The burning of peat, timber and coal remains the largest single source of pollution in a series of major regional towns, according to a two-year study conducted for the Environmental Protection Agency.
The reduction in car traffic flows caused by the Covid-19 lockdown led to a dramatic falls in the levels of harmful nitrogen oxides (NOx) in the air in the State’s cities, especially Dublin.
However, air quality in towns such as Killarney, Birr and Enniscorthy improved less since the majority of pollution there comes not from traffic, but, rather, the burning of solid fuels.
Such burning creates so-called PM2. 5 particles in the air, which are 2.5 micrometres in size, or more than 100 times thinner than a human hair and cause difficulties with breathing.
Evening levels of PM2.5 in Killarney, Birr and Enniscorthy were multiples of day-time levels and even more significant spikes in pollution levels were found on evenings when wind speeds were low.
Real-time monitoring by the UCC team shows residential solid fuel burning was the dominant source, accounting for 72 per cent of PM2.5 in Killarney, 82 per cent in Enniscorthy and 60 per cent in Birr.
Peat burning
Using chemical fingerprints of particles generated from the combustion of different fuels, the team showed that peat burning is responsible for the majority of this pollution, followed by wood and coal.
In Dublin, the level of nitrous oxide in the air (NOx) fell sharply during lockdown, but particulate levels remained puzzling high, particularly as the city has a ban on smoky fuels.
However, Dublin City Council’s air quality monitoring unit ultimately ascribed the high levels of PMs to dust that had been blown on to the city from north Africa, which then combined with particulate matter in the air.
“All of these pollutants are of concern, but if you want to see the impact of cars the NOx data is a key indicator and it fell very significantly in lockdown,” said principal environmental health officer Martin Fitzpatrick.
The results of the two years of research by the UCC team, led by Prof John Wenger, were published this week on the Environmental Protection Agency website.
The European Environment Agency has identified air pollution as the single largest environmental health hazard in Europe, while PM2.5 pollution alone is blamed for 1,100 premature deaths in Ireland each year.
