Active travel: Benefits and trade-offs - Audrey de Nazelle
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Walking and cycling as means of transportation offer convenient and low-cost opportunities to integrate healthy physical activity behaviour in daily patterns of activity. It is thus seen as an essential component of tackling physical inactivity, one of the world’s greatest public health challenges of today. However in urban environments, there may be trade-offs associated with active travel. Pedestrians and cyclists will typically inhale greater amounts of pollutants compared to other mode users in particular. This presentation will review some of the latest research on combined effects of physical activity and pollution, and discuss other potential benefits and trade-offs associated with active travel policies.
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Active travel: Benefits and trade-offs - Audrey de Nazelle
- 1. Active Travel: Benefits and tradeoffs Audrey de Nazelle Routes to Clean Air, IAQM conference Birmingham October 24 2017
- 2. Burden of disease from physical inactivity Coronary heart disease Type 2 diabetes Breast cancer Colon cancer All-cause mortality Global 6% 7% 10% 10% 9% UK 11% 13% 18% 19% 17% Lee et al, Lancet 2012; 380:219-29
- 3. Brazil UK USA Trends in physical activity and time in sedentary behaviour: measured for 2000–2005, forecasted for 2006–2030. Ng & Popkin 2012 Obes Rev China
- 4. • The gobal physical inactivity pandemic • Urban air pollution • Traffic injuries (8th cause of death worldwide, 6 in Western Eu) • Climate change Current major public health challenges International calls for multilevel approaches: planning cities for health Credit: Stockxpert. Active travel policies
- 6. Travel microenvironments, air pollution, and health Travel microenvironments (Barcelona sample, de Nazelle et al. 2013): • Onset of myocardial infarctions (Peters et al., 2013) • Sub-clinical effects (Adar et al., 2007; McCreanor et al., 2007; Strak et al., 2009; Weichenthal et al., 2011, Kubesch et al., 2014a,b ) Time traveling % contribution to NO2 exposure % contribution to NO2 inhalation
- 7. Literature review on exposure contrasts in different modes in Europe: Modes vs background concentrations de Nazelle et al. 2017 Environment International v99, pp151-160 PM2.5 UFP BC CO Walk Walk Walk Walk Cycle Cycle Cycle Cycle Ratio to Background Ratio to Background Ratio to Background Ratio to Background
- 8. Literature review on exposure contrasts in different modes in Europe: Modes vs walk de Nazelle et al. 2017 Environment International v99, pp151-160 Ratio to Walk Ratio to Walk Ratio to Walk Ratio to Walk Cycle Cycle Cycle Cycle Car Car Car Car Bus Bus Bus Bus
- 9. Literature review on exposure contrasts in different modes in Europe: Modes vs Cycle de Nazelle et al. 2017 Environment International v99, pp151-160 Walk Car Car Bus Bus Car Car Bus Bus Walk WalkWalk
- 10. Average concentrations and inhaled doses UFP concentration 0 20000 40000 60000 80000 100000 120000 140000 160000 Walk Bike Bus Car pt/cm3 Inhaled UFP in one hour 0 10 20 30 40 50 60 70 Walk Bike Bus Car pt Trip "Resting" Inhaled UFP in 24 hours 0 50 100 150 200 250 300 350 Walk Bike Bus Car pt Trip "Resting" IR (L/min) Trip time (min) Walk 23 49 Bike 37 24 Bus 10 34 Car 10 28 de Nazelle et al. 2012 Atmospheric Environment. 59:151-159; 2012
- 11. AP and PA: Experimental studies TAPAS experimental study Case crossover, 28 volunteers - Benefits of cycling on respiratory and cardiovascular outcomes even at high air pollution levels - Exercise may protect against acute adverse effects of air pollution - Difficulty of disentangling effects Exercise improves the same physiological mechanisms that air pollution deteriorates (Kubesch et al. 2014 European Journal of Preventive Cardiology; Kubesch et al. 2014 Occupational Environmental Medicine; Cole-Hunter et al. 2015 J of Exposure Science and Environmental Epidemiology; Matt et al. 2016 Environment International )
- 12. Air pollution and physical activity • TAPAS epidemiologic analysis (Andersen et al. 2015 Environmental Health Perspectives): • Danish Diet Cancer and Health Cohort (52 061 members, NO2 concentration at home address) • Benefits of outdoor physical activity outweigh risks associated with air pollution exposure • Some benefits may be attenuated when exposed to high levels of NO2 (for respiratory mortality, benefits of physical activity are halved in high air pollution vs low air pollution, but it is still beneficial to be physical active) Photo: Gil Garcetti Photo: Gil Garcetti ©
- 13. Air Pollution Mortality / morbidity Physical Activity Traffic Incidents Walking and Cycling Policies/Scenarios Health impact assessment models of active travel Rojas-Rueda et al. BMJ 2011, Environment International 2012, Preventive Medicine 2013, PLoS One 2016; Rabl and de Nazelle Transport Policy 2012;
- 14. HIA Example: Barcelona BICING case study Inaugurated March 2007 In 2009: 182 000 subscribers 6000 bikes 425 stations
- 15. Results: mortality in new cyclist population Air pollution Traffic mortality physical activity Relative Risk Bike vs Car 1.002 1.0007 0.80 Attributable fraction of mortality 0.002 0.0007 -0.23 Deaths / year +0.13 +0.03 -12.46
- 16. - Current Altmetric score 1122: best score over all articles ever published in Preventive Medicine - In the top 1% of all research outputs ever tracked by Altmetric
- 17. PA: Non-linear dose-response PM: Linear dose-response For a given level of air pollution, is there a tipping beyond which additional physical activity does not bring additional benefits, and a “break-even” point beyond which additional physical activity brings greater risks?
- 18. Delhi, 153 µg/m3 of PM2.5 Cycling a risk after 60 min of cycling per day London, 16 µg/m3 of PM2.5 Active travel always beneficial WHO Ambient Air Pollution Database, 2014. When risks become higher than benefits: Cycling
- 19. scenario PM2.5 concentration % reduction Deaths/year attributable to Air pollution General population physical activity Traffic mortality Air pollution travellers 20% in-city car trip reduction, all replaced by biking 0.32 -5 -33.73 0.08 0.57 Air pollution benefits of active travel? Rojas-Rueda et al. Environment International 49 (2012) 100-109 Changes in air pollution and deaths/year for transport scenarios in Barcelona
- 20. scenario physical activity Air pollution Traffic mortality TOTAL increased active travel -528 -21 +11 -538 lower carbon emission vehicles 0 -17 0 -17 Co-benefits of climate change strategies Woodcock et al. (2009) Comparison of GHG emission policy scenarios in London: death per million people Woodcock et al. 2009 The Lancet , v3674, 9705: 1930-1943 And take a holistic approach…
- 23. Potential co-benefits of planning strategies… Estimated preventable deaths under compliance with exposure recommendations by exposure domain in Barcelona, Spain. Mueller et al Urban and Transport Planning Related Exposures and Mortality: A Health Impact Assessment for Cities EHP June 2016
- 24. Conclusion: Air pollution in cities- can the problem become an opportunity? Air pollution needs to be tackled, and it offers huge opportunities for co-benefits with appropriate planning strategies Thank you! Audrey de Nazelle - anazelle@imperial.ac.uk
- 25. Extra slides
- 26. AP-PA epidemiologic analysis Danish Diet, Cancer and Health (DCH) cohort 57,053 subjects (age 50-65 years), Copenhagen and Aarhus Questionnaire in 1993-1997 (baseline) Central Population Registry, residential address history since 1971 Linkage with Cause of Death Register between baseline and 31.12.2009 (overall, cardiovascular, respiratory, and diabetes mortality ) Physical activity (walk, bike, gardening, sports…) Air pollution exposure at residence annual means of NO2 / NOx Andersen et al. A study of the Combined Effect of PA and AP on Mortality in Elderly Urban Residents…Environmental Health Perspectives 123, 6, 2015
- 27. Overall Mortality (n = 5,534) Cardiovascular Mortality (n = 1,285)
- 28. Respiratory (COPD, Asthma) Mortality (n = 354) Diabetes Mortality (n = 122)
- 29. During the past decade, e-bike ownership has grown from near-zero to ∼2× greater than CVs. Ji et al. Environ. Sci. Technol. 2012, 46, 2018-2024. Motorization and electricity use in China normalized to population.
- 30. Comparison of emissions and environmental health impacts from the use of conventional vehicles and electric vehicles in 34 majors cities in China Emissions: station-to- wheel • emission factors from conventional vehicles (CV) and electricity generation units (EGU) varying along 15 regional electricity grids Ji et al. Environ. Sci. Technol. 2012, 46, 2018-2024. • Intake Fraction = 𝑻𝒐𝒕𝒂𝒍 𝑰𝒏𝒕𝒂𝒌𝒆 𝑻𝒐𝒕𝒂𝒍 𝑬𝒎𝒊𝒔𝒔𝒊𝒐𝒏𝒔 – Accounts for population, land area, average breathing rates, wind speed, mixing heights • Dose-response function from the literature (for health impact)
- 31. Ji et al. Environ. Sci. Technol. 2012, 46, 2018-2024.
- 32. PM2.5 mortality risk per 1010 passenger-km, for the 34 cities considered. Icon size is proportional to city population. In each plot, “R” is the population- weighted average ratio between x- and y-axes, “P” is the proportion of the population (among the 34 cities) for which the mortality risk is lower for EVs than for CVs. For reference, dashed lines are 1:1 lines. The population- weighted average value is indicated with an asterisk. Ji et al. Environ. Sci. Technol. 2012, 46, 2018-2024.
- 33. Portion of primary PM2.5 health impacts from EGUs experienced by rural versus urban populations. Icon area is proportional to PM2.5 emission factor (g km–1) for an EV in that power grid. Numbers identify nonurban mortality impact proportions, i.e., of the total mortality impacts attributable to primary PM2.5 from electricity generation – here, owing to urban use of EVs. Urban use of EVs rather than CVs typically moves the emissions (and, exposures and health impacts) to more rural locations. In general, a substantial proportion – on average, about half – of the emissions from urban use of EVs are inhaled by nonurban populations. Ji et al. Environ. Sci. Technol. 2012, 46, 2018-2024.
- 34. Global Burden of Disease 2010: top risk factors Lim et al. The Lancet 2012 # 10 worldwide # 9 worldwide