ABSTRACT

Numerous epidemiologic studies demonstrated an association between an increase in levels of fine particles (particulate matter less than 2.5 um in diameter, PM_2.5) and elevation in the number of hospital admissions for cardiovascular diseases. Air pollution levels including PM_2.5 clearly decreased in Taipei City after the mass rapid transit (MRT) system began operations in 1996. The aim of this study was to investigate the extent of changes in the risk of daily hospital admissions for ischemic heart disease (IHD) over a 17-year period after the installation of a MRT system in Taipei. The full study was divided into Period 1 (1997–2000), total track length 65.1 km; Period 2 (2001–2008), total track length 75.8 km; and Period 3 (2009–2013), total track length 121.3 km. A time-stratified case-crossover analysis was conducted to estimate relative risk (RR) of hospital admissions for IHD for each 10 ug/m³ increase in PM_2.5 for different periods. On cool days, the associated RR of IHD for Period 3 was consistently lower compared to period 2 in both our single- and two-pollutant models. However, the daily risk for IHD admissions was found to be significantly higher for period 3 compared to period 2 in our single-pollutant model and in our two-pollutant models (PM_2.5+ SO₂) on warm days. The basis for this difference is unknown. Data suggests that an MRT system may provide substantial health benefits, a finding that may be helpful to urban communities, urban planners, and public health specialists.

摘要

许多流行病学研究表明，细颗粒物（直径小于 2.5 微米的颗粒物，PM _2.5）水平增加与心血管疾病住院人数增加之间存在关联。空气污染水平，包括 PM _2.51996 年捷运 (MRT) 系统开始运营后，台北市的死亡率明显下降。 本研究的目的是调查 17 年来每天因缺血性心脏病 (IHD) 住院的风险变化程度在台北安装捷运系统后的时期。完整的研究分为第一阶段（1997-2000），轨道总长65.1公里；第二阶段（2001-2008），赛道总长75.8公里；第三阶段（2009-2013），轨道总长121.3公里。进行时间分层病例交叉分析以估计PM _2.5每增加10 ug/m ^{3 时}IHD 住院的相对风险 (RR)针对不同时期。在凉爽的日子里，在我们的单污染物和双污染物模型中，与时期 2 相比，时期 3 的 IHD 相关 RR 始终较低。然而，在我们的单一污染物模型和我们的双污染物模型 (PM _2.5 + SO ₂ ) 中，在温暖的日子里，与第 2 期相比，第 3 期的每日 IHD 入院风险显着更高。这种差异的基础尚不清楚。数据表明，捷运系统可能会提供大量的健康益处，这一发现可能对城市社区、城市规划者和公共卫生专家有所帮助。