I study how the surgical team generate airborne particles through their movements and activities, and how these contaminants are distributed over short distances around the patient and surgical field (the surgical microenvironment).
Invisible particles, real consequences: Rethinking contamination in operating rooms
We all remember the time of COVID-19, when suddenly everyone became aware of viruses, disinfectants, and hygiene. It often felt as if we cleaned enough or used enough disinfectants, we could eliminate all risks. But over time, we realized that transmission is far more complex, especially when it comes to invisible airborne particles.
What the pandemic really highlighted was how easily particles can move through the air and how difficult they are to control once they are released into indoor environments. The Covid-19 outbreak brought indoor air quality into the spotlight, particularly in critical environments like operating rooms, where even small levels of contamination can have serious consequences. At the same time, the number of surgeries worldwide continues to increase, making it even more important to maintain safe and sterile conditions. Yet, despite strict protocols and advanced technologies, healthcare-associated infections (HAIs), especially surgical site infections (SSIs), as one of the most common and expensive types of HAIs, remain a major challenge.
The ultra-clean operating room vs the human factor
Generally, in operating theaters, contamination can originate from several sources, including supply air, adjacent spaces, and the activities taking place within the room. However, in the majority of today’s modern ultra-clean operating rooms equipped with high-efficiency particulate air (HEPA) filtration and maintained under positive pressure, external sources of contamination are greatly reduced. As a result, the primary contributors become the occupants themselves, the surgical team, and the patient, and their behaviors and activities.
Among these human-related sources, two are particularly important. The first is the continuous shedding of skin particles, which may carry microorganisms. The second is respiratory activity, such as breathing and speaking, which produces droplets that can also contain microorganisms. These emission processes generate particles of different sizes, and this size variation strongly influences how they behave in the air. Once released, particles do not follow the same path. Their movement, transportation, and deposition depend largely on their size, with smaller particles being more easily carried by airflow and remaining suspended for longer periods, while larger particles tend to settle more quickly due to gravity.
This is what makes the problem particularly challenging. The human factor is one of the most dynamic and least predictable elements in the operating room environment. While technology can control airflow and filtration with high precision, human behavior introduces variability that is much harder to quantify and manage.
Ultimately, contamination control is not only about advanced ventilation systems or strict protocols, but also about understanding and reducing variability caused by human presence and activity. Recognizing this complexity is a crucial step toward designing more effective strategies to improve patient safety and reduce infection risks.
Where human presence, their movements, and activities redefine airflow patterns, airflow dynamics, contaminants’ transportation, and infection risk
This is exactly where my research begins.
I am part of the HumanIC project which aims to improve healthcare environments by reducing infection risk while also ensuring thermal comfort for both patients and healthcare workers, without neglecting energy efficiency and sustainability. In other words, the goal is to balance health, comfort, and sustainability.
To investigate this, I mainly conduct experiments in a full-scale simulated operating room laboratory (OR Lab) at NTNU, where I can study different scenarios under controlled conditions.
I use advanced measurement techniques, combining airflow visualization methods such as Particle Image Velocimetry (PIV) to understand airflow patterns with particle measurements (Optical Particle Counters, OPCs) to characterize airborne particles and their behavior.
Recently, I have mainly focused on using optical particle counters along with other sensors for particle measurements at specific critical locations within the surgical microenvironment. When possible, I complement these experiments with measurements at St. Olav’s Hospital to better capture the complexity of real surgical environments.
From research to impact: Towards safer hospitals and better patient outcomes
My research can contribute to more efficient hospital design by improving our understanding of how human activities and ventilation systems influence the distribution of airborne particles in operating rooms. A deeper understanding of these interactions may help support the development of more effective ventilation layouts and infection-control strategies, ultimately contributing to safer surgical environments and improved healthcare quality.
Beyond Research
Outside of research, I enjoy reading books, listening to podcasts and music, swimming, and playing chess. I also love photography, especially nature photography, and I enjoy making genuinely big puzzles, 5000+ pieces is where the fun really begins! Moreover, I’ve recently started exploring pottery and ceramics, which I find very soothing.
Despite common belief, as you can see, as a researcher I have a wide range of interests beyond my work, although that depends on whether the particles decide to cooperate and allow me to take a break from chasing them or not 🙂
About the author
Dorsa Rabizadeh is a PhD Candidate at NTNU – Department of Energy and Process Engineering, affiliated with the European Union’s Horizon Europe research and innovation program under the Marie Sklodowska-Curie Actions (HORIZON-MSCA-2022-DN-01, project no 101119726). She’s from Iran and she had a background in mechanical engineering. She holds both a B.Sc. and an M.Sc. in Mechanical Engineering, where she graduated as a top student, ranking first among all graduates.
During her studies, she developed a strong interest in multiphase flows and how small-scale phenomena can lead to large, sometimes unexpected outcomes, an idea that continues to shape her current research on airborne particles in operating rooms.
Rabizadeh is supervised by Professor Guangyu Cao and co-supervised by Professor Laurent Georges at NTNU.