Moorland burning exposes millions to unsafe air pollution
Managed burning on moorland in the UK led to millions of people being exposed to unsafe levels of fine particulate pollution, according to research led by the University of Leeds and the RSPB.
The study shows that on average more than half a million additional people were exposed, with peak exposure affecting up to 2.3 million people.
Our results show that prescribed burning can increase PM2.5 concentrations across much larger regions impacting towns and cities across northern England and Scotland.
During the months analysed, primary emissions of PM2.5 (particulate matter smaller than 2.5 micrometres in diameter) were equivalent to one third of that from road transport with PM2.5 exposure highest in Northern England, North Scotland and East Scotland. The deliberate burns, which were largely carried out to support recreational shooting, led to almost one in five people in affected areas being exposed to unsafe levels of pollution on at least one day in the burning season.
The research is published today (Tuesday 19 May) in the journal Environmental Research Letters.
Lead author, Dr Ailish Graham from Leeds’ School of Earth, Environment and Sustainability, said: “Until now, prescribed moorland burning has been seen as a local air quality issue. Our results show that it can increase PM2.5 concentrations across much larger regions, impacting towns and cities across northern England and Scotland.
“On days burning occurs, millions of people are exposed to increased pollution with PM2.5 concentrations exceeding World Health Organization air quality guidelines.”
Moorland burning is widely used to maintain a mosaic of heather-dominated moorland for red grouse but the practice releases small particles of pollution in the smoke, known as PM2.5.
Increased risks
These particles are tiny, smaller than the diameter of a human hair, and so they can travel far from their source into nearby towns and cities. Since they are so small, they can be inhaled deep into our lungs, which causes inflammation and increased risk of heart and health problems in people repeatedly exposed to unsafe levels. Even short-term exposure to particulate matter can cause increased risks for heart and lung health.
Scientists estimated the daily emissions of PM2.5 from moorland burning from 2017-2022, covering mostly prescribed burning, with a very small contribution from wildfires (<5%). They then modelled how emissions from these burns would spread due to weather and atmospheric conditions.
They found that between 2017/18 and 2021/22, moorland burning generated 1,300 tonnes of particulate matter per year, around 1.5% of the total British human caused primary PM2.5 emissions. The areas where PM2.5 emissions were highest were Yorkshire and Humber, North East England, East Scotland and North Scotland.
They then identified the impacts specifically attributable to prescribed burning by focussing on a period where wildfires accounted for less than 5% of the area burned (Oct 2017- Apr 2018). They combined satellite data and a regional air quality model to estimate the impacts of prescribed burning on air pollution and to calculate the regions of the UK where people were exposed to the pollution.
On days where prescribed burning occurred, an average additional 0.55 million people were exposed to PM2.5 levels above the World Health Organization (WHO) recommended limit. Across the whole period, an estimated 2.3 million people were exposed to PM2.5 concentrations above the threshold due to prescribed moorland burning. This is almost 1 in 5 people in the affected regions (19%).
Managed moorland
To create ideal conditions for red grouse, land managers can use prescribed burning as a means of forming mosaics of heather of different ages and structures, which collectively are on such a large scale that they are visible from space. Managed moorland covers 8,550 km2, equivalent to the size of North Yorkshire.
This burning often occurs on internationally important peatland habitat, leading to the loss of stored carbon into the atmosphere, water pollution and increased flood risk, as well as the loss and degradation of habitats for wildlife.
Tom Aspinall, Uplands Senior Policy Officer at RSPB, said: “The environmental impacts that burning has on our precious upland peatland habitats are well-documented and can lead to the devastation of peatland landscapes which are vital both for wildlife and carbon storage. This new research reinforces the need to restrict peatland burning and take steps to restore our uplands.
“This is one of the reasons why we’re calling on the UK Government to introduce a system of licensing to regulate grouse moor management practices across England in line with recent legislative changes in Scotland.
“Across much of Europe licensing is already in place, and evidence shows that shoots successfully operate whilst being properly regulated and environmentally sustainable. We believe this is a sensible and proportionate way to bring about the change required to allow upland landscapes to flourish and deliver their potential for nature and people.”
Dr Graham added: “Moorland managers need to consider the air quality impacts of prescribed burning and seek alternative approaches where possible.”
Further information
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