Overexposure to ultraviolet (UV) light is known to cause skin cancer, premature aging, immune system suppression, and eye damage. What many cannabis growers don't know, however, is that they may also be exposed to harmful amounts of ultraviolet light on the job.
Metal halide lights
Metal halide lights used in grow rooms have an inner arc tube that is similar to a welder's arc and emits intense ultraviolet radiation along with visible light. Normally, an outer glass bulb reduces the ultraviolet radiation; but, if the bulb is broken, ultraviolet levels can be significant enough to cause
photokeratitis – a painful eye condition that happens when the eye is exposed to ultraviolet light. Symptoms include tearing, blurry vision, and the feeling of a foreign body in the eye that typically peak six to 12 hours after exposure. Broken metal halide bulbs should be immediately removed from service to prevent photokeratitis.
Many growers also use ultraviolet lamps in their grow rooms. The effect of overexposure from UV lamps, which can affect eyes and skin, depends on ultraviolet intensity and wavelength, the body part exposed, and the sensitivity of the person to ultraviolet light. Symptoms of overexposed eyes include painful inflammation, a gritty sensation, and tears within three to 12 hours. Overexposed skin can burn within one to eight hours. Some medications can also increase a person's sensitivity to ultraviolet light.
Ultraviolet-C lamps in particular – often referred to as germicidal lamps – can cause painful burns on the skin and temporary damage to the cornea if observed directly.
LED and fluorescent lights
LED and fluorescent lights are also used in grow rooms. Health hazards associated with broken fluorescent lamps include lead, cadmium, and mercury.
- Choose grow lamps with lower ultraviolet intensities.
- Position ultraviolet bulbs at least eight feet above the ground.
- Train employees how to take proper safety precautions with ultraviolet bulbs.
- Never use germicidal lamps when workers are present. Rooms containing germicidal lamps should be interlocked to prevent access while lamps are on.
- Display warning signs where ultraviolet-emitting bulbs are used.
- Provide eyewear that protects workers from the ultraviolet wavelengths emitted by bulbs in grow rooms.
- Encourage workers to wear long-sleeved shirts to limit their exposure to ultraviolet light.
- Consider substituting metal halide lights with safer alternative lighting such as LED.
- Operate metal halide and high-pressure sodium discharge lamps with the appropriate ballast, rated fixture, and socket.
- Ensure that workers follow safe electrical practices when they change bulbs.
Disposing of used and broken lights
Lighting that contains mercury, such as fluorescent, high-pressure sodium, mercury vapor, and mercury halide lamps, is classified as “Universal Waste" and covered by the Oregon's hazardous waste regulations and the Resource Conservation and Recovery Act (RCRA).
Immediately remove broken bulbs from service. If a bulb is broken, the room should be ventilated and central forced-air heating and air conditioning should be shut off while repairs are made. Ensure that used and broken bulbs are disposed of as hazardous waste.
Do not vacuum broken bulbs. Broken glass should be swept onto stiff paper or cardboard. Sticky tape can be used to pick up small glass fragments and powder. Put used tape in a glass jar or plastic bag. Put clean-up materials in a sealed container.
Label used and broken bulbs as “Waste Lamp," “Used Lamp," or “Universal Waste Lamp." If the bulbs are placed in a container, only the container must be labeled – not the individual bulbs. Take the contents of the container to an appropriate disposal facility.