A STUDY ON PM 10 AND VOCS CONCENTRATIONS OF INDOOR ENVIRONMENT IN SCHOOL AND RECOGNITION OF INDOOR AIR QUALITY

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1 A STUDY ON PM 10 AND VOCS CONCENTRATIONS OF INDOOR ENVIRONMENT IN SCHOOL AND RECOGNITION OF INDOOR AIR QUALITY BS Son 1,*, MR Song 2, WH Yang 3 1 Department of Environmental Health Science, Soonchunhyang University, Asan, KOREA 2 Department of cosmetology, Dong Kang College of Kwangju, Kwangju, Korea 3 Department of Occupational Health, Catholic University of Daegu, Daegu, Korea ABSTRACT To analyze the air quality of the indoor environments of schools, we measured the indoor, outdoor and personal exposure concentration level of PM 10 and VOCs for 40 classrooms (20 old, 20 new) in Choongnam area from June 22 to July 19 and from November 21 to December 30, In addition, we used Questionnaire for 193 nurse- teachers, 41 teachers, and 1,359 students. The results are as follows. 1. Old classrooms contained more dust than new classrooms; the average of respirable dust was μg / m3 for new classrooms while μg / m3 for old one. The exposure concentration level of respirable dust in new classrooms was higher in outdoors than in indoors in summer. The values were indoors μg / m3, outdoors μg / m3, and personal μg / m3. Meanwhile in winter indoors had a higher concentration level than outdoors, the values of indoors μg / m3, outdoors μg / m3, and personal μg / m3. 2. In VOCs examination, analysis found benzene, toluene and xylene in most of the classrooms. Both old and new classrooms contained similar amounts of benzene, but new classrooms contained higher amounts of toluene and xylene. 3. VOCs measurements resulted in comparison of toluene concentration level between new classrooms and old classrooms showed 3.15 times higher indoor concentration level in new class rooms, containing μg / m3, while old classrooms contained μg / m3. Personal exposure showed 2.87 times higher in new classrooms, containing μg / m3, while old classrooms contained μg / m3. The results of this research indicated insufficient understanding of health risks from indoor air pollution, and showed possible health problems to students from school indoor air pollution. A logical and systematic education program for students about the importance of indoor air quality should be carried out. Also the results of PM 10 and VOCs concentration level measurements emphasize the need for regular measurements of indoor, outdoor and personal concentration level. New classrooms in particular need to be used after measuring pollutants and safety, and require the installation of a ventilation device in all classrooms to improve air quality. INDEX TERMS School, Class rooms, Air Quality, VOCs, PM 10 INTRODUCTION Since 1970, the use of tight close-up and insulation in construction of houses and increased amount of new pollutants emitted from articles and goods we have to use (Hoddinott and Lee, 2000). These caused deterioration of indoor air quality, which is negatively affecting health of people who have to stay inside (Shin Dong-chun and et al., 2003). * Corresponding author kosie@kosie.or.kr 827

2 These days, people spend more time in indoor (70 ~ 80%).In particular, young students in the period of mentally and physically flourishing development have to inhale more air, but as they have sensitive immune-system, they may be seriously affected by contaminated indoor air. Students spend most of their time (7-14 hrs) in schools, institutes or classrooms. It is important to maintain their indoor environment pleasant and safe (EPA, 2002). However, Korean elementary, middle and high schools did not prepare management policies on management of VOCs, lead, and heavy metals, and studies on school environment health facilities, their current status and management are still insufficient. The School Health Enforcement Regulation presents two standards: CO 2 concentration : 1,000ppm, PM 10 : 150 μg / m3, and suggests they should be complemented to adapt to the regulation in five years (School Health Management Enforcement Regulation presented by Ministry of Education, 2003). However, schools do not recognize even necessity of measuring the quality while students' parents are asking safe indoor environment for their children. Thus, interests of parents and the Ministry of Education in air quality have increased, but who has to take care of indoor air quality and how it should be managed have not been decided yet. Also, management standards on what problems exist in indoor air have not been prepared. Therefore, this study is to investigate the concentration of micro dust in indoor and outdoor environment and components and concentration of heavy metals in the dust, and to measure the concentration of VOCs for good school environment where young students stay safely. Also, it is to identify the recognition of students and teachers on indoor air quality through questionnaire, and the results will be used as data for health management education. METHODS For the purpose, this study randomly selected 2 or 4 classrooms from 9 elementary schools and 2 middle schools in Dangjin-gun, Chunan, Choongchungnamdo. From them, 20 classrooms that have been built for more than three years ( hereafter mentioned as old classrooms ), and 20 classrooms that have been built for less than three years ( hereafter mentioned as new classrooms ) were measured in summer (June 22 - July ) and winter (November 21 ~ December 30) separately and the data were collected for 48 hours. The subjects for the study were minute dust (PM 10 ) in air, heavy metals, VOCs such as Benzene, Toluene, and Xylene. To collect PM 10 with below 10 μm diameter from floating dust, this study used Pump(personal air sampler-gilian Co.) whose flow ranges from 0 to 5 LPM(l/min) and Cyclone & Cassette holder assembly kit(gilian Co., Document No. F-PRO-1247)) and dust were subsequently measured for 2 days. In general, the activated carbon tube method, the organic vapor monitor method, and tedlar bag method were used to collect VOCs. This study used the OVM badge 3500 produced by 3M to prevent obstruction of the class to collect samples. To identify concentration of VOCs and PM 10, this study used SPSS 11.0 and conducted χ2 test to identify significance of each factor according to the mean, standard deviation and concentration of pollutants. RESULTS As shown in Table 1, the mean amount of indoor and outdoor dust was μg / m3 and μg / m3 respectively while individual exposure was μg / m3 which was relatively high. A study in Hongkong reported that 21~617 μg / m3 was measured in five classrooms (Lee, 2000), and data in indoor air measured at Modena University, Italy, presented the results as follows: indoor 80 μg / m3 and outdoor 350 μg / m3 for downtown and indoor 210 μg / m3 and outdoor 200 μg / m3 for suburban areas (Guglielmina Fantuzzi, 1996). The study by Sin and et al. showed lower amount of concentration in comparison with the results of 240 μg / m3 and 303 μg / m3 in elementary schools classrooms (Sin Eun-sang and et al., 2002). The result of this study showed lower amount of PM 10 was suggested to be due to weather characteristics and high humidity of corresponding areas during measurement period: sunshine duration : 3.1 hours in summer, 4.6 hours in winter, mean temperature : 22.2 in summer and 1.7 in winter, mean velocity: 1.7 m/sec in summer, 828

3 and 1.8 m/sec in winter; humidity in summer : mean 82.4%, winter : mean 71.3%. The period of measurement in summer for this study was from June 22 to July 19 and it was rainy season. 64.3% of the period (18 days of 28) had rain, and mean rainfall was 11.8 mm. Table 1. Measured concentrations( μg / m3 ) of PM 10 in indoor, outdoor and personal exposure Sampling site N Mean ± S.D. Minimum Maximum Indoor ± Outdoor ± Personal ± Total ± Concentration of individual exposure was μg / m3 which was higher than μg / m3 of indoor concentration or μg / m3 of outdoor concentration. In this case, it is thought that teachers used measuring instruments at school and home, and were exposed to the environment with higher amount of subject dust while moving or at home. The mean amount of PM 10 of the subject schools was μg / m3, for old classrooms and μg / m3 for old classrooms as presented in Table 2. The concentration of old classrooms was higher than that of new classrooms. It was because most of the floors of old classrooms were wooden and for new classrooms, every facility was new, and the floors were PVC or linoleum which generated less dust. However, below the mean of 150 μg / m3 for 24 hours regulated in School Health Code was measured in both classrooms. Table 2. Measured concentrations( μg / m3 ) of PM 10 in new and old classes Sampling site No. Mean ± S.D. Minimum Maximum New class ± Old class ± As seen in Table 3, there was no statistical difference between the means of PM10 in summer and winter. For summer, there was no difference between old and new classrooms (new: μg / m3, and old: μg / m3 ), but for winter, PM 10 of old classrooms was higher (new: μg / m3, and old: μg / m3 ). When the results of old and new classrooms were combined, there was no statistically significant difference. In addition, as measurement period included many rainy or snowy days, outdoor concentration of PM 10 was lower. Table 3. Measured Concentrations( μg / m3 ) PM 10 in summer and winter Sampling site N New classes Old classes Total Mean ± S.D.(Median) Summer ± (41.11) ± (43.25) ± (42.94) Winter ± (39.38) ± (40.92) ± (39.82) This study sampled 20 new classrooms that have been built for less than three years and 20 old classrooms that have been built for more than 3 years, and attached OVM badges indoor, outdoor and individuals (teachers) to measure concentration of VOCs. In particular, this study targeted benzene, toluene, and xylene for analysis and comparison. In Table 4, when indoor concentration (benzene: 8.17 μg / m3, toluene: μg / m3, xylene: 23.2 μg / m3 ), outdoor concentration (benzene: 7.49 μg / m3, toluene: μg / m3, xylene: μg / m3 ), and individual exposure concentration (benzene: 7.73 μg / m3, toluene: μg / m3, xylene: μg / m3 ) was considered, there was no significant difference, but exposure of individuals to toluene and xylene are was the highest, followed by indoor and outdoor exposure. A study on indoor air at the library in Modena University reported the following indoor concentration (benzene: 11.0 μg / m3, toluene: 22.0 μg / m3, xylene: 38.0 μg / m3 ) and outdoor concentration (benzene: 11.0 μg / m3, toluene: 32.5 μg / m3, xylene: 59.0 μg / m3 ) (Guglielmina Fantuzzi, 1996), and Shin and et al., reported the following: for indoor concentration of housing and offices in Seoul city, benzene: 38.9/ m3, toluene: μg / m3 and for 829

4 outdoor concentration, benzene: 27.8/ m3, toluene: μg / m3. The indoor concentration was 1.2 or 2.4 times higher than outdoor concentration (Shin Hye-soo and et al., 1993). Baek reported that indoor concentration (benzene: 5.3 μg / m3, toluene: 26.1 μg / m3, xylene: 18.6 μg / m3 ) was higher than that of outdoor (benzene: 6.2 μg / m3, toluene: 34.4 μg / m3, xylene: 30.0 μg / m3 ) (Baek Sung-ok, 1996). This study proposed the similar results to other domestic studies on indoor air, but the mean concentration of Toluene was higher than that of other studies because of the results of new classrooms Table 4. VOCs concentration( μg / m3 ) in indoor, outdoor and personal exposure VOCs Mean ± S.D. (Median) Indoor (n=74) Outdoor (n=74) Personal (n=75) Benzene 8.17 ± 5.68 (7.29) 7.49 ± 1.37 (7.00) 7.73 ± 1.42 (7.51) Toluene ± (36.95) ± (15.10) ± (28.40) Xylene 23.2 ± 31.6 (8.78) ± (6.18) ± (12.18) As shown in Table 5, there was no statistically significant difference in Benzene concentration between new classrooms (benzene: 7.6 μg / m3, toluene: μg / m3, xylene: μg / m3 ) and old ones (benzene: 7.99 μg / m3, toluene: μg / m3, xylene: μg / m3 ), but concentrations of toluene and xylene in new classrooms were 3 times higher than those of old ones. According to the results of comparison between new and old buildings in housings and offices, it was found that VOCs of new buildings was 1.3 times higher than that of old buildings, and it is similar to the report that such components of construction materials affected concentration of VOCs (Shin Hye-soo, 1993). So and et al., reported that above the permitted standard of Toluene was found from only one new school of the three schools surveyed (So Jong-ryol et al. 2003). This study also found that lots of toluene and xylene were emitted from newly-built buildings because this study targeted new classrooms that have been built for less than one year, and higher difference in their amount was found. Most of the floors in old classrooms were wooden and the walls were made of painted cement bricks. As they were repainted every third or fourth year, the paint was thick. The ceilings were made of plaster board and for the old classrooms, the plaster boards were painted. Table 5. VOCs concentrations( μg / m3 ) in new classes and old classes VOCs Mean ± S.D. (Median) New class (n=115) Old class (n=108) Total (n=223) Benzene 7.60 ± 1.74 (6.74) 7.99 ± 4.52 (7.59) 7.80 ± 3.46 (7.25) Toluene ± (41.60) ± (16.50) ± (27.20) Xylene ± (12.56) ± (6.86) ± (8.55) As a result of the analysis of VOCs in summer and winter, Table 6 presented the following results: for summer, benzene: 8.83 μg / m3, toluene: μg / m3, xylene: μg / m3 and for winter, benzene: 6.93 μg / m3, toluene: μg / m3, xylene: μg / m3. Table 6. VOCs concentrations( μg / m3 ) in summer and winter VOCs Mean ± S.D. (Median) Summer (n=121) Winter (n=102) Benzene 8.83 ± 1.0 (8.62) 6.93 ± 4.43 (6.46) Toluene ± (243.50) ± (12.30) Xylene ± (12.53) ± (7.27) The study on Concentration of VOCs in general indoor environment in Daegu by Kim and et al. reported that it was about from 1.9 to 2.5 times higher in winter than that of summer (Kim Young-min and et al, 1995), and Baek reported that there was a little difference according to items analyzed, but in general, the concentration of VOCs was higher in winter than that of in summer (Baek Sung-ok, 1996). However, this study found that concentration of VOCs was higher in summer due to new classrooms, which indicates that the concentration of VOCs should be controlled in new classrooms. 830

5 Figure 1. VOCs concentrations( μg / m3 ) in summer and winter. In general, the concentration is higher in winter than that of in summer as ventilation is not good in winter. However, this study found that concentrations of benzene, toluene and xylene were higher in summer than those of in winter as shown in Figure 1. Their concentration was higher in summer for new classrooms as just three months have passed since they were built. However, for winter survey, the measurement was conducted six months after the construction. Also it is thought that evaporation of benzene, toluene, and xylene would affect the results of the study. CONCLUSION This study selected 40 classrooms (20 old classrooms and 20 new classrooms) of elementary and middle schools in some area in Chungchungnamdo from June 22 to July 16 in 2003 (summer) and from November 21 to December (winter), aiming to analyze air quality of school indoor environment. It measured indoor, outdoor and personal exposure concentration of PM 10, and interviewed the school staff using a questionnaire to survey recognition on school indoor air quality. The subjects were 193 nurse- teachers, 41 teachers in charge of the class and 1359 students in Chungchungnamdo, and the results were presented as follows: 1. The mean amount of PM 10 in new classrooms was μg / m3 and the mean amount of PM 10 in old ones μg / m3. PM 10 in old classrooms was more than that of new classrooms. The concentration of PM 10 in new classrooms was μg / m3 for indoor, 50,46 μg / m3 for outdoor, and μg / m3 for individuals in summer. The outdoor concentration was higher than indoor concentration, but for winter, indoor concentration: μg / m3, outdoor concentration:34.86 μg / m3, and individual exposure: μg / m3. 2. For VOCs, benzene, toluene and xylene were detected in most of the classrooms, and for benzene, the difference between new classrooms and old ones was insignificant. But more toluene and xylene were found in new classrooms. 3. As a result of measuring VOCs, more toluene was found in new classrooms ( μg / m3 ) than in old ones ( μg / m3 ), that is, 3.15 times higher in new classrooms. For individual samples, μg / m3 of toluene was found in new classrooms but μg / m3 of toluene was found in old classrooms. It was 2.87 times higher in new classrooms. Based on the results of this study, it indicated that school indoor air pollution may affect health of students because the subjects have insufficient understanding of influences indoor air pollution in relation to health problem. Therefore, the organized and planned education on importance of indoor air should be given to teachers and students. Also, the results of measured concentration of PM 10 and VOCs suggested that the proper measurement of school indoor and outdoor air and individual exposure is needed. In particular, for the new classrooms, air safety should be confirmed through measurement of pollutants, and ventilation systems should be prepared for all the classrooms to improve air quality. 831

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