A control system and associated methods for an air treatment system. In one aspect, the present invention provides a control system and method for controlling blower speed as a function of separately determined smoke and dust concentrations. In one embodiment, the control system and method provides a variable delayed between changes in motor speed to address undesirable rapid changes between speeds. In another aspect, the present invention provides a system and method for calibrating a sensor to provide more uniform operation over time. In yet another aspect, the present invention provide a system and method for calibrating motor speed to provide more consistent and uniform motor speed over time. The present invention also provides a system and method for tracking filter life by as a function of time, motor speed and/or a sensed variable, such as particulate concentration in the environment.