What We Monitor

The Environmental Protection Agency manages the national ambient air quality monitoring network. We also measure the levels of a number of atmospheric pollutants. The pollutants of most concern are those whose main source is traffic such as Particulate Matter and Nitrogen Dioxide.

Particulate matter (PM₁₀ and PM_2.5)

PM are particles in the air typically measured as PM₁₀ and PM_2.5 with diameters of 10μm (microns) or 2.5μm. In Ireland, the main sources are solid fuel burning and vehicular traffic. Other sources are soil and road surfaces, construction works and industrial emissions or natural sources such as windblown salt, plant spores and pollens. These direct emissions are known as primary PM. Particulate matter can be formed from reactions between different pollutant gases (secondary sources).

Small particles can penetrate the lungs and cause damage. There are high levels of PM₁₀ in many cities and towns.

Nitrogen dioxide (NO₂) and Nitrogen oxides (NO_x)

Emissions from traffic are the main source of nitrogen oxides in Ireland along with electricity generating stations and industry. Nitrogen dioxide can affect the throat and lung. The main effects are emphysema and cellular damage.

It impacts visually as it has a brown colour and gives rise to a brown haze. Oxides of nitrogen contribute to the formation of acid rain and of ozone.

Levels in Ireland are moderate but are increasing due to growth in traffic numbers.

Ozone (O₃)

Ozone is a natural component of the atmosphere. Most ozone is found high up in the stratosphere, the layer of the atmosphere between 12km and 50km above sea level. Stratospheric ozone is essential to life on earth as it protects us from harmful rays from the sun.

Ozone is also found in the troposphere, the layer of the atmosphere next to the earth. Exposure to high concentrations of tropospheric ozone causes chest pains, nausea and coughing in humans.

Long term exposure to moderate concentrations causes a reduction in lung capacity and can worsen heart disease, bronchitis, emphysema and asthma. Tropospheric ozone contributes to the greenhouse effect and subsequent global climate change.

Levels of ozone in Ireland are moderate.

Sulphur dioxide (SO₂)

The main source of sulphur dioxide in Ireland is burning coal and oil to heat homes and industries and to produce electricity.

It is an irritant gas which attacks the throat and lungs. Prolonged exposure can lead to increases in respiratory illnesses like chronic bronchitis. It contributes to the formation of acid rain which damages vegetation and buildings.

Levels in Ireland are low to moderate. Levels have decreased over recent years due to increased use of low-sulphur "smokeless" coal, increased use of natural gas instead of solid fuels and reduced industrial emissions through IPC licensing.

Carbon monoxide (CO)

The main source of carbon monoxide in Ireland is traffic. It is absorbed into the bloodstream more readily than oxygen, so the relatively small quantities in inhaled air can have harmful effects.

Prolonged exposure can cause tissue damage and individuals suffering from cardiovascular disease are particularly at risk. Levels in Ireland are low.

Benzene (C₆H₆)

Benzene comes from petrol emissions and the evaporation of petrol at petrol stations. It is a carcinogen.

Acute short-term inhalation may cause drowsiness, dizziness, headaches, as well as eye, skin, and respiratory tract irritations, and, at high levels, unconsciousness. Levels of benzene are low in Ireland.

Lead (Pb)

The main source of lead in air has historically been from petrol engine exhaust emissions. High concentrations can affect mental and physical development in children. Long-term exposure to low levels of lead can affect the nervous system.

Following the introduction of unleaded petrol in Ireland, lead emissions in ambient air have been dramatically reduced resulting in very low lead concentrations.

PAH (Poly Aromatic Hydrocarbons)

This encompasses a wide range of compounds that consist of two or more aromatic rings made entirely of Carbon and Hydrogen. Airborne PAH, when inhaled, is believed to produce lung cancer.

Sources in Ireland include car emissions and the burning of fossil fuels such as coal and turf.

Benzo(a)pyrene (BaP) is the most common PAH in ambient air and is therefore used as a marker to set air quality and emission standards.

Arsenic (As)

Arsenic in ambient air can exist in two forms. Primarily it exists in the form of various compounds absorbed onto the surface of fine particles (<2mm), usually a mix of Arsenite and Arsenate. These particles can be transported by wind across distances greater than 1,000 kilometres.

The other form occurs in the gaseous state as a result of high temperature volitalisation. Examples are Arsenic Trioxide (As₃O₃) and Arsenic Trihydride (As₃H₃).

Short-term exposure can cause irritation of the respiratory system, which can lead to laryngitis, bronchitis or rhinitis. Long-term exposure can cause irritation to the respiratory tract and cardiovascular and neurological effects. It can also produce severe dermatitis and increase the risk of lung cancer.

Nickel (Ni)

Sources of nickel in the atmosphere are primarily fossil fuel (oil and coal) combustion, high temperature metallurgical operations, nickel primary production operations, and municipal waste incineration.

Nickel in air is mainly in particulate form, mainly in the form of nickel sulphates, nickel chloride, nickel nitrate, and nickel oxide. Nickel inhalation has been reported to affect the respiratory, immune and renal systems.

Long-term inhalation can produce asthma, chronic bronchitis, emphysema, reduced vital capacity, and lung and nasal cancers.

Cadmium (Cd)

The release of Cadmium containing particles to the atmosphere are as a result of industrial processes including mining, metal-plating and the production of batteries, plastics and pigments. Cadmium is also emitted from waste incineration.

Cadmium forms cadmium oxide (CdO) when combusted in air. While other industry led sources of cadmium containing species include cadmium chloride (CdCl₂), cadmium sulfate (CdSO₄) and cadmium nitrate (Cd(NO₃)₂).

Cadmium and many cadmium containing compounds are carcinogenic and are associated with numerous cancers. Significant non-cancer effects are also reported. Exposure to environmental cadmium is predominately as a result of the burning of fossil fuels and municipal waste.

Mercury (Hg)

The majority of mercury emissions are produced from fossil fuel combustion and solid waste incineration. Coal burning power plants are the largest human-caused source of mercury emission to the air.

Mercury in the atmosphere eventually deposits in water where certain micro-organisms can change into methyl mercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. This is the main source of exposure to humans.

Another source of exposure is breathing of elemental mercury or products that contain elemental mercury that break and release elemental mercury to the air, particularly in warm and poorly ventilated indoor spaces.

Mercury exposure at high levels can harm the brain, heart, kidneys, lungs and immune system of people of all ages, especially to the developing nervous system of unborn babies and young children.

When elemental mercury enters the bloodstream, it can penetrate the blood-brain barrier where it can disrupt metabolic processes, causing tremor and psychopathological symptoms such as shyness, insomnia, depression and irritability.