This study highlights significant differences in air quality data obtained from wall-mounted and device sensors. The findings suggest that the sensor placed at the inlet of the air purifier provides more accurate and immediate readings, particularly in environments with fluctuating air quality. In contrast, the wall-mounted sensor may introduce delays, reducing their effectiveness for real-time monitoring. These results have important implications for designing indoor air quality monitoring systems, where sensor placement should be prioritized to ensure accurate assessments of human exposure to pollutants. More studies are needed to visualize the relationship between the concentrations of wall-mounted particle sensors, ventilation exhaust sensors, and the sensor placed at a local air purifier inlet. This could be done by using CFD simulations.