Europeans are regularly exposed to unsafe amounts of ground level ozone, a gas which can have serious health effects, a report commissioned by the European Union showed yesterday. "The threshold set for the protection of human health is exceeded substantially and in all (EU) member states," said the European Environment Agency,which provides the data on which EU environmental legislation is based. More than 90 percent of all EU citizens were exposed to ozone levels above the limits recommended by the World Health Organisation at least once in 1995, the Copenhagen-based EEA said. The report marks the first part of the EU's ozone-monitoring programme, concentrating on the 1994 to 1996 period.