United States
Environmental Protection
Agency
Research and Development
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
EPA/600/SR-92/001 Feb. 1992
Project Summary
Documentation of AIRS AMS
National Methodologies
E. Sue Kimbrough
The report provides, to states and
other participants (e.g., Regional Of-
fices, Headquarters, other federal agen-
cies) and users of the Area and Mobile
Source Subsystem (AMS), an under-
standing of the estimation procedures
that will be used by the national compo-
nent of AMS to generate emissions esti-
mates for area and mobile source
categories. It discusses general meth-
odology and assumptions as well as
the original source of algorithms, activ-
ity levels, and emission factors neces-
sary to calculate emissions for each
area and mobile source in AMS. The
report presents methodologies for all
identified sources not defined as point
sources. Area and mobile sources are
divided into seven major groups: sta-
tionary source fuel combustion, mobile
sources, industrial processes, solvent
utilization, solid waste disposal, natural
sources, and miscellaneous area
sources. Historically, these methodolo-
gies have been referred to as the Na-
tional Emissions Data System (NEDS)
methods and to some extent are docu-
mented in area source documentation
for the 1985 National Acid Precipitation
Assessment Program (NAPAP) inven-
tory; however, the NAPAP documenta-
tion does not include certain initial data
calculations. In addition, over the years
numerous changes have occurred to
the sources of the data that "feed" these
methodologies. These initial data cal-
culations and source data changes are
included in the report.
This Project Summary was devel-
oped by EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The U.S. Environmental Protection
Agency's (EPA's) Office of Air Quality Plan-
ning and Standards (OAQPS) in Research
Triangle Park, NC, is in the process of
developing a nationwide database of esti-
mated air pollutant emissions from area
and mobile sources known as the
Aerometric Information Retrieval System
(AIRS) Area and Mobile Source Subsystem
(AMS).
The purpose of this document is to
provide states and other participants and
users of AMS (e.g., Regional Offices, Head-
quarters, other federal agencies) with an
understanding of the estimation procedures
that will be used by AMS to generate emis-
sions estimates for area and mobile source
categories. General methodology and as-
sumptions are discussed as well as the
original source of algorithms, activity lev-
els, and emission factors necessary to cal-
culate emissions for each area and mobile
source in AMS.
The document presents methodologies
for all identified sources not defined as
point sources in a specific geographic re-
gion. Area sources include all mobile
sources, and stationary sources too small,
difficult, or numerous to classify as point
sources. Area and mobile sources are di-
vided into seven major groups: stationary
Printed on Recycled Paper
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source fuel combustion, mobile sources,
Industrial processes, solvent utilization,
solid waste disposal, natural sources, and
miscellaneous area sources.
Activity levels are derived primarily from
related information published by other fed-
eral agencies, supplemented by special
data developed by EPA for the purpose of
developing AMS emission inventories. Pub-
lished data such as fuel use by state,
motor vehicle miles of travel by state and
county, and forest fire acres burned by
state are used with related data such as
employment, population, and miscella-
neous geographic or economic data to
derive annual county estimates of the ac-
tivity levels for each of the National Emis-
sions Data System (NEDS) area source
categories. The activity levels derived are
adjusted to account for point source activ-
ity (such as fuel use by point sources) so
that the area source data reflect only the
activity levels (and resulting calculated
emissions) that are not accounted for by
point sources. The source of this point
source data is the AIRS Facility Subsystem
(FS). Point source emissions data are sub-
mitted annually by each state to EPA for
Inclusion in the AIRS FS.
Area and mobile source emissions es-
timates for seven pollutants—particulate
matter >10 u.m (PM,0). total suspended
particulate matter (TSP), sulfur dioxide
(SOj), nitrogen oxides (NO,), reactive vola-
tile organic compounds (VOCs), carbon
monoxide (CO), and lead (PB)—are calcu-
lated for each area and mobile source
category utilizing appropriate emission fac-
tors which are contained in the AMS emis-
sion factor file. For many categories, the
same emission factors are used for all
counties; however, for some source cat-
egories, state or county specific emission
factors account for local variables that af-
fect emissions. The more specific emis-
sion factors are used in AMS calculations
for alJ highway motor vehicle categories,
fugitive dust categories, and selected other
categories in a few counties where data
are available to develop more applicable
emission factors than the national emis-
sion factors.
Emissions estimates are updated an-
nually by AMS which first estimates activity
levels for each county and then applies the
appropriate emission factor and any appli-
cable control efficiency. County emissions
estimates are then summed to produce
national emissions estimates.
Background
Historically, NEDS has been the com-
puter system that the U.S. EPA has used
to calculate, store, and retrieve area and
mobile source emissions for the following
criteria pollutants: TSP, SO2, NOX, VOCs,
and CO. EPA is in the process of design-
ing and developing a new data subsystem
in the AIRS called the AMS, which will
replace NEDS.
AMS will use state-of-the-art database
management software with user-friendly
menus and screens. The goals of AMS
are: 1) provide storage and reporting ca-
pabilities for area and mobile source emis-
sions and related data required by EPA
regulations and the Clean Air Act; 2) re-
place the existing system used to store
and report these data with a state-of-the-
art system; 3) promote information sharing
among EPA offices and state and local air
agencies; 4) provide the ability to interact
with other EPA databases; and 5) provide
enhanced data processing services to the
EPA and state and local user community.
With passage of the Clean Air Act
Amendments (CAAA) of 1990 in Novem-
ber 1990, a data system that tracks area
and mobile source emissions inventory data
became critical to the needs of the Agency.
In particular, an area and mobile source
data system will be needed to support
implementation of Title I of the CAAA. This
takes the form of 1) storing area and mo-
bile source emissions data as reported by
state and local air agencies; and 2) devel-
oping comprehensive capabilities to sup-
port CAAA regulatory reporting, tracking,
and analytical requirements.
Emissions inventory data reported to
AMS by state and local air agencies in
support of Title I of the CAAA involve
reporting emissions inventory data for non-
attainment areas only. AMS, in addition to
supporting Title I requirements, will include
a national component that will include emis-
sions inventory data that may be used for
regional modeling. Since regional models
require data for both non-attainment and
attainment areas and generally require con-
sistent emission estimation methodologies
throughout the modeling domain, this na-
tional component will generate emission
estimates using a consistent methodology
for area and mobile source categories for
all areas of the U.S.—non-attainment and
attainment areas.
In order to accommodate the need to
support Title I activities and regional mod-
eling needs, a basic design decision has
been made to develop AMS using what
may be described as a "parallel approach."
The definition of parallel approach is that
EPA would prepare area and mobile source
data for all counties in the U.S. Any state
data submitted would reside in "parallel"
with the EPA prepared data. As a result of
this parallel approach, AMS will consist of
two components—a national component
and a state component.
Ideally, a more integrated or hybrid ap-
proach would be better. (In the hybrid ap-
proach, EPA would prepare area and
mobile source data for all counties in the
U.S. Any state data submitted would re-
place EPA prepared data for source cat-
egories in those counties.) However,
implementation of the hybrid approach will
not be attempted in the base system until:
1) better methodologies are available from
emission inventory research projects cur-
rently underway and the states become
familiar with an AMS system, and 2) a
plug-in methodology capability is fully in-
troduced. The emission estimation proce-
dures described below will be 'used within
the national component of AMS.
Historically, these methodologies have
been referred to as the NEDS methods
and are described in area source docu-
mentation for the 1985 National Acid Pre-
cipitation Assessment Program (NAPAP)
inventory. Much of the narrative from that
documentation has been used in the prepa-
ration of this report, since the basic con-
cepts for the estimation of the emissions
have remained comparable to the meth-
ods described in earlier documents. Cur-
rently, a number of emissions inventory
research projects are underway and should
provide improved emission estimation pro-
cedures. When these new procedures are
available, they will be implemented in AMS.
Stationary Source Fuel
Combustion
Stationary source fuel combustion which
contributes to area source emissions has
been divided into three major categories:
Residential Fuel, Commercial and Institu-
tional Fuel, and Industrial Fuel. Collec-
tively, these categories account for all
stationary fuel combustion activity not usu-
ally reported as point sources. Each cat-
egory is further subdivided into the following
fuel types: anthracite coal, bituminous coal,
distillate oil, residual oil, natural gas, lique-
fied petroleum gas (LPG), wood, industrial
coke, and process gas. Methodologies for
activity level estimation and emission fac-
tor derivation are discussed for each cat-
egory and fuel type.
In the following methodologies for the
calculation of activity levels, consumption
is determined for each type of fuel using
two general steps:
1) County consumption is calculated
using an algorithm which is based on
significant variables for which county-
specific data are available (e.g., de-
gree days, number or rooms per
dwelling, number of dwellings).
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2) Resulting county consumption esti-
mates are normalized to reflect pub-
lished state consumption data by the
equation:
NCC = ECC
ESC
where:
NCC = Normalized county con-
sumption
ECC = Estimated county con-
sumption
PSC = Published state consump-
tion
ESC = Estimated state con-
sumption (summation of
estimated county con-
sumption)
Residential Fuel
The residential fuel category estimates
emissions for residential activities which
utilize fuel for water heating, space heat-
ing, and cooking. Emissions contributed
by residential fuel consumption are broken
down into six categories according to fuel
type: anthracite coal, bituminous coal, dis-
tillate oil, natural gas, LPG, and wood.
Emissions from the residential residual oil
consumption category are considered to
be negligible; therefore, no methodology
exists for this category. For each listed fuel
type, activity levels measured by fuel quan-
tity consumed in weight or volume units
are multiplied by emission factors to obtain
emissions estimates. Methodologies for
activity levels and emission factors are
discussed in turn.
Commercial and Institutional
Area source emissions from fuel use
by commercial and institutional sources
consist of emissions from all fuel burned in
stationary sources that are not included
under residential sources, industrial
sources, power plants, or commercial point
sources. Examples of commercial/institu-
tional area sources are hospitals, hotels,
laundries, schools, and universities. Fuel
types included in the discussion of activity
levels and emission factors are anthracite
coal, bituminous coal, distillate oil, residual
oil, natural gas, LPG, and wood.
Activity levels are estimated for anthra-
cite coal, bituminous coal, distillate oil, re-
sidual oil, natural gas, and LPG. Currently,
AMS does not employ a methodology to
estimate wood consumption at commer-
cial/institutional sources. Emissions from
this source are considered negligible com-
pared to those from other sources.
Industrial
Area source emissions generated by
the industrial fuel consumption sector which
are not accounted for by point source cat-
egories are discussed for the following fuel
types: anthracite coal, bituminous coal, dis-
tillate oil, residual oil, natural gas, LPG,
wood, and process gas. Methodologies for
consumption and emission factor compu-
tation are presented as available.
A procedure was developed for the
allocation of state industrial area source
consumption of bituminous coal, distillate
oil, residual oil, natural gas, and LPG. The
procedure for estimating industrial bitumi-
nous coal area source consumption has
been adjusted and applied to estimating
industrial anthracite coal area source con-
sumption. Originally, the procedure for in-
dustrial natural gas consumption called for
the inclusion of industrial LPG consump-
tion. LPG will now be estimated sepa-
rately. In addition, industrial natural gas
consumption by boilers and internal com-
bustion (1C) engines will be estimated sepa-
rately.
Procedures for estimating coke, wood,
and process gas activity levels have not
been developed. Industrial area source
consumption of these fuels is assumed to
be negligible.
Mobile Sources
Mobile sources which contribute to area
source emissions are divided into five ma-
jor categories: Highway Vehicles, Off-High-
way Vehicles, Railroad Locomotives,
Aircraft, and Marine Vessels. For each of
the above categories, methodologies for
activity level and emission factor estima-
tion are discussed.
Highway Vehicles
AMS disaggregates motor vehicles into
eight EPA vehicle categories on the basis
of use and gross vehicle weight for the
purpose of calculating emissions:
Light Duty
Gasoline Vehicles LDGV
Light Duty Gasoline
Trucks -1 LDGT1
Light Duty Gasoline
Trucks - 2 LDGT2
Heavy Duty
Gasoline Vehicles HDGV
Motorcycles MC
Light Duty
Diesel Vehicles LDDV
Light Duty
Diesel Trucks LDDT
• Heavy Duty
Diesel Vehicles HDDV
LDGVs are defined as gasoline pow-
ered passenger vehicles weighing 8500
Ib* or less. LDGT1 s include gasoline cargo
vehicles weighing 6000 Ib or less. LDGT2s
include gasoline cargo vehicles weighing
between 6001 and 8500 Ib. Heavy duty
vehicle categories separate diesel and
gasoline powered trucks and buses weigh-
ing more than 8500 Ib. MCs are defined as
any motor vehicles designed to travel with
not more than three wheels in contact with
the ground, and weighing less than 1,500
Ib. LDDVs are defined as diesel powered
passenger vehicles weighing 8500 Ib or
less. LDDTs include diesel cargo vehicles
weighing 8500 Ib or less.
While vehicle miles travelled (VMT) are
determined for each vehicle class and road
class, fuel consumption is determined only
for each vehicle class. Emission factors in
grams per mile obtained from the execu-
tion of the MOBILE model are applied so
as to determine emissions for vehicle type
and speed class. VMT is determined for
the following road classes:
Assumed
Speed,
mph**
55
55
55
55
55
55
55
45
45
45
19.6
19.6
Road Class
Urban Interstate
Rural Interstate
Urban Other Freeways and
Expressways
Urban Other Principal
Arterials
Rural Other Principal
Arterials
Urban Minor Arterials
Rural Minor Arterials
Rural Major Collector
Rural Minor Collector
Rural Local
Urban Collector
Urban Local
Off-Highway Vehicles
Emissions from off-highway vehicles are
generated by activities of gasoline and
diesel vehicles which do not utilize road
systems. Vehicles contributing to off-high-
way emissions are divided into six general
1 !b = 0.454 kg
1 mph = 1.609km/h
-------
categories: farm equipment, construction
equipment, industrial equipment, lawn and
garden equipment, motorcycles, and snow-
mobiles. While gasoline is consumed by all
sbc categories, diesel fuel is utilized only by
farm equipment, construction equipment,
and industrial equipment.
In general, consumption is estimated
by one of the following methods:
1) Apportionment of national fuel con-
sumption to counties on the basis of
employment, population, etc.
2) Calculation of county or state totals
by applying fuel consumption rates
to average usage figures and equip-
ment populations.
Consumption estimation methodologies
are described for each category by fuel
type.
Aircraft
Emissions estimates for aircraft are di-
vided into three categories: commercial,
military, and civil. Activity levels and emis-
sion factors, measured relative to units of
aircraft landing and takeoff cycles (LTOs)
by county, are multiplied by emission fac-
tors to obtain emissions estimates.
Activity level is measured by LTOs us-
ing either operation records from county
airports or aircraft registration data, de-
pending on the location of Federal Aviation
Administration (FAA) airports. For these
calculations, an operation, as defined by
the FAA, consists of either a takeoff or a
landing.
Weighted average emission factors are
computed for each type of aircraft within
each aviation category. In some catego-
ries, flying hours are used as a unit of
measure assuming that the number of fly-
ing hours are proportional to LTOs. Emis-
sion factors are then combined using
aircraft type population data from Jane's
and FAA Aviation Forecasts to form one
factor for each pollutant.
Marine Vessels
Marine vessel categories for which
emissions estimates are discussed include
coal vessels, distillate oil vessels, residual
oil vessels, and gasoline vessels. Final
estimates are measured in gallons of fuel
consumed. Emissions from coal vessels
have not been estimated because emis-
sions from this source are considered neg-
ligible compared to other area sources.
Consumption methodologies and emission
factor derivation are presented for each
category.
Railroad Locomotives
This category includes fuel utilized by
railroad locomotives and fuel used by rail-
road stations and workshops for space
heating. The latter fuel consumption has
been included primarily because it is diffi-
cult to separate from total railroad fuel use
and is considered insignificant compared
to locomotive consumption. The primary
fuel consumed by railroad locomotives is
distillate oil (diesel fuel). The activity level,
measured in thousands of gallons, is multi-
plied by emission factors to produce emis-
sions estimates.
The methodology used to estimate dis-
tillate oil consumption involves the alloca-
tion of published state consumption of
distillate oil by railroad locomotives to the
county level on the basis of current popu-
lation distribution.
Gasoline Marketing Operations
This source category covers evapora-
tive losses of VOCs from gasoline market-
ing operations such as filling losses from
loading underground storage tanks at ser-
vice stations, and spillage and filling losses
from filling automobile tanks. Gasoline
evaporative losses at refineries or bulk
distribution terminals are not included.
Emissions from refineries are assumed to
be accounted for in point source catego-
ries.
The activity level for this category, mea-
sured by retail gas sales in thousands of
gallons, is multiplied by emission factors to
generate emissions estimates.
Retail sales of gasoline include all sales
of gasoline for highway use, aviation use,
and for use by the construction equipment,
industrial equipment, and farm equipment
off-highway subcategories. Sales to the
above user categories are estimated sepa-
rately and summed to generate total county
sales.
State retail sales of gasoline for high-
way and marine use are allocated to each
county according to the county's propor-
tion of the statewide gross dollar receipts
from gasoline service stations. Published
state aviation retail sales of gasoline are
allocated to the county according to the
total LTO cycles in the county for each of
the military, civilian, and commercial air-
craft categories.
County retail sales of gasoline for off-
highway sources are assumed to be the
same as consumption derived in the activ-
ity levels section of Farm Equipment, Con-
struction Equipment, and Industrial
Equipment under Off-Highway Sources
Unpaved Roads
Vehicle traffic over unpaved roads, park-
ing areas, and recreational areas gener-
ates fugitive dust emissions which are
estimated in NEDS. Primary factors which
affect the amount of dust generated are
vehicle speed, surface type, wind speed,
surface moisture, and type of vehicle. Meth-
odologies for the estimation of activity level
measured in vehicle miles travelled (VMT)
and for emission factor derivation are de-
scribed.
The methodology developed to deter-
mine the county VMT on unpaved roads is
based on regression analysis of data col-
lected for VMT per county and mileage of
unpaved roads per county. County road
mileages for this study were obtained from
state transportation or highway depart-
ments. VMT was found to be dependent
on the county population and mileage of
unpaved roads in the county.
Industrial Processes
Industrial processes are very properly
considered as point sources in most emis-
sion inventories and in the recent past
have not been considered to be significant
contributors to area source emissions. How-
ever, there may be many industrial pro-
cesses that are too small to be considered
point sources, but collectively may contrib-
ute substantially to the overall total. At the
present time, no methodologies are avail-
able to estimate activity levels on a county
basis.
Construction
Road and building construction activi-
ties generate particulate emissions. Princi-
pal activities in construction which cause
dust emissions are land clearing, excava-
tion, and vehicle traffic around the con-
struction site. Variables known to affect
emissions are soil type, moisture, wind
speed, and type of operations on-stte. At
present, no methodology is available to
estimate activity level at the county level.
However, emission factors are available
from AP-42.
Solvent Utilization
This area source category documents
the estimation procedures for evaporative
losses of VOCs from solvent usage by
area sources. Organic solvent usage is
divided into seven major categories: sur-
face coating operations, dry cleaning op-
erations, degreasing operations, graphic
arts, rubber and plastics, miscellaneous
industrial operations, and miscellaneous
non-industrial operations. Surface coating
is further divided into the following subcat-
egories: architectural coatings, auto refin-
ishing, textile products, flatwood products,
wood furniture, metal furniture, paper, plas-
tic products, cans, metal coils, miscella-
neous finished metals, electrical, large
appliances, magnet wire, motor vehicles,
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aircraft, marine, railroad, and miscellaneous
manufacturing operations. In each cat-
egory, use of specific solvents is identified
and enumerated to compute total solvent
usage in tons per year.
The methodology for allocating organic
solvent consumption by county consists of
apportioning national consumption of 20
primary solvent groups by major user cat-
egory according to county population or
employment data. User categories are
listed in Table 1. Table 2 lists the primary
solvent groups used to determine losses
from organic solvent consumption. The
category "Special Naphthas" includes the
aliphatic naphthas such as V. M. P. naph-
thas, Stoddard solvent, rubber solvents,
and mineral spirits.
National consumption of the primary
solvent groups is distributed to each of the
user categories according to the percent-
age of total solvent consumption used by
the user category. Percentage usage ob-
tained from published sources is compiled
for each user category in Table 2. National
area source solvent use estimates are de-
termined by subtracting point source sol-
vent use or emissions for each user
category from total solvent use for each
user category.
County consumption for each solvent
group and user category is then computed
by allocating calculated national area
source consumption on the basis of appli-
cable county SIC area source employment
or population as shown in Table 1. For
example, in the degreasing processes use
category, total solvent use is allocated to
each county in proportion to the county
area source employment for SIC groups
34 through 39. Area source employment is
determined by subtracting point source
employment from total county employment
for each SIC category. For dry cleaning
applications, the county-wide allocation is
made on the basis of total employment in
SIC groups 7215, 7216, and 7218. To
reflect the unequal solvent use in particu-
lar establishments within SIC groups, con-
sumption is multiplied by a factor which
compares the number of individuals in the
county in each area source user category
to the number of individuals in the nation in
each area source user category. County
consumption of each solvent type is then
summed for each county to yield a total
county consumption.
Solid Waste Disposal
The area source category for solid
waste disposal includes on-sfte refuse dis-
posal activities by residential, commercial/
institutional, and industrial sectors. In this
section, emissions from the disposal prac-
Table 1. User Categories
User Categories
Population or Employment by SIC
Used for Country Allocation
Surface Coating
Architectural Coatings
Auto Refinishing
Textile Products
Flatwood Products
Wood Furniture (SIC 25 partial)
Metal Furniture (SIC 25 partial)
Paper
Plastic Products
Cans
Metal Coils
Misc. Finished Metals
Electrical
Large Appliances
Magnet Wire
Motor Vehicles
Aircraft
Marine
Railroad
Miscellaneous Mfg.
County Population
SIC 7535
SIC 22
SIC 243 +244
SIC 26
SIC 308
SIC 341
SIC 3498
SIC 34-(341 + 3498)
SIC 35
SIC 363
SIC 36 - 363
SIC 371
SIC 372
SIC 373
SIC374
Total Mfg. - Above SIC
employment
Degreasing
Dry Cleaning
Graphic Arts
Rubber & Plastics
Miscellaneous Industrial
Miscellaneous Non-Industrial
SIC 34 thru 39
SIC (7216x2) = 7215+ 7218
SIC 264 + 265 + 27
SIC 30
Summation ofCBP' employment
in SIC's 20 thru 39
County Population
* County Business Pattern
tices of open burning and on-sfte incinera-
tion are discussed separately. Solid waste
generation in hundreds of tons is used as
a measure of activity level.
Natural Sources
Natural sources are known to be sig-
nificant contributors to area source emis-
sions. Natural sources may include:
biogenic sources, wind erosion, lightning,
geothermal sources, and open-water
sources. However, while there are numer-
ous methodologies for estimating emis-
sions from natural sources, there remains
disagreement among the experts as to the
most appropriate methodology to use for
estimating emissions from this category.
Miscellaneous Area Sources
Area sources which are not defined by
Stationary Source Fuel Combustion, Mo-
bile Sources, Industrial Processes, Sol-
vent Utilization, Solid Waste Disposal, or
Natural Sources categories are compiled
in the miscellaneous area sources cat-
egory. The importance of these area cat-
egories is that, while total emissions from
each source are relatively small compared
to the major categories, emissions at a
particular time may be significant.
As presented, identified miscellaneous
area sources include: Acres Under Culti-
vation (Land Tilling), Agricultural Burning,
Forest Wildfires, Managed Burning, and
Structural Fires.
Agriculture Production—Crops
Acres Under Cultivation
(Land Tilling)
Fugitive dust emissions result from vari-
ous soil preparation operations which in-
clude rough plowing, mulch plowing, and
the cutting of narrow slits into the sod for
seed and/or fertilizer. Variables known to
affect the quantity of dust generated are
soil type, surface moisture, resulting tool
speed, type of equipment, and wind speed.
However, no methodology has been de-
veloped to adequately estimate emissions.
For previous inventories, activity levels are
estimated using the number of acres tilled
as obtained from the Census of Agricul-
ture. It was assumed that each acre of
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Tablo 2. Percentage End Use of Solvents by Major Solvent Category
Solvent Type
Special Naphthas
Porchtoroothylene
Elhanol
Trichbroalhyfone
Isopropanol
Acotono
Gtycol Ethers
Cydohoxanona
Mothy! Ethyl Kotona
Ethyl Benzene
Propytono Glycol
Mothanol
Butyl Acotato
EthylAcatato
Butyl Alcohols
Mothyl Isobutyl Ketona
Monochtorobenzane
o-Dtchlorobenzene
p~Dhhlorobenzene
AH Other Solvents'
Surface Dry Graphic
Coating Degreasing Cleaning Arts
48.7 6.7 2.0 6.4
10.0 53.0
80.0
15.0
17.0
43.0
69.4
65.0 5.0
41.0
15.5
65.5
21.0
Rubber & Miscellaneous
Plastics Industrial
9.6 7.1
26.0
9.0
10.0
5.0
10.0
54.0 4.0
8.0
8.0
1.8
8.0
21.0
25.0
23.0
Miscellaneous
Non-Industrial
10.7
4.0
5.0
37.0
11.5
0.5
6.0
15.0
3.0
13.0
1.3
18.0
11.0
5.0
46.0
miscellaneous non-industrial.
harvested cropland is tilled three times per
year. The resultant activity levels were re-
ported In thousands of acres.
Agricultural Burning
This miscellaneous area source cat-
egory estimates emissions from agricul-
tural burning practices routinely used to
clear and/or prepare land for planting. Spe-
cific operations include grass stubble burn-
Ing, burning of agricultural crop residues,
and burning of standing field crops as part
of harvesting (e.g., sugarcane). Emissions
estimates are generated by multiplying the
number of acres burned in each county by
a fuel loading factor and the emission fac-
tor for each pollutant.
The original methodology estimated the
1974 activity level in terms of acres burned
per state. It is assumed that the total quan-
tity of agricultural products burned in 1974
Is the same quantity which will be con-
sumed by fire each year. If no specific crop
data were available, it was assumed that
the number of acres burned annually are
divided equally between sugar cane and
field crops. For the purposes of these cal-
culations, fuel loadings for grass burning
are 1 to 2 tons per acre;* for sugar cane
burning, fuel loadings range from 6 to 12
tons per acre.
If new state, regional, or national esti-
mates are available, the existing county
data will be updated by the same percent-
age as the relative state, regional, or na-
tional percentage increase or decrease.
Other Combustion
Area sources which are defined as
Other Combustion include such categories
as forest wildfires, managed burning, and
structural fires. The importance of these
area categories is that, while total emis-
sions from each source are relatively small
compared to the major categories, emis-
sions at a particular time may be signifi-
cant.
Forest Wildfires
Each year emissions are generated by
forest wildfires covering large tracts of for-
ested land. For this category, emission
estimates are generated by multiplying the
number of acres burned per county by a
fuel loading factor and then the emission
factor.
In the original methodology, state esti-
mates of wildfire activity were allocated to
the county level on the basis of forest
acreage per county. These wildfire statis-
tics were obtained, reported in number of
acres burned, from contact with state for-
estry officials and from state land use maps
for the base year 1974. Since 1974, the
wildfire activity level for each county from
the previous year has been updated with
wildfire statistics from the U.S. Forest Ser-
vice. Regional fuel loading factors in tons
per acre for each EPA region are applied
to state averages within each region to
yield tons consumed.
Managed Burning (Slash/
Prescribed Burning)
Managed burning activities included in
this area source category are slash burn-
ing and prescribed burning. In slash burn-
ing operations, waste from logging
operations is burned under controlled con-
ditions to reduce fire hazards and remove
1 ton/acre « 0.224 kg/m2
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brush considered to host destructive in-
sects. Prescribed burning is used as a
forest management practice to establish
favorable seedbeds, remove competing
underbrush, accelerate nutrient cycling,
control tree pests, and contribute other
ecological benefits.
For this category, emissions estimates
are generated by multiplying the number
of acres burned in each county by a fuel
loading factor and the emission factor for
each pollutant.
Original state estimates of acreage con-
sumed by both managed burning tech-
niques were determined for the NEDS
inventory year of 1974. Individual state
officials and the U.S. Forest Service were
contacted to provide estimates of acreage
burned, burning technique, and fuel load-
ing ratios. AMS uses state data generated
for 1974 which was allocated to the county
level according to forest acreage per county
as obtained from contact with local officials
or state land use maps. If not provided,
fuel loadings for slash burning and pre-
scribed burning are 75 and 3 tons per
acre, respectively.
If new state, regional, or national esti-
mates are available, the existing county
data will be updated by the same percent-
age as the relative state, regional, or na-
tional percentage increase or decrease.
Structural Fires
Structural fires have been included in
AMS because building fires have been
identified in the production of short-term
emissions of air contaminants. Activity level
for this category, measured by the total
number of fires per county, is multiplied by
a loading factor and the emission factor to
obtain emissions estimates.
The total number of building fires is
obtained from the most recent statistics
from the National Fire Protection Associa-
tion (NFPA). In absence of county level
allocation data, it is assumed, based on
the nationwide NFPA figures, that an aver-
age of four fires per 1,000 population oc-
cur each year. Estimates of the material
burned is obtained by multiplying the num-
ber structural fires by a fuel factor of 6.8
tons* of material per fire.
If new state, regional, or national esti-
mates are available, the existing county
data will be updated by the same percent-
age as the relative state, regional, or na-
tional percentage increase or decrease.
* 1 ton = 907 kg
*US. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40162
-------
E Sue Kfmbrough is the EPA Project Officer, (see below).
The complete report, entitled "Documentation of AIRS AMS National Methodologies,"
(Order No. PB92-132869/AS; Cost: $26.00, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC, 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA PERMIT NO. G-35
Official Business
Penalty for Private Use $300
EPA/600/SR-92/001
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