Secular trends in facial anthropometry among Chilean workers: Implications for ergonomic respirator design and fit panel adaptation

Abstract

The ergonomic fit of respiratory protective equipment (RPE) is critical for ensuring both protection and long-term usability in occupational settings. However, most respirators are designed based on outdated or foreign anthropometric data that may not represent local populations. In Chile, as in many countries without updated national databases, this mismatch can compromise comfort, effectiveness, and user compliance. This study evaluated temporal changes in facial dimensions among Chilean workers and assessed the applicability of four widely used respirator fit test panels. Two representative datasets collected a decade apart were analyzed: Dataset A (n = 474; 2013) with manual measurements, and Dataset B (n = 2016; 2024) using 3D facial scanning. Eleven facial dimensions recommended by ISO standards were examined against the LANL half- and full-facepiece panels and the NIOSH/ISO bivariate and PCA panels. Results showed significant increases in facial size, particularly among men, and a general shift toward larger facial morphologies. The NIOSH/ISO bivariate panel provided the highest coverage, while the LANL full-facepiece panel showed the poorest fit, especially among recent male participants. Gender-based differences in fit were consistent across both datasets. These findings underscore the need for updated, population-specific anthropometric references and the ergonomic redesign of respirators and fit panels. Although centered on Chile, the study has global relevance for countries that import RPE without validating fit locally. The methodology offers a scalable approach for aligning protective equipment with evolving worker characteristics, supporting international efforts to improve comfort, safety, and usability through data-informed design. These declining match rates suggest that respirator fit panels may become increasingly outdated, potentially compromising worker safety if they are not updated to reflect current population characteristics.