School of Environmental & Resource, Inner Mongolia University, Huhhot, China

Transcription

1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Spatial and temporal distribution and air quality evaluation of the indoor air microorganisms in summer campus JiFei Xu*, XinYing Wang, HuiMin, HongYu Ma, and Ji Zhao* School of Environmental & Resource, Inner Mongolia University, Huhhot, China Keywords: Air microorganisms, Spatial and temporal distribution, Campus, Quality Evaluation. Abstract. The campus indoor environment is an important learning and living environment for college students, and it is closely related to the health of college students. Using natural sedimentation to monitor and evaluate the indoor air microorganisms of four classrooms (0407, 0408, 0409 and 0410) which are in the Inner Mongolia University campus comprehensive building of fourth floor. The results show that the concentration variation of indoor air microorganisms is different in one day, in the 5 periods of time from morning to night, the maximum is cfu m -3 in the morning, which is 12 times to the minimum. Air microbial content of the sunny classrooms (0407 and 0409) is obviously higher than night side classrooms (0408 and 0410), the total bacteria concentration of classroom 0407 is 2.1 times to classroom 0408, and the concentration of classroom 0409 is 1.5 times to classroom Among the 4 sampling points, the highest total concentration of air microorganisms is cfu m -3, the lowest value is cfu m -3, and the average value is cfu m -3. Bacteria as the main air microorganism in summer campus classroom, accounted 77.4%, mold accounted18.9%, actinomycetes accounted 3.7%. According to the air microorganism standards, it evaluates that each time of indoor air is clean. Introduction Air quality affects the quality of people's life directly. The concentration of air microorganisms is an important indicator to measure the air quality well or not [1], the quantity of indoor air microorganisms relates with indoor environment, population density and activities, air flow etc. The indoor environment of college campus is an important place where is the place for college students learning and living, the air quality condition is extremely important to students health. Therefore, to measure and analyze air microbiological status of campus where population concentrated, is a guarantee to creating a good environment for campus life [2-4]. The trial aims to study indoor air microorganisms content of bacteria, mold and actinomycetes as well as the characteristics of spatial and temporal distribution in the Inner Mongolia University campus, and thus to make a qualitative assessment of indoor air quality situation on campus. Materials and methods 2.1 Selection of sample and distribution of sampling points Selected four classrooms as sampling points which are sunny classrooms (0407 and 0409) and night side classrooms (0408 and 0410) in the in the Inner Mongolia University. Mid-May (14 th -21 th ) is the sampling time; we selected five time points that were 7:30 am before class, 12:00 o clock pm after class, 13:50 pm before class, 16:20 pm after class and 20:30 pm study hall respectively. Each classroom layout front, middle and back the three monitoring sites, each point arranged with three parallel sample dishes. 2.2 Sampling mediums The mediums for collecting the bacteria, mold and actinomycetes are Beef-Protein medium, Rose Bengal Agar medium, Gause No.1 cultural medium respectively. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-05/03/16,12:25:18)

2 Bacterial colony counting (cfu/m 3 ) 1374 Advances in Environmental Technologies 2.3 Sampling and counting Using the method of natural sedimentation [5, 6], the height of sampling is around m, the time of sampling is 15 minutes, each medium of every sampling point does three parallels. It must be sealed after sampled, bacteria cultured in Beef-protein medium at 37 C for 48 h; Model cultured in Martin Substratum at 28 C for 72 h; actinomycetes cultured in Gause No.1 medium at 28 C for 72 h, colonies count on each Petri dish respectively. In accordance with the Soviet Union Hommey Beam Skae formula to calculate the number of total bacteria colonies contained in per cubic meter of air (cfu m - 3 ), analyzing the distribution and the air pollution level of indoor microorganisms on campus according to the statistical result. The test used Hommey Beam Skae formula [7] to calculate the content of air microorganisms: N: the number of microbial colonies after cultured grown in a petri dish (A/dish); A: area of Petri dish (cm 2 ); t: exposure time of Petri dish in the air (min); C: microbial content of atmospheric (CFU/m 3 ). Results and Analysis 3.1 Temporal distribution of bacteria, mold and actinomycetes on campus classroom Bacteria, mold and actinomycetes also have a different distribution of quantity in a summer day of campus classroom, the results as shown in Fig.1, Fig. 2 and Fig. 3. (1) Sampling time A.0407 B.0408 C.0409 D.0410 Fig. 1. Temporal distribution of bacteria Fig. 1 shows the distribution feature of bacteria versus time. In the sunny classrooms (0407; 0409), the maximum bacterial concentration of point A (0407) is at noon, followed by night, minimum is the afternoon. But the concentration of bacteria doesn t change a lot in a day, maintained at the range of cfu m -3 basically. The maximum bacterial concentration of point C (0409) is in the morning, followed by noon, minimum is the night. In the night side classrooms (0408 and 0410), the maximum bacterial concentration of point B (0408) is in the afternoon, followed by the noon, minimum is the morning. The maximum of point D (0409) is in the morning, followed by the noon, minimum is the night. Generally, the bacterial concentration of night side classrooms is lower than sunny classrooms.

3 Actinomycetes colony counting (cfu/m 3 ) Mold colony counting (cfu/m 3 ) Advanced Materials Research Vols Sampling time Fig. 2. Temporal distribution of mold A.0407 B.0408 C.0409 D.0410 Fig. 2 shows the distribution feature of mold versus time. In the sunny classrooms (0407 and 0409), the mold concentration of point A changes that noon is higher than night, the afternoon and morning, the lowest one is afternoon. The highest mold concentration of point C is morning, followed by noon and the afternoon, afternoon, the lowest one is night. The concentration of classroom 0407 at 12:00 o clock pm and classroom 0409 at 07:10 am are higher, they are 300 cfu m -3 and 250 cfu m -3 respectively. In the night side classrooms (0408 and 0410), the mold concentration of point B changes in the order that noon, afternoon, night, the afternoon and morning. The mold concentration of point D is that noon, morning, afternoon, the afternoon and night. The maximum mold concentration is 350 cfu m -3 in the classroom 0410 at 12:00 o clock pm Sampling time A.0407 B.0408 C.0409 D.0410 Fig. 3. Temporal distribution of actinomycetes Fig. 3 shows the distribution feature of actinomycetes versus time. All of the classrooms, the actinomycetes concentration of 0407 is higher than other three sampling points, the maximum concentration is 120 cfu m -3 at noon 12:00 o clock. 3.2 Temporal distribution of the total indoor air microorganisms on campus The total number of air microorganisms change characteristics versus time as shown in Table 1. It can be seen from Table 1, it is obvious difference for indoor air microorganism concentration in different times, of which the maximum content of microorganism can reach cfu m -3 at 7:00 o clock am, that is12 times to the minimum. It attributes to the indoor air flows slowly, poor ventilation, the accumulation of more microorganisms [8-10]. Followed by 12:00 o clock pm, it is mainly because of the high temperature of noon, and the growing propagation of morning emissions [11].

4 1376 Advances in Environmental Technologies Table 1. Each time the classroom indoor air microbial content (cfu m -3 ) Sampling points sampling time A ± ± ± ± ±174.0 B ± ± ± ± ±67.9 C ± ± ± ± ±73.7 D ± ± ± ± ±61.4 Average concentration Spatial distribution and Evaluation of indoor air microorganisms on campus All-day average content of indoor microbial colonies is shown in Table 2. In the observational classrooms, the maximum of microorganism concentration is 830 cfu m -3, and the minimum is 320 cfu m -3, the average value is 600 cfu m -3. The largest number of bacteria is classroom 0409 with 676 cfu m -3, the least one is classroom 0408 with 240 cfu m -3 ; the largest number of mold is classroom 0409 with 130 cfu m -3, the least one is classroom 0408 with 70 cfu m -3 ; the largest number of actinomycetes is classroom 0407 with 50 cfu m -3, the least one is classroom 0408 with 10 cfu m -3. The indoor air microorganisms and total number of microorganisms in classroom 0408 are lower than other classrooms, mainly because of its less number of self-study, a better air circulation. The content of air microorganisms in the sunny classrooms 0409 and 0407 is obviously higher than the night side classrooms 0408 and 0410, the total count of classroom 0407 is 2.1 times to classroom 0408, and 0409 is 1.5 times to The main reason is that a suitable temperature and a good lighting in sunny classrooms, large number of students with frequent activities for a long time. The reason for why the microorganism concentration in 0409 and 0410 is higher than in 0407 and 0408 is that more organization courses. Table 2. The classroom all sampling points of microorganism air content (cfu m -3 ) Sampling points Bacteria Mold Actinomycetes Sum Cleanliness A ± ± ± ±310.0 clean B ± ± ± ±98.8 clean C ± ± ± ±608.9 clean D ± ± ± ±246.8 clean Average concentration clean As shown in Table 2, bacteria as the main air microorganism in summer campus classroom [12], accounted 77.4%, mold accounted 18.9%, actinomycetes accounted 3.7%. Additionally, the content of air microorganisms in the sunny classrooms 0409 and 0407 is obviously higher than the night side classrooms 0408 and 0410, the total count of classroom 0407 is 2.1 times to classroom 0408, and 0409 is 1.5 times to The main reason is that a suitable temperature and a good lighting in sunny classrooms, large number of students with frequent activities for a long time. The reason for why the microorganism concentration in 0409 and 0410 is higher than in 0407 and 0408 is that more organization courses. The source of indoor air microorganisms mainly from human activities, and the weather was fine before sampled, the air was dry, a better indoor ventilation, the whole environment was not suitable for germination, growth and reproduction of microbial [13], which leading to a low content of microorganisms. According to the air microorganism standards, it evaluates that each time of indoor air is clean. It also indicates that the campus has a good greening and healthy condition, which creating an excellent learning environment for all the staff and students.

5 Advanced Materials Research Vols Conclusions According to the determination of indoor air microbiological content on summer campus, we can know that: (1) Different variations of indoor air microorganisms concentration in a day, among the five time periods from 07:10 am to 20:30 pm, the maximum concentration is cfu m -3 in the morning 07:10 am, which is 12 times to the minimum, followed by 12:00 o clock pm. (2) The content of air microorganisms in the sunny classrooms 0409 and 0407 is obviously higher than the night side classrooms 0408 and 0410, the total count of classroom 0407 is 2.1 times to classroom 0408, and 0409 is 1.5 times to (3) Bacteria as the main air microorganism in summer campus classroom, accounted 77.4%, mold accounted 18.9%, actinomycetes accounted 3.7%. (4) It evaluates that each time of indoor air is clean according to the air microorganism standards. Acknowledgement This research was financially supported by Program of Higher-level talents of Inner Mongolia University (Z ). References [1] P. Ge, J. Y. Zhang, Research progress of indoor air microorganisms, Industrial & Science Tribune, vol. 10, pp , [2] X. J. Duan, X. W. Fan, and Q. S. Chen, Analysis and defending method on biological pollutants in indoor, Journal of Zhengzhou Institute Technology, vol. 16, pp. 8-11, [3] F. Qiu, and L. Zhang, Comparation study of impacting method and precipitation method for sampling of bacterial counts of air in the ward of hospital, Preventive Medicine Tribune, vol. 12, pp , [4] Y. J. Li, J. C. Qi, Z. X. Zhang, and L. L. Hou, Source, transportation and removal of indoor air microbes: a review of recent researches, J. Environment and Health, vol. 28, pp , [5] G. Q. Liu and Y. Zhou, The detection and evaluation of microorganisms for air pollution in schools, Journal of Microbiology, vol. 3, pp , [6] H. S. Sun and F. Wang. Air microbiology survey university students living spaces. Journal of Integrated Traditional Chinese and Western Medicine, vol. 14, pp. 139, [7] X. R. Fan, Microbiology experiment (Second Edition). Beijing: Higher Education Press, [8] J. J. Li, Y. P. Chang, H. Q. Li, P. D. Mao, and L. Fu, Determination and evaluation of indoor airborne microbe on campus in summer. Journal of Henan Normal University (Natural Science Edition), vol. 39, pp , [9] J. Zhang, The recommended value of indoor air microbial contamination and health standards, J. Environment and Health, vol. 18, pp , [10] D. J. Yu, L. J. Ye, M. Cheng, D. Li, S. D. Yang, and S. Y. Zheng, Monitor and analysis of airborne microbial content in college campus. Journal of Microbiology, vol. 31, pp , [11] Z. G. Fang and L. F. Yun, Progresses of airborne microbial communities in urban ecosystem, Acta Ecologica Sinica, vol. 24, pp , [12] P. Y. Sun, X. L. Liu, and J. L. Liu, Recent research progress on air microorganism. Chinese Agricultural Science Bulletin, vol. 26, pp , [13] Q. Wang, T. Tian, and Y. Jin, Determine the microbe content in atmosphere of ChuZhou City, Instrumentation Analysis Monitoring, vol. 1, pp , 2011.

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