Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe (c. 50)

ANNEX XII INFORMATION AND ALERT THRESHOLDS

B. Information and alert thresholds for ozone

a For the implementation of Article 24, the exceedance of the threshold is to be measured or predicted for three consecutive hours.
Purpose	Averaging period	Threshold
Information	1 hour	180 µg/m3
Alert	1 houra	240 µg/m3