric environments.
This document is available to the public through the National
Technical Information Service, Springfield, Virginia 22161.
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EPA-600/3-75-010a
September 1975
ANNUAL CATALYST RESEARCH PROGRAM REPORT
Summary
by
Criteria and Special Studies Office
Health Effects Research Laboratory
Research Triangle Park, North Carolina 27711
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
HEALTH EFFECTS RESEARCH LABORATORY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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CONTENTS
Page
CATALYST RESEARCH PROGRAM ANNUAL REPORT
EXECUTIVE SUMMARY 1
INTRODUCTION 5
PROGRAM SUMMARY . 7
TECHNICAL CONCLUSIONS 17
DISCUSSION 22
REFERENCES 45
APPENDICES TO CATALYST RESEARCH PROGRAM ANNUAL REPORT
VOLUME 1
A. OFFICE OF AIR AND WASTE MANAGEMENT
A1. AUTOMOTIVE SULFATE EMISSIONS 1
A2. GASOLINE DE-SULFURIZATION - SUMMARY 53
A2.1 Control of Automotive Sulfate Emissions
through Fuel Modifications 55
A2.2 Production of Low-sulfur Gasoline. ..... 90
VOLUME 2
B. OFFICE OF RESEARCH AND DEVELOPMENT
Bl. FUEL SURVEILLANCE
B1.1 Fuel Surveillance and Analysis 1
B1.2 The EPA National Fuels Surveillance
Network. I. Trace Constituents in Gasoline
and Commercial Gasoline Fuel Additives. . . 19
B2. EMISSIONS CHARACTERIZATION
B2.1 Emissions Characterization Summary .... 44
B2.2 Sulfate Emissions from Catalyst- and Non-
catalyst-equipped Automobiles 45
B2.3 Status Report: Characterize Particulate
Emissions - Prototype Catalyst Cars .... 68
B2.4 Status Report: Characterize Particulate
Emissions from Production Catalyst Cars . . 132
B2.5 Status Report: Survey Gaseous and Particu-
late Emissions - California 1975 Model Year
Vehicles 133
B2.6 Status Report: Characterization and Meas-
urement of Regulated, Sulfate, and Particu-
late Emissions from In-use Catalyst Vehicles -
1975 National Standard 134
B2.7 Gaseous Emissions Associated with Gasoline
Additives - Reciprocating Engines. Progress
Reports and Draft Final Report - "Effect of
Gasoline Additives on Gaseous Emissions" . . 135
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VOLUME 3
Page
B2.8 Characterization of Gaseous Emissions from
Rotary Engines u^'r.g Additive Fuel -
Progress Reports 220
B2.9 Status Report: Exploratory Investigation of
the Toxic and Carcinogenic Partial Combus-
tion Products from Oxygen- and Sulfur-
containing Additives 232
B2.10 Status Report: Exploratory Investigation of
the Toxic and Carcinogenic Partial Combus-
tion Products from Various Nitrogen-
containing Additives 233
B2.11 Status Report: Characterize Diesel Gaseous
and Particulate Emissions with Paper "Light-
duty Diesel Exhaust Emissions" 234
B2.12 Status Report: Characterize Rotary Emissions
as a Function of Lubricant Composition and
Fuel/Lubricant Interaction 242
B2.13 Status Report: Characterize Particulate
Emissions - Alternate Power Systems (Rotary) . .243
B.3 Emissions Measurement Methodology
B3.1 Emissions Measurement Methodology Summary ... 1
B3.2 Status Report: Develop Methods for Total
Sulfur, Sulfate, and other Sulfur Compounds
in Particulate Emissions from Mobile Sources ... 2
B3.3 Status Report: Adapt Methods for SO and SO
to Mobile Source Emissions Measurements 3
B3.4 Evaluation of the Adaption to Mobile Source
SO? and Sulfate Emission Measurements of
Stationary Source Manual Methods 4
B3.5 Sulfate Method Comparison Study. CRC APRAC
Project CAPI-8-74 17
B3.6 Determination of Soluble Sulfates in CVS
Diluted Exhausts: An Automated Method 19
B3.7 Engine Room Dilution Tube Flow Characteristics- 41
B3.8 An EPA Automobile Emissions Laboratory 52
B3.9 Status Report: Protocol to Characterize Gaseous
Emissions as a Function of Fuel and Additive
Composition - Prototype Vehicles 89
B3.10 Status Report: Protocol to Characterize Particu-
late Emissions as a Function of Fuel and Additive
Composition 90
B3.11 Interim Report and Subsequent Progress Reports:
Development of a Methodology for Determination
of the Effects of Diesel Fuel and Fuel Additives
on Particulate Emissions 192
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Prge
B3.12 Monthly Progress Report #7: Protocol to
Characterize Caseous Emissions as a Function
of Fuel and Additive Composition .200
B3.13 Status Report: Validate Engine Dynomometer Test
Protocol for Control System Performance 218
B3.14 Fuel Additive Protocol Development 221
B3.15 Proposed EPA Protocol: Control System
Performance 231
VOLUME 4
B3.16 The Effect of Fuels and Fuel Additives on Mobile
Source Exhaust Particulate Emissions 1
VOLUME 5
B3.17 Development of Methodology to Determine the
Effect of Fuels and Fuel Additives on the Perform-
ance of Emission Control Devices 1
B3.18 Status of Mobile Source and Quality Assurance
Programs 260
VOLUME 6
B4. Toxicology
B4.1 Toxicology: Overview and Summary 1
B4.2 Sulfuric Acid Effect on Deposition of Radioactive
Aerosol in the Respiratory Tract of Guinea Pigs,
October 1974 38
B4.3 Sulfuric Acid Aerosol Effects on Clearance of
Streptococci from the Respiratory Tract of Mice.
July 1974 63
B4.4 Ammonium and Sulfate Ion Release of Histamine
from Lung Fragments 89
B4.5 Toxicity of Palladium, Platinum and their
Compounds 105
B4.6 Method Development and Subsequent Survey
Analysis of Experimental Rat Tissue for PT, Mn,
and Pb Content, March 1974 128
B4.7 Assessment of Fuel Additives Emissions Toxicity
via Selected Assays of Nucleic Acid and Protein
Synthesis 157
B4.8 Determination of No-effect Levels of Pt-group
Base Metal Compounds Using Mouse Infectivity
Model, August 1974 and November 1974 (2
quarterly reports) 220
B4.9 Status Report: "Exposure of Tissue Culture
Systems to Air Pollutants under Conditions
Simulating Physiologic States of Lung and
Conjunctiva" 239
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Page
B4.10 A Comparative Study of the Effect of inhalation of
Platinum, Lead, ar.J Other Base Metal Compounds
Utilizing the Pulmonary Macrophage as an Indicator
of Toxicity 256
B4.11 Status Report: "Compare Pulmonary Carcinogenesis
of Platinum Group Metal Compounds and Lead Com-
pounds in Association with Polynuclear Aromatics
Using [r^ vivo Hamster System . 258
B4.12 Status Report: Methylation Chemistry of Platinum,
Palladium, Lead, and Manganese 263
VOLUME 7
B.5 Inhalation Toxicology
B5.1 Studies on Catalytic Components and Exhaust
Emissions 1
B.6 Meteorological Modelling
B6.1 Meteorological Modelling - Summary 149
B6.2 HIWAY: A Highway Air Pollution Model ...... .151
B6.3 Line Source Modelling 209
B.7 Atmospheric Chemistry
B7.1 Status Report: A Development of Methodology to
Determine the Effects of Fuel and Additives on
Atmospheric Visibility 233
Monthly Progress Report: October 1974 255
B7.2 Status Report: Develop Laboratory Method for Collec-
tion and Analysis of Sulfuric Acid and Sulfates -259
B7.3 Status Report: Develop Portable Device for Collection
of Sulfate and Sulfuric Acid 260
B7.4 Status Report: Personal Exposure Meters for
Suspended Sulfates 261
B7.5 Status Report: Smog Chamber Study of SO?
Photo-oxidation to SO under Roadway
Condition - 262
B7.6 Status Report: Study of Scavenging of S0? and
Sulfates by Surfaces near Roadways 263
B7.7 Status Report: Characterization of Roadside
Aerosols: St. Louis Roadway Sulfate Study 264
B7.8 Status Report: Characterization of Roadside
Aerosols: Los Angeles Roadway Sulfaite Study -269
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Page
VOLUME 8
B.8 Monitoring
VOLUME 9
B.9
B8.I Los Angeles Catalyst Study. Background Pre-
liminary Report 1
B8.2 Los Angeles Catalyst Study; Summary of Back-
ground Period (June, July, August 1974) 13
B8.3 Los Angeles Catalyst Study Operations Manual
(June 1974, amended August 1974) 33
B8.4 Collection and Analysis of Airborne Suspended
Particulate Matter Respirable to Humans for
Sulfates and Polycyclic Organis (October 8, 1974) -194
Human Studies
39.1 Update of Health Effects of Sulfates, August 28, 19741
B9.2 Development of Analytic Techniques to Measure
Human Exposure to Fuel Additives, March 1974 . . 7
B9.3 Design of Procedures for Monitoring Platinum
and Palladium, April 1974 166
B9.4 Trace Metals in Occupational and Non-occupation-
ally Exposed Individuals, April 1974 178
B9.5 Evaluation of Analytic Methods for Platinum and
Palladium 199
B9.6 Literature Search on the Use of Platinum and
Palladium 209
B9.7 Work Plan for Obtaining Baseline Levels of Pt
and Pd in Human Tissue 254
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CATALYST RESEARCH PROGRAM
ANNUAL REPORT
Office of Research and Development
and
Office of Air and Waste Management
U. S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
National Environmental Research Center
Research Triangle Park, North Carolina
June 1975
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EXECUTIVE SUMMARY
EPA Administrator Russell Train's mandate for an accelerated and
expanded research program on the mobile source oxidation catalytic con-
verter in late 1973 initiated the development of interdisciplinary
examination of the potential public health impact of both regulated and
unregulated emissions from catalyst-equipped vehicles by both the Office
of Research and Development and the Office of Air and Waste Management.
The strategy underlying the establishment of the program can briefly be
summarized in the following five objectives:
1. Identify emissions
2. Determine emission factors
3. Estimate human exposure
4. Assess public health impact
5- Evaluate control options
6. Provide timely reports to provide basis
for management decisions
Within this framework, the resources available both within EPA and
in the research community were marshalled to address the issue. The
program areas involved in the effort have been as follows:
1. Emissions characterization
2. Emission measurement methodology development
3. Meteorological modelling
4. Toxicology (classical and inhalation)
5. Human health studies (epidemiology, occupational exposure)
6. Control technology
Each of the above areas of expertise impinges upon one or more of
the others; this fact necessitated from the beginning of the program
close coordination, clear definition of objectives and methods, and
centralized program direction. Since the program cut across traditional
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organization structures, a matrix approach emerged as the appropriate
management tool for effective use of disparate and diverse resources
both human and financial. The specific areas of research completed,
current, and planned are treated in thlc report according to these
program areas in identified appendices, but conclusions regarding the
implications of the results of these research efforts must and will be
evaluated as an integrated body of knowledge.
Summary technical conclusions based upon results of the program
to date are as follows:
1. Our current (1974 model year and older) in-use light-
duty motor vehicle population emits trace quantities
of sulfuric acid.
2. Current ambient sulfate particulate levels reported by
epidemiological studies (CHESS) already exceed the
estimated health effects threshold many days of the year
in many urban centers, particularly in the northeastern
United States.
3. Oxidation catalyst-equipped light-duty motor vehicles
emit sulfuric acid aerosol. While non-catalyst-equipped
vehicles appear to convert about 1% of fuel sulfur to
sulfuric acid, catalyst cars convert 20 to 40% of such
sulfur to sulfuric acid with air-injected catalyst-equipped
vehicles being the higher emitters.
4. Catalyst-generated sulfuric acid aerosol will result in
localized incremental exposures to persons on and near
major highways and other areas of high motor vehicle
density.
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5. The catalyst-generated localized incremental sulfuric
acid exposures are projected to exceed the estimated
health effects threshold 2 years after vehicles have been
equipped with catalysts in California and (after 3 to 4
years in the rest of the nation). Such exposures will
occur on and near our busiest highways.
6. Development of a reliable analytical measurement method
specific to ambient sulfuric acid is crucial, as no
specific method now exists The wet chemical techniques
for ambient particulate sulfate are not necessarily
specific for sulfates; sulfides and sulfites, if present
will interfere. Thus, the present techniques measure
total particulate water soluble sulfur compounds.
7. Existing (pre-catalyst) baseline data establishing
current rural, urban, and occupationally-exposed
human burdens of platinum and palladium needs to be
clearly defined and are under investigation.
8. Research into long-term health effects of platinum,
palladium, and sulfuric acid must be continued.
9. Methods to control sulfuric acid emissions from catalyst-
equipped vehicles must be pursued.
10. Preliminary pre-catalyst baseline studies on the Los
Angeles freeway monitoring site tend to confirm via CO,
Pb, and S0? surrogates the projected incremental sulfuric
acid exposures.
Policy implications of the above technical conclusions are as
follows:
1. Data or ambient and exhaust sulfate levels available
thus far suggest that an ambient standard for sulfates
be considered.
3
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For the same reasons, the feasibility and desirability
of controlling motor vehicle emissions of sulfate
must also be considered.
Resolution must be made between the fact that current
suggested threshold health effects levels of sulfates
may be exceeded on and near major highways within
two years and the fact that the earliest possible
date of application of controls for motor vehicle
sulfate emissions would very likely be three years hence,
at a minimum.
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INTRODUCTION
Section 202 of the Clean Air Act of 1970, as amended, mandated
substantial reductions in certain specified emission products from
automobiles. The automotive industry, to achieve this reduction, chose-
the oxidation catalytic converter as a primary method of emission
control for model year 1975. After this decision was made known to EPA
the Agency intensified its research program to determine what, if any,
new pollutants might be emitted into the atmosphere as a result of the
application of this technology. Also studied were the effects of fuel
composition and fuel additives on these, as well as regulated, emissions.
The EPA research program results indicated that though emissions of
hydrocarbons, carbon monoxide, and certain organics would be dramatically
lowered, sulfuric acid aerosol emissions would increase, and slight emissions
of platinum, palladium, and alumina might also be expected.
Since existing ambient concentrations of sulfates in many areas of
the country have been shown to be at levels sufficient to cause concern
to those in EPA and elsewhere responsible for the protection of public
health, and since very little information existed regarding health effects
of platinum or palladium as air pollutants, EPA initiated a broad research
program to examine the questions of public health impact of these three
pollutants: catalyst-emitted sulfates, platinum, and palladium.
In testimony to the Public Works Committee of the U. S. Senate,
Administrator Train specified EPA's planned program of catalyst-related
research:
1. Accelerate work on development of a reliable test procedure
for automotive sulfate emission measurement.
2. Consider all feasible alternatives for automotive
sulfate emission control.
3. Improve the Agency's ability to estimate the public
health impact of sulfate and other automotive emissions.
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4. Improve understanding of the atmospheric chemistry
involved in these emissions and initiate an appropriate
air monitoring program.
From these broad objectives defined in Administrator Train's
testimony of November 1973, an extensive interdisciplinary research
program utilizing the resources of a broad range of EPA's technical
staff both with the Office of Research and Development and the Office
of Air and Waste Management and of the scientific community outside
the government through extramural programs, was developed. The
program has been designated as priority number one in EPA's research
effort. This program has now completed its first six months of effort.
The results are summarized in the following report, which will be the
first of a series to be issued annually through at least 1977.
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PROGRAM SUMMARY
The thrust of the catalyst research program is to evaluate the
potential public health impact of emissions unique to catalyst-equipped
automobiles. The issue is a complex one, requiring the best efforts
of scientific and technical staff from several disciplines. Although
many other fields of scientific/technical study are tangentially related
to the catalyst program, the major program areas involved are as follows:
1. emi ssions character!'zation - necessary to determine what
specific chemical elements and/or compounds should be
studied to assess health effects and whether new or higher
levels of pollutants are present
2. emissions measurement methodology development - necessary
to assign quantitative numbers to levels of a given
pollutant for purposes of comparison, and to assign rela-
tive priorities related to projected public exposures
3. meteor o 1 o g i c a 1 mode11ing - necessary to project dispersion
route of pollutants from the source through ambient air
to determine probable areas and levels of exposure resulting
from given source emissions
4. toxicology - necessary to determine the risk to health
posed by a given substance relative to compounds known
to have serious adverse health effects
5. human studies - necessary to determine the effects of
chronic or intermittent exposure to substances on human
health, both reversible and irreversible, and relative
to both the general population and to high risk populations
(once identified)
6. control technology - necessary to evaluate the feasibility
and effectiveness of means of controlling emissions of
pollutants shown to have adverse health or welfare effects
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In the catalyst research program, the first program area has been a
joint Office of Research and Development and Office of Air and Waste
Management effort; the next four program areas have been the responsibility
of the Office of Research and Development; the sixth has been that of
the Office of Air and Waste Management. In addition to research specifically
addressed to the catalyst issue, many continuing programs basic to the
Agency's total research effort are related and will be included when
appropriate.
Specific research tasks within the ORD catalyst research program
are listed below. The currently available information on each such
area is discussed in the "technical conclusions" section, and further
information is contained within the detailed technical appendices of
this report.
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TASK DESCRIPTIONS - ORD PROGRAM
ORD Program Element 1AA002, "Fuel and Fuel Additive Registration"
Emission Characterization (Appendix B2)
ORD Research Objective Achievement Plan (ROAP) 21BCE --
"Health and welfare impact of catalysts used in the control of
mobile sources of air pollutants"
Task
001 Survey and gaseous particulate emissions - California 1975
model year vehicles
002 Characterize particulate emissions, prototype catalyst cars
044 Characterize particulate emissions from production catalyst-
equipped cars
045 Operate dynamometer and test equipment in support of catalyst-
related emissions method development and characterization
studies
046 Procure test and data acquisition equipment in support of
catalyst-related emissions testing program
070 In-house and field evaluation of existing analytical sampling
and analysis schemes pertinent to the determination of pollu-
tants emanating from catalyst-equipped automobiles
082 Characterization and measurement of regulated, sulfate, and
particulate emissions from in-use catalyst vehicles - 1975
national standard
ORD Research Objective Achievement Plan (ROAP) 26AAE --
"Development of information for fuel and fuel additives control
or prohibition"
012 Characterize current vehicle gaseous emissions
014 Characterize alternate power systems (rotary)
017 Characterize particulate emissions - alternate power systems
(rotary). Develop protocol
018 Characterize detailed gaseous and particulate emissions --
non-catalytic advanced control prototypes
019 Characterize diesel gaseous and particulate emissions
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2. Emissions Measurement Methodology (Appendix B3)
ORD Research Objective Achievement Plan (ROAP) 21BCE
"Health and welfare impact of catalysts used in the control of
mobile sources of air pollutants"
Task
004 Develop methodology to determine the effect of gas composi-
tion and additives on emissions control device performance
039 Analysis of "unusual" emissions from current and future
mobile sources impact of control devices
042 Adapt methods for SOp and SO., to mobile source emissions
measurement
043 Develop methods for total sulfur, sulfate, and other sulfur
compounds in particulate emissions from mobile sources
056 Standardized methods for measurement of and collection and
analysis of particulate sulfates
057 Quality assurance guidslines for measurement methods applicable
to mobile sources and fuels and fuel additives
058 Development of standard reference materials for emissions from
mobile sources and fuels and fuel additives
059 Collection and analysis of samples at selected sites, including
sulfate, trace metals, and nitrates
060 Collection and analysis of samples at selected sites, including
sulfate, trace metals, and nitrates
061 Determination of various pollutants in TSP, fine particulate,
and soil samples
064 Survey and evaluate analytical methods pertinent to Task 065 and
066
065 Standardized method for measurement of exhaust and ambient sulfates
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066 Standardized methods for noble metals and catalyst supnort
materials
067 Develop standard reference materials for mobile source
pollutants measurements
068 Conduct inter!aboratory performance surveys for sulfate and
catalyst-related particulates
070 In-house and field evaluation of existing analytical sampling
and analysis schemes pertinent to the determination of pollu-
tants emanating from catalyst-equipped automobiles
3. Fuel Collection and Analysis (Appendix Bl)
Research Objective Achievement Plan (ROAP) 21BCE
Task
055 Commercial fuels collection and analysis
062 Maintain national sample bank and implement data acquisition
and processing system
063 Expand network for collection and analysis of fuel samples
specificially in southern California in support of cataTyst
field program
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4. Toxicology (Appendix B4)
Research Objective Achievement Plan (ROAP) 21BCE
Task
005 Estimate no-effect level using mouse pulmonary infectivity
model
fa) of appropriate Pt-group metal compounds administered
singly
(b) of base metal compounds administered in appropriate
combination
006 Compare relative toxicity against Pb compounds using in vitro
macrophage system -- of Pt-group compounds ~~
007 Compare relative toxicity against Pb compounds using in vitro
conjunctiva! cell and respiratory epithelial cell cultures --
of Pt-group compounds
008 Estimate no-effect level of Pt-group metal compounds using
immediate and delayed allergic response in animals
009 Compare relative cytogenicity against Pb compounds using i_n_ vivo
hamster system
(a) of Pt-group compounds
(b) of base metal compounds
010 Compare relative mutagenicity of Pb compounds using host-
mediated assay system
Oil Compare relative toxicities against Pb compounds using biochemical
parameters
(a) of Pt-group compounds
(b) of base metal compounds
012 Compare pulmonary carcinogenicity of Pt-group metal compounds and of
Pb compounds in association with polynuclear armoatics using j_n
vivo hamster system
12
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022 Comparative methylation chemistry of Pt-group compounds,
selected base metals, and lead with subsequent toxicoloqical
assessment of stable metallic compounds
025 Analysis of animal tissues for platinum, palladium, lead,
and manganese
074 Toxicology of respirable sulfur compounds
075 lexicological evaluation of airborne respirable particulates
and mists
5. Inhalation Toxicology (Appendix B5)
ORD Program Element 1AA007
Research Objective Achievement Plan (ROAP) 21AFK
Office of Research and Development
National Environmental Research Center
Environmental Toxicology Laboratory
Cincinnati, Ohio
ORD Program Element 1AA002
Research Objective Achievement Plan (ROAP) 21BCE
Task
013 Toxicological evaluation of whole engine exhausts from
catalytic-controlled systems
076 Comparative inhalation toxicology specific to catalyst
nonregulated emissions
077 Long-term, low-level comparative inhalation toxicology
specific to nonregulated emissions from oxidation
catalvsts
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6. Meteorology (Appendix B6)
Research Objective Achievement Plan (ROAP) 21BCE
Task
027 Validation of highway gaseous dispersion model for simulation
of air quality
028 Conduct wind tunnel experiments to evaluate current highway
model for gaseous emissions. Monitor Tasks 029/030 --
prepare reports
029 Evaluate applicability of highway gaseous dispersion model
for mobile source particulate and aerosol species
030 Develop and evaluate dispersion model for complex mobile
sources
7. Atmospheric Chemistry (Appendix B7)
Research Objective Achievement Plan (ROAP) 21BCE
Task
003 Visibility effects of catalyst and non-catalyst advanced
prototype vehicles
040 Atmospheric chemistry of acid aerosols
041 Personal exposure meters for suspended sulfates
048 Particle size, chemical characterization, formation, and
growth roles of scattering roadside aerosols
049 Study of scavenging of S02 and sulfates by surfaces near
roadways
050 Smog chamber study of S02 photo-oxidation to SO. under
roadway conditions
052 Develop portable device for collection of sulfate and
sulfuric acid
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053 Develop laboratory method for collected sulfate and sulfuric
acid aerosols
054 Fabricate 12 portable samplers for measurement of sulfuric
acid
079 Characterization of roadside aerosols for St. Louis.
Particle size, chemical composition, formation, growth, and
light scattering of roadside aerosols
8. Monitoring (Appendix B8)
Research Objective Achievement Plan (ROAP) 21BCE
Task
024 Monitor air quality along a major highway in southern
California. Utilizing existing methods, analyze water-
soluble sulfate, lead, and TSP at 4 sites and CO at 1
or 2 sites. Additionally, 1 meteorology station will
be established and total motor vehicle count (not
vehicle mix) at 1 site will be made (4-month task).
(FY 74)
071 Same as Task 069 with the addition of traffic mix data,
TSP, size distribution at one station, one or two
additional hi-vols at a distance away from the highway,
and of TSP samples. (Pt methodology is not fully de-
veloped, coordination needed with CPL). (3-year study)
072 Handling, validating, and interpreting data from southern
California, and complex source studies, including report
writing and computer costs
073 Monitor complex sources such as street canyons, shopping
centers, and parking garage in southern California for
mobile source pollutants (FY 76)
080 Assist in sampling and analysis for Los Angeles Catalyst
Study (LACS). (Task 071)
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9. Human Studies (Appendix B9)
Research Objective Achievement Plan (ROAP) 21BCE
Task
014 Effects of chronic or intermittent exposure to low levels
of major catalyst attrition products or their decay products
on human pollutant burdens
015 Effects of above (14) on irritation symptoms in humans
016 Assessment of subtle physiologic changes induced by exposure
to major catalyst attrition products or their decay products,
enzyme changes, immunologic deficits, chromosomal abberations,
etc.
031 Public health impact of suspended particulate sulfates
032 Public health impact of suspended particulate sulfates
033 Analysis of tissue samples collected throughout CHESS network
to assess population pollutant burdens of Pt, Pd, and Al
034 Clinical studies of human response to noble metals
035 Effects of controlled exposure to specific particulate
pollutants on immune response
036 Effect of particulate sulfates and noble metals on human
behavior
037 Effects of ambient exposure to selected chemical particulates
on the occurrence of carcinogenic or mutagenic effects
038 Comprehensive PFT on high risk population
081 Development of sensitive biochemical and behavioral indicators
of trace substance exposure
10. Control Technology (Appendix A)
Office of Air and Waste Management
16
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TECHNICAL CONCLUSIONS
This first annual research report contains information on research
programs principally initiated during the current fiscal year. Thus,
the technical conclusions reviewed herein are largely based upon pre-
liminary data. Based upon these studies, the following conclusions have
been drawn:
1. Two collection methods have been employed by EPA and
industry laboratories in effort to ascertain the
emission rate of sulfuric acid from non-catalyst and
catalyst-equipped vehicles. Data derived from the
application of the stationary source Method 8 technique
suggested that sulfuric acid was emitted from both non-
catalyst- and catalyst-equipped vehicles. The air-diluted
particulate method suggested that only trace amounts of
sulfuric acid was emitted from non-catalyst vehicles,
while significant quantities were emitted from catalyst-
equipped vehicles. The Method 8 technique has now been
shown to generate artifact sulfate. We now believe that
only the air-diluted particulate collection procedures
provide valid sulfuric acid collection from mobile sources.
2. Current data indicate that non-catalyst-equipped vehicles
emit only trace quantities of sulfuric acid whether
equipped with air pumps or not.
3. Catalyst-equipped vehicles do convert some of the fuel
sulfur combusted to sulfuric acid which is emitted in a
fine aerosol form. The earlier EPA emission factor estimate
of 0.05 gm/mile sulfuric acid for a fuel containing 300 ppm
sulfur is now felt to be approximately correct. However,
certain catalyst types make a precise estimate of the
emissions factor very difficult due to severe sulfate
17
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storage and release phenomena, making estimates
based upon emission rates from catalyst-equipped
vehicles operated on the Federal Test Procedures
unreliable.
4. The Federal Test Procedure (CVS-75) cannot be used
as a basis for determining sulfuric acid emission
rates from catalyst-equipped vehicles due to catalyst
sulfate storage problems. Work is under way to
attempt to derive an appropriate test cycle to permit
correlation of sulfuric acid emissions with localized
air quality exposure projections.
5. Sulfuric acid emission rates from oxidation catalyst-
equipped vehicles are dependent not only upon catalyst
type, as noted in 3 and 4 above, but also upon fuel sul-
fur levels, fuel economy, mode of vehicle operation,
catalyst preconditioning, and catalyst age. These
factors compound the researcher's problem in attempting
to derive a meaningful emission factor.
6. An automated method has been developed and tested for the
determination of sulfuric acid concentrations from the
exhaust air-diluted particulate collection procedure. A
multi-laboratory analysis round-robin is currently under
way to ascertain the reproducibility of the sulfuric acid
measurement techniques. The method appears to be highly
reliable, reproducible, and accurate. The methods (air-
dilution collection and automated SO, method) have been
installed and are operating in the OAWM Ann Arbor
emissions laboratory.
18
-------
7. The use of oxidation catalysts on motor vehicles results
in a substantial decrease in the emissions of carbon
monoxide, unburned hydrocarbons, phenols, aldehydes,
polynuclear aromatic hydrocarbons, and organic pani-
culates. This is a positive public health benefit.
8. Several sulfuric acid emission control techniques are
under investigation. Fuel desulfurization is one such
approach which will, of course, reduce such emissions.
Preliminary technical feasibility, cost, timing, and
impact studies have been completed. Other approaches
being pursued include a sulfate emission standard, a
particulate emission standard, potential low-sulfate
emission catalyst systems, and sulfate traps.
9. While earlier work with pre-production catalysts indicated
that some of the catalyst substrate and active components
(platinum and palladium) were emitted as particulate, recent
studies by EPA and industry laboratories with production
catalysts suggest that such emissions are at extremely low
levels. What, if any, such emissions occur during or after
catalyst poisoning or thermal failure is not, however,
known at this time.
10. Insufficient information is available to assure that the
public health will not be adversely affected by the platinum
and palladium used in current oxidation catalysts. While
studies to determine living human burdens of these metals in
urban and rural settings are nearing completion, occupationally
exposed persons have not been examined as yet. The available
toxicological, biological, and human data suggests that
the public health will likely not be adversely affected
19
-------
by the introduction of noble metal catalysts in the
short term. Long range chronic studies are, of course,
not completed nor are the methylation chemistry studies
currently under way.
11. Emission data and baseline pre-catalyst datalyst data
from the Los Angeles area freeway monitoring site suggest
that the earlier projections presented in the Agency
technical papers on the subject to the Senate Public Works
Committee on January 11, 1974, are valid. That is,
incremental localized exposures to sulfuric acid generated
from catalyst-equipped vehicles will exceed the estimated
health effects threshold several days per year on our
busiest freeways after two model years of vehicles are
equipped with such devices. These projections assume that
25% of the vehicles miles are driven with catalyst-
equipped vehicles. Because all 1975 vehicles are not
equipped with catalysts, with the exception of California,
and due to the fact that the '75 interim emissions standards
will be in effect through model year 1976, at least,
these projections appear valid for California only. We,
therefore, expect that major urban centers outside California
would not experience these incremental exposure levels
for at least three years. Decreased sales of new motor
vehicles at levels less than recent years, increased
purchases of vehicles with improved fuel economy, and
decreased vehicle miles driven would all tend to stretch
out the time required to generate adverse incremental
exposures.
12. Current ambient sulfate levels already exceed the estimated
health effects threshold many days of the year in our major
Northeastern urban centers.
20
-------
13. No proven measurement method now exists to permit the
accurate analysis of sulfuric acid aerosols in ambient
air. Work to develop such techniques is being vigorously
pursued.
21
-------
Discussion
This first annual research report on EPA's catalyst emissions
research program is intended to provide both an overview, with preliminary
conclusions, and the details of the research information currently
available from the program. This report will be updated on an annual
basis. It is our intention that this report provide a brief overview of
the program and the conclusions. The technical appendices provide an
in-depth view of the many individual research efforts which comprise the
total program.
Over 2 years ago, it was first recognized by a contractor to EPA
that particulate emissions from catalyst-equipped vehicles operating
on lead-free fuel were substantially higher than from non-catalyst
vehicles operating on the unleaded fuel. The contractor, in cooperation
with Ford Motor Company scientists, identified the bulk of the additional
particulate generated as sulfuric acid. These findings prompted the EPA
laboratories in Ann Arbor, Michigan and Research Triangle Park, North
Carolina to expand their programs to assess non-regulated emissions from
oxidation catalyst-equipped prototype vehicles. At about the same time,
Esso Research and Engineering (now Exxon Research and Engineering)
reported similar findings to EPA.
The initial efforts of these various investigations were reported
in hearings before the Committee on Public Works of the U.S. Senate on
November 5 and 6, 1973. The Administrator testified before the Committee
(page 431, Ref. 1) on November 6, 1973. His decision regarding the use
of catalysts on 1975 model year vehicles was based upon three technical
papers prepared by EPA and formally forwarded to the Senate on January
2
11, 1974. That decision is best summarized from testimony:
22
-------
"I intend to make no change in the emission standards
that are currently promulgated to be applicable
to the 1975 model year, and to take no action that
would inhibit the use of catalysts on 1975 cars.
At the same time, however, EPA will do the following;
1.
2.
3.
4.
Accelerate our work on developing a test pro-
cedure of assured reliability for measuring
emissions of sulfates from cars;
Consider all feasible measures for controlling
sulfate emissions from cars, including a
regulatory approach tc controlling sulfur con-
tent in gasoline and other alternatives. In
the next few weeks, EPA intends to begin a
process of soliciting the views
parties. EPA will then be in a
initiate a regulatory proposal,
indicate such action is necessary to protect
public health. In addition, we intend to
encourage the petroleum industry to voluntarily
make available unleaded gasoline of low sulfur
content for the 1975 model vehicles;
our ability to estimate the impact of
of all interested
position to
if studies
Improve
sulfate
quality
Improve
and other emissions from cars on air
and public health; and
our understanding of the atmospheric
chemistry involved and institute an appropriate
air monitoring program."
The material covered by this first annual catalyst research program
report is responsive to the mandate established by Administrator Train
as outlined in items one through four of this testimony as quoted above.
Subsequent discussion will address each item.
"1. Accelerate our work on developing a test procedure of assured
reliability for measuring emissions of sulfates from cars;"
At the time EPA was preparing testimony for the Senate regarding
catalyst-generated sulfuric acid, two rather different approaches were
being used to ascertain the emission levels of sulfuric acid. One, an
23
-------
adaption of a stationary source SO?/S(L method (referred to as Method 8)
L-. «_)
was principally used by the EPA laboratory in Ann Arbor and by Chrysler
Corporation. Data obtained by this method indicated that sulfuric acid
was emitted by non-catalyst vehicles while catalyst-equipped vehicles
2
emitted substantially higher levels. The other method, used in minor
variations of design was an exhaust-air diluted particulate technique
pioneered by Habibi. This method indicated that little or no sulfuric
acid was emitted by non-catalyst vehicles but that easily measurable
quantities were emitted by oxidation catalyst-equipped vehicles. At
the time the Administrator made his decision regarding the use of
catalysts on 1975 vehicles, it was not known which method was correct.
The Office of Research and Development in the National Environmental
Research Center, Research Triangle Park, N.C., has devoted considerable
effort during the past year to examining the question of a reliable
and accurate sulfuric acid measurement method. We have concluded that the
stationary source Method 8 results in "artifact" sulfate (Appendix B3.4).
Further, the exhaust-air dilution technique provides a highly reliable,
repeatable, and accurate method for ascertaining sulfuric acid emissions
from motor vehicles (Appendix B2.2, B3.7, B3.8) (The exhaust-air dilution
method has subsequently been installed in the Ann Arbor facility.). We,
therefore, conclude that current vehicles, whether equipped with air
pumps or not, emit trace quantities of sulfuric acid.
The emission rate of sulfuric acid from oxidation catalyst-equipped
vehicles, while clearly established, is somewhat more difficult to quantify.
Sulfuric acid emissions are dependent upon at least the following variables:
vehicle cycle, catalyst type, fuel sulfur level, catalyst age, degree of
HC/CO control desired (75 National Interim Standard vs 75 California
Interim Standard), fuel economy, catalyst pre-conditioning, catalyst
operating temperature, and catalyst volumetric flow rate. Major determi-
nants are known to be fuel sulfur levels, vehicle cycle, and catalyst type.
24
-------
Increased fuel sulfur levels do result in increased sulfuric acid emission
levels. Cold start Federal Emissions test procedures result in lower
sulfuric acid emission rates than do cruise modes. The monolithic type
catalysts exhibit nrjch higher sulfuric acid emission rates during the
cold start FTP than do the beaded catalyst systems. The beaded systems,
however, exhibit very high transient sulfuric acid emissions when operated
from the FTP to a cruise mode. This phenomenon is due to the fact that
the beaded catalyst system stores large quantities of sulfur compounds
during cold operation and releases them as both S0? and sulfuric acid
when operated under the higher temperatures associated with cruise
operation. At the present time, it appears that both systems emit about
the same amount of sulfuric acid when the urban cold-start (FTP) cycle,
transient, and cruise modes are considered.
Other data suggest that catalyst age, catalyst pre-conditioning
(particularly for beaded systems), catalyst operating temperature, and
exhaust flow rate through the catalyst are also minor determinants of
sulfuric acid emission rates. As with fuel sulfur level, the fuel
economy of the specific vehicle being evaluated is an important factor
in determining the sulfuric acid emission rate.
Limited data with 1975 production vehicles indicate that those
achieving the more stringent 1975 California emissions standards also
emit higher levels of sulfuric acid. This will be better quantified in
the near future.
We have reviewed the factors which affect the generation and collection
methods for exhaust sulfuric acid. The third critical area in assessing
sulfuric acid emission rates is the analysis of the collected particulete
sample. Various investigators have used several techniques. ORD at
NERC/RTP has developed a highly accurate automated barium method (Appendix
B3.6). The method, in this laboratory, has been compared to the
25
-------
Thorin method, x-ray fluorescence, and atomic absorbtion techniques
while utilizing a variety of particulate collection media. The automated
barium method has been shown to be highly reliable, accurate, and
repeatable, particularly for samples collected on fluoropore filter
media and is superior to the other methods examined. This method is
also now being used in the Ann Arbor laboratory and in a number of
industry laboratories. In addition, a number of laboratories are
currently involved in a round-robin sulfate analysis method comparison
study which involves a multi-laboratory analysis of a large batch of
particulate from a catalyst vehicle collected at the RTP laboratories.
The results of this study should be available within a few months.
In summary, we now can conclude that non-catalyst vehicles emit
little, if any, sulfuric acid; that catalyst cars do emit sulfuric acid;
and while we now have reliable collection and analysis techniques for
mobile source generated sulfuric acid, we also are more fully aware of
they many factors which are important in determining the sulfuric
acid emission rate. At this time, we believe that the emission factor
estimate (.05 gm/mile) used in the Agency's technical papers in support
of the Administrator's Senate testimony is approximately correct.
The final aspect of our program to determine emission rates of
sulfuric acid from catalyst-equipped vehicles involves two in-use
consumer-owned, operated, and maintained vehicle studies. All current
data have been obtained in the laboratory using prototype, pre-production,
and a small number of production 1975 catalyst-equipped vehicles. It
is the intent of the two field programs to obtain data on the emissions
of regulated pollutants (CO, HC, NO ) and selected non-regulated
/\
pollutants (particulates and sulfates) from 1975 California standard
vehicles and from 1975 National standard vehicles. Emission factors
for these pollutants from a fairly large number of vehicles owned, operated,
and maintained by the consuming public and using commercial fuels
26
-------
purchased by the public will provide information pertinent not only to
the sulfuric acid emission issue but will also provide an index to the
reliability of catalyst technology for emissions control (See Appendix
B2.5 and B2.6).
"2. Consider all feasible alternatives for controlling sulfate
emissions from cars..."
A number of projects have been instituted to evaluate means of
controlling sulfate emissions from catalyst-equipped vehicles. This
area is the principal responsibility of EPA's Office of Air and Waste
Management (OAWM). An extensive cooperative effort exists between
OAWM and the ORD emissions research groups in this particular phase
of the catalyst program. Options being pursued are:
1. Gasoline de-sulfurization
2. Sulfate traps
3. Minimize sulfate emission by control system
modification
4. A mobile source sulfate emission standard
The de-sulfurization program is under the direction of the
Office of Air Quality Planning and Standards, OAWM. In November
1973, ORD, NERC/RTP initiated a three-phase study with M.W. Kellogg
to ascertain the feasibility, cost, and time required to de-sulfurize
gasoline. Appendix A2 contains details of the current status of the
de-sulfurization program including the Kellogg reports (A2.2). We can
conclude at this time the following regarding the gasoline de-sulfurization
option:
1. De-sulfurization of gasoline is technically feasible.
2. De-sulfurization of the special gasoline for catalyst-
equipped vehicles to levels of 60 to 100 pprn sulfur
(current national average is about 300 ppm) would require
an industry capital investment of about $2 to $4 billion.
27
-------
3. The added cost to the consumer would be around lit/gallon.
4. It would require 3-5 years for complete installation of
the equipment.
Some discussions have been held between EPA and the Federal Energy
Administration regarding the feasibility of allocating low-sulfur crude
or finished product to those urban areas which would be most impacted by
catalyst-generated sulfuric acid. Such discussions are in the pre-
liminary stage at this time. Aspects of voluntary petroleum industry
efforts to provide low-sulfur gasoline for catalyst-equipped vehicles
is discussed in Appendix A2.1. In general, some refineries could
operationally do so, while others could not without equipment investment.
A recent survey of sulfur levels in the unleaded gasoline grade, while
limited, shows values ranging from 25 ppm to over 900 ppm sulfur. One
might expect this range to narrow »s the demand for the unleaded grade
increases with increasing 1975 vehicle purchases.
Sulfate traps and the catalyst operating conditions study are
covered in detail in Appendix Al. The catalyst operating conditions
study is principally directed at ascertaining the critical parameters
of catalyst operation which affect sulfuric acid formation. The
objective is to define a catalyst type which when operated under select
conditions would minimize the SO^ conversion to sulfuric acid and
yet provide the HC and CO control required to achieve the mandated
emissions standards. At this time, a number of sulfuric acid determinants
have been identified, most of which have been reviewed earlier in this
discussion.
Sulfate traps, and from a regulatory point of view, a sulfate emission
standard for new motor vehicles are also being actively evaluated. The
results to date are summarized in detail in Appendix Al, as noted
earlier. While the program is in preliminary stages, the sulfate trap
approach appears to be cautiously optimistic. Implementation of such
28
-------
traps would likely hinge upon regulatory standards limiting sulfuric
acid emissions from new light-duty motor vehicles by EPA. Such standards
would require three years for implementation at a minimum.
In March 1974, EPA published, in the Federal Register, a notice
seeking information from interested parties on the catalyst sulfuric
acid issue. Many responses were received. These have been reviewed and
discussions pertinent to the various aspects of the issue were prepared
by an OAWM-ORD task force. The responses and EPA's analysis thereof
will be available in the near future from OAWM. In summary, the responses
provided little new information that would assist the Agency in evaluating
the potential public health impact of the use of oxidation catalysts on
light-duty motor vehicles beyond that being obtained from the program
being reviewed in this report.
"3. Improve our ability to estimate the impact of sulfate and other
emissions from cars on air quality and public health;"
When the emission factor of a new pollutant has been determined,
the next two critical steps in assessing impact involve estimating
exposure levels and ascertaining whether such levels pose a threat
to public health. In the case of sulfuric acid and catalyst attrition
products, a number of approaches to estimating exposure levels were noted,
but the principal technique involved application of meteorological highway
2
models. Once preliminary exposure estimates were completed, potential
adverse health effects were estimated, based, in part, upon the extensive
atmospheric sulfate background information available from the Office of
Research and Development Community Health and Environmental Surveillance
System (CHESS). Assessment of potential public health risk due to
catalyst attrition products was quite another issue, as little information
was available within EPA or the technical literature. As a result,
substantial toxicological, biological, and human studies were initiated.
29
-------
Of equal importance was the assessment of the public health benefits
associated with reduced emission levels of regulated motor vehicle
pollutants, i.e., CO, oxidants (HC), and NO .
X
Exposure estimates have relied principally upon the application of
highway CO dispersion models (Appendix B6.2). Subsequent to the EPA
2
technical paper submitted to the Senate on this subject, these models
have been further evaluated and are presented in Appendix B6.3. Contained
within B6.3 is an example of line source CO dispersion modelling which
relates to the catalyst sulfate issue. Of particular interest is the
graphical presentation relating peak hourly concentration at various
receptor distances to the 24-hour average exposure value. It is not,
however, known that a dispersion model for a stable gas (CO) is directly
applicable to the sulfuric aerosol which is emitted. Studies are
under way to assess the relevance of this particular issue.
A number of other methods have been used to estimate exposures.
These include CAMP CO monitoring data, Pb surrogates, a CO activity
model and a carboxyhemoglobin (COHb) model which is independent of an
assumed activity pattern. All such approaches to estimating sulfuric
acid exposures have resulted in incremental exposure values of roughly the
same magnitude. We, therefore, conclude that such estimates are likely
to predict actual exposures. Tables 1 and 2 summarize all currently available
exposure estimates. It is important to note however, that all such
exposure estimates have been calculated assuming 25% of the vehicle miles
travelled are with catalyst-equipped vehicles (2 model years) and that
such vehicles emit an average of 0.05 gms/mile sulfuric acid.
Further, it is apparent from Appendix B6.2, B6.3, and Reference 2,
that such exposures are localized on and near major sources of vehicular
traffic and do not include current ambient background sulfate levels.
Also, complex source models (shopping centers, parking garages, etc.) have
not been developed. Such models will be developed as part of this
program in FY 76.
]See Appendices B6.2, B6.3, and Reference 2.
30
-------
A fuller discussion of the impact of catalyst-generated localized
sulfuric acid on urban commuters in areas with currently existing worrisome
ambient sulfate levels is contained within References 4, 5, and 6.
Reference 4 also addresses the issue of the benefits associated with
regulated emissions reductions from motor vehicles utilizing dispersion
model estimates. Table 3 summarizes those findings, while Reference 7
examines such public health benefit aspects from the perspective of the
impact of removal of lead from gasoline. Assessment of the potential
public health impact of localized exposures to sulfuric acid aerosol
generated from catalyst-equipped vehicles has relied heavily upon the
ambient sulfate epidemiological studies conducted over the past 3 years
by EPA at NERC/RTP. Appendix B9.1 provides the latest update on such
studies. Such health assessments including other studies have also been
treated in some detail in References 1, 2, 5, 6, 7, 10, and 11. In
general, these studies indicate that:
1. There exist within our population people who are
particularly susceptible to particulate sulfate
exposure. These are those with pre-existing heart
and respiratory diseases. Such people comprise
approximately 10% of the U.S. population.
2. Susceptible people are believed to exhibit aggravation
of symptoms when exposed to levels of approximately
3
10 )agm/m of ambient particulate sulfates for a 24-hour
period.
3. Ambient sulfates, as measured in these studies, include
all water-soluble particulate sulfate species of
which sulfuric acid could be one.
4. Sulfuric acid may or may not be a major component of
most urban ambient sulfates.
5. Sulfuric acid is likely to be more irritating than the
current ambient sulfates at the same concentrations.
31
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12 13 14
While definitive data are lacking, limited human studies t"y"1
indicate that sulfuric acid should increase pulmonary flow resistance
in humans. Morando briefly (15 minutes) exposed young healthy human
subjects not accustomed to inhaling H9SO. to concentrations varying from
3
0.35 to 5.0 mg/m . Even at concentrations not subjectively detected by
o
the volunteers (less than 0.05 to 0.7 mg/m ) the respiratory rate increased
12
rapidly and remained elevated for several minutes after exposure. Amdur
observed a respiration rate increase of 30%, inspiration and expiration
decreases of 20% and total tidal volume increases of about 28% using human
volunteers exposed for 15 minutes to H9SO. levels between 0.35 and 0.5
3 LI
mgm/rn .
In human volunteers exposed to H~SOA mist levels greater than 0.35
3
to 0.5 mg/m , bronchiospasm, increased upper respiratory-tract secretions,
and a rapid respiration rate were consistently found, along with elevated
pulmonary air-flow resistance. All subjects were healthy young adults who
could easily compensate for the increased resistance imposed on their
breathing. Elevated airway resistance severely hampers breathing in
individuals already burdened by cardiorespiratory deficiencies, however,
making it more difficult to obtain needed oxygen.
Studies of atmospheric chemistry have shown that at least a portion
of the sulfur dioxide (SOp) emitted to the atmosphere undergoes transfor-
mation (oxidation) leading eventually to the formation of sulfuric acid
and sulfate particles. Such atmospheric reactions are believed to proceed
at a rate from 2 to 15% per hour. Epidemiological, human volunteer, and
animal studies demonstrate that some of these oxidized sulfur aerosols
and particulates have a much greater irritant potential than sulfur oxide
itself. One such aerosol product, sulfuric acid, has been specifically
shown to be substantially more irrtating than sulfur dioxide.
32
-------
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-------
TABLE 2
INCREMENTAL EXPOSURE ESTIMATES - AUTOMOTIVE-GENERATED
SULFURIC ACID AEROSOL
(25% Vehicle Miles with Oxidation Catalysts. Data Based
upon an Emission Rate of 0.05 gm/mile H2S04)
Comparisons of Various Estimates
(corrected for emission rate only)
Exposure
Model
CO Dispersion
CAMP Station
(Chicago) CO
Surrogate (not a
highway CO value)
Pb Surrogate
Activity Models
CO Model
COHb Model
Estimate
Source
EPA
EPA
EPA
EPA
EPA
EPA
GM
EPA
GM
EPA
Ford
GM
EPA
Exposure
Estimate
7 yg/m3 - pe=>'.
124 pg/m3 - peak
5 yg/m3 - peak
88 yg/m3 _ peak
14.5 ug/m3 - 24-hr
11.1 yg/m3 - 24-hr
25.4 pg/m3 - 24-hr
14.7 yg/m3 - 24-hr
6.9 yg/m3 - 24-hr
4.4 yg/m3 - 24- hr
1.1 yg/m3 - 24- hr
6.6 yg/m3 - 24- hr
5 yg/m3 - 24- hr
2 yg/m3 - 24- hr
1 .3 yg/m3 - 24-hr
.93yg/m3 - 24-hr
11.6 yg/m3 - 24-hr
5.9 yg/m3 - 24-hr
5.3 yg/m3 - 24-hr
7.0 yg/m3 - 8-hr
9.4 yg/m3 - pk-hr
5.0 yg/m3 - 24-hr
3.8 - -
5.3 pg/m - pk-hr
3.3 -
6.8 yg/m3 . pk-hr
1.7 - ,
9.2 yg/mj - pk-hr
1 yg/m3 - Av.yr.
24-hr
3 yg/m3 -2-3-hr
5 ug/m3 -2-3-hr
5 pg/m3 _ 24 -hr
8.8 pg/m3 - 24-hr
1.3 yg/m3 - 24-hr
6.7 yg/m3 - 24-hr
1.0 yg/m3 - 24- h4
0.6 -
8.8 yg/m3 - 24-hr
0.4 - -
6.7 pg/nT - 24-hr
1.6 -
8.1 pg/m3 - 24-hr
1-0 -
5.1 pg/mj - 24-hr
Meteorological
Conditions
Typical
Adverse
Typical
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Adverse
Maximum CO
Maximum CO
Maximum CO
Maximum CO
All
All
All
All
Typical
Adverse
Adverse
Adverse
Typical
Adverse
Typical
All
All
All
All
Receptor
Vehicle passenger
Vehicle passenger
10M from roadway
10M from roadway
Vehicle passenger
10M from roadway
1M from roadway
10M from roadway
50M from roadway
100M from roadway
50 OM from roadway
1M from roadway
10M from roadway
50M from roadway
100M from roadway
500M from roadway
1M - street canyon
10M - street canyon
Vehicle passenger
Pedestrian
Urban shopping center
On/Near highway
On/Near highway
On /Near highway
On/ Near highway
4 ^j
Person living near
expressway
Person living
near expressway
Person living away
from expressway
Person living aw a/
from expressway
Person living near
expressway
Person living away
from expressway
"ligh estimate (urban)
1 Low estimate (suburban)
lypical - median day
Adverse - worst 2-3 days of the year
34
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While there are those who are critical of the CHESS epidemiological
program, there is sufficient evidence at the present time to consider
suspended sulfates as potentially injurious to human health. This
requires us to undertake a concerted research effort to define more
precisely the adverse health aspects of suspended sulfates and sulfuric
acid on human health, particularly in regard to potentiation or aggravation
of difficulties already experienced by persons presently burdened by
cardiorespiratory deficiencies. It must also be pointed out that the
threshold adverse health effects levels estimated for ambient sulfates
provide m) safety factor for these susceptible groups in our population.
Reference 15 provides an excellent review of several animal studies
where exposure to HpSO. aerosol was at least one parameter. That report
suggests that laboratory animals have increasing sensitivity to H-SO,
aerosols as follows:
Rabbits - Least sensitive
Rats - |
Mi ce - I
Guinea Pigs - Most sensitive
A number of conclusions presented in Reference 15 regarding toxicity
in experimental animals are highlighted below:
1. Sulfuric acid is a respiratory irritant and can cause
death if present in sufficient concentrations.
2. Sulfuric acid causes pathological lesions in the lungs
after much less than lethal exposure.
3. Effective, short-term exposures produce a degree of lung
damage related to the arithmetic product of concentration
and time rather than the concentration alone.
4. Sulfuric acid-induced lung damage is slow to repair.
5. Sulfuric acid aerosol size is an important factor in
determining its irritant potency. In long-term studies
the effect of 0.9 y particles was greater than either
0.6 or 9.0 \i particles.
35
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6. Data on mass concentration alone provide an
insufficient basis for predicting potency.
7. The participate oxidation products of sulfur
dioxide generally have much greater irritant
potency than the parent sulfur dioxide gas.
15
This review report discussed effects in laboratory animals at
many exposure levels of FUSO. alone and in combination with other
gaseous and particulate sulfur compounds. Additional work relating to
animal exposures to sulfuric acid is contained within Appendices 84.2,
B4.3, and B4.4. Detectable lung changes have been identified within
these studies at levels
studies are continuing.
3 3
these studies at levels as low as 30 pgm/m (.03 mgm/tn ). These
Inhalation toxicological studies of exhaust untreated and
treated with an oxidation catalyst have been under way at the Environ-
mental Toxicology Research Laboratory, NERC, Cincinnati. Extensive
details of this program are contained within Appendix B5.1. This
program to date has principally addressed issues related to the
benefits associated with catalytic treatment of exhaust pollutants.
More specific studies related to sulfuric acid exposures are now
under way, utilizing the more sensitive animals (guinea pigs) and
longer exposure durations (3 months).
It was noted earlier in this discussion that our ability to
quantify adverse health effects associated with incremental sulfuric
acid exposures was reasonably well-based. Such was not the case for
catalyst attrition products: platinum and palladium. Scattered reports
in mid-1973 from laboratories testing pre-production catalysts
indicated that detectable levels of platinum and palladium were emitted
as exhaust particulates. While we were able to estimate potential
exposure levels, we were not able to assess the potential public health
risk associated with such exposure. This was due to the fact that
36
-------
extremely little had been published in the literature regarding
these materials. Organic platinum compounds have, however, been
identified as having adverse health effects on those occupationally
exposed. As a result, an occupational TLV (threshold limit value)
3
of 2 ugm/m has been established for the work environment.
The research programs undertaken to increase our knowledge of the
effects of platinum and palladium exposure cover a number of key areas:
1. Toxicology - Appendix B4 and Appendix B5
2. Inhalation Toxicology - B5
3. Human Studies - Appendix B9
These programs have presented difficult concurrent challenges. While
animal exposure studies were being undertaken it became apparent that
analytical methods were not really adequate to ascertain baseline or
even low level concentrations in tissues and biological specimens. In
addition, as noted earlier, the relevant published literature was
greatly lacking -- indeed almost non-existent -- relative to any work
outside of occupational exposures to organic platinum compounds.
This aspect of the catalyst program has made dramatic progress.
Procedures have been designed, evaluated, and implemented for the
collection and analysis of tissues and biological specimens from living
human population (Appendices B9.2, B9.3, B9.4, B9.5, B9.8). Analytical
techniques, an order of magnitude more sensitive than those previously
available, have been developed (Appendix B4.6). The uses and sources
of these metals have been documented (Appendices B9.6 and B9.7) and a
broad toxicological program initiated (Appendices B4.5, B4.7, B4.8, B4.9,
B4.10, B4.ll, and B5.1).
To date, only acute studies have been or are nearing completion.
The longer term chronic studies will not be completed until FY 77. In
summary, preliminary results suggest the following:
37
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1. Platinum, as complex salts, is a potent sensitizer
and is highly allergenic.
2. We do not know what fraction of our population may
be susceptible to platinum allergy.
3. Platinum and palladiurr. can be absorbed into biological
tissues when administered to experimental animals by
various exposure routes.
4. Soluble platinum compounds are more toxic than lead or
manganese when administered orally. Palladium is more
toxic than these metals when administered intravenously.
5. Absorbed noble metals can traverse the placenta!
barrier in pregnant experimental animals.
6. Palladium apparently acts as a non-specific cardiac
irritant as well as a peripheral vasoconstrictor in
experimental animals.
7. At the present time, there is relatively little, if any,
contamination of platinum in human tissue.
Appendix B4.1 and Reference 16 provide an excellent, detailed
overview of our current state of knowledge regarding platinum and palladium.
As was evident in Table 3, presented earlier in this discussion, we do
not now expect platinum or palladium exposures to be at levels of concern,
based upon our current knowledge, for several years. This is principally
due to the fact that all work reported by EPA's laboratories and industry
laboratories indicate that platinum and palladium emissions from current
production catalyst systems are below detectable limits. What emissions
occur during catalyst failure due to poisoning or thermal destruction are
not known, however. The potential for platinum methylation via the
Vitamin B^ route, similar to mercury methylation, is being investigated.
The status of that effort is reviewed in Appendix B4.12.
38
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"4. Improve our understanding of the atmospheric chemistry involved
and institute an appropriate air monitoring program.
Current motor vehicles emit about 1% of the total man-made ^09
(sulfur dioxide) in the United States. This SCL, as indeed the SO-
from all fossil fuel combustion sources, disperses in the atmosphere
and slowly reacts to form ambient airborne particulate sulfates. Some
of the sulfate generated is sulfuric acid. Whether all sulfates found in
the atmosphere go through the acid stage before achieving their final
form is not really known. In any event, it is currently believed that
the atmospheric conversion rate of SCL to sulfate proceeds at a rate of
2 to 4% per hour. Rates in excess of 10% per hour have been reported
17 1 R
in the Los Angeles Basin, however. Work reported by Charlson suggests
that the dominant sulfate species in the St. Louis Region is (HHA)9SOA.
19
Brosset, et al. reporting on studies conducted in Sweden concluded
that two types of acid particulate were present. One type, related
to the phase (Nf-L)3H(S04)2 was evidently generated by catalytic oxidation
of S02 absorbed in water droplets about the particle. The second type,
a NH..HSO,, phase, was very small and likely formed in the presence of N09.
20
A publication by the Norwegian Ministry of Environment concludes that
sulfuric acid acounts for 45 to 90% of the sulfate deposited with
precipitation and that long range sulfate transport accounts for a
21
majority of such sulfates. Further, a study reported by Benarie in
1972 indicated that in an urban/industrial French city sulfuric acid
accounted for 7.1% of the ambient particulate sulfur, that transformation
rates ranged from 6 to 25% per hour, and that no direct photochemical
reactions could be recognized.
It is apparent from the foregoing that our knowledge about the
atmospheric chemistry of SO^ reactions and acid sulfates is far from
complete. Several programs are under way within this particular
research program and within other ORD programs to further our
39
-------
knowledge in these areas. The RAPS program (Regional Air Pollution
Study) in St. Louis is one such effort, which is concentrating a
large number of advanced sampling stations within a defined urban area.
Its objective is to describe atmospheric reaction processes and
develop and validate models which could be applied to all parts of
the nation. The SCL transformation process is one being studied in
this program.
Within the catalyst program, three principal areas of investigation
are being pursued. These are reviewed in some detail in Appendix B7.
There areas are:
1. Smog chamber studies.
2. Sulfuric acid collection and analysis.
3. Highway studies.
The smog chamber work involves two projects. The first involves the
assessment of catalyst-generated sulfuric acid aerosols' effect on
visibility compared to non-catalyst vehicle exhaust effects. These
studies employ a huge smog chamber (20,000 ft ) into which the complete
exhaust generated from a Federal test cycle is directed. Results are
expected by February 1975 from these studies. The current status of
this study is provided in Appendix B7.1. The second study involves a
controlled smog chamber study aimed at ascertaining the extent of
S0? photo-oxidation to sulfate under roadway conditions. This project
is reviewed in a status report in Appendix B7.5.
Sulfuric acid is one of the oldest known irritants to man. Yet,
no specific measurement method exists for the determination of
sulfuric acid in ambient air. Apparently, reliable non-specific methods
1921
have been employed in Europe. ' A number are currently under
investigation and development in this program. Appendices B7.2, B7.3, and
B7.4 review the current status of these efforts. We will likely not
have a reliable measurement method for ambient sulfuric acid until FY 76.
40
-------
A contract has, however, been funded for the analysis of roadside
19
particulate uy Brosset's laboratory in Sweden to provide us with
the benefit of their experience in this area.
The highway-related studies are reviewed in Appendices B7.6,
B7.7, and B7.8 and basically involve extensive characterization of
roadside aerosols in both St. Louis and Los Angeles and an assessment
of S(L and sulfate scavenging by surfaces and materials near the
roadway in Los Angeles.
Obviously, once information begins to become available from these
studies we will be in a position to move from the laboratory to the
real-world environment and, hopefully, gain a better grasp of the
short-term reactions ajid transformations which could be expected to
occur on and near major roadways due to SCL and sulfuric acid emissions
from motor vehicles. Such comparative evaluations will not be
possible before FY 76, however.
Quite apart from the previously discussed programs aimed at
permitting estimation of exposure levels, developing SCL transformation
mechanisms, and developing area-wide pollutant models, we are conducting
two major real-world monitoring programs related specifically to the
catalyst sulfate issue.
The first is a national fuel surveillance and analysis network
(Appendix Bl). Sulfate emissions (and also lead and other trace metal
emissions) are a direct function of fuel and fuel additive composition.
While the fuels used in emissions testing are related to commercially
available fuels, it is virtually impossible to cover the range of such
fuel and additive variations in the laboratory. This surveillance
and analysis effort, therefore, provides hard data about the composition
of fuels actually purchased by the consuming public. Regional shifts
in fuel sulfur content, for example, would have an effect on sulfuric
acid emissions from catalyst-equipped vehicles. This particular
41
-------
program also supports the EPA Fuel and Fuel Additive Registration Regulations
in addition to the two EPA lead in gasoline regulations.
The second monitoring program was begun in April 1974. It involves
an extensive monitoring program along a Los Angeles County freeway (405)
near Santa Monica. This Los Angeles site was chosen for three basic
reasons:
1. Southern California gasolines typically contain much
higher sulfur levels than national gasolines, thus more
sulfate will be emitted by catalyst vehicles located in
Southern California.
2. This freeway has a high vehicle usage: approximately
170,000 per day.
3. Meteorological conditions favored this site, i.e., the
wind was predominantly perpendicular to the roadway.
This highway monitoring program is the most extensive such program
conducted. It will be in operation year-round for 3 years. The objectives
are three-fold:
1. to measure concentrations of motor vehicle-generated
pollutants at and near the highway;
2. to measure catalyst-generated sulfuric acid at and near
the highway
3. to provide input to the highway meteorological modelling
program discussed earlier
The details of this program, including a review of the first 3
months data is included in Appendix B8. Appendix B8.4 specifically
discusses the collection and analysis of airborne particulates near
the roadway at the highway monitoring site. A special sampling device
has been designed, developed, and placed on-site to permit the collection
of a size fractionated ambient particulate sample of about 1 gm/day
42
-------
(Appendix B8.4). Detailed trace elements (including Pt and Pd) and
sulfur compound analysis will be performed on these samples. In
addition, a number of prototype sampling devices are being operated
at the site aimed at the collection and analysis of sulfuric acid
aerosols. Some samples collected on-site have been sent to Brosset's
laboratory in Sweden for acid analysis.
In support of the emissions characterization work, the statistical
analysis of the data obtained for the months of June, July, and August
indicate ino vehicle contribution to sulfates near the roadway. Contri-
butions to CO, total suspended particulate, S(L, and lead are easily
measurable, however.
General Discussion
This program is a complex, interdisciplinary effort involving six
ORD laboratories, two ORD National Environmental Research Centers, and
at least two different groups within OAWM. It should be apparent from
the foregoing discussion that a high level of cooperation and interrela-
tionships exist among the researchers and various managers involved
in the program. While a large number of individual research efforts are
under way which comprise this overall program, one must realize that
most are in their early stages of development. It is, therefore,
difficult at this point to provide clear answers to the many complex
issues posed by such a difficult public health trade-off issue.
There have also been reports that catalyst-equipped vehicles emit
HpS (hydrogen sulfide), PFL (phosphine), partially oxygenated compounds,
and perhaps even COS (carbonyl sulfide) and CS? (carbon disulfide). Our
laboratories are investigating the possibility of emissions of these
products as well. It has been suggested that one might expect the oxidation
of NO/NOp to nitrates or nitric acid following much the same reasoning as
43
-------
that associated with the generation of sulfuric acid through the
22
oxidation of S0?. Our laboratories, and the one industry laboratory
from which we have obtained data have been unable to ascertain that
such products are generated across oxidation catalysts.
The catalyst issue has also stimulated our efforts to examine
more fully the broader concepts encompassed by the non-regulated
emissions from other engine types, such as, diesel and rotary. In
addition, the Office of Air and Waste Management laboratories in
Ann Arbor are sponsoring characterization programs to assess some of
these non-regulated emissions from alternate sources through both
the Emissions Control Technology Division and Alternative Automotive
Power Systems of the Mobile Source Emissions Control Program.
The program will provide a sound technical basis for evaluating
the public health issues related to both the benefits associated with
regulated emissions reductions and the potential hazards associated
with exposure to the sulfuric acid generated by control systems. It
will also provide a sound future basis for estimating the public health
impact of any mobile-source generated pollutant.
44
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References
1. Hearings before the Committee on Public Works, United States
Senate, November 5 and 6, 1973. Serial No. 93-H23, Compliance
with Title II (Auto Emission Standards) of the Clean Air Act.
2. Estimated Changes in Human Exposure to Suspended Sulfate Attribu-
table to Equipping Light-Duty Motor Vehicles with Oxidation
Catalysts, Effects of Particulate Sulfates on Human Health, and
Automotive Sulfate Emissions. Environmental Protection Agency.
January 11, 1974.
3. Habibi, K. Automotive Particulate Emissions and Their Control.
SAE Paper No. 710638. Midland, Michigan. October 1970.
4. Impact of Using Oxidation Catalysts on Light-Duty Motor Vehicles
on Human Exposures to Regulated and Nonregulated Emission
Products. Environmental Protection Agency, National Environmental
Research Center, Research Triangle Park, N.C. July 3, 1974.
5. Finklea, J. F., et al. The Role of Environmental Health Assessment
in the Control of Air Pollution. Environmental Protection Agency,
National Environmental Research Center, Research Triangle Park, N.C.
August 27, 1974.
6. Briefing NotesA Status Report on Sulfur Oxides. Environmental
Protection Agency, National Environmental Research Center, Research
Triangle Park, N.C. April 1974.
7. Moran, J. B. Lead in Gasoline: Impact of Removal on Current and
Future Automotive Emissions. APCA. June 1974.
8. Health Consequences of Sulfur Oxides: A Report from CHESS, 1970-1971
Environmental Protection Agency, National Environmental Research
Center, Research Triangle Park, N.C. May 1974.
9. Power Generation: Conservation, Health, and Fuel Supply. A Report
to the Task Force on Conservation and Fuel Supply, Technical
Advisory Committee on Conservation of Energy. National Power
Surveys, U.S. Federal Power Commission. 1973.
45
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10. Finklea J. F. Conceptual Basis for Establishing Standards.
Environmental Protection Agency, National Environmental Research
Center, Research Triangle Park, N.C. 1974.
11. Health Effects of Increasing Sulfur Oxides Emissions. Environmental
Protection Agency, National Environmental Research Center, Research
Triangle Park, N.C. August 18, 1974.
12. Amdur, M., et al. Inhalation of H?SO» Mist by Human Subjects.
A.M.A. Arch. Ind. Hyg. Occup. Med. 6^:305-313. October 1952.
13. Bushtueva, K.A. Limits to Allowable Concentrations of Atmospheric
Pollutants. Book 3, U.S. Dept. of Commerce, pp. 20-36. 1957.
14. Kim, et a!. Effect of Possible Smog Irritants on Human Subjects.
JAMA. 165_:1908-1913. December 1957.
15. Toxicology of Atmospheric Sulfur Dioxide Decay Products. Environ-
mental Protection Agency, July 1972.
16. Brubaker, P.E., et al. Noble Metals: A Toxicological Appraisal
of Potential New Environmental Contaminants. April 1974.
17. Roberts, P. T. and S. K. Friedlander. Conversion of S0? to Ambient
Particulate Sulfates in the Los Angeles Atmosphere. Presented at
EPA-NIEHS Conference "Health Consequences of Environmental Controls."
Durham, N.C. April 1974.
18. Charlson, R. J. H2S04/(NH3)2S04 Aerosol: Optical Detection in
St. Louis Region. Science. April 1974.
19. Brosset, C., et al. The Nature and Possible Origin of Acid
Particles Observed at the Swedish West Coast. Gottenburg. July
1974.
20. Acid Precipitation and Its Effects in Norway. Norwegian Ministry
of Environment. Oslo, Norway. September 1974.
21. Benearie, M., et al. The Transformation of Sulfur Dioxide into
Sulfuric Acid in Relation to the Climatology of an Urban/Industrial
Area (Rouen, France). Proc. Int. Clean Air Conference. Melbourne,
Australia. 1972.
22. Pierson, W.R., et al. Nitrate and Nitric Acid Emissions from
Catalyst-Equipped Automotive Systems. Environ. Letters.
7(3), 267-272. 1974.
46
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/I'll use rcatl Inline linn CM llie ro'fnc hr/oic coini'lctim;!
i REPORT NO 2.
EPA-600/3-75-010a ' '
.1. TIT IE ANOSUBTITLE
ANNUAL CATALYST RESEARCH PROGRAM REPORT
Summary
7. AUTHOR(S)
Criteria and Special Studies Office
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Health Effects Research Laboratory
Office of Research & Development
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
1. RECIPIhMTT- ACCESSION-NO.
5. REPORT DATE
September 1975
f>. PERFORMING ORGANIZATION CODE
fl. PEJW ORMING ORGANIZATION REPORT NO
10. PROGRAM ELEMENT NO.
1AA002
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT AND PEMIOD COVERLD
Annual Program Status 1/74-9/7
1<». SPONSORING AGENCY CODE
EPA-ORD
Ib. SUPPLEMENTARY NOTES
This is the Summary Report of a set (9 volumes plus Summary).
See EPA-600/3-75-010b throuah OlO.i. Report to Congress.
16. ABSTRACT
This report constitutes the first Annual Report of the ORD Catalyst Research
Program required by the Administrator as noted in his testimony before the
Senate Public Works Committee on November 6, 1973. It includes all research
aspects of this broad multi-disciplinary program including: emissions charac-
terization, measurement method development, monitoring, fuels analysis,
toxicology, biology, epidemiology, human studies, and unregulated emissions
control options. Principal focus is upon catalyst-generated sulfuric acid
and noble metal particulate emissions.
1 7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Catalytic converters
Sulfuric' acid
Desulfurization
Catalysts
Sulfates
Sulfur
Health
li.IDENTIFIERS/OPEN ENDED TERMS
Automotive emissions
Unregulated automotive
emissions
Health effects (public)'
C. COSATI I ILlll/dlllllp
I'I. DISTRIBUTION STATEMENT
Available to public
19. SECURITY CLASS (linn Hcporl)
21. NO. OF PAGES
Unclassified
( Has pane)
22. PRICE
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