In this study, the performance of a portable air cleaner, which is used to clean the air of a room with a person sitting in it, was investigated. The effects of different blowing angles and flow rates from the air supply vent on the device cleaning performance were investigated. In this context, air age and clean air delivery rate (CADR) parameters were calculated numerically. Randomly distributed particles in the room were tracked using the discrete phase model (DPM) and the relationship of pollutant concentrations with CADR and air age was examined. It has been seen that the blowing angle is an important parameter along with the flow rate. Moreover, it was concluded that the air age approach can be used to determine the performance of air cleaning devices. It has been found that the air cleaning device capture more than half of the particles in the environment, while the remaining particles are captured by other room surfaces.