| Summary: | 碩士 === 崑山科技大學 === 環境工程研究所 === 99 === The indoor environment is full of materials that are harmful to human health, and one of them is bio-aerosol. Bio-aerosols are aerosolized suspensions of organisms or organic matter, such as bacteria (Legionella pneumophila, E.Coli), fungi (molds), viruses (avian influenza virus, SARS virus), organic particles like pollen, dead plant, animal furs and hairs; these matters may become sources of lethal pathogens and allergens in some cases.
Taiwan is situated in the sub-tropical climate zone with an average annual humidity of 80% and above. The high outdoor temperatures of summer seasons resulted in long term indoor usage of air conditioning, and coldness in winter produced poor ventilation due to closing of the doors and windows, all of which may contribute to growth of biological contaminants such as bacteria and fungi. The geographical differences in Taiwan also contributed to variations in the distribution of indoor bio-aerosol concentrations; the tropical climate regions in Southern Taiwan have significantly higher concentrations of fungi than Northern Taiwan, and the effects are even more pronounced during fall/winter seasons.
This study has selected 39 locations (including medical institutes, schools, office buildings, supermarkets, libraries, train stations and cinemas) for data collection, starting with sectional readings taken from simple direct-measurement meters. Subsequently, a representative indoor space from each location was chosen for further testing, based on the initial results collected. The tests were then conducted in accordance with methods promulgated by the Environment Protection Agency. The test results showed that the concentration range of type 1 CO2 was between 699~1022ppm (recommended value: 600ppm), and the bacterial concentration was 958~3025CFU/m3 (recommended value: 500CFU/m3). The standards exceeding the ratio of these two tests was 100%; the Type 2 CO2 concentration was 518~1182 ppm (recommended value: 1000ppm) and the standard exceeding ratio was 14%; bacterial concentration was 178~3183CFU/m3 (recommended value: 1000CFU/m3) and the standard exceeding ratio was 43%; the fungal concentration was 107~4500CFU/m3 (recommended value: 1000CFU/m3), and the ratio was 29%. The main reasons for the overtly high CO2 concentration were due to excessive indoor personnel and inadequate ventilation; the sources of bacterial and fungal concentrations were from the indoor personnel, filters in the ventilation and air conditioning systems, kitchen waste and garbage collection areas.
Additionally, to further investigate the relationship between CO2 and bacteria, the current study conducted statistical analysis on the CO2 and bacterial concentrations in the aforementioned locations. Our results showed a medium to high degree of correlation (r=0.71); similar statistical result was also obtained in medical institutes (r=0.72). Our results suggested that indoor airborne bacterial concentration may be positively correlated with indoor personnel density. In addition, because the outdoor fungal concentrations outdoors during fall/winter seasons in Southern Taiwan were often higher than those indoors, the current study have also performed initial strain identifications on the samples collected from outdoor sources of excessively high fungal concentrations. Out of the four dominant fungal species tested, 3 strains were indentified to be Cladosporium, and the remaining strain was the Fusarium.
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