Health care workers (HCWs) are at constant occupational risk for many infectious diseases transmitted from ill patients, despite existing safety protocols.² For instance, during the severe acute respiratory syndrome (SARS) outbreaks, many front-line HCWs had a greatly increased risk of contracting the SARS-coronavirus (SARS-CoV) that resulted in severe illness and death.³ Although clinical guidelines and protective measures for the management of patients with acute respiratory infections (ARIs) exist, the magnitude of the risk of acquiring ARIs through some patient care procedures is not clearly understood.^4,5

Procedures that are believed to generate aerosols and droplets as a source of respiratory pathogens include positive pressure ventilation (bi-level positive airway pressure [BiPAP] and continuous positive airway pressure [CPAP]), endotracheal intubation, airway suction, high-frequency oscillatory ventilation, tracheostomy, chest physiotherapy, nebulizer treatment, sputum induction, and bronchoscopy.^1,6,7 Although those procedures are known to stimulate coughing and to promote the generation of aerosols, the risk of transmission of ARIs is not well known. It is worth emphasizing that the scientific evidence for the creation of aerosols associated with these procedures, the burden of potential viable microbes within the created aerosols, and the mechanism of transmission to the host have not been well studied. It is unclear whether those procedures pose a higher risk of transmission and whether HCWs caring for patients undergoing the aerosol-generating procedures are at higher risk of contracting the diseases compared with HCWs caring for patients not undergoing the procedures.

Prolonged exposure and poor infection control compliance, such as poor handwashing, may be associated with risk of occupational acquired infection.^8,9 Inadequate spacing and ineffectiveness of personal protective equipment may also contribute to nosocomial transmission.⁵ There is some evidence that training programs and adequate personal protection equipment are associated with a decreased risk of transmission of SARS.¹⁰ For instance, with proper control measures in three key areas (including staff personal protection, categorization of patients to stratify risk of SARS transmission, and reorganization of the operating room), high-risk aerosol-generating procedures (surgical tracheostomy) performed on SARS patients appeared to be low risk to HCWs who were in direct contact with the patients in the operating room.¹¹

While there appears to be a lack of high-quality evidence regarding the risk of transmission of ARIs from aerosol-generating procedures, the current evidence-based guidelines^{1,6,7,12–17} recommend that additional precautionary measures be taken for specified aerosol-generating procedures performed on patients with suspected respiratory infection. These precautionary measures include performing aerosol-generating procedures in a single room with a minimal number of personnel present; using the most qualified personnel to perform the aerosol-generating procedures; and requiring the use of personal protective equipment, specifically an N95 mask or equivalent, full waterproof gown, face shield or goggles, and gloves. Many of these guidelines do, however, draw recommendations based on little understanding of the risk of transmission of the aerosol-generating procedures.

This report systematically reviewed the risk of transmission of ARIs to HCWs exposed to patients undergoing aerosol-generating procedures, as specified in the existing literature.^1,6,7 It does not address the generation of aerosols from specific procedures and does not address the presence of viable microbes responsible for ARIs within aerosols that may have been created by specific procedures and does not address the risk of transmission of airborne pathogens such as Mycobacterium tuberculosis.