当建筑物通风系统排出的废气含有有害的污染物如有毒或腐蚀性气体、蒸气或气味时，系统设计者必须考虑建筑物周围的风会将被污染的废气再循环到空气入口，或将其变成可能危害的地面水平。因此，设计师应该能够估算出给定排气进气配置下风提供的稀释量。考虑到这个问题，ASHRAE支持了两个研究项目，第一个由Halitsky（1）于1962年完成，第二个由Wilson（2）于1975年完成，以确定一个合理的程序，用于估算风在建筑物周围传播时废气的稀释度。 这两项研究都表明，正如理论预测的那样，在距通风口一定距离处的污染物浓度与风速UH成反比，与通风口处污染物的体积流量Q成正比。引文:伊利诺伊州芝加哥ASHRAE Transactions第83卷第1部分

When the exhaust air from a building ventilation system contains an undesirable contaminant such as toxic or corrosive gases, vapors, or odors, the system designer must consider the possibility that the wind around the building will recirculate this contaminated exhaust gas to an air intake, or to ground level where it may become a hazard. For this reason a designer should be able to estimate the amount of dilution that the wind will provide for a given exhaust-intake confi gura ti on.With this problem in mind ASHRAE has supported two research projects, the first completed in 1962 by Halitsky (1) and the second in 1975 by Wilson (2), to determine a rational procedure for estimating the dilution of exhaust gases as they are carried around a building by the wind. Both of these investigations showed, as predicted by theory, that the concentration of a contaminant at a given distance from a vent was inversely proportional to the wind speed UH, and directly proportional to the volume flow rate Q of the contaminant from the vent.