環境暴露與孩童呼吸道健康效應研究

Abstract

前言： 呼吸道感染與過敏症是孩童常見的疾病。肺炎與氣喘則是造成孩童死亡與不健康的主要下呼吸道疾病。過去證據顯示環境暴露與呼吸道疾病有關。了解是否環境中可改善的呼吸系統為害因子有其重要性。我們藉由2005年與2011年兩個全國性調查來評估出生前與出生後之孩童呼吸道健康風險因子，目標的疾病包括肺炎、氣喘、與肺功能下降。 方法： 台灣出生世代研究從2005年開始，我們的研究分析六個月大的出生世代調查資料。該調查使用問卷蒐集孩童相關資訊，包括：基本資料、母親懷孕時狀況、孩童出生後的環境狀況、與孩童疾病狀況(包括住院肺炎)。使用逐步向後羅吉斯迴歸用來評估可能的風險因子，且針對可改善的風險因子計算族群的可歸因危險性。 於2011年四月至五月間，我們使用國際兒童氣喘暨過敏研究問卷針對6~15歲國中國小學童進行全國性的橫斷性調查。總共有264間教室被隨機從22所國中與22所國小中選出。選定教室內的所有學童被詢問參與問卷評估，問卷為學童帶回給家長填寫。之後再由每間教室隨機抽樣六位沒有氣喘的學童，並詢問其家長參與後續肺功能檢測及口腔黏膜與尿液之蒐集的意願。每間教室空氣中的黴菌孢子使用Burkard個人採樣器於肺功能檢查當天早上進行採樣，並於之後以顯微鏡讀取，並計算出每立方公尺內的各種黴菌孢子數。空氣汙染物的數據來自於位於學校一公里內環保署空氣汙染監測站的資料。相關性的探討則使用階層羅吉斯與線性迴歸，並使用階層線性與非線性模型處理多層次的資料之統計分析。 結果： 於24200位隨機選取的主要孩童照顧者中，21248(87.8%)參與出生後六個月之台灣出生世代研究調查。六個月大嬰兒的肺炎盛行率為0.62%。多變項羅吉斯回歸顯示與嬰兒肺炎有關之因子包括早產、先天性心肺疾病、懷孕期間抗生素使用、母親懷孕時體重過重、懷孕期間暴露二手菸、與懷孕期間媽媽抽菸、與出生後家中牆壁有黴斑等。我們於2011年所進行的全省學童調查，回收有效問卷6346份(回覆率88.7%)。曾經被醫師診斷過氣喘的盛行率為11.7%，曾經被醫師診斷有氣喘且現在仍有氣喘症狀的盛行率為7.5%，而目前氣喘會於休假日較有改善者的盛行率為3.1%。於264間教室內的總黴菌孢子數、黑麴菌/青黴菌孢子數、與擔孢子數的幾何平均數分別為2181、49、與318孢子每平方公尺。黑麴菌/青黴菌孢子數與擔孢子數與現有氣喘和氣喘會於休假日較有改善者有顯著相關。且現有氣喘者中，有41%提及於休假日氣喘症狀改善。此外，共有1494位非氣喘孩童具有完整的肺功能檢查結果。每增加16.9微克每立方公尺濃度的過去三個月空氣中細懸浮微粒之暴露，造成學童肺活量下降118毫升，第一秒吐氣肺活量下降100毫升，最大呼氣中期流速下降127毫升每秒。肺功能檢測前一天的臭氧暴露與最大呼氣中期流速下降有關。於年紀較小的孩童(6~10歲)中，細懸浮微粒額外造成一秒率和最大吐氣中期流速與肺活量比值的下降。 結論： 我們的研究顯示嬰兒肺炎與幾個可改善風險因子有關，包括母親懷孕時體重過重、懷孕期間暴露二手菸、與懷孕期間媽媽抽菸、與出生後家中牆壁有黴斑等。學童的現氣喘與教室空氣中的黑麴菌/青黴菌孢子數、與擔孢子數有關。於6~15歲孩童中，慢性暴露細懸浮微粒可造成肺活量下降，然而急性暴露臭氧則造成最大吐氣中期流速下降。於年紀較小的孩童(6~10歲)，慢性細懸浮微粒的暴露額外增加阻塞性呼吸道型態之肺功能變化。我們的結果支持對於環境風險因子對於孩童呼吸道健康之持續研究的需要。

Background and Objective: Respiratory tract infection and allergy are common illnesses in children. Pneumonia and asthma are diseases involving lower respiratory tract and contributing to mortality and morbidity in children. Evidences have shown that respiratory diseases are closely related to environmental exposures. It is important to know whether there are any other modifiable environmental risk factors for children’s respiratory health. Two nationwide surveys in 2005 and 2011 were conducted to evaluate prenatal and postnatal risk factors for children's respiratory health problems, including pneumonia, asthma and lung function reduction. Method: The Taiwan Birth Cohort Study (TBCS) was started in 2005. This study analyzed the data collected from the survey at 6-month-old of TBCS. Information on demographics, maternal conditions, postnatal environmental conditions, and hospitalization for pneumonia were inquired by questionnaire. Backward stepwise logistic regression was used to identify potential risk factors. Population attributable risk was calculated for each modifiable risk factor. Between April and May 2011, a nationwide cross-sectional study in Taiwan using a modified Chinese version of the International Study of Asthma and Allergies in Childhood (ISSAC-C) questionnaire was conducted in schoolchildren aged 6~15. There are 264 classrooms randomly sampled from 22 elementary and 22 middle schools. All children in selected classrooms were asked for questionnaire survey. Six of participated non-asthmatic children in each classroom were randomly sampled and asked for further lung function test and collection of oral mucosa and urinary samples. Fungal-spore sampling was conducted for 40 minutes continuously during class in the morning of lung function test using the Burkard Personal Air Sampler. Fungal spores was counted by microscopy and presented as spore counts per cubic meter. Complete monitoring data of air pollution were obtained from 24 Taiwan EPA monitoring stations within 1-km catchment area of selected schools. Hierarchical logistic and linear regression models were applied for statistical analysis on multi-level data. Result: Among the 24200 randomly sampled main caretakers invited, 21248 (87.8%) participated in the 6-month-old TBCS survey. The prevalence of pneumonia was 0.62% in 6-month-old infants. Multivariate logistic regression analysis showed that preterm birth, congenital cardiopulmonary disease, antibiotics use during pregnancy, maternal overweight, daily prenatal exposure to environmental tobacco-smoke, maternal smoking during pregnancy, and visible mold on walls at home are risk factors associated with infantile pneumonia. Our 2011 schoolchildren survey was completed by 6346 out of 7154 parents (88.7%). The prevalences of physician-diagnosed asthma, current asthma, and asthma with symptoms reduced on holidays or weekend (ASROH) were 11.7%, 7.5%, and 3.1%, respectively. The geometric mean spore concentrations of total fungi, Aspergillus/Penicillium, and basidiospores in the 264 classrooms were 2181, 49, and 318 spores/m3. Aspergillus/Penicillium and basidiospores were significantly correlated with current asthma and ASROH after adjusting for personal and school factors. Of those with current asthma, 41% reported relief of symptoms during weekends. In addition, adequate spirograms were obtained from 1494 non-asthmatic children. Lung function changes per inter-quartile increase (16.9 μg/m3, 32-48.9) of the average levels of the past three months of particulate matter <2.5 μm (PM2.5) were -118 ml on FVC, -100 ml on FEV1, and -127 ml/s on MMEF. Lag-1-day ozone exposure was associated with decreased MMEF. In children aged 6-10, PM2.5 was additionally associated with decreased FEV1/FVC and MMEF/FVC ratios. Conclusion: Infantile pneumonia is associated with several modifiable risk factors, including maternal overweight, maternal use of antibiotics, maternal tobacco-smoke exposure, and postnatal exposure to home molds. Current asthma in school children was associated with spore concentrations of Aspergillus/Penicillium and basidiospores in classrooms. In children aged 6-15 years, sub-chronic exposure to ambient PM2.5 leads to reduced lung capacity, whereas acute exposure to ozone decreases mid-expiratory flow. In children aged 6-10 years, additional airway obstructive patterns in lung function are associated with PM2.5 exposure. Our results emphasize the continued need to control environmental risk factors for children’s respiratory health.