| Changing microbial concentrations are associated with ventilation performance in Taiwan's air-conditioned office buildings. | |
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MedLine Citation:
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PMID: 15660566 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Our study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research. Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings. PRACTICAL IMPLICATIONS: As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place. |
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Authors:
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P-C Wu; Y-Y Li; C-M Chiang; C-Y Huang; C-C Lee; F-C Li; H-J Su |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Indoor air Volume: 15 ISSN: 0905-6947 ISO Abbreviation: Indoor Air Publication Date: 2005 Feb |
Date Detail:
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Created Date: 2005-01-21 Completed Date: 2005-03-15 Revised Date: 2009-09-29 |
Medline Journal Info:
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Nlm Unique ID: 9423515 Medline TA: Indoor Air Country: Denmark |
Other Details:
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Languages: eng Pagination: 19-26 Citation Subset: IM |
Affiliation:
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Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Air Conditioning* Air Movements Air Pollution, Indoor / analysis* Bacteria / growth & development*, isolation & purification* Environmental Monitoring Facility Design and Construction Fungi / growth & development*, isolation & purification* Humans Population Density* Regression Analysis Taiwan Ventilation* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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