Environmental pollution
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Environmental pollution · Sep 2014
Ozone levels in European and USA cities are increasing more than at rural sites, while peak values are decreasing.
Ground-level ozone (O3) levels are usually lower in urban centers than nearby rural sites. To compare trends in O3 levels during the period 1990-2010, we obtained monitoring data from paired urban and rural sites from the European Environment Agency and the US Environmental Protection Agency. ⋯ The overall trend was for convergence between urban and rural O3 data. Ozone levels exceeded the criteria established for the protection of human and vegetation health at both urban and rural sites.