Static electricity in the workplace can not only be a nuisance—one which causes annoying garment cling—but also be a potential hazard. Static electricity, which refers to the build up of an electric charge on the surface of objects, can spark in a flammable atmosphere under certain conditions.
The primary risk of spark potential comes from static charges that are stored on the body of an ungrounded worker, rather than from garments. However, static electricity also generates on all clothing. Fortunately, FR garments are no more likely to generate static than other garments under the same conditions.
Static electricity builds up on garments due to a number of factors including the type of fabric, the relative humidity, the fabric’s ability to absorb moisture, the task being performed and the use or lack of use of grounding devices.
Flame-resistant (FR) fabrics are designed to prevent the spread of flames, to resist ignition, and to self-extinguish once removed from the source of ignition, to help protect employees. Compared to FR fabrics, non-FR garments are more likely to ignite and continue to burn until the fire is extinguished or the flammable material is burned up.
Both FR and non-FR garment fibers fall into two general categories: natural fibers and synthetic fibers.
Fabrics with synthetic fibers, such as polyester, nylon or aramid absorb less moisture than natural fiber fabrics. Thus, synthetics retain more static electricity than fabrics that are made from natural fibers.
To deter the accumulation of static electricity, many FR synthetic blends include static dissipative fibers, which have been added to the garments in order to address the nuisance static. In addition the dissipative fibers help to reduce the contribution of clothing to the static buildup on the human body.
On the opposing side, the category of fabrics with natural fibers, such as cotton and Lyocell, absorb more water from the atmosphere than synthetics. For example, FR treated 100% cotton, 88/12 cotton/Nylon blend and Modacrylic blends with Lyocell contain fibers which absorb moisture. Once retained, the water conducts static electricity and can help aid the distribution of static charge. Ergo, natural fibers can experience less static buildup in high humidity conditions than synthetics. However, if those fabrics are being utilized in low humidity conditions, then the fabric will be ineffective at dissipating static charges.
Variables that Affect Static Electricity in Clothing
Other variables that can alter the accumulation of static electricity on garments include the use of grounding devices as well as the specific tasks that are being performed by the wearer. Fabric manufacturers do not recommend using fabric softeners, dryer sheets or anti-static products that have not been tested for flammability, because those products could leave behind a flammable residue. Furthermore, removing or putting on garments in a hazardous area can increase the risk of ignition, because the movement increases the charge on the human body, which could then become a source of spark energy.
Beyond wearing FR Garments, it is recommended that a user in a high-risk environment also wear a grounding device such as a static dissipative wristlet or anklet to help eliminate static electricity and spark potential.