European ozone limit breaches fall in 2014

The number of breaches of EU legal limits for ground-level ozone (O3) pollution continued to fall across Europe in summer 2014, according to the European Environment Agency (EEA).

EEA map showing long-term ozone (O3) exceedances across Europe in 2014 (click to enlarge)

However, in a briefing note published today (May 6), the EU body said that ozone continued to affect many countries throughout Europe during summer 2014, with almost all European countries exceeding long-term thresholds for ozone set by EU legislation.

Nevertheless, the number of exceedances was lower than in many previous years, in line with the long-term downward trend observed over the last 25 years, the EEA said.

Ozone is a ‘secondary’ pollutant formed from gases such as nitrogen oxides (NO_X) and volatile organic compounds (VOCs) in the presence of solar light, thus high ozone levels are most common during summer months in Europe due to the warmer temperatures higher levels of solar radiation.

Indeed, June and July last year respectively accounted for 75% and 25% of EU alert threshold exceedances.

Furthermore, the EEA’s assessment found that a large proportion of EU limit breaches across Europe took place during a single episode of high ozone concentrations between 7 and 14 of June 2014.

EU ozone legislation

Exposure to high concentrations of ground-level ozone can cause and aggravate cardiovascular and respiratory disease and the EU sets four legal standards to cut emissions of the pollutant:

• Information threshold: 1-hour average ozone concentration of 180 μg/m³ (microgrammes per cubic metre). Exceedance of this threshold triggers an obligation to inform the population on possible risks if exposure.
• Alert threshold: 1-hour average ozone concentration of 240 μg/m³. Exceedance of this threshold requires countries to take ‘immediate action’.
• Long-term objective: the maximum daily 8-hour mean concentration of ozone should not exceed 120 μg/m³
• Target value: long-term objective should not be exceeded on more than 25 days per year, averaged over 3 years.

The EEA said: “Depending on which threshold is exceeded, authorities in the affected areas and countries have to take specific measures. For example, exceeding the information threshold triggers an obligation to inform the population on possible risks, while exceeding the alert threshold requires authorities to take immediate action.”

Ozone measurements were reported from 1,607 monitoring stations across 30 European countries, although the EEA assessment is based on provisional data and is therefore subject to possible change.

None of the 74 ozone monitoring stations in the UK reported any target value exceedances in 2014, although the threshold was exceeded on a maximum of seven days.

Meanwhile, some of the largest number of breaches were seen in France, where exceedances of ozone limits took place on 65 days during 2014, with 23 of its 298 ozone monitoring stations reporting breaches.

Indeed, ozone concentrations higher than the EU alert threshold were reported on only four occasions 2014, and these were all in France.

Related Links:

–EEA summer 2014 ozone assessment