Safety advisory on metal halide lamps

The US-Amercican Department of Consumer and Business Services, Occupational
Safety and Health Division (Oregon OSHA) released a safety advisory to educate
employers and workers about the hazard posed by ultraviolet (UV) light
overexposures from broken metal halide lamps.

Late last year, approximately 60 employees reported eye and skin irritation or
sought medical attention after attending a meeting. The source of alleged UV
overexposure was identified as a metal halide lamp with a broken protective

Light measurements were conducted using a broken bulb similar to the one
present on the day of the exposure incident. Readings from intact bulbs were
within acceptable national standards, while radiation from directly beneath the
broken lamp reached the maximum allowed daily exposure levels for UV radiation
within eight minutes.

The source of the excessive light radiation was a 400-watt metal halide bulb
with a damaged outer protective cover. The bulb's inner quartz tube continued
to function properly, and radiated light energy without the UV-filtering
properties of the glass cover absorbing the UV radiation. This form of lamp is
common in many large indoor or outdoor facilities where lighting is required to
cover a broad area, for example, gymnasiums and auditoriums, large warehouses
and warehouse retail stores, and sports facilities.

Oregon OSHA recommends that employers with facilities that utilize metal halide
lamps follow several recommendations to protect workers or visitors, and
prevent possible UV overexposures:

  • Educate workers about the potential hazard of UV light overexposure.

  • Regularly inspect overhead lights for cracks or breakage.

  • Use self-extinguishing metal halide lamps. When breakage occurs, the lamp
    will shut down automatically as a precaution. Metal halide lamps utilizing this
    feature are commercially available.

  • For existing lamps, consider an additional glass or plastic lens to screen
    UV rays. The additional protective lens fits under the light and envelope
    assembly of the light.

Further Information

AplusA-online.de - Source: Oregon OSHA