The ventilation system of an operating theatre (OT) in a hospital needs to provide a comfortable and healthy surgical environment, particularly to minimise the risk of airborne infection. Engineering standards are available to outline specialised ventilation design and installation requirements based on knowledge accumulated from quality research and day-to-day practices. In this paper, the integrated effect of a reduction in supply air velocity and changed medical lamp positions on the ultra-clean ventilation performance of a standard OT environment is reported. The dispersion of infectious particles from both the surgical team and the patient were examined through computational fluid dynamic analysis. It was observed that variations in supply velocity and medical lamp configuration will only slightly affect the thermal comfort environment. However, they could have a serious effect on the movement of infectious particles and hence increase the cross infection risk.
A good ventilation system in an OT is able to provide a comfortable and clean surgical environment and to guard against cross infection between the medical staff and the patient. Engineering standards are available as guidance to enhance quality design and installation practices. One of these is the HTM2025  developed by the UK National Health Service Estates. The guidelines are the outcome of numerous research and development activities, as well as practical operating experiences. For several decades, there have been tremendous efforts to investigate the performance of OT ventilation systems via experimental and field studies [2–7]. In recent years, the work has been complemented by numerical analysis. In particular, computational fluid dynamics (CFD) have been used extensively as a numerical tool for fluid flow and heat transfer analysis. It can be used to assess air movement, temperature and contaminant dispersion. CFD applications used to study airflow, heat transfer and contaminant distribution patterns in an OT can help to arrive at an economical and optimum ventilation scheme [8–12].