Fine particle and gaseous emission rates from residential wood combustion

Article abstract of DOI:10.1021/es9909632

Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning-communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter(<2.5 μm) and 5-22 g/kg volatile organic compounds were observed. Samples were collected using a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and se mivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C₈- C₂₀), canister (C₂-C₁₂), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and forts were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography. Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter (<2.5 μm) and 5-22 g/kg volatile organic compounds were observed. Samples were collected using a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and semivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C₈-C₂₀), canister (C₂-C₁₂), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence, and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and ions were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography.

Full text of DOI:10.1021/es9909632

Environ. Sci. Technol. 2000, 34, 2080-2091
Previous studies on the organic composition of wood
Fine Particle and Gaseous Emission
Rates from Residential Wood
Combustion
combustion products have focused predominately on the
emissions of polycyclic aromatic hydrocarbons (PAHs) due
to public health concerns. Some PAHs, such as benzo[a]-
pyrene, are known carcinogens (7), and Watts et al. (8) showed
that ambient air mutagenicity and the concentration of PAHs
were positively correlated with wood smoke-impacted areas.
Wood combustion has been estimated to account for more
emissions of PAHs than any other source (9).
J A C O B D . M C D O N A L D , †
B A R B A R A Z I E L I N S K A , * E R I C M . F U J I T A ,
J O H N C . S A G E B I E L ,
J U D I T H C . C H O W , A N D J O H N G . W A T S O N
Other wood combustion emissions studies have focused
on the identification of compounds that distinguish wood-
burning contributions from those of other sources. Elements,
ions, nitrate, sulfate, ammonia, and total organic (OC) and
elemental carbon (EC) are the most commonly used chemical
species in past source apportionment studies. Within these
species, contributions from vegetative burning, meat cooking,
and other sources are based upon the relative abundance’s
of water-soluble potassium, chloride, sulfate, OC, and EC in
source and ambient samples. Similarities between meat-
cooking and wood-burning constituents, as well as a com-
monality of EC+OC with those of motor vehicle exhaust,
have resulted in large uncertainties in source contribution
estimates (10, 11). Recent receptor modeling studies (3, 11)
that have included measurement of organic compounds in
addition to the more commonly measured chemical species
have improved estimation of source contributions with
respect to carbonaceous particles.
In this study, we measured more than 350 chemical
species, including volatile and semivolatile organics from C2
to C20, particle-phase organics such as PAHs, methoxylated
phenols, organic and elemental carbon, inorganic species,
elements, and carbon-14. Fuels, appliances, and burning
conditions were typical of residential wood combustion
communities such as Denver, CO, and Reno, NV. Fuels and
appliances included softwoods (gymnosperms), hardwoods
(angiosperms), and synthetic logs in a fireplace as well as
hardwoods burned in a wood stove. The objective of our
study was to quantify emission rates of compounds, or classes
of compounds, that may further improve assessment of
source apportionment relative to estimates developed from
previous studies. The ultimate goal of our study was also to
increase the knowledge base of air toxics that are emitted
from the combustion of wood during residential heating.
The source profiles derived from these data were applied to
the ambient fine particle source apportionment during the
1997 Northern Front Range Air Quality Study (NFRAQS) (11).
These source measurements are compared to the emission
rates developed from previous studies.
Desert Research Institute, 2215 Raggio Parkway,
Reno, Nevada 89512
Residential wood combustion emissions were analyzed to
determine emission rates and to develop chemical
emissions profiles that represent the appliances and
woods typically used in wood-burning communities. Over
350 elements, inorganic compounds, and organic compounds
were quantified. A range of 4-9 g/kg dry fuel of particulate
matter (<2.5 µm) and 5-22 g/kg volatile organic compounds
were observed. Samples were collected using a dilution
stack sampler equipped with a 2.5-µm particle selective
cyclone. Emissions were diluted 20-70 times, cooled to
ambient temperature, and allowed 80 s for condensation
prior to collection. Wood type, wood moisture, burn rate, and
fuel load were varied for different experiments. Fine
particle and semivolatile organic compounds were collected
on filter/PUF/XAD/PUF cartridges. Inorganic samples and
mass were collected on Teflon and quartz filters. Volatile
organic carbon compounds were trapped with Tenax (C -
8
C ), canister (C -C ), and 2,4-dinitrophenylhydrazine
20
2
12
impregnated cartridges (carbonyl compounds). Analysis of
particle and semivolatile organic species was conducted
by gas chromatography/mass spectrometry. Teflon filters were
analyzed for mass by gravimetry, trace elements were
analyzed by X-ray fluorescence, and ammonium was analyzed
by automated colorimetry. Quartz filters were analyzed
for organic and elemental carbon by thermal/optical
reflectance, and ions were analyzed by ion chromatography.
Select quartz filters were analyzed by accelerator mass
spectrometry for carbon-12 and carbon-14 abundance.
Canister and Tenax samples were analyzed by gas
chromatography with a flame ionization detector, and
carbonyl compounds were analyzed by high-performance
liquid chromatography.
Experimental Methods
Sam pling. Wood combustion emissions have been shown
in previous studies to be highly variable and dependent on
many factors related to burn conditions, fuels, and appliances
(6, 9, 12-14). Some of the most important factors that have
been shown in previous studies to affect these emission rates
and compositions are type of appliance [wood stove (catalytic
or conventional) versus fireplace], burn rate (related to
amount of wood being burned and stove ventilation), type
of wood [hardwood (angiosperm) versus softwood (gym-
nosperm)], configuration (grate versus no grate), and mois-
ture content (high moisture if greater than 20% wet weight).
An effort was made during the current study to address many
of these parameters by including them in the tests conducted
shown in Table 1. There were 19 individual wood combustion
tests made (Table 1), including three replicates of pine burned
in a fireplace, three replicates of dry oak burned in a wood
Introduction
Residential wood combustion (RWC) contributes to the
ambient concentration of fine (PM2.5) particulate matter (1-
3) and volatile organic compounds (VOCs) (4), especially in
residential neighborhoods during winter. Using 1997 emis-
sion inventory data, annual emissions from wood stoves in
the United States are estimated to be composed of 368 000
tons of PM10 and 527 000 tons of VOCs (5). In residential
areas where wood is the predominant heating fuel, wood
stoves have been shown to contribute as much as 80% of the
ambient fine particle concentrations during winter (6).
* Corresponding author e-mail: barbz@dri.edu, fax: (775)674-
7008.
† Current address: Lovelace Respiratory Research Institute, Al-
buquerque, NM 87185.
9
2 0 8 0 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 11, 2000
10.1021/es9909632 CCC: $19.00
2000 Am erican Chem ical Society
Published on Web 04/21/2000

TABLE 1. Wood Combustion Test Conditions and Emission Rates for Carbon Monixide, Total Volatile Organic Carbon (VOC), and
Fine Particulate (<2.5 mm) Mass (PM)
used in profilea
target
burn
fuel
av
fuel
SVOC/
type of
wood
fuel burn rate burned firebox moist.
CO
VOC
PM
sample PMb
VOC
appliance
fuel
grate load rate (kg/h)c (kg) T (°C) (% wet) (g/kg)d (g/kg)d (g/kg)d
FS01
FS02
FS03
FS04
yes
yes
yes
no
yes fireplace
no fireplace
Ponderosa pine
Ponderosa pine
Ponderosa pine
pinion pine
pinion pine
m ixed hardwoods hardwood no
softwood yes naf na
2.6
3.2
2.8
2.7
3.2
3.8
3.0
2.2
2.2
2.5
1.3
3.4
10.9 352.4
14.1 338.9
13.1 298.6
12.5 346.7
14.7 346.7
14.3 266.9
10.7 404.2
10.0 335.0
9.2 333.7
12.5 316.9
10.0
8.9
9.5
e
e
e
e
e
e
e
e
e
e
e
5.6
e
5.8
4.9
4.7
9.0
2.9
4.2
5.5
6.6
8.0
6.4
8.3
6.1
2.5
2.3
3.6
4.4
e
softwood yes na
softwood yes na
na
na
na
na
na
na
na
na
na
na
yes fireplace
yes fireplace
yes fireplace
yes fireplace
yes fireplace
yes fireplace
yes fireplace
yes fireplace
yes fireplace
5.8
5.1
7.5
8.1
7.9
14.5
11.8
7.0
1.4
e
softwood no
softwood yes na
na
m ixed hardwoods hardwood yes na
oak hardwood yes na
m ixed hardwoods hardwood yes na
na
8.1
FS05
no
11.4
13.1
13.3
14.9
18.1
18.2
FH01
FH02
FH03
FH04
FH05
FSY1
WH01
WH02
WH03
WH04
WH05
WH06
WH07
WH08
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
yes
yes
no
oak
synthetic log
hardwood yes na
synthetic yes na
2.8 223.8 na
no
no
wood stove m ixed hardwoods hardwood na
wood stove m ixed hardwoods hardwood na
high low
low high 6.2
21.7 405.6
11.7 519.3
12.8 423.5
20.7 398.0
21.9 402.9
21.5 396.6
22.5 474.7
9.0 135.8
14.1 178.6
7.6 102.7
6.5 124.9 14.2
6.5 104.8 15.2
8.5 131.9 13.6
15.2 131.9 55.3
15.5 120.9 36.8
e
6.2
yes wood stove m ixed hardwoods hardwood na
low low
high low
high low
high low
high low
high low
4.4
3.9
4.1
3.7
5.6
3.3
no
wood stove oak
hardwood na
hardwood na
hardwood na
hardwood na
hardwood na
yes wood stove oak
yes wood stove oak
yes wood stove oak
7.2
e
no
wood stove oak
21.5
e
a
All sam ples collected are shown in this table. Not all of these sam ples were used to create the com posite em ission rate profiles shown in
b
c
d
Table 2. SVOC/PM, sem ivolatile and particulate chem ical species m easured. Burn rate for wood com bustion is in dry kg/h. Em ission rate
calculated as g of pollutant/dry kg of fuel. No data available. f na, not applicable.
e
stove, and two replicates of high moisture oak burned in the
wood stove. The “high” moisture samples used are actually
lower moisture levels than recommended by the EPA Federal
Register (15) for conducting high moisture tests (20% wet
weight). These woods were desiccated by the dry climate in
Reno.
pressure transducer. Stack gas and humidity were not
measured, so default values of 19% oxygen, 1.8% carbon
dioxide, and 2% moisture by volume were used to convert
the differential pressure readouts from the pitot into veloci-
ties. These default values were obtained by Omni Environ-
mental Services from fireplace tests using the same model
Heatilator appliance that we used (16). Stack velocities
measured were comparable to numbers obtained by previous
tests conducted by Omni Environmental using the Heatilator
appliance (16). Stack velocities for the wood stove tests were
considerably less than those of the fireplace tests, and they
were below the measurable range of the pitot tube. Wood
stove stack velocity was calculated based on a model
developed for the U.S. EPA (15). The model is based on a
carbon stoichiometric relationship between carbon mon-
oxide, carbon dioxide, and the fuel consumption. Flue gas
samples were collected using an EPA Method 5H sampling
train. Details of this system are explained elsewhere (15).
Percent oxygen was measured electrochemically with a
Teledyne model 920 gas analyzer. Percent carbon dioxide
and carbon monoxide were both measured by infrared
spectrometry with an NDIR model 702D gas analyzer. A three-
point calibration with authentic gas standards was conducted
before stove tests. Pre- and post-span checks were conducted
on the analyzers to ensure analysis accuracy. The details
about these model calculations, and the assumptions therein,
can be found in the Federal Register (15).
A dilution stack sampler was built at DRI in order to collect
emissions during the wood combustion source tests. The
dilution sampler is a slightly modified version of the model
built and described by Hildemann et al. (17). Modifications
include improvements in portability and a longer mixing
chamber (17 effective diameters as compared to 10) that
provides more mixing time to ensure uniform sample
distribution. Emissions were withdrawn from the fireplace
or wood stove exhaust 8 ft above the bottom of the appliance
through a 10 ft by 0.5 in. heated stainless steel line. Sample
line flows ranged between 20 and 30 L/ min, and flow was
measured with a calibrated venturi meter purchased from
Lambda Square, Inc. (Bay Shore, NY). Emissions were drawn
into the dilution sampler, where they were mixed under
turbulent conditions with ambient air that was filtered
through a high-efficiency particulate air (HEPA) filter (to
Wood combustion tests were conducted at Desert Re-
search Institute (DRI) in Reno, NV, using wood samples
obtained from Denver, CO. Fireplace tests were conducted
in a Heatilator model E36 fireplace (with a model GR4 grate).
Wood stove tests were conducted with a noncatalytic
Pineridge appliance. Each appliance was placed in the center
of a shed with a 18 ft by 8 in. i.d. stainless steel exhaust flue
extended through the center of the roof. Wood types burned
in the fireplace included Ponderosa pine, pinion pine,
Missouri oak, scrub oak, mixed hardwood (cottonwood, birch,
aspen), and synthetic log. Fires were started with black print
newspaper. Kindling was the same species used as the fuel
for every test. The weight of the fuel, and therefore the burn
rate, was monitored continuously throughout all of the tests
using a Digimatex scale. Wood moisture content was
measured with a Delmhorst meter.
A three test-fuel charge was used for the fireplace tests,
with two additions after the initial test charge. Addition of
fuel occurred when one-third of the weight of the preceding
test charge was reached. The fuel-loading density was
maintained at 7.0 lb of wood/ cf. firebox area (112.1 kg/ m3)
for all fireplace tests. Wood stove tests were conducted by
igniting the fire, adding a 5-7 lb warm-up load, loading the
desired fuel load [“high” and “low”, i.e., 10 and 3 lbs of wood/
cf. firebox area (160.2 and 48.1 kg/ m3)], and changing the air
intake with the adjustable aperture on the face of the stove
(high air, open 8 mm; low air, open 1 mm). The synthetic log
test was conducted by placing one Duraflame log on the
grate in the fireplace, lighting it, and letting it burn. Wood
tests were terminated when 90% of the final test charge weight
had been burned. Using this termination point, the smol-
dering condition characterized by a lower temperature burn
with a lack of flame makes up approximately 20% of the
fireplace burn cycle and approximately 35-40% of the wood
stove tests.
The stack velocity for the fireplace tests was measured
with an S-type pitot tube connected to a DP41-E Omega
9
VOL. 34, NO. 11, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 2 0 8 1

remove particulate matter) and an activated carbon bed (to
remove gas-phase organics) prior to entering the chamber.
Fireplace emissions were diluted 20-40 times, and wood
stove emissions were diluted 50-70 times. To assess the
contribution of background chemicals to our wood combus-
tion samples, system blanks were collected from dilution air
flowing through the system at 1200 L/ min with the sample
inlet capped off. The background concentrations for all
species ranged from approximately 50 to 500 times less than
the wood combustion samples. Most of the analytes in the
blanks were at or below the detection limit and thus were
not subtracted from the wood combustion samples.
Samples were drawn through Bendix 240 cyclones located
inside the dilution sampler at 113 L/ min to remove particles
larger than 2.5 µm and then collected on (a) Teflon-
impregnated glass fiber filters (TIGF) followed by PUF/ XAD/
PUF cartridges for semivolatile/ particle organics; (b) Teflon
membrane filters for mass and elemental analysis; (c) quartz
fiber filters for ions, carbon, and C-14 analysis; (d) stainless
steel canisters for C2-C12 volatile organic compound (VOC)
analysis; (e) Tenax-TA cartridges for C8-C20 hydrocarbon
analysis; and (f) C18 Sep-Pak (Waters, Inc.) cartridges
impregnated with 2,4-dinitrophenylhydrazine (DNPH) for
the analysis of carbonyl compounds. These collection
methods are described in detail elsewhere by Zielinska et al.
(18, 19).
Analysis Methods. Laboratory methods are described in
detail elsewhere (18-20). Canister and Tenax-TA samples
were analyzed for compound identification by high-resolu-
tion gas chromatographic separation with Fourier transform
infrared/ mass spectrometric detection (Hewlett-Packard GC/
IRD/ MSD, 5890/ 5965B/ 5970). High-resolution gas chroma-
tography with flame ionization detection (GC/ FID, Hewlett-
Packard 5890 series II) was used for quantitative determina-
tion.
Oxygenated hydrocarbons measured with the canister and
Tenax methods were quantified by GC/ FID using relative
response factors (also called effective carbon numbers, ECNs).
The ECNs were developed for methanol, ethanol, ethyl
acetate, furan, 2-furaldehyde, hexenal, and guaiacol using
the method of Scanlon and Willis (21). Compounds that were
not experimentally determined were calculated from their
molecular structures using the method developed by Jor-
gensen et al. (22). The ECN correction factor will provide a
lower limit for the levels of oxygenated compounds quantified
as a result of losses of these compounds that occur during
analysis. Potential areas for loss of oxygenated compounds
during analysis include poorer penetration through the
injection system or column when compared to nonpolar
compounds. Loss may also occur from oxygenated com-
pounds “sticking” to the walls of the canister during sampling
and analysis (23). The degree of oxygenated compound loss
from sampling and analysis was not determined during this
study.
response of the deuterated internal standard that most closely
matches its retention time and stability. To correct for the
varying response factors encountered for compounds with
different molecular structures, calibrations were created using
authentic standards purchased from Aldrich Chemical Co.
(Milwaukee, WI) and the National Institute of Standards and
Technology (Gaithersburg, MD). Standards were injected for
all of the PAH reported here except 1,7-dimethylnaphthalene,
and the methoxylated phenols except ethylguaiacol and
ethylsyringol. The compounds that were analyzed without
authentic standards were quantified using the response
factors of standards with similar structures.
Teflon filters were weighed prior to and after sampling to
determine mass concentrations. These were analyzed for
trace elements by X-ray fluorescence (XRF). A 0.56-cm2 punch
from the prefired quartz fiber filters was analyzed for organic
and elemental carbon by the thermal/ optical reflectance
(TOR) method described by Chow et al. (24). Half of the
quartz filter was extracted in 10 mL of deionized water, and
the extract was analyzed for nitrate, sulfate, and chloride
ions by ion chromatography; for ammonia by indolphenol
automated colorimetry; and for water-soluble potassium by
atomic absorption spectrometry. Some of the quartz filters
were analyzed at the University of Arizona-NSF AMS Facility
by accelerator mass spectrometry for carbon-12 and carbon-
14 isotopic abundance. These methods are described else-
where (25). One-half of a quartz filter was submitted for 14C/
12C analysis of wood combustion experiments taken in the
fireplace for a hardwood, softwood, and synthetic log sample.
Results and Discussion
Particle and gaseous emission rates from wood burning are
heavily dependent on the chemical composition of the fuels
and the combustion conditions. The chemical composition
of wood and the combustion process have been described
previously (2, 4, 6, 9, 12, 26-34). The data presented here
show results of wood combustion tests conducted in both
a fireplace and a conventional (noncatalytic) wood stove.
Creation of Com posite Wood Com bustion Profiles. Since
the primary objective of this study was to develop source
profiles that represent major compositional differences in
wood combustion, data are presented here in composite
profiles corresponding to the major woods and appliances
tested. These composite profiles were created from the
emission profiles of the individual experiments shown in
Table 1 with the aid of a cluster analysis. Clustering is a
multivariate statistical technique of grouping data together
that share similar values. A hierarchical cluster using Ward’s
Method from the statistical analysis software JMP (35) was
utilized to exploit differences and similarities in the com-
position of individual wood combustion profiles (normalized
by weight fraction). Hierarchical cluster data are often
presented in a dendrogram in which similar data are
branched together in closer proximity than less similar data.
The cluster dendrogram shown in Figure 1 shows similarities/
differences between the emission profiles of softwoods
(FS01-FS04), hardwoods (FH01-FH03, FH05), and synthetic
logs (FSY1) burned in a fireplace as well as hardwoods burned
in a wood stove (WH01-WH05, WH07). The individual
profiles used in the cluster analysis are the same profiles that
are shown in Table 1 to be included in the profile develop-
ment. The major differences in profile composition observed
in this study can be attributed to the appliance used (wood
stove versus fireplace) and the type of wood (softwoods,
hardwoods, synthetic log). The compositional differences
observed that led to the pooling of these data into composite
profiles are discussed throughout the Results and Discussion
section.
Carbonyl compounds collected on DNPH cartridges (as
hydrazones) were eluted with 2 mL of HPLC grade acetonitrile
and analyzed by HPLC (Waters, Inc.) with UV detection at
360 nm (18).
Prior to extraction of filter/ PUF/ XAD/ PUF cartridges,
deuterated internal standards were added to each filter-
sorbent pair for PAH compounds ranging from naphthalene-
d8 to coronene-d12. PUF plugs were Soxhlet extracted
separately with 10% diethyl ether in hexane, and the filter-
XAD pairs were microwave extracted with dichloromethane.
The samples were analyzed by the EI (electron impact) GC/
MS technique, using a Hewlett-Packard 5890 GC interfaced
to a 5970B mass selective detector (MSD) operated in selective
ion monitoring (SIM) mode. Quantification of compounds
extracted from the filter/ PUF/ XAD/ PUF cartridge was con-
ducted by comparing the response of the analyte to the
The high moisture fireplace sample (FH05) was separated
from the other fireplace/ hardwood samples in Figure 1. This
9
2 0 8 2 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 11, 2000

FIGURE 1. Hierarchical clustering of wood combustion source samples including fireplace tests for hardwoods, softwoods, and a synthetic
log as well as wood stove tests with hardwoods.
sample was distinguished by its higher proportion of semi-
volatile organics as compared to tests FH01-FH03 and was
included in the fireplace/ hardwood composite. The wood
stove tests with low burn rates (WH02, WH03) were separated
from the cluster of wood stove tests with higher burn rates.
The low burn rate samples were distinguished by their higher
amounts of semivolatile organic compounds. While WH03
was included in the wood stove composite profile, WH02
was not included because of an incomplete data set. Within
the four composite profiles developed, the relative chemical
composition is similar. Emission rates, however, were effected
by both moisture content and burn rate. Differences in the
emission rates for total VOC and fine particle mass are shown
in Table 1 and discussed in a further section.
Table 2 shows average emission rates in mg of pollutant/
kg of dry fuel for both softwoods and hardwoods burned in
the fireplace, a synthetic log burned in the fireplace, and
hardwoods burned in the wood stove. These rates are
composite averages of the tests indicated in Table 1 and
Figure 1. As indicated in Table 1, not all of the tests conducted
are included in the composite profiles. Only tests where
complete data sets exist were included in the composites.
Measurement uncertainties used for composite source
profiles are the larger of the 1 σ standard deviations between
tests or the root mean square of the analytical measurement
uncertainties [SQRT ((replicate precision × analyte concen-
tration)2 + (analyte detection limit)2)]. Differences between
the individual tests are reflected in the profile uncertainties,
and the individual emission rates for each test are available
upon request.
Chem ical Com position of Wood Sm oke. Table 2 shows
an abbreviated list (full list available in the Supporting
Information or from the correspondence author) of the
emission rates of individual fine particulate and gaseous
species quantified during this study. A comparison of the
data to previous studies is also provided. A summary of the
emission rates for each respective chemical class is also shown
in Table 2. These major chemical classes are discussed below.
Fine Particle and Gaseous Emission Rates. Total fine
particle PM2.5 emissions rates for all wood combustion tests
are summarized in Table 1. The composite emission rates
were 5.1 g/ kg for softwoods burned in the fireplace, 5.7 g/ kg
for hardwoods in the fireplace, and 4.7 g/ kg for the wood
stove emissions. The synthetic log yielded emissions of 8.3
g/ kg. Varying the appliance, fuel, and burn conditions did
not seem to have a large effect on the amount of fine particle
emissions during this study.
The VOC emissions are defined here as any hydrocarbon,
including oxygenated, which are measured by the canister,
Tenax, or DNPH methods. For reporting the total VOC (Table
1, Table 2, Figure 2), the sum of all compounds measured
by the canister analysis was used to enable comparison to
previous VOC studies on wood combustion. Emission rates
for VOCs are shown in Table 1 for the individual tests and
in Table 2 for the composite profiles. The highest emission
rates are observed from burning hardwoods in the wood
stove (21.8 g/ kg), and the softwoods combusted in the
fireplace showed the lowest emission rates (5.8 g/ kg) among
nonsynthetic woods. The synthetic log emitted less VOC (1.2
g/ kg) than the woods. The higher VOC emissions from wood
stove as compared to fireplace can be attributed to higher
combustion temperatures and a longer burn cycle. Contrary
to the fine particle emission rates, moisture content had a
noticeable effect on the emission rates of VOCs. The high-
moisture wood stove tests yielded approximately 2-4 times
more VOC than the next highest wood combustion test (Table
1).
Data regarding the impact of residential wood combustion
VOC to ambient airsheds are currently sparse. Such data are
important due to the presence of many compounds that are
potentially toxic and/ or highly reactive in ambient air. To
estimate the contribution of some selected pollutants from
wood combustion in an area impacted by wood smoke,
emission inventory activity data for Washoe County (Reno),
NV, in 1998 were obtained. On the basis of these data and
the data obtained during the current study, it is estimated
that 18.7 tons of benzene, 6.0 tons of formaldehyde, and 3.9
tons of 1,3-butadiene were emitted from residential wood
combustion in Washoe County during 1998.
Carbon monoxide (CO) emissions, shown in Table 1 and
Table 2 for the wood stove tests, averaged 129 ( 25 g/ kg. CO
emissions factors from these tests are comparable to those
found in other emissions studies, as shown. Table 1 shows
that hardwoods combusted with a low fuel load and high
burn rate provided an enrichment in the carbon monoxide
emission rate (178.6 g/ kg).
Aliphatic and Olefin Hydrocarbons. Volatile and semiv-
olatile hydrocarbons from C2 to C20 were quantified during
9
VOL. 34, NO. 11, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 2 0 8 3

TABLE 2. Fine Particle and Gaseous Emission Rates from Softwood (Fireplace), Hardwood (Fireplace + Wood Stove), and Synthetic Logs (Fireplace)w
fireplace, softwood
fireplace, hardwood
mg/kg
wood stove, hardwood
synthetic
log (mg/kg)
method
mg/kg
median
median
mg/kg
median
other ref (mg/kg)
C2-C6 Hydrocarbons
539.85 ( 41.09
acetylene
alkanes
can
312.97 ( 11.67
na
na
1119.13 ( 59.04
na
nq
ethane
propane
n-butane
n-pentane
n-hexane
can
can
can
can
can
468.51 ( 17.47
107.43 ( 24.79
17.36 ( 11.9
8.69 ( 0.84
na
108.52
21.35
8.88
662.88 ( 181.79
167.84 ( 57.70
20.24 ( 19.60
11.85 ( 5.29
7.02 ( 3.77
na
157.08
23.42
8.83
1425.67 ( 977.85
155.06 ( 79.73
1.67 ( 3.34
13.12 ( 7.81
12.30 ( 7.47
na
158.27
0.00
14.12
14.19
nq
735(4)
180.73 ( 4.01
18.24 ( 0.81
7.90 ( 0.46
6.16 ( 0.35
331(13),j 45(13)k
55(13),j 6(13)k
6.01 ( 2.03
5.59
5.01
alkenes
ethene
propene
1-butene/isobutene
1,3-butadiene
1-pentene
1,3-pentadiene
1-hexene
can
can
can
can
can
can
can
can
715.05 ( 26.66
243.64 ( 49.35
84.13 ( 17.63
62.63 ( 12.71
10.33 ( 1.04
7.35 ( 4.28
na
1069.78 ( 319.90
346.20 ( 136.74
120.68 ( 50.68
94.67 ( 40.80
15.19 ( 8.11
na
2528.65 ( 424.92
667.97 ( 439.24
148.85 ( 72.71
196.58 ( 143.78
18.73 ( 11.64
0.00 ( 0.01
na
nq
2245(4)
230.51
79.29
59.47
10.42
5.79
11.03
29.39
295.86
101.07
73.51
10.63
9.84
10.77
35.05
589.47
159.29
158.38
18.98
0.00
19.26
80.90
30.38 ( 1.51
14.64 ( 0.99
8.48 ( 0.58
7.49 ( 0.58
0.64 ( 0.06
10.22 ( 0.58
0.93 ( 0.06
888(13),j 331(13)k
12.34 ( 7.36
11.15 ( 2.69
26.84 ( 9.15
18.55 ( 12.86
27.60 ( 21.91
19.57 ( 19.11
127.88 ( 115.59
1,3-cyclopentadiene
C7-C20 Hydrocarbons
alkanes
n-heptane
n-octane
n-nonane
n-decane
can
can
can
can
can
can
Tenax
Tenax
Tenax
Tenax
Tenax
Tenax
Tenax
Tenax
3.71 ( 0.26
2.54 ( 0.71
1.09 ( 0.26
0.92 ( 0.26
2.27 ( 0.93
0.93 ( 0.35
1.60 ( 2.27
2.16 ( 1.19
4.71 ( 1.05
0.73 ( 0.66
0.94 ( 0.71
1.14 ( 0.75
1.32 ( 0.74
1.04 ( 0.90
3.63
2.39
1.09
0.84
2.18
1.02
na
na
na
na
na
5.36 ( 3.23
3.90 ( 3.00
2.31 ( 1.90
2.10 ( 1.94
2.92 ( 2.57
2.54 ( 2.47
1.45 ( 2.91
0.00 ( 0.08
14.41 ( 12.49
1.91 ( 2.02
0.86 ( 0.75
1.33 ( 1.18
1.89 ( 1.08
0.60 ( 0.60
3.51
1.94
1.50
1.78
4.59
3.19
0.00
0.00
13.14
1.36
0.58
0.83
2.22
0.49
4.60 ( 2.04
14.94 ( 21.78
5.13 ( 3.56
1.67 ( 0.71
1.29 ( 1.28
2.18 ( 1.96
0.40 ( 3.23
0.92 ( 1.85
1.82 ( 3.64
0.11 ( 0.25
0.11 ( 0.11
0.11 ( 0.30
0.12 ( 0.28
0.13 ( 0.15
5.16
5.57
4.27
1.82
1.16
2.17
0.09
0.14
0.19
0.08
0.05
0.06
0.10
0.09
5.00 ( 0.29
8.13 ( 1.05
0.00 ( 0.06
2.73 ( 0.17
1.86 ( 0.29
0.81 ( 0.23
0.51 ( 0.45
0.89 ( 0.49
1.64 ( 0.37
0.41 ( 0.38
0.06 ( 0.12
0.76 ( 0.32
0.46 ( 0.27
2.79 ( 1.73
n-undecane
n-dodecane
n-tridecane
n-tetradecane
n-pentadecanea
n-hexadecane
n-heptadecane
n-octadecane
n-nonadecane
n-eicosane
alkenes
na
na
na
8.8(2)l
21.7(2)l
1-heptene
1-octene
1-nonene
1-dodecene
can
can
can
can
3.22 ( 0.77
1.49 ( 0.52
0.49 ( 0.59
1.06 ( 0.85
3.09
1.35
0.41
0.78
5.15 ( 3.94
0.43 ( 0.59
0.50 ( 0.39
1.23 ( 1.06
2.85
0.00
0.44
0.91
6.70 ( 4.45
0.18 ( 0.35
0.00 ( 0.01
0.77 ( 0.72
6.92
0.00
0.00
0.63
3.20 ( 0.06
7.49 ( 0.12
1.22 ( 0.06
0.70 ( 0.12
Oxygenated
furans
furan
can
can
can
can
132.52 ( 38.02
127.63 ( 51.36
25.80 ( 13.44
2.71 ( 1.17
123.34
135.24
24.83
2.69
213.65 ( 162.75
209.86 ( 165.84
36.32 ( 37.29
2.31 ( 1.78
157.86
167.29
30.38
1.87
208.49 ( 100.44
261.93 ( 169.61
43.15 ( 22.83
2.89 ( 2.01
222.49
279.50
47.82
3.44
2.27 ( 0.17
3.89 ( 0.87
0.23 ( 0.06
0.70 ( 0.06
4.21 ( 3.39
225(13),j 133(13)k
1076(13),j 39(13)k
277(13),j 10(13)k
2-m ethylfuran
2,5-dim ethylfuran
2,4-dim ethylfuran
2-furaldehyde
ketones
b
Tenax
317.60 ( 258.17
na
445.33 ( 473.84
244.73
99.71 ( 80.13
na
790(32)
glyoxal
DNPH
can
can
can
can
424.32 ( 302.63
258.86 ( 69.74
45.63 ( 9.32
80.40 ( 15.47
52.20 ( 16.87
480.21
256.31
46.61
78.38
50.70
599.97 ( 470.71
426.10 ( 211.34
58.76 ( 34.38
138.84 ( 44.19
58.12 ( 43.68
573.12
274.37
54.58
133.28
51.52
172.68 ( 123.79
549.18 ( 463.84
174.59 ( 119.24
172.71 ( 96.68
80.27 ( 52.26
191.76
391.63
174.23
180.76
85.21
18.86 ( 6.54
106.66 ( 22.55
2.32 ( 0.52
acetone (+propanal)
3-buten-2-one
butanone
9.93 ( 0.87
335(13),j 35(13)k
3-m ethyl-3-buten-2-one
2.38 ( 1.22

TABLE II (Continued)
fireplace, softwood
fireplace, hardwood
mg/kg
wood stove, hardwood
synthetic
log (mg/kg)
method
mg/kg
median
median
mg/kg
median
other ref (mg/kg)
Oxygenated
alkanals
form aldehyde
acetaldehyde
proponal
butanal
pentanal
octanal
nonanal (+undecene)
alkenals
DNPH
DNPH
DNPH
can
can
can
113.32 ( 34.67
301.03 ( 89.75
80.22 ( 39.72
18.64 ( 1.26
6.81 ( 2.40
114.71
282.54
87.68
18.31
6.37
177.95 ( 53.03
164.51
425.01
139.44
26.54
4.56
245.58 ( 48.58
360.46 ( 161.75
96.44 ( 48.51
36.49 ( 26.56
13.05 ( 9.92
1.55 ( 1.12
261.87
415.94
99.91
36.29
12.05
1.42
35.95 ( 4.95
45.13 ( 4.39
18.88 ( 5.50
9.06 ( 0.70
6.74 ( 0.35
0.58 ( 0.12
0.64 ( 0.12
100-700(14)
30-600(14)
100-300(14)
450.43 ( 87.57
150.10 ( 82.55
22.48 ( 14.61
6.26 ( 3.96
8.87 ( 6.73
5.73
8.25
1.02 ( 0.82
1.12 ( 0.94
0.65
0.88
can
7.85 ( 5.07
2.27 ( 2.94
1.29
2.97(2)l
acrolein
butenal
alcohols
DNPH
can
46.90 ( 13.81
19.62 ( 6.64
45.84
18.13
91.23 ( 34.72
25.77 ( 14.42
81.94
28.58
45.54 ( 21.76
22.52 ( 22.18
49.58
17.42
18.21 ( 2.90
0.00 ( 0.06
20-103(14)q
m ethanol (+m ethyl form ate)
ethanol (+acn+acroelin)
other oxy com pds
ethyl acetate
acetophenone
phenolic com pds
phenol
can
can
949.97 ( 344.63
208.91 ( 49.74
0.00 ( 0.00
862.59
209.49
0.00
2.90
na
2905.05 ( 1181.01
145.38
0.00 ( 0.00
10.63 ( 3.25
56.63 ( 48.87
2624.75
256.59
0.00
8.83
53.56
3245.71 ( 2639.68
10525.75
2849.57
619.08
0.00
0.00 ( 0.06
114.38 ( 18.01
0.00 ( 0.00
4300(32)
110(32)
0.00 ( 0.00
can
Tenax
3.72 ( 4.49
1.17 ( 2.34
0.00
na
8.19 ( 0.06
64.95 ( 30.03
10.90 ( 4.95b
17.77 ( 8.07
Tenax
157.58 ( 39.92
na
246.81 ( 174.46
246.92
142.37 ( 36.97b
na
8.56 ( 2.17
guaiacols
guaiacol
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
77.30 ( 46.98
142.62 ( 58.96
27.95 ( 9.99
60.81
141.48
27.03
16.81
33.71
118.05 ( 21.65
76.10 ( 24.68
22.40 ( 6.33
27.50 ( 10.87
47.31 ( 14.01
128.07
70.90
21.75
24.80
46.96
21.69 ( 12.42
13.84 ( 8.10
4.04 ( 2.35
1.55 ( 1.03
2.96 ( 2.33
27.29
16.80
4.80
1.86
3.69
2.09 ( 0.28
3.20 ( 0.38
0.85 ( 0.07
0.87 ( 0.34
7.09 ( 1.18
180(32)
260(32)
4-m ethylguaiacol
4-ethylguaiacol
4-allylguaiacol
4-form ylguaiacol
syringols
syringol
4-m ethylsyringol
4-ethylsyringol
22.57 ( 15.33
43.19 ( 20.94
76(32)
29.3(2),m 2.0(2)n
F/P/X/P
F/P/X/P
F/P/X/P
1.57 ( 1.77
0.52 ( 0.22
1.75 ( 0.78
0.92
0.43
2.14
389.78 ( 132.08
244.28 ( 130.75
108.84 ( 55.98
405.20
244.03
138.47
45.69 ( 28.57
13.41 ( 9.26
5.19 ( 3.94
53.96
18.46
7.34
6.39 ( 0.47
3.42 ( 0.56
3.78 ( 0.69
1.1(2),m 10.8(2)n
Halgogenated
39.99 ( 15.14
151.84 ( 47.08
chlorom ethane
m ethylene chloride
can
can
27.67 ( 6.12
176.19 ( 38.56
26.90
159.41
42.47
172.74
21.06 ( 8.95
2.12 ( 1.88
20.49
2.05
20.27 ( 1.68
71.45 ( 4.82
Resin/Terpenoid Compounds
isoprene
can
can
can
Tenax
Tenax
Tenax
38.74 ( 14.63
53.59 ( 24.05
59.68 ( 54.19
189.59 ( 56.36
35.36 ( 8.71
34.53
54.65
48.77
na
na
na
27.04 ( 13.39
4.01 ( 4.39
6.50 ( 8.12
18.15 ( 27.13
2.89 ( 1.15
0.00 ( 0.09
24.80
43.25 ( 31.86
3.69 ( 2.55
16.56 ( 14.56
0.00 ( 0.01
0.06 ( 0.13
0.06 ( 0.06
35.71
4.10
15.37
0.00
0.00
0.07
4.36 ( 0.23
5.81 ( 1.51
10.34 ( 0.41
0.00 ( 0.12
0.37 ( 0.14
0.00 ( 0.12
R-pinene
3.38
2.81
7.03
3.23
0.00
â-pinene
3-carene
lim onene
sesquiterpene-e
53.86 ( 25.86
Volatile Aromatic Compounds
benzene
toluene
m +p-xylene
o-xylene
styrene (+heptanal)
indan + indene
indan
can
can
can
can
can
224.97 ( 40.25
130.62 ( 21.12
49.63 ( 16.95
16.12 ( 4.19
229.02
126.23
47.64
15.02
37.13
312.15 ( 83.14
141.50 ( 44.03
40.91 ( 12.22
19.15 ( 9.71
324.37
1189.68 ( 875.27
320.00 ( 223.60
71.78 ( 47.67
793.13
243.68
58.34
24.55
82.07
42.87 ( 2.90
20.16 ( 1.05
10.86 ( 1.10
7.09 ( 0.35
3.72 ( 0.35
988(13),j 951(13)k
373(13),j 241(13)k
138.52
39.56
15.35
37.67
27.28 ( 16.80
87(13),j 0(13)k
40.17 ( 13.15
34.51 ( 22.29
117.21 ( 91.48
Tenax
Tenax
0.12 ( 0.15
7.80 ( 7.77
0.08
6.23
0.13 ( 0.19
1.06 ( 0.64
0.00
0.97
0.49 ( 0.86
1.75 ( 1.69
0.09
1.36
0.29 ( 0.06
0.29 ( 0.35
indene

TABLE II (Continued)
fireplace, softwood
mg/kg
fireplace, hardwood
mg/kg median
wood stove, hardwood
synthetic
log (mg/kg)
method
median
mg/kg
median
other ref (mg/kg)
Gas-Phase PAH
naphthalene
2-m enaphthalene
1-m enaphthalene
biphenyl
acenaphthylene
acenaphthene
fluorene
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
21.42 ( 5.13
22.57
4.76
4.14
1.18
5.35
0.43
2.42
54.62 ( 18.32
12.90 ( 4.35
10.33 ( 3.66
2.47 ( 0.98
8.67 ( 3.65
0.89 ( 0.29
3.50 ( 1.08
60.86
15.55
12.71
2.63
8.18
0.77
28.06 ( 19.06
4.91 ( 3.33
4.07 ( 2.77
2.43 ( 1.80
5.19 ( 3.65
0.52 ( 0.37
1.66 ( 1.15
34.96
6.32
5.23
2.84
6.40
0.65
2.04
20.58 ( 4.93
2.03 ( 0.38
2.28 ( 0.41
7.92 ( 1.87
6.70 ( 1.24
0.23 ( 0.04
2.05 ( 0.31
39(4), 84(6)o
4.65 ( 0.84
4.02 ( 0.71
1.18 ( 0.28
4.97 ( 1.03
0.41 ( 0.06
2.15 ( 0.53
2(6),p 15(6)o
5(4), 1.1(6)o
2.1(6),p 6.7(6)o
3.09
Particle-Phase PAH
phenanthrene
1-m ethyl-
phenanthrene
1,7-dim ethyl-
phenanthrene
retenec
F/P/X/P
F/P/X/P
10.42 ( 2.74
2.30 ( 0.21
10.17
2.28
16.59 ( 4.80
17.62
1.61
7.35 ( 5.00
0.26 ( 0.27
9.12
0.26
7.62 ( 2.01
0.56 ( 0.05
5.8(56)q
1.42 ( 0.49
0.19(56)q
F/P/X/P
1.85 ( 0.17
1.86
1.09 ( 0.90
1.55
0.09 ( 0.06
0.12
0.62 ( 0.06
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
F/P/X/P
1.79 ( 0.30
1.61 ( 0.24
0.07 ( 0.04
0.10 ( 0.01
0.15 ( 0.03
2.50 ( 0.29
1.88 ( 0.29
0.31 ( 0.25
0.28 ( 0.04
0.51 ( 0.08
0.07 ( 0.06
0.03 ( 0.02
1.63
1.65
0.09
0.10
0.16
2.43
1.93
0.29
0.28
0.51
0.09
0.03
0.50 ( 0.22
3.39 ( 1.29
0.19 ( 0.11
0.25 ( 0.12
0.34 ( 0.19
3.76 ( 1.21
3.99 ( 1.47
0.45 ( 0.34
0.61 ( 0.31
1.05 ( 0.57
0.22 ( 0.13
0.09 ( 0.05
0.54
3.77
0.18
0.25
0.30
3.46
4.47
0.48
0.59
0.93
0.21
0.08
0.02 ( 0.01
1.49 ( 1.03
0.08 ( 0.06
0.14 ( 0.10
0.20 ( 0.14
1.43 ( 0.97
1.75 ( 1.21
0.56 ( 0.48
0.35 ( 0.25
0.66 ( 0.48
0.09 ( 0.06
0.03 ( 0.02
0.02
1.82
0.10
0.16
0.24
1.79
2.14
0.62
0.43
0.79
0.11
0.03
0.39 ( 0.04
2.99 ( 0.45
0.18 ( 0.02
0.26 ( 0.02
0.30 ( 0.04
1.57 ( 0.18
3.26 ( 0.50
0.53 ( 0.38
0.36 ( 0.05
0.94 ( 0.15
0.24 ( 0.04
0.09 ( 0.05
0.68(2)m
pyrene
2.6(9), 2.7(56)q
0.42(56)k
indeno[123-cd]pyrene
benzo[e]pyrene
benzo[a]pyrene
anthracene
fluoranthene
benz[a]anthracene
chrysene
benzo[b+j+k]fluorene
benzo[ghi]perylene
coronene
0.3(2), 6(4)
0.6(56),q 2(4)
0.82(56),q 3.1(6)r
1.24(2),m 2.6(9)
0.16(6),p 0.63(6)o
6(4), 0.26(6)p
1.32(2),m 1.1(2)l
2(4),1.3(9)
0.1(2),l 0.8-3(14)
Organic and Elemental Carbon
organic C
elem ental C
TOR
TOR
3007.28 ( 333.54
774.15 ( 69.67
3034.88
761.03
3579.95 ( 798.12
397.52 ( 117.67
3486.60
395.15
2821.09 ( 1770.64
356.33 ( 216.86
2861.28
311.89
1087.61 ( 108.75
6578.23 ( 474.97
2-20(14)
Inorganic Species
nitrate
sulfate
am m onium
IC
IC
CO
6.80 ( 1.42
10.20 ( 3.33
5.46 ( 1.58
6.48
8.90
5.12
9.94 ( 3.41
10.28
23.30
5.14
0.59 ( 3.83
26.64 ( 14.62
6.84 ( 8.32
0.09
26.59
3.31
2.24 ( 3.00
0.00 ( 2.98
9.44 ( 3.08
16.9(50),s 32.5(50)t
19.5(50),s 32.5(50)t
24.7(50),s 19.5(50)t
27.51 ( 15.11
5.05 ( 3.40
Elements
chloride
soluble potassium
sodium
IC
AA
XRF
7.54 ( 3.69
17.98 ( 7.38
1.38 ( 2.16
5.56
16.65
1.17
10.07 ( 6.19
67.40 ( 48.95
1.08 ( 2.46
7.79
49.77
0.32
5.71 ( 3.79
15.36 ( 11.85
1.95 ( 6.79
6.02
12.01
1.37
0.00 ( 2.98
1.42 ( 0.34
6.89 ( 2.51
3.4(55),u 1.2(55)v
61.1(50),s 114.4(50)t
12.2(50),s 2.6(50)t
Summary of Emission Rates by Chemical Classd
alkanes(C3-C6)
alkanes(C7-C12)
alkenes(C3-C6)
alkenes(C7-C12)
furans
carbonyls (C2-C9)
other oxy
can
can
can
can
can
can
can
can
can
can
can
can
192.7
52.2
531.1
26.3
447.6
890.4
26.3
1201.4
292.0
653.0
236.3
5769.0
200.1
52.1
509.8
24.5
434.9
881.1
28.4
1109.6
250.2
629.7
215.8
5505.9
239.7
65.5
223.1
61.7
238.1
94.3
242.7
78.6
1161.5
26.4
1035.7
1565.3
82.5
3694.1
57.5
292.7
35.1
88.5
16.4
17.4
251.6
18.8
123.0
29.2
108.9
106.4
1235.6
757.0
30.9
822.2
1293.3
35.0
648.4
26.3
750.1
1176.2
32.9
1327.3
31.1
1024.2
1794.0
95.5
alcohols
3388.5
42.5
658.6
237.4
9448.0
3030.7
34.5
670.4
255.4
8793.3
9175.0
65.8
2096.3
31.6
resins/terpenoid
arom atic (non-PAH)
halogen
1488.7
29.7
13973.39
identified VOCe
21796.8
12597 (13)j

this study. Most of the aliphatic and olefin hydrocarbon VOC
is made up of the C1-C6 compounds. Wood-burning emis-
sions contain higher proportions of ethene and alkadienes
than typically found in other emission sources (36). Figure
2 shows that C2 hydrocarbons constitute approximately 20%
of the total measured VOC (C2-C12), with ethene (∼12%)
exceeding ethane and acetylene by approximately 4 and 5%,
respectively. Acetylene, shown to be present in the wood
combustion emissions, is often used as a marker species for
mobile sources (37, 38) and has a strong influence on the
attribution of motor vehicle exhaust in Chemical Mass
Balance (CMB) calculations. Of the C3-C6 hydrocarbons,
emissions of alkenes are at least twice as prevalent as alkanes
(Table 2, Figure 2). The dienes, especially 1,3-butadiene and
1,3-cyclopentadiene, are enriched in wood combustion
emissions and probably arise from the decomposition of
terpenoids. In contrast, synthetic logs produce more alkanes
than alkenes due to the presence of paraffin hydrocarbons
in their structure.
k
t
50
s
j
s
56
r
h
56
q
6
p
Furans. Furans, which are formed from the decomposition
of wood cellulose upon heating, constitute from 5 to 10% of
the total C2-C12 VOC from softwood and hardwood emissions
(Figure 2). Furan, 2-methylfuran, 2,5-dimethylfuran, and
2-furaldehyde are the most abundant of the furan species
measured for all of the softwood and hardwood emissions.
The structures of the pentoses commonly found in wood
structure, xylose and arabinose, favor the production of furans
with substituents at the 2 position.
f
d
6
o
2
d
n
Carbonyls. The carbonyl compounds, including ketones,
alkanals, and alkenals, constitute between 10 and 18% of the
C2-C12 VOC emissions from residential wood combustion
(Figure 2). The C4 ketones (butanone + 3-butene-2-one) and
3-methyl-3-butene-2-one are present in large amounts in
softwood and hardwood emissions. These compounds
most likely arise from the oxidation and decomposition of
isoprene (2-methyl-1,3-butadiene) during combustion.
Lower molecular weight carbonyl compounds such as
glyoxal, acetone, formaldehyde, acetaldehyde, and acrolein
are the most abundant carbonyl species emitted. These
compounds arise primarily from the combustion of cellulose
(29). Table 2 shows that glyoxal emissions are the most
abundant of these compounds, with 599.97 mg/ kg being
emitted from hardwoods combusted in the fireplace. Acrolein
is emitted in the lowest amount, with hardwoods burned in
the fireplace yielding 91.23 mg/ kg. Carbonyl compound
emissions from the synthetic log are lower as compared to
the hardwoods and softwoods.
2
m
c
2
l
28
13
k
e
13
Alcohols. Alcohols, in particular methanol, constitute as
much as 40% of the VOC emissions from residential wood
combustion. Methanol has been postulated to originate
primarily from the cleavage of methoxyl groups from lignin
and secondarily from methyl uronic acid units in hemicul-
luloses (32, 39). These data (Table 2) are consistent with this
proposed formation mechanism; methanol emissions are
higher for hardwoods, which contain more methoxy groups
in their lignin structure.
j
b
w
5
Lignin Breakdown Products (Methoxylated Phenols and
Phenols). Synapyl and coniferyl alcohols consist of the syringol
and guaiacol structural units, respectively (10, 26-28, 40-
42). Guaiacol is the predominant precursor of softwood
(gymnosperm) lignin. In the lignin polymer of hardwoods
(angiosperms), structural units consist of both guaiacyl and
syringyl types in roughly equal proportions. Thus, hardwood
lignin shows a higher methoxyl content than that of conifer-
ous woods (26).
v
i
i
g
5
g
f
g
h
u
h
g
Syringols and guaiacols are commonly found in wood-
burning emissions (2, 3, 10, 27, 32, 34, 40-42). These wood
lignin pyrolysis products are emitted in distinctive amounts
and constitute as much as 21% of the total fine particle mass
emissions during this study. As expected from variation in
50
n
a
t
9
VOL. 34, NO. 11, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 2 0 8 7

FIGURE 2. Weight fraction of volatile organic compounds (canister analysis only) from wood combustion source tests.
lignin composition, syringol abundances are larger in
hardwood emissions than in softwood emissions. Syringol
emission rates are 1.6 mg/ kg for the fireplace/ softwood
composite, 389.8 mg/ kg for the fireplace/ hardwood com-
posite, and 45.7 mg/ kg for the wood stove composite.
Guaiacols are emitted in approximately equal amounts
from both types of fuel in the fireplace, consistent with the
results from Hawthorne et al. (28). The sum of the guaiacol
compound emission rates are 391.5, 450.0, and 49.6 mg/ kg
for the fireplace/ softwood composite, fireplace/ hardwood
composite, and wood stove composite, respectively.
Fireplace hardwood emissions are especially enriched
with methoxylated phenols because hardwood emits both
syringol and guaiacol compounds. Wood stove emissions
contain less of the methoxylated phenols than the fireplace
emissions. The methoxylated phenols appear to break down
at the higher combustion temperatures encountered in the
wood stove. The methoxylated phenols are also present in
small amounts from the synthetic log emissions. This is not
surprising because the synthetic log contains sawdust from
real wood.
Phenol and the methyl phenols are also derived from the
thermal decomposition of wood lignin. Table 2 shows that
over 140 mg/ kg of phenol is emitted from both hardwoods
and softwoods in both appliances. Lower amounts of phenol
are emitted during synthetic log combustion.
Halogenated Compounds. Edgerton et al. (43) used chlo-
romethane to quantify wood smoke contributions to ambient
particulate matter in Oregon. Table 2 shows that in addition
to chloromethane, methylene chloride and methylchloroform
are emitted from wood combustion. Methylene chloride is
emitted at over 150 mg/ kg for hardwoods and softwoods in
the fireplace and at over 70 mg/ kg from the synthetic log.
The emissions of methylene chloride from the wood stove
are considerably lower.
Resin Acids/Terpenoids. The principal biogenic emissions
(not combustion related) from forest vegetation are isoprene
for hardwoods and R/ â-pinene for softwoods (44). As found
in this study, isoprene is emitted in similar amounts from
hardwoods and softwoods in both appliances. The terpenoids
quantified during this study include the pinenes, carene,
limonene, and a series of sesquiterpene isomers (shown in
Supporting Information). These terpenoids are enriched in
the softwood combustion emissions. Softwoods contain
oleoresins that are composed of terpenoids and resin acids.
These compounds are secreted by the resin-forming cells of
the sapwood when the tree is wounded by scarifying, boring,
etc. (30). The composition of these emissions depends on
the genus and species of the softwood being burned. The
Ponderosa and pinion pines tested during this study are
especially enriched in 3-carene, emitting a composite average
of 189.5 mg/ kg.
Retene (1-methyl-7-isopropylphenanthrene) and 1,7-
dimethylphenanthrene have been proposed as markers for
wood burning emissions that are formed by combustion
reactions of abietic and pimaric resin acids that are present
in softwood (28, 46, 47). Retene, 1-methyl-phenanthrene,
and the 1,7-dimethylphenanthrene isomers are more abun-
dant in softwood as compared to hardwood (Table 2). Retene
emission rates for the softwood fireplace composite are 4
times those of the hardwood fireplace composite and 90 times
those of the wood stove hardwood composite. However, the
emission rates of these compounds are low as compared to
the methoxy phenols emission rates, and their use in
apportionment studies are limited when their concentrations
are at or below ambient detection limits (10, 11).
Volatile Aromatic Compounds. Residential wood com-
bustion is a notable source of benzene, toluene, and the
xylenes. Hardwood combusted in the wood stove emits over
1 g of benzene/ kg of wood burned. Considerably more of the
9
2 0 8 8 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 11, 2000

aromatic compounds come from the wood stove combustion
than other appliances. The high temperatures and long
smoldering conditions encountered during a wood stove cycle
favor the emission and formation of aromatic species.
There is a considerable difference in the amount of indan
emitted from wood combustion as compared to indene.
Indene is likely to be formed from the same pathway as
benzofuran, which has a similar structure. The dehydration
of and cyclization of cellulose could favor the formation of
indene over indan.
Polycyclic Aromatic Hydrocarbons. Polycyclic aromatic
hydrocarbons (PAH) are an important component of resi-
dential wood smoke emissions (9, 12, 13, 48-50). The fuel
itself does not contain PAH, so these compounds must arise
from pyrosynthesis (12). The presence of lignin, the only
aromatic present in wood, has been shown to increases the
formation rate of PAH during combustion (33).
For the purpose of this study, PAH are divided into two
broad categories: gas phase and particle phase, even though
large groups of the three-four-ring PAH are distributed
between both gas and particle phases. Gas-phase PAH are
defined as those that elute from a nonpolar capillary
chromatographic column between naphthalene and phenan-
threne (not including phenanthrene). Particle PAH include
all PAH eluting between phenanthrene and coronene. The
ratio of gas to particulate phase PAH is approximately 1:1 for
softwood combusted in the fireplace, 2:1 for hardwood in
the fireplace, and 3:1 for hardwood in the wood stove. The
production of the more complex particle PAH, which are
formed at elevated combustion temperatures, were expected
to be enriched in the wood stove emissions. However, the
slower burn cycle characteristic of wood stove combustion
consists of a longer lower temperature smoldering condition
that may favor the production of gas-phase PAH. The total
PAH emission rate for fireplace/ softwood and fireplace/
hardwood combustion are 79.8 and 167.4 mg/ kg, respectively.
The average emission rate for total PAH compounds from
wood stoves is 74.7 mg/ kg. Similar to the results of Rogge et
al. (2), synthetic logs were found to be a source of PAH
emissions, yielding 75.2 mg/ kg.
chemical components. These species are limited as wood
combustion markers, however, by their presence in other
types of vegetative burning and meat cooking (10, 52).
Emissions of water-soluble potassium from wood com-
bustion are highly variable, with hardwoods burned in the
fireplace emitting 3-4 times more than softwoods or
hardwoods in the wood stove. The synthetic log combustion
emitted only 1.4 mg/ kg dry fuel of water-soluble potassium
during these tests (Table 2). Chlorine emissions range from
1.3 mg/ kg in the synthetic log to 8.9 mg/ kg from the fireplace/
hardwood. Sulfate emissions are enriched in hardwood
combustion in the wood stove (27.5 mg/ kg), which emits on
average almost 4 times more sulfate than softwood in the
fireplace (10.2 mg/ kg).
Isotopic Carbon. Isotopic carbon measurements of the
14C/ 12C abundance in ambient air and source samples show
the fraction of modern versus fossil derived carbon. This
isotopic carbon distribution has been used to apportion the
contributions of vegetative burning (modern carbon) in
ambient air. During this study, isotopic measurements were
conducted for selected samples of hardwoods and softwoods
and a synthetic log burned in the fireplace. The results for
hardwood and softwood burning (Table 2) showed modern
signatures, as expected. The synthetic log sample showed a
mixed fossil and modern signature (Table 2) consistent with
the wood chips/ petroleum wax composition of this source.
Source Profiles. As mentioned previously, the primary
objective of this study was to produce source profiles for
wood combustion that can be used as input files in source
attribution studies. For receptor modeling, methoxylated
phenols and ions are useful for the attribution of fine particle
emissions from wood combustion. Select PAH, such as retene,
1,7-dimethylphenanthrene, and 1-methylphenanthrene, can
be useful but are limited to emissions mostly from softwoods
and they are emitted in low amounts (<0.1% of fine particle
mass) relative to the other species mentioned. Levoglucosan,
a compound not reported in this study, is emitted in copious
amounts from wood combustion and is a potentially useful
compound for source apportionment (53). Among the volatile
fraction, terpenoids, methyl chloride, furans, and the ketones
could be useful for both hardwood and softwood apportion-
ment. Caution must be exercised in using many of these
compounds, however, due to their potentially short atmo-
spheric lifetimes.
Khalil (48) reported that the predominate PAHs in wood
smoke emission samples were acenaphthylene, naphthalene,
anthracene, phenanthrene, benzo[a]pyrene (BaP), and ben-
zo[e]pyrene (BeP). Two- and three-ring PAHs were respon-
sible for 70% of the measured PAHs (49). Table 2 shows similar
results from this study, with unsubstituted naphthalene,
phenanthrene, and acenaphthylene being emitted in the
largest amounts.
Organic and Elemental Carbon. The ratio of total organic
carbon (OC) to total elemental carbon (EC) can be useful in
distinguishing carbonaceous sources. The ratio of OC/ EC
for the softwood is 3.9, as compared to 9.0 for the hardwood
burned in the fireplace and 7.9 in the wood stove.
For the purposes of calculating weight fractions of
semivolatiles and particle compounds for source profiles, a
sum of particulate species is used as the denominator. This
sum includes particulate organics, elements (normalized for
oxygenated species by multiplying 1.89 × Al, 2.14 × Si, 1.65
× Cl, 1.4 × Ca, and 1.43 × Fe), elemental carbon, and organic
carbon. Organic carbon results used for the sum of particulate
species are adjusted by multiplying by 1.2 to account for
unmeasured hydrogen + oxygen (54) and by subtracting the
particle organic species measured.
Hildeman et al. (50) found that organic carbon was more
prevalent in synthetic log emissions than elemental carbon,
while this study shows the opposite. These differences are
possibly a result of different burning conditions for the
individual tests conducted. Differences may also result from
the different analytical methods used for the analysis of
carbon in these two studies. Chow et al. (24) described the
importance of the analytical method used when defining the
measured split between organic and elemental carbon.
Elements + Ions. Trace elements and ionic species such
as water-soluble potassium, chloride, and sulfate are emitted
from wood combustion (1). Turn et al. (51) showed that many
of these species make up large amounts of the unburned
inorganic portion of wood mass. As mentioned previously,
these trace elements have been commonly used with the
total organic and elemental carbon concentrations to ap-
portion wood smoke in studies that did not utilize organic
The total VOC used as the denominator for calculating
weight fraction of individual VOC (Figure 2) is a sum of all
identified and unidentified compounds measured by the
canister analysis. A standard protocol has not been estab-
lished to define the denominator for VOC profiles used in
source attribution studies. Fujita et al. (36) has proposed
using the Photochemical Assessment Monitoring Stations
(PAMS) list of compounds as the denominator. The PAMS
species are emitted from most combustion sources and can
account for 70-80% of the total ambient hydrocarbons in
most urban locations (36).
Summary
This paper describes a comprehensive analytical effort to
analyze the fine particle and gaseous emissions from
residential wood combustion. Over 350 compounds and
9
VOL. 34, NO. 11, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 2 0 8 9

(12) Cooke, W. M.; Allen, J. M.; Hall, R. E. Characterization of
Emissions from Residential Wood Combustion Sources. Pro-
ceedings of the 1981 International Conference on Residential
Solid Fuels: Environmental Impacts and Solutions, Portland,
OR, June 1-4, 1982.
(13) Burnet, P. G. Effects of Appliance Type and Operating Variables
on Woodstove Emissions. Vol. 1, Report and Appendices A-C;
EPA 600/ 2-90/ 001A; U.S. EPA: Washington, DC, 1988.
(14) U.S. Environmental Protection Agency. A Summary of the
Emissions Characterization and Nonrespiratory Effects of Wood
Smoke; EPA 453/ R-93-036; U.S. EPA: Washington, DC, 1993.
(15) U.S. Environmental Protection Agency. 40 CFR Part 60. Fed.
Regist. 53 (38), 1988.
elements were quantified for emissions of wood smoke from
appliances, fuels, and burn conditions that have been shown
in previous studies to effect both the composition and the
emission rates from wood burning. During this study, the
appliance used (fireplace versus wood stove) and the type
of wood burned (hardwood, softwood, synthetic log) had
the largest effect on the composition of emissions from wood
combustion. Four distinct composite emission rate profiles
were constructed to represent softwoods, hardwoods, and
synthetic logs burned in a fireplace as well as hardwoods
burned in a wood stove.
By creating source profiles according to guidelines
described in this paper, these data may be used in source
attribution studies for either fine particles or VOC. Until
recently (57), wood combustion has not been included in
VOC source apportionments. On the basis of the emission
rates measured in this study, wood combustion should be
included when evaluating the impact of combustion sources
on VOC in ambient airsheds. In addition, the data presented
here improve the current knowledge base for the types of
pollutants emitted from wood combustion and their emission
rates; especially hazardous air pollutants such as 1,3-
butadiene, benzene, formaldehyde, and others that are not
considered in current assessments of wood combustion
emissions.
(16) Tiegs, P. Omni Environmental Services, personal communica-
tion, 1997.
(17) Hildemann, L. M.; Cass, G. R.; Markowski, G. R. Aerosol Sci.
Technol. 1989, 10, 193-204.
(18) Zielinska, B.; Fujita, E. M.; Sagebiel, J. C.; Harshfield, G.; Uberna,
E.; Hayes T.; Keene, F. J. Air Waste Manage. Assoc. 1998, 48,
1038-1050.
(19) Zielinska, B.; Sagebiel, J. C.; Harshfield, G.; Gertler, A. W.; Pierson,
W. R. Atmos. Environ. 1996, 30, 2269-2286.
(20) Chow, J. C.; Watson, J. G. Guidelines for PM-10 Sampling and
Analysis Applicable to Receptor Modeling; U.S. Environmental
Protection Agency, Office of Air Quality Planning and Stan-
dards: Washington, DC, 1994; EPA-452/ R-94-009.
(21) Scanlon, J. T.; Willis, D. E. J. Chromatogr. Sci. 1985, 23, 333-
340.
(22) Jorgensen, A. D.; Picel, K. C.; Stamoudis, V. C. Anal. Chem. 1990,
62, 683-689.
(23) Pate, B.; Jayanty, R. K. M.; Peterson, M. R.; Evans, G. F. J. Air
Acknowledgments
We express our appreciation of the Colorado State University,
Cooperative Institute for Research in the Atmosphere, for
financial support of the work relating to NFRAQS. Additional
support was granted from Brian Jennison and the Air Quality
Division of the Washoe County District Health Department.
Larry Sheetz, Steve Batie, and Rick Purcell are the DRI
technicians responsible for the construction of the dilution
tunnel sampling system. The authors received invaluable
assistance from Ben Myren (Myren Consulting) with the wood
stove testing. This work could not have been accomplished
without their help.
Waste Manage. Assoc. 1992, 42, 460-462.
(24) Chow, J. C.; Watson, J. G.; Pritchett, L. C.; Pierson, W. R.; Frazier,
C. A.; Purcell, R. G. Atmos. Environ. 1993, 27A, 1185-1201.
(25) Klinedinst, D. B.; Currie, L. A. Environ. Sci. Technol. 1999, 33,
4146-4154.
(26) Sarkanen, K. V.; Ludwig, C. H. Lignins; Wiley and Sons: New
York, 1971.
(27) Simoneit, B. R. T.; Rogge, W. F.; Mazurek, M. A.; Standley, L. J.;
Hildemann, L. M.; Cass, G. R. Environ. Sci. Technol. 1993, 27,
2533-2541.
(28) Hawthorne, S. B.; Miller, D. J.; Barkley R. M.; Krieger M. S.
Environ. Sci. Technol. 1988, 22, 1191-1196.
(29) Rowell R. The Chemistry of Solid Wood; Advances in Chemistry
Series; American Chemical Society: Washington, DC, 1984.
(30) Hillis, W. E. Wood Extractives; Academic Press: New York, 1962.
(31) Commins, B. T. Atmos. Environ. 1969, 3, 565-77.
(32) McKenzie, L. M.; Hao, W. M.; Richards, G. N.; Ward, D. E. Atmos.
Environ. 1994, 28, 20, 3285-3292.
Literature Cited
(1) Watson, J. G.; Chow, J. C.; Richards, L. W.; Neff, W. D.; Andersen,
S. R.; Dietrich, D. L.; Houck, J. E.; Olmez, I. The 1987-88 Metro
Denver Brown cloud Study, Vol. III: Data Interpretation; DRI
Document 8810.1F3; DRI: Denver, CO, 1988.
(2) Rogge, W. F.; Hildemann, L. M.; Mazurek, M. A.; Cass, G. R.;
Simoneit, B. R. T. Environ. Sci. Technol. 1998, 32, 13-22.
(3) Schauer, J. J.; Rogge, W. F.; Hildemann L. M.; Mazurek M. A.;
Cass G. R. Atmos. Environ. 1996, 30, 3837-3855.
(33) Hueglin, C.; Gaegauf, C.; Ku¨ nzel, S.; Burtscher, H. Environ. Sci.
Technol. 1997, 31, 3439-3447.
(34) Standley, L. J.; Simoneit, B. R. T. Atmos. Environ. 1994, 28, 1-16.
(35) Statistics and Graphics Guide, JMP Manual, Version 3.1; SAS
Institute: Cary, NC, 1995.
(4) U.S. Environmental Protection Agency. Compilation of Air
Pollutant Emission Factors. Vol. 1: Stationary Point and Area
Sources, 5th ed.; AP-42; Office of Air Quality Planning and
Standards: 1995.
(36) Fujita, E. M. Emission Source Profiles Applicable to CMB Receptor
Modeling of Texas PAMS VOC Data; Air Quality Planning and
Assessment Division, Texas Natural Resource Conservation
Commission: 1998.
(5) http:/ / www.epa.gov/ ttn/ chief/ trends97/ emtrnd.html.
(6) Leese, K. E.; Harkins, S. M.; McCrillis, R. C. Effects of Burn Rate,
Wood Species, Moisture Content and Weight of Wood Loaded on
Woodstove Emissions; EPA 600/ 2-89/ 025; U.S. Environmental
Protection Agency: Washington, DC, 1989.
(37) Barrefors, G.; Petersson, G. Chemoshpere 1995, 30, 8, 1551-
1556.
(38) Fujita, E. M.; Watson, J. G.; Chow, J. C.; Lu, Z. Environ. Sci.
Technol. 1994, 28, 1633-1649.
(39) Degroot, W. F.; Pan, W. P.; Rahman, M. D.; Richards, G. N. J.
(7) Klaasssen, C. D. Casarett and Doull’s Toxicology: The Basic
Science of Poisons; McGraw-Hill: New York, 1996.
Anal. Appl. Pyrol. 1988, 13, 221-231.
(40) Hawthorne, S. B.; Miller, D. J.; Langenfield, J. J.; Krieger, M. S.
Environ. Sci. Technol. 1992, 26, 2251-2262.
(8) Watts, R. R.; Drago, R. J.; Merrill, R. G.; Williams, R. W.; Perry,
E.; Lewtas, J. J. Air Pollut. Control Assoc. 1988, 38, 652-660.
(9) Peters, J. A. POM emissions from residential wood burning; An
environmental assessment. Presented at the International
Conference of Residential Solid Fuels, Portland, OR, 1981.
(10) McDonald, J.; Zielinska, B.; Fujita, E. M.; Chow, J. C.; Watson,
J. G.; Sagebiel, J. C.; Sheetz, L.; Batie, S Chemical Speciation of
PM2.5 Emissions from Residential Wood Combustion and Meat
Cooking. Proceedings of the 91st Annual Meeting and Exhibition
of the Air & Waste Management Association, San Diego, CA,
June 14-18, 1998; Paper 98-RP92B.02.
(41) Sagebiel, J. C.; Seiber, J. N. Environ. Toxicol. Chem. 1993, 12,
813-822.
(42) Steiber, R. S. J. Air Waste Manage. Assoc. 1993, 43, 859-863.
(43) Edgerton, S. A.; Khalil, M. A. K.; Rasmussen, R. A. Environ. Sci.
Technol. 1986, 20, 803-807.
(44) Tanner, R. L.; Zielinska, B. Atmos. Environ. 1994, 28, 1113-
1120.
(45) Benner, B. A.; Wise, S. A., Jr.; Currie, L. A.; Klouda, G. A.;
Klinedinst, D. B.; Zeidinger, R. B.; Stevens, R. K.; Lewis C. W.
Environ. Sci. Technol. 1995, 29, 2382-2389.
(46) Ramdahl, T. Nature 1983, 306, 580-582.
(47) Guenther, F. R.; Gordon, G. E.; Zoller, W. H. J. High Resolut.
(11) Fujita, E. M.; Watson, J. G.; Chow, J. C.; Robinson, N. F.; Richards,
L. W.; Kumar N. Northern Front Range Air Quality Study. Volume
C: Source Apportionment and Simulation Methods and Evalu-
ation; Colorado State University: Denver, CO, 1998.
Chromatogr. 1988, 11, 761-765.
9
2 0 9 0 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 11, 2000

(48) Khalil, M. A. K.; Edgerton, S. A.; Rasmussen R. A. Environ. Sci.
Technol. 1983, 17, 555-559.
(54) Pierson, W. R.; Brachaczek, W. W. Aeresol Sci. Technol. 1983, 2,
1-40.
(49) Schmeltz, I.; Hoffmann, D. Formation of Polynuclear Aromatic
Hydrocarbons from Combustion of Organic Matter, Carcino-
genesissA Comprehenxive Survey, Vol. 1; Raven Press: New York,
1976.
(55) Rau, J. Aerosol Sci. Technol. 1989, 10, 181-192.
(56) Ramdahl, T.; Alfheim, I.; Rustad, S.; Olsen, T. Chemosphere.
1982, 11, 601-611.
(50) Hildemann, L. M.; Markowski, G. R.; Jones, M. C.; Cass, G. R.
Aerosol Sci. Technol. 1991, 14, 138-152.
(57) Schauer, J. J.; Cass, G. R. Environ. Sci. Technol. 2000, 34, 1821-
1832.
(51) Turn, S. Q.; Jenkins, B. M.; Chow, J. C.; Pritchett, L. C.; Campbell,
D.; Cahill, T. A.; Whalen, S. A. J. Geophys. Res. 1997, 102, 3683-
3700.
(52) Schauer, J. J.; Kleeman, M. J.; Cass, G. R.; Simoneit, B. R. T.
Environ. Sci. Technol. 1999, 33, 1566-1577.
Received for review August 17, 1999. Revised manuscript
received March 6, 2000. Accepted March 7, 2000.
(53) Simoneit, B. R. T.; Schauer, J. J.; Cass, G. R. Atmos. Environ.
1999, 33, 173-182.
ES9909632
9
VOL. 34, NO. 11, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 2 0 9 1