The prevention of nosocomial infections and surgical site infections is a major focus of the discipline of infection control. Any method can be used to propagate an infection, including blood, oral fluid, other fluids, surfaces, tools, air, etc. Air is the most abstract way of disease transfer. 99.97% of all particles larger than 0.3 microns in diameter may be removed by the HEPA (High-efficiency particulate air filter). However, it takes time for the HEPA filter to start lowering the microbial load in the air in the room. In this study, we examined the amount of time the HEPA filter needs to operate in order to prevent any development on a culture plate. We were able to stop any development on the culture plate after 30 minutes, highlighting the need of turning on the HEPA filter 30 minutes before surgery for the greatest benefits in preventing surgical site infections.