New Research Reveals Hidden Air Pollution from Smokeless Fuels
Recent research indicates that burning "smokeless" or low-smoke fuels may introduce new air pollution hazards both outdoors and indoors. These fuels, marketed as alternatives to coal, wood, and peat for home heating, have been found to emit large quantities of ultrafine particles—smaller than the wavelength of light—that can penetrate deeply into the lungs, posing significant health risks.
Discovery of Ultrafine Particles During Fuel Testing
The presence of ultrafine particles was an unexpected finding during tests of various fuels in both traditional and modern eco-design stoves. While alternative fuels such as smokeless coal ovoids and briquettes made from olive stones produced less visible smoke and overall particle pollution compared to wood or coal, they emitted substantially more ultrafine particles.
Dr Agnieszka Ovadnevaite, from the University of Galway, stated: "No one had taken the next step to consider that less smoke could simultaneously lead to an increase in ultrafine particles. We hadn’t anticipated such a pronounced effect either until we saw the data."
Dr Chunshui Lin, also at Galway, added:
"It took us nearly two months with sample burning almost every single day to ensure data quality and consistency."
Quantifying Ultrafine Particle Emissions
For every kilogram of fuel burned, low-smoke fuels produced between two and three times more ultrafine particles than wood or coal. This unexpected result prompted the researchers to revisit and re-analyze their previous outdoor air quality measurements to assess the contribution of these particles to local pollution.
Field Measurements in Ireland Confirm Laboratory Findings
The team examined past data from Dublin and the small town of Birr in the Irish Midlands. They observed elevated levels of ultrafine particles during winter evenings, consistent with emissions from home fires but at concentrations significantly higher than anticipated. In some instances, these levels surpassed those recorded in major cities such as Beijing and Shanghai. In Dublin, the concentration of ultrafine particles increased starting in 2021, coinciding with a shift in households toward low-smoke fuels, aligning with laboratory observations.
Ovadnevaite noted: "Without sustained measurements, it would have been impossible to evaluate these consequences."
Health Implications of Ultrafine Particles
The extremely small size of these ultrafine particles allows them to deposit deep within the lungs, amplifying their health impact. In Dublin, low-smoke fuels accounted for more than half of the ultrafine particles capable of lung deposition. These particles include poly-aromatic hydrocarbons, some of which are recognized carcinogens.
Regulatory Context and Ongoing Challenges
While the sale of house coal was phased out in Ireland and Northern Ireland, low-smoke fuels remain available. In the UK, these fuels are the only ones legally permitted for use in smoke control areas.
Measurements from Imperial College London’s urban air quality monitoring indicate that these ultrafine particle concentrations are among the highest recorded, warranting further investigation.
The 1990 ban on smoky coals in Dublin was credited with saving lives and was followed by a significant reduction in winter mortality. However, the new findings suggest that replacing one solid fuel with another low-smoke alternative may not effectively resolve air pollution issues.
Ovadnevaite emphasized: "We need a more holistic approach to air pollution – one that accounts for the full range of effects. So before lighting a fire, it’s worth pausing to think. Are we prepared to accept those health costs for our children, our older relatives, and our neighbours? Every fire adds to that burden."
