Environ. Sci. Technol. 1990, 2 4 , 1265-1270
Selected Organic Pollutant Emissions from Unvented Kerosene Space Heaters Gregory W. Traynor,” Michael G. Apte, and Harvey A. Sokol
Indoor Environment Program, Applied Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 Jane C. Chuang
Analytical and Structural Chemistry Center, Battelle Columbus Laboratories, Columbus, Ohio 4320 1 W. Gene Tucker Air and Energy Engineering Research Laboratory, US. Environmental Protection Agency, Research Triangle Park, North Carolina 277 1 1
Judy L. Mumford
Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 277 11 An exploratory study was performed to assess the semivolatile and nonvolatile organic pollutant emission rates from unvented kerosene space heaters. A well-tuned radiant heater and maltuned convective heater were tested for semivolatile and nonvolatile organic pollutant emissions. Each heater was operated in a 27-m3 chamber with a prescribed on/off pattern. Organic compounds were collected on Teflon-impregnated glass filters backed by XAD-2 resin and analyzed by gas chromatography/mass spectrometry. Pollulant source strengths were calculated by use of a mass balance equation. The results show that kerosene heaters can emit polycyclic aromatic hydrocarbons (PAHs); nitrated PAHs; alkylbenzenes, phthalates; hydronaphthalenes; aliphatic hydrocarbons, alcohols, and ketones; and other organic compounds, some of which are known mutagens. Introduction
The sale and use of unvented kerosene space heaters have increased dramatically in the United States during the past decade. These heaters have been found to emit a wide variety of pollutants including carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, sulfur dioxide, formaldehyde, and suspended particles (1-5). Several studies using a kerosene-fueled turbulent-diffusion continuous-flow combuster showed that many polycyclic aromatic hydrocarbons (PAHs) are emitted during kerosene combustion (6-8). Two of these studies also showed that kerosene soot is indirectly mutagenic (7,8),and one showed that essentially all of the indirect mutagenic activity of kerosene soot was due to unnitrated PAH compounds (8). Another study revealed that kerosene heaters emit dinitropyrenes, showed kerosene soot to be directly mutagenic, and attributed most of the direct mutagenic activity to the dinitropyrenes (9). The above studies have shown the following: kerosene combustion products can be mutagenic, kerosene combustion can produce PAHs and nitrated PAHs, and much of the mutagenic activity of kerosene soot is likely due to the PAHs and nitrated PAHs. However, it is not known whether the unvented portable kerosene space heaters with wicks commonly used indoors in the United States produce emissions similar to those emitted by turbulent-diffusion kerosene combustors used in laboratory studies (6-8) be0013-936X/90/0924-1265$02.50/0
cause of the difference in the combustion process. Additionally, it is not known whether unvented kerosene space heaters produce other potentially harmful organic pollutants. The goal of this exploratory study was to measure selected pollutant emission rates (including PAH and nitrated PAH emission rates) from portable kerosene heaters commonly used in the United States. Two heater/tuning conditions were chosen based, in part, on previously reported particulate emission data (4).The previous study showed that particulate emissions from a well-tuned, properly adjusted convective kerosene heater were negligible but that particulate emissions from a well-tuned, properly adjusted radiant heater were not. Therefore, it was reasonable to assume that the organic pollutant emission rates observed from a radiant heater would be higher than the rates from a convective heater. A radiant heater operating under well-tuned, properly adjusted conditions was chosen as the first heater/ tuning combination to be tested. The other heater/tuning combination chosen for testing was a convective heater operated under maltuned conditions. This choice was based, in part, on conversations with kerosene heater users and testers, who indicated that a convective heater was more likely to “soot” (i.e., emit a visible stream of particles) than was a radiant heater. The convective heater was maltuned by lifting the exterior shell of the heater by approximately 1cm, thereby providing excess air to the wick, which probably represents an exaggerated case of maltuning. Multiple tests were conducted on each heaterltuning combination to allow collection of enough pollutant mass for future tests of mutagenic activity. All experiments were conducted at the Lawrence Berkely Laboratory (LBL). Battelle Columbus Laboratories prepared and analyzed filters, provided clean resins used by LBL, and provided sample extracts to the Health Effects Research Laboratory of the U.S. Environmental Protection Agency for future mutagenicity tests. Experimental Methods and Test Protocol
Each heater was operated in a 27-m3 chamber. The chamber walls and ceiling are taped-and-sealed Sheetrock, and the floor is concrete. The heaters were operated intermittently to avoid unrealistically high chamber temperatures. For the five radiant heater tests conducted, the
0 1990 American Chemical Society
Environ. Sci. Technol., Vol. 24, No. 8, 1990
1265
heater was operated for 4 cycles of 1h on and 1h off. For the two maltuned convective heater tests, the heater was operated for only 2 cycles of the same 1-h-on/l-h-off pattern. The fuel consumption rates averaged 7000 f 100 kJ/h for the radiant heater tests and averaged 6900 f 600 kJ/h for the maltuned convective heater tests (heat content of kerosene, 43.5 kJ/g or 41.2 Btu/g). Two &h control tests were also conducted without a heater in operation. The air-exchange rates of the chamber averaged 1.1f 0.1 air changes/ h for all tests. An average air-exchange rate for each test was computed from the decay curves of either CO or COz. The air-exchange rate was dominated by our sampling flow rate. Pollutant source strengths (mass of pollutants emitted per hour) of particles and organic compound emissions were calculated by the steady-state, mass balance equation. The mass balance equation, arranged to isolate the pollutant source strength, follows: s = V[C ( a + k) - PUC,] (1)
Table I. Standard Compounds for the Semiquantitative Analyses of Organic Pollutants
where S is the pollutant source strength (mass/h), Vis the chamber volume (27 m3), C is the average indoor pollutant concentration (mass/m3),a is the average chamber airexchange rate (h-l), k is the average net rate of removal processes other than airflow, also called “reactivity” rate (h-l), P is the outdoor pollutant penetration factor (dimensionless), and C, is the average outdoor pollutant concentration (mass/m3). Equation 1 is the steady-state version of the indoor air quality mass balance equation developed by Turk (10) and used by numerous researchers (e.g., refs 3 and 11-14). The pollutant reactivity rate is the rate that the pollutant reacts with or deposits on indoor surfaces and suspended particles. This rate is often expressed as a first-order removal process similiar to air exchange. The outdoor penetration factor is a number between zero and 1 that reflects pollutant removal caused by the chamber shell as the outdoor air flows into the chamber. A value of 1implies that there was no pollutant removal by the chamber shell. Average source strengths determined with eq 1 were multiplied by 2 in order to estimate the pollutant source strengths with the kerosene heater on. Pollutant source strengths for CO, NO, and NOz were calculated by using the time-dependent version of eq 1 (11)because real-time data, as opposed to time-averaged data, were available for these pollutants. Pollutant emission rates (mass of pollutant emitted per kilojoules of fuel consumed) were calculated by dividing the kerosene heaters’ pollutant source strengths by their fuel consumption rates. P was assigned the value of 1.0 for inorganic gases, such as nitrogen dioxide, and 0.4 for particles on the basis of previous research in the same chamber (12). Somewhat arbitrarily, P was assumed to be 0.8 for semivolatile organic compounds (SVOCs);however, using a value of 1.0, as for other gaseous compounds, would not significantly alter the emission rate results. The average chamber reactivity/deposition rate, h, was directly determined from real-time decay curves for inorganic gases. For SVOCs and particles, estimates of k were made by rearranging eq 1 and using the indoor/ outdoor pollutant ratios measured during control tests (i.e., when S = 0), the air-exchange rates measured during control tests, and the estimates for P. The estimates of k ranged from 0.0 to over 2.0 h-’ for SVOCs, depending upon the compound or class of compounds, and ranged from 0.0 to 0.4 h-’ for particles. For the purpose of estimating pollutant emission rates, k was assigned the value of 1.0 h-’ for SVOCs and 0.2 h-’ for particles. Since different SVOCs have different reactivity rates, some error will be introduced to the emission rate calculations by
10 10
1266 Environ. Sci. Technol., Vol. 24, No. 8, 1990
compd name octane decane dodecane heptadecane n-eicosane docosane naphthalene phenanthrene pyrene chrysene benzo[ a]pyrene benzo[ghi]perylene acridine pentachlorophenol benzoic acid 1,2,4-trimethylbenzene di-methyl phthalate di-n-butyl phthalate bis(2-ethylhexyl) phthalate
compd classa aliphatic HCs aliphatic HCs aliphatic HCs aliphatic HCs aliphatic HCs aliphatic HCs PAHs PAHs PAHs PAHs PAHs PAHs N heterocyclic compds phenols organic acids base-neutral org compds phthalates phthalates phthalates
concn, rg/mL high low level level 20 20 20 20 20 20 10 10 10 10 10 10 10 10 20
20 20 20 20
10 10 10 10 10 10 5 5 5 5 5 5 5
5
10 10 10
HCs, hydrocarbons.
using a single k value for all SVOCs. Indoor pollutant concentration measurement/collection techniques fell into three categories. First, real-time CO, COO,NO, and NOz measurements were made with standard outdoor air pollution instruments (11). Second, 100cm2 Teflon-impregnated glass-fiber filters were used to collect nonvolatile and particle-bound organic compounds. And third, approximately 100 g of XAD-2 resin was placed behind each glass-fiber filter to collect SVOCs (15). Each XAD/fdter sampler was operated at an airflow rate of 6.8 m3/h, and each sample was collected for no more than 8 h. Two samplers were operated inside the chamber, and one was operated outside the chamber. One filter and one XAD cartridge were used per test at each sampling location except for the maltuned convective tests, where heavy soot loading required the use of two filters per test for both indoor sampling systems. After sample collection, the XAD resin was placed in clean glass jars with Teflon-lined caps, and the filters were folded and wrapped in aluminum foil. The XAD-2 and filter samples were placed in unused clean paint cans that were placed in dry ice mailing boxes. The samples and filter and XAD-2 blanks were shipped from LBL to Battelle Columbus Laboratories, by overnight carriers, where all analyses of the glass-fiber filters and XAD resin were done (15). The glass filters were weighed before and after sample collection to determine the total mass of collected particles, to an estimated precision of 5%. Soluble organic material was removed from the filter and the XAD resin samples by Soxhlet extraction with methylene chloride. After this extraction, aliquots of extracts from XAD samples were removed for total chromatographable organic (TCO) analysis (16). TCO analysis yields information on the amounts of organic material with boiling points in the approximate range of 100-400 OC. A gas chromatograph (GC) with a flame ionization detector was used for TCO analysis. The GC was calibrated with mixtures of known concentrations of normal Cg, Clz, C16, and Cz0 hydrocarbons. The estimated precision for TCO analysis is 20%.
Table 11. Carbon Monoxide, Nitric Oxide, and Nitrogen Dioxide Emission Rates for Tests of Well-Tuned Radiant and Maltuned Convective Heaters
Table IV. GRAV and TCO Concentration Results for XAD-Collected Samples for Well-Tuned Radiant and Maltuned Convective Heaters GRAV," fig/m3 inc outd
average emission rates," Na/kJ test RAD-1 RAD-2 RAD-3 RAD-4 RAD-5 MCON-1 MCON-2
co
NO 0.69 f 0.16 0.53 f 0.19 0.69 f 0.21 0.85 f 0.24 0.71 f 0.19 21 f 3 22 f 0
92 f 16 88 f 11 77 f 10 a5 f 12 79 f 4 22 f 7 18f4
NO2 5.1 f 0.4 5.0 f 0.3 5.0 f 0.3 4.7 f 0.2 4.6 f 0.2 7.5 f 1.8 5.6 1.6
*
"Radiant (RAD) test averages are from four 1-h burns. Maltuned convective (MCON) test averages are from approximately two I-h burns. Plus/minus values are standard deviations of the two or four emission rates calculated from each 1-h burn. ~
~~
Table 111. Total Suspended Particulate Mass and GRAV Concentration Results for Filter-Collected Samples for Well-Tuned Radiant and Maltuned Convective Kerosene Heaters
test RAD-1 RAD-2 RAD-3 RAD-4 RAD-5 MCON-1 MCON-2 CONTROL-1 CONTROL-2
mass, fig/m3 OUtC inb 28 23 24 14 13 5300 2300 5 4
18 9 9 7 2 62 40 13 13
GRAV,"sd rg/m3 inb outc nm nm 8.2 nm nm nm 100 1.6 nm
nm nm 3.6 nm nm nm 13 5.6 nm
" GRAV analysis is designed to measure solvent-extractable organics, most of which have boiling points over 300 "C. bRefers to the concentrations measured inside the chamber. CRefersto the concentrations measured outside the chamber. nm, not measured. Gravimetric (GRAV) analyses for solvent-extracted organics, most of which have boiling points over 300 OC, were done on selected XAD and filter extracts (16). Aliquots of sample extracts were dried and weighed for this analysis. Repeat measurements yielded an average estimated precision of 20% for the GRAV analyses. Nitrated-PAH and other organic analyses were accomplished with a combined gas chromatograph/mass spectrometer (GC/MS). Analyses were performed by a Finnigan 4500 quadrapole MS equipped with an INCOS 2300 data system and a Finnigan GC. The sample extracts were quantitatively analyzed by an on-column injection, negative chemical ionization (NCI) technique (17)for the following nitrated PAHs: 1-nitronaphthalene, 2-nitrofluorene, 9-nitroanthracene, 9-nitrophenanthrene, 6nitrochrysene, 6-nitrobenzo[a]pyrene, 3-nitrofluoranthene, 1-nitropyrene, 1,3-dinitropyrene, 1,6-dinitropyrene, 1,8dinitropyrene, 2,7-dinitrofluorene, and 2,7-dinitrofluorenone. The accuracy and precision of this technique were within 20%. The extracts were also analyzed by electron impact (EI) GC/MS to provide tentative determinations of the various classes of compounds in the extracts. The identifications of sample components were accomplished by comparison to reference spectra in the Environmental Protection Agency/ National Institutes of Health mass spectral library. The quantitations were based on the surrogate response factors generated from partial calibration curves (two levels, triplicate analyses) of the surrogate standards. The surrogate standards (Table I) were chosen to best represent
test RAD-1 RAD-2 RAD-3 RAD-4 RAD-5 MCON-1 MCON-2 CONTROL-1 CONTROL-2
490 360 510 450 380 500 360 99 50
190 120 120 77 48 250 220 94 29
TCO,bpg/m3 inc outd 1400 930 4900 1000 1700 2100 950 700 100
150 190 370 92 130 400 240 290 110
" GRAV analysis is designed to measure solvent-extractable organics, most of which have boiling points over 300 "C. bTCO analysis is designed to measure solvent-extractable organics with boiling points between 100 and 400 "C. cRefers to the concentrations measured inside the chamber. Refers to the concentrations measured outside the chamber. the range of organic compound classes present in the extracts. The response factor of each standard was used for the same class of compounds (e.g., naphthalene as the standard for all two-ring PAHs). If the identified compounds are not represented by the standards, the response factors are designated as 1. The analysis is called semiquantitative because results are estimated to be accurate only to within a factor of 3-4. However, the precision of the results is on the order of 30%. The MS was operated at 70 eV and scanned from 50 to 450 amu/s in the E1 mode. In the NCI mode, the MS was operated at 150 eV and scanned from 100 to 450 amu/s. Methane was used as the carrier and reagent gas.
Results and Discussion Carbon Monoxide, Nitric Oxide, and Nitrogen Dioxide. CO, NO, and NO2 emission rate results for each test that employed organic pollutant samples are presented in Table 11. The emission rate results for the well-tuned radiant heater are consistent with previously published data (2,4). The results for the maltuned convective heater show that total nitrogen oxide (NO + NO2 = NO..) emissions are 27% lower than for a well-tuned convective heater. A well-tuned heater will emit approximately 15 pg/kJ N (of NO,) ( 4 ) ;the maltuned convective heater emitted approximately 11 pg/kJ N (of NO,). The CO emissions from the maltuned convective heater were similiar to those from a well-tuned heater. This result is not expected to be universal but is probably unique to the method of maltuning used in this study, that is, supplying excess air to the combustion region. TCO, GRAV, and TSP Mass. Table I11 lists the TSP mass and GRAV concentration results for filter-collected samples. Both TSP mass and GRAV concentrations were higher for the maltuned convective heater tests than for the radiant heater tests. However, the ratio of GRAV to TSP mass was much lower for the maltuned convective heater tests than for the radiant heater tests. This observation is consistent with a previously reported observation that increased sooting does not cause a proportionate increase in organic pollutants (18). Table IV lists the GRAV and TCO results for XADcollected samples. Again, notice that the GRAV and TCO indoor concentrations for the well-tuned radiant and the maltuned convective tests are similiar, despite the great difference in TSP concentrations. Tables I11 and IV show that kerosene heaters do emit some organic pollutants and Environ. Sci. Technol., Vol. 24, No. 8, 1990
1267
Table V. TCO, GRAV, and TSP" Mass Emission Rates for Well-Tuned Radiant and Maltuned Convective Kerosene Heaters pollutant group TCO-XAD GRAV-XAD GRAV-filter TSP
emission rates, ng/kJ RAD-1, -2, -4, -5 RAD-3 MCON-1, -2 19 6 nmb 0.2
76 3
0.07 0.2
23 6 0.9 40
TSP. total sumended oarticdate. *nm. not measured. Table VI. Nitrated-PAH Emission Rates from Well-Tuned Radiant and Maltuned Convective Kerosene Space Heaters
compounds 1-nitronaphthalene XAD filter 9-nitroanthracene XAD filter 3-nitrofluoranthene (filter only) 1-nitropyrene (filter only)
emission rates," ng/kJ RAD-1, -2, -4, -5 RAD-3 MCON-1, -2 0.04
0.02
nd
0.0005
0.04 0.02
nd 0.0001 0.0003
0.008 0.0005 nd
nd 0.006 nd
0.0006
0.001
nd
'nd, none detected. that most of the organic pollutants were trapped by the XAD-2 resin. TCO analyses were not performed on the filter-collected samples because compounds with boiling points lower than 300 "C were assumed to pass through the filter to be collected on the XAD-2 resin. As will be discussed later in this report, the assumption applied well to the well-tuned radiant heater tests but not as well to the maltuned convective heater tests, in which the heavy soot loading on the filters trapped a significant fraction of many SVOCs before they reached the XAD. Nitrated PAHs and Other Organic Compounds. Samples of similar types were combined before organic and nitrated-PAH compound analyses were done; however, XAD samples were not mixed with filter samples. Samples for radiant tests coded RAD-1, RAD-2, RAD-4, and RAD-5 were combined (note that the TCO results for RAD-3 were much higher than for the other radiant tests so RAD-3 was analyzed separately); samples from maltuned convective tests MCON-1 and MCON-2 were combined; and samples from CONTROL-1 and CONTROL-2 were combined. Indoor and outdoor samples were not combined. The final totals were eight XAD-2 and eight filter samples: two indoor radiant, two outdoor radiant, one indoor convective, one outdoor convective, one indoor control, and one outdoor control. Field blanks of glass-fiber filters and XAD-2 were also analyzed. The amounts of pollutants found in the field blanks were subtracted from the results of the test samples. To conform with previous research on pollutant emissions from combustion appliances, results presented here will be expressed as pollutant emission rates (i.e., mass of pollutant emitted per unit of fuel consumed). Pollutant source strengths (i.e., mass of pollutant emitted per unit of time) can be calculated by multiplying the emission rate values by the kerosene heater fuel consumption rate (approximately 7000 kJ/h for the heaters used in this study). Estimates of indoor air pollutant concentrations can be calculated by rearranging eq 1. 1288
Environ. Sci. Technol., Vol. 24, No. 8 , 1990
A rough error propagation analysis was conducted on our calculations of pollutant emission rates, using precision estimates for the variables in eq 1, to determine if the emission rates were significantly different from zero. Except where noted, the omission of a source strength value from this paper is the result of one of three possibilities: the pollutant was not sought, the pollutant was sought but not found, or the pollutant emission rate was not significantly different from zero. In the last circumstance, qualitative judgments were used in some cases, for example, when the limit of detection of a compound was only approximately known and no outdoor concentrations were reported. For comparison with other emission rate tables, the emission rates for TCO, GRAV, and TSP mass are given in Table V. Table VI lists the emission rates of several nitrated PAHs. The nitrated PAHs searched for were previously discussed. 1-Nitronaphthalene is clearly emitted by the well-tuned radiant and maltuned convective koerosene space heaters and was collected almost entirely on the XAD-2 resin for the radiant heater tests. For the maltuned convective heater tests, 30% of the 1-nitronaphthalene was collected on the filter. This is a result of the heavy loading of fresh soot on the filter, which acted like a collecting resin. Emissions of 9-nitroanthracene were observed in the XAD fraction of one of the radiant heater tests and in the filter fraction of the maltuned convective test. (Again, the heavy soot loading on the filters in the convective tests captured the 9-nitroanthracene before it reached the XAD). Emissions of 1-nitropyrene were also observed in the filter fraction of both radiant-test samples, whereas only trace amounts of 3-nitrofluoranthene were observed in one of the two series of radiant heater tests in the filter-collected fraction. Both 3-nitrofluoranthene and 1-nitropyrene have been observed to be somewhat mutagenic (9,19),but the mutagenic activities of 1-nitronaphthalene and 9-nitroanthracene are low (19). Missing from Table VI are the highly mutagenic dinitropyrenes (DNPs),possibly because their emission rates were below the detection limit of the techniques used here. The 1,3-DNP, 1,6-DNP, and 1,8DNP combined source strengths were measured by another research team to be approximately 0.2 ng/h (9). The estimated limit of detection in terms of source strengths for DNPs or other nitrated PAHs investigated for this report is approximately 1.0 ng/h. Future studies could take advantage of various fractionation and cleanup techniques to improve the detection sensitivity for this class of compounds; however, such elaborate techniques were not appropriate for this exploratory study. Table VI1 presents pollutant source-strength results for selected organic pollutants emitted from the well-tuned radiant and maltuned convective heaters. Although the table contains more information than can be discussed here, two topics are of particular interest: the differences in relative source strengths among the three test/sample categories and the PAH emissions. There is a striking difference in relative source strengths between the RAD-1, -2, -4,and -5 tests and the RAD-3 test. The alkylbenzene emissions from the RAD-3 test were much greater than those from the other radiant heater tests, whereas the aliphatic hydrocarbon and aliphatic ketone emissions from the RAD-1, -2, -4, and -5 tests were much greater than those from the RAD-3 test. All five radiant heater tests were experimentally identical, yet the relative emission rates of many compounds observed from the RAD-3 test are dramatically different from the other
Table VII. Selected Organic Pollutant Emission Rates from Well-Tuned Radiant and Maltuned Convective Kerosene Space Heater
compound class PAH naphthalene XAD-2 filter C2, naphthalene (filter only) C3, naphthalene (filter only) phenanthrene (XAD only) fluoranthene XAD-2 filter anthracene (filter only) chrysene (filter only) indeno[ cd]pyrene (filter only) alkylbenzenes XAD-2 filter pentachlorophenol XAD-2 filter phthalates XAD-2 filter hydronaphthalenes decalin (XAD-2 only) C2, decalin (XAD-2 only) C1, tetralin XAD-2 filter aliphatic hydrocarbons XAD-2 filter aliphatic alcohols XAD-2 filter aliphatic ketones XAD-2 filter benzoic acids (filter only) aromatic acid (XAD-2 only) fatty acids (filter only) esters (filter only) miscellaneous C1, cyclohexane (XAD-2 only) C2, methoxybenzene (XAD-2 only) C2, ethenylbenzene (XAD-2 only) (chloropheny1)ethanone (XAD-2 only) acridene (filter only) methylpropoxybenzene (filter only) aliphatic amine (filter only)
emission rates,’ ng/kJ RAD-1, -2, RAD-3 MCON-1, -2 -4, -5
8.0 nda nd
33 nd nd
3 20 4
0.2
nd
0.7
0.3
2
0.9
nd 0.02 nd
0.1 0.01 nd
nd 0.3 0.3
0.01
nd
nd
nd
0.02
nd
13 0.3
8700 nd
120 2
5 0.05
7 0.2
nd 130
170 1
470 3
510 220
43
150
3
260
930
270
100 nd
240 nd
170 23
220 1
nd 0.9
420 200
1400 0.8
700 5
710 85
96 nd 0.3
nd 0.2 nd
650 nd nd
nd
nd
91
2
3
32
0.9
2
28
nd
75
nd
420
nd
nd
nd
96
nd
nd
nd
40
nd
nd
0.2
nd
nd
8
nd
nd
29
and, none detected.
radiant tests. This appears to imply that small changes in combustion conditions can result in large changes in
pollutant emission rates. The comparison of the convective-test emissions of many compounds with those of the radiant tests reveals both similarities and differences. The PAH, phthalate, and aliphatic alcohol emissions for the radiant and convective tests are quite similar, yet the aliphatic ketone and, particularly, the pentachlorophenol (PCP) emissions are much greater in the convective tests than in the radiant tests. With regard to PCP emissions, tests were conducted on the kerosene for trace amounts of chlorinated compounds using a GC/MS technique (20). The results showed that concentrations of chlorinated compounds were below the detection limit of 10 ppm (20). However, ambient chlorine was present in the form of airborne sea salt, and methylene chloride was used near the outside of the chamber before and after the experiments were conducted. Since pentachlorophenol was used as a calibration standard for this analysis and some pentachlorophenol was emitted during the radiant heater tests, we must conclude that the convective heater pentachlorophenol source strength presented in Table VI1 is valid, although how such a compound could be produced in a kerosene flame is somewhat puzzling. Higher levels of acidic compounds such as ketones, acids, and esters were emitted from the maltuned convective heater than from the well-tuned radiant heater. This result is expected since such acidic compounds are indicative of incomplete combustion. Also of interest is the observation that many SVOCs were trapped by the soot-laden filter during the maltuned convective tests. Relatively few PAHs were observed to be emitted by the kerosene heaters with the very broad GC/MS scanning technique employed in this study. Other PAHs would probably be found by a more sensitive technique. Our analysis shows naphthalene to be the primary PAH emission from kerosene heaters. Emissions of fluoranthene and indeno[cd]pyrene, two slightly mutagenic compounds (8,21),were also found. Previous research from a turbulent-diffusion, continuous-flow kerosene combuster showed that 18 nonvolatile or particle-bound PAHs were emitted, with naphthalene accounting for only 3% of the particlebound PAHs (8). The earlier study also found that relatively few PAHs (perylene, cyclopenta[cd]pyrene, and fluoranthene) accounted for almost all of the indirect mutagenic activity of the kerosene heater soot. Of those mutagenic compounds, only fluoranthene was also observed in this study. A more specific study of PAH emissions using more sensitive techniques is warranted.
Conclusions This study has confirmed the results of other studies, that is, that the kerosene combustion process can emit PAHs and nitrated PAHs. In addition, kerosene heaters were found to emit many other organic compounds including aliphatic hydrocarbons, alcohols, and ketones; phthalates; and alkylbenzenes. Pollutant emission rate results, such as those presented here, need to be incorporated into air pollution exposure assessment models. Exposure assessments can then be combined with health effects data to determine the risk associated with exposure to these organic compounds. PAH and nitrated-PAH emissions are sufficiently important to justify additional quantitative studies; furthermore, examinations of other organic compounds of toxicologial significance and of other combustion sources are warranted. This study revealed that the indoor reactivity rates of some SVOCs were near 2 h-l. This implies that reactivity rates for some SVOCs may be more important than typical residential air-exchange rates for determining indoor Environ. Sci. Technol., Vol. 24, No. 8, 1990
1289
concentrations. Therefore, future studies must quantify the indoor reactivity process for individual SVOCs to allow a better understanding of and quantification of indoor exposures to these compounds.
(10) Turk A. ASHRAE J . 1963,5, 55-58. (11) Traynor, G. W.; Girman, J. R.; Apte, M. G.; Dillworth, J.
Acknowledgments
(13)
We thank J. Crum, B. Henschel, J. Lewtas, D. Sanchez, and J. White of the U.S.Environmental Protection Agency (Research Triangle Park, NC); W. Gutknecht of the Re-
(14)
search Triangle Institute (Research Triangle Park, NC); and A. Carruthers and J. McCann of the Lawrence Berkeley Laboratory for their assistance during various phases of this project.
(12)
(15) (16)
(17)
Literature Cited (1) Yamanaka, S.; Hirose, H.; Takaoa, S. Atmos. Environ. 1979, 13, 407-412. (2) Leaderer, B. P. Science 1983,218, 1113-1115. (3) Ryan, P. B.; Spengler, J. D.; Letz, R. Atmos. Environ. 1983, 17, 1339-1345. (4) Traynor, G. W.; Allen, J. R.; Apte, M. G.; Girman, J. R.; Hollowell, C. D. Environ. Sci. Technol. 1983,17,369-371; Environ. Sci. Technol. 1985, 19, 200, addendum. (5) Lionel, T.; Martin, R. J.;Brown, N. J. Environ. Sci. Technol. 1986, 20, 78-85. (6) Prado, G. P.; Lee, M. L.; Hites, R. A.; Hoult, D. P.; Howard, J. B. Proceedings of the 16th International Symposium on Combustion; T h e Combustion Institute: Cambridge, MA, 1973; p p 649-661. (7) Skopek, T. R.; Liber, H. L.; Kaden, D. A.; Hites, R. A,; Thilly, W. G. JNCI, J. Natl. Cancer Inst. 1979,68,309-312. (8) Kaden, D. A.; Hites, R. A.; Thilly, W. G. Cancer Res. 1979, 39, 4152-4159. (9) Tokiwa, T.; Nakagawa, R.; Horikawa, K. Mutat. Res. 1985, 157, 39-47.
1270
Environ. Sci. Technol., Vol. 24, No. 8, 1990
F.; White, P. D. J . Air Pollut. Control Assoc. 1985, 35, 231-237. Traynor, G. W.; Anthon, D. W.; Hollowell, C. D. Atmos. Enuiron. 1982, 16, 2979-2987. Alzona, J.; Cohen, B. L.; Rudolph, H.; Jow, H. N.; Frohliger, J. 0. Atmos. Enuiron. 1979, 13, 55-60. Dockery, D. W.; Spengler, J. D. Atmos. Environ. 1981, 15, 335-343. Mumford, J. L.; Harris, D. B.; Williams, K.; Chuang, J. C.; Cooke, M. Environ. Sci. Technol. 1987, 21, 308-311. Lentzen, D. E.; Wagoner, D. E.; Estes, E. D.; Gutknecht, W. S. IERL-RTP Procedures Manual: Level 1 Environmental Assessment, 2nd ed.; EPA-600/7-78-201; U.S.Environmental Protection Agency: Research Triangle Park, NC, 1978. Nishioka, M. G.; Petersen, B. A.; Lewtas, J. In Polynuclear
Aromatic Hydrocarbons: Chemical Analyses and Biological Fate; Cooke, M., Dennis, A. J., Fisher, G. L.; Eds.; Battelle Press: Columbus, OH, 1982; pp 603-612.
(18) Howard, J. B.; Longwell, J. P. In Polynuclear Aromatic Hydrocarbons: Formation,Metabolism and Measurement; Cooke, M., Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1983; pp 27-62. (19) Rosenkranz, H. S.; Mermelstein, R. J. Environ. Sci, Health 1985, C3,221-272. (20) Carter Analytical Laboratory, Inc., Campbell, CA. (21) National Research Council Polycyclic Aromatic Hydrocarbons: Evaluation of Sources and Effects, National Academy Press: Washington, DC, 1983; p A-14.
Received for review February 28,1989. Accepted March 9,1990. The project was funded by the U S . Environmental Protection Agency (EPA)under Interagency Agreement D W89930753-01 through the U S . Department of Energy under Contract No. DE-AC03-76SF00098. Although funded by the EPA, the research described here does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.
