Abstract: Lighting devices using selectively permeable barrier elements, graphite sheet materials, and/or browning agent destroyers/sequestering agents are disclosed. In one embodiment a lighting device may include a body or housing with a selectively permeable barrier element, such as a silicone membrane or o-ring to allow diffusion of contaminants from one or more interior volumes to the exterior environment. Contaminants may be mitigated through use of a sequestering agent/browning agent destroyer. Heat conduction between elements of the housing, such as to aid removal of heat generated from a lighting element such as an LED, may be improved through use of graphite materials, such as PGS sheets between housing elements.