In the Republic of Ireland, over 40 million tonnes of slurry are stored, handled and spread each year. Working with slurry is a particularly hazardous activity. The two risks when working with slurry are the risk of drowning in slurry tanks and the risk of asphyxiation by toxic gases released from slurry in storage.

Drowning in slurry and water, and asphyxiation (gas poisoning), caused 14% of farm deaths between 2000 and 2009. Drowning is by far the most common cause of death involving slurry. Children and the elderly are at particular risk.

In the period 2000-2010, 30% of child fatal accidents on farms were caused by drowning in slurry or water. In the same period 8% of deaths to elderly farmers were caused by drowning. Toxic gases are released during the bacterial decomposition of slurry in tanks. Inhaling these gases which include hydrogen sulphide, ammonia, methane and carbon dioxide can be lethal.

Some, like methane, are flammable. One in particular, hydrogen sulphide, is poisonous. All these gases are heavier than air, so they displace oxygen. This can lead to suffocation when a person enters a tank.

Hydrogen sulphide is extremely poisonous both to people and animals. It affects the nervous system and small concentrations can cause death. There have been many incidents in which people were overcome by slurry gases. Several people have been killed.

Smell is no indicator of the absence of gas, as many gases are odourless. Hydrogen sulphide has a ‘rotten egg’ smell at low levels, but cannot be smelt at higher levels. High levels can be released when slurry is agitated. One breath or lung-full at this level causes instant death.

The highest risk is when slurry is being agitated. The gases are trapped in the slurry and are released when it is mixed. Studies indicate that levels are greatest shortly after mixing commences in the tank, when slurry is stored for several months, when slurry is mixed in deep tanks, after silage effluent is added and when slurry is mixed in cold weather.

• Open slurry tanks should be protected by an unclimbable fence or wall at least 1.8 metres high, with locked gates. When the tank has to be emptied, consider having an adequately constructed access platform with safety rails
• Covered or slatted tanks require access manholes that children cannot open easily. Fit a safety grid below the manhole to give secondary protection. All slurry tanks should be adequately fenced
• Evacuate all livestock and make sure no person or animal is in or near the building. Do not allow slurry to rise within 300mm of the slats or tank covers. It is essential to avoid smoking and naked flames as the gas mixture can be highly flammable
• Never enter a tank for any reason - gases can build up and remain in partially emptied tanks above the slurry
• Never enter the slurry tank or any confined space unless you are wearing suitable breathing apparatus and/ or a harness attached to a lifeline controlled by at least two other adults positioned outside of the area
• Put up warning signs to warn of the dangers when working with slurry. Remember that scrape holes on outdoor lagoons should be adequately protected
• Cover all slurry tank manhole openings and beware of the risk of back injury if you need to lift slats in the shed. Agricultural contractors must be aware of the dangers of working with slurry and should ensure that they work safely at all times
• Use outdoor agitation points where possible - one lung-full of slurry gas can kill. Only agitate where there is good air movement .Evacuate and ventilate before you agitate, open all doors and outlets to provide a draught
• Avoid vigorous agitation in confined spaces and at least two people should be present and should stand up-wind
• Keep all people away from the agitation point for 30 minutes after starting agitation. In particular keep children and elderly persons away from the area when agitating. One should never stand over slats or near tank access points when agitation is in progress. Guard the PTO on the slurry tanker and agitator– do not use unless correctly guarded. As we know a high proportion of PTO entanglements occur when using slurry tankers
• There are now easy to use and affordable equipment to make slurry operations much safer. For example the Protege ZM hydrogen sulphide gas detection equipment is simple to use. It is easy-to-use, needs zero-maintenance with one-button activation, adjustable alarm settings and an easy-to-read display. The personal gas detection monitor is designed for monitoring the atmosphere for potentially hazardous levels of gases such as Hydrogen Sulphide (H2S), Carbon Monoxide (CO) and Oxygen (O2) enrichment or depletion.