Adverse health effects of ambient air pollution


  • Of all air impurities, the fine particles are the most harmful for health. According to an assessment made by the WHO Regional Office for Europe in 2010 in 25 European countries, they advance the death of 350,000 persons by approximately 8 months and cause approximately 100,000 hospitalizations annually.
  • The adverse health effects caused by air pollutants are mainly seen in patients with chronic cardiovascular or pulmonary diseases, including asthma. In these patients, the symptoms are manifested as exacerbations of the primary diseases. Elderly persons are the most susceptible to the effects of air pollutants.
  • Air impurities also to some extent increase the occurrence of respiratory infections and lung cancer, and possibly also allergies, preterm births, low birth weight and neonatal morbidity.
  • Airway mucosal injury is considered to be the main mechanism of action of air impurities.
  • With the exception of malodorous sulphur compounds, acute adverse health effects caused by ambient air pollutants are experienced only in built-up areas where the most hazardous compounds are fine particles, i.e. particles with a diameter of less than 2.5 µm (PM2.5), and nitrogen dioxide.
  • Even if efforts have been made to decrease air impurities in urban areas, long-range transport of airborne pollutants like ozone and fine particles remains a problem.

Sources of emissions

  • Traffic is the most important source in cities and towns (nitrogen dioxide, respirable particles, hydrocarbons, carbon monoxide).
  • Energy production, including separate heating of one-family houses (nitrogen dioxide, sulphur dioxide, respirable particles)
  • Industry (sulphur dioxide, nitrogen dioxide, respirable particles, hydrocarbons, malodorous sulphur compounds, heavy metals)
  • Foreign sources, long-range transport of airborne pollutants (sulphur dioxide, ozone, fine particles, heavy metals)

Health effects

  • Fine particles are the most hazardous air pollutants, and are known to reduce life expectancy at the population level. In patients with cardiovascular or chronic pulmonary diseases there is an increase of symptoms as well as of hospitalizations. Irritation of the nose, throat, eyes and airways, respiratory infections and mild dyspnoea may occur in healthy people as well.
  • Nitrogen dioxide, sulphur dioxide, and ozone (formed in air in reactions of nitrogen dioxide and hydrocarbons) irritate the respiratory tract.
    • The acute effects are a cough, asthma attacks and infections of the respiratory tract.
    • Exacerbations and hospitalizations in patients with cardiovascular diseases and chronic pulmonary diseases like COPD and asthma are increased.
  • Increased concentration of carbon monoxide in red blood cells increases hospitalizations and risk of death among people with cardiovascular diseases.
  • Genotoxic compounds, such as polyaromatic hydrocarbons (PAH) originating from traffic and energy production, increase the risk of lung cancer. Air pollution is estimated to cause 2–3 cases of lung cancer per 100,000 inhabitants annually in cities.
  • Malodorous sulphur compounds, for example mercaptanes and hydrogen sulphide cause acute health effects, such as dyspnoea when occurring in sudden, high concentrations. Long-term effects include irritation of the eyes and respiratory tract, headache, nausea, tiredness and depression.
  • Lead emissions are no longer a significant health problem in countries in which lead-containing fuels for cars have been forbidden. The lowest threshold concentration for toxicity in the central nervous system of foetuses and small children is estimated to be 10 µg/100 ml. The lead blood concentrations among children in the Nordic Countries are below 2–5 µg/100 ml. In the vicinity of foundries and industrial plants using metal the concentrations of lead in vegetables (lettuce, parsley, dill) may be elevated due to contamination by dust emissions.
  • Cadmium originating from metal industry emissions and long-range transportation of particles accumulates in the liver and kidneys of cows and moose. Therefore, abundant use of these organs as food is not recommended.


  • There are national guidelines for the concentrations of sulphur dioxide, nitrogen dioxide, carbon monoxide, benzene, lead, respirable particles (PM10) and fine particles (PM2.5). These are measured in major cities continuously.
  • Directive 2008/50/EC of the European Parliament and of the Council on ambient air quality and cleaner air for Europe has been issued in May 2008.

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