AIR POLLUTION HAS been in the news a lot over the last few months as large reductions in air pollution have been observed around the world during Covid-19 lockdowns.

These improvements in air quality bring considerable benefits for health and the environment. However, as the restrictions are lifted, there are early signs that traffic-related pollution levels are on the rise again.

Furthermore, emissions from other sources, such as home heating, have not been reduced at all. As we build for a healthy recovery from this global pandemic, it is vitally important that we keep air pollution under control.

Air pollution is a silent, sometimes invisible, killer made up of a complex chemical mixture of gases and particles that impact strongly on both climate and health.

While gases such as carbon monoxide and ozone are hazardous at certain concentrations, the main health hazard is airborne particulate matter with a diameter of less than 2.5 micrometers, also called PM 2.5. There is no safe level of exposure to these microscopic particles and, as a result, PM 2.5 is regulated across the world.

• (Read more here on how you can support a major Noteworthy project to examine the scale of air pollution in Ireland and the impacts on the health of our vulnerable citizens.)

Smaller than a grain of sand

PM 2.5 particles are around 40 times smaller than a grain of sand – they are invisible to the human eye, but can scatter sunlight and are responsible for the haze associated with polluted cities. They are so small that they can be inhaled deep into the respiratory system, cross into the bloodstream and move around the body.

It is now well established that exposure to PM2.5 can worsen asthma and chronic obstructive pulmonary disease (COPD), cause heart attacks, strokes and even death. In fact, PM2.5 is responsible for the premature deaths of over 4.2 million people every year, with more than 1,100 of these deaths occurring annually in Ireland.

Any policies introduced to tackle this public health problem need to be based on reliable scientific information on the sources of PM2.5. Our research team in the Centre for Research into Atmospheric Chemistry at University College Cork (UCC) has been studying PM2.5 in Ireland for over a decade and we find that it has a range of sources, including traffic, industry and agriculture.

The main source, however, is the burning of solid fuels (peat, wood and coal) in stoves and fireplaces for home heating. Our studies, along with those conducted by colleagues in NUIG, have mainly focused on the urban centres of Cork, Galway and Dublin.

Information on PM2.5 sources in most towns around Ireland is very limited, even though air pollution from home fires is a widely recognised problem.

Average PM2.5 concentrations in Killarney and Enniscorthy were considerably higher than those in large cities Prof John Wenger Prof John Wenger

Closing the knowledge gap

Our research group in UCC devised the SAPPHIRE project to address this knowledge gap by measuring and identifying the key sources of air pollution in small towns.

In this research, funded and just published by the EPA, we conducted detailed measurements of PM2.5 in Killarney, Enniscorthy and Birr during wintertime when solid fuel burning and PM2.5 levels are typically at their highest.

Along with standard air quality monitoring equipment, we used advanced chemical fingerprinting techniques to quantify the contribution that peat, wood and coal made to PM2.5 levels.

We observed very similar results at each location.

• Regular daily patterns of PM2.5 pollution with evening peaks up to 10 times higher than daytime levels.
• Huge spikes in pollution when wind speeds and temperatures were low.
• On average 60-82% of the PM2.5 pollution was due to residential solid fuel burning.
• The burning of peat was the dominant source, followed by wood and then coal.

Average PM2.5 concentrations in Killarney and Enniscorthy were considerably higher than those in our large cities, even though these towns have a fraction of their population. Perhaps more worryingly, the World Health Organisation’s (WHO) 24-hour mean guideline value was exceeded on 42% of the days (16 out of 38) monitored.

Painting a stark picture

These research findings paint a stark picture of poor air quality in some of our smaller towns, which is likely replicated across the country. It is clear that action is urgently needed to reduce harmful emissions from residential solid fuel burning.

The introduction of the coal ban proved very effective at reducing air pollution and improving public health in Dublin and in other urban areas when it was introduced. The long-promised nationwide smoky coal ban could deliver similar benefits for small towns, and indeed the UK government has now moved to adopt this approach from next year.

However, it is clear from the SAPPHIRE research that a ban on smoky coal does not offer a panacea and will, in time, need to be complemented by a wider range of measures to address pollution from peat and wood burning. Consideration should be given to this broader approach in the National Clean Air Strategy proposed in the new Programme for Government.

Let’s not forget that reductions in solid fuel burning will also lower our carbon emissions, protect our natural peatlands, which act as a carbon store and so help to mitigate the damage caused by climate change.

More policy incentives needed

Ultimately, we need to ‘stop burning stuff’ to heat our homes and use clean energy sources instead. This change will take many years and entail significant costs. Many people in Ireland cannot afford to change to cleaner home heating, even with the current home energy grants.  

The government needs to provide a broader range of initiatives to support a transition from solid fuels. These initiatives could include: green taxes to make ‘dirty’ fuels more expensive; fuel standards such as wood moisture content (‘wet’ wood emits more PM2.5); support for people to transition from turf to cleaner fuels; and set emission standards for new stoves.

Finally, a national communication strategy is needed to raise awareness of the health impact of solid fuel home heating so that those with heating options can better appreciate the need to improve air quality by choosing less polluting ways of heating their homes.

In fact, we should start making better choices right now, as emerging research indicates that exposure to air pollution is likely linked with the occurrence or severity of Covid-19 infection.

So, using clean energy sources for heating our homes not only has benefits for air quality and climate, it also supports our national efforts to reduce the impact of Covid-19. Now, that is a win-win-win situation.

Professor John Wenger is director of the Centre for Research into Atmospheric Chemistry in UCC. He has over 25 years experience in air pollution research.

SOMETHING IN THE AIR Investigation

Do you want to know more about the main causes and impacts of air quality in Ireland? The Noteworthy team want to do an in-depth investigation into this issue to find out what is causing the problem, what we could be doing to tackle it, and how it impacts on the health of our most vulnerable citizens.

Here’s how to help support this proposal>