Infrared imaging for leak detection of N95 filtering facepiece respirators: A pilot study

BACKGROUND: This study was undertaken to determine the utility of an infrared camera (IRC) for assessing leaks around filtering facepiece respirators (FFR) during quantitative respirator fit testing. METHODS: Eight subjects underwent quantitative fit testing on six N95 FFR models (48 total fit tests) while simultaneously being recorded with an IRC. RESULTS: The IRC detected 49 exhalation leaks during 39 tests and no leaks in nine tests. Exhalation leaks were identified in all failed fit tests (13) and a majority (26 of 35) of passed tests. Anatomically, the nasal region and malar (cheekbone) regions accounted for 71% of identified leak sites. Fit factors for fit tests without identified exhalation leaks were significantly higher than fit tests with leaks detected by IRC (P = 0.01). CONCLUSIONS: Thermal imaging using IRC can detect leaks in respiratory protective equipment and has the potential as a screening tool for assessment of the adequacy of post-donning FFR fit.