## 3 Results
Figure 8 shows the results of the underfoot vision assessment. The best possible visibility in a protective mask is important not only for the visibility of activities in an environment that is often cluttered, but also for the safety and protection needs of the wearer. The \"completely satisfactory\" rating for the STS Shigematsu CF01 protective mask received 37 responses and the \"rather satisfactory\" rating received 15 responses, meaning that the underfoot vision of this mask was satisfactory for up to 52 respondents. The second rating was achieved by the Guzu CM-6 mask. The underfoot vision of the protective mask does not suit 20 respondents, which means that this mask has the worst rating for this criterion. Figure 9 shows the results of the evaluation of the criterion focusing on the handling of the clamping system. The Guzu CM-6 achieves the best rating for handling the clamping system. A total 30 respondents rated the handling of the clamping system as very good and easy. Conversely, only one respondent indicated that the handling was very poor and difficult. The second place was occupied by the STS Shigematsu CF01 protective mask, where 42 respondents rated the handling of the clamping system positively and 7 respondents negatively, but this represents the most negative ratings. The OM-90 protective mask has a relatively positive rating. The result of the STS Shigematsu CF01 protective mask can be compared with the result of the evaluation of the first criterion. It was the clamping system that achieved the worst rating that may have caused the slowest donning time. Figure 10 shows the results of the evaluation of breathing in the protective mask. The test subject shall consciously and deeply inhale and exhale slowly for at least 30 s during the breathing assessment. The STS Shigematsu CF01 mask was again the first choice for this criterion. Not a single respondent gave the answer \"very poor\" for this type of mask, whereas 49 respondents gave a positive assessment of breathing in the protective mask. As many as 22 respondents found it difficult to breathe in the OM-90 protective mask and 9 respondents found it difficult to breathe in the Guzu CM-6 mask. The answer \"neither bad nor good\" was marked by 7 respondents for the STS Shigematsu CF01 protective mask, 15 respondents for the OM-90 mask, and 14 respondents for the Guzu CM-6 mask. Breathing in the OM-90 protective mask is rated as the worst. Figure 11 shows the results of the clarity ratings in the protective mask. The worst-rated speech intelligibility is for the OM-90 protective mask, where 18 respondents rated it negatively and 20 respondents rated it positively. The STS Shigematsu CF01 protective mask is the best-rated protective mask. A total 49 respondents indicated that speech intelligibility in this mask is rather good or very good. For the Guzu CM-6 protective mask, 10 respondents indicated that speech intelligibility is very good and 25 respondents indicated \"rather good\". However, quite a number of respondents indicatedthat speech intelligibility was poor. Figure 12 shows the results of the evaluation of the criterion focusing on filter replacement. The worst results were achieved by the STS Shigematsu CF01 protective mask. A total 20 respondents found filter replacement or filter fitting difficult. Although the protective filters for the STS Shigematsu mask are smaller, lighter, and non-restrictive, the method of fitting them caused problems for users. The OM-90 protective mask achieved the best results with little difference to the Guzu CM-6 mask. Figure 13 shows the results of the evaluation of the protective masks according to comfort under load. Figure 14 shows the results of an evaluation focusing on the overall comprehensive evaluation of the individual protective masks. The tenth criterion evaluated was comfort with the load, in which respondents had to perform 15 squats. The most satisfactory comfort under load is in the STS Shigematsu CF01 protective mask.