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標題: | 車輛空調與雨刷水系統退伍軍人菌汙染調查 Legionella contaminations in the air conditioning and windscreen wiper systems of vehicles |
作者: | Yi-Wei Hsu 徐藝瑋 |
指導教授: | 張靜文(Ching-Wen Chang) |
關鍵字: | 退伍軍人菌,空調,雨刷水,雨刷精,職業駕駛, Legionellae,air conditioning,windscreen wiper fluid,commercial screenwash,professional driver, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 過去文獻指出職業駕駛與長時間開車者有較高的退伍軍人病感染風險,且添加雨刷精之車輛使用者的感染風險顯著較低,依此推測係因車體雨刷水系統與空調系統遭退伍軍人菌污染所致,然其缺少詳盡的環境調查數據佐證之。為能了解車輛雨刷水與空調系統遭退伍軍人菌污染狀況以及其影響因子,本研究採集大台北地區長途客運及貨運兩類大型車輛雨刷水與空調系統樣本,以培養法、qPCR及EMA-qPCR方法分析其中具可培養性、活性及總退伍軍人菌,同時亦分析各類環境因子並以問卷收集人員操作資訊;此外,為能評估大小型車種退伍軍人菌污染狀況,也為能擴大樣本數以探究影響退伍軍人菌污染之環境因子,本研究亦整併過往完成之民眾自用車及計程車兩類小型車體之水樣分析數據與問卷資訊,藉此解析退伍軍人菌污染實況,並探討「物理、化學及生物環境因子」、「車體資訊、用車習慣」以及「空調、雨刷水系統使用維護狀況」與退伍軍人菌污染之相關性。 大型車體空調系統出風口處之扇葉抹拭樣本顯示,總嗜肺性退伍軍人菌(Legionella pneumophila)檢出率24.4%,檢出濃度介於0.2-9.8 cells/cm2;活性嗜肺性退伍軍人菌檢出率為8.1%,檢出濃度介於0.2-3.2 cells/cm2。無論總或活性嗜肺性退伍軍人菌,長途客運與貨運之檢出率及檢出濃度相近,不具統計上顯著差異。嗜肺性退伍軍人菌與空調生物性因子之multiple logistic regression則指出,高於51.8 CFU/cm2之異營性細菌濃度與總嗜肺性退伍軍人菌檢出呈負相關(P =0.01, OR =0.20);檢出活性棘阿米巴原蟲 (偵測極限0.002-0.006 cells/cm2)則與總嗜肺性退伍軍人菌檢出呈正相關(P =0.006, OR =7.08)。車體問卷資訊之multiple logistic regression分析則顯示,相對行駛路線未經工業區及汙水處理廠之車輛,行經工業區或汙水處理廠之車輛有較高的總嗜肺性退伍軍人菌檢出機會(P =0.002, OR =6.21)。至於空調系統嗜肺性退伍軍人菌檢出濃度則未與任一調查之因子呈顯著相關。 小型車雨刷水桶水樣分析部分則發現,總、活性與培養性退伍軍人菌屬(Legionella spp.)檢出率分別為90.0%、88.0%、40.0%,而總及活性退伍軍人菌屬檢出濃度範圍分別為3.8 x 101 - 1.9 x 108 與4.9 x 100 - 1.8 x 108cells/mL,且民眾自用車及計程車兩類小型車輛之退伍軍人菌屬檢出率與檢出濃度均無車種間差異。 大小型車輛雨刷水桶內嗜肺性退伍軍人菌之檢出率與檢出濃度則達統計上顯著差異,其中,計程車、自用車、客運、貨運雨刷水桶之總嗜肺性退伍軍人菌檢出率分別為89.5%、74.2%、47.7%與33.3%,活性嗜肺性退伍軍人菌檢出率依序為68.4%、58.1%、29.6%與21.4%,培養性嗜肺性退伍軍人菌檢出率則為36.9%、29.0%、4.6%與16.7%。總嗜肺性退伍軍人菌檢出濃度介於2.7 × 100 - 2.5 × 104 cells/mL,其中,計程車與自用車檢出濃度顯著高於客運和貨運;活性嗜肺性退伍軍人菌檢出濃度則介於1.9 × 100 - 1.1 × 104 cells/mL,檢出濃度由高至低依序為自用車、計程車、客運、貨運。 至於雨刷水出水口處之水樣分析則發現,小型車之退伍軍人菌屬檢出率與檢出濃度無車種間差異,總、活性與培養性退伍軍人菌屬檢出率分別為98.0%、96.0%、56.0%,總及活性退伍軍人菌屬檢出濃度範圍則為8.0 x 102 - 1.5 x 108 與2.0 x 101 - 1.5 x 108 cells/mL。而大小型車輛之嗜肺性退伍軍人菌檢出率及檢出濃度於車種間則達統計上顯著差異,計程車、自用車、客運、貨運之總嗜肺性退伍軍人菌檢出率分別為89.5%、71.0%、36.4%和40.5%;活性嗜肺性退伍軍人菌檢出率依序為73.7%、54.8%、31.8%和33.3%;培養性嗜肺性退伍軍人菌檢出率則為42.1%、22.6%、9.1%和16.7%;總嗜肺性退伍軍人菌檢出濃度範圍介於1.9 x 100 - 2.2 x 104 cells/mL,活性嗜肺性退伍軍人菌檢出濃度則介於1.1 x 100 - 9.1 x 103 cells/mL,至於車種間檢出濃度高低趨勢則與雨刷水桶結果相同。 配對比較雨刷水桶與雨刷出水口處嗜肺性退伍軍人菌、退伍軍人菌屬、異營性細菌與活性棘阿米巴原蟲之檢出情形,顯示兩測點具有檢出與否之一致性,然出水口退伍軍人菌屬及異營性細菌之濃度則皆顯著高於雨刷水桶內濃度(P<0.05),推測係因雨刷水輸送管線內孳生生物膜所致。 雨刷水桶內水質因子與嗜肺性退伍軍人菌檢出與否之multiple logistic regression分析指出,嗜肺性退伍軍人菌與濁度呈負相關,當濁度高於1.0 NTU,培養性嗜肺性退伍軍人菌檢出機會下降;若濁度高於10.0-10.2 NTU,總嗜肺性退伍軍人菌檢出機會減低。其他負相關因子尚有pH與TDS,培養性嗜肺性退伍軍人菌在TDS高於338.5 mg/L時檢出機會下降;而總及活性嗜肺性退伍軍人菌則分別在pH高於7.1或7.2時有較低的檢出機會。另一方面,嗜肺性退伍軍人菌與硬度呈正相關,當硬度高於24.1 mg/L,培養性嗜肺性退伍軍人菌檢出機會上升;若硬度提升至56.5-63.0 mg/L,總嗜肺性退伍軍人菌檢出機會將提高。此外,水溫與異營性細菌亦與嗜肺性退伍軍人菌檢出呈正相關,總及培養性嗜肺性退伍軍人菌分別在水溫高於26.0°C及異營性細菌濃度高過5.6x〖10〗^5 CFU/mL時有較高的檢出機會。進一步以multiple linear regression分析嗜肺性退伍軍人菌檢出濃度,則未發現與濃度呈顯著相關之水質因子。除水質因子外,另將問卷所得之車體資訊與嗜肺性退伍軍人菌檢出情形亦以multiple logistic regression進行分析,發現相對市售雨刷精,添加家用清潔劑之雨刷水系統較不易檢出嗜肺性退伍軍人菌。然由於本研究為cross sectional式之環境調查研究,此相關性無法為二者具因果關係提供直接證據,故type of surfactant-containing WWF與total及viable L. pneumophila檢出之關係仍需後續研究進一步釐清。進一步以multiple linear regression分析退伍軍人菌檢出濃度與車體資訊,然並未發現任何顯著之因子。 最後,雨刷水桶水質因子與退伍軍人菌屬檢出與否之multiple logistic regression指出,其與異營性細菌濃度呈正相關,當異營性細菌濃度高於2.3 x〖10〗^4 CFU/mL時,培養性退伍軍人菌屬檢出機會上升。然進一步分析退伍軍人菌屬檢出濃度,multiple linear regression並未發現與檢出濃度呈顯著相關之水質因子。 總結本研究之新穎性,透過詳盡之環境調查,本研究證實車輛空調系統中活性嗜肺性退伍軍人菌之存在,車內環境為職業駕駛及乘客潛在暴露環境。此外,藉由雨刷水系統之相關性分析,本研究得以評估多因子互動下退伍軍人菌之顯著相關因子,可為未來污染管理計畫之提供參考。 Previous studies show that driving as occupation and driving for long period of time are significant risk factors of Legionnaires’ disease. In addition, comparing to no commercial screenwash addition, drivers and passengers who ride vehicles with commercial screenwash in windscreen wiper systems have lower risk of Legionnaires’ disease infection. A plausible assumption indicates that windscreen wiper systems can serve as reservoir of Legionellae and thus contaminate the indoor environment of vehicles. However, thorough environmental surveillance in support of this assumption is still unavailable. In order to assess the contamination profile and related factors that influence Legionellae in vehicles, swab samples and water samples were collected from buses, trucks in Taipei metropolitan area. Culture assay, qPCR, EMA-qPCR were conducted to provide information about total, viable and culturable Legionella pneumophila. Meanwhile, environmental parameters (such as water parameters of windscreen wiper fluid and viable Acanthamoeba on vents of air conditioning), and vehicle characteristics (such as operation status of vehicle, habitual car use, usage and maintenance of air conditioning and windsreen fluids systems) were also investigated. Furthermore, water samples and questionnaire of taxi and private cars collected in previous study were included in the interest of evaluating contamination profile in various car type and expanding sample size for correlation analysis. By organizing and taking in information of small cars, this study can investigate positive rate and concentration of Legionellae with broader context and better investigate the relationship between Legionellae, environmental parameters and vehicle characteristics. Results of air conditioning systems of large vehicles showed that positive rate and concentration of total L.pneumophila was 24.4% and 0.2-9.8 cells/cm2;positive rate and concentration of viable L.pneumophila was 8.1% and 0.2-3.2 cells/cm2. Statistical results found no difference between buses and trucks regarding the positive rate and concentration. Multiple logistic regression of L.pneumophila and microbiological factors affirmed that heterotrophic bacteria counts (HPC) greater than 51.8 CFU/cm2 is negatively associated with the presence of total L.pneumophila (P value =0.01, OR=0.20);as for viable Acanthamoeba, the presence of this protest (detection limit: 0.002-0.006 cells/cm2) is positively related to total L.pneumophila (P value =0.006, OR=7.08). Additionally, multiple logistic regression of L.pneumophila and vehicle characteristics pointed out the relationship between driving route and presence of L.pneumophila. In fact, driving through industrial or sewage treatment areas is risk factor of the presence of total L.pneumophila (P value =0.002, OR=6.21). Lastly, when analyzed the correlation of L.pneumophila concentrations and factors investigated in this study, no statistically significant association was revealed. Positive rates and concentrations of Legionella spp. in windscreen wiper tanks from small cars showed no difference between taxi and private cars. Positive rates of total, viable and culturable Legionella spp. of small cars were 90.0%、88.0%、40.0% respectively. Concentrations of total and viable Legionella spp. were 3.8 x 101 - 1.9 x 108 and 4.9 x 100 - 1.8 x 108cells/mL. In contrast, positive rates and concentrations of L.pneumophila in windscreen wiper tanks were statistically different among taxi, private car, bus and truck. Positive rates of total L.pneumophila of taxi, private car, bus and truck were 89.5%、74.2%、47.7% and 33.3% respectively. Positive rates of viable L.pneumophila of taxi, private car, bus and truck were 68.4%、58.1%、29.6% and 21.4%. As for culturable L.pneumophila, positive rates were 36.9%、29.0%、4.6% and 16.7%. Concentrations of total L.pneumophila were 2.7 x 100 - 2.5 x 104cells/mL, with higher concentrations in small cars than large vehicles. Concentrations of viable L.pneumophila were 1.9 x 100 - 1.1 x 104cells/mL. Sorting concentrations of viable L.pneumophila from high to low for various vehicle, taxi will be the highest, followed by private car, bus, and truck sequentially. With respect to Legionellae in outlets, positive rates and concentrations of Legionella spp. in windscreen wiper outlets from small cars showed no difference between taxi and private cars. Positive rates of total, viable and culturable Legionella spp. of small cars were 98.0%、96.0%、56.0% respectively. Concentrations of total and viable Legionella spp. were 8.0 x 102 - 1.5 x 108 and 2.0 x 101 - 1.5 x 108 cells/mL. In contrast, positive rates and concentrations of L.pneumophila in windscreen wiper outlets were statistically different among taxi, private car, bus and truck. Total L.pneumophila were detected in 89.5%、71.0%、36.4% and 40.5% of taxi, private car, bus and truck. Viable L.pneumophila were detected in 73.7%、54.9%、31.8% and 33.3% of taxi, private car, bus and truck. Culturable L.pneumophila presented in 42.1%、22.6%、9.1% and 16.7% of taxi, private car, bus and truck samples. As for concentrations of L.pneumophila, total L.pneumophila was 1.9 x 100 - 2.2 x 104cells/mL and viable L.pneumophila was 1.1 x 100 - 9.1 x 103cells/mL. Sorting concentrion from high to low, the trends of outlet samples are in accordance with tanks. Comparing paired tank and outlet samples, the presence of microbiological factors (Legionella spp., L.pneumophila, HPC and viable Acanthamoeba) were statistically comparably between these two sampling sites. Nonetheless, the concentrations of Legionella spp. and HPC were significantly higher in outlets compared to their counterparts in tanks(P<0.05), suggesting tubing of outlets as plausible niche for biofilm. According to multiple logistic regression between the presence of L.pneumophila and water parameters in tanks, negative relationship was found between turbidity and L.pneumophila. Turbidity higher than 1.0 NTU and 10.0-10.2 NTU are associated with lower risk of culturable and total L.pneumophila detection respectively. In addition, TDS higher than 338.5mg/L is related to lower odds of culturable L.pneumophila detection while pH value higher than 7.1 and 7.2 also showed negative association with total and viable L.pneumophila. On the other hand, hardness is positively related to the presence of culturable and total L.pneumophila when hardness value reaches 24.1 mg/L and 56.5-63.0 mg/L. Regarding water temperature and HPC, temperature higher than 26°C and HPC greater than 5.6x〖10〗^5CFU/mL will elevate the odds of detecting L.pneumophila. Correlation of L.pneumophila concentrations and water parameters were also assessed, yet no significant result was found in multiple linear regression. Correlation analyses between L.pneumophila and vehicle characteristics demonstrated that the type of surfactant-containing WWF is strongly associated with the presence of L.pneumophila. In fact, comparing with household detergent addition, WWF with commercial screenwash addition is prone to L.pneumophila contamination. However, since this study is a cross-sectional investigation, the finding should not be viewed as straightforward implication of cause effect relationship. To clarify the effect of type of surfactant-containing WWF on the presence of L.pneumophila, futher investigation is needed. Lastly, while multiple linear regression were conducted, no vehicle characteristics was significantly correlated with L.pneumophila concentrations. With respect to Legionella spp., positive relationship between the presence of culturable Legionella spp. and HPC greater than 2.3 x〖10〗^4CFU/mL was revealed in multiple logistic regression. Nonetheless, statistical analyses failed to find significant factor correlated to concentrations of Legionella spp.. Summarizing the novel information discovered in this study, through comprehensive environmental investigation, this study proved the existence of viable L.pneumophila in air conditioning systems and thus might serve as potential source of exposure for occupational drivers and passengers. Meanwhile, after taking multiple factors into consideration, factors associated with Legionellae in windscreen wiper systems were revealed by correlation analyses, providing further reference material for pollution control plan. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/54908 |
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顯示於系所單位: | 環境衛生研究所 |
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