Peatland burns over the reservoir in Langsett, a village in South Yorkshire. Wendy Birks, CC BY-NC-NDEarly one October afternoon in 2023, thick grey smoke drifted across Sheffield’s western skyline. As much of the city became blanketed, residents turned to social media to complain about “bonfire smoke”, while others were forced to leave the city due to breathing difficulties. However, this smoke did not originate within the city. It was drifting in from the Peak District, more than nine miles away, where controlled heather burning was taking place on the moorlands. For around six hours, levels of fine particulate matter (known as PM2.5), tiny airborne pollutants known to harm human health, exceeded 40 micrograms per cubic metre of air (µg/m³) and peaked at 70µg/m³, well above the guidelines recommended by the World Health Organization.This single incident points to the wider and largely invisible problem of the routine burning of the UK’s uplands. This can be a serious source of air pollution, but because most official air pollution monitoring concentrates on urban areas, the effects are overlooked. This is why we have started monitoring upland fires and the pollution they cause. Prescribed burning is a longstanding land management practice often used to control vegetation for grouse shooting or livestock grazing. It happens across a range of upland landscapes. Many of the areas being burned sit on deep peat, an organic-rich soil made from layers of slowly decomposed plant material formed over thousands of years in waterlogged conditions. Peatlands are incredibly important. They are one of the most carbon-rich ecosystems on the planet. In the UK, they cover around 12% of the land area and store an estimated 3.2 billion tonnes of carbon. This is equivalent to all the forests of Germany, France and the UK combined. Most of the UK’s peat is found in Scotland, but notable areas in England include the Peak District and North York Moors. However, their value goes well beyond carbon. Around 70% of Britain’s drinking water comes from upland areas that are largely peatland, and healthy peatlands help reduce flooding by slowing the flow of water from hills to towns and cities. They also provide vital habitats for birds, insects and rare plants, forming the UK’s largest area of semi-natural habitat. Read more: Wildfire smoke can harm human health, even when the fire is burning hundreds of miles away – a toxicologist explains why Despite their ecological importance, more than 80% of English peatlands are classified as degraded, often through historic air pollution, draining, overgrazing and, importantly, repeated burning. One hidden consequence of that burning is air pollution. These burns are often viewed as isolated rural events, but their effect on regional air quality can be substantial. On that day in Sheffield, pollution levels briefly rivalled those seen across the city during bonfire night, a well-known peak in urban air pollution.In response to that October event, our research team launched a new pilot monitoring network across part of the Peak District national park. This FireUp project combines air quality sensors, satellite data and community observations to detect and measure pollution from upland fires. Planned burning event in the Peak District captured via Copernicus Sentinel-2 data (2024), retrieved from Copernicus SciHub and processed by European Space Agency. CC BY By using a mix of technologies and local reporting, we have documented spikes in PM2.5 pollution that would have otherwise been missed. Our system offers a clearer picture of when and where fires occur, and how far their smoke spreads, opening the door for better planning and stronger protections for public health. But the problem is not just a lack of data, it is also a failure of regulation. England’s current upland burning regulations are limited on four fronts.Heather and grass burning regulations introduced in 2021 prohibit burning only on peat deeper than 40cm inside designated sites. That means 60% of upland peat is excluded from these protections. With more than 95% of PM2.5 monitors located in urban areas, smoke from moorland fires in remote rural locations is rarely registered on official networks. The resources for organisations responsible for enforcing regulations have shrunk over the last decade. Natural England, one of the government’s statutory bodies responsible for environmental protection, has experienced a 4% decrease in funding for 2024-25 compared to the previous year.Prosecutions for illegal burning are exceptionally rare, with satellite analyses pointing to a higher level of unlicensed activity than official records suggest. In short, narrow legal scope, limited monitoring coverage and under-resourced enforcement leave many prescribed burns undetected and unaccounted for, along with the health and environmental risks they carry. Our FireUp system improves fire detections and helps quantify the effects of air pollution from these burns. As the UK government reviews regulations as part of the 2025 heather and grass burning consultation for England, and as upland fire risk increases, this kind of evidence is essential, not just to track what is happening, but to help shape a healthier and better future for the UK’s uplands. Our next step is to develop a citizen science app that makes it easier for people to report peatland fire incidents and upland burning to help improve regulation and log the effects of changes in air quality. Don’t have time to read about climate change as much as you’d like?Get a weekly roundup in your inbox instead. Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 45,000+ readers who’ve subscribed so far.James is a member of the Welsh Government Clean Air Advisory Panel, and Promoting Awareness of Air Quality Delivery Group. James also sits on the Scottish Government's Air Quality Advisory Group.Maria Val Martin receives funding from UKRI and is a member of the DEFRA Air Quality Expert Group. Rebecca Brownlow does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.