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Computational fluid dynamics application in indoor air quality and health

Time: Mon 2022-05-30 13.00

Location: Kollegiesalen, Brinellvägen 8, Stockholm

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Language: English

Subject area: Civil and Architectural Engineering, Fluid and Climate Theory

Doctoral student: Parastoo Sadeghian , Hållbara byggnader, Fluid and climate Technology

Opponent: Professor Catherine Noakes, University of Leeds, UK

Supervisor: Docent Sasan Sadrizadeh, Byggteknik och design; Docent Sture Holmberg, ; Docent Ann Tammelin, Karolinska institutet; Professor Olof Sköldenberg, Karolinska institutet

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QC 20220502


Indoor air quality directly affects the comfort, performance, and well-being of occupants. Indoor pollution can cause immediate or long-term health effects and has been responsible for 4.1% of global deaths in recent decades. In operating rooms, providing a high indoor air quality is especially critical as surgical site infection can occur in patients due to air contamination in operating rooms.

Surgical site infections due to antibiotic resistant bacteria may threaten the safety and lives of millions of people each year. To moderate and reduce indoor contamination, it is necessary to select a proper ventilation strategy.Improving ventilation system performance requires a deep understanding of airflow patterns and contamination distribution.

This thesis adopted computational fluid dynamics to evaluate airflow patterns and the spread of airborne contaminations in indoor environments. Moreover, we sought to provide an approach to facilitate transferring the obtained knowledge to medical experts and decisionmakers to reduce the infection risk after the surgery.

The use of warming blankets has raised the concern about surgical site infections. Warming blankets are used to prevent hypothermia in patients during surgery. However, our results showed that these warming blankets reduce the bacteria-carrying particles level at the wound due to warm upward airflows.

Surgical lamps can block the airflow and generate a low-velocity area under the lamp that increases the accumulation of contaminants. The simulation results revealed that a novel fan-mounted surgical lamp reduced the contamination level to an acceptable range for infection-prone surgeries. This novel surgical lamp successfully reduced contamination in the operating room supplied with both turbulent mixing and laminar airflow ventilations.

In another study, we implemented a protective curtain and showed that this strategy could significantly reduce the exposure level of the medical team to a patient with infectious respiratory disease. This novel protective curtain is located between the patient’s upper body and the lower part during surgery. We found a 57% reduction in bacteria-carrying particle concentration at the wound by adopting this curtain. Thus, using this protective curtain can reduce the exposure level of both patient and surgical team in the operating room.

Besides investigating the performance of ventilation systems in hospitals, we investigated the application of diffuse ceilings ventilations in clinics, especially waiting rooms. Diffuse ceiling ventilation systems are common air distribution systems in offices and schools. Based on simulation results, a diffuse ceiling with a central opening and evenly distributed heat loads resulted in the highest cooling capacity and thermal comfort in clinic waiting rooms.

We have visualised the airflow field and airborne particles in operating rooms with the help of virtual reality techniques. We found the virtual reality environment more engaging to understand the airflow field and particle movements in operating rooms.