Preventing Deaths with Slurry
The Slurry Spreading season commences in many parts of the Country after the 12th January. With 10% of deaths being slurry-related in the 10 year period to 2020, John McNamara and Francis Bligh, Teagasc Health and Safety Specialists discuss the dangers and prevention of deaths with slurry
Over the 10 year period to 2020, 10% of deaths have been slurry-related, however it may be the case that there is confusion in farmers’ minds about the specific causes of slurry-related farm deaths.
Slurry deaths can arise from drowning or gassing. It can be difficult to determine which is the cause, but it is vital to put measures in place to protect against either cause.
From our experience farmers think that ‘gassing’ is the majority issue and it comes as a surprise that ‘drowning’ is such a frequent occurrence.
Farmers are busy when working around an agitator and it is possible to lose concentration and ‘step-back’ into a slurry tank. As slurry is a viscous liquid with 6-8% solids it is not easy for a person to escape from this situation. Also the slurry agitator is running in the same vicinity and the possibility of entanglement arises.
The safety message from this scenario should be clear, prevention is the issue, have safety grids and barriers installed to prevent falling into slurry and maintain high vigilance when placing slurry agitators into position. Both older farmers and children have been the victims of slurry drowning which reinforces the message of keeping slurry tanks and pits securely covered or fenced.
A H.S.A video focusing on the danger of drowning when agitating slurry can be viewed by clicking the following link https://youtu.be/1pIwb7wMOrU
Slurry produces a range of gases based on the nature of the fermentation which occurs. Poisoning occurs ‘above ground’ due to the release of Hydrogen Sulphide ( H2S) which is more poisonous than Hydrogen Cyanide which was used as a poison gas in World War1. H2S can be detected by smelling at 0.1 ppm but a 150 ppm the olfactory nerve which detects smell in the nose is desensitised and it then cannot be detected by smell.
The gas produces adverse health effects at increasing concentration and is rapidly fatal above 700ppm. Teagasc measurements have indicated that fatal levels of gas levels can occur in the period after agitation commences.
Teagasc and the H.S.A have jointly produced a safety leaflet on preventing death with slurry which is available at https://www.teagasc.ie/rural-economy/farm-management/farm-health--safety/ with further information on Safety with Slurry available at http://www.hsa.ie in the Agriculture section at the Slurry page. Embedded in the H.S.A webpage is a video titled Dangers of Slurry Gas - Just One Breath Will Kill. You can view this video by clicking the following link https://youtu.be/VGCo5h6D-gA
The key controls related to slurry gassing are:
- to pick a windy day when there is a lot of air movement and
- to stay away from the agitation point for the first 30 minutes after agitation commences.
It is important to realise that poisoning can occur either outdoors or indoors in calm condition.
A wind speed of at least Beaufort Scale 2 where wind ‘is felt on exposed skin and leaves rustle’ and has a speed of 7 Km per hour or higher is required. This rapidly dissipates the poisonous gas. With sheds, ensure that all doors and vents are opened and that there is adequate air movement and ensure that persons particularly children or older persons do not enter during/after agitation.
Installing a slurry aeration system is an alternative to handling and mixing slurry indoors.
See video below focusing on Best practice in Safe Slurry Agitation
Slurry gas meters
The H.S.A /Teagasc guidance does not recommend the use of gas detection systems by farmers. These meters typically are set to alarm at 10ppm which is the Occupational Exposure Limit Value (OELV) for a 15 minute exposure under the Code of Practice for the Safety, Health and Welfare (Chemical Agents) Regulations. This is considered to be the maximum exposure that will not cause a health issue.
The problem is that with the potentially high level of H2S emissions from slurry (over 1000ppm) that a fatality could occur in an instant. The best advice is that gas detection systems can only be used safely along with full breathing apparatus and should not be used as a substitute for the safety guidelines outlined in the H.S.A. Teagasc Slurry handling guidance.
Never enter a tank
Entering a slurry tank or any tank with organic material in it can be lethal and is not advised. Doing this work is covered by Confined Space entry regulations and a Code of Practice giving guidance on these regulations is available on the H.S.A. website.
The potential problem with entering a slurry tank is that gas such as H2S, methane, carbon dioxide or ammonia may be present. In addition to the poisonous nature of some of these gases, they deplete oxygen levels which cause asphyxiation and instant death. Rescue is not possible and multiple fatalities have occurred when this has been attempted. So not entering a tank is the key prevention measure.
The farmer has little need to enter a tank and when the need arises it is best to hire persons or firms with the requisite training and equipment.
Further Information on Slurry Safety
Further Information on safety with slurry is available from the H.S.A. website www.hsa.ie and the Teagasc website: https://www.teagasc.ie/rural-economy/farm-management/farm-health--safety/ In particular, a video series on the dangers of slurry can be viewed on The H.S.A. and Teagasc YouTube channels.