Safety Services



Mercury is easily absorbed through the lungs in the bloodstream. It can accumulative in the body, including in the brain tissue of children and developing foetuses.

Why this substance is hazardous?​

The character from Alice in Wonderland, the Mad Hatter, may derive from the health risk that mercury presents. Erethism, also known as Erethism Mercurialis or mad hatter disease is a neurological disorder which affects the whole central nervous system caused by mercury poisoning.​

Mercury is easily absorbed through the lungs in the bloodstream. It can accumulative in the body, including in the brain tissue of children and developing foetuses.  ​


  • Mercury is used for demonstration purposes as it is the only metal that is liquid at room temperature.​
  • The use of mercury-based chemical reagents still provides synthetic routes currently used.​
  • Mercury is still used in thermometers and barometers and it can be found in dental fillings.​

Recommended control measures​

Mercury and its compounds are controlled chemicals (Poison  UCL ref PA008) – see information on standards for all controlled chemicals


  • The distillation of mercury should not occur on any UCL controlled site including in vacuum pumps. If it becomes vital to a research project, it must have the written permission of the HoD and be carried out in a dedicated room and fume cupboard with full supervision at all times.​
  • Alternatives to mercury should be used including but not limited to alcohol and electronic thermometers.​

Reduce exposure​

  • Although mercury only evaporates at room temperature slowly, precautions must be in place to prevent this and increasing the likelihood of exposure through inhalation. ​
  • Always have good ventilation, if possible work with LEV​
  • Mercury is highly mobile should be bunded at all times. Carry out any work in a tray or similar item that is smooth and impervious.​

Health surveillance ​

  • Mercury levels can be found by using urine or blood samples tested by an accredited laboratory.​ 
  • After the loss of containment, air monitoring should be carried out to test mercury vapour concentration. ​
  • Safety Services cannot perform either of these functions so an external party will need to be contacted.​

Decontamination of Mercury​

Spill of one thermometer or less​

Spill kit​

  • 4-5 zip locking plastic bags​
  • trash bags (2 to 6 mils thick)​
  • rubber, nitrile or latex gloves​
  • paper towels​
  • cardboard or squeegee​
  • eyedropper​
  • shaving cream and small paint brush / duct tape​
  • flashlight or small task light​
  • optional: powdered sulphur


  • Put on rubber, nitrile or latex gloves.​
  • If there are any broken pieces of glass or sharp objects, pick them up with care. Place all broken objects on a paper towel. Fold the paper towel and place in a zip locking bag. Secure the bag and label it as directed by your department.​
  • Locate visible mercury beads. Use a squeegee or cardboard to gather mercury beads into small mercury balls. Use slow sweeping motions to keep mercury from becoming uncontrollable. Take a flashlight, hold it at a low angle close to the floor in a darkened room and look for additional glistening beads of mercury that may be sticking to the surface or in small cracked areas of the surface. Note: Mercury can move surprising distances on hard-flat surfaces, so be sure to inspect the entire room, including any cracks in the floor, when searching.​
  • Use the eyedropper to collect or draw up the mercury beads. Slowly and carefully squeeze mercury onto a damp paper towel. Alternatively, use two pieces of cardboard paper to roll the mercury beads onto the paper towel or into the bag. Place the paper towel in a zip locking bag and secure. Make sure to label the bag as directed by your local health or fire department.​
  • After you remove larger beads, put shaving cream on top of a small paintbrush or a piece of duct tape and gently "dot" the affected area to pick up smaller hard-to-see beads. Place the paintbrush or duct tape in a zip-locking bag and secure. Make sure to label the bag as directed by your local health or fire department.​
  • OPTIONAL STEP: Use powdered sulphur to absorb the beads that are too small to see. The sulphur does two things: ​
    • it makes the mercury easier to see since there may be a colour change from yellow to brown, and​
    • it binds the mercury so that it can be easily removed and suppresses the vapour of any missing mercury​
Spill of greater than one thermometer up to 1 lb (pound) or 0.45 Kg ​

Procedure ​

  • Have everyone else leave the area; don't let anyone walk through the mercury on their way out
  • Open all windows and doors to the outside.​
  • Turn down the temperature
  • Shut all doors in the room and leave the area
  • Do not vacuum
  • Call Security emergency number 222 as soon as possible​
Greater than 1lb or 0.45kg - GET OUT

Get out, secure the areas and call Security on 222.​


  • Never use a vacuum cleaner to clean up mercury. The vacuum will put mercury into the air and increase exposure
  • Never use a broom to clean up mercury. It will break the mercury into smaller droplets and spread them
  • Never pour mercury down a drain. It may lodge in the plumbing and cause future problems during plumbing repairs. If discharged, it can cause pollution of the septic tank or sewage treatment plant.​
  • Never walk around if your shoes might be contaminated with mercury​

Chemical safety library

> Read more about control measures for chemicals in our chemical safety library

Last updated: Tuesday, June 23, 2020