What are the guidelines drafted by the World Health Organisation?
The World Health Organisation (WHO) has drafted guidelines for certain pollutants with the aim to reduce the health effect as much as possible. These guidelines are meant to inform policy makers across the globe and to reduce or prevent the risks of air pollution in an effective manner. The guidelines are established after evaluation of scientific studies (meta-analyses). The guidelines were revised in September 2021:
| WHO guidelines | ||||
|---|---|---|---|---|
| Pollutant | Subject | Averaging Period | Old guideline value (2005) | New guideline value (2021) |
| Particulate Matter - PM10 | guideline value | 1 day 1 year |
50 µg/m³ (max. 3 - 4/year) 20 µg/m³ |
45 µg/m³ (max. 3 - 4 exceedances/year) 15 µg/m³ |
| Particulate Matter - PM2.5 | guideline value | 1 day 1 year |
25 µg/m³ (max. 3 - 4/year) 10 µg/m³ |
15 µg/m³ (max. 3 - 4exceedances/yearr) 5 µg/m³ |
| Nitrogen dioxide (NO2) | guideline value | 1 hour 1 day 1 year |
200 µg/m³ / 40 µg/m³ |
200 µg/m³ 25 µg/m³ 10 µg/m³ |
| Suphur dioxide (SO2) | guideline value | 10 minutes 1 day |
500 µg/m³ 20 µg/m³ |
500 µg/m³ 40 µg/m³ |
| Ozone (O3) | guideline value | 8-hour* 6 month/8-hour** |
100 µg/m³ / |
100 µg/m³ (max. 3 - 4 exceedances/year) 60 µg/m³ |
| Carbon monoxide (CO) | guideline value | 15 minutes 1-hour mean 8-hour mean 1 day |
100 mg/m³ 35 mg/m³ 10 mg/m³ / |
100 mg/m³ 35 mg/m³ 10 mg/m³ 4 mg/m³ (max. 3 - 4 exceedances/year) |
| Benzene | reference value | calendar year | 1.7 µg/m³ | 1.7 µg/m³ |
| Lead (Pb) | guideline value | calendar year | 0.5 µg/m³ | 0.5 µg/m³ |
| Arsenic (As) | reference value | calendar year | 6.6 ng/m³ | 6.6 ng/m³ |
| Cadmium (Cd) | guideline value | calendar year | 5 ng/m³ | 5 ng/m³ |
| Nickle (Ni) | reference value | calendar year | 25 ng/m³ | 25 ng/m³ |
| Benzo(a)pyrene (B(a)P) | reference value | calendar year | 0.12 ng/m³ | 0.12 ng/m³ |
Until today, the scientific world has not been able to establish a value beneath which no health effects prevail. The guidelines shown above can thus not guarantee absolute protection of health. The WHO guidelines are meant to be used all over the world to support actions (in various contexts) for amelioration of air quality.
The limit and target values used in the European Union are most often a consideration of three elements: protection of public health, the accompagnying risk analysis, and the political context. The standards are dependent of the used strategy to reach a balance between health risks, technical feasability, economical considerations and even more political and social aspects, which in turn are dependent on the level of development and the options of a member state, and the available expertise on air quality.
