AIRCRAFT EMISSIONS:
  IMPACT ON AIR QUALITY
     AND FEASIBILITY OF CONTROL
               SSEZ
      UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

-------
                          PREFACE
    This report presents the available information on the
present and predicted nature and extent of  air  pollution
related to aircraft operations in the United  States.  In
addition, it presents an investigation of the present and
future technological feasibility of  controlling such
emissions.  This report is published in accordance with
Section 231 (a) of the Clean Air Act as amended, which
states:

       " (1)  Within 90 days after the date  of enactment of
the Clean Air Amendments of 1970, the Administrator shall
commence a study and investigation of emissions of air
pollutants from aircraft in order to determine-

           "A.  the extent to which  such emissions affect
air quality in air quality control regions  throughout the
United States, and

           NB.  the technological feasibility of controlling
such emissions

           n (2)  within 180 days after commencing such study
and investimation, the Administrator shall  publish a report
of such study and investigation . .  ."

-------
                     TABLE OF CONTENTS
                                                                     Page
LIST OF FIGURES	v

LIST OF TABLES	vii

INTRODUCTION	1

CONCLUSIONS	'	5

METHODOLOGY FOR ASSESSMENT OF AIR QUALITY IMPACT	7

     NATIONAL AMBIENT AIR QUALITY STANDARDS	7

     BASIC REQUIREMENTS FOR IMPACT EVALUATION	10

          EMISSION FACTORS	10

          SELECTION OF CRITICAL AREAS AND AIRPORTS	12

          EMISSION PROJECTIONS	13

RESULTS OF IMPACT EVALUATION	19

     REGIONAL IMPACT OF AIRCRAFT EMISSIONS	19

     SUBREGIONAL AND LOCALIZED IMPACT	29

          GENERAL INDICATIONS OF LOCALIZED AIR  QUALITY IMPACT	29

              PASSENGER USAGE DENSITY AND AIR  POLLUTION POTENTIAL	29

              EMISSION DENSITY COMPARISON	30

          DETAILED INVESTIGATION OF LOCALIZED POLLUTANT CONCENTRATION..33

              8-HOUR CARBON MONOXIDE CONCENTRATIONS	33

              1-HOUR CARBON MONOXIDE CONCENTRATIONS  AT LOS ANGELES AIRPORT
                                                                	39
              CARBON MONOXIDE CONCENTRATIONS AT  OTHER AIRPORTS	39

              HYDROCARBONS AND POTENTIAL OXIDANT CONCENTRATIONS	A3

              OXIDES 'OF NITROGEN	47

              SMOKE AND PARTICULATES	49

TECHNOLOGICAL FEASIBILITY OF CONTROLLING AIRCRAFT EMISSIONS	53
                                    111

-------
                                                                       Page



      EMISSION  CONTROL BY ENGINE  MODIFICATION .......................... 54




           ENGINE  CLASSIFICATION  ....................................... 54




           EMISSION  CONTROL METHODS  AND  EFFECTIVENESS .................. 55




                TURBINE ENGINES ........................................ 56




                PISTON ENGINES .......................................... 62




           COST  AND  TIME REQUIREMENTS  FOR  CONTROL METHOD




           DEVELOPMENT AND IMPLEMENTATION  .............................. 55




                EXISTING ENGINES  ....................................... 66




                FUTURE ENGINES .......................................... 70




      EMISSION CONTROL BY MODIFICATION OF  GROUND OPERATIONS ............ 71




           DEFINITION  OF GROUND OPERATIONS ............................. 71




           EMISSION  CONTROL METHODS .................................... 71




           IMPLEMENTATION COST AND TIME  REQUIREMENTS ................... 72




      COMPARATIVE EVALUATION OF EMISSION CONTROL METHODS ................ 76




      EMISSION MEASUREMENT  TECHNOLOGY ...........................         79




           SAMPLING AND  TEST PROCEDURES ................................ 80




           EMISSION MEASUREMENT INSTRUMENTATION ........................ 81




APPENDIX A [[[ 83




APPENDIX B [[[ 91

-------
                        LIST OF FIGURES
                                                                        Page

 1.  AIR SAMPLING LOCATIONS  AT  LOS  ANGELES  INTERNATIONAL AIRPORT	34

 2.  EXPECTED CO CONCENTRATIONS,  8-HOUR AVERAGING TIME, WINTER
    1970,  STATION 209,  LAX	35

 3.  VICINITY OF LOS  ANGELES INTERNATIONAL: PERCENT OF CONTRIBUTION
    BY AIRCRAFT TO CARBON MONOXIDE LEVELS	37

 4.  FREQUENCY DISTRIBUTIONS FOR  CARBON MONOXIDE FOR VARIOUS
    AIRCRAFT EMISSION CONTRIBUTIONS  AT STATION 209, WINTER 1980	38

 5.  HYDROCARBON ISOPLETHS IN THE VICINITY  OF LOS ANGELES  INTER-
    NATIONAL :  AIRCRAFT SOURCES  (3-Hr. Average for 1970)	44

 6.  HYDROCARBON ISOPLETHS IN THE VICINITY  OF LOS ANGELES  INTER-
    NATIONAL:  AIRCRAFT SOURCES  (3-Hr. Average for 1980)	45

 7.  CALCULATED NON-METHANE  HYDROCARBON CONCENTRATIONS DOWNWIND
    OF LOS ANGELES AIRPORT  FOR 1980  WITH NON-AIRCRAFT SOURCES
    CONTROLLED	46

 8.  NOX ISOPLETHS IN THE VICINITY  OF LOS ANGELES INTERNATIONAL:
    AIRCRAFT SOURCES (Annual Average for  1970)	48

 9.  NOX ISOPLETHS IN THE VICINITY  OF LOS ANGELES INTERNATIONAL:
    AIRCRAFT SOURCES (Annual Average for  1980)	50

10.  NOX ISOPLETHS IN THE VICINITY  OF CHICAGO-0'HARE INTER-
    NATIONAL :  AIRCRAFT SOURCES  (Annual Average for 1980)	51

11.  PISTON ENGINE EMISSION  CHARACTERISTICS	64

12.  HYDROCARBON AND  CARBON  MONOXIDE  EMISSIONS FROM A TYPICAL
    AIRCRAFT TURBINE ENGINE (JT3D)	73

A-l. MAXIMUM 8-HOUR AVERAGE CO CONCENTRATIONS  IN  LOS  ANGELES  AREA	85

A-2. BASELINE DATA,  DAILY MAXIMUM 8-HOUR  AVERAGE  CO CONCENTRATIONS
     STATION 209, LAX, 1970	'	86

A-3. FREQUENCY DISTRIBUTION FOR  8-HOUR CO DATA, STATION  209,  LAX,
     SEPTEMBER 1970	87

A-4. EXPECTED CO CONCENTRATION DISTRIBUTION, WINTER,  STATION  209,
     LAX FOR 80 PERCENT AIRCRAFT CONTRIBUTION	88

A-5. EXPECTED CO DISTRIBUTION, WINTER, STATION 209, LAX  FOR 20
     PERCENT AIRCRAFT CONTRIBUTION	89

-------
                          LIST OF TABLES
                                                                          Page
TABLE

 1. NATIONAL AMBIENT AIR QUALITY STANDARDS	  9

 2. AIRCRAFT CLASSIFICATION SYSTEM	;	:	> • 11

 3. PRESENT AND PROJECTED LTD CYCLES FOR 1970, 1975,  and  1980	14

 4. CURRENT AND PROJECTED EMISSIONS FOR AIRCRAFT AND  AIRPORTS	16

 5. ABILITY OR NON-ABILITY TO MEET THE NATIONAL AMBIENT AIR QUALITY
    STANDARDS IN 1975	20

 6. METROPOLITAN LOS ANGELES INTRASTATE AQCR EMISSIONS	21

 7. NEW YORK PORTION OF THE N.J. - N.Y. - CONN. INTERSTATE AQCR
    EMISSIONS	••••' 22

 8. NATIONAL CAPITAL INTERSTATE AQCR EMISSIONS	• • • 23

 9.  ILLINOIS PORTION OF THE METROPOLITAN CHICAGO INTERSTATE AQCR
     EMISSIONS	24

 10.  METROPOLITAN DENVER INTRASTATE AQCR EMISSIONS 1	25

 11.  SAN  FRANCISCO BAY AREA INTRASTATE AQCR EMISSIONS	26

 12.  METROPOLITAN DALLAS - FORT WORTH INTRASTATE AOCR EMISSIONS	27

 13.  METROPOLITAN BOSTON INTRASTATE AQCR EMISSIONS	28

 14.  INDICATIONS OF  LOCALIZED AIRPORT IMPACT OF 20 LARGEST AIR
     CARRIER AIRPORTS	•	31

 15.  COMPARISON OF EMISSION DENSITIES FOR AIRPORTS VERSUS URBAN
     AREAS FOR 1970, 1975, and 1980	32

 16.  EXPECTED  RANGE  OF DAYS THAT 8-HR STANDARD WILL BE EXCEEDED
     IN VICINITY OF  LAX FOR VARIOUS LEVELS OF AIRCRAFT IMPACT	40

 17.  LOS ANGELES AIRPORT - NUMBER OF TIMES THE  1-HOUR CO STANDARD
     WAS EXCEEDED  -  MAY 10 THROUGH NOVEMBER 9,  1970	41

 18.  DISPERSION MODEL ESTIMATES  OF  1-HOUR CO CONCENTRATIONS . ;	42
                                            ^                              i
 19.  AIRCRAFT  ENGINE CLASSIFICATION	55

 20.  ENGINE MODIFICATIONS  FOR EMISSION  CONTROL  FOR EXISTING AND
     FUTURE TURBINE  ENGINES	57
                                 VI1

-------
                                                                           Page
 21.  EFFECTIVENESS  OF tl - MINOR COMBUSITON CHAMBER REDESIGN  -
     ON  REDUCTION OF EMISSIONS FROM TURBINE ENGINES	59

 22.  EFFECTIVENESS  OF ENGINE MODIFICATION  IN CONTROL OF EMISSIONS
     FROM TURBINE ENGINES, BY OPERATING MODE	60

 23.  BASES FOR  CONTROL METHOD EFFECTIVENESS ESTIMATES FOP  TURBINE
     ENGINES	61

 24.  ENGINE MODIFICATIONS FOR EMISSION  CONTROL  FOR  EXISTING AND
     FUTURE PISTON  ENGINES	53

 25.  CURRENT UNCONTROLLED EMISSION  RATES FOR PISTON ENGINES	65

 26.  EFFECTIVENESS  OF ENGINE MODIFICATIONS  IN CONTROL OF
     EMISSIONS  FROM PISTON ENGINES  BY POLLUTANT	65

 27.  TIME  AND COSTS FOR MODIFICATION OF CURRENT CIVIL AVIATION
     ENGINES	    68

 28.  COST  RESULTS FOR TURBINE ENGINE POPULATION BY  SEPARATE USE
     CATEGORIES	69

 29.  COMPARATIVE  REDUCTIONS  RESULTING FROM  CONTROL  METHODS APPLIED
     AT LOS ANGELES  INTERNATIONAL AIRPORT	 74

 30.  COSTS AND TIME  FOR OPERATIONS  CHANGES  AT LOS ANGELES INTER-
    NATIONAL AIRPORT	 75

 31.  COMPARISON OF  EMISSION  CONTROL METHODS	 77

 32.  INSTRUMENTATION  FOR MEASUREMENT OF TURBINE ENGINE EMISSIONS	82

B-l.  SHORT-TERM METEOROLOGICAL AND ACTIVITY CONDITIONS	 94
                                  Vlll

-------
                       INTRODUCTION
     Public awareness that aircraft were a source of air
 Pollution developed in the late 1950* s with the introduction
 of turbine-engine aircraft.  Visible exhaust plumes from the
 engines and increased levels of exhaust odors a?air ports
 £??lei J°^aints *° b« lodged.  The complaints, in £S*
 stimulated investigations into the nature and extent of
 aircraft emissions.  The Air Quality Act of 1967
 specifically identified aircraft emissions as a subject of
 £n?^n ™d re?uired ™ investigation by the DepIrtmlS of
 Health, Education, and Welfare.  The study*,  submitted  to
 Congress on January 17, 1969,  concluded that:

        "1.  Reduction of particulate emissions  from  -jet
 aircraft is both desirable and feasible.   Engine
 Sn?«JS*UrerS fnd airlines have indicated that improvements
 in turbine  engine combustor design can  be built into new
 engines and retrofitted on engines already in  use?   Teltina
          aJS alread? underw*y-   Furthermore, thly have     9
          that application of  this technology  will be
          y ^ early 197°'s-   While there «e io laws or
          L£r?Sei  thS  *ndustr* to follow through  on  this
          ppears that  public pressures  resulting primarily
          fT8! eff€cts of odors  and visibilit? obscuration
          industrv to  Initiate  the  application  of this
 technology as  soon as  possible  and  to complete  it within the
 SS^SLSSS1; time'  ^rclingly, it L the'LSntion o!
 tuis Department  to encourage such  action by enoine
 manufacturers  and airline operators and to keep close watch
 on their progress,  if, at any time, it appears that
 K°^S? 1S ^•TOte or that completion of the work will
 ?L^  ?iy Prolon9ed' or that the concern of the industry
 lags, the Department will recommend regulatory action to the
 Congress that statutory authority for such actioTbe
 provided .
r,^-.             research is needed to define more
precisely the present and probable future "**ur«» and

SS^i^f/ii*?^ a±r P°11Uti°n P^ble^s associated
niS« J      *  Jivaty ln the United States and to  identify
needs for control measures.   Emphasis must be placed
particularly on assessment of air pollutant levels  in the

-------
  air terminal  environment and their  effects  on health  and
  satety and  on evaluation of  possible  long-term effects  of
  upper  atmospheric pollution  resulting from  aircraft flight
  activity.   The Department will undertake  research
  appropriate to the solution  of this problem.

    *   *"3'  As further research results in identification of
  needs  for additional measures to control  air  pollution  from
  any type of aircraft, and as  measures to  achieve such
  control become  available  through research and  development.
  it is  the Department's expectation that engine
  manufacturers,  airline operators, and other segments of the
  aviation community will take  the initiative in the
  development and application of such control measures.   If
  the private sector fails to provide adequate controls, the
  Department will not hesitate to recommend to the Congress
 that Federal regulatory action be authorized.

        "4.  In light of the relatively small contribution of
 aircraft to community air pollution in all places for  which
 adequate data are available,  and in view of the practical
 £??«"? *5S* would result from State and local regulatory
 action in this field,  it is the Department's conclusion that
 adoption and enforcement of State or local emission control
 regulations pertaining to aircraft cannot be adequately
 ^iT^f    at this time'   The  Department recommends  that, if
 and when regulations become necessary, the rationale used to
 develop Federal rather than local emission standards for
 motor  vehicles be applied to  aircraft.

        "5.  The Department recognizes that  State and local
 agencies, in cooperation with the Federal  Aviation
 Administration and other cognizant  agencies,  are the most
 appropriate  groups to  insure  that control  of airport
 pollution hazards  will be given adequate consideration in
 ™^Seie°^°n  of *irp°rt sites, planning for expansion and
 fnd £nn£»T°2 °f  airP°rts' desi^  of  airports,  and planning
 and conduct  of ground operations.

        "6. The Department  will include information  on
 progress in  the  control  of air pollution from  aircraft in
 the annual report  which  must be submitted  under  section  306
 of the  Air Quality Act."

    As  a result  of conclusion  (1) above, in March 1970,  at a
meeting held by  the Secretaries of Health, Education, and
Welfare and  of Transportation, representatives of 31
airlines agreed  to a schedule  for retrofitting JT8D engines
with reduced smoke combustors, to be substantially completed
by the end of 1972.  This agreement sought to significantly

-------
abate visible (smoke)  emissions from aircraft powered by
•this widely used engine.  This retrofit program is 85%
complete (July 1972) ,   conclusion (2) pointed to the need
for studying air terminal environments, a need which led to
an EPA-sponsored study of Los Angeles International Airport
by the Los Angeles Air Pollution Control District.  This
study was completed in April 1971.*

    Passage of the 1970 Clean Air Act Amendments essentially
required that we reassess the aircraft emissions problem and
update our knowledge concerning the air quality impact and
feasibility of control of such emissions.

    The data base for this report includes information
developed by Northern Research and Engineering3 *, Cornell
Research Laboratories5, the previously cited LAPCD study,
and information compiled separately by EPA personnel.

-------
                       CONCLUSIONS
    The various approaches taken in this  study to assess  the
impact of aircraft on air quality indicate,  both
individually and collectively,  that aircraft operations
"cause or contribute to or are  likely to  cause or contribute
to air pollution which endangers the public  health or
welfare" (Sec.  231(a), Clean Air Act Amendments of 1970).
Based on this general conclusion a realistic program of
emissions control should be instituted.   Though such a
control program cannot be quantitatively  related to the  air
quality considerations discussed herein,  pollutant emissions
from aircraft and aircraft engines should be reduced through
the application of the present  and prospective technology
described in this study.  A control program  should have
inherent flexibility so that as more extensive impact data
become available the required controls can be modified
accordingly.

    The results of EPA's current study of aircraft emissions
and their control have led to the following  specific
conclusions:

    1. Aircraft emissions are significant contributors to
the regional burden of pollution in comparison to other
sources which will have to be controlled to  meet National
Ambient Air Quality Standards.

    2. When airports are viewed as concentrated area sources
of pollution emissions, either in isolation or in concert
with their surrounding pollution sources, it can be
demonstrated that airports will probably exert localized
impact on air quality, in excess of the standards, even
though relief is provided elsewhere in the region by
controls relating to automobiles and stationary sources.
That is, unless aircraft emissions are reduced, airports
will still remain intense area emitters of pollutants when
the emission densities in the surrounding region have been
greatly reduced.

    3. Aircraft emissions have impact on air quality in
residential and business areas adjacent to major U. S.
airports.  The control of non-aircraft sources in and around
such airports will not be adequate to insure compliance  with

-------
the  National Ambient Air Quality Standards  indicating the
need for  controlling aircraft emissions.

     U.  There exists a variety of control  technigues  for
effecting aircraft emissions  reductions which  appear both
feasible  and economically attractive  during the  next two
decades.   Emissions may  be reduced  by means of the following
general approaches:

          (a)  Modification of  ground operational  procedures.

          (b)  Improvement in maintenance and quality  control
procedures to minimize emissions from existing families of
turbine engines.

          (c)  Development and  demonstration  of  new combustion
technology for major reductions  in  emissions from second-
generation turbine and piston aircraft engines.

          (d)  Retrofit of  turbine engine fleets with  existing
technology for near-term reduction  of emissions.

-------
   METHODOLOGY  FOR IMPACT ASSESSMENT
    Assessment of air quality impact involves  investigation
at several different levels:  (a)  global,  (b) regional  (sub-
global) , (c)  urban, and (d)  local.   In this report the urban
level is defined as an air guality  control  region.  The
ability to conduct investigations or assessment  at these
levels depends entirely on the analytical tools  and data
bases available.  Until quite recently most assessments were
source oriented and presented data  in terms of national or
air quality control region inventories.  With  the
development of models and more refined monitoring systems,
we can now explore the more localized "hot  spots" within an
urban area.  The earlier report*  on the impact of aircraft
emissions dealt only with national  and regional  inventories
and projections of aircraft emissions and pointed to the
need for a closer look at local airports and their immediate
environments.  Hence, this study  concentrates  on assessing
local effects through a combination of approaches involving
monitoring, statistical analysis, and modeling.
Additionally, aircraft emissions  are compared  with those
from other sources of the same pollutants in terms of
relative importance and relative  cost of control.

    The potential impact of aircraft emissions on the global
and sub-global environments is not  being ignored.  Studies
of pollution at these levels  involve an integrated
assessment of all contributors to the global pollution
inventory, and hence are beyond the scope of this report.
The Clean Air Act mandates that EPA study the  geophysical
effects of air pollution.  Research and monitoring
components of EPA are now engaged in preliminary phases of
such studies.

    To provide continuity, we have  updated  pertinent data
prepared by Northern Research and Engineering  which was
contained in the previous report*.   Discrepancies between
similar data presentations in the two reports  result from
the better data base obtained in  this study.

 NATIONAL AMBIENT AIR QUALITY STANDARDS

    In order to assess the significance of  aircraft
emissions, one must evaluate  their  contribution  to pollutant
concentrations in the atmosphere  and relate the  resulting
concentrations to the national ambient air  quality
standards.

-------
     In accordance with the Clean Air Act Amendments of 1970,
 the EPA established primary and secondary ambient air
 quality standards* for six major pollutants: carbon
 monoxide, nitrogen dioxide, hydrocarbons, photochemical
 oxidants, sulfur dioxide, and particulates.   The primary
 standards provide for protection of public health and the
 secondary standards for prevention of all other undesirable
 effects of air pollution.  Table 1 shows the national
 standards for these six pollutants.

     It should be noted that nonmethane hydrocarbons at
 concentrations observed in the atmosphere have not been
 associated with health effects.   The relationship between
 nonmethane hydrocarbons and photochemical oxidants
 indicates, however,  that peak photochemical  oxidant
 concentrations are associated with hydrocarbon
 concentrations averaged over the time period from 6 to 9
 a.m. *   The peak oxidant levels normally appear some three
 hours  later.   The nonmethane hydrocarbon standard is based
 on  this relationship.

    As  a basis for implementation of the standards,  the
 entire  United States has been divided into some  2HO Air
 Quality Control Regions*.  Regional boundaries are based  on
 considerations of urban-industrial concentration,  existing
 jurisdictional boundaries,  and other factors including
 topography and meteorology,  which would affect levels of  air
 quality in an area.

    In  accordance with the  provisions of  Section  110  of the
 Clean Air Act,  the States have submitted  plans that provide
 for the  implementation,  maintenance,  and  enforcement  of the
 national air  quality standards on a  regional  (air  quality
 region)  basis.   The  State implementation  plan  for  each
 region  must provide  for  attainment  of the primary  standards
 in 3-5  years  depending on whether an  extension has  been
 granted.   The  State  plan  is  required  to set  forth the
 procedure for  attaining  the  secondary standards within  a
 reasonable amount of time.

    Strategies  which States  are proposing to meet the
 standards and the  possible impact  aircraft emissions and
their control may  have on the  strategies are discussed in
the section on  regional impact.

-------
               Table  1   NATIONAL AMBIENT AIR QUALITY STANDARDS
        Pollutant
              Standard Description
Carbon monoxide
  (Primary and secondary
  standards are the same)
10 milligrams per cubic meter (9 ppm), maximum
8-hour concentration not to be exceeded more than
once per year.
40 milligrams per cubic meter (35 ppm), maximum
1-hour concentration not to be exceeded more than
once per year.
Nitrogen dioxide
  (Primary and secondary
  standards are the same)
100 micrograms per cubic meter (0.05 ppm), annual
arithmetic mean.
Hydrocarbons (non-methane)
  (Primary and secondary
  standards are the same)
160 micrograms per cubic meter (0.24 ppm), maximum
3-hour concentration (6-9 a.m.) not to be exceeded
more than once per year.  For use as a guide in
devising implementation plans to meet the oxidant
standards.
Particulate matter
  Primary standard
  Secondary standard
75 micrograms per cubic meter, annual geometric
mean.
260 micrograms per cubic meter, maximum 24-hour
concentration not to be exceeded more than once per
year.

60 micrograms per cubic meter, annual geometric
mean, as a guide to be used in assessing implementa-
tion plans to achieve the 24-hour standard.
150 micrograms per cubic meter, maximum 24-hour
concentration not to be exceeded more than once per
year.
 Sulfur dioxide
   Primary  standard
   Secondary  standard
80 micrograms  per cubic meter, annual arithmetic
mean.
365 micrograms per  cubic meter, maximum  24-hour
concentration  not to  be exceeded more than once per
year.

60 micrograms  per cubic meter, annual arithmetic
mean.
260 micrograms per  cubic meter, maximum  24-hour
concentration  not to  be exceeded more than once per
year.
1300 micrograms per cubic  meter, maximum 3-hour con-
centration not to be  exceeded more  than  once  per
year.
 Oxidant
   (Primary and secondary
   standards are the  same)
 160 micrograms  per cubic meter,  maximum  1-hour  con-
 centration,  not to be exceeded more  than once per
 year

-------
 BASIC REQUIREMENT FOR IMPACT EVALUATION

EMISSION FACTORS

Pollutants emitted by aircraft engines include gaseous
hydrocarbons, carbon monoxide, oxides of nitrogen,
particulate matter, and sulfur oxides.  In order to evaluate
the impact of aircraft emissions on the ambient air levels
of these pollutants, the logical first step is an estimate
of the total emissions due to aircraft.  Because emission
rates vary according to engine type, number of engines and
operating mode, we have classified aircraft by type, defined
the typical operating modes for each class throughout their
landing and takeoff  (LTO) cycles, and determined emission
factors for each  class operating in each mode.

The aircraft classification system groups aircraft into 12
separate types that include the currently used commercial
air carriers, and general aviation, and military aircraft.
(Classes 8-11 are exclusively military aircraft and are
excluded from further consideration in this report.)
Provision was also made in the classification system for the
possible introduction of supersonic commercial aircraft in
the future.  The  basis for classification of civilian and
commercial aircraft is presented in Table 2.

The aircraft modes of operation for which emission rates
were categorized  are:

       (1)  Start-up and idle
       (2)  Taxi
       (3)  Idle at runway
       (U)  Takeoff
       (5)  Climb-out to 3,000 foot elevation
       (6)  Fuel dumping
       (7)  Approach from 3,000 foot elevation
       (8)  Landing
       (9)  Idle and shutdown
       (10)  Maintenance

Emission factors  were developed for the civil aviation
aircraft classes.  A representative listing of emission
factors for piston and turbine engines is presented in
subsequent discussions of control feasibility.

The aircraft emission data, obtained through various
research programs funded by EPA, are summarized in the
report prepared for EPA by Cornell University.'

Emissions from non-aircraft sources on and around the
airport are also  accounted for in the air quality analyses.
These sources of  emissions include airport heating plants.
                              10

-------
                                                      TABLE 2

                                           AIRCRAFT CLASSIFICATION SYSTEM
Ref. 14
class-
Category Class fication
Air
Carrier 1
2
3 1
4 2
5 4
General
Aviation 6 3

7 6
V/Stol 12 7
Type
Supersonic
transport
Jumbo jet
transport
Long-range
jet transport
Medium range
jet transport
Turboprop
transport

Business jet

Piston-engine
utility
Helicopters
and V/STOL
Examples
Concorde
Tupolev TU-144
Boeing 747
Douglas DC-10
Boeing 707
Douglas DC-8
Boeing 727
Douglas DC-9
Lockheed Electra
Fairchild Hiller
FH-227

Lockheed Jetstar
North American
Sabreliner
Cessna 210
Centurion
Piper 32-300
Cherokee Six
Silorsky S-6L
Vertol 107
Engine Model
R-R/Snecraa
Olympus 593
P&WA JT9D
P&WA JT3D
P&WA JT8D
Allison
501-D13

P&WA JT12

Continental
10-520-A
General
Electric CT58
Type
Turbojet
Turbofan
Turbofan
Turbofan
Turbo-
prop

Turbojet

Opposed
piston
Turbo-
shaft
Engines
Thrust per
or powera aircraft
39,000 Ib. 4
43,000 Ib. 4
18,000 Ib. 4
13,900 Ib. 2.6
3,750 hp. 2.5

2,900 Ib. 2.1

292 hp. lb
1,390 hp. 2
Equivalent shaft power.
b,
 Representative of Van Nuys and Tamiami.

-------
fuel storage losses, automobiles, service vehicles, and
areas neighboring the airport.  To estimate the impact of
aircraft emissions on air quality near the ground, one must
take into account emissions from the time an aircraft enters
the atmospheric mixing layer during approach until it leaves
this layer during climb-out.  In defining an LTO cycle
representative of this consideration, a height of 3,000 feet
above the runway was selected as a reasonable approximation
of atmospheric mixing depth over major U. S. metropolitan
areas.1 The number of LTO cycles performed, and the relative
lengths of time spent in each operational mode of an LTO
cycle, combined with the appropriate emission factors,
determine the quantities of pollutants emitted ty aircraft.

SELECTION OF CRITICAL AREAS AND AIRPORTS

Once the general emission characteristics of aircraft were
determined, specific regions and airports having high
aircraft activity and air pollution potential were selected
for impact evaluation.

As a part of the Northern study3, several airports were
selected to represent, as nearly as possible, those at which
the impact of emissions from aircraft and related activities
would probably be greatest.  The factors considered in
evaluating the potential impact of individual airports
included: (1)  aircraft activity levels,  (2) airport area,
(3) mean wind speed, and (U) relative activity of different
types of aircraft (commercial air carrier and general
aviation).  On the basis of these considerations and the
availability of airport and aircraft activity data, these
airports were selected for study:

    (1) Commercial Air Carrier

       Los Angeles International

       Washington National

       J. F, Kennedy International

       O'Hare International

    (2) General Aviation

       Van Nuys, California

       Tamiami, Florida
                               12

-------
 Less  elaborate evaluations of  four additional  airports and
 their impact in  their respective air quality control regions
 were  developed as  the regional impact analysis was expanded
 to  include an examination of State implementation plans  for
 the attainment of  the air quality standards.

 The four additional airports,  located in San Francisco,
 Dallas-Ft. Worth,  Denver, and  Boston, were selected on the
 basis of high levels of aircraft activity and  severity of
 the regional pollutant levels.

 EMISSION PROJECTIONS

 The basic emission factors for any particular  engine type
 are not expected to change substantially with  time unless
 changes are required by emission standards.  In addition,
 the number and type of engines representative  of one
 particular class of aircraft are not expected  to change
 substantially in the next 10-20 years.  The important and
 determining factors affecting the projected controlled or
 uncontrolled emissions are:  (1) changes in the level of
 airport activity, and (2)  changes in the mix of the various
 classes of aircraft.

 As  a  part of the Northern Research Study, records of
 aircraft activity by class were obtained for the selected
 airports.  Prospective growth in activity at each airport
 was estimated by projecting past and current activity data
 to  1975 and 1980.  The general trend at the selected
 airports is towards more aircraft operations in classes 1,
 2,  4, 6 and 7; and less in classes 3 and 5.  The total
 yearly activity  data and projections are summarized in Table
 3.

 The air carrier  airports are so-called because of the
 preponderance of commercial air carrier activity, which,  in
 1970, ranged from 66 percent of total activity at Washington
 National to 92 percent at Chicago O'Hare.  Activity at
 Tamiami and Van  Nuys Airports is approximately 99 percent
 general aviation aircraft.

 Additionally, data were obtained on the uses and locations
 of taxiways,  runways,  terminals,  hangars, heating plants,
 fuel storage areas, and roadways at each airport in  order to
 locate and quantify the various sources of emissions during
the operation of aircraft.

Based on projections from  Reference 3,  revised to
 incorporate more accurate  emission factors,  total projected
emissions of  pollutants from aircraft and from all  sources
                               13

-------
                                                     Table  3
                           Present and Projected LTD Cycles for 1970,  1975,  .md  1980
Airport
All FAA operated airports
Air carrier airports
Los Angeles
International
Washington
National
J. F. Kennedy
International
Chicago
General aviation airports
Van Nuys ,
California
Tamiami,"
Florida
Type of aircraft
Air
carrier
-

203,900
109,800
188,800
314,300

20
General
aviation
-

59,900
55,500
27,800
21,200

279,400
200,800
Military
-

4,200
1,500

-

2,700
"
Helicopters
-

4,050
-




Total L'TO cycles
1970a
28 x 106

272,000
166,700
219,200.
339,900

281,600
200,800
1
1975
39 x 106

305,200
169,800
208,500
357,000

	 1
1980
59 x 106

358,100
173,500
241,300
410,800

700,000
       parts do not add up
b!971 estimated activity
to total, LTD cycles not classified by type were included in total

-------
were calculated for the years 1975 and 1980 at each of the
selected airports except New Tamiami (which lacked reliable
activity projections).  These projections are presented in
Table H for total hydrocarbons, carbon monoxide, nitrogen
oxides, sulfur dioxide, particulate matter (including lead),
and lead.  For a more complete assessment of proposed
control strategies, emission projections for three of the
pollutants (hydrocarbons, carbon monoxide, and nitrogen
oxides) were also developed for 1990.  The projected values
for 1990 are presented in the discussion of control
feasibility and impact.  The emission projections are based
on present emission rates for each aircraft engine class and
do not incorporate potential future reductions in emissions
as a result of aircraft emission standards.  The projected
aircraft emissions reflect increased activity and changes  in
the mix of existing engines.

At the four air carrier airports during the 1970*s, as a
result of continued introduction of jet engines found in
present-day new jet aircraft, total emissions of carbon
monoxide from aircraft are not projected to change greatly.
Hydrocarbon emissions, however, although predicted to
increase by 18 percent at Washington National Airport, are
expected to decrease by about 60 to 70 percent at Los
Angeles, John F. Kennedy, and O«Hare Airport.  The estimated
average increase in aircraft operations is 20 percent at
these airports during the 1970»s, indicating in general,
lower hydrocarbon and carbon monoxide emissions from the
newer and, in many cases, larger engines.  As shown in Table
U there will be substantial increases in aircraft NOx
emissions of 275 percent at Los Angeles, 1U6 percent at John
F. Kennedy, 98 percent at O'Hare, and 33 percent at
Washington National Airport between 1970 and 1980.  These
increases reflect the greater amounts of NOx emitted during
an entire LTO cycle  from the newer engines.  Some increases
in SO2 and particulate emissions from aircraft  are
projected, since such increases usually follow  increases in
aircraft operations.

At Van Nuys Airport, the projected increases in all
pollutants parallel  the large projected increases in
activity at this airport.  During the 1970«s, emissions of
hydrocarbons, carbon monoxide, NOx, and lead from aircraft
are projected to increase by about 110 percent.

As Table U indicates, we estimate that in 1975  CO emissions
from aircraft at Van Nuys Airport will exceed CO emissions
from aircraft at a major commercial airport, Washington
National.  This estimation indicates the  increasing
importance of general aviation aircraft emissions, and
                             15

-------
                         Table  4.  CURRENT AND PROJECTED EMISSIONS*
                                                       (tons/year)
FROM AIRCRAFT  AND  AIRPORTS
Airport
and year
Los Angeles
1970
1975
1980
Washington
National
1970
1975
1980
John F. Kennedy
1970
1975
1980
O'Hare
1970
1975
1980
Van Nuys
1970
1975
1980
Particulates
Aircraft

570
610
680


231
242
286

570
550
550

900
970
1,100

3.2
5.4
7.7
Airport
total

616
627
693


253
253
297

660
605
583

1,001
1,023
1,100

3.7
5.7
7.8
NOX
Aircraft

3,060
6,790
11,490


820
980
1,090

2,580
4,660
6,370

3,760
5,760
7,440

12.1
19.8
28.6
Airport
total

4,369
8,110
12,480


1,074
1,211
1,277

4,846
6,640
7,580

6,290
7,520
8,540

27.5
34.1
36.3
SO 2
Aircraft

431
490
623


105
121
143

418
415
442

562
600
718

0.033
0.066
0.099
Airport
total

434
561
726


319
330
352

902
913
957

605
660
803

0.33
0.55
0.88
Lead
Aircraft

0.3
0.9
1.0


0.5
0.5
0.5

0.3
0.4
0.9

0.2
0.4
0.6

3.2
5.3
7.6
Airport
total

35.2
22.0
7.8


4.8
2.1
0.9

53.9
27.5
7.8

63.8
28.6
7.7

3.6
5.5
7.6
Carbon monoxide
Aircraft

16,030
16,630
18,480


2,410
2,700
3,030

12,590
11,280
10,680

14,740
13,840
13,530

1,650
2,750
3,960
Airport
total

29,230
28,730
27,280


3,731
3,691
3,470

32,390
26,680
18,380

34,540
31 ,440
22,330

1,870
2,860
4,070
Total
hydrocarbons
Aircraft

12,570
8,660
4,770


610
680
720

9,490
5,700
2,830

9,580
6,300
3,710

100
165
242
Airport
total

14,660
10,530
5,760


864
823
775

12,680
8,010
3,930

13,210
8,830
4,920

132
198
264
 Based  on  aircraft emissions below 3000 feet altitude.
Includes  lead.

-------
emphasizes that during an LTO cycle, CO emissions from a
small general aviation piston engine can, in many cases, be
expected to approach CO emissions from a commercial air
carrier turbine engine.

The existing and potential air quality impact of sulfur
oxides and lead is considered to be negligible in comparison
to other sources of these two pollutants.  Therefore, no
further analysis was performed on these pollutants in this
study.  The particulate problem associated with aircraft
operations has already been shown to be confined to the
smoke problem and hence the air quality impact discussion is
very brief in this report.

Emission projections for the additional airports at Dallas-
Ft. Worth, San Francisco,  Denver, and Boston were based on
the similarity of the particular airport to one or more of
those in Table 4.
                              17

-------
        RESULTS OF IMPACT EVALUATION
 REGIONAL IMPACT

 The implementation plans of eight air quality control
 regions were reviewed in detail.   These regions  have
 critical problems in terms of their ability to meet the
 National Ambient Air Quality Standards and also  have
 airports with high air passenger  activity.  Pour of the
 regions considered are those in which the four major air
 carrier facilities considered in  the Northern Research Study
 are located.  The analysis of regional implementation
 strategies was extended to include San Francisco, Boston,
 Denver, and Dallas-Fort Worth.  Table 5 reflects the present
 status of implementation plans relating to the control
 strategies  (by pollutant)  for these regions and  their
 ability to meet the air quality standards by 1975.

 As an aid in assessing aircraft emissions and their regional
 impact Tables 6 through 13 present the 1970 emission
 inventories and emission projections for 1975 and 1980, for
 the eight regions cited, along with reductions expected as a
 result of Federal standards for emissions from light-duty
 motor vehicles.9  In addition,  one or more of the proposed
 strategies representing ccntrol of smaller sources or
 additional controls on motor vehicle sources are cited so
 that the spectrum of control demands is evident.   Present
 and projected estimates of aircraft emissions are also
 tabulated, along with the reductions to be expected if the
 proposed standards are met.  The  reductions for  1975
 represent application of the only feasible control  strategy
 available by that date, ground operation control.   Two
 values are shown for 1980 potential reduction: the first
 represents the actual reductions  achievalbe by 1980; the
 second, mass reductions achievable in the 198C—1990 time
 frame as a result of the proposed 1979 design standards.
 Note that in 9 of the 17 possible region/pollutant
 combinations (an 8-region by 2-pollutant matrix  plus Los
 Angeles NOx) the potential reductions in aircraft emissions
 are comparable to (at least half  of)  or greater  than the
 reductions due to minimum strategies proposed for 1980 by
 the various regional or State agencies.

 More importantly, in « of these 9 cases,  the air quality
 standard will not be met or will  be only marginally met in
 the 1975-1980 time frame.   In these cases aircraft  emission
reductions before and after 1980  would represent effective
control strategies.   In all regions facing difficulties in
                                19

-------
                             TABLE  5

                        ABILITY TO  MEET
             NATIONAL AMBIENT AIR QUALITY STANDARDS
                             IN 1975

                    (yes = able, no  = unable)

      Based on  Current  State Implementation  Plan  Information
       Region



1. Los Angeles

2. New York

3. Washington, D.C.

A. Chicago

5. Denver

6. San Francisco

7. Dallas/Fort Worth

8. Boston
*N02 air quality data is currently being reevaluated.  Results of this
 reassessment may require additional or accelerated control of aircraft
 NOX emissions to those herein proposed.
CO
Yes
No
No
Yes
No
Yes
Yes
No
Pollutant
HC N02*
No No
No
Yes
Yes
No
No
Yes
No
                                  20

-------
                                               TABLE 6

                               METROPOLITAN LOS ANGELES INTRASTATE AQCR
                                     EMISSIONS, KILOTONS PER YEAR
EMISSIONS

WITHOUT ADDITIONAL CONTROLS


Region
Aircraft (for entire region)

REGION WITH PROPOSED CONTROLS
(Aircraft control not included)
REDUCTION FOR SPECIFIC STRATEGIES

Present motor vehicle program
Petroleum industry
Organic solvents
Incineration
Combustion of fuels
Agriculture
Periodic vehicle inspection
Retrofit evaporative control
1/3 conversion to gaseous fuels
20% traffic reduction
AIRCRAFT CONTROL
Turbine ground operation
Turbine emission standard

Piston emission standard

Sum of aircraft control
strategies
CO




4,130
41.1























1970
HCa




651
6.8























NOX




573
4.2























CO




4,400
51.4

880



2,200


C 14.61

C i.a)
584

485
200.7

10.4




Ci

(_ 2.2)
230

175
o°2J>

10.9
1.9
(25.8)
2.3
(30.9)
15.1
any
1980C
HCa




756
3.2

130



548
25.5
(^2.21



CE3)
9.1
C? .3])
18.3

1.3
0.4
(2.7)
0.0
(0.3)
1.7
o>
NOX




668
15.6

275



350


C"i . l>
C9.Q
i
+14. 6b

I 25.6;)
27.4


1.0
(13.4)


1.0

aReactive HC based on California SIP

 Increase rather than decrease due to engine operation tradeoff
'Values shown in parenthesis are projected 1990 emission reductions.

-------
                                                     TABLE 7
                           NEW YORK PORTION OF THE N.J. - N.Y. - CONN. INTERSTATE AQCR
                                           EMISSIONS, KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (JFK only)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
(Other Strategies)
AIRCRAFT CONTROL
Ground Operation
Emission Standards
1970
CO HC NOX

4,207
12.6









832
9.5









741
2.6








1975
CO HC NOV
A

4,840
11.3

2,630

2,139
41a

5.7


955
5.7

485

431
20. 8b

3.6
.4

851
4.7

727

101
23. 6C



1980d
CO HC NOX

5,260
10.7

1,136

4,066
44. 6a

5.1
0.8
(9.6)

1,040
2.8

268

702
21b

1.6
0.6
.(3.0)

926
6.4

622

269
25. 6C


0.5
(6.1)
ho
NJ
           aDowntown truck control.
            -Process evaporation.
            Gas space heat downtown.
             Values shown in  parenthesis are projected 1990 emission reductions.

-------
                                                     TABLE 8
                                         NATIONAL CAPITAL INTERSTATE AQCR
                                           EMISSIONS,  KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (National)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
Minimum Strategies
AIRCRAFT CONTROL
Ground Operation
Emission Standards
1970
CO HC NOX

1,389
2.4









267
0.6









184
0.8








1975
CO HC NOX

1,554
2.7

1,025


470
25. f

1.1


299
0.7

155


97
a
2.2

.3
0.1

206
0.9

188


20
0.55



198QC
CO HC NOX

1,735
3.0

460


1,215
a
11.3-

1.2
0.2
(2.9)

335
0.7

117


190
erf:

.4
0.2

230
1.1

150


78
b
0.3


0.1
(1 . 0.)
N>
OJ
           Use of liquified petroleum gas  for  fleet vehicles.
           Motor vehicle maintenance and inspection.
           'Values shown in parenthesis are projected  1990 emission reductions.

-------
                                           TABLE  9
                ILLINOIS PORTION OF THE METROPOLITAN CHICAGO INTERSTATE AQCR
                                 EMISSIONS, KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (O'Hare)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
Aggregate Stationary
Source Controls3
AIRCRAFT CONTROL
Ground Operation
Emission Standards

1970
CO HC NOV
X

2,730
14.7











606
9.6











383
3.8










1975
CO HC NOV
A.

3,064
13.8

1,480



1,383
r^bi

nrg



688
6.3

235.5



262
(TTV

co>
0.6


435
5.8

306



94.5
6.0d



1980e
CO HC NOY
A

3,496
13.3

506



2,748
rT3b>

6.2
1.1
MMM^HM^L


796
3.7

96



465
fl~3C>

2.0
0.8
5T5V

504
7.4

196



265
7.4<3

0.6
(6.5;
Note:  Midway emissions = 20% O'Hare.
^Minimum source strategy assumed to be 10% of aggregate.
 Incinerators.
cRefinery solvents.
 Values shown in parenthesis are projected 1990 emission reductions.

-------
                                       TABLE  10
                         METROPOLITAN DENVER INTRASTATE AQCR
                            EMISSIONS, KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (Stapleton)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC -
STRATEGIES
National Motor Vehicle
Standards
Retrofit Pre '67 Cars
Tune-ups
AIRCRAFT CONTROL
Ground Operation
Emission Standards
1970
CO HC NO
X

873
4.5










174
2.6










139
1.0









1975
CO HC NO
X

965
4.6

516

280
66
103

1.8


192
1.7

98

70
14.5
9

1.0
0.2

154
1.6









1980s
CO HC NOY
J\.

1,065
4.8

252

757
12
44

1.7
0.3
(3.5)

212
1.0

65

140
C2.6>
4

0.5
0.2
C J. * -L^r* '

170
2.0








0.2
(1.8)
Values shown in parenthesis are projected 1990 emission reductions.

-------
                                          TABLE .11
                          SAN FRANCISCO BAY AREA INTRASTATE AQCR
                               EMISSIONS, KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (S.F. Int'l.)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
Minimum Strategies
Vehicle Inspection
AIRCRAFT CONTROL
Ground Operation
Emission Standards


1970
CO HCb NOX

1,980
11.0













315
3.2













266
2.1












1975
CO HO NOX

2,150
11.5

451


1,030
16*
266

5.3
0



340
2.2

89


172
02
10.9

m>
0.1



287
4.7

156


77
21. 8d
+7.3f





1980a
CO HCb NOV
X

2,350
12.7

291


1,730
rr8c|
106

5.6
1.0
(13 . 33


371
1.2

69


252
cr
2.9

0.7
0.2
C1.4)l

313
7.9 .

125
*

164 •
10. 8S
i
;

0.5 •'
6.8
i
Note:  Oakland and San Jose = 20% of S.F. Int1].
Rvalues shown in parenthesis are projected 1990 emission reductions.
 Defined highly reactive.
Agricultural burning.
d20% traffic reduction.
 "1/3 conversion to gaseous fuels.
 Increase rather than reduction.

-------
                                        TABLE  12
                  METROPOLITAN DALLAS - FORT WORTH INTRASTATE AQCR
                              EMISSIONS, KILOTONS PER YEAR
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (Love Field)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
Minimum, Control Stationary
Source and Gases
Maintenance and Inspection
AIRCRAFT CONTROL
Ground Operation
Emission Standards
1970
CO HC N0x

2,340
7.2










454
4.5










280
1.8









1975
CO HC NO
X

2,620
6.9







3.1


509
3.0

256

199
6.4
48

1.7
0.3

314
2.7

270

44





1980 a
CO HC NOX

2,920
6.7







2.9
0.5
(5.9)
.

567
1.8

149

393
6.4
19

0.9
0.4 :
1.8

350
3.5

178

172




0.3
(3.2)
Values shown in parenthesis are projected 1990 emission reductions.

-------
                                                      TABLE 13
                                       METROPOLITAN BOSTON INTRASTATE AQCR
                                           EMISSIONS, KILOTONS PER YEAR
NJ
oa
EMISSIONS
WITHOUT ADDITIONAL CONTROLS
Region
Aircraft (Logan)
WITH STATE PROPOSED CONTROLS
Region
REDUCTION FOR SPECIFIC
STRATEGIES
National Motor Vehicle
Standards
Gasoline Handling
Evaporative Losses
Solvent Control
Other Strategies Sited
None Actually Proposed
AIRCRAFT CONTROL
Ground Operation
Emission Standards
1970
CO HC NOV
A

1,352
7.9











263
5.8









	 1

206
1.6










1975
CO HC NOV
A

1,555
7.0

1,034

502




3.5


302
3. '5

141.5

95
12
52


2.2
0.2

237
2.8

211.7

25






1980a
CO HC NOV
A

1,690
6.5

490

1,200




3.1
0.5
(5.9)
t

329
1.7

82

178
13
56


1.0
0.4
(1.8)

258
3.9

183

75





0.3
(3.7)
              Values shown in parenthesis are projected 1990 emission reductions.

-------
meeting the air quality standards, every viable control
strategy will have to be applied to meet requirements of the
Clean Air Act.

Table 6, which relates to the implementation plan for
metropolitan Los Angeles, lists all proposed strategies and
gives aircraft emission figures representative of all
aircraft activity, including LAX, in the region.  For a
specific region, total aircraft emissions can be
substantially higher than those attributed to the area«s
major air carrier airport.  The region encompassing
metropolitan Los Angeles, for example, includes, besides
LAX, several smaller commercial air carrier airports and
numerous general aviation facilities.  It is not surprising
then that LAX accounts for only U0%, 70%, and 73%,
respectively, of the total regional aircraft emissions of
CO, HC, and NOx in 1970.  This general relationship of
emissions attributable to major airports and total regional
aircraft emissions could be expected in similar highly
populated air quality control regions.

In the Los Angeles region, uncontrolled emissions from
aircraft are expected to account  for 14% of the CO, 2.5% of
the reactive HC, and 5.5% of the  NOx total emissions by
1980.

Emissions from  piston aircraft have a particularly
significant impact on regional CO levels.  Although piston
aircraft were responsible for about 0.5% of the total CO
emissions in 1970, their contribution to CO emissions, if
uncontrolled, is expected to reach 10% by 1980.

 SUB REGIONAL AND LOCALIZED IMPACT

This section deals with the effect of aircraft  emissions on
air quality at  major airports and downwind of these
airports.  Emission densities and other parameters of
emission intensity and air quality impact are first
presented to  provide indications  of the contribution of
aircraft to air pollutant concentration around  a  number of
major  U. S. airports.  Then detailed results of sampling and
dispersion modeling are presented to give deeper  insight
into the localized impact of aircraft at airports where
aircraft contributions to air pollutant concentration  are
expected to be  particularly important.

GENERAL INDICATORS OF LOCALIZED  AIR QUALITY  IMPACT

Passenger Usage Density and Air  Pollution Potential.   An
indication of  localized impact of aircraft on air quality  is
                                  29

-------
  presented in  Table  1U  for the  20 largest U. S.  air carrier
  airports, as  determined  by  passenger enplanement.  On the
  basis of concentration of passenger activity, proximity of
  the  airport to  built-up  areas, and meteorological pollution
  potential»o  (a  function  of  atmospheric mixing height and
  wind speed),  seven  airports, designated by asterisks in
  Table 1U, could be  expected to be particularly  important
  contributors  to localized air pollutant concentrations.   The
  results of Table 14  indicate most directly the  airport
  contributions to localized  carbon monoxide concentrations-
  the airport contributions to oxidant and nitrogen dioxide
  concentrations  are  indicated less directly because
  intermediate  atmospheric reactions are involved in their
  production.

  Emission Density Comparison.  Emission densities have been
 calculated for  four of the  airports that show a major air
 quality impact potential.  Table 15 indicates that emission
 densities due to aircraft alone in 1970 were in most cases
 comparable to those of densely populated metropolitan areas
 served by the corresponding airports.

 This emission density comparison suggests that,  in these
 four airport areas,  the contribution by aircraft to ambient
 air concentrations of hydrocarbon,  CO,  and NOx is
 substantial.   Such contributions are particularly important
 where major airports lie  in  or  near metropolitan areas in
 which national ambient air quality standards are currently
 exceeded.   AS  shown  in Table 5,  this is  the case for  the
 four areas  considered.

 The comparison of  emission densities  (airport  versus
 metropolitan area)  for 1975  and 1980 demonstrates that the
 ratio of the airport emisison densities to  those of the
 metropolitan areas will increase  in most cases,  sometimes
 dramatically.   The trends can be  identified in Table  15,
 which  indicates  that aircraft are expected  to  become
 increasingly significant  contributors to air pollutant
 concentrations at airports and  in their vicinities.

 It  should be kept in mind that the emissions densities
 presented in Table 15 are averaged for the  given areas and
 that variation in actual  emission rates within the defined
 areas exist.

 The majority of  the  HC, CO,  and NOx emissions in
 metropolitan areas are  due to area rather than point
 sources.  This tends to minimize variation in emission
 densities throughout a  metropolitan area.  However, one
would expect to  observe higher emission densities where
                                 30

-------
                                                   TABLE 14

                  INDICATIONS OF LOCALIZED AIRPORT IMPACT OF 20 LARGEST AIR  CARRIER AIRPORTS
Enplaned
Passengers
Millio-ns
Airport (FY 1970)
* O'Hare
* Los Angeles
* Atlanta
* J.F. Kennedy
* La Guardia
San Francisco
* Dallas (Love)
* Washington (Nat.)
Boston
u> Miami
^ Detroit
Denver
Newa rk
Philadelphia
St. Louis
Pittsburgh
Minneapolis
Cleveland
Seattle
Houston
13.5
8.5
8.2
7.0
5.9
5.5
5.3
4.9
4.5
4.4
3.7
3.5
3. L
3.2
3.1
3.0
2.6
2.5
2.5
2 . 2
Aircraft Activity
Percent Percent
Commercial General
Aviation Aviation
95
76
86
86
80
78
70
66
66
66
71
48
76
70
58
64
55
45
68
73
5
22
14
14
20
21
30
33
34
31
27
52
24
30
38
29
37
55
32
27
Airport
Area,
Miles2 "
14.1
4.8
6.6
8.1
0.9
8.1
2.0
1.0
3.7
4.2
7.5
7.2
3.4
3.9
2.9
4.8
4.6
2.3
2.8
11.4
Passengers
'area X 105
36
40
33
25
65
20
38
49
24
22
14
13
19
17
18
14
13
17
16
6
Airport
Proximity to
Built-up
Areas e
2
2
2
2
2
1
2
2
1
2

2
2
2
2

2

2
1
Morning
Meteorological
Air Pollution
Potential (x/Q)b
50
50
50
30
30
50
30
70
20
20
40
30
30
30
40
80
60
50
40
30
a 1  =  Residential and business areas adjacent  to  airport  boundaries.
  2  =  Residential and business areas adjacent  to  airport  boundaries,  and  a significant  frequency  of
      wind from airport toward these areas.
  This  parameter is based on a simple  model of dispersion  over  urban areas,  in  which an  average  area-
  wide  pollutant concentration, \,  is  normalized for an  average emission rate,  0.   High  x/Q values
  indicate high potential pollutant concentrations.   The values listed above are morning upper
  decile levels for a 10-kilometer  along-wind distance.  More detailed information  on  this parameter
  is  presented in Ref.  10.

-------
Table 15. COMPARISON OF EMISSION DENSITIES FOR AIRPORTS VERSUS URBAN AREAS FOR 1970, 1975, and 1980



Los Angeles metropolitan area
Los Angeles Airport - all
emission sources
Los Angeles Airport - air-
craft alone
New York metropolitan area
Airport - all emission
sources
Airport - aircraft alone
Washington D.C. metropoliian
area
National Airport - all
emission sources
National Airport - air-
craft alone
Chicago metropolitan area
O'Hare Airport - all
emission sources
O'Hare Airport - air-
craft alone


Area ,a
mi2_
1250.0

3.9

3.9
320.0

4.5
4.5

61.0

1.0

1.0
227. 0

6.7

6.7
Emission densities,13 tons/mi2-day
1970
Carbon
monoxide
7.2

20.6

11.2
14.5

19.6
7.7

12.5

10.2

6.6
8.1

14.1

6.0
Hydro-
carbons
2.0

10.3

8.8
3.4

7.7
5.8

1.7

2.4

1.7
2.5

5.4

3.9
Nitrogen
oxides
1.0

2.0

1.1
3.6

2.1
0.8

1.7

1.7

1.0
1.4

1.9

0.8
1975
Carbon
monoxide
4.8

20.2

11.7
11.4

16.2
6.9

7.9

10.1

7.4
6.3

12.9

5.7
Hydro-
carbons
1.1

7.4

6.1
2.4

4.9
3.5

1 .1

2.3

1.9
1.7

3.6

2.6
Nitrogen
oxides
0.9

3.5

2.6
3.6

2.7
1.5

1.5

1.8

1.2
1 .4

2.0

1.3
1980
Carbon
monoxide
2.8

19.1

13.0
5.5

11.2
6.5

3.3

9.5

8.3
1 .4

9.1

5.5
Hydro-
carbons
0.9

4.0

3.4
1.3

2.4
1.7

0.4

2.1

2.0
0.9

2 n
C- • \J
1.5
Nitrogen
oxides
0.8

5.6

4.9
3 2

-------
there is high population activity such as in downtown and
industrial areas as opposed to residential areas within the
region.

Detailed Investigation of Localized Pollutant Concentrations

The emissions density data previously discussed pointed to
the fact that major airports are and will continue to be
significant area sources of air pollution emissions.  If the
health and welfare of the exposed population is to be
protected, the conclusion may be drawn that the emissions
must be reduced equally for all such sources, e.g., whether
they be airport or non-airport area sources of pollution.

8-Hour Carbon Monoxide Concentrations.  Carbon monoxide
concentrations at the Los Angeles International Airport and
in its vicinity were measured from May to November, 1970*.
The sampling was done by the Los Angeles County Air
Pollution control District under EPA contract.  Carbon
monoxide concentrations were continuously monitored at
several sampling sites, including U sites in the airport
terminal area, and 2 sites located upwind and downwind of
the airport complex.  At all of these, ambient
concentrations of CO were measured.  The monitoring sites
were located as shown in Figure 1.  Data from site 209 were
analyzed extensively to determine as quantitatively as
possible the air quality impact of aircraft CO emissions on
8-hour ambient CO concentrations in residential and business
areas downwind of the airport.

Site 209 is located directly downwind of the L. A. airport
when the wind blows from its most frequent direction, as
indicated by the wind rose in Figure 1.  Until recently this
area was a residential neighborhood, but now it is almost
completely owned by the Los Angeles Airport.  Other
residential areas, however, are located only a few blocks
west and north of this area; and it was concluded that
concentrations measured at site 209 are indicative of
concentrations in such residential areas.

Figure 2 presents an estimated frequency distribution of
carbon monoxide concentrations at site 209 during the winter
months, the time of highest CO concentrations  in the Los
Angeles area.  This frequency distribution is based on
sampling data collected at site 209 during August and is
adjusted to represent wintertime concentrations using a
seasonal conversion based on air quality data  for the entire
Los Angeles basin.  Derivation of the results  shown  in
Figure 2  is detailed  in Appendix A.  It can be  seen, in
Figure A-3 of that section, that site 209  is  exposed to  the
                                33

-------
                                                          ~\	-? v  '•OH pa
                                                          i«s^a^i|iy
                                                          •sw^-iWisyfl r..v.','":;•;'..;;
                     Figure 1
             AIR SAMPLING LOCATIONS
        AT LOS ANGELES INTERNATIONAL AIRPORT
      ^M I^WHF-
      ?„: .."isi^^-^A-WESTCiiFr'
                         * *«?.*.* "3.O.J-,"
                         S$&t$*^
           r i   i    •sS»i*sv«-*r™¥W^

     ••] >  J • !:  A i
Inair  3
iv1—7f r !?- STHiWtniF- i^'^h, h-i V'j't v
!„   :y^;;|; |i|fe =?--lUiJ wfi]  jjlti -
1^—a !l     ilfellWl "' iUlfeS^i
          *...:»-:3i rW L
                                                                           \ =
                                                   FREQUENCY OF WIND DIRECTION AT L.A.
                                                   AIRPORT, IN PERCENTAGES OF TOTAL,
                                                            1951-1960
                    11
                                                             Calm - 14%

-------
                                                 FIGURE 2



             EXPECTED CO CONCENTRATIONS,  8-HOUR AVERAGING TIME, WINTER 1970, STATION 209, LAX
   60
a.
ex
   20
H

W  10
CJ
z

8   8
g
o
3:

oo
Ambient A/Q Standard = 9 ppm
                                                    13 days/month
    99.9        99              90          70       50       30



       Probability  (%) of exceeding  the given pollutant  level.
                                                              10
0.1

-------
same levels of carbon monoxide whether it be influenced by
pollution from other than the airport  (easterly winds) or
from the airport alone  (westerly winds).  Figure 2 shows
that the 8-hour CO standard, which is not to be exceeded
more than once per year, is estimated to have been exceeded
at site 209 13 times per month, or 39 times in the winter 3-
month period.

Part of the carbon monoxide concentrations shown in Figure 2
is due to aircraft.  To estimate the portion of the
concentration that is due to aircraft, dispersion modeling
was applied.  The dispersion modeling methodology is
discussed in Appendix B.  The model's resulting estimate of
the current contribution by aircraft to total CO
concentrations, shown in Figure 3, indicates that aircraft
are highly significant contributors to local CO
concentrations downwind of the airport.  Figure 3 indicates
that expected aircraft contributions constitute 60-70% of
the total CO concentrations in the area of site 209.

Between 1970 and 1980, CO emissions from aircraft are
estimated to increase by fifteen percent (Table 4)  while CO
emissions from all other sources in the Los Angeles area are
expected to decrease to 20% of their 1970 levels.»«  Using
the estimated changes in emissions from these two source
categories, and assuming that the emission changes yield
proportional changes in pollutant concentrations due to each
source category, CO concentration frequency distributions
for various aircraft contributions can be derived from
Figure 2.  The result is presented in Figure U for various
1970 aircraft contributions to pollutant concentrations.

Figure U indicates that without controls of CO emissions
from aircraft the 8-hour CO standard will be exceeded more
than once during the 1980 winter months at site 209 if the
aircraft contribution to the total CO concentration in 1970
is as little as 20%.  As shown in Figure 3, the 1970
contribution by aircraft exceeds this percentage over a
large area downwind of the airport.  If the reasonable
assumption is made that Figure 2 approximates the 1970
winter CO concentration frequency distribution in this area,
it is evident that in 1980 the 8-hour CO concentrations will
continue to exceed the standard in this same area downwind
of the Los Angeles Airport if aircraft CO emissions are not
controlled.

As noted in Appendix A, the analysis resulting in Figures 2
and H can be repeated using data from September, rather than
from August, as a basis.  The September data will yield
higher concentrations than will the August data for similar
                             36

-------
                                                                                 u*-fi*-—\-{-{-*ri--£.r.\
                                                                                 -/•y.l i._^_._/»«.*__L ,.i, ,.(.- .*	.„*..'!
                                                                                 -•v-.U—V-L-M'..!.'.!1---- -: ?,
:.;.

                                                                                          ~    '•• •   :~
                                       FIGURE  3
                     VICINITY OF LOS  ANGELES INTERNATIONAL:
                      Percent Contribution by Aircraft to
                            Carbon Monoxide  Levels

                                                                             J I r-'V^lt I ! 1 I I i ."i:";-"-i" "77j .:•• j^T:."" ;
' '•     :r!:^---r
<.   t  CK-J?--
\    I~;.?I  !V
   V Y" """"•        EL SEGUKDO

-------
oo
H
2
W
U

§
u

o
u

PC;

o

 i
oo
                                                          FIGURE  4

                                 FREQUENCY DISTRIBUTIONS  FOR  CARBON  MONOXIDE  FOR VARIOUS

                              AIRCRAFT EMISSION CONTRIBUTIONS AT STATION  209  -  WINTER 1980
                  Notes

                     1. 80%  rollback from 1970 on non-AC sources

                     2. 1980 AC CO emissions  = 1.15 X 1970 emissions
                   AMBIENT  A/Q  STANDARD =  9  ppm
             99.9         99              90          70      50      30



             Probability (%)  of  exceeding the given pollutant level
                                                                                                  0.1

-------
frequencies of occurrence.  Consequently, -the results from
the September data analysis can be used to indicate an upper
value of a range of frequencies at which the 8-hour CO
standard is exceeded; the results from the August data can
be used to indicate a lower value of the range.  The ranges
for 1970, and for 1980 with various aircraft contributions,
is presented in Table 16.

1-Hour CO Concentrations at the Los Angeles Airport.  The 1-
hour CO air quality standard of 35 ppm (10 uq/m3) was
exceeded at only one of the outdoor continuous sampling
locations at the Los Angeles Airport.  A summary of the 1-
hour sampling data at these receptors is presented in Table
17, which indicates that only at site 205 was the 1-hour CO
standard frequently exceeded.  Site 205 was located next to
heavy automobile traffic en World Way Boulevard at an
automobile passenger unloading area.  The 1-hour CO standard
was exceeded 12 times during the approximately 1-week period
of sampler operation.  Expected reductions in CO emissions
from automobiles probably would reduce concentrations at
sites such as 205 to levels below the 1-hour standard.
Generally the 8-hour CO standard of 10 ug/m3 is the most
difficult of the two standards to reach,  and statistically
if the 8-hour standard is met, the 1-hour CO standard will
also be met.»3

Carbon Monoxide Concentrations at Other Airports.
Dispersion modeling was used to provide estimates of 1-hour
CO concetnrations both from aircraft alone and from all
airport and adjacent sources within 10 kilometers of the
center of each airport.  This modeling was done for Los
Angeles, J. F. Kennedy, Chicago-O'Hare, and Washington
National Airports.  The results, presented in Table 18, are
predicted concentrations at airport area points where: (1)
the general public could have access for 1-hour periods, and
(2) the total concentrations, as estimated by dispersion
modeling, exceed the standards.

Although minimal reliance should be placed on the precise
numerical values predicted by the model,  these values are of
the same order of magnitude as the values from actual
measurements presented in Table 17.  These results indicate
that localized carbon monoxide effects are not limited to
Los Angeles Airport.

The potential of high 8-hour CO concentrations downwind of
other airports, with large aircraft contributions, exists
near airports besides Los Angeles Airport.  As previously
discussed. Table 11 indicates the potential of such
concentrations at six additional airports.
                                39

-------
                               TABLE 16

    EXPECTED RANGE OF DAYS THAT 8-HR STANDARD WILL BE EXCEEDED IN
             VICINITY OF L.A. AIRPORT, 1970 and 1980a
Based on
August
Datab
Based on
September
Data
   Days Standard Exceeded
          in 1970

   Days Standard Exceeded
   in 1980, With Following %
   Contributions by Aircraft
   (at 1970 emission levels)
   to Total CO Concentrations

           80%

           60%

           40%

           20%

            0%
39
36

22

 9

 1

 0
to
to

to

to

to

to
65
61

49

32

14

 1
 aBecause the highest CO concentrations occur during winter months,
it is assumed that the frequency of exceeding the standard during the
winter quarter gives the frequency of exceeding the standard the
entire year.
   From Figures 2 and 4.
                                 40

-------
                                TABLE  17

                          LOS  ANGELES  AIRPORT

          NUMBER OF  TIMES THE 1-HOUR  CO  STANDARD WAS  EXCEEDED
       MAY 10  THROUGH NOVEMBER 9,  1970, CONTINUOUS SAMPLING  SITES
Site*
201
203
204
205
208
209
Downtown LA
Total Hours
of Sampling
3710
4256
4258
637
4326
4279
4965
Number of Hourly
Values When
Standard Exceeded
0
2
0
12
1
0
3
Highest Two
Hourly Values
27, 26
46, 40
23, 19
51, 49
37, 28
31, 27
37, 35
*Refer to Figure 1 for Location.
                                     41

-------
                              Table  18

                Dispersion Model Estimates of 1-Hour
                    Carbon Monoxide Concentrations
Site Location*
JFK (T)
JFK (T)
JFK (T)
LAX (P)
LAX (P)
ORD (T)
ORD (S)
DCA (P)
DCA (P)
CO Concentration, mg/nP
Aircraft Sources Only Total
85
4
3
55
32
21
9
110
45
100
45
44
62
45
41
41
120
59
*DCA = Washington National Airport, LAX = Los Angeles International
 Airport, JFK = John F. Kennedy International Airport,  and ORD =
 O'Hare Airport, Chicago

(T) = Terminal area

(P) = Peripheral area--away from terminals,  but within  airport
      boundary

(S) = Outside of airport boundary, in airport surroundings
                               42

-------
Hydrocarbon and Potential Oxidant Concentrations.  Isopleths
of 1970 hydrocarbon concentrations due to aircraft alone at
the Los Angeles Airport are presented in Figure 5.  These
isopleths are based on the dispersion modeling methodology
presented in Appendix B, and are a result of meteorological
conditions that are particularly conducive to high
hydrocarbon concentrations.  Such conditions would be
expected to occur at least once per year.

The results indicate that there are large areas surrounding
the airport where the hydrocarbon concentrations due to
aircraft are well in excess of the standard.

Between 1970 and 1980, Table 4 indicates that at the Los
Angeles Airport, hydrocarbon emissions from aircraft will
decline to about UQ% of their 1970 values.  These reductions
are reflected in Figure 6 which presents isopleths of 1980
hydrocarbon concentrations due to aircraft alone, at Los
Angeles Airport, based on meteorological conditions
equivalent to those used for the isopleths in Figure 5.
Even with the reduction in aircraft hydrocarbon emissions,
it is likely that in 1980 the hydrocarbon standard will
continue to be exceeded over a large area due to aircraft
emissions alone.

As indicated earlier, hydrocarbon concentrations at levels
typically found in the atmosphere are not harmful to health.
However, if airport hydrocarbon concentrations were followed
downwind for several hours under conditions conducive to the
accumulation of high oxidant concentrations,7 aircraft-
generated hydrocarbons could be expected to be large
contributors to downwind oxidant concentrations over the Los
Angeles area.

A modeling analysis was performed to estimate hydrocarbon
concentrations downwind of Los Angeles Airport in 1980.  The
meteorological conditions used were similar to those used
for Figures 5 and 6.  The methodology of this analysis is
presented in Appendix C, and results are presented in Figure
7.  The three curves in Figure 7 show nonmethane hydrocarbon
concentrations downwind of Los Angeles Airport resulting
from the surroundings plus total airport emissions, total
airport emissions alone, and aircraft emissions alone.  The
initial concentration at the western airport boundary (0 km
in Figure 7) is shown to be zero, which is a result of the
proximity of the western boundary to the ocean, wind
direction from the west, and the assumption of negligible
hydrocarbon concentrations in wind coming off at the ocean.
At a point 3 hours downwind (16 km from the eastern airport
boundary) the overall hydrocarbon concentration will have
                               43

-------
                                                                                                  1—•-.  .... '.,..  '
                                                                                                   	• •_ °  ':' :' :'- •'
£5.vv
ife

                                                                               TY!!;!'

                                            (numbers in^yg/m )
FIGURE 5   HYDROCARBON ISOPLETHS  IN  THE VICINITY OF LOS ANGELES  INTERNATIONAL:  AIRCRAFT SOURCES
                                     3-Hr Average for 1970 (6-9 AM)

-------
                 ww
                 r  ~'v^-
                 A

                                                                                      ;.	^.-_L •' i.Ji; -~;: -I';  __•_• J." ' -
                                                                                     rjTtS^Ti i":l i i i ."iKf^-'i"7=5 ,:i"j."
                                                (numbers  in

FIGURE 6    HYDROCARBON ISOPLETHS  IN  THE VICINITY OF  LOS ANGELES INTERNATIONAL:   AIRCRAFT SOURCES

                                        3-Hr Average for  1980 (6-9 AM)

-------
     600 «
                     FIGURE 7

CALCULATED NON-METHANE HYDROCARBON CONCENTRATIONS
     DOWNWIND OF LOS ANGELES AIRPORT FOR 1980
       WITH NON-AIRCRAFT SOURCES CONTROLLED
     500.
     400J
                                            Meteorological Conditions Used:
                                              Wind from West
                                              Stability Class 3
                                              Wind Speed 1.5m/sec
                                              Mixing Height = 200m
E
00
c
o
•H
C
01
o
c
o
u
     300
     200.
     100
                                                             Total, All Sources
                                                             Total Airport
                                                             Aircraft Alone
                      Airport  East  Boundary
                            (3.2  km)
8
                                            12
                                   16
20
24
                               DOWNWIND  DISTANCE,  KILOMETERS

-------
been in excess of the standard for 3 hours, enough time for
possible formation of oxidant in concentrations exceeding
the standard.

It is important to emphasize that this analysis was
performed for 1980.  If it were repeated for 1970, the
concentrations for each of the curves would be at least
double the 1980 values.

The emissions densities presented in Table 15 indicate that
among the four airports studied, emission densities from
aircraft alone are highest at Los Angeles Airport.  However,
the range among these emission density values is still less
than a factor of 2.3 in 1980, indicating that ccnclusions
concerning future aircraft-generated hydrocarbon and oxidant
concentrations at the Los Angeles Airport and vicinity apply
generally to the other airports studied, and that additional
reductions in aircraft-generated hydrocarbon concentrations
are necessary.

Oxides of Nitrogen.  Although the ambient air guality
standard is for NO2  (100 ug/m3, annual concentration), the
result of the dispersion modeling is presented as oxides of
nitrogen (NOx).  This is done because there exists no well-
defined relationship for the conversion of NO to NO2.   In
the presence of hydrocarbons; the NO to NO2 conversion is
accelerated; best estimates indicate that 90 percent of the
NO is converted to NO2 within a 2-hour period in the
presence of sunlight.  The reaction is essentially
negligible at night.  Considering all NOx as N02 could
result in an overestimation of annual average
concentrations.

Oxides of nitrogen concentrations due to aircraft alone are
presented in Figure 8 for Los Angeles Airport area for 1970.
These modeling approximations indicate that LAX is
responsible for NOx impact over a large area surrounding the
airport.  With growth of overall aircraft activity, and the
changeover to bigger and higher pressure ratio turbine
engines, aircraft emissions of NOx will increase greatly
between 1970 and 1980.  Present and expected future NOx
emissions from aircraft at the four major airports studied
are given in Table 15, which indicates that between 1970 and
1980 aircraft emissions of NOx will increase by factors of
2.2 at O'Hare Airport, 1.U at Washington National Airport,
1.5 at Los Angeles International Airport, and 2.9 at John F.
Kennedy Airport.

The general affect of increased NOx emissions from aircraft
at LAX is reflected in Figure 9, which presents isopleths of
                                 47

-------



                                                                                          r?r: n'Tnv' t
                                                                                           J     »•
                      \ v    -rn
                       \  V  L^1;?.**
                                                                     !HtK
                                                   (numbers  in/xg/m )

^•--~z.~^': FIGURE 8    NOJ: ISOPLETHS  IN THE VICINITY OF  LOS ANGELES INTERNATIONAL:  AIRCRAFT SOURCES

                                                Annual  Average for 1970

-------
1980 NOx concentrations due to aircraft.  Figure 9 indicates
that NOx concentrations due to aircraft alone could be
widespread in residential areas around LAX, and that in some
areas, the NO2 concentrations due to aircraft are comparable
to the standard.  It should be emphasized -that these NOx
concentrations are due to aircraft alone, and NOx emissions
from other sources would be expected to significantly
increase the concentrations plotted in Figures 8 and 9.

NOx concentrations of similar magnitude to those in Figures
8 and 9 can be expected in the vicinity of other airports.
For example, isopleths showing expected 1980 NOx emissions
densities due to aircraft alone for O'Hare Airport are
presented in Figure 10.  Without emission controls, aircraft
using O'Hare Airport can be expected to be large future
contributors to localized NOx concentrations, as was the
case for Los Angeles Airport.

Smoke and Particulates.  Smoke generated by aircraft causes
significant reductions in visibility and is a cause of
widespread complaint by affected citizens.

The 1-year air guality monitoring program conducted at Los
Angeles International Airport indicated increased soiling
effects in the airport vicinity due to aircraft activity.
Atmospheric measurements of particulates using a tape
sampler technigue gave higher readings (indicative of
soiling)  for the airport area than for locations several
miles removed, such as downtown Los Angeles.  Additionally,
sampling at sites surrounding and adjacent to the Los
Angeles Airport area showed increasing soiling values from
upwind of the airport to a maximum immediately downwind of
the airport.

Measurement of total weight of particulate material,  based
on Hi-Vol sampling, showed little variation between airport
and downtown areas.

Results of the dispersion modeling analysis for all four
airports indicated that particulate concentrations due to
aircraft in some parts of the airports could exceed the
secondary particulate air guality standards.
                                   49

-------

                                                                         Of^r''^^'^^ i!-^:;!-
                                                                        c^x^i^r
                                                                         iV? 's l:-;.'i ;
                                                                         r, •-• il ;:•!,•

                                                                         !^^S,
                                                                         '^C-i ,.?
                                                                          si!
                                                                                   ^     "    '
                                     (numbers  in//g/m )
.: FIGURE 9    NO  ISOPLETHS  IN THE VICINITY OF LOS ANGELES  INTERNATIONAL:  AIRCRAFT SOURCES


                                  Annual Average for  1980

-------
              HARE
            CHICAGO
           TERNATIO
            AIRPOR
                 FIGURE 10     (numbers in^ltg/m )

NO  ISOPLETHS IN THE VICINITY OF CHICAGQ-Q'HARE INTERNATIONAL:  AIRCRAFT SOURCES

                            Annual Average for 1980

-------
 TECHNOLOGICAL FEASIBILITY OF CONTROLLING

                 AIRCRAFT EMISSIONS
    Information on emission control  methods is necessary to
determine the levels to which aircraft emissions can
feasibly be reduced.  An earlier Federal study,* »*
identified potential control approaches including
modification of aircraft engines,  fuels, and ground
operational procedures.   This study  indicated that
modification of aircraft engines and ground operational
procedures appear to be the most feasible and effective
control procedures.  More recently,  the Aerospace Industries
Association (AIA)  has issued a reportis summarizing results
of investigations conducted by industry on: (1)  emission
characteristics of aircraft gas turbine engines; and (2)
potential methods for reducing aircraft turbine engine
emissions.  The AIA report also identifies the possibility
of reducing emissions through modifications of engines
(especially combustor design)  and  of ground operational
procedures.

    The current reassessment of control methods must
consider each of the aforementioned  approaches.   In
assessing the feasibility of a control method, four factors
must be explored:  (1)  effect of the  method on the
functioning or capacity of the aircraft system;  (2)
effectiveness of the method in reducing emissions; (3)  cost
of utilizing the method;  and (U) time required for
implementing the method.   Information on emission-
measurement instrumentation is also  necessary to ensure that
aircraft emissions can be measured with the accuracy and
sensitivity required for enforcing the desired standards.

    The Environmental Protection Agency has conducted
several studies (references 16-27)  to obtain information for
assessment of aircraft emission control methods.  This
report summarizes the information obtained in these
investigations.  The specific objectives of this analysis  of
aircraft emission control technology are:

       (1)  To identify methods of controlling aircraft
emissions through modification of engines, fuels,  and ground
operations.
                                  53

-------
         (2) To estimate their effectiveness in reducing
 aircraft  emissions.

         (3) To estimate the time required for and cost of
 implementation.

         (4) To assess the technology of measuring emissions
 from aircraft engines and to identify areas requiring
 advancements in instrumentation or test procedures.

     Emission control by fuel modifications was reassessed to
 evaluate developments in aircraft fuel technology.   This
 investigation was discontinued after preliminary analysis
 indicated that no significant reductions in emissions could
 be achieved by modifying fuels, except for reduction*- in
 sulfur or lead content that result in proportionate
 reductions of SO  and lead emissions.

     A list of specific emission control methods involving
 engine modifications was formulated on the basis of
 preliminary analyses, which indicated that each method was
 feasible and offered a significant reduction  in one or more
 emission classes.   Feasibility was assessed on the  basis of
 the following factors:

        (1)  No reduction in engine  reliability  (safety) .

        (2)  Little  or no reduction  in engine performance
 (power-weight ratio).

        (3)  Reasonable cost of  implementation.

     The  preliminary  list  of  control  methods was  then
 subjected  to  more  detailed analysis  of  control  effectiveness
 and  implementation costs.   Control methods  involving  changes
 in  ground  operations were  evaluated  in  a similar manner.

     Evaluation of the emission  control  methods  involving
 engine modifications gave  primary consideration  to the
 following emission classes: carbon monoxide (CO), nitrogen
 oxides  (NOx), total  hydrocarbons (including drained fuel)
 (THC), dry  particulates  (DP) , and smoke.

 EMISSION CONTROL BY ENGINE MODIFICATION

 Engine Classification

    To facilitate analyses of engine modificaticns,  aircraft
engines are categorized according to their thrust or power
level.  The classification system is indicated in Table 19.
                                   54

-------
                         TABLE 19

            AIRCRAFT ENGINE CLASSIFICATION
Engine class
Engine Type
   Power Range,
 Ib thrust or eshp
     Tl

     T2

     T3

     PI
  Turbine

  Turbine

  Turbine

  Piston
  Less than 6,000

  6,000 to 29,000

Greater than 29,000

 All piston engines
                              55

-------
     Although this classification system is  based simply upon
 power level it effectively groups engines of  similar
 emission potential (when the emission rates are normalized
 according to an appropriate engine-size parameter) .   Also,
 since effectiveness factors and costs of the  control methods
 are  similar for engine models within each class,  the system
 is particularly useful for this analysis.

     Three classes of turbine engines are defined,  and all
 piston engines are included in a single class.   This system
 thus categorizes engines according to their principal
 applications and according to certain design  characteristics
 that affect emission rates.

     The  small turbine engine class (Tl)  includes  most of the
 turboshaft and small turbojet and turbofan  engines used in
 business and small commercial aircraft.   It also  includes
 auxiliary power units (APU)  used on large commercial
 aircraft.   These engines are considered as  one  class because
 the  relatively small size of the combustor  components (or
 large surface-volume ratio)  makes control of  certain
 emissions  more difficult than with larger engines.

     The  next turbine engine class (T2)  includes most of the
 turbojet and turbofan engines used in medium-to-large
 commercial aircraft.   The design characteristics  of  most of
 these engines are basically similar.

     The  third turbine engine class (T3)  includes  large
 turbofan engines for "jumbo" transport  aircraft and  the SST
 engines  currently in use or under development.

 Emission Control Methods and Effectiveness

     Technology for controlling emissions from aircraft
 engines  by means of engine  modifications has been analyzed.
 The  purpose  of this analysis  was  to  identify specific
 methods  of reducing pollutant emissions from aircraft
 engines  and  to indicate  the  reductions  in rates of emission
 attainable by these methods.   Various engine modifications
 appear to  be  feasible  in  that they can be applied to
 aircraft without degrading  engine  reliability or seriously
 reducing aircraft performance.   Costs of implementing these
 control  methods  also  appear  to be  within reasonable limits,
 at least in  preliminary  analysis.

 Turbine  Engines  - The  engine  modification control methods
 considered  feasible for  turbine engines are listed and
described  briefly in Table  20.   Six methods are, at least in
                                   56

-------
  Table 20.   ENGINE  MODIFICATIONS  FOR  EMISSION  CONTROL  FOR  EXISTING AND  FUTURE

                                  TURBINE  ENGINES
       Control  method
                    Modification
Existing engines
  tl  - Minor combustion
       chamber redesign


  t2 - Major combustion
       chamber redesign


  t3 - Fuel  drainage control


  t4 - Divided fuel  supply
       system


  t5 - Water injection
  t6 - Modify compressor air
       bleed rate
Minor modification of combustion chamber and fuel
nozzle to achieve best state-of-art emission
performance.

Major modification of combustion chamber and fuel
nozzle incorporating advanced fuel injection concepts
(carburetion or prevaporlzation).

Modify fuel supply system or fuel  drainage system to
eliminate release of drained fuel  to environment.

Provide independent fuel supplies  to subsets of fuel
nozzles to allow shutdown of one or more subsets dur-
ing low-power operation.

Install water injection system for short duration use
during maximum power (takeoff and climb-out) opera-
tion.

Increase air bleed rate from compressor at low-power
operation to increase combustor fuel-air ratio.
Future engines
  t7 - Variable-geometry
       combustion chamber

  t8 - Staged injection
       combustor
Use of variable airflow distribution to provide inde-
pendent control of combustion zone fuel-air ratio.

Use of advanced combustor design concept involving a
series of combustion zones with independently con-
trolled fuel injection in each zone.
                                          57

-------
 principle, applicable to existing engines by retrofitting of
 new or modified parts, and to engines currently in
 production.  Two methods are considered to be applicable
 only to future engines of new design, since the
 modifications required are too extensive to be applied to
 engines for which development has been completed.

     The first control method consists of simple
 modifications of the combustor and fuel nozzles to reduce
 all emission rates to the best levels currently attainable
 within each engine class.  The degree of control attainable
 depends upon the performance of specific engines compared
 with those engines in the same class demonstrating the
 lowest emission rates.   In general,  this control method
 requires emission quality control (emission reduction to
 levels demonstrated by other engines of that model).
 Additionally,  for certain high-emission engine models,  it
 means emission reduction  to the level of other engines of
 the same class.   Each of  the other control methods is more
 specifically directed at  one or two  pollutant classes.

     Reductions in  emissions achievable through the use of a
 control method vary with  the pollutant considered,  the
 engine class,  and  the engine operating mode.   Estimates of
 the effectiveness  of each control method have been made for
 all combinations of these factors and are presented in
 Tables 21  and  22.   The  estimation of emission control
 effectiveness  for  turbine engines is based upon  reductions
 attainable from "lowest current emission rates."  These
 rates  are  defined  as those  attainable through control  method
 tl  (table  19), minor combustion chamber redesign.

     It is  predicted that  all  engines in  each  class  could  be
 modified to achieve these "best  rates."  The values  of these
 rates  are  listed in Table 21.  These "best rates" are not
 the  lowest  rates indicated  for each  engine class, but are
 rates  near  the low  end of those  emission  rates that appear
 to be  realistically  attainable.   The use  of the  "best rate"
 basis  is necessary  to allow effectiveness  estimates for each
 engine class.  Because of the wide variations in actual
 emission rates of turbine engines, an effectiveness analysis
 based  on average rates would be less significant.  Table 22
 indicates the effectiveness of control methods t2 through
 t8.  Some estimates are based upon demonstrated performance.
 Most, however, are not based on direct experience with these
 control methods on aircraft engines.   Therefore, estimates
of effectiveness are based largely on theoretical analyses
of engine performance under the operating conditions
associated with the control methods.   The bases for these
estimates are summarized in Table 23.
                                  58

-------
 Table 21.   EFFECTIVENESS  OF  tl  -  MINOR  COMBUSTION  CHAMBER

 REDESIGN3  - ON  REDUCTION  OF  EMISSIONS FROM  TURBINE ENGINES

         ^(Emission rates  in  lb/1000 Ib  of fuel)
Engine
class
Tl
Tl
Tl
Tl
T2
T2
T2
T2
T3
T3
T3
T3
Pollutant
CO
THC
NOX
DP
CO
THC
NOX
DP
CO
THC
NOX
DP
Mode
Idle/taxi
25
10
3
0.2
45
10
2
0.2
50
10
3
0.1
Approach
5
1
7
0.5
6
1
6
0.5
3
1
10
0.1
Takeoff
2
0.2
11
0.5
1
0.1
12
0.5
0.5
0.1
40
0.1
aMinor combustor redesign is  assumed
 invisible or "smokeless" levels for
to reduce the smoke to
all engine classes.
                         59

-------
                                      Table  22
                  Effectiveness  of  Engine Modification in Control
               of Emissions  from Turbine Engines, by Operating Mode3
Control
method
h
t2
t2
t2
t2
t3
t3
t3
t4
t4
t4
t4
t4
t4
t5
t5
t5
t6
t6
t6
t6
t6
t6
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
t7 or t8
Engine
class

Tl
Tl
T2
T3
Tl
T2
T3
Tl
Tl
T2
T2
T3
T3
Tl
T2
T3
Tl
Tl
T2
T2
T3
T3
Tl
Tl
Tl
Tl
T2
T2
T2
T2
T3
T3
T3
t7 or t8 ' T3
Pollutant

DP
NOX
DP

Idle/taxi

0.5
NCC
0.5
NOX j NC
THC
THC
THC
CO
THC
CO
THC
CO
THC
NOX
NOX
NOX
CO
THC
CO
THC
CO
THC
CO
THC
NOX
DP
CO
THC
NOX
DP
CO
THC
NOX
DP
NC
NC
NC
0.25
0.25
Mode
Approach

0.5
NC
0.5
NC
NC
NC
NC
NC
NC
0.25 j NC
0.25
0.25
0.25
NC
NC
NC
0.5
0.5
0.5
0.5
0.5
0.5
0.1
0.1
NC
0.5
0.1
0.1
NC
0.5
0.1
0.1
NC
0.5
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
0.5
NC
NC
NC
0.5
NC
NC
NC
0.5
Takeoff

0.5
0.5
0.5
0.5
Qd
Od
Od
NC
NC
NC
NC
NC
NC
0.1
0.1
0.1
NC
NC
NC
NC
NC
NC
NC
NC
0.75
0.5
NC
NC
0.75
0.5
NC
NC
0.75
0.5
aEmission rate is fraction of best current
 through minor combustion chamber redesign

 t2 = Major combustion chamber redesign
 t3 = Fuel drainage control
 t4 = Divided fuel supply system
 t5 = Water injection
 t6 = Modify compressor air bleed rate
 t7 = Variable-geometry combustion chamber
 t8 = Staged injection combustor

CNC indicates no change

dRefers to raw fuel drainage only
rate assumed  to be attainable
and with control method  cited
                                          60

-------
                                        Table  23

            Bases  for  Control  Method  Effectiveness  Estimates  for Turbine Engines
      Control method
                                                      Rationale
tl - Minor combustion
     chamber redesign
t2 - Major combustion
     chamber redesign
t3 - Fuel drainage control
t4 - Divided fuel supply
     system
 t5  - Water  injection
 t6 -  Modify compressor  air
 t7 - Variable-geometry
      combustion chamber

 t8 - Staged injection
      combustor
The assumption is made that emission rates for all
engines within a given class can be reduced to common,
optimum levels (on a lb/1000 Ib fuel basis) by minor
combustor modifications.  These optimum emission rates
are based on the best performance reported for each
engine class, excluding extreme data points.
Estimates are based on reports of carbureting fuel
injector performance and reduction of smoke emission.
Concept is incorporated in some Class T3 engines.
Estimates are based on assumption that best emission
rate for Class Tl and T2 engines is at an exhaust
visibility threshold at maximum power.  Carburetion
appears to reduce smoke level, and presumably particu-
late emissions,  to approximately half that level.  Addi-
tionally, premixing of air and fuel can be used  to give
substantial NO.,  reduction by decreasing residence time
              A.
in the combustor.
Estimate is based on the assumption that  fuel drainage
can be completely eliminated by collecting drained fuel
and returning to fuel  tank.
Control method results  in combustion  zone  fuel-air ratio
similar to that  at approach condition.  Reduction in  CO
and THC from  idle to approach  is approximately  90 per-
cent in Class Tl and T2 engines and 90 percent  in
Class  T3 engines.  Effectiveness is reduced  by  one order
because combustor is not operating  at "well-designed"
condition.
Water  injection  is assumed  only at  takeoff  at  a rate
up  to  twice  the  fuel rate.  Water  injection  into
compressor or diffuser is  assumed  to  be by system
similar  to those in  current use.   Effectiveness based
upon published  results with  steam  injection.     Water
injection  assumed  to be of  equal effectiveness  when
injected  upstream  of combustor.
Assumptions  are  (1)  fraction  of  air that  can be bled  is
small  so  that engine operating point  is  nearly unchanged,
 (2)  combustor f/a  varies  inversely with  air  bleed rate,
 and  (3)  CO and  THC  emissions  at  idle  vary as the (air
mass  flow rate)3 and inversely as  (f/a)  .  This
 relationship is  based  upon data from Reference 14.
 If maximum air  bleed rate  is  20 percent,  CO and THC
emission rates  are reduced by 50  percent.
Combustor primary zone is  assumed  to operate at a con-
 stant  f/a equal to normal  f/a at  approach power condition
 (primary equivalence ratio = 0.6).  CO and THC emissions
 at idle are  reduced  to levels corresponding to approach
 power, or by 90 percent for Classes Tl,  T2,  and T3.   This
 incorporates design characteristics that provide a good
 mixture in the combustion zone.   This feature and con-
 stant  f/a operation combine to reduce NOX emissions  at
 full power by 75 percent26 and particulate emissions by
 50 percent at all power levels as in t2.	
                                                61

-------
     Emission-control effectiveness is indicated in Tables
 21, 22, and 23 for each control method and for each
 pollutant for which a significant degree of control
 expected.  Pollutants for which little or no control
 expected are not listed.  Effectiveness is indicated
 separately for each engine class.  No specific estimates
 have been made for control of reactive hydrocarbons, odor,
 or aldehydes because control methods applicable to these
 emissions are not yet identified.  Reductions in these
 emissions are expected along with reductions in THC
 emissions.  Any of the modifications defined for existing
 turbine engines (tl through t6)  could be combined to achieve
 increased emission control effectiveness; exceptions are
 modifications tl and t6, which are mutually exclusive.

 Piston Engines - The control methods considered feasible for
 aircraft piston engines are listed with brief descriptions
 in Table 2U.   These methods include most of the approaches
 that have been developed for automotive engines for control
 of carbon monoxide and total hydrocarbon.  Methods for
 controlling nitrogen oxide (NOx)  emissions are not included
 because the fuel-rich operating  conditions of aircraft
 piston engines result in low NOx emission rates.   Piston
 engine emission characteristics  are included in Figure 11.
 As this figure indicates,  fuel-air ratio has a significant
 effect on aircraft piston  engine emissions.   Plans for
 changes in engine  operating conditions  to reduce  CO and THC
 emissions must also consider NOx to prevent significant
 increases in  emissions of  this pollutant.

     Table 2U  lists nine piston-engine control methods,
 including the use  of direct-flame afterburners and water
 injection,  methods that are not  being considered  currently
 for automotive engines.  Afterburners might  be used  to
 advantage in  this  application because they can utilize  the
 high-velocity airflow around  the  aircraft.   Although
 aircraft  piston engines  and automobile  engines are
 fundamentally similar,  their  applications are  significantly
 different,  with different  requirements.   Reliability is  of
 primary importance  in  aircraft piston engine  applications
 and  therefore  is given paramount  consideration  in
 identifying applicable control methods.  The  piston-engine
 emission-control methods were identified  and  evaluated
 through reviews of  published  investigations.  Of the methods
 identified, all are considered applicable to existing
 engines except those that would reguire redesign of the
 basic  engine or its control systems.

    Effectiveness estimates for piston engines are based on
reductions of current uncontrolled rates listed in Table 25.
                                    62

-------
                                       Table  24

                      Engine Modifications  for Emission Control
                       for Existing and Future Piston Engines
       Control method
                     Modification
Existing engines
  pi - Fuel-air ratio
       control

  p2 - Simple air injection
  p3 - Thermal reactors
  p4 - Catalytic reactors
       for HC and CO
       control

  p5 - Direct-flame
       afterburner

  p6 - Water injection
  p7 - Positive crankcase
       ventilation
  p8 - Evaporative emission
       controls
Future engines
  p9 - Engine redesign
Limiting rich fuel-air ratios to only those
necessary for operational reliability.

Air injected at controlled rate into each engine
exhaust port.

Air injection thermal reactor installed in place of,
or downstream of, exhaust manifold.

Air injection catalytic reactor installed in exhaust
system.  Operation with lead-free or low-lead fuel
required.

Thermal reactor with injection of air and additional
fuel installed in exhaust system.

Water injected into intake manifold with simultaneous
reduction in fuel rate to provide for cooler engine
operation at leaner fuel-air ratios.

Current PCV system used with automotive engines applied
to aircraft engines.  Effective only in combination
with one of preceding control methods.

A group of control methods used singly or in combina-
tion to reduce evaporative losses from the fuel system.
Control methods commonly include charcoal absorbers and
vapor traps in combination with relatively complex
valving and fuel flow systems.
Coordinated redesign of combustion chamber geometry,
compression ratio, fuel distribution system, spark and
valve timing, fuel-air ratio, and cylinder wall temper-
ature to minimize emissions while maintaining opera-
tional reliability.
                                              63

-------
                                                           FIGURE  11


                                           PISTON ENGINE EMISSION CHARACTERISTICS
2
O
CO

O
•
CX,
00
w
     0.7
     0.6
       0.5
  .-> PC

  § i  °-4
0>Lt, K
*•   M
  U ^^
  M J3
  SC  0.3
  u
     0.2
     0.1
               3
              4-1
W)
JO
               tn
               C
               O
              •^
               U)
               tn
CU
TD
•r-(
X
O
C
O
               C
               O
              .G
              U
                  1600
                  1400
              §   1200
              o
                  1000
     800
                   600
                   400
     200
                                                                          BSFC
                                                                                                        OJ
                                                                                                   140   a
                                                                                                   120
                                                                                                                 100
                                                                                                   80
                                                                                                                  60
                                                                                                                  40
                                                                                                                   20
                                                                                                       O
                                                                                                       O
                                                                                                       O
                                                                                                        t/3
                                                                                                        C
                                                                                                        o
                                                                                                        •1-1
                                                                                                        U)
                                                                                                        in
                                                                                                        •H
                                                                                                        E
                                                                                                                        X
                                                                                                                       O
                                                                                                                       3

                                                                                                                       •o
                                                                                                                       C
                                                                                                       0

                                                                                                       H
                     8:1
                    9:1
                                                10:1
11:1
12:1
13:1
14:1
15:1
                                                           Air-Fuel  Ratio

-------
                               TABLE 25
                 CURRENT UNCONTROLLED EMISSION RATES
                         FOR PISTON ENGINES29
                         (lb/1000 lb of fuel)
Pollutant
CO
THCa
NOX (as N02)
Idle
896
48
7
Taxi
882
76
4
Approach
918
80
4
Takeoff
849
18
6
 Total hydrocarbon  (THC) emission rates have been increased by 50%  to
 account for crankcase blow-by emissions.  Evaporative emissions are
 not included in these rates.

                               TABLE  26

               EFFECTIVENESS OF ENGINE MODIFICATIONS IN
               CONTROL OF EMISSIONS FROM PISTON ENGINES
                            BY POLLUTANT3
Controlled
Control Method CO
PI
P2
P3
P4
P5
P6
P7
P8
P9
Fuel-air ratio control
- Simple air injection
- Thermal reactor
- Catalytic reactor
(requires lead-free fuel)
- Direct-flame
afterburner
- Water injection
- Positive crankcase
ventilation (PCV)
- Evaporative emission
control
- Engine redesign
0.5
0.1
0.1
0.1
0.1
0.1
NC
NC
0.1
Emission Rate
THCb
0.5
0.5
0.25
0.25
0.1
0.25
d
e
0.5
a Emission rate is fraction of uncontrolled emission rate after installation
  of control method and applies to all operating modes.
b Exhaust HC only.
c NC indicates no change.
d PCV would eliminate blow-by emissions when used in combination with pi,
  p2, p3, p4, p5, or p8.   Blow-by THC emission estimated to be equal to
  30% of uncontrolled exhaust emission.
e Evaporative controls would reduce THC emissions due to evaporation from
  fuel supply.  Magnutude  of uncontrolled emissions is inknown.

                                        65

-------
Since emission rates from piston engines do not vary as
widely as those from turbine enqines, control effectiveness
can be based on average rates for existing engines.  The
effectiveness estimates shown in Table 26 are based in most
cases on the application of individual control methods
without other engine changes.  Method p7 (PCV) is an
exception; it is considered to be most effective in
combination with method pi, p2, p3, pU, p5, p6, or p9.

    Piston-engine modifications p2 through p6 are designed
to serve the same function and, thus, are mutually
exclusive.  All of the others could be combined with any of
the modifications p2 through p6 to achieve increased
emission-control effectiveness.

Cost and Time Requirements for Control-Method Development
and Implementation

Existing Enqines - Estimates of the cost and time
requirements of applying each control method applicable to
existing engines are preliminary and are intended to
indicate the magnitude of costs and time involved in
controlling emissions from all civil aircraft.  Cost and
time requirements are estimated separately for control-
method development and implementation.  Development includes
all effort required from initial stages through
certification of the control method for a specific engine
class and tooling for production.  Implementation includes
initial installation of the control method on all engines of
a given class and costs associated with additional effort or
materials required for the control method throughout the
remaining service life of the engines.  These estimates are
based on a turbine engine life of 10 years with engine
overhauls every 5,000 hours or 2 1/2 years and a piston
engine life of 10 years with engine overhauls every 5,000
hours or 5 years.  Operating costs for water injection are
based upon experience with the water injection system on the
Boeing 717 aircraft.

    Because few of the control methods have been developed
for or applied to aircraft engines, and because many factors
affect total implementation costs, many uncertainties are
involved in the estimates.  Estimates of development costs
and time requirements are based on the previous experience
of aircraft engine manufacturers in similar modifications.
Estimates of implementation costs are considered to be less
certain than development costs.  The cost and service life
of a modified engine component is difficult to predict
accurately.  Yet these factors strongly affect the
cumulative costs of operating and maintaining the modified
                                     66

-------
 engine.   Because  implementation  costs  could  be far  greater
 than  development  costs  for  some  control  methods,  the
 estimates of implementation  costs  are  only indicative  of
 cost  penalties  that  might be involved  with control-method
 implementation.

    Three potential  levels of aircraft emission control
 entail three distinct associated cost  levels:  (1)
 retrofitting in-use  engines,  (2) modifying present
 production designs -to incorporate  emission control
 technology in new engines of models  presently  being
 produced,  and  (3) incorporating  emission control  technology
 into  new  engine designs during the design phases  of a  new
 engine model.

    Costs are highest for retrofitting in-use  engines, are
 significantly lower  for modifying  existing designs  in  new
 production engines and are lowest  for  incorporating emission
 technology during engine design.  Table  27 presents
 estimates  of the development  time, development costs,  and
 implementation  costs for application of the control methods
 that  could be retrofit-ted on  the current population of all
 civil engines.

    The development time requirements  listed in Table  27 are
 the periods required to reach the point where  installation
 of the control methods in existing engines could  begin.  The
 application of controls in all existing engines would
 require an additional time period that depends primarily on
 the availability of engine maintenance facilities.  The time
 for implementation is estimated to be  2 1/2 years for
 turbine engines and 5 years  for piston engines.  These time
 estimates  allow implementation of the emission control
 method during normal maintenance procedures,  minimizing
 cost.   Table 28 presents costs by category: air carrier,
 general aviation, and civil aviation.  These tables
 represent  cost to retrofit the various control methods to
 the current population of aircraft.

    From another perspective, implementation costs  may be
 expressed  as fractions of total engine costs.  For  a typical
class T2  (turbine) engine,  the cost of installing and
maintaining control systems ranges from $300 to $69,900,
assuming a 10-year engine life.   Based on a total engine
cost of $250,000, these control-method implementation costs
represent  0.1 to 25 percent of the total engine cost.   For a
typical piston engine,  estimated control-method
implementation costs range from  $100 to $1,000, also based
upon a 10-year engine life.   For a total engine cost of
                                    67

-------
                                    Table 27
                   Time and Costs for Modification of Current
                            Civil Aviation3 Engines
Control method
Turbine engines
Minor combustion
chamber redesign
Major combustion
chamber redesign
Fuel drainage control
Divided fuel supply
Water injection
Compressor air bleed
Piston engines
Simple air injection
Thermal reactor
Catalytic reactor
Direct-flame
afterburner
Water injection
Positive crankcase
ventilation
Evaporative emission
control
Development
time ,
years
2.5 to 5
2.5 to 7.5
1 to 2.5
5 to 7.5
2.5 to 4
4 to 6.5
1.5 to 3
3 to 6
2.5 to 5
3 to 6
1.5 to 3
2 to 4
1.5 to 2.5
Development
cost,
10b dollars
37
74
1.5
84
25
90
9
25
22
25
9
4
4
Implementation
cost,
10° dollars
383
665
5.4
102
175
58
165
424
535
424
400
94
269
"Civil aviation" includes air carrier and general aviation engines
                                          68

-------
                                       Table  28
                      Cost  Results  for  Turbine  Engine  Population
                              by  Separate  Use Categories
Engine
class
Tl
Tl
Tl
Tl
Tl
Tl
T2
T2
T2
T2
T2
T2
T3
T3
T3
T3
T3
T3
i
Control
method
tl
t2
t3
t4
t5
t6
tl
t2
t3
t4
t5
t6
tl
t2
*- O
t4
t5
t6
i
Cost
scaling
factor
0.35
0.35
--
0.35
0.35
0.35
1.00
1.00
--
1.00
1.00
1.00
1.64
1.64
1 C. 1.
1.64
1.64
1.64
|
Development ]
cost per
engine family,
106 dollars
0.90
1.80
0.05
1.80
0.62
2.20
0.90
1.80
0.05
1.80
0.62
2.20
0.90
1.80
0.05
1.80
0.62
2.20
Implementa-
tion cost
per engine,
103 dollars
12.4
21.3
0.1
3.7
5.5
2.1
35.5
69.9
0.3
10.5
15.6
6.0
58.3
100.0
n c.
17.2
25.6
9.9
Total
Air
carrier
19.2
34.5
0.4
14.9
9.8
15.5
243.0
^418.0
2.0
87.0
108.7
61.5
50.0
95.0
2.0
13.7
29.5
16.0
cost, 106 dollars
General
aviation
90.5
159.3
1.0
51.5
43.6
48.1
17.8
31.0
--
8.3
8.2
7.1
--
--
..
--
--
--
Civil
aviation3
109.7
193.8
1.4
66.4
53.4
63.6
259.8
449.6
2.0
95.3
116.9
68.6
50.0
95.0
o n
13.7
29.5
16.0
a"Civil aviation" includes  air carrier  and  general  aviation engines
                                              69

-------
$6,000, these implementation costs represent 2 to 65 percent
of the total.

    Retrofit cost and time estimates for turbine engines
were developed by using the application of low-smoke
combustors to the JT8D engine class as a reference for cases
in which no direct experience was available.  Cost and time
requirements for this modification, which is considered a
minor combustor redesign for a class T2 engine, were
estimated in detail in 1969.27 Requirements for other
control methods were determined essentially by proportioning
the cost and time expenditures according to the complexity
of the method, with respect to the reference case.
Requirements for other engine classes were determined by
using appropriate scaling factors and by again using the
JT8D modifications as reference.  Time and cost estimates
for piston engines are based largely on experience to date
with emission controls for automobile engines.  Significant
differences, such as certification and safety requirements
and production levels, were considered in scaling the costs
from the experience with automobiles.

    Costs of emission control technology are substantially
lower when applied to new engines only.  These costs are
less than one-half the retrofit costs on a per-engine basis.
These estimates cannot be totalled as were the retrofit
estimates because of uncertainty concerning the number of
engines that would be affected.

Future Engines - Cost estimates have been developed also for
incorporation of emission controls in future engines, that
is, engines that have not yet been developed.  These
estimates are defined only as fractions of total engine
cost, since no reasonable basis is available for estimating
the numbers of engines that would be affected.

    Emission control in turbine engines that is attained
through the use of advanced combustor-design concepts is
estimated to represent an increase in total engine cost of 3
to 1 percent.  Emission control in piston engines that is
achieved by engine-design modifications would not
necessarily result in any significant increase in engine
cost.  If greater control of emissions is required than can
be achieved by engine design modifications, however, one or
more of the control methods applicable to existing engines
will be necessary.  The costs of these control methods,
which involve the addition of auxiliary devices such as
thermal reactors, will be significant, probably in the range
of 5 to 10 percent of total engine cost.
                                     70

-------
    These estimates represent the increased costs of new
engines with emission controls installed.  Additional
continuing costs may accrue for maintenance of the controls.
These maintenance costs will be considerably less than those
entailed in modifications of existing engines.

 EMISSION CONTROL BY MODIFICATION OF GROUND OPERATIONS

Definition of Ground Operations

    The cycle of operations performed by an aircraft during
its arrival at and departure from an airport can be defined
quite precisely because most of these operations are
prescribed by airport or aircraft operating procedures.
Characteristic operating or LTO (landing-takeoff) cycles
have been defined for various classes of aircraft for
purposes of estimating pollutant emissions.

    The LTO cycle can be separated logically into flight and
ground operations.  Flight operations include the approach
and climb-out modes as well as landing and takeoff, even
though the latter occur partially on the ground.  Ground
operations include the taxi and idle modes of the cycle.
This separation is logical for two reasons.  First, flight
operations as defined here are those that cannot readily be
modified to reduce pollutant emissions.  Second, flight
operations are conducted almost entirely with aircraft
engines at full or part power; under these conditions,
pollutant emission rates are quite different from those at
the low power levels characteristic of ground operations.
Aircraft ground operations contribute substantially to the
concentrations of CO and THC at air carrier airports because
of the relatively high emission rates of these pollutants at
low engine power levels, and because ground operations are
largely confined to limited areas within the airport
boundaries.

Fjnission Control Methods

    Six methods offer some degree of control of CO and THC
emissions at air carrier airports by modification of
turbine-aircraft ground-operation procedures.

        (1) Increase engine speed during idle and taxi
operations.

        (2) Increase engine speed and reduce number of
engines operating during idle and taxi.
                                     71

-------
         (3) Reduce idle operating time by controlling
 departure times from gates.
            Reduce taxi operating time by transporting
 passengers to aircraft.

        (5)  Reduce taxi operating time by towing aircraft
 between runway and gate.

        (6)  Reduce operating time of aircraft auxiliary power
 supply by providing ground-based power supply.

     The first two methods reduce emissions by requiring that
 engines be operated at more efficient power settings  than
 those in current practice (Figure 12);  the next four  methods
 reduce emissions by reducing operating time of  either main
 or auxiliary engines.   The effectiveness of these methods in
 reducing emissions varies considerably.   Table  29 summarizes
 the reductions in CO and THC emissions that would result at
 Los Angeles International Airport from the six  suggested
 ground-operation changes.  Tables developed for other major
 air carrier airports show emission reductions of the  same
 magnitude.

     The control  methods listed,  with the possible exception
 of number 3,  are not applicable  to small,  piston-engine
 aircraft, and,  therefore, do not seem to offer  means  for
 controlling emissions  at general aviation  airports.   Periods
 of delay  at take-off are significant at  some  general
 aviation  airports;  however,  aircraft ground traffic at
 general aviation airports may not be sufficiently controlled
 to allow  an effective  system of  controlled gate  departures
 or engine start-ups to reduce periods of delay.

 Implementation Cost and Time Requirements

     The cost  and time  requirements of the  contrcl methods
 involving ground operation modifications have been estimated
 for Los Angeles  International.   Table 30 presents summary of
the estimates.   Implementation of these methods at other
airports would involve  costs of  the  same magnitude.
 Specific costs,  however,  would vary  with airport activity
 level and the present availability of auxiliary equipment.
FAA and the airlines have estimated  savings for control
method  2, and their estimates are within 2OX of the estimate
in Table 30.

    Tables 29 and 30 indicate that alternative 2 is the most
attractive means of reducing turbine aircraft emissions
                                    72

-------
                Normal Taxi-idle
    120
o
JE
cu
CL

Hi
c
•1-1
60
C

-------
                      Table 29
   Comparative Reductions Resulting from Control
Methods Applied at Los Angeles International Airport
1.
2.



3.
4.
5.
6.
i
Control method
Increase engine idle speed
Increase idle speed and use minimal
engines for taxi
Two engines
Single engine
Eliminate delays at gate and runway
Transport passengers between
terminal and aircraft
Tow aircraft to avoid taxi emissions
Avoid use of aircraft auxiliary
power units (APU)
Resultant emissions,
70 of uncontrolled
emissions
CO
71


53
39
90
98
34
96
Hydrocarbons
93


66
51
91
97
42
98.5
                               74

-------
                         Table 30

          Costs and Time for Operations Changes
           at Los Angeles International Airport
Control method
1.
2.
3.
4.
5.
6.
Increase engine speed
Increase speed, reduce
number
Control gate departure
Transport passengers
Tow aircraft
Reduce APU operation
Time,
years
0
0.3
5
2.5
1
0.5
Initial cost,
106 dollars
0
0
15
65
1.2
1.3
Annual operating
cost change,3
106 dollars
8.5
-0.7
-0.4
5.0
0.4
1.5
sign indicates an estimated savings
                                 75

-------
 providing  that  operational  and  safety  requirements can be
 met.

 COMPARATIVE EVALUATION OF EMISSION CONTROL METHODS

    The engine  and  ground operation modifications just
 discussed  can be  compared in terms of  effectiveness, cost,
 and implementation  time.  A "potential benefit  factor" has
 been defined to allow comparison  of cost/benefit of the
 emission control  methods.   The  potential benefit factor
 (PBF)  is the net  emission reduction resulting from a
 particular control  strategy, averaged  over the  next 20
 years, divided  by the cost.

                  PBF =  FYE x CE  x ECF
                              CP

 where  FYE  is the  fraction of the  next  20 years  that the
 control method  is effective; CE is the control  method
 effectiveness (the  percentage reduction of a particulate
 pollutant);  ECF  is the emission  contribution fraction
 (percentage of  total  aircraft emissions at relevant airports
 contributed by  engines affected by this control  strategy);
 and CP is  the cost  of the control strategy for  the pollutant
 considered.  Emissions at major carrier airports were used
 to determine effectiveness  of turbine  engine control methods
 and those  at general  aviation airports to determine
 effectiveness of  piston engine  emission control methods.

    The potential benefit factor  is a  measure of the cost-
 effectiveness of  each control strategy.  Potential benefit
 factors (Table  31)  have been calculated for the control
 strategies previously described as applied to (1)
 retrofitting in-use aircraft, (2) modifying new engines of
 present models, and  (3) incorporating control methods in new
 engine designs.   The  higher numbers represent the most cost-
 effective  strategies  for emission reduction.

    The potential benefit factors in Table 31 are a
 composite  for all turbine and piston engines.  Although
 these factors indicate the relative merits of the control
 methods, the factor for an individual engine classification
 may be significantly  different.   For example, retrofit of
 water injection for class T3 shows a potential benefit
 factor of  U.2, whereas the average for all turbine engines
 is only 1.1.  Additionally, while some control strategies
 show a high potential benefit number,  other strategies must
 also be used to achieve significant emission reductions.
For example, fuel venting represents from U to 20% of total
 hydrocarbon emissions, dependent  upon airport considered.
                                     76

-------
               Table 31




Comparison of Emission Control Methods
Control Method

Turbine Engines
A. Retrofit-Engine Modifications
1. Minor combustion chamber redesign
(APU)
2. Major combustion chamber redesign
(T3 and APU)
(T2 only)
3. Fuel drainage control
(T2 and T3 only)
4. Divided fuel supply
5. Water injection
(T3 only)
6. Compressor air bleed
B. New Production Engine Modification
1. Minor combustion chamber redesign
2. Major combustion chamber redesign
3. Fuel drainage control
4. Divided fuel supply
5. Water injection
(T3 only)
6. Compressor air bleed
C. Future Engine Emission Control
1. Fuel drainage control
2. Divided fuel supply
3. Water injection
(T3 only)
4. Compressor air bleed
5. Variable geometry combustion chamber
6. Staged injection combustor
D. Ground Operations Modification
1. Increase engine idle speed
2. Increase speed, reduce number
3. Eliminate delays
4. Transport passengers
5. Tow aircraft
6. Reduce APU operation
Piston Engine
A. Retrofit-Engine Modification
1. Fuel-air ratio control
2. Air injection
3. Thermal reactor
Potential Benefit Factor
HC & CO


0.37
(2.5)
0.3


10
(20)
1.5
--

1.3

5.0
4.6
30
5.0
--

4.0

30
15
--

15
25
25

2.4
105
10
0.1
75
1.0


50
5
2
NOX


0.37

1.1
(6.6)

--

--
1.4
(4.2)
--

5.0
4.6
--
--
1.4
(4.2)
--

--
--
2.0
(5.6)
--
25
25

--
--
--
--
--
--


--
--
--
Smoke


0.37

1.1

(5.0)
--

--
--

--

5.0
4.6
--
--
--

--

--
--
--

--
25
25

--
--
--
--
--
--


--
--
~~
                      77

-------
           Table 31 (Cont.)




Comparison of Emission Control Methods
Control Method






B.








C.









D.


4.
5.
6.
7.
8.

Catalytic reactor
Direct-flame afterburner
Water injection
Positive crankcase ventilation
Evaporative emission control
New Production Engine Modifications
1.
2.
3.
4.
5.
6.
7.
8.
Fuel-air ratio control
Air injection
Thermal reactor
Catalytic reactor
Direct-flame afterburner
Water injection
Positive crankcase ventilation
Evaporative emission control
Future Engines
1.
2.
3.
4.
5.
6.
7.
8.
9.
Fuel-air ratio control
Air injection
Thermal reactor
Catalytic reactor
Direct-flame afterburner
Water injection
Positive crankcase ventilation
Evaporative emission control
Engine redesign
Ground Operations Modifications
1.
Eliminate delays
Potential Benefit Factor
HC
1
1
2
3
1

500
30
6
5
3
15
50
3

500
30
6
5
3
15
50
6
25

10
& CO
.5



.5



.6
.0
.3


.0



.6
.0
.3


.0



NOX
--
--
--
--
--

--
--
--
--
--
--
--
--

	
--
--
--
--
--
--
--
—

*" —
Smoke
--
--
--
--
--

--
--
--
--
--
--
--
--

--
--
--
--
--
--
--
--
—

"
                      78

-------
Consequently, to achieve substantial reduction cf
hydrocarbon emissions a less attractive control method is
necessary in addition to eliminatinq fuel venting.

    A review of the PBF values in Table 31 supports the
following conclusions providing that all operational and
safety requirements can be met:

       (1) Modification 2 for ground operation procedures is
the most cost-effective method of reducing hydrocarbon and
carbon monoxide emissions from turbine engines,

       (2) Incorporating emission control methods into
design of new engines is the most cost-effective method of
over-all aircraft emission control.

       (3) Control of fuel-air ratio is the most cost-
effective method of reducing hydrocarbon and carbon monoxide
emissions from piston engines.

       (U) Retrofits of class T3 turbines is a more cost-
effective method for NOx control compared to retrofit of
other turbine engine classes.

       (5) Fuel drainage control has high PBF because of
extremely low cost of implementation  (CP) rather than high
control  effectiveness  (CE).

       Because cost-effectiveness varies significantly among
engine classes and control strategies, several factors in
addition to  cost and effectiveness  must be considered in
developing emission control  strategies for aircraft engines.

 EMISSION MEASUREMENT TECHNOLOGY

     Reliable methods for measuring  the rates at which
pollutants are emitted  from  aircraft engines are  required
for the  support of an emission-control program.   Emission
measurements are required for  evaluating the effectiveness
of  control methods, and specific measurement methods must be
incorporated in emission-control standards.

     The  state of emission-measurement technology  has been
assessed to  determine whether  measurement techniques are
sufficiently well advanced to  support the development of
emission-control methods and the implementation of  emission
standards for aircraft  engines.  The conclusion drawn from
this assessment is that current measurement technology will
meet the requirements  of an  emission-control program.
Although measurement techniques  for particulate emissions
                                     79

-------
 are inadequate at present, improved techniques are being
 developed throuqh cooperative government-industry action.

     Measurement of emission rates from an aircraft engine
 involves three major requirements:

        (1)  A test procedure specifying engine operating
 conditions.

        (2)  A sampling technique for obtaining a
 representative sample of exhaust gas.

        (3)  Analytical instrumentation  for determining
 pollutant concentrations in the exhaust-gas sample.

     Aircraft engine manufacturers,  FAA,  and EPA are  devoting
 substantial effort toward meeting these  requirements for
 measuring emissions from turbine engines.

 Sampling  and Test Procedures

     Obtaining a representative sample  of exhaust gas from  an
 aircraft  engine for analysis of emission rates is a  complex
 and difficult procedure.  Sampling  emissions from turbine
 engines  is  difficult at  the outset  because of the jet-blast
 environment in which the sampling equipment must be
 installed.   Beyond this  problem,  the following factors  all
 significantly affect the composition of  the exhaust  sample:

        (1)  Engine power  level.

        (2)  Temporal and  spatial variations in exhaust
 composition.

        (3)  Sampling-line diameter,  length,  material,  and
temperature.

        (*»)  Ambient temperature  and  humidity.

        (5)  Ambient pollutant  levels.

    Procedures  for sampling and analyzing turbine-engine
exhaust gases have been  under development for  several years
by engine manufacturers,  FAA, and EPA.  More  recently, the
Society of  Automotive Engineers Aircraft  Exhaust  Emission
Measurement  (E-31)  Committee  has been  formed to standardize
these procedures.   Standardization  of  measurement techniques
will minimize variations  resulting  from the factors listed
above; however, the  several sources of error  in collecting
exhaust samples and  the  variability of samples among
                                    80

-------
different engines must be considered in the establishment of
a standard emission measurement procedure.

    Sampling reguirements for aircraft piston engines are
similar to those for automobile engines.  The exhaust gases
are well mixed by the time they reach the exhaust stack
exit.  Conseguently, no factors are apparent, beyond those
already recognized as affecting automobile exhaust
emissions, that would cause variability in exhaust samples
from aircraft piston engines.  Differences in engine
operation, however, must be considered in the establishment
of a standard emission measurement procedure.

Emissions Measurement Instrumentation

    Measuring the concentrations of most gaseous pollutants
in exhaust samples from aircraft engines is generally within
the capabilities of existing instruments and should remain
so, even when engines are modified to reduce emission rates.

    The various types of instruments that are available and
in current use for aircraft emission measurement have been
reviewed.  Instruments that appear to be most suitable for
measuring turbine-engine emissions at the present time are
presented in Table 32.
                                    81

-------
                        Table  32

            Instrumentation for Measurement
              of Turbine Engine Emissions
      Measurement method
Ntm-dispersive infrared (NDIR)'

Heated flame ionization

Chemiluminescenee

Chemiluminescence3

SAE smokemeter (ARP1179)

None

Determined from fuel analysis

3-MBTH

Human odor panel
Pollutant class


   CO and CC>2

      THC

       NO

      NO 2

     Smoke

  Particulates

      so2

   Aldehydes

      Odor
aThe non-dispersive ultraviolet instrument (NDUV)
 may also prove acceptable for N0~ measurement
                                82

-------
APPENDIX A:
ANALYSIS OF CARBON MONOXIDE CONCENTRATION
AT LOS ANGELES INTERNATIONAL  AIRPORT
  When continuous air quality monitoring data  is  available,
  statistical analysis may be applied to determine  frequencies
  of occurrence  of any concentration for any averaging time
  either by interpolation of the data or by extrapolation if
  the available  data is limited.  It has been  observed that
  all air quality data regardless of averaging time follows a
  log normal distribution.*3

  The continuous carbon monoxide data taken at LAX  during six
  months in 1970 were analyzed statistically for  1-hour and 8-
  hour averaging times at several sites to determine the
  expected frequencies when the NAAQS would be exceeded.  With
  the use of the simple rollback technique, adjusted
  frequencies could be determined for changes  in  emissions and
  various control strategies for aircraft and  non-aircraft
  emission sources.  Dispersion modeling results  were used to
  predict the degree of influence aircraft emissions have in
  locations beyond the boundaries of Los Angeles  Airport.

  The analysis focused on the 8-hour exposure  case  in areas
  adjacent to the airport where it would be expected that
  people would meet the exposure time criteria either as
  residents or business employees.  The 1-hour exposure case
  would apply to the terminal area itself as well as the areas
  considered in  the 8-hour averaging time case.

  Corrections were made to the available ambient  data because
  of the recognized seasonal variation of carbon  monoxide
  levels in the  Los Angeles basin.  A recent report published
  by the LAAPCD  contained sufficient data to calculate the
  summer-winter  correction factors for the hourly and 8-hour
  averaging times.  The average correction factors  for the
  basin to convert August-September data to December-January
  data were found to be 1.5 for the 1-hour data and 1.9 for
  the 8-hour case.

  Data and statistical information on carbon monoxide analysis
  presented in a paper by Larsen31 were also utilized in this
  phase of the analysis.  The L. A. basin CO data in the
  Larsen paper were used to check the LAX data for  consistency
                                      83

-------
 in terms of the frequency and range of observed carbon
 monoxide levels.  Tabulated and plotted data in this
 reference indicate the air pollution hot spot represented by
 the Los Angeles Airport and its environs.  Figure A-l, taken
 from the reference shows this point quite clearly.  Figure 1
 in the main text of this report indicates the location of
 the continuous ambient carbon monoxide stations.  Station
 209 was chosen as representative of an off airport site for
 the 8 and 1-hour analysis.  Figure A-2 shows the plot of the
 raw station 209 data for the months of August and September.

 It is obvious that station 209 is directly influenced by the
 airport only when the wind is blowing from a westerly
 direction.   The September data were categorized into East or
 West influences and the results are plotted on Figure A-3.
 It can be seen that the composite plot is representative of
 both these  subcategories and therefore was used for all
 subsequent  analysis.   It further demonstrates that the
 airport exerts the same impact on the air quality at station
 209 as the  non-airport area sources surrounding it.   Figure
 2,  in the text of the report,  shows the August station 209
 frequency distributions for maximum 8-hour daily averages
 adjusted for the summer-winter correction factor.   The
 frequency of occurrence relating to one day per quarter is
 assumed to  be equivalent to the one day per year frequency
 associated  with the 8-hour NAAQS because it can be assumed
 that the worst exposure case would occur during the  winter
 quarter of  the year.   This plot has then been ad-justed
 (Figures A-4 and A-5)  for expected rollback emission
 reductions  of non-aircraft sources in combination  with
 various percent contributions  due to due to aircraft sources
 and assumed levels of  aircraft emission controls.  Similar
 methodology was used  in estimating expected 1980 CO
 concentrations with various aircraft contributicns.   These
 are given in the main  text.  Modeling results were used  to
 determine the  relating distribution  and magnitude  of
 aircraft  emissions around LAX.   It can  be  seen  that  the
 station 209  analysis is quite  representative  of  other areas
 adjacent  to  LAX where  adverse  influences of aircraft
 operations can be  expected  to  occur.

 The same  procedures were  followed  in  plotting the  adjusted
 September data  to  determine the  frequency with which the
 standard would be  expected  to  be exceeded for various
 percent aircraft contributions.  This data would represent
 the upper limits of the  analysis.

 Similar frequency  analysis can be  performed for the  1-hour
 exposure case.  However,  unless there is extreme variation
between the  slopes  (or standard geometric deviations) of the
                                    84

-------
                          FIGURE A-l.
      MAXIMUM ANNUAL 8-HOUR-AVERAGING-TIME CONCENTRATION OF

CARBON MONOXIDE EXPECTED  AT VARIOUS SITES IN THE LOS ANGELES AREA.
\  LOS ANGELES COUNTY

 \


   \


    \


      \
                                                        I.
                    \   *
                        30
                      \ SAN FERNANDO

                     —'  VALLEY          /    f

                          \       i°  *°   /    l'8'3
                    -'    • l»37     /««f    / .32  V •
                         * |      ^BURBANK A28     X^

                        HOLLYWOOD /37   / PASADENA
                               l.r^I  •   *-"*
                   fTf'j*™ "'I  a      "^^^     •   -^
           HOLLYWOOD /37  / PASADENA    "" • r*
                  4V.37* 38* •/DOWNTOWN      P
               ^5  ,VV'hs  «       lx     rj
             J.^ffi^f".,.  /.„    --^
                  Nn Wa^4<        r DISNEYLAND  ^^x-
    0  5  10


      miUf
                                  22
                                  DISNEYLAND
                                      23

                                        SANTA ANAV
                                      12* AIRPORT
                                   85

-------
    50
                                                 FIGURE A-?


                                 BASELINE DATA, DAILY MAXIMUM 8-HR. AVERAGE

                                 CO CONCENTRATIONS, STATION 209, LAX, 1970
a
a
c
o
•H
c
0)
O
c
o
o

o
o

M
3
O
    20
    10
     2 •
September Data
                                August Data
                                  90    80           50           20    10


                           Probability (%) of Exceeding the Given Pollutant  Level
                                                  «  t
                                                     0.1

-------
                                                    FIGURE A-3

                  FREQUENCY DISTRIBUTION  FOR 8-HR.  CO DATA',  STATION 209, LAX, SEPTEMBER 1970
00
          o.
          o.
         H
         z
         u
         u
         z
         o
         u
          I
         00
            60 T
            40 -
            20 '
10 ••
          Key

           o •- easterly wind  influence.

           A -- westerly wind  influence.
                                 —#-

                                 95
                      90      80            50           20


Probability (%) of exceeding  the  given  pollutant  level.
                                                                 10
                                                                                             0.1

-------
                                                     FIGURE  A-4
00
00
          E
          a
          a
          c
          o
          •l-l
          4-1
 C
 Q)
 O
 c
 o
o

o
u

 (-1
 3
 O

 I
oo
                         EXPECTED CO CONCENTRATION  DISTRIBUTION,  WINTER,  STATION 209,  LAX

                                       FOR 80 PERCENT AIRCRAFT CONTRIBUTION
              40 r
              20
              10
                99
                                     39 days/year
                    Ambient AQ Standard, 9 ppm
                                90         70      50      30         10



                                Probability (%) of exceeding given pollutant level

-------
                                                   FIGURE A-5


                               EXPECTED CO DISTRIBUTION, WINTER, STATION 209, LAX

                                      FOR 20 PERCENT AIRCRAFT CONTRIBUTION
           40
00
       E
       a
       ex
       c
       o
C
0)
o

o
CJ

o
o

t-l
3
O
       oo
            20
            10


             8
           Ambient  AQ  Standard,  9 ppm
              99
                                                  .1.
                                                                     JL
                       90          70       50       30         10              1


                      Probability  (%) of exceeding the given pollutant  level

-------
1-hour data and -the 8-hour averaging time data, the 1-hour
standard will be met if the strategies are imposed to meet
the 8-hour standard.  This wculd appear to be the case in
those areas at LAX where the 1-hour GO levels are higher
than the standard at the present time.
                                      90

-------
                     APPENDIX B:

 DISPERSION MODELING METHODOLOGY AND

                ISOPLETH DERIVATION
    The primary and most direct method of estimating
aircraft contributions to air pollutant concentrations
involved the application of frequently used dispersion
modeling procedures to estimate air pollutant concentrations
caused by aircraft alone and by all sources located in the
airport vicinity (within a 10-kilometer radius of the
airport center). Dispersion models similar to the one used
in this study are specified by EPA as one means of showing
that implementation plans for certain regions will be
adequate to meet the  ambient air quality standards.  Much of
the analysis of aircraft air quality impact presented in
this report is based  on modeling work performed, under EPA
contract, by Northern Research and Engineering Corporation.
A general description of the modeling procedure is presented
here; a more detailed account of the modeling work and
results is available  in the contract report.'

    The procedure in  the modeling study involved:  (1)
approximating emission sources as continuous, stationary
point sources of constant strength over the time period
being considered, (2) modeling the dispersion of pollutants
from these sources  using an empirical mathematical model,
and  (3) estimating  concentrations at specified receptor
points by summing the pollutant contributions from each
point source, and (U) constructing isopleths of estimated
pollutant concentrations based on the estimated receptor
point concentrations.

    The point sources used  in the modeling approximated the
location and strength of emission sources at each of the
four airports studied.  Lines along which automobile or
aircraft movement occur were represented by series of point
sources.  Area sources, representing airport surroundings
out to a 10-kilometer radius  from the airport center, were
represented by circular arrangements of point sources around
the airports.  Altogether,  1U9 to 276 point sources were
used for each air carrier airport, depending on the  size and
complexity of the airport.  The number of sources was chosen
to provide a reasonable approximation of emissions at the
                                      91

-------
 airport  and in the vicinity  without  need  for  excessive
 computer time or computer  program  complexity.

     The  basis of the  atmospheric dispersion modeling is an
 empirical,  mathematical  approximation of  pollutant
 dispersion  after emission  from  a point  source.  This
 approximation yields  a plume whose concentration
 distribution is Gaussian in  the vertical  and  crosswind
 direction.   The distribution is dependent upon  downwind
 distance from the source and on atmospheric stability.
 Eventually  the upper  boundary of the atmospheric mixing
 layer restricts vertical spread of the  plume  and modifies
 the  distribution of pollutants  in  the vertical  direction.
 This dispersion model should be considered as a general
 approximation of airport dispersion  patterns; considerable
 model development would  be required  to  include  more detailed
 small-scale dispersion patterns, such as  those  around large
 buildings or near jet blasts.

     In calculation of long-term concentrations, the fact
 that there  is a distribution of meteorological  conditions is
 used to  simplify the  basic dispersion model.  The result,
 known as the Martin-Tikvart  model, approximates plume spread
 in the crosswind direction and  sums  the contributions of all
 combinations of wind  speeds  and atmospheric stabiltities.

    The  concentration at any receptor point is  obtained as
 the  sum  of  the contributions from  each point  source of
 emissions.   The accuracy of  the concentration value for this
 type of  model is dependent upon the  proximity of the
 receptor point and the emission sources.  Because the
 sources of  emission are  actually a collection of points,
 lines areas,  and volumes,  rather than merely a  collection of
 points, as  assumed in the  model, greater  accuracy generally
 results when the receptor  point is not close proximity to
 any sources.   To limit inaccuracies  attributable to the
 point source,  receptor locations within 100 meters of a
 point source were  not considered in  the results.

    The model  provided estimates of  air pollutant
concentrations  both from aircraft  alone and from all sources
 at a number  of  sites  located in and  around the  selected
airports.  Receptors  considered in this study were located
according to the  following overall scheme at air carrier
airports: (1)  one  receptor at the  center of each major
terminal, (2)  one  receptor 100 meters from the  head of each
runaway,  (3) sixteen receptors on  the airport boundary,
spaced equally  on  a compass rose located at the designated
center of the airport, and (4)  sixteen more receptors
located in the  airport surroundings,  5 kilometers from the
                                      92

-------
center of the airport and spaced equally on the compass
rose.  Not more than 50 receptors were used, the actual
number depending on the number of terminals and runways at
each airport.

The resulting concentrations at the various receptor points
were used in constructing isopleths of pollutant
concentration.  Isopleths were constructed for 6-9 a.m.
hydrocarbon and annual NOx concentrations due tc aircraft
alone, and for aircraft contributions to total CO
concentrations.

    The model input data used in calculating annual
concentrations of NOx were based on yearly distributions of
wind direction, stability class and wind speed class, and
annual average values of mixing height and emission rates.
The short-term meteorological and activity conditions used
to calculate the 8-hour and 1-hour CO conditions and the 6-9
a.m. hydrocarbon concentration were chosen to be
representative of conditions that would be expected to yield
high concentrations of these pollutants, i.e., low wind
speed, high atmospheric stability, and low mixing height,
and moderate to high aircraft activity.  The conditions for
calculation of short-term concentrations are presented in
Table B-l.

    Because the results of the model have not been
extensively validated or verified, the concentratidns
generated by the model should be considered to be very
approximate.  They are useful, however, in indicating
general pollutant concentration levels of the extent of
aircraft contributions to localized pollutant concentration.
                                      93

-------
                                      TABLE B-l

                  SHORT-TERM METEOROLOGICAL AND ACTIVITY CONDITIONS
                         6-9 A.M. HC
               8-Hour CO
                       at L.A. Airport   at L.A. Airport
                               LAX
                     1-Hour CO
                    ORD    JFK    DCA
Wind speed class
Stability class (Turner)
Wind direction, deg.
Wind variability, deg .
Mixing height, m.
Aircraft activity, 60
LTO cycles. 79
Direction of movement
1
C
255
20
200
(1970)
(1980)
West
1
E
255
20
200
260
West
1
E
90
40
535
54
E
1
F
215
30
700
49
SW
1
E
200
10
960
30
S
1
E
320
20
980
34
N
 Idle time at runway,
        sec.
60
Estimated annual
frequency of occurrence
of meteorological con-
itions                   at least
                           once
150
240
                                                                  260
540
                                                            81
                                       29*
                            10
300
                       67
a These conditions are used in estimating ratios between aircraft generated and total
8-hour CO concentrations; the ratios are not sensitive to the conditions assumed.
b  Based on 5 months of data.
                                                  94

-------
                        APPENDIX C:

AREA - SOURCE DISPERSION MODELING TO ESTIMATE

       DOWNWIND POLLUTANT CONCENTRATIONS
      The modeling method used  in  this analysis involved
  approximating emissions both  at  airports and in surrounding
  areas  as area sources, and relating these emissions to
  downwind pollutant concentrations by assuming Gaussian
  pollutant distribution in the vertical and crosswind
  directions.  For each receptor point, the concentration
  caused by small-area elements was determined by integrating
  in the crosswind and upwind directions over each source
  region.  The airport and surroundings were considered as
  separate source regions.  The concentrations due to these
  two source regions were calculated separately then added
  together to obtain the total  concentration at each receptor.
  Near the airport source, concentrations are the same as
  those  from an area source of  infinite extent.32  At greater
  distances, edge effects caused by the finite width of the
  airport are considered by including the integration in the
  cross-wind direction.  Also included is the limit to
  vertical mixing imposed by a  more stable layer aloft.

      For the purpose of this modeling, the airport was
  assumed to cover an area of 3.2  by 3.2 kilometers.  The time
  period for the analysis, 8 a.m.  to 11 a.m., was selected  on
  the basis of recurring meteorological conditions conducive
  to high air pollutant concentrations.  A diurnal correction
  factor was applied to the resulting concentrations to
  correct for the disproportionately greater amount of
  activity that occurred during this 3-hour period than
  occurred during other 3-hour  periods during the day.  The
  specific meteorological conditions used for the time period
  considered were: wind from west; stability class = 3, wind
  speed  = 1.5 in/second mixing height = 200 m.  These
  conditions are representative of severe conditions, from  an
  air pollution standpoint, that are expected to cccur at
  least  once a year in the Los  Angeles area.
                                       95

-------
                        REFERENCES
 1.  Nature and Control of Aircraft Engine  Exhaust Emissions.  Report
    of the Secretary of Health,  Education,  and Welfare  to  the United
    States Congress.  December 1968.

 2.  Jet Aircraft Emissions and Air Quality in  the Vicinity of the
    Los Angeles International Airport.   Air Pollution Control District,
    County of Los Angeles, California.   April  1971.

 3.  The Potential Impact of Aircraft  Emissions Upon Air Quality.
    Northern Research and Engineering Corporation.  Final  Report to
    the U. S. Environmental Protection Agency.   Research Triangle Park,
    North Carolina.  Contract Number  68-02-0085.  December 1971.

 4.  Assessment of Aircraft Emission Control Technology. Northern
    Research and Engineering Corporation.   Final Report to the U. S.
    Environmental Protection Agency.   Research Triangle Park, North
    Carolina.  Contract Number 68-04-0011.   September  1971.

 5.  Analysis of Aircraft Exhaust Emission  Measurements. Cornell
    Aeronautical Laboratory.  Available from NTIS--PB  204-879.  Contract
    Number 68-04-0040.  October 1971.

 6.  National Primary and Secondary Ambient Air Quality  Standards.
    Environmental Protection Agency.   Federal  Register  36(84):8187.
    April 30, 1971.

 7.  Air Quality Criteria for Hydrocarbons.  U. S. DHEW, PHS,  EHS,
    National Air Pollution Control Administration.  Publication Number
    AP-64.  Washington, D. C.  March  1970.

 8.  Federal Air Quality Control Regions.  Environmental Protection
    Agency, Office  of Air Programs, Research Triangle  Park, North
    Carolina.  Publication Number AP-102.   January  1972.

 9.  Requirements for Preparation, Adoption, and  Submittal  of  Implemen-
    tation Plans.   Environmental Protection Agency.  Federal  Register
    _36 (158): 15486,  August 14, 1971.

10.  Mixing Heights, wind Speeds, end  Potential for  Urban Air  Pollution
    Throughout the  Contiguous United  States.  Environmental Protection
    Agency, Office  of Air Programs, Research Triangle  Park, North
    Carolina.  Publication Number AP-101.  January  1972.

11.  Climatography of U. S., Summary of Observations for Los Angeles
    International Airport, 1951-1960.  U.  S. Department of Commerce,
    Weather  Bureau.  Washington, D. C.  1962.
                                        97

-------
12.  The State of California Implementation Plan for Achieving  and
     Maintaining the National Ambient Air Quality Standards.  California
     Air Resources Board.  Sacramento, California.   January 1972.

13.  A Mathematical Model for Relating Air Quality Measurements to  Air
     Quality Standards.  Environmental Protection Agency,  Office of Air
     Programs, Research Triangle Park, North Carolina.   Publication
     Number AP-89.  November 1971.

14.  Nature and Control of Aircraft Engine Exhaust Emissions.   Northern
     Research and Engineering Corporation.  Final Report to the National
     Air Pollution Control Administration.  Durham, North  Carolina.
     Contract Number CPA 222-68-27.  November 1968.

15.  A Study of Aircraft Gas Turbine Engine Exhaust Emissions.   Aerospace
     Industries Association.  Washington, D. C.   August  1971.

16.  Collection and Assessment of Aircraft Emissions Baseline Data  -
     Turbo-prop Engines.  Detroit Diesel Allison Division  (CMC). Avail-
     able from NTIS--PB 202-961.  Contract Number 68-04-0029.   September
     1971.

17.  Exhaust Emissions Test: AiResearch Aircraft Propulsion and Auxiliary
     Power Gas Turbine Engines.  AiResearch Division Garrett Corporation.
     Available from NTIS--PB 204-920.  Contract  Number  68-04-0022.
     September 1971.

18.  Assessment of Aircraft Emission Control Technology.  Northern
     Research and Engineering Corporation.  Available from NTIS--PB 204-878.
     Contract Number 68-04-0011.  September 1971.

19.  Collection and Assessment of Aircraft Emissions -  Piston Engines.
     Teledyne Continental Motors.  Available from NTIS--PB 204-196.
     Contract Number 68-04-0035.  October 1971.

20.  Analysis of Aircraft Exhaust Emission Measurements: Statistics.
     Cornell Aeronautical Laboratory.  Available from NTIS--PB  204-869.
     Contract Number 68-04-0040.  November 1971.

21.  A Study of Aircraft Powerplant Emissions (Piston and  Turbine).
     Scott Research Laboratories, Inc.  Available from  NTIS--PB 207-107.
     Contract Number 68-04-0037.  January 1971.

22.  Collection and Assessment of Aircraft Emissions Baseline Data  -
     Turbine Engines.  Pratt and Whitney Aircraft.   Available from  NTIS--
     PB 207-321.  Contract Number 68-04-0027. February 1972.
                                          98

-------
23.  A Field Survey of Emissions from Aircraft Turbine Engines.  U. S.
     Bureau of Mines, RI 7634.   Bartlesville Energy Research Center,
     Bartlesville,  Oklahoma.

24.  Gaseous Emissions from a Limited Sample of Military and Commercial
     Aircraft Turbine Engines.   Southwest Research Institute.  Available
     from NTIS--PB 204-177.  Interim Report, Contract Number EHS 70-108.

25.  A Study of Exhaust Emissions from Reciprocating Aircraft Power
     Plants.  Scott Research Laboratories.  Available from NTIS--PB 197-627.
     Contract Number CPA 22-69-129.  December 1970.

26.  Design Criteria for Control of Nitrogen Oxide Emissions from Air-
     craft Turbine Engines.  Ronald S. Fletcher, Richard D. Siegel, and
     E. Karl Bastress.  Northern Research and Engineering Corporation.
     Report Number 1162-1.

27.  Time Requirements for Retrofitting Jet Aircraft with Improved
     Combustor Design.  Northern Research and Engineering Corporation.
     Final Report to National Air Pollution Control Administration,
     Durham, North Carolina.  Contract Number CPA 22-69-90.  July 1969.

28.  Reduction of Nitrogen Oxides from Gas Turbines by Steam Injection.
     N. R. Dibelius, M. B. Hilt, and R. H. Johnson.  ASME Paper 71-67-58,
     American Society of Mechanical Engineers.

29.  A Study of Exhaust Emissions from Reciprocating Aircraft Power
     Plants.  Scott Research Laboratories, Inc.  Scott Project Number 1136.
     Final Report to the U. S.  Environmental Protection Agency.  Research
     Triangle Park, North Carolina.  Contract Number CPA 22-69-129.
     December 1970.

30.  Profile of Air Pollution Control. County of Los Angeles, Air Pollution
     Control District.  1971.

31.  Ambient Carbon Monoxide Exposures.  R. I. Larsen and H. W. Burke.
     APCA 69-167, Air Pollution Control Association.  June 1969.

32.  A Simple Method of Calculating Dispersion for Urban Areas.  Steven R.
     Hanna.  Journal of the Air Pollution Control Association, 2^1(12) : 774-
     777.  December 1971.
                                         99
oU.S. GOVERNMENT PRINTING OFFICE: 1973 514-151/133 1-3

-------