A modular ozone generator includes an ultraviolet (UV) lamp within a chamber for converting some of the oxygen molecules in air to ozone molecules. The air is introduced through an inlet at a high point of the chamber and discharged through an outlet at a low point of the chamber to increase the proportion of ozone molecules relative to the oxygen molecules discharged due to the higher density ozone molecules migrating downwardly. The introduced air is conveyed through a diffuser to provide multiple streams of air flowing about the lamp to enhance irradiation of the oxygen molecules and form ozone molecules. A second or more ozone generator modules are beneath the first ozone generator module with an interlocking mechanism to align the outlet of an upper ozone generator with the inlet of a lower ozone generator module. The number of cascaded ozone generator modules forming a vertical stack is a function of the concentration (and amount) of ozone molecules sought to be generated. Readily removable end caps for each ozone generator module accommodate repair and replacement of any and all internal components with or without dismounting the ozone generator module from its supporting structure. Slidably mounted tabs accommodate attachment of the ozone generator modules to hard points of the supporting structure.