Slurry gas – one breath can kill

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With the closed period for spreading slurry coming to an end on 31 January, the Health and Safety Executive for Northern Ireland (HSENI) is urging farmers to take extra care when working with slurry.

The call comes as part of a new slurry awareness drive which features a new leaflet warning of the dangers from slurry gas and offering advice on how to mix slurry safely.

HSENI inspectors have also started a series of visits to local farms to offer advice and information to improve working systems.

Slurry gas is a mixture of gases, including the extremely poisonous hydrogen sulphide. Even a low concentration of hydrogen sulphide can knock out your sense of smell so you won’t even know it’s there. At higher concentrations you will rapidly find it harder to breathe and become confused – and at certain concentrations, just one breath can kill.

Over recent years, incidents involving slurry have tragically claimed the lives of a number of people in Northern Ireland, including that of a child.

Mixing slurry can be a particularly dangerous job as the gas is released very quickly, and in large quantities, as soon as the mixing starts.

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.

Appealing to farmers to follow the advice on offer, Malcolm Downey, who heads up the farm safety team at HSENI, said: “Before mixing slurry, always stop and think about the job ahead and plan to do it safely.

“Cover all the openings and keep children and animals well away during the mixing process – and stay out of the building for at least 30 minutes after the mixing starts and every time you move the pump or change the direction of mixing.

“Don’t take any chances - you may have got away with it in the past, but you are risking your own life and the lives of others as well as putting your livestock in danger.

“Always follow the slurry mixing code and remember that with slurry gas, just one breath can kill.”

Follow the slurry mixing code to stay out of trouble:

l keep children away from the area at all times when working with slurry

l If possible, mix on a windy day

l open all doors and windows

l take all animals out of the building before starting to mix slurry

l use outside mixing points first

l if slats are removed, cover exposed areas of the tank beside the pump/mixer to stop anything falling in

l start the pump/mixer – then get out and stay out of the building for as long as possible - at least 30 minutes

l 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

l 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


l rely on filter type facemasks

l use gas monitors as a substitute for working safely

l have naked flames near slurry, as slurry gas mixture is flammable

l stand close to the exhaust of a vacuum tanker when it is being filled

HSENI has produced a new slurry mixing safety leaflet ‘Slurry Gas – Mixing Slurry Safely’, which can also be downloaded at the following link:

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: