Date published: 31 May 2019

In recent weeks we have seen three serious incidents involving the mixing of slurry, incidents which very easily could have resulted in fatalities.

We are reminding the farming community: DO NOT TAKE ANY CHANCES WHEN MIXING SLURRY!!  

Slurry gas is released very quickly, and in large quantities, as soon as the mixing process begins. This gas is a mixture of gases, including Hydrogen Sulphide, which is an extremely poisonous gas. Even a low concentration of hydrogen sulphide can knock out your sense of smell, as a result you won’t even know it’s there. At higher concentrations you will rapidly find it harder to breath and become confused – and at even higher concentrations, JUST ONE BREATH WILL KILL YOU!! 

The slurry mixing code:

  • keep children away from the area at all times when working with slurry
  • if possible, mix on a windy day
  • open all doors
  • take all animals out of the building before starting to mix slurry
  • use outside mixing points first
  • if slats are removed, cover exposed areas of the tank beside the pump/mixer to stop anything falling in
  • start the pump/mixer – then get out and stay out of the building for as long as possible - at least 30 minutes
  • any time you have to go into the building try to make sure that another adult knows what you are doing and can get help if necessary
  • if you have to re-enter to move the pump or change the direction of the pump, leave the building as soon as this is done – do not go back in for as long as possible – at least another 30 minutes


  • rely on filter type facemasks
  • use gas monitors as a substitute for working safely
  • have naked flames near slurry, as slurry gas mixture is flammable
  • stand close to the exhaust of a vacuum tanker when it is being filled

The first 30 minutes are the most dangerous, so it is important for farmers to leave the shed as soon as the mixing starts – AND TO STAY OUT FOR AT LEAST 30 MINUTES!!

If you find someone has been overcome during slurry mixing, if possible, stop the pump and get the person to fresh air but do not put yourself at risk in the process. If breathing is weak or stopped, artificial respiration may be effective. Contact the emergency services and seek immediate medical attention.

For more information about working safely with slurry or general farming health and safety issues please contact the HSENI helpline on: 0800 0320 121 or visit the farm safety topic page on the HSENI website: www.hseni.gov.uk.

NEVER go to assist someone who is in difficulty, without first alerting the emergency services.


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