ENVIRONMENTAL HEALTH SERIES
Air Pollution
SOURCES
POLYNUCLEAR HYDROCAR
IN THE ATMOSPHERE
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
-------
SOURCES OF POLYNUCLEAR HYDROCARBONS
IN THE ATMOSPHERE
R. P. Hangebrauck
D. J. von Lehmden
J. E. Meeker
Control Technology Research and Development
National Center for Air Pollution Control
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Bureau of Disease Prevention and Environmental Control
Cincinnati, Ohio
1967
-------
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Public Health Service Publication No. 999-AP-33
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CONTENTS
Page
Abstract v
Introduction 1
Sources Surveyed 2
Polynuclear Hydrocarbon Compounds Determined 2
Sample Collection and Analytical Techniques 3
Heat-Generation Processes 5
Refuse Burning 14
Industrial Processes: Direct Sampling 18
Industrial Processes: Atmospheric Sampling 28
Motor Vehicles 33
Summary and Conclusions 37
References 41
111
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ABSTRACT
Rates of emissions of polynuclear hydrocarbons were measured at
several sources considered likely to produce such emissions. The
sources included heat generation by combustion of coal, oil, and gas;
refuse burning; industrial processes; and motor vehicles. The annual
emissions of benzo(a)pyrene in the United States were estimated for each
of the sources surveyed, to provide a rough gauge of the importance of
each source. Small, inefficient residential coal-fired furnaces appear
to be a prime source of polynuclear hydrocarbons; other sources may
be of local importance. Production of polynuclear hydrocarbons was
generally associated with conditions of incomplete combustion.
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INTRODUCTION
Concern with the health effects of carcinogenic substances dates
back at least to 1775, as reflected by the writings of Pott. 1 It was
discerned that among persons employed as chimney sweeps in Europe
the rate of skin cancer was higher than that of the general population.
Since that time, considerable progress has been made in isolating and
identifying individual compounds from many suspected cancer-causative
agents such as soot and coal tar. The isolation of benzo(a)pyrene
(3, 4-benzpyrene) from coal tar in 1933 2 has particular significance.
Although this compound has not been definitely identified as the etiolog-
ical agent responsible for many of the so-called industrial cancers,
laboratory experiments with animals have shown that it is one of the
more biologically active organic compounds in the group termed "poly-
nuclear hydrocarbons." The carcinogenic effects of benzo(a)pyrene on
animals are well documented in the published literature. 3-5 xhe bio-
logical activities of the other polynuclear hydrocarbons discussed have
been reported. Some of these compounds are weakly carcinogenic;
some are not carcinogenic; some may inhibit or accelerate the activity
of benzo(a)pyrene. 3, 6
Surveys by the Public Health Service
In the late 1950's, the U.'S. Public Health Service, Division of Air
Pollution, surveyed concentrations of polynuclear hydrocarbons in the
atmosphere of 103 urban and 28 nonurban areas of the United States.?- 8
The air in all of the 103 urban areas contained benzo(a)pyrene. Concen-
trations ranged from 0.11 to 61 micrograms per 1000 cubic meters of
air, with a geometric mean concentration of 6. 6. Concentrations in
nonurban areas were much lower, ranging from 0. 01 to 1. 9 micrograms
per 1000 cubic meters, with a geometric mean concentration of 0.4.
The relatively large quantities found in the air of urban areas are log-
ically attributed to the higher density of domestic, commercial, and
industrial activities.
A very limited amount of published data is available, either on
concentrations of polynuclear hydrocarbons in effluent streams from
specific air pollution sources or on the atmospheric concentrations to
be expected in the vicinity of such sources. Because of the need for
information of this type, the U.S. Public Health Service inaugurated a
program in 1960 to survey selected processes to evaluate emissions of
polynuclear hydrocarbons. The main purpose of the survey was to
"screen" processes likely to produce emissions of polynuclear hydro-
carbons and thereby to indicate the probable origin of the polynuclear
compounds contained in urban air. Individual studies, comprising por-
tions of the over-all survey, have been reported for heat-generation
and incineration processes, 9-12 industrial processes, 13 and motor
vehicles. 14 This report compiles and summarizes the entire survey
and presents some previously unpublished data on residential furnaces
and petroleum catalytic-cracking catalyst regenerators.
1
-------
Significance of the Data
A review of the published literature indicates that no definite
atmospheric concentrations of polynuclear hydrocarbons constituting
hazards to human health have been established. Therefore, no attempt
is made herein to interpret the hygienic significance of the polynuclear
hydrocarbon concentrations. The results are presented simply to indi-
cate the relative importance of the processes studied as contributors
of polynuclear hydrocarbons to the atmosphere.
SOURCES SURVEYED
The processes to be surveyed were selected from a list of prob-
able potential sources of polynuclear hydrocarbon emissions. The
categories of the sources tested are listed in Table 1.
Table 1. SOURCES SURVEYED FOR EMISSIONS OF POLYNUCLEAR HYDROCARBONS
Heat generation: coal, oil, and gas
Refuse burning: municipal and commercial incineration; open burning
Miscellaneous industrial processes:
Petroleum catalytic cracking — catalyst regeneration: FCC, TCC (air lift), TCC (bucket
elevator), and Houdriflow
Asphalt air blowing
Asphalt hot-road-mix manufacture
Carbon-black manufacture
Steel and coke manufacture
Chemicals manufacture
Motor vehicle exhaust (gasoline): automobile; trucks
POLYNUCLEAR HYDROCARBON
COMPOUNDS DETERMINED
The individual polynuclear hydrocarbons that were quantitatively
analyzed are classified in Table 2 in two groups corresponding to the
relative reliability of the analytical determinations. Because of inter-
ferences that occur during chemical analyses, values for the compounds
in Group 2 are of lower quantitative reliability than those for Group 1.
2 POLYNUCLEAR HYDROCARBONS
-------
Table 2. PROPERTIES OF POLYNUCLEAR HYDROCARBONS3
Compound
Q.
D
O
0
CN
Q.
D
O
1_
Pyrene (C,6H10)
Benzo(a)pyrene (^-20^12^
Benzo(e)pyrene (^-20^12^
Perylene (020^12^
Benzo(ghi)perylene (C22H]2)
Anthanthrene (C22H]2)
Coronene (^24^12^
Anthracene (CI^H-IQ)
Phenanthrene (C]4H]0)
Fluoranthene (Ci^HiQ)
Abbreviation
P
BaP
BeP
Per
B(ghi)P
Anth
Cor
A
Phen
Fluor
Melting
point, °C
150
178
178
275
273
257
435
217
101
110
Biological
activity0
--
•H+
+
not reported
not reported
not reported
°Relative activity on mouse epidermis:
+H- active, + weak, - - inactive
SAMPLE COLLECTION
AND ANALYTICAL TECHNIQUES
Data were collected in three ways: by direct sampling of station-
ary sources, by atmospheric sampling near stationary sources for which
direct sampling was not practical, and by sampling of exhaust from motor
vehicles. The principal items of special equipment were the sample
collection trains illustrated in Figures 1 and 2. These sampling trains,
designed to minimize loss of condensed polynuclear hydrocarbons from
volatilization, have been described in previous publications. 9, 13-15
Stationary Source Testing
In testing of stationary sources (Figure 1) the sample gas stream
passes through a series of water bubblers kept at 32°F and then through
a series of freeze-out traps immersed in a dry-ice alcohol bath, from
which it exits at 0°F. Finally, the sample gas stream passes through a
high-efficiency glass-fiber filter. Isokinetic sampling rates ranged
from 2. 1 to 6. 0 standard cubic feet per minute (70°F, 1 atm), and all
sources were sampled continuously over periods ranging from 80 min-
utes to 3 hours.
Sampling and Analysis
-------
U - TUBES IN DRY-ICE _
-ALCOHOL BATH MANOMETER
BUBBLERS IN
ICE - WATER BATH
Figure 1 Polynuclear hydrocarbon sample train for stationary source testing.
UPPER GRID-
ALUMINUM SCREEN-
THERMISTER TEMPERATURE PROBE
TAILPIPE
CONNECTION
ICE-WATER
BATH
CONDENSATE RESERVOIR
Figure 2. Polynuclear hydrocarbon sample train for motor vehicle testing.
Atmospheric Testing
Some installations were not amenable to direct source testing
(e.g. , slot-type coke ovens). In addition, some processes are so com-
plex that proper evaluation of emissions of polynuclear hydrocarbons
would require the sampling of many related installations (e.g. , chem-
ical manufacture). In this survey, such processes were evaluated
indirectly by collection of atmospheric samples in urban residential
areas near the installations.
Atmopsheric samples were collected with high-volume air
samplers. 16 Usually, air samplers were operated simultaneously at
POLYNUCLEAR HYDROCARBONS
-------
three to five urban residential sites near each installation. All
samplers were located at least 15 feet above ground level to minimize
the possibility of sampling dust-laden air. Samplers were operated for
periods of 1 to 3 days at flow rates ranging from 20 to 65 cubic feet per
minute. Tests were conducted over an interval of 2 weeks.
Motor Vehicle Testing
Figure 2 is a diagram of the apparatus used in sampling exhausts
from automobiles and trucks. Total exhaust is piped into an ice-chest
condenser and then through a filter. Sample volumes ranged from 675
to 1120 standard cubic feet (70°F, 1 atm) of dry exhaust. Maximum
instantaneous temperature at the filter ranged from 37° to 80°F for
automobiles and from 40° to 60°F for trucks.
Analysis
All of the samples were analyzed by the same technique, which
involved benzene extraction of the particulate matter, the condensate,
and the rinse liquids. The benzene-soluble fraction of the samples
was separated by column chromatography, and the analyses made by
ultraviolet-visible spectrophotometry. 1'. 18
The analytical scheme is believed to be accurate to within ± 20
percent for benzo(a)pyrene, not including possible variations attribut-
able to sample collection and extraction. This degree of variation is
consistent with the complexity of the analysis and the small amounts of
material present in samples containing many similar compounds.
HEAT-GENERATION PROCESSES
Combustion units that burn conventional fuels were designated as
heat-gene ration processes. Design and operation data for these units
are given in Tables 3, 4, and 5. Data on emissions are summarized
in Tables 6, 7, and 8. 9-12
Coal-Burning Units
The largest units tested were coal-fired boilers with rated capaci-
ties ranging from 1, 300, 000 down to 70, 500 pounds of steam per hour
(Tables 3 and 4). The larger boilers in this range incorporated pulver-
ized and cyclone firing and were used to generate electric power. The
smaller boilers in this size range supplied steam for industrial process
heating and electric power generation. Firing was accomplished with
pulverized coal, chain grates, or spreader stokers. Smaller coal-
burning units tested were rated by Btu input. Units in this group sup-
plied steam for smaller industrial-process heating systems as well as
Heat-Generation Processes
-------
Table 3. DESIGN AND OPERATIONAL SUMMARY: HEAT GENERATION SOURCES (COAL-FIRED POWER PLANTS)
Sample
No.
ISS-22
24, 25
27
28, 29
30, 31
42
44
61 +62
63
64
65
69
70
71
72
73
Test condition
100% load
100% load
100% load
75% load
75% load
(slightly higher excess air)
100% load
100% load
100% load
100% load
(with fly-ash reinjection)
100% load
(without fly-ash reinjection)
100% load
(with fly-ash reinjection)
100% load
100% load
75% load (normal)
75% load (normal)
75% load (normal)
(slightly higher excess air)
Design data
Type of unit
Pulverized coal
(vertically-fired,
dry-bottom furnace)
Pulverized coal
(front-wall-fired,
dry-bottom furnace)
Pulverized coal
(tangent i ally -fired,
dry-bottom furnace)
Pulverized coal
(opposed-, downward-
inclined burners;
wet-bottom furnace)
Crushed coal
(cyclone-fired,
wet-bottom furnace)
Crushed coal
Spreader stoker
(traveling grate)
Rated
capacity
103 Ib
per hour
1000
/1900 psig\
I 1000°F J
/ 92° x
(1900 psig\
\ 1000°F/I
940
^ 1050° Fj
150
/1000psi^\
\ 8354F )
1360
/2400 psig\
( losoV)
220
/875Psig\
I 760° F j
Dust
collector
Multiple
cyclone
and
electrostatic
precipitator
Electrostatic
precipitator
Multiple
cyclone
and
electrostatic
precipitator
Multiple
cyclone
Electrostatic
precipitator
Multiple
cyclone
Fuel and operating data
As-received basis
Moisture,
%
1.1
1.1
1.1
1.1
1.1
2.3
1.2
2.8
1.8
2.0
2.0
2.0
1.1
1.1
4.2
4.6
4.9
Volatile,
%
30.8
30.8
30.8
30.8
30.8
38.3
36.2
37.2
32.9
36.5
36.5
36.5
37.0
37.0
42.3
43.7
43.8
Ash,
%
19.8
19.8
19.8
19.8
19.8
9.8
8.1
16.0
11.7
7.9
7.9
7.9
7.5
7.5
7.1
8.3
8.7
rate
Gross
Btu
input
rate
per hour
tans
64.5
65.2
67.0
48.0
46.2
52.0
49.5
56.6
8.8
10.8
9.1
59.0
66.8
9.0
9.2
9.3
million Btu
1525
1541
1584
1135
1092
1315
1340
1365
232
285
240
1647
1861
233
232
230
103 Ib
1100
1100
1100
830
830
860
860
960
149
152
149
1320
1330
160
160
156
s
F
O
F
o
§
o
-------
a
0>
n>
(B
o
o
o>
en
co
0>
01
Table 4. DESIGN AND OPERATIONAL SUMMARY: HEAT GENERATION SOURCES (INTERMEDIATE-SIZED COAL-FIRED UNITS AND INTERMEDIATE
- AND SMALL-SIZED OIL - AND GAS-FIRED UNITS)
Sample
No.
ISS- 6
7
5
4
14
8
12
10
17
13
15
11
9
18
16
21
Design data
Fuel
_i
3
o
_j
0
<
o
Firing method
Pulverized
(dry-bottom furnaces)
Chain grate stoker
Spreader stoker
(with reinjector)
Underfeed stokers
Steam-atomized
Low-pressure
air-atomized
Pressure-atomized
Vaporized
Premix burners
Type of unit
Water-tube
boiler
Water -tube
boiler
Fire-tube
boiler
Water-tube
boiler
Scotch-marine
boiler
Cast-iron sec-
tional boiler
Hot-air furnace
Hot-air furnace
Fire-tube
boiler
Scotch-marine
boiler
Double-shell
boiler
Hot-air furnace
Wall space
heater
Use
Process
heating
Electric
generation
Process
heating
Process
heating
School
heating
Process
heating
Hospital
heating
Home
heating
Home
heating
Process
heating
Hospital
heating
Home
heating
Rated capacity
per hr
103lb
steam
200
125
70.5
22
30
million
Btu°
7.2
3.8
23
30
4.2
0.25
0.14
0.09
7.2
4.2
0.18
0.21
0.025
Dust
collector
Multiple
cyclone
None
Multiple
cyclone
None
None
None
Fuel data
As-received basis
Moisture,
%
3.2
10.4
3.0
1.2
2.0
Volatile,
%
36
44
37
36
19
Ash,
%
4.3
7.0
4.7
4.7
5
No. 2 fuel oil
(28.5° API)
No. 6 fuel oil
(13.5° API)
No. 1 fuel oil
(43.5° API)
No. 2 fuel oil
(31.5° API)
No. 2 fuel oil
(31.5° API)
No. 1 fuel oil
(43° API)
Natural gas
(94.2% methane
3.6% ethane)
Operating conditions during test
Fuel rate
Ib
9,420
12,400
4,290
317
214
1,110
769
35
8.8
4.4
1.2
402
42
7.9
7.4
0.51
Gross Btu
input
per hr
million Btu
130
147
59.2
4.4
3.0
21
14.4
0.70
0.17
0.085
0.025
9.3
0.98
0.18
0.17
0.012
Steam
rate
103lb
106
111
49
17.9
10.3
Steam
pressure
PSIg
307
450
160
110
37
250
125
95
108
96
Smoke
Opacity, %
60
20-40
0-20
20-40
0-20
5
5
0
0
0
0
0
0-20
0
0
0
""Gross heat input
-------
for institutional and home heating. Firing was accomplished with under-
feed stokers. The smallest units surveyed were domestic underfeed
and hand-stoked furnaces used for heating single-family dwellings
(Table 5).
Table 5. DESIGN AND OPERATIONAL SUMMARY: HEAT GENERATION SOURCES (COAL-
FIRED RESIDENTIAL FURNACES)
Sample
No
ISS-19
34
36
59
60
20
57
58
Design
Firing
Method
Underfeed
Hand-stoked
Type of
unit
Cast-iron
sectional
boiler
Hot-air
Furnace
Hot-air
Furnaces
Fuel and operating data
As-received basi s
Moisture,
%
3.5
3.5
2.0
2.8
2.8
1.8
2.3
2.3
Volatile,
38
38
22
38
38
38
38
38
Ash,
3.9
3.9
4.0
2.4
2.4
2.7
2.9
2.9
Fuel
rate
Gross Btu
input
per hr
Ib
4.8
4.2
3.8
5.0
4.5
8
6.3
5.6
mi 1 1 ion
Btu
0.066
0.058
0.056
0.070
0.063
0.115
0.089
0.080
Opacity,
0- 20
0- 15
0
0- 10
0- 10
40- 80
0- 70
<5- 70
Rates of emission of polynuclear hydrocarbons from coal-burning
units varied widely, depending on the quality of combustion achieved.
The highest emission rates were found in small domestic furnaces used
to heat single-family homes. For example, tests on hand-fired and
underfeed stoker-fired domestic units, with essentially no combustion
control, showed emissions ranging from 3800 to 3, 300, 000 micrograms
of BaP* per million Btu gross heat input (Table 8). Intermediate-sized
and large-sized units incorporating chain-grate stokers, spreader
stokers, pulverized feed, and cyclone firing achieved better combustion
and produced appreciably lower emissions of polynuclear compounds
(17 to 370 micrograms of BaP per million Btu gross heat input) at
normal operating conditions (Tables 6 and 7). Among the other large,
fully instrumented, coal-fired steam power plants, the cyclone-fired
unit, which burns crushed coal, showed the highest emission rate (76
to 370 micrograms of BaP per million Btu gross heat input).
In Figure 3, BaP emission rates are plotted against size of the
coal-, oil-, and gas-fired units. Because of the many variables affect-
ing the formation of this compound, a wide range of emissions can be
*Benzo{a)pyrene; abbreviations for other compounds are given in Table 2.
POLYNUCLEAR HYDROCARBONS
-------
10« 10' 10"
GROSS HEAT INPUT TO FURNACE, Btu/hr
Figure 3. Range of benzo (a) pyrene emissions from coal, oil, and natural gas heat-generation
processes.
expected from a given size of unit and the results do not lend themselves
to a straight-line relationship. Emissions of BaP from units operating
with relatively good combustion conditions would be expected to fall
near the lower boundary of the range, whereas emissions from less
efficient combustion processes would fall near the upper boundary.
Although it is constructed with limited data from oil- and gas-burning
sources, the plot in Figure 3 emphasizes that heavier emissions are to
be expected from coal-burning units than from gas- or oil-fired units
of comparable sizes.
The lower emission rates from the large coal-fired units can be
attributed to the more efficient combustion of fuel attainable with
closely regulated air-fuel ratios and uniformly high combustion-chamber
temperatures.
Among the seven polynuclear hydrocarbons for which the analytical
technique was most reliable, pyrene, BaP, and benzo(e)pyrene were
detected in all coal-fired units tested (see Tables 6 through 8). In all
Heat-Generation Processes
-------
Table 6. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: HEAT GENERATION SOURCES (COAL-FIRED POWER PLANTS)
Sample
No."
ISS-22
24
25
27
28
29
31
42
44
61+62
63
64
65
69
70
71
72
73
Type of unit
Pu Iverized coal
(vertical ly-fired,
dry-bottom furnace)
Pulverized coal
(front-wall-fired,
dry-bottom furnace)
Pulverized coal
(tangential ly-fired,
dry-bottom furnace)
Pulverized coal
(opposed-, downward-
inclined burners;
wet- bottom furnace)
Crushed coal
(cyclone-fired,
wet-bottom furnace)
Spreader stoker
(traveling grate)
Sampling
Polntb
B
B
A
A
B
A
B
A
A
A
A
A
A
Benzene-
soluble
Organics
a per
10° Btu
3.0
0.99
1.7
2.0
1.4
1.4
1.3
1.2
0.34
0.62
0.65
1.3
1.1
1.0
2.1
0.92
1.1
1.8
1.4
Group 1
BaPc
M9/S ,
^soluble6
16
22
11
9.3
39
38
330
110
48
33
220
110
21
21
175
83
22
<8.5
<11
ldb%me5e
110
50
42
42
130
120
930
270
39
48
320
330
57
46
730
170
58
<36
<33
vg per
Ib fuel
0.58
0.26
0.23
0.22
0.66
0.63
5.3
1.5
0.21
0.28
1.7
1.9
0.29
0.28
5.2
1.1
0.31
<0.19
<0.19
BaP
P
BeP
Per
BghiP
Anth
Cor
Group 2
A
Phen
Fluor
Micrograms per million Btu heat input
49
22
19
19
56
55
440
130
17
21
140
140
22
21
370
76
24
<15
<15
150
130
190
120
180
230
840
74
200
160
140
130
51
39
1800
250
59
32
21
33
41
250
79
55
84
420
110
72
680
no
61
66
23
71
34
45
19
160
83
14
150
1100
190
150
360
36
16
35
4.9
4.7
7.1
93
19
8.
11
9.5
110
820
200
32
370
190
210
190
320
410
1700
84
160
13
390
210
65
55
no
44
59
32
21
O
r
w
§
o
°Additional filter used before the bubblers in the sampling train as shown in Figure 1
°B: sampling point before fly ash collector; A: after fly ash collector.
c"Less than" values for benzo (a)pyrene were calculated for those samples having concentrations below the limit of
quantitative determination (approximately 0.6 microgram per sample). Similar calculations were not included for the
other polynuclear hydrocarbons (indicated by blanks in the table).
"Micrograms per gram of benzene soluble organics.
eMicrograms per 1000 cubic meters of flue gas at standard conditions (70°F, 1 atmosphere).
-------
w
(D
o
n>
(D
o
o
o
0)
en
en
Table 7. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: HEAT GENERATION
INTERMEDIATE-AND SMALL-SIZED OIL-AND GAS-FIRED UNITS)
SOURCES (INTERMEDIATE-SIZED COAL-FIRED UNITS AND
Sample
No.
ISS- 6
7
5
4
14
8
12
10
17
13
15
11
9
18
16
47
Fuel
3
O
u
_l
o
CO
<
O
Firing method
Pulverized
Chain grate stoker
Spreader stoker
Underfeed
stokers
Steam-atomized
Low-pressure
air-atomi zed
Pressure atomized
Vaporized
Premix burners
Benzene-
soluble
organics
M9 per
106 Btu
2.9
1.9
5.4
3.0
4.0
1.4
3.3
14
8.1
3.6
3.5
1.1
1.2
0.95
0.65
5.2
Group
BaP
fg/g
Efsol.t
11
19
4.7
3,400
29
<11
15
65
<4.6
<17
<33
<17
170
<21
<35
51
BaP°
^g per
1000 m3c
75
71
49
7,900
61
<38
40
1,900
<26
<27
<34
<29
350
<23
<30
71
^g per
Ibfuel
0.43
0.44
0.35
140
1.6
<0,3
0.89
18
<0.9
<1
<2
<0.4
4.6
<0.5
<0.6
6.1
P
BeP
Per
B(ghi)P
Anth
Cor
Group 2
A
Phen
Fluor
Micrograms per million Btu heat input
32
37
26
10,000
120
<20
47
900
<40
<60
<100
<20
200
<20
<20
270
240
390
590
16,000
1,700
49
300
6,100
1,800
15
1,200
160
18,000
170
120
16,000
92
130
350
7,900
230
490
18
1,500
1,600
4,500
300
1,800
2,300
290
200
73
26
330
2,100
14
5,300
830
370
850
3,900
10,000
1,000
1,800
3,500
8,900
77
550
680
360
38,000
3,200
.56
270
1,900
5,000
76
15,000
100
2,900
320
110
8,000
a"l_ess than" values for benzo(a)pyrene were calculated for those samples having concentrations below the limit of
quantitative determination (approximately 0.6microgram per sample). Similar calculations were not included for
the other polynuclear hydrocarbons (indicated by blanks in the table).
^Micrograms per gram of benzene-soluble organics.
cMicrograms per 1000 cubic meters of flue gas at standard conditions (70°F, 1 atmosphere).
-------
Table 8. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: HEAT GENERATION SOURCES (COAL-FIRED RESIDENTIAL FURNACES)0
Sample
No.
ISS-19
34
36
59
60
20
57
58
F iring
method
Under-
feed
Stokers
Hand-
stoked
Benzene-
soluble
orgonics
g per
106 Btu
2.4
47
73
20
8.7
91
170
350
Group 1
BaP
/ig/g
0sol.b
1,600
1,400
1,100
3,400
990
3,900
10,400
9,400
u. g Per
lOOOmSc
3,400
40,000
44,000
18,000
2,200
340,000
690,000
1,500,000
M9 Per
Ib fuel
52
900
1,200
930
120
6,000
25,000
46,000
BaP
P
BeP
Per
BghiP
Anth
Cor
Group 2
A
Phen
Fluor
Micrograms per million Btu heat input
3,800
65,000
81,000
67,000
8,600
400,000
1,700,000
3,300,000
7,700
300,000
190,000
160,000
45,000
600,000
2,700,000
9,100,000
5,400
39,000
59,000
55,000
7,700
100,000
870,000
1,500,000
7,900
4,800
5,500
430
60,000
220,000
350,000
580
61,000
58,000
59,000
6,300
300,000
1,400,000
2,200,000
6,100
3,000
1,300
90,000
270,000
490,000
1,200
4,100
3,400
30,000
49,000
97,000
70,000
48,000
14,000
1,300
400,000
1,100,000
2,900,000
29,000
610,000
350,000
170,000
51,000
1,000,000
2,300,000
7,500,000
47,000
330,000
150,000
320,000
76,000
1,000,000
4,300,000
11,000,000
o
t-1
o
f
M
§
o
s
°A blank indicates that the compound was not detected in the sample.
^Micrograms per grams of benzene-soluble organics.
cMicrograms per 1000 cubic meters of flue gas at standard conditions (70°F, 1 atmosphere).
-------
but two tests, the ratio of pyrene to BaP was greater than 1, varying
from 0. 6 to 23. Ratios of BaP to benzo(ghi)perylene ranged from 0. 9
to 6. 6 except for one power plant for which the ratio was 0.13. Ratios
of BaP to coronene ranged from 1. 0 to 94. Average ratios for the res-
idential coal-fired furnaces are as follows: P/BaP, 2. 6; BaP/BghiP,
1. 7; BaP/Cor, 19. These results tend to confirm the data reported by
Sawicki 19 regarding the ratios of these compounds in particulate
samples collected from the atmosphere. Sawicki states that particulate
pollution from coal-burning sources (as opposed to auto exhaust) might
be characterized by ratios of BaP to benzo(ghi)perylene greater than
0. 6 and ratios of BaP to coronene greater than 1. He further suggests
that the ratio of pyrene to BaP might indicate the "age" of the particu-
late pollution, since pyrene is less stable in the atmosphere than is
BaP and tends more to be lost by volatilization. This interpretation is
substantiated by the finding that ratios of pyrene to BaP in particulate
matter collected from the atmosphere in cities throughout the United
States were less than 1 in most cases reported. 8
Comparison of polynuclear hydrocarbon emissions with other
products of incomplete combustion indicates that polynuclear emission
rates are generally high when carbon monoxide and total gaseous hydro-
carbons are high. 9
Oil-Burning Units
The capacities of the oil-burning units tested ranged from 0. 09 to
30 million Btu per hour gross heat input (Table 4). The largest of these
boilers produced steam for process heating and was fired by steam-
atomizing burners. The smaller units (up to 4. 2 million Btu/hr, heat
input) produced hot water and hot air for institutional and home-heating
uses; most of these units were fired by air-atomizing and pressure-
atomizing burners.
Polynuclear hydrocarbon emissions from oil-burning sources
were generally much lower than from coal-burning sources of equiva-
lent size (Table 7). Detectable BaP concentrations were found in only
two of the six oil-burning units tested, but pyrene was present in all
sources. Ratios of pyrene to BaP for the two BaP-emitting units
averaged 6. 6. Ratios of BaP to benzo(ghi)perylene were >2 and 3.0,
and ratios of BaP to coronene were 0.4 and >5. The highest BaP emis-
sion rate from oil-burning occurred in a unit with an air-atomizing
burner.
Low BaP emissions from liquid-petroleum-fired units have also
been reported by Howe. 20 In a study of household-sized units (12, 000
to 250, 000 Btu per hour) and small industrial-sized units (6, 000 pounds
of steam per hour), no BaP was detected in the samples collected. Two
of the small household-size units produced smoke during testing.
Heat-Generation Processes 13
-------
Gas-Burning Units
The gas-burning units tested ranged in capacity from 0. 025 to 7. 2
million Btu per hour gross heat input (Table 4). The larger units pro-
vided steam for process and institutional heating; the smaller units
(0. 21 million Btu per hour gross heat input and below) provided hot
water and hot air for single-family home heating.
Polynuclear hydrocarbon emissions from gas-fired units were
generally lower than from coal-fired units and were about the same as
emissions from oil-fired units (Table 7). For three of the five gas-fired
sources the only compound of consequence was pyrene. Two gas-fired
sources (Samples ISS-9 and ISS-47) produced more polynuclear hydro-
carbons than the others, apparently because of improper adjustment of
the air-fuel ratio as evidenced by high concentrations of CO and total
gaseous hydrocarbons. The ratio of pyrene to BaP for these sources
averaged 75. The ratios of BaP to benzo(ghi)perylene and BaP to
coronene averaged 0. 1 and 0. 2, respectively; these values contrast
with the higher ratios obtained in tests of coal-fired units and are more
similar to the lower ratios for auto exhaust. 19
REFUSE BURNING
Incinerators
Waste materials burned during the incinerator tests were typical
of present-day municipal and commercial wastes collected from house-
holds, grocery stores, and restaurants. Municipal units included a
continuous-feed 250-ton-per-day furnace and a batch-charged 50-ton-
per-day furnace equipped with water spray scrubbers. Commercial
incinerators included a 5. 3-ton-per-day unit and a 3-ton-per-day unit
equipped with an auxiliary gas burner. (See Table 9).
Polynuclear hydrocarbon emissions produced by municipal and
commercial incinerators are summarized in Tables 10 and 11. BaP
and benzo(e)pyrene, both of which have demonstrated carcinogenic
qualities, were detected in the flue gases from every incinerator tested.
The concentrations of pyrene from each unit were higher than those of
any of the other polynuclear hydrocarbon compounds detected, and
ratios of pyrene to BaP ranged from 6.0 to 120. Ratios of BaP to
benzo(ghi)perylene ranged from 0. 3 to more than 2, and ratios of BaP
to coronene ranged from 0. 3 to 2. 5. Following the pattern of the coal-
fired sources, the small-sized commercial incinerators with relatively
poor combustion emitted more polynuclear hydrocarbons than the
intermediate- and large-sized municipal units. The largest municipal
unit, operating at relatively constant temperatures above 1600°F and
with longer gas retention times in the high-temperature zone, produced
the least of these compounds in terms of emissions per pound of refuse
charged. In additional tests run with less underfire air (50 and 20 per-
cent versus 80 percent) this low emission rate was reduced only slightly.
14 POLYNUCLEAR HYDROCARBONS
-------
g?
Table 9. DESIGN AND OPERATIONAL SUMMARY: INCINERATION AND OPEN-BURNING SOURCES
Sample
No.
INC- 19+20
11+17
12+18
38+39
35+37
24+25
27
29+30
31 + 32
33+34
40+41
42+43
44
Design data
Type of unit
Municipal
Incinerators
Commercial
Incinerators
D)
C
'§
D
CQ
c
u
CL
O
Multiple chamber,
travel ing grate
(continuous feed)
Multiple chamber
batch charged,
reciprocating
Single chamber
Multiple chamber
with auxi Mary gas
burner in primary
chamber
On-site
air samples
Facility for
research on open
burning fires
Rated
capacity
tons /day
250
50
5.3
3
Grate
area
f|2
288
85.5
13
19.7
Dust
collector
Settling
Chamber
Water
spray
scrubber
None
None
Fuel data
Type
Residential refuse
(14 to 20% non-
combustiblej
Residential and com-
mercial refuse (14 to
20% noncombustible)
Cardboard,
Packing crates
60% paper
40% wet garbage
Municipal refuse
Automobi le tires
Grass cl ippings,
leaves, tree branches
Automobile bodies
Municipal refuse
Grass clippings,
leaves, tree branches
Automobi le
components
Moisture
content, %
35
25
20
50
20
25
Operating data
Charging
rate
tons/day
260
49
4.7
2.3
Underfire
air
%
80
50-60
0
Excess
air
%
185°
108a
465C
Gas
temp.
°F
1940b
1470°
1300b
1850b
Smoke
Opacity,%
20
0
0-20
0-50
20-100
20-100
20-100
20-100
a]n breeching.
bln furnace.
cln stack.
-------
Table 10. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: INCINERATION AND OPEN BURNING SOURCES
Sample
No.
INC- 19 + 20
11+17
12+18
38+39
35+37
40+41
42+43
44
Type of unit
,E?-
1
E
0
O
1
c
O
250-ton/day
Multiple chamber
50-ton/day
Multiple chamber
5.3-ton/day
Single chamber
3-ton/day
Multiple chamber
Municipal refuse
Grass clippings,
leaves, branches
Automobile
components
Sampling
point
Breeching (before
settling chamber
Breeching
(before scrubber)
Stack
(after scrubber)
Stack
Stack
Stack
(facility for
research on open-
burning fires)
Benzene-
soluble
organics
g/lb
of
refuse
0.018
0.0031
0.0060
0.012
0.065
3.37
3.48
3.03
Group 1
BaP
Mg/g
4.2
2000
15
4500.0
5900
45
45
4300
1000m3c
19
2700
17
11,000
52,000
2800
4200
173,000
BaP
P
BeP
Per
BghiP
Anth
Cor
Group 2
A
Phen
Fluor
Micrograms per pound of refuse charged
0.075
6.1
0.089
53
260
153
157
13,000
8.0
52
2.1
320
4200
800
780
34,300
0.34
12
0.58
45
260
105
70
6570
3.1
60
17
1180
34
0.63
90
870
70
73
8900
6.6
79
12
1000
0.24
15
0.63
21
210
1090
47
86
1420
18
140
59
9690
9.8
4.6
3.3
220
3900
730
505
24,400
o
f
o
f
O
§
n
aA blank indicates that the compound was not detected in the sample.
'•'Micrograms BaP per gram benzene-soluble organics.
cMicrograms per 1000 cubic meters of flue gas at standard conditions (70° F., 1 atmosphere).
-------
3?
?
OJ
CD
Table 11. POLYNUCLEAR HYDROCARBON CONTENT OF PARTICIPATE MATTER EMITTED: INCINERATION AND OPEN BURNING SOURCES
Sample
No>
INC-19 + 20
11 + 17
12+18
38 + 39
35 + 37
24 + 25
27
29 + 30
31 + 32
33+34
40 + 41
42 + 43
44
Type of unit
— i~
Municipa
incinerate
Commercial
incinerators
en
c
c
D
m
0)
a.
0
250-ton/day
Multiple chamber
50-ton/day
Multiple cnamber
5. 3- ton/day
Single chamber
3-ton/day
Multiple chamber
Municipal refuse
Automobile tires
Grass clippings,
leaves, branches
Automobile bodies
Municipal refuse
Grass cl ippings,
leaves, branches
Automobile
components
Sampling
point
Breeching (before
settling chamber)
Breeching
(before scrubber)
Stack
(after scrubber)
Stack
Stack
In smoke
plume
(on- site
air samples)
Stack
(facility for
research on
open-burning
fires)
Group 1
BaP
P
BeP
Per
BghiP
Anth
Cor
Group 2
A
Phen
F luor
Micrograms per gram of particulate
0.016
3.3
0.15
58
180
11
1100
35
270
28
29
380
1.9
28
3.6
350
2600
29
1300
120
670
146
152
1000
0.08
6.5
0.97
49
180
4.5
450
21
120
19
14
190
3.3
36
72
33
2.8
35
19
1.1
98
540
660
5.4
150
12
12
260
7.1
45
53
12
1.8
29
0.06
8.2
1.1
23
130
81
15
32
51
53
4.7
110
4.7
220
43
9.8
150
62
450
160
280
2.2
2.5
5.5
240
2400
13
470
110
450
133
100
710
QA blank indicates that the compound was not detected in the
'•'Additional filter used before the bubblers in the sampling trai
sample.
in as shown in Figure 1 for tests 40 through 44).
-------
A water-spray scrubber used to control fly ash from the smaller
municipal unit proved highly effective in reducing the level of polynuclear
hydrocarbons emitted to the atmosphere. Emissions of BaP, for ex-
ample, were reduced 98 percent by use of the scrubber. Additional
tests with a combination of lower-than-normal underfire air (19 percent
versus 50 to 60 percent) and higher excess air (220 percent versus 108
percent) also reduced emissions at a rate equivalent to that obtained
with the scrubber.
Open-Burning Sources
Emissions from open fires were evaluated by two different
methods: on-site sampling and sampling at a special test facility. In
on-site sampling a high-volume air sampler attached to the end of an
8-by-10-inch duct collected particulate samples on MSA 1106-BH glass-
fiber filters. The open end of the duct was positioned in the smoke
plume. Separate samples were taken from the open burning of munic-
ipal refuse, automobile tires, grass and tree branches, and automobile
bodies. Refuse burning rates and combustion gas flow rates were not
obtained during these tests because of the difficulty of making such
measurements in the field. Hence, results can be compared only on
the basis of the amounts of polynuclear hydrocarbons in the particulate
matter collected. Table 11 summarizes the results.
The facility designed specifically for research on open fires was
made available by the Air Pollution Research Center of the University
of California at Riverside. This facility consists of a "burning table"
with an inverted conical hood suspended above it to collect and funnel
the combustion products into a stack. Instrumentation allowed the
measurement of flue-gas flow, weight of fuel remaining, and temper-
ature, and the analysis of gases. Quantitative emissions were deter-
mined for the open burning of municipal refuse, grass and tree branches,
and automobile components. Results are given in Tables 10 and 11.
The comparatively high emissions of polynuclear hydrocarbons
from open burning, especially of automobile components, is consistent
with the general pattern that has developed for other combustion proc-
esses; i. e., the inadequate combustion conditions typical of uncon-
trolled burning processes consistently produce the highest levels of these
compounds. Ratios of pyrene to BaP ranged from 1. 2 to 2. 6, BaP to
benzo(ghi)perylene from 1. 7 to >20, and BaP to coronene from 6. 6 to
>60. These ratios are similar to those for residential coal furnaces.
INDUSTRIAL PROCESSES: DIRECT SAMPLING
Petroleum Catalytic Cracking -- Catalyst Regeneration
Concentrations of polynuclear hydrocarbons in the waste gases of
catalyst regenerators were measured for each of the major types of
petroleum catalytic cracking units: Fluid catalytic crackers (FCC);
18 POLYNUCLEAR HYDROCARBONS
-------
Thermofor catalytic crackers (TCC), both air lift and bucket elevator
catalyst carriers; and a Houdriflow catalytic cracker (HCC).
The objective of catalytic cracking is to upgrade heavier petro-
leum fractions by breaking up long-chain hydrocarbons to obtain high-
octane gasoline and distillate fuels. The most common feed-stock is
the gas-oil fraction obtained from the crude distillate unit.
Although the catalytic cracking units surveyed may differ some-
what in equipment, geometry, and actual operation, the cracked prod-
ucts and basic chronology of the process are the same. Preheated gas-
oil and silica-alumina type catalyst are charged into a reactor main-
tained at about 900°F and 15 psig. The cracked products are separated
by fractionation and further processed. The spent catalyst, laden with
coke, is rejuvenated in a catalyst regenerator kiln. Here the coke is
burned off the catalyst at temperatures near 1000°F and pressures
ranging from 2 to 20 psig, depending on the type of unit; the catalyst is
recycled to the reactor. The regenerator flue gases, high in carbon
monoxide and unburned hydrocarbons, are then exited directly to the
atmosphere or to a carbon monoxide waste heat boiler. Typical flow
diagrams of the units tested are given in Figures 4, 5, and 6. Table 12
summarizes the operational data.
The emission rates measured are presented in Table 13. High
concentrations were present in the regenerator waste gases from the
HCC and TCC air-lift units. Emissions of BaP, pyrene, benzo(e)pyrene,
and benzo(ghi)perylene were especially high. The average BaP emis-
sion rates for the HCC and TCC air-lift units were 218, 000 and 90, 000
micrograms per barrel of oil charged. By comparison, the highest
BaP emission rates from TCC bucket elevator and FCC units were 31
and 460 micrograms per barrel of oil charged. These large variations
in emission rates cannot be explained by analysis of data from the small
number of tests performed in this screening program.
Concentration ratios for the high-emission units are as follows:
Unit P/BaP BaP/BghiP BaP/Cor
HCC 0.58 0.65 15
TCC, air lift 1.1-4.3 1.7-1.2
The HCC and FCC units incorporated CO waste heat boilers to
effect complete combustion of the regenerator flue gases. The CO
boilers, providing combustion with auxiliary fuels or a catalyst, greatly
reduced emissions of carbon monoxide and total gaseous hydrocarbons.
In addition, all the polynuclear hydrocarbons detected in the HCC regen-
erator waste gases, including BaP, underwent more than 99 percent
reduction upon passage through the CO boiler. BaP emissions were
reduced from 218, 000 to 45 micrograms per barrel of oil charged. The
CO boilers on the FCC units further reduced the low emissions.
Industrial Processes 19
-------
The TCC air-lift units were equipped with plume burners. The
plume burner is a secondary stage of combustion built into the regen-
erator kiln. This type of burner has successfully increased the clarity
of plumes from regenerator waste gases; however, compared to a CO
waste heat boiler, the plume burner is ineffective as a control device
for reducing emissions of polynuclear hydrocarbons, total gaseous
hydrocarbons, and carbon monoxide.
In 1964, CO boilers in the United States burned regenerator gases
from 65 percent of the total HCC capacity and 31 percent of the total
FLUE GAS
STACK
CATALYST
REGENERATOR
OVERFLOW
WELL
REACTOR
PURGE STREAM
20
Figure 4. Fluid catalytic cracking unit, Model IV.
POLYNUCLEAR HYDROCARBONS
-------
VENT
LIQUID FEED
STEAM
VAPOR FEED —
REACTOR
PURGE STEAM-
FLUE GAS
SAMPLING
POINT
COMBUSTION
AIR
CATALYST
REGENERATOR
FLU EGAS
SAMPLING
POINT"
SURGE
HOPPER
SYNTHETIC CRUDE
AIRLIFT
SECONDARY
LIFT AIR
PRIMARY
LIFT AIR
Figure 5. Airlift TCC catalytic cracking unit.
Industrial Processes
21
-------
VENT
LIFT DISENGAGER
REACTOR FEED
FLUE GAS
REACTOR
CRUDE
PURGE
STEAM
CATALYST
REGENERATOR
COMBUSTION
AIR
-D
STACK
SAMPLING
POINT
1000000
DDDDODDODDD
STEAM
CATALYST
LIFT PIPE
LIFT ENGAGER
Figure 6. Houdriflow catalytic cracking unit.
22
POLYNUCLEAR HYDROCARBONS
-------
I
en
o
o
(B
Ol
03
0>
01
Table 12. OPERATIONAL SUMMARY: PETROLEUM CATALYTIC CRACKING, CATALYST REGENERATION
Sample
No.
ISS-49,50
51,52
78
80,81
53,54
55,56
66
74+75
76+77
67
68
Catalytic reactor
Type of
unit
FCC
FCC
HCC
TCC
(Air lift)
TCC
(Air lift)
TCC
(Bucket lift)
Process rate
(fresh feed and recycle)
bpsda
20,200
23,000
46,250
46,600
37,200
34,400
19,600
22,800
23,800
13,200
10,000
Recycle,
%
46
41
44
44
30
27
15
42
45
31
33
Charge
stock
°A.P.I.
31
30.5
30
25
35
29
30
Catalyst regenerator
Waste gas
CO,
%
6.5
9.1
10.0
9.8
4.2
5.1
6.3^
4.1 b
3.3b
4.2
4.7
Combustion
equipment
Waste
Heat
Boiler
Waste
Heat
Boiler
Catalytic
Waste
Heat
Boiler
Plume
Burner
Plume
Burner
None
Catalyst
Geometry
Powder
Powder
Bead
Bead
Bead
Bead
Circulation
rate,
tons/hr
2,500
2,500
890
920
550
440
440
148
148
to
CO
aBarrels per stream day.
"Average composition from two stacks.
-------
CO
tr-
13. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: PETROLEUM CATALYTIC CRACKING, CATALYST REGENERATION0
Sample
No.
ISS-49d
50d
511
52d
78+80
81
53d
55d
54+56d
66d
74+75
76+77
67"
68d
Type of
Unit
FCC
FCC
HCC
TCCe
(Air lift)
TCC
(Air lift)
TCC
(Bucket lift)
Sampling
pom!
Regenerator
outlet
CO boiler
outlet
Regenerator
outlet
CO boiler
outlet
Regenerator
outlet
CO boiler
outlet
Regenerator
outlet
CO boiler
outlet
Regenerator
outlets
Regenerator
outlets
Regenerator
outlet
Benzene-
soluble
organ ics
grams per
barrel oil
charged
0.69
0.95
0.21
0.84
1.82
0.22
9.0
14
0.09
36
12.2
13.5
0.26
0.38
Group 1
BaP
M g per
grn^sol.0
63
12
20
<7.5
253
97
22,700
17,000
502
3,280
4,560
4,590
120
<24
f g P«
1000 m3c
400
46
46
6,400
212
2,800,000
2,700,000
61C
1,200,000
680,000
780,000
320
BaP
P
BeP
Per
BghiP
Anth
Cor
Group 2
A
Phen
Fluor
Microgiams per barrel oil charged (fresh feed plus recycle)
44
11
4.3
460
21.5
205,000
231,000
45
120,000
56,000
62,000
31
167
87
40
25
28,000
165
131,000
130,000
39
132,000
250,000
260,000
280
360
53
21
11
3,600
18
310,000
380,000
97
120,000
56,000
75,000
82
34,000
34,000
4.8
!0,000
8,800
5,500
15
424
55
300,000
380,000
125
72.COO
44,000
54,000
15,000
18,000
3.2
4,40C
1,300
1,750
11,200
26,000
8.3
360
2,070
920
2,000
7.9
24,000
10,300
10,600
400.000
21,000
29,000
83
78,000
352,000
330,000
160
72
44
20
20,000
85
8,300
11,400
23
29,000
10,600
59
106
o
t-1
o
§
o
a A blank indicates that the compound was not detected in the sample.
''Micrograms per gram of benzene-soluble organics.
cMicrograms per 1000 cubic meters flue gas at standard conditions (70°F, 1 atmosphere).
d Additional filter used before the bubblers in the sampling train as shown in Figure 1.
e Emmission rates for this unit are only approximate.
-------
air-lift TCC capacity. Fifty-one of a total of approximately 113 FCC
units are equipped with CO boilers. The use of plume burners on air-
lift TCC units amounted to 45 percent of total capacity.
Asphalt Air-Blowing Process
The asphalt plant surveyed processed about 140, 000 gallons of
asphalt per day (24 tons per hour). The air-blowing operation involved
charging 10 enclosed reactors of 5, 000- and 10, 000-gallon capacity
each with petroleum-base asphalt; the material was then heated exter-
nally by gas burners and maintained at temperatures ranging from 430
to 500°F. Air then was bubbled through the hot asphalt continuously for
periods ranging from 8 to 16 hours. The partially oxidized end products,
more viscous and less resilient than ordinary asphalt, are termed either
flexible coating, linoleum saturate, or shingle material. A summary of
the polynuclear hydrocarbon emissions and a flow sheet of the asphalt-
blowing process are given in Figure 7.
The gaseous emissions from the 10 reactors in operation were
vented to the atmosphere through a system consisting of a common duct,
oil knock-out tanks, and a stack. The individual reactors are charged
on a rotating schedule; hence, the gases vented to atmosphere at any
given time represent materials emitted at different stages of the air-
blowing process.
The lower section of the stack was equipped with a steam spray-
baffle arrangement. Pyrene was detected in large quantities in samples
collected at the inlet and outlet sides of this baffle arrangement. The
pyrene emission rate at the inlet was 3. 5 grams per ton of material
processed. Anthracene was present in smaller quantities. Phenan-
threne and fluoranthene were detected in trace amounts. BaP, if
present, was not detected because of interferences from unknown com-
pounds. On the basis of the threshold concentration for this analysis,
the BaP concentration in the gases would be at most 10 milligrams per
ton of processed material. At this concentration, the daily contribu-
tion of BaP from this asphalt-blowing source would be less than that
from two hand-stoked residential coal furnaces. By comparison, an
equivalent emission of pyrene would require 250 hand-stoked furnaces
(see Table 8).
Simultaneous with collection of the source samples, atmospheric
concentrations of polynuclear hydrocarbons were measured in the
immediate plant vicinity. For this purpose, high-volume air samplers
were situated 1/4 to 1/2 mile from the plant in five residential areas
of the city. Benzene extracts from the collected atmospheric samples
(July 1962) were composited for a single analysis. BaP from this
analysis measured 0. 42 microgram per 1000 cubic meters air. This
concentration is considerably lower than the 3. 9 micrograms per 1000
cubic meters (July 1958) reported previously7 for the downtown area
of the same city.
Industrial Processes 25
-------
SAMPLING
LOCATION
Inlet
Outlet
GAS
FLO«
scf m
8,400
IB. 600
BENZENE-
SOLUBLE
ORGANICS
POLYNOCLEAR HYDROCARBONS3
PYRENE
processed
1.800
4,400
3.5
4.1
BaP
ANTHRACENE
(70° F. 1 aim)
5,BOO,DOO
3,100,000
-20.000
-= 4.DOD
310,000
220,000
Detected: phenanthrene (outlet), fluoranthene (inlet)
Not Detected: Benzo(e)pyrene, perylene, benzo(Ehi)-
perylene, anthanthrene and coronene
SAMPLING LOCATIONS
GASEOUS EMISSIONS
i i
if
' STFAU I—'
-BAFFLE OIL KNOCKOUT TANKS-^ GAS BURNER—i
Figure 7. Flow sheet of effluent gases from asphalt air-blowing process-batch operation.
Thus, both the source samples and the air samples indicate that
polynuclear hydrocarbons larger than pyrene are not volatilized to any
significant extent by the air-blowing process. This process does not
appear to emit significant amounts of BaP or other polynuclear hydro-
carbons of equal or greater molecular weight. One other point of sig-
nificance is that Sawicki 22 has found that the samples contain large
quantities of alkyl-type polynuclear hydrocarbons (the analytical tech-
nique did not permit the determination of specific compounds of this
type). Alkyl polynuclear hydrocarbons such as 9, 10-dimethyl anthra-
cene and 1, 2, 4-trimethyl phenanthrene have been shown to be carcino-
genic in studies with animals. 4, 5 Because of the nature of the asphalt
air-blowing process, one would also expect the presence of oxygenated
hydrocarbons. Epstein23 has shown that the oxygenated fraction of the
benzene extract from atmospheric particulate samples produces skin
cancers on mice.
In summary, asphalt air blowing does not appear to be an im-
portant source of BaP. The source surveyed did emit large quantities
of unidentified alkyl polynuclear hydrocarbons. Future identification
of these alkyl compounds, and determination of oxygenated polynuclear
hydrocarbons or the absence thereof, should define more precisely the
importance of asphalt air blowing as a source of carcinogenic compounds.
26
POLYNUCLEAR HYDROCARBONS
-------
Asphalt Hot-Road-Mix Plant
An asphalt hot-road-mix plant with a capacity of 3 tons per batch
was tested for polynuclear hydrocarbon emissions by direct measure-
ments. The plant was operating at a rate of 133 tons of finished mix
per hour. A typical weighed 3-ton batch consisted of 6 percent asphalt
and 94 percent sand and crushed stone. The mixture of sand and
crushed stone was dried and charged to a mixer at 400°F. Asphalt at
250°F was then added to the mixer, and the materials were blended for
1 minute or less before being discharged to waiting trucks. A flow
sheet of the process and, a summary of emissions during the test are
given in Figure 8.
Effluent gases from both the mixer and the rotary drier
(45, 000, 000 Btu per hour) were passed in sequence through a cyclone
and a water spray tower to remove process contaminants. Samples
were collected simultaneously before and after passage through the
spray tower. Duplicate samples were taken at each sampling location
and combined for one analysis at each location.
D
SAMPLING
LOCATION
inlet
Outlet
GAS
FLO«
scfm
37,000
41,000
BENZENE-
SOLUBLE
ORGAN 1 OS
POLVNUCLEAR HYDROCARBONS3
Pyrene
grans per ton
processed
IS
0.9
0.0041
0.0016
BaP
BeP
BghiP
A
Fluor
microgranis per 1000 cubic meters
(70° F, 1 itn)
8,900
3,000
1,350
-=100
740
1,300
3,800
1,400
2,700
2,500
Selected: phenanthrene (outlet)
Hot detected: perylene, anthanthrene, coronene
FINISHED PRODUCT
Figure 8. Flow sheet of effluent gases from asphalt hot-road mix process—batch operation.
Nearly all the emissions reported from this hot-road-mix
plant are attributed to combustion gases emitted from the rotary dryer
and not to effluent gases from the mixing chamber. This is evidenced
by the results for a sample of the suspended particulates collected
Industrial Processes
27
-------
directly from the mixing chamber. Of the 10 polynuclear hydrocarbons
under consideration only anthracene was qualitatively identified. In the
sample collected from the gas stream prior to the spray tower, how-
ever, six polynuclear hydrocarbons, including BaP, were detected. At
this sampling location, the gas stream consisted of flue gases from the
dryer and effluent gases from the mixing chamber.
Concentrations of the Group 1 polynuclear hydrocarbons are
reduced considerably by the scrubbing effect in the spray tower. For
example, the BaP concentration was reduced from 630 micrograms per
ton of processed material to less than 50 micrograms per ton.
Because of the low inlet concentrations and the ease with which
pollutants are removed, the asphalt hot-road-mix process does not
appear to be a potentially important contributor of polynuclear hydro-
carbon emissions to the atmosphere.
INDUSTRIAL PROCESSES:
ATMOSPHERIC SAMPLING
The remaining industrial processes were evaluated by collection
of atmospheric samples in urban residential areas in the vicinity of the
installation. General atmospheric samples do not, of course, indicate
anything about the relative distribution in the atmosphere, e.g. , high
concentrations that may exist only a few feet from a source having
relatively small total emissions. For example, in one case reported
by Sawicki, et al. , ^4 gap concentrations as high as 78, 000 micro-
grams per 1000 cubic meters of air were found a few feet downwind
from a sidewalk tarring operation in which coal tar pitch was being used.
Carbon-Black Manufacturing
Samples of suspended particulates were collected at several urban
residential sites in the vicinity of carbon-black manufacturing plants.
The sites were located 1 to 3 miles from two adjacent carbon-black
plants. Figure 9 (City A) shows the general location of sampling sites.
Carbon black was manufactured primarily from incomplete com-
bustion of natural gas by both the furnace and channel processes. Some
residual oil was burned intermittently with natural gas in the furnace
process. One plant used both the furnace and channel methods whereas
the other used only the furnace method. At the time of testing, one plant
operated 360 burner houses for channel black and 2 production-size units
for furnace black. The other plant operated five production-size furnace
units.
The degree of carbon-black buildup on the filters varied from
heavy loadings when the sampling sites were fumigated by the carbon-
28 POLYNUCLEAR HYDROCARBONS
-------
black plume to light loadings at other times. All samples showed the
presence of carbon black.
Concentrations of polynuclear hydrocarbons in atmospheric par-
ticulate samples collected in winter and summer are summarized in
Tables 14 and 15. In Figure 10 the BaP concentrations near the three
processes investigated indirectly are compared with the average winter
and the average summer concentrations for a number of cities. These
comparisons can be used very generally to determine the BaP emission
potential of the three processes surveyed.
The winter BaP concentration in City A was well below the arith-
metic mean winter concentration calculated from previously reported
CARBON BLACK MFC
CITY A
STEEL AND COKE MFC
CITY B
CHEMICAL INDUSTRY
CITYC
RESIDENTIAL AND SMALL INDUSTRY
COAL-BURNING AREA
CITYD
. 1 MILE,
X-HI-VOLUME AIR SAMPLERS ^ -SOURCES SURVEYED
Figure 9. Maps of cities and sources included in the atmospheric survey.
Industrial Processes
29
-------
data7 for 102 United States cities (Figure 9). In fact, the BaP concen-
tration of 0. 58 microgram per 1000 cubic meters air in City A would
be the fourth lowest concentration if it were included in this 102-city
survey. On the basis of micrograms of BaP per gram suspended par-
ticulate, the concentrations in City A would rank eighth lowest.
Table 14. SUMMARY OF CONCENTRATIONS (BY VOLUME) OBTAINED IN ATMOSPHERIC
SAMPLING NEAR AIR POLLUTION SOURCES
(micrograms per 1000 cubic meters of air)a
Air pollution
source
City
Time of year
Benzene-
soluble
organics
Suspended
atmospheric
particulates
GROUP 1
CN
Q_
=>
o
a:
0
Benzo (a) pyrene
Pyrene
Benzo (e) pyrene
Perylene
Benzo (ghi) perylene
Anthanthrene
Coronene
Anthracene
Phenanthrene
Fluoranthene
Carbon
black
A
Summer
1260
60,000
0.035
0.15
0.18
0.37
0.16
0.43
Winter
3800
65,000
0.58
0.33
0.76
0.03
1.6
0.59
0.07
Steel and
coke
B
Summer
6700
100,000
8.6
6.6
4.1
1.0
7.1
0.83
0.44
2.4
3.2
Chemical
c
Winter
4600
169,000
6.9
0.37
0.57
1.5
0.78
0.30
aA blank indicates that the compound was not detected in the sample.
Carbon-black manufacture does not appear to be an important
source of polynuclear hydrocarbon emissions for the following reasons:
(1) the industry is relatively small; (2) although 87 percent of the carbon
black in 1961 was manufactured by the furnace process, only 20 percent
of the furnace black was classified as either "semi-reinforcing" or
"high modulus" furnace black, the classes shown by Falk, et al, 26, 27
to contain the most polynuclear hydrocarbons; (3) low BaP concentra-
tions were detected in the vicinity of the furnace-black plant tested.
These results might be expected since published data by Lindsey, et
al, 28 show no detectable BaP in a carbon-black sample of American
origin manufactured for industrial use. Other data reported by Lindsey,
et al, 29 show BaP concentrations as high as 1 percent by weight in two
carbon-black samples of European origin.
Other previously reported studies also appear to support the con-
clusion that carbon-black manufacture is not an important source. Nau,
30
POLYNUCLEAR HYDROCARBONS
-------
et al, 30, 33 showed that whole carbon black manufactured by the chan-
nel and furnace processes in the United states produces no appreciable
carcinogenic effect on animals. Ingalls 34 concluded from a statistical
study that the carbon-black worker faces no more than the ordinary
risks of cancer encountered by other groups of the male working popu-
lation.
Table 15. SUMMARY OF CONCENTRATIONS (BY WEIGHT) OBTAINED IN ATMOSPHERIC
SAMPLING NEAR AIR POLLUTION SOURCES
(micrograms per gram suspended participate)0
Air pol lution
source
City
Time of year
Q_
Z>
o
a:
o
(N
0_
3
O
a:
o
Benzo (a) pyrene
Pyrene
Benzo (e) pyrene
Perylene
Benzo (ghi) perylene
Anthanthrene
Coronene
Anthracene
Phenanthrene
Fluoranthene
Carbon
black
A
Summer
0.58
2.4
3.0
6.1
2.7
7.2
Winter
8.8
5.0
11
0.4
24
8.9
1.1
Steel and
coke
B
Spring
89
75
43
10
77
9.1
4.1
29
33
Chemical
c
Summer
41
12
89
43
6.1
12
°A blank indicates that the compound was not detected in the sample.
Steel and Coke Manufacturing
Samples of atmospheric suspended particulate were collected at
four urban residential sampling sites in the vicinity of an integrated
steel and coke manufacturing plant. Sampling sites were located 1/4
to 1-1/2 miles from the source in City B. Figure 9 shows the general
location of the sampling sites.
Air pollutants from the steel and coke processes come primarily
from two sources: (1) slot-type coke ovens and (2) oxygen-lanced open-
hearth furnaces. During the test period the coke ovens, with an aver-
age capacity of 18 tons per charge, were operated at the rate of 383
oven charges per day. Meanwhile 11 of the 14 oxygen-lanced open-
hearth furnaces (420 ton average size) were in operation. The open-
hearth furnaces did not utilize control equipment to reduce dust emis-
sions.
The BaP concentration during the spring test period in City B
approximates the average winter concentration of 102 United States
cities (Figure 10). Since samples were collected during the spring
Industrial Processes
31
-------
season, the contribution from the periodic use of residential coal fur-
naces would be included in the measured result. Residential-size coal
furnaces, as previously mentioned, are important sources of BaP
emissions.
Micrograms per 1000 cubic meters air
10 20 30 40 50
60
CARBON BLACK MFC WINTER
1961
SUMMER
CITY A 1961
STEEL AND COKE MFG SPRING
CITY B 1961
CHEMICAL INDUSTRY SUMMER
CITYC 1961
RESIDENTIAL AND SMALL WINTER
INDUSTRY COAL BURNING 1961
AREA 1 1
SUMMER
CITY D 1963
102 U.S. CITIES W'NTER
1959
9 LARGE U.S. CITIES" SUMMER
1958
Populations greater than
150,000 people 0
\
1
jjjJIJh
T-™ 1
m
dicrog
ubic n
dicrogr
us pen
i
3
•i
ams p
refers
ams p<
dedpa
erlOO
air
sr grar
rticulc
)
n
te
60 120 180 240 300 360
Micrograms per gram suspended participate
Figure 10. Comparison of atmospheric benzo (a) pyrene concentration in the United States.
The relative contribution of polynuclear hydrocarbons from the
coking operations and the steel operations in City B cannot be ascer-
tained by atmospheric sampling. No data were found in the published
literature on polynuclear hydrocarbon emissions from steel manufactur-
ing, but BaP concentrations ranging from 120 to 1700 micrograms per
gram particulate have been reported by Yanysheva 35 in discharge
gases from coke ovens in the U. S. S. R. These samples were aspirated
from the upper areas of the coke oven.
Slot-type coke ovens are normally equipped with a chemical
recovery system, and polynuclear hydrocarbon emissions result mainly
from gas leakage. Therefore, even though high BaP concentrations
have been reported in the particulates from coke ovens, the use of
chemical recovery systems on the coke ovens operating in City B
unquestionably restricted emissions of BaP to the atmosphere.
Higher polynuclear hydrocarbon emissions would be expected
from the now-obsolete beehive coke ovens. Since production by this
method amounted to only 6 percent of the total United States coke pro-
duction in 1960, 36 no attempt was made to sample a beehive oven.
32
POLYNUCLEAR HYDROCARBONS
-------
Chemical Manufacturing Complex
Atmospheric suspended particulate samples were collected at
five urban residential sampling sites within a chemical industry complex
in City C (Figure 9). This chemical complex produces graphite prod-
ucts, metallurgical products, inorganic acids and alkalies, and many
organic compounds including organic polymers.
Concentrations of polynuclear hydrocarbons in the atmospheric
particulate samples, which were taken during the summer, are sum-
marized in Tables 14 and 15. The BaP concentrations on a volume
basis and on a weight basis are only 80 percent and 70 percent higher,
respectively, than the average summer concentrations ' for nine larger
United States cities (population greater than 150, 000). On this basis,
benzo(a)pyrene emissions to the atmosphere from such a chemical
industry complex do not appear to be unusually high.
MOTOR VEHICLES
Eight automobiles and four trucks, representing two popular
vehicle makes, were tested. To avoid obscuration of any relationship
between emissions and the combined effects of age and mileage, auto-
mobiles of a given make were selected with the same type of engine:
vehicles of Make A were powered by in-line 6-cylinder engines; those
of Make B, by V-8 engines. All trucks tested were powered by in-line
6-cylinder engines. All automobiles were equipped with automatic
transmissions and all trucks with standard transmissions. This choice
was a compromise in the attempt both to represent typical usage and to
exclude the influence of transmission type in comparisons of emissions
from individual passenger cars and individual trucks. Each vehicle was
carefully checked to ascertain that the mileage on the odometer was
correct and that no major engine work had been done. Vehicle statistics
and operating data are given in Table 16.
After a brief warmup to give a "hot start," all vehicles traversed
the same 11. 8-mile route, which consists of a realistic composite of
business, arterial, and rapid-transit driving. Average run times were
31. 9 and 34. 4 minutes for the automobiles and trucks, respectively, at
average speeds of 22. 2 and 20. 6 mph. Trucks were loaded with barrels
of water to a weight representing 50 percent of rated payload capacity.
All vehicles burned the same regular-grade fuel having medium aro-
matic content of 25 percent.
Emission data for polynuclear hydrocarbons are given in Table 17.
The average BaP emission for the eight automobiles tested equals 11
micrograms per vehicle mile traveled. The average emission rate for
Make-B automobiles (V-8 engines) was 14 micrograms per mile; the
average rate for Make-A automobiles (6-cylinder engines) was 8.6 (see
Table 17). The higher total emissions for Make B are expected in view
of the larger engine displacements, but the average emission rate is
also higher on the basis of micrograms of BaP per gallon of fuel. In
Motor Vehicles 33
-------
Table 16. VEHICLE STATISTICS AND OPERATION DATA
Sample
No.
AE-52
46
47
54
49
60
61
57
58
59
50
56
67
65
68
62
63
Vehicle
l/l
a>
_Q
o
E
£
ID
<
_¥
u
3
H
<
a>
-x
0
CO
-------
Table 17. POLYNUCLEAR HYDROCARBON EMISSION SUMMARY: MOTOR VEHICLES
Sample
No.
AE-52
46
47
54
49
60
61
57
58
59
50
56
67
65
68
62
63
Vehicle
LO
LU
_l
ff>
o
t—
<
LO
^
U
r>
a:
I—
<
ID
_*
D
ca
0)
_*
D
<
tt>
-X
0
S
CO
a>
_i:
D
Year
1962
1962
1959
1956
Mileage
19,000
26,000
49,000
58,000
4-car average
1964
1962
1959
1957
14,000
19,000
53,000
67,000
4-car average
1963
1956
17,000
50,000
2-truck average
1964
1963
6,000
17,000
2-truck average
Group 2
Benzene-
soluble
organ ics
gm/mi le
0.175
0.120
0.108
0.072
0.511
0.218
0.0956
0.1098
0.0662
0.0597
0.0566
0.1112
0.0633
0.0703
0.077
0.618
0.348
0.159
0.243
0.233
0.199
BaP
/ig/gm
eisola
32
35
27
55
42
40
e
e
160
88
66
94
530
>32
210
>120
120
52
27
80
*g/galb
91
72
43
62
380
147
60f
60f
137
80
49
162
470
190
>40
1450
>750
216
149
68
160
A1560
70,000
>36,000
4,700
2,400
BaP
P
BeP
Per
B(ghi)P
Anth
Cor
Group 2
A
Phen
Fluor
micrograms per vehicle mile
5.6
4.2
2.9
3.9
21.5
8.6
t
10.6
5.3
3.7
10.5
33.5
14
>2.5
130
>66
19.2
12.6
6.3
14.4
81
70
12.9
27
119
67
76
67
142
125
58
103
341
156
410
1500
960
440
640
600
530
9.5
8.1
4.7
8.6
23.5
12.0
e
13.9
9.6
6.3
17.8
31.6
>3.5
105
>54
39
48
42
42
0.28
0.78
0.34
0.57
1.38
0.70
d
d
1.72
0.78
0.54
1.89
3.54
1.7
0.84
20
10
2.55
1.02
1.12
1.81
26
35
34
14.3
77
38
6.7
9.4
65
49
28
41
144
60
94
480
290
92
153
94
108
2.30
0.64
0.33
0.30
3.17
1.56
d
d
0.36
0.37
d
0.68
4.56
1.37
d
118
59
d
d
d
d
9.6
10.7
17.2
4.1
32.2
15.0
7.2
7.7
19.9
18.5
8.5
11.1
63.9
25
61
240
150
38
102
61
60
5.8
3.6
3.9
d
d
2.4
1.3/
l.O/
7.6
5.7
3.6
11.1
12.7
7.7
10.0
270
140
23.0
13.6
7.0
16.7
27
46
4.4
d
10.3
53
36
92
32
8.5
49
75
53
260
1030
650
340
290
290
320
39
39
6.7
39
102
51
42
32
67
65
32
76
223
98
220
980
600
310
440
330
350
o
I
fD
GO
aMicrograms per gram of benzene-soluble organics.
'•'Micrograms per gallon of fuel input.
cMicrograms per 1000 cubic meters of dry exhaust at 68°F and 1 atmosphere.
"Comnound not deterted in snmole.
CO
Ol
Micrograms p'~. ,- —« _„„,_ ,,,~._.~
Compound not detected in sample.
Interference prevented determination.
Estimate based on average of pyrene to BaP ratios
for tests 57, 58, and 59.
-------
Nearly every sample contained all of the polynuclear hydrocarbons
for which analyses are reported, and the emission trends in general
followed those reported for BaP. In addition, the compounds benz(a)-
anthracene and chrysene were detected. Pyrene was present in the
greatest quantities; the average ratios of pyrene to BaP were 9. 4 and
12. 5 for the Make-A and Make-B automobiles and more than 90 and 48
for Make-A and Make-B trucks, respectively. Ratios of BaP to benzo-
(ghi)perylene and BaP to coronene averaged approximately 0. 2 and 0. 6
for both makes of automobiles. These values are consistent with ratios
reported earlier by Sawicki: 8 BaP to benzo(ghi)perylene, less than
0. 6; and BaP to coronene, less than 1. 0.
Two sets of preliminary tests yielded less substantial, but still
comparable data. The first series of measurements was designed to
determine which modes of operation of an automobile produced the
greatest quantities of polynuclear hydrocarbons. A portion of the
exhaust gas was sampled from an automobile having a 6-cylinder engine,
mounted on a chassis dynamometer. Tests were made at constant-
speed conditions of 20-mph cruise, 40-mph cruise, 20-mph decelera-
tion, 40-mph deceleration, idle, and 20-mph acceleration. On the basis
of micrograms per vehicle-mile, the 20-mph acceleration produced the
highest BaP emission rate, 14 micrograms per mile.
The second series of preliminary measurements consisted of road
tests similar to those described earlier. Total exhaust flow was sampled
from three automobiles: two with V-8 engines (283 cubic inches, 5600
miles and 292 cubic inches, 32, 000 miles). Emissions of BaP ranged
from an average of 5. 3 micrograms per mile for the V-8 engines to 77
micrograms per mile for the 6-cylinder engine.
reports an estimated BaP emission rate of 49 micro-
grams per mile* determined by simultaneous particulate sampling and
measurements of ventilation air flow and traffic flow in the Sumner
Tunnel in Boston.
Begeman39 reports a BaP emission rate of 9. 6 micrograms per
minute from a dynamometer-mounted V-8, 364-cubic-inch gasoline
engine operated on a simulated city-driving cycle. At the average cycle
speed of 23 miles per hour, 39 the reported emission rate equals 25
micrograms per mile. Samples taken over successive mileage inter-
vals showed the possibility of increasing BaP emissions. 39, 40, 41
BaP Emission Rate,
Mileage Interval ug/min _ ug/milea
8,000 12,000 9.6 25b
19,300 25,500 6.2 16
25,500 29,000 9.0 24
29, 000 33, 000 27C 740
a Calculation based on 23-mph average cycle speed.
b Takes into account high BaP content of condenser collected tar.
c Malfunction of engine reported reference 40.
^Corrected value; emission rates for polynuclear hydrocarbons as given in this reference are in
error by a factor of 1 0.
36 POLYNUCLEAR HYDROCARBONS
-------
The higher aromatic content of the gasoline used in Begeman's tests
(36 percent versus 25 percent aromatic by fluorescence indicator
analysis) may have contributed to the slightly higher emission rates.
More recently, Hoffman 6 reported BaP emission rates at two
levels of oil consumption for the same dynamometer-mounted V-8
engine. BaP emission rates equivalent to 19 and 250 micrograms per
mile were determined for oil consumptions of 1 quart per 1600 miles
and 1 quart per 200 miles, respectively. The 13 times greater emis-
sion for the high-oil-consumption test suggests a partial explanation of
the high BaP emission rates for the older, higher-mile age vehicles.
SUMMARY AND CONCLUSIONS
A screening survey of likely sources of emissions of BaP and
other polynuclear hydrocarbons has produced some semi-quantitative
data on possible major contributors of these compounds to the atmos-
phere. The sources were evaluated either by direct sampling of the
effluent gases from the process or by atmospheric samples taken in
residential areas in the vicinity of the process. The survey was not
intended to establish statistically sound average emissions for every
source category; such a study would have required many times the
effort and funds expended. Enough emission data are available, how-
ever, to reveal the probable major sources, when annual consumption
or production figures are considered. Table 18 is presented for this
purpose. In interpreting the significance of this information, one should
keep in mind that the calculation of total emissions involved consider-
able estimating and a number of assumptions, with respect to both
emission rates and annual consumption or production figures. Also, the
aggregate emissions from a number of small sources not considered in
this study, although probably small, cannot be calculated.
The sources were classified in four major categories: heat gen-
eration, refuse burning, industrial processes, motor vehicles. This
study has revealed that each category must be considered a factor
affecting the atmospheric loading of BaP. Generally, the importance
of a particular category or source has been evaluated in terms of the
United States as a whole, but the importance of a particular source
relative to concentrations found in the atmosphere undoubtedly varies
considerably with locality; e. g., no coal is burned in Los Angeles
County, but that city has areas of exceptionally high traffic density.
Other factors may also influence the concentrations of BaP and other
polynuclear hydrocarbons found in the atmosphere, e. g., decomposition
or reaction with smog constituents in the atmosphere.
Heat Generation
Although each process surveyed undoubtedly contributes to the
atmospheric loading of BaP, the most important source of BaP is the
inefficient combustion of coal, typified by residential and small indus-
Summary 37
-------
Table 18. ESTIMATED ANNUAL BaP EMISSIONS FOR THE UNITED STATES
Source
Heat generation
Coal
Residential
i hand-stoked
ii underfeed
Commercial
Industrial
Electric generation
Oil
Gas
Total
Refuse burning
Incineration
Municipal
Commercial
Open Burning
Municipal refuse
Grass, leaves
Auto components
Total
Industries
Petroleum Catalytic Crack-
ing (catalyst regeneration)
FCC
i no CO boiler
ii with CO boiler
HCC
i no CO boi ler
ii with CO boiler
TCC (Air lift)
i no CO boiler
ii with CO boi ler
TCC (Bucket lift)
i no CO boi ler
ii with CO boiler
Asphalt road mix
Asphalt air blowing
Steel and coke manufacture
Chemical complex
Total
Motor vehicles
Gasoline
Automobi les
Trucks
Diesel
Total
Total (all sources tested)
Estimated BaP
emission
rate
(Mg/106Btu)
1,400,000
44,000
5,000
2,700
90
200
100
(/ig/ton)
5,300
310,000
310,000
310,000
26,000,000
Ug/bbl)
240
14
218,000
45
90,000
<45
31
<31
SOji.g/ton
<10,000,ug/ton
Estimated ann.
consumption
or production
(10'5Btu)
0.26
0.20
0.51
1.95
6.19
6.79
10.57
(106 tons)
18
14
14
14
0.20
(lO'bbl)
790
790
23.3
43.3
131
59
119
0
187,000 tons
4,400 tons
Estimated ann.
BaP emission,
tons
400
9.7
2.8
5.8
0.6
1.5
1.2
421.6
0.1
4.8
4.8
4.8
5.7
20.2
0.21
0.012
5.6
0.0024
13.0
O.0029
0.0041
0
0.000010
<0.000048
Atmospheric samples indicate that BaP emissions from
these processes are not extremely high
(^ig/gal)
170
>460
690
(10'° gal)
4.61
2.01
0.257
18.8
8.6
>10
2.0
>20.6
481
trial coal-fired furnaces. BaP concentrations were determined during
the winter and summer in a city in which the number of residential and
small-industry coal-burning units was unusually high (Figure 9, City D).
In Figure 10 these concentrations are compared with averages for United
States cities and with the concentrations measured in the vicinity of
processes surveyed by atmospheric sampling. This figure shows that
38
POLYNTJCLEAR HYDROCARBONS
-------
the atmospheric concentration during the winter for City D is consider-
ably higher than the other concentrations shown.
The efficient combustion of coal in modern industrial process
heating boilers and power plants and the combustion of fuel oil and
natural gas do not appear to be significant contributors.
Replacement of inefficient coal-fired furnaces would greatly
reduce emissions attributable to heat-generation.
Refuse Burning
In refuse burning, as in coal burning, efficiency of combustion
governs the emission of polynuclear compounds. Inefficient combustion
in small incinerators and open burning results in considerable forma-
tion of BaP and other polynuclear hydrocarbons, whereas good com-
bustion in municipal incinerators leads to very little BaP formation.
The burning of all refuse, especially that which has a high ratio
of hydrogen to carbon, in modern municipal incinerators or disposal by
noncombustion methods would almost eliminate emissions attributable
to refuse burning.
Industrial Processes
Results from direct and indirect sampling of industrial sources,
although not conclusive, indicate that the following are not major sources
of BaP: (1) an asphalt air-blowing process (pyrene emissions were
high), (2) an asphalt hot-road-mix plant, (3) a carbon-black manufac-
turing area, (4) a steel and coke manufacturing area, and (5) a chemical
industry complex.
Direct samples of the effluent from the catalyst regenerators of
petroleum catalytic cracking units indicate that Houdriflow and Thermo-
for (air-lift) units can be significant sources of BaP and other poly-
nuclear hydrocarbons among industrial sources. Emissions of these
compounds can be and frequently are reduced to negligible amounts
through the use of CO-waste heat boilers on individual "cat-cracker"
catalyst regenerators. Thermofor (bucket lift) and Fluid units incor-
porate catalyst regenerator designs that result in only minor emissions.
Considerable additional testing would be necessary to report contribu-
tions from catalyst regenerators with statistical assurance, as is the
case for all of the sources tested.
Motor Vehicles
Consideration of the emission rates determined for gasoline-
powered automobiles and trucks and the annual fuel usage leads one to
Summary 39
-------
believe that motor vehicles are a major contributor of BaP to the atmos-
phere. This is confirmed by Colucci, 42 who reports automotive BaP
contributions of 5 to 42 percent based on ratios of lead to BaP in exhaust
and in the atmosphere. Evidence indicates that the older, higher-mileage
vehicles and those with poorly adjusted engines yield the highest emis-
sion rates.
Limited data indicate higher emission rates for gasoline-powered
trucks. Diesel-powered trucks may also yield higher rates; 43, 44
however, diesel fuel usage by trucks and buses accounts for only about
4 percent of the total petroleum consumption for motor vehicles. The
over-all contribution from trucks and buses possibly exceeds that from
automobiles, even though the total fuel usage for this category is about
half that for automobiles.
Control systems applied to automobiles and trucks for the purpose
of reducing emissions of total gaseous hydrocarbons should reduce
emissions of BaP and other polynuclear hydrocarbons, but no data are
available to confirm this.
40 POLYNUCLEAR HYDROCARBONS
-------
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44 POLYNUCLEAR HYDROCARBONS
-------
BIBLIOGRAPHIC: Hangebrauck, R. P., D. J. von
Lehmden, and J. E. Meeker. Sources of poly-
nuclear hydrocarbons in the atmosphere. PHS
Publ. No. 999-AP-33. 1967. 44pp.
ABSTRACT: Rates of emissions of polynuclear
hydrocarbons were measured at several sources
considered likely to produce such emissions.
The sources included heat generation by combus-
tion of coal, oil, and gas; refuse burning; indus-
trial processes; and motor vehicles. The annual
emissions of benzo(a)pyrene in the United States
were estimated for each of the sources surveyed,
to provide a rough gauge of the importance of
each source. Small, inefficient residential coal-
fired furnaces appear to be a prime source of
polynuclear hydrocarbons; other sources may be
of local importance. Production of polynuclear
hydrocarbons was generally associated with con-
ditions of incomplete combustion.
BIBLIOGRAPHIC: Hangebrauck, R. P. , D. J. von
Lehmden, and J. E. Meeker. Sources of poly-
nuclear hydrocarbons in the atmosphere. PHS
Publ. No. 999-AP-33. 1967. 44pp.
ABSTRACT: Rates of emissions of polynuclear
hydrocarbons were measured at several sources
considered likely to produce such emissions.
The sources included heat generation by combus-
tion of coal, oil, and gas; refuse burning; indus-
trial processes; and motor vehicles. The annual
emissions of benzo(a)pyrene in the United States
were estimated for each of the sources surveyed,
to provide a rough gauge of the importance of
each source. Small, inefficient residential coal-
fired furnaces appear to be a prime source of
polynuclear hydrocarbons; other sources may be
of local importance. Production of polynuclear
hydrocarbons was generally associated with con-
ditions of incomplete combustion.
ACCESSION NO.
KEY WORDS:
Air Pollution
Polynuclear
Hydrocarbons
Emissions
Sources
Combustion
Refuse Burning
Industrial
Processes
Motor Vehicle
ACCESSION NO.
KEY WORDS:
Air Pollution
Polynuclear
Hydrocarbons
Emissions
Sources
Combustion
Refuse Burning
Industrial
Processes
Motor Vehicle
------- |