906R89104
             March 1989
        PROCEDURES FOR
ESTIMATING AND ALLOCATING
   AREA  SOURCE EMISSIONS
         OF AIR TOXICS


           WORKING DRAFT
               Original
              Prepared by:
              Versar, Inc.  -
           6850 Versar Center
          Spingfield, VA 22151
       EPA Contract No. 68-02-4254
          Work Assignment 105


             Prepared for

             Dallas Safriet
    Noncriteria Pollutant Programs Branch
  Office of Air Quality Planning and Standards
    U.S. Environmental Protection Agency
     Research Triangle Park, NC 27711

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                             Table of Contents
                                                           Page

    Preface 	1-1
1.   INTRODUCTION 	1-4
    1.1  Background 	1-4
    1.2  General Methodology 	1-5
    1.3  Steps In  Conductinq An Emission Inventory      	I"8
    1.4  Format of This Manual  	1-9

2.   SOLVENT USAGE 	2-1
    2.1  General 	2-1
    2.2  Surface Coating 	2-7
    2.3  Dry Cleaning 	2-9
    2.4  Degreasing (Solvent Cleaning Operations) 	2-10
    2.5  Rubber and Plastics 	2-12
    2.6  Graphic Arts (Printing and Publishing) 	2-13
    2.7  Other Industrial Solvent Usage 	2-15
    2.8  Commercial/Consumer Solvent Usage 	2-16
    2.9  Example Calculations 	2-17
    2.10 Methods to Apportion Countywide Emissions
           from Solvent Usage 	2-18

3.   HEATING (INCLUDING WASTE OIL COMBUSTION)  	3-1
    3.1  General 	3-1
    3.2^ Industrial  Heating 	3-7
    3.3  Commercial  and Institutional Heating 	3-10
    3.4  Residential  Heating 	3-13
    3.5  Waste Oil Combustion	3-18
    3.6  Example Calculations 	3-24
    3.7  Methods to Apportion Countywide Emissions
           from Heating 	3-26

4.   ROAD VEHICLES 	4-1
    4.1  General 	4-1
    4.2  Factors 	4-1
    4.3  Methodology Options 	4-2
    4.4  Example Calculations	4-3
    4.5  Methods to Apportion Countywide Emissions
           from Road Vehicles 	4-13

5.   AIRCRAFT 	5-1
    5.1  General 	5-1
    5.2  Factors 	5-1
    5.3  Methodology Options 	5-1
    5.4  Example Calculation 	5-8
    5.5  Methods to Apportion Countywide Emissions
           from Aircraft 	5-10

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                            Table of Contents
                                                           Page
6.   COMFORT AND INDUSTRIAL COOLING TOWERS 	6-1
    6.1  General  	6-1
    6.2  Factors  	6-4
    6.3  Methodology Options 	6-9
    6.4  Example  Calculations 	6-13
    6.5  Methods  to Apportion Countywide Emissions
           from Cooling Towers 	6-16

7.   FOREST FIRES  AND AGRICULTURAL BURNING 	7-1
    7.1  General  	7-1
    7.2  Factors  	7-1
    7.3  Methodology Options 	7-2
    7.4  Example  Calculations 	7-9
    7.5  Methods  to Apportion Countywide Emissions
           from Forest Fires and Agricultural Burning 	7-11

8.   GASOLINE SERVICE STATIONS (GASOLINE MARKETING)  	8-1
    8.1  General	8-1
    8.2  Factors  	'.	8-3
    8.3  Methodology Options 	8-3
    8.4  Example Calculations 	8-11
    8.5  Methods  to Apportion Countywide Emissions
           from Gasoline Marketing 	8-12

9.   CHROMIUM ELECTROPLATING  	-.	9-1
    9.1  General  	9-1
    9.2  Factors  	9-2
    9.3  Methodology Options 	9-3
    9.4  Example Calculation 	9-5
    9.5  Methods to Apportion Countywide Emissions
           from Chromium Electroplating 	9-5

10. HOSPITAL AND LABORATORY  STERILIZERS 	10-1
    10.1 General  	10-1
    10.2 Factors 	10-2
    10.3 Methodology Options 	10-4
    10.4 Example Calculations 	10-5
    10.5 Methods to Apportion Countywide Emissions  	10-6
                                  11

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                            Table  of  Contents


                                                           Page
APPENDIX A    METHODS TO APPORTION COUNTYWIDE AREA
                SOURCE EMISSIONS 	A-l
    A.I  Direct Determination of Emissions
           within an Area Source Grid 	A-2
    A.2  Spatial Apportionment 	A-2
    A.3  Mobile Source Apportionment  	A-15
    A.4  Temporal Distribution of Countywide Emission
           Estimates 	A-17
    A.5  Example Calculations 	A-18

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                              List of Tables
1-1    Source Categories  Not  Covered  	1-2
1-2    Standard NEDS  Area Source Categories 	1-7
2-1    National Solvent Consumption by
         User Category 	2-3
2-2    SIC Codes Comprising Solvent Use Categories 	2-4
2-3    Employee-Based Emission Factors
         for Solvent Usage 	2-5
2-4    Per Capita Emission Factors for Solvent Usage 	2-6
2-5    Spatial and Temporal Resolution of Countywide
         Emissions Totals for Solvent Usage 	2-20

3-1    Thermal Equivalents for Various Fuels 	3-6
3-2    Densities of Selected Fuels 	3-6
3-3    Emission Factors for Industrial Area
         Source Heating  	3-8
3-4    Emission Factors for Commercial/Institutional
         Area Source Heating 	3-11
3-5    Emission Factors for Residential Area
         Source Heating  	3-14
3-6    Apportionment of Residential Wood Consumption
         Between Fireplaces (FP) and Wood Stoves  (WS)
         for the Year 1976 	3-16
3-7    Waste Oil Consumption by State  	3-19
3-8    Waste Oil Characteristics and Combustion
         Emission Factors  	3-20
3-9    Spatial and Temporal Resolution for Heating
         and Waste Oil Combustion  	3-28

4-1    Road Vehicle  Emission Factors  	4-2
4-2    Spatial and Temporal Resolution for Road Vehicles  ..4-15

5-1    Military Aircraft  	:	5-2
5-2    Civil Aircraft 	5-4
5-3    Commercial Aircraft 	5-6
5-4    Spatial and Temporal Resolution for Aircraft  	5-11

6-1    Lower-  and Upper-Bound Estimates of Annual
         Cr+5  Emissions.  Per Person by  State 	6-7
6-2    Industrial Cooling Tower Emission Factors  	6-10
6-3    SIC Codes Included  in Industry-Specific
         Emission Factors  	6-10
6-4    Industrial Cooling Tower hexavalent Chromium
         Employee-Based  Emission Factors	6-11
6-5    Temporal and  Spatial Resolution for Industrial
         and Comfort Cooling Towers  	6-18

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                              List of Tables

                                                                    Page

 1-1      Source Categories Not Covered 	  1-2


 7-1      Emission Factors Used to Estimate Emissions From
            Wildfires, Managed Burning and Agricultural  Burning ..  7-3

 7-2      Summary of Hydrocarbon Emission Factors for Forest
            Wildfires 	  7-4

 7-3      Volatile Organic Species Profile From Typical  Forest
            Wildfires 	  7-5

 7-4      Summary of Estimated Fuel Consumed by Forest Fires 	  7-7

 7-5      Spatial and Temporal Resolutions for Agricultural
            Burning 	  7-13


 8-1      Selected Air Toxic Emissions From Gasoline Stations ....  8-4

 8-2      VOC Speciation Factors for Gasoline Marketing 	  8-5

 8-3      Spatial and Temporal Resolutions for Gasoline
            Marketing 	  8-14


 9-1      Uncontrolled Emission Factors Used to Estimate
            Emissions from Chromium Electroplating Operations ....  9-4

 9-2      Spatial and Temporal Resolution for Chromium
            Electroplaters 	  9-7


10-1      Spatial and Temporal Resolution of Countywide Emission
            Totals for Hospital and Laboratory Sterilizers 	  10-8


A-l       Land Use Categories 	  A-8

A-2       Example of Grid Cell/Area Source Grid Matrix 	  A-10

A-3       Example of an Apportionment of Area Source Categories
            by Land Use Category (land use/area source matrix) ...  A-ll
                                    VI

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                              List of Figures

                                                           Page
1-1-    Area Source/Pollutant Matrix 	1-10
7-1    Forest Area and U.S. Forest Service Regions 	7-8
A-l    Land Use Map 	A-24

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                    PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                      AREA  SOURCE EMISSIONS  OF AIR  TOXICS
                  Interim Procedures For Estimating And
                   Allocating Area Source Emissions of
                                Ai r Toxics
                                 Preface
     Most of the initial draft of this report was prepared under contract
to the Environmental  Protection Agency (EPA) Pollution Characterization
Section, Non-Criteria Pollutant Programs Branch (NPPB) in response to the
recognized need to be able to estimate emissions of various toxic air
pollutants to the atmosphere from various area sources.  These area
sources are generally individually small but numerous and often scattered
throughout an air basin.  Automobiles, for example, are categorized as an
area source, as are residential woodstoves.   Small  commercial  and industrial
operations such as cooling towers may also be small localized sources of
toxic air pollutants  which collectively may  have a  major impact upon
health risk estimates.
     As a result of the contractor's effort, and other agency work,
available methodologies and emission factors were examined and incorporated
into this report.  The procedures and factors that  resulted are better in
some areas than others.  Many of the procedures can be traced to procedures
developed for the National Emissions Data System (NEDS) over 15 years
ago.  Though age does not necessarily indicate inadequacy, the staff of
the Pollutant Characterization Section has felt that there may be better
ways for estimating emissions that could be  developed or perhaps may
already be in use in  some State and local agencies.  Also, it is felt
that the source coverage may not be complete (see Table 1-1).   Consequently,
this document is being distributed as an interim or "Working Draft"
document so that State and local personnel may (1)  use it for benefit as
applicable, (2) provide comments and alternate procedures or other

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                   PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA  SOURCE EMISSIONS  OF AIR TOXICS
                               TABLE 1-1


                     Source Categories Not Covered
                        Structural Fires
                        Motor-boats
                        Cutback Asphalt
                        Cold Cleaning
                        Construction Equipment
                        Railroads
                        Industrial Equipment
                        Wastewater
                        On-Site Incineration.
                        Vessels
                        Pesticides
                        Farm Equipment
3/89

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                    PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                      AREA SOURCE EMISSIONS  OF AIR TOXICS
improvements, (3) use it to stimulate development of new procedures and

factors, and (4) use it as the initiation of a "clearinghouse" of the

agencies' methods and procedures.

     Depending upon comments and other feedback, EPA will likely revise

and upgrade this document in the future.   The unbound format of this

document is used to facilitate this concept.  Users and specialists in

the field are encouraged to provide reactions, ideas and comments directly

to EPA at the following address:

          Pollutant Characterization Section
          Non-Criteria Pollutant Programs Branch
          Office of Air Quality Planning  and Standards
          U. S.  Environmental Protection  Agency
          MD-15
          Research Triangle Park, NC 27711

     Any comments and feedback received by August 1989 will  facilitate

planning and implementation of the first  update/revision.  Holders of the

document who wish to be provided with updates to the document should

advise EPA, in writing, at the above address if they were not the original

addressee of the document.  It would also be helpful in this case to

provide the name and address of the original addressee who will need to

be dropped from  the mail  key.
3/89

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                   AREA SOURCE EMISSIONS OF AIR TOXICS
1.0  INTRODUCTION
1.1  Background
     This manual is intended to provide methodologies, techniques,
procedures, and emission factors that can be used by state and local
environmental agencies in estimating and allocating area source emissions
of toxic air pollutants in a given area.  When applied in combination
with a detailed point source inventory, this handbook can be used as  a
guide to develop the area source portion of a comprehensive air toxics
inventory.  The emissions data can then be used in combination with air
dispersion modeling and risk assessment to estimate ambient levels  of,
and exposures to air toxic^ and the accompanying environmental and  health
impacts.
     The content of this manual is based on information and data available
at the time of preparation.  In a number of cases, emission factors are
based on limited test data of varying quality or may rely on gross
assumptions that were the best possible at that time.  It is generally
assumed that emission rates are, on average, uniform throughout the
country.  Many of the activity coefficients (i.e., usage rates) that  are
used with emission factors to estimate pollutant loadings are also  generic
in nature, but are scaled to the local  level based on employment by
Standard Industrial Classification (SIC) code, population density,  etc.
     This document has been designed in a looseleaf format, permitting
periodic updates and revisions as additional or more complete data  become
available, or as improved procedures are identified.   The EPA's intent
is for this format to facilitate its being a "clearinghouse" of procedures
that exist or may be developed.
3/89
                               INTRODUCTION
                                                                      1-4

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                   PROCEDURES FOR ESTIMATING AND ALLOCATING
                     AREA SOURCE EMISSIONS OF AIR TOXICS
1.2  General Methodology
     Area source emissions are estimated by multiplying an emission factor
by some known indicator of collective activity for each source category
within the inventory area.  An indicator is any parameter associated with
the activity level  of a source, such as production, employment, or
population, that can be correlated with the air pollutant emissions from
that source.  For example, emissions of volatile organic compounds (VOC)
from dry cleaning facilities in an area correlate well  with population;
thus, it is possible to develop a per capita emission factor that can be
used to estimate emissions.  As another example,, the total amount of
gasoline handled by service stations in an area can be used to estimate
collective evaporative losses from gasoline handling.
     Estimates can be derived by (1) treating area sources as point
sources, (2) surveying (e.g., telephone or questionnaire) local activity
levels, (3) apportioning national or statewide activity totals to local
inventory areas, (4) using per capita emission factors, (5) using emissions-
per-employee factors, or (6) a combination of these.  Each method has
distinct advantages and disadvantages when used for developing area source
emissions estimates.  The merits of these alternative methods must be
evaluated on a source-category-specific basis.
     One alternate approach for estimating area source emissions is to
assume that either population data or employment data are a good indicator
of emission rates.  Assuming that emissions are greatest in high population
density areas is reasonable for many area source categories.  Employment
within an area source category, for example dry cleaners, can be used as
an indicator of activity and emissions.
 3/89           "                INTRODUCTION

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                    PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                     AREA  SOURCE EMISSIONS OF AIR TOXICS
     There are many approaches to estimating air toxics area source
emissions.  A simple approach, when practical, is to utilize output
from the (now defunct) NEDS, a computerized data base that is now being
replaced with the Aerometric Information Retrieval  System (AIRS).  This
system is focused primarily on the five criteria air pollutants (particulates,
SOX, NOX, CO and hydrocarbons).  The National  Air Data Branch (NADB),
Research Triangle Park, North Carolina, maintains the AIRS Data Base and
NEDS area source data.  These data are available as standard publications,
computer printout reports, or magnetic tape files.   The activity level
information available may be most useful to the person or agency making a
toxics area source estimate.  Also available are data for parti cul ate and
volatile organic compound emissions, fuel use, vehicle miles traveled,
solvent consumption, and gasoline marketed.  The NEDS area source categories
are shown in Table 1-2.
     Area source emission estimates are calculated for each source
category, utilizing criteria pollutant emission factors contained in the
area source emission factor f-ile.  For many categories, the same emission
factors are used for all counties; however, for some source categories,
state- or county-specific emission factors account for local variability
that affect emissions.  Locale specific emission factors are used in NEDS
calculations for highway motor vehicle categories,  fugitive dust categories
and for selected other categories in a few counties where more detailed
data area available to develop more applicable emission factors than the
national emission factors.  Provision is also  made to override computer-
calculated emissions for any county source category by hand calculated
emissions, which may allow more judgmental  applications than simple
computerized emission-factor calculations.
 3/89
                               INTRODUCTION

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                    PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                     AREA  SOURCE EMISSIONS  OF AIR TOXICS
                                TABLE 1-2
                   Standard NEDS Area Source Categories
                          (Criteria Pollutants)
Residential Fuel
Commercial and Institutional Fuel
Industrial Fuel
Gasoline Fuel
Gasoline Powered Vehicles
  Hi ghway
  Off Highway
Diesel Powered Vehicles
  Highway
  Off Highway
Railway Locomotives
Ai rcraft
Vessels
Evaporative Loss
Solid Waste Disposal
  Residential
  Commercial and Institutional
  Industrial
Fugitive Dust
Other
  Wildfires
  Managed  Burning
  Orchard  Heaters
  Structure Fires
 3/89
                                INTRODUCTION
                                                                      1-7

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                    PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                     AREA  SOURCE EMISSIONS OF AIR TOXICS
     The NEDS-based approach has the advantage of easy access.   There are,

however, alternative approaches for estimating activity levels  and emission

rates.  Sometimes these alternative approaches will  be more accurate;

activity or emissions might, for example,  be based on a site-specific

survey of sources in the area, or many differ because of local  regulation.

     Once countywide emissions of area sources are estimated,  air dispersion

modeling may be conducted to predict the contribution of area  source

emissions on ambient levels and population exposures.  It is generally

recommended that county wide area source emissions be distributed within

the study area inio rectangular area source grid cells and that spatial

seasonal and temporal variations of emissions be factored into  the

apportionment.  Modeling results can then  more accurately reflect ongoing

activities in different sections of the county.

1.3  Steps In Conducting An Emission Inventory*

     An air toxics area source emission inventory may generally be

conducted in five initial steps:

          1.  Collecting data on national, state and local area source
              activity levels (NEDS reports can be the source  of many of
              these data);

          2.  Collecting demographic, economic and other data  to be used
              to apportion activity levels and emission factor  parameters;

          3.  Apportioning the areawide (typically a State) activity
              levels of area sources to the county level  using  apportionment
              factors;

          4.  Calculating estimated area source emissions by applying
              emission factors to the apportioned area source  activity
              levels, and

          5.  Converting the source information and  emissions  to a formal
              formatted record and placing this record in a file (manual
              or automatic).

     Alternatively, however, many agencies chose to  use existing inventory

data for VOC arvd particulate and speciate  them into  their toxic components.2

3/89                            INTRODUCTION                           1-8

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                   PROCEDURES FOR ESTIMATING AND ALLOCATING
                     AREA SOURCE EMISSIONS OF AIR TOXICS
It is essential  to document data and procedures used in compiling the
inventory.  Thorough documentation  allows  the agency to identify  sources
of raw data and data-handling methods used to estimate emissions.
Documented procedures must be followed during quality assurance checks
and when the inventory is being updated with new data.
1.4  Format Of This Manual
     The remainder of this manual  consists of individual  sections organized
by source category.  Each of these sections describes the source  category
and presents procedures and emission factors to estimate toxic emissions
on an annualized basis.  Multiple techniques to predict emission  rates
are described.  Example calculations have also been provided to demonstrate
how to apply the various factors and algorithms.  Spatial apportionment
techniques can be used once countywide annual emission estimates  are
determined to distribute emissions throughout the county, concentrating
emissions in those parts  (grids) of a county where the emissions  are
likely to be greatest.  Temporal factors are provided so that emissions
can reflect seasonal, daily or hourly variations of emissions; this input
is especially useful when used in conjunction with air dispersion modeling.
Appendix A elaborates on these apportionment methodologies.
     Figure 1-1 is a matrix indicating sources and pollutants covered in
this manual.  The absence of an entry for a pollutant does not necessarily
imply that the source does not emit contaminants, but rather that no
emission  factor has been  identified.
 3/89           "•                INTRODUCTION                           1-9

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                  PROCEDURES FOR ESTIMATING AND ALLOCATING

                    AREA  SOURCE  EMISSIONS OF  AIR TOXICS
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6/88
INTRODUCTION
1-10

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                               REFERENCES
1.  Air Emissions Species Manual, Volume I:  Volatile Organic Compound
    (VOC) Species Profiles And Volume II:  Particulate Matter (PM) Species
    Manual.  EPA-450/2-88-003a and b, U. S. Environmental Protection
    Agency, Research Triangle Park, NC, April 1988.

2.  Procedures For Emission Inventory Preparation, Volume III:  Area
    Sources.EPA-450/4-81-OZ6c, Office of Air Quality Planning and
    Standards, Research Triangle Park, NC, September 1981.
3/89           '                INTRODUCTION                          1-H

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                  PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
2.     SOLVENT USAGE

2.1    General

    For purposes of toxic inventories, solvents are defined as any liquid
organic compounds (or group of compounds) that are used to dissolve other
materials.  These compounds can be used as cleaning agents or in the
application of a product.  Some or all of the solvent typically
evaporates into the atmosphere, resulting in potentially significant
emissions of a variety of chlorinated and unchlorinated organic toxic air
pollutants.      i

    Solvents are used in numerous industrial, commercial, and domestic
applications, thus complicating the development of a solvent emission
inventory.  As with other area source categories,  major sources should.be
treated as point sources, using methods described in AP-42  and
Procedures for the Preparation of Emission Inventories for Volatile
                            2
Organic Compounds, Volume 1.   However, because of the large number of
small solvent users, it is necessary to develop countywide area source
estimates.

    Organic solvent usage can be divided into seven major subcategories:

    •  Surface coating;
    •  Dry cleaning;
    ,  Degreasing;
    •  Graphic arts (printing and publishing);
    •  Rubber and plastics;
    •  Other industrial; and
    •  Commercial/consumer (nonindustrial);

    Walden  allocated consumption of specific organic solvents by
county according to national solvent consumption of 17 photochemically
3/89         .                 SOLVENT USAGE                      2-1

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
reactive solvents.   That technique estimated consumption by major user
category based on county population or user category employment data.
GCA  updated Walden's estimates to reflect 1985 consumption patterns.
For this manual, the list of solvents has been further expanded to
include data for two nonreactive organic compounds, 111-trichloroethane
and methylene chloride; this revised table is presented in Table 2-1.

    By assuming that all solvent consumed in the study area is emitted
somewhere within the study area (at the user site; during transport; at a
treatment, storage, and disposal facility; or at a sewage or wastewater
treatment plant), 7they can then estimate total emissions from solvent
consumption, by category, can be estimated.

    Based on this conservative assumption, two sets of emission
factors--population-based and employment-based--have been derived.  These
factors should be used only when area-specific data, usually based on
surveys, are not available.  The former set, of these factors assumes
that area source solvent emissions within a study area (e.g., county,
city, state) are directly proportional to the population living within
the study area, as reported in the 1980 U.S. Census.  The latter set of
emission factors, generally believed to be more accurate for industrial
user categories, assumes that emissions are directly proportional to
employment in Standard  Industrial  Classification (SIC) codes (as reported
                           Q
in County Business Patterns ) of likely solvent users such as dry
cleaners or degreasers.  (For commercial/consumer solvent use, population
serves as an indicator of consumption.)  Table 2-2 shows which industrial
categories comprise each solvent user category.  Table 2-3 presents
employee-based factors, while Table 2-4 contains per capita factors.

    In the discussion below, each user category is described along with
methodologies for estimating emissions.  Example calculations are
provided in Section 2.8.
6/88          :               SOLVENT USAGE                          2-2

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING

                     AREA SOURCE EMISSIONS  OF  AIR  TOXICS
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6/88
           SOLVENT USAGE
                                                     2-3

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                      PROCEDURES  FOR  ESTIMATING AND  ALLOCATING
                         AREA  SOURCE EMISSIONS  OF  AIR  TOXICS
                    Table 2-2 SIC Codes Comprising Solvent Use  Categories
       Solvent Use Categories
                   SIC Codes
       Surface Coatings

       Trade Paints-Auto  Refinishing
       Auto Refinishing  (Trade)
       Automotive
       Wood Furniture and Fixtures
       Metal Furniture and Fixtures
       Metal Containers
       Sheet Strip and Coil
       Appllances
       Machinery and Equipment
       Paper
       Factory-finished  Wood

       Transportation (Non-Auto)
        Electric Insulation

        Other, Exterior,  Interior
        Marine

        Decreasing
        Dry Cleaning
        Rubber and Plastics

        Other Industrial
       7535  (Paint Shops)
       371  (Motor Vehicles)
       25 (Furniture and Fixtures)

       34 (Fabricated Metal Products)

       35 and  36 (Machinery, Electrical)
       Equipment and Supplies
       26 (Paper and Allied Products)
       243,  244  (Millwork, Plywood-
       Related Supplies, Wooden Containers)
       37 (Transportation Equipment)
       Less  371  (Motor Vehicles) and
       373  (Shipbuilding Repair)
       36 (Electrical Equipment and
       Supplies
       19-39 (Total Manufacturing)
       373  (Shipbuilding and Repair)

       34-39 (Metal Products, Machinery,
       Transportation Equipment,
       Instruments, Miscellaneous)

       2 x  7216, Plus 7215 and 7218 (Dry
       Cleaning  and Combination with  Wet
       Laundering

       264,  265, and 27  (Paper Products,
       Containers, Printing and Publishing
       30 (Rubber  and Plastics)

       1/2 of 19-39  Employment -i
       County Employment
1/2
6/88
SOLVENT  USAGE
                    2-4

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                PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                  AREA SOURCE EMISSIONS OF AIR TOXICS









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SOLVENT USAGE
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                     PROCEDURES FOR  ESTIMATING AND  ALLOCATING
                        AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
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6/88
            SOLVENT USAGE
                                      2-6

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
2.2      Surface Coating

    The surface coating solvent use subcategory involves the application
of paint, varnish, lacquer, or paint primer for decorative or protective
purposes.  This is accomplished by brushing, rolling, spraying, flow
coating, and dipping operations.

    Solvents are emitted as the coating material dries.  Compounds
released include aliphatic and aromatiac hydrocarbons, alcohols, ketones,
esters, alky! and aryl hydrocarbon solvents, and minteral spirits..  The
trend toward water-based coatings is reducing the magnitude of solvent
emissions.

    Surface coatings can be divided into the following categories:

    Architectural surface coatings,  often called "trade paints," are used
primarily by homeowners and painting contractors to coat the interior or
exterior of houses and buildings and of other structures such as
pavements,  curbs, or signs.  Painting contractors and homeowners are the
major users of architectural  coatings.

    Solvents used for thinning architectural surface coatings and for
clean up after application also contribute significantly to volatile
organic compound (VOC) emissions associated with the architectural
coating process.

    Automobile refinishing encompasses  the repainting of worn or damaged
automobiles, light trucks, and other vehicles.   Surface coating during
manufacture is not considered refinishing.  In  automobile refinishing,
lacquers and enamels are usually spray-applied  in paint booths.  Since
vehicles contain heat-sensitive plastics and rubber, solvent-borne
6/88         ".                SOLVENT USAGE                          2-7

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
coatings that can dry in low-temperature ovens are used.  Paint booths
may be equipped with paint arresters or water curtains to handle
overspray.

    Industrial surface coating includes the coating, during manufacture,
of magnet wire, automobiles, cans, metal coils, paper, fabric, metal and
wood furniture, and miscellaneous products.  Materials applied in coating
include adhesives, lacquers, varnishes, paints, and other solvent-borne
coating material.  Many surface coating facilities generate sufficient
emissions to be considered major sources, and should be included in the
point source inventory.  However, small sources probably will still be
present in any developed inventory area.

    There are two generic methods of estimating emissions from the
application of surface coating:

    Method 1.  Calculate emissions based on employment data in County
                 n
Business Patterns  for industrial categories listed in Table 2-2 that
conduct surface coating.  Apply emission factors provided in Table 2-3.
Be certain to subtract emissions accounted for in point source
inventories (or subtract point source employment prior to calculating
area source emissions).

    Method 2.  Apply per capita emission factors contained in Table 2-4
(a less accurate method requiring fewer resources).  Here, too, it is
necessary to subtract any emissions included in the point source
inventories.  Countywide population data can be collected from the U.S.
Census Bureau.
6/88          -.                SOLVENT USAGE                           2'8

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
2.3      Dry Cleaning

    Dry cleaning operations vary in size, type of service, and type of
solvent used.  Industrial, commercial, and self-service facilities clean
not only personal  clothing, but also uniforms, linens, drapes, and other
fabric materials.   Three basic solvent types are used in dry cleaning:
petroleum (Stoddard), tetrachloroethylene or perchloroethylene ("perc"),
and trichlorotrifluoroethane (Freonฎ 113).  Perchloroethylene is used
in approximately 80 to 90 percent of all  dry cleaning establishments and
constitutes about  70 percent of all cleaning solvent consumed.  Almost
all other establishments use petroleum solvent.  The use of fluorocarbons
as a dry cleaning  solvent is decreasing in popularity and is not
considered in this report.
    VOC emissions from dry cleaning vary with the type of process and
   ^ent used.   Detailed process descr
and controls can be obtained in AP-42
solvent used.   Detailed process descriptions and information on emissions
                                    ,1
    Virtually all  commercial  and self-service dry cleaning facilities are
area sources, while industrial  dry cleaning facilities may be either
point or area sources.   There are several  methods of estimating dry
cleaning emissions; three widely applicable methods are given below.

    Method 1.  Calculate emissions based on employment data provided in
County Business Patterns9 for SICs 7215, 7216, and 7218.  Apply
emission factors provided in  Table 2-3.   Be certain to subtract emissions
accounted for in point  source inventories  (or subtract point source
employment) prior to calculating area source emissions.

    Method 2.  Multiply per capita emission factors contained in Table
2-4 by county population data (from the  U.S. Census Bureau).  (This is a
less accurate method requiring  fewer resources).   Again it is necessary
to subtract any emissions included in the  point source inventories.
6/88         \                SOLVENT USAGE                          2-9

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Method 3.  Send survey forms to a representative sample of dry
cleaners taken from the Yellow Pages or a similar telephone directory.
The data to be collected are number of employees, quantity of clothes
cleaned (ton/year), type and amount of solvent used (solvent purchased
minus solvent returned for recycle), and normal operating schedule.
Assume that all of the solvent used is emitted, and check the survey
values with emissions calculated as the product of the AP-42  emission
factors and the quantity of clothes cleaned.  Emissions by solvent type
can then be estimated based on the survey results assumed that
alternatively, it can be 70 percent of all emissions are
perch!oroethylene, with the remainder being Stoddard Solvent (petroleum
distillates or special naphthas).

2.4      Deqreasinq (Solvent Cleaning Operations)

    There are basically three types of degreasers:  small cold cleaners,
open top vapor degreasers, and conveyorized degreasers.  According to
recent estimates, there are about 1,300,000 small cold cleaning units
operating in the U.S.  Seventy percent of these units are devoted to
maintenance of servicing operations, including service stations, auto
dealerships, and miscellaneous repair stations; the remaining 30 percent
are devoted to manufacturing operations.  A typical cold cleaning unit
emits approximately one-third metric ton of VOC per year.  In contrast,
typical open-top vapor degreasers and conveyorized degreasing units emit
10 and 27 metric tons of VOC per year, respectively.  These larger units
are commonly used  in the metalworking industry.  The design and operation
of each of these types of degreasers will vary, as will emissions and the
                               2
types of control measures used.   A broad spectrum of organic liquids,
including petroleum distillates  (special naphthas), chlorinated
hydrocarbons, ketones, and alcohols is used in solvent cleaning
operations.
6/88          -.               SOLVENT USAGE                          2-10

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    The development of degreasing emission estimates is complicated by a
number of factors.  First, some degreasers are large enough to be
considered point sources, yet a large fraction of all degreasers will
fall  below the point source cutoff and should be accounted for as area
sources.  Second, degreasing operations are not associated with any
particular industrial  activity.  Instead, degreasing of some sort may be
carried out in a wide variety of industries including (1) metal working
facilities (e.g., automotive, electronics, appliances,  furniture,
jewelry, plumbing, aircraft, refrigeration, business machinery,
fasteners), (2) nonmetalworking facilities (printing, chemicals,
plastics, rubber, textiles, glass, paper, electric power), (3)
maintenance cleaning operations (electric motors, forklift trucks,
printing presses), and (4) repair shops (automobile, railroad, bus,
aircraft, truck, electric tool).  Third,  the fact that  some of the VOC
emissions associated with degreasing occur at the solvent waste disposal
site complicates the location of emissions within the inventory area.

    Open top vapor (OTV) cleaners and conveyorized cleaners are larger
operations that should be included in the point source  inventory whenever
possible.  These types of equipment tend  to be associated with industrial
plants that are already included in the point source inventory.  Cold
cleaners are smaller and usually are treated as area sources in an
inventory.  For all degreasers not included in the point source
inventory, one of the following methods should be used  to estimate
emissions for the category.

    Method 1.  Calculate emissions based  on employment  data provided in
                        q
County Business Patterns  for SICs 34 through 39.  Apply emission
factors provided in Table 2-3.  Be certain to subtract  emissions
accounted for in point source inventories (or subtract  point source
employment prior to calculating area source emissions).
6/88          -                SOLVENT USAGE                          2-11

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Method 2.  A less accurate method requiring fewer resources is to
multiply per capita emission factors contained in Table 2-4 by U.S.
Census Bureau population data.  Here, too, it is necessary to subtract
any emissions included in the point source inventories.

2.5      Rubber and Plastics

    The rubber and plastics solvent user category (SIC 30 industries)
includes tire and inner tube manufacturing and the fabrication of other
rubber and plastic products such as footwear and hoses.  Solvents are
used by these industrial categories for cleaning, molding, sealing, and
gluing.  Special naphthas are the solvents used in greatest volumes;
lesser amounts of propylene glycol, ethyl acetate, and p-dichlorobenzene
are used.

    Using emission factors provided on a per capita or per employee
basis, estimate emissions are explained below.

    Method 1.  Calculate emissions based on employment data provided in
                        q
County Business Patterns  for SIC 30.  Apply emission" factors provided
in Table 2-3.  Be certain to subtract emissions accounted for in point
source inventories (or subtract point source employment prior to
calculating  area source emissions).

    Method 2.  Multiply U.S. Census Bureau data for the county by per
capita emission factors contained in Table 2-4 (a less accurate method
requiring fewer resources).  Again it is necessary to subtract any
emissions included in the point source inventories.
6/88          -                SOLVENT USAGE                          2-12

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
2.6      Graphic Arts (Printing and Publishing)

    Printing of newspapers, books,  magazines, fabrics, wall coverings,
and other materials is considered to be a graphic art application.
Inventorying the graphic arts (printing and publishing) industry is
complicated by the fact that the industry consists of approximately
                  q
50,000 facilities.   About half of these establishments are in-house
printing services in nonprinting industries, further complicating
estimating techniques.

    While printing inks vary in composition, they consist of three major
components:  (1) organic or inorganic pigments that produce the desired
color, (2) the binder or solid components (organic resins, polymers,
oils, or rosins) that lock the pigments to the receiving material or
"substrate," and (3) solvents that  dissolve or disperse the pigments and
binders and are usually composed of organic compounds.  The solvent
evaporates, typically as heated air is passed across the wet surface, and
is exhausted to the atmosphere.

    Solvent emissions vary depending on the type of printing process and
the ink used.  Printing techniques  used include:

    Wet offset lithography, the process used to produce the majority of
books and pamphlets and an increasing number of newspapers, typically
uses inks containing between 5 (newspaper) and 40 percent solvent.
Solvents are usually petroleum derived (naphthas).  Isopropanol can be
                                  2
used to dampen the printing plate.

    Letterpress is the oldest form of movable type printing.  Letterpress
newspaper and sheet-fed printing use oxidative drying inks, which are not
a source of solvent emissions.  Publication letter printing, on the other
hand, uses solvent-borne inks that  are usually 40 percent petroleum-based
                                                2
solvents; the solvents are driven off with heat.
6/88         -.                SOLVENT USAGE                          2-13

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                 PROCEDURES TOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Rotogravure systems are used in publications and advertising, such as
newspaper supplements; mail order catalogues; folding cartons and other
flexible packing materials; and specialty products such as wall and floor
coverings,  decorated household paper products, and vinyl upholstering.
The inks typically contain 55 to 95 volume percent low-boiling-point
solvents, such as alcohols, aliphatic naphthas, aromatic hydrocarbons,
                                                   2
esters, glycol ethers, ketones, and nitroparaffins.

    Flexoqraphy is used in flexible packing and laminates such as
multiwall bags, milk cartons, gift wrap, folding cartons, corrugated
cardboard,  paper cups and plates, labels, tapes, and envelopes.  It uses
water-based or organic-based solvents depending on the specific product.
Among the solvents used are alcohols or alcohols mixed with aliphatic
hydrocarbons or esters, glycols, ketones, and ethers.

    Screen printing is used to print patterns or designs on fabrics.
Organic solvents (predominately mineral spirits) or water-based solvents
are used in the print pastes that are applied in the roller, flat screen,
and rotary screen printers.

    Currently graphic arts emissions can be estimated by using one of
three methods:

    Method 1.  Multiply U.S. Census Bureau data for the county by per
capita emission factors contained in Table 2-4.  It is necessary to
subtract any emissions included in the point source inventories.

    Method 2.  Calculate 'emissions based on employment data provided  in
County Business Patterns9 for SICs 264 (Paper Products), 265
(Containers), and 27  (Printing and Publishing).  Apply emission factors
provided in Table 2-3.  Note that an emissions-per-employee approach may
not be as reliable as a per capita approach in the graphic arts solvent
6/88          '-                SOLVENT USAGE                          2-14

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
user category because of the uncertainty as to which facilities and
industries have captive graphic art capabilities.  It is important to
subtract emissions accounted for in point source inventories (or subtract
point source employment prior to calculating area source emissions.)

    Method 3.  OAQPS has prepared a new air toxics speciation
manual   that contains speciation factors for various printing and
publishing processes.  If data are available on VOC emission rates from
printing and publishing processes in the study area, the speciation
factors can be applied to estimate emissions of individual compounds.

2.7      Other Industrial Solvent Usage

    This category covers solvent releases from a variety of manufacturing
process and industries including:

       •  Synthetic organic chemical manufacturing (SOCM);
       •  Paint formulating;
       •  Ink formulating;
       •  Textiles;
       •  Iron and steel manufacturing (cold rolling mills);
       •  Pharmaceuticals; and
       •  Pesticides, herbicides, etc.;

All of these industries used and release solvents to the air.
Nationally, a variety of solvents are used in large quantities.  (See
Table 2-2).

    The diversified nature of the industries in this category,  and the
multiple uses of many of the solvents make it impractical to survey
facilities to estimate emissions.  However, emissions can be estimated on
a per capita basis or based on employment in user subcategories.  Two
methods for estimating emissions are described below.
6/88          -                SOLVENT USAGE                          2-15

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Method 1.   Calculate emissions based on employment data for

industries conducting surface coating according to County Business
        Q
Patterns  listed in Table 2-3.  Apply emission factors provided in

Table 2-3.  Be certain to subtract emissions accounted for in point

source inventories (or subtract point source employment prior to

calculating area source emissions).


    Method 2.   Multiply U.S. Census Bureau population data for the county

by per capita emission factors contained in Table 2.4.  Here, too, it is

necessary to subtract any emissions included in the point source

inventories.
2.8    Commercial/Consumer Solvent Usage


    Commercial/consumer uses of products containing solvents are not

easily quantified using questionnaires, surveys, or other inventory

methods that can make emission estimates locale-specific.  Among the

commercial/consumer products that often contain solvents are aerosol

products such as (1) insect sprays, (2) paints and finishes,

(3) household products, (4) personal products, (5)- animal products,
(6) automotive and industrial products, (7) food products, and
(8) miscellaneous products, as well as nonaerosol products such as
(1) personal products, (2) household products, and (3) garage

products.    Certain subcategories

commercial/consumer VOC emissions:
products.    Certain subcategories account for the vast majority of
       Paints, primers, and varnishes,
       Hair sprays,
       All-purpose cleaners,
       Insect sprays,
       Car polishes and waxes,
       Room deodorants and disinfectants,
       Adhesives,
       Caulking and sealing compounds,
       Moth control products,
6/88          -.               SOLVENT USAGE                           2-16

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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    •  Window and glass cleaners,  and
    •  Herbicides and fungicides.
    These sources account for 75 percent of commercial/consumer VOC
emissions,  as reported in ongoing  work by EPA.

    Commercial/consumer solvent usage can be estimated using per capita
emission factors contained in Table 2-3 or 2-4.   Emission factors are
multiplied by county population as listed in the U.S.  Census.

2.9    Example Calculations

    Examples are provided below to demonstrate  the application of per
capita and employee-based factors.

Example Calculation 1

    Estimate the annual area source emissions from degreasing  in Delaware
County, Pennsylvania.

    SIC codes 34-39 are identified in Table 2-1  as conducting
                                                       9
degreasing.   Based on data in County Business Patterns,   the employment
in Delaware County in SICs 34-39 is 12,704.  Applying  emission factors
from Table 2-3, emissions can be estimated.

    Special  naphthas = (12,704) x  (58 lb/yr/employee)  =  736,832 Ib/yr
    Perch!oroethylene - (12,704) x (6.3 Ib/yr/employee)  = 80,034 lb/yr
    Trichloroethylene = (12,704) x (16 Ib/yr/employee)  = 203,264 lb/yr
    Monochlorobenzene = (12,704) x (58 Ib/yr/employee)  - 736,832 lb/yr
    1,1,1-Trichloroethylene = (12,704) x 44 lb/yr/employee)  =  558,976 lb/yr
    Methylene chloride = (12,704)  x 7.6 Ib/yr/employee)  = 96,550 lb/yr
6/88          -                SOLVENT USAGE                          2-17

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
Example Calculation 2

    What are the total  annual  trichloroethylene emissions from solvent
usage in DeKalb County,  Georgia?

    The 1980 U.S.  Census reports the population of DeKalb County to be
466,600.

    Applying emission factors  in Table 2-4, countywide emissions can be
calculated.
    Surface Coating     (466,600) x 8.8 x 10"6 Ib/capita =       4 Ib/yr
    Degreasing          (466,600) x 6.0 x 10"1 Ib/capita = 270,960 Ib/yr
    Other Industrial    (466,600) x 2.4 x 10"2 Ib/capita =  11,198 Ib/yr
    Commercial/Consumer (466,600) x 7.9 x 10   Ib/capita =   3.686 Ib/yr

                                      TOTAL               = 294,848 Ib/yr

2.10   Methods to Apportion Countvwide Emissions from Solvent Usage

    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
emissions.  Similarly temporal in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect on-going activities in that portion
of the county, e.g., residential heating in the winter, commercial
solvent usage during working hours on weekdays.

    There are three alternative approaches that can be used in spatially
distributing emissions:  (1) population, i.e., the magnitude of emissions
6/88          :                SOLVENT USAGE                          2-18

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                  PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE  EMISSIONS  OF AIR TOXICS
within a grid are directly proportional to the population  living  in  the
grid,  (2) land area,  i.e., emissions from a countywide distributed based
on the size of the area source cjrid, and (3) landuse patterns, that
assume that certain area  source activities, most likely occur  in  certain
areas of the county,  e.g., commercial, residential or industrial.

     In apportioning emissions from solvent usage any of these  methods may
be appropriate.  Land area and population data can be readily  obtained,
and  applied as described  in Appendix A.  Land use data, available from
the  U.S. Geological survey and other sources can be used  in combination
with the spatial resolution for each category of solvent  usage, to
•distribute emissions  based on the type of activity being  performed,  as
shown  in Table 2-5.

     Estimated seasonal, daily, and hourly temporal resolution  for each
category of solvent usage are also included in Table 2-5,  and  can be used
with annual countywide emissions data to estimate temporal variations.
6/88          \               SOLVENT USAGE                          2-19

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                    PROCEDURES  FOR  ESTIMATING AND  ALLOCATING
                       AREA  SOURCE EMISSIONS OF AIR  TOXICS
                  Table 2-5  Spatial and Temporal  Resolution of County  Wide
                            Emissions Totals  for Solvent Usage
         1.     Industrial Surface Coating  (Solvent)
               Spatial Resolution
                    Surrogate indicator:

               Information source(s):
     commercial/industrial  areas  (Codes
     12,  13, and 15)
     land use map
               Temporal Resolution
                    Seasonal:
                    Daily:
                    Hourly:
     uniform through the year
     uniform through the week
     80  percent from 0700 to 1900, 20
     percent from 1900 to 2400, otherwise
     zero
               Nomndustnal Surface Coating
                                           13
               Spatial Resolution
                     Surrogate indicator:

                     Information source(s):
     urban or builtup land (codes  11
     through 17)
     land use map
               Temporal Resolution
                     Seasonal:
                     Daily:
                     Hourly:

               Dry Cleaning13

               Spatial Resolution
                     Surrogate indicator:
                     Information source(s):
               Temporal Resolution
                     Seasona 1 :
                     Daily:
                     Hourly:
     uniform through the year
     uniform through the week
     uniform 0700 to 1900,  otherwise zero
     commercial areas (codes  12  and  15)
     Retail service employment,  land use
     map
     uniform through the year
     uniform Monday through Saturday
     uniform 0700 to 1900,  otherwise zero
6/88
SOLVENT  USAGE
2-20

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                      PROCEDURES FOR  ESTIMATING AND  ALLOCATING
                         AREA  SOURCE  EMISSIONS OF AIR  TOXICS
                                    Table 2-5 (continued)
                Degreasing
                          13
Spatial  Resolution
      Surrogate  indicator:
      Information source(s)'

Temporal Resolution
      Seasona 1:
      Daily:
      Hourly:
                Rubber and  Plastics  (Solvent)

                Spatial Resolution
                      Surrogate  indicator:

                      Information source(s)
                Temporal Resolution
                      Seasona 1:
                      Daily:
                      Hourly:
                                              industrial area (codes 13 and 15)
                                              land  use map and Reference 14
                                              uniform  through the year
                                              uniform  Monday through Saturday
                                              80 percent from 0700 to 1900,  20
                                              percent  from 1900 to 2400
                              commercial/institutional areas
                              (codes  12,  13, and 15)
                              land use map

                              uniform through the year
                              uniform through the week
                              80 percent  from 0700 to 1900,
                              20 percent  from 1900 to 2400,
                              otherwise zero
          6.    Graphic Arts  (Solvent)

                Spatial Resolution
                      Surrogate  indicator:
                      Information source:

                Temporal Resolution
                      Seasona 1:
                      Daily.

                      Hourly:
                              commercial areas (code 12)
                              land  use map
                              uniform  through the year
                              80 percent Monday through Saturday,
                              20 percent Sunday
                              uniform  through the day
          7.    Other Industrial  (Solvent)

                Spatial  Resolution
                      Surrogate  indicator:
                      Information source:

                Temporal Resolution
                      Seasonal:
                      Daily:
                      Hourly:
                              commercial areas (code 12).
                              land  use map
                              uniform through the year
                              uniform through the week
                              80 percent from 0700 to 1900,  20
                              percent from 1900 to 2400,  otherwise
                              zero.
6/88
                        SOLVENT  USAGE
2-21

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                     PROCEDURES  FOR ESTIMATING AND ALLOCATING
                        AREA SOURCE  EMISSIONS OF  AIR TOXICS
                                  Table 2-5 (continued)

               Commercial/Consumer Solvent Use

               Spatial Resolution
                    Surrogate  indicator:     residential,
                                           commercial/institutional  areas
                                           (codes 12, 13, and 15)
                    Information source(s):   land  use map

               Temporal Resolution
                    Seasonal:               uniform through the year
                    Daily:                  uniform through the week
                    Hourly                 80 percent from 0700 to 1900, 20
                                           percent from  1900 to 2400
6/88            '-                   SOLVENT USAGE                                 2-22

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1.
2.
3.
4.
5.
                  PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                 REFERENCES
U.S. Environmental Protection Agency.  Compilation of Air Pollutant
Emission Factors Volume I:  Stationary Point and Area Sources
(AP-42).  EPA-460/3-81-005.  Office of Air Quality Planning and
Standard.  Research Triangle Park, NC.  September 1985.

U.S. Environmental Protection Agency.  Procedures for the Preparation
of Emission Inventories of Volatile Organic Compounds.  Volume 1.
EPA-450/2-27-028.  Office of Air Quality Planning and Standards.
Research Triangle Park, NC.  September 1980.

Walden Research Division of Abcor.  Methodologies for Countvwide
Estimation of Coal, Gas, and Organic Solvent Consumption.  U.S.
Environmental  Protection Agency, Office of Air Quality Planning and
Standards.  Research Triangle Park, NC.  December 1975.

GCA Technology Division, Inc.  Area Source Documentation for the
1985, National Acid Precipitation Assessment Program Inventory (Draft
Report).  U.S. Environmental Protection Agency, Air and Engineering
Research Laboratory.  Research Triangle Park, NC.  September 1986.
Mannsville Chemical Products Corporation.
Synopsis.  Cortland, NY.
Chemical Products
6.  Schnell  Publishing Company.  Chemical Profiles.  Chemical Marketing
    Reporter (Weekly).  New York, NY.

7.  U.S.  Department of Energy.  Petroleum Marketing Monthly.  Energy
    Information Administration (Monthly).  Washington, DC.

8.  U.S.  International Trade Commission.  Synthetic Organic Chemicals,
    Washington, DC.

9.  U.S.  Department of Commerce.   County Business Patterns.  Bureau of
    the Census.  Washington, DC.   1982.

10. U.S.  Environmental Protection Agency.  Emission Inventory Workshop,
    Volume II.   EPA 450/3-78-042b.  Research Triangle Park, NC.  1978.

11• Compilation and Speciation  of National Emission Factors for Commercial/
    Consumer Solvent Use.   EPA-450/2-89-008, U. S. Environmental  Protection
    Agency,  Research Triangle  Park, NC, March 1989.
6/88
                          SOLVENT USAGE
                      2-23

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                   PROCEDURES FOR ESTIMATING AND ALLOCATING
                     AREA SOURCE EMISSIONS OF AIR TOXICS
12.   Air Emissions Species Manual,  Volume I:   Volatile Organic Compound
     (VOC)  Species Profiles And Volume II:   Particulate Matter (PM)
     Species ManuanEPA-450/2-88-003a and b, U.  S.  Environmental
     Protection Agency,  Research Triangle Park, NC,  April  1988.

13.   Procedures for the  Preparation of Emission Inventories of Volatile
     Organic Compounds,  Volume II:   Emission  Inventory Requirements  for
     Photochemical Air Quality Simulation Models.   EPA-450/4-79-018,
     Office of Air Quality Planning and Standards, Research Triangle
     Park,  NC, September 1979.

14.   Residential and Commercial Area Source Emission  Inventory Methodology
     for the Regional  Air Pollution Study.EPA-450/3-75-008,  EPA Contract
     No. 68-02-1003,  Environmental  Science and Engineering, Inc.,
     Gainesville, FL,  March 1973.
     3/89
                                 SOLVENT USAGE                        2'24

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
3.     HEATING (INCLUDING WASTE OIL COMBUSTION)

3.1    General

    The combustion of fossil fuels and wood to generate heat produces
emissions of a variety of air toxics including volatile organic
compounds, metals, and polycyclic organic matter (POM).  Emissions from
larger sources such as electric utilities and major industrial and
commercial/institutional boilers are typically included in a point source
inventory.  Area source emissions from heating occur from fuel combustion
in small  stationary sources.  Emissions from smaller sources can be
organized into three major area source categories:   (1) industrial
(small),  (2) commercial/institutional, and (3) residential.

    Emissions vary based on the fuel type, burner type, operating
parameters,  and pollution controls.  It is assumed, unless otherwise
noted, that  all area source heating is uncontrolled or at best has
minimal (i.e., mechanical) pollution control  equipment.  Major fuels used
for area source heating include coal, virgin oil  (distillate and resi-
dual), natural gas, wood, and waste oil, which are discussed below.

    Coal.  Area sources burning coal usually use bituminous and lignite
coal.  (Anthracite, bituminous, and lignite coals are all burned in point
source boilers.)  Small coal units, common to area sources, are usually
stoker-fired.  There are three types of stoker units:  (1) spread
stokers,  (2) overfeed stokers, and (3) underfeed stokers.  Generally
these small  boilers have no air pollution controls.

    Major toxic pollutants emitted from coal  combustion include metals
and organic  compounds (including aldehyde and polycyclic organic
matter).   Some unburnt combustibles, including numerous organic
compounds, are usually emitted even under proper boiler operating
conditions.

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Virgin Oil.   Both distillate and residual virgin oils (hereafter
referred to as distillate and residual oils) are burned in area source
heating units.  Distillate oils (fuel oil grade Nos. 1 and 2) are used
mainly in domestic and small commercial applications in which easy fuel
burning is required.  Distillates are more volatile and less viscous than
residual oils, having negligible ash and nitrogen contents and usually
containing less than 0.3 weight percent sulfur.  Residual oils (grade
Nos. 4, 5, and 6), on the other hand, are used mainly in industrial and
utility boilers and larger commercial applications.  Residual oils, which
are produced from the residue left after lighter fractions (gasoline,
kerosene, and distillate oils) have been removed from the crude oil,
usually contain higher quantities of ash, nitrogen, and sulfur.  Thus,
burning residual oils generally produces greater concentrations of air
toxics than does burning distillate oils.

    Pollutant loadings from fuel oil combustion are also influenced by
the type  (tangential, wall, etc.) and size of the boiler, firing and
loading practices, and equipment maintenance   .  If a boiler unit is
operated  improperly or is poorly maintained, the concentrations of toxic
pollutants may increase by several orders of magnitude.

    Natural Gas.  Natural gas is often used as a fuel in heating units to
produce heat  in small industrial boilers and domestic and commercial
space heaters.  Because natural gas  is a gaseous, homogenous fluid, the
effective operation of the combustion unit  is more easily achieved with
its use.

    Even  though natural gas is a relatively clean fuel, some emissions do
occur from the combustion reaction.   For example, improper operating
conditions, including poor mixing and insufficient air, may cause
increased amounts of formaldehyde, polycyclic organic matter, and other
pollutants to be emitted.
 6/88          -.  HEATING  (INCLUDING WASTE OIL COMBUSTION)             3-2

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                       PROCEDURES FOR ESTIMATING AND ALLOCATING
                         AREA SOURCE EMISSIONS OF AIR TOXICS
     It is assumed that no emission controls are used for area sources
burning natural gas.l
     Wood.  The combustion of wood, primarly in residences, can be a
significant source of air toxics, most notably polycyclic organic matter.
As with other fuel combustion technologies, emissions vary depending on
the characteristics of the fuel  burned (e.g., moisture content, wood
type), the operating parameters (most notably the fuel:air ratio),
combustion unit (fireplace, catalytic stove, noncatalytic stove), and
wood load.
     Wood stoves are commonly used as space heaters to supplement
conventional  heating systems in  residences.  They are increasingly found
as the primary source of heat, as well.
     Because of differences in both the magnitude and the composition of
emissions from wood stoves, four different categories of stoves should be
considered when estimating emissions of the conventional  noncatalytic
wood stove, the noncatalytic low emitting wood stove, the pellet fired
noncatalytic wood stove, and the catalytic wood stove.
     Among these categories there are many variations in wood stove
design and operation characteristics.
     The conventional stove category comprises all  stoves without catalytic
combustors not included in the other noncatalytic categories.   Stoves of
many different airflow designs,  such as updraft, downdraft, crossdraft,
and S-flow, may be in this category.
     "Noncatalytic low emitting" wood stoves are those having no catalyst
and meeting EPA certification standards.
     Pellet fired stoves are fueled with pellets of sawdust,  wood products
and other biomass materials pressed into manageable shape and size.  These
3/89           '  HEATING  (INCLUDING WASTE OIL COMBUSTION)             3-3

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                       PROCEDURES  FOR ESTIMATING AND ALLOCATING
                        AREA SOURCE EMISSIONS OF AIR TOXICS
stoves have a specially  designed  or modified grate to accommodate this type
of fuel.
     Catalytic stoves  are equipped with  a ceramic or metal honeycomb
material, called a  combustor  or converter that is coated with a noble
metal  such as platinum or palladium.  The catalyst material reduces the
ignition  temperature of  the unburned hydrocarbons and carbon monoxide in
the exhaust gases,  thus  augmenting their ignition and combustion at normal
stove operating temperatures.  As these  comonents of the gases burn, the
temperature inside the catalyst increases to a point where the ignition of
the gases is essentially self-sustaining.

     Waste Oil.  Approximately 1.1 billion gallons of waste oil are
 generated annually in the United States.   This used oil  is produced by  a
 range of sources such as repair shops, service stations, airports,
 shipyards, and recycling centers.  Additionally, spill cleanup and tank
 cleaning contribute to  waste oil generation.  A major portion of  this
 waste oil, 400 to 660 million gallons, is burned in boilers, kilns,
 diesel  engines, and waste oil heaters.  Ninety-two percent of the oil
 that is  burned is burned in boilers.   Combustion represents the largest
 single use of waste oil, with the remainder being re-refined, used as
                                          2
 dust suppressants, landfilled,   or dumped.

     The major concern about using waste oil as fuel is related to
 increased emissions of air toxics, as  a result of contamination of the
 oil.   Available literature indicates that air emissions  are dependent on
 the type of combustion  unit, the waste oil composition,  operating
 parameters, and the type of air pollution controls in place.

     Oil-fired boilers consuming waste  oil include small  residential
 boilers, intermediate commercial and institutional boilers, and large
 industrial boilers.  Typically, industrial boilers are larger in  size and
 achieve high combustion efficiency at  higher burner temperatures; the
 factors that affect the quality of combustion are not as carefully
 controlled in smaller boilers.   These  conditions impose  a tremendous

3/89               HEATING (INCLUDING WASTE  OIL  COMBUSTION)            3-4

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
variability in the level of metal emissions from boilers, the average
metal emissions ranging from 31 to 75 percent of the original metal
feed.  However, to be on the conservative side, a 100 percent emission
rate for metals could be assumed.

    Methods for estimating emissions of air toxics from  industrial,
commercial, institutional, and residential area source burning of coal,
virgin oil, wood, and natural gas are discussed in Sections 3.1 through
3.3.  An approach for estimating emissions from waste oil combustion is
described in Section 3.4.

    A method for estimating the quantities of fuel burned by stationary
area sources (activity levels) has been documented by GCA Technologies,
    3
Inc.   Portions of that document are incorporated directly into this
manual (with approval from Dale-Pahl, the EPA Project Officer).
Secondary references cited in Reference 3 have been cited in this manual,
as well, so that the reader can obtain additional information if needed.

    Emission factors have been compiled for each heating category, along
with example calculations to demonstrate the application of activity
levels .and emission factors to estimate countywide pollutant loads.  In
addition, thermal equivalents for various fuels and densities of fuels
are presented in Tables 3-1 and 3-2, respectively, to help in conversions
in estimating emissions.

     The EPA has  developed a VOC and particulate spectatton manual4 which
contains factors  for  a  number of point and area source categories,  including
heating, that can be  used to supplement factors provided in this  manual.
Many of those factors may be incorporated, with mtnor revisions,  into
future versions of this  manual.
6/88         "-   HEATING (INCLUDING WASTE OIL COMBUSTION)            3-5

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                  PROCEDURES FOR ESTIMATING  AND  ALLOCATING
                      AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
                        Table 3-1 Thermal Equivalents for Various Fuels
        Type of fuel
                  8TU  (gross)
                                                           kcal
Solid fuels

  Bituminous  coal
  Anthracite  coal
  Wood

Liquid fuels

  Residual fuel oil
  Distillate  fuel 011

Gaseous fuels

  Natural gas
                                  (21.0 to  28.0) x 10D/ton
                                  25.3 x 10ฃ
                                  21.0 x lOVcord
                                  6.3 x 10D/bbl
                                  5.9 x 106/bbl
                                  1,050/fr
                                       (5.8 to 7.8) x 10D/MT
                                       7 03 x 105/MT
                                       1 47 x 10S/m3
                                       10 x 103/liter
                                       9.35 x 103/liter
                                       9.350/nT
        Source:  Reference 1.
                             Table 3-2  Densities of Selected Fuels
Fuel
Fuels
Crude oil
Residual oil
Dlsti Hate 01 1
Gasoline
Natural gas
Wood3


874 kg/m3
944 kg/m3
845 kg/m3
739 kg/m3
673 kg/m3
600 kg/m3
Density

7.30
7.88
7.05
6.17
1.00
38.00


Ib/gal
Ib/gal
Ib/gal
Ib/gal
lb/23.8 ft3
lb/ft3
         Average of  10 wood types

        Source:  Reference 1.
6/88
HEATING  (INCLUDING  WASTE OIL COMBUSTION)
                                                                                     3-6

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
3.2    Industrial Heating

    This category encompasses all industrial stationary combustion
sources that are not typically included as point sources.  Traditionally,
boilers larger than 26 GJ/hr are treated in inventories as point
sources.  Combustion equipment in this category is used for energy and
steam generation, along with space heating.
    Small  industrial boilers generally use the following types of fuel:
anthracite coal, bituminous coal, industrial coke, distillate oil and
natural gas.

    (1)  Activity Levels for Industrial Heating.  Walden  developed a
procedure for the estimation of state industrial area source consumption
of bituminous coal, distillate oil,  residual oil, natural gas, and liquid
petroleum gas (LPG).  NEDS' estimates of countywide fuel consumption are
calculated using these procedures and can be used in combination with
emission factors to estimate countywide emissions.

    (2)  Emission Factors for Industrial Heating.  Emission factors to
estimate air toxics emissions from industrial  area source heating are
presented in Table 3-3.  Emissions can be calculated by multiplying the
activity for each area source by the appropriate emission factor.

    Most of the emission factors were taken from Reference 6.  It was
conservatively assumed that no controls are in place and that
technologies common to small units typical of area sources (such as coal
stokers) were used.  Emissions of ROMs were estimated based on
information provided by ORD, who defined ROMs as the benzene extractable
portion of particulate matter.  For each source category e.g. industrial
coal,  residential oil, ORD provided a percent of particulate that is
considered to be ROMs for that category.
6/88         \   HEATING (INCLUDING WASTE OIL COMBUSTION)            3-7

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                PROCEDURES FOR  ESTIMATING AND  ALLOCATING
                  AREA SOURCE EMISSIONS  OF  AIR TOXICS
                  Table 3-3 Emission Factors for Industrial Area Source Heating
Fuel type Pollutant
Anthracite Arsenic

Benzo(a)pyrene
Beryllium
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS


Vanadium
Bituminous Coal Arsenic

Benzo(a)pyrene
Beryllium

Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS


Vanadium
Residual oil Arsenic
Benzo(a)pyrene

Beryllium
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS
Emission factor
482 pg/J (2.5 x 10~2 Ib/ton)

0.06 pg/J (3.3 x 10"6 Ib/ton)
0.005 pg/J (9 5 x 10"4 Ib/ton)
17 9 pg/J (9.4 x 104 Ib/ton)
38.3 pg/J (2.1 x 10'3 Ib/ton)
537 pg/J (3 x 10~2 Ib/ton)
4.1 pg/J (2.3 x 10~4 Ib/ton)
68.4 pg/J (3.8 x 103 Ib/ton)
343 pg/J (1.8 x 10~2 Ib/ton)


58.1 pg/J (3.2 x 10"3 Ib/ton)
482 pg/J (2.7 x 10~2 Ib/ton)

0.06 pg/J (3.5 x 10"6 Ib/ton)
18.1 pg/J (1.0 x 10"3 Ib/ton)

17.9 pg/J (1.0 x 10"3 Ib/ton)
38.3 pg/J (2.2 x 10'3 Ib/ton)
537.0 pg/J (3 x 10~2 Ib/ton)
4.1 pg/J (2.4 x 10"4 Ib/ton)
68.4 pg/J (4.0 x 10"3 Ib/ton)
537 pg/J (3.0 x 10~2 Ib/ton)


58.1 pg/J (3.4 x 10"3 Ib/ton)
47.3 pg/J (1.6 x 10"2 lb/1.000 gal)
0.13 pg/J (4.52 x 10"5 lb/1.000 gal)
0.2 pg/J (7.0 x 10"5 lb/1,000 gal)
1.9 pg/J (6.6 x 10~4 lb/1,000 gal)
71.3 pg/J (2.5 x 10"2 lb/1.000 gal)
28.6 pg/J (1.0 x 10"2 lb/1,000 gal)
94.4 gh/J (3.3 x 10"2 lb/1.000 gal)
4.1 pg/J (1.42 x 10"3 lb/1,000 gal)
31.4 pg/J (1.0 x 10"2 lb/1,000 gal)
207 pg/J (7.0 x 10"2 lb/1.000 gal)
Reference
6

6

6
6
6
6
6
7. 1


6
6

6
6

6
6
6
6
6
7. 1


6
6
6
6
6
6
6
6
6
6
7. 1
Comment
Stoker
(uncontrolled)

Stoker
Stoker
Stoker

Stoker
Stoker
Assumed POMS are
0.2% of TSP for
Anthracite stoker

Stoker
(uncontrolled)

Stoker
(uncontrolled)
Stoker
Stoker

Stoker
Stoker
Assumed POMS are
0.2% of TSP for
Bituminous stoker

Tangential, Wall
Tangential
Wall
Tangential, Wall
Tangential, Wall
Tangential, Wall

Tangential, Wall
Tangential, Wall
Assumed POMS are
               Vanadium
           1000 pg/J (3.5 x 10"1 lb/1.000 gal)
0.7% of  TSP
Tangential, Wall
6/88
HEATING (INCLUDING WASTE OIL  COMBUSTION)
                                                                              3-8

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                    PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                       AREA SOURCE EMISSIONS  OF AIR  TOXICS
                                       Table 3-3 (Continued)
  Fuel  type
Natural  Gas
  Pollutant
       Emission factor
Reference
Comment
Oisti 1 late 01 1 Arsenic
Benzo(a)pyrene

Beryllium
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS

Vanadium
47
0.
0.
1.
71
28
94
4.
31
43

.3
13
2
9
.3
.6
.4
1
.4
.3

1000
pg/J
pg/J
pg/J
pg/J
pg/J
pg/J
pg/J
pg/J
pg/J
pg/J

pg/J
(i
(4
(6.
(6.
(2
(9
(3
(1.
(1
(1

(3
.53
.23
5 x
2 x
.3
.3
.3
33
.02
.4

.2
x 10"2
x 10"5
lb/ 1.000
lb/1,000
gal)
gal)
10"5 lb/1,000 gal)
10~4 lb/1,000 gal)
x 10"2
x 10"3
x 10"2
x 10"3
x 10"2
x lO'2

x 10"1
lb/1,000
lb/1,000
lb/1,000
lb/1,000
lb/1.000
lb/1,000

lb/1,000
gal)
gal)
gal)
gal)
gal)
gal)

gal)
6
6
6
6
6
6
6
6
6
7, 1

6
Tangential ,
Tangential
Wall
Tangential ,
Tangent lal ,
Tangential ,

Tangential,
Tangential ,
Assumed POMS
0.7% of TSP
Tangential ,
Wall


Wall
Wall
Wall

Wall
Wall
are

Wall
FormaIdehyde
2.0 x 10ฐlb/million cubic feet
   16
Note:  pg/J indicates picograms per joule.
    6/88
    HEATING  (INCLUDING WASTE OIL COMBUSTION)
                                                                                    3-9

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
3.3    Commercial and Institutional Heating

    The commercial and institutional heating source category includes  all
stationary fuel combustion sources that are not included under residen-
tial sources, industrial sources, power plants, or commercial point
sources.  Major commercial/institutional area sources include hospitals,
hotels, laundries, schools, and universities.

    Activity levels for commercial/institutional heating.  Quantities  of
fuels burned by industry  are estimated for anthracite coal, bituminous
coal, distillate oil, residual oil, and natural gas using the methodology
described by Wai den.5 The  NEDS data base estimates commercial/institutional
fuel consumption  by fuel  type, using these procedures.  These values can
be multiplied by  the appropriate emission factor listed in Table 3-4 to
estimate emissions.

    A methodology for estimating waste oil consumption in residential,
institutional, and commercial (RIC) and industrial boilers can be  found
in Section 3.4.  It  is estimated that 23 percent of the waste oil  that  is
burned in the United States is burned in RIC boilers.

    Emission factors for commercial/institutional heating.   Emission
factors for commercial and institutional heating are presented in  Table
3-4.  Emissions can  be calculated by multiplying the activity for  each
area source by the appropriate emission factor.

    Most of the emission factors were taken from Reference 6.  It  was
conservatively assumed that no controls are in place and that
technologies common  to small units typical of area sources (such as coal
stokers) were used.  Emissions of ROMs were estimated based  on
information provided by ORD, who defined ROMs as the benzene extractable
portion of particulate matter.  For each source category e.g. industrial
coal, residential  oil, ORD provided a percent of particulate that  is
considered to be POMs for that category.
6/88          "   HEATING  (INCLUDING WASTE OIL COMBUSTION)             3-10

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                   PROCEDURES  FOR ESTIMATING  AND ALLOCATING
                      AREA  SOURCE  EMISSIONS OF AIR TOXICS
              Table 3-4 Emission Factors for Commercial/Institutional Area Source Heating
Fuel type Pollutant
Anthracite coal Arsenic
Benzo(a)pyrene
Beryllium
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS

Vanadium
Bituminous coal Arsenic
Benzo(a)pyrene
Beryl 1 lum
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS

Vanadium
Residual oil Arsenic
Benzo(a)Pyrene
Beryl 1 lum
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS
Emission factor
482 pg/J (2.7 x 1~2 Ib/'ton)
4.7 pg/J (2 6 x 10"4 Ib/ton)
18.1 pg/J (9.5 x 10~4 Ib/ton)
12.9 pg/J (7.1 x 10"3 Ib/ton)
38.3 pg/J (2 1 x 10"3 Ib/ton)
567 pg/J (3 x 10~2 Ib/ton)
4.1 pg/J (2.3 x 10"4Jb/ton)
68.4 pg/J (3.8 x 10"3 Ib/ton)
1486 pg/J (7.8 x 10~2 Ib/ton)

51.8 pg/J (2.8 x 10"3 Ib/ton)
482 pg/J (2.8 x 10~2 Ib/ton)
4.7 pg/J (2.7 x 10~4 Ib/ton)
18.1 pg/J (1.0 x 10~3 Ib/ton)
12.9 pg/J (7.5 x 10"4 Ib/ton)
38.3 pg/J (2.2 x 10"3 Ib/ton)
537.0 pg/J (3.0 x 10~2 Ib/ton)
4.1 pg/J (2.4 x 10"4Jb/ton)
68.4 pg/J (4.0 x 10"3 Ib/ton)
543 pg/J (3 x 10"2 Ib/ton)

51.8 pg/J (3.0 x 10"3 Ib/ton)
47.3 pg/J (1.6 x 10"2 lb/1,000 gal)
0.4 pg/J (1.4 x 10"4 lb/1,000 gal)
0.1 pg/J (3.5 x 10"5 lb/1.000 gal)
71.8 pg/J (2.5 x 10~2 lb/1.000 gal)
50.0 pg/J (1.7 x 10"2 lb/1,000 gal)
94.4 pg/J (3.3 x 10"2 lb/1.000 gal)
4.1 pg/J (1.4 x 10"3 lb/1.000 gal)
804 pg/J (2.7 x 10"1 lb/1,000 gal)
40 pg/J (1 4 x 10"2lb/l,000 gal)
Reference
6
6
6
6
5

6
6
7. 1

6
6
6
6
6
6
6
6
6
7, 1

6
6
6
6
6
6
6
6
6
7, 1
Comment
Stoker
Stoker
Stoker
Stoker
Stoker

Stoker
Stoker









Assumed POMS are
0.2% of TSP
Stoker
Stoker
Stoker
Stoker
Stoker
Stoker

Stoker
Stoker
Assumed POMS
0.2% of TSP
Stoker
Tangential ,
Tangent lal ,
Tangential ,
Tangential ,
. Tangential,

Tangential ,
Tangential,
Assumed POMS










are


Wall
Wall
Wall
Wall
Wall

Wall
Wall
are
                Vanadium
             3660 pg/J (1.2 lb/1,000 gal)
0.7% of TSP
Tangential, Wall
6/88
HEATING (INCLUDING  WASTE OIL COMBUSTION)
                                                                               3-11

-------
                      PROCEDURES FOR ESTIMATING  AND ALLOCATING
                        AREA SOURCE EMISSIONS OF AIR TOXICS
                                       Table 3-4 (Continued)
  Fuel type
Natural Gas
  Pollutant
       Emission factor
Reference
Comment
Disti Hate 01 1 Arsenic
Benzo(a)Pyrene

Beryllium
Cadmium
Chromium
Formaldehyde
lead
Nickel
POMS

Vanadium
47.3 pg/J (1.5 x 10~2 lb/1,000 gal)
0 4 pg/J (1.3 x 10"4 lb/1.000 qal)
c
0.1 pg/J (3.3 x 10~J lb/1.000 gal)
71.8 pg/J (2.3 x 10"2 lb/1,000 gal)
50.0 pg/J (1.6 x 10~2 lb/1.000 gal)
94 4 pg/J (3.3 x 10"2 lb/1,000 gal)
4.1 pg/J (1.3 x 10"J lb/1,000 gal)
112 pg/J (3 6 x 10"2 lb/1,000 gal)
44 pg/J (1 4 x 10~2 lb/1,000 gal)

30 pg/J (9.8 x 10~2 lb/1,000 gal)
6
6

6
6
'6
6
6
6
7. 1

6
Tangential ,
Tangential ,

Tangential ,
Tangential ,
Tangential ,

Tangential,
Tangential,
Assumed POMS
0.7% of TSP
Tangential ,
Wall
Wall

Wall
Wall
Wall

Wall
Wall
are

Wall
Formaldehyde
6.3 x 10   Ib/million cubic feet
Note:  pg/J indicates picograms per joule
   6/88
    HEATING (INCLUDING  WASTE  OIL COMBUSTION)
                                                3-12

-------
                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
3.4    Residential Heating

    The residential heating category includes emissions for residential
activities that use fuel for water heating, space heating, and cooking.
Emissions contributed by residential fuel consumption are broken down
into six categories according to the type of fuel.  Fuel types included
are anthracite coal, bituminous coal, distillate oil, residual oil,
natural gas, and wood.  For each of the listed fuel types, activity
levels measured by fuel quantity consumed in weight or volume units are
multiplied by emission factors listed in Table 3-5 to obtain emissions
estimates.  Methodologies for activity levels follow.

    Activity levels for residential heating.  Total county residential
consumptions of coal, oil, and natural gas are calculated based on
algorithms derived by Walden.   It should be noted that residential
                                                     Q
residual oil consumption is assumed to be negligible.   Residential
wood consumption provided in NEDS also are based on Estimates of U.S.
Wood Energy Consumption.   updated annually using regional data from
                          Q
the Annual Housing Survey.   The NEDS data base provides estimates of
consumption based on these procedures.

    Emission factors for residential heating.  Air toxic emission factors
are presented in Table 3-5.  Emissions can be estimated by multiplying
the appropriate factor from Table 3-5 by the activity for the area of
concern.

    Most of the emission factors were taken from Reference 6.  It was
conservatively assumed that no controls are in place and that
technologies common to small units typical of area sources (such as coal
stokers) were used.  Emissions of ROMs were estimated based on
information provided by ORD, who defined ROMs as the benzene extractable
portion of particulate matter.  For each source category e.g. industrial
coal,  residential oil, ORD provided a percent of particulate that is
considered to be ROMs for that category..
6/88         -.   HEATING (INCLUDING WASTE OIL .COMBUSTION)            3-13

-------
                  PROCEDURES FOR  ESTIMATING  AND ALLOCATING
                    AREA  SOURCE EMISSIONS OF AIR  TOXICS
                 Table 3-5 Emission Factors for Residential Area Source Heating
Fuel type Pollutant
Bituminous coal Arsenic
Benzo(a)pyrene
Beryllium
Cadmium
Chromium
Formaldehyde
Lead
Nickel
POMS

Vanadium
Anthracite coal Arsenic
Benzo(a)pyrene
Beryllium
Cadmium
Chromium
Lead
Nickel
Formaldehyde

POMS

Vanadium
Disti Hate 01 1 Arsenic
Benzo(a)pyrene
Beryl lium
Cadm i urn
Chromium
Formaldehyde


Lead
Nickel
POMS

Vanadium
Emission factor
717 pg/J (4.2 x 10'2 Ib/ton)
108 pg/J (6.0 x 10"3 Ib/ton)
7.2 pg/J (4.2 x 10"4 Ib/ton)
17.9 pg/J (1.0 x 10"3 Ib/ton)
71.3 pg/J (4.1 x 10~3 Ib/ton)
43.0 pg/J (2.4 x 10"3 Ib/ton)
359 pg/J (2.1 x 10"2 Ib/ton)
71.8 pg/J (4.2 x 10"3 Ib/ton)
221,960 pg/J (12.4 Ib/ton)

71.8 pg/J (4.2 x 10"3 Ib/ton)
166 pg/J (9.86 x 10~3 Ib/ton)
106 pg/J (6.2 x ID"3 Ib/ton)
6.6 pg/J (3.9 x 10~4 Ib/ton)
6.6 pg/J (3.9 x 10"4 Ib/ton)
56.2 pg/J (3.3 x 10"3 Ib/ton)
265 pg/J (1.6 x 10'2 Ib/ton)
66.2 pg/J (3.9 x 10"3 Ib/ton)
40.9 pg/J (2.4 x 10"3 Ib/ton)

141,351 pg/J (8.3 Ib/ton)

56.2 pg/J (3.3 x 10'3 Ib/ton)
1.5 pg/J (5.1 x 10~4 lb/1,000 gal)
0.1 pg/J (3.4 x 10"5 lb/1,000 gal)
1.9 pg/J (6.4 x 10"4 lb/1.000 gal)
11 pg/J (3.7 x 10"3 lb/1.000 gal)
1.1 pg/J (3.7 x 10~4 lb/1,000 gal)
94.4 pg/J (3.3 x 10"2 lb/1.000 gal)


9.5 pg/J (3.2 x 10'3 lb/1,000 gal)
103 pg/J (3.5 x 10"2 lb/1,000 gal)
2,451 pg/J (8.2 x 10"1 lb/1.000 gal)

10.1 pg/J (3.4 x 10"3 lb/1,000 gal)
Reference Comment
6
6
6
6
6
6
6
6
7, 1 Assumed POMS are
83% of TSP
6
6
6
6
6
6
6
6
6 Assumed same as
Bituminous
7, 1 Assumed POMS are
83% of TSP
6
6
6
6
6
6
6 Assumed same as
commercial
distillate
6
6
7. 1 Assumed POMS are
33% of TSP
6
6/88
HEATING  (INCLUDING WASTE OIL COMBUSTION)
3-14

-------
                     PROCEDURES  FOR ESTIMATING AND ALLOCATING
                       AREA SOURCE  EMISSIONS OF AIR  TOXICS
                                    Table 3-5 (Continued)
Fuel type
Wood-woodstoves








Wood-fireplaces



Natural Gas
Pollutant
Acetaldehyde
Acrolein
Arsenic
Benzo(a)pyrene
Beryl 1 lum

Formaldehyde
Nickel

POMS



Acetaldehyde
Acrolein
Arsenic
Benzol a)pyrene
Beryllium
Cadmium
Formaldehyde
Nickel
POMS

Formaldehyde
Emission factor
0.24 Ib/ton
7.3 x 10"2 Ib/ton
3.6 x 10"4 Ib/ton
3.4 x IO"6 Ib/ton
2 9 x 10"7 Ib/ton
'
0.48 Ib/ton
6.0 x IO"5 Ib/ton

3.4 x 101 Ib/ton •



1.4 Ib/ton
7.3 x 10"2 Ib/ton
2.6 x iO"4 Ib/ton
3.0 x IO"6 Ib/ton
2.9 x IO"7 Ib/ton
7.1 x IO"5 Ib/ton
3.0 Ib/ton
3.3 x IO"3 Ib/ton
2.3 x IO1 Ib/ton

6.2 Ib/ton million cubic feet
Reference
10
11
10
11
10

6
11

7. 1



6
11
10
11
10
10
6
10
7. 1

8
Comment
Average catalytic
and noncatalyt ic.
Assumed max cured
pine, noncatalytic
Assumed max cured
oak, noncatalytic
Assumed POMS are
83% of TSP for
conventional non-
catalytic
Assumed same as
woodstoves
Assumed POMs are
83% of TSP

Note:  pg/J indicates picograms per joule.
  6/88
HEATING  (INCLUDING  WASTE OIL COMBUSTION)
3-15

-------
                     PROCEDURES  FOR ESTIMATING -AND ALLOCATING
                       AREA SOURCE  EMISSIONS OF AIR  TOXICS
                    Table 3-6 Apportionment of Residential Wood Consumption
                 Between Fireplaces (FP) and Wood Stoves (WS) for the Year  1976
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of
Columbia
Florida
Georgia
Hawa i i
Idaho
11 1 i no i s
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania

AL
AK
AZ
AR
CA
CO
CT
DE

DC
FL
GA
HI
ID
IL
IN
IA
KS
KY
LA
ME
MD
MA
MI
MN
MS
MO
MT
NE
NV
NH
NJ
NM
NY
NC
NO
OH
OK
OR
PA
FP
.08
14
.57
.17
.57
.40
.26
.28

.29
.30
.17
.57
.39
.32
.33
.32
.32
. .16
.29
.04
.29
.25
.19
.11
.16
.19
.40
.32
.56
.04
.40
.73
.25
.30
.33
.32
.45
.13
.40
WS
.92
.86
.43
.83
.43
.60
.74
.72

.71
.70
.83
.43
.61
.68
.67
.66
.68
.84
.71
.96
.71
.75
.81
.89
.84
.81
.60
.68
.44
.96
.60
.27
.75
.70
.67
.68
.55
.87
.60
6/88             "'HEATING (INCLUDING WASTE OIL COMBUSTION)              3-16

-------
                PROCEDURES FOR ESTIMATING  AND ALLOCATING
                   AREA SOURCE  EMISSIONS OF AIR  TOXICS
                              Table 3-6 (Continued)
         State                           FP          WS
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming

RI
SC
SD
TN
TX
UT
VT
VA
UA
WV
WI
WY

.40
.30
'.30
.05
.29
.42
.04
.30
.13
.30
.19
.40
.24
.60
.70
.70
.95
.71
.58
.96
.70
.87
.70
.81
60
.76
         Source:  Reference 10.
6/88         -    HEATING  (INCLUDING WASTE  OIL COMBUSTION)              3-17

-------
                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
3.5    Waste Oil Combustion

    As mentioned earlier, between 400 million and 660 million gallons of
waste oil is burned in boilers, kilns, diesel engines, and waste oil
heaters.  Ninety-two percent of the oil that is burned is burned in
boilers, with 77 percent burned in industrial boilers and 23 percent
burned in RIC units.  Table 3-7 presents a rough estimate of
state-by-state waste oil consumption.

    A number of studies have been performed to characterize the
                                                             12
contaminant concentrations in waste oil.  Franklin Associates   has
provided .a detailed analysis of the typical contaminant concentrations  in
waste oil.  Extensive sampling was carried out as a part of the study for
each source of oil and its end-use application.  The range of contaminant
concentrations determined in the study varied from virtually zero to very
high for most contaminants.  In general, this large variation in
contaminant concentration occurs because of (1) the numerous and varied
processes and mechanism that originally contaminated the oil, (2) the
different types of oil, and (3) the various additives that are used to
enhance the performance characteristics of the oil.

    Waste oil is often pretreated prior to burning.  The pretreatment
includes  (1) reprocessing of the waste oil, (2) re-refining of the waste
oil, and  (3) blending of virgin or clean fuel oil with the waste oil.   It
has been  estimated that approximately 44 percent of the total waste oil
                                                    12
generated in 1982 underwent some form of processing.

    Median concentrations of metals and organics in waste oil, the
fraction  emitted, and emissions factors based on population and fuel
usage are presented in Table 3-8.
6/88          -.  HEATING  (INCLUDING WASTE OIL COMBUSTION)             3-18

-------
                     PRnrrnURES FOR  ESTIMATING AND  ALLOCATING
                        ARE!SOURCE EMISSIONS  OF  AIR TOXICS
                       Table 3-7 Waste Oil Consumption by State
State
Alabama
Alaska
Arizona
Cal ifornia
Colorado
Connecticut
Delaware
Florida
Georgia
Hawa i i
Idaho
I Ilinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Total - 429.014
Waste 01 1 burned
(gal Ions)
6,678,000
374,000
5,130.000
36,053,000
6,080.000
3,610,000
1,606,000
10,640,000
8,542,000
608,000
570,000
19,419,000
6,707,000
4.151,000
8,220,000
4.075.000
17,233,000
2 , 098 , 000
6,287,000
8,550,000
24,397,000
7,373,000
4,431,000
13,590,000
969,000
,000 gallons
State
Nebraska
Nevada
New Hampshire
New Mexico
New York
North Carolina
North Dakota
Ohio
Ok lahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington, DC
Washington
West Virginia
Wisconsin
Wyoming


Waste 01 1 burned
(gallons)
5,362,000
1,069,000
855.000
2,563,000
16,503,000
9,856,000
665,000
9,405,000
12.806,000
5,653,000
32,797,000
2.166,000
4,367.000
739,000
10,947,000
43,698.000
2.660.000
470,000
7,429,000
556.000
9.063,000
4,932,000
5,013,000
1,461,000


 Source:  Communication between Hope Pillsbury, IEMD, EPA, and Eric Males, OSW, EPA, cited in

 Reference 13.
6/88
HEATING (INCLUDING WASTE OIL  COMBUSTION)
3-19

-------
                    PROCEDURES FOR ESTIMATING AND  ALLOCATING
                       AREA SOURCE  EMISSIONS  OF  AIR TOXICS
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   6/88
HEATING  (INCLUDING  WASTE OIL COMBUSTION)
3-20

-------
                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Test data indicate destruction efficiencies for organics ranging from
97 to 99.99 percent.  Higher combustion temperatures in industrial
boilers dictate higher destruction efficiencies.  Hence, a 99.9 percent
destruction efficiency for organics in industrial boilers is a reasonable
estimate.  In residential, institutional and commercial (RIC) boilers,
where the units tend to be less efficient, a 99 percent destruction
efficiency for organics is assumed to be representative.

    Because the boilers using waste oil as a fuel vastly differ in their
characteristics, simple quantification of boiler population, fuel
blending, or oil consumption is not practical.  OSW has estimated that
about 100 million gallons of waste oil are burned in RIC boilers
(23 percent) and about 330 million gallons are burned in industrial
boilers (77 percent).  It has also been indicated that waste oil is more
likely to be burned at facilities that currently burn residual oil than
                                  14
at those that burn distillate oil.

    Methodology Options.   Toxic emissions that result from the combustion
of waste oil can be estimated when one of the following is known or can
be estimated:
    •  The quantity of waste oil burned in the study area;
    •  The population of a particular county, state, or region; or
    •  The quantity of waste oil burned for a particular state, county,
       or region can be estimated.

    Method 1:  Estimates based on fuel consumption data

    This approach is preferred when data on countywide consumption are
available or can be collected by surveying users or distributors.  Once
data on the quantity of waste oil  burned in the county or state are
known, the estimation of emissions is straightforward.   The emission
6/88         -    HEATING (INCLUDING WASTE OIL COMBUSTION)            3-21

-------
                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
factor (Table 3-8) that relates the quantities of emissions emitted per
1,000 gallons of waste oil  burned is multiplied by the quantity of waste
oil  burned in the county or state.   For example, if the county burns
74,290 gallons of waste oil annually and the emission factor from Table
2.2-8 is 3.6 kg Pb/1,000 gallons of waste oil burned/year, then the
amount of lead emitted can  be estimated as follows:

Pb emitted = 74.290 (thousand gallons of waste oil burned) 3.6 kg Pb
                                                           1000 gallons waste
                                                          oil burned per year

Pb emitted = 267 kg/yr

    Method 2:  Estimates based on population (per capita estimates).

    Population data can be collected from the U.S. Census Bureau.  Air
toxic emissions can be estimated by applying the per capita emission
factors from Table 3-8 which relate the quantity emitted per 1,000
persons.  For example, to estimate the quantity of arsenic emitted in a
county of 180,375 persons,  use the emission factor from Table 3-8 to
estimate the amount of arsenic emitted annually.

As emitted = 180.4 (1,000persons) x 3.5 x 10"2 kg As/1,000 persons/yr
As emitted =6.3 kg/yr.

    Method 3:  Estimates based on virgin oil consumption

    This method assumes that quantities of waste oil burned  in a given area
is directly proportional to the quantity of residual oil that is burned.

STEP  1:  Determine from NEDS or other sources state and county quantities
         of residual  oil burned in RIC and industrial boilers.
6/88          -  HEATING  (INCLUDING WASTE OIL COMBUSTION)            3-22

-------
                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
STEP 2:  Determine quantity of waste oil burned in each county, assuming

         that the quantity of waste oil burned in the county is directly

         proportional to the quantity of residual oil burned in the

         county.


                        WOC = (CR + Ci + CCI) x WOS
                                 SR H- ST + SCI

    where

       WOQ =   annual waste oil  burned in the county
       CR  =   annual countywide residential residual oil consumption
       Cj  =   annual countywide industrial residual.oil consumption
       CQJ =   annual countywide commercial/institutional residual oil
               consumption
       SR  =   annual state-wide residential residual oil consumption
       Sj  =   annual state-wide industrial residual oil consumption
       SQJ =   annual state-wide commercial/institutional residual oil
               consumption
       W0$ =   annual.state-wide waste oil consumption  (from Table 3-7).


STEP 3:  Calculate the quantity of waste oil burned  in  residential,

         commercial and industrial  boilers assuming  that 23% of the waste
         oil that is burned is burned in RIC boilers, and 77% is burned

         in industrial  boilers.


                           WOR = WOC x 0.23 x CR	
                                              CCI

                          WOCI = WOC x 0.23 x CCI
    where
                                       CCI + CR

                       WOj  =  WOC  x  0.77


        waste oil burned in residential  boilers
.._U1    waste oil burned in commercial/institutional boilers
WOj =   waste oil burned in industrial boilers
6/88          -   HEATING (INCLUDING WASTE OIL COMBUSTION)            3-23

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
STEP 4:  Obtain the emission factor from Table 3-8 for the contaminant in
         question.  (Note:  this factor should relate kg/1,000 gallons
         waste oil burned.)

STEP 5:  Compute metal or organic emission by multiplying the quantity of
         waste oil .burned in the county by the emission factor obtained
         in Step 4.

                             Ep  (WOj +  WOCI +  WOR) x  EFp

    where
       Ep  = annual emission of pollutant p kg/yr
       EFp = emission factor for pollutant p from Table 3-8.

3.6    Example Calculations

    Example calculations for estimating toxic emissions from virgin fuel
combustion are shown below.  Examples of waste oil emission calculations
are contained in Section 3.4.

    Example Calculation 1

    The following calculation estimates the area source emission of
formaldehyde from burning distillate oil in commercial/industrial
boilers.  The consumption of commercial/institutional distillate oil for
a particular county in one year is reported as 12,270,000 gallons (12,270
thousand gallons/year).  The emission factor for formaldehyde for
distillate oil from Table 3-4 is 0.033 lb/1,000 gallons.
6/88          :   HEATING (INCLUDING WASTE OIL COMBUSTION)            3-24

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    The calculation is as follows:

    12.270 thousand gallons  X  0.033 1b Formaldehyde  = 405 Ib/year
             year                 thousand gallons

    For the county in question, the estimated formaldehyde emission from
commercial/institutional boilers burning distillate oil is 405 Ib/yr.

    Other pollutants in Table 3-4 can be estimated in a similar manner
for commercial/institutional boilers.  Emissions from the burning of
other fossil fuels in residential, industrial, and commercial/
institutional can be estimated using a similar methodology as well.

    Example Calculation 2

    This example illustrates the calculation of acetaldehyde emissions
due to burning of wood in woodstoves and fireplaces in a county in
Maryland.  The residential  wood consumption in this county for one year
is 1,000 tons.  The woodstove/fireplace apportionment from Table 3-6 for
Maryland is 0.71 for woodstoves and 0.29 for fireplaces (i.e.,  71% of the
wood consumed is burned in woodstoves and 29% in fireplaces).  The
acetaldehyde emission factors from'Table 3-5 are 0.24 Ib/ton for
woodstoves and 1.4 Ib/ton for fireplaces.

    The calculations are as follows:

Woodstoves
    1,000 ton  X  0.71  X 0.24 1b = 170 Ib/yr
      year                  ton
6/88         -    HEATING (INCLUDING WASTE OIL COMBUSTION)             3-25

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
Fireplaces

    1.000 ton  X 0.29  X 1.4 1b = 406 Ib/yr
      year                ton

    The estimated acetaldehyde emissions for the county in question are
170 Ib/yr from woodstoves and 406 Ib/yr for fireplaces.  Other pollutants
in Table 3-5 can be estimated in a similar manner.

3.7    Methods to Apportion Countywide Emissions from Heating

    As described in Section 1.0 and Appendix A,  when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations  in  activity and
emissions.  Similarly,  temporal in activities can be factored into the
modeling to reflect seasonalor diurnal fluctuations in emissions.
Modeling results would then reflect on-going activities in that portion
of the county, e.g., residential heating in the  winter, commercial
solvent usage during working hours on weekdays.

    There are three alternative approaches that  can be used in spatially
distributing emission:   (1) population, i.e., the magnitude of emissions
within a grid are directly proportional to the population living in the
grid, (2) land area, i.e., emissions from a countywide area source are
assumed to be uniform throughout the county and  are distributed based on
the size of the area source grid, and  (3) landuse patterns that assume
that certain area source activities, most likely to occur in certain
areas of the county, e.g., commercial, residential, or industrial.
6/88             HEATING (INCLUDING WASTE OIL COMBUSTION)            3-26

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                  PROCEDURES  FOR  ESTIMATING AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    In apportioning emissions from heating any of these methods may be
appropriate.  Land area and population data can be readily obtained and
applied as described in Appendix A.  Land use data, available from the
U.S. Geological  survey and other sources can be used in combination with
the spatial resolution for heating to distribute emissions based on the
type of activity being performed, as shown in Table 3-9.

    Estimated seasonal, daily, and hourly temporal resolution for heating
are also included in Table 3-9, and can be used with the annual
countywide emissions data to estimate temporal variations.
6/88         -    HEATING (INCLUDING WASTE OIL COMBUSTION)            3-27

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                   PROCEDURES  FOR  ESTIMATING AND  ALLOCATING
                      AREA SOURCE EMISSIONS OF AIR  TOXICS
                         Table 3-9 Spatial and Temporal Resolution
                            for  Heating and Waste Oil Combustion
         Fuel Combustion,  Industrial
                                   15
             Spatial  Resolution
                  Surrogate  indicator:
                  Information source(s):
                   industrial  areas  (codes 13 and 15)
                   land use map
             Temporal  Resolution
                  Seasona 1 :
                  Daily:
                  Hourly:
                   uniform through  the year
                   Monday through Saturday
                   80 percent from  0700 to 1800 and 20
                   percent from 1800 to 2400, otherwise
                   zero
         Fuel Combustion,  Commercial/Institutional
                                                 15
             Spatial Resolution
                  Surrogate  indicator:
                  Information source(s):
                    industrial areas  (codes 12 and 15)
                    land use map and  Reference 16
             Temporal Resolution
                  Seasona 1:
                  Daily:
                  Hourly:
          Fuel Combustion,  Residential
                                    15
             Spatial Resolution
                  Surrogate  indicator:

                  Information  source(s):
                   25 percent uniform through the year and
                   75 percent uniform during the months
                   that have an average temperature of
                   688ฐF or less
                   95 percent Monday through Saturday
                   90 percent from 0600 to 2400 and 10
                   percent from 2400 to 0600
                    residential area  (codes 11, 16, and
                    17); dwelling units
                    land use map
             Temporal Resolution
                  Seasonal:
                  Daily:
                  Hourly:
                    10 percent uniform through the year and
                    90 percent uniform during the months
                    that have an average  temperature of
                    688ฐF or less
                    uniform through the week
                    uniform through the day
6/88
HEATING  (INCLUDING  WASTE  OIL COMBUSTION)
3-28

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                        PROCEDURES FOR  ESTIMATING  AND  ALLOCATING
                           AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS

                                  Table  3-9  (Continued)
         Waste Oil Combustion  (Industrial)
Spatial Resolution
     Surrogate indicator:
     Information source(s):
                                         industrial areas  (codes 13 and  15)
                                         land use map
             Temporal Resolution
                 Seasonal:
                 Daily:
                 Hourly:
                            uniform through the year
                            uniform Monday through  Saturday
                            80 percent from 0700 to 1800, 20
                            percent from 1800 to 2400, otherwise
                            zero
         Waste Oil Combustion  (Residential/Institutional/Commercial)
             Spatial Resolution
                 Surrogate  indicator:
                            residential, institutional, and
                            commercial areas (land  use codes 11,
                            12,  15,  16, 17)
                 Information source(s):    land use maps
             Temporal Resolution
                 Seasona1:
                 Daily:
                 Hourly:
                            25 percent uniform through the year and
                            75 percent uniform during the months
                            that  have an average  temperature of
                            688ฐF or less
                            95 percent Monday through Saturday
                            90 percent from 0600  to 2400, 10
                            percent from 2400 to  0600
6/88
         HEATING  (INCLUDING  WASTE  OIL  COMBUSTION)
                                                                                         3-29

-------
                  PROCEDURES  FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS  OF AIR TOXICS
                                 REFERENCES
 1. U.S. Environmental Protection Agency.  Compilation  of  Air  Pollutant
    Emission Factors. Volume 1:  Stationary Point  and Area Sources
    (AP-42).  Fourth  Edition.  Office of Air Quality Planning  and
    Standards.  Research Triangle Park, NC.  September  1985.

 2. U.S. Environmental Protection Agency. A Risk Assessment of Waste  Oil
    Burning in Boilers and Space Heaters. Contract No.  68-02-3173.
    Office of Solid Waste.  Washington, DC. 1984.
 3,
GCA Technology Division, Inc.   Area Source Documentation for the 1985
National Acid Precipitation Assessment Program Inventory Draft
Report.  U.S. Environmental Protection Agency, Air and Energy
Engineering Research Laboratory.  Research Triangle Park, NC.
September 1986.
4.  Air Emissions  Species Manual, Volume I:  Volatile Organic Compound
    (VOC)  Species  Profiles And Volume II:   Particulate Matter (PM)  Species
    Manual.   EPA-450/2-88-Q03a and b, U. S. Environmental  Protection
    Agency,  Research Triangle Park, NC, April  1988.
  5. Walden Research Division of Abcor.  Methodologies for Countvwide
     Estimation of Coal, Gas, and Organic Solvent Consumption.
     EPA-450/3-75/06.  U.S. Environmental Protection Agency, Office  of Air
     Quality Planning and Standards.  Research Triangle  Park, NC.
     December 1975.

  6. U.S. Environmental Protection Agency.  Preliminary  Compilation  of Air
     Pollutant Emission Factors for Selected Air Toxic Compounds.  Office
     of Air Quality Planning and Standards.  Research Triangle  Park, NC.

 7.  Lewtas, J.  Information provided to Versar, Inc. and the Regulatory
     Integration Division of EPA's Office of Policy and  Resource
     Management.  U.S. Environmental Protection Agency.  Office of
     Research and Development.  Research Triangle Park,  NC.  September
     1987.

 8.  JRB, Inc.  Materials Balance - Formaldehyde.  Revised Draft  Report.
     U.S. Environmental Protection Agency.  Office of Pesticides  and Toxic
     Substances.  Washington, DC.  January  1982.

  9. Walden Research Corporation.  Development of a Methodology to
     Allocate Liquid Fossil Fuel Consumption by County.  EPA-450/3-74-021.
     U.S. Environmental Protection Agency,  Office of Air Quality  Planning
     and Standards.  Research Triangle Park, NC.  March  1974.
  6/88             HEATING  (INCLUDING WASTE OIL COMBUSTION)             3-30

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                REFERENCES
10.  D.G.  De Angelis,  D.S.  Ruffin,  J.A.  Peters,  and R.B. Reznik. Source
    Assessment:  Residential  Combustion of Wood.  EPA-600/2-80-042b. U.S.
    Environmental  Protection Agency,  Office of Research and Development.
    Washington,  DC 1980.

11.  Engineering  Sci-ence,  Inc.  Emission Factor Documentation for AP-42:
    Section 1.10.  Residential Wood Stoves.   (Draft).  U.S. Environmental
    Protection Agency.   Office of Air Quality Planning and Standards.
    Research Triangle Park,  NC.   May  1987.

12.  U.S.  Environmental  Protection Agency.  Composition and Management of
    Used  Oil Generated  in  the United  States.   Office of Solid Waste and
    Emergency Response.   Washington,  DC.  1984.

13.  GCA Technology.   Locating and Estimating  Air Emissions from Sources
    of Chlorobenzenes.  EPA-450/4-84-007m. U.S.  Environmental Protection
    Agency, Office of Air  Quality Planning  and Standards.   Research
    Triangle Park, NC.   1986.

14.  Versar Inc.   Hazardous Air Pollutants,  An Exposure and Preliminary
    Risk  Appraisal for  35  U.S. Counties.  U.S. Environmental Protection
    Agency.  Washington,  DC. 1984.

15.  U.S.  Environmental  Protection Agency.  Procedures for the Preparation
    of Emission  Inventories  for Volatile  Organic Compounds.  Volume II:
    Emission Inventory  Requirements for Photochemical Air Quality
    Simulation Models.   EPA-450/4-79-018.  Office of Air Quality Planning
    and Standards.  Research Triangle Park, NC.  September 1979.

16.  Mineral Industry  Surveys.  Sales  of Fuel  Oil and Kerosene.
6/88         '_   HEATING (INCLUDING WASTE OIL COMBUSTION)            3-31

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
4.     ROAD VEHICLES

4.1    General

    Road vehicles are a major source of organic and inorganic air toxics
in urban areas.  The Six Month Study  which estimated cancer risks from
exposure to selected toxic air pollutants identified mobile sources as
contributing a large portion of the national cancer incidence.  Specific
pollutants and pollutant categories which are emitted by road vehicles
include diesel particulates, formaldehyde, benzene, gas phase organics,
organics associated with non-diesel particulates,  asbestos, and metals.
Sources include exhaust and evaporative  emissions tire wear, and (in the
case of asbestos) emissions from the wearing away of brake linings.

    The composition of road vehicle emissions varies depending on
numerous factors including the age, model, and condition of the vehicle;
the type of fuel used (i.e., leaded or unleaded gasoline, diesel); the
composition of the gasoline including any additives; driving patterns and
speed; and any pollution controls (catalytic or noncatalytic).  Because
of the large number of parameters that can affect emissions, it is
necessary to apply "typical" vehicular emissions rates to predict
pollutant loadings in a geographic area.  These typical factors are by
vehicular class (e.g., light duty gas, heavy duty diesel) and reflect the
age, accrued mileage, etc., typical of the fleet.

4.2    Factors

    Table 4-1 provides toxic pollutant factors.  Factors that can be used
with NEDS data are provided on an average VMT basis and on a percent of
hydrocarbon emissions.  Many of the factors in Table 4-1 were taken
                          4
directly from Carey (1987) ; that report should be accessed for
additional information.  POM Emissions were estimated based on
                           1 o
information provided by ORD   and are defined as the benzene
exhaustable portion of particulates emitted in road vehicle exhaust.

-------
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                              ROAD VEHICLES
                                                                     4-4

-------
                     PROCEDURES  FOR ESTIMATING  AND  ALLOCATING

                        AREA SOURCE  EMISSIONS  OF  AIR TOXICS
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                                 ROAD VEHICLES
                                                                                         4-5

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               PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                 AREA SOURCE EMISSIONS OF AIR TOXICS




















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6/88
                              ROAD VEHICLES

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
4.3    Methodology Options

    Emission factors can be based on vehicle miles traveled (VMT) and/or
emissions of criteria pollutants, particularly hydrocarbons.  When used
in conjunction with NEDS' VMT data or EPA's MOBILE3 (Mobile Source
Emission Model) both of which predict emissions of criteria pollutants,
apportionment factors can be applied to predict toxic pollutant
emissions.

    In NEDS, road vehicles can be disaggregated into five categories on
the basis of use and gross vehicle weight for the purpose of calculating
emissions.   Light duty gasoline vehicles are defined as gasoline powered
passenger vehicles weighing 8500 pounds or less; similarly light duty
diesel vehicles.  Light duty gasoline Trucks I include gasoline cargo
vehicles weighing 6000 pounds or less.  Light duty gasoline Trucks II
include gasoline cargo vehicles weighing 6001 pounds to 8500 pounds.
Heavy duty vehicle categories separate diesel and gasoline powered trucks
and buses weighing more than 8500 pounds.  Motorcycles, light duty diesel
vehicles and light duty diesel trucks are assumed to contribute little
emissions relative to the above four categories.

    Fuel consumption and average fuel efficiencies are used to determine
vehicle miles traveled (VMT) for four classes of average speed to reflect
road usage, namely, limited access roads (55 mph), rural roads (45 mph),
suburban roads (35 mph), and urban roads (19.6 mph).  At the present
time, NEDS calculates criteria pollutant emissions for limited access
roads, rural  roads and urban road types.  Each speed class includes the
following road types.

    Limited Access Roads       Rural and Urban Interstate
          (55 mph)             Rural and Urban Other Principal Arterials
                               Other Freeways and Expressways
                               Rural and Urban Minor Arterials
6/88         -                ROAD VEHICLES                          4-7

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
   Rural  (45 mph)             Rural  Major Collector
                              Rural  Minor Collector
                              Rural  Local
   Urban (19.6 mph)           Urban Collector
                              Urban Local

    For highway vehicles, NEDS contains data on fuel consumption (10
gallons)  by fuel type for  each vehicle type and speed class specific
annual vehicle miles traveled (VMT), along with estimated emissions of
criteria pollutants.

    MOBILES, on the otherhand, is a computer model that calculates
emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of
nitrogen (NO ) from highway motor vehicles using emission factors
                              2
contained in AP-42, Volume II.   MOBILES estimates depend on various
ambient,  vehicle usage, and local conditions such as temperature, speed,
and mileage accumulation, and accrual distributions. 'MOBILES will
estimate emissions for any calendar year between 1970 and 2020,
inclusive.  The twenty most recent vehicle model years are considered in
operation during each calendar year.  Additional information on MOBILES
can be obtained in Reference 3.
    MOBILES differentiates between evaporative and exhaust emissions.  A
                              A
recent EPA study, (Carey 1987)  compiled emission factors that can be
used with MOBILES to estimate road vehicle related emissions (as well as
exposure and risk); this report is the basis for many of the road vehicle
emission factors that are listed in this manual.
4.4    Example Calculations

    The following examples demonstrate the approach for estimating
emissions from onroad vehicles.
6/88          ..               ROAD VEHICLES                           4-8

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Example Calculation 1
    This example illustrates the calculation of road vehicle emissions
for heavy duty gasoline vehicles (HDGV) using data contained in the NEDS
area source report.  NEDS gives estimated total hydrocarbon emissions in
the three-county study area.  Then, using emission factors in terms of
percent of total hydrocarbons, the emissions of each pollutant can be
determined.
                                      HDGV total hydrocarbons (THC)
   County                             	(MT/vr)	
     A                                           56.21
     B                                           32.85
     C                            •               79.57
   Using the emission factors in terms of percent of hydrocarbons from
Table 4-1 the emissions from heavy duty gasoline vehicles in the study
area of concern can be calculated as follows:

County A
    Formaldehyde:
        Exhaust:  0.031 x 56.21 MT THC = 1.74 MT/yr
        Evaporative:   Not Applicable
    1,3 Butadiene
        Exhaust:  0.0094 x 56.21 MT THC =0.53 MT/yr
        Evaporative:   Not Applicable
    Benzene
        Exhaust:  0.0348 x 56.21 MT THC =1.96 MT/yr
        Evaporative:   0.011 x 56.21 MT THC =0.62 MT/yr
                                  yr
    Ethylene dichloride
        Exhaust:  0.00051 x 56.21 MT THC = 0.029 MT/yr
                                yr
        Evaporative 0.00015 x 56.21 MT THC = 0.0084 MT/yr
                                   yr
6/88                          ROAD VEHICLES                          4-9

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
County B
    Formaldehyde
        Exhaust:  0.031 x 32.85 MT THC = 1.02 MT/yr
                               yr

        Evaporative:  Not Applicable

    1,3 Butadiene
        Exhaust:  0.0094 x 32.85 MT THC = -0.31 MT/yr
        Evaporative:  Not Applicable

    Benzene
        Exhaust:  0.0348 x 32.85 MT THC =1.14 MT/yr
                                yr

        Evaporative:  0.011 x 32.85 MT THC = 0.36 MT/yr
    Ethylene dichloride
        Exhaust:  0.00051 x 32.85 MT THC = 0.017 MT/yr
                                 yr

        Evaporative:  0.00015 x 32.85 MT THC = 0.0049 MT/yr

County C

    Formaldehyde
        Exhaust:  0.031 x 79.57 MT THC = 2.47 MT/yr
                               yr

        Evaporative:  Not Applicable

    1,3 Butadiene
        Exhaust:  0.0094 x 79.57 MT THC =0.75 MT/yr
                                yr

        Evaporative:  Not Applicable

    Benzene
        Exhaust:  0.0348 x 79.57 MT THC =2.77 MT/yr
                                yr

        Evaporative:  0.011 x 79.57 MT THC = 0.87 MT/yr
                                   yr
6/88          -                ROAD VEHICLES                          4-10

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Ethylene dichloride
        Exhaust:  0.00051 x 79.57 MT THC = 0.041 MT/yr
        Evaporative:  0.00015 x 79.57 MT THC = 0.012 MT/yr
                                     yr

    For metals and semi-volatiles the emissions must be calculated using
estimates of VMT as in Example Calculation 2.  Summing the emission over
all the counties will  give the total emissions for the study area.

    [In a similar manner, emissions from other classes of vehicles can be
calculated based on NEDS data.]

Example Calculation 2

    This example demonstrates the calculation of emissions from light
duty gasoline vehicles (LDGV) using data on vehicle miles traveled (VMT)
and emission factors in terms of VMT.

    We will  assume the study area consists of one county.  The annual VMT
for that county is 356,177,000.

    Using the emission factors in terms of VMT from Table 4-1 the
emissions are calculated as follows:

County A
    Formaldehyde
        Exhaust:  3.32 x 1Q-5 MT x 356,177 (1,000 VMT) = 11.82 MT/yr
                     1,000 VMT                yr
        Evaporative:  Not Applicable
6/88         '.                ROAD VEHICLES                          4-11

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
    1,3  Butadiene
        Exhaust:   2.4  x  10-5  MT  x  356,177  (1,000  VMT)  =  8055  MT/yr
                     1,000  VMT                 yr
        Evaporative:   Not Applicable
        Tire  Wear:   1.0  x  10-8 MT  x 356,177  (1,000  VMT)  =  0.0036 MT/yr
                     1,000  VMT                 yr
    Benzene
        Exhaust:   1.27 x 10-4 MT x 356,177 (1,000 VMT)  = 45.23  MT/yr
                     1,000  VMT                 yr
        Evaporative :   Not  Applicable
    Benzo(a)pyrene
        Exhaust:   4.57 x 10-8 MT x 356,177 (1,000 VMT)  = 0.0016 MT/yr
                     1,000  VMT                 yr
        Evaporative:   Not  Applicable
    Lead
        Exhaust:   1.28 x 10-6 MT x 356,177 (1,000 VMT)  = 0.46 MT/yr
                     1,000  VMT                 yr
        Evaporative:   Not  Applicable
    Cadmium
        Exhaust:   1.9 x 10-9  MT  x  356,177  (1,000  VMT)  = 0.00068 MT/yr
                     1,000  VMT                 yr
        Evaporative:   Not  Applicable
        Tire Wear:  4.85 x  10-9  MT x  356,177 (1,000 VMT) * 0.0017 MT/yr
                     1,000  VMT.                yr
    Chromium
        Exhaust:   6.1 x 10-4  MT  x  356,177  (1,000  VMT)  - 217.27 MT/yr
                     1,000 VMT                 yr
        Evaporative:   -Not  Applicable
   The evaporative emissions factor for benzene is given as a range.
To calculate the emissions in this example,  we assumed the emission
factor was the midpoint of the range.

6/88          '                ROAD VEHICLES                           4-12

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Ethylene dichloride
        Exhaust:  7.65 x 10-7 MT x 356,177-(1,000 VHT) = 0.27 MT/yr
                     1,000 VMT                yr
        Evaporative:   1.53 x 10-7 MT x 356,177 (1,000 VMT) = 0.054 MT/yr
                     1,000 VMT                yr
    Acetaldehyde
        Exhaust:  4.8 x 1Q-7 MT x 356,177 (1,000 VMT) = 0.17 MT/yr
                     1,000 VMT                yr
        Evaporative:   Not Applicable
    Asbestos
        Exhaust:  Not Applicable
        Evaporative:   Not Applicable
        Brake Linings:  2.05 x 1Q-9 MT x 356,177 (1,000 VMT) = 0.00073 MT/yr
                          1,000 VMT                 yr   '
    Polycyclic Organic Matter
        Exhaust:  3.92 x 10-6 MT x 356,177 (1,000 VMT) = 1.40 MT/yr
                     1,000 VMT                yr
        Evaporative:   Not Applicable

    Summing the type  of emission for each pollutant will give the total
emission from LDGV for the study area.
    [In a similar manner, emissions from other classes of onroad vehicles
can be calculated.]
4.5     Methods to Apportion Countywide Emissions from Road Vehicles
    As described in Section 1.0 and Appendix A when performing air
dispersion modeling,  it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
6/88         '_                ROAD VEHICLES                          4-13

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
emissions.  Similarly temporal in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect ongoing activities in that portion of
the county, e.g., residential heating in the winter, commercial solvent
usage during working hours on weekdays.
    There are three alternative approaches that can be used in spatially
distributing emission:  (1) population, i.e., the magnitude of emissions
within a grid are directly proportional to the population living  in the
grid; (2) land area, i.e., emissions from a countywide area source are
assumed to be uniform throughout the county and.are distributed based on
the size of the area source grid; and (3) land use patterns, that assume
that certain area source activities, most likely occur in certain areas
of the county, e.g., commercial, residential or industrial.
    In apportining emissions from onroad vehicles any of these methods
may be appropriate.  Land area and population data can'be readily
obtained, and applied as described in Appendix A.  Land use data,
available from the U.S. Geological Survey and other sources can be used
in combination with the spatial resolution for onroad vehicles, to
distribute emissions based on the type of activity being performed, as
shown in Table 4-2.
    Estimated seasonal, daily and hourly temporal resolution for  onroad
vehicles are also included in Table 4-2, and can be used with the annual
countywide emissions data to estimate temporal variations.
6/88          -.               ROAD VEHICLES                           4-14

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                      PROCEDURES  FOR ESTIMATING  AND  ALLOCATING
                         AREA  SOURCE EMISSIONS  OF AIR TOXICS
                 Table  4-2 Spatial and Temporal Resolution  for Road Vehicles
              Spatial  Resolution
                Surrogate Indicator:       traffic volume'
                Information source(s)      zonal  traffic statistics

              Temporal Resolution
                Seasonal:                 uniform through the year
                Daily:                    uniform through the week
                Hourly:                   75 percent from 0600 to 1800,
                                         25 percent from 1800 to 0600
6/88
ROAD VEHICLES                                4-15

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
                                REFERENCES
1.   Haemisegger,  E.,  Jones,  A.,  Steigerwald,  B.,  and Thomson, V.  The Air
    Toxics Problem in the United States:   An  Analyses of Cancer Risks for
    Selected Pollutants.   U.S.  Environmental  Protection Agency.  Office
    of Air and Radiation.  May  1985.

2.   U.S. Environmental  Protection Agency.   Compilation of Air Pollutant
    Emission Factors.  Volume II:  Mobile  Sources.  Motor Vehicle
    Emission Laboratory.   Ann Arbor,  MI.   AP-42.

3.   U.S. Environmental  Protection Agency.   Users  Guide to MOBIL3 (Mobile
    Source Emissions  Model).  Office  of Mobile Sources.  Ann Arbor, MI.

4.   Carey, Penny M.  Air Toxic  Emissions  from Motor Vehicles.  U.S.
    Environmental Protection Agency.   Office  of Mobile Sources.  Ann
    Arbor, MI.  EPA-AA-TSS-PA-86-5.

5.   Lewtas, Joellen.   Information supplied to Versar, Inc. and the
    Regulatory Integration Division of the EPA Office of Policy and
    Resource Management.   -U.S.  Environmental  Protection Agency.  Office
    of Research and Development.  September 1987.

6.   Smith, L.R.,  Black, F.M.  "Characterization of Exhaust Emissions from
    Passenger Cars Equipped with Three-way Catalyst Systems."  Society of
    Automotive Engineers.  Warrendale, PA.  1980.

7.   Versar, Inc.   Non-Occupational Asbestos Exposure.  U.S. Environmental
    Protection Agency.   Office  of Toxic Substances.  Washington, DC.
    1987.

8.   U.S. Environmental  Protection Agency.   Sources of Atmospheric
    Cadmium.  EPA-450/5-79-006.   U.S. Environmental Protection Agency.
    Office of Air Quality Planning and Standards.  Research Triangle
    Park, NC.  1979.

9.   Radian Inc.  Compiling Air Toxics Emission Inventories.
    EPA-450/4-86-010.  U.S.  Environmental  Protection Agency.  Office of
    Air Quality Planning and Standards.  Research Triangle Park, NC.
    July 1986.

10. Versar Inc.  Exposure Assessment for 1,3-Butadiene.  U.S.
    Environmental Protection Agency.   Office of Toxic Substances.
    Washington, DC.  1984.
6/88          -                ROAD VEHICLES                          4-16

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                 REFERENCES
11.  Carey,  R.N.   Mobile Source Emissions of Formaldehyde and Other
    Aldehydes.   EPA/AA/CTAB/PA-81-11.   U.S. Environmental Protection
    Agency.   Ann Arbor, MI.  1981.

12.  U.S.  Environmental  Protection Agency.  Evaluation of Air Pollution
    Regulatory  Strategies for Gasoline Marketing Industry.   Office of Air
    and Radiation.   Washington, DC.   1984.

13.  Sigsby,  Drabkin,  Bradaw, and Lank.  "Automotive Emissions of Ethylene
    Dibromide".   Society of Automotive Engines.   Warrenton, PA.  1982.
6/88         -                ROAD VEHICLES                          4-17

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                  PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
5.       AIRCRAFT

5.1    General

    Aircraft exhaust contains an assortment of toxic compounds,  including
formaldehyde, benzene, metals, and semivolatiles.  Ambient monitoring  in
areas adjacent to large municipal and military airports indicate that
these levels may at times be significant.  Unfortunately, little data  are
available on which to base emission factors, since emissions vary
according to engine type, landing and takeoff patterns, etc.  At this
time, VOC speciation factors are the only factors available to predict
aircraft exhaust emissions  on an  area-wide basis.  While data are
available on levels of other  pollutants emitted by planes, the information
was inadequate to develop factors representative of all aircraft.
5.2    Factors

    Emission factors are available for total hydrocarbons  (HC) and
particulates.  An approach for estimating criteria pollutant emissions  is
presented below.  The methodology described in detail  in AP-42, Volume
II ,  and used in NEDS to estimate criteria pollutant emissions can  be
used in combination  with  speciation factors provided in Air Emissions Species
Manual2 to estimate  emissions of air toxics.  These data may be used to  apportion
VOCs  and particulates based on activities at the airport such as takeoffs
and landings and are provided in Tables 5-1, 5-2 and 5-3.

5.3    Methodology Options

    NEDS uses the AP-42  methodology to estimate LTO's  and  emissions of
criteria pollutants, including total hydrocarbons for  commercial,  civil,
and military aircraft.    In that methodology emissions  of criteria

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                    PROCEDURES FOR ESTIMATING AND ALLOCATING
                      AREA  SOURCE EMISSIONS  OF  AIR TOXICS
                          Table 5-1 Military Aircraft
Species Name
Isomers of Dodecane
Isomers of Tetradecane
Isomers of Pentadecane
Isomers of Pentene
C16 Branched Alkane
C7-C16
Methane
Ethane
Ethylene
Propane
Propene
Acetylene
Butene
cis-2-Butene
1 ,3-Butadiene
N-Pentane
1-Pentene
2-Methyl-2-Butene
Metnylpentane
Heptane
Octane
Nonane
N-Decane
N-Undecane
1-Hexene
N-Dodecane
N-Tndecane
N-Tetradecane
N-Pentadecane
Heptene
Octene
1-Nonene
Formaldehyde
Acetaldehyde
Propionaldehyde
Acrolein
Butyraldehyde
Hexanal
Glyoxal
Methyl Gloxal
Percent Weight
0.19
0.20
0.18
0.76
0.16
0.32
9.37
0.91
18.36
0.19
5.44
4.41
2.06
0.50
1.89
0.22
0.89
0.21
-0.41
0.07
0.05
0.13
0.44
0.54
0.86
1.07
0.67
0.59
0.26
0.54
0.30
0.26
15.47
4.83
0.98
2.38
1.24
0.22
2.18
2.06
6/88          --                    AIRCRAFT
                                                                         5-2

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                     PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                        AREA  SOURCE EMISSIONS OF  AIR TOXICS
                                    Table 5-1 (Continued)
              Species Name                             Percent Weight
           Crotonaldehyde                                   0.00
           Acetone                                          2.41
           Benzene                                          2.02
           Toluene                                          0.55
           Ethylbenzene                                     0.18
           0-Xylene                                         0.20
           Styrene                                          0.41
           Pentyl Benzene                                   0.21
           Butyl Benzene                                    0.26
           Phenol                                           0.26
           Benzaldehyde               '                      0.57
           Napthalene                                       0.60
           Methyl Naphthalenes                              0.52
           M-Xylene and P-Xylene                            0.30
           1-Oecene                                         0.17
           C6H1803SI3                                       6.96
           C8H2404SI4                                       2.37
           Hexadecane                                       0.12
           N-Heptadecane                                    0.01
           Note:   Composite profile developed from data .for CFM-36  jet engine fired
                  with JP-5 fuel  at idle, 30% thrust and 80% thrust.  Data
                  collected by  GC/MS and DNPH analyses were combined according to
                  average LTO cycle times obtained from AP-42 (4th. Edition) for
                  military aircraft

           Source:  Reference 2
6/88             "-                        AIRCRAFT                                     5-3

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                 PROCEDURES FOR ESTIMATING AND  ALLOCATING
                    AREA SOURCE  EMISSIONS OF AIR TOXICS
                           Table 5-2 Civil Aircraft
Species Name
Isomers of Dodecane
Isomers of Tetradecane
Isomers of Pentadecane
Isomers of Pentene
C16 Branched Alkane
C7-C16
Methane
Ethane
Ethylene
Propane
Propene
Acetylene
Butene
cis-2-Butene
1,3-Butadiene
N-Pentane
1-Pentene
2-Methyl-2-Butene
Methyl pen tane
Heptane
Octane
Nonane
N-Decane
N-Undecane
1 -Hexene
N-Dodecane
N-Tridecane
N-Tetradecane
N-Pentadecane
Heptene
Octene
1-Nonene
Formaldehyde
Acetaldehyde
Propionaldehyde
Acrolein
Butyraldehyde
Hexanal
Glyoxal
Methyl Gloxal
Percent Weight
0.16
0.17
0.15
0.64
0.13
0.27
10.95
0.92
15.48
0.20
4.59
3.69
1.79
0.45
1.57
0.19
0.75
0.18
0.35
0.06
0.04
0.15
0.42
0.52
0.76
1.21
0.66
0.59
0.27
0.52
0.25
0.22
14.14
4.32
0.90
2.06
1.19
0.20
2.53
1.81
6/88                              AIRCRAFT                              5"4

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                       PROCEDURES FOR ESTIMATING  AND  ALLOCATING
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                                     Table 5-2  (Continued)
               Species Name                             Percent Weight
            Crotonaldehyde                                   0.00
            Acetone                                          2.93
            Benzene                                        •  1.79
            Toluene                                          0.49
            Ethylbenzene                                     0.13
            0-Xylene                                         0.19
            Styrene                                          0.37
            Pentyl Benzene                                   0.17
            Butyl Benzene                                    0.22
            Phenol                                           0.22
            Benzaldehyde                                     0.53
            Napthalene                                       0.51
            Methyl Naphthalenes                               0.44
            M-Xylene and P-Xylene                             0.25
            1-Oecene                                         0.15
            C6H1803SI3                                      11.77
            C8H2404SI4                                       4.20
            Hexadecane                                       0.14
            N-Heptadecane                                    0.01
            Note:    Composite  profile developed from data for CFM-36 jet engine
                    fired with JP-5 fuel at idle. 30% thrust  and 80% thrust.   Data
                    collected  by GC/MS and DNPH analyses were combined according to
                    average LTD cycle times obtained from AP-42 (4th. Edition) for
                    general aviation.

            Source:  Reference  2
                                                                                          5-5
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                   PROCEDURES FOR  ESTIMATING AND ALLOCATING
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                           Table 5-3 Commercial Aircraft
Species Name
Isomers of Dodecane
Isomers of Tetradecane
Isomers of Pentadecane
Isomers of Pentene
C16 Branched Alkane
C7-C16
Methane
Ethane
Ethylene
Propane
Propene
Acetylene
Butene
cis-2-Butene
1 ,3-Butadiene
N-Pentane
1-Pentene
2-Methyl-2-Butene
Methylpentane
Heptane
Octane
Nonane
N-Oecane
N-Undecane
1-Hexene
N-Dodecane
N-Tndecane
N-Tetradecane
N-Pentadecane
Heptene
Octene
1-Nonene •
Forma Idehyde
Aceta Idehyde
Prop lona Idehyde
Acrolein
Butyra Idehyde
Hexana 1
Glyoxal
Methyl Gloxal
Percent Weight
*•
0.18
0.19
0.17
0.73
0.14
0.30
9.56
0.88
17.42
0.18
5.15
4.17-
1.97
0.48
1.80
0.21
0.84
0.20
0.39
0.06
0.05
0.13
0.42
0.53
0.82
1.07
0.66
0.58
0.26
0.54
0.28
0.24
15.00
4.65
0.95
2.27
1.20
0.21
2.54
1.97
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                    PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                       AREA SOURCE EMISSIONS OF  AIR TOXICS
                                   Table 5-3 (Continued)
            Species  Name                              Percent Weight
         Crotonaldehyde                                   0.00
         Acetone                                         2.45
         Benzene                                         1.94
         Toluene                                         0.52
         Ethylbenzene                                     0.17
         0-Xylene                                        0.19
         Styrene                                         0.39
         Pentyl Benzene                                   0.19
         Butyl Benzene                                    0.24
         Phenol                                          0.24
         Benzaldehyde                                     0.55
         Napthalene                                      0.57
         Methyl Naphthalenes                              0.49
         M-Xylene and P-Xylene                            0.29
         1-Decene                                        0.17
         C6H1803SI3                                      9.10
         CbH2404SI4                        '              2.92
         Hexadecane                                      0.12
         N-Heptadecane                                    0.01
         Note:    Composite profile developed from data for CFM-36 jet  engine
                  fired with JP-5 fuel  at  idle,  30'7. thrust and 80% thrust.  Data
                  collected by GC/MS and ONPH analyses were combined according to
                  average LTD cycle times  obtained from AP-42 (4th.  Edition) for
                  commercial aircraft.

         Source:   Reference 2
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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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pollutants are estimated based on aircraft takeoffs and landings.  The
general approach is to first estimate the number of landing and takeoff
(LTO) cycles per aircraft type for a specified period of time at each
airport facility.  An LTO cycle incorporates all of the normal flight and
around operation modes (at their respective times-in-mode), including
descent/approach from approximately 3000 feet (915 meters) above ground
level(AGL), touchdown, landing run, taxi in, idle and shutdown, startup
and idle, checkout, taxi out, takeoff, and climbout to 3000 feet (915
meters) AGL.  It is during this cycle that most compound emissions that
affect the subsequent ground-level concentrations of concern are
released.  The LTO estimates are multiplied by aircraft and specific
emission factors, and the results are summed to provide an estimate of
particulate and organic compound emissions for the inventory period and
location of interest.

    Alternative, more labor  intensive, approaches are available to
estimate LTOs.  One possible approach, for example, is to obtain
information directly from each airport.  Airports often have detailed
information on their operations that can be very helpful.

5.4    Example Calculation

Example Calculation

    The example below demonstrates a methodology for estimating total
annual airport emissions of  three pollutants:  1,3 butadiene,
formaldehyde, and benzene.

Step 1.  Obtain VOC Data.

    The emission factors are given by percentage of VOC for three types
of aircraft:  military, civil, and commercial.  NEDS gives estimates of
countywide VOC estimates for these aircraft categories.  Data for a
hypothetical county is given below.

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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    Aircraft Type                   VOC Emissions (kkq/vr)
    Military                                 384
    Civil                                      40
    Commercial               ,.              1,357


Step 2.   Multiply VOC estimates by pollutant specific emission factors.


    Table 5-1,  5-2,  and 5-3 provide speciation factors for the three

compounds.  The emissions of three pollutants of concern -(1,3 butadene,

formaldehyde, and benzene) are calculated as follows.


Military
    1,3 butadene:  384 Metric tons x 0.0189 = 7.3 Metric tons/yr
                      year

    formaldehyde:   384 Metric tons x 0.1547 = 59.40 Metric tons/yr
                       year

    benzene:  384  Metric tons x 0.0202 -  7.75 Metric tons/yr
                  year
Civil
    1,3 butadene:   40 Metric tons x 0.0157 = 0.6 Metric tons/yr
                      year

    formaldehyde:   40 Metric tons x 0.1414 = 5.7 Metric tons/yr
                       year

    benzene:  40 Metric tons x 0.0179 = 0.7 Metric tons/yr
                  year
Commercial
    1,3 butadene:  1.357 Metric tons x 0.0180 = 24.4 Metric tons/yr
                         year

    formaldehyde:  1.357 Metric tons x 0.1500 = 203.6 Metric tons/yr
                         year

    benzene:   1.357 Metric tons x 0.0194 = 26.3 Metric tons/yr
                  year
6/88         .                   AIRCRAFT                            5"9

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
5.5    Methods to Apportion Countvwide Emissions from Aircraft

    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
emissions.  Similarly temporal in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect ongoing activities in that portion of
the county, e.g., residential heating in the winter, commercial solvent
usage during working hours of weekdays.

    In apportioning emissions from aircraft the U.S. Geological Survey
and other sources can be used in combination with the spatial resolution
for aircraft, to distribute emissions based on the type of activity being
performed, as shown in Table 5-4.

    The best approach for estimating spatial distribution is to identify
airports on U.S. Geological Survey land use maps, contacting local
airport authorities, and surveying U.S. Department of Transportation data
on airport activities, as noted in Table 5-4.  Spatial, temporal
variations on activity and emissions tend to be unique for each airport;
airport authorities usually have detailed information on variations in
activity.
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                        PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                           AREA  SOURCE EMISSIONS  OF AIR  TOXICS
                                           Table  5-4
                          Spatial  and  Temporal Resolution for  Aircraft
           Aircraft,  General0

           Spatial Resolution
               Surrogate indicator:
               Information  source(s)1
           Temporal Resolution
               Seasonal:
               Daily:
               Hourly:
airport area  (code 14)
land use map,  local airport
authority,  and Reference 4
uniform through the year
40 percent  of operations occur on
weekends
and 60 percent on weekdays
uniform from 0700 to 2100, otherwise
zero
           Aircraft,  Commercial

           Spatial Resolution
               Surrogate  indicator:
               Information  source(s):
           Temporal Resolution
               Seasonal,  daily, and
               hourly:
airport area  by airport (code 14)
land use map,  local airport
authority,  and References 5 and 6
Since the temporal profiles of
commercial  airports vary widely,  the
respective  airport managers should be
contacted.   The airport managers
usually have very detailed temporal
information.
           Aircraft,  Military

           Spatial Resolution
               Surrogate indicator:
               Information  source(s):
           Temporal Resolution
               Seasonal,  daily, and
               hourly:
airport area  (code 14)
land use map,  local airport
authority,  and Reference 7
Estimate on  individual basis.   Contact
local  airport authorities and
appropriate  military agencies.
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                   PROCEDURES FOR ESTIMATING AND ALLOCATING
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                               REFERENCES
 1.  Compilation of Air Pollutant Emission Factors, Volume II:  Mobile
    Sources  (AP-42), Fourth Edition, Office of Mobile Sources, U. S.
    Environmental Protection Agency, Ann Arbor, MI, 1985.

 2.  Air Emissions Species Manual, EPA-450/2-88-003a and b, Office of Air
    Quality  Planning and Standards, U. S. Environmental Protection
    Agency,  Research Triangle Park, NC, April 1988.

 3.  Procedures for the Preparation of Emission Inventories for Volatile
    Ozone Compounds. Volume II;  Emission Inventory Requirements for
    Photochemical Air Quality Simulation Models.EPA-450/4-79-018,
    Office of Air Quality Planning and Standards, U. S. Environmental
    Protection Agency, Research Triangle Park, NC, September 1979.

 4.  Census of U. S. Civil Aircraft, U. S. Department of Transportation,
    Federal  Aviation Administration, Washington, DC.  Annual.

 5.  FAA Air  Traffic Activity Reports, U. S. Department of Transportation,
    Federal  Aviation Administration, Washington, DC.  Annual.

 6.  Aircraft Activity Statistics for Certified Route Air Carriers, U.  S.
    Department of Transportation, Federal Aviation Administration,
    Washington, DC.  Annual.

 7.  Military Air Taffic Report, U. S. Department of Transportation,
    Federal  Aviation Administration, Washington, DC.  Annual.
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                  PROCEDURES  FOR. ESTIMATING AND ALLOCATING
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6.      COMFORT AND INDUSTRIAL COOLING TOWERS

6.1    General1

    Chromium, in the form of chromates, is commonly added to cooling
tower water as a corrosion inhibitor.  Water droplets and the dissolved
solids, including chromates, that they contain are entrained in the air
and are emitted from the cooling tower stack.  Because this cooling tower
"drift" will also presumably contain chromates, it follows that cooling
towers are potentially an important source of hexavalent chromium air
emissions.

    There are two types of cooling towers, comfort and industrial.
Comfort cooling towers are used to maintain a specified environment or
refrigeration system.  Industrial process cooling towers are used to
control the temperatures of process fluids in industrial production units.

    Chromium emission rates vary depending on the type of cooling tower.
It is estimated that national baseline emissions of hexavalent chromium
from comfort cooling towers are between 7.2 and 206 metric tons annually,
and national baseline emissions from industrial cooling towers (for the
four major industries that make up the majority of industrial towers) are
795 metric tons per year.

    Warm water is cooled by cooling towers when it contacts ambient air
that is drawn or forced through the tower.  For most cooling towers,
about 80 percent of the cooling occurs through evaporation of water, as
the air flowing through the tower contacts the water flowing from the top
to the bottom of the tower.  Most tower systems are designed with
recirculating water systems to conserve water resources or reduce the
cost of purchasing water.  The major cooling tower components are the
fan(s), fill material, water distribution deck or header, drift

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                  PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
eliminator, structural  frame,  and cold water basin.   Other components
that affect tower operation include the pumps and pipes necessary to
circulate the cooling water through the tower and heat exchanger loops.

    Cooling towers are designed with mechanically induced-, mechanically
forced-, or natural-draft airflow.   Induced-draft airflow is provided by
a propeller-type fan located in the stack at the top of the tower.
Forced-draft towers are usually smaller than induced-draft towers and
have either centrifugal fans located at the base of the tower or axial
fans located on the side of the tower.  Natural-draft airflow relies on
the buoyancy created by differences in temperature between the air in the
tower and the atmosphere.  When the cooling demands are minimal and the
air temperature is low enough,  water can be circulated through the tower
and can be cooled sufficiently without using the fans.  In these
instances, a natural draft is created in a mechanical draft tower.  The
direction of airflow in a mechanical-draft tower is either crossflow or
counterflow.  Crossflow refers to horizontal airflow through the fill;
counterflow refers to upward vertical airflow.

    Drift eliminators can be installed at the exit of the fill sections
to reduce the drift in the exiting airflow.  The drift removal efficiency
is a function of the drift eliminator design, of which there are four
major types:  blade-type, waveform, cellular, and herringbone.
(Herringbone is similar to blade-type, but the blades in one row are
offset from the blades in the next row.)  Typically, herringbone and
blade-type units are the least efficient, waveform units are moderately
efficient, and cellular units are the most efficient.  Drift eliminators
are constructed of wood, PVC, metal, asbestos-cement, polystyrene, or
cellulose.

    Comfort cooling towers.   Comfort cooling towers are used in all
states in the U.S., primarily in urban areas.  Major users of comfort
cooling towers with heating, ventilating, and air conditioning (HVAC)
systems include hospitals, hotels, educational facilities, office
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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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buildings, and shopping malls.  Refrigeration systems that may operate
with comfort cooling towers include ice skating rinks, cold storage
(food) warehouses, and other commercial operations.  Estimates from the
two largest manufacturers of cooling towers indicate that the nationwide
                                                                    2 3
population of comfort cooling towers is between 200,000 and 300,000. '

    Water treatment vendors estimated that 10 to 25 percent of comfort
cooling towers use chromium-based water treatment chemicals.   '    For
analysis purposes, it is assumed that the nationwide population of
comfort cooling towers is 250,000 units and that 15 percent of them
(about 37,500) use chromium-based water treatment chemicals.  Hexavalent
chromium use in comfort cooling towers appears to be distributed randomly
across the country.

    Typically, comfort cooling towers are open recirculating systems with
either forced- or induced-draft airflow (natural-draft airflow is not
used for comfort cooling towers) and are designed with crossflow air
direction.

    Industrial cooling towers.   The industrial cooling tower category
includes all cooling towers that are used to remove heat from an
industrial process or chemical reaction.  Towers that are used to cool
both industrial processes and HVAC and refrigeration systems are also
included in this category.  Only towers devoted exclusively to cooling
HVAC and refrigeration systems are defined as comfort cooling towers.

    Major users of industrial cooling towers are chemical manufacturing,
petroleum refining, primary metals, and numerous miscellaneous
industries.  The industries in the U.S. using chromium-based water
treatment chemicals include approximately 190 petroleum refineries,
1,800 chemical manufacturing plants, 1,000 primary metals plants
(including 775 foundries), and 750 plants in five miscellaneous
industries (textiles, tobacco products, tire and rubber products, glass
6/88         -    COMFORT AND INDUSTRIAL COOLING TOWERS              6-3

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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products, and utilities).  It was assumed that chromates are not used in
miscellaneous industries other than the five referred to above.
Approximately 8,800 industrial cooling towers are estimated to be
operating in all eight industries.  It is further estimated that the
percentage of towers using chromium-based chemicals is 73 percent at
petroleum refineries, 40 percent at chemical manufacturing plants, 21
percent at primary metals facilities, and 15 percent in the miscellaneous
industries, except for utilities where only two are reported to use
chromates.  These percentages result in a total of about 2,800 industrial
cooling towers using chromium-based water treatment chemicals.

    In a typical industrial cooling system, cooling water is pumped from
the cooling tower basin to the heat exchanger(s) being served by the
tower, and the heated water flows back to the cooling tower water
distribution system.  The cooling water loop may include numerous
separate heat exchangers of various designs.  Heat exchangers are
designed to transfer heat from one fluid to another.  The transfer can
occur directly by mixing the hot and cold materials or indirectly through
a device separating the hot and cold materials.  Indirect heat exchanger
types include shell-and-tube, flat plate, and spiral designs.  In most
industries, heat transfer is accomplished with shell-and-tube heat
exchangers. '

6.2    Factors

    Comfort cooling towers.   Chromium emission factors have been
developed based on EPA-sponsored tests performed on industrial cooling
towers equipped with lower efficiency drift eliminators, which are
similar to comfort cooling towers.  These emission factors relate
chromium emissions to the chromium concentration in the recirculation
water.  Data on chromate concentrations in comfort cooling tower water
indicate that concentrations vary from less than 1 ppm to 20 ppm
         8910
chromate.  ''    Although a large amount of data has
6/88         .    COMFORT AND INDUSTRIAL COOLING TOWERS              6-4

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
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shown that the average concentration of chromate in industrial process
cooling towers is 13 ppm, there are insufficient data on comfort cooling
towers to justify using a concentration other than the midpoint of the
               11-19
observed range.       Therefore, the chromate <
to be 10 ppm, or 4.48 ppm hexavalent chromium.
               11-19
observed range.       Therefore, the chromate concentration is assumed
    The lowest emission factor is-thought to underestimate emissions
because some of the hexavalent chromium in the samples was retained on
the walls of the beakers used to concentrate the samples.  Errors are
not, expected to account for most of the difference between the lowest
and highest emission factors, however.  The wide differences among
emission factors indicate that emissions may vary substantially with time
for an individual tower as'well as from tower to tower.

    The above results were used to develop emission factors on a per
capita basis.  The total number of comfort cooling towers was apportioned
(by size groups) by state based on state population.  The chromium
emissions for individual towers in each state are dependent on the
utilization rate for the state.  The utilization rate is the percentage
of the number of days that the tower operates annually.  The utilization
rate depends on the climate at the cooling tower site.  It was assumed
(as a rough approximation) that the tower is not used on days when the
average temperature is below 60ฐF

    The annual chromium emissions from individual towers in each state
were estimated by calculating annual emissions based on the factors cited
above.  The estimated individual  emission rates for the six tower sizes
in each state were then multiplied by the respective number of comfort
cooling towers of that size in the state to obtain the statewide chromium
emission.  The average emission rate per person for each state was
estimated by dividing the total chromium emission rate for the state by
the population of the state.  The resulting emission factors are provided
6/88          -    COMFORT AND INDUSTRIAL COOLING TOWERS              6-5

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
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in Table 6-1.  The factors are presented as ranges because they were
calculated from the highest and lowest emission factors from the
EPA-sponsored study.   Therefore,  the lower value carries the same -
uncertainty as the Agency's lowest emission factor because of the problem
of the chromium retention in the beaker during the test.

    Industrial cooling towers.   An estimated national average emission
factor for chromium releases from industrial cooling towers was
determined based on four industries:  petroleum refining, chemical
manufacturing, primary metals, and miscellaneous industries (including
the textiles, tire and rubber, tobacco, glass manufacturing, and
utilities industries), as well as four different sizes of cooling towers
in each industry.

    Data compiled from the petroleum refinery industry indicate that the
average chromate concentration in industrial cooling towers is
approximately 13 ppm.  Data from the Chemical Manufacturers Association
also indicate an average of 13 ppm chromate in the chemical manufacturing
industry.  (These two categories account for the majority of the
industrial cooling towers.)   In the absence of data for other industries,
13 ppm chromates was assumed  for all industry categories.  Thirteen ppm
chromates translates into 5.82 ppm hexavalent chromium.

    A chromium emission factor was developed from EPA-sponsored tests
performed on  industrial cooling towers equipped with low efficiency drift
eliminators.  The emission factor relates chromium emissions to
recirculation rate and chromium concentration in the water.  Testing was
done for crossflow towers, the most common type of comfort cooling tower
in use.  Information from a cooling tower vendor indicates that crossflow
towers are more likely to have higher drift rates than the other  type of
tower, counterflow towers, because crossflow towers have higher
velocities at the outlet.
6/88          -.    COMFORT AND INDUSTRIAL COOLING TOWERS              6-6

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                    PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                       AREA  SOURCE EMISSIONS  OF AIR TOXICS
                          Table 6-1 Lower- and Upper-Bound Estimates of
                            Annual Cr  Emissions Per Person By State
State
Alabama
Alaska3
Arizona
Arkansas
Cal ifornia
Colorado
Connecticut
Delaware
Florida
Georgia
Hawa i i
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Uti lization
(percent)
59
0
55
56
54
29
33
33
89
59
100
21
42
42
38
42
42
65
21
46
33
33
29
59
42
Hexavalent Chromium
Emissions
(kg/yr
per person)
4.13E-05-1.17E-03
O.OOE+00-O.OOE+OO
3.85E-05-1.09E-03
3.92E-05-1.11E-03
3.78E-05-1.07E-03
2.03E-05-5.76E-04
2.31E-05-6.56E-04
2.31E-05-6.56E-04
6.23E-05-1.77E-03
4.13E-05-1.17E-03
7.QOE-05-1.99E-03
1.47E-05-4.17E-04
2.94E-05-8.35E-04
2.94E-05-8.35E-04
2.66E-05-7.55E-04
2.94E-05-8.35E-04
2.94E-05-8.35E-04
4.55E-05-1.29E-03
1.47E-05-4.17E-04
3.22E-05-9.14E-04
2.31E-05-6.56E-04
2.31E-05-6.56E-04
2.03E-05-5.76E-04
4.13E-05-1.17E-03
2.94E-05-8.35E-04
Hexavalent Chromium
Emissions
(Ib/yr
per person)
9.11E-05-2.59E-03
0-OOE+OO-O.OOE+OO
8.49E-05-2.41E-03
8.64E-05-2.45E-03
8.33E-05-2.37E-03
4.48E-05-1.27E-Q3
5.09E-05-1.45E-03
5.09E-05-1.45E-03
1.37E-05-3.90E-03
9.11E-05-2.59E-03
1.54E-04-4.38E-Q3
3.24E-05-9.20E-04
6.48E-05-1.84E-03
6.48E-05-1.84E-03
5.86E-05-1.67E-03
6.48E-05-1.67E-03
6.48E-05-1.84E-03
1.00E-04-2.85E-03
3.24E-05-9.20E-04
7.10E-05-2.02E-03
5.09E-05-1.45E-03
5.09E-05-1.45E-03
4.48E-05-1.27E-Q3
9.11E-05-2.59E-03
6.48E-05-1.84E-03
          Alaska .was  assumed to have no comfort cooling towers because,  on average, there
         are no days  when the main temperature exceeds 60ฐF.
6/88
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                  PROCEDURES FOR ESTIMATING AND ALLOCATING
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                                Table 6-1 (Continued)
State
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carol ina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Washington, D.C.
Uti 1 ization
(percent)
25
42
39
27
42
39
33
53
25
39
54
23
39
33
59
33
50
63
31
25
42
20
42
31
25
50
Hexavalent Chromium
Emissions
(kg/yr
per person)
1.75E-05-4.97E-04
2.66E-05-7.55E-04
2.73E-05-7.75E-04
1.89E-05-5.37E-04
2.94E-05-8.35E-04
2 73E-05-7.75E-04
2.31E-05-6.56E-04
3.71E-05-1.05E-03
1.75E-Q5-4.97E-04
2.73E-05-7.75E-04
3.78E-05-1.07E-03
1.61E-05-4.57E-04
2.73E-05-7.75E-04
2.31E-05-6.56E-04
4 13E-05-1.17E-03
2.31E-05-6.56E-04
3.50E-05-9.94E-04
4.41E-05-1.25E-03
2.17E-05-6.16E-04
1.75E-05-4.97E-04
2.94E-05-8.35E-04
1.40E-05-3.98E-04
2.94E-05-8.35E-04
2.17E-05-6.16E-04
1.75E-05-4.97E-04
3.50E-05-9.95E-04
Hexavalent Chromium
Emissions
(Ib/yr
per person)
3.86E-05-1.10E-03
5.86E-05-1.67E-03
6.02E-05-1.71E-03
4.17E-05-1.18E-03
6.48E-05-1.84E-03
6.02E-05-1.71E-03
5.09E-05-1.45E-03
8.18E-05-2.32E-03
3.86E-05-1.10E-Q3
6.02E-05-1.71E-03
8.33E-05-2.37E-03
3.55E-05-1.01E-03
6.02E-05-1.71E-03
5.09E-05-1.45E-03
9.11E-05-2.59E-03
5.09E-05-1.45E-03
7.72E-05-2.19E-03
'9.72E-05-2.76E-03
4.78E-05-1.36E-03
2.86E-05-1.10E-03
6.48E-05-1.84E-03
3.09E-05-8.76E-04
6.48E-05-1.84E-03
4.78E-05-1.36E-03
3.86E-05-1.10E-03
7.72E-05-2.19E-03
         Source:  Reference 1

6/88               COMFORT AND  INDUSTRIAL COOLING  TOWERS
6-8

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Table 6-2 lists the emission factors for counterflow, crossflow, and the
national  average baseline.  The emissions are given as amount of
hexavalent chromium emitted per hexavalent chromium concentration in the
cooling water.  Hexavalent chromium emissions can be estimated by
multiplying the emission factor by the concentration of chromium and the
recirculation rate.

    Emission factors have also been calculated to relate hexavalent
chromium emissions to the number of employees in the study area for the
industries that contribute the most to industrial cooling tower
emissions.  The Background Information Document for Industrial Cooling
Towers  contains data on national emissions of hexavalent chromium for
the petroleum refining, chemical manufacturing, primary metals, textile
finishing, tobacco, tire and rubber, and glass manufacturing industries
as well as for utilities.

                            20
    County Business Patterns   was used to determine the number of
employees nationally for each of the SIC codes listed in Table 6-3.  The
number of employees (by SIC code) was summed for each industry.  The
national  hexavalent chromium emission for that industry was then divided
by the national number of employees for that industry, giving the
emission factor as kg/yr/employee (Ib/yr/employee).  Table 6-4 presents
these emission factors.

6.3      Methodology Options

    Comfort Cooling Towers.  To estimate area source emissions of
hexavalent chromium from comfort cooling towers, the following steps are
recommended:
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                   PROCEDURES  FOR  ESTIMATING AND ALLOCATING

                      AREA SOURCE  EMISSIONS  OF AIR TOXICS
                        Table 6-2 Industrial  Cooling Tower Emission Factors
                                       Emission factor
                 +6      +6                                   +6      +6
            mg Cr  /ppm Cr  /I  HO                          Ib Cr  /ppm Cr  /gal  HO
             0.0003                                                2.49 x 10"9
        Source:  Reference 2.
                 Table 6-3 SIC Codes  Included in  Industry-Specific Emission Factors
                       Industry                    SIC Codes
                   Petroleum Refining           291


                   Chemical Manufacturing       281,  282, 286,  287


                   Primary Metals               331,332,333


                   Textile Finishing            223,  226


                   Tobacco                     211,  212, 213


                   Tire and Rubber              301,  302, 304,  306


                   Glass Manufacturing          321,  322


                   Utilities                   491
        Source:  Reference 7.
6/88           .      COMFORT AND  INDUSTRIAL COOLING TOWERS                  6"10

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                      PROCEDURES FOR ESTIMATING  AND  ALLOCATING
                         AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
                   Table 6-4 Industrial Cooling Tower Hexavalent Chromium
                              Employee-Based Emission Factors
                   Industry
                                     Emission factor

                             kg/yr/employee    Ib/yr/employee
            Petroleum Refining

            Chemical Manufacturing

            Primary Metals

            Textile Finishing

            Tobacco

            Tire  and Rubber

            Glass Manufacturing

            Utilities
                                0.35

                                0.19

                                0.02

                                0.09

                                0.018

                                0.0037

                                0.005

                                0.002
0.75

0.42

0.045

0.20

0.044

0.008

0.011

0.005
6/88
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              6-11

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
    •     Determine the population of the study area.   This information
          can be obtained from population reports published by the U.S.
          Department of Commerce,  Bureau of the Census.

    •     Multiply the emission factor for the state in which the study
          area lies by the population of the study area to give an
          estimate of the study-wide area emission of hexavalent chromium
          from comfort cooling towers.

    Industrial cooling towers.  The easiest method for estimating area
source emissions of hexavalent chromium is to determine the number of
employees in industries likely to  use hexavalent chromium in cooling
towers,  and to apply the emission  factors in Table 6-5,  as follows:

    •     Determine, for each industry listed in Table 6-5, the number of
          employees in the study area.   This information is available
                                        21
          from County Business Patterns.   which
          employees for each SIC code by county.
                              21
from County Business Patterns.    which gives the number of
    •     For each industry,  multiply the emission factor by the number
          of employees in the study area to give an estimate of the area
          source emissions for that industry.

    •     Sum the emissions over all  industries in the study area to
          obtain an estimate of the total area source emissions of
          hexavalent chromium from industrial  cooling towers in the study
          area.

    Alternately, area source emissions of hexavalent chromium from
industrial cooling towers can be estimated using the following approach:
6/88          -    COMFORT AND INDUSTRIAL COOLING TOWERS              6-12

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
          Determine,  by surveying the facilities in the study area, which
          facilities  have cooling towers that use chromate-based water
          treatment,  and what the annual recirculation rate is for each
          of the towers under consideration.

          Sum the recirculation rates to determine the total
          recirculation rate of chromium-containing cooling water in the
          study area.

          Multiply the national average baseline emission factor by the
          concentration of hexavalent chromium (assumed to be 4.48 ppm)
          and by the  total recirculation rate in the study area to give
          an estimation of the study-wide area emission of hexavalent
          chromium by industrial  cooling towers.
6.4    Example Calculations

Example Calculation 1

    Hexavalent chromium emissions can be calculated on a per capita basis
as shown in the following example.

    The emission is calculated on a per capita basis.   Assuming the study
area is in Alabama and the study area population is 150,000, the per
capita emission factor for Alabama from Table 6-1 is multiplied by the
study area population of 150,000:

           1.17  x  1    kg/yr/person  x  150,000  people  =  175.5  kg/yr
           2.59  x  10    Ib/yr/person x  150,000  people =  388.5  Ib/yr.
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                  PROCEDURES  FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
Example Calculation 2


    A method for estimating hexavalent chromium emissions from industrial
cooling towers is demonstrated in the following example.


    One can assume that there are 15 industrial cooling towers in a study

area-that use chromates for corrosion control  and that summing the

recirculation rate for all  15 of these towers  yields a total

recirculation rate of 6.8 x 10  1/hr (1.8 x 107 gal/hr).  Multiplying

this value by the national  average baseline emission factor will  give the
emission of hexavalent chromium from industrial cooling towers in the
study area:


(6.8 x 107 1/hr) x (4.48 ppm) x (0.0016 mg Cr/ppm Cr/1 H20) = 4.88 x 105 mg/hr

(1.8 x 107 gal/hr) x (4.48 ppm) x (1.33xlO~8 IbCr/ppm Cr/gal  H20) = 1.07 Ib/hr.


     Alternatively, the emissions can be calculated based on number of employees f

the major industries in the study area.  Assuming the study area is Allegheny

County, Pennsylvania, the number of employees  by SIC code can be determined from
County Business Patterns (Pennsylvania).    The number of employees for Allegheny
County for each SIC Code of concern is as follows:
     Industry

Petroleum Refining
            SIC Code

              291
            Total
 No. of
 employees
Chemical Manufacturing
              281
              282
              286
              287
            Total
    468
  1,679
250-499 (assume average of 375)
 	0
  2,522
Primary Metals
              331
              332
              333
            Total
  38,68
  2,622
 	0
 41,311
6/88
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                  6-14

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                  PROCEDURES  FOR ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                      No. of
     Industry

Textile Finishing
            SIC Code

              223
              226
            Total
      employees

           0
      	0
Tobacco
Tire and Rubber
Glass Manufacturing
              211
              212
              213
            Total

              301
              302
              304
              306
            Total

              321
              322
            Total
           0
           0
           0
           0
           0
           0
       20-99 (assume average of 60)
          60

           0
         877
                                                       877
Utilities
              491
            Total
     250-499 (assume average of 375)
         375
     The next step is to multiply the emission factor for each industry by
the total number of employees for that industry
      Industry

Petroleum Refining
Chemical Manufacturing
Primary Metals
Textile Finishing
Tobacco
Tire and Rubber
Glass Manufacturing
Utilities
        Emission factor
        (Ib/yr/employee)

                4.03
                2.27
                0.24
                1.06
                0.21
                0.044
                0.06
                0.029
No. of employees
            Emissions Cr-6
                flb/yr)
       2
      41
   0
,522
,311
   0
   0
  60
 877
 375
   0
,725
,915
   0
   0
   3
  53
  11
6/88
COMFORT AND INDUSTRIAL COOLING TOWERS
                       6-15

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Finally, summing the chromium emissions over all the industries will
givean estimate of the hexavalent chromium emissions from industrial
cooling towers in the study area:

                5,725 + 9,915 + 3 + 53 + 11 = 15,707 Ib/yr.

6.5    Methods to Apportion Countywide Emissions from Cooling Towers

    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
emissions.  Similarly temporal in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect on-going activities in that portion
of the county, e.g., residential heating in the winter, commercial
solvent usage during working hours on weekdays.

    There are three alternative approaches that can be used in spatially
distributing emission:  (1) population, i.e., the magnitude of emissions
within a grid are directly proportional to the population living  in the
grid,  (2) land area, i.e., emissions from a countywide area source  are
assumed to be uniform throughout the county and are distributed based on
the size of the area source grid, and  (3) landuse patterns, that  assume
that certain area source activities, most likely occur in certain areas
of the county, e.g., commercial, residential or industrial.

    In apportioning emissions from comfort and industrial cooling towers,
any of these methods may be appropriate.  Land area and population  data
can be readily obtained, and applied as described in Appendix A.  Land
use data, available from the U.S. Geological survey and other sources can
6/88          .    COMFORT AND INDUSTRIAL COOLING TOWERS              6-16

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
be used in combination with the spatial resolution for both categories of
cooling towers, to distribute emissions based on the type of activity
being performed, as shown in Table 6-5.

    Estimated seasonal, daily and hourly temporal resolution for
industrial and comfort cooling towers are also included in Table 2-5, and
can be used with the annual countywide emissions data to estimate
temporal  variations.
6/88         .     COMFORT AND INDUSTRIAL COOLING TOWERS              6-17

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                        PROCEDURES  FOR ESTIMATING AND  ALLOCATING
                           AREA SOURCE  EMISSIONS  OF AIR  TOXICS
                   Table 6-5 Temporal and Spatial  Oesolution for Industrial and
                                    Comfort Cooling Towers

               Industrial  Cooling Towers

               Spatial Resolution
                  Surrogate  indicator-            industrial  areas (codes 13 and  15)
                  Information source:             land use maps

               Temporal Resolution
                  Seasonal:                      uniform through the year
                  Daily:                         uniform through the week
                  Hourly:                        80 percent  from 0700 to 1900, 20
                                                percent from 1900 to 2400.
                                                otherwise zero

               Comfort Cooling  Towers (Residential/Commercial/Instltutional)

               Spatial Resolution
                  Surrogate indicator:            residential areas (land use codes
                                                11, 16, and 17) and commercial
                                                areas (land use codes 12 and 15)
                   Information source(s):          land use maps

               Temporal Resolution
                  Seasonal:                      25 percent  uniform through year and
                                                75 percent  uniform during months
                                                that have an average temperature of
                                                68* or more
                  Daily:                        90 percent  Monday through Saturday
                    10 percent  Sunday
                   Hourly:                        75 percent  0800 through 2000
                    25 percent  0100 through 0800
6/88              .   COMFORT  AND INDUSTRIAL COOLING  TOWERS                   6-18

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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                 REFERENCES

 1.   U.S.  Environmental  Protection  Agency.   Chromium Emissions from Comfort
     Cooling Towers - Background Information for Proposed Standards
     (Preliminary Draft).   Office of Air Quality Planning and Standards.
     Research Triangle Park, NC.  1987.

 2.   Telecon.  Comfort Cooling Towers Population.  P-. Bellin, MRI, with I.
     Kularic, Marley Cooling Towers.  July  5,  1985.

 3.   Telecon. Comfort Cooling Tower Population.   M.  Upchurch, MRI with J.
     Carroll, BAC-Pritchard.  Septembers,  1986.

 4.   Telecon.  Chromium-using Comfort Cooling  Towers.  C. Green, MRI, with
     R.  Kellog, Jr.,  Dubois Chemical Division,  Chemed Corp.  March 29,
     1985.

 5.   Telecon.  Chromium-using Comfort Cooling  Towers.  C. Green, MRI, with
     P.  Thomas, Drew Chemical Company.  April  2, 1985.

 6.   Telecon.  Chromium-using Comfort Cooling  Towers.   C. Green, MRI, with
     J.  Lee, 01 in Water Services.  April 2,  1985.

 7.   U.S.  Environmental  Protection  Agency.   Background Information Document
     (Chapters 3 Through 8) for Chromium Emissions from Industrial Process
     Cool ing Towers. (Draft).  Office of Air Quality Planning and
     Standards. Research Triangle Park,  NC.   1987.

 8.   Trip  report: Sovran Bank, Norfolk,  Virginia.  D. Randall, MRI, to R.
     Meyers, EPA:ISB. July 15, 1986.

 9.   Letter and attachments.  Response to Section 114 information request.
     Campbell R., Union Oil Company of California, to Farmer, J., EPA:ESED.
     July  1, 1986.  •

10.   Letter and attachments.  Response to Section 114 information request.
     Arvidson, P., BASF Corporation, to Farmer,  J.,  EPA:ESED. July 31, 1986,

11.   Letter and attachments.  Summary of CMA member  survey on corrosion
     inhibitors used in process cooling towers including average
     circulating water pom.  Mayer, A.,  Chemical Manufacturers Association,
     to  Cuffe, S., EPA:ISB. September 27, 1986.

12.   Letter and attachments.  Response to Section 114 information request.
     Evans, R., AMOCO Oil  Company,  to Myers,  R., EPA:ISB. June 14, 1985.
6/88         -     COMFORT AND INDUSTRIAL COOLING TOWERS              6-19

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                            REFERENCES  (Continued)


13.  Letter and attachments.  Response to Section 114 information request.
     Simmons, R., ARCO Petroleum Products Company, to Farmer, J., EPA:ESED.
     June 3, 1985.

14.  Letter and attachments.  Response to Section 114 information request.
     Parker, F., Chevron U.S.A., to Farmer, J., EPA:ESED. May 16 and 31,
     1985.

15.  Letter and attachments.  Response to Section 114 information request.
     Johnson, J., Exxon Company, U.S.A., to Farmer, J.,  EPA:ESED. May 20,
     1985.

16.  Letter and attachments.  Response to Section 114 information request.
     Williams, J., Gulf Oil Products Company, to Farmer, J., EPA:ESED. May
     20 and July 26, 1985.

17.  Letter and attachments.  Response to Section 114 information request.
     Kienle, R., Shell Oil Company, to Farmer, J., EPA:ESED. May 22, 1985.

18.  Letter and attachments.  Response to Section 114 information request.
     Hawes, R., Mobil Oil Corporation, to Farmer, J. EPA:ESED. May  20,
     1985.

19.  Letter and attachments. Response to Section 114 information request.
     Cox, R., Texaco U.S.A., to Farmer, J., EPArESED. May 24, 1985.

.20.  U.S. Department of Commerce.  County Business Patterns  1982 United
     States, Employment and Payrolls, Number  and Employment, Size of
     Establishments by Detailed Industry.  CBP-82-1. Bureau  of the  Census.
     October 1984.

21.  U.S. Department of Commerce.   County Business Patterns 1980
     Pennsylvania, Employment and  Payrolls, Number and  Employment.  Size  of
     Establishments bv Detailed Industry.  CBP-80-40. Bureau of  the Census.
     July,  1982.
 6/88          -     COMFORT  AND  INDUSTRIAL  COOLING  TOWERS               6-20

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
7.     FOREST FIRES AND AGRICULTURAL BURNING

7.1    General

    Open burning (e.g., forest wildfires, managed burning, and
agricultural burning) is a source of a number of air toxics, most
notably, products of incomplete combustion such as polycyclic organic
matter (POM).  A forest "wildfire" is a large-scale natural combustion
process that consumes various ages, sizes, and types of botanical
specimens growing outdoors in a defined geographical area.  Managed
burning activities include slash burning and prescribed burning.  Slash
burning practices are used to burn wastes from logging operations under
controlled conditions,  whereas prescribed burning is used as a forest
management practice to  establish favorable seedbeds, remove competing
underbrush, and produce to other ecological benefits.  Agricultural
burning is practiced routinely to clear and/or prepare land for
planting.

7.2    Factors

    Emissions from wildfires and controlled burning in areas can be
significant despite the relatively short duration of the burn.  The size
and intensity of these  fires are dependent on such variables as
meteorological conditions, species of vegetation and their moisture
content, and the weight of consumable fuel per acre.

    Limited data are available to characterize air toxics emissions from
wildfires, managed burning, and agricultural burning.  It has been
hypothesized (but not proved) that the nature and amounts of air
pollutant emissions are directly related to the intensity and direction
(relative to the wind)  of the wildfire and are indirectly related to the
rate at which the fire  spreads.  The factors the rate of spread are (1)
weather (wind velocity, ambient temperature, relative humidity, and

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
precipitation); (2) fuels (type,  bed array, moisture content, and size);
and (3) topography (slope and profile).  However, logistical problems
(such as size of the burning area) and the difficulties involved in
safely situating personnel and equipment near the fire have prevented the
collection of reliable experimental emission data on actual wildfires.
Thus, it is presently impossible to verify or disprove the above
hypothesis.  Until such measurements are made, therefore, the only
available information is that obtained from burning experiments in the
laboratory.  Although existing emission factors are adequate for
laboratory-scale emissions estimates, substantial errors may result if
they are used to calculate actual wildfire emissions.   Emission
factors that can be used to estimate air toxics emitted from forest
fires, managed burning, and agricultural burning are presented in Tables
7-1, 7-2, and 7-3.

7.3      Methodology Options

    For each type of burning or burning operation, the quantity of air
toxics emitted can be estimated by multiplying the number of acres burned
in each county by a fuel loading factor and the emission factor for each
pollutant.  The acreage burned can be obtained from NEDS, along with the
estimated VOC emissions.  Emission estimates of semivolatiles can be
obtained either directly by using the emission factors provided in
Table 7-1.  Emissions for a subset of volatile organic compounds (VOC's),
by the data contained in Tables 7-2 and 7-3.

    Alternatively, instead of relying on NEDS data, Table 7-2 identifies
the percentage by weight of various VOC's emitted from ponderosa loggings
slash materials collected from the San Bernadino National Forest and
                                              2
burned under controlled laboratory conditions.   Table 7-3  is a summary
of total hydrocarbon emission factors for forest wildfires  as a function
of geographical area.  Wildfire emissions of a compound listed
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                     PROCEDURES  FOR ESTIMATING  AND ALLOCATING
                        AREA  SOURCE  EMISSIONS  OF AIR  TOXICS
                     Table 7-1 Emission Factors Used to Estimate Emissions from
                       Wildfires, Managed Burning, and Agricultural Burning
Emission factor
Air toxic (kg/MT dry fuel)
Anthracene 2.5 x 10
Benzo(a)anthracene 3.1 x 10
Benzo(a)f luoranthene 1.3 x 10
Benzo(k)f luoranthene 1.3 x 10
Benzo(ghi)perylene 2.5 x 10
-4
Benzo(a)pyrene 7.4 x 10
Cnrysene 3.1 x 10
Fluoranthene 5.5 x 10
Indeno(l,2,3-cd)pyrene 1.7 x 10 J
Phenanthrene 2.5 x 10
Pyrene 4.6 x 10
Emission factor
(Ib/ton dry fuel)
5.0 x 10"3
6.2 x 10~3
2.6 x 10"
2.6 x 10"J
.5.0 x 10'3
1.5 x 10'3
6.2 x 10"3
1.1 x 10"2
2.4 x 10*
5.0 x 10~3
9.2 x 10"3
              Source:  Reference 4.
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                          PROCEDURES FOR  ESTIMATING  AND  ALLOCATING
                              AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
                           Table 7-2 Summary of Hydrocarbon Emission  Factors
                                        for Forest Wildfires3
               Geographic area
                   Emission factors, kg/hectare

                        Hydrocarbons
               Rocky Mountain
               .group
                  Northern.
                     Region 1
                  Rocky Mountain,
                     Region 2
                  Southwestern,
                     Region 3
                  Intermountain.
                     Region 4
                              996


                            1.620

                              808

                              269

                              215
               Pacific group
                  Cal iforma,
                     Region  5
                  Alaska,
                     Region  10
                  Pacific  N.W..
                     Region  6
                              512

                              485

                              431

                            1.620
                Southern group
                  Southern,
                     Region 8
                              242
                              242
                North Central group
                  Eastern,  Region 9
                (Both groups are in
                Region 9)
                              296
                              296
                Eastern group
                (With Region 9)
                              296
                Total United  States
                              458
                aAreas consumed by wildfire and emissions are for 1971.

                 Geographic areas are defined in Figure  7-1

                Source:  Reference 1.
6/88
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7-4

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                     PROCEDURES  FOR ESTIMATING AND  ALLOCATING
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                           Table 7-3 Volatile Organic Species Profile
                                 from Typical Forest Wildfires
Chemical name
Isomers of pentane
Propane
N-Butane
Isobutane
Isomers of butene
Ethylene
Propylene
Butene
1 ,3-Butadiene
3-Methyl-l-butene
Unidentified hydrocarbons
Acetylene
Methylacetylene
Methane
Ethane
Percent weight
15
.35
.24
.11
.92
19.11
3.93
.81
.52
.17
44.59
8.40
.41
9.82
10.47
              Source:  Reference 3
6/88             -.  FOREST  FIRES AND  AGRICULTURAL BURNING
7-5

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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in Table 7-2 can be estimated by simply (1) multiplying the "percent
weight" term for that compound by the hydrocarbon emission factor
corresponding to the geographical area of interest and (2) multiplying
that product by the estimated acreage of the wildfire.  This procedure is
illustrated in Example 2 in this section.

    As noted earlier, NEDS lists the acreage, tons of growth burned per
acre, and VOC emissions.  In most cases these data are adequate.

    For forest "wildfires," estimates of the quantity and types of growth
burned in a given area can also be obtained from the U.S. Forest
Service's state forestry or agricultural department, or from local fire
protection agencies.  For localities where estimates are not available,
                                                               2
the U.S. Forest Service annually publishes Wildfire Statistics,  which
gives the total acreage burned in each state.  Although this document
does not include data for each county, local fire and forestry officials
can usually provide county-specific estimates.  If sufficient information
cannot be obtained from local officials, the state total from Wild Fire
Statistics should be apportioned to counties according to forest acreage
per county.

    Determination of tons of growth burned per acre ("fuel loading") is
equally important, and local officials should be contacted for this
information.  The emissions in the study area are then obtained by
multiplying the appropriate emission factor by the fuel loading factor,
then multiplying this product by the amount of forest acreage burned.

    Average fuel loadings for the various U.S. Forest Service regions  are
presented in Table 7-4.

    Slash Burning and Agricultural Field Burning.  Wastes from logging
operations are often burned under controlled conditions to reduce
 6/88          -     FOREST  FIRES AND AGRICULTURAL BURNING               7-6

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                      PROCEDURES FOR ESTIMATING AND ALLOCATING
                         AREA SOURCE  EMISSIONS  OF AIR TOXICS
                       Table 7-4 Summary of Estimated Fuel  Consumed
                                    by Forest Fires
             Area and region
          Eastern group
                                      Estimated average fuel loading


                                          MT/hectare    ton/acre
Rocky Mountain
Region r
Region 2:
Region 3:
Region 4:
Pacific group
Region 5:
Region 6:
Region 10:


Southern group
Region 8:
group
Northern
Rocky Mountain
Southwestern
Inter-mountain

Cal ifornia
Pacific Northwest
Alaska
Coastal
Interior

Southern
83
135
67
22
40
43
40
135
36
135
25
20
20
37
60
30
10
8
19
18
60
16
60
11
9
9
                                            25
11
          North Central group

             Region 9: Conifers

                      Hardwoods
                                            25

                                            22

                                            27
11

10

12
6/88
a Geographical areas are defined in Figure 7-1.

Source:  Reference  1


       "-    FOREST FIRES AND AGRICULTURAL  BURNING
               7-7

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                  PROCEDURES FOR  ESTIMATING AND ALLOCATING

                     AREA SOURCE EMISSIONS  OF AIR TOXICS
        
          10
                JUNEAU
                                          •  HEADQUARTERS

                                        _	REGIONAL BOUNDARIES
            Figure 7-1  Forest Area and  U.S. Forest Service  Regions
6/88
FOREST FIRES AND AGRICULTURAL BURNING
7-8

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
the potential fire hazard in forests and to remove brush that can serve
as host for destructive insects.  As with forest fires, NEDS provides
data on the acreage and tons of growth burned per acre, and the estimated
VOC emissions.  If NEDS data are not used, Officials of the U.S. Forest
Service or the state forestry department can be contacted for estimates
of the area burned and quantity of slash burned per acre.  If an estimate
of the quantity of slash burned per acre cannot be obtained from other
sources, a rough value of 75 tons per acre can be used.

    Also included in this source category are agricultural field burning
operations such as stubble burning and burning of land-clearing refuse.
Little published information is available on this subject, so burning
activity estimates must be determined through state agriculture
departments or extension services.

    Acreage and average fuel loadings should be estimated.  The U.S. Soil
Conservation Service should be able to provide some of this information.
Average fuel loadings and organic emission factors for various wastes are
provided in Section 2.4 of Reference 1.  In some cases, agricultural
burning may be reported under residential open burning.

7.4      Example Calculations

Example Calculation 1

    By assuming that a wildfire in a county located in the Pacific
Northwest consumes 1,735 hectares, one can estimate the quantity of
Benzo[a]anthracene (BaA) emitted.  Using Table 7-1, the total quantity
emitted can be calculated as follows:

Total BaA = 3.1xlO'3kg BaA x 1,735 hectares x 60MT fuel*
            MT dry fuel                       hectare
Total BaA = 3.2 x IQ/kg BaA emitted.
    *  From Table 7-4

6/88          .    FOREST FIRES AND AGRICULTURAL BURNING              7-9

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    In a similar manner, emissions can be estimated for the other
pollutants shown in Table 7-1, as follows:
    Anthracene                        260 kg = 0.3 MT
    Benzo(a)fluoranthene              135 kg * 0.1 MT
    Benzo(k)fluoranthene              135 kg = 0.1 MT
    Benzo(ghi)perylene                229 kg = 0.2 MT
    Benzo(a)pyrene                    770 kg ป 0.8 MT
    Chrysene                          323 kg = 0.3 MT
    Fluoranthene                      572 kg = 0.6 MT
    Indeno(l,2,3-cd)Pyrene            177 kg = 0.2 MT
    Phenanthrene                      260 kg = 0.3 MT
    Pyrene        .                    479 kg = 0.5 MT

Example Calculation 2

    NEDS reports that a wildfire in a county in Alaska produces 1,208
tons of VOC emissions annually; one can estimate the quantity of
1,3-butadiene using the speciation factor provided in Table 7-2.

Total 1,3-Butadiene = (1208 tons/yr) (907 kg/ton) (0.0052 kg/kg of VOC)
                    = 5.7
    In a similar manner, emissions can be estimated for the other
pollutants in cited Table 7-2, as follows:
              Isomers of pentane            1.6 x 10  kg
              Propane                       3.8 x 103 kg
              N-Butane                      2.6 x 103 kg
              Isobutane                     1.2 x 103 kg
              Isomers of butene             1.0 x 10  kg
              Ethylene                      2.1 x 105 kg
              Propylene                     4.3 x 10  kg
              Butene                  •      8.9 x 103 kg
*
     From Table 7-2.
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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
             3-Methyl-l-butene             1.9 x 103 kg
             Acetylene                     9.2 x 104 kg
             Methy acetylene               4.5 x 10  kg
             Methane                       1.1 x 105 kg
             Ethane                        1.2 x 105 kg
             Unidentified hydrocarbons     4.9 x 10  kg
7.5    Methods to Apportion Countywide Emissions from Forest Fires and
       Agricultural Burning
    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect on-going activities in that portion
of the county, e.g., residential heating in the winter, commercial
solvent usage during working hours on weekdays.

    There are three alternative approaches that can be used in spatially
distributing emission:  (1) population, i.e., the magnitude of emissions
within a grid are directly  proportional to the population living in the
grid, (2) land area, i.e., emissions from a countywide area source are
assumed to be uniform throughout the county and are distributed based on
the size of the area source grid, and (3) land use patterns that assume
that certain area source activities, most likely to occur in certain
areas of the county, e.g., commercial, residential or industrial.

    In apportioning emissions from agricultural burning, and of these
methods may be appropriate.  Land area and population data can be readily
obtained, and applied as described in Appendix A.  Land use data,
available from the U.S. Geological Survey and other sources can be used
6/88          -    FOREST FIRES AND AGRICULTURAL BURNING              7-11

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
in combination with the spatial  distribution for agricultural  burning, to
distribute emissions based on the type of activity being performed, as
shown in Table 7-5.

    Seasonal, daily, and hour  temporal resolution are also included in
Table 7-5, and can be used with the annual countywide emissions data to
estimate temporal variations.
6/88          -   FOREST FIRES AND AGRICULTURAL BURNING              7-12

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                      PROCEDURES FOR ESTIMATING  AND  ALLOCATING
                         AREA  SOURCE  EMISSIONS OF  AIR  TOXICS
                         Table 7-5 Spatial and Temporal Resolutions
                                 for Agricultural Burning
              Spatial Resolution
                  Surrogate  indicator:     areas where these activities occur
                  Information source(s):   U.S. Forest Service, state forestry
                                         departments,  state agricultural
                                         department, extension services, citrus
                                         grove operations, and land use map
              Temporal Resolution
                  Seasonal, and Daily:     Base on local  regulations and on data
                                         collected from information sources.
                  Hourly:                 N/A
6/88                  FOREST FIRES  AND  AGRICULTURAL  BURNING                 7-13

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
                                REFERENCES
1.   U.S. Environmental  Protection Agency.   Compilation of Air Pollution
    Emission Factors,  Volume I:   Stationary Point and Area Sources
    (AP-42)  Fourth Edition.   EPA-460/3-81-005.   Office of Air Quality
    Planning and Standards.   Research Triangle  Park, NC.  1985.

2.   U.S. Environmental  Protection Agency.   Volatile Organic Compound
    (VOC) Species Data Manual.   Second Edition.   EPA-450/3-81-005.
    Office of Air Quality Planning and Standards.  Research Triangle
    Park, NC.  1980.

3.   U.S. Department of Agriculture,  Forest Service.  Wildfire Statistics
    (Annual].  Washington, DC.

4.   Arthur D. Little,  Inc.  An  Exposure and Risk Assessment for
    Benzofalpyrene and Other Polvcvlic Aromatic Hydrocarbons, Volume IV,
    Benzofalpyrene, Acenaphthylene.  BenzFalanthracene,
    Benzofblfluoranthene. Benzol" blfluoranthene,  Benzofklfluoranthene,
    Benzofg,h,i1pery1ene. Chrvsene,  Pibenzfa.hi anthracene, and
    Idenori.2.3-c.d1pyrene.   U.S. EPA Contract  No. 68-01-6160.  U.S.
    Environmental Protection Agency, Office of  Water Regulations and
    Standards.   Washington, D.C. 1982.

5.   U.S. Environmental  Protection Agency.   Guidelines for the Preparation
    of Emission Inventories  for Volatile Organic Compounds Volume II:
    Emission Inventory Requirements for Photochemical Air Quality
    Simulation Models.   EPA-450/4-78-018.   U.S.  Office of Air Quality
    Planning and Standards.   Research Triangle  Park, NC.  September  1979.
6/88              FOREST FIRES AND AGRICULTURAL BURNING              7-14

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                  PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
8.     GASOLINE SERVICE STATIONS (GASOLINE MARKETING)

8.1    General

    Air toxics are emitted from gasoline stations as a result of  (1)
underground storage tank filling,  (2) underground storage tank breathing,
and (3) vehicle refueling.  The quantity of gasoline vapor released from
each of these sources is affected  by the method and rate of tank  filling,
tank geometry, and quantity of gasoline added.  The amount of any one
toxic chemical released.with the vapor depends on such factors as the
initial concentration of the chemical in the gasoline, the vapor-liquid
equilibrium of the system, and the temperature within the tank.

    Gasoline is generally transported to retail sales outlets in
8,000-gallon tank trucks.  When these trucks unload the gasoline  into.
underground storage tanks, gasoline vapor in the storage tank is
displaced by the liquid gasoline and vented to the atmosphere.  The
underground storage tank may be filled by either a splash or a submerged
method.

    With the splash filling method, the fill pipe ends above the  level of
the gasoline in the tank so that,  as gasoline enters the tank, it
.splashes into the liquid already in the tank, causing turbulent mixing
and additional vaporization of volatiles.  The displaced vapors are then
lost through the hatch.

    Submerged filling lessens the  amount of vaporization because  the fill
pipe extends below the liquid level.  Although this method avoids the
turbulent splattering of the splash method, emissions of displaced vapors
are still not controlled.

    One control method that avoids this problem is a vapor balance system

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
wherein gasoline vapors are returned to the tank truck and the
underground tank is equipped with a pressure relief vent.  This method of
submerged filling is 93 to 100 percent efficient at controlling vapor
emissions.

    In 1980, an estimated 70 to 95 percent of the service stations used
submerged filling techniques, with the balance using splash filling.
Only a very small number used the vapor balance method.  Recent trends
show a move toward submerged and vapor balanced methods and away from the
splash technique.  Current local data on the filling techniques and
control methods should be used whenever possible.

    Underground storage tank breathing losses result from daily changes
in temperature and barometric pressure, which change the vapor-liquid
equilibrium of the system and cause expansion and contraction of the
vapors.  Expansion forces vapors out of the tank and into the
atmosphere.  When the vapor in the tank contracts, however, fresh air is
drawn  into the tank, and volatilization increases until equilibrium is
again  reached.  This cycle repeats with daily environmental changes.  The
quantity of fresh air introduced into the tank when gasoline is withdrawn
also increases the amount of evaporation and, thus, breathing losses.

    Vehicle refueling also results in the emission of vapors to the
atmosphere because the vapors present in the automobile gas tank are
displaced by gasoline and because gasoline spilled during refueling
evaporates.  Emissions of displaced vapors can be controlled by conveying
the displaced vapors back to the underground storage tank through a
specially-designed hose and nozzle.  This conveyance can either be caused
by a natural pressure differential established during gasoline transfer
(as with the vapor balanced storage tank fill method) or by a
vacuum-assisted method.
6/88          .GASOLINE SERVICE STATIONS  (GASOLINE MARKETING)         8-2

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
8.2      Factors

    Emission factors relating the quantity of benzene,
1,2-dichloroethane, (ethylene dichloride), and ethylene dibromide (EDB)
released from sources within gasoline service stations to the volume of
gasoline flowing through the system are presented in Table 8-1.  In this
table apportionment factors have been applied, where appropriate, to the
estimated quantity of gasoline vapors emitted from each source.  In order
for these factors to be useful, the quantity of gasoline flowing through
the system must be known.  This quantity can be approximated by using the
quantity of gasoline sold within a given study area, as provided in NEDS
or other data sources.

    Estimates of VOC emissions can be speciated using factors being
developed by OAQPS.2  The speciation profile for gasoline marketing  is
presented in Table 8-2.  It should be noted that the benzene speciation
factor is approximately five times greater in Reference 2 than it is in
Reference 1; this discrepancy is probably at least in part attributable
to the large variation in gasoline compositions.

8.3      Methodology Options

    As noted earlier, NEDS contains data on the quantities of gasoline
marketed in a county (as well as estimated VOC emissions).  In most
cases, these data are considered to be adequate.  However, if NEDS
estimates are believed to be out of date, or unreliable for other
reasons, the quantities of gasoline sold in a study area can be estimated
using one of several methods described below (in order of preference):

    Distributor Data.  Data from the gasoline distributor provide the
most accurate source of gasoline use figures because they are based on
the actual quantity of gasoline passing through the system rather than on
the amount sold.  Unfortunately, these data are not usually available for
all areas of the country.

6/88         -GASOLINE SERVICE STATIONS (GASOLINE MARKETING)         8-3

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                        PROCEDURES  FOR  ESTIMATING AND  ALLOCATING
                           AREA SOURCE  EMISSIONS  OF AIR  TOXICS
                        Table 8-1 Selected Air Toxic Emissions  from Gasoline Stations3
Emission source
Benzene emissions
(g/Db
(lb/gal)
Ethylene dichloride
emissions
(g/Dc
(lb/gal)
Ethyene dibromide
emissions
(g/D
! lb/gal)
Filling Underground Storage Tanks
Submerged

Splash
Vapor balance
(submerged)
Breathing
Losses
Vehicle Refueling
Uncontrolled
displacement
Controlled
displacement
Spillage
5.28 x
(4.4 x
8.28 x
(6.9 x
2.4 x
(2.0 x
7.2 x
(6.0 x

7.92 x
(6.6 x
7.92 x
(6.6 x
4.8 x
(4.0 x
ID'3
10'5)
io-35
10 5)
ID'4
10'5)
ID'4
10'6)

ID"3
10"5)
ID'4
10"6)
10~46
10'6)
4.4 x
(3.7 x
6.9 x
(5.8 x
2.0 x
(1.7 x
6.0 x
(5.0 x

6.6 x
(5.5 x
6.6 x
(5.5 x
4.0 x
(3.3 x
ID'4
ID'6
10"46
10 6)
ID'5
ID'7)
io-5
103)

io-4
IO"6)
ID'5
10"3)
IO-5
10"3)
4.4 x
(3.7 x
6.9 x
(5.8 x
2.0 x
(1.7 x
6.0 x
(5.0 x

6.6 x
(5.5 x
6.6 x
(5.5 x
4.0 x
(3.3 x
ID'5
ID'7)
ID'5
1Q-7)
io-6
10'8)
ID'6
10"8)

1C'5
10"7)
io-6
10"8)
ID'6
10'8)
         Emission factors  given in units of grams of toxic vapor released  per liter of
        gasoline passing through the system.

        bBased on the apportionment factor, 6.0 x 10"3 MT benzene/MT VOC  (Reference 1  in
        conjunction with emission factors from AP-42. (Reference 4)

        GBased on the apportionment factor, 5.0 x 10"4 MT ethylene dichloride/MT VOC
        (Reference 1). in  conjunction with emission factors from AP-42.  (Reference 4)

         Based on the apportionment factor, 5.0 x 10   MT ethylene dibromide/MT VOC
        (Reference 1), in  conjunction with emission factors from AP-42.  (Reference 4)
6/88
GASOLINE SERVICE  STATIONS  (GASOLINE  MARKETING)
8-4

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                       PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                           AREA SOURCE EMISSIONS  OF  AIR  TOXICS
                    Table 8-2  VOC Special ion  Factors for Gasoline Marketing
              Species Name                             Percent Weight
           Isomers of Hexane                               0.10
           Isomers of Decane                               0.10
           Isomers of Undecane                              0.09
           Isomers of Undecane                              0.00
           Isomers of Dodecane                              0.00
           Isomers of Dodecane                              0.05
           Isomers of Tetradecane                           0.02
           C-7 Cycloparaffins                               0.05
           C9 Olefins                                      0.08
           C9 Olefins                                      0.01
           C9 Olefins                                      0.01
           C9 Olefins                                      0.00
           CIO Olefins                                     0.04
           CIO Olefins                                     0.00
           CIO Paraffin                                    0.00
           CIO Paraffin                                    0.00
           CIO Paraffin                                    0.00
           C9 Paraffin                                     0.48
           C-8 Olefins                                     0.00
           C-8 Olefins                                     0.21
           C8 Paraffin                                     3.84
           C7 Paraffin                                     0.04
           C5 Olefin                                       1.91
           C5 Paraffin                                     2.09
           C5 Paraffin/Olefin                               1.08
           Cll Olefin                                      0.00
           Cll Olefin                                      0.01
           Cll Olefin                                      0.04
           C9H16                                           0.00
           C9H16                                           0.02
           C9H16                                           0.00
           C8H14                                           0.00
           Butene                                          0.14
           Hexane                                          3.91
           Heptane                                         1.84
           Cyclopentane                                    0.16
           Methylcyclohexane                               0.21
           Methylcyclopentane                               0.68
           Heptene                                         0.03
           Methylcyclopentene                               0.45
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                 PROCEDURES FOR  ESTIMATING AND  ALLOCATING
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                           Table 8-2 (Continued)
         Species Name                        Percent Weight
Cyclohexene
Ethyl eye lohexane
Cyclopentene
C7H120
Dimethylcyclobutanone
Isomers of Butylbenzene
Isomers of Butylbenzene
Isomers of Oi ethyl benzene
Trimethylbenzene
Isomers of Propylbenzene
C10H12
C10H10
C10H10
Benzene
Toluene
Ethyl benzene
0-Xylene
Cunene (Isopropyl Benzene)
Styrene
Methyl Styrene
Ethyltoluene
Propylbenzene
Ethyldimethylbenzene
Tetramethyl benzene
CS-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene
C5-Alkylbenzene (Unsat.)
C6-Alkylbenzene
C6-Alkylbenzene
C6-Alkylbenzene
C6-Alkylbenzene
C6-Alkylbenzene
C6-A1ky1benzene
C4-Alkylstyrene
C4-Alkylstyrene
C4-Alkylstyrene
C4-Alkylstyrene
0.04
0.08
0.18
0.04
0.05
3.18
0.03
0.02
4.29
0.76
0.04
0.00
0.00
3.25
15.22
4.07
6.41
0.33
0.17
0.05
3.61
0.92
1.24
1.03
0.35
0.02
0.04
0.05
0.83
0.05
0.09
0.05
0.00
0.06
0.00
0.03
0.02
0.00
0.04
0.02
0.00
0.01
6/88          ".GASOLINE SERVICE STATIONS  (GASOLINE MARKETING)          8-6

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                       PROCEDURES  FOR ESTIMATING AND  ALLOCATING
                          AREA  SOURCE  EMISSIONS  OF AIR  TOXICS
                                    Table 8-2 (Continued)
             Species  Name                             Percent Weight
          C7-Alky1benzene                                  0.00
          Benzaldehyde                                     0.00
          Chlorobenzene                                    0.03
          Oimethylnaphthyndine                            0.01
          Napthalene                                       0.80
          Methyl Naphthalenes                              0.64
          C2-Alkylnapthalene                               0.10
          Methylindan                                      0.01
          Methylindan                                      0.52'
          Methylindan                                      0.00
          Methyldihydronaphthalene                         0.01
          Dimethylindan                                    0.00
          Dimethylindan                                    0.42
          Dimethylindan                                    0.00
          Dihydronapthalene                                0.06
          Dimethylindene                                   0.01
          Ethylindan                                       0.04
          Tnmethyl indan                                   0.06
          M-Xylene  and P-Xylene                           15.28
          Methylpropane                                    2.65-
          Methylpropene                                    0.14
          Methylbutene                                     0.06
          Methylbutadiene                                  0.01
          Methylpentene                                    0.48
          Methylpentene                                    0.41
          Methylpentane                                    1.76
          Methylcyclopentadiene                            0.04
          Methylhexane                                     1.68
          Methylhexene                                     0.00
          Methylhexene                                     0.03
          Methylhexadiene                                  0.25
          Methylcyclohexadiene                   '          0.02
          Methylhexanal                                    0,92
          Methylheptyne                                    0.02
          Methytheptane                                    0.35
          Methylcyclohexene                                0.14
          Methylnonane                                     0.21
          Methyldecane                                     0.12
          Pentenyne                                        0.03
          Hexene                                          0.40
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                        PROCEDURES  FOR ESTIMATING AND  ALLOCATING
                           AREA SOURCE EMISSIONS  OF AIR  TOXICS
                                     Table 8-2 (Continued)
               Species Name                             Percent Weight
            Hexadienal                                       0.03
            Heptadienal                                      0.02
            Dimethylbutane                                   2.29
            Dimethylbutene                                   0.30
            Dimethylpentane                                  0.36
            Dimethylpentene                                  0.02
            Dimethylcyclopentane                             0.15
            Dimethylcyclopentene                             0.22
            Dimethylcyclopentene                             0.09
            Dimethylhexane                                   0.48
            Dimethylhexane   •                                0.28
            Dimethylhexadiene                                0.10
            Dimethylethylcyclohexane                         0.09
            Oimethyloctane                                   0.04
            Dimethyloctane                                   0.02
            Oimethylundecane                                 0.00
            Oimethyldecane                                   Q.Q7
            Ethylpentene                                     0.03
            Ethylcyclopentene                                0.06
            Ethylmethylcyclopentane                          0.12
            Ethylhexane                                      0.24
            Ethylmethylhexane                                0.21
            Ethylmethylcyclohexane                           0.04
            Ethylmethylcyclohexane                           0.02
            Ethylheptane                                     0.02
            Ethylmethyloctane                                0.02
            Ethylbicycloheptane                              0.01
            Ethyldimethylpentane                             0.13
            Tetramethylcyclobutene                           0.04
            Tnmetnylpentane                                 0.68
            Trimethylpentadiene                              0.05
            Tnmethylheptane                                 0.09
            Trimethylheptane                                 0.05
            Trimethylhexene                                  0.04
            Trimethyloctane                                  0.07
            Trimethyldecane                                  0.03
            Octatnene                                      0.01
            Nonene                                          0.03
            Pentadiene                                •      0.04
            Methyloctane                                     0.55
            Indane                                          0.44
6/88             GASOLINE  SERVICE STATIONS  (GASOLINE MARKETING)            8-8

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                  PROCEDURES FOR ESTIMATING  AND ALLOCATING
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                              Table 8-2  (Continued)
          Species  Name                          Percent Weight
       Tnmethylcyclopentane                         0.09
       Dimethylcyclohexane                           0.10
       Tnmethylcyclohexane                          0.02
       Dimethyl heptane           •                   0.16
       Unidentified                                 0.00
       Source:  Reference 2
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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Fuel  Tax Data.  Fuel  tax data,  on the other hand,  are readily
available through state fuel tax offices.  These data  provide tax
statistics for local  political  jurisdictions.   Therefore, because tax is
collected for each gallon sold, gasoline consumption can be
back-calculated with  the  tax formulas from each jurisdiction.  Care must
be taken, however, that the local  jurisdictions of interest have
comparable tax bases.  For instance, gasoline sold to  government
agencies, or for nonhighway use, may not be taxed in one jurisdiction,
but may be taxed in another.

    Questionnaires.  If the area sources of interest do not correspond
directly with a local tax area, and if the sources are relatively few in
number, direct questionnaires concerning gasoline volumes distributed may
be useful.  An example of a situation for which this method may be
helpful is if the investigator is concerned only with  emissions resulting
from gasoline sales by convenience stores within a three-county area.
Advantages of this type of data include the accuracy of the results and
the flexibility to ask particular questions, such as emission control
practices and number of employees.   Obvious administrative and analytical
difficulties limit the usefulness of this data source.

    Publications.  National publications also provide data on gasoline
consumption and sales.  The Federal Highway Authority publishes Highway
Statistics,  containing state consumption data.  These state data can
be apportioned to local areas if the percent of state gasoline sales
occurring within each jurisdiction can be determined.   Other
apportionment factors such as vehicle miles traveled,  registered
vehicles, or population within the local jurisdiction, can be used if
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they are more appropriate for a particular area.  Countywide gasoline
sales data are available in the Census of Retail Trade. '  '

8.4      Example Calculation

    Analysis of fuel tax data for the county of concern showed that
         Q
2.78 x 10  liters of gasoline were sold in that county in 1986.  It was
also determined that approximately 90 p_ercent of the stations were
equipped for submerged fueling of underground storage tanks, 5 percent
used splash filling techniques, and 5 percent used a vapor balanced
technique.  In addition, .only 10 percent of the stations were equipped
with pump nozzles that controlled refueling losses.  Benzene emissions
from gasoline service stations in this county can be estimated as
follows, based on emission factors provided in Table 8-1.

    (1)  Filling of underground storage tanks

         (a)  Submerged
         (5.28 x 10"3 grams of benzene/liter) x (2.78 x 109 liters)
         x 0.90
         = 1.32 x 10^ grams of benzene/year
         (b)  Splash
         (8.28 x 10'3) x (2.78 x 109) x 0.05
         = 1.15xl06 grams of benzene/year
         (c)  Vapor Balanced
         (2.4 x 10'4) x (2.78 x 109) x 0.05
         = 3.34xl04 grams of benzene/year
    (2)  Breathing losses
         (7.2 x 10'4) x (2.78 x 109)
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         = 2.00 x 106 grams of benzene/year
    (3)   Vehicle refuel ing
         (a)   Uncontrolled
         (7.92 x 1CT3) x (2.78 x 109)  x 0.90
         = 1.98x10? grams of benzene/year
         (b)   Controlled
         (7.92 x 10'4) x (2.78 x 109)  x 0.10
         = 1.98x106 grams of benzene/year
    (4)        Spillage
         (4.8 x 10'4) x (2.78 x 109)
         = 1.33x10^ grams of benzene/year.
    The  total countywide emissions of benzene from gasoline service
stations can  be estimated by summing the component emissions as shown:

(1.32 x  107)+(1.15 x 105)+(3.34 x 104)+(2.00 x 106) + (1.98 x 107) +
(1.98 x  106)  + (1.33 x 106)
= 3.95 x 10  grams of benzene/year
= 39.5 MT benzene/year.

    Similarly, emissions of 1,2 dichoroethane are estimated to be
3.3 MT/yr, and emissions of ethylene dibromide are estimated to be
0.3 MT/yr.

8.5    Methods to Apportion Countvwide Emissions from Gasoline Marketing

    As described in Section 1.0 and Appendix A when performing air
dispersion modeling,  it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
emissions,  similarly temporal in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.


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Modeling results would then reflect on-going activities  in that portion
of the county, e.g., residential heating in winter, commercial solvent
usage during working hours on weekdays.

    There are three alternative approaches that can be used  in spatially
distributing emission:  (1) population, i.e., the magnitude  of emissions
within  a grid, (2) land area, i.e., emissions from a countywide  area
source are assumed to be uniform throughout the county and are
distributed based on the size of the area source grid, and (3) land  use
patterns, assume that certain  area  source activities, most likely occur
in certain areas of the  county,  e.g., commercial, residential  or
industrial.

    In apportioning emissions from gasoline marketing, any of these
methods may be appropriate.  Land area and population data can be readi.ly
obtained, and applied as described in Appendix A.  Land  use  data,
available from the U.S.  Geological Survey and other sources  can be used
in combination with the spatial resolution for gasoline  marketing, to
distribute emissions based on the type of activity being performed,  as
shown in Table 8-3.

    Estimated seasonal,  daily, and hourly temporal resolution for
gasoline marketing are .also included in Table 8-3, and can be used with
the annual countywide emissions data to estimate temporal variations.
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                          Table 8-3 Spatial and Temporal Resolutions
                                  for Gasoline Marketing
               Spatial Resolution
                   Surrogate indicator:      Industrial and commercial/institutional
                                          land use areas (Codes 12, 13, and  15}
                   Information source(s):    land use map and Reference 14
               Temporal Resolution
                   Seasonal:              uniform through the year
                   Daily:                 Monday through Saturday
                   Hourly:                uniform from 0600 to 2000, otherwise
                                         zero
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                 PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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                                 REFERENCES


1.  U.S.  Environmental Protection Agency.  Evaluation of Air Pollution
    Regulatory Strategies for the Gasoline Marketing Industry.
    450/3-84-012a.   Office of Air and Radiation.  Washington, DC. 1984.

2.  Air Emissions Species Manual,  Volume  I:  Volatile Organic Compound
    (VOC) Species Profiles And Volume  II;  Particulate Matter (PM) Species
    Manual.  EPA-450/2-88-003a and b,  U.  S. Environmental Protection  Agency,
    Research Triangle Park,  NC, April  1988.

3.  U.S.  Environmental Protection Agency.  Procedures for the Preparation
    of Emission Inventories for Volatile Organic Compounds,  Vol. I.  EPA
    450/2-770-028.   Office of Air Quality Planning and Standards.
    Research Triangle Park, NC. 1980.

4.  U.S.  Environmental Protection Agency.  Compilation of Air Pollutant
    Emission Factors.  Vol. I: Stationary Point and Area Sources (AP-42).
    Fourth Edition.  EPA-460/3-81-005.  Office of Air Quality Planning
    and Standards.    Research Triangle Park,  NC. 1985.

5.  U.S.  Department of Transportation.  Highway Statistics.  Federal
    Highway Administration, Washington, DC.   Annual.

6.  U.S.  Department of Commerce.   Census of Retail Trade.  Bureau of
    Census.  Washington, DC.  Quinquennial.

7.  GCA Technology Division,  Inc.  Area Source Documentation for 1985
    National Acid Precipitation Assessment Program Inventory.  Office of
    Research and Development.  Washington, DC. 1986.

8.  U.S.  Environmental Protection Agency.  Procedures for the Preparation
    of Emission Inventories for Volatile Organic Compounds Volume II:
    Emission Inventory Requirements for Photochemical Air Quality
    Simulation Models.  EPA-450/4-79-015.  U.S. Office of Air Quality
    Planning and Standards.   Research Triangle Park, NC.  September 1979.
6/88         -GASOLINE SERVICE STATIONS (GASOLINE MARKETING)         8-15

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9.     CHROMIUM ELECTROPLATING

9.1    General

    The chromium electroplating source category includes two distinct
types of plating operations:  hard and decorative.  In hard plating, the
substrate (usually steel) is plated with a relatively thick layer of
chromium to provide wear resistance, low coefficient of friction,
hardness, and corrosion resistance or to build up surfaces that have been
eroded by use.  Hard plating is used for items such as hydraulic
cylinders and rods, industrial rolls, zinc die castings, plastic molds,
engine components, and marine hardware.  In decorative plating, the
substrate (e.g., brass, steel, aluminum, or plastic) is plated with a
layer of nickel followed by a relatively thin layer of chromium to
provide a bright, tarnish-resistant surface.  Decorative plating is used
for items such as automotive trim, metal furniture, bicycles, hand tools,
and plumbing fixtures.  Although other types of operations performed at
electroplating plants involve chromium in some form, this source category
includes only those processes that use chromic acid in an electrolytic
cell to deposit chromium metal on a product.

    There are approximately 4,500  chromium electroplating operations
in the country.  Chromium electroplating is used in the manufacture of a
wide variety of industrial  and consumer items.  In general, chromium
plating operations are located at or near the industries they service,
which are usually in centers of high population density.  Plating
operations range in size from small shops operating one tank for as few
as 15 hours per week to large shops operating several  tanks for as many
as 130 hours per week.  Most plating operations are "captive" processes
performed within larger manufacturing facilities.   Some operations are
"job shops" that provide custom plating services for many different
clients.  Captive platers and job shops may perform either hard plating,
decorative plating, or both.

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    The actual chromium plating process is similar for hard and
decorative plating, although pretreatment processes and operating
parameters may differ somewhat.  The plating process involves dipping the
item to be plated in a tank containing chromic acid solution and a small
amount of sulfuric acid as a catalyst.  Electric current passed through
the lead anodes causes chromium to deposit out of solution onto the
substrate, which acts as the cathode.  (In the case of plating a plastic
substrate, the pretreatment process includes steps to render the surface
conductive so that it can act as the electrical cathode.)

    The chromium  plating process is inefficient.  Only 10 to 20 percent
of the electric current supplied to the anodes is used to deposit
chromium onto the item; the rest produces chemical reactions that
generate hydrogen gas at the surface of the cathodes and oxygen gas at
the surface of the anodes.  Efficiency can be improved in some situations
by using fluoride rather than sulfuric acid as the catalyst in the
plating solution.  Fluoride cannot be used in all types of plating
solutions, however, and may cause "etching" or "burning" of exposed steel
surfaces if used in hard plating solutions.

9.2      Factors

    Hexavalent chromium is emitted during the chromium electroplating
process.  It  can be seen as a yellow mist that is formed when hydrogen
gas is released through the surface of the plating solution.
Additionally, oxygen bubble formation and plating bath evaporation
contribute to chromium emissions; however, their contribution is
negligible when compared to emissions related to hydrogen gas generation.

    The amount of mist generated and consequently the amount of
hexavalent chromium emitted depends on several factors:  (1) the
magnitude of  the current supplied to the  anodes,  (2) the surface area
plated, (3) the duration of electrolysis,  (4) the quantity of chromic
 6/88          -           CHROMIUM ELECTROPLATING                     9-2

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acid consumed, and (5) the efficiency of any mist control systems.
Emissions factors that can be used to estimate the quantity of hexavalent
chromium emitted from uncontrolled hard and decorative plating operations
are presented in Table 9-1.  These factors were derived from EPA source
tests conducted in Greenville, South Carolina, and Sterling Heights,
Michigan.

9.3      Methodology Options

    A reasonable method of estimating chromium emissions is based on
population density, because chromium electroplating operations are used
by many different industries and are usually located in centers of high
population density.  According to OAQPS 147,000 kg of hexavalent chromium
are emitted by electroplaters.  This estimate of 147,000 kg/yr of Cr
was calculated by OAQPS based on the emission factors provided in
Table 9-1, and assumed that hard platers had the following levels of
control:, scrubber (40%), fume suppressant (15%), mist eliminator (15%)
and uncontrolled (30%).  Decorative platers were assumed to have the
following levels of controls:  scrubbers (35%), fume suppressnat (50%),
and uncontrolled (15%).  It was also assumed that scrubbers are 95
percent effective in reducing Cr  emissions; mist eliminators are 85
percent effective; and fume suppressant, 90 percent effective.
    Based on the United States population of 2.265 x 10  thousand
persons,  the per capita quantity of chromium emitted annually can be
calculated at 6.5 x 10"1 kg Cr^/lOOO persons (1.4 x 10"1 Ib
Cr+ /I,000 persons).   The population of a given county can be obtained
from U.S. Census data and multiplied by this per capita emission factor
to estimate the amount of Cr   emitted from plating operations in the
county.
6/88         -.           CHROMIUM ELECTROPLATING                     9-3

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              Table 9-1 Uncontrolled Emission Factors  Used to Estimate
                  Emissions from Chromium Electroplating Operations
      Type of operation
mg/Cr /ampere
    hour
Basis
      Hard
                                 10
                     EPA source test  at
                     Carolina
                     Plating—Roll
                     Division plant  in
                     Greenville, South
                     Carolina.
      Decorative
                     EPA source test  at
                     C.  S. Ohm
                     Manufacturing
                     Company plant in
                     Sterling Heights,
                     Michigan.
       Based on the assumption that the fume suppressant used during the test
      controlled 80 percent of the misting.
      Source:  Reference 2.
6/88
                               CHROMIUM  ELECTROPLATING
                                                                                       9-4

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9.4    Example Calculation

    Given that a county has 33,345 residents, the chromium emission can
be estimated as follows:

Chromium emitted = 33.345 (thousand persons) x 1.4 Ib of Cr+6/1000 persons
                 = 46.7 Ib Cr+6 emitted annually.

9.5    Methods to Apportion Coimtywide Emissions from Chromium
       Electroplating
    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide emissions
be distributed within the study area into rectangular area source grid
cells reflecting spatial variations in activity and emissions.  Similarly
temporal in activities can be factored into the modeling to reflect
seasonal or diurnal fluctuations in emissions.  Modeling results would
then reflect on-going activities in that portion of the county, e.g.,
residential heating in the winter, commercial solvent usage during working
hours on weekdays.

    There are three alternative approaches that can be used in spatially
distributing emission:  (1) population, i.e'., the magnitude of emissions
within a grid are directly proportional to the population living in the
grid, (2) land area, i.e., emissions from a countywide area source are
assumed to be uniform throughout the county and are distributed based on
the size of the area source grid,  and (3) land use patterns, that assume
that certain area source activities, most likely occur in certain areas of
the county, e.g., commercial, residential or industrial.

    In apportioning emissions from chromium electroplaters any of these
methods may be appropriate.  Land area and population data can be readily
obtained, and applied as described in Appendix A.  Land use data,
6/88         "-           CHROMIUM ELECTROPLATING                     9-5

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available from the U.S. Geological Survey and other sources can be used in
combination with the spatial reolution for chromium electroplaters, to
distribute emissions based on the type of activity being performed, as
shown in Table 9-2.

    Estimated seasonal, daily and hourly temporal resolution for chromium
electroplaters are also included in Table 9-2, and can be used with the
countywide emissions data to estimate temporal variations.
6/88          -.          CHROMIUM ELECTROPLATING                     9-6

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                          Table 9-2 Spatial  and Temporal Resolution
                                 for Chromium Electroplaters
               Spatial Resolution
                 Surrogate indicator:       commercial  and industrial areas
                                          (codes 12,  13, and 15)
                 Information source(s);     land use maps

               Temporal Resolution:
                 Seasonal:                 uniform through the year
                 Daily:                    95 percent  Monday through Friday,
                                          5 percent Saturday
                 Hourly:                   80 percent  from 0700 to 1900,  20
                                          percent from  1900 to 2400, otherwise
                                          zero
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                                 REFERENCES
1.   U.S.  Environmental  Protection Agency.   Chromium Electroplating NESHAP
    Background Information Document.  Chapters 3 through 5.  Office of Air
    Quality Planning and Standards.  Research Triangle Park, NC.  February
    1987.

2.   U.S.  Environmental  Protection Agency.   Technical Paper: Chromium
    Electroplating (unpublished).  Office of Air Quality Planning and
    Standards. Research Triangle Park,  NC.   1985.
6/88          -.           CHROMIUM ELECTROPLATING                     9-8

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10.    HOSPITAL AND LABORATORY STERILIZERS

10.1   General

    Ethylene oxide (EO) is a highly toxic compound that is widely used as
a fumigant and sterilant.   It has been estimated that there are 7,000
potential  emitters and that U.S. hospitals alone emitted 400 to
                              1  2
450 metric tons of EO in 1976. '   Research laboratories emitted an
                                  2
additional 275 to 444 metric tons.   Types of equipment that use
ethylene oxide include vacuum chambers, atmospheric chambers,
ampule/liner bags, and sterijet systems.

    Vacuum chambers are pressure vessels, each with a vacuum pump that
removes air from the chamber prior to sterilization and removes the
EO/air mixture after sterilization.  Units vary in size and design.  For
example, small countertop models are primarily used in health care and
diagnostic facilities.  Generally, these models have capacities of less
than 0.1 m .  In hospitals, these units can be used in operating
rooms.  The EO is supplied to the unit by single dose cartridges or
pressurized cylinders.  Emissions occur when the EO is vented through a
                                            2
length of tubing directly to the atmosphere.

    Chambers from 0.1 m  to 2.8 m  are used primarily in hospital
central supply facilities.  Ethylene oxide is provided from .pressurized
cylinders.  Emissions occur when the chamber is vented directly to the
atmosphere.  Also, emissions may be mixed with water and routed to a
            2
sewer drain.

    Since atmospheric chambers do not evacuate air before treatment, a
longer sterilization time is usually required.  Ethylene oxide is
supplied as a gas mixture in a cartridge, and emissions occur when the
units vent their contents directly into the workplace.  Other units
reduce emissions by manually pumping the chamber contents through a
                   2
charcoal adsorbent.

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    Ampule/liner bags contribute to EO emissions.   In this method, the
article to be sterilized and a broken ampule of 100 percent EO are placed
in a plastic liner bag.  The bag is sealed and the EO escapes slowly into
               2
the atmosphere.
              •ป
    The sterijet system is used in hospitals and is similar to the
ampule/liner bag method.  In this system the article to be sterilized is
placed in a pouch.  It is attached to a gas delivery nozzle that draws a
slight vacuum on the pouch and then injects a premeasured amount of EO
mixture.   The pouch is heat sealed, and emissions  to the atmosphere occur
                                 2
as EO diffuses through the pouch.

    Other important emitters of EO are research laboratories.  It has
been estimated that in 1976, research laboratories used between 275 and
                                        2
444 metric tons  of EO for sterilization.   Emissions would result as
previously discussed for hospitals.

10.2     Emission Factors

    Whenever possible, emissions of ethylene oxide from sterilizers
should be treated as a point source.  Many of the emission factors and
procedures that  are described in this section can be applied to a single
laboratory or hospital.  When activity coefficients are available on a
point source basis, the preferred approach is to treat the source as a
point source, rather than an area source.  When facility-specific data
are unavailable, the source can be incorporated into the area source
inventory.

    Hospitals.  Emission factors for estimating ethylene oxide emissions
from hospitals were developed based on the results of a study by Midwest
Research Institute (MRI) to estimate chlorinated fluorocarbon (CFC)
emissions that resulted from sterilization procedures at
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hospitals.  Often, these sterilization processes use a mixture of
88 percent dichlorodifluoromethane (Freon ) and 12 percent ethylene
oxide (EO).  This mixture is referred to as "12/88."

    MRI estimated Freon  emissions program to evaluate nationwide
ethylene oxide emissions.  Based on their findings, 12/88 hospital usage
was divided into three categories:

(1) large hospitals (>500 beds), (2)  medium hospitals (200 to 500 beds),
and (3) small  hospitals (<200 beds).   Hospitals do not emit sterilant at
the same rate, and a linear regression analysis indicated that for the
data from the Section 114 responses,  12/88 emissions are most closely
related to the number of beds at the  hospital.  The following ethylene
oxide emission factors are presented  on a per bed basis:

         •  Large hospital               1.8 Ib/bed/yr
         •  Medium hospital              1.3 Ib/bed/yr
         •  Small hospital               1.7 Ib/bed/yr.

    An alternative method of estimating ethylene oxide emissions uses a
countywide per capita emission factor.  Assuming that
425 metric tons of ethylene oxide are emitted nationally, and that there
                                      8       3
is a national  population of 2.265 x 10  people , it is estimated that
ethylene oxide is emitted from hospitals at an annual per capita rate of
1.9 kg/1000 persons (4.2 lb/1000 persons).

    Research Laboratories.  As noted, research laboratories used 275 to
                                                            2
444 metric tons of ethylene oxide for sterilization in 1976.   It may
be difficult to determine the number'of individual laboratories in a
given county or city because they generally constitute a smaller
operation in a large company or institution.  For example, a
pharmaceutical manufacturer may have  a research laboratory associated
with its production facilities, and a teaching hospital can have
extensive research laboratory facilities.

6/88         ".    HOSPITAL AND LABORATORY STERILIZERS                10-3

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10.3     Methodology Options


    Hospital Emissions.  To estimate area source emissions of ethylene
oxide resulting from hospital  sterilization, the following steps are
recommended:

    (1)    Determine the number of hospitals in each county, and the
           number of beds in each hospital.  This information can be
           located in the American Hospital Association Guide to the
           Health Care FieTd"?*

    (2)(a) Estimate the annual quantity of ethylene oxide emitted by
           multiplying the emission factors times the number of beds in
           each hospital, or

       (b) Survey the individual hospitals in the receptor area to
           determine the amount of ethylene oxide that was purchased and
           used.  Conservatively, it can be assumed that all EO used is
           emitted to the atmosphere.  Emissions from hospitals could be
           treated as an area source and summed.  Emissions from large
           hospitals can be treated as point sources for modeling
           purposes, if so desired.


    Laboratory Emissions.  Laboratories tend to be located in urban areas
of high population density; a reasonable method of estimating area source
emissions from these facilities is to use a per capita emissions factor.


    Assuming a median value of 360 Mg of EO is consumed and emitted
annually by research laboratories, and a national population of 2.265 x
10  thousand persons, an annual emission factor can be calculated to be
1.6 kg/1000 persons/yr (3.5 lb/1000 persons).2'4
    County and city population data can be obtained from the U.S. Bureau
of Census.  The population of a particular county or city can then be
multiplied by the per capita emission factor to estimate a countywide
emission of ethylene oxide from laboratories.
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10.4     Example Calculations

Example Calculation 1

    EO emissions from hospitals are calculated as follows.

    The study area has five hospitals.  One is a large facility with 530
beds and a 75 percent annual occupancy.  Another is a medium-sized
facility of 450 beds and a 70 percent occupancy.  The remaining three
hospitals are small facilities having 125, 150, and 165 beds, with
percent occupancies of 73, 78, and 82 percent, respectively.
    Ethylene oxide emissions can be estimated for the large hospital as
follows:
         530 beds x 1.8 Ib EO/bed/yr =   954 Ib EO/yr.
Ethylene oxide emissions can be estimated for the medium hospital as
follows:
         450 beds x 1.3 Ib EO/bed/yr =   585 Ib EO/yr.
EO Emissions from the small hospitals can be estimated as follows:
                   125 x 1.7 Ib EO/bed/yr = 213 Ib/yr
                   150 x 1.7 Ib EO/bed/yr = 255 Ib/yr
                   165 x 1.7 Ib EO/bed/yr = 281 Ib/vr
                                    Total = 749 Ib/yr
The total EO emission can be determined by adding the quantity emitted by
the large hospital, the quantity emitted by the medium hospital,  and the
total  annual quantity of EO emitted by small  hospitals, 954 + 585 + 749
or 2,288 Ibs EO/yr.
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Example Calculation 2
    EO emissions from laboratories are calculated as demonstrated.
    If a county has a population of 219,368 persons, the area source
emission of EO from laboratories can be estimated as follows:
    EO Emissions = 219 (1,000 persons) x 1.6 kg EO/1000 persons/yr
                 = 350 kg EO/yr.

10.5   Methods to Apportion Countvwide Emissions

    As described in Section 1.0 and Appendix A when performing air
dispersion modeling, it is generally recommended that countywide
emissions be distributed within the study area into rectangular area
source grid cells reflecting spatial variations in activity and
emissions.  Similarly temporal  in activities can be factored into the
modeling to reflect seasonal or diurnal fluctuations in emissions.
Modeling results would then reflect on-going activities in that portion
of the county, e.g., residential heating in the winter, commercial
solvent usage during working hours on weekdays.
    There are three alternative approaches that can be used in spatially
distributing emission:  (1) population, i.e., the magnitude of emissions
within a grid are directly proportional to the population living  in the
grid,  (2) land area, i.e., emissions from a countywide area source are
assumed to be uniform throughout the county and are distributed based on
the size of the area source grid,and (3) land use patterns that assume
that certain area source activities, most likely occur in certain areas
of the county, e.g., commercial, residential, or industrial.
    In apportioning emissions from sterilizers, any of these methods may
be appropriate.  Land area and population data can be readily obtained,
and applied as described in Appendix A.  Land use data, available from
the U.S. Geological survey and other sources can be used in combination
with the spatial resolution for hospitals and laboratories to distribute
emissions based on the type of activity being performed, as shown in
6/88          :    HOSPITAL AND LABORATORY STERILIZERS                10-6

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Table 10-1; hospitals can, in fact, often be identified on topographical
or street maps and may be treated as point sources in the inventory..
    Estimated seasonal, daily, and hourly temporal resolution for both
categories of sterilizers are also included in Table 10-1, and can be
used with the annual countywide emissions data to estimate temporal
variations.
6/88         -.    HOSPITAL AND LABORATORY STERILIZERS                10-7

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                      PROCEDURES  FOR ESTIMATING AND-ALLOCATING
                         AREA  SOURCE  EMISSIONS  OF AIR  TOXICS
                       Table  10-1 Spatial and Temporal  Resolution of Countywide
                       Emissions Totals  for Hospital  and Laboratory Sterilizers
              Hospital Sterilizers

                  Spatial Resolution
                     Surrogate indicator:

                     Information source(s):
                  Temporal Resolution
                     Seasona1:
                     Daily:
                     Hourly:

              Laboratory Sterilizers
                       identify hospitals on maps or
                       commercial areas  (code 12)
                       land use map and  U.S.6.S.  topographical
                       maps, street maps
                       uniform through the year
                       uniform through the week
                       uniform through the day
                  Spatial Resolution
                     Surrogate indicator:

                     Information source(s):
                       commercial (code  12) and industrial and
                       commercial complexes (code 15)
                       land use maps
                  Temporal Resolution
                     Seasonal:
                     Daily:
                     Hourly:
                       uniform through  the year
                       90% Monday through Friday;  10%  Saturday
                       uniform from 0800 to 2400;  otherwise
                                              zero
6/88
HOSPITAL  AND  LABORATORY  STERILIZERS
10-8

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                 REFERENCES
1.  Memorandum:  Baseline Freon 12 Emission Estimates from Hospital
    Sterilization Processes.  MRI Project No. 8662-k.  From Bruce
    Nicholson to Neil Patel.  U.S. Environmental Protection Agency.
    Office of Air and Radiation.   Washington, DC. 1986.

2.  Radian Corporation.  Locating and Estimating Air Emissions from
    Sources of Ethvlene Oxide.  EPA-450/4-84-0071.  U.S. Environmental
    Protection Agency, Office of Air QuaTity Planning and Standards.
    Research Triangle Park,  NC. 1984.

3.  U.S. Department of Commerce.  Census of Population 1980 Number of
    Inhabitants. Part 1.  United States Summary.  Bureau of the Census.
    Washington, DC. 1983.

4.  American Hospital Association.  American Hospital Association:  Guide
    to the Health Care Field;  Chicago, IL.
6/88         .     HOSPITAL AND LABORATORY STERILIZERS                10-9

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
                                 APPENDIX  A

A.  METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS

    In order to perform air dispersion modeling, it is generally
recommended that countywide area source emissions are distributed within
the study area into rectangular area source grid cells and that spatial
and temporal variations of area source emissions are defined within the
grid.   By spatially and temporally apportioning countywide area source
emissions, modeling results will reflect on-going activities in that
portion of the county, e.g., residential heating in the winter, or
commercial solvent use on weekdays.

    Note that methods used in selecting the area source grid boundaries
are not addressed in -this Appendix; it would suffice to say that the
boundaries are somewhat subjective, and are established based on the
level  of detail in the inventory, the boundaries of the study area, the
requirements of the air dispersion model and the resulting data analysis.

    Two methods are commonly used to spatially distribute countywide
emissions to area source grids.  In some cases, the area source emissions
can be determined directly from the area source activity within the grid
cell.   The most frequently used method, however, is to apportion the
countywide emissions to the grid cell level  by assuming that the
distribution of the area sources behaves similarly to that of a surrogate
indicator.  Often these spatial apportionment factors are generic in
nature, i.e., they are based on "typical"  national  data.  Obviously,
site-specific data are preferred, when available.

    Temporal apportionment, on the other hand, is usually based on
typical seasonal, weekly, and daily operating schedules.

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                  PROCEDURES  FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
A.I      Direct Determination of Emissions within an Area Source Grid

    This method is often used when data are available on the location of
individual minor facilities that comprise an area source category.  For
example, a local gas company may have information on the quantity of
natural gas consumed in every household or commercial facility, or a
survey can identify the locations of commercial or industrial facilities
such as dry cleaners or service stations.  These data can be compiled by
surveying facilities within an industrial category, using the telephone
Yellow Pages, Dunn and Bradstreet's Electronic Yellow Pages  . zip code
                              2
locations, the Thomas Registry , or other sources.  Emissions can then
be calculated at the grid cell level, resulting in emission estimates
that better reflect variations within the county.

A.2      Spatial Apportionment

    The selection of apportionment factors for a given area source
category depends on the spatial distribution of the emissions and on what
other information is available.  In most cases, data are not readily
available to directly estimate area source emissions at the grid level.
As a result, default or "surrogate" indicators can be identified that
reflect activity and emission rates at the grid cell level.  These
surrogate indicators can then be used to apportion grid all emissions to
the basic countywide Inventory.  Variables often used as surrogate
indicators of area source activity include land area, land use
parameters, employment in various industrial and commercial sectors and
population.  Appropriate surrogate indicators for each area source
category  (Sections 2.10) are presented in the appropriate section of the
manual.
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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
       Spatial Apportionment Based on Land Area


    Land area (e.g., square mileage, acres) can be used as a surrogate

indicator for those area source categories where the activity level is

typically uniform across the study region.  The step-by-step procedure,
described below, is based on the assumption that source emissions are

directly proportional  to land area.


    1. Estimate the area of the study region.

       If the study region is a unique geographic entity (i.e., city or
       county) this information is often available from a local or state
       government agency.  If the study region is not so easily defined,
       however, the areas must be estimated manually.  A planimeter is a
       tool frequently used to accomplish this task.

    2. Overlay the chosen grid system onto the study region and estimate
       the area of each grid cell.

       A planimeter is again useful for this procedure.  If the area grid
       cell extends beyond the study region, only the cell area that is
       within the study region should be considered in the apportionment
       process.

    3. Apportion the area source emissions within the grid cell according
       to land area.

       Because area source emission estimates are typically available on
       a county level, it is best to proceed with the .allocation process
       on a county-by-county basis.  The area source emissions within
       each grid cell  are apportioned according to the percentage of the
       respective total county land area the grid cell occupies.  (For
       example, if .05 percent of the land area of County A resides in a
       grid cell, then .05 percent of the area source emissions of County
       A are apportioned to the grid cell.)  This relationship can be
       expressed mathematically as follows:

         	Area Within Grid	  =  	Country Area	
         Grid Cell Area Source Emissions     Total County Area Source
                                             Emissions.


This methodology is illustrated in Example Calculation #1, Section 3.5.1.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-3

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    The major advantage of this methodology is its simplicity.  It is
relatively easy to obtain all the information necessary to accomplish
this method of apportionment.  It should be noted, however, that the
method assumes that emissions are uniform across the country or study
region; in reality, even for source categories that are relatively
uniform across a region there tends to be clustering a't distinct
geographical locations (i.e., gasoline stations are often found at
intersections).

       Spatial Apportionment Based on Population Density

    The spatial distribution of many area source emissions such as those
from residential heating is proportional to population density within the
study region.  As a consequence, countywide area source emissions are
frequently assigned to the grid cell level by using population density as
a surrogate indicator.  This methodology is described in the following
steps:

    1. Obtain population density information and a census tract
       identification map for the study region.
       Population data statistics are assembled according to census
       tracts.  The data and the census tract identification maps for the
       study region can be obtained from the U.S. Department of Commerce,
       Bureau of the Census or any current census almanac publication.
    2. Overlay the chosen grid onto the census tract map and estimate the
       area of the census tracts and each grid cell.
       A planimeter is frequently used to estimate these areas.  At this
       point, it is important to closely identify those grid cells or
       portions thereof that lie within each county comprising the study
       area.
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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    3. Apportion population within a grid cell  according to the
       percentage of 4he area of the respective census tract that the
       grid cell occupies.  (For example, if the area of the grid cell
       occupies 50 percent of the area of a census tract, then it is
       assumed that 50 percent of the population of that census tract
       lies within the grid cell.)

       Special attention is required when determining the population of
       those grid cells which overlap two or more population census
       tract.  In those cases, the area of the grid cell that lies within
       each census tract and the corresponding population within that
       area must be computed separately.   These population estimates must
       then be summed to estimate the total population of the grid cell.

    4. Apportion the area source emissions for the study area by grid
       cell population density.

       Because area source emission estimates are typically available on
       a county level, it is best to proceed with the allocation process
       on a county-by-county basis.  The area source emissions within
       each grid cell are apportioned according to the percentage of the
       respective county population'residing in the grid cell.  (For
       example, if .05 percent of the population of County A resides in a
       grid cell, then .05 percent of the area source emissions of County
       A is apportioned to the grid cell.)  This relationship can be
       expressed mathematically as follows:

        Population Within Grid      =   	County Population	
    Grid Cell Area Source Emission      Total County Area Source Emission.

This methodology is illustrated in Example Calculation #2, Section 3.5.2.


    The obvious advantage of this approach lies in the simplicity of the
methodology and the availability of the information needed to perform the
procedure.   This method is quite useful for those source categories such
as residential heating that can be spatially related to population
density.  The primary weakness of this approach is the assumption that
emissions are proportional to population.  While this is true for many

source categories, some categories such as degreasing or industrial
heating, are not necessarily concentrated in the more densely populated
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-5

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
areas.   Other categories such as forest fires may,  in fact,  be inversely
proportional to population density.  A second major disadvantage lies in
the assumption that population density is uniform throughout the census
tract.

       Spatial Apportionment Based on Land Use Patterns

    Land use patterns can serve as a useful surrogate indicator of the
spatial distribution of area source emissions because they provide a more
accurate picture of the "real world" situation.  Frequently, pollution
sources are located in low population areas such as industrial parks.
Local ordinances may dictate the location of certain types of industries
or businesses.  This clustering of area sources results in concentrations
of certain types of sources in specific sections of a study area.  For
example, small dry cleaners, a source of perchloroethylene,  are typically
found in commercial areas, whereas domestic heating emissions are common
to suburban and urban residential areas.

    A prerequisite for using this approach is the availability of land
use data.  The U.S. Geological Survey (USGS) maintains a comprehensive,
computerized data base of information on land use distributions
throughout the country.  One of the basic sources of land use compilation
data for the USGS is the NASA high latitude U-2/RB-57 aerial
photocoverage, usually at macroscales.   This land use and land cover
data compilation is based upon the classification system of land use and
cover shown in Table A-l.

    State and local governments frequently compile land use maps for
urban areas that are, in some instances, more current, more detailed, and
less costly than the USGS survey land maps.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-6

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    Historically, land use data have been presented on topographical
maps; however, much of these data have, in recent years, been
computerized.  USGS now compiles digital data, for many regions in the
country, in terms of 200 meters x 200 meters (4 hectare) grid cells.

    For ease of transfer and readability, USGS data files also are
available in a character-coded format.  These data files contain records
of each individual  grid cell and provide the following information:

       •  UTM zone number;
       •  UTM Easting value in meters;
       •  UTM Northing value in waters;
       •  Land use and land cover attribute code (see Table A.2-1);
       •  Political unit code;
       •  USGS hydro!ogic unit code;
       •  Census county subdivision or SMSA tract code;
       •  Federal land ownership agency code; and
       •  State land ownership code.

    The standard character-coded grid cell data files will have only grid
cell records for which at least one of the categories is coded.
Apportionment of areawide emissions according to land use patterns
requires the manipulation of enormous amounts of data.  There are
frequently 500,000 to 1,000,000 four-hectare grid cells in a study area.
Data manipulation of such magnitude can be achieved only by using a
computer.

    Land use data are compiled at four Levels (I through IV) with
increasing levels of detail.  For environmental  analyses, however, Levels
I and II provide sufficient detail  for categorizing pollution source
distribution.  A more complete description of USGS land use categories
can be found in Reference 3.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-7

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                PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                   AREA  SOURCE  EMISSIONS  OF  AIR TOXICS
                                 Table A-l  Land Use Categories
           1.  URBAN OR  BUILT-UP LAND
              11 Residential
              12 Commercial and Service
              13 Industrial
              14 Transportation, communtcat ions
                  and services
              15 Industrial and
                  commercial complexes
              16 Mixed  urban or
                 built-up  land
              17 Other  urban or built-up
                  land

           I.  AGRICULTURAL  LAND
              21 Cropland  and pasture
              22 Orchards,  groves, vineyards,
                  nurseries, and ornamental
                  horticultural groves
              23 Confined  feeding operation
              24 Other agricultural land

           3.  RANGELAND
              31 Herbaceous range land
              32 Shrub and brush  range land
              33 Mixed range land

           4.  FOREST LAND
              41 Deciduous forest land
              42 Evergreen forest land
              43 Mixed forest  land

           5.  WATER
              51 Streams and canals
              52 Lakes evergreen
              53 Reservoirs
              54 Bays and  estuaries

           6.  WETLAND
              61 Forested  wetland
              62 Nonforested wetland
                                      BARREN LAND
                                      71  Dry salt flats
                                      72  Beaches
                                      73  Sandy areas, other
                                      75  Strip mines, quarries,
                                          and gravel pits
                                      76  Transitional areas
                                      77  Mixed barren land

                                      TUNDRA
                                      81  Shrub and brush tundra
                                      82  Herbaceous tundra
                                      83  Bare ground
                                      84  Wet tundra
                                      85  Mixed tundra
                                      PERENNIAL  SNOW OR ICE
                                      91 Perennial snow fields
                                      92 Glaciers
           Source:  Reference 3
6/88
METHODS TO APPORTION COUNTYWIDE  AREA SOURCE  EMISSIONS
A-8

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
    The basic steps to the apportionment procedure are as follows:


    1.  Compute or obtain county-specific area source emissions.   This
       information can usually be obtained from local  and state
       government agencies.

    2.  Identify the total  number of land use grid cells in the county by
       land use category.

    3.  Identify the area grids lie within the county.

    4.  Compile a grid cell/area source grid matrix.

       Land use fractions  for each area grid are computed for the various
       land use categories.   This information is then  combined with the
       data assembled in steps 1 through 3 above and compiled into a
       matrix format.  An  example of this type of matrix is shown in
       Table A-2.

    5.  Allocate area source  emission fractions into  land use categories.

       This step requires  the compilation of a land  use/area source
       matrix.  Table A-3  is an example of this type of matrix.   The
       creation of this matrix should be based upon  source distributions
       found in the literature in combination with  engineering  judgment,
       as needed.  Emissions from residential heating, for example, can
       be totally assigned to the residential land use category.   Dry
       cleaning emissions, 90 percent of which come  from coin-operated
       and commercial dry  cleaners,4 can be distributed proportionately
       to the commercial and services land use category.  Surface coating
       emissions can be distributed between five urban categories, all of
       which paint and coat  surfaces.  A sixth urban category, "mixed
       urban," is typically  redistributed equally among Categories 11,
       12, 12, 14, 15, and 17.  Site-specific characteristics, if
       available, should be  used in the development  of this matrix.

    6.  At the area source  grid level in a county, for  each area  source
       category and each pollutant, multiply the county area source
       emission by the land  use fraction of Step 4 and the emission
       fraction of Step 5  to obtain land use emissions.

       The two matrices, when multiplied, are transformed into a product
       matrix that defines the fraction of the area  source emissions is
       assigned to each area source grid.  This fraction is then
       multiplied by each  pollutant total in the countywide emission
       inventory to determine the apportionment of each pollutant to each
       area grid cell.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-9

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                   PROCEDURES  FOR ESTIMATING AND  ALLOCATING
                      AREA SOURCE EMISSIONS OF AIR TOXICS
                Table A-2  Example of Grid Cell/Area Source Grid Matrix
Land Use Category
Resident lal

Com. & Services

Industrial

Trans., Com.. & Services

Ind. & Com Complex

Mixed Urban

Other Urban

Streams & Canals

Lakes

Reservoirs

Bays & Estuaries

All Other

Area 02
3774
53.6
797
63.8
276
59.2
261
61.1
166
57.6
133
75.1
357
32.5
100
68.5
0
0.0
48
76.2
0
0.0
15510
88.1
Area 06
820
11.7
82
6.6
119
25.5
60
14.1
• 0
0.0
5
2.8
243
22.2
46
31.5
0
0.0
9
14.3
0
0.0
993
5.6
Area 07
1034
14.7
159
12.7
44
9 4
79
18.5
80
27.8
16
9.0
184
16.8
0
0.0
0 •
0.0
5
7.9
0
0.0
777
4.4
Area 11 County total
1409 7037
20.0
212 1250
17.0
27 466
5.8
27 427
6.3
42 288
14.6
23 177
13.. 0
313 1097
28.5
0 146
0.0
0 1
0.0
1 63
1.6
0 1
0.0
326 17606
1.9
6/88
METHODS TO  APPORTION COUNTYWLOE AREA SOURCE  EMISSIONS
A-10

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               PROCEDURES  FOR  ESTIMATING AND ALLOCATING


























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6/88
METHODS TO APPORTION  COUNTYWIDE AREA SOURCE  EMISSIONS
A-ll

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    An example calculation using this procedure is presented as Example

Calculation 3, Section A. 5.


    An alternative approach is based on extracting data directly from..

land use maps.  In this approach, the surrogate indicator is the area in
the study region devoted to each land use zone.  Key assumptions in this
methodology are that (1) area source activity is uniformly distributed
throughout land use zones, and (2) the area of the grid cell devoted to a

particular land use code is a true indication of the magnitude of the

area source emissions within that grid cell.  The basic steps in this

alternative procedure are summarized below.


    1. Identify the total countywide emissions of the area source
       categories under study.  These estimates can usually be obtained
       from local and state governmental offices or can be estimated from
       available area source activity data.

    2. Identify the land use code in which the activity of a particular
       area source category would be likely to occur.  An example of this
       association is to assume that dry cleaning activities would be
       most likely to occur in a commercial land use zone.

    3. Superimpose the grid system network on the land use map and
       estimate the area of each grid cell devoted to each land use code.

    4. Estimate the emissions from each grid cell as a simple fraction of
       the total as follows:

         E1 = Et (Si/St)

         where
         E =  area source emissions;
         S =  surrogate indicator;
         i =  the value in grid cell; and
         t =  the total for the county or region
                 is' known as the "apportioning factor."
    The units for the surrogate indicator(s) can be arbitrary  (i.e.,
percent of grid cell, square kilometer, square mile).
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-12

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
    An example of this apportionment method is shown in Example 4,
Section A.5.

    The discussion above is applicable for apportioning area source
emissions based on a single land use surrogate indicator.  In some cases,
more than one indicator may be used for an area source emission
apportionment.  For example, miscellaneous solvent use can be associated
with the two consumer (residential and commercial) land use categories
(land use codes 11 and 12).

    There are two principal ways to manage this type of apportionment.
The first approach is to estimate solvent emission subtotals for the two
types of land use involved; then each of these subtotals is apportioned
according to the corresponding land use areas.  This action creates two
new emission subcategories where the countywide inventory may have had
only one.  For example, one-half of the miscellaneous solvent emissions
could be assigned to multifamily residences (land use 11) and one-half to
commercial and service use (land use 12).  Hence, if countywide emissions
from miscellaneous solvent use are 12 tons per day, 6 tons per day would
be apportioned at the grid cell level for each of these
subcategories,based on the distribution of the corresponding surrogate
indicator.  Alternatively, the relative intensity of solvent use in the
two types of areas could be estimated.  For example, it can be assumed
that residential areas have one-third the emission rate per unit area of
commercial and service areas.  In this case,  the apportioning factors
would be calculated using an appropriate weighting factor for the two
types of land use.  This would be expressed,  mathematically, by the
equation:
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-13

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE  EMISSIONS  OF  AIR TOXICS

fik =
j =
2
2 Wjksij
1
n
2
i = 1
2
2
j =

Wjksij
1
       where

       f^ - apportioning factor
       W-K = the weighting factor selected for land -use type j in
       relation to source category k.

       S,, = the value of the surrogate indicator (i.e.,  the area) of
        ' J
       land use type j in cell.

    The summation term appearing in the numerator is essentially a
composite surrogate indicator for the  entire category.   Consequently, if
solvent emissions are weighted according to the previous  suggestion (W-,
= 1, Wซ = 3) and the respective areas  in a given grid cell are 0.6 and
0.4, then the value of the composite surrogate indicator for that cell is
(0.6 x 1)  + (0.4 x 3), or 1.8-   The countywide emission for the category.
is then apportioned based on this composite surrogate indicator.

    The above methodology can also be  implemented using traffic
zone-level demographic statistics.

    State and local transportation planning agencies often compile data
on employment and other demographic statistics for urban areas.  These
data, which are frequently aggregated  at the zonal level, can be used in
lieu of land use maps to define surrogate indicators for area source
apportionment.  These zonal statistics are usually much more detailed in
data characterization than are land use data.  For instance, zonal
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-14

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
statistics in a particular urban area may typically be compiled for five

or more commercial and industrial subcategories, whereas the

corresponding land use maps may only identify generalized commercial and

industrial land uses.


    Reference 5 discusses this approach in greater detail.


A.3      Mobile Source Apportionment


    Several methods are currently available to apportion emissions from

mobile sources.  Each methodology is discussed below.


       Apportionment Based on Vehicle Miles Traveled


    Vehicle Miles Traveled (VMT) data can .be effectively used as a

surrogate indicator to allocate mobile VOC emissions to the grid cell

level  for modeling purposes.   State and local traffic agencies usually

compile VMT data disaggregated into traffic zones.  In most cases, these
data are readily available for most metropolitan areas.  The basic steps
in the allocation procedure are illustrated below: an example of this
procedure is presented as Example Calculation #5; Section 3.5.5.

    1. Obtain countywide or study area VMT and mobile VOC emissions data
       from state or local agencies.  These data are typically compiled
       according to vehicle type and pollutant species.  VOC emissions
       are also frequently categorized as either evaporative or exhaust
       and are emanating from either gasoline or diesel fuels.

    2. Obtain traffic zone VMT data from local or state agencies and
       determine the total VMT for each grid cell.  This is accomplished
       by summing the VMT data for all  the traffic zones lying within
       each grid cell.  If only a portion of a traffic zone lies within
       the grid cell, apportion VMT's within the cell in proportion to
       the area of the traffic zone lying within the grid cell (i.e.,  if
       10 percent of the traffic zone lies within the cell apportion
       10 percent of the traffic zone's total VMT to the grid cell).  A
       planimeter can be used to estimate the area of the traffic zones.
       In some cases, area estimation can be done by sight.
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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF  AIR TOXICS
    3.  Determine the apportionment factor for each grid cell.   The
       apportionment (A-j)  is defined by the following equation
         A1  = VMTi/VMTt
         where VMT-j  is the VMT within the grid cell and VMTt is the
         total VMT for the study area.
    4.  Apportion VOC emissions to each grid cell  by multiplying the
       apportionment factor by the total  county/study area mobile VOC
       emissions.  The apportionment factor is further multiplied by each
       pollutant-specific  subtotal of the county/study area mobile VOC
       emissions data to create a speciated VOC data base for each grid
       cell.

       Apportionment Based on MOBILES
    As mentioned in Section 4, MOBILES is a computer program that
calculates emissions of hydrocarbon (HC), carbon monoxide (CO), and
oxides of nitrogen (NO ) from highway motor vehicles.  MOBILES can be
adapted to apportion the estimated emissions into designated area grids
for modeling purposes.  The best sources of data for input into the model
(i.e., VMT distribution, driving patterns) are local and state
transportation planning commissions and other related organizations.
Emissions can then be each estimated for grid within a county.  For
further information on MOBILES, the reader is directed to User's Guide to
MOBILES (Mobile Source Emissions Model).

    The VMT approach to apportionment is an effective screening tool for
mobile emission estimates; however, driving patterns and vehicle speed
are not considered in estimating emissions, which is a major drawback.
MOBILE4 estimates mobile emissions in a much more sophisticated manner
taking into account both driving patterns and vehicle speed.  Mobile
emissions are categorized as evaporative or exhaust, resulting in a more
real life representation of pollutant production.  A second major
advantage of MOBILES is that mobile emissions are directly apportioned
into area source grids.
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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
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    The sophisticated nature of MOBILES demands that persons familiar
with the program must conduct the modeling exercise.  In addition,
obtaining the extensive data needed as input into the model, if not
readily available from a local or state transportation commission, can be
time consuming and expensive.  In contrast, the Vehicle Miles Traveled
approach, while less accurate, can be performed more easily by
individuals not familiar with the MOBILES model.
                                      ซ
A.4      Temporal Distribution of Countywide Emission Estimates

    The countywide emission values used in the apportionment process
above are typically available only as annual or perhaps seasonal
estimates.  In order to more effectively use the data for modeling
purposes, it must be translated into hour-by-hour emission rates.

    If only annual emission estimates are available, the first step in
this process is to estimate the seasonal component of activity for each
area source.  For many sources, activity is fairly constant from season-
to season, whereas for some sources, a strong seasonal component will be
evident. _Degreaser operations is an example of the former category where
activity is fairly constant throughout the year.  Conversely, emissions
from residential heating will occur primarily in the colder winter
months.

    Once the seasonal component is known, the daily component should be
determined.  Again, some area source activities are relatively constant
from day to day, thereby simplifying the estimation process.  For
example, gasoline storage losses and natural gas leaks can be assumed to
be uniform over the week.  On the other hand, many work-related area
sources are more active on weekdays.  Examples include dry cleaning
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-17

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
plants and degreasing operations where activities are concentrated from
Monday through Friday (or Saturday in some cases).   The seasonal
activity for these sources should be distributed only to those days on
which the source is active.  For instance, if dry cleaning emissions for
the county are 312 tons of solvent over a 92-day period from July to
September, and most plants typically operate 6 days a week (for a total
of 78 operating days), then daily emissions from dry cleaning would be 4
tons (312 + 78).  This daily rate would not be applicable to a
Sunday.

    After the daily activity level has been determined for each area
source, the final step is to estimate hourly emissions.  This is
generally accomplished by applying a 24-hour operating pattern to the
daily activity level.  The 24-hour operating pattern can be obtained from
onsite measurements, survey data, or engineering judgment.  To
illustrate, dry cleaning establishments generally operate from 7 a.m. to
5 p.m., Monday through Saturday, with uniform emissions throughout the
period.  Given a countywide daily emission rate of 4 tons, the hourly
emission would be .36 tons (4 -=• 11).

    Temporal resolution methodologies for various area source categories
are presented in the manual in Sections 2 through 10.

A.5      Example Calculations

    Example calculations of selected area source apportionment
methodologies are provided.  The examples presented are somewhat
simplistic to better illustrate the fundamental steps of each methodology.
6/88      METHODS TO APPORTION COUNTRYWIDE AREA SOURCE EMISSIONS      A-18

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                  PROCEDURES  FOR  ESTIMATING  AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
       Example Calculation 1

    Estimate area source spatial apportionment using land area as a
surrogate indicator.

    County A has an area of 1472 square miles.  For purposes of air
dispersion modeling, the county has been divided into two area source
grids.  Using a planimeter, the square mileage of the grid is estimated
to be as follows:
                   Area	         % of Area
    Grid 1    962 square miles            65
    Grid 2    510 square miles            35

    Emissions of benzene from gasoline marketing are estimated to be 11
MT/yr and emissions of formaldehyde from heating area sources is
estimated to be 75 MT/yr.

    The emissions are apportioned using the methodology described in
Section A.2.1, as follows.

    Benzene
    Grid 1                   (11 MT/yr) x (.65) = 7 MT/yr
    Grid 2                   (11 MT/yr) x (.35) = 4 MT/yr

    Formaldehyde
    Grid 1                   75 MT/yr x (.65) = 49 MT/yr
    Grid 1                   75 MT/yr x (.35) = 26 MT/yr
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-19

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
       Example Calculation 2

    Estimate area source spatial  apportionment using population density
as a surrogate indicator.

    County A, USA has a population of 354,000 people.  For purposes of
modeling the county has been divided into three area source grids with
the following populations estimated based on census tract data.
    Grid 1
    Grid 2
    Grid 3
          Population
           193,000
           120,000
            41,000
% of County Population
          55
          34
          11
    Total emissions from area sources of perchloroethylene from dry
cleaners is estimated to be 73 MT/yr and trichloroethylene emissions from
degreasers are 49 tons/yr.

    The emissions are apportioned using the methodology described in
Section A.2.2 as follows.

    Perchloroethylene
    Grid 1
    Grid 2
    Grid 3

    Trichloroethvlene
                   (73 MT/yr)  x (.55)  = 40 MT/yr
                   (73 MT/yr)  x (.34)  = 25 MT/y,r
                   (73 MT/yr)  x (.11)  -  8 MT/yr
    Grid 1
    Grid 2
    Grid 3
                   (49 MT/yr) x (.55) = 27 MT/yr
                   (49 MT/yr) x (.34) = 17 MT/yr
                   (49 MT/yr) x (.11) -  5 MT/yr
6/88
METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS
                              A-20

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
       Example Calculation 3


    Sample calculations are provided below for apportioning emissions

from dry cleaning operations in County A, USA, utilizing the surrogate

land use matrix methodology.  It is estimated that 162 MT/yr of

perch!oroethylene are emitted from area source dry cleaners.
Step 1
                                       Number of Grid Cells in
    Land Use Category                      Land Use .Category

    Residential                                2,799
    Commercial  and Services                     618
    Industrial                                    78
    Transportation, Communications,
      and Services                              348
    Industrial  and Commercial
      Complexes                                    1
    Mixed Urban*                •                  3
    Other Urban                                  128
    Streams and  Canals                          233
    Lakes                                        61
    Reservoirs                                   519
    Bays and Estuaries                          652
    All  Other                                53,480
Step 2

       Area Grid Cells 22 and 23 lie within this county.
       * Mixed Urban grid cells in Area Source 22:   3
                                   Area Source 23:   0

    The reallocation of the above grid cells will not change the county

and area grid distributions.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-21

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Step 3
Land Use Category
            Area Source  22
            Grid Cells %
Area Source 23
Grid Cells %
Residential            2107    75.3
Commercial and
 Services               363    58.7
Industrial               75    96.2
Transportation,
 Communication,
 and  Services          136    39.1
Industrial and
 Commercial Complexes
Other Urban
Streams and Canals
Lakes
Reservoirs
Bays and Estuaries
All Other
Step 4
    For dry cleaning, emission fractions
                                  692

                                  255
                                    3

                                  212
         24.7

         41.3
          3.8

         60.9
County Total
Grid Cells %
2799

 618
  78

 348
100

100
100

100
1
97
9
- 24
285
29
34584
100
75.8
3.9
39.3
54.9
4.4
64.7
0
31
224
37
234
623
18896
0
24.2
96.1
60.7
45.1
95.6
35.3
1
128
233
61
519
652
53480
100
100
100
100
100
100
100
                               from various land use categories
are:
    Commercial and Services:   90%
    Industrial:                 5%
    Industrial and Commercial
      Complexes:                5%
6/88
METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS
                           A-22

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Step 5
    Area Source Grid 22        Perchloroethvlene
Commercial and Services = 162 MT/yr x 58.7 x   90
                                       100    100
                        =85.6 MT/yr.
Industrial              = 162 MT/yr x 96.2 x    5
                                       100    100
                        =7.8 MT/yr
Industrial and Commercial
  Complexes             = 162 M.T./yr x 100 x 	5_
                                        100   100
                        = 8.1 M.T./yr.
Therefore, total perchloroethylene emissions from Area Source Grid 22
                        = 85.6 + 7.8 + 8.1 = 101.5 MT/yr
Similarly, in Area Source Grid 23,
       Perchloroethylene emissions = 60.5 MT/yr.
       Example Calculation 4
    Example calculations are provided below for apportioning emissions
from dry cleaning operations in County B, USA, utilizing an alternative
surrogate land use methodology.  It is estimated that 100 MT/yr of
perchloroethylene are emitted by area source dry cleaners.  Refer to
Figure A-l.
Step 1   Surrogate Land Use Codes
                       12:  Commercial
                       15:  Industrial and Commercial Combined
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-23

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                 PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                   AREA SOURCE EMISSIONS'OF AIR TOXICS
 26
     1   2
         5   6   7  8   9  10 11  12  13  14 15  16 17  18  19  20
SOURCE:  Reference 5
                           Figure A-l LAND USE MAP
6/88
METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS
A-24

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Steps 2 and 3


                           For Grid Cell (15, 15)
                           S, = .20 grid cells (20 percent of the area
                           is indicated as commercial/industrial)


                           St = 26.3 grid cells


                           (Si/St) for grid cell (15, 15) = .0076
                           Ei = (100) (.0076) = .76 MT/yr


       Example Calculation 5


    A county is divided into two grid cells for air dispersion modeling.
The following example apportions mobile emissions data resulting from
gasoline consumption from light duty vehicles (cars and light trucks) in

Grid Cells 931 and 932.


    Total county emissions by pollutant (MT/yr), using the methodology
provided in Section 4 are as follows:
Acetaldelyde
Asbesto|
Benzene
Benzo(a)pyrene
1.3-butadiene
 0.2
 0.001
68.8
 0.002
11.7
 The benzene evaporative emissions factor on Table 4-1 is given as a
range to calculate the total county emissions, we assumed the benzene
evaporative factor was the mid-point of the range.

6/88      METHODS TO APPORTION COUNTWIDE AREA SOURCE EMISSIONS      A-25

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                  PROCEDURES  FOR  ESTIMATING AND ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Cadmuin                      =   0.003
Chromium                     = 298.9
Ethylene dichloride          =   0.45
Formaldehyde                 =  16.3
Lead                         =   0.6
Polycyclic organic Matter    =   1.9

    Traffic zone data provided is as follows:

    TRAFFIC ZONES	VMT/DAY
1
2
3
4
5
' 6*
7
75,827
513,601
386,399
150,132
56,013
80,537
241,611
Step 1

    Grid Cell 931 consists of traffic zones 1, 2, and 3.
    Grid Cell 932 consists of traffic zones 4, 5, and 6, as well as
    one-third of traffic zone 7.

    Allocate VMT Data to Grid Cells 931 and 932.

       Grid Cell 931:
         75,827 + 51,3601 + 386,399 = 975,827
        (Zone 1) (Zone 2) (Zone 3)
        Grid Cell 932:
         150,132 + 56,013 + 80,537 + (1/3 x 241,611) = 367,219
        (Zone 4) (Zone 5) (Zone 6) (1/3 Zone 7)

Step 2

    Apportionment Factor (^ = VMTi/VMTt)

       Grid Cell 931; A = 975,827/(975,827 + 1,342,506) = .70

       Grid Cell 932; A = 367,219/(975,827 + 1,342,506) = .30
 One-third of the area of zone 7 lies within Grid Cell 932.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS      A-26

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                  PROCEDURES  FOR  ESTIMATING  AND  ALLOCATING
                    AREA SOURCE EMISSIONS OF AIR TOXICS
Step 3

    To apportion emissions to Grid Cells 931 and 932, multiply results of
Step 2 times countywide emissions

Light duty vehicle

Grid Cell 931

Acetaldehyde •
Asbestos
Benzene
Benzo(a)pyrene
1,3-Butadiene
Cadmium
Chromium
Ethylene dibromide
Formaldehyde
Lead
Polycyclic organic Matter

Grid Cell 932

Acetaldelyde
Asbestos
Benzene
Benzo(a)pyrene
1,3-Butadiene
Cadmium
Chromium
Ethylene dibromide
Formaldehyde
Lead
Polychclic organic matter
0.2
0.001
68.8
0.002
11.7
0.003
298.9
0.5
16.3
0.6
1.9
X
X
X
X
X
X
X
X
c
X
X
0.70
0.70
0.70
0.70
0.70
0.70
0.70
0.70
0.70
0.70
0.70
= 0.2
= 0.0007
= 48.2
= 0.002r
= 8.7
= 0.002
= 209.2
= 0.3
= 11.4
= 0.4
= 1.3
0
0
68
0
11
0
298
0
16
0
1
.2
.001
.8
.002
.7
.003
.9
.5
.3
.6
.9
X
X
X
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
0
0
0
0
.30
.30
.30
.30
.30
.30
.30
.30
.30
.30
.30
=
s
s
Si
=
=
=
=
s
sr
s
0
0
20
0
3
0
89
0
4
0
0
.07
.0003
.6
.0007
.5
.0001
.7
.1
.9
.2
.6
6/88
METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS
A-27

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                 PROCEDURES FOR ESTIMATING AND ALLOCATING
                    AREA  SOURCE  EMISSIONS  OF  AIR  TOXICS
                                REFERENCES
 1.  Dunn  and  Bradstreet.   Dunn's  Electronic  Yellow  Pages  (EPS)  -  Dialog
    Data  Base Catalog.   Dialog  Information Services  Inc.   January 1987.

 2.  Thomas  Publishing  Company.  Thomas  Register  of  American  Manufacturers
    and Thomas Register  Catalog File.   Volumes  1-14.   New York,  NY.   1986.

 3.  Fegeas,  R.C.  et  al.   USGS Digital Car to Graphic  Data Standards:
    Land  Use  and  Land  Cover  Digital  Data.  GSC 895-E.   U.S.  Department of
    the  Interior.  Washington,  DC.  1983.

 4.  U.S.  Environmental Protection Agency.  Perchloroethvlene
    Drvcleaning-Background Information  for Proposed  Standards.
    EPA-450/3-79-029a.   Office  of Air Quality Planning and Standards.
    Research  Triangle  Park,  NC.   August 1979.

 5.  Environmental  Protection Agency.  Procedures for  the  Preparation  of
    Emission  Inventories for Volatile Organic Compounds Volume  II:
    Emission  Inventory Requirements  for Photochemical  Air Quality
 '   Simulation Models.   EPA-450/4-79-018.  U.S.  Office of Air Quality
    Planning  and  Standards.  Research Triangle  Park,  NC.   September 1979.

 6.  U.S.  Environmental Protection Agency.  Computation of Air Pollutant
    Emissions Factors.   Volume  II:   Mobile Sources  AP-42.  Mobile Vehicle
    Emissions Laboratory,  Ann Arbor, MI - September,  1985.

 7.  U.S.  Environmental Protection Agency.  User's Guide to Mobi1e3.   U.S.
    Environmental  Protection Agency. Ann Arbor,  MI.
6/88      METHODS TO APPORTION COUNTYWIDE AREA SOURCE EMISSIONS   •   A-28

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