Decontamination is the process of removing or destroying harmful substances and microorganisms from surfaces or objects. Its purpose is to make items safe for handling, use, or disposal by reducing microbial contamination. This practice prevents disease spread and maintains public health.
An Overview of Decontamination Levels
Decontamination involves three primary levels: cleaning, disinfection, and sterilization. These levels progressively eliminate microorganisms, each designed for different situations based on infection risk. Cleaning is the initial step, followed by disinfection, and then sterilization, which offers the highest level of microbial removal.
Cleaning, Disinfection, and Sterilization Explained
Cleaning is the physical removal of visible soil, organic matter, and some microorganisms from surfaces or objects. This process typically involves water, detergents, and friction, and is a necessary first step before higher-level decontamination. Cleaning removes microorganisms but does not necessarily kill them. Removing dirt and debris ensures that disinfectants or sterilants can effectively reach and act upon remaining pathogens.
Disinfection eliminates most pathogenic microorganisms from inanimate objects, though it does not reliably kill bacterial spores. This process significantly reduces viable microorganisms to a safe level. Disinfection is categorized into low-level, intermediate-level, and high-level, depending on the range of microbes they target.
Low-Level Disinfection
Low-level disinfectants kill most vegetative bacteria, some fungi, and inactivate some viruses.
Intermediate-Level Disinfection
Intermediate-level disinfectants kill all microbial pathogens except bacterial endospores.
High-Level Disinfection
High-level disinfectants are effective against all microbial pathogens, with the exception of large numbers of bacterial endospores.
Common chemical agents used for disinfection include alcohols, chlorine products, hydrogen peroxide, phenolics, quaternary ammonium compounds, and peracetic acid.
Sterilization is the complete elimination or destruction of all forms of microbial life, including highly resistant bacterial spores. This is the most thorough level of decontamination, making an object completely free of living microorganisms. Sterilization methods achieve this through physical or chemical means.
Physical Sterilization Methods
Common physical methods include steam sterilization, often performed using an autoclave. Dry heat sterilization is used for items that can withstand high temperatures but not moisture.
Chemical Sterilization Methods
Chemical sterilization methods use agents like ethylene oxide gas, hydrogen peroxide gas plasma, or peracetic acid immersion. Ethylene oxide is used for heat-sensitive medical devices, and hydrogen peroxide gas plasma for devices that cannot tolerate high heat and humidity. Radiation sterilization, using gamma rays or electron beams, is employed for disposable medical supplies.
Where Decontamination Levels Are Applied
Cleaning is applied in everyday household chores, such as wiping kitchen counters or general surface cleaning in offices. In healthcare settings, cleaning is performed on non-critical items like floors and bed railings, reducing infection transmission. It is the initial step before any further decontamination.
Disinfection is used where pathogen reduction is necessary but complete sterility is not required. Hospitals use disinfectants for non-critical items like stethoscopes and blood pressure cuffs, and for environmental surfaces in patient rooms and operating theaters. Public restrooms, schools, and kitchens also employ disinfection to control microbial spread.
Sterilization is reserved for items that will come into contact with sterile tissues or the bloodstream, where the risk of infection is highest. Surgical instruments, implantable medical devices, and laboratory equipment are routinely sterilized. Examples include autoclaves for surgical tools and ethylene oxide gas for heat-sensitive devices like catheters.