Journal of Hospital Znfection (1988) 12, 109-l 15 Safety devices to prevent airborne infection from clinical suction apparatus J. Ian Blenkharn Department of Bacteriology, Royal Postgraduate Medical School, Hammers- mith Hospital, Duane Road, London W12 OHS Accepted for publication 18 November 1987 Summary: Infection related to clinical suction apparatus has been widely recognized. Safety systems available at present include devices to prevent overflow from collecting vessels and in-line air filters. The relative efficiency of these devices for the containment of aerosols generated within the collecting vessel has been evaluated. Although of increased resistance, filter capsules of 0.3-urn pore size prevented the passage of test aerosols for longer periods than the widely used 8-urn fibre filter tubes. Filter life can be prolonged by preventing overflow from collecting vessels and protecting against the passage of foam and froth. Keyword: Suction apparatus; filters; safety system for suction Introduction Many episodes of infection have been related to the use of clinical suction apparatus (Ip et al., 1976; Rahman, 1980; Blenkharn & Hughes, 1982). These may arise from misuse of equipment (Cunningham & Sergent, 1983) or from design limitations (Blenkharn & Hughes, 1982). Improper use of equipment can be reduced by improving education and training of staff (Blenkharn, 1986). With regard to equipment design, the use of specific safety devices to prevent contamination and spread of bacteria to the environment is essential. Almost all apparatus currently available incorporates in-line air filters situated between the collecting vessel and suction source. However, filters are expensive and some have serious limitations in use due to the generation of aerosols within the collecting vessel. A newly designed system for monitoring filter efficiency has been described which enhances the safe use of in-line filters (Blenkharn, 1987). A comparative study of commercially available filters and of devices to protect them from overflow of fluid and froth generated within the collecting vessel has now been undertaken to evaluate the efficiency of these systems. 019%6701/88/060109+07 $03.00/O 109 0 1988 The Hospital Infection Socmty