Air infiltration is an important way to exchange indoor air with outdoors. It significantly impacts energy consumption and air quality of buildings. Fine particles (PM_2.5) in the outdoor atmosphere environment are a potential natural tracer for the measurement of air infiltration rate, especially in the long term field measurement. In this study, a PM_2.5-based method, named as CADR (clean air delivery rate) method, is developed to supplement traditional tracer gas method in order to make routine measurement in realistic environments possible and convenient. An air cleaner is installed indoors to reduce indoor PM_2.5 concentration. Air infiltration is determined by fitting a model to the decreasing concentration data. Comparison with CO₂ decay method in four different indoor environments gives a normalized mean error of 19% and a correlation coefficient of 0.80 for this method. This justifies the CADR method as a feasible option to measure air infiltration rate. Although subject to several constraints, the proposed method would facilitate field measurement under realistic conditions by being combined with current tracer gas methods.

空气渗透是与室外交换室内空气的重要方式。它严重影响建筑物的能耗和空气质量。在室外大气环境中，细颗粒（PM _2.5）是潜在的自然示踪剂，可用于测量空气渗透率，尤其是在长期现场测量中。在这项研究中，开发了一种名为PMR的基于PM _2.5的方法，以补充传统的示踪气体方法，从而使在现实环境中进行常规测量成为可能和方便。空气净化器安装在室内，以降低室内PM _2.5浓度。空气渗透是通过对降低的浓度数据拟合模型来确定的。与CO _2的比较在四个不同的室内环境中使用衰减法，该方法的归一化平均误差为19％，相关系数为0.80。这证明了CADR方法是测量空气渗透率的可行选择。尽管受到一些限制，但通过与当前的示踪气体方法相结合，所提出的方法将有助于在实际条件下进行现场测量。