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Measuring Urban Bicyclists' Uptake of Traffic-Related Pollution

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Alex Bigazzi, Portland State University

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Measuring Urban Bicyclists' Uptake of Traffic-Related Pollution

  1. 1. Measuring Bicyclists’ Uptake of Traffic-Related Air Pollution Alex Bigazzi PSU Transportation Seminar Feb. 28, 2014 Miguel Figliozzi Jim Pankow Wentai Luo Lorne Isabelle Urban Bicyclists' Pollution Uptake 1
  2. 2. Bicycle & Health Promotion Exercise Public Health Pollution Crashes Exposure/ Dose Emissions Urban Bicyclists' Pollution Uptake 2
  3. 3. Framework 3 Adapted from Ott, Stieneman & Wallace, 2007 Vehicle Emissions Air Quality Traveler Inhalation Exposure Uptake Health Effects Urban Bicyclists' Pollution Uptake
  4. 4. Outline Lit. review & early results: 1. Exposure concentrations 2. Inhalation 3. Uptake doses 4. Health effects Urba n Bicyclists' Pollution Uptake 4
  5. 5. Traveler Exposure Bicyclists’ Exposure to Air Pollution Urban Bicyclists' Pollution Uptake 5
  6. 6. Bicyclists’ Exposures 6 42 studies 0.5 – 13 ppm 5 – 88 μg/m3 0 5 10 15 20 NO2 VOC CO Black Carbon Coarse PM Fine PM Ultrafine PM # studies measuring on-road bicyclists’ exposure concentrations Pollutant 9k – 94k pt/cc Urban Bicyclists' Pollution Uptake 3 in U.S. since 1970’s
  7. 7. Modal Comparisons of Exposure • Majority of bike exposure research • Inconsistent results – Bicyclists lower if separated • Inconsistent comparisons – Available bicycle facilities & routes • Exclude other modal factors – Origins & destinations, weather… Urban Bicyclists' Pollution Uptake 7
  8. 8. High-Traffic/Low-Traffic Routes 250% 200% 150% 100% 50% 0% -50% N=6 N=11 N=8 N=6 N=3 N=5 CO VOC UFP PM2.5 PM10 BC Exposure Increase on High-Traffic Routes Urban Bicyclists' Pollution Uptake 8
  9. 9. Urban transportation system Bicyclists’ uptake of air pollution PSU Bike Exposure Research Going beyond bike versus car. How can we reduce exposure risks for bikers? Urban Bicyclists' Pollution Uptake 9
  10. 10. Sampling Equipment CO Cameras TVOC CO2 Sampler Pump Breath Bags Cycle computer Sample Cartridge Smart phone PM ACE Device Urban Bicyclists' Pollution Uptake 10
  11. 11. The Portland ACE Portable, Low-cost and Networked Device for Assessing Cyclists’ Exposure Urban Bicyclists' Pollution Uptake 11
  12. 12. On-Road Sampling Urban Bicyclists' Pollution Uptake 12
  13. 13. 13 Exposure Data coverage Urban Bicyclists' Pollution Uptake ~40 hours of data over 13 days
  14. 14. Exposure Early Results Major Arterials Minor Arterials Local Roads I-205 Path 0% 50% 100% 150% 200% 250% 300% Benzene Toluene Ethylbenzene m,p-Xylene Concentration Increase (over Tabor) Urban Bicyclists' Pollution Uptake 14
  15. 15. Bicyclists’ Inhalation Doses 15 Inhalation Urban Bicyclists' Pollution Uptake
  16. 16. Inhalation Exposure Conc’n Respiration Duration Intake Dose 16 mg/ m↑3   m↑3 /sec  sec mg 푉↓푇  × 푓↓퐵  Urban Bicyclists' Pollution Uptake ( breaths/ sec ) ( m↑3 /breath )
  17. 17. Respiration and Exercise • Ventilation strongly related to workload and heart rate • ln⁠( 푉↓퐸 ) =푎+푏∙퐻푅 – 푅↑2 ≈0.97 Mermier et al. (1993) 50 Ventilation 25 (VE) 90 120 Heart Rate (HR) Urban Bicyclists' Pollution Uptake 17
  18. 18. Bicyclists’ Exertion • External work – Speed & acceleration – Weight & slope – Wind & drag – Rolling resistance (tires, road) • Personal factors (minor effects) – Basal metabolic rate – Fitness (exercise response) Urban Bicyclists' Pollution Uptake 18
  19. 19. Respiration & Bicycle Studies 19 57 studies assess bicyclists’ exposure Ignored 38 Constant 16 Assumed 7 Modeled 8 Measured 1 Variable 3 Modeled 2 Measured 1 Respiration: Urban Bicyclists' Pollution Uptake
  20. 20. Bicyclists’ Respiration 5 4 All Men Women Traveler Respiration Bicycle Speed (mph) 3 2 1 0 0 5 10 15 20 Ratio of Bicycle/Motorized Urban Bicyclists' Pollution Uptake 20
  21. 21. Modal Comparisons of Intake • Bicyclists’ respiration 2-5x higher than passengers • Often longer duration • Greater intake doses for bicyclists • Respiration is a major factor for dose Urban Bicyclists' Pollution Uptake 21
  22. 22. Modal Comparisons of Dose 60% 40% 20% 0% -20% -40% -60% -80% -100% Pedestrian Car/Taxi Bus Difference from Bicyclist Dose CO UFP PM2.5 N (3) (3) (5) Urban Bicyclists' Pollution Uptake 22
  23. 23. Duration vs. Respiration • For active modes (bike/ped), speed: Respiration Duration • Duration dominates: faster travel reduces intake / mile Urban Bicyclists' Pollution Uptake 23
  24. 24. PSU Research • Second-by-second on-road respiration rate & amplitude • 8% correlation between 1-second TVOC and breathing rate – Bad for intake doses – Missed with constant respiration rates – e.g. at intersections & hills Urban Bicyclists' Pollution Uptake 24
  25. 25. Bicyclists’ Uptake Doses Uptake Urban Bicyclists' Pollution Uptake 25
  26. 26. Lung Fun Facts! • Gas exchange area is about ___ sq-ft. – And ~0.2 μm thin! 800 • During exercise, a red blood cell spends ___ seconds in the gas-exchange ¼ area. – Yet O2 fully exchanged in this time! Urban Bicyclists' Pollution Uptake 26
  27. 27. What happens to inhaled gas? 1. Immediately expired (dead space) 2. Absorbed/desorbed into lung lining – Water-soluble compounds 3. Absorbed/desorbed into blood – Rapid diffusion to/from blood cells Urban Bicyclists' Pollution Uptake 27
  28. 28. What happens to inhaled PM? 1. Immediately expired 2. Trapped/expelled (Large PM) 3. Deposits on lung lining (Medium PM) – Muco-ciliary clearance 4. Deposits in alveoli (Tiny PM) – Lymphatic/blood clearance Urban Bicyclists' Pollution Uptake 28
  29. 29. Factors Influencing Uptake Uptake increases with: Exposure Inhalation dose Pollutant Smaller particles Blood-soluble compounds Respiration & Physiology Deeper breathing Oral breathing Cardiac output Metabolic rate Urban Bicyclists' Pollution Uptake 29
  30. 30. Exercise and Uptake • Uptake dose increases with exercise – Primarily through ventilation • Compared to intake doses – PM uptake doses increase more • 40% greater effect than breathing alone – Gas uptake doses increase less • Limited by blood/air equilibrium Urban Bicyclists' Pollution Uptake 30
  31. 31. Bicyclist Uptake Studies • Blood/urine samples (x1) – Metabolites of BTEX compounds (VOC) – Urban bikers > rural bikers • Induced sputum samples (x1) – Lung-deposited black carbon – Bicyclists > transit riders • Modeled uptake (x4) – Doses increases with exertion Urban Bicyclists' Pollution Uptake 31
  32. 32. PSU Uptake Research • New approach • High-resolution uptake measurement • Breath sampling in bags Urban Bicyclists' Pollution Uptake 32
  33. 33. Breath Sampling • Developed as medical screening • End-tidal breath good proxy for blood concentrations – Low water-solubility VOC – Hydrocarbons like benzene, toluene,… • Requires very precise instrumentation Urban Bicyclists' Pollution Uptake 33
  34. 34. Data Collection • 75 breath VOC samples • 9 days • 3 subjects • 123 compounds Urban Bicyclists' Pollution Uptake 34
  35. 35. On-Road Sampling Example 1 2 Breath Breath Breath Paired subjects; ambient & breath VOC (20-30 minutes, 3-5 miles) Bigazzi Dissertation Proposal Defense 35
  36. 36. Early Results • The method works: exposure predicts breath concentrations – Breath elasticity to exposure: 0.3-0.5 – For traffic-related VOC • Significant history effects • Minimal subject-specific effects Urban Bicyclists' Pollution Uptake 36
  37. 37. Early Results Ambient Breath Major Arterial Local I-205 Benzene path 0 50 100 150 200 250 300 % concentration increase (vs. Tabor) Urban Bicyclists' Pollution Uptake 37
  38. 38. Health Effects Health Effects Urban Bicyclists' Pollution Uptake 38
  39. 39. Bicycle Biomarker Studies • Inconsistent results – Insignificant acute effects (4) – Some cardiovascular, respiratory, or neurological biomarker changes (7) • Health implications? • Chronic effects for commuters? Urban Bicyclists' Pollution Uptake 39
  40. 40. Net Health Effects Estimates • Health impacts for bicyclists: – Physical activity benefits dominate • By a factor of 9-96 – Outweigh crash & pollution risks • Still, we can & should reduce pollution risks Urban Bicyclists' Pollution Uptake 40
  41. 41. Conclusions • Low-traffic facilities have much lower exposure concentrations • Respiration is the big factor for bikes – And insufficiently studied • Uptake rates & health effects are still unclear Urban Bicyclists' Pollution Uptake 41
  42. 42. Future Work We have a novel data set of empirical uptake measurements – Much more analysis work to do! 1. Bike exposure & respiration models 2. Bicycle network/facility design guidance for pollution dose impacts 3. Extend to pedestrians Urban Bicyclists' Pollution Uptake 42
  43. 43. Thank you! • Bigazzi, A. and M. Figliozzi, “Review of Urban Bicyclists’ Intake and Uptake of Traffic-Related Air Pollution.” Transport Reviews, Forthcoming 2014. • Bigazzi, A., W. Luo, M. Figliozzi, J. Pankow, and L. Isabelle, “Measuring urban bicyclists’ uptake of traffic-related volatile organic compounds using ambient and breath concentrations.” 93rd Annual Meeting of the Transportation Research Board, Washington D.C., January 2014. abigazzi@pdx.edu alexbigazzi.com 43 Acknowledgements: City of Portland Metro NITC OTREC NSF Urban Bicyclists' Pollution Uptake

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