[The relationship between fit characteristics of two kinds of self-inhalation air-purifying dust respirators and head-face dimensions of subjects].

Objective: To investigate the fitness characteristics of self-inhalation air-purifying dust respirators for representative subjects and to explore the influencing factors on fitness characteristics of respirators.

Methods: According to the Chinese new bivariate fit test panel, 50 representative subjects were studied for using 2 kinds of self-inhalation air-purifying dust respirators. The N95 Companion from TSI was used to test the Fit factor (FF), and five representative facial dimensions (face width, bigonial breadth, nasal root breadth, face length and nose protrusion) were measured. Then chi-square test was used to compare the qualified rates of 2 kinds of respirators. The t-test was utilized to analyze the differences of facial dimensions between qualified samples and unqualified samples. Multiple linear regression models were also established to analyze the effects of facial dimensions on FF.

Results: The qualified rate (86%) of folding respirators was significantly higher than that (68%) of cup respirators (P < 0.05). There were no significant differences of facial dimensions between qualified subjects and unqualified subjects for folding respirators. However, the face width, bigonial breadth and face length of qualified subjects were significantly larger than those of unqualified subjects for cup respirators (P < 0.01). The regression coefficient (0.31846) demonstrated that the positive effects of face length on mean log-transformed fit factor (MLFF) for all subjects with cup respirators (P < 0.05).

Conclusion: There were significant effects of respirator styles and head-face dimensions on the respirator fitness. There was a significant correlation between the respirator fitness and the facial dimensions for cup respirators.