使用连续空气监测仪（CAM）的主要动机是，当超过显著的放射性浓度值时，需要以可接受的误报率以最准确的方式迅速发出警报，以便采取适当措施减少相关人员的暴露。 该CAM的性能不仅取决于以判定阈值为特征的计量方面，检测极限和测量不确定度，以及以响应时间为特征的动态能力，以及与可接受的误报率相对应的最小可检测活性浓度。 理想的性能是具有尽可能低的最低可检测活性浓度，且响应时间非常短，但不幸的是，这两个标准是相反的。因此，重要的是，CAM以及调整参数和报警级别的选择应符合辐射防护目标。 需要了解一些因素来解释凸轮的响应，并选择合适的凸轮类型及其工作参数。 在这些因素中，重要的是了解所涉放射性核素的半衰期，以便选择适当的探测系统及其相关的评估模式。 使用过滤介质累积取样技术的CAM通常有两种类型: a） 固定过滤器； b） 移动过滤器。 本文件首先描述了每种凸轮类型的操作原理，即: -考虑短或长放射性核素半衰期值的不同评估模型， -动态特性和响应时间的确定。 在大多数情况下，当涉及具有重要放射性毒性的放射性核素（ALI值较小）时，使用CAM。这些放射性核素通常具有较长的半衰期值。 然后，使用长半角描述CAM特征极限（判定阈值、检测极限、覆盖区间极限）的确定- 生命评估模型。 最后，指出了确定最小可检测活性浓度和警报设置的可能方法。 本文件附件显示了CAM数据的实际示例，说明了如何通过确定响应时间、特征限值、最小可检测活动浓度和报警设置来量化CAM性能。

The use of a continuous air monitor (CAM) is mainly motivated by the need to be alerted quickly and in the most accurate way possible with an acceptable false alarm rate when a significant activity concentration value is exceeded, in order to take appropriate measures to reduce exposure of those involved. The performance of this CAM does not only depend on the metrological aspect characterized by the decision threshold, the limit of detection and the measurement uncertainties but also on its dynamic capacity characterized by its response time as well as on the minimum detectable activity concentration corresponding to an acceptable false alarm rate. The ideal performance is to have a minimum detectable activity concentration as low as possible associated with a very short response time, but unfortunately these two criteria are in opposition. It is therefore important that the CAM and the choice of the adjustment parameters and the alarm levels be in line with the radiation protection objectives. The knowledge of a few factors is needed to interpret the response of a CAM and to select the appropriate CAM type and its operating parameters. Among those factors, it is important to know the half-lives of the radionuclides involved, in order to select the appropriate detection system and its associated model of evaluation. CAM using filter media accumulation sampling techniques are usually of two types: a) fixed filter; b) moving filter. This document first describes the theory of operation of each CAM type i.e.: — the different models of evaluation considering short or long radionuclides half-lives values, — the dynamic behaviour and the determination of the response time. In most case, CAM is used when radionuclides with important radiotoxicities are involved (small value of ALI). Those radionuclides have usually long half-life values. Then the determination of the characteristic limits (decision threshold, detection limit, limits of the coverage interval) of a CAM is described by the use of long half-life models of evaluation. Finally, a possible way to determine the minimum detectable activity concentration and the alarms setup is pointed out. The annexes of this document show actual examples of CAM data which illustrate how to quantify the CAM performance by determining the response time, the characteristics limits, the minimum detectable activity concentration and the alarms setup.