Air Pollution

3. General Conclusions

      3.1 Recommendations
      3.2 Other aspects to address in the development of air pollution policy in Europe
      3.3 Concluding remarks

3.1 Recommendations

WHO states: "The ultimate goal of any clean air policy is to develop strategies to reduce the risk of adverse effects on human health and the environment as a whole caused by ambient air pollution. With the existence of very susceptible populations and the ability to detect effects even if they are infrequent, we may be confronted with situations when the concept of thresholds is no longer useful in setting standards to protect public health. The principle of eliminating adverse effects with an adequate margin of safety even for the most susceptible groups may not be realistic. However, risk reduction strategies are and will continue to be powerful tools in promoting public health. The development of such strategies requires not only qualitative, but also quantitative knowledge on the most relevant adverse effects.

Therefore, the working group recommended, as a follow up of this work, a meta-analysis using the bibliographic database developed at the St George’s Hospital Medical School. This meta-analysis should be guided by a small task group and should derive updated cause-specific risk coefficients for the following health endpoints, which can also be used in subsequent health impact assessments:

Ozone

• Mortality short-term: all causes all ages
  
• Respiratory hospital admissions: adults, children, elderly
  
• Symptom exacerbation in asthmatics

PM (PPM_2.5; coarse; BS; PM₁₀)

• Mortality short-term
  
• Hospital admissions/Emergency room visits

The working group also recommended

• an update of the concentration-response table for O₃ in the current WHO AQG, which is based on controlled exposure, considering lung function and inflammation under new evidence and
  
• an identification of those risk coefficients to be used within CAFE to estimate long term mortality in relation to PM exposure.

In addition, the working group noted that the recommendation to use PM_2.5 as indicator for PM- related health effects does not imply that PM_2.5 is the only relevant parameter to characterize PM pollution. Therefore, it was recommended to set up a more comprehensive monitoring programme in different European cities (possibly including PM₁₀, PM_2.5, PM₁, BS, PM composition, gases), which, in combination with properly designed health studies, could lead to an additional gain in knowledge on the health effects of ambient air pollution in the coming years."

Source & © : WHO Regional Office for Europe "Health Aspects of Air Pollution" (2003), Chapter 8 Recommendations: follow up actions

3.2 What other aspects of air pollution are important to address in the development of air pollution policy in Europe?

WHO states: "The main purpose of this survey was therefore to identify any important issues related to health effects of air pollution in Europe, which are currently not adequately addressed by WHO Air Quality Guidelines and/or the European Commission’s Clean Air for Europe programme.

Based on advice by the SAC, WHO decided to conduct a small survey among a wide range of experts to get additional views on this item. Experts were invited to highlight important aspects that are currently not addressed adequately in the development of air pollution policy in Europe. In agreement with the header under which this question was received (“On substances and pollutants that have not yet been addressed”), it was mentioned that this could be linked to pollutants or exposure situations posing risk to health in Europe and not covered by the present regulations, or those for which new scientific information warrants re-evaluation of the available risk assessment. A copy of the letter that was sent to the experts can be found in Annex 3.

Roughly 10% of the experts that were contacted replied. Pollutants highlighted by experts include the following.

• The “classical” air pollutants carbon monoxide and sulphur dioxide. As a justification, it was indicated that new epidemiological studies revealed an association of these pollutants with severe health effects, which are not necessarily adequately reflected in the current WHO Air Quality Guidelines for Europe.
  
• Persistent organic pollutants (POP) such as PAH. For example, a recent assessment (United Kingdom Committee on Carcinogenicity, 2003) of the contribution of dibenzo[al]pyrene to the overall carcinogenic potential of PAH has caused concern about this substance. Dioxins, nitro-PAH and nitro-oxy-PAH were also mentioned.
  
• Heavy metals, in particular lead and some transitional metals. Lead was of concern since there are new studies suggesting effects at low concentrations.
  
• Carcinogenic volatile organic species 1.3-butadiene and benzene
  
• Nitrogen trichloride, since there is evidence of health effects from this substance from epidemiological studies.

Few experts suggested to assess the health effects from diesel versus gasoline exhaust emissions.
The Working Group has also pointed out the unresolved issue of the combined effects of urban air pollution mix and its combined effects on health."

Source & © : WHO Regional Office for Europe Health Aspects of Air Pollution
- answers to follow-up questions from CAFE (2004), Section 9

3.3 Concluding remarks

WHO states: "The working group agrees on the following general statements in response to the questions by the European Commission.

• The body of evidence on health effects of air pollution at levels currently common in Europe has strengthened considerably over the past few years; both epidemiological evidence and toxicological evidence has contributed to this strengthening; the latter provides new insights into possible mechanisms for the hazardous effects of air pollutants on human health and complements the large body of epidemiological evidence.
  
• The evidence is sufficient to recommend strongly further policy action to reduce levels of air pollutants including PM, NO₂ and ozone; it is reasonable to assume that a reduction of air pollution will lead to considerable health benefits.

The present assessment represents the state-of-the-art understanding of the existing science. Further substantial reduction of the existing uncertainty will only be achieved by further targeted research and its subsequent systematic evaluation. The working group requests the European Commission and national funding authorities to make the necessary resources available to ensure that the outstanding questions can be addressed effectively to continuously support the political process of reducing the impact of environmental factors on human health."

Source & © : WHO Regional Office for Europe Health Aspects of Air Pollution
- answers to follow-up questions from CAFE (2004), Section 10