1. Cycling research: highlights of recent academic & government projects
All-Party Cycling Parliamentary Group
26th Feb 2019
Cycling research: highlights of recent academic & government projects
Dr James Woodcock,
University of Cambridge

2. Order of presentation Me and my work
DfT project: Propensity to Cycle Tool
PHE project: Report on health benefits of walking and cycling
New modelling study on air pollution and cycling

3. About me
Principal Research Associate, Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge
Lead a programme of epidemiologists, transport researchers, and data scientists looking at health impacts of changes in how people travel in the UK and across the world
Lead projects for Public Health England and Department for Transport, and UK research councils
Recently awarded European Research Council Consolidator Grant €2 million “Global and Local Health Impact Assessment of Transport”

6. PCT in the Cycling and Walking Investment Strategy
Propensity to Cycle Tool (PCT) is a free, open source strategic planning tool that has been developed in partnership with four universities.
The tool has been designed to assist transport planners and policy makers in the planning of cycling networks and identification of interventions to promote cycling.
The tool comprises an interactive map that shows the current and potential future distribution of commuter [+ school] cycling trips under potential growth scenarios.
It provides numerical and graphical outputs, including estimated numbers of cyclists in an area [also health and carbon benefits], and along desire lines and routes.
The Propensity to Cycle Tool can assist with the preparation of Local Cycling and Walking Infrastructure Plans and will be of particular assistance in
defining potential demand for cycling
identifying the most promising routes and areas for investment
estimating future capacity needs for route and area-based measures.

8. Propensity to Cycle Tool: new features
Cycling to school will be included in two weeks
Training sessions being organised for local authorities (basic, intermediate, and advanced)
New scenarios being added (near market)

9. Propensity to Cycle Tool:
travel to school
A ‘Go Dutch Scenario’ suggests high potential for cycling to school (much bigger increases than for commuting)
Proportion of secondary school students getting at least half their recommended physical activity from active travel to school increase from around 1 in 6 to 2 in 5.

10. Cycling and walking for individual and population health benefits:
a rapid evidence review for health and care system decision-makers
Review Team
Yvonne Laird, Paul Kelly, Soren Brage, James Woodcock

11. This rapid evidence review is intended for health and social care policy makers, decision makers and commissioners and attempts to address the following question:
“What is the impact of walking and/or cycling on different health outcomes?”

12. Context

13. Cycling and Walking Investment Strategy
In 2018, Government ministers asked for a clearer summary of the population health impacts that are specific to walking and cycling.
This was to strengthen the national narrative on the benefits of walking and cycling, and to make the health impact case more accessible.
This review has been produced in response.

14. Methods
The evidence for each health outcome was assessed according to the following hierarchy:
Systematic review and meta-analysis level evidence
Scoping and narrative review level evidence
Consistent study level evidence
Inconsistent study level evidence
Fragmented or incomplete level evidence
No evidence

15. Headline findings

16. We found that walking and cycling benefit health in a number of ways:
People who walk or cycle have improved metabolic health and reduced risk of premature mortality.
Walking and cycling reduce the risk factors for several diseases, including cardiovascular disease, respiratory disease, some cancers, and Type II diabetes.
Walking and cycling have positive effects on mental health and general well-being. This includes reduced risk of dementia, improved sleep quality, and a greater sense of wellbeing.
In environmental terms, health benefits accrue for the general population from a reduction in pollution due to car use.
On average the health benefits of walking and cycling outweigh risks and harms – for example from injury or pollution.

17. Conclusions

18. “The weight of evidence suggests that if walking and cycling can be increased, they have potential to lead to important health gains at the population level, and thus benefit the NHS and the wider health and care system.”

19. Evidence base

20. 25 reviews and 15 studies Walking Cycling Physical Health Benefits
Multiple systematic reviews
Systematic reviews
Mental Health Benefits
Scoping reviews and multiple studies
Some studies
25 reviews and 15 studies

21. Walking and Cycling as part of total physical activity

23. Walking or Cycling Health Benefit Walking or Cycling Physical Activity
Direct Evidence
Walking or Cycling
Physical Activity
Health
Benefit
Indirect Evidence

24. Moderate to Vigorous Physical Activity
Strong evidence from systematic reviews that physical activity reduces risk of these outcomes:
All-cause mortality
Cardiovascular disease
Coronary heart disease
Stroke
Diabetes
Dementia
Total cancer
Breast, colon, lung cancer
Depression

25. Cycling in polluted towns and cities

26. We found that walking and cycling benefit health in a number of ways:
People who walk or cycle have improved metabolic health and reduced risk of premature mortality.
Walking and cycling reduce the risk factors for several diseases, including cardiovascular disease, respiratory disease, some cancers, and Type II diabetes.
Walking and cycling have positive effects on mental health and general well-being. This includes reduced risk of dementia, improved sleep quality, and a greater sense of wellbeing.
In environmental terms, health benefits accrue for the general population from a reduction in pollution due to car use.
On average the health benefits of walking and cycling outweigh risks and harms – for example from injury or pollution.

28. Physical Activity and Air Pollution affect similar diseases
All-cause mortality
Cardiovascular disease
Coronary heart disease
Stroke
Diabetes
Dementia
Total cancer
Breast, colon, lung cancer
Depression
All-cause mortality
Cardiovascular disease
Coronary heart disease
Stroke
Diabetes (?)
Lower respiratory infections
Lung cancer
Chronic obstructive pulmonary disease
Asthma

29. Health gains from physical activity while cycling

30. Health harms from air pollution while cycling

31. Why are cyclists more exposed?
Inhaled dose =
Background air pollution (PM2.5) concentration *
ventilation rate *
background to exposure rate (in traffic)*
time

32. Cycling/walking
PM2.5 air pollution x ?

33. Results for 50 µg/m3 concentration (~Shanghai, Lima)

34. For the general population it pays to be active even in a polluted city
The long-term physical activity benefits of active commuting (cycling and walking) are larger than the additional risk caused by air pollution while commuting in most urban areas of the world
For the average urban background PM2.5 concentration (22 μg/m3) in the WHO database, the tipping point would only be reached after 7 h of cycling.

35. The impact of restricting cycling on high air pollution days

36. Policy regulation: UK Daily Air Quality Index
Air Pollution Banding
Accompanying health messages for the general population
Low
Enjoy your usual outdoor activities.
Moderate
High
Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High
Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

37. Policy regulation: UK Daily Air Quality Index
Air Pollution Banding
Accompanying health messages for the general population
Low
Enjoy your usual outdoor activities.
Moderate
High
Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High
Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

38. Design of the study
Daily PM2.5 air pollution data from six cities for three years
Helsinki, London, Sao Paulo, Warsaw, Beijing, New Delhi
Benefits of cycling and walking based on Kelly et al meta- analysis
Exposure to PM2.5 based on estimated concentration while in traffic, ventilation rate and time

39. Days per year exceeding threshold: London
London (days per year)
>35 μg/m3 (moderate): 27
>53 μg/m3 (high): 5
>70 μg/m3 (very high): <1
>100 μg/m3: 0

40. Increase in risk of all-cause mortality if restrict cycling on high pollution days

41. Results
Reducing cycling in a city like London on highly polluted days produces marginal reductions in health benefits
Reducing cycling in a highly polluted like Delhi on highly polluted days produces substantial reduction in health benefits

42. Summary
Propensity to Cycle Tool: for local authorities to estimate where cycling has the biggest potential to grow for commuting and soon for travel to school
There is direct evidence that cycling and walking benefit a range of health outcomes, and this evidence sits within a bigger evidence base on total physical activity
Benefits from cycling typically outweigh the harms from breathing in more polluted air. Based on UK levels of air pollution benefits of physical activity are far higher than harms for the general population and activity shouldn’t be reduced even on the most polluted days.

43. Any questions?

44. Why might impacts vary? Who and Where? Who Where?
Baseline risk of disease (e.g. older people or with other risk factors)
Non travel walking and cycling (e.g. people who do sport)
Higher injury risk (e.g. older people)
Higher air pollution susceptibility (e.g. people with asthma)
Where?
Injury risk (e.g. cycling on rural A roads)
Air pollution (e.g. walking by urban A roads)

45. Other vehicle involved in collision
Rural A 
Urban A
Rural Minor
Urban Minor
Total
Car/Taxi
3.71
3.14
4.03
2.45
3.28
LGV (van)
3.09
2.46
2.88
1.95
2.62
HGV (lorry)
15.98
18.99
19.86
19.56
17.27
Motorcycle
9.21
11.57
8.52
4.16
7.75 
Bus
23.20
25.23
18.81
13.80
19.41
Cyclist
4.71 
2.01
1.25
0.65
1.11

51. Travel microenvironments, air pollution, and health
(Barcelona sample, de Nazelle et al. 2013):
Time
travelling
% contribution to NO2 exposure
% contribution to NO2 inhalation
24% NO2 inhalation
11% NO2 exposure
a relatively large case-crossover study (1459 cases)
of exposures while cycling, walking, or taking the bus in urban environments
6% Time

52. Why are cyclists more exposed?
Inhaled dose:
Background PM2.5 concentration * ventilation rate * background to exposure rate * time
Cycling
Walking
Ventilation rate
2.6
1.4
Background to in traffic exposure ratio
2.0
1.1

53. Work in progress numbers will change!
150 minutes per week of moderate intensity activity = 8.8 MMETh/wk
300 minutes per week of moderate intensity activity =17.5 MMETh/wk