The system and method provide for the monitoring and trending the rate at which fire detection devices get dirty. This information is used to determine which devices are clogged or getting clogged and to establish that the chambers are open to air flow because they are accumulating dirt over time. Air flow through the detection chamber is proven using this analysis. Further self-testing is also employed for the fire detection devices by including modules that simulate the smoke interference with the light. This can be accomplished in two ways. In one example, light from the chamber light source can be reflected toward the scattered light photodetector to simulate alarm conditions. In another example, an additional chamber light source can be added to the detection chamber that can generate light to simulate alarm conditions.