Emergency Respiratory Protection with Common Materials

Abstract

The efficacy of readily available materials, such as cotton fabric, toweling, and a single-use respirator, for providing emergency respiratory protection was evaluated by determining the filtration efficiency as a function of particle size over the range of 0.4 to 5 µm diameter and performance against a reactive water soluble (I2) and unreactive vapor (CH3I). At a reasonable design face velocity (1.5 cm/s), the respirator mask used at double thickness could reduce particle concentrations a factor of 30 or more throughout the particle range tested, and a wetted towel four layers thick could provide a factor of five. Dry fabrics were ineffective in removing iodine vapor, but wetted sheeting or toweling reduced concentration by a factor often or more under design conditions, 1.5 cm/s face velocity and 50 Pa pressure drop (0.2 inches of water). The fabrics provided a statistically insignificant reduction in methyl iodide. In practice, any leaks around the seal to the face would lessen the protection offered by such materials. The effectiveness factor approach proved useful in comparing filter performance under different conditions.