Metal halide lose efficacy quite quickly but you can't see it by eye, check the rated hours. Also, the Lumiere usually has a glass pane it, this blocks the UV

Metal halide lose efficacy quite quickly but you can't see it by eye, check the rated hours. Also, the Lumiere usually has a glass pane it, this blocks the UV - extended exposure to the bulb direct without these panes of glass is definately harmful, eg cataracts, melanoma etc