Time limits in the control of pollution systemsTime limits in the control of pollution systems Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-10-061981enExponentially growing pollution systems are examined from the point of view of control. A simplified mathematical model is used. Employing optimal control theory, we show that it is not always possible to drive the state (level of pollution) of such a system to a desired level. We prove that the state has to be smaller than certain bound for the system to be controllable. A specific example illustrates these ideas. The importance of this research lies in the fact that it shows the existence of certain state, and, consequently, time limits in the process of controlling the system. http://creativecommons.org/licenses/by/4.0/Journal of Theoretical Biology393541-546 Yannis Phillis Φιλλης Ιωαννης Balance of nature Biology--Ecology Bionomics Ecological processes Ecological science Ecological sciences Environment Environmental biology Oecology ecology balance of nature biology ecology bionomics ecological processes ecological science ecological sciences environment environmental biology oecology