過去的研究中已有大量證據表明，對於易感人群而言，長期暴露於空氣污染相對於短期急性暴露，會對心血管疾病的發病率和死亡率產生明顯的影響。然而，過去大部分研究專注於短期暴露，而這些研究可能因不同研究人群或研究方法的緣故造成結果不一致，因此本篇論文採用不同的研究方法，來分析空氣污染與心血管系統之間的關聯。

本篇論文根據台灣環境部的空氣污染監測數據，主要關注污染物為懸浮顆粒物、氮氧化物、二氧化硫以及一氧化碳等污染物。由於臨床試驗數據的地理限制，本研究的分析僅限於台北市。首先，先利用空氣污染數據，研究將不同污染水平的區域進行分類，並同時提取由國立台灣大學醫學院附設醫院所提供的相對應區域臨床數據，從24小時心電圖中分別截取白天以及夜晚各四小時進行線性以及非線性心率變異性分析，再使用Wilcoxon rank sum test評估來自不同空氣污染水平的臨床數據之間的HRV指標差異。

在白天的分析中，來自較高污染水平的臨床患者在非線性的多尺度熵(MSE) Scale 15 - Scale 20數值均顯著低於低污染水平的臨床患者(p-value < 0.050)，以及去趨勢波動分析(DFA)中的短期分行標度指數 $\alpha_{1}$在兩區域間也具有顯著差異性(p-value = 0.041)。這些結果表明，在不同空氣污染水平的慢性暴露下，低污染水平的臨床試驗群體在白天的心律更加複雜，心血管具有更好的調節功能。

Past research has provided substantial evidence indicating that chronic exposure to air pollution among susceptible populations has a notable effect on the incidence and mortality rates of cardiovascular diseases compared to acute exposure. However, prior research has concentrated on brief exposure, and these inquiries have produced conflicting findings, possibly because of differences in study populations or methodologies. Therefore, this paper employs different research methods to analyze the association between air pollution and the cardiovascular system.

This study utilizes air pollution monitoring data obtained from the Ministry of Environment in Taiwan, with a specific emphasis on pollutants including suspended particulate matter, nitrogen oxides, sulfur dioxide, and other relevant substances. Due to geographical constraints, the analysis is confined to Taipei City. Using air pollution data, the research categorizes regions with different pollution levels and concurrently extracts clinical data provided by the National Taiwan University Hospital within the same regions. Four hours of the daytime and midnight were intercepted from the 24-hour ECG for linear and nonlinear heart rate variability(HRV) analysis. Following this, a Wilcoxon rank-sum test was utilized to evaluate the disparities in HRV indicators among clinical patients exposed to varying levels of air pollution.

In the daytime analysis, clinical patients from higher pollution levels exhibit significantly lower values in nonlinear multiscale entropy (MSE) for Scale 15 to Scale 20 (p-value < 0.050) and a notable difference in the detrended fluctuation analysis (DFA) short-term fractal scaling exponent $\alpha_{1}$ between the two regions (p-value = 0.041). These results indicate that, under chronic exposure to different air pollution levels, clinical trial populations with lower pollution levels have more complex daytime heart rhythms and better cardiovascular regulatory function.

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