台北都會區空氣污染和氣象變化與慢性阻塞性肺病患者健康風險之探討

Abstract

都市化常會伴隨氣象變化影響到空氣品質，進而導致都會區整體空氣品質惡化。我國老年化人口呈現逐年增加趨勢，並且地狹人稠及都市化程度偏高，又因氣候變遷導致氣溫增加趨勢，致使都會地區衍生嚴重空氣污染，對易感受之老年族群健康威脅升高。本研究包括兩部分，第一部分是為了解我國都會區與鄉鎮區之空氣污染長期趨勢變化差異，即針對台北、台中及高雄等三大都會區與花蓮縣空氣污染與氣象長期變化進行探討分析，第二部分則是選擇台北都會區為研究地區，探討空氣污染與氣象長期變化對老年慢性阻塞性肺病（Chronic Obstructive Pulmonary Disease , COPD）患者之健康影響。 本研究選擇國內三大主要都會區（台北都會區、台中市及高雄市）及鄉鎮地區（花蓮縣）為研究地區，針對1993年至2012年空氣污染與氣象長期變化進行探討，並選擇台灣最大都會區（台北都會區，包括台北市和新北市）進行空氣污染與氣象長期變化（2000年至2013年）對老年COPD病患至醫院急診影響之研究。 本研究所用空氣污染 (PM10, PM2.5, O3, SO2, NO2 and CO)、氣象(氣溫、相對濕度及氣壓)及COPD急診病患資料分別來自我國環保署空氣品質監測站、中央氣象局氣象測站及衛生福利部健保資料庫。本研究採用病例交叉研究法(Case-crossover study)，並以條件式邏輯迴歸分析模式(Conditionsl logistic regression model)探討分析台北都會區各種環境因子(空氣污染與氣象因素)在不同延遲日時，對老年COPD病患急診之風險，並以勝算比(Odds Ratio, OR)及95%信賴區間(95% Confidence Interval, 95% CI)來呈現。 研究結果顯示我國都會地區空氣污染濃度明顯高於鄉鎮地區，其中並以高雄市的O3，SO2，PM10和PM2.5濃度最高，並發現各研究地區的CO，NO2，PM10，PM2.5和SO2濃度均有明顯下降趨勢，然而O3卻呈現上升之趨勢。我們也發現O3和PM濃度分佈均呈現雙峰分布之季節性變化趨勢。台灣自1993年以來迄今空氣品質已有顯著改善，顯見我國長期推動空氣品質管制策略措施之成效，並且也發現台北都會區空氣品質在1996年捷運系統開通後已有明顯改善。研究亦發現台北都會區PM2.5、O3和SO2對於65歲至79歲之老年COPD病患至醫院急診之影響具有顯著較大的延遲性效應影響(PM2.5之延遲天數為4天，O3和SO2之延遲天數為5天) ，PM2.5、O3和SO2濃度每增加一個四分位數(Interquartile Range, IQR)，分別增加0.8%(95% CI＝0.1%-1.6%, p=0.029), 1.3%(95% CI＝0.4%-2.3%, p=0.007)和10.3%(95% CI＝1.6%-19.7%, p=0.02)的急診風險。在較溫暖天氣(>27.9℃)時，PM2.5與O3共存時會對老年COPD病患至醫院急診人數增加具有顯著較大的影響(OR=1.037, 95% CI＝1.001-1.074, p=0.047 )。此外，不論O3或是SO2與其他空氣污染物共存時，在較高之相對濕度(75.1%-81.5%)和氣壓差(3.91hpa-4.80hpa)天氣型態出現時，分別會增加老年COPD病患至醫院急診之風險。 研究發現氣象變化會影響都會區空氣污染，同時也證實我國最大都會區之空氣污染和氣象會對易感受之老年族群COPD病患至醫院急診人數具有加成效應之影響，對於空氣污染物對人類健康影響及其生物效應機制，有必要更進一步探討。環保及衛生相關主管機關宜再審視檢討現有空氣污染管制政策，並加強健康教育宣導，以確保易感受老年族群之健康。

Urbanization causes air pollution in metropolitan areas, coupled with meteorological factors that affect air quality. Taiwan has the second highest population density in the world with higher urbanization, and the proportion of the elderly population is increasing rapidly. Serious urban air pollution had become a threat to susceptible elderly population. This study aimed to investigate the long-term variations of air pollution in the metropolitan (Taipei area, Taichung City, and Kaohsiung City) and rural areas (Hualien County), and to evaluate the relationship among air pollution, meteological factors, and COPD-associated ED visits of susceptible elderly population in Taipei city and New Taipei city. Data of air pollutants concentrations (PM10, PM2.5, O3, SO2, NO2 and CO), meteorological factors (daily temperature, relative humidity and air pressure), and daily COPD-associated ED visits were collected from Taiwan Environmental Protection Administration (EPA) air monitoring stations, Central Weather Bureau stations, and the Taiwan National Health Insurance database, respectively. We used a case-crossover study design and conditional logistic regression models for evaluating the associations between the environmental factors and COPD-associated ED visits. The analytical results indicate that levels of air pollution in metropolitan areas were greater than in the rural area. Kaohsiung City had the highest levels of O3, SO2, PM2.5 and PM10. Clear downward trends for CO, NO2, PM10, PM2.5, and especially SO2 concentrations were found in the surveyed areas, whereas O3 showed no decrease. Both O3 and PM concentrations showed similar bimodal seasonal distributions. Taiwan’s air quality has improved significantly since 1993, indicating the effectiveness of promoting air pollution strategies and policies by the Taiwan EPA. Air pollution had an obvious improvement in Taipei area after the MRT system began operations in 1996. Additionally, single lag day effects were found greatest on lag 4 for PM2.5 exposure, on lag 5 for both O3 and SO2 exposure, corresponding to risk of elderly COPD emergency visits (65 to 79 years old) of 0.8% (95% CI=0.1%-1.6%, p=0.029), 1.3% (95% CI=0.4%-2.3%, p=0.007), and 10.3% (95% CI=1.6%-19.7%, p=0.02) with IQR increment of pollutant concentrations, respectively. In warmer days (>27.9℃), a significantly greater effect (OR=1.037, 95% CI＝1.001-1.074, p=0.047 ) on elderly COPD-associated ED visits was estimated for PM2.5 with coexistence of O3. Additionally, either O3 or SO2 combined with other air pollutants increased the risk of elderly COPD-associated ED visits in the days of high relative humidity (75.1%-81.5%) and air pressure difference (3.91-4.80 hpa), respectively. Evidence of the combined effect of air pollutants and meteorological factors on COPD-associated ED visits in the susceptible elderly people was found. It suggests that government authorities revise existing air pollution regulation policies, and strengthen health education propaganda in order to ensure the health of the susceptible elderly population.