Sussex-air :: Promoting better Air Quality in Sussex :: www.sussex-air.net :: How is the Air Pollution Index calculated?

How the air quality bands are calculated

Band	Index	Ozone	Nitrogen Dioxide	Sulphur Dioxide	PM2.5 Particles	PM10 Particles
		Running 8 hourly mean	Hourly mean	15 minute mean	24 hour mean	24 hour mean
		µg m-3	µg m-3	µg m-3	µg m-3	µg m-3
Low
	1	0-33	0-67	0-88	0-11	0-16
	2	34-66	68-134	89-177	12-23	17-33
	3	67-100	135-200	178-266	24-35	34-50
Moderate
	4	101-120	201-267	267-354	36-41	51-58
	5	121-140	268-334	355-443	42-47	59-66
	6	141-160	335-400	444-532	48-53	67-75
High
	7	161-187	401-467	533-710	54-58	76-83
	8	188-213	468-534	711-887	59-64	84-91
	9	214-240	535-600	888-1064	65-70	92-100
Very High
	10	241 or more	601 or more	1065 or more	71 or more	101 or more
Pollution concentrations recorded by the LAQN analysers have been classified according to Defra's Air Pollution Index system. This classes levels into bands from 'low' to 'very high'. Each band is subdivided into three to produce an Air Pollution Index, from 1 to 10, 1 being 'low', 10 being 'very high'. Measurements are rounded to the nearest whole number. The concentrations are classified according to the table above. Note that different pollutants have different concentrations and averaging periods, related to the estimated health effects of each.
Read a technical explanation of how the new index bands (1st January 2012 onwards) are calculated here