Scotland Adopts Respiratory Infection Control Guidance Informed by Aerosol Research

Many precautions have hinged on the assumption that certain clinical interventions create high-risk aerosols, driving extensive personal protective equipment use and workflow disruption. Health systems need guidance that reflects how aerosols actually arise in care environments. In response, Scotland has adopted a risk-based infection control approach informed by new evidence from the AERATOR study and associated aerosol measurements.

The AERATOR (AERosolisation And Transmission Of SARS-CoV-2 in Healthcare Settings) study took place during the COVID-19 pandemic. It was led by anesthetic, intensive care, infectious disease, and respiratory clinicians at Southmead Hospital and aerosol scientists at the University of Bristol, with support from the National Institute for Health and Care Research Biomedical Research Centre: Bristol. The study also involved Bristol NHS Foundation Trust and examined whether procedures long labeled aerosol-generating truly produce substantial aerosols.

Investigators used PLUME (Portable Low-background Unit for Measuring Exhaled Aerosol) to quantify aerosol production in real time. Measurements were performed in ultraclean operating rooms typically used for orthopedic and neurosurgical procedures, allowing direct characterization of aerosols in clinical environments. The findings identified respiratory aerosols produced during breathing, speech, and coughing as the main route for transmission of infections such as COVID-19.

The study found that most procedures previously considered high risk generated fewer aerosols than coughing or talking. These results challenge procedure-based risk categorization and shift attention toward patient behaviors that drive higher aerosol emission. The findings underpin guidance that emphasizes infection type, patient symptoms, and exposure context.

Scotland is the first country to use this evidence to reshape guidance on limiting respiratory disease spread in health care settings. Public Services Delivery Scotland has issued updated transmission-based precautions that introduce a consistent, risk-based approach across National Health Service Boards, care homes, and wider settings.

The guidance moves away from procedure-focused assessments, ends use of the term “aerosol-generating procedure” in risk evaluations, and will change how personal protective equipment is deployed. Wales has adopted the same approach, while England has not yet fully retired its aerosol-generating procedures list.

"The AERATOR study challenged long-held assumptions about which medical procedures generate aerosols and therefore potentially increase the risk of infection transmission. By using innovative technology to measure aerosols directly in health care settings, we were able to show that many procedures previously considered high risk actually produce fewer aerosols than normal breathing, coughing or talking," said Dr. Andy Shrimpton, academic clinical lecturer in anesthetics at the University of Bristol, who conducted many of the studies during his Ph.D.

“It is extremely unusual to see this evidence so rapidly shape national guidance. Scotland's adoption of a risk-based approach reflects a growing understanding that infection prevention measures should be proportionate to the actual risk. This will help ensure that patients continue to receive safe, effective care while supporting health care staff to make evidence-based decisions about the precautions they use,” said Tony Pickering, professor of neuroscience and anesthesia at the University of Bristol and consultant anesthetist at Bristol NHS Foundation Trust.

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