Characteristics of aerosol penetration through zippers

Particulate protective clothing (PPC) is designed to protect workers’ skin from making contact with hazardous substances. It has been shown that PPC provided less protection when the junctions became part of the ensemble. Among the junctions, zippers account for about 80% of all the junction accessories. Therefore, this study aimed to investigate the characteristics of aerosol penetration through zippers.

Zippers are commonly categorized into metal, nylon and plastic, based on the materials they are made of. In the present study, metal and plastic zippers were designated as one group for the same appearance and design principle. Nylon zippers were classified as another group according to the structure of zipper chains. The nylon zippers were further divided into two types by whether the chain can be fully covered by the tape (type A) or not (type B). Effective diameter was used to characterize the leak size between teeth of metal and plastic zippers, when the zippers were chained. Active sampling, closed-returned sampling, and fluorescent aerosol methods, developed in previous studies, were employed to measure the aerosol penetration through zippers.

The results showed that aerosol penetration through zippers increased with increasing effective diameter for both metal and plastic zippers, but not the size of the zipper teeth. Aerosol penetration through type-A nylon zipper was lower than that in type B because of better tape design. Moreover, aerosol penetration through the back of type-A nylon zipper was lower than that through the front, indicating that the current design of nylon zipper was solely aesthetic thinking. The zippers should be turned around to provide better protection against airborne particles. Extra attention should be paid to the quality control of the zipper manufacturing, since zippers might become the major route of entry of hazardous substances.