The Air Quality Standards Regulations (Northern Ireland) 2007

PART 4 Ozone

7.  The minimum number of sampling points for fixed measurement of ozone to assess compliance with the target values, long-term objectives and information and alert thresholds where continuous measurement is the sole source of information is set out in the following table.

Population of zone (thousands)	Agglomerations (urban and suburban)(1)	Other zones (suburban and rural)(1)	Rural background
(1) At least 1 station in suburban areas, where the highest exposure of the population is likely to occur. In agglomerations at least 50% of the stations should be located in suburban areas.
(2) 1 station per 25,000 km² for complex terrain is recommended by Directive 2002/3/EC.
0–249	1	1	1 station/50,000 km² as an average density over all zones per country(2)
250–499	1	2
500–999	2	2
1,000–1,499	3	3
1,500–1,999	3	4
2,000–2,749	4	5
2,750–3,749	5	6
3,750 or more	1 additional station per 2 million inhabitants	1 additional station per 2 million inhabitants