幼兒時期空氣汙染對台灣1996至2004年間出生之非氣喘學童肺功能之影響

Abstract

背景：雖然目前文獻顯示空氣汙染與學童肺功能的變化有關，但是僅有少數文獻探究終身空氣汙染暴露對學童肺功能的影響。本篇研究旨在檢驗不同年齡間所受到空氣汙染對於學童肺功能的影響 方法：在2011年一項過敏性疾病的調查中，我們在台灣22個縣市中各挑選一所國中，針對其學童發放問卷，篩選出無氣喘病史的學生後，隨機抽樣進行肺功能檢驗。根據1996年以來環保局所提供的年平均空氣汙染資料，我們利用Arc GIS地理資訊系統推算各年度，各鄉鎮的空氣污染濃度。利用學童問卷中所填寫的各年度居住鄉鎮，我們即可推算學童自出生以來每年所受的一氧化碳(CO)、二氧化氮(NO2)、臭氧(O3)、懸浮微粒(PM10)與二氧化硫(SO2)的暴露，並將其切分為出生後第一年，與出生後2~6年的暴露。我們以二階層線性回歸(Hierarchical linear regression)計算肺功能佔相較預測值百分比，並以簡單線性回歸分析肺功能與各時期汙染物的關聯性。 結果：研究調查了無氣喘病史，6~15歲的535位女學童與481位男學童。在以兩個月內空氣污染平均值加以校正下，在患有過敏性鼻炎的學童中出生後2~6歲的O3與肺活量25%時之用力呼氣流速呈顯著負相關。每4ppb的O3¬上升造成肺活量25%時之用力呼氣流速4.38%下降，95%信賴區間(-8.61%, -0.14%)。在全體受試者與其他子群體中，第一年以及2~6年間所受CO, NO2, PM10, SO2, 與用力肺活量、第一秒吐氣量、肺活量25%時之用力呼氣流速、或最大呼氣中段流速等肺功能指標並無顯著關聯性。 結論：除了最近兩個月之PM2.5及O3對於肺功能有不良影響之外，幼年時期所受到的臭氧汙染對於過敏性鼻炎的學童日後之肺功能有顯著影響。無過敏性鼻炎的學童則未發現類似的影響，顯示過敏性鼻炎可能為對O3產生肺功能影響之易感性指標。

Background: Although air pollutants have been associated with lung function changes in children, only few studies investigated life-long exposure to ambient air pollution on the schoolchildren’s lung function. This study examined effects of air pollutants on schoolchildren’s lung function in different time period. Methods: In 2011, spirograms were obtained from a random sample of non-asthmatic children from 22 middle schools in 22 administrative districts in Taiwan after a questionnaire survey for atopic diseases. Based on air pollutant data obtained from Taiwan Environmental Protection Agency monitoring stations, concentrations of pollutants in each township was estimated using the Arc9 Geographic Information System''s Kriging method. Yearly exposure of the participants to CO, NO2, O3, PM10, and SO2 was estimated according to their living townships. Hierarchical linear regression and was used to calculate lung function percent and simple linear regression was used analyze the relationship between lung function parameters and exposures in the first year after birth, and in 2-6 years of life. Results: A total of 535 girls and 481 boys without asthma history were enrolled in the study. After adjustment with 2-month average exposure, forced expiratory volume in forced expiratory flow at 25% of FVC (FEF25%) was negatively associated with O3 in 2-6 years of life. Each 4 ppb O3 increment 2-6 years of life was related to 4.38% decrement of FEF25% with 95% confidence interval [-8.61%, -0.14%]. Exposure to CO, NO2, PM10, or SO2 in the first year of life and 2-6 years had no significant association with forced vital capacity, forced expiratory volume in 1 second, forced expiratory flow at 25% of FVC, and maximal-mid expiratory flow (MMEF) in complete study group or in other subgroup analysis. Conclusion: In addition to the negative effect of past two-months level of PM2.5 and ozone, early life exposure to ozone has significant negative influence on lung function in schoolchildren with allergic rhinitis. This effect is not observed in children without allergic rhinitis. This observation indicates that allergic rhinitis may be the susceptible marker of ozone’s effect on lung function.