Insights into personal exposure to air pollution. Ben Barratt, King s College London LAQN Seminar, 21 st June 2013

Transcription

1 Insights into personal exposure to air pollution Ben Barratt, King s College London LAQN Seminar, 21 st June 2013

2 Fixed air quality monitoring

3 Air quality modelling

4 The traditional approach to air pollution exposure assessment Single pollutant Outdoor sources Home Exposure Dose Heath Impact Chronic Effects 4

5 Contemporary approach to air pollution exposure assessment Single pollutant Multi pollutant Noise Outdoor sources Location Home Exposure Dose Heath Impact Local Regional Transboundary Acute Effects Chronic Effects Quality of Life 5

6 True/aspirational approach to air pollution exposure assessment A detailed attempt to quantify what an individual breathes Cooking Heating Cleaning Materials Indoor sources Outdoor sources Local Regional Transboundary Building design Ventilation Location Infiltration rate Route Mode Infiltration rate Home Work / School Travel T I M I N G D U R A T I O N B R E A T H I N G R A T E Single pollutant Multi pollutant Noise Exposure Dose Sensitivity Age Ethnicity Heath Impact Acute Effects Chronic Effects Quality of Life 6

7 Is this disconnect important? Perhaps not?: - Air Quality Standards are largely based on epidemiological evidence linking fixed monitoring results to health end points. - At population level this disconnect may not be so important. But, improved exposure estimates should provide: - Stronger epidemiological evidence (reduced uncertainty) - Stronger toxicological evidence - More targeted evidence for emissions control - More targeted evidence for health protection (sensitive individuals) Social justice - the public are entitled to know how they can reduce their own personal exposure to air pollution. 7

8 How do we close the gap? Personal pollution monitors are theoretically capable of measuring what we breathe. We can t give everyone a monitor to carry around for the rest of their lives. A model is theoretically capable of estimating what a population breathes (based on some assumptions). We are all individuals with different behaviours, and how do you know if the estimates are correct? We therefore require a combined monitoring and modelling approach. 8

9 Mobile or personal monitoring

10 Practical limitations of personal monitoring Cost (small cohorts) Battery life (short monitoring periods) Weight/inconvenience (volunteers) Accuracy/precision Data volumes (high temporal resolution) Interpretation 10

11 Common misconceptions 1 A 1:1 calibration curve or co-location against reference method equates to an accurate monitor. A laboratory test does not reflect the complexities of the real world - monitors have to cope with physical abuse, rapid changes in temperature and humidity and an ambient pollutant cocktail. 11

12 Common misconceptions 2 You can map pollution levels in a neighbourhood by wandering around with a monitor for a few hours. 12

13 Common misconceptions 2 You can map pollution levels in a neighbourhood by wandering around with a monitor for a few hours. 13

14 Common misconceptions 3 Standing next to a bus/junction and recording PM 10 levels of 200 µg/m 3 means you re going to die/the AQS is wrong. 14

15 Characterising personal exposure/dose Cooking Heating Cleaning Materials Indoor sources Outdoor sources Local Regional Transboundary Building design Ventilation Location Infiltration rate Route Mode Infiltration rate Home Work / School Travel T I M I N G D U R A T I O N B R E A T H I N G R A T E Single pollutant Multi pollutant Noise Exposure Dose Sensitivity Age Ethnicity Heath Impact Acute Effects Chronic Effects Quality of Life 15

16 Public engagement demonstration study Personal exposure provides an effective way of communicating air pollution issues in an engaging way. Pilot study black carbon and GPS monitors provided to seven volunteers for the same 24 hour period. The results were immediately recognisable and personal. Toddler School pupil Officer worker Home worker Cycle courier Ambulance driver Pensioner 16

17 Travel Central Walk, Tube Travel (lunch) Central Walk Travel Central to Suburban Tube, Rail, Walk Office Central Mechanical ventilation Home Suburban Natural ventilation

18 Travel Central Walk Travel Central Walk Nursery Central Natural ventilation Home Inner Natural ventilation

19 School pupil travelling to/from school Home close to the A2 Bus to school along main roads Walk from school along back roads School in suburban location

20 20 Cumulative BC exposure (7am to midnight)

21 21 Relative importance of each period

22 The London Hybrid Exposure model Combines pollution model outputs with travel behaviour and route data to create a personal air pollution exposure model. 22

23 Hybrid exposure model first steps Box plots of PM 2.5 exposure concentrations during walking, cycling trips in different periods of the day and during car driving in morning rush hours. walk cycle car PM 2.5 exposure concentrations during car trips for various ventilation settings and for two different age cars. 23

24 Personal exposure next steps Development and validation of exposure model. - Integration of additional travel behaviour information to characterise population - Sensitivity testing of model outputs as first validation stage - Validation of outputs against PE measurements Application of model outputs to epidemiological studies. Visualisation of outputs for research and public information. Application of combined modelling/monitoring approach to cohort studies to relate exposure to health end points. Public exposure reduction activities tools and information on how air pollution can be avoided (public meetings, website and route planner). 24

25 Thank you