Bethan Jones is a Specialist Trainee in General Practice at Guy’s and St Thomas’ NHS Foundation Trust, London.
As parts of the country return to work and school, concerns remain about the safety of travelling by public transport amid the Covid-19 pandemic. This has contributed to a surge in cycling, both during the lockdown and as restrictions are eased. But cycling for daily travel has obvious benefits beyond social distancing; it is recommended by the Chief Medical Officer as amongst the ‘easiest ways’ to meet physical activity guidelines, and is proven to reduce obesity, cancers and depressive symptoms. Nevertheless, some patients will have reservations about the associated risks, including accidents, injury and exposure to pollutants. GPs need evidence to help them allay such concerns and incorporate active travel into their standard health promotion toolkit.
Cycling is proven to reduce obesity, cancers and depressive symptoms.
Exposure to air pollution – often measured according to atmospheric concentrations of nitrogen dioxide (NO2) or coarse or fine particulate matter (PM10 and PM2.5 respectively) – is indeed associated with considerable morbidity and mortality at a global level, largely relating to cardiovascular and respiratory diseases. However, a health impact modelling study found that the health benefits of active travel on all-cause mortality far outweigh any risks from air pollution; at the average urban background PM2.5 concentration, the harms of cycling would only exceed the benefits after seven hours of cycling per day. In over 99% of the world’s cities – including every city in Europe and North America – cycling up to half an hour a day would confer overall health benefits.1 Researchers have also shown significantly lower levels of NO2 and certain types of particulate matter on segregated cycle paths than on bike lanes shared with other traffic.2 This has implications both for individuals selecting routes to work and for larger-scale urban planning.
According to the Department for Transport, cyclists accounted for just 6% of road fatalities in Great Britain in 2019. While this partly reflects the low number of cyclists relative to other types of road user, after controlling for miles travelled the data still suggest a higher proportion of non-fatal accidents for cyclists compared to other road users. What’s more, in previous years over half of UK cycling casualties have occurred on rural roads, so are less likely to represent commuters. Most cycling fatalities involve collisions with other vehicles and result from head injuries; doctors should stress, therefore, that wearing a helmet is key to reducing mortality, and segregated cycle paths are preferable. Most importantly, a recent UK-based prospective study showed that while commuting by bicycle was associated with a higher risk of injury than non-active travel, those who cycled had a lower risk of cardiovascular disease, cancer and death. Indeed, the authors extrapolated that if 1000 participants added cycling to their commuting habits for 10 years, there would be 15 fewer first cancer diagnoses, four fewer cardiovascular events and three fewer deaths overall.3
Commuting by bicycle … outweighs the risks related to injury and air pollution.
Commuting by bicycle has been consistently associated with reduced obesity, cardiovascular disease, cancer and all-cause mortality, which outweighs the risks related to injury and air pollution.4,5 Interestingly, this effect is not seen with walking to work. It is estimated that expanding cycling networks in London alone could prevent 1210 premature deaths per year, accounting for the mortality impacts of changes in physical activity, air pollution and traffic incidents.6 The mental health benefits of physical activity are also significant and well-documented, and studies have specifically shown improvements in depressive symptoms in those who switch from inactive to active commuting.7
Alongside these clear health advantages, travelling by bicycle can save our patients time and money, promote independence and counter social isolation. At a population level, increasing cycling could contribute to improved air quality and enhanced road safety for all road users, especially if dedicated cycling infrastructure is made available. While the long-term effects of the Covid-19 pandemic and subsequent work and travel patterns remain unknown, GPs can – and should – encourage commuting by bicycle as an effective way of integrating physical activity into a weekly routine and safeguarding individual and public health.
References
1. Taino M, de Nazelle AJ et al (2016). Can air pollution negate the health benefits of cycling and walking? Preventative Medicine. 87: 233-236. doi: 10.1016/j.ypmed.2016.02.002
2. MacNaughton P, Melly S et al (2014). Impact of bicycle route type on exposure to traffic-related air pollution. Science of The Total Environment. 490: 37-43. doi: 10.1016/j.scitotenv.2014.04.111
3. Welsh C, Celis-Morales CA, Ho F et al (2020). Association of injury related hospital admissions with commuting by bicycle in the UK: prospective population based study. BMJ. 368:m336. doi: 10.1136/bmj.m336.
4. Flint E, Cummins S (2016). Active commuting and obesity in mid-life: cross-sectional, observational evidence from UK Biobank. Lancet Diabetes and Endocrinology. 4(5):420-35. doi: 10.1016/S2213-8587(16)00053-X
5. Celis-Morales C, Lyall D, Welsh P et al (2017). Association between active commuting and incident cardiovascular disease, cancer, and mortality: prospective cohort study. BMJ. 357: 1456. doi: 10.1136/bmj.j1456
6. Mueller N, Rojas-Rueda D, Salmon M et al. (2018) Health impact assessment of cycling network expansions in European cities. Preventive Medicine. 109: 62-70. Doi: 10.1016/j.ypmed.2017.12.011
7. Knott S, Panter J, Foley L et al (2018). Changes in the mode of travel to work and the severity of depressive symptoms: a longitudinal analysis of UK Biobank. Preventative Medicine. 112: 61-69. doi: 10.1016/j.ypmed.2018.03.018
Featured photo by Max Bender on Unsplash
