Protecting both the product and the worker against potential hazards in cleanroom environments.
Most of the time, the “protection” part of hand protection is straightforward. Gloves are designed specifically to protect the wearer’s hands from some type of injury—cuts, spills, burns, or even repetitive use injuries that only manifest over time. The challenge is to find the glove that offers the right level of protection workers need for the job and the comfort or performance-enhancing benefits they want.
In cleanroom environments, however, choosing the right glove isn’t so simple. These are delicate ecosystems dedicated to research and manufacturing that are sensitive to even minute impurities, and the majority of those impurities originate from people. Gloves and other personal protective equipment must limit the introduction of any contaminants into aseptic or cleanroom environments, which means these special-use gloves are designed to protect the products as much as the wearer. Consider the potential cost of a contaminated pharmaceutical product—millions of dollars could be conservative.
With that in mind, let’s take a closer look at hand protection for cleanrooms from both perspectives—providing protection for the wearer and for the product—and how glove technologies and design practices are addressing both needs.
Protecting the Product
Of course, there are several types of cleanrooms. A cleanroom designed for assembly of microchips for electronics is different than one designed for pharmaceutical or aseptic manufacturing, and the level of cleanliness required in the rooms is dependent on the activities taking place inside.
In the U.S., cleanrooms are designated Class 1, 10, 100, 1,000, 10,000, or 100,000, corresponding to a certain acceptable number of particulates per cubic foot. The lower the number, the cleaner the room. In Europe, this designation follows ISO numbering guidelines (ISO 1-9), again with the lower number representing the cleaner room. As you might expect, gloves and other PPE designed for Class 1, 10, or 100 rooms—sometimes referred to as ultra-cleanrooms—are more carefully manufactured, packed, and shipped than those carrying less-sensitive classifications.
It’s interesting to note that while there are industry standards that establish the maximum number of particulates allowed per cubic foot in cleanrooms with different designations, there are no standards or regulations around cleanroom PPE or glove performance. When choosing gloves for use in a cleanroom, buyers should therefore carefully check that the particle count of the gloves does not exceed the standards of the cleanroom where they will be used. For example, gloves for use in a Class 10 cleanroom should carry particle counts no higher than 850—that’s the number of particles 0.5 microns or smaller. An acceptable number for Class 100 is 3,000. Again, those numbers are recommended, not regulated.
Another concern is ionic content—the measure of the amount of residual ions, either positive or negative—on the gloves. Non-volatile residue (NVR) is a potential contaminant with various implications to products or activities. Silicone, for example, can’t be present in aerospace manufacturing in a cleanroom environment because it can impact the effectiveness of some adhesives. Sodium ions can cause conduction and low field breakdown in semiconductor manufacturing, while chlorides can trigger corrosion in disk drive manufacturing.
Ionic residuals and the insulative properties of the base glove material also dictate how well a material behaves in terms of electrostatic discharge (ESD)—another important consideration in the cleanroom, especially in the electronics sector. Since natural rubber latex is an excellent insulator, it isn’t viable for ESD-sensitive applications. A nitrile glove is by far the better choice.
For aseptic environments, maintaining the sterile conditions of the workspace and the product is paramount and selecting a protective glove that is sterile is essential. Look for a product that is sterile and validated to a Sterility Assurance Level of 10-6.
Protecting the Person
While preserving the sanctity of the cleanroom is an important component of glove selection, it can’t take precedence over the safety and protection of the worker. Cleanroom hazards fall into three categories: physical, biological, and chemical, each of which requires unique characteristics from a glove.
Most physical hazards are what you might expect—sharp or abrasive objects and surfaces that can cut, scratch, or penetrate the skin. These types of hazards can present a challenge in terms of glove design. Innovations in materials are improving durability in cleanroom gloves, but today true cut protection still requires wearing a cut-resistant glove under the cleanroom glove.
Biological hazards are common in aseptic manufacturing and research and include risks associated with handling potentially pathogenic materials. Gloves for these tasks typically are thin, single-use, disposable gloves designed to provide a reliable barrier between the biological agent and the skin. Barrier efficacy or integrity for this type of product is evaluated by testing the gloves for pinholes. As with any mass-produced product, these gloves typically are held to a manufacturer-determined acceptable quality level (AQL). This is another metric informed decision-makers need to know before choosing a glove—understanding that the lower the AQL, the better quality the barrier.
Chemical hazards are different, because various chemicals and chemical compounds can react in different ways to materials used in gloves—and to the skin beneath those gloves. Workers in cleanrooms typically handle small quantities of hazardous chemicals, and most cleanroom gloves are designed appropriately, as single-use gloves focusing primarily on splash-resistance. This means the gloves are designed to provide initial protection when a chemical splashes onto the hands, giving the worker adequate time to remove and dispose of the glove immediately and don a replacement.
Ensuring Protection without Compromise
There was a time when serving these two distinct needs—protecting the product and the person—wasn’t possible to the standards we find acceptable today. Fortunately, that no longer is the case. Advanced materials and new design and cleaning processes ensure the availability of a glove that can provide adequate protection for the job without compromising the purity of the cleanroom.
While cleanroom gloves start out as any other typical, single-use glove, they go through additional manufacturing steps to ensure they meet the rigorous requirements of cleanroom personal protective equipment. Those steps include multiple washing and leaching, or rinsing, cycles to remove production chemicals and thoroughly clean the finished gloves. The final laundering happens in a cleanroom itself, and those gloves then are bagged (or double-bagged) in vacuum-sealed plastic bags in yet another cleanroom. Truly sterile gloves go through a sterilization process involving gamma irradiation after cleaning and packaging. It’s an expensive, time-consuming process and some manufacturers may cut corners. Responsible decision-makers should ask questions about the cleaning and packaging processes used by their cleanroom glove manufacturer.
Cleanroom gloves must protect not just the person wearing the gloves, but the cleanroom environment itself and the products within that environment. Potential hazards to the worker include physical, biological, and chemical hazards, while the threats to the product include loose particulates, biological contamination, ionic residue, and electrostatic discharge. Today’s technologies make it possible to mitigate all of these risks.
This article can also be found in the March 2016 edition.
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