When most people think of a large spill, they envision several hundreds or thousands of gallons. But, when it comes to mercury, a spill of as little as 2 tablespoons is considered big. Cleaning up mercury spills safely and completely can present some unusual challenges.
Mercury is the only metal that is liquid at room temperature. Like all liquids, when it is above its freezing point, it melts and evaporates. The freezing point of mercury is −37.6°F, so it is always evaporating. This presents an inhalation hazard to anyone in the area because mercury bio-accumulates in the body causing neurological and other health problems.
Unlike some liquids, mercury vapors are colorless and odorless. This makes it hard to detect without the use of specialized instruments. A pea-sized drop of mercury that goes undetected can take up to 384 days to fully vaporize. In that amount of time, it can cause severe neurological damage—especially in infants and children.
Spilled mercury does not act like most liquids. Instead of staying in a distinct puddle, when mercury hits a surface, it forms small beads that scatter on hard surfaces and will displace dust or dirt in crevices, making it harder to detect.
OSHA (Occupational Safety and Health Administration), NIOSH (National Institute for Occupational Safety and Health), ACGIH (American Conference of Governmental Industrial Hygienists), and ATSDR (Agency for Toxic Substances and Disease Registry) all acknowledge the hazards of mercury, but have different allowable exposure limits. The ATSDR limits are the most stringent because they encompass the entire susceptible population, including the elderly and small children.
When Mercury Spills
- Remove jewelry, watches and anything else with metal before handling mercury
- Wear goggles and latex, vinyl or rubber gloves
- Open windows to ventilate affected rooms
- Turn off central ventilation or HVAC units
- Properly dispose of items contaminated with mercury
- Use a standard vacuum cleaner or a broom to sweep up mercury
- Dump mercury down a drain
- Wash clothing or other items that have come in contact with mercury in a washing machine
- Walk through an area where mercury has spilled
- Make sure the spill is mercury, especially if the spill is from a broken thermometer. Mercury has high surface tension and stays in beads. The beads scatter quickly and roll easily.
- Some thermometers are filled with Galinstan, which is silver-colored like mercury but is non-toxic. Mercury forms beads, Galinstan splats and sticks to surfaces.
- Air monitoring devices can help determine the concentration of mercury vapor in an area.
Evacuation and Isolation
- Close doors and prevent access to affected areas.
- Avoid walking through the spill area.
- Bag shoes, clothing, and other items that may have come in contact with spilled mercury.
- Turn off HVAC systems and open windows to ventilate rooms.
Cleanup and Decontamination
- Remove jewelry and wear proper PPE during response.
- Place broken or contaminated items in bags and seal them. Mark the bags for proper disposal.
- Do not use vacuums, brooms or mops to collect mercury droplets. This will spread them even more.
- Do not chase mercury droplets. Dip a paintbrush in shaving cream, mayonnaise or whipped cream and dab it on surfaces to immobilize the mercury and make it easier to pick up.
- If mercury droplets are contained, index cards and small dustpans may be used to collect the droplets.
- Use opposed lighting to look for mercury droplets. To do this, place a flashlight at floor level in an unlit room and look for anything shiny.
- Mercury is heavier than dust and dirt and will hide under it. Look for it in grout lines, floor cracks and other recessed areas.
- To make a small brush to get into small nooks and crannies, cut an old extension cord into 3″ pieces. Expose the copper wire to make a brush. Mix salt and vinegar in a glass or plastic container with a screw-on lid to make a flux. Shake the mixture and make sure there is still some salt left in the bottom of the container. Dip the brush into the flux and wipe it off. Dip it again and swish it around. Dry it off and it’s ready to use. The copper will amalgamate the mercury on contact.
- Specialized mercury spill kits that contain sulfur or zinc powder can be used to amalgamate mercury and suppress mercury vapors.
- Warm, soapy water and anti-dandruff shampoo that contains at least 1% selenium sulfide can be used during the decontamination process for workers or others who may have come in contact with mercury.
You tell us: Is a mercury spill a concern at your facility? What other tips do you have for dealing with the cleanup of a mercury spill? Let us know in the comments section below!