目標：本研究探討大氣細懸浮微粒（fine particulate matter, PM_(2.5)）短期暴露對失智症與帕金森氏症（Parkinson's disease, PD）惡化影響。方法：分析「長庚醫學研究資料庫」選取嘉義縣市失智症與PD急診就醫個案（2015-2019年），連結環保署空品測站資料。以時間分層病例交叉研究法探討大氣PM_(2.5)對失智症與PD惡化影響。結果：PM_(2.5)每增加10 mg/m^3，PD急診就醫風險增加39%（Lag0），且呈現累積效應（Lag0-1至Lag0-3的勝算比[Odds ratio, OR]分別為1.29、1.31、1.36）。女性，PD急診就醫風險增加53%（Lag0），且呈現延遲（Lag1，OR = 1.31）與累積效應（Lag0-1至Lag0-5，OR分別為1.45、1.51、1.61、1.58、1.60）。特定鄉鎮（高齡化、農業與偏遠），PD急診就醫風險增加46% （Lag0）；一般鄉鎮，PD急診就醫風險則呈現延遲（Lag2，OR = 1.49）與累積效應（Lag0-2與Lag0-3，OR分別為1.63、1.90）。急診就醫年齡（> 75歲），PD急診就醫風險增加32% （Lag0）；≤75歲，PD急診就醫風險呈現累積效應（Lag0-3至Lag0-5，OR分別為2.13、2.28、2.40）。失智症則無顯著增加現象。結論：大氣PM_(2.5)短期暴露可能提高PD急診就醫風險。

Objectives: This study investigated the effects of short-term exposure to ambient fine particulate matter (PM_(2.5)) on the worsening of dementia and Parkinson's disease (PD). Methods: Data regarding emergency department visits (EDVs) for dementia and PD and air pollutant levels in Chiayi City from 2015 to 2019 were obtained from the Chang Gung Research Database and Taiwan's Environmental Protection Administration, respectively. A time-stratified case-crossover design was adopted to estimate the risks of EDVs for dementia and PD patients associated with short-term exposure to PM_(2.5). Results: Increased exposure to PM_(2.5) was associated with a 39% increase in EDVs for PD patients following a 10 mg/m^3 increase at Lag 0. Moreover, cumulative effects were observed, with odds ratios (ORs) of 1.29, 1.31, and 1.36 for Lag 0-1 to Lag 0-3, respectively. Among women, PD-related EDVs increased by 53% at Lag 0, and delayed and cumulative effects were evident, with ORs of 1.31, 1.45, 1.51, 1.61, 1.58, and 1.60 for Lag 1, Lag 0-1 to Lag 0-5, respectively. In specific towns (aged, agricultural, and rural), a 46% increase in EDVs was noted for PD at Lag 0. In general towns, PM_(2.5) exhibited delayed and cumulative effects, with ORs of 1.49, 1.63, and 1.90 for Lag 2, Lag 0-2 to Lag 0-3, respectively. Among individuals aged ≥75 years, PM_(2.5) had cumulative effects, with ORs of 2.13, 2.28, and 2.40 for Lag 0-3 to Lag 0-5, respectively. However, no significant association was observed between PM_(2.5) exposure and an increase in EDVs for dementia patients. Conclusions: Short-term PM_(2.5) exposure increased the risk of PD exacerbation and demonstrated delayed effects.