The presence of air pollutants in the room can cause health problems in the long and short term. Indication of air pollution is the presence of CO and dust or particulates and bacteria. In addition to CO air pollutant substances and dust in the room, bacteria due to droplets is a severe problem. This study aimed to analyze the modification of a cyclone ventilator with the addition of an activated carbon filter to improve room air quality. This research is an experiment with an application in a natural environment in the form of a One Group Pre-Post Test Design. The air parameters analyzed were temperature, humidity, air flow rate, particulate meter (PM 2.5 ), and total bacteria in the room. The results show that the use of a cyclone ventilator with the addition of an activated carbon filter can improve indoor air quality for temperature parameters from 28.37 o C to 20.54 o C, humidity from 65.61–52.22%, PM 2.5 from 53.41 to 40.66 and air microbiology from 123.04 CFU to 66, 40 CFU and the airflow rate increased from 0.15 m/s to 0.29 m/s. Statistically, there was a significant difference (p ≤ 0.001) for all parameters measured before and after using a cyclone ventilator.