Clean-up of Fire Extinguisher Materials Causes Eye and Throat Irritation

What happened?  

Three workers were cleaning up fire extinguisher material that had leaked out of a broken fire extinguisher in their workspace. All three workers developed sore throats and eye irritation while cleaning up the residue. This incident took place in a non-laboratory area. However, this type of exposure could also occur in a lab environment.

What was the cause? 

Chemicals contained in fire extinguishers can cause irritation of the mucous membranes of the eyes and respiratory tract. The workers were not aware of this risk. Luckily these extinguishing materials are generally non-toxic.

How can incidents like this be prevented? 

When cleaning up any chemical powder, you should do the following:

  • Perform a risk assessment to know the hazard and risk of the extinguisher materials
  • Wear gloves and safety goggles
  • Wear appropriate respiratory protection
    • Dry Chemical Extinguishers can contain irritating chemicals. Wear a dust mask or an N95 respirator during the clean-up. Please note, that use of respirators requires users to be fit-tested by EH&S and medically cleared. Reach out to EH&S for help.
    • For potentially toxic chemical spills, a dust mask is NOT sufficient and an N95 respirator should be employed at a minimum. Reach out to EH&S for guidance before attempting to clean up these materials.


Fire extinguishers, their use and their materials

Fire extinguisher




Ordinary combustibles

Wood, paper, cloth, rubber, and many plastics


Flammable liquids and gases

Combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases


Live Electrical equipment

Electrical panel, motor, wiring, etc.


Combustible metals

Magnesium, titanium, zirconium, sodium, lithium, and potassium


Cooking equipment

Cooking oils, animal fats, vegetable oils


  • ABC Dry Chemical or multi-purpose dry chemical fire extinguishers contain monoammonium phosphate as the main ingredient. Note: The chemicals inside Dry Chemical Extinguishers can be irritants, use a dust mask (or N95), goggles, and gloves.
    • Vacuum (HEPA filtered) or sweep up as much of the excess residue as possible.
    • Make a solution of equal parts hot water and baking soda. Wipe the area and let the solution settle for about five minutes. Then rinse the area with warm water.
    • Residues that have hardened can be cleaned with a solution of equal parts isopropanol and warm (not hot) water.
    • Use soot erasers (natural rubber sponges) to effectively remove dust and dirt from surfaces that should not be exposed to water.
    • Dispose of all materials as regular trash.


  • Class BC or dry-chemical fire extinguishers contain sodium bicarbonate and potassium bicarbonate as their main ingredients. Note: Protect your hands and eyes from the dry powder residue by using goggles and gloves.
    • Vacuum (HEPA filtered) or sweep up as much of the excess residue as possible.
    • Mix together a solution using 98% hot water and 2% vinegar (3 ounces vinegar/1-gallon hot water) and wash the area with it. Let the solution settle for about five minutes then rinse the area using warm water.
    • Dispose of all materials as regular trash.


  • Class D fire extinguishers or dry powder extinguishers may contain powdered graphite, granular sodium chloride or copper. Note: Protect your hands and eyes from the dry powder residue by using goggles and gloves.
    • Clean up the powder residue by using a vacuum (HEPA filtered), brush or dry cloth.
    • Place all the powder from the vacuum cleaner or that has been swept up into a plastic bag and seal it. Dispose of the bag in the trash can.
    • Use a damp cloth to clean any residue of powder off affected surfaces.


  • Wet-chemical fire extinguishers (Class K) contain potassium acetate as their main ingredient. Note: Protect your hands and eyes from the wet chemical residue by using goggles and gloves.
    • Turn off all fuel sources connected to your cooking equipment and all nearby electrical equipment.
    • Use gloves to clean up any residue using hot water mixed with soap. Scrub the area using a sponge or cloth.
    • Rinse the surfaces and affected areas.
    • Allow the area to dry before you turn back on any of your equipment.
    • Dispose of all materials as regular trash.



NFPA Today: Fire Extinguisher Types by Brian O’Connor

Quick Action Tips 

  • Before cleaning up any materials from a fire extinguisher, please be aware that the local Fire Authorities may need to preserve the scene for a fire investigation. Be sure to get approval from Fire officials before cleaning up these residues.
  • Before cleaning up fire-extinguisher material, consult your campus Fire Marshal to see if they can provide guidance or equipment needed for clean-up. Alternatively, your campus custodians may also be trained to clean up these residues.
  • Make sure to have your fire extinguishers replaced/refilled after use.