Cycling and walking – an essential component of tackling poor air quality in cities’

Transport Knowledge Hub logo Published on: 10th October 2018 by Matt Easter.

Air pollution is one of the leading public health crises today, killing tens of thousands of people prematurely across the UK every year, with higher exposure affecting those in towns and city centres. Two of the most harmful forms of air pollution, Nitrogen Dioxide and particulate matter (PM10 and PM2.5), are largely produced from motorised transport.

In fact road transport is responsible for 80% of NOx pollution where legal limits are being broken. But it’s not just burning fuel that causes the problem. In London, where there is good data, 45% of the particulate matter comes from tyre and brake wear – so even if we switched all the vehicles to electric, we’d still have a damaging amount of very fine dust as a result of the traffic. Recent studies have also linked poor air quality with other health impacts such as reduced cognitive development and dementia.
Sustrans has recently responded to a number of consultations regarding new Clean Air Zones and other measures to tackle harmfully poor air quality in our towns and cities. It is apparent that longer term sustainable solutions to improving urban air quality that work across a number of policy areas are often either entirely or low on detail. Plans to tackle the solution are often narrowly centred on a few streets where the problem is currently defined as most acute or too focused on the move to cleaner or electric vehicles. Cleaner vehicles are part of the solution but they are a long way from being the whole solution. We need less cars not just different cars. Indeed Clean Air Zones themselves will cause traffic displacement which in many cases could have an impact on communities already characterised by poorer than average health.

Reducing the amount of vehicles on the road must be a critical part of the plan to tackling poor air quality, achieved through a ‘modal shift’ away from cars by investment in more sustainable forms of transport, including cycling and walking.

Sustrans has used aggregated survey data from our seven Bike Life cities to estimate the amounts of air pollutants averted annually by cycling instead of driving based on access to a car or bike and the miles potentially driven or cycled. In Birmingham alone, over 16 tonnes of nitrogen oxide and 1,797 kg of particulates are avoided annually across the city by people with access to a car choosing to cycle instead. Although we have not estimated the mortality or morbidity averted by the reduced emissions, it is clear that both would be lessened.

Outlining the potential positive impact on air quality of increased cycling and walking is hampered because policy areas do not effectively join up. For example:

  • Air quality policies are not effectively integrated with other policies which could contribute to improving air quality, including transport, and health and are focusing on only the most acute problem areas, rather than tackling the broader problem. Therefore the co-benefits (improved health, reduced congestion etc.) of measures to reduce air pollution, including increased cycling and walking, can be overlooked or not modelled at the same time as potential reductions per cubic metre of NOx are modelled.
  • Transport policies either disregard air quality implications or are too heavily focused on technology-led solutions.
  • Health policies are too heavily focused on remedial ‘cure’ work, rather than prevention with the impacts on health of increased cycling and walking well known but complicated to model.
    Whatever the difficulty in joining up strategies and policies we know that a cultural shift away from the car and towards healthy, clean alternatives such as cycling and walking will work: for improving air quality; public health, the flow of our towns and cities and for making our streets safer, quieter and more welcoming.

We know that safety is clearly a barrier to cycling and last year’s Birmingham Bike Life study also revealed that only 22% of residents think that cycling safety is good. The report also found eight out of ten residents support the construction of more protected cycle lanes – even if it meant less room for other traffic. Clear evidence that more people will cycle with the right investment.

A proportion of this investment could come from reinvesting Clean Air Zone-related income. Traffic free paths and protected bike lanes require this investment – the former offer lower exposure to pollutants and the latter are essential where traffic free routes cannot be created. This will not only address the causes of poor air quality but will also help with other challenges such as obesity and physical inactivity thereby freeing up local NHS budgets and services.

About the Author

This post was written by Matt Easter. Matt Easter is the Director England Midlands and East Sustrans.