Science to policy

Experts Symposium on Air quality

Hong Kong 10th January 2009

Ross AndersonSt George’s, University of London

From science to policy

1. Hazard identification2. Exposure-response3. Health impact assessment for specified

exposure scenarios (risk characterization)4. Cost-benefit and cost effectiveness5. Development of air quality strategy6. Implementation of appropriate measures7. Evaluation of benefits (“accountability”)

Various paradigms: NRC 1983, WHO 2000

Updates of WHO guidelines

Year PM measure GuidelineAnnual mean

µg/m3

Notes

1970s SPM 60-90 Threshold(Lowest observed level for healtheffects ~ 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.

3PM10 ~ 0.5 x SPM; 2 x BS; 1.3 x PM2.5

Long term exposure to PM and risk of mortalityin ACS cohort (~ 0.5 million people in a largenumber of US cities followed for 16 years)

4

Adapted from Pope et al 2002

Annual meanlevel

PM10(µg/m3)

PM2.5(µg/m3)

Basis for the selected level

Interim target-1(IT-1)

70 35 Levels associated with about15% higher long-term mortalitythan at AQG

Interim target-2(IT-2)

50 25 Risk of premature mortalitydecreased by approximately6% compared to IT1

Interim target-3(IT-3)

30 15 Mortality risk reduced byapproximately 6% compared toIT2 levels.

Air qualityguideline(AQG)

20 10 Lowest levels at which total,CP and LCA mortality havebeen shown to increase (Popeet al., 2002). The use of PM2.5guideline is preferred.

WHO AQG: Global update 2005

PassinginterimtargetsonthewaytowardsAQGPassinginterimtargetsonthewaytowardsAQG

Exposure

Effect

AQG IT-2 IT-1

Implications of no threshold

ConcentrationResponse

Implementation of exposure reductionconcept for PM2.5 in the UK

Health based, and quantified by cost-benefitanalysis

1. 15% reduction in average annual urbanbackground concentrations 2010 - 2020

2. Backstop objective (concentration cap) of25µ/m3 applicable to all areas. To provideminimum protection.

8The Air Quality Strategy for England, Scotland, Wales and N Ireland, 2008