Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclist

TREC Webinar22 April, 2015

Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclists

Alex BigazziMiguel FigliozziJim PankowWentai Luo

Health Effects of Bicycling

• Health impact studies for walking & biking have shown that physical activity benefits outweigh crash & air pollution risks by an order of magnitude or more

• Still, we can & should reduce pollution risks

2Urban Bicyclists' Pollution Uptake

Framework

3

Vehicle Emissions

Air Quality

Traveler ExposureInhalation

Uptake Health Effects

Bicyclists' Pollution Uptake

Outline

1. Exposure concentrations

2. Ventilation & inhalation dose

3. Pollutant uptake

4. Applications for transportation planning and design

4Bicyclists' Pollution Uptake

Bicyclist ExposureConcentrations


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 42 studies


9k – 94k pt/cc

0.5 – 13 ppm

5 – 88 µg/m3

Modal Comparisons of Exposure

– Is this actionable information?

Context-dependent results– Bicyclists lower if separated


vsvs

High-Traffic/Low-Traffic Routes


-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


How can we reduce exposure risks for bicyclists?

Sampling Equipment


11

Exposure Data coverage

Urban Bicyclists' Pollution Uptake

Results: VOC Exposure Models

• +2% per 1,000 ADT

• +20-30% in stop-and-go riding

• Off-street path +300% in industrial

corridor


13

Parallel Path Comparison


E Burnside St. SE Ankeney St.

N Williams Ave. NE Rodney Ave.

Naito Pkwy. Riverside Path

Bicyclist Pollution Inhalation


Inhalation

Ventilation and Exercise


50 100 150 200 250 Watts

Vent

ilatio

n (

liter

/min

) 75

50

25

Ventilation is strongly related to exertion level

Ventilation & Bicycle Studies

16

57 studies assessbicyclists’ exposure

Ignored38

Constant16

Assumed/Modeled

15Measured

1

Variable3

Modeled 2

Measured1

Ven

tila

tio

n:

Urban Bicyclists' Pollution Uptake

Bicyclist Ventilation


0

1

2

3

4

5

0 5 10 15 20Ratio

of

Bic

ycle

/Mot

oriz

ed

Trav

eler

Ven

tilat

ion

Bicycle Speed (mph)

AllMenWomen

Modal Comparisons of Dose


-100%

-80%

-60%

-40%

-20%

0%

20%

40%

60%

Pedestrian Car/Taxi Bus

Dif

fere

nce

fro

m B

icyc

list

Dos

e

COUFPPM2.5

N

(3)

(3)

(5)

PSU Research Findings

• 4-8% increase in ventilation per 10 W

• Mean lag ~50 sec

• Highly variableon-road


0 50 100 150

0.0

0.2

0.4

0.6

0.8

Seconds workload lagged

Cum

ulat

ive im

pact

on ve

ntila

tion

(%

SubjecABCPooled

% Δ

vent

ilatio

n pe

r W

Seconds lag

Bicyclist Pollution Uptake


Uptake

Bicyclist Uptake Studies

2 studies of biomarkers:

• VOC: blood & urine– Urban bikers > rural bikers

• BC: induced sputum– Bicyclists > transit riders


Breath BiomarkersExhaled breath is a good proxy for

blood concentrations of VOC


alphaszenszor.com

VOC in blood

1) Local roads

Pre Breath

Post Breath

PSU On-Road Sampling

20-30 minutes, 3-5 milesExposure & breath VOC

Paired subjects


Pre Breath

Post Breath

2) Major arterials

Breath and Exposure Concentrations

0 1 2 3

Breath

Exposure

Concentration (normalized to Park)

Toluene

Major arterials

Local streets


Breath Sampling Results

• The breath sampling method works– Exposure predicts breath concentrations– Δ Breath ~ ½ Δ Exposure

• 10-60% higher on major arterials than local streets– Traffic impact (over BG) 3-5x greater on

major arterials than local streets


Explained variance in breath BTEX


0%

10%

20%

30%

40%

50%

Measured variables Modeled variables

Exposure

Ventilation

Exposure variability

Weather variables

Road & traffic

variables

Exercise and Uptake

• Ventilation/inhalation rate: 2-5x higher

• PM uptake: ≥2-5x higher

• VOC uptake: 1.5-2x higher


Applications


Route Choice

• Detour to reduce inhalation dose if:– <46% longer than minor arterial route– <123% longer than major arterial route

• Inhalation doses +20-30% per 1% grade


?

Comparison with Preferences


Will bicyclists naturally minimize inhaled dose over a trip?

Bike boulevard

or

neighborhood greenway

Bike lane

Minor arterial (no bike lane)

Major arterial (no bike lane)

• Slightly over-avoid

• Balance on collectors (6-10k ADT) • Under-avoid arterials

• Greatly over-avoid

vs.

vs.

vs.

Inhalation and Stops


0

100

200

300

400

500

600

6 8 10 12 14 16 18

Cru

ise-

equ

ival

ent

exce

ss

ven

tila

tio

n (

ft)

Cruise speed (mph)

Inhalation and Speed


0

50

100

150

200

250

300

0 4 8 12 16

Ven

tila

tion

(l/

km)

Speed (mph)

0% Grade2% Grade

Bikeway Design ConsiderationsBike lane • Higher-traffic streets

• Some lateral separation• Dedicated lane reduces stops in

congestion

Cycle track • Higher-traffic streets• More lateral separation

Bike boulevard

• Low-traffic streets• Additional benefits from traffic calming• Fewer stops reduces doses

Off-street path

• Low exposure (nearby industry?)• Fewer stops reduces doses


Take-Away Principles

1. Bicyclist Exposure a) Many different pollutantsb) Traffic, weather, and land-use all important c) Benefits of separation from traffic

2. Bicyclist Inhalationa) Varies greatly with workload (speed, grade)b) Breath response spread out over 1-2 min

3. Bicyclist Uptakea) For particles, highly sensitive to breathingb) For some gases, more sensitive to exposure &

duration


Future Work

• Abstraction for HIA & CBA• Characterizations of urban bicyclists • Similar study for pedestrians• Crowd-source pollution data


Questions?

[email protected]


Acknowledgments• Miguel Figliozzi, Jim Pankow, Wentai Luo• NITC, City of Portland, Portland Metro, NSF, OTREC

37

Industrial Corridor


Steady-state biking work


0

50

100

150

200

250

0 2 3 5 6 8 9 11 13 14 16

Wor

kloa

d (W

)

Speed (mph)

Rolling Resistance Drag 1% Grade

Minimum-Inhalation Speed


0

5

10

15

0% 2% 4% 6% 8% 10%

Min

imu

m-v

enti

lati

on

spee

d (

mp

h)

Grade

Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclist

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