## 2 Materials and Methods
This would correlate to 500 clicks annually and is an estimated use case for a 10-year lifecycle if two measurements per week are made. This durability testing consisted of an expected failure analysis at the system designs weakest point. In this failure testing, the clip system was subjected to elastic deformation similar to what would be expected in the application of attaching the system to the harness, but to a greater extent as in this case it was repeated immediately allowing for heat to be generated by the friction of repetitions. The heat generated in the testing was not near notable values. In addition of mechanical friction testing, the clip system was tested by putting it on and off a harness for 500 times. Before the field testing, both the hose holder clip and cyclone sampler clip were subjected to lead user testing. This test covered ease of use and aesthetics of these clips compared to the traditional systems. During the field testing, test subjects were interviewed to provide feedback concerning the functionality and ergonomics of the clips. Two occupational specialists placed the harness on and used the previous systems of attaching the hose and cyclone sampler. These previous solutions were a custom made metal hose holder and original cyclone sampler holder with a serrated edge clamp. After testing the previous solutions, they tested prototype harness and placed the cyclone sampler with the redesigned clip into it and used the hose holder clip to attach the hose. The clips were also tested if they could be used with commercial harnesses as well as the prototype harness. Field testing of the hose holder was carried out in three different measurements and workplaces in May, June, and October 2018. Duration of the first measurement was 20 min, and similarly, it was 6 h for the second, and 5 h for the third measurement. During the first measurement, the clip as well as prototype harness was attached to an operator in an industrial workplace. Volatile chemical compounds were measured. The work was partly physical but also included driving a forklift. The hose holder kept the sampling hose attached to a harness and an air pump, although plastic camps of the prototype harness released during the measurements. A second measurement was also done in an industrial workplace where maintenance worker's exposure to inhalable dust was measured. The worker had hose holder clip(s) with original harnesses. In the third measurement, the cyclone sampler attached to the original harness was used in a machine workshop during welding. A respirable dust was measured from the breathing zone for manganese analysis to evaluate worker's exposure. A hose holder clip was also used. After every measurement, the clip holders were detached from the harness and cleaned according to a cleaning test. To simulate the situation where environmental experts would decide on their own clip needs, generate correct files, and send the files to be printed in (e.g., using 3D printing services like 3D Hubs, 3 DSD, etc.) or print their own systems using low-cost 3D printers, a test was designed. The test occupational specialist/possible end user with no CAD experience was given a link to the files, the FreeCAD software, and instructions for printing. They downloaded the hose holder clip files (FCStd) and opened them in the downloaded FreeCAD. Then, they decided which harness width they wished to use and changed it in the parametric model to generate correct 3D data. Then, they sent the STL data to be printed. There were three cases, in the first case, Aalto University acted as a service provider and printed both clip systems with an industrial level printer (uPrint SE Plus) and printed the hose holder clip with a low-cost printer (Lulzbot Mini). In the second case, a test person's organization, Finnish Institute of Occupational Health (FIOH), had their own in-house printer (Uprint SE Plus) and they tested the printing of their own clips as well. FIOH acted as a pilot organization for this study.