根据公布的统计数据，大多数结核病污染发生在未知和意外的结核病携带者身上。根据建筑规范的要求，在医疗设施的许多区域都可以发现这种情况，空气不会排到室外，而是再循环到设施的其他区域。尽管任何排气系统而不是再循环空气都能极大地降低污染风险，但由于能耗增加，所有排气系统均未使用。作为替代方法，循环空气经过高效空气过滤器（HEPA）过滤。为了评估这些系统的经济影响，针对三个地点:洛杉矶、纽约和亚特兰大，使用五种替代方案对医疗设施进行生命周期成本分析:再循环、HEPA过滤，或将100%的废气应用于候诊室，并将HEPA过滤和100%的废气应用于整个建筑。结果表明，HEPA过滤系统的成本高于100%排气系统，但其附加年成本和使用寿命较低- 如果与一名结核病患者的医疗费用（约10万美元）相比，研究的任何替代方案相对于使用再循环系统的周期成本都是微不足道的。单位:I-PCITION:研讨会，ASHRAE交易，第106卷，pt。2.

According to published statistical data, most TB contamination occurs from unknown and unsuspected TB carriers. It can be found in many areas of a health care facility where, based on the building code requirements, the air is not exhausted to the outside but recirculated to other areas of the facility. Although any system exhausting instead of recirculating the air greatly minimizes the risk of contamination, all-exhaust systems are not used because of their increased energy consumption. As an alternative method, recirculated air is HEPA filtered. To assess the economic impact of these systems, a life-cycle cost analysis is performed for a health care facility using five alternatives, recirculation, HEPA filtration, or 100% exhaust applied to the waiting rooms and HEPA filtration and 100% exhaust applied to the entire building, for three locations: Los Angeles, New York, and Atlanta. The results show that the HEPA filtration system costs more than the 100% exhaust system, but the supplementary annual costs and life-cycle costs of any of the alternatives studied versus using the recirculation system are insignificant if compared to the cost of medical treatment for one TB patient--approximately $100,000.Units: I-P