在美国和加拿大，空气系统清洁的启动是基于目视检查，这是主观的，对于主要清洁工作来说是不切实际的。法国污染预防与研究协会（ASPEC）发布了一份关于保持无孔空气系统清洁的客观采样方法（数值评估方法）指南。然而，抽样方法也存在一些不足。本研究的目的是在实验室中重现暖通空调系统无孔管道中的不同清洁度水平，将管道中表面灰尘取样的新方法与文献中引用的方法进行比较，并将数值评估方法（客观方法）与视觉方法（主观方法）进行比较。对于每个模拟的清洁条件，一个专家委员会根据3分制进行视觉评估，其中1级表示正常，2级表示高于正常，3级表示严重。 根据这些评估，确定的起始标准对应于NADCA方法的0.2克/平方米（0.00066盎司/平方英尺），ASPEC方法的0.3克/平方米（0.00098盎司/平方英尺），以及新方法的0.6克/平方米（0.002盎司/平方英尺）。这些标准之间存在显著差异（p=0.05）。在替代目视法时，只要采用了相应的起始标准，就可以使用任何表面取样方法，但在将这些结果用作清洁起始标准之前，需要在带有真实灰尘的真实管道中对其进行评估。引文:ASHRAE交易，2010年，第116卷，pt。新墨西哥州阿尔伯克基2号

In the United States and Canada, the initiation of air system cleaning is based on visual inspection, which is subjective and impractical for major cleaning work. The association for the prevention and study of contamination (ASPEC) in France has published a guide on objective sampling methods (numerical evaluation method) for keeping non-porous air systems clean. However, the sampling methods have some deficiencies. The objectives of this study were to reproduce in the laboratory different levels of cleanliness in non-porous ducts of HVAC systems, to compare a new method for sampling surface dust in ducts with those methods cited in the literature, and to compare the numerical evaluation method (objective method) to the visual method (subjective one). For each of the simulated cleanliness conditions, a committee of specialists did a visual assessment based on a scale of 3, where level 1 meant normal, 2 meant above normal, and 3 meant serious. According to these assessments, the established initiation criteria correspond to 0.2 grams per square meter (0.00066 ounces per square foot) for the NADCA method, 0.3 g/m2(0.00098 oz/ft2) for the ASPEC method, and 0.6 g/m2(0.002 oz/ft2) for the new method. These criteria are significantly different (p=0.05) from one another. When replacing the visual method, any of the surface sampling methods can be used, insofar as the corresponding initiation criterion is applied, but these results need to be evaluated in real ducts with real dust before being used as cleaning initiation criteria.