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Environmental Health & Safety


The high-intensity, high-power mercury vapor lamps frequently used for floodlighting and area lighting pose a very severe risk of an ultraviolet burn (like sunburn) if operated when the outer envelope is broken away. These lamps are normally made with two envelopes, one inside the other, and they will still function even when the outer envelope if broken.. The mercury arc which is established in these lamps emits intense ultraviolet radiation as well as visible light. The outer envelope absorbs the ultraviolet and an intact lamp presents no UV hazard. Without the protection of the outer envelope, an acute and possibly serious burn can result in seconds if one is within a foot or so of the lamp. In one case, some 25 persons were burned by a broken lamp from 25 to 35 feet away.

Whenever it is necessary to work on or in the vicinity of such lamps when they are lit, it is imperative that a determination be made first that the lamp is shielded, either by an intact outer envelope or (in some cases) the diffuser globe in which the lamp is housed. Do not risk serious exposure by inspecting such lamps while lit, unless it is certain that adequate shielding is present for the absorption of the UV.

Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.

This page last updated 11/24/2010. Disclaimer.