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Impact of kerosene space heaters on indoor air quality
Chemosphere xxx (2015) xxx–xxx
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Impact of kerosene space heaters on indoor air quality B. Hanoune ⇑, M. Carteret 1 Physicochimie des Processus de Combustion et de l’Atmosphère (PC2A), UMR 8522 CNRS/Lille 1, Université Lille 1 Sciences et Technologies, Cité Scientifique, Villeneuve d’Ascq, France
h i g h l i g h t s Kerosene space heaters are sources of indoor air contaminants. Their impact on IAQ is higher than any other source. NO2 and CO2 levels exceed the guideline values during operation. Average CO2 and NOx levels are correlated with the duration of use. Kerosene heaters also produce ultrafine particles and VOCs.
a r t i c l e
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Article history: Received 2 July 2014 Received in revised form 15 October 2014 Accepted 18 October 2014 Available online xxxx Handling Editor: Caroline Gaus Keywords: Kerosene heaters Indoor air quality Gaseous emissions Particles
a b s t r a c t In recent years, the use of kerosene space heaters as additional or principal heat source has been increasing, because these heaters allow a continuous control on the energy cost. These devices are unvented, and all combustion products are released into the room where the heaters are operated. The indoor air quality of seven private homes using wick-type or electronic injection-type kerosene space heaters was investigated. Concentrations of CO, CO2, NOx, formaldehyde and particulate matter (0.02–10 lm) were measured, using time-resolved instruments when available. All heaters tested are significant sources of submicron particles, NOx and CO2. The average NO2 and CO2 concentrations are determined by the duration of use of the kerosene heaters. These results stress the need to regulate the use of unvented combustion appliances to decrease the exposure of people to air contaminants. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Kerosene space heaters are combustion devices relying on liquid fuel. They are cheap (100–200 €, with some models up to 1000 €), unvented, lightweight, small-size heaters, providing a fast heat. Wick-type kerosene heaters do not require an electrical outlet, whereas injection type heaters have to be plugged to such an outlet, or can run on batteries. Kerosene heaters can be installed in any location, and be easily moved, so as to provide an additional or temporary heat source where the user needs it. They are therefore particularly suited to heat places which are not connected to a central heating system, such as outhouses, garages or workshops. They are also increasingly found, in Northern France or Belgium, in shops and restaurants during wintertime. However, the main reason why kerosene heaters are used (Carteret, 2012;
⇑ Corresponding author. Tel.: +33 3 20 43 40 67. E-mail address: [email protected] (B. Hanoune). Present address: Laboratoire de Chimie Moléculaire et Environnement (LCME), Université de Savoie, 73000 Chambéry, France. 1
Salthammer, 2013) is linked to fuel poverty, because they are much cheaper than a standard central heating system, and provide heat only where it is needed. In addition, their fuel tanks capacity is limited to a few liters, and the users have to refill them regularly and have therefore real-time feedback over the actual cost of heating. Because kerosene heaters are unvented appliances, the combustion products build up in the room during their use, in case of insufficient ventilation. As fuel poverty is usually associated with poorly thermally insulated dwellings, people tend to close all vents so as to retain the heat. This results in increased dampness of the dwelling, possibly leading to damages to the structure of the building. For this reason, kerosene heaters are usually forbidden in many French places such as university dorms or low income housing, though their use in such locations is often reported. It is therefore quite difficult to ascertain to what extent kerosene heaters are used, as people do not voluntarily admit to using such a device. It is estimated, based on cases reported by social workers and in two field studies of indoor pollution in Northern France (Schadkowski, 2003; Chambon and Schadkowski, 2004), that kerosene space heaters are used in 10% of French households. These
http://dx.doi.org/10.1016/j.chemosphere.2014.10.083 0045-6535/Ó 2014 Elsevier Ltd. All rights reserved.
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studies also reported that the daily average duration of use is 9 h, with a maximum of 22 h, well above the recommended duration (2 h d 1). They also put in evidence that the use of kerosene heaters is linked with elevated CO concentrations, possibly resulting in chronic CO poisoning. Few studies have investigated the emissions induced by kerosene space heaters, and their impact on indoor air quality. Nitrogen oxides NO and NO2, sulfur dioxide SO2, and carbon oxides CO and CO2 were identified in the emissions from kerosene heaters (Yamanaka et al., 1979; Leaderer, 1982; Tu and Hinchliffe, 1983; Lionel et al., 1986; Zhou and Cheng, 2000), as well as many organic compounds, such as carbonyl compounds (Traynor et al., 1983), aliphatic alkanes and mono- and poly-aromatic compounds, including nitro-PAHs (Mumford et al., 1991; Bozzelli et al., 1995). Particulate matter is also emitted (White et al., 1987; Traynor et al., 1990), with some mutagenic species, especially nitropyrene derivatives (Tokiwa et al., 1987; Kinouchi et al., 1988). In addition to the continuous emissions during use of the heater, a transient emission of air toxics is reported when the heater is turned on or off (Woodring et al., 1985). In particular, there is a spike in ultrafine particles (<100 nm aerodynamic diameter) that progressively coagulate into coarser particles during the continuous operation of the heater (Carteret et al., 2010). Gaseous pollutants emission factors were recently determined in laboratory experiments, using the different heater types and fuels currently available in Northern France (Carteret et al., 2012). This study confirmed that NOx, CO2 and CO are the main gaseous pollutants emitted by kerosene space heaters. SO2 emissions were found to be negligible. Carbonyl compounds (formaldehyde, acetaldehyde, acetone) were identified, as well as 50 other VOCs, six of which presenting a risk for human health (1,3-butadiene, benzene, ethylene, propene, isobutene and acetylene). This study also put in evidence the accumulation of soot on wick heaters after a few hours of operation, concomitant with increasing CO emissions, which might explain the reported chronic and acute CO poisonings. In the present paper we investigate the impact of kerosene space heaters emissions on indoor air quality in 7 private homes in the Lille (Northern France) area, where these heaters are used as the primary or supplemental source of heating.
Mesures, France), with a 1-min time resolution. Carbon monoxide (CO) was measured with a 1-min time resolution using a Dräger Pack III probe (Drägerwerk AG & Co., Allemagne). In the first six dwellings, NO2 and NOx were sampled with passive samplers (Ogawa & Co, USA), which were analyzed by visible spectrophotometry at 545 nm, after reaction with a color producing reagent (sulfanilamide and N-(1-Naphthyl)-ethylenediamine dihydrochloride). The estimated accuracy is 10%. In dwelling #7, three NO2 sensors were used (Cairpol, France, 0–250 ppb and 0–1000 ppb range, estimated limit of quantification of 4 ppb, possible interferences with ozone and other oxidant species), as well as an online NOx analyzer (Thermo Scientific model 42i). VOCs were sampled in dwellings 1–6 using passive diffusive GABIE samplers (TECORA, France), that were chemically desorbed with CS2 and analyzed by gas chromatography with mass spectrometer and flame ionization detection. The estimated accuracy is 10%. Formaldehyde was sampled in dwellings 1–6 using passive UMEx 100 samplers (Tecora, France) (four days in dwelling #5), and analyzed with the standard HPLC method with UV detection at 365 nm (OSHA Method 1007). The estimated accuracy is 20%. In dwelling #7, online CO and SO2 analyzers (Thermo Scientific, models 48i and 43i) were also employed, as well as a handheld particle counter (Lighthouse HH3016IAQ, size range 0.3–10 lm) and a submicron particle counter (TSI P-Trak, 0.02–1 lm). Only one kerosene space heater was used during experiments in each dwelling. Whenever possible, all the measuring instruments were in the same room as the kerosene heater, a few meters from the heater, and away from any other potential pollution source, about 1 m above the ground. In that way, the measured concentrations can be directly related to the exposure of a sitting person or a standing child. In dwelling #1, the room adjacent to the one with the heater was also instrumented, so as to check for dispersion of the pollutants throughout the house. In dwelling #2, the heater was located in a hallway, but the instruments were installed in the living room. All the activities possibly influencing the air quality during the measurements were documented with questionnaires filled in by the occupants of the dwellings, and with open enquiries after the measurement period.
3. Results and discussion 2. Materials and methods The measurements were carried out in six individual dwellings, five in France and one in Belgium. They were selected on a voluntary basis of the occupants, and cannot therefore be considered representative of the French house panel (Kirchner et al., 2008). The heaters used in these households cannot also be considered representative of the heaters available in France. However, only few models are available, and it was shown (Carteret et al., 2012) that the emission factors of wick- and injection-type heaters are comparable. Additional measurements were carried out in one semi-detached private house (dwelling #7), with the kerosene heaters and fuels previously used in the laboratory experiments (Carteret et al., 2012). These dwellings were located in urban or suburban areas, away from high traffic or industrial emissions. The characteristics of the dwellings and heaters are summarized in Table 1. The reported room volume is approximate, because of unclear boundaries in the case of open space living rooms, or when the room opens on a staircase. The ventilation rates, of 0.5–0.6 h 1, estimated from the CO2 decay curves after extinction of the kerosene heaters, are typical for French dwellings (Kirchner et al., 2008). Environmental parameters (T, RH) and carbon dioxide (CO2) concentration were measured with a HD37B17D probe (ATC
Average daily duration of use of the heaters, calculated from the activity statement questionnaire, ranged from 2 to over 10 h. This covers widely different usage patterns, with some users leaving the heater on for long periods of time, even in their absence, in spite of the safety advice from the kerosene heaters manufacturers. Oppositely, some people only use their heater for short periods of time (less than ½ h each time). It is to be noticed than though kerosene heaters are intended as auxiliary heat sources, in two dwellings (#4 and #5) they are reported as the main source of heat. Moreover, in dwellings #1 and #2, the average daily duration of use of the kerosene heater is longer than the duration of use of the selfreported main heat source (coal stove and wood stove respectively). The environmental parameters (CO2, T and RH) in each dwelling are presented in Table 2. Time dependent CO2, CO and H2O data in one of the dwellings are presented in Fig. 1. Also presented on the graphs are the specific activities which could influence the CO, CO2, and H2O concentrations (cooking, window opening, use of open wood-burning fireplace, smoking). The data for the other dwellings are available in supplementary figures. There is a strong agreement between the observed CO2 concentrations and the questionnaires reporting the use of the heater and the other activities. This validates that the questionnaires were
Please cite this article in press as: Hanoune, B., Carteret, M. Impact of kerosene space heaters on indoor air quality. Chemosphere (2015), http://dx.doi.org/ 10.1016/j.chemosphere.2014.10.083
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B. Hanoune, M. Carteret / Chemosphere xxx (2015) xxx–xxx Table 1 Overview of the kerosene heaters and dwellings included in this study. Dwelling
#1
#2
#3
#4
#5
#6
#7
Kerosene heater
Zibro Kamin Laser 156 Electronic 1900 19
Equation S29D, DTN France
Tectro R253C
Tayosan SRE 4600
Zibro SRE 71X
Zibro Kamin SRE 176
Tayosan 263/Zibro SRE 25 E
Wick 2700 –
Wick 2200 –
Electronic 3000 20
Electronic 1900 19
Electronic 2380 20
Wick/electronic 2400/2700 23
8 Standard
10–12 Standard
5 Standard
5 Standard (purchased in Belgium, so higher sulfur content)
2 Low aromatic compounds (<1%)
Home office 71 0.5
Hallway
Living room
Living room
3 Standard (purchased in Belgium, so higher sulfur content) Living room
200 0.6
Living room 206 0.6
10 Standard (purchased in Belgium, so higher sulfur content) Living room
113 0.5
188 0.5
104 0.5
94
Closed pellet stove (living room)
Electric heating (every room) ; closed fireplace (living room)
Closed coal stove (living room)
Electric heater (bedroom); closed wood stove (living room)
Electric heater (every room); closed fireplace (living room)
Gas central heating
Gas central heating
Gas
Electric
Gas
Gas
Gas
Electric
Electric
Injection type Power (W) Temperature setpoint (°C) Stove age (years) Fuel type
Heater location Room volume (m3) Ventilation rate (h 1) Other heating devices (declared as main heating source) Cooking range
Table 2 Environmental parameters. Dwelling
#1 #2 #3 #4 #5 #6 #7
Monitoring duration (days)
7 7 7 7 4 7 3
Outside temperature (°C)
CO2 concentration (ppm)
Temperature (°C)
Average ± S.D.
Average ± S.D.
Min/max
Average ± S.D.
Min/max
Relative humidity (%) Average ± S.D.
Min/max
6.3 ± 3.5 0.1 ± 3.1 6.4 ± 4.1 3.7 ± 2.2 4.6 ± 2.5 5.0 ± 3.1 10.2 ± 2.0
1082 ± 810 1596 ± 837 900 ± 422 1714 ± 960 1092 ± 786 1173 ± 992 1053 ± 1036
440–3260 650–3490 500–2765 500–3270 450–3265 500–4430 305–4429
16.1 ± 2.6 19.9 ± 1.7 19.0 ± 1.5 19.1 ± 2.0 14.8 ± 2.6 19.1 ± 1.7 20.4 ± 1.1
10.9–22.4 16.8–25.0 14.4–22.2 15.4–23.0 11.2–21.1 15.1–23.0 17.7–23.7
63 ± 3 38 ± 7 49 ± 2 47 ± 3 54 ± 3 49 ± 5 45 ± 2
52–70 27–52 43–55 40–56 49–62 40–68 38–52
Dwelling #2
[CO2](ppm) [CO]/2 (ppb) 7000
[H2O] (molecule.cm-3) 5E+17 cooking
6000 4E+17 5000
fireplace use 3E+17
4000
3000
2E+17 smoking
2000
1E+17 1000
0 25-Jan
0E+00 26-Jan
27-Jan
28-Jan
29-Jan
30-Jan
31-Jan
1-Feb
Fig. 1. Carbon monoxide, carbon dioxide and water concentrations in dwelling 2. Gray areas indicate the self-reported use of the kerosene heater. Purple triangles indicate cooking events. For clarity, [CO] concentrations have been divided by 2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
correctly filled in. All the CO2 pollution events (>1000 ppm, recommendation level of the French ANSES agency) can be ascribed to combustion sources: kerosene heater, gas stove cooking, smoking. The use of the kerosene heater is at the origin of all the high CO2 (>2500 ppm) pollution events. The other activities, such as the
use of a wood-burning fireplace, smoking or cooking, have also a small but noticeable impact on the CO2 concentrations. Maximal CO concentrations (Table 3) in dwellings with a wicktype heater (dwellings #2 and #3) are higher (up to 13 ppm) than the concentrations in dwellings with an injection heater (0–
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Table 3 Measured CO, NOx, and HCHO concentrations. Dwelling
Monitoring duration (days)
Maximal CO concentration (ppm)
NO2 average concentration (ppb)
NOx average concentration (ppb)
HCHO average concentration (ppb)
Other VOC detected
#1 (injection)
7
0
Office: 96 ± 7 (3 replicate samplings) Adjacent living room 64 ± 9 (3 replicate samplings)
237 ± 14
10
155 ± 20
7
Toluene, ethylbenzene, xylenes Ethylbenzene, xylenes
#2 (wick)
7
13
38 ± 3 (2 replicate samplings)
64 ± 7
12
Toluene, xylenes
#3 (wick)
7
6
16
54
8
Toluene, octane, xylenes, nonane
#4 (injection)
7
2
118
716
7
Toluene, xylenes, a-pinene
#5 (injection
4
0
33
271
8
No data
#6 (injection)
7
No data
31
186
8
Trichlorethylene, toluene, octane, xylenes, nonane
#7 (wick/injection)
3
3
No data
No data
2 ppm). This agrees with the laboratory results (Carteret et al., 2012), where it was shown that CO results both from an incomplete combustion in the flame developing from the wick and from the reburning of the soot deposited on the walls of the combustion chamber. In dwelling #2, CO is also associated to the use of the wood-burning fireplace, and the respective contributions of the two emitters are not easily distinguished. The measured 1-h moving average levels show a maximum of 12 ppm, below the shortterm WHO indoor air guideline value of 30 ppm (WHO, 2010). The CO levels reported in previous studies in dwellings with kerosene heaters were higher, with a maximum of 18 ppm in Leaderer et al. (1984), of 40 ppm in Tamura (1987) and of 100 ppm in Amitai et al. (1998), where such levels were associated with smaller rooms. The 8-h or 24-h moving averages (resp. 8 and 7 ppm) in our study are close to the WHO guidelines values of 9 and 6 ppm. Low values with a maximum of 2 ppm were also measured in dwelling #4 but are associated to outdoor sources. Because the measurements were performed in living rooms isolated from the kitchens, no CO spikes have been associated with the use of a gas cooker, contrary to the observations of Tan et al. (2013), who have shown that gas cookers can be significant emitters of CO in kitchens, as well as of PM2.5 and NO2. NOx concentrations in the six first dwellings investigated are presented in Table 3. These values are comparable to the ones previously reported in real dwellings or in simulated conditions, with NO2 concentrations ranging from 20 to 65 ppb in average (Leaderer et al., 1986; Kawamoto et al., 1993; Ruiz et al., 2010). Daily average NOx concentrations were not calculated in the case of dwelling #7 because of the use of two heaters with different injection systems, and because temporal profiles were available (Fig. 2) for this dwelling. The data from the NO2 sensors agree with the data from the online analyzer. These data confirm that indoor NO and NO2 levels can be attributed to the use of the kerosene heaters. No other event has been identified leading to elevated NO2 concentrations, except two periods in the evenings of the first two days, corresponding to the opening of the windows. The maximal NO2 concentrations during these periods, of 30 ppb, is comparable to the outdoor NO2 level, whereas the use of the kerosene heaters leads to higher concentrations in the room, of 80 ppb (wick heater), or over 200 ppb (injection heater), twice the 1-h WHO indoor air guideline (WHO, 2010). NO2 concentration does not reach a plateau and would probably still increase should the heater continue to operate. At the same time, NO concentration increases up to 200 ppb in the case of the wick heater, and up to around 700 ppb for the injection heater. This difference between the two types of heater is in accor-
dance with previous laboratory results (Carteret et al., 2012), which indicated that the emission factors of NOx is about 3 times higher with injection heaters than with wick heaters. SO2 concentrations, measured only in dwelling #7, present the same temporal profiles as the nitrogen oxides concentrations. SO2 concentrations range from 1 ppb when the heater is not in use, to 13.7 ppb when using the heater. These concentrations are lower than the ones reported in previous studies (up to 400– 800 ppb) (Caceres et al., 1983; Cooper and Alberti, 1984; Leaderer et al., 1984), because of the lower sulfur content now allowed in the fuel. Formaldehyde concentrations, given in Table 3 together with the VOCs that were identified, ranged from 7 to 12 ppb, comparable to the long-term exposure recommendation in France of 8 ppb (Salthammer et al., 2010). These values are also in accordance with the previous measurements in real environments (Leaderer et al., 1986). Submicron particulate counts in dwelling #7 are presented in Fig. 3. Only the kerosene heaters have been identified as a source for these particles. Particles in the range 0.3–0.5 lm and to a smaller extent 0.5–1 lm are also produced by another source, which has been identified as a bread toaster located in the adjacent kitchen. The submicron particles produced by the heater eventually coagulate, resulting in a slow increase in coarser particles. Particles up to PM1.0 are produced almost exclusively from the kerosene heaters. Particles of larger diameter are also produced when using the heaters, but other sources are present. The high concentration of PM2.5 and PM5.0 at the end of the second day is not related to the use of the kerosene heater, and has not been identified, which stresses the limits of the questionnaires filled by the occupants. The maximal value for PM2.5 is 29.3 lg m 3, and the average value 7.3 lg m 3, below the WHO chronic exposure guideline of 10 lg m 3. Due to the difference in the pattern of use and in the size of the rooms, the measured particle concentrations cannot be compared to the previous studies (Mumford et al., 1991; Leaderer et al., 1999; Ruiz et al., 2010), even though these three studies pointed out that the use of kerosene heaters induces an increase in the PM2.5 concentrations compared to houses without kerosene heaters. For instance, in Leaderer et al. (1999) the kerosene heaters were estimated to add 40 lg m 3 of total PM2.5 to the indoor air. CO2 temporal variations in Fig. 1 are associated mainly with the use of the kerosene heater, and CO2 can be used as a proxy to determine when the heater is fired, so as to make sure that the questionnaires were correctly filled. Time resolved NOx measurements can
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B. Hanoune, M. Carteret / Chemosphere xxx (2015) xxx–xxx
NOx (ppb) 800 NO2 online NO2 sensor #1 NO2 sensor #2 NO2 sensor #3 NO
700 600 500 400 300
1-hour WHO guideline (105 ppb)
200
toaster use
Electronic heater
100
Wick heater
Wick heater
0
15-May
16-May
16-May
17-May
17-May
Fig. 2. Time resolved NOx concentrations in dwelling #7. Gray areas indicate the use of the kerosene heater.
PM mass concentraon (μg.m-3) 100 90 80
ultrafine parcles (#.cm-3) 500000
PM0.5 PM1.0 PM2.5 PM5.0 0.02-1.00 μm
450000 400000
70
350000
60
300000
50
250000 200000
40 toaster u
30
150000
20
100000
10
50000
0 15-May
0 16-May
16-May
17-May
17-May
Fig. 3. PM counts in dwelling #7. Gray areas indicate the use of the kerosene heater.
also be used as a proxy for the use of the heater, as seen from the measurements in dwelling #7 (Fig. 2). The average concentrations of CO2 and of NOx are presented in Fig. 4 as a function of the daily duration of use. The average CO2 concentration, up to 1700 ppb, is linearly correlated to the duration of use. The average NO2 concentrations are also correlated to the duration of use, in spite of the high uncertainty on the passive sampling measurements. In addition, we have to distinguish between the wick-type or electronic injection heaters. Only NO presents one clear outlier, in the case of dwelling #4, with a daily average value of about 600 ppb, for which no explanation can be found. This correlation between the average CO2 or NO2 concentration and the daily average duration of use of the heaters holds true even though the average concentration of the gases takes into account the slow decrease of the gas concentration after the heater is turned off, due to the ventilation of the room. In addition, many potential parameters are not included in the analysis, such as the size of the room, the pattern of use of the heater, or the heating power. A correction for the power of the heater would be feasible for wick-type heaters, but not for electronic injection heaters, because these devices are fitted with a regulation system adapting the fuel consumption to the difference between the setup temperature and the actual temperature. This analysis makes also no
assumption regarding the well-mixed state of the air inside the room, the exchange with air from the outside or the other rooms during use of the heater, or the various sinks for the pollutants such as the reactions on surfaces. This confirms that all the other potential emission sources, from outdoor or indoor, are negligible compared to the emissions of the kerosene heaters. In the dwellings investigated, the other sources that have been identified, in addition to smoking, cooking, and the presence of people in the room, are wood burning appliances (closed pellet stove in dwelling #1, closed wood stove in dwelling #4, closed fireplaces in dwellings #2 and #5), and a closed coal stove in dwelling #3. There are no emissions associated with the gas central heating systems, because the combustion gases from the boiler are normally vented to the outdoor through well-insulated sealed ducts, with no impact on indoor pollutants concentrations (Tan et al., 2013). The emissions from the gas cookers, used in dwellings #1 and #3, are also negligible compared to the emissions from the kerosene heaters. For instance, the CO2 level increase associated with the cooking periods in dwelling #1 is only 200 ppm. As a comparison point, an increase of about 1500 ppm was reported in a kitchen during use of a gas cooking range (Tan et al., 2013). Our measurements were however not performed in the kitchen but in the living room, which might explain
Please cite this article in press as: Hanoune, B., Carteret, M. Impact of kerosene space heaters on indoor air quality. Chemosphere (2015), http://dx.doi.org/ 10.1016/j.chemosphere.2014.10.083
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Fig. 4. Average concentrations of CO2 and NOx vs. average daily duration of use of the kerosene heater. For clarity, NO2 concentrations have been multiplied by 4.
the smaller increase that we observed. In addition, the emissions from cooking devices tend to be attenuated with the generalized use of a range hood, which has been stressed by Nazaroff (2013) as an effective means of managing the indoor emissions from cooking. In dwelling #3, no CO or CO2 emissions associated with the use of the coal stove have been detected. Using coal for heating in Western Europe is now marginal, and no recent data is available, so this kind of heater will not be discussed here. Much more widespread, and increasing, is the use of wood burning appliances (Salthammer et al., 2014), such as the ones encountered in our present study (pellet stove, fireplace, wood stove). However, because all these systems were closed sources, only low concentrations of air contaminants are usually observed. For instance, it has been reported (Johansson et al., 2004) that the emissions from pellet stoves, in particular NO2 emissions (Gillespie-Bennett et al., 2008), are low compared to emissions from burning wood logs. In particular, as these stoves are automatically filled, there is no need to open the fire chamber. This manual refilling of wood burning ovens is at the origin of a temporary increase in particles and gaseous pollutants (Salthammer et al., 2014). In this latter study on the impact of modern wood-burning ovens on indoor air quality, it was shown that using these combustion devices has a noticeable but rather limited impact on indoor air quality, with concentrations of carbon oxides, nitrogen oxides and VOCs within the German guideline limits. These results agree with the several previous studies on the reduction of NOx and particulate matter emissions when replacing an open stove with a model where the fire chamber is sealed off from the room air, and where most of the combustion products are evacuated to the outside through a flue (GillespieBennett et al., 2008; Ward and Noonan, 2008).
4. Conclusion The present paper investigated the impact of kerosene heaters on indoor air quality in six dwellings, using the heaters normally used by the occupants. Additional measurements were performed in a seventh dwelling, with the heaters previously used in our laboratory study. All heaters comply with the French regulations, and so do the fuels provided by the occupants, except when the occupants purchased the kerosene in Belgium where the sulfur content can be higher than in France. The patterns of use of the heater vary greatly in the households investigated, with some occupants using it as an additional source of heat, while others make it their principal source of heat. The
average daily use duration ranges between 2 and 10 h, sometimes including periods when no one is present in the room or the house. In spite of the restricted number of houses investigated, which cannot be considered representative of the French dwellings panel, and of the restricted number of heaters under study, we have ascertained that the use of kerosene space heaters has a negative impact on indoor air quality, because kerosene heaters are unvented appliances and all combustion products are directly released into the room. Operation of kerosene space heaters induces an instantaneous increase in the CO2, NO, NO2 and submicron particles, which can be distinguished from the emissions of all the other sources in the dwellings. Measured concentration of CO2 during operation, up to 4500 ppm, are above the recommended maximal values (1000–1500 ppm). NO2 concentrations up to 200 ppb were also reached when using an electronic injection type heater for at least 30 min, and prolonged use of such a heater therefore results in an exposure of the users to NO2 levels above the WHO 1-h 105 ppb guideline. H2CO levels were of the order of the proposed long term exposure recommended value of 8 ppb guidelines. Real-time NOx and CO2 concentrations can be used as tracers of the use of kerosene heaters. Even if no time-resolved data are available for these compounds, their average daily concentration can be correlated to the duration of use.
Acknowledgments This work was supported by the ADEME (Agence de l’Environnement et de la Maîtrise de l’Energie) and the Région Nord-Pas-deCalais. PC2A participates in the Institut de Recherche en Environnement Industriel (IRENI) which is financed by the Région Nord-Pasde-Calais, the Ministère de l’Enseignement Supérieur et de la Recherche, the Centre National de la Recherche Scientifique (CNRS), and European Regional Development Fund (ERDF). We thank the Association pour la Prévention de la Pollution Atmosphérique (APPA) for their help in finding the dwellings investigated here.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2014.10.083.
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References Amitai, Y., Zlotogorski, Z., Golan-Katzav, V., Wexler, A., Gross, D., 1998. Neuropsychological impairment from acute low-level exposure to carbon monoxide. Arch. Neurol. 55 (6), 845–848. Bozzelli, J.W., Kebbekus, B., Bobenhausen, C., 1995. Analysis of selected volatile organic compounds associated with residential kerosene heater use. Int. J. Environ. Stud. 49 (2), 125–131. Caceres, T., Soto, H., Lissi, E., Cisternas, R., 1983. Indoor house pollution: appliance emissions and indoor ambient concentrations. Atmos. Environ. 17 (5), 1009– 1013. Carteret, M., 2012. Evaluation de l’exposition des personnes aux polluants issus des chauffages d’appoint au pétrole. PhD. Villeneuve d’Ascq, Université Lille 1. Carteret, M., Hanoune, B., Pauwels, J.F., 2010. Emissions de particules par les chauffages d’appoint à pétrole. Journée technique RSEIN/OQAI ‘‘Les particules dans l’air intérieur’’, Lille (France), INERIS. Carteret, M., Pauwels, J.F., Hanoune, B., 2012. Emission factors of gaseous pollutants from recent kerosene space heaters and fuels available in France in 2010. Indoor Air 22 (4), 299–308. Chambon, C., Schadkowski, C., 2004. Diagnostic de l’impact des feux à petrole sur le monoxyde de carbone dans les logements. Rapport APPA Nord Pas de Calais. Cooper, K.R., Alberti, R.R., 1984. Effect of kerosene heater emissions on indoor air quality and pulmonary function. Am. Rev. Respir. Dis. 129 (4), 629–631. Gillespie-Bennett, J., Pierse, N., Wickens, K., Crane, J., Nicholls, S., Shields, D., Boulic, M., Viggers, H., Baker, M., Woodward, A., Howden-Chapman, P., 2008. Sources of nitrogen dioxide (NO2) in New Zealand homes: findings from a community randomized controlled trial of heater substitutions. Indoor Air 18 (6), 521–528. Johansson, L.S., Leckner, B., Gustavsson, L., Cooper, D., Tullin, C., Potter, A., 2004. Emission characteristics of modern and old-type residential boilers fired with wood logs and wood pellets. Atmos. Environ. 38 (25), 4183–4195. Kawamoto, T., Matsuno, K., Arashidani, K., Yoshikawa, M., Kayama, F., Kodama, Y., 1993. Personal exposure to nitrogen dioxide from indoor heaters and cooking stoves. Arch. Environ. Contam. Toxicol. 25 (4), 534–538. Kinouchi, T., Nishifuji, K., Tsutsui, H., Hoare, S.L., Ohnishi, Y., 1988. Mutagenicity and nitropyrene concentration of indoor air particulates exhausted from a kerosine heater. Jpn. J. Cancer Res. (GANN) 79 (1), 32–41. Kirchner, S., Derbez, M., Duboudin, C., Elias, P., Gregoire, A., Lucas, J.-P., Pasquier, N., Ramalho, O., Weiss, N., 2008. Indoor air quality in French dwellings. Proc. Indoor Air 2008. Leaderer, B.P., 1982. Air pollutant emissions from kerosene space heaters. Science 218 (4577), 1113–1115. Leaderer, B.P., Stolwijk, J.A.J., Zagraniski, R.T., Ma, Q., 1984. A field study of indoor air contaminant levels associated with unvented combustion sources. In: 77th Proc. – APCA Annu. Meet. vol. 2, 84–33.3, 13p. Leaderer, B.P., Zagraniski, R.T., Berwick, M., Stolwijk, J.A., 1986. Assessment of exposure to indoor air contaminants from combustion sources: methodology and application. Am. J. Epidemiol. 124 (2), 275–289. Leaderer, B.P., Naeher, L., Jankun, T., Balenger, K., Holford, T.R., Toth, C., Sullivan, J., Wolfson, J.M., Koutrakis, P., 1999. Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO24 , H+, NH+4, NO3 , NH3, and nitrous acid in homes with and without kerosene space heaters. Environ. Health Perspect. 107 (3), 223–231.
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Lionel, T., Martin, R.J., Brown, N.J., 1986. A comparative study of combustion in kerosine heaters. Environ. Sci. Technol. 20 (1), 78–85. Mumford, J.L., Williams, R.W., Walsh, D.B., Burton, R.M., Svendsgaard, D.J., Chuang, J.C., Houk, V.S., Lewtas, J., 1991. Indoor air pollutants from unvented kerosene heater emissions in mobile homes: studies on particles, semivolatile organics, carbon monoxide, and mutagenicity. Environ. Sci. Technol. 25 (10), 1732–1738. Nazaroff, W.W., 2013. Four principles for achieving good indoor air quality. Indoor Air 23 (5), 353–356. Ruiz, P.A., Toro, C., Caceres, J., Lopez, G., Oyola, P., Koutrakis, P., 2010. Effect of gas and kerosene space heaters on indoor air quality: a study in homes of Santiago, Chile. J. Air Waste Manage. Assoc. 60 (1), 98–108. Salthammer, T., 2013. Formaldehyde in the ambient atmosphere: from an indoor pollutant to an outdoor pollutant? Angew. Chem., Int. Ed. 52 (12), 3320–3327. Salthammer, T., Mentese, S., Marutzky, R., 2010. Formaldehyde in the indoor environment. Chem. Rev. 110 (4), 2536–2572. Salthammer, T., Schripp, T., Wientzek, S., Wensing, M., 2014. Impact of operating wood-burning fireplace ovens on indoor air quality. Chemosphere 103, 205– 211. Schadkowski, C., 2003. Exposition individuelle aux oxydes d’azote et au monoxyde de carbone: premiers résultats de l’étude ‘‘Sentinelles de l’air’’ en région NordPas-de-Calais. Air pur 64, 14–29. Tamura, G.T., 1987. Measurement of combustion products from kerosene space heaters in a two-story house. ASHRAE Trans. 93, 173–184. Tan, C.C.L., Finney, K.N., Chen, Q., Russell, N.V., Sharifi, V.N., Swithenbank, J., 2013. Experimental investigation of indoor air pollutants in residential buildings. Indoor Built Environ. 22 (3), 471–489. Tokiwa, H., Nakagawa, R., Horikawa, K., Ohkubo, A., 1987. The nature of the mutagenicity and carcinogenicity of nitrated, aromatic compounds in the environment. Environ. Health Perspect. 73, 191. Traynor, G.W., Allen, J.R., Apte, M.G., Girman, J.R., Hollowell, C.D., 1983. Notes. Pollutant emissions from portable kerosine-fired space heaters. Environ. Sci. Technol. 17 (6), 369–371. Traynor, G.W., Apte, M.G., Sokol, H.A., Chuang, J.C., Tucker, W.G., Mumford, J.L., 1990. Selected organic pollutant emissions from unvented kerosene space heaters. Environ. Sci. Technol. 24 (8), 1265–1270. Tu, K.W., Hinchliffe, L.E., 1983. A study of particulate emissions from portable space heaters. Am. Ind. Hyg. Assoc. J. 44 (11), 857–862. Ward, T., Noonan, C., 2008. Results of a residential indoor PM2.5 sampling program before and after a woodstove changeout. Indoor Air 18 (5), 408–415. White, J.B., Leaderer, B.P., Boone, P.M., Hammond, S.K., Mumford, J. L., 1987. Chamber studies characterizing organic emissions from kerosene heaters. In: 1987 EPA/APCA Symposium on Measurement of Toxic and Related Air Pollutants. WHO (2010). WHO guidelines for indoor air quality: selected pollutants. WHO regional office for Europe, Copenhagen. Woodring, J.L., Duffy, T.L., Davis, J.T., Bechtold, R.R., 1985. Measurements of combustion product emission factors of unvented kerosene heaters. Am. Ind. Hyg. Assoc. J. 46 (7), 350–356. Yamanaka, S., Hirose, H., Takada, S., 1979. Nitrogen oxides emissions from domestic kerosene-fired and gas-fired appliances. Atmos. Environ. 13 (3), 407–412. Zhou, Y., Cheng, Y.-S., 2000. Characterization of emissions from kerosene heaters in an unvented tent. Aerosol Sci. Technol. 33 (6), 510–524.
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Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Impact of kerosene space heaters on indoor air quality B. Hanoune ⇑, M. Carteret 1 Physicochimie des Processus de Combustion et de l’Atmosphère (PC2A), UMR 8522 CNRS/Lille 1, Université Lille 1 Sciences et Technologies, Cité Scientifique, Villeneuve d’Ascq, France
h i g h l i g h t s Kerosene space heaters are sources of indoor air contaminants. Their impact on IAQ is higher than any other source. NO2 and CO2 levels exceed the guideline values during operation. Average CO2 and NOx levels are correlated with the duration of use. Kerosene heaters also produce ultrafine particles and VOCs.
a r t i c l e
i n f o
Article history: Received 2 July 2014 Received in revised form 15 October 2014 Accepted 18 October 2014 Available online xxxx Handling Editor: Caroline Gaus Keywords: Kerosene heaters Indoor air quality Gaseous emissions Particles
a b s t r a c t In recent years, the use of kerosene space heaters as additional or principal heat source has been increasing, because these heaters allow a continuous control on the energy cost. These devices are unvented, and all combustion products are released into the room where the heaters are operated. The indoor air quality of seven private homes using wick-type or electronic injection-type kerosene space heaters was investigated. Concentrations of CO, CO2, NOx, formaldehyde and particulate matter (0.02–10 lm) were measured, using time-resolved instruments when available. All heaters tested are significant sources of submicron particles, NOx and CO2. The average NO2 and CO2 concentrations are determined by the duration of use of the kerosene heaters. These results stress the need to regulate the use of unvented combustion appliances to decrease the exposure of people to air contaminants. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Kerosene space heaters are combustion devices relying on liquid fuel. They are cheap (100–200 €, with some models up to 1000 €), unvented, lightweight, small-size heaters, providing a fast heat. Wick-type kerosene heaters do not require an electrical outlet, whereas injection type heaters have to be plugged to such an outlet, or can run on batteries. Kerosene heaters can be installed in any location, and be easily moved, so as to provide an additional or temporary heat source where the user needs it. They are therefore particularly suited to heat places which are not connected to a central heating system, such as outhouses, garages or workshops. They are also increasingly found, in Northern France or Belgium, in shops and restaurants during wintertime. However, the main reason why kerosene heaters are used (Carteret, 2012;
⇑ Corresponding author. Tel.: +33 3 20 43 40 67. E-mail address: [email protected] (B. Hanoune). Present address: Laboratoire de Chimie Moléculaire et Environnement (LCME), Université de Savoie, 73000 Chambéry, France. 1
Salthammer, 2013) is linked to fuel poverty, because they are much cheaper than a standard central heating system, and provide heat only where it is needed. In addition, their fuel tanks capacity is limited to a few liters, and the users have to refill them regularly and have therefore real-time feedback over the actual cost of heating. Because kerosene heaters are unvented appliances, the combustion products build up in the room during their use, in case of insufficient ventilation. As fuel poverty is usually associated with poorly thermally insulated dwellings, people tend to close all vents so as to retain the heat. This results in increased dampness of the dwelling, possibly leading to damages to the structure of the building. For this reason, kerosene heaters are usually forbidden in many French places such as university dorms or low income housing, though their use in such locations is often reported. It is therefore quite difficult to ascertain to what extent kerosene heaters are used, as people do not voluntarily admit to using such a device. It is estimated, based on cases reported by social workers and in two field studies of indoor pollution in Northern France (Schadkowski, 2003; Chambon and Schadkowski, 2004), that kerosene space heaters are used in 10% of French households. These
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studies also reported that the daily average duration of use is 9 h, with a maximum of 22 h, well above the recommended duration (2 h d 1). They also put in evidence that the use of kerosene heaters is linked with elevated CO concentrations, possibly resulting in chronic CO poisoning. Few studies have investigated the emissions induced by kerosene space heaters, and their impact on indoor air quality. Nitrogen oxides NO and NO2, sulfur dioxide SO2, and carbon oxides CO and CO2 were identified in the emissions from kerosene heaters (Yamanaka et al., 1979; Leaderer, 1982; Tu and Hinchliffe, 1983; Lionel et al., 1986; Zhou and Cheng, 2000), as well as many organic compounds, such as carbonyl compounds (Traynor et al., 1983), aliphatic alkanes and mono- and poly-aromatic compounds, including nitro-PAHs (Mumford et al., 1991; Bozzelli et al., 1995). Particulate matter is also emitted (White et al., 1987; Traynor et al., 1990), with some mutagenic species, especially nitropyrene derivatives (Tokiwa et al., 1987; Kinouchi et al., 1988). In addition to the continuous emissions during use of the heater, a transient emission of air toxics is reported when the heater is turned on or off (Woodring et al., 1985). In particular, there is a spike in ultrafine particles (<100 nm aerodynamic diameter) that progressively coagulate into coarser particles during the continuous operation of the heater (Carteret et al., 2010). Gaseous pollutants emission factors were recently determined in laboratory experiments, using the different heater types and fuels currently available in Northern France (Carteret et al., 2012). This study confirmed that NOx, CO2 and CO are the main gaseous pollutants emitted by kerosene space heaters. SO2 emissions were found to be negligible. Carbonyl compounds (formaldehyde, acetaldehyde, acetone) were identified, as well as 50 other VOCs, six of which presenting a risk for human health (1,3-butadiene, benzene, ethylene, propene, isobutene and acetylene). This study also put in evidence the accumulation of soot on wick heaters after a few hours of operation, concomitant with increasing CO emissions, which might explain the reported chronic and acute CO poisonings. In the present paper we investigate the impact of kerosene space heaters emissions on indoor air quality in 7 private homes in the Lille (Northern France) area, where these heaters are used as the primary or supplemental source of heating.
Mesures, France), with a 1-min time resolution. Carbon monoxide (CO) was measured with a 1-min time resolution using a Dräger Pack III probe (Drägerwerk AG & Co., Allemagne). In the first six dwellings, NO2 and NOx were sampled with passive samplers (Ogawa & Co, USA), which were analyzed by visible spectrophotometry at 545 nm, after reaction with a color producing reagent (sulfanilamide and N-(1-Naphthyl)-ethylenediamine dihydrochloride). The estimated accuracy is 10%. In dwelling #7, three NO2 sensors were used (Cairpol, France, 0–250 ppb and 0–1000 ppb range, estimated limit of quantification of 4 ppb, possible interferences with ozone and other oxidant species), as well as an online NOx analyzer (Thermo Scientific model 42i). VOCs were sampled in dwellings 1–6 using passive diffusive GABIE samplers (TECORA, France), that were chemically desorbed with CS2 and analyzed by gas chromatography with mass spectrometer and flame ionization detection. The estimated accuracy is 10%. Formaldehyde was sampled in dwellings 1–6 using passive UMEx 100 samplers (Tecora, France) (four days in dwelling #5), and analyzed with the standard HPLC method with UV detection at 365 nm (OSHA Method 1007). The estimated accuracy is 20%. In dwelling #7, online CO and SO2 analyzers (Thermo Scientific, models 48i and 43i) were also employed, as well as a handheld particle counter (Lighthouse HH3016IAQ, size range 0.3–10 lm) and a submicron particle counter (TSI P-Trak, 0.02–1 lm). Only one kerosene space heater was used during experiments in each dwelling. Whenever possible, all the measuring instruments were in the same room as the kerosene heater, a few meters from the heater, and away from any other potential pollution source, about 1 m above the ground. In that way, the measured concentrations can be directly related to the exposure of a sitting person or a standing child. In dwelling #1, the room adjacent to the one with the heater was also instrumented, so as to check for dispersion of the pollutants throughout the house. In dwelling #2, the heater was located in a hallway, but the instruments were installed in the living room. All the activities possibly influencing the air quality during the measurements were documented with questionnaires filled in by the occupants of the dwellings, and with open enquiries after the measurement period.
3. Results and discussion 2. Materials and methods The measurements were carried out in six individual dwellings, five in France and one in Belgium. They were selected on a voluntary basis of the occupants, and cannot therefore be considered representative of the French house panel (Kirchner et al., 2008). The heaters used in these households cannot also be considered representative of the heaters available in France. However, only few models are available, and it was shown (Carteret et al., 2012) that the emission factors of wick- and injection-type heaters are comparable. Additional measurements were carried out in one semi-detached private house (dwelling #7), with the kerosene heaters and fuels previously used in the laboratory experiments (Carteret et al., 2012). These dwellings were located in urban or suburban areas, away from high traffic or industrial emissions. The characteristics of the dwellings and heaters are summarized in Table 1. The reported room volume is approximate, because of unclear boundaries in the case of open space living rooms, or when the room opens on a staircase. The ventilation rates, of 0.5–0.6 h 1, estimated from the CO2 decay curves after extinction of the kerosene heaters, are typical for French dwellings (Kirchner et al., 2008). Environmental parameters (T, RH) and carbon dioxide (CO2) concentration were measured with a HD37B17D probe (ATC
Average daily duration of use of the heaters, calculated from the activity statement questionnaire, ranged from 2 to over 10 h. This covers widely different usage patterns, with some users leaving the heater on for long periods of time, even in their absence, in spite of the safety advice from the kerosene heaters manufacturers. Oppositely, some people only use their heater for short periods of time (less than ½ h each time). It is to be noticed than though kerosene heaters are intended as auxiliary heat sources, in two dwellings (#4 and #5) they are reported as the main source of heat. Moreover, in dwellings #1 and #2, the average daily duration of use of the kerosene heater is longer than the duration of use of the selfreported main heat source (coal stove and wood stove respectively). The environmental parameters (CO2, T and RH) in each dwelling are presented in Table 2. Time dependent CO2, CO and H2O data in one of the dwellings are presented in Fig. 1. Also presented on the graphs are the specific activities which could influence the CO, CO2, and H2O concentrations (cooking, window opening, use of open wood-burning fireplace, smoking). The data for the other dwellings are available in supplementary figures. There is a strong agreement between the observed CO2 concentrations and the questionnaires reporting the use of the heater and the other activities. This validates that the questionnaires were
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B. Hanoune, M. Carteret / Chemosphere xxx (2015) xxx–xxx Table 1 Overview of the kerosene heaters and dwellings included in this study. Dwelling
#1
#2
#3
#4
#5
#6
#7
Kerosene heater
Zibro Kamin Laser 156 Electronic 1900 19
Equation S29D, DTN France
Tectro R253C
Tayosan SRE 4600
Zibro SRE 71X
Zibro Kamin SRE 176
Tayosan 263/Zibro SRE 25 E
Wick 2700 –
Wick 2200 –
Electronic 3000 20
Electronic 1900 19
Electronic 2380 20
Wick/electronic 2400/2700 23
8 Standard
10–12 Standard
5 Standard
5 Standard (purchased in Belgium, so higher sulfur content)
2 Low aromatic compounds (<1%)
Home office 71 0.5
Hallway
Living room
Living room
3 Standard (purchased in Belgium, so higher sulfur content) Living room
200 0.6
Living room 206 0.6
10 Standard (purchased in Belgium, so higher sulfur content) Living room
113 0.5
188 0.5
104 0.5
94
Closed pellet stove (living room)
Electric heating (every room) ; closed fireplace (living room)
Closed coal stove (living room)
Electric heater (bedroom); closed wood stove (living room)
Electric heater (every room); closed fireplace (living room)
Gas central heating
Gas central heating
Gas
Electric
Gas
Gas
Gas
Electric
Electric
Injection type Power (W) Temperature setpoint (°C) Stove age (years) Fuel type
Heater location Room volume (m3) Ventilation rate (h 1) Other heating devices (declared as main heating source) Cooking range
Table 2 Environmental parameters. Dwelling
#1 #2 #3 #4 #5 #6 #7
Monitoring duration (days)
7 7 7 7 4 7 3
Outside temperature (°C)
CO2 concentration (ppm)
Temperature (°C)
Average ± S.D.
Average ± S.D.
Min/max
Average ± S.D.
Min/max
Relative humidity (%) Average ± S.D.
Min/max
6.3 ± 3.5 0.1 ± 3.1 6.4 ± 4.1 3.7 ± 2.2 4.6 ± 2.5 5.0 ± 3.1 10.2 ± 2.0
1082 ± 810 1596 ± 837 900 ± 422 1714 ± 960 1092 ± 786 1173 ± 992 1053 ± 1036
440–3260 650–3490 500–2765 500–3270 450–3265 500–4430 305–4429
16.1 ± 2.6 19.9 ± 1.7 19.0 ± 1.5 19.1 ± 2.0 14.8 ± 2.6 19.1 ± 1.7 20.4 ± 1.1
10.9–22.4 16.8–25.0 14.4–22.2 15.4–23.0 11.2–21.1 15.1–23.0 17.7–23.7
63 ± 3 38 ± 7 49 ± 2 47 ± 3 54 ± 3 49 ± 5 45 ± 2
52–70 27–52 43–55 40–56 49–62 40–68 38–52
Dwelling #2
[CO2](ppm) [CO]/2 (ppb) 7000
[H2O] (molecule.cm-3) 5E+17 cooking
6000 4E+17 5000
fireplace use 3E+17
4000
3000
2E+17 smoking
2000
1E+17 1000
0 25-Jan
0E+00 26-Jan
27-Jan
28-Jan
29-Jan
30-Jan
31-Jan
1-Feb
Fig. 1. Carbon monoxide, carbon dioxide and water concentrations in dwelling 2. Gray areas indicate the self-reported use of the kerosene heater. Purple triangles indicate cooking events. For clarity, [CO] concentrations have been divided by 2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
correctly filled in. All the CO2 pollution events (>1000 ppm, recommendation level of the French ANSES agency) can be ascribed to combustion sources: kerosene heater, gas stove cooking, smoking. The use of the kerosene heater is at the origin of all the high CO2 (>2500 ppm) pollution events. The other activities, such as the
use of a wood-burning fireplace, smoking or cooking, have also a small but noticeable impact on the CO2 concentrations. Maximal CO concentrations (Table 3) in dwellings with a wicktype heater (dwellings #2 and #3) are higher (up to 13 ppm) than the concentrations in dwellings with an injection heater (0–
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B. Hanoune, M. Carteret / Chemosphere xxx (2015) xxx–xxx
Table 3 Measured CO, NOx, and HCHO concentrations. Dwelling
Monitoring duration (days)
Maximal CO concentration (ppm)
NO2 average concentration (ppb)
NOx average concentration (ppb)
HCHO average concentration (ppb)
Other VOC detected
#1 (injection)
7
0
Office: 96 ± 7 (3 replicate samplings) Adjacent living room 64 ± 9 (3 replicate samplings)
237 ± 14
10
155 ± 20
7
Toluene, ethylbenzene, xylenes Ethylbenzene, xylenes
#2 (wick)
7
13
38 ± 3 (2 replicate samplings)
64 ± 7
12
Toluene, xylenes
#3 (wick)
7
6
16
54
8
Toluene, octane, xylenes, nonane
#4 (injection)
7
2
118
716
7
Toluene, xylenes, a-pinene
#5 (injection
4
0
33
271
8
No data
#6 (injection)
7
No data
31
186
8
Trichlorethylene, toluene, octane, xylenes, nonane
#7 (wick/injection)
3
3
No data
No data
2 ppm). This agrees with the laboratory results (Carteret et al., 2012), where it was shown that CO results both from an incomplete combustion in the flame developing from the wick and from the reburning of the soot deposited on the walls of the combustion chamber. In dwelling #2, CO is also associated to the use of the wood-burning fireplace, and the respective contributions of the two emitters are not easily distinguished. The measured 1-h moving average levels show a maximum of 12 ppm, below the shortterm WHO indoor air guideline value of 30 ppm (WHO, 2010). The CO levels reported in previous studies in dwellings with kerosene heaters were higher, with a maximum of 18 ppm in Leaderer et al. (1984), of 40 ppm in Tamura (1987) and of 100 ppm in Amitai et al. (1998), where such levels were associated with smaller rooms. The 8-h or 24-h moving averages (resp. 8 and 7 ppm) in our study are close to the WHO guidelines values of 9 and 6 ppm. Low values with a maximum of 2 ppm were also measured in dwelling #4 but are associated to outdoor sources. Because the measurements were performed in living rooms isolated from the kitchens, no CO spikes have been associated with the use of a gas cooker, contrary to the observations of Tan et al. (2013), who have shown that gas cookers can be significant emitters of CO in kitchens, as well as of PM2.5 and NO2. NOx concentrations in the six first dwellings investigated are presented in Table 3. These values are comparable to the ones previously reported in real dwellings or in simulated conditions, with NO2 concentrations ranging from 20 to 65 ppb in average (Leaderer et al., 1986; Kawamoto et al., 1993; Ruiz et al., 2010). Daily average NOx concentrations were not calculated in the case of dwelling #7 because of the use of two heaters with different injection systems, and because temporal profiles were available (Fig. 2) for this dwelling. The data from the NO2 sensors agree with the data from the online analyzer. These data confirm that indoor NO and NO2 levels can be attributed to the use of the kerosene heaters. No other event has been identified leading to elevated NO2 concentrations, except two periods in the evenings of the first two days, corresponding to the opening of the windows. The maximal NO2 concentrations during these periods, of 30 ppb, is comparable to the outdoor NO2 level, whereas the use of the kerosene heaters leads to higher concentrations in the room, of 80 ppb (wick heater), or over 200 ppb (injection heater), twice the 1-h WHO indoor air guideline (WHO, 2010). NO2 concentration does not reach a plateau and would probably still increase should the heater continue to operate. At the same time, NO concentration increases up to 200 ppb in the case of the wick heater, and up to around 700 ppb for the injection heater. This difference between the two types of heater is in accor-
dance with previous laboratory results (Carteret et al., 2012), which indicated that the emission factors of NOx is about 3 times higher with injection heaters than with wick heaters. SO2 concentrations, measured only in dwelling #7, present the same temporal profiles as the nitrogen oxides concentrations. SO2 concentrations range from 1 ppb when the heater is not in use, to 13.7 ppb when using the heater. These concentrations are lower than the ones reported in previous studies (up to 400– 800 ppb) (Caceres et al., 1983; Cooper and Alberti, 1984; Leaderer et al., 1984), because of the lower sulfur content now allowed in the fuel. Formaldehyde concentrations, given in Table 3 together with the VOCs that were identified, ranged from 7 to 12 ppb, comparable to the long-term exposure recommendation in France of 8 ppb (Salthammer et al., 2010). These values are also in accordance with the previous measurements in real environments (Leaderer et al., 1986). Submicron particulate counts in dwelling #7 are presented in Fig. 3. Only the kerosene heaters have been identified as a source for these particles. Particles in the range 0.3–0.5 lm and to a smaller extent 0.5–1 lm are also produced by another source, which has been identified as a bread toaster located in the adjacent kitchen. The submicron particles produced by the heater eventually coagulate, resulting in a slow increase in coarser particles. Particles up to PM1.0 are produced almost exclusively from the kerosene heaters. Particles of larger diameter are also produced when using the heaters, but other sources are present. The high concentration of PM2.5 and PM5.0 at the end of the second day is not related to the use of the kerosene heater, and has not been identified, which stresses the limits of the questionnaires filled by the occupants. The maximal value for PM2.5 is 29.3 lg m 3, and the average value 7.3 lg m 3, below the WHO chronic exposure guideline of 10 lg m 3. Due to the difference in the pattern of use and in the size of the rooms, the measured particle concentrations cannot be compared to the previous studies (Mumford et al., 1991; Leaderer et al., 1999; Ruiz et al., 2010), even though these three studies pointed out that the use of kerosene heaters induces an increase in the PM2.5 concentrations compared to houses without kerosene heaters. For instance, in Leaderer et al. (1999) the kerosene heaters were estimated to add 40 lg m 3 of total PM2.5 to the indoor air. CO2 temporal variations in Fig. 1 are associated mainly with the use of the kerosene heater, and CO2 can be used as a proxy to determine when the heater is fired, so as to make sure that the questionnaires were correctly filled. Time resolved NOx measurements can
Please cite this article in press as: Hanoune, B., Carteret, M. Impact of kerosene space heaters on indoor air quality. Chemosphere (2015), http://dx.doi.org/ 10.1016/j.chemosphere.2014.10.083
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NOx (ppb) 800 NO2 online NO2 sensor #1 NO2 sensor #2 NO2 sensor #3 NO
700 600 500 400 300
1-hour WHO guideline (105 ppb)
200
toaster use
Electronic heater
100
Wick heater
Wick heater
0
15-May
16-May
16-May
17-May
17-May
Fig. 2. Time resolved NOx concentrations in dwelling #7. Gray areas indicate the use of the kerosene heater.
PM mass concentraon (μg.m-3) 100 90 80
ultrafine parcles (#.cm-3) 500000
PM0.5 PM1.0 PM2.5 PM5.0 0.02-1.00 μm
450000 400000
70
350000
60
300000
50
250000 200000
40 toaster u
30
150000
20
100000
10
50000
0 15-May
0 16-May
16-May
17-May
17-May
Fig. 3. PM counts in dwelling #7. Gray areas indicate the use of the kerosene heater.
also be used as a proxy for the use of the heater, as seen from the measurements in dwelling #7 (Fig. 2). The average concentrations of CO2 and of NOx are presented in Fig. 4 as a function of the daily duration of use. The average CO2 concentration, up to 1700 ppb, is linearly correlated to the duration of use. The average NO2 concentrations are also correlated to the duration of use, in spite of the high uncertainty on the passive sampling measurements. In addition, we have to distinguish between the wick-type or electronic injection heaters. Only NO presents one clear outlier, in the case of dwelling #4, with a daily average value of about 600 ppb, for which no explanation can be found. This correlation between the average CO2 or NO2 concentration and the daily average duration of use of the heaters holds true even though the average concentration of the gases takes into account the slow decrease of the gas concentration after the heater is turned off, due to the ventilation of the room. In addition, many potential parameters are not included in the analysis, such as the size of the room, the pattern of use of the heater, or the heating power. A correction for the power of the heater would be feasible for wick-type heaters, but not for electronic injection heaters, because these devices are fitted with a regulation system adapting the fuel consumption to the difference between the setup temperature and the actual temperature. This analysis makes also no
assumption regarding the well-mixed state of the air inside the room, the exchange with air from the outside or the other rooms during use of the heater, or the various sinks for the pollutants such as the reactions on surfaces. This confirms that all the other potential emission sources, from outdoor or indoor, are negligible compared to the emissions of the kerosene heaters. In the dwellings investigated, the other sources that have been identified, in addition to smoking, cooking, and the presence of people in the room, are wood burning appliances (closed pellet stove in dwelling #1, closed wood stove in dwelling #4, closed fireplaces in dwellings #2 and #5), and a closed coal stove in dwelling #3. There are no emissions associated with the gas central heating systems, because the combustion gases from the boiler are normally vented to the outdoor through well-insulated sealed ducts, with no impact on indoor pollutants concentrations (Tan et al., 2013). The emissions from the gas cookers, used in dwellings #1 and #3, are also negligible compared to the emissions from the kerosene heaters. For instance, the CO2 level increase associated with the cooking periods in dwelling #1 is only 200 ppm. As a comparison point, an increase of about 1500 ppm was reported in a kitchen during use of a gas cooking range (Tan et al., 2013). Our measurements were however not performed in the kitchen but in the living room, which might explain
Please cite this article in press as: Hanoune, B., Carteret, M. Impact of kerosene space heaters on indoor air quality. Chemosphere (2015), http://dx.doi.org/ 10.1016/j.chemosphere.2014.10.083
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Fig. 4. Average concentrations of CO2 and NOx vs. average daily duration of use of the kerosene heater. For clarity, NO2 concentrations have been multiplied by 4.
the smaller increase that we observed. In addition, the emissions from cooking devices tend to be attenuated with the generalized use of a range hood, which has been stressed by Nazaroff (2013) as an effective means of managing the indoor emissions from cooking. In dwelling #3, no CO or CO2 emissions associated with the use of the coal stove have been detected. Using coal for heating in Western Europe is now marginal, and no recent data is available, so this kind of heater will not be discussed here. Much more widespread, and increasing, is the use of wood burning appliances (Salthammer et al., 2014), such as the ones encountered in our present study (pellet stove, fireplace, wood stove). However, because all these systems were closed sources, only low concentrations of air contaminants are usually observed. For instance, it has been reported (Johansson et al., 2004) that the emissions from pellet stoves, in particular NO2 emissions (Gillespie-Bennett et al., 2008), are low compared to emissions from burning wood logs. In particular, as these stoves are automatically filled, there is no need to open the fire chamber. This manual refilling of wood burning ovens is at the origin of a temporary increase in particles and gaseous pollutants (Salthammer et al., 2014). In this latter study on the impact of modern wood-burning ovens on indoor air quality, it was shown that using these combustion devices has a noticeable but rather limited impact on indoor air quality, with concentrations of carbon oxides, nitrogen oxides and VOCs within the German guideline limits. These results agree with the several previous studies on the reduction of NOx and particulate matter emissions when replacing an open stove with a model where the fire chamber is sealed off from the room air, and where most of the combustion products are evacuated to the outside through a flue (GillespieBennett et al., 2008; Ward and Noonan, 2008).
4. Conclusion The present paper investigated the impact of kerosene heaters on indoor air quality in six dwellings, using the heaters normally used by the occupants. Additional measurements were performed in a seventh dwelling, with the heaters previously used in our laboratory study. All heaters comply with the French regulations, and so do the fuels provided by the occupants, except when the occupants purchased the kerosene in Belgium where the sulfur content can be higher than in France. The patterns of use of the heater vary greatly in the households investigated, with some occupants using it as an additional source of heat, while others make it their principal source of heat. The
average daily use duration ranges between 2 and 10 h, sometimes including periods when no one is present in the room or the house. In spite of the restricted number of houses investigated, which cannot be considered representative of the French dwellings panel, and of the restricted number of heaters under study, we have ascertained that the use of kerosene space heaters has a negative impact on indoor air quality, because kerosene heaters are unvented appliances and all combustion products are directly released into the room. Operation of kerosene space heaters induces an instantaneous increase in the CO2, NO, NO2 and submicron particles, which can be distinguished from the emissions of all the other sources in the dwellings. Measured concentration of CO2 during operation, up to 4500 ppm, are above the recommended maximal values (1000–1500 ppm). NO2 concentrations up to 200 ppb were also reached when using an electronic injection type heater for at least 30 min, and prolonged use of such a heater therefore results in an exposure of the users to NO2 levels above the WHO 1-h 105 ppb guideline. H2CO levels were of the order of the proposed long term exposure recommended value of 8 ppb guidelines. Real-time NOx and CO2 concentrations can be used as tracers of the use of kerosene heaters. Even if no time-resolved data are available for these compounds, their average daily concentration can be correlated to the duration of use.
Acknowledgments This work was supported by the ADEME (Agence de l’Environnement et de la Maîtrise de l’Energie) and the Région Nord-Pas-deCalais. PC2A participates in the Institut de Recherche en Environnement Industriel (IRENI) which is financed by the Région Nord-Pasde-Calais, the Ministère de l’Enseignement Supérieur et de la Recherche, the Centre National de la Recherche Scientifique (CNRS), and European Regional Development Fund (ERDF). We thank the Association pour la Prévention de la Pollution Atmosphérique (APPA) for their help in finding the dwellings investigated here.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2014.10.083.
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References Amitai, Y., Zlotogorski, Z., Golan-Katzav, V., Wexler, A., Gross, D., 1998. Neuropsychological impairment from acute low-level exposure to carbon monoxide. Arch. Neurol. 55 (6), 845–848. Bozzelli, J.W., Kebbekus, B., Bobenhausen, C., 1995. Analysis of selected volatile organic compounds associated with residential kerosene heater use. Int. J. Environ. Stud. 49 (2), 125–131. Caceres, T., Soto, H., Lissi, E., Cisternas, R., 1983. Indoor house pollution: appliance emissions and indoor ambient concentrations. Atmos. Environ. 17 (5), 1009– 1013. Carteret, M., 2012. Evaluation de l’exposition des personnes aux polluants issus des chauffages d’appoint au pétrole. PhD. Villeneuve d’Ascq, Université Lille 1. Carteret, M., Hanoune, B., Pauwels, J.F., 2010. Emissions de particules par les chauffages d’appoint à pétrole. Journée technique RSEIN/OQAI ‘‘Les particules dans l’air intérieur’’, Lille (France), INERIS. Carteret, M., Pauwels, J.F., Hanoune, B., 2012. Emission factors of gaseous pollutants from recent kerosene space heaters and fuels available in France in 2010. Indoor Air 22 (4), 299–308. Chambon, C., Schadkowski, C., 2004. Diagnostic de l’impact des feux à petrole sur le monoxyde de carbone dans les logements. Rapport APPA Nord Pas de Calais. Cooper, K.R., Alberti, R.R., 1984. Effect of kerosene heater emissions on indoor air quality and pulmonary function. Am. Rev. Respir. Dis. 129 (4), 629–631. Gillespie-Bennett, J., Pierse, N., Wickens, K., Crane, J., Nicholls, S., Shields, D., Boulic, M., Viggers, H., Baker, M., Woodward, A., Howden-Chapman, P., 2008. Sources of nitrogen dioxide (NO2) in New Zealand homes: findings from a community randomized controlled trial of heater substitutions. Indoor Air 18 (6), 521–528. Johansson, L.S., Leckner, B., Gustavsson, L., Cooper, D., Tullin, C., Potter, A., 2004. Emission characteristics of modern and old-type residential boilers fired with wood logs and wood pellets. Atmos. Environ. 38 (25), 4183–4195. Kawamoto, T., Matsuno, K., Arashidani, K., Yoshikawa, M., Kayama, F., Kodama, Y., 1993. Personal exposure to nitrogen dioxide from indoor heaters and cooking stoves. Arch. Environ. Contam. Toxicol. 25 (4), 534–538. Kinouchi, T., Nishifuji, K., Tsutsui, H., Hoare, S.L., Ohnishi, Y., 1988. Mutagenicity and nitropyrene concentration of indoor air particulates exhausted from a kerosine heater. Jpn. J. Cancer Res. (GANN) 79 (1), 32–41. Kirchner, S., Derbez, M., Duboudin, C., Elias, P., Gregoire, A., Lucas, J.-P., Pasquier, N., Ramalho, O., Weiss, N., 2008. Indoor air quality in French dwellings. Proc. Indoor Air 2008. Leaderer, B.P., 1982. Air pollutant emissions from kerosene space heaters. Science 218 (4577), 1113–1115. Leaderer, B.P., Stolwijk, J.A.J., Zagraniski, R.T., Ma, Q., 1984. A field study of indoor air contaminant levels associated with unvented combustion sources. In: 77th Proc. – APCA Annu. Meet. vol. 2, 84–33.3, 13p. Leaderer, B.P., Zagraniski, R.T., Berwick, M., Stolwijk, J.A., 1986. Assessment of exposure to indoor air contaminants from combustion sources: methodology and application. Am. J. Epidemiol. 124 (2), 275–289. Leaderer, B.P., Naeher, L., Jankun, T., Balenger, K., Holford, T.R., Toth, C., Sullivan, J., Wolfson, J.M., Koutrakis, P., 1999. Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO24 , H+, NH+4, NO3 , NH3, and nitrous acid in homes with and without kerosene space heaters. Environ. Health Perspect. 107 (3), 223–231.
7
Lionel, T., Martin, R.J., Brown, N.J., 1986. A comparative study of combustion in kerosine heaters. Environ. Sci. Technol. 20 (1), 78–85. Mumford, J.L., Williams, R.W., Walsh, D.B., Burton, R.M., Svendsgaard, D.J., Chuang, J.C., Houk, V.S., Lewtas, J., 1991. Indoor air pollutants from unvented kerosene heater emissions in mobile homes: studies on particles, semivolatile organics, carbon monoxide, and mutagenicity. Environ. Sci. Technol. 25 (10), 1732–1738. Nazaroff, W.W., 2013. Four principles for achieving good indoor air quality. Indoor Air 23 (5), 353–356. Ruiz, P.A., Toro, C., Caceres, J., Lopez, G., Oyola, P., Koutrakis, P., 2010. Effect of gas and kerosene space heaters on indoor air quality: a study in homes of Santiago, Chile. J. Air Waste Manage. Assoc. 60 (1), 98–108. Salthammer, T., 2013. Formaldehyde in the ambient atmosphere: from an indoor pollutant to an outdoor pollutant? Angew. Chem., Int. Ed. 52 (12), 3320–3327. Salthammer, T., Mentese, S., Marutzky, R., 2010. Formaldehyde in the indoor environment. Chem. Rev. 110 (4), 2536–2572. Salthammer, T., Schripp, T., Wientzek, S., Wensing, M., 2014. Impact of operating wood-burning fireplace ovens on indoor air quality. Chemosphere 103, 205– 211. Schadkowski, C., 2003. Exposition individuelle aux oxydes d’azote et au monoxyde de carbone: premiers résultats de l’étude ‘‘Sentinelles de l’air’’ en région NordPas-de-Calais. Air pur 64, 14–29. Tamura, G.T., 1987. Measurement of combustion products from kerosene space heaters in a two-story house. ASHRAE Trans. 93, 173–184. Tan, C.C.L., Finney, K.N., Chen, Q., Russell, N.V., Sharifi, V.N., Swithenbank, J., 2013. Experimental investigation of indoor air pollutants in residential buildings. Indoor Built Environ. 22 (3), 471–489. Tokiwa, H., Nakagawa, R., Horikawa, K., Ohkubo, A., 1987. The nature of the mutagenicity and carcinogenicity of nitrated, aromatic compounds in the environment. Environ. Health Perspect. 73, 191. Traynor, G.W., Allen, J.R., Apte, M.G., Girman, J.R., Hollowell, C.D., 1983. Notes. Pollutant emissions from portable kerosine-fired space heaters. Environ. Sci. Technol. 17 (6), 369–371. Traynor, G.W., Apte, M.G., Sokol, H.A., Chuang, J.C., Tucker, W.G., Mumford, J.L., 1990. Selected organic pollutant emissions from unvented kerosene space heaters. Environ. Sci. Technol. 24 (8), 1265–1270. Tu, K.W., Hinchliffe, L.E., 1983. A study of particulate emissions from portable space heaters. Am. Ind. Hyg. Assoc. J. 44 (11), 857–862. Ward, T., Noonan, C., 2008. Results of a residential indoor PM2.5 sampling program before and after a woodstove changeout. Indoor Air 18 (5), 408–415. White, J.B., Leaderer, B.P., Boone, P.M., Hammond, S.K., Mumford, J. L., 1987. Chamber studies characterizing organic emissions from kerosene heaters. In: 1987 EPA/APCA Symposium on Measurement of Toxic and Related Air Pollutants. WHO (2010). WHO guidelines for indoor air quality: selected pollutants. WHO regional office for Europe, Copenhagen. Woodring, J.L., Duffy, T.L., Davis, J.T., Bechtold, R.R., 1985. Measurements of combustion product emission factors of unvented kerosene heaters. Am. Ind. Hyg. Assoc. J. 46 (7), 350–356. Yamanaka, S., Hirose, H., Takada, S., 1979. Nitrogen oxides emissions from domestic kerosene-fired and gas-fired appliances. Atmos. Environ. 13 (3), 407–412. Zhou, Y., Cheng, Y.-S., 2000. Characterization of emissions from kerosene heaters in an unvented tent. Aerosol Sci. Technol. 33 (6), 510–524.
Please cite this article in press as: Hanoune, B., Carteret, M. Impact of kerosene space heaters on indoor air quality. Chemosphere (2015), http://dx.doi.org/ 10.1016/j.chemosphere.2014.10.083