Last reviewed 19 November 2013

Despite the successes of the European Union’s actions to curb air pollution, levels of ozone and particulate remain at unsafe levels. The latest European Environment Agency report sets out the challenges regulators still face. Rob Bell reports.

The European Environment Agency’s (EEA) latest research and report, Air Quality in Europe — 2013 Report, has found that around 90% of European Union (EU) city dwellers are exposed to ground-level ozone (O3) and fine particulate matter (PM2.5) at levels determined to be harmful to health by the World Health Organization (WHO).

The EEA says vehicles, industry, agriculture and homes are contributing to air pollution in Europe, and despite falling emission levels and reductions of some air pollutant concentrations in recent decades, “Europe's air pollution problem is far from solved.”

EEA Executive Director Hans Bruyninckx says: “Air pollution is causing damage to human health and ecosystems. Large parts of the population do not live in a healthy environment, according to current standards. To get on to a sustainable path, Europe will have to be ambitious and go beyond current legislation.”

Europe’s Environment Commissioner Janez Potocnik also commented on the report. He says: “Air quality is a central concern for many people. Surveys show a large majority of citizens understand well the impact of air quality on health, and are asking public authorities to take action at EU, national and local levels, even in times of austerity and hardship.”

Exceeding WHO guidelines

Between 2009 and 2011, up to 96% of city dwellers were exposed to PM2.5 concentrations above WHO guidelines, and up to 98% to O3 at levels above WHO guidelines, the EEA says. Rural areas were also found to have significant levels of air pollution.

Alongside health concerns, the report also highlights environmental problems, such as eutrophication: when excessive nutrient nitrogen damages ecosystems, threatening biodiversity. Eutrophication is still a widespread problem that affects most European ecosystems.

The report also states: “Emissions of some nitrogen-containing pollutants have decreased, for example, emissions of nitrogen oxides and ammonia have fallen by 27% and 7% respectively since 2002. However, emissions were not reduced as much as anticipated, with eight EU Member States breaching legal ceilings a year after the deadline for compliance. To address eutrophication, further measures are needed to reduce emissions of nitrogen.”

Threats to Europe’s economy

It’s not all bad news. Europe has significantly cut emissions of several air pollutants in recent decades, greatly reducing emissions and exposure to substances such as sulphur dioxide (SO2), carbon monoxide (CO), benzene (C6H6) and lead (Pb).

However, the report says: “PM, O3, reactive nitrogen substances and some organic compounds still pose a significant threat… and constitute real losses for the European economy, the productivity of its workforce, and the health of its natural systems.”

A range of factors are to blame for continuing problems with air pollution. Road transport, industry, power plants, households and agricultural activities continue to emit significant amounts of pollution. Combustion of biomass by households — burning fuels such as wood and coal — is an important source of directly emitted PM and polycyclic aromatic hydrocarbons (PAHs).

The report says: “In fact, biomass combustion has become a more important source of air pollution. This is because wood burning is often relatively cheap, and is considered to be an environmentally friendly source of energy since it is renewable and carbon-neutral.” Cross-border, or trans-boundary, pollution is also a challenge in Europe. For many European countries, less than 50% of PM2.5 concentrations derive from their own emissions.

Many air pollutants are transported over long distances. For example, contributions from intercontinental transport influence O3 and PM concentrations in Europe.

Each pollutant produces a range of effects from mild to severe, as concentrations or exposure increases. The main effects of air pollution are:

  • damage to human health caused by exposure to air pollutants, or by intake of pollutants transported through the air, deposited and then accumulated in the food chain

  • acidification of ecosystems (both terrestrial and aquatic), which leads to loss of flora and fauna

  • eutrophication in ecosystems on land and in water, which can lead to changes in species diversity; damage and yield losses affecting agricultural crops, forests and other plants due to exposure to ground-level O3

  • impacts of heavy metals or toxic metalloids and persistent organic pollutants on ecosystems, due to their environmental toxicity and bioaccumulation

  • contribution to climate forcing and indirect effects on climate

  • reduction of atmospheric visibility

  • damage to materials and buildings due to soiling and exposure to acidifying pollutants and O3.

Damage to ecosystems

The report says: “European citizens often breathe air that does not meet European standards. Current pollution levels, especially of PM, O3, and an important PAH — benzo(a)pyrene (BaP) — clearly impact on large numbers of the urban population.

“Air pollution's most important effects on European ecosystems are damage to vegetation resulting from exposure to O3, eutrophication and acidification.

“As SO2 emissions have fallen, ammonia (NH3) emitted from agricultural activities, and nitrogen oxides (NOX — a family of gases that includes nitrogen dioxide (NO2) and nitrogen oxide (NO)) emitted from combustion processes have become the predominant acidifying and eutrophying air pollutants.”

Climate forcers

Several air pollutants also act as what the EEA describes as “climate forcers” — pollutants with an impact on the planet's climate and global warming in the short term (decades). Ground level O3, PM and black carbon (a constituent of PM) are examples, contributing directly to positive or negative changes in global radiative forcing. Particles can also cause climate-forcing indirectly, through changes caused to cloud properties such as reflectivity, rainfall and cloud formation.

The report says: “Measures to cut black carbon and other pollutants leading to O3 formation (among them— CH4, which is itself a greenhouse gas) will have twin benefits, reducing both global warming and pollution effects to human health and ecosystems.

“Air quality and climate change can be cost-effectively tackled together by using an integrated approach when defining policies and measures.”

Particulate matter (PM)

The EEA report says: “In terms of potential to harm human health, PM poses the greatest risk, as it penetrates into sensitive regions of the respiratory system and can lead to health problems and premature mortality.”

PM in the atmosphere originates from primary particles emitted directly; and “secondary” particles produced as a result of chemical reactions involving precursor gases: SO2, nNOX, NH3 and non-methane volatile organic compounds (NMVOC).

Emissions of primary PM10 and PM2.5 decreased by 14% and 16% respectively in the EU between 2002 and 2011, the EEA found. PM precursor emissions also decreased between 2002 and 2011 — by 50% in the case of sulphur oxides, down to just 5% for NH3.

However, the report says: “Despite these emission reductions, 22–44% of the EU urban population was exposed to concentrations of PM10 in excess of the EU air quality daily limit value in the period 2002–2011.

“EU limit and target values for PM were exceeded widely in Europe in 2011, with the PM10 24-hour limit value being exceeded in 22 European countries. The non-legally-binding WHO guidelines for PM10 and PM2.5 annual mean concentrations, which are stricter than the limit and target values set by EU legislation, were exceeded at the majority of monitoring stations across continental Europe.”

Ground-level O3

Ozone is a secondary pollutant (it is not emitted directly by any emission source), formed in the troposphere, the lower part of the atmosphere, from complex chemical reactions between precursor gases such as NOx and NMVOCs. At the continental scale, CH4 and CO also play a role in O3 formation. It is a powerful and aggressive oxidising agent, elevated levels of which cause respiratory health problems and lead to premature mortality.

High levels can also damage plants, leading to reduced agricultural crop yields and decreased forest growth. Ground-level O3 also contributes directly and indirectly to global warming.

In the EU between 2002 and 2011, EEA research found a decrease in O3 precursor gas:

  • NOx emissions by 27%

  • NMVOC emissions by 28%

  • CO emissions by 32%

  • CH4 emissions by 15%.

However, O3 in Europe also results from precursor gases emitted elsewhere. The report says: “There is a discrepancy between past reductions in emissions of O3 precursor gases in Europe and the change in observed average O3 concentrations in Europe. One of the reasons for this is increasing intercontinental transport of O3 and its precursors in the northern hemisphere, which is likely to mask the effects of European measures to reduce O3 precursor emissions.

“While emissions of gases that contribute to the formation of O3 dropped significantly in Europe, O3 concentrations decreased only slightly. Larger reductions in emissions of O3 precursor gases are necessary to achieve reductions in O3 concentrations.”

Between 14 and 65% of the EU urban population was exposed to O3 concentrations above the EU target value for protecting human health in the period 2002–2011. Furthermore, between 21 and 69% of agricultural crops in the EEA-32 were exposed to O3 levels above the EU target value for protecting vegetation from 2002 to 2010.

Challenges ahead

As Potocnik says: “There are still major challenges to human health from poor air quality. We are still far from our objective to achieve levels of air quality that do not give rise to significant negative impacts on human health and the environment.”

The EU has achieved a great deal through the regulatory measures it has put in place. Unfortunately, they have not proven enough, due to a range of factors from growing car use to winds blowing precursor gases over the Continent.

Tougher action is required — and planned — but the EU has a long way to go before city dwellers are free from the health impacts of air pollution. Those who choose to live in Europe’s cities may accept tainted air as part of the price they pay for their choice of home, but the EEA report finds rural dwellers, too, suffer as a result of air pollution. Progress will continue to be made, but unfortunately the health impacts of breathing polluted air will be felt by Europeans daily, for many years to come.