The World Health Organisation publishes Air Quality Guidelines based on certain pollutants health effects and are there to aid policy makers. The European Union developed their Ambient Air Quality (AAQ) Directives (Directives 2008/50/EC and 2004/107/EC) considering the WHO Guideline figures and the situation in Europe at the time. For some pollutants, they mirror each other exactly (NO2 & CO) whereas for others the WHO guidelines are tighter than EU regulation (SO2, O3 and PM)
| Pollutant |
Air Quality Guidelines (WHO, 2005) |
EU Standards (Directive 2008/50/EC) |
no. of EU exceedances allowed in a year |
| PM2.5 |
10 µg /m3 annual mean
|
25 µg /m3 annual mean
|
-
|
|
25 µg /m3 24-hour mean
|
-
|
-
|
| PM10 |
20 µg /m3 annual mean
|
40 µg /m3 annual mean
|
-
|
|
50 µg /m3 24-hour mean
|
50 µg /m3 24-hour mean
|
35
|
| O3 |
100 µg /m3 8-hour mean |
120 µg /m3 8-hour mean |
25 averaged over 3 years |
| NO2 |
40 µg /m3 annual mean
|
40 µg /m3 annual mean
|
-
|
|
200 µg /m3 1-hour mean
|
200 µg /m3 1-hour mean
|
18
|
| SO2 |
20 µg /m3 24-hour mean
|
125 µg /m3 24-hour mean
|
3
|
|
-------------
|
350 µg /m3 1-hour mean
|
24
|
|
500 µg /m3 10-minute mean
|
-----------
|
-
|
| CO |
10,000 µg /m3 8-hour mean |
10,000 µg /m3 8-hour mean |
- |
