United States
                    Environmental Protection
                    Agency	
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
                    Research and Development
EPA/600/S2-89/054  Jan. 1990
4>EPA          Project Summary
                    Characterization  of
                    Emissions from  the Simulated
                    Open  Burning  of Scrap Tires
                    Jeffrey V. Ryan
                     Discarded automobile tires have
                   become a serious  health concern,
                   largely because the growing  number
                   of stockpile  fires has focused
                   attention on the potentially  harmful
                   products of incomplete combustion
                   (PICs)  emitted into the atmosphere
                   from burning scrap tires. This small-
                   scale   combustion  study was
                   designed to  collect, identify,  and
                   quantify products emitted during the
                   simulated open combustion of scrap
                   tires. Fixed  combustion gas, volatile
                   and semi-volatile organic, participate,
                   and  airborne  metals data were
                   collected under two burn conditions
                   that varied by the size of tire material.
                   Burn rates,  varied by material size,
                   were  used  to  estimate potential
                   emissions  of  identified products.
                   Total estimated emissions of semi-
                   volatile organics ranged from 10 to 50
                   g/kg  of tire  material burned. Mono
                   and poly aromatic hydrocarbons were
                   the  main   emission  products
                   identified. Benzo(a)pyrene (BAP) In
                   participate extracts is  of particular
                   concern because it  is  a  known
                   carcinogen. The presence of zinc in
                   gaseous particulate collection  was
                   also  verified and quantified.  Several
                   trends  were  evaluated relating
                   emission products with  burn rates.
                     This  Project Summary was
                   developed by EPA's  Air and Energy
                   Engineering  Research Laboratory,
                   Research  Triangle Park,  NC, to
                   announce key findings of the research
                   project that is fully documented  in a
                   separate report of the same title  (see
                   Project Report ordering information at
                   back).
Introduction
  Approximately 240 million vehicle tires
are  discarded annually. Although viable
methods for reclamation exist, less than
25% are re-used or  re-processed. The
remaining 170 million scrap tires  are
discarded  in landfills,  above-ground
stockpiles, or illegal dumps.
  Many landfills are  refusing  to accept
tires because they  present  not  only
disposal but also health-related problems.
After burial, tires often float to the surface
and become  partially filled with water.
Cutting the tire in half or in pieces can
reduce this tendency. It is very costly to
cut or shred tires into a condition suitable
for landfill; in any event, many sites lack
the  necessary equipment.  Steel-belted
radials which comprise the majority of the
nation's discarded  tires,  are particularly
difficult to cut and/or shred. Often, they
are simply stockpiled or illegally dumped.
These stockpiles and dumps can become
a breeding ground for  many insects,
especially mosquitos,  where  water
collects in the tires and creates an ideal
breeding habitat. The introduction and
spread of several mosquito species has
been directly  attributed to the presence
of refuse tires.
  The growing incidence  of tire  fires
creates another potential health hazard.
More tire stockpiles  and illegal dumps
are coming into existence, and with them
the  occurrence of tire fires. These fires,
often started by arson, generate a huge
amount of  heat making them  extremely
difficult to extinguish.  Some of these tire
fires have continued for months.  For
example, the Rhinehart  tire  fire  in
Winchester, Virginia, burned for nearly 9

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months,  potentially  exuding large
quantities of harmful compounds.
  The EPA's  Control  Technology Center
(CTC) received numerous requests  from
state and  local agencies nationwide for
information pertaining to tire fires and
their  effects. Because  very  little
information on the open burning  of scrap
tires  was available,  the  steering
committee felt a study investigating this
potential problem was warranted. Guided
by  the  Combustion   Research  Branch
(CRB)  of EPA's Air  and   Energy
Engineering  Research   Laboratory
(AEERL),  Acurex  conducted  a study
which identified and  quantified  organic
and inorganic emission products
produced  during the simulated  open
combustion of scrap tires.
Experimental Approach
  The project consisted  of a parametric
study to collect organic  and inorganic
emissions  from  the simulated  open
combustion  of  scrap  tires.  Small
quantities (10-20 Ib, 4.5-9.0 kg) of scrap-
tire  material  were  burned under two
controlled conditions  determined by the
size of the material. The conditions were
evaluated  in  duplicate  on successive
days. An  existing burn  hut used  for
similar projects was  modified  to
accommodate  this  task. A separate
outbuilding housed the required organic
and particulate  sampling  equipment.
CRB's  Hazardous Air Pollutants  Mobile
Laboratory (HAPML) was used to monitor
fixed combustion  gases.  Organics were
collected using the  Volatile  Organic
Sampling  Train (VOST) and  a semi-
volatile collection  system using XAD-2
and particulate  filters. Particulate  was
also collected to assess airborne metals.
The organic  constituents  were  analyzed
both qualitatively  and quantitatively by
GC/MS, GC/FID, HPLC, and  gravimetric
methodologies.
  Representative scrap  truck  and
passenger  car  bias ply  tires  were
obtained from local tire dealers. Bias ply
tires were  chosen  due  to  difficulties
encountered  attempting to  cut  steel
belted radial tires.  The tires were cut into
two sizes in  order to vary initial surface
area and therefore combustion rate. The
"CHUNK"  condition  represented a
quarter to a sixth  of an entire tire, while
tire material cut  into 5.08 cm (2  in.)
squares  represented the  "SHRED"
condition. Tire material approximating the
equivalent weight  of  two  passenger  car
tires (30 Ibs,  13.6 kg) was placed  in a
small burn pit and  combusted. A platform
scale under the burn pit monitored  the
weight of tire material combusted. An air
system designed to deliver  nominally
1,200  cfm  (34.0 ms/min) was used  to
simulate rapid dilution and  cooling  of
combustion products.
  An  insulated  duct transported the
gaseous sample to an adjacent sampling
shed for collection of volatile  and  semi-
volatile organics,  particulate,  and  fixed
combustion gases. Common combustion
gases,  02,  CO,  C02, S02,  and total
hydrocarbons (THC)  were  monitored
continuously throughout the burn period.
Volatile organics were collected using the
Volatile Organic Sampling Train (VOST).
Semi-volatile organics and  particulate
were collected using applicable modified
sampling systems. During the sampling,
tire material weight differentials  were
recorded to determine burn rates.
  The  VOST  samples collected  were
analyzed by  gas chromatography/mass
spectrometry (GC/MS). Compounds were
identified  through  spectral  library
searches and  matching, along  with
investigator interpretation. The  identified
compounds  were quantitated  using the
system response to  toluene.  Individual
compound  responses were   not
determined.  Semi-volatile  organics were
collected on  both  particulate  filters as
well as  the XAD-2  organic sorbent
material. The  organics were  retrieved
from the collection media by soxhlet
extraction with dichloromethane. Both the
particulate  extracts and the XAD-2
extracts  were  analyzed  for  total
chromatographable organics (TCO) and
GRAV—organic compounds with boiling
points  of 100-300°C,  and  > 300°C,
respectively. The XAD-2  extracts  were
analyzed  by   GC/MS  to   identify
compounds  found in  the TCO range.
Again,  compounds  were identified  using
library  spectral matching and investigator
interpretation. Identified compounds were
quantitated  using  the  same  response
used  for TCO quantitation.   Individual
identified compound responses were not
determined.  The organic  extracts  were
also analyzed for polycyclic  aromatic
hydrocarbons  (PAHs).  Separately
collected particulate matter  was  also
quantitated  for specific  metals common
in tire ash residues.
Data and Results
  The size of tire  material was varied to
change combustion conditions and  gain
insight into the mechanisms governing
burn rate. Burn rates were calculated by
dividing the  amount  of tire material
burned over a given period by that  time
in minutes and normalizing to a mass per
hour  basis. A higher burn  rate  was
observed during CHUNK tests  than  in
SHRED  tests.  Roughly  double the
amount of  tire  material was  combusted
during the  same  time. In  both burn
conditions,  an  initial high  burn rate was
observed and led to a gradual leveling off
until the burn rate was steady.
  Combustion  gases  were  monitored
continuously throughout the  test. High
emissions of CO,  S02,  and  THC were
observed at high burn rates.
  The  identification of  unknown volatile
organics  using the MS proved to be
highly  successful.  More  than  50
compounds were  identified  from the
VOST  samples collected.  Most of these
compounds  are aliphatically, olefinically
or acetylenically substituted  aromatics.
Cyclic  and  chained alkanes, alkenes and
dienes were also identified.  Several
sulfonated and  nitrogenated compounds
were   also identified in  samples.
Thiophene, substituted  thiophenes,
isocyanobenzene and benzodiazine were
isolated in  multiple samples.  Following
quantitation of identified  compounds,
average  gaseous concentration  and
emissions were estimated.Of  particular
interest are  the emission rate estimations.
The estimated emissions  are  based on
several variables and were obtained by
relating the amount  of  tire  material
combusted  during  the  sampling  period
with the average gaseous concentration.
It was assumed that the dilution air added
to the burn hut was constant.
  It is difficult to isolate consistent trends
in the  types and  amounts of  specific
volatile organic  compounds  formed
during  the  combustion of  scrap tires
under varied burn  rates. A trend  appears
that, as burn rate decreases, the amount
of organics potentially emitted tends to
increase with respect to the  amount of
tire material combusted.
  As with the  volatile  organic analyses,
the MS analysis of the XAD-2  extracts
identified  the same types of compounds.
Table 1 lists the 60 compounds identified
and indicates that substituted mono and
poly aromatics were  the  predominant
products of  incomplete  combustion.
Table  2 presents the  average gaseous
concentration and estimated emissions of
the quantitated  identified compounds
from  the four test conditions.  The
estimated emissions of many compounds
increase with decreased burn  rate. Table
3 summarizes  the semi-volatile  organic
emission  data from  the  four test
conditions.  The  total organics  from
respective boiling-point-based analyses
are presented for each component of the
sampling  media. The  estimated emis-

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Table 1. Compounds Identified by GC/MS from XAD-2 Extracts
    Compound Identified
                               Formula
     Compound Identified
Formula
      Compound Identified
Formula
Methyl Benzene
Cyclopentanone
Dimethyl Cyclohexene
Ethenyl Cyclohexene
Ethyl Benzene
Dimethyl Benzene
Hexanenitrile
Ethynyl Benzene
Styrene
Nonane
Propenyl Cyclohexane
Methylethyl Benzene
Propyl Benzene
Benzaldehyde
Trimethyl Benzene
Phenol
Cyanobenzene
Propenyl Benzene
Methyl, Ethenyl Benzene
Methyl, Methylethyl Benzene
                                C7H8



                                CgH12
                                £-8^70
                                CgHg

                                CgH20
                                CgH,2
                                C7H60

                                CgH72

                                C6H60

                                C7H5N
Limonene
Dihydro Indene
Hydroxy Benzaldehyde
Indene
Tetramethyl Benzene
Ethyl, Dimethyl Benzene
Methyl Phenol
Methyl Benzaldehyde
Methyl, (Methylethyl) Benzene
Propenyl, Methyl Benzene
Undecane
(Dimethylpropyl) Benzene
Dimethyl, (Methylethyl) Benzene
Butynyl Benzene
Methyl Indene
Azulene
Naphthalene
Benzo[b]th!ophene
Benzisothiazole
Hexahydro Azepinone
C7H602

CgHg
                                                                       C7H80
                                                                       CgHaO
                                                                       C,jH24
                                                                       CgHgS

                                                                       C7H5NS

                                                                       CgH^NO
Dihydro, Methyl Naphthalene
Butyl,Trimethyl Benzene
Methyl Naphthalene
Biphenyl
Dimethyl Naphthalene
Dihdro Acenaphthalene
Acenaphthalene
(Dimethyl, Hexenyl), Methyl Benzene
Pentadecane
1,1' Biphenyl,Methyl
Isocyano Naphthalene
Naphthalenecarboxaldehyde
Propenyl Naphthalene
Trimethyl Naphthalene
1H Fluorene
Dimethyl Biphenyl
Dibenzothiophene
Phenanthrene
9H Fluorene, Methylene
Phenylnaphthalene
                                         C12H12

                                         C12H10

                                         C12Hg
                                         C13H12
                                         C,,H7/V
                                         C,,H80
                                         C12H10S

                                         C14H-,Q

                                         C 14^10
sions data  presented show that 12-50 g
of semi-volatile organics can  be emitted
for every kilogram of tire burned. A trend
does  seem evident when relating  the
amount of organics emitted to burn rates.
It appears  that, as burn rate  decreases,
the  amount  of  organics   emitted,
particularly  in the TCO range,  increases.
There did not seem to be  any significant
variation  in  GRAV  range  organic
emissions when related to burn rate. A
PAH analysis was performed on the XAD-
2  and particulate  filter extractions. Of
particular importance is the presence of
benzo(a)pyrene (BAP)  in  all  particulate
portions.  BAP  is  a reported  carcinogen
and a highly scrutinized compound when
evaluating combustion processes.
  A  separate  particulate   collection
system was operated to  verify  and
quantitate  the  presence  of  metals
collected from  ambient emissions.  The
results of the analyses  were marginal for
many of the targeted metals. Many of the
results were  at  or  near  instrument
detection levels. It did seem evident that
lead and particularly zinc  were found to
be collected from gaseous  emissions.


Conclusions
  The  primary goal of this  project was to
characterize  potentially  harmful
emissions  from  the  simulated  open
                                         burning of scrap tires. The simulation was
                                         necessarily  crude,  because it woujd  be
                                         extremely difficult to match the burning of
                                         the equivalent of two tires with a 6 million
                                         tire, full-scale, stockpile fire.  Neverthe-
                                         less,  the  study  allowed the  investigators
                                         to  identify  and  measure  gaseous
                                         emissions  and directly  relate  this
                                         information to a  mass burn rate. This task
                                         was  accomplished  by  accurately
                                         measuring  dilution  volumes,  sample
                                         volumes,  and weights of tire material
                                         combusted.
                                           It is not known how well the concentra-
                                         tions obtained from this study represent
                                         those at an actual tire fire. The dilution air
                                         added to  the burn hut was used not only
                                         to control known volumes introduced,  but
                                         also to simulate ambient condition's.The
                                         same types  of compounds  identified
                                         during  this  study  are probably  emitted
                                         during  an actual fire, but  whether  the
                                         average  gaseous  concentrations and
                                         estimated emissions  are comparable is
                                         uncertain. A comparison with limited data
                                         collected  at the  Winchester, Virginia,  fire
                                         by NIOSH,  indicates  that reasonable
                                         agreement  exists  within  several
                                         measurement areas.  Many  of the  same
                                         compounds  were  identified  in  actual
                                         plume samples.  Particularly  good
                                         agreement  exists  in  PAH   plume
                                         measurements.  NIOSH reported  ambient
                                         concentrations of total PAHs  are gener-
                                          ally within the same order of magnitude
                                          as  average gaseous  concentrations
                                          obtained during testing. Measurements of
                                          CO  and metals also indicate similar
                                          agreement.  Both  the  lead  and  zinc
                                          measurements  show similar values both
                                          in  concentration  and   relative
                                          concentration between the two metals.  It
                                          may be reasonable to assume  that the
                                          estimates obtained during this study may
                                          be  within  an  order of  magnitude  of
                                          emissions realized from actual stock-pile
                                          fires.

                                            The results of this study pose a variety
                                          of  pertinent  topics and  questions
                                          regarding tire fires. How far does the
                                          particulate  from a  stockpile  fire carry?
                                          Are  evacuation  procedures  for
                                          populations  near  stockpile  fires
                                          sufficient? Is it good policy to continue to
                                          let  tire  fires burn themselves out?  A
                                          greater  potential  for  harmful  organic
                                          emissions seems to exist at lower burn
                                          rates; thus  a smoldering tire fire may be
                                          more harmful than one that is burning out
                                          of control. The  identification of significant
                                          quantities   of  benzo(a)pyrene  in  the
                                          particulate  extracts warrants  serious
                                          concern. High emissions of other noxious
                                          compounds, particularly  benzene, with
                                          concentrations  often exceeding  1  ppm,
                                          suggest that uncontrolled  scrap  tire
                                          combustion poses significant health risks.

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Table 2, Quantitation and Emission Summary of Compounds Identified in
Day 1 CHUNK Condition
Vol Samp = 12,98 m3
Burn Rate =2.3 kg/h
Compound Identified
Methyl Benzene
Ethyl Benzene
Dimethyl Benzene
Ethynyl Benzene
Styrene
Methylethyl Benzene
Propyl Benzene
Benzatdehyde
Trimethyl Benzene
Phenol
Cyanobenzene
Trimethyl Benzene
Methyl, Methylethyl Benzene
Limonene
Indene
Tetramethyl Benzene
Ethyl, Dimethyl Benzene
Methyl Benzatdehyde
Ethyl, DimeVtyl Benzene
Propenyl, Methyl Benzene
Methyl Indene
Methyl Indene
Naphthalene
Benzo[B]thiophene
Benzisothiazole
Hexahydro Azepinone
2-Methyl Naphthalene
1 -Methyl Naphthalene
Biphenyl
Dimethyl Naphthalene
Acenaphthalene
1,1' Biphenyl, Methyl
Isocyano Naphthalene
Propenyl Naphthalene
Trimethyl Naphthalene
1H Fluorene
Phenanthrene
Totals
Average
Gaseous
Concentra-
tion (mg/m3)
0,716
0.074
0.000
0,185
0.419
0,000
0.000
0.111
0.000
0.190
0.095
0.127
0.000
0.000
0.325
0.000
0,000
0,000
0.000
0.000
0.000
0.000
1,230
0.099
0.000
0.000
0.164
0.124
0.083
0.000
0.390
0.025
0.021
0.053
0,000
0.087
0,152
4,670
Estimated
Emissions
(mg/kg TIRE)
634.8
65.8
0.0
163.6
371.5
0,0
0.0
98.6
0.0
168.3
84.3
112.8
0.0
0.0
288.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1,090.4
87.6
0.0
0.0
145.6
109.9
73.5
0.0
345.6
22,1
18.7
46.6
0.0
76,9
135.0
4,140.4
XAD-2 Extracts' •*
Day 2 CHUNK Condition
Vcrf Samp = 12.76 mg/m3
Burn Rate = 1.7 kg/h
Average
Gaseous
Concentra-
tion (mg/m3)
1.500
0.289
0.513
0.325
0.795
0.081
0.000
0.327
0.000
0.473
0.305
0.256
0.215
0.094
0.602
0.000
0,000
0,000
0.000
0.000
0.188
0.000
1.931
0,000
0.000
0.126
0.466
0.463
0.290
0.069
0.773
0.000
0.000
0.000
0.000
0.288
0.194
12,672.8
Estimated
Emissions
(mg/kg TIRE)
1,799.5
347.1
615.3
390.0
953.3
97.4
0.0
392.1
0.0
566.9
365.5
307.6
258.1
113.2
722.0
0.0
0.0
0.0
0.0
0.0
225.6
0.0
2,315.9
0.0
0.0
151.4
559.4
555.3
347.8
83.0
927.0
0.0
00
0.0
0.0
346.0
233.2
9.367
Day 1 SHRED Condition
Vol Samp = 13.77 mg/m3
Burn Rate = 1.1 kg/h
Average
Gaseous
Concentra-
tion (mg/m3)
0.731
0.192
0.554
0.078
0.332
0.142
0.136
0.343
0.156
0.360
0.307
0.195
0.926
1.402
0.156
0.094
0.000
0,089
0.162
0.537
0.223
0.000
0.516
0.000
0.179
0.345
0.202
0.122
0.180
0.183
0.217
0.000
0.000
0.000
0.169
0,141
0.000
17,362.2
Estimated
Emissions
(mg/kg TIRE)
1,354.9
355.0
1,026.1
144.2
614.6
263.5
251.2
635.3
289.9
667.2
569,3
361.5
1,716.1
2,599.2
289.9
174.8
0.0
164.7
300.0
996,2
413.7
0.0
957.2
0.0
330.9
638.9
373.9
225.7
333.6
338.8
402.2
0.0
0.0
0.0
312.9
260.8
0.0
9.633
Day 2 SHRED Condition
Vol Samp = 12.43 mg/m3
Burn Rate = 1.3 kg/h
Average
Gaseous
Concentra-
tion (mg/m3)
0.911
0.203
0.532
0.150
0.433
0.122
0.118
0.000
0.351
0.470
0.292
0.199
0.704
1.316
0.251
0.000
0.154
0.000
0.000
0.000
0.114
0.132
0.843
0.000
0.000
0.555
0.313
0.146
0.208
0.000
0.430
0.000
0.000
0.000
0.203
0.230
0.251
15,108.7
Estimated
Emissions
(mg/kg TIRE)
1,429,0
318.3
834.2
235,2
679.8
191.0
184.6
0.0
549.9
736.8
458.6
312.2
1,104.9
2,064.5
393.9
0.0
241,8
0.0
0.0
0.0
179.2
207,3
1,322.8
0.0
0,0
869.9
490.5
229,7
326.3
0.0
673,8
0.0
0.0
0.0
319.1
361.2
394.2
10,566
1 Concentrations determined using system response to TCO calibration mix.
2 Average gaseous concentrations and estimated emissions are based on controlled dilution of pit emissions. It is not known how well this dilution
 represents ambient air exchange under actual conditions.

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Table 3. Organic Emission Summary
Average Gaseous
Concentration
Sample Portion
Sample
Time (min)
Weight
Change (kg)
Avg
Rate
Bum
(kglh)
Volume
Samp (m3)
TCO
(mg/m3)
GRAV
(mglm3)
Estimated Emissions
TCO
(mglkg
GRAV
TIRE)
 XAD-2
 Filter 1
 Filter 2
 Filter Total
 KAD-2
 Filter 1
 Filter 2
 Filter Total
 XAO-2
 Filter
140
 11
129
140
152
 42
110
152
182
182
5.4
1.7
3.7
5.4
4.3
2.4
1.8
4.3
3.2
3.2
2,3
9,4
1.7
2.3
1.7
3.5
1.0
1.7
1.1
1,1
                                                    Day 1 CHUNK Condition
12.98
 0.93
12.05
12.98
6.067
0.043
0.066
0.065
                                                    Day 2 CHUNK Condition
12.78
  3.3
 9.45
12.76
11.398
 0,018
 0.53
 0.398
                                                    Day 1 SHRED Condition
13.77
13.77
20.658
 0.141
                                                    Day 2 SHRED Condition
 0.698
33.634
 •J.S23
 6,888

 Total
 0,749
18.498
10.219
12.359

 Total
  0.89
  6.822

 Total
 5,379
     9
   79
   58

 5,436
13,671
    11
 1,081
   477

14,148
38,292
  261

38,554
   619
 7,298
 5,785
 6,106

 6,725
   898
10,776
20,837
14,824

15,722
 1,SSO
12,646

14,295
                                                                                                                  12,161
                                                                                                                 25,870
                                                                                                                 52,849
XAD-2
Filter

183
183

4.0
4.0

1.3
1.3

12.43
12.43

15.65
0,173

1,099
8.77?
Total
24,546
271
24,819
1,724
13,757
15,481

40,299
  Results  from  the  airborne metals
portion of the study  were inconclusive.
Maximum values were presented,  often
based on detection levels. Emissions of
lead and zinc  may  reach  significant
quantities. Reported chemical analysis of
tire  ash  residues  reveals that  zinc
comprises nearly 50 percent of the total
residue.  Evidently,  the  other metals
known to be contained in  tires  remain in
the ash residue. Although no attempt was
made to  analyze ash  residue, significant
quantities of metals  present in the ash
could potentially  be  leached  out into
groundwater systems, posing another
major problem.
  The  values  obtained by the on-line
analyzers for  normal  combustion  gases
                       showed that as burn rate increased, the
                       amount of CO,  SO2,  and  unburned
                       hydrocarbons also increased. High  burn
                       rate conditions were  not fully evaluated,
                       so greater quantities of  these gases,
                       particularly SOg, may be emitted during a
                       stockpile  fire. Tires contain a significant
                       amount of sulfur, so high  emissions of
                       SOa, while likely only a minor contributor
                       to  the  acid  rain  problem, could  have
                            significant local consequences.
                         This study was designed to identify the
                       potential chemical hazards from tire  fires
                       on a small-scale, simulation basis.  The
                       study  reveals  the  potential  for   the
                       emission  of  great amounts of  organic
                       compounds, primarily aromatics, some of
                       which  may  be  extremely  harmful.
                                                     Although  the estimates  of average
                                                     gaseous concentrations and emissions
                                                     are crude, the trends presented for burn
                                                     rate may be  helpful in  directing  further
                                                     research  and  control efforts. That  the
                                                     "SHRED"  condition resulted in a lower
                                                     burn rate indicates that the gaps between
                                                     the tire material provide the major avenue
                                                     of oxygen transport. Oxygen transport
                                                     appears to be a  major if not the con-
                                                     trolling  mechanism  for  sustaining  the
                                                     combustion process. This fact could have
                                                     advantageous implications for   those
                                                     attempting to combat tire fires. It may be
                                                     possible to fill the  gaps between  tires
                                                     with a foam  inhibitor,  potentially  suffo-
                                                     cating the fire from within.

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 J. V. Ryan is with Acurex Corp., Research Triangle Park, NC 27709.
 Paul lit Lemieux is the EPA Project Officer (see below).
The complete report, entitled "Characterization  of Emissions from the Simulated
 Open  Burning of Scrap Tires," (Order No. PB 90-126  0041 AS; Cost: $17.00,
 subject to change) will be available only from:
       National Technical Information Service
       5285 Port Royal Road
       Springfield, VA 22161
       Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
       Air and Energy Engineering Research Laboratory
       U.S. Environmental Protection Agency
       Research Triangle Park, NC 27711
United States                   Center for Environmental Research
Environmental Protection         Information
Agency                         Cincinnati OH 45268
Official Business
Penalty for Private Use $300

EPA/600/S2-89/054

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