This research will help to limit the spread of hospital-related infections. Experts agree that infection-prone surgery (orthopedic and transplant operations) should be performed in an ultra-clean atmosphere. There is evidence of a strong correlation between the level of airborne bacteria and infection. An efficient ventilation system is therefore extremely important in the protection process. There is a significant difference in what degree of different airflow principles and climatic conditions prevent bacterial spread. The most effective ventilation principle is an ideal parallel-organized air front with good transport capacity, which is not yet sufficiently developed for practical applications. Mixing ventilation is an alternative method with poorer function. In addition, we do research on particle inhalation and how/where they deposit inside the human respiratory system. This will be the foundation for future proposals in collaboration with the medical industry and hospitals.