Directive 2008/50/EC of the European Parliament and of the CouncilShow full title

ANNEX XII U.K. INFORMATION AND ALERT THRESHOLDS

A. Alert thresholds for pollutants other than ozone U.K.

To be measured over three consecutive hours at locations representative of air quality over at least 100 km² or an entire zone or agglomeration, whichever is the smaller.

Pollutant	Alert threshold
Sulphur dioxide	500 μg/m3
Nitrogen dioxide	400 μg/m3

B. Information and alert thresholds for ozone U.K.

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