Intensive farms are polluting Scotland with increasing amounts of ammonia gas that contributes to millions of deaths worldwide, according to figures from the Scottish Environment Protection Agency (Sepa).

The latest available data, collated by The Bureau of Investigative Journalism and passed to The Ferret, showed a spike in ammonia emissions from large scale pig and poultry farms between 2015 and 2017.

Ammonia poses a risk both to the environment and human health, particularly when it combines with vehicle and industrial pollution to form tiny airborne particles.


Farming sites releasing the largest amount of ammonia pollution were owned by the poultry manufacturer Hook 2 Sisters. Two of its operations, in Broxburn and Alloa, were the first and second most polluting sites in Scotland respectively. Another of its sites, at Balado Airport in Kinross took fifth place.

Egg producer Glenrath Farms was the second most prominent ammonia polluter. Its sites in West Linton and Peebles took third and fourth place, while another of its West Linton sites took sixth place.

An Aberdeenshire egg production site by Aberdeen & Northern Eggs – widely known as Farmlay – and a Fife poultry operation run by Noble Foods Limited also featured highly. Others included intensive pig farming sites near Montrose and Stonehaven, operated by John I Forbes and DW Argo respectively.

The increase in ammonia pollution was slammed by the Scottish Greens, who said it can also “cause misery for people living in rural areas”. The National Farmers Union Scotland claimed that ammonia emissions were “significantly below the benchmark 1990 levels”, despite a recent increase.

The Scottish Government promised that its Cleaner Air for Scotland strategy would be “revised and updated by 2020”, with “an increased focus on agricultural emissions”.

Air pollution kills

Agriculture is responsible for almost 90 per cent of ammonia emissions, according to UK government statistics. Ammonia gas, which comes largely from animal faeces and fertilisers, is prevalent on industrial farms due to the large quantities of livestock waste generated.

Sepa describes ammonia as a “colourless, pungent-smelling, caustic (corrosive) gas”. In high concentrations, it can cause “irritation of the eyes, nose and throat as well as burning the skin where there is direct contact”, it says.

Agricultural ammonia has also been found to have a huge impact on air pollution in cities, which can drift from distant farms in rural areas. The gas combines with industrial and vehicle pollution, forming tiny particles that damage the lungs and enter the bloodstream.

This can lead to heart or pulmonary disease, respiratory problems such as aggravation of asthma, and lung cancer.

In 2014, particulate air pollution caused an estimated 600 early deaths in England and Wales, according to an article in Environment International  journal. A 2015 study in the Nature journal estimated that air particles cause at least 3.3 million annual deaths globally.

Experts and campaigners have criticised councils and ministers for failing to do enough to cut air pollution, which is blamed for 2,500 premature deaths every year in Scotland.

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Professor Mark Sutton is an Edinburgh-based environmental physicist for the Centre for Ecology and Hydrology. He has focussed on the environmental impact of ammonia for almost 30 years.

He said that “ammonia reacts in the atmosphere to make particulate matter, which, along with gaseous ammonia, comes down as nitrogen rain – a form of acid rain”. He pointed out that estimates suggested that “agriculture is the single highest contribution to Edinburgh’s particulate matter levels”.

Ammonia itself can also damage vegetation and is very toxic to aquatic organisms, according to Sepa. While acting as a good fertiliser for some plant species, ammonia can damage others, thereby harming wildlife.

Sutton added: “Many of the natural habitats in Scotland have adapted to clean air over millions of years. When you’re near a big farm, you’re able to see the effects of ammonia pollution on vegetation in just a few months”.

However, when new polluting farming activities occur, “you might not see the effects until it’s far too late to do anything about it.”

When you’re near a big farm, you’re able to see the effects of ammonia pollution on vegetation in just a few months. Professor Mark Sutton

In 2017 scientists estimated that a 50 per cent reduction in agricultural ammonia emissions worldwide could prevent an estimated 250,000 early deaths globally each year.

While the release of all other forms of air pollutants have fallen across the UK, ammonia emissions have increased in recent years, a UK government report shows.

However, despite farming causing the majority of ammonia emissions, there is no official government monitoring. All available data are based on modelling and estimates, leaving the full extent of pollution unknown.

The conservation group, Plantlife, called for tougher regulation of ammonia pollution. “We need to know what these emissions are, but more research shouldn’t stop governments taking action now because we already know it’s a massive problem,” said the group’s senior policy officer, Jenny Hawley.

“It comes down to how manure and animal waste is managed on farms and how efficiently that’s being done. Because it’s not regulated, it’s incredibly inefficient at the moment in terms of losses to air and water.”

She argued for “a package of regulations” to govern what farmers must do to prevent pollution. “But they also need advice and support to do that and some help with the one-off capital costs,” she added.

“One of the biggest problems is when there’s very intensive animal housing, such as a big poultry shed with hundreds of thousands of birds, and there isn’t the land for the manure to be used. This kind of factory farming has become very disconnected from the land.”

Hawley thought there ought to be a “more circular” form of farming where the manure from the animals goes back on the land nearby. “The threshold for environmental permits should be much lower,” she said.

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Most farms don’t report ammonia emissions

Only intensive farms are legally required to report estimated ammonia emissions to Sepa under the Pollution Prevention and Control (Scotland) Act. These are sites which have a capacity of more than 40,000 poultry, 2,000 pigs or 700 sows.

Sepa advises farms of this size to make calculations based on “emissions factors”, such as the type and age of livestock, and the type of housing and manure storage.

Most farms are exempt from reporting ammonia emissions, and remain unregulated. Dairy and beef and farms also do not need to report emissions, despite being common across the UK.

A UK government report found that 88 per cent of ammonia pollution was owed to agriculture in 2016. Almost half  came from beef and dairy cattle, while just over a fifth came from pig and poultry farms. Fertiliser application accounted for 23 per cent.

The Department for Environment, Food and Rural Affairs‘ (Defra) Clean Air Strategy, published in January 2019, promised to regulate intensive cattle farms. While the report offers advice on how best farming practices can reduce ammonia, it fell short of committing to financial support to aid new initiatives.

The Scottish Government said they had already adopted several of Defra’s proposals and were “leading the way” as the first country in Europe to adopt the World Health Organisation guideline for fine particulate matter.

A spokesperson said that the Scottish Government’s own clean air strategy included “a series of 40 actions to deliver further improvements to air quality”. This strategy will be “revised and updated by 2020″.

The spokesperson added: “As we have stated previously there will be an increased focus on agricultural emissions as part of this exercise. We will ensure that the views of farmers are taken fully into account.”

Scotland’s top 10 intensive farm ammonia polluters

CompanySiteAmmonia Pollution 2015-17 (Kg)
Hook2Sisters Ltd.Broxburn, West Lothian110,098.00
Hook2Sisters Ltd.Alloa, Clackmannanshire103,422.00
Glenrath Farms Ltd.West Linton, Scottish Borders102,467.00
Glenrath Farms Ltd.Peebles, Scottish Borders84,503.00
Hook2Sisters Ltd.Balado Airfield, Kinross69,496.00
Glenrath Farms Ltd.West Linton, Scottish Borders66,000.00
John I ForbesKinneff, Aberdeenshire65,900.00
Aberdeen & Northern Eggs LimitedStrichen, Aberdeenshire58,123.00
Noble Foods LimitedKinglassie, Fife56,013.00
D W ArgoCatterline, Aberdeenshire54,200.00
source: Scottish Environment Protection Agency.

Between 2015-17, almost 2,200 tonnes of ammonia was estimated to have been released into Scotland’s’ atmosphere by 103 pig and poultry intensive farms. The vast majority of pollution came from intensive poultry farms, which accounted for 76 per cent of ammonia emissions, while the other 24 per cent came from intensive pig farms.

Aberdeenshire operations were responsible for more than a quarter of Scotland’s intensive ammonia farming emissions. Sites in the Scottish Borders accounted for 18 per cent, 12 per cent came from sites in Angus, 11 per cent from Fife, and eight per cent from Perth and Kinross.

High rates of ammonia pollution reflected the number of intensive farms in each region. There were 25 in Aberdeenshire, 13 in the Scottish Borders, 12 each in Fife and Perth and Kinross, and 10 in Angus.

The UK is currently on course to fail to meet UN and EU ammonia emission reduction targets by 2020. Professor Sutton said that while “this ceiling was agreed in 2012, many European countries, including the UK, have failed to take action”.

He highlighted that the current form of muck spreading is one of the biggest causes of ammonia emissions, together with the storage of slurry, and the housing of livestock.

Larger farms “need to get to grips with the best techniques for reducing ammonia pollution, such as lids on slurry tanks and low emission muck spreading techniques”, he said, adding that legislation was required to ensure action.

Tackling ammonia pollution

The Scottish Greens’ environment and farming spokesperson, Mark Ruskell MSP, said that ammonia pollution “can cause misery for people living in rural areas and it’s frustrating to see ammonia emissions increase in the UK while other pollutants are decreasing.”

He highlighted that The Netherlands “have achieved enormous ammonia reductions” and said “we should seek to follow their example here in Scotland.”

Sepa highlighted that it inspects intensive pig and poultry farms to ensure their compliance with environmental regulation. A spokesperson said that they give “clear guidance for farmers on management techniques that will reduce the release of ammonia during livestock housing, manure storage and application of fertiliser to land.”

Sepa added that under Pollution Prevention and Control regulations “the overall reported volume of ammonia decreased by 31.8 per cent between 2007 and 2017, despite an increase in the number of reporting sites.” Annual data on ammonia releases from named individual sites is included in Sepa’s Scottish Pollutant Release Inventory.

It is entirely misleading to make inferences, such as constructing league tables on emissions, when we are the largest poultry farmer in Scotland. Spokesperson, Hook 2 Sisters

National Farmers Union Scotland environment policy manager, Andrew Midgley, said that “farming itself will be a big part of the solution” to reducing emissions. He said that he expected agricultural emissions to be included in the Scottish Government’s revised air quality strategy and “ammonia is likely to be one part of that strategy.”

Midgley added that “although ammonia emissions from agriculture have increased slightly in recent years, it’s important to bear in mind that they remain significantly below the benchmark 1990 levels.”

A Hook 2 Sisters spokesperson stressed that it conducted “continual ammonia modelling risk assessments” at its sites, and took action “to limit any potential impacts”. The company said that Sepa’s latest environmental assessments for its three sites with the highest ammonia emissions were rated either “excellent” or “good”.

The spokesperson added: “It is entirely misleading to make inferences, such as constructing league tables on emissions, when we are the largest poultry farmer in Scotland and would have emissions commensurate to farm size.”

John I Forbes and Glenrath Farms said their views would be reflected in the response from National Farmers Union Scotland. Noble Foods declined to comment, while Aberdeen & Northern Eggs and DW Argo did not respond to requests to comment.

The story was part of a UK-wide collaboration with the The Bureau of Investigative Journalism.

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