Tab. II.6.1 Air quality index definition

Index  Air quality Threshold concentration [μg.m-3]
 hourly average  8-hour average
 NO2  O3  PM10  SO2  CO
1  very good  0–25  0–33  0–15  0–25  0–1 000
2  good  26–50  34–65  16–30  26–50  1 001–2 000
3  satisfactory  51–100  66–120  31–50  51–120  2 001–4 000
4  acceptable  101–200  121–180  51–70  121–250  4 001–10 000
5  poor  201–400  181–240  71–150  251–500  10 001–30 000
6  very poor  above400  above240  above150  above 500  above 30 000