Indoor Air Quality in a Real Operating Theatre under Effective Use Conditions

The aim of this study is to investigate the impact of surgical staff on the indoor air quality in a un- idirectional ventilation Operating Theatre (OT). Experimental measurements of particles and mi- croclimate were acquired at rest and in operational conditions. The real OT (operational) use was simulated by a sham hip arthroplasty. CFD simulations were carried out outlining the studied en- vironment used for experimental measurement campaign. A standard k-ε closure scheme based on RANS equations was implemented to solve the velocity and pressure field using an eddy viscos- ity approach. Temperature and relative humidity distributions were also computed keeping into account sensible and latent heat sources inside the OT. An Euler-based approach was applied to solve the concentration fields of gaseous contaminant and small particles (up to 5 μm in diameter) in the indoor air. An innovative strategy is proposed to estimate, by an iterative comparison be- tween experimental data and numerical results, the emission rate of particles (differentiated by diameters) released by the occupants to be considered as source terms in the numerical model. Compliance with literature evidence concerning thermal and velocity fields and CO2 concentration was confirmed. From our analyses, some IAQ indexes were deduced, allowing monitoring of the local and overall OT air quality level supplied by the ventilating system during real operational conditions. The highest values of microbial air contamination were recorded during surgical ac- tivity; nevertheless, results showed the suitability of the ventilation system in providing the ex- pected air quality.