Performance of N95 elastomeric respirators in high humidity and high coal dust concentration environment

Abstract

High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal miners. This paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of miners. Based on the self-designed in-situ PM2.5 collector, controllable PM2.5 generator, human breathing simulator, and respirator simulation testing system, under the simulated deep mine working condition, this study investigated the effects of dust loading, wearing time, and dust concentration on the filtration efficiency, breathing resistance, and quality factor of N95 elastomeric respirators. With the increase of dust loading, the respirator filtration efficiency firstly decreased, then increased (minimum value 97.5%). The breathing resistance increased exponentially from 120 to 180 to 1020–1530 Pa, and the quality factor decreased logarithmically from 0.051 to 0.076 to 0.0058–0.0085 Pa−1. As the PM2.5 coal dust concentration increased from 5 to 50 mg/m3, the wearing time for the respirator breathing resistance to exceed 300 Pa reduced from 7 h to less than 1 h. One N95 elastomeric respirator is not able to perform an 8-h work shift. To avoid the excessive breathing resistance caused by dust loading, more filter cartridges are needed for coal miners.