An air pollution study, led by researchers at NUI Galway’s School of Physics and Ryan Institute’s Centre for Climate and Air Pollution Studies have found that Dublin’s PM2.5 air pollution (Particulate Matter airborne smog, smoke and haze particles smaller in size than 2.5 microns) can surpass the World Health Organisation’s recommended 24-hour Air Quality Guideline.
Breached every one in five days
Over the two-month winter period, from late November 2016 to late January 2017, the daily Average Quality Guideline (AQG) was breached every one in five days and during the main emission period of these events (late evening), hourly levels were frequently 10 times higher than the 24-hour AQG threshold (25 µg m-3).
The Average Quality Guideline is more-strict than current regulatory levels but is not to be regarded as a safe level since adverse health impacts can still occur well below the AQG threshold. This research, which was funded by the Environmental Protection Agency Research Programme 2014-2020, was published recently in the international journal, 'Nature Sustainability'.
The research team, led by NUI Galway’s Dr Jurgita Ovadnevaite, deployed a pilot air pollution network (AEROSOURCE), comprising highly sophisticated, next-generation air pollution fingerprinting technology, with the capability of identifying specific sources of even the smallest amounts of air pollution.
AEROSOURCE, the first national network of its kind, attributed 70% of the extraordinarily-high pollution levels during these events to peat and wood burning, despite only a small percentage of residential homes using peat or wood as a primary fuel type (13 per cent based on the closest census data).
All of the exceedance levels were driven by peat and wood rather than coal or oil
Irrespective of the different timescales of these events and census data, all of the exceedance levels were driven by peat and wood rather than coal or oil, or even non-residential sources such as traffic. The contribution from coal use is strikingly low and highlights the success of the Smoky Coal Ban which was first introduced in Dublin in 1990 and has since been introduced in many towns and cities across the country.
Like most severe air pollution events, they are associated with cold and generally stagnant winter days when fuel consumption is high and dispersion is low. However, the study found these exceedance levels are driven by solid fuels, some of which are marketed as more ‘climate-friendly’ than fossil-fuels.
The climate policy shift from fossil fuels to ‘low-carbon’ or ‘carbon-neutral’ fuels is aimed at mitigating the atmospheric accumulation of greenhouse gases responsible for driving global warming, but in terms of residential heating, this shift is often towards wood (including pellets), considered as ‘low-carbon’ or ‘carbon-neutral’ biomass fuels and other solid fuels, which can lead to disproportionately poor air quality. That is to say, what is considered climate-friendly is not necessarily environmentally friendly across the board.
Disproportionate sensitivity of air pollution levels to solid fuel
Professor Colin O’Dowd, director of NUI Galway’s Centre for Climate and Air Pollution Studies, said: “The disproportionate sensitivity of air pollution levels to solid fuel, including climate-friendly ‘low-carbon’ solid biomass fuel, is quite concerning since fuels like wood are one of the most popular choices of ‘low carbon’ biomass fuel and consumption of this fuel type is set to double across Europe by 2020 (from 2016), and to triple globally by 2030.
"The results from this study suggest that along with promoting low-carbon or carbon-neutral solid fuels, it is especially important to fully consider the health impact from any associated air pollution emission.
“The EU is currently conducting a major review of its Clean Air for Europe directive with a view to delivering on the aim of its 7th Environment Action Program to adopt World Health Organisation air quality values by 2020.
"It is important that this innovative research, which highlights the disproportionate impact of solid fuels on air quality, is fully considered in developing future EU legislative and regulatory frameworks to protect public health and the environment.
"The smoky coal ban did its job where it was applied and the nationwide extension in 2019 will be of further benefit but we need to remain vigilant and consolidate those victories by developing policies that continue to reduce air pollution and improve public health.
Considering the wider impacts of climate policy to avoid negative health impacts
“These striking results also illustrate the importance of considering the wider impacts of climate policy to avoid negative health impacts, as occurred with diesel vehicles, and ensure positive co-benefits and win-win outcomes, so that actions to mitigate against climate change benefit air quality and vice versa.”
The study, comprising an international team from NUI Galway, University College Cork, Italian CNR-ISAC in Bologna and the Chinese Academy of Science in Xi’an was funded by the Irish Environmental Protection Agency, Science Foundation Ireland-MaREI Centre and the Chinese Academy of Science.
To read the full study entitled ‘Extreme Air Pollution from Residential Solid Fuel Burning’ in Nature Sustainability, visit:
https://www.nature.com/natsustain/