As part of the study, ozone levels potentially detrimental to human health were assessed where data was available, both in urban and non-urban areas worldwide. There is considerable variation within regions and hot-spot locations with the highest ozone levels have been identified.
This study uses a variety of ways of measuring the occurrence of high ozone levels to assess the frequency of periods a given population is exposed to harmful ozone levels and how this has changed over time.
Surface ozone levels potentially detrimental to human health are found in many regions around the globe, both in urban and non-urban areas. They found that different methods of determining high and peak ozone levels worldwide are generally similar.
While ozone has decreased in much of Europe and the North America over the past 15 years, the study shows it is increasing in parts of East Asia with increasing development and pollution emissions. A large publicly available database has been compiled which includes a complete set of statistics and graphics available for viewing and download.