Local authorities, health and environment
WHO/EURO Home page

Taking actions to improve air quality

Local authority powers to control sources and levels of air pollution will often be dictated by international and national policy and laws. For example, the way in which an industrial source operates and the level of permitted emissions will usually be decided nationally as will standards for vehicle exhaust emissions or measures to control domestic smoke emissions. Often, however, local authorities or regional authorities are responsible for enforcing legislation, for example issuing permits or licences for industrial processes under national or European integrated pollution control legislation. Local authorities can also influence local air quality by regulating or restricting traffic use in specific areas. Planning controls offer another means of ensuring that potentially polluting or hazardous processes are not sited in residential or other protected areas.

Local actions need to be supported by, and coordinated with, national air quality plans (e.g. The UK national air quality strategy, 1997) and related legislation and agreements such as the forthcoming Ambient Air Quality Assessment and Management Directive, other EU Directives, or international agreements, such as the Convention on the Long Range Transport of Air Pollution, or the Montreal Protocol on Substances that Deplete the Ozone Layer.

In order to help public authorities to manage and reduce health hazards and other risks from air pollutants, the WHO, EU and national authorities publish guidelines and limit values for most of the common pollutants (see tables p. a10). Although the WHO guidelines are not mandatory they are often used as the basis for EU and national limit values and guidelines. Some common air pollutants

WHO Air quality guidelines
Substances Averaging time Time-weighted average
Lead (1987) 1 year 0.5-1.0 µg/m3
Nitrogen dioxin (1994) 1 hour
200 µg/m3
40-50 µg/m3
Ozone (1994) 8 hours 120 µg/m3
Sulphur dioxine (1994) 10 minutes
4 hours
500 µg/m3
125 µg/m3
50 µg/m3
Particulate matter (1994)   (a)
Carbon monoxide (1994) 15 minutes
30 minutes
1 hour
8 hours
100 mg/m3 (b)
60 mg/m3
30 mg/m3
10 mg/m3
(a) no guideline value because there is no evident threshold for effects on morbidity and mortality
(b) the guideline is to prevent carboxyhaemaglobin levels in the blood exceeding 2.5%

EU Air quality guidelines
Substances Reference period Limit value (to be met by 1.4.83)
Sulphur dioxide one year
(median daily values)
120 µg/m3 if smoke less than 40 µg/m3

80 µg/m3 if smoke more than 40 µg/m3

(median daily values)
180 µg/m3 if smoke less than 60 µg/m3

130 µg/m3 if smoke more than 60 µg/m3

  year, peak
(98 percentile of daily values)
350 µg/m3 if smoke less than 150 µg/m3

250 µg/m3 if smoke more than 150 µg/m3

Suspended particulate matter (SPM) one year (median of daily values) 80 µg/m3
(median daily values)
130 µg/m3
  year, peak
(98 percentile of daily values)
250 µg/m3
    Guides values
Black smoke one year (median of daily values) 40-60 µg/m3
  24 hours mean 100-150 µg/m3
Sulphur dioxide 24 hours mean 100-150 µg/m3
  one year mean 40-60 µg/m3
  Reference period Limit value (to be met by 1.7.87)
Nitrogene dioxide:
EC Directive 85/203/EEC
1 year
(98 percentile of 1-hour means)
200 µg/m3
    Guides values
  1 year
(50 percentile of 1-hour means)
50 µg/m3
  1 year
(98 percentile of 1-hour means)
135 µg/m3
  Reference period Limit value (to be met by 9.12.87)
Lead in the air:
EC Directive 82/884/EEC
annual mean 2 µg/m3
Ozone Thresholds:
EC Directive 92/72/EEC
1 year
(98 percentile of 1-hour means)
200 µg/m3
Health protection 8 hours mean 110 µg/m3
Vegetation protection 1 hour mean 200 µg/m3
  24 hours mean 65 µg/m3
Population information 1 hour mean 180 µg/m3
Population warning 1 hour mean 360 µg/m3


Document Actions