Abstract: A single device adaptable to alter any one of a variety of air characteristics such as temperature, humidity, ion content, odor, etc. Several interchangeable cartridges are provided. Each cartridge has an apertured support structure, an air treatment element that alters a particular characteristics of an air flow through the cartridge, and male connectors. The device has a housing, a fan, and female connectors that cooperate with the male connectors to position any one of the cartridges on the housing to receive an air flow discharged from the fan. When interfitted, the connectors also complete an electric circuit to a power supply that provides current to any electrically-operable cartridge. A removable protective envelope contains the cartridge. The protective envelope has an arm that inserts through a housing slot to trip a switch controlling current flow from the power supply. When the protective envelope is removed, current flow to the cartridge is disabled, allowing safe handling of the cartridge.