Particulate matter

Car emissions

Every year, on September 22nd, we have a European Car Free Day. Across the EU, people are asked to take different types of transport like walking, cycling and public transport.

Car emissions

Car emissions

Every year, on September 22nd, we have a European Car Free Day. Across the EU, people are asked to take different types of transport like walking, cycling and public transport.

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In the context of air pollution, particulate matter relates mainly to very small particles that are less than ten micrometres in size.  These very small particles are commonly known as PM₁₀ and they arise from the combustion of solid fuels and from road traffic.  PM₁₀ can also be caused by the chemical reaction of other air pollutants in the atmosphere and from natural sources such as airborne sea salt.

PM₁₀ particles are of concern because, due to their small size, they can penetrate deep into the lungs and can thereby damage the respiratory system and the heart.

While PM₁₀ emissions are dangerous, smaller particles known as PM_2.5 are even more damaging, as they can enter the bloodstream. 

PM10 2020

The PM₁₀ limit in air is set at a mean of 40 micrograms per cubic metre annually. A decreasing and steady trend is seen in urban zones (Zones A, B (Dublin) and C (Cork)) since 2009, which is most likely due to the decreases in particulate emissions from traffic due to improved vehicle engine emissions (although Zone B has shown a rise and fall in recent years). This general decrease is not seen in Zone D, where domestic solid fuel emissions are more significant than traffic emissions.

Emissions from cars have reduced over recent years thanks to improved engine design and exhaust cleaning, but the number of vehicles on the road has cancelled this out to some extent.  High PM₁₀ values were recorded both in inland towns, due to traffic and solid fuel burning, and at seaside locations due to sea salt in the air.

PM₁₀ values across Ireland have remained below EU and WHO air quality guideline limits since 2015. The increased use of electric vehicles will help to reduce the levels of PM₁₀ across Ireland, though PM_2.5 from Non Exhaust Emissions (NEEs) will remain an issue. 

PM25 2020

PM_2.5 particles are very very small, 1/40th the width of a human hair. We monitor these particles across Ireland to determine the danger they pose to public health. Levels of PM_2.5 have exceeded WHO limits in multiple years since 2009.

In 2019, both Dublin (Zone A) and Ennis (Zone C) exceeded the WHO air quality guideline value. Large towns with over 15,000 people and higher traffic volumes have the highest PM_2.5 levels.