The use of air conditioning system in dental hospitals creates a higher risk of airborne infection due to the amount of aerosol release form the patient’s mouth. Air suction positioned close to the patient seat are necessarily. The effectiveness of the system in reducing the airborne infection risk depends on how the room ventilation for fresh air exchange works. A walkthrough survey was conducted in the RSGM UMY dental hospital. The objective data, which consists of temperature, humidity, airflow, and CO2 levels, were collected using a handheld measuring instrument. Rooms with mechanical ventilation systems are in good indoor air comfort with an average temperature of 26 ℃ and average humidity of 71% based on the standards. However, the effectiveness of the ventilation system in reducing airborne infection risk is not yet measurable. This paper also proposed using computational fluid dynamic simulation as a preliminary technique following the walkthrough survey. The air velocity and the particle movement created by the ventilation system was evaluated.