WHO European Centre for Environment and Health

1. WHO European Centre for Environment and Health TASK FORCE on Integrated Assessment Modelling (29th Session, Amiens, 10-12 May 2004) Results from the 7th joint WHO UN-ECE TF on Health meeting Jürgen Schneider Project Manger WHO ECEH, Bonn, Germany

2. WHO European Centre for Environment and Health TASK FORCE on Integrated Assessment Modelling (29th Session, Amiens, 10-12 May 2004) • Content: • WHO Systematic Review • 7th meeting of the TF on Health • Recommendations for ozone • Recommendations for PM • Follow up

3. WHO European Centre for Environment and Health Systematic Review - Products • Published reports: • Health aspects of air pollution with particulate matter, ozone and nitrogen dioxide • Meta analysis of time-series studies and panel studies op particulate matter and ozone • Health aspects of air pollution – answers to follow-up questions form CAFE • In preparation: • Impact of air pollution on children’s health (to be published Sept 2004) • Short summary report (June 2004)

4. WHO European Centre for Environment and Health 7th Meeting of the TF Health • Purpose: • Develop recommendations on the approach to model health impacts within RAINS • Health impact assessment: • Science-based • No cookbook approach yet • Several assumptions and choices – transparency is needed • ‚Conservative approach‘ - estimates are ‚at least‘ • CBA complementory

5. WHO European Centre for Environment and Health Ozone • Ozone effects: • Health endpoint: attributable mortality • Causal relationship between ozone exposure and mortality • Independent of PM • RR from WHO meta-analysis of European studies: The relative risk for all-cause mortality is 1.003 (C.I. 1.001, 1.004) for a 10 µg/m3 increase in the daily maximum 8-hour mean.

6. WHO European Centre for Environment and Health Ozone Results from the meta-analysis – RR and summary estimate

7. WHO European Centre for Environment and Health Ozone • Ozone effects: • A linear concentration response function is assumed. • The principle metric for assessing effects of ozone on mortality should be the daily maximum eight-hour mean. • Current evidence is insufficient to derive a level below which ozone has no effect on mortality. • The use of a cut-off for IAM at 35 ppb is recommeded

8. WHO European Centre for Environment and Health Systematic Review - Process

9. WHO European Centre for Environment and Health Ozone • It is likely that the overall effects of ozone are underestimated by this approach. • Sophisticated statistical analysis applied to address the question of thresholds for PM have not been applied to the same degree for O3 • There remain uncertainties about the shape of the CR function, in particular at the lower end of the ambient range • Although there is evidence that associations exist below the current guideline value, the confidence in the existence of associations with health outcomes decreases as concentrations decrease. • 20 to 40 ppb is the hemispheric background • There are difficulties of state-of-the-art dispersion models to simulate low ozone situations in urban areas. • Titration becomes important at low levels

10. WHO European Centre for Environment and Health Ozone • This recommendation is based on the application of a very conservative approach for integrated assessment modelling and takes account of uncertainties in relation to the evidence in health studies. • Therefore, it was recommended to make a sensitivity analysis applying no cut-off. This estimate would outline an upper estimate of the attributable effects of ozone on mortality. • The Task Force also stressed that the approach did not yield an overall quantification of all effects related to exposure to ozone. Important effects which were currently not covered, but should eventually be taken into account in any cost benefit analysis, included morbidity outcomes.

11. WHO European Centre for Environment and Health Particulate matter • PM effects: • Use annual mean of PM2.5 as indicator for PM related mortality • RR from cohort study • Linear CR function • Health outcome: Reduction of life expectancy • Effect for explained anthropogenic contribution only • ‘Most epidemiological studies on large populations have been unable to identify a threshold concentration below which ambient PM has no effect on mortality and morbidity. It is likely that within any large human population, there is a wide range in susceptibility so that some subjects are at risk even at the low end of current concentrations.’

12. WHO European Centre for Environment and Health Particulate matter • One factor for different PM constituents: • Epi studies: Combustion sources are particularly important for health effects. • Tox studies: • Primary, combustion-derived particles have a higher toxic potency. These are often rich in transition metals and organics, in addition to their relatively high surface area • Other single components of the PM mix are lower in toxicity in laboratory studies e.g. ammonium salts, chlorides, sulphates, nitrates and wind-blown crustal dust such as silicate clays. • Despite these differences among constituents studied under laboratory conditions, it is currently not possible to quantify the contributions from different sources and different PM components to health effects from exposure to ambient PM.

13. WHO European Centre for Environment and Health Systematic Review – key findings • Follow-up actions • Finalisation of the reports for WHO Systematic Review • Dissemination of main results • Prepare report on risk of PM and ozone from LRTAP • Revision of WHO Air Quality Guidelines (PM, ozone)

14. WHO European Centre for Environment and Health TASK FORCE on Health Seventh Session, Bonn, 6-7 May 2004 • For further information see: • http://www.euro.who.int/air Thanks!

15. WHO European Centre for Environment and Health Systematic Review – key findings • Relevance of exposure at hot spots; exposure to peaks- Hot-spot versus urban background

16. WHO European Centre for Environment and Health Systematic Review – key findings • Relevance of exposure at hot spots; exposure to peaks- Hot-spot versus urban background • However, some studies have documented that subjects living close to busy roads experience more short-term and long-term effects of air pollution than subjects living further away. In urban areas, up to 10% of the population may be living at such “hot spots”. The public health burden of such exposures is therefore significant. Unequal distribution of health risks over the population also raises concerns of environmental justice and equity.

17. WHO European Centre for Environment and Health Systematic Review – key findings • Consistency of epi and tox evidence in the defining thresholds - General remark • For a uniform population with specific exposures, thresholds for certain pairs of pollutant/health endpoints may be detectable • At a population level, susceptibility and exposure vary over a wide range. Large differences in individual exposure-response curves may lead to a disappearance of thresholds at a population level. • Taking into account these differences, the evidence coming from the epidemiological and toxicological studies is not contradictory.

18. WHO European Centre for Environment and Health Systematic Review – key findings • Consistency of epi and tox evidence in the defining thresholds - PM • Most epidemiological studies on large populations have been unable to identify a threshold concentration below which ambient PM has no effect on mortality and morbidity. It is likely that within any large human population, there is a wide range in susceptibility so that some subjects are at risk even at the low end of current concentrations.

19. WHO European Centre for Environment and Health Systematic Review – key findings • Consistency of epi and tox evidence in the defining thresholds – PM long term studies • Abrahamowicz et al. (2003) on ACS: • “…our… estimates of the adjusted effect of fine particles on all cause mortality indicated a stronger relationship in the lower (up to approximately 16 µg/m3) than in the upper range of values. This is similar to findings of other studies ... In general our results reinforce the growing body of evidence against the hypothesis of a putative threshold below which exposure to fine particles does not affect public health. The lack of thresholds for fine PM was consistently reported in various studies... • In contrast, analyses of sulfates suggested a threshold might exist at about 12 µg/m3

20. WHO European Centre for Environment and Health Systematic Review – key findings • Consistency of epi and tox evidence in the defining thresholds - Ozone: • Statistical significant associations between ozone and mortality have been demonstrated at places with low ozone levels • Sophisticated statistical analysis applied to address the question of thresholds for PM have not been applied to the same degree for O3 • There remain uncertainties about the shape of the CR function, in particular at the lower end of the ambient range • Although there is evidence that associations exist below the current guideline value, the confidence in the existence of associations with health outcomes decreases as concentrations decrease.

21. WHO European Centre for Environment and Health Systematic Review – key findings • Consistency of epi and tox evidence in the defining thresholds - Ozone: • A recent paper (Kim et al., 2004) applied a linear model, a natural spline model and a threshold model to a dataset in Seoul and found that the threshold model, with a threshold at 56 µg/m3 (28 ppb) 1 hour average, gave the best fit. However, the slope above the threshold was steeper than in the linear model so the threshold model did not necessarily predict a lower health impact.

22. WHO European Centre for Environment and Health Systematic Review – key findings • Contribution of different sources to PM related health effects • Epi studies: Combustion sources are particularly important for health effects. • Tox studies: • Primary, combustion-derived particles have a higher toxic potency. These are often rich in transition metals and organics, in addition to their relatively high surface area • Other single components of the PM mix are lower in toxicity in laboratory studies e.g. ammonium salts, chlorides, sulphates, nitrates and wind-blown crustal dust such as silicate clays. • Despite these differences among constituents studied under laboratory conditions, it is currently not possible to quantify the contributions from different sources and different PM components to health effects from exposure to ambient PM.

23. WHO European Centre for Environment and Health Systematic Review – key findings • Coarse particles and health • There is limited evidence that coarse particles are associated independently of PM2.5 with mortality in time series studies. • One study has investigated the effect of long-term exposure to coarse particles on life expectancy without producing evidence of altered survival. • There is evidence that coarse particles are independently associated with morbidity endpoints such as respiratory hospitalizations in time-series studies. • There is sufficient concern about the health effects of coarse particles to justify their control.

24. WHO European Centre for Environment and Health Systematic Review – key findings • Effects of air pollution on children’s health • There are several factors which potentially increase children’s susceptibility to adverse effects of air pollution • There is evidence for effects of air pollution (PM) on infant mortality • Poor air quality effects lung development of children • Air pollution is associated with increased upper and lower respiratory symptoms in children • Air pollution may increase bronchitis, cough and aggravates asthma symptoms • There are still uncertainties whether ambient air pollution at current levels causes cancer in children

25. WHO European Centre for Environment and Health Systematic Review – key findings • 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.

26. WHO European Centre for Environment and Health Systematic Review – key findings • Follow-up actions • Finalisation of the reports • Dissemination of main results • Keep contact with CAFE • Revision of WHO Air Quality Guidelines (PM, ozone)

27. WHO European Centre for Environment and Health TASK FORCE on Health Seventh Session, Bonn, 6-7 May 2004 • For further information see: • http://www.euro.who.int/air Thanks!