Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment. Why is. mercury used .in the manufacture of these lamps ?

Fluorescent lamps contain a small amount of mercury because the element’s vapor, when electrically excited, emits ultraviolet (UV) radiation; this UV production is the essential first step in generating light in these lamps. The UV photons produced by excited mercury atoms strike a phosphor coating on the inside of the tube, and that phosphor absorbs the UV and re‑emits visible (white) light—so mercury supplies the UV source, not the visible light directly. Because lamps therefore deliberately include mercury vapor, breakage or indiscriminate disposal can release mercury to the environment, which is why such lamps are managed as mercury‑containing products [1].

Sources

1. [1] https://minamataconvention.org/sites/default/files/documents/working_document/compilation_03_lamps_20Aug_Clean.pdf