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Clean Outdoor Air

Scyscrapers in smog, Indonesia
Pie chart: 30% of world population affected (1.84 billions) Bar chart: 960 000 deaths per year Bar chart: 74.3 billion $ in damages per year Negative trend

Humans need healthy air, but especially in urban settlements there is a high level of air pollution. This results in respiratory and cardiovascular diseases. Additionally, air pollution damages ecosystems and agriculture.

Affected people and foundations of life: In 2000, about 1.84 billion people of urban population were exposed to annual mean levels of particulate air pollutants above 20 g/m3 (micrograms per cubic metre). This is the health related guideline for PM10 (particulate matter with a diameter less than 10 microns [m] or 0.01 mm). Among them 937 million people were exposed to levels above 70 g/m3 of airborne particles, and only 226 million city-dwellers lived below the recommended guideline level of 20 g/m3. (OECD [Organisation for Economic Co-operation and Development] 2008, 183ff. [and following pages], and 2008a, Data, world; sum by own calculation; WHO [World Health Organization] 2006.)
  The hemispheric background concentration of ozone has doubled since industrialization started. (Ground level ozone is formed by photochemical processes involving pollutants like nitrogen oxides or volatile organic compounds [VOC]; it is not to be confused with the natural and protective ozone layer in the high altitudes of the stratosphere.) The economic costs of ground level ozone exposure by agricultural crops in Europe are estimated to have been € 2.8 billion in 2000. (OECD 2008, 181 and 179.)
  Annual damages by air pollution in the US (United States (of America)) are estimated to be US$ (United States dollars) 74.3 billion or 0.7% of GDP (gross dmoestic product) (OECD 2008, 260). 5% of all cases of lung, trachea, and bronchus cancers can be attributed to urban air pollution. The principal cause is the increasing combustion of fossil fuels for traffic, power generation, etc. (and so on) Particularly cities in Asia and the Western Pacific Region are concerned. (WHO 2002, 69, 226.) The atmosphere's ability to cleanse itself of pollutants has declined by about a tenth since preindustrial times (MA [Millennium Assessment] 2005, 42).

Deaths: 960 000 premature death cases were caused by PM10 in 2000 (158 per million inhabitants), and 7 deaths per million inhabitants caused by ground-level ozone (OECD 2008, 257ff., and 2008b).

Loss of able life-years: 9.6 million years of life lost (YLL, not considering years of disability) caused by PM10 in 2000 (OECD 2008, 257).

Targets/goals: The WHO has set guidelines for air quality, which are supplemented with interim targets that aim at promoting a gradual shift from high to lower concentrations:

  • Particulate matter:
    • PM2.5: 10 g/m3 annual mean (interim targets: 35, 25, 15 g/m3)
    • PM10: 20 g/m3 annual mean (interim targets: 70, 50, 30 g/m3)
    As no threshold for respirable particles below which no damage to health is observed has been identified, the aim is to achieve the lowest concentrations possible.
  • Ground-level ozone (O3):
    100 g/m3 daily maximum 8-hour mean (interim target: 160 g/m3)
  • Nitrogen dioxide (NO2):
    40 g/m3 annual mean
  • Sulphur dioxide (SO2):
    20 g/m3 24-hour mean (interim targets: 125, 50 g/m3; WHO 2006, 9, 11f. [and following page], 14f., 16 and 18).

Trend: While many air pollution indicators have shown a downward trend during the last decades, a further deterioration of urban air quality until 2030 is projected. Premature deaths caused by PM10 are estimated to triple from 960 000 inhabitants in 2000 to 3.1 million inhabitants in 2030. Deaths caused by ground-level ozone will quadruple from 7 per million inhabitants in 2000 to 31 per million inhabitants in 2030. (OECD 2008, 178, 257ff., 278, and 2008b.) According to previous WHO estimates death cases attributable to urban air pollution have already increased from 799 000 in 2000 to 865 000 people in 2002 (WHO 2002, 69 and 226; WHO 2007).

Measures: Advisable measures are filtering or avoidance of exhaust fumes from vehicles, power plants, and industry, the switch to renewable energy, traffic reduction, as well as expansion of public transport and bicycle traffic. Benefits of policies which improve air quality often outweigh their costs (up to 20 times; OECD 2008, 260f.).

Annotations: 1 m = 1 micrometre (micron) = 0.001 mm = 10-6 m


Draft (2008)

This draft is to be reviewed by experts. Your hints are welcome, please use the contact form.

Photo credit: © GTZ/Andreas König