Sterility is a major part of every cleanroom, be it the equipment, the tools, the product, or the structure. In aseptic cleanrooms, the garments must also be sterile. Most companies require all components in an aseptic cleanroom – including garments – to be terminally sterilized to 10-6SAL. There are three methods of achieving this: autoclaving, ethylene oxide (EtO), and ionizing radiation (gamma or electron beam.)
1. Steam Autoclaving
As the name suggests, sterility is attained in this method using steam and pressure. The garment is wrapped in a vapor-permeable bag and placed under a high temperature. The steam carries heat to every surface of the garment. So long as the object in the autoclave isn’t heat, pressure, or moisture-sensitive, this method is reasonably efficient and convenient. However, it typically shrinks garments up to two sizes. Aside from the obvious problem here, it degrades the material more quickly. Wrinkles also set in, making the garments unsightly.
2. EtO
This is a gas that kills microorganisms, and this sterilization method was used widely for years. It works by using a vacuum chamber to evacuate the air from wrapped objects and replace it with EtO. After sterilization, the gas is evacuated and air replaced. The greatest downside to this is EtO’s dangerous effects on humans. Items sterilized with this method had to be quarantined up to two weeks while the EtO dropped to a safe level. For this reason, extra garments need to be on hand to use while other garments are outgassing.
While both methods have their upsides, neither is considered the most advantageous given the culture and needs of today’s cleanroom. This brings us to the third, most preferred method of garment sterilization…
3. Ionizing Radiation
This includes two forms, though gamma irradiation is the only one being successfully used in cleanrooms. The electromagnetic radiation of gamma rays has great penetrating power, like an x-ray, but with a shorter wavelength. Sterilization with these rays occurs after the garments have been laundered and packaged. Before gamma irradiation, however, you must follow validation protocol to determine the dosage required to obtain the desired sterility. Since this kind of radiation is destructive, it’s important to use the lowest possible dose, which may be lower than the 25 kilograys we know are sufficient. This will help extend the garment’s life significantly.
Liability also plays a role in using the lowest possible dosage. Garment service providers undergo extremely rigorous customer audits because if the process drifts out of control or the dose has not been set properly, it can put a person’s life at risk. Therefore, the calculated sterilization dose for gamma irradiation will be included in the customer specifications for the product.
When it comes to cleanrooms, every aspect of sterilization and sanitation affects compliance and validation. Gerbig Cleanrooms knows how vital every detail is the overall process. If you need cleanroom construction, reach out to us. We know what you need to achieve and maintain success: 888-628-0056; info@gerbig.com.