Cambridge University Hospitals - NHS
Professional training, consultancy and specialist services for decontamination testing and validation

Understanding the Three Levels of Decontamination

Mon, 06/12/2021

Understanding the disinfection requirements and procedures is key for maintaining standards across the medical industry. Across the entire spectrum of appliances, devices and instruments, maintaining a rigorous decontamination schedule helps alleviate the transfer of potentially harmful micro-organisms to patients and staff. An understanding of the cycle of usage is a foundation for a broader understanding of decontamination.

Decontamination is defined as a single process or combination of processes that result in the equipment being safe to be used again on the same or another person.

There are three levels of decontamination, namely general cleaning, disinfection and sterilisation. 

Equipment used in healthcare may be designated as single use, single patient use or reusable multi-patient use. Any equipment not designated as a single use item must be made safe following use to prevent micro-organisms being transferred from equipment to patients and potentially resulting in infection.

The Department of Health defines the medical device life cycle as acquisition; cleaning; disinfection; inspection; packaging; sterilization; tracking; transportation and storage before use. 

In terms of reusable medical devices the approach is exactly the same with an extended life cycle that follows a use, transport, wash, disinfect, dry, inspect, pack, label, sterilise, storage, tracking, re-use process.

To ensure that the decontamination of reusable medical devices is undertaken correctly, it is vital for technicians to conduct appropriate risk assessments and follow schedules that allocate risk levels to specific pieces of equipment.

The table below is taken from the Microbiological Advisory Committee (MAC) issued & updated by the MHRA in 2020 & is based upon the Spaulding Classification published in 1957, it’s principles remain relevant today.

Low risk: These items either contact only intact skin or do not come into contact with the patient e.g. IV pumps, furniture, floors. Low risk items should be kept both clean and dry & subjected to localised decontamination schedules between patient use. 

Intermediate risk: These items: come into contact with intact mucous membranes; or may be contaminated with particularly virulent or readily transmissible organisms e.g. commode chair; or used on immunocompromised patients. Items require disinfection or sterilisation after cleaning. 

High risk: These items penetrate skin or mucous membrane; enter the vascular system or sterile spaces. These items go through the complete decontamination process of cleaning, disinfection and sterilization.

Cleaning and/or disinfection of medical equipment must: 

  • Take place after and between uses on individual service users. 
  • Once cleaned/disinfected, pieces of equipment should be labelled, including being dated and signed to identify that it has been cleaned. 
  • Audits should be carried out regularly on cleanliness of equipment in each area. 
  • Equipment requiring service or repair must be thoroughly cleaned and decontaminated prior to inspection, and a label attached identifying method of decontamination.

In line with the above, the process across all risk levels involves cleaning, with lower risk items often requiring no more than a detergent wipe or wash with hot water, and thorough drying.

As the risk levels increase, so too does the requirement for comprehensive cleaning ahead of a heat disinfection process using steam under pressure, ethylene oxide, gamma irradiation and other sterilisation processes. See the table below:

Microbiocidal activity of decontamination methods:


  Spores Mycobacteria Bacteria Viruses
Thermal Washer-Disinfector X ✔✔✔ ✔✔✔ ✔✔
Low Temperature Steam X ✔✔✔ ✔✔✔ ✔✔
Chemical Disinfectant Efficacy Dependent on Exact Chemical Efficacy Dependent on Exact Chemical Efficacy Dependent on Exact Chemical Efficacy Dependent on Exact Chemical
Steam ✔✔✔ ✔✔✔ ✔✔✔ ✔✔✔
Dry Heat
Gas Plasma / Activated Hydrogen Peroxide ✔✔✔ ✔✔✔ ✔✔✔ ✔✔✔


Key: X None, ✔ Poor, ✔✔ Moderate, ✔✔✔ Good

To find out more about service relating to the three levels of decontamination of reusable medical devices we offer at AVM Services, contact us today on 01223 254499 or email


Understanding the Three Levels of Decontamination