A crossover study assessing the protective efficacy of improvised snorkel-based improvised respirators.

These data suggest that improvised PPE designs cannot provide reliable protection against aerosols. Failures are likely due to poor fit, but the suitability of 3D printed materials is also uncertain as fused-filament manufacturing yields parts that are not reliably gas-tight. Improvised PPE cannot be recommended as a substitute for purpose designed systems.