Civic Exchange 2009 The Air We Breathe Conference - WHO Guidelines & How
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Civic Exchange 2009 The Air We Breathe Conference - Experts Symposium 9 January 2009 WHO Guidelines & How presented by Ross Anderson (St George's, University of London) http://air.dialogue.org.hk
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Civic Exchange 2009 The Air We Breathe Conference - WHO Guidelines & How
- 1. WHO Guidelines & How The Air We Breathe: a public health dialogue Hong Kong 10th January 2009 Ross Anderson St George’s, University of London
- 2. Some questions • What are the guidelines? • How were they developed? • Why have they been updated? • What are their uses and limitations? • Implications for policy in Hong Kong? 2
- 3. WHO AQG: Global update 2005 Pollutant Averaging time AQG value Particulate matter PM2.5 1 year 10 µg/m3 24 hour (99th percentile) 25 µg/m3 PM10 1 year 20 µg/m3 24 hour (99th percentile) 50 µg/m3 Ozone, O3 8 hour, daily maximum 100 µg/m3 Nitrogen dioxide, NO2 1 year 40 µg/m3 1 hour 200 µg/m3 Sulfur dioxide, SO2 24 hour 20 µg/m3 10 minute 500 µg/m3
- 4. WHO AQG: Global update 2005 Annual mean PM10 PM2.5 Basis for the selected level level (µg/m3) (µg/m3) Interim target-1 70 35 Levels associated with about (IT-1) 15% higher long-term mortality than at AQG Interim target-2 50 25 Risk of premature mortality (IT-2) decreased by approximately 6% compared to IT1 Interim target-3 30 15 Mortality risk reduced by (IT-3) approximately 6% compared to IT2 levels. Air quality 20 10 Lowest levels at which total, guideline CP and LCA mortality have (AQG) been shown to increase (Pope et al., 2002). The use of PM2.5 guideline is preferred.
- 5. Passing interim targets on the way towards AQG Effect Exposure AQG IT-2 IT-1
- 6. WHO AQG Working Group
- 7. Systematic evaluation of epidemiological evidence. WHO guideline document Recommendations on Health Hazard Characterization: 1) Develop protocol for the review 2) Identify relevant studies http://www.euro.who.int/document 3) Systematically assess the validity of each study /e68940.pdf 4) Conduct systematic overview of evidence from multiple studies: the use of meta-analysis 5) Draw conclusions from epi evidence - critical scientific thinking - document the process of scientific reasoning
- 8. Updates of WHO guidelines Year PM measure Guideline Notes Annual mean µg/m3 1970s SPM 60-90 Threshold (Lowest observed level for health effects ~ 150 + Safety factor of 2) 1987 Black Smoke 50 Threshold (linked to SO2, also 50) 2000 PM10 Dose-response No threshold 2006 PM10 20 No threshold 2006 PM2.5 10 No threshold. Hong Kong RSP 55 Threshold 1987 PM10 = RSP ~0.5 x 8 SPM; 2 x BS; 1.3 x PM2.5
- 9. Published time-series studies of air pollution up to 2006 (Source: APED) Cohort studies Number of publications 70 60 WHO 1987 GL 50 40 30 20 10 0 00 03 91 97 82 85 88 94 73 76 79 20 20 19 19 19 19 19 19 19 19 19 Year of publication All ETS Multi-city All Panels July 06 9
- 10. Shifts in knowledge since the 1980s • No threshold for health effects in the ambient range • Effects extend beyond the respiratory system. • Cardiovascular effects may be the most important.
- 11. Long term exposure to PM and risk of mortality in ACS cohort (~ 0.5 million people in a large number of US cities followed for 16 years) Adapted from Pope et al 2002 11
- 12. Dose Response between Total Mortality and PM10 20 15 Percent Increase in Deaths PM10 and daily 10 mortality: 22 5 European cities. 0 -5 0 50 100 150 200 Samoli et al 2005 PM10 (ìg/m3) Ozone and daily mortality: 21 European cities. Gryparis et al 2004
- 13. How should the guidelines be used?
- 14. Guidelines are not enforceable standards/limit values • Guidelines: – Recommendation on protection of health or environment from adverse effects of pollutants • Standard: – Concentration (exposure level) of the pollutant determined by the regulatory authority as enforceable – Instruments for implementation (monitoring and reporting requirements, consequences of non- compliance, …) 14
- 15. Threshold assumption is a critical issue Threshold: Implies safe level. Suited to standards, limit values. Non-threshold: Implies no safe level. Suited to population exposure reduction.
- 16. Implications of no threshold Concentration Response
- 17. Implementation of exposure reduction concept for PM2.5 in the UK (within the European framework) Health based, and quantified by CBA 1. 15% reduction in average annual urban background concentrations 2010 - 2020 2. Backstop objective (concentration cap) of 25 µg/m3 applicable to all areas. To provide minimum protection. 17 The Air Quality Strategy for England, Scotland, Wales and N Ireland, 2008
- 18. Implications for Hong Kong Q 1. Does the evidence underlying the GL apply to Hong Kong? Q 2. Should Hong Kong adopt these GL as standards? Q 3. If not, why not?
- 19. % increase in hospital admissions for respiratory disease ages 65+ associated with a 10 μg/m3 increase in pollutant 0.7 (Wong et al, 2002) 0.6 0.62 0.46 0.49 0.5 Percent Increase 1.8 0.4 1.6 HK London 0.3 0.2 1.4 0.1 1.2 0 US(90 Cities)* Eur(21 Cities)* Asia (4 Cities) 1 0.8 0.6 % increase in daily mortality 0.4 associated with 10µg/m3 PM10 (HEI 2004) 0.2 0 19 N O2 O3 PM SO2
- 20. Hong Kong and London Some similarities • Size and population • Toxicity of pollution • Large regional contribution to pollution • Baseline health status • Wealth, education and technical capacity 20
- 21. 0 50 100 150 200 250 Karachi NewDehli Katmandu Dhaka Kol Kata Shanghai Beijing Gangzhou HCMC Asia Mumbai Colombo Busan IT1 Seoul Manila Bangkok Taipei HongKong Tokyo Lima Arequipa Medellin Fortaleza Santiago Bogota Hong Kong Cochabamba San Salvador Guatemala city Latin IT2 Havana city Mexico City Quito Rio de Janeiro LaPaz Sao Paulo San Juan Bello Horizonte selected cities worldwide Cairo Vereenigen Johannesburg Africa CapeTown IT3 Prag Torino Bucharest Barcelona Milano Roma Krakow Berlin Erfurt Oslo Palermo Sevilla Annual average PM10 concentrations (µg/m3) Bologna Helsinki Budapest Florence Hamburg Europe Vienna Warsaw Munich AQG level Amsterdam Køln Geneva Basel Zurich Copenhagen London Athens Leeds Brussels London Stockholm SanDiego StLouis LosAngeles Annual average PM10 concentrations observed in Knoxville Houston Pittsburg Dallas N.Amer Memphis Oklahoma Washington New York Seattle
- 22. Hong Kong differs from London • Sources: – Local: e.g. more power generation and marine sources – Greater regional component • Not embedded in a regional strategy • Objectives are not based on adequate protection of public health • It is not setting a challenging standard which is possible based on best current knowledge and technology • No effective legal framework to enforce compliance with standards 22
- 23. Summary (1) • The GL comprise recommendations for the protection of health from adverse effects of pollutants. • They are a basis for the development of national health-based standards. • Updated evidence suggests that air pollutants should now be considered as non-threshold hazards. • This means that reductions in exposure across the whole population will bring the greatest health benefits.
- 24. Summary (2) • The effects of air pollution in Hong Kong are likely to be similar to those in other cities. • National or Local strategies must take individual circumstances into account, and Hong Kong is no exception • For local and regional strategies to work, political will and appropriate enforcement are required.
- 25. Thanks