A method of alternatingly emitting two or more volatile materials, the method including the steps of: (a) activating a first heater to emit a first volatile material; (b) emitting the first volatile material for a first time period of time including the steps of: during a first portion of the first time period, emitting the first volatile material such that a first primary room concentration is achieved; and during a second portion of the first time period, emitting the first volatile material such that a first secondary room concentration is achieved; wherein the first secondary room concentration is less than the first primary room concentration and the first secondary room concentration occurs after the first primary room concentration; (c) deactivating the first heater; (d) activating a second heater to emit a second volatile material; and (e) emitting the second volatile material for a second time period of time including the steps of: during a first portion of the second time period, emitting the second volatile material such that a second primary room concentration is achieved; and during a second portion of the second time period, emitting the second volatile material such that a second secondary room concentration is achieved; wherein the second secondary room concentration is less than the second primary room concentration and the second secondary room concentration occurs after the second primary room concentration; (f) deactivating the second heater; and repeating the steps of (a) through (f) wherein: the room concentration of the first volatile material peaks at the first primary room concentration and trends downwardly until the first secondary room concentration at the point where the first heater is deactivated; and the room concentration of the second volatile material peaks at the second primary room concentration and trends downwardly until the second secondary room concentration at the point where the second heater is deactivated. (a) activating a first heater to emit a first volatile material; (b) emitting the first volatile material for a first time period of time including the steps of: during a first portion of the first time period, emitting the first volatile material such that a first primary room concentration is achieved; and during a second portion of the first time period, emitting the first volatile material such that a first secondary room concentration is achieved; wherein the first secondary room concentration is less than the first primary room concentration and the first secondary room concentration occurs after the first primary room concentration; (c) deactivating the first heater; (d) activating a second heater to emit a second volatile material; and (e) emitting the second volatile material for a second time period of time including the steps of: during a first portion of the second time period, emitting the second volatile material such that a second primary room concentration is achieved; and during a second portion of the second time period, emitting the second volatile material such that a second secondary room concentration is achieved; wherein the second secondary room concentration is less than the second primary room concentration and the second secondary room concentration occurs after the second primary room concentration; (f) deactivating the second heater; and repeating the steps of (a) through (f)