FARMERS have warned against “strict” regulations being imposed to curb soaring levels of harmful ammonia after a Government report stressed there has been “a "lack of direct policy focus" from SNP ministers.

Reduction in harmful ammonia, which is linked to cardiovascular and respiratory disease, has stuttered in Scotland – while air pollution from vehicles and industry has been scaled back more successfully over recent years.

The Scottish Government’s updated air quality strategy has warned that “unlike emissions of the other main air pollutants, which have significantly declined over the last 30 years, ammonia levels have decreased by only around 12%”, adding that “even this modest reduction has started to reverse slightly since 2012”.

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The report stressed that "the fact that, almost uniquely amongst the main air pollutants, ammonia levels have not fallen significantly suggests that additional interventions are now required to address issues in the agriculture sector, through awareness raising and supporting farmers and crofters to take up best practice measures".

Agriculture accounts for around 90% of ammonia emissions in Scotland. Ammonia is a nitrogen-based gas which is released when slurries, manures and nitrogen fertilisers come into contact with the air. These chemical reaction products have a longer atmospheric lifetime, are harmful to human health.

Ammonia can contribute to acidification and too much nitrogen in habitats and ultimately reduce biodiversity. The Scottish Government has now pledged to work with Sepa and the agricultural industry to “develop a voluntary code of good agricultural practice” to help improve air quality.

Farmers have appealed that any strict mandatory measures should be ruled out, but have acknowledged that individual farms can take action to make a difference.

NFU Scotland’s environmental resources policy manager, Sarah Cowie, said: “As we tackle the wider issue of emissions, it is clear that farming itself will be a big part of the solution.

“The Scottish Government’s Cleaner Air for Scotland 2 consultation in January looked more closely at all emissions from the sector as part of its air quality strategy. Although ammonia emissions from agriculture have increased slightly in recent years, it is important to bear in mind that they remain significantly below the benchmark 1990 levels.

“One barrier to reducing ammonia as an emission is that it is particularly difficult to measure accurately. In our response to the consultation, we have asked for the way in which ammonia is measured to be revisited as current reference figures may not be representative of the progress being made.”

She added: “What is clear, however, is that ammonia levels can be addressed at farm level. We are looking to Scottish Government to increase awareness of measures that can help to further reduce ammonia emissions, ensuring there is a strong focus on engagement around best practice rather than a strict, regulatory route.

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“On the ground, as technology continues to improve, support for farmers that enables investment in buildings, infrastructure and new equipment will drive reductions in all emissions, including ammonia, by ensuring better fertiliser, slurry and manure application and storage on pig, poultry, beef and dairy units.”

A Scottish Government spokesperson said: “The air that we breathe is fundamental to the health of our people and planet.

“With the publication of our updated clean air strategy, we have recognised the need for greater action on emissions from a range of sectors, including agriculture. That's why we will work with the agriculture sector to develop a voluntary code of good practice for improving air quality and will support farmers in finding new ways of working that reduce harmful emissions.”

A Sepa spokesperson added: “Sepa welcomes action to reduce ammonia and nitrogen emissions to air, including the development of a voluntary code of good agricultural practice for improving air quality and other measures as outlined in ‘Cleaner Air for Scotland 2 – A Better Place for Everyone’, which we will contribute to developing with our partners.

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“Through our sector approach, we work closely and constructively with land managers, consultants, trade associations and researchers to understand how emissions occur and how practices can reduce these.

“We directly regulate emissions from the larger intensive pig and poultry units in Scotland via controls in pollution prevention and control (PPC) permits. Our staff also regularly engage with farmers throughout priority catchment visits and in following up on any pollution incidents reported to us.

“We are keen to see the adoption of low emission and precision technology for land spreading of livestock slurries as well as signing off new storage structures that are suited to the installation of covers. Maximising the value out of the nutrients in livestock manures and slurries by effective controls at source can also be a win-win for land managers and the environment. “