2 Public health need and practice
Physical activity is essential for good health. It can help reduce the risk of coronary heart disease, stroke, cancer, obesity and type 2 diabetes (Chief Medical Officers of England, Scotland, Wales and Northern Ireland 2011). It also helps keep the musculoskeletal system healthy and promotes mental wellbeing.
As well as a direct benefit from physical activity, walking and cycling offer pleasure, independence and exposure to outdoor environments. These benefits may be particularly significant for people with disabilities whose participation in other activities may be more restricted.
New national physical activity guidelines were issued in 2011 (Chief Medical Officers of England, Scotland, Wales and Northern Ireland 2011) for: the under-5s, those aged 5–18, adults aged from 19–64 and for those aged 65 plus. Key points include the need to:
be physically active at all ages
be flexible (combining moderate and vigorous-intensity activity can be effective)
participate in daily activity
minimise sedentary behaviour
consider strength and balance activities for adults and older adults.
Depending on factors such as speed and the terrain, walking and cycling can both be moderate or vigorous activities. Moderate intensity activities will make the participant breathe faster, experience an increase in heart rate and feel warmer. They may sweat on hot or humid days. The amount of activity needed to reach this varies from one person to another.
Based on self-reporting, 61% of men (71% of women) in England aged 16 and over did not meet the national recommended physical activity levels (Craig et al. 2009).
The proportion of men who are physically active enough decreases markedly as they get older (from 53% at age 16–24 to 16% at 65-plus). The level of activity among women was considerably lower once they reach 65-plus, from a lower base. (Around 12% of women over 65 met the recommended levels compared to 28–36% of younger women.) (Craig et al. 2009).
Black African and Asian adults and black Caribbean women were less likely to achieve the recommendations than the general population (Sproston and Mindell 2006).
Sixty three per cent of girls (72% of boys) aged between 2 and 15 report being physically active for 60 minutes or more on 7 days a week (girls' activity declines after the age of 10) (Craig and Shelton 2008).
However, objective data suggest the above self-reporting data is an overestimate. Based on accelerometry, only 6% of men and 4% of women achieved at least 30 minutes of moderate or vigorous activity on at least 5 days (Craig et al. 2009). Only 2.5% (5.1% of boys and 0.4% of girls) actually did more than 60 minutes of moderate-to-vigorous physical activity daily (Riddoch et al. 2007).
There is a lack of information on the levels of physical activity among people with disabilities, although they are likely to be low for those with limited mobility.
The Chief Medical Officers' 2011 report notes: 'there is a clear causal relationship between the amount of physical activity people do and all-cause mortality. While increasing the activity levels of all adults who are not meeting the recommendations is important, targeting those adults who are significantly inactive (that is, engaging in less than 30 minutes of activity per week) will produce the greatest reduction in chronic disease' (Chief Medical Officers of England, Scotland, Wales, and Northern Ireland 2011).
Walking is reported to be the most common – and cycling the fourth most common – recreational and sporting activity undertaken by adults in Britain (Fox and Rickards 2004). Walking (for any purpose) accounted for between 37% and 45% of the time that women of all ages spent doing moderate or vigorous-intensity physical activity. It also accounted for between 26% and 42% of the time devoted to such activities by men of all ages (Belanger et al. 2011). As a result, it is the most likely way all adults can achieve the recommended levels of physical activity.
Bicycles are used for around 2% of journeys in Britain – compared to about 26% in the Netherlands, 19% in Denmark and 5% in France (Ministry of Transport, Public Works and Water Management 2009). Yet of all trips made in Great Britain in 2009, 20% covered less than 1 mile and more than half (56%) of car journeys covered less than 5 miles (Department for Transport 2010a).
In England on average, 10% of adults cycle at least once a week (this figure varies from over 50% to less than 5% according to the area) (Department for Transport and Sport England 2012). On average, 11% of adults cycle for at least half an hour, at least once a month (again, this figure varies from 4% to 35% according to the area (Department for Transport and Sport England 2012). Today, on an average day in London, it is estimated that around 4.3 million trips are 'potentially cyclable' (Transport for London 2010).
The majority (85.8%) of adults claim they can ride a bicycle (around 92.9% of men and 79% of women) (Department for Culture Media and Sport 2011). However, the average time spent travelling on foot or by bicycle in Britain has decreased from 12.9 minutes per day in 1995/97 to 11 minutes per day in 2007 (Department for Transport 2010a). More starkly, the average distance walked, per person per year, has fallen from 255 miles in 1975/76 to 201 miles in 2006. Bicycle mileage for the same years fell from 51 to 39 miles per person per year (Department for Transport 2007).
Motorised transport in urban areas of England is associated with poor air quality, congestion, collisions and physical inactivity – each costing society around £10 billion a year (Department for Transport 2009a). The cost of greenhouse gas emissions and the annoyance associated with noise are smaller, but still significant. In the case of greenhouse gases, costs are expected to rise sharply in future years (Department for Transport 2009a).
Exposure to air pollution is a significant cause of mortality in England. The House of Commons environmental audit report on air quality noted that: 'poor air quality reduces the life-expectancy of everyone in the UK by an average of 7 to 8 months and up to 50,000 people a year may die prematurely because of it' (House of Commons Environmental Audit Committee 2010).
Air pollution is caused by a range of factors and people's exposure depends on the level of emissions, dispersion and other factors. Particulate matter, especially small particles less than 10 or 2.5 microns (PM10 or PM2.5) in diameter, has a significant impact on health. Other significant pollutants include nitrogen oxides (NOx) and ozone.
Industrial sources produce a larger percentage of PM10 and NOx than road transport (46% and 30% respectively for NOx and 36% and 18% for PM10). However, road transport is responsible for up to 70% of air pollution in urban areas where most human exposure to air pollution occurs (House of Commons Environmental Audit Committee 2010).
Greenhouse gas emissions from domestic transport in Great Britain stayed at the same level between 1990 and 2009 (around 120 MtCO2e). Over this period, an improvement in the fuel economy of new cars was offset by increases in mileage. At the same time, the overall emission of greenhouse gases from all sources in this country has decreased. As a result, as a percentage, the proportion from transport has increased from 16% to 22%. Ninety per cent of these emissions are from road transport (58% from cars and around 30% from heavy goods vehicles and light vans) (Department for Transport 2010a).
The transportation of goods and general travel in urban areas accounts for around 20% of the distance travelled by motor vehicle, but the contribution to air pollution and climate change is greater, because of driving conditions and frequent cold starts (Favez et al. 2009).
Climate change, driven by human emissions of gases such as carbon dioxide, will lead to higher temperatures, more frequent extreme weather events, changes in rainfall and weather patterns, food and waterborne diseases and changes in distribution of vector-borne diseases. This will all have a significant impact on health in England (and globally). Changes associated with migration, following events such as flood or famine and higher levels of stress from extreme events are also likely to have a negative effect (World Health Organization 2009).
Reducing transport-related carbon emissions, by supporting a shift to walking and cycling, will help to address these adverse effects. It will also help ensure people are more physically active, so improving their health (Vardoulakis and Heaviside 2012).
The wider economic impact of supporting walking and cycling are difficult to identify with certainty.
Excess delays from traffic congestion in English urban areas are estimated to cost the economy around £10.9 billion a year (based on 2009 prices and values) (Department for Transport 2009a).
A Living Streets report highlights that improvements to the walking environment can increase the economic value of, and economic activity within, an area. This can be reflected by the sale price of residential properties and the rental price of retail premises (Sinnett et al. 2011). The report points out that local retailers may overestimate the proportion of shoppers arriving by car (41% compared with the actual proportion of 22%, in a study in Bristol).
Transport for London's 'Town centre study' (Transport for London 2011) found that people walking to a town centre spent an average of £93 per week there, compared with £56 for car drivers or passengers. Bus users spent £70 per week.
 These figures refer to the pre-2011 guidelines for physical activity (that is: adults should be active for at least 30 minutes at least five times a week at moderate intensity or greater).
 Million tonnes of carbon dioxide equivalent. Various gases (such as methane) have a different impact on the warming of the atmosphere. Converting to MtCO2e enables a direct comparison of the impact of different gases or mixtures on the atmosphere.