Drivers & Pressures

Main sources of pollutants

Emissions from road traffic are the main source of many air pollutants harmful to human health, including nitrogen dioxide, oxides of nitrogen, particulate matter, carbon monoxide, volatile organic compounds and heavy metals. In Dublin and Cork concentrations of nitrogen dioxide are close to the limit value at monitoring stations near busy roads.

The burning of coal and other solid fuel is also a source of particulate matter and other air pollutants including sulphur dioxide and polycyclic aromatic hydrocarbons.  The ban on bituminous coal in large cities and towns has greatly reduced levels of particulate matter in those areas.  The absence of a ban on bituminous coal in smaller towns means levels of particulate matter there are as high as levels in some cities.

Transboundary Pollution

Air pollution has a transboundary aspect meaning that emissions in one country can cause pollution in a different country.  National emissions ceilings are in place across Europe to control emissions of four key transboundary pollutants: sulphur dioxide (SO₂), oxides of nitrogen (NO_x), volatile organic compounds (VOC) and ammonia (NH₃).  These pollutants  can contribute to acidification, eutrophication and ozone formation. 

Strategies implemented in Ireland in recent years have substantially reduced emissions of SO₂, VOC and NH₃, but levels of NO_x are expected to remain high in the short term. Large increases in road transport are responsible for high NO_x emissions levels. The benefits associated with increased penetration of catalyst control technology have been offset by increases in road traffic.