Research Uncovers Hidden Dangers of Smokeless Fuels
New findings indicate that substituting one solid fuel for another may not effectively combat air pollution, as so-called 'smokeless' or low-smoke fuels introduce new hazards. These fuels, sold as alternatives to traditional coal, wood, and peat for home use, have been discovered to emit large quantities of ultrafine particles during combustion. These particles are smaller than the wavelength of light and can penetrate deep into human lungs, posing significant health risks.
Accidental Discovery in Fuel Testing
The revelation emerged unexpectedly during tests on fuels in both traditional and modern eco-design stoves. While burning alternative fuels, such as smokeless coal ovoids and briquettes made from olive stones, resulted in less overall particle pollution compared to wood or coal, researchers were surprised by a sharp increase in ultrafine particles. Professor Jurgita Ovadnevaite from the University of Galway noted, "No one had considered that reduced smoke could coincide with a rise in ultrafine particles. We didn't anticipate such a pronounced effect until we examined the data."
Dr Chunshui Lin, also at Galway, highlighted the rigorous testing process: "It took nearly two months of daily sample burning to ensure data quality and consistency." The study found that for each kilogram burned, low-smoke fuels produced two to three times more ultrafine particles than wood or coal.
Impact on Outdoor Air Quality
Motivated by these laboratory results, researchers revisited past measurements from Dublin and the town of Birr in the Irish Midlands. They detected ultrafine particles in winter evenings, linked to home fires, at concentrations far exceeding expectations—sometimes surpassing levels in cities like Beijing and Shanghai. In Dublin, ultrafine particle levels increased from 2021 onwards, correlating with a shift towards low-smoke fuels in households.
Ovadnevaite emphasized the importance of ongoing monitoring: "Without sustained measurements, evaluating these consequences would have been impossible." The tiny size of these particles allows them to lodge deep in the lungs, amplifying health impacts. In Dublin, low-smoke fuels accounted for over half of the ultrafine particles that can deposit in lungs, including poly-aromatic hydrocarbons, some of which are known carcinogens.
Regulatory Context and Health Implications
While house coal sales were phased out in England from 2020 and in Ireland from 2022, low-smoke fuels remain legally available. In the UK, these are the only fuels permitted for open fires in smoke control areas covering most major cities. Measurements from Imperial College London's research supersite in south London show peak concentrations of ultrafine particles during evenings, prompting calls for further investigation.
Historical data shows that banning smoky coals in Dublin in 1990 led to a 17% decrease in deaths from breathing problems the following winter. However, the new study suggests that simply switching solid fuels may not be an optimal solution for air pollution. Ovadnevaite advocates for a holistic approach: "We need to account for the full range of effects. Before lighting a fire, consider the health costs for children, older relatives, and neighbours. Every fire adds to that burden."
This research underscores the complexity of air pollution management and the need for comprehensive strategies beyond fuel substitution.
