Controlling Indoor Benzene Concentrations using a Fuzzy System

Abstract Indoor occupational exposure to hazardous concentrations of Volatile Organic Compounds (VOC) at small workshops could have impact in the health of the workers, resulting in severe intoxication, respiratory diseases or even cancer. Therefore, controlling the concentration of (VOCs) in indoors is necessary to avoid injuries of the workers. In this manuscript it is presented a strategy to reduce hazardous indoor air benzene concentrations in small workshops through the use of a fuzzy logic controller. The closed room is separated in two defined zones using the Near Field-Far Field (NF-FF) model. From the knowledge of the (NF-FF) model a Mamdani fuzzy model controller was designed to maintain the benzene concentration within secure levels for the workers. Fuzzy systems can be analyzed as a mapping between an input data vector (error) and a control output. The input-output behavior is defined by fuzzy rules which infer an output value from an input value. A fuzzy control system is used to characterize the duty cycle required by a pulse width modulator (PWM), which controls the speed of direct current (DC) motors of exhaust fans; thus keeping the indoor air benzene concentration within the regulations established by the EPA (0.03 mg/m 3 ). The simulation results show that the proposed fuzzy control is promissory to assure indoor air quality in this kind of work environments.