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
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
Bicycle & Health Promotion
Public Health
Exercise
Crashes Pollution
Emissions
Exposure/ Dose
2 Urban Bicyclists' Pollution Uptake
Framework
3
Adapted from Ott, Stieneman & Wallace, 2007
Vehicle Emissions
Air Quality
Traveler Exposure Inhalation
Uptake Health Effects
Urban Bicyclists' Pollution Uptake
Outline
Lit. review & early results:
1. Exposure concentrations
2. Inhalation
3. Uptake doses
4. Health effects
4 Urban Bicyclists' Pollution Uptake
Bicyclists’ Exposure to Air Pollution
5 Urban Bicyclists' Pollution Uptake
Traveler Exposure
Bicyclists’ Exposures
6
0 5 10 15 20
Ultrafine PM
Fine PM
Coarse PM
Black Carbon
CO
VOC
NO2
# studies measuring on-road bicyclists’ exposure concentrations
Pollutant
9k – 94k pt/cc
0.5 – 13 ppm
5 – 88 µg/m3
42 studies
Urban Bicyclists' Pollution Uptake
3 in U.S. since 1970’s
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…
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High-Traffic/Low-Traffic Routes
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-50%
0%
50%
100%
150%
200%
250%
CO VOC UFP PM2.5 PM10 BC
Expo
sure
Inc
reas
e on
H
igh-
Traf
fic R
oute
s
N=6 N=11 N=8 N=6 N=3 N=5
PSU Bike Exposure Research
9 Urban Bicyclists' Pollution Uptake
Going beyond bike versus car.
How can we reduce exposure risks for bikers?
Urban transportation
system
Bicyclists’ uptake of air
pollution
Sampling Equipment
10 Urban Bicyclists' Pollution Uptake
CO
Cameras
CO2
TVOC Sampler Pump
Breath Bags
Sample Cartridge
Smart phone
Cycle computer
PM
ACE Device
The Portland ACE
Portable, Low-cost and Networked Device for Assessing Cyclists’ Exposure
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On-Road Sampling
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13
Exposure Data coverage
Urban Bicyclists' Pollution Uptake
~40 hours of data over 13 days
Exposure Early Results
0% 50% 100% 150% 200% 250% 300%
m,p-Xylene
Ethylbenzene
Toluene
Benzene
Concentration Increase (over Tabor)
Major Arterials Minor Arterials Local Roads I-205 Path
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Bicyclists’ Inhalation Doses
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Inhalation
Urban Bicyclists' Pollution Uptake
Inhalation
Exposure Conc’n Respiration Duration Intake
Dose
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mg/m↑3 m↑3 /sec sec mg
Urban Bicyclists' Pollution Uptake
𝑉↓𝑇 × 𝑓↓𝐵
(breaths/sec )
(m↑3 /breath )
Respiration and Exercise
• Ventilation strongly related to workload and heart rate
• ln (𝑉↓𝐸 ) =𝑎+𝑏∙𝐻𝑅 – 𝑅↑2 ≈0.97
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25
50 Ventilation
(VE)
90 120 Heart Rate
(HR)
Mermier et al. (1993)
Bicyclists’ Exertion
• External work – Speed & acceleration – Weight & slope – Wind & drag – Rolling resistance (tires, road)
• Personal factors (minor effects) – Basal metabolic rate – Fitness (exercise response)
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Respiration & Bicycle Studies
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57 studies assess bicyclists’ exposure
Ignored 38
Constant 16
Assumed 7
Modeled 8
Measured 1
Variable 3
Modeled 2
Measured 1
Res
pir
atio
n:
Urban Bicyclists' Pollution Uptake
Bicyclists’ Respiration
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0
1
2
3
4
5
0 5 10 15 20 Ratio
of Bic
ycle
/Mot
oriz
ed
Trav
eler
Res
pira
tion
Bicycle Speed (mph)
All Men Women
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
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Modal Comparisons of Dose
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-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
Pedestrian Car/Taxi Bus
Dif
fere
nce
fro
m B
icyc
list
Dos
e
CO UFP PM2.5
N
(3)
(3)
(5)
Duration vs. Respiration
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• For active modes (bike/ped), speed:
• Duration dominates: faster travel reduces intake / mile
Respiration
Duration
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
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Bicyclists’ Uptake Doses
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Uptake
Lung Fun Facts!
• Gas exchange area is about ___ sq-ft. – And ~0.2 µm thin!
• During exercise, a red blood cell spends ___ seconds in the gas-exchange area. – Yet O2 fully exchanged in this time!
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800
¼
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
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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
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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
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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
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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
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PSU Uptake Research
• New approach • High-resolution uptake measurement • Breath sampling in bags
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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
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Data Collection
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• 75 breath VOC samples • 9 days • 3 subjects • 123 compounds
On-Road Sampling Example
Paired subjects; ambient & breath VOC (20-30 minutes, 3-5 miles)
35 Bigazzi Dissertation Proposal Defense
1
2
Breath
Breath
Breath
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
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Early Results
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Breath
Ambient
Major ArterialLocalI-205
Benzene
% concentration increase (vs. Tabor)
0 50 100 150 200 250 300
path
Health Effects
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Health Effects
Bicycle Biomarker Studies
• Inconsistent results – Insignificant acute effects (4) – Some cardiovascular, respiratory, or
neurological biomarker changes (7)
• Health implications? • Chronic effects for commuters?
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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
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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
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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
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Thank you!
[email protected] alexbigazzi.com
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Acknowledgements: City of Portland Metro NITC OTREC NSF
Urban Bicyclists' Pollution Uptake
• 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.