UFU warns of dangers of slurry mixing in hot weather

The Ulster Farmer’s Union (UFU) has cautioned farmers to take care when mixing slurry in hot weather, as slurry-related incidents account for one in four farming deaths in Northern Ireland.

Stored slurry contains several harmful gasses – namely methane, carbon dioxide, ammonia, and, most dangerous of all, hydrogen sulphide. These gases are created by bacteria as the slurry decomposes.

UFU deputy president William Irvine said: “Mixing slurry is an extremely dangerous job, but even more so when temperatures are high like we have been experiencing this past week.

See also: Top tips for how to take on dangerous job of mixing slurry

“Slurry gas contains poisonous hydrogen sulphide and releases very quickly in large volumes when mixing begins.

“This is why slurry should only be mixed when doors and windows are open and when there are high winds so fumes can be dispersed in the air.”

Leave the building

The UFU recommends that housed animals are moved and farmers leave the shed before mixing starts, as the first 30 minutes provide the most dangerous exposure to fumes.

“Farmers should leave the shed as soon as mixing begins and stay out during the entire process. If you have to go into the building during mixing for an essential reason, it is vital that famers inform a family member or an adult when they are working with slurry to ensure help is close at hand if needed,” said Mr Irvine.

Gas concentration is measured in parts per million (ppm) in the atmosphere, and levels from 20-200ppm can cause symptoms such as irritation of the eyes and respiratory tract, along with dizziness and headaches.

Frequently, gas levels in cow sheds during slurry mixing can be in excess of 500ppm – levels that can cause disorientation, collapse, and death.

Stephanie Berkeley, the manager of the Farm Safety Foundation (Yellow Wellies), said: “Last year a self-employed worker died when he came into contact with slurry gas. Unfortunately, this kind of incident is all too common on our farms.

“There have been several high-profile incidents involving slurry over the past 10 years and, for an industry where this work is unavoidable, we have a responsibility to familiarise ourselves with the process of working with gasses that can have devastating consequences.”

The Stop and Think checklist

The Health and Safety Executive for Northern Ireland has issued a comprehensive list of safety advice for farmers mixing and handling slurry:


  • Assume hazardous gas is present during mixing
  • Keep all unnecessary openings to slurry tanks covered


  • Rely on filter-type facemasks
  • Use gas monitors/meters as a substitute for a safe method of working
  • Rely on meters at the start of mixing
  • Have naked flames near slurry, as slurry gas mixture is flammable
  • Stand close to the pump/exhaust of a vacuum tanker when it is being filled

Always follow the safe system of work outlined below to stay out of trouble:

  • If possible, mix on a windy day
  • Keep children away from the area at all times 
  • Take all animals out of the building before starting to mix slurry
  • Open all doors and windows
  • 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 and then stay out of the building for as long as possible (at least 30 minutes)
  • If you have to go into the building, make sure that another adult stays outside and can get help if needed
  • If you have to re-enter to move 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)