an environmental control system having particulates in air therein includes a sensor , an air purification subsystem , and a controller in communication with the sensor and air purification subsystem . the sensor detects particulates in the air , and generates a particulate concentration signal . the controller : compares the particulate concentration signal to a predicted particulate concentration threshold that is based on one of a probability of odor detection , a probability of sensory irritancy detection , and a combination thereof . when the particulate concentration signal reaches the predicted particulate concentration threshold , the controller commands the air purification subsystem to alter a condition in the air containing the particulates .