| Band |
Index |
Ozone |
Nitrogen Dioxide |
Sulphur Dioxide |
Carbon Monoxide |
PM10 Particles** |
| 8 hourly or hourly mean* |
hourly mean |
15 minute mean |
8 hour mean |
24 hour mean |
| µg m-3 |
ppb |
µg m-3 |
ppb |
µg m-3 |
ppb |
mg m-3 |
ppm |
µg m-3 |
| Low |
| |
1 |
0-32 |
0-16 |
0-95 |
0-49 |
0-88 |
0-32 |
0-3.8 |
0.0-3.2 |
0-19 |
| 2 |
33-66 |
17-32 |
96-190 |
50-99 |
89-176 |
33-66 |
3.9-7.6 |
3.3-6.6 |
20-40 |
| 3 |
67-99 |
33-49 |
191-286 |
100-149 |
177-265 |
67-99 |
7.7-11.5 |
6.7-9.9 |
41-62 |
| Moderate |
| |
4 |
100-126 |
50-62 |
287-381 |
150-199 |
266-354 |
100-132 |
11.6-13.4 |
10.0-11.5 |
63-72 |
| 5 |
127-152 |
63-76 |
382-476 |
200-249 |
355-442 |
133-166 |
13.5-15.4 |
11.6-13.2 |
73-84 |
| 6 |
153-179 |
77-89 |
478-572 |
250-299 |
443-531 |
167-199 |
15.5-17.3 |
13.3-14.9 |
85-94 |
| High |
| |
7 |
180-239 |
90-119 |
573-635 |
300-332 |
532-708 |
200-266 |
17.4-19.2 |
15.0-16.5 |
95-105 |
| 8 |
240-299 |
120-149 |
363-700 |
333-366 |
709-886 |
267-332 |
19.3-21.2 |
16.6-18.2 |
106-116 |
| 9 |
300-359 |
150-179 |
701-763 |
367-399 |
887-1063 |
333-399 |
21.3-23.1 |
18.3-19.9 |
117-127 |
| Very High |
| |
10 |
360 or more |
180 or more |
764 or more |
400 or more |
1064 or more |
400 or more |
23.2 or more |
20 or more |
128 or more |
* For ozone, the maximum of the 8 hourly and hourly mean is used to calculate the index value.
** Note that from August 2009 the PM10 index uses Reference Equivalent PM10 measurements. |
| 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'. 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 |
| See the bands for 1st Janurary 2012 Go back to the bulletin page |
|
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