cycling, air pollution exposure & health an overview of...

Cycling, air pollution exposure & health An overview of research findings

Michael Brauer, Christie Cole

The University of British Columbia

School of Population and Public Health

VeloCity 2012 June 27, 2012 Vancouver

• Adults Metro Vancouver

• 2,149 completed telephone interview 1,402 completed web/mail questionnaire

cyclin

g i

n c

itie

s

The cycling ‘near market’ survey

other adults,

68.8% of population

~1,100,000

regular cyclists: cycle at least weekly

2.4% of population, ~40,000 adults

frequent cyclists: cycle at least monthly


occasional cyclists: cycle at least yearly


potential cyclists: cycle at least weekly


Winters M, Davidson G, Kao D, Teschke K. Motivators and deterrents of bicycling: comparing influences on decisions to

ride. Transportation. 2010. DOI 10.1007/s11116-010-9284-y

cyclingincities.spph.ubc.ca

LIKELIHOOD OF CYCLING

1= much more likely

0= no influence -1 = much less likely

all participants

regular cycl ists

occasional cycl ists

potential cycl ists

The route is away from traffic noise & air pol lution 0.8 0.8 0.8 0.7

The route has bicycle paths separated from traffic for the entire distance

0.7 0.8 0.7 0.6

The route has beautiful scenery 0.7 0.7 0.7 0.6

Cycling to the destination takes less time than traveling by other modes

0.6 0.7 0.6 0.5

The route is flat 0.6 0.6 0.6 0.6

The distance to my destination is less than 5 km 0.5 0.6 0.5 0.5

Secure indoor bike storage 0.5 0.6 0.5 0.5

I can take my bike on the SkyTrain at any time 0.5 0.6 0.5 0.4

A 2-way off-street bike pat h has a reflective centre line for night & poor weather cycling

0.5 0.6 0.5 0.4

I can make the trip in daylight hours 0.5 0.5 0.5 0.5

Covered bike racks, to protect from rain 0.5 0.5 0.5 0.5

Informat ion about cycling routes to the destination is available 0.5 0.5 0.5 0.4

The route has bike signage, pave ment markings & bike activated signals on residential streets

0.5 0.6 0.4 0.4

The bus has racks that carry bikes 0.5 0.6 0.4 0.4

A web-based trip-planning tool is available 0.5 0.5 0.4 0.4

most positive influences on decisions to cycle (top 15 of 73)

cyclin

g i

n c

itie

s

Winters M, Davidson G, Kao D, Teschke K. Motivators and deterrents of bicycling: comparing influences on decisions to

ride. Transportation. 2010. DOI 10.1007/s11116-010-9284-y

Air pollution and health

• Air pollution individual risk is small…but large exposed population = large population impact – no threshold

• On days with worse air quality, more people die

• In more polluted cities, people die earlier than in less polluted cities…

• …and, in the most polluted areas of cities, there is an increased risk of dying…

4

Brauer et al. 2012

Crouse et al. 2012

Pollution gradients

Karner et al. (2010) Environ. Sci. Technol. 44, 5334

Traffic proximity

Traffic influence zones

• 32% of Canadian population

• 36% of primary schools in large Canadian cities

Henderson et al. 2007; Brauer et al. 2012

Freeways Major Roads

Legend

Annual NO (ppb)

N

0 - 1010 - 2020 - 3030 - 4040 - 50

50 - 6060 - 7070 - 8080 - 9090 - 100

Methods

• Large databases searched (PubMED, Web Of Science, EMBASE, Google Scholar, etc.)

• Search initiated using terms from known relevant articles • Multiple key words searched using “AND” statements ex.

bicycl* AND physical activity AND risk; distinct search terms used to address specific topics – Cycling/bicycl*/cyclist AND air pollution, travel mode,

inhalation/environmental/commuter/personal exposure, commuter/urban transport, environmental monitoring, active transportation, microenvironment, traffic, exposure assessment, particulate matter, health response/effects, acute, vehicle, emissions, toxicity, exercise, cost, injury, benefit, physical activity, risk, life expectancy, non-motorized transportation, risk assessment, health behaviour, built environment, health policy, public health, accidents, mortality,

• Scanned papers for additional references & new search terms added iteratively

Three major types of studies

i) Measuring air pollution exposures of cyclists comparing route type or to other travel modes (N=18)

ii) Assessing changes in health responses following cycling in proximity to traffic (N= 7 + 1)

iii) Estimating health impacts and benefits of related to cycling under different scenarios, while considering air pollution (and sometimes physical activity and injuries) (N=6)

Exposure & Intake

EXPOSURE = CONCENTRATION x DURATION

INTAKE = EXPOSURE x INHALATION

• Travel mode

• Route type

• Inhalation

Travel Mode

Zuurbier et al. (2010) Environ Health Perspect. 118:783-9

Ultrafine particles (UFP) & travel mode

Knibbs et al. (2011) Atmos. Environ. 45. 2611

Travel mode

Authors Pollutant Location Car:Cycle Ratio

Boogard et al, 2009 UFP 11 Dutch cities 1.0

Int Panis et al, 2010 UFP 3 Belgian cities ~1.0

Zuurbier et al, 2010 UFP Arnhem 0.9

Kaur et al, 2007 UFP London 1.1

Knibbs et al, 2011 UFP Summary 1.3

Adams et al, 2002 Black Carbon London 1.7 Summer 1.8 Winter

Kingham et al, 1998 Black Carbon London 1.2

Gegisian et al, 2003 Black Carbon London 1.6

Zuurbier et al, 2010 Black Carbon Arnhem ~1.5

Dons et al, 2012 Black Carbon 3 Belgian cities 1.8

Travel mode

Authors Pollutant Location Car:Cycle Ratio

Adams et al, 2001 PM2.5 London 1.1 Summer 1.4 Winter

Kaur et al, 2007 PM2.5 London 1.1

O'Donoghue et al, 2007

PM2.5 Dublin 0.9

Zuurbier et al, 2010 PM2.5 Arnhem ~1.2

Boogard et al, 2009 PM2.5 11 Dutch cities 1.1

Huang et al, 2012 PM2.5 Beijing 0.6 (Taxi:Cycle)

Zuurbier et al, 2010 PM10 Arnhem 1.2

Huang et al, 2012 CO Beijing 2.7 (Taxi:Cycle)

Van Wijnen et al, 1995

CO Amsterdam 1.4 – 2.6

MacKay et al, 2004 CO Leeds 0.9

Kaur et al, 2007 CO London 1.2

Cycling routes and air pollutant exposure

*Thai A, McKendry I, Brauer M. Particulate Matter Exposure along Designated Bicycle Routes in Vancouver, British

Columbia. Science of the Total Environment, 2008.

Route Type (traffic level) Authors Pollutant Location High:Low traffic

Route Ratio

Strak et al, 2009 UFP Utrecht, Netherlands 1.6

Zuurbier et al, 2010 UFP Arnhem, Netherlands 1.4

Kaur et al, 2007 UFP London, UK 1.4

Knibbs et al, 2011 UFP Summary ~1.3

Kingham et al, 1998 Black Carbon London 2.3

Strak et al, 2009 Black Carbon Utrecht 1.4

Zuurbier et al, 2010 Black Carbon Arnhem 1.3

Adams et al, 2001 PM2.5 London 1.2 – 1.5

Zuurbier et al, 2010 PM2.5 Arnhem 1.0

Strak et al, 2009 PM2.5 Utrecht 1.0

Zuurbier et al, 2010 PM10 Arnhem 1.0

Bevan et al, 1991 CO Southampton, UK 1.6

Bevan et al, 1991 VOCs Southampton ~2.0

Determinants of increased UFP peaks

Activity Percent increase

Passing mopeds 58

Passing cars 4

Intersections 8 – 10

Waiting for a traffic light Average waiting time for a traffic light was 25 seconds

10

Cycling on a marked bicycle lane (separated from vehicles by line marking only)

11

Cycling on adjacent, separated bike lane 8

Boogard et al. Atmos Environ. 2009

Barriers and separation

• Displacement of cycling paths 1-2 meters away from roads (e.g. small cement barriers or planters) reduced exposures of cyclists by 8 – 38%.

• Noise barriers (5 m high, 0.3 m thick) reduced roadside UFP levels 12 - 84% along adjacent bicycle/pedestrian pathway.

Kendrick CM, Moore A, Haire A, Bigazzi A, Figliozzi M, Monsere CM, George L. The impact of bicycle lane characteristics on bicyclists’ exposure to traffic-related particulate matter. Transportation Research Record, 2011. #11-3070. 2247: 24-32. http://dx.doi.org/10.3141/2247-04; Moore A, Kendrick C, Bigazzi A, Haire A, George L, Figliozzi M, Monsere C. Assessing Bicyclist and Pedestrian Exposure to Ultrafine 1 Particles: Passive Shielding with Noise Barriers TRB 2011 Paper 11-4064 Transportation Research Board Annual Meeting 2011 Paper #11-4064

http://dx.doi.org/10.3141/2247-04

http://dx.doi.org/10.3141/2247-04

http://dx.doi.org/10.3141/2247-04

http://dx.doi.org/10.3141/2247-04

http://dx.doi.org/10.3141/2247-04

Inhalation

Author Cyclist:Car ratio

van Wijnen et al, 1995 2.3

O’Donoghue et al, 2007 2.6

Zuurbier et al, 2009 2.1

Int Panis et al, 2010 4.1 males 4.5 females

Photo: BBC

Authors Design Air pollution (UFP pt/cc)

Outcomes

Jacobs et al, 2010; Bos et al, 2012 (Antwerp)

N=38, 20 min cycle in traffic vs filtered air in lab

29,000 500

3.9 % increase in blood neutrophils No associations for exhaled NO, platelet function, Clara cell protein, Serum brain derived neurotrophic factor

Vinzents et al, 2005 (Copenhagen)

N=15, 90 min cycle in traffic (6 days) vs in lab

32,400 (not measured in lab)

4-fold increase in level of oxidative DNA base damage No association with DNA strand breaks.

Weichenthal et al, 2011 (Ottawa)

N=42, 60 min cycle in high vs low traffic vs in lab

20,000 11,000 1,200

4 hrs post ride: Decreased heart rate variability No associations with lung functions, exhaled NO

Strak et al, 2010 (Utrecht)

N=12, 60 min cycle high vs low traffic routes

44,000 28,000

0 hrs post-ride: increased lung function 6 hrs post: (non-significant) decreased lung function, increased exhaled NO.

Zuurbier et al, 2011ab (Utrecht)

N=34, 2 hr cycle vs car, bus commute (5-12 days) Dose: Bus: 24-34 Car: 25-27 Cycle High traffic: 59 Cycle Low traffic: 50

Bus: 32,00 - 45,000 Car: 35,00 - 39,000 High traffic cycle: 42,000 Low traffic cycle: 36,000

UFP dose associated with increased CRP No association for blood cell counts, markers of lung epithelial damage, coagulation or inflammation. UFP dose associated with decreased airflow and increased airway resistance No association with exhaled NO (effects not specific to cycling)

Cole et al, 2012 (Vancouver)

N=38, 1 hr cycle in high vs low traffic

16,000 10,000

DNA oxidative damage

Vinzents et al, 2005

Authors Location Change Risk Benefit Balance

Grabow

et al,

2012

Midwest

USA, 11

metro

areas

50% shift of car

round trips of ≤

8 km to cycling.

None

evaluated

Physical activity

Reduced air pollution

Combined effect: 1,129 fewer deaths/ 31.9

million population

= 35 fewer deaths/million population / year.

Benefit to risk ratio: no risks considered.

Lindsay

et al,

2010

New

Zealand

5% shift in Vkmt

for trips < 7km,

adults.

Traffic

crashes

Physical activity


Combined effect: 117 fewer deaths / 2.7 million

population = 43 fewer deaths/million

population/year.

Benefit to risk ratio ~ 24:1 (deaths) Wood-

cock et

al., 2009

London,

England

Increased active

transportation:

2X walking &

8X cycling.

Traffic

crashes

Physical activity


Combined effect: 530 fewer premature deaths

and 7,332 more disability-adjusted life-years per

million population per year.

Benefit to risk ratio: ~ 49:1 (deaths); ~ 15:1

(DALYs) de

Hartog

et al.,

2010

Netherlan

ds

500,000 adults

switch from car

to bicycle for

trips < 7.5 km.

Traffic

crashes

Air pollution

Physical activity

Combined effect: gain of 7 months of life per

person

= 583,333 years/million population over life

course.

Benefit to risk ratio: ~ 9:1

Rabl &

de

Nazelle,

2012

Europe Driver who

switches to 5 km

of cycling for

work commute

Traffic

crashes

Air pollution

Physical activity


(reduced noise and

congestion)

Combined effect: gain of 1,271 Euros/yr per car

driver who switches to cycling

= 1.3 billion Euros/yr per million car drivers who

switch.


Rojas-

Rueda et

al., 2011

Barcelona

, Spain

181,982 public

bike share users,

compared to car

use.

Traffic

crashes

Air pollution

Physical activity


Combined effect: 12.3 fewer deaths per year

= 67 fewer deaths per million population per

year.


Cycling benefits outweigh risks

The Netherlands: Modal shift

(Cars → Bikes), N=500,000 (short trips)1 – Physical activity: 14 – 90 life-day

increase

– Air pollution: 0.8 - 40 life-day decrease

– Traffic accidents 5 - 9 life-day decrease

Barcelona Bicing bike share (181,982 users)2

– Physical activity: 12 deaths avoided

– Air pollution: 0.13 increased deaths

– Traffic accidents: 0.03 increased deaths

1 De Hartog et al. 2010, 2 Rojas-Rueda et al., 2011 Getty Images

Summary

• Compared to other travel modes, cyclists experience similar or slightly lower pollutant CONCENTRATIONS, however…

…cyclists receive increased pollution INTAKE due to increased inhalation – Travel duration: pedestrians > cyclists > motor car

• Concentrations of primary traffic pollutants can differ dramatically based on route type

• Some evidence of subtle health impacts amongst cyclists in traffic compared to low/no traffic routes

• Overall cycling health benefits clearly greater than impacts of increased air pollution dose

Implications

• Cycling is beneficial, but some negative impacts due to traffic pollutant exposures

• Negative impacts can be reduced by increased separation – Barriers – Residential routes (1 block displacement) – Alternate bike and car friendly roads…. – Bike paths – Route planner (www.cyclevancouver.ubc.ca)

• Cyclists willing to detour 400 m (~2 blocks) to bike route

Su J et al. Designing a route planner to facilitate and promote cycling in Metro Vancouver, Canada. Transportation Research Part A: Policy and

Practice, 2010, 44: 495–505; Winters M et al. How far out of the way will we travel? Built environment influences on route selection for bicycle

and car travel. Transportation Research Record. 2190:1-10. http://dx.doi.org/10.3141/2190-01

http://dx.doi.org/10.3141/2190-01

http://dx.doi.org/10.3141/2190-01

http://dx.doi.org/10.3141/2190-01

Thank you!

[email protected]

Cycling route planner

Su J, Brauer M, Winters M, Nunes M. Designing a route planner to facilitate and promote cycling in Metro Vancouver, Canada. In press,

Transportation Research Part A: Policy and Practice, 2010, 44: 495–505.2010. www.cyclevancouver.ubc.ca

Boogard et al. Atmos Environ. 2009

↑ UFP: Passing mopeds (58%) and to a lesser extent passing cars (4%), Intersections (8-10%) with a right-of-way road, Waiting for a traffic light (10%) . Average waiting time for a traffic light was 25 Cycling on a marked bicycle lane (separated from vehicles by line marking only) (11%) Cycling adjacent, separated bike lane (8%)

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