Transport and Health

A policy report on the health benefits of increasing levels of cycling in Oxfordshire

Introduction

The increasing popularity of car travel over the last few decades has had major consequences for the lives of individuals, communities, society, and the environment. Cars have brought enormous freedom and opportunities for independence to many people, but the costs have been significant, and are disproportionately borne by the most disadvantaged groups in society. Aside from traffic deaths and injuries cars produce many other negative effects, such as noise and air pollution, and the social impacts of busy roads, such as community severance and social exclusion. Children's lives are now led very differently from the way they were a generation ago, with anxious parents shielding their children from what are perceived as the major hazards of dangerous roads and 'stranger danger'.1 Although cyclists often fear for their lives as they ride through traffic, the major health risks on the roads are in fact carried by sedentary drivers, who are more likely to die as a result of their particular lifestyle choice than any other group.

Levels of physical activity within the population are declining, and sedentary lifestyle is a major risk factor for coronary heart disease. Since Morris found that bus drivers suffer more heart attacks than bus conductors.2 the evidence has been mounting for the health benefits of physical activity; these are greatest when it is performed regularly over a lifetime. Regular cycling to work is an effective way of incorporating this exercise into daily routines; it can also have the beneficial effect of reducing traffic, a major disincentive to cycling, thus encouraging more people to use their bicycles for all sorts of travel.

his report has concentrated primarily on cycling because it is more likely to be an appropriate mode of transport for the kinds and lengths of journeys under consideration,3 but walking can be equally beneficial to health,4 and many of the same recommendations apply.

Aims

This report addresses the health costs of car and cycle transport, and the health risks of sedentary lifestyles. The aim of the report is to investigate aspects of the potential health benefits of achieving an increase in self-powered travel (walking and cycling) and a commensurate decrease in car use.

Having reviewed the evidence for the health benefits of exercise and the health costs of car use, and established the key local issues through discussion with stakeholders, a series of recommendations will be made for action by Oxfordshire Health Authority and other agencies.

Background

Public health importance

Health and transport are inextricably linked. Current levels of motorised transport have major consequences for public health, both in terms of the health impact of sedentary lifestyles, and the environmental and social effects of traffic.5 6 7

Policy context

The World Health Organisation Transport, Environment and Health programme has stated that 'sedentary lifestyle, one of the two most important risk factors for non-communicable disease and early mortality in Western populations is associated with the use of motor vehicles. There is a need to promote healthy and sustainable transport alternatives as a way to prevent the negative impacts of transport systems on human health. One important way to do this is to ensure that health issues are clearly on the agenda when transport decisions are being made and policies formulated. This requires…a change in the current strategies towards full consideration of transport policy implications for development, the environment, and health'.8

In the UK there have been many recent national and local policy initiatives encouraging exercise in general and cycling in particular. The National Cycling Strategy 9 was produced by the Conservative government in 1996, with targets to double cycling from 1996 levels by 2002, and quadruple them by 2012. The Department of the Environment, Transport and Regions' (DETR) Transport 2010: The 10 Year Plan 10 contains a commitment to providing safer cycling and walking routes, and more 20mph areas and Home Zones, particularly around schools. The Government's road safety strategy has set casualty reduction targets for 2010 of a 40% reduction in the number of people killed or seriously injured in road accidents, a 50% reduction in the number of children killed or seriously injured, and a 10% reduction in the slight casualty rate. It also acknowledges the importance of road safety for broader health, environmental and social inclusion issues.9

Several recent initiatives from central government are also highly relevant. Our Healthier Nation included a commitment to reduce the death rate from CHD, stroke and related diseases in people aged under 75 by at least 40% by 2010; it also set a target of reducing accidental deaths by 20% and serious injuries by 40%, and made a commitment to 'improve conditions and give greater priority to pedestrians and cyclists.'11 The Department of Health National Priorities Guidance 2000/01 - 20002/3 states that 'all health authorities [are] to develop and implement local prevention policies on CHD and stroke by March 2001'.12

The National Service Framework (NSF) for coronary heart disease, has among its targets a requirement that the NHS should 'develop, implement and monitor policies that reduce the prevalence of coronary risk factors in the population, and reduce inequalities in risks of developing heart disease.' It also states that by April 2001 'health authorities, local authorities, PCGs/PCTs, and NHS trusts will have agreed and be contributing to the delivery of the local programme of effective policies on…increasing physical activity' in order to reduce the incidence of CHD. The first of the four principles underpinning the NSF is that 'reducing the burden of CHD is not just the responsibility of the NHS. It requires action right across society'; it also states that 'publicly funded bodies will work together to tackle the broad determinants of health, including…transport. They will help children and adults have the opportunity to lead healthy lives, for example by increasing the opportunities for regular physical activity…'13

Current transport patterns are a major source of health inequalities. The Independent Inquiry into Inequalities in Health recommended 'further measures to encourage walking and cycling as forms of transport and to ensure the safe separation of pedestrians and cyclists from motor vehicles', and 'further steps to reduce the usage of motor vehicles to cut the mortality and morbidity associated with motor vehicle emissions', along with 'further measures to reduce traffic speed, by environmental design and modification of roads, lower speed limits in built up areas, and stricter enforcement of speed limits.'14

The foreword to the Oxfordshire Health Improvement Programme (HImP) for 2000-2003 identifies transport as one of the two key issues to be tackled. The programme supports the importance of physical activity in the prevention of CHD and diabetes, and contains local targets for reducing death and serious injury from accidents for both adults and children. It sets out several relevant objectives, such as those to promote healthy lifestyles to reduce the incidence of CHD and stroke, to develop transport policies that will benefit health, to reduce traffic and transport problems generated by the health care sector, and to improve local collection of accident data.15

Oxfordshire County Council produced cycling 16 and walking 17 strategies in 1999, along with a corporate travel plan.18 The cycling strategy contains a target to increase the proportion of cycle trips to work from 9.2% in 1991 to 10% in 2001, and 20% in 2011, and in 1993 Oxford City Council set itself a target to increase cycle use by 50% by 2001.

Current situation in Oxfordshire

Oxfordshire County Council is the highway authority for the county, although it has devolved certain powers, notably in the form of an agency agreement with Oxford City Council, which has responsibility for the majority of highways within its boundaries.

Oxford has in the last 18 months seen major changes to its traffic system as a result of the Oxford Transport Strategy (OTS); these have generated significant controversy. The strategy was first conceived by the City and County councils in the 1970s as a response to the increasing traffic flows within the city, and developed over the subsequent two decades with the aim of maintaining traffic levels at those at the time of its inception. The first phase of the OTS was implemented on 1 June 1999 with the closure of the High Street to through traffic and the pedestrianisation of Cornmarket, a major central shopping street which until that time had been a major bus thoroughfare.

Methods

The formal development of this report was conducted in three main parts: an analysis of local and national data on transport and health, a review of the evidence for the health benefits of exercise, and interviews with local stakeholders and other experts concerned with cycling and other local transport issues.

Travel, injury, and other data

Statistical and other data were obtained from appropriate sources, including the Office for National Statistics (ONS) and the DETR. The Information Team at Oxfordshire Health Authority was exceptionally helpful, and provided a wide range of these data in the appropriate formats.

Literature review

Major electronic databases were searched for relevant papers. The search terms were selected to emphasise sensitivity rather than specificity. Results were closely inspected for relevant papers, which were then selected on the basis of quality criteria.19 Other studies were located by studying citations within the papers obtained, and from previous work in this field. The staff of the Institute of Health Sciences library were extremely helpful, both in providing advice and training on search strategies, and in obtaining references.

Other sources of information included literature and references obtained at two conferences on cycling and health, one organised by the British Medical Association, the other by the Road Danger Reduction Forum. As a co-opted member of both the Highways and Traffic Committee and the Pedestrians' and Cyclists' Sub-Committee of Oxford City Council, I was able to observe discussions and decisions concerning local cycling and other transport issues. Academics and other experts were contacted for suggestions of key documents, and interviewees were extremely helpful in suggesting and providing sources of important information.

Stakeholder views

Local stakeholders were identified in a number of ways. Previous work on cycling for Oxfordshire Health Authority had involved contact with relevant local people, who were also able to suggest other suitable contacts. It was felt important to obtain a broad spectrum of political views from within local government, as well as contributions from the police, the universities, bus companies, representatives of local businesses, Oxfordshire Health Promotion, health service staff, and others. Mayer Hillman, Senior Fellow Emeritus at the Policy Studies Institute, a transport and health policy expert and the author of the original BMA book 20 which inspired this report, was also interviewed as an expert in the field.

The purpose of the interviews was to obtain information about local issues relevant for cycling, such as major political and community concerns, the viewpoints of the people involved in making the decisions, and obstacles to development within the current structures. It was also hoped that some unanticipated insights, and potential solutions to some of the problems, would become apparent.

Interviews were conducted either in person or by telephone, apart from one interviewee who gave a written response to the questions and requested anonymity; everyone approached for interview agreed to participate. Most interviews took around 30 minutes, although some lasted well over an hour. All interviewees will be sent a copy of this report.

Interviews were preceded with an explanation of my role and the purpose of the report. The interviews were semi-structured around a small number of questions. Discussion beyond the terms of the questions was encouraged. Notes were taken during the interview, typed up afterwards, and analysed in several stages. Major themes were identified and analysed in terms of factors such as the respondent's cycling experience and rural or urban location.

Results

Travel, injury and other data

The most recent year with full mortality, population, and transport data available is 1998; other years have been selected where they were the most recent quoted in reliable sources. The current Department of Transport (now DETR) report on Cycling in Great Britain, for example, was published in 1996.

Cycling and travel

38% of households overall, and 69% of those with two or more children, own at least one bicycle. Cycle ownership is linked to household income: about a quarter of households in the lowest 40% of incomes own a cycle, compared to nearly half in the remaining 60%.9

Bicycle usage has declined from 23.6 billion vehicle kilometres in 1949 to 4.0 billion in 1998; car use has increased from 20.3 billion vehicle kilometres to 375.9 billion in the same period.21 As a proportion of all road traffic, cycling has declined from 37% in 1949 to less than 1% in 1998; cycling accounts for 3.4% of journeys to work in England, but only 1.5% in Wales and Scotland.22 About a quarter of journeys travelled by bicycle are less than a mile, and another third between one and two miles; a quarter of car journeys are less than two miles.9

With 17.4% of residents cycling to work in 1991, Oxford has the third highest levels of cycle usage in the country, after Cambridge at 28.2% and York with 19.0%.9 The biannual census of pedestrian and vehicle flows into Oxford shows that the number of cyclists entering the city has increased slightly between 1996 and 2000, but remains steady around 15,500 per day. However, as the number of cars entering the census cordon points has decreased, the number of cycles as a proportion of total vehicles has increased from about 16% in 1996 to about 20% in 2000.23

A 1996 study of two Oxfordshire villages found a median car journey length of half a mile for people aged 30-59 travelling within their village; 25% of all journeys were four miles or less. It would have taken 25 minutes or less to walk (i.e. 10 minutes or less to cycle) rather than use the car for 40% of the journeys to work. The report states that 'for work journeys, the dominance of the car and acceptability of cycling to an office was explained in terms that indicated they were perceived as unalterable'; cars 'were recognised to marginalize other transport modes such as cycling and walking', and 66% of men and 71% of women supported reducing car use 'because of the associated health problems.' The study also found that the most affluent respondents had the highest levels of car ownership and car usage; the 10% of households using the most energy for travel was the most affluent group, and travelled ten times further than the 10% of households using the least energy, which was the poorest group.24

Casualty rates

3,421 people died on Great Britain's roads in 1998, and 322,000 were injured. National cyclist death rates have declined from 842 in 1949 to 158 in 1998; this is in the context of a large decrease in bicycle usage, and reflects an increase in the numbers of cyclists killed per distance travelled of about 10%. Cyclists make up 7.3% of road casualties in the UK, but cycling is, in absolute terms, a low risk activity; there is one cyclist death per 21 million kilometres cycled.21 Men average more than three times the annual cycle mileage of women, and male casualties outnumber female casualties by four to one overall and five to one for those aged under 20.22 A 1999 study of child pedestrian injuries in Britain, France and the Netherlands found that the injury risk on Britain's roads, matched for equivalent exposure, is significantly greater than in the other two countries.25

The numbers of cyclists killed on the roads in Oxfordshire are too small to discern trends, but ranged from one to five, with a mean of two, between 1994 and 1998. Despite the small numbers a standardised mortality ratio (SMR) for cycling deaths in Oxfordshire between 1994 and 1998 was calculated with a result of 131 (95% CI: 45-194). With cycle commuting rates in the county over five times the national average, and presumably other usage rates to match, even the upper limit of the 95% confidence interval for the SMR is less than half what one would anticipate given this level of cycling, suggesting that Oxfordshire is a relatively safe place to cycle.

Life years lost

Table 1 shows the numbers of life years lost through cyclist deaths in Oxfordshire 1994-98. The large year-to-year variation is a result of the inevitable random variations with small numbers of people of different ages dying. Life expectancies were calculated for each of the years 1994-98 from ONS population and mortality figures using standard formulae,26 and life years lost were then calculated by multiplying the number of deaths within each five-year age band by the life expectancy for that age band. The same calculations were also performed for CHD deaths both nationally and locally.

Table 1: Life years lost from cycling deaths and coronary heart disease deaths 1994-98

Activity levels

The 1998 Health Survey for England found that 63% of men and 75% of women exercise less than 30 minutes on most days; 20% of men and 24% of women reported less than 15 minutes of physical activity in the previous four weeks.27 A local survey of 2,056 people in 1997 found that 13% exercise three or more times a week, but 46% exercise less than once a month. Those in social class V are more than twice as likely to be sedentary as those in social class 1, and those in social class 1 are over three times as likely to exercise three or more times a week as those in social class V.28

Literature review

General points

There is a large body of evidence for the beneficial health effects of exercise on mortality and morbidity, especially from cardiovascular disease. Although different studies have taken a number of approaches to assessing and classifying activity levels, making comparison between studies difficult, it is nevertheless possible to draw broad conclusions about the activity levels required to benefit health.

Physical activity and mortality

A major review article in 1995 stated that approximately 12% of deaths in the United States are attributable to lack of physical activity, and concluded that every adult should engage in at least 30 minutes of moderate exercise on most, preferably all, days of the week. It defined moderate activity as that which expends 4-7 kcal/minute, such as brisk walking, or cycling for leisure or transport.29 A review that categorised the population as sedentary, irregularly active, regularly active, or vigorously active found that the greatest health benefits would accrue from increasing the exercise levels of the irregularly active group.30 A meta-analysis of physical activity in the prevention of CHD supported a dose-response relationship between exercise and protection from CHD.31

A prospective study of over 13,000 men and women found that those in the least fit quintile had relative risks of all-cause mortality of 1.58 (95% CI: 1.32, 1.89) for men, and 1.94 (95% CI: 1.30, 2.88) for women, compared with those in the most fit quintile, with a strong and graded association between physical fitness and mortality.32 In a study of 10,269 Harvard alumni those who were previously sedentary but took up moderate physical activity during the course of the study had a 41% lower risk of death from CHD than those who remained sedentary, and added 0.72 years of life (95% CI:0.14, 1.29).33 An earlier study of 16,936 Harvard alumni found that those expending less than 2000 kcal/week had a relative risk of fatal heart attack of 2.01 compared to those expending over 2000 kcal/week (p=0.001).34 A follow-up to this study found that death rates declined steadily as energy expenditure increased from below 500 kcal/week to 3500 kcal/week, with rates 25-33% lower in those expending over 2000 kcal/week compared to those expending less than this. By the age of 80 the amount of additional life attributable to adequate regular exercise, as opposed to sedentary lifestyle, ranged from one to over two years.35 There has until recently been a dearth of good evidence for the benefits of activity in women, but this situation has now been redressed with several large, high-quality studies showing equivalent benefits to those found in men.36 37 38

Physical activity and morbidity

In addition to the effects on cardiovascular morbidity discussed above, regular exercise has been shown to be beneficial in many conditions4 including diabetes 39 40 and insulin sensitivity,41 42 hypertension,43 44 stroke,45 elevated blood lipids,46 47 obesity,42 and cancer.48

There is evidence to support a relationship between physical activity and psychological well-being 49 50 and a recent review shows that low to moderate physical activity has beneficial effects on depression, stress,51 mood, self-esteem and premenstrual syndrome.52 Physical activity has been shown to improve cognitive function in the elderly,53 and reduce falls.54 Regular exercise allows elderly people to maintain a reasonable degree of fitness for activities of daily living,55 and a review of the relationship between physical activity and hip fractures found a protective effect of the order of a 50% reduction in the more physically active subjects.56

Stakeholder views

Interviewees live across the county, some in urban and some in rural areas, although the majority of them live in or near Oxford. Only one respondent does not cycle at all, and about half cycle regularly.

Those who lived in urban areas were more likely to cycle further and more frequently than those in rural areas, with long distances and high speed traffic on narrow roads cited by the latter group as disincentives. Experienced and higher mileage cyclists were more likely to cycle on the carriageway, and were less likely to be put off cycling by bad weather, traffic or other factors.

Fear of traffic danger was overwhelmingly the greatest disincentive to cycling. Segregation from vehicles, lower traffic speeds, and continuous cycle lanes were felt to be the most important mechanisms to counter the threat of traffic. There was broad agreement on this from the majority of respondents, with less experienced cyclists especially keen. Large vehicles, especially buses, were felt to be the most threatening.

The interviewees were broadly supportive of the projects and facilities currently in place for cyclists, and there was general agreement that they should be taken further; discontinuities in cycle lanes in particular were seen as a problem, especially by less experienced cyclists. Bicycle theft is a major concern, and greater provision of secure cycle parking was felt to be essential.

Many of the interviewees felt that employers should provide facilities such as secure cycle parking, lockers, and showers at work. There was also support for financial incentives, such as subsidies for cycle and equipment purchase, and generous mileage allowances. There was widespread criticism of the health sector for apparently failing to get its own house in order, and not leading the way with its own staff.

Several respondents stated that a process of cultural change was required to encourage more people to cycle, especially in relation to their employment. It was felt that while certain workplaces were very supportive of cycling, in others where it was not culturally accepted there would be greater obstacles to those who did want to cycle. The need to look smart at work was cited several times as a reason for people not to cycle, including by regular cyclists, as were difficulties carrying bulky items.

There was strong support for effective joint working, and public consultation, but problems were identified with both these activities. While members of all agencies were keen to work closely with their counterparts elsewhere, many respondents felt that current arrangements were ineffective, and the City Council / County Council split in Oxford was felt to be a particular barrier. Many reasons were cited for these problems, including a lack of appreciation of one another's perspectives, differing agendas, and budgetary constraints. There is little money available for public consultation, which is expensive and time consuming, and several interviewees reported practical difficulties in obtaining the views of the general public.

Many other points were raised, including:

• Widespread criticism of poor and/or illegal behaviour by cyclists
• Local Authorities across the country have a standardised system for collecting transport and accident data, allowing comparison between authorities; no such system exists for health data
• It is important to recognise the different needs of town and country dwellers. In rural areas roads tend to be narrower with higher speed traffic, and journeys made over greater distances. As a result safe, comfortable off-road routes, as have been created by Sustrans for the National Cycle Network,57 were felt to be necessary outside the major towns
• The Oxford City cycling map was very popular, and felt to be an excellent encouragement to leisure cycling

Discussion

Health benefits of exercise

Paffenbarger et al's Harvard alumni study of 1986 35 provides useful data for plotting the relationship between exercise and mortality. It includes a table relating activity levels (as defined by energy expenditure) to risk of all-cause mortality; a simple calculation allows energy expenditure to be expressed as time spent cycling, and a graph of relative risk against cycling time can then be plotted (Figure 1). The reason for the increased mortality above 3500 kcal/week is not clear, and is at odds with other studies which have shown similar gradients for reduction in mortality from increasing activity at much higher levels of energy expenditure.58

Deaths from all causes in Oxfordshire in the years 1994-98 led to a loss of 340,343 life years. Relating this to the health benefits of exercise shown in Paffenbarger's study 35 allows an estimate of the number of life years that could be gained as a result of deaths avoided if cycling activity were to increase, as shown in Table 2. A relative risk of 0.78 was used for the calculations as this is the appropriate relative risk for people exercising at a level equivalent to cycling for 20-40 minutes/day at 10mph. This reflects the potential benefit available even to inexperienced cyclists making short journeys. If 1% of the population took up cycling these people would reduce their risk of all cause mortality by (1.0-0.78) - i.e. by 22%. These calculations are inevitably crude, but they give a rough idea of the order of magnitude of the potential benefits. The calculations are based on an assumption that cycling deaths increase linearly with increasing levels of cycling. It appears, however, that cycling becomes safer as cycling levels increase (see section on Speed and Danger below). I have also assumed that the risk exposure within this sub-population is the same as that within the general population. I have requested more detailed figures on this risk exposure from the DETR, and will update the calculations once I have received them.

Table 2: Life years gained if an extra 1% of the population of Oxfordshire were to cycle regularly

The mortality reduction resulting from regular exercise significantly outweighs the dangers of cycling on British roads. Although the greatest benefits are found in those who expend over 2000 kcal/week, lower levels of exercise also have a beneficial impact on mortality and morbidity. At a population level even relatively meagre increases in activity by large numbers of people could result in significant health gains; individually these gains are likely to be the greatest among those with the highest current risks of death or disease, but the population benefits may be most significant in the larger numbers of people with lower personal risks.

Transport and the environment

Motorised transport imposes significant environmental costs. In order to appreciate the environmental benefits of a switch from motor vehicles to walking and cycling (a so-called modal shift) it is necessary to consider the environmental effects of traffic. Buses and trains are less environmentally damaging than cars and lorries, and may generate cycling and walking at either end of journeys, but detailed consideration of public transport is beyond the scope of this report.

Pollution

Vehicle emissions cause asthma, chronic cough, bronchitis, emphysema, lung fibrosis, and premature death.59 60 Catalytic converters have reduced harmful emissions, but levels remain high, and by 2010 the improvements will be overtaken by traffic growth and the concentrations of pollutants will rise again.61

The recent discovery of water at the north pole 62 is just the latest manifestation of the effects of global warming, which is generally accepted to be attributable to emissions of carbon dioxide and other heat-trapping gases. Motor vehicle emissions are a source of around 20% of these gases, and thus a major contributor to climate change and all its attendant health and social problems.63

Transport is the most pervasive source of noise in the UK daily environment.63 Almost half the population of the EU is adversely affected by road traffic noise at levels that disturb sleep and may have broader effects on health.60 Most traffic noise in urban areas is a result of engine and transmission noise, but at night events such as slamming doors and starting engines can be a major irritant. At high speeds tyre noise becomes the main source of noise; this can be tackled by reducing speeds, erecting acoustic barriers, and constructing special road surfaces.64 65

Speed and danger

Crash, injury and mortality data are extremely poor measures of risk; pedestrian fatalities are rare on both car-free precincts and motorways, but these locations clearly pose very different levels of danger for pedestrians. Much more sophisticated indices are needed accurately to reflect the dangers to which different road users are exposed.3 64 66

The 30mph speed limit is observed by only 31% of drivers.67 The contrast between the high-risk and population approaches to disease prevention applies equally to traffic enforcement: should the police focus on the small numbers of people breaking speed limits by a large margin, or attempt to tackle the lower level infractions by much larger numbers of people? These decisions are complex, and subject to many other factors such as the desirability or otherwise of criminalising a large proportion of drivers and the capacity of the criminal justice system, but they deserve consideration in terms of the potential health benefits of controlling excessive speeds.64 It seems credible that Rose's prevention paradox 68 should apply to traffic danger, and that the majority of harm is a consequence of common, relatively low level, speeding.

One of the criticisms of the Oxford Transport Strategy has been that reducing traffic levels in the city centre has allowed speeds to increase for the remaining traffic, thus increasing the risks for pedestrians and cyclists: within the range of likely urban speeds, every 1mph increase in speed raises mortality by 5%.69 A recent study of congestion and risk supports this, showing that the accident rates for cyclists and pedestrians in urban and peri-urban conditions were very much lower (by between 60 and 85%) in congested than uncongested conditions.70

There is an understandable reluctance on the part of many road safety professionals, and others responsible for transport decisions, to encourage cycling for health because it has a higher casualty rate than many other modes of transport, but this view should be challenged on several grounds. The health benefits of cycling greatly outweigh the risks, and higher rates of cycling, when supported by good infrastructure, are associated with lower casualty levels. This is shown by data from many cities in continental Europe (such as Lüneberg in Germany 71), and the experience of York, where despite a 10% increase in peak-hour cycling over the last 10 years casualties have fallen by 30%.72

Social factors and inequalities

Traffic has many other detrimental consequences for society as a whole, especially groups such as children, the elderly, and the poor;73 these people are also the least likely to have access to cars, and the most likely to rely on buses.74 Physical activity is related to socio-economic status, and is an important factor in health inequalities:75 children in the lowest socio-economic group, for example, are five times more likely to be killed as pedestrians than their counterparts in higher socio-economic groups.73

The development of the modern road network has had a profound effect on the built environment and the way we lead our lives.3 76 The ease of car travel has allowed people to live at greater distances from the places they work and shop, and the synergy between car usage and out-of-town developments has fuelled this disaggregation of communities. Many Oxfordshire villages are now low-density commuter suburbs rather than rural communities.24 It will be difficult to reverse these social and geographical trends, and there is currently little public or political will to do so.

Traffic can also lead to social isolation and community severance. Appleyard and Lintell's study in San Francisco showed that the residents of streets with differing traffic flows (light, medium and heavy) gave different ratings for traffic hazard, stress/noise/pollution, social interaction, privacy and environmental measures, with the busiest streets faring worst.77 Social networks have a positive influence on health; their disruption by traffic adversely affects health.78 Empowering communities to develop their own responses to health problems can help to build social networks at the same time as tackling the problems.79 80

Stakeholder views

One of the most striking features of the interviews was the range of factors that encourage or discourage people from cycling. These seemed to reveal a hierarchy of needs matched to cycling experience. Less experienced cyclists tended to be keener on safety facilities such as segregated routes, while the more experienced ones were more supportive of features, such as advanced stop lines, that give the cyclist priority over traffic. This equates to the hierarchy of needs found in a recent study of regular cycling in previous non-exercisers. At the start of the study 'participants were most concerned about the distance being too far, being unfit, and overcoming practical problems. As they became more used to cycling, distance and lack of fitness became less important, while weather, air pollution and fear of injury became more important.'81

Many people reported feeling threatened by large vehicles, especially buses, which they felt drove too fast and too close. Representatives of the bus companies object to these criticisms as unjustified, stating that buses are not disproportionately involved in crashes with cyclists. But if we are to encourage more people to cycle the concerns arising as a result of perceptions need to be addressed, whether or not the vehicles actually pose a disproportionate threat. The potential public health benefits of increasing levels of cycling are sufficiently large to justify major efforts to encourage anxious cyclists onto the road, and partnership with bus companies and other commercial vehicle operators is an important element in this.

Several interviewees raised objections to poor cycling, citing behaviour such as ignoring traffic signals, and riding on pavements or in pedestrianised areas. The offending behaviour seems to fall into two broad categories: breaking the law, and placing other people in danger. In fact, cyclists pose very little threat to other road users, including pedestrians, and it is noticeable that in countries with higher levels of cycling there is much greater acceptance of pedestrians and cyclists sharing space. While illegal behaviour cannot be condoned, it seems surprising that law-breaking cyclists, who are generally only placing themselves in danger, received greater criticism than speeding drivers who place other road users in danger.

It was notable that the major themes in the interviews were extremely similar to those found in a 1996 survey of attitudes to cycling,82 and suggests that the interviewees were a reasonably representative group. The survey found 'varied and complex' attitudes to cycling, with 'danger from traffic, concerns about personal safety and cycle theft, and poor image cited as major deterrents to cycling. Attitudes of government and institutions [were] seen as favouring the car and giving an inferior status to the bicycle.' Reducing motor vehicle speed, better enforcement of traffic regulations, provision of secure cycle parking facilities, employer/college initiatives, and more information about cycle routes were felt to be the most likely factors to encourage cycle use. Previous studies in Oxford 83 84 have produced similar results.

Recent policy initiatives from central government emphasise a broad perspective on health, embracing agencies beyond those engaged in formal health care. Co-operation between agencies is essential for tackling health and transport problems, and successful joint working requires transparency, trust, and a recognition of the differing viewpoints of different groups. This can be especially difficult when involving the public in decision making, given the inevitable power imbalances and multiple viewpoints inherent in the process,85 and the professional norms of the experts involved.86 But complex problems such as transport cannot be solved by independent agencies each pursuing their own agendas, and real progress will not be possible without addressing and tackling these issues.

Many different groups and individuals feed their interests into the policy-making process. These interests often conflict, and the way in which this is resolved depends upon the people doing the resolving, just as the ways in which a balance is struck between the desires of drivers and the wishes of cyclists depend upon who is doing the balancing: these are not objective processes. An understanding of the alternative rationalities involved, and a consideration of different cultural constructions of risk, can help to overcome apparently irreconcilable differences between groups or individuals with opposing viewpoints.87

Sedentary middle-aged people are among the groups most likely to benefit from reducing their car use and increasing their walking and cycling. They may have a bicycle sitting in their shed, but prefer to leave it there and drive instead. It was not feasible to conduct original research for this report, and although both local and national surveys were studied this is no substitute for ascertaining local people's views. Almost all stakeholders interviewed for this report cycle at least reasonably frequently, and thus may not be best placed to identify strategies to remove the barriers perceived by non-cyclists.

High quality public consultation is difficult and expensive to perform, but if local transport policies are successfully to address the cycling needs of current non-cyclists the public must be fully involved in the process. The recent blockades of oil refineries in protest at current levels of fuel taxation demonstrate the difficulty of reasoned argument about the complex issues involved in transport, health, and the environment. Nevertheless, an intelligent debate between experts and the public needs to be conducted, and imaginative approaches to public consultation are required. This may include initiatives such as local radio phone-ins, local parliaments and similar community fora, and other mechanisms by which views, and potential solutions, can be identified.

Limitations of this report

The use of mortality data allows basic comparisons at the level of life years lost and gained, but is a crude measure of health benefit, and depends upon many assumptions. Road death statistics provide a very distorted view of true danger as a result of multiple social and behavioural adaptations leading to risk avoidance and risk compensation.87 88 Physical exertion can trigger myocardial infarction in unfit individuals,89 but regular activity provides a strong protective effect against this.90 Significant long term morbidity is not likely to be a significant public health problem in terms of cycle casualties,20 91 92 but is a major issue in coronary heart disease; this has not been factored into the calculations, which therefore underestimate the potential health benefits of modal shift.

The calculations in this report were based on a relative risk obtained from a study that considered men aged 35 to 74, but because of the small numbers of casualties in Oxfordshire they were performed on data relating to men and women of all ages. Since men have far higher cycling casualty rates than women this may have overstated the health benefits, but the Oxfordshire results are consistent with calculations on national data for men aged 35-74; these showed a ratio of life years gained to life years lost of 269, and 245 for men and women of all ages.

One of the problems with the evidence on the health benefits of exercise is the variability of the indices used. Studies have investigated workplace activity,2 58 leisure activity,93 94 commuting,95 and overall activity,96 and the measurements made include fitness,32 97 and self-reported activity.34 Most of the major observational studies on physical activity involve a degree of self-selection in terms of the exercise level for the participants, so may tend to overstate the benefits; the calculations in this report have thus been based on the most conservative figures available in appropriate studies.

The aim of this report is to investigate the public health benefits of reducing car use and increasing walking and cycling, and make policy recommendations as a result. It does not attempt to determine the most appropriate strategies for promoting cycling or other exercise, although studies have looked at this,98 99 100 101 and have also considered its cost effectiveness.102 103 104 105 Detailed financial calculations have not been made, for a number of reasons. The cost implications of the recommendations to the Health Authority are small, and the recommendations to the local authorities could be met with relatively minor reallocation of part of their transport budgets from car facilities to cycle facilities; cycle parking spaces are, for example, much cheaper than car parking spaces. Beyond this the financial implications of potential health benefits are too complex to be dealt with in a report of this type.

Although the interviewees were chosen to be broadly representative of local stakeholders, it was impossible to include representatives of every viewpoint. The Travel for Work Project Officer in Cambridge (whose post is funded by Cambridgeshire Health Authority) was consulted about local schemes she is involved in and provided an example of their literature,106 but there was no broader comparison with other cities or districts.

The health and safety of children, and wider issues about travel to and from school, are important and complex issues. Childhood obesity is increasing, and exercise rates in childhood are declining. Lifetime exercise patterns are established in childhood, and are also linked with other factors relevant for health such as self-esteem and confidence. Issues such as these have been studied in detail elsewhere 1 101 and it was beyond the scope of this report to consider them in isolation.

Conclusions

Sedentary lifestyle is a major threat to public health. Walking and cycling for transport are effective ways for people to engage in regular exercise with all its commensurate benefits for health. A modal shift towards these forms of transport should reduce car use, thus further improving road safety, and reducing the environmental damage caused by current travel patterns. There would also be positive social and community effects, with greater social cohesion, higher levels of social capital, and a stronger focus on local communities; all these factors are likely to have a positive influence on health.

Current volumes and speeds of traffic have serious adverse health impacts on individuals and communities. Traffic is disproportionately generated by the most affluent groups in society, but the greatest ill effects are borne by the most disadvantaged sectors: 'the poor are breathing the air that the rich pollute'.107 Current transport patterns are an important factor in health inequalities, and the dominance of the car over other forms of transport is a major factor in this. There are social class gradients for coronary heart disease and sedentary lifestyle, with the highest levels in social class V. Encouraging walking and cycling for transport, and reducing car use, are effective ways of reducing these health inequalities.

Motorists are entitled to take risks with their own lives, but not with the lives of others, and they should not expect society as a whole to bear the costs of their risk-taking behaviour. Speed limits, and other restrictions on traffic, should be based on a thorough consideration of the social, health, and other impacts of that traffic. This requires a new and more rational approach, both locally and nationally, to planning and enforcement. The complex interactions of traffic, individuals, and society are difficult to disentangle, but equity, social justice and the public's health demand that the effort is made. The rights of drivers must be balanced against those of people living in and around the streets they drive through and the needs of other road users, including pedestrians and cyclists.

There is no single approach that will work to encourage fewer people to drive and more to cycle. A range of approaches, adapted to individual and local circumstances, is needed. There are two central points to bear in mind. The first is that everyone will have their own set of concerns; the second is that the needs of a novice are different from those of an experienced cyclist. This has been evocatively expressed by Ampt: 'The first issue that the ordinary human being needs to focus on is 'shall I ride?', 'can I ride?', 'shall I buy a bike?', 'how much does it cost?', 'what if I buy it and don't like it?', 'what kind shall I buy?', 'what about theft?', 'what do I need to buy for it?', 'how will I get it home from the shop?', 'what, ride!!'. All of these things can be extraordinarily difficult….I think we need a gentle reminder now and then that there are other people out there, individuals with their own myriad of balancing acts, all of which need to be considered when we are telling them about the benefits of including cycling in their way of life.'108

The health sector has an important role to play in many aspects of transport policy, but it cannot work alone. As Marmot states: 'We can make it easier or harder for people to take exercise. We can create the conditions where it is easier for people to build exercise into their daily lives. You do not just say, 'Don't be a couch potato. Take exercise'. If cycling and walking are acceptable modes of transport, it is then easy for people to exercise.'109 The joint working required to achieve this is a challenge for all agencies concerned, but it is a vital part of any serious attempt to tackle the causes of ill health at their source.

The greatest health risks on the roads are carried by sedentary car drivers; they are also the source of the majority of the danger posed to others. Cycling is a safe and effective way of improving one's health without causing harm to other road users. A modal shift from car travel to walking and cycling would have enormous public health benefits to both individuals and communities, would help to reduce health inequalities, and should be strongly supported and encouraged by Oxfordshire Health Authority.

Recommendations

Health Authority

The first step should be to lead by example and improve the situation in the NHS:

• Encourage walking and cycling to work for health authority and NHS staff
• Pay generous cycle and walking mileage allowances for business travel
• Provide signage for pedestrian and cycle routes to all NHS sites, and produce clear information on how to reach NHS sites for pedestrians and cyclists
• Provide lockers, showers, and secure cycle storage at all NHS sites
• Work with other agencies to reduce transport-related health inequalities
• Work with local employers to encourage non-car modes of transport
• Support better collection of data on cycling injuries

Local Authorities - County, City, and Districts

• Planning priorities should favour walking and cycling over motor transport wherever possible
• Tackle the policy and implementation barriers inherent in the City/County split
• Health impact assessment should be an integral part of the transport planning process
• Greater public involvement in local decisions - including a consideration of the cycling needs of current non-cyclists
• Work with police and other agencies to reduce traffic speeds and volumes in all areas where traffic has a negative impact on health, the environment and communities
• Provide more secure cycle parking in busy areas, under cover where possible
• Provide lockers, showers, secure cycle parking, etc for all local authority staff
• Continue working towards providing an unbroken network of cycle lanes in the county
• Work with law enforcement agencies to ensure tougher enforcement of parking regulations where infractions endanger vulnerable road users eg parking in cycle lanes

General issues

• Improve joint working between local agencies to ensure a fully integrated approach to transport
• Poor cyclist behaviour should be tackled with a combination of training, enforcement, and imaginative transport planning reducing the potential for conflicts
• There should be greater police involvement in setting and enforcement of speed limits
• Bus and taxi driver cyclist awareness training should be encouraged
• Perform regular monitoring of the effectiveness and health impact of interventions to increase cycling

National

• Lobby government to shift transport planning from its current car/bus/lorry focus to a much broader consideration of the health and social needs of all members of the population
• Support a new approach to speed limits nationally - they should be evidence-based with consideration of public health impacts, road safety, social, environmental, and economic factors
• Develop a greater awareness of the role of transport issues in health inequalities

Declaration of interest

I am a keen cyclist and I commute by bicycle in Oxford. In the 4 months prior to the completion of this report two cyclists were killed in collision with vehicles along the route I cycle to work.

References

1. Hillman M, Adams J, Whitlegg J. One false move...a study of children's independent mobility. Policy Studies Institute 1990
2. Morris JN, Heady JA, Raffle PAB, Roberts CG, Parks JW. Coronary heart disease and physical activity of work. Lancet 1953;2:1053-7
3. McCarthy M. Transport and Health. In Marmot M, Wilkinson RG (Eds.) Social Determinants of Health. Oxford: Oxford University Press 1999
4. Morris JN, Hardman AE. Walking to health. Sports Med 1997;23:306-32
5. McCarthy M. The effect of urban pollution and transport on health. In Sussex J (Ed.) Improving population health in industrialised nations. London: Office of Health Economics 2000
6. Dora C. A different route to health: implications of transport policies. BMJ 1999;318:1686-9 http://www.bmj.com/cgi/content/full/318/7199/1686
7. Godlee F. Transport: a public health issue. BMJ 1992;304:48-50
8. World Health Organisation. Transport, Environment and Health 2000 http://www.who.it/Ht/teh.htm (viewed on 12/6/00 - minor amendments made since then)
9. DETR. Cycling in Great Britain 1999 http://www.transtat.detr.gov.uk/facts/nts/pt5_99/cycle99.htm
10. Transport 2010: the 10 year plan. London: The Stationery Office 2000
11. Saving Lives: Our Healthier Nation. London: The Stationery Office 1999
12. National Priorities Guidance 2000/01 - 2002/03. London: The Stationery Office 2000
13. Department of Health. National Service Framework for Coronary Heart Disease. London: The Stationery Office 2000
14. Independent inquiry into inequalities in health (The Acheson report). London: The Stationery Office 1998
15. Oxfordshire Health Improvement Programme 2000/01 - 2000/03. Oxfordshire Health Authority 2000
16. Oxfordshire County Council Cycling Strategy. Oxfordshire County Council 1999
17. Oxfordshire County Council Walking Strategy. Oxfordshire County Council 1999
18. Oxfordshire County Council: corporate travel plan 1999
19. Ball C, Sackett D, Phillips R, Haynes B, Straus S. Levels of Evidence and Grades of Recommendations 2000 http://cebm.jr2.ox.ac.uk/docs/levels.html
20. Hillman M / BMA. Cycling: towards health and safety. Oxford: Oxford University Press, 1992
21. DETR. Transport Statistics Great Britain 1999. London: The Stationery Office, 1999
22. Department of Transport. Transport statistics report: cycling in Great Britain. London: HMSO 1996
23. Oxford City Council Director of Community Services. Report to Pedestrians and Cyclists Sub-Committee 30 June 2000
24. Root A, Boardman B, Fielding WJ. The costs of rural travel. Energy and Environment Programme, Environmental Change Unit, University of Oxford 1996
25. Bly P, Dix M, Stephenson C. Comparative study of European child pedestrian exposure and accidents. MVA Ltd / ITS / DETR 1999
26. Newell C. Methods and models in demography. London: Belhaven Press, 1988
27. Department of Health. Health Survey for England. London: The Stationery Office 1998
28. Peterson S, Stewart-Brown S, Peto V. Health and lifestyle in four counties: results from the third Oxford Healthy Lifestyle Survey. Oxford: Health Services Research Unit 1998
29. Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402-7
30. Powell KE, Blair SN. The public health burdens of sedentary living habits: theoretical but realistic estimates. Med Sci Sports Exerc 1994;26:851-6
31. Berlin JA, Colditz GA. A meta-analysis of physical activity in the prevention of coronary heart disease. Am J Epidemiol 1990;132:612-28
32. Blair SN, Kohl HW, Paffenbarger RS, Clark DG, Cooper KH, Gibbons LW. Physical fitness and all-cause mortality. A prospective study of healthy men and women. JAMA 1989;262:2395-401
33. Paffenbarger RS, Hyde RT, Wing AL, Lee IM, Jung DL, Kampert JB. The association of changes in physical-activity level and other lifestyle characteristics with mortality among men. N Engl J Med 1993;328:538-45
34. Paffenbarger R, Wing AL, Hyde RT. Physical activity as an index of heart attack risk in college alumni. Am J Epidemiol 1978;142:889-903
35. Paffenbarger RS, Hyde RT, Wing AL, Hsieh CC. Physical activity, all-cause mortality, and longevity of college alumni. N Engl J Med 1986;314:605-13
36. Kushi LH, Fee RM, Folsom AR, Mink PJ, Anderson KE, Sellers TA. Physical activity and mortality in postmenopausal women. JAMA 1997;277:1287-92
37. Manson JE, Hu FB, Rich-Edwards JW, Colditz GA, Stampfer MJ, Willett WC et al. A prospective study of walking as compared with vigorous exercise in the prevention of coronary heart disease in women. N Engl J Med 1999;341:650-8
38. Stampfer MJ, Hu FB, Manson JE, Rimm EB, Willett WC. Primary prevention of coronary heart disease in women through diet and lifestyle. N Engl J Med 2000;343:16-22
39. Helmrich SP, Ragland DR, Leung RW, Paffenbarger RS Jr. Physical activity and reduced occurrence of non-insulin-dependent diabetes mellitus. N Engl J Med 1991;325:147-52
40. Horton ES. Exercise and decreased risk of NIDDM. N Engl J Med 1991;325:196-8
41. Mayer-Davis EJ, D'Agostino R, Karter AJ, Haffner SM, Rewers MJ, Saad M et al. Intensity and amount of physical activity in relation to insulin sensitivity: the Insulin Resistance Atherosclerosis Study. JAMA 1998;279:669-74
42. Ross R, Dagnone D, Jones PJ, Smith H, Paddags A, Hudson R et al. Reduction in obesity and related comorbid conditions after diet-induced weight loss or exercise-induced weight loss in men. A randomized, controlled trial. Ann Intern Med 2000;133:92-103
43. Nelson L, Jennings GL, Esler MD, Korner PI. Effect of changing levels of physical activity on blood-pressure and haemodynamics in essential hypertension. Lancet 1986;2:473-6
44. Kelley GA, Kelley KS. Progressive resistance exercise and resting blood pressure: a meta-analysis of randomized controlled trials. Hypertension 2000;35:838-43
45. Hu FB, Stampfer MJ, Colditz GA, Ascherio A, Rexrode KM, Willett WC et al. Physical activity and risk of stroke in women. JAMA 2000;283:2961-7
46. Wood PD, Stefanick ML, Williams PT, Haskell WL. The effects on plasma lipoproteins of a prudent weight-reducing diet, with or without exercise, in overweight men and women. N Engl J Med 1991;325:461-6
47. Stefanick ML, Mackey S, Sheehan M, Ellsworth N, Haskell WL, Wood PD. Effects of diet and exercise in men and postmenopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol. N Engl J Med 1998;339:12-20
48. Thune I, Lund E. Physical activity and risk of colorectal cancer in men and women. Br J Cancer 1996;73:1134-40
49. Steptoe A, Butler N. Sports participation and emotional wellbeing in adolescents. Lancet 1996;347:1789-92
50. Hassmen P, Koivula N, Uutela A. Physical exercise and psychological well-being: a population study in Finland. Prev Med 2000;30:17-25
51. Roth DL, Holmes DS. Influence of aerobic exercise training and relaxation training on physical and psychologic health following stressful life events. Psychosom Med 1987;49:355-65
52. Scully D, Kremer J, Meade MM, Graham R, Dudgeon K. Physical exercise and psychological wellbeing. In MacAuley D (Ed.) Benefits and hazards of exercise. London: BMJ Books 1999
53. Kramer AF, Hahn S, Cohen NJ, Banich MT, McAuley E, Harrison CR et al. Ageing, fitness and neurocognitive function. Nature 1999;400:418-9
54. Province MA, Hadley EC, Hornbrook MC, Lipsitz LA, Miller JP, Mulrow CD et al. The effects of exercise on falls in elderly patients. A preplanned meta-analysis of the FICSIT Trials. Frailty and Injuries: Cooperative Studies of Intervention Techniques. JAMA 1995;273:1341-7
55. Fentem PH. ABC of sports medicine. Benefits of exercise in health and disease. BMJ 1994;308:1291-5 http://www.bmj.com/cgi/content/full/308/6939/1291
56. Joakimsen RM, Magnus JH, Fonnebo V. Physical activity and predisposition for hip fractures: a review. Osteoporos Int 1998;7:503-13
57. Sustrans and the national cycle network: facts and figures. Sustrans Information sheet FF29. Bristol: Sustrans 2000 http://www.sustrans.org.uk/pdf/ff29.pdf
58. Paffenbarger RS, Hale WE. Work activity and coronary heart mortality. N Engl J Med 1975;292:545-50
59. Dockery DW, Pope CA, Xu X, Spengler JD, Ware JH, Fay ME et al. An association between air pollution and mortality in six U.S. cities. N Engl J Med 1993;329:1753-9
60. McMichael AJ. Transport and health: assessing the risks. In Fletcher T, McMichael AJ (Eds.) Health at the crossroads: transport policy and urban health. Chichester: John Wiley & Sons 1995
61. Bly PH. Cleaner, quieter, safer: towards a better environment. Crowthorne, Berkshire: Transport Research Laboratory 2000
62. Browne E. First ice-free pole in 50 million years. The Observer 20 August 2000
63. McMichael AJ. Planetary Overload: global environmental change and the health of the human species. Cambridge: Cambridge University Press, 1993
64. Plowden S, Hillman M. Speed Control and Transport Policy. London: Policy Studies Institute, 1996
65. Nelson PM, Phillips SM. Quieter road surfaces. Crowthorne, Berkshire: Transport Research Laboratory 1997
66. Hillman M. Cycling and the Promotion of Health. Policy Studies 1993;14:49-58
67. DETR. Transport Statistics in Great Britain. London: The Stationery Office 1999
68. Rose G. The strategy of preventive medicine. Oxford: Oxford University Press, 1992
69. Finch D, Kompfner P, Maycock G. Speed limits and accidents. Crowthorne, Berkshire: Transport Research Laboratory 1994
70. DETR. Compendium of research projects 1999/2000. London: The Stationery Office 1999
71. Hass-Clau C. Innovative urban transport planning - examples from Europe: car-free town centres and residential areas - utopia or reality? In Fletcher T, McMichael AJ (Eds.) Health at the crossroads: transport policy and urban health. Chichester: John Wiley & Sons 1995
72. DETR. Tomorrow's roads: safer for everyone - the Government's road safety strategy and casualty reduction targets for 2010, 2000. http://www.roads.detr.gov.uk/roadsafety/strategy/tomorrow/index.htm
73. Abdalla I, Barker D, Raeside R. Road accident characteristics and socio-economic deprivation. Traff. Engin. Control 1997;38:672-6
74. Aldous E. Household expenditure on transport. Transport Trends 2000
75. Physical activity and inequalities: a briefing paper. Health Education Authority 1999
76. Rogers R. Cities for a small planet. London: Faber and Faber, 1997
77. Appleyard D, Lintell M. The environmental quality of city streets: The residents' viewpoint. American Inst of Planners Journal 1972;38:84-101
78. Brown GW, Harris T. Social origins of depression: a study of psychiatric disorder in women. London: Tavistock Publications, 1978
79. El-Askari G, Freestone J, Irizarry C, Kraut KL, Mashiyama ST, Morgan MA et al. The Healthy Neighborhoods Project: a local health department's role in catalyzing community development. Health Educ Behav 1998;25:146-59
80. Flynn BC, Ray DW, Rider MS. Empowering communities: action research through healthy cities. Health Educ Q 1995;21:395-405
81. Boyd HN, Hillman M, Nevill A, Pearce AD, Tuxworth W. Effects of regular cycling on a sample of previous non-exercisers. Cited in DETR Traffic Advisory Leaflet 12/99. Allot & Lomax and Policy Studies Institute 1998
82. Davies DG, Halliday ME, Mayes M, Pocock RL. Attitudes to cycling - a qualitative study and framework. Crowthorne, Berkshire: Transport Research Laboratory 1996
83. Sissons Joshi M, Senior V. Journey to work: the potential for modal shift? Health Educ J 1998;57:212-23
84. Sissons Joshi M, Smith GP. Cyclists under threat: a survey of Oxford cyclists' perceptions of risk. Health Educ J 1992;51:188-91
85. Popay J, Williams G. Partnership in health: beyond the rhetoric. J Epidemiol Community Health 1998;52:410-1
86. Illich I. Energy and equity. London: Calder & Boyars, 1974
87. Adams J. Risk. London: UCL Press, 1995
88. Davis R. Death on the streets: cars and the mythology of road safety. Hawes, North Yorkshire: Leading Edge Press, 1993
89. Willich SN, Lewis M, Lowel H, Arntz HR, Schubert F, Schroder R. Physical exertion as a trigger of acute myocardial infarction. Triggers and Mechanisms of Myocardial Infarction Study Group. N Engl J Med 1993;329:1684-90
90. Mittleman MA, Maclure M, Tofler GH, Sherwood JB, Goldberg RJ, Muller JE. Triggering of acute myocardial infarction by heavy physical exertion. Protection against triggering by regular exertion. Determinants of Myocardial Infarction Onset Study Investigators. N Engl J Med 1993;329:1677-83
91. Kopjar B, Wickizer TM. Cycling to school - a significant health risk? Injury Prevention 1995;1:238-41
92. Powell KE, Heath GW, Kresnow MJ, Sacks JJ, Branche CM. Injury rates from walking, gardening, weightlifting, outdoor bicycling, and aerobics. Med Sci Sports Exerc 1998;30:1246-9
93. Tager IB, Hollenberg M, Satariano WA. Association between self-reported leisure-time physical activity and measures of cardiorespiratory fitness in an elderly population. Am J Epidemiol 1998;147:921-31
94. Kujala UM, Kaprio J, Kannus P, Sarna S, Koskenvuo M. Physical activity and osteoporotic hip fracture risk in men. Arch Intern Med 2000;160:705-8
95. Vuori IM, Oja P, Paronen O. Physically active commuting to work - testing its potential for exercise promotion. Med Sci Sports Exerc 1994;26:844-50
96. Tuxworth W, Nevill A, White C, Jenkins C. Health, fitness, physical activity, and morbidity of middle aged male factory workers. Br J Ind Med 1986;43:733-53
97. Sandvik L, Erikssen J, Thaulow E, Erikssen G, Mundal R, Rodahl K. Physical fitness as a predictor of mortality among healthy, middle-aged Norwegian men. N Engl J Med 1993;328:533-7
98. Unwin NC. Promoting the public health benefits of cycling. Public Health 1995;109:41-6
99. Dunn AL. Getting started - a review of physical activity adoption studies. Br J Sports Med 1996;30:193-9
100. Hillsdon M, Thorogood M. A systematic review of physical activity promotion strategies. Br J Sports Med 1996;30:84-9
101. Pearce LM, Davis AL, Crombie HD, Boyd HN. Cycling for a healthier nation. Crowthorne, Berkshire: Transport Research Laboratory, 1998
102. Hatziandreu EI, Koplan JP, Weinstein MC, Caspersen CJ, Warner KE. A cost-effectiveness analysis of exercise as a health promotion activity. Am J Public Health 1988;78:1417-21
103. Stevens W, Hillsdon M, Thorogood M, McArdle D. Cost-effectiveness of a primary care based physical activity intervention in 45-74 year old men and women: a randomised controlled trial. Br J Sports Med 1998;32:236-41
104. Nicholl JP, Coleman P, Brazier JE. Health and healthcare costs and benefits of exercise. Pharmacoeconomics 1994;5:109-22
105. Munro J, Brazier J, Davey R, Nicholl J. Physical activity for the over-65s: could it be a cost-effective exercise for the NHS? J Public Health Med 1998;19:397-402
106. Taylor M. Cycle friendly employers: good practice guide. Cycle Friendly Employers Scheme, Cambridge 1998
107. Steensberg J. Future directions in policy and research: a public health perspective. In Fletcher T, McMichael AJ (Eds.) Health at the crossroads: transport policy and urban health. Chichester: John Wiley & Sons 1995
108. Ampt L. Address to 3rd VeloCity Conference, Nottingham, 1993
109. Marmot M. Conclusions: how the relative importance of population health determinants may change. In Sussex J (Ed.) Improving population health in industrialised nations. London: Office of Health Economics 2000

Dr Harry Rutter
Specialist Registrar in Public Health Medicine
Oxfordshire Health Authority
Richards Building
Old Road
Headington
Oxford OX3 7LG

T: 01865 22 66 30
F: 07092 25 00 40
E: info@modalshift.org

October 2000

Top | Home | Contents