Evaluation of the effects of PM2.5 due to domestic solid fuel burning on health outcomes in Scotland
This study assesses the potential health benefits of further policy actions affecting domestic solid fuel burning in Scotland. Three options were taken forward for more detailed modelling: Burn less; Burn better; and Targeted stock upgrades.
1 Introduction
The detrimental impacts on health associated with exposure to air pollution are well documented. Fine particulate matter (or PM2.5) can penetrate deep into the lungs and bloodstream, causing severe health issues. There is substantial evidence[1] linking long-term and short-term PM2.5 exposure to mortality and morbidity through a range of respiratory and cardiovascular diseases, including for long-term exposure: childhood asthma, chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), stroke and hypertension[2]. The International Agency for Research on Cancer (IARC) has classified outdoor air pollution, specifically particulate matter, as a Group 1 carcinogen, meaning there is sufficient evidence that it causes lung cancer[3]. A recent report from the Committee on the Medical Effects of Air Pollution (COMEAP) confirmed an association between chronic exposure to air pollution (most likely fine particles) and cognitive decline and dementia[4]. UKHSA[5] have estimated that 1,800 to 2,700 deaths per year in Scotland are attributable to exposure to outdoor air pollution (based on long-term average concentrations of PM2.5 and NO2).
According to the UK’s National Atmospheric Emissions Inventory (NAEI), small combustion was the largest source of PM2.5 emissions which accounted for 25% of total UK PM2.5 emissions in 2024[6] (small combustion includes fuel combustion in the residential, commercial and public sectors as well as in agriculture). The residential burning of wood accounted for over 40% of the PM2.5 emission from small combustion, and about 11% of total UK PM2.5 emissions in 2024. In addition to fine particles, biomass emissions contain both coarse (e.g. PM10) and ultrafine (size less than 0.1 microns) particles, carbon monoxide, nitrogen dioxide, and a number of volatile and semi-volatile organic species, with the specific composition depending on the type of fuel burned[7] [8]. As a result, solid fuel burning leads to complex mixtures of airborne particles and irritant gases that reduce both indoor and ambient outdoor air quality. Some of the gases emitted from domestic combustion are precursors for the formation of inorganic and organic secondary PM2.5 components. Furthermore, it seems that burning of domestic solid fuels shows no sign of slowing down: the Stove Industry Association reported that 200,000 stoves were sold in 2022[9]. A Defra sponsored survey[10] published in 2024 reported that: overall burning prevalence (including indoor and outdoor) rose in all UK nations, but most sharply in Scotland (7 percentage points from 14.9% to 22.2%) from the previous survey reported in 2020; and that 11.3% of homes in Scotland regularly burned indoors, which had increased from 6.8% in the previous survey.
The Cleaner Air for Scotland 2 (CAFS2) strategy defined a range of actions aimed at domestic solid fuel burning to improve health. These included a proposed ban on the sale of house coal and certain highly polluting manufactured solid fuels (MSF), improving emissions standards for stoves, as well as recognising the importance of education for consumers. Air Quality Consultants (part of Logika Group, referred to as AQC/Logika), together with the UK Centre for Ecology & Hydrology (UKCEH) have been commissioned by the Scottish Government to undertake this study, which assesses the potential health benefits of further policy actions affecting domestic solid fuel burning in Scotland.
This study focuses on contributions to ambient PM2.5 pollution and associated health effects, hence does not capture impacts associated with other pollutants nor exposure inside the home (however the body of evidence on the relevant health effects from indoor pollution is growing and is a recognised risk[11]). This work follows on from (and makes use of) a preceding study by UKCEH on ‘The contribution of indoor domestic solid fuel burning to Scotland’s air pollution’ (referred to from here as ‘UKCEH (2025)’) which sought to better understand the contribution of domestic burning to PM2.5 emissions in Scotland.
Within this report:
- Section 2 sets the context, presenting evidence around patterns of burning, its contribution to air pollution and a review of associated health risks.
- Section 3 presents a quantification of the baseline health burden associated with domestic solid fuel burning in Scotland.
- Section 4 then presents analysis of spatial and demographic trends in exposure.
- Section 5 presents an initial long-list of policy options and screening against several criteria to define a short-list for more detailed assessment.
- Section 6 describes the modelled impacts of the policy options on air quality.
- Section 7 sets out the health and distributional impacts of the policy options.
- Section 8 concludes with a summary and conclusions drawn from the analysis.
- Several Appendices present detailed results.