Choosing the right sterilizing/decontaminating agent for your cleanroom can be both an easy task and a daunting choice. This article examines the various methods for the sterilization/decontamination, disinfection, or sanitization of cleanrooms, including:

• Manual spray and wipe techniques
• Misting systems or fogging
• Vapor systems
• Gaseous systems

The goal of this article is to give readers an understanding of the benefits and drawbacks of the various sterilizing/disinfecting methods with a thorough discussion of the efficacy, ease of use, and relative cost of each method. Practical aspects of the different methods, such as room size, content, configuration limitations, and scale-up potential, are compared. A thorough understanding of the various methods will allow the user to choose the appropriate method to achieve the desired level of decontamination for each particular application.

The optimal agent should be classified and registered as an antimicrobial pesticide with the United States Environment Protection Agency (EPA). Antimicrobial pesticides are substances or mixtures of substances used to destroy or suppress the growth of harmful microorganisms, such as bacteria, viruses, or fungi,on a variety of objects and surfaces.

Antimicrobial pesticides have two major uses:

1. To disinfect, sanitize, reduce, or mitigate growth or development of microbiological organisms.
2. To protect objects (floors and walls, for example), industrial processes or systems, surfaces, water, or other chemical substances from contamination, fouling, or deterioration caused by bacteria, viruses, fungi, protozoa, algae, or slime.¹

Why is EPA registrationimportant?

EPA registration is important because the EPA regulates the sale and use of antimicrobial pesticides under the statutory authority of the Federal Insecticide,Fungicide, and Rodenticide Act (FIFRA):

• Regulation 40CFR Subchapter E - Pesticide Programs (Parts 150-189)
• 40CFR Part 152 & Part 156 Antimicrobial Registration Requirements

The Federal Government carefully regulates pesticides to ensure that they do not pose unreasonable risks to either human health or the environment, and as part of that effort, requires extensive test data from antimicrobial pesticide producers that demonstrate as such. EPA scientists and analysts carefully review these data to determine whether to register (license) a pesticide product or a use and whether specific restrictions are necessary.²

When performing any disinfection, decontamination, or sterilization, the user must remember what is being accomplished; the maximum kill of the target organisms with a minimal amount of hazard to the user. All appropriate safety precautions should always be taken as all of these methods pose some risk to humans. In terms of safety, liquid-based systems are probably the safest since most of the agent is contained in solution; however, there is some off-gassing that occurs with different liquid agents. The vapor and gassing systems are all equally harmful to people. As such, the rooms must never be entered during the decontamination process because the concentration of sterilant in the room is high enough to be harmful to humans.

AVAILABLE METHODS
Current room decontamination methods include gaseous systems (formaldehyde and chlorine dioxide), vapor systems (both “wet” and “dry”), misting and fogging systems, and manual spray and wipe techniques that use a variety of liquid disinfecting or sterilizing agents. Manual spray andwiping, and formaldehyde gassing are by far the primary methods.