負壓隔離病房內有關通風方面之建造指引與設計規範，包括供排氣口位置、供排氣風量差異、每小時換氣次數以及負壓值等，至今許多國家已有了明確的規定。其中負壓之目的在於避免具有感染性生物氣膠自房內向病房外擴散，造成院內感染。而在既有之供氣量以及供排氣風量差異條件下，門縫開口大小為控制負壓值的重要因素。但是，在建造病房過程中對於門縫開口大小未有明確之規範，而造成實際施工時無從參考，需利用嘗試法加以決定。 為了提供未來建置與改善病房實務上之依據，本研究利用一座具有可調整供排氣風量之獨立通風系統以及體積大小可改變的暴露艙，來模擬無前室之負壓病房，獲得不同體積大小與每小時換氣次數條件下，以負壓值達到8 Pa需求為前提，進行所對應之門縫大小之實驗。結果發現，負壓值隨著門縫高度增加而減少，門縫高度達到特定範圍後其負壓值下降趨勢較為平坦，甚至接近無壓差狀態。在固定門縫高度下，每小時換氣次數越小其負壓值也越低；而且在本次實驗的三個體積條件下(45.38 m3、36.93 m3、28.47 m3)，每小時換氣次數為4次，於可量測門縫高度最小值0.2 cm時，都無法達到8Pa的負壓值。因此可知，欲達到負壓值至少8 Pa的要求下，每小時換氣次數至少需大於4次以上，或是將排氣量與供氣量差異調整大於目前所建議的20%。藉由本次研究之數據結果，亦推導出開口面積推估模式，可提供未來負壓隔離病房設計參考及建造時之實務應用。

Abstract The location of air supply and exhaust, differential of supply and exhaust air, air change per hour and negative pressure have been proposed in the specification of negative pressured isolation ward. The purpose of negative pressure is to prevent virus from spreading out. The doorway size is an important factor on negative pressure. However, the doorway size is never suggested in the guidelines. The aim of this study is to investigate the effect of doorway size on pressure difference under different room sizes and air change rates. A volume adjustable chamber with independent ventilation system was used to simulate negative pressured isolation room without anteroom. By changing doorway size, the corresponding negative pressure could be measured under different room size and air change per hour (ACH). It was found that the negative pressure decreases with the increasing doorway size, and reaches to zero when the doorway size is large enough. When the doorway size is fixed, the pressure difference decreases with ACH. When the ACH is equal to 4, the pressure difference is always smaller than 8 Pa though the doorway size is kept at minimum (0.2cm). Therefore, to maintain negative pressure is equal to 8 Pa, the ACH is required to be greater than 4, or increasing the exhaust air at least 20% greater than supply air. The model of doorway size was also developed by using the experimental data. The results provide useful information for future design and improvement of negative pressured isolation ward.