Safety Services



This page provides guidance on managing the risk of spillages and dealing with spills at UCL.

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What is a spill?

Purple chemical being poured into a container

A spill is any accidental empyting, overflow or release of a substance out of its container or vessel. 

Some examples of spills include:

  • Spilling a beverage or soup in the office / kitchen
  • A cleaner accidentally spilling the cleaning materials on the floor
  • Students spilling fluids during an experiment in a teaching room
  • A spillage of chemical, biological or radioactive substances in a laboratory

What are the risks from spills?

Spills large or small create an immediate slip hazard. Spills of hazardous substances can have greater consequenes as the spill removes containment of the substance and can create an aerosol increasing its risk of inhalation. Potential splashes also increase the risk of absorption through the skin directly or through clothing that is contaminated. A spill where the area of contamination can’t be defined (such as a wide splash area) or the entire spill area isn’t accessible, risks leaving hazardous substances present after cleanup. Depending on the chemical or infectious substance, this increases the risk of subsequent injury or infection.

The risk is high when inhalation is possible. This may be a volatile chemical or an aerosol of a chemical or infectious substance. This is particularly important if the mode of transmission of infectious substances can be by inhalation. Risk is also increased by spills from height, or when they are widely distributed in an open area (loss of containment under pressure) or closed area (loss of containment within a centrifuge or orbital shaker). Stay clear, evacuate or keep equipment closed to allow aerosols to settle.

Some laboratories will use a combination of biological, chemical and GM hazards and the specialist sections below must be considered for all hazards present. This is to ensure that the correct spill kits are available. users are trained in where they are, their content, how they should be used and when the risks presented by a spill mean it should not be attempted to be cleaned up independently.

Spill kits

A spill kit is a well-organised set of equipment that has been specifically designed to deal with cleaning up hazardous substances. It enables you to efficiently clean the spill in the safest way possible. The purpose of a spill kit is to contain, control and clean up.

The general contents of a spill kit include:

  • Instructions on its use and the substances it is suitable for
  • Absorbent materials
  • A containment boom / movable bunds for preventing further spread of the spill
  • Specific personal protective equipment (PPE)
  • Waste disposal bags
  • Neutralising substances (for specific substances)

Spill kits should be:

  • Easily accessible and signposted
  • Have its contents always replenished
  • Be situated as near to the location where spills are likely to occur
  • If there is a risk of spills within a secure environment (e.g. a containment level laboratory), then a spill kit should be available within the secure area

General guidance in the event of a significant spill of any hazardous substance

  • Be prepared for the foreseeable hazards from spills in the work area, considering spills as part of your risk assessment
  • Have a spill kit of the appropriate size and contents in place
  • Staff must be trained in the use of spill kits and drilled in their use for high hazards
  • In the event of a spill, tell people. Evacuate the area if necessary, to keep people safe. This allows time to think clearly, assess the situation and call for assistance
  • Are individuals contaminated or injured? Take care of injured parties.
  • Be safe. Quarantine the area to prevent unauthorised entry
  • Wear PPE, ensure the area is safe to enter (there may be a risk fire, inhalation of toxic or infectious substances etc.)
  • Stop the source (boom or sock)
  • Contain the spill, including protecting the drains
  • Notify authorities if required at this stage (are sewage plants affected?)
  • Clean up, starting work from the outside in
  • Dispose of safely in the correct waste stream
  • If sharps are present, never touch sharps by hand.Sharps must be picked up with forceps or a dustpan and brush and discarded into a sharps container
  • Decontaminate the area
  • Restock response equipment
  • Report the incident on riskNET, there may be legal requirements for it to be reported to authorities once the spill has been dealt with
  • Review the response and consider if further decontamination steps are required
  • Review and disseminate the findings

Responding to chemical spills

For information and guidance on responding to chemical spills, follow the link below to our webpage.

Responding to chemical spills →

Spills in CL2 and CL3 facilities

For dealing with biological and GM spills, including blood spills, the contents of the spill kit should include the items listed below, depending on the level of risk:

  • Instructions
  • Do not enter sign
  • PPE such as gloves, RPE and lab coat or gown for the helper
  • Sufficient decontamination solution (e.g. Distel or 2N NaOH solution)
  • Paper towels
  • Liquid soap
  • Alcohol gel or wipes for initial decontamination and cleaning of worker
  • A sheet to cover the contaminated person with
  • Shower accessories (towel, soap)
  • Large pair of scrubs or coverall suit for worker to wear after the decontamination procedure
  • Autoclave bags
  • In addition, every CL3 worker should be advised to keep a spare set of clothes at the workplace for emergency reasons.

The contents have a limited shelf life and must be replenished so they are effective and not out of date.

Due to the risk of infection in containment level laboratories, spills are classified as minor or major and different procedures put in place. The following must be put in place in its entirety in CL3 facilities.

All accidents, injuries, near misses and dangerous occurrences must be reported on riskNET, no matter how trivial. If they have not already been informed, the CL3 lab manager or other lab manager, deparmental safety officer (DSO), work supervisor, and in the case of a significant spill, the UCL Biological Safety Advisor must all be informed.

Minor spill

The following must be the case for a spill to be considered minor:

  • The spill is within a microbiological safety cabinet (MSC)
  • The quantity (volume and titre) is less than that defined by risk assessment as minor
  • The spill area is clearly defined, and the total spill is accessible.

Procedure for a minor spill

  • Remain calm
  • Stop work
  • Assess the spill and the risk
  • In the event of a minor spill, outer gloves must be changed immediately.
  • Treat a minor spill of infected material within a safety cabinet by flooding it with a suitable disinfectant (e.g. 5% Distel) for at least 30 minutes and then mop up with disposable absorbent material.
  • Where the risk is increased by aerosol, such as a respiratory pathogen, cover with a paper towel, spray liberally with a suitable disinfectant (e.g. 5% Distel), leave soaking for at least 30 minutes
  • In the case of a spill during centrifugation, allow any potential aerosols to settle within the equipment for at least 30 minutes before opening.
  • Many disinfectants will not decontaminate prion spills. Use absorbent paper soaked in 2M NaOH placed over the spillage and leave it for 1 hour. Gloves should be changed and the spill cleaned up with fresh paper tissues.
  • Discard paper towel or absorbent material and gloves into a biohazard bag for autoclaving.
  • Clean the surfaces with paper soaked in a suitable disinfectant (e.g. Distel) and subsequently with 70% ethanol.
  • Gloves must be worn when cleaning up minor spillages
  • All materials discarded into a biohazard disposable must be autoclaved.
  • Any contaminated equipment must also be thoroughly decontaminated with a suitable disinfectant (e.g. 5% Distel) and subsequently with 70% ethanol

Major spill

If any of the following is the case, the spill is considered major:

  • The spill is outside an MSC
  • The quantity (volume and titre) is equal or greater than that defined by risk assessment as minor
  • The spill area is not clearly defined or is not totally accessible.
  • The user is not confident to tackle the spill without support

Procedure for major spill

  • Remain calm
  • All persons must leave the laboratory immediately in the event of a large spillage.
  • All work in a CL3 laboratory where spill has not occurred will also cease and be made safe.
  • Evacuation should be by the safest route into the adjacent laboratory taking care not to disturb the spill. The risk from respiratory pathogens requires keeping the greatest distance possible from the spill.
  • No attempt must be made to clean up or disinfect.
  • Contact the CL3, or other laboratory manager, and assess the spill and risk outside facility
  • Formulate an assessment of risks and a plan for the clear up and/or fumigation of the facility with the CL3 or other laboratory manager. The factors to be considered should include;
    • Type of biological agent; the hazard group, route of transmission, infectious dose (if known), and its stability in the environment.
    • Quantity and titre of the hazard
    • Location (MSC or open lab, defined and accessible or otherwise)
    • Type of accident; present (a dropped flask) or delayed (a break in a sealed centrifuge or orbital shaker), or whether an aerosol may have been generated.
    • Numbers of people potentially exposed
    • Air change rate and LEV filtration.
      Refer to HSE guidance for estimated clearance times →.
  • If the spill is in an MSC but deemed to be a major spill because it is of a sufficient volume, widely distributed or inaccessibly, then fumigation will be necessary,
  • Allow the cabinet to run for at least 1 hour to remove as much aerosol as possible, before following the appropriate procedure for fumigation.
  • In the case of a spill during centrifugation, allow any potential aerosols to settle within the equipment for at least 30 minutes before opening. Assessment of the risk may require the use of RPE (FFP2/3) depending on aerosol formation and scrubbing of the air.

Emergency decontamination 

If the user has been extensively contaminated with infectious material, or if personal clothing has been contaminated (which is likely to be accompanied by skin exposure). The user should follow the emergency decontamination procedure.

The affected party should;

  • Remove all contaminated clothing (including shoes and trousers if any spillage occurred onto them) and leave them inside the room
  • In the case of respiratory pathogens, do not remove RPE
  • Do not attempt to clean the spillage before leaving
  • Call for assistance. Press the alarm or lone worker alarm to inform the CL3 manager or other competent user.
  • Move to the lobby until a helper arrives
  • Prevent further entry or further use of the facility

A helper (normally another user) should:

  • Put on required CL3 PPE provided in the ‘decontamination kit’ located in the lobby. In the case of respiratory pathogens, a FFP3 face mask is required, and helpers must be face fit tested.
  • If necessary, assist in removing contaminated clothing from the affected person
  • Put a ‘do not enter’ sign in place
  • If splashed, the eye must be irrigated immediately using the hand wash basin for several minutes. It must not be rubbed.
  • Using a suitable disinfectant (e.g. 5% Distel), decontaminate clothing where appropriate. Contaminated materials should be placed into an autoclave bag.
  • Using paper towels and liquid soap, the assistant should then help the user to wash any skin that has been exposed to infectious materials.
  • The user can then put on the coverall suit and seek medical advice, if necessary.
  • The assistant should then dispose of their PPE into an autoclave bag and wash their hands.
  • The autoclave bags should be transferred to the empty decontamination box for transport to the autoclave room for sterilisation.

If there is a possibility that infection has occurred as a result of a spill, immediately inform Workplace Health for advice and further assessment, and go to the nearest Accident and Emergency department. Ensure that information on the infective agent is taken.


Fumigation will be required in the event of a significant spillage or aerosol release of an HG3 pathogen unless the risk assessment states otherwise. Fumigation is unlikely to suitable for clearing large spills and penetrate large volumes of liquid alone. Clean-up of large volumes may be required in advance of fumigation using disinfectant. To facilitate this, air handling should be used to clear the room of aerosols and RPE may be required, particularly for respiratory pathogens.

Microbiological safety cabinets (MSC)

  • If the spill is in an MSC but deemed to be a major spill, then fumigation will be necessary.
  • Allow the cabinet to run for at least 1 hour to remove as much aerosol as possible, before following the appropriate procedure for fumigation.
  • Fumigation is also required for a highly infectious or airborne transmissible agent such as a HG3 respiratory pathogen.
  • Provide fumigation contractors with all required information to enable their work.


  • The CL3 lab manager will contact UCL Estates and the UCL Biological Safety Advisor to assess the risk, discuss and, if required, recommend facility fumigation.
  • Re-entry should be avoided unless necessary for fumigation.
  • Provide fumigation contractors with all required information to enable their work.
  • A 'do not enter' sign will be posted and the facility locked, or card access suspended to prevent access to any member of academic staff, students, Estates and contractors.
  • Once a time and date has been set for fumigation, inform Estates and get acknowledgement of the message in writing or in person before starting fumigation. Estates will need to prepare for fumigation, such as adapting fire alarms, closing dampers and turning off air handling.
  • Information must be shared on the actions to take in the event of an emergency (e.g. escape of fumigant from the laboratory).
  • Access to the CL3 facility will not be permitted during fumigation. A 'do not enter' sign will be displayed until the contractor gives permission that the fumigant is gone, negative pressure is achieved, and it is safe to re-enter.

Information and training

Users of laboratory space must be informed and trained in the actions expected in the event of a spill during their induction. The contents of training should include:

  • The findings of the relevant risk assessments to the work activity.
  • Specific procedures for the relevant hazardous substances
  • Examples of foreseeable incidents recorded in the facility ‘code of practice’ so users can be trained in the recommended response to their occurrence
  • Contents of the spill kit
  • What the spill kit is suitable for.
  • The hazards of foreseeable spills
  • The whereabout of any spill kit
  • How to use the spill kits
  • The size and nature of a spill that can be tackled without competent assistance
  • When a spill kit should not be used by an individual
  • Lone workers must have access to spill kits, be competent to respond to a spill and be capable of raising the alarm.
  • Reporting of all spills on riskNET, as there may be a legal requirement to report them to the competent authority
  • Reporting of all spills to laboratory managers so that spill kits can be replenished.
  • Carry out periodic refresher training and record it
  • A schedule of drills must be planned and written in the facility ‘code of practice’ and carried out to ensure users are familiar with the emergency procedures for foreseeable incidents. The results of the drills must be recorded, reviewed and the findings circulated to all users.

> Download the training guidance for spills

Last updated: Friday, October 22, 2021