Evaluation of Operating Theatre Ventilation Systems and Infection Control Engineering in Teaching Hospitals in Ogun State

Surgical site infections are a major source of patient harm and healthcare costs in Nigerian teaching hospitals, and the engineering performance of operating theatre ventilation systems plays a critical preventive role that has been inadequately evaluated in Ogun State facilities. This study evaluates the ventilation system performance and infection control engineering parameters of operating theatres at two teaching hospitals in Ogun State. Measurements were conducted in six operating rooms across both facilities, covering air change rate, airborne particle count, differential pressure between theatre and adjacent corridors, temperature, relative humidity, and air filter integrity. Measurements used calibrated instruments including a hot-wire anemometer, a particle counter, a digital manometer, and a thermohygrometer. Theatre air change rates ranged from eight to fourteen per hour, falling below the WHO-recommended minimum of twenty air changes per hour for conventional operating theatres in four of the six theatres measured. Positive pressure differentials relative to adjacent corridors were absent in three theatres, creating potential for contaminated air ingress. Airborne particle counts exceeded ISO 14644-1 Class 7 limits during active surgical periods in two theatres, suggesting inadequate filtration efficiency. HEPA filter inspection revealed expired filter elements at one facility. Temperature and humidity fell within acceptable ranges at both facilities. The study concludes that ventilation engineering deficiencies represent a preventable contributor to surgical site infection risk and recommends urgent HVAC system upgrades, regular filter replacement schedules, and continuous environmental monitoring programmes at Ogun State teaching hospitals. Keywords: operating theatre, ventilation system, surgical site infection, air change rate, Ogun State.