Indoor Pollution from Heating Keiichi ARASHIDANII~, Masahiro

Industrial Health, 1996, 34, 205-215 205

Indoor Pollution from Heating

Keiichi ARASHIDANII~, Masahiro YOSHIKAWA2~, Toshihiro KAWAMOTO3~, Koji MATSUNO3~, Fujio KAYAMA4~ and Yasushi KODAMA3~

1) EnvironmentalHealth Science Course, School of HealthSciences, University of Occupationaland EnvironmentalHealth, 1-1, Iseigaoka, Yahatanishi-ku,Kitakyushu City 807, Japan 2) Divisionof OccupationalHygiene, School of Nursingand Medical Technology,University of Occupationaland EnvironmentalHealth, 1-1, Iseigaoka,Yahatanishi-ku, Kitakyushu City 807, Japan 3) Departmentof EnvironmentalHealth, School of Medicine,University of Occupationaland EnvironmentalHealth, 1-1, Iseigaoka, Yahatanishi-ku,Kitakyushu City 807, Japan 4) Departmentof EnvironmentalHealth, Jichi MedicalSchool, School of Medicine,329-4, Yakushiji,Minamikawachi-machi, Kawachi-gun, Tochigi-ken329-04, Japan

(ReceivedMarch 19, 1996 and in revisedform April 25, 1996)

Abstract: The concentrationsof indoor pollutantsgenerated from types of heaters were measuredin a model room of 20m2in area and 45m3in capacity.We used six different heaters: three keroseneheaters of differenttypes, town and propanegas heaters, and an electricheater. Three ventilationconditions were introducedinto each experiment:non- ventilation,fan-on ventilationwith closeddoor and fan-off ventilationwith half-opened door. The resultsobtained by heating under non-ventilationcondition were as follows:The concentrationsof NO2and CO2were comparativelyhigh and the values obtainedfrom all the heaters exceptthe electric heater exceededthe 1-hr Environmental Quality Standards, Japan (EQSNO2: 0.04-0.06 ppm) and the BuildingSanitation Management Standards, Japan (BSMSC02: 1,000ppm), respectively. The CO concentrationemitted from reflectionkerosene and town gas heaters slightlyexceeded the BSMS(10 ppm). The concentrationsof suspendedparticulate matter and polynucleararomatic hydrocarbons showed an increasingtendency during the use of kerosene-fueledheaters. Under two ventilatingconditions, NOx concentrationdecreased to less than a third in comparison with non-ventilatingcondition.

AddressCorrespondence to: KeiichiArashidani, Ph.D., Environmental Health Science course, School of Health Sciences,University of Occupationaland EnvironmentalHealth, 1-l, Iseigaoka,Yahatanishi-ku, Kitakyushu City 807, Japan. Tel: 093-691-7282 206 K. ARASHIDANI et al.

Key words: Indoor air pollution - Heating- NOx - CO and CO2- Suspendedparticulate matter - Polynuclear aromatic hydrocarbons

INTRODUCTION

Today, the quality of indoor air has been recognized as an important factor in the assessment of health effect. People have been spending far more time indoors than outdoors' 3), where it often happens that the concentration of pollutants is higher than outdoors. Moreover, most modern Japanese houses are similar to those of Europe and the U.S.A., losing their traditional open-style structure. Cigarette smoking, heating, cooking and plywood are often the most significant factors influencing the concentrations of indoor air components4-10~. The pollutants emitted from man-made sources can be hazardous chemicals which lead to diseases such as respiratory disease, blood toxicity, potential mutagens and carcinogens. In particular, several substances emitted from smoking and heating appliances may have adverse human health effects, and human exposure to these hazardous substances of high concentration, even if for a short period of time, may cause an undesirable effect on the health of the individual. Observation of hazardous substances in a small and closed-style room seems to make a highly significant contribution to the understanding of indoor air health effects. This study, therefore, is designed to determine the pollutants generated by heating under non-ventilation or ventilation conditions.

EXPERIMENTALPROCEDURES

As shown in Figure 1", a simulated model room of 20 m2 in area and 45 m3 capacity was used for the measurement of pollutants generated from heating appliances. The six heating appliances of different types included: an electric heater (Hitachi, 1,200 W, Japan), a town gas heater (Rinnai, 3,300 Kcal/hr, Japan), a propane gas heater (National, Japan), a convection kerosene heater (Aladine, 0.26 L/hr, Japan), a reflection kerosene heater (Hitachi, 0.26 L/hr, Japan), and a kerosene-fan heater (Daikin, 3,300 Kcal/hr, Japan). Each heater was run in the model room for 3 hours and the concentrations of pollutants were measured for 9 hours for three stages (pre-, test-, post-burning) under non-ventilation (Fan-off, Door-closed) or ventilating (Fan-on, Door-closed or Fan-off, Door 45°-opened) conditions. The ventilation rate (m3/hr) and number of air changes per hour (time/hr) of these ventilating systems were 31.3 ± 20.7, 0.7 ± 0.4 for non-ventilating condition, 136.1 ± 54.0, 3.8 ± 1.1 for Fan-on, Door-closed condition and 165 ± 53.2, 3.0 ± 1.2 for Fan-off, Door 45°-opened condition, respectively. INDOOR POLLUTION FROM HEATING 207

Fig. 1. Schematic diagram of the model room. l: Nitrogen oxides analyzer 2: Low volume air sampler 3: Gas collector 4: CO-CO2 meter 5: Thermometer 6: Hygrometer 7: Digital dust indicator 8: Particle counter 9: Glove thermometer

The nitrogen oxides were determined by a chemiluminescence NOx analyzer (Denkikagaku Co. Ltd., Japan) which recorded NO2, NO and NOx (NO2 + NO) continuously at intervals of 30 seconds. The flame temperature was measured at the circumference of the flame by a digital thermometer (Chino Works Co. Ltd., Japan). CO and CO2 were determined by a CO and CO2 meter (Sibata Scientific Technology Ltd., Japan). Suspended particulate matter (SPM) was collected on a glass fiber filter (Type 60 A20, Tokyo Dylec Ltd., Japan) using a low volume air sampler equipped with a particle-size-separator to remove particles larger than 10 µm. Relative SPM and the number of particles were measured by a digital dust indicator P-5 (Sibata Scientific Technology Ltd., Japan) and particle counter (Rion Ltd., Japan), respectively. Polynuclear aromatic hydrocarbons (PAHs) in SPM were extracted by using ultrasonic method and cleaned up with basic alumina and then determined by using a high-performance liquid chromatograph with a fluorescence detector12~. 208 K. ARASHIDANI et al.

RESULTSAND DISCUSSION

(1) Nitrogen oxides An example of the change of NOx concentrations during pre-, test-, and post- burning, and the maximum level of NOx concentrations during test-burning under non-ventilating condition in the model room are summarized in Figure 2 and Figure 3, respectively. As shown in Figure 2, NOx concentrations from all the heaters except the electric heater increased simultaneously with burning and then reached the maximum level after 1 hour in the case of non-ventilating condition. NOx concentrations under two ventilating conditions increased simultaneously with burning, the same as non-ventilating condition, and already reached the maximum level after 30 minutes, in comparison with non-ventilating condition. At post-burning, NOx concentrations decreased to much the same level as those in pre-burning within 30 minutes under the two ventilating conditions. However, NOx concentration under non-ventilating condition decreased gradually and needed 90 minutes to reach a pre- burning level. When heating was stopped, the decrease of N02 concentration obtained was about twice as large as NO concentration. In the case of the reflection kerosene heater under non-ventilation, N02 concentration needed about 30

Fig. 2. Changes of 1 hour values of NO2 and NO concentrations in the model room by the kerosene-fan heater (Fan off, door closed). INDOOR POLLUTION FROM HEATING 209

minutes to decrease to half the level of concentration. NO2 concentration in the model room during pre-burning was at a level below 0.03 ppm, and NO concentration was at a lower level than NO2 concentration. Therefore, NO2 concentration in indoor air by non-heating was just under the EQS. As shown Figure 3, NO2 concentration of all the heaters except the electric heater exceeded the EQS. These results indicate the possibility of ill effects on the health of people exposed to NOx in indoor environments, including the working environment, during winter season. Therefore, it is necessary to decrease the NOx concentration by means of ventilating condition and so forth. A fact worthy of note from this result was a remark- able difference of NOx emission means by the type of heater, as shown in Figure 3. The ratio of NO/NO2 concentration was 4.6 for convection kerosene heater, 0.2 for reflection kerosene heater, 2.9 for kerosene-fan heater, 0.02 for town gas heater and 0.08 for propane gas heater, respectively. As shown in Figure 4, under non- ventilating condition in which the number of air changes per hour is less than one, NO2 concentration from all heaters except the electric heater were exceedingly high, and exceeded the EQS upper limit (0.06 ppm). In contrast, under two different

Fig. 3. Concetrations of NO2 & NO in the model room by heating (Fan off, Door closed). A: Convection kerosene heater B: Reflection kerosene heater C: Kerosene-fan heater D: Town gas heater E: Propane gas heater F: Electric heater 210 K. ARASHIDANI et al.

Fig. 4. Comparison of NO2 concentration and ventilating conditions. A: Convection kerosene heater B: Reflection kerosene heater C: Kerosene-fan heater D: Town gas heater E: Propane gas heater ventilating conditions, NOx concentrations decreased to less than a third of those under non-ventilation. This result is considered to be attributed to the increase of ventilation volume. However, NO2 concentrations for the convection kerosene heater and the kerosene-fan heater exceeded the EQS upper limit despite the ventilating operation. NO2 concentration obtained from the present study was in agreement with the findings of some published reports'3, 14)that NOx concentration from convection kerosene heaters is generally at a high level. NOx concentration from the reflection kerosene heater was the same as the concentration (NO2: 0.26 ppm, NO: 0.16 ppm) from the same type of heater in the Hasegawa et al. report14~. NOx concentration from the town gas heater was the same as the result (NO2: 0.15 ppm, NO: 0.02 ppm) of Hasegawa et al. 14)and also Palmes et al. reports15~. In the case of convection kerosene heater, NO concentration of the present data was the same level with the result (NO: 1.25 ppm) but NO2 concentration of the present data was at a low level, less than a fourth of the Hasegawa et al. report14~ INDOOR POLLUTION FROM HEATING 211

The ratio of NO/N02 varied according to the type of heater and burning conditions. The flame temperature shows a mean measurement of ten points. As shown in Figure 5, in the case of the convection kerosene heater, under the burning condition (600°C) of red flame, the main component of nitrogen oxides was N02, but NO concentration increased with the length of the flame, indicating a rise in the flame temperature. N02 concentration increased until the temperature increased to 800°C, but flame temperature over 800°C quickly decreased N02 concentration.

Fig. 5. Relationship between combustion temperature of kerosene heater and NO & NO2 concentrations. 212 K. ARASHIDANI et al.

In the case of the reflection kerosene heater, both gas concentrations of NO2 and NO increased gradually until the flame temperature of about 780°C, and the main component of NOx was NO2, the same as the convention kerosene heater. When the flame temperature was over about 780°C, NO2 and NO concentrations increased rapidly, and were at an equal ' level. Therefore, NOx emission was dependent on the type of heater and the !burning condition.

(2) Carbon monoxide and Carbon dioxide The hourly maximum concentrations of CO and CO2 are shown in Figure 6 and Figure 7, respectively. Under non-ventilating condition, concentrations of CO and CO2 increased simultaneously by heating and reached a steady level within 1 hour, and reverted to the normal level in 3 hours after heating. CO2 concentration from all heaters except the electric heater under non-ventilating condition showed a higher level than 3,000 ppm and exceeded the BSMS (1,000 ppm). CO concentrations from reflection kerosene and town gas heaters were 11 ppm and 13.7 ppm, respectively, and these were the only cases which exceeded the BSMS limit (10

Fig. 6. Maximal CO concentration in the model room by heating (Fan off, Door closed). A: Convection kerosene heater B: Reflection kerosene heater C: Kerosene-fan heater D: Town gas heater E: Propane gas heater F: Electric heater INDOOR POLLUTION FROM HEATING 213

Fig. 7. Maximal CO2 concentration in the model room by heating (Fan off, Door closed). A: Convection kerosene heater B: Reflection kerosene heater C: Kerosene-fan heater D: Town gas heater E: Propane gas heater F: Electric heater ppm). Operating under the two different ventilating conditions, CO concentration by heating decreased with all appliances and were under the BSMS. CO2 concentrations under ventilating operations except the town gas heater (Fan off, Door 45°-opened) or propane gas heater (Fan on, Door closed) were not decreased to a level under the BSMS.

(3) SPM and PAHs As shown in Table 1, SPM concentration of convection kerosene heater under non-ventilating condition showed an increase with the use of convection and reflection kerosene heaters in comparison with other heaters. SPM concentration by all the heaters was less than BSMS (0.15 mg/m3) and at a lower level than its concentration (0.054-0.077 mg/m3) in the ambient air measured during 1980- 1988 in the Kitakyushu district16~ Relative SPM concentration measured by a digital-dust indicator ranged from 6-29 cpm at preheating to 7-39 cpm during test-heating, and 6-35 cpm at post- heating. Determination of the number of particles emitted from the heaters by a particle counter showed no differences due to the type of heating appliances. Distribution of particle size was 0.3-0.5 µm > 0.5-1.0 tm > 1.0-2.0 µm > 2.0-5.0 rim > larger 214 K. ARASHIDANI et al.

Table 1. Suspended particulated matter (SPM), Benzo[a]pyrene and Benzo[ghi]perylene concentrations in the model room by the heaters (Fan off, Door closed).

than 5 µm. Particles of 0.3-0.5 µm were many in number, being over 10,000/L. On the other hand, the number of particles of 0.3-0.5 µm accounted for about 90%, in agreement with the analysis by a scanning electron micrograph. Table 1 shows PAHs concentrations in the model room during test-heating under non-ventilating condition. Benzo[a]pyrene is a typical carcinogenic substance in PAHs. PAHs concentration from convection and reflection kerosene heaters showed an increasing tendency in comparison with other heaters and background and were on a similar level (year mean: 0.43-1.94 ng/m3) to those in the ambient air in Kitakyushu city, Fukuoka Prefecture, Japanl6)

CONCLUSIONS

This study focused on the pollution by six different heating appliances under three ventilation conditions in a model room, with the following conclusions. 1. Concentrations of NOx increased, depending on the heating appliances and ventilating conditions. NO2 concentrations obtained from kerosene-fueled heaters were higher than those obtained from gas heaters and exceeded the EQS upper limit. 2. CO and CO2 concentrations showed a simultaneous increase by heating. Under non-ventilating condition, CO concentrations by heating rose over the BSMS, while CO2 concentrations from all the heaters except the electric heater exceeded the BSMS. 3. The concentrations of SPM and PAHs showed a rising tendency during the use of the kerosene-fueled heater. 4. Ventilating operations by door opening and fan-on were an effective method for decreasing the concentration of indoor pollutants.

From the above mentioned facts, therefore, this study indicates that heating INDOOR POLLUTION FROM HEATING 215

causes emissions of chemical substances such as NOz, NO, CO, C02, SPM and PAHs, sometimes at a high concentration exceeding the BSMS. Therefore, these facts also suggest that it will be necessary to decrease the concentration of pollutants in the indoor environment.

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