Summer ozone at harmful levels in 2013

News Published 13 Mar 2014 Last modified 20 Feb 2017
2 min read
Photo: © Francesco Pasqualetti
Ground-level ozone exceeded legal limits in every Member State and at many individual measurement sites during summer 2013, according to the European Environment Agency's annual report on this harmful pollutant. Although the number of exceedances is high, they have decreased over recent decades, the report notes.

Ozone pollution significantly exceeded EU standards to protect health during the summer of 2013, particularly during July and the first days of August. The most problematic areas were the Mediterranean and Alpine regions. In some countries up to two fifths of the population was exposed to levels exceeding limits, the report says.

Recent scientific studies have shown that ground-level ozone pollution is harmful even at very low levels. This means that levels are still far too high, even though the the limits were exceeded on fewer occasions than in many previous years. Moreover, this does not necessarily mean that exposure is falling a corresponding amount. A separate study found that in 2012, almost all inhabitants of cities in the EU were exposed to ozone levels above World Health Organisation guidelines, which are stricter than the EU limits.

Ground-level ozone is a 'secondary pollutant', which means it is formed in chemical reactions between other pollutants in the air. It is a particular problem during the summer as it forms in warm weather. High ozone concentrations can cause serious health problems, especially respiratory illnesses and cardiovascular problems, leading to premature death in some cases. It also damages vegetation such as agricultural crops.

Key findings

  • The long-term objective (LTO) for the protection of human health (a maximum daily eight-hour mean concentration of 120 μg/m3) was exceeded at least once in all Member States and overall at 83 % of all reporting stations. Although the number of exceedances is still very high, it is the lowest percentage since reporting started in 1997.
  • The LTO was exceeded on more than 25 days across a significant part of Europe.
  • The so-called 'information threshold' (a one-hour average ozone concentration of 180 μg/m3) was exceeded at approximately 26 % of all operational stations, one of the lowest percentages since 1997. In Northern Europe, the information threshold was not exceeded at all in 2013.
  • The 'alert threshold' (a one-hour average ozone concentration of 240 μg/m3) was exceeded 27 times, again one of the lowest numbers on record.


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