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Hierarchy of Controls


The hierarchy of controls helps implement effective infection prevention and control (IPC) measures to reduce the spread of respiratory and other pathogens in healthcare settings. In addition, it helps organisations and employers with the responsibility to assess, manage and monitor risk in managing infectious diseases and multi-drug-resistant organisms (MDROs) based on the measures prioritised in the hierarchy of controls. 

Fig. 1 outlines the hierarchy of the control methods. Implementing this system is very effective in substantially reducing cross-infection and other hazards in healthcare facilities. The measures on the top of the chart are potentially more effective than those on the bottom.

Fig 1 Hierarchy of the infection prevention and control measures.

The risk assessments must be carried out in all areas by a competent person with the skills, knowledge, and experience to recognise the hazards of infectious diseases and pathogens. In addition, risk assessments must be revisited when any element of the original risk assessment changes, for example, clinical speciality, patient vulnerability, staff, building, and environment.

It is essential to point out that engineering controls are favoured over administrative and personal protective equipment (PPE) for controlling cross-infection as they are designed to remove or minimise the hazard at the source before it comes in contact with health workers and other individuals.


The most effective steps within the hierarchy of controls are those that ideally remove hazards. Therefore, organisations and employers must redesign the activity to eliminate or mitigate risk to a minimum. Key mitigation measures include:

  • Screening, triage and/or screening of respiratory (SARS-CoV-2, flu, RSV, etc.) and other pathogens ( difficili, norovirus, etc.) and multi-drug resistant organisms (MDROs). It must be undertaken to enable early recognition and assess patients before they attend a healthcare facility.
  • Where treatment is not urgent, consider delaying this until the resolution of symptoms providing this does not negatively impact patient outcomes.
  • Staff should not attend work if they are symptomatic or have a contagious disease. If necessary, seek the advice of the Occupational Health Department.


When a source of infection cannot be eliminated, substitutions should be implemented to reduce or control the risk. Unfortunately, in some circumstances, this may not be possible for a healthcare facility. However, for some services, it is possible to consider virtual (telephone or video) consultations.

Engineering controls

Engineering controls are used to reduce or control the risk of exposure at the source from infected/colonised patients. Priority should be given to measures that provide collective/maximal protection rather than those that protect individuals or a small group of people, for example, to control respiratory pathogens:

  • Ensuring ventilation systems, mechanical or natural, meet national recommendations for minimum air changes. This should be done with organisational estates teams/specialist advice from the ventilation group and/or authorised engineer.
  • To dilute air with natural ventilation by opening windows and doors where possible.
  • Consider putting screens/partitions in reception/waiting areas. Consult with Estates Facilities teams.
  • Assess whether room provision is sufficient if there were to be increased patients requiring isolation for respiratory and other infectious diseases. Work in a multidisciplinary team with hospital leadership, engineering, IPC and clinical staff to plan for the creation of adequate isolation rooms/units.
  • Assess the care areas and ensure that patients with respiratory infections should not care for in poorly ventilated and/or overcrowded areas. Where a clinical space has very low air changes, and it is not practical to increase dilution effectively, consider alternative technologies with Estates and the ventilation group. Don’t perform the Aerosol Generating procedures in an open bay.

Administrative controls

Administrative controls (e.g. the design and use of appropriate processes, systems and engineering controls, and provision and use of suitable work equipment and materials) are implemented to help prevent and limit the transmission of infection in healthcare facilities, which include:

  • Screening, triaging and testing to enable early recognition of infectious diseases and MDROs.
  • Maintaining separation in space and/or time between patients.
  • Appointment or clinic scheduling to reduce waiting times in reception areas and avoid mixing of infectious and non-infectious patients.
  • Appropriate patient placement for infectious patients in ensuite single room or cohort areas.
  • Regular assessments of physical distancing and bed spacing, taking into account potential increases in staff-to-patient ratios and equipment needs.
  • It is important that a patient’s treatment cannot be deferred with suspected or confirmed infectious diseases and MDROs. Instead, their care should be provided, and services can operate to minimise the risk of cross-infection with other patients and individuals.
  • Provision of appropriate education for staff, patients, and visitors in infection prevention and control.
  • Provision of additional hand hygiene facilities, including the availability of Alcohol-Based Hand Rub at appropriate locations. Use signage to ensure good hygiene practices among staff, patients, and visitors.
  • Provide safe spaces for staff breaks areas and changing facilities.
  • Ensuring regular cleaning regimes are followed and compliance monitored, including that of reusable patient care equipment.
  • Ensuring staff and patient adherence to IPC guidance, including wearing appropriate PPE (face masks/coverings) and physical distancing measures.

Personal protective equipment

Personal protective equipment (PPE) is considered the least effective measure and, therefore, should be considered in addition to all previous mitigation measures in the hierarchy of controls.

It is acknowledged that not all elements of the hierarchy of controls will be possible in some settings, for example, in a patient’s home. In these situations, healthcare workers must have:

  • Availability of Alcohol-Based Hand Rub for hand hygiene
  • Adequate supply and availability of PPE, including Respiratory Protective Equipment (RPE)
  • If necessary, staff must wear an FFP3 respirator that has been fit tested as this is a legal requirement.
  • All staff (clinical and non-clinical) are trained in putting on removing and disposing of PPE safely.
  • Visual reminders are displayed, communicating the importance of wearing appropriate PPE (e.g., face masks, gloves, etc.), complying with hand hygiene, and maintaining physical distancing if appropriate.

PPE must be worn when exposure to blood and/or other body fluids, non-intact skin, or mucous membranes is anticipated in line with standards and transmission-based IPC precautions.