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Well, no, but you’d be forgiven for thinking they did after UK newspaper headlines last week.  In focusing on the much-maligned speed bump, poor reporting of NICE’s guidelines on action to reduce air pollution deflected attention from the real problem – our continued over-reliance on motorised transport.

Speed bumps may mean drivers accelerate and decelerate frequently – leading to more dangerous emissions. Air pollution is a major problem in the UK, with illegally high levels contributing to thousands of avoidable deaths each year.  So, news reports suggested, the UK health advice body NICE had recommended that it was time for speed bumps to go.   The Guardian initially offered UK health body proposes removal of speed bumps to cut air pollution and several other papers suggested that NICE had recommended that speed bumps be removed to cut pollution risks.

The problem is that NICE’s draft guidance on air pollution did not actually advocate removing speed bumps (as the later, amended, Guardian headline reflected).  NICE considered the evidence on a range of measures that would help with air pollution, including rolling out 20 mph zones, lowering speeds on motorways to even out speeds, training for drivers on how to reduce emissions, and encouraging cycling and walking.  On road bumps, the draft recommendation was “Where physical measures are needed to reduce speed, such as humps and bumps, ensure they are designed to minimise sharp decelerations and consequent accelerations”.

Hardly an earth shattering conclusion, and certainly less newsworthy than the ‘road bumps help kill 1000s’  message suggested in some headlines.

That NICE’s rather measured advice initially got such dramatic (and misinformed) headlines reflects the controversy that often surrounds attempts to control car travel.  There is an urgent need to reduce our reliance on motorised transport – to reduce our dependence on fossil fuels, to address climate change, and to make our cities safer, more accessible and less polluted.  But any political action designed with health as a primary goal often means coming up against the vested interests of the motoring lobby, and resistance to “nanny state” governance in the public interests.  Whether it is the introduction of congestion charging, building new cycling infrastructure, or calming traffic speeds, there are always voices calling for the ‘freedom’ to drive and pollute at will.  Not surprisingly, it is easier to leap on ‘speed bumps’ as if they were the problem, rather than the fact that they are needed at all.  The real problem is our transport systems, which still prioritises the convenience of drivers over safety and wellbeing.  It is not speed bumps that cause pollution, but the emissions from cars.

And pollution is of course not the only negative consequence of car-based systems. Cars also kill and cause serious injuries directly, in crashes on the roads. In 2015, 1,732 people died in road injuries in Great Britain, and 186,209 were injured , and that burden of injury was very unevenly distributed.  Shaming inequalities in risk persist in road injury in the UK, with children in the poorest neighbourhoods over three times more likely to be injured on the roads compared with their peers in richer neighbourhoods.

Reducing traffic speed and volumes is key: to reduce pollution, to reduce road danger, and to encourage walking and cycling.  One of the very few things in that does seem to be a win-win strategy for public health and more liveable neighbourhoods are measures that reduce speed. Driving at 20 mph reduces the number of collisions, and reduces the chance of a collision ending in a serious injury.  Reducing this road danger also encourages more people to use the roads to walk or cycle, and to feel that their neighbourhood is a pleasant place to live.  Speed bumps have had an important role here.  Indeed a  study of London’s 20mph zones found they had a significant impact on road danger: roads with 20 mph zones had over 40% fewer injuries than those without.   It is difficult to think of many interventions that have had such a dramatic influence on health in recent decades.  The effect was particularly strong for young children and for serious injuries.  This study also knocked a common myth on the head: that traffic calming simply shifts the problem to other areas, as drivers speed up again.  On the contrary: the researchers found that injuries were also lower in adjacent areas with no speed bumps.  Even more encouragingly, there was also evidence that the 20mph zones had reduced widening inequalities in road injury.  By locating the zones in the poorest areas, local authorities had managed to do what has eluded many health programmes: they had improved both health, and health inequalities.  So, rather than killing, speed bumps have saved lives.

None of which means that road bumps are necessarily the best way to save lives or foster health. Good design of roads and infrastructure is a key contributor to improving our polluted, traffic congested and poorly accessible cities.  Well-designed environments can make walking or cycling a pleasure, and make welcoming public spaces for all to enjoy.  Poor design and inadequate public transport encourages us to use cars and excludes anyone not rich enough or able enough to drive.   But transport systems, and the human communities they serve, are complex and there is plenty of legitimate debate about how best to reduce car volumes and speed without creating unexpected negative consequences.

Road infrastructure is expensive to put in and also expensive to remove.  Local authorities therefore need, and want, good evidence to inform them about the likely costs and benefits of any new infrastructure.  Evidence reviews from bodies like NICE are an essential part of this, helping them to make informed decisions.   However, there are many challenges in producing these reviews.  The research evidence is not always very strong: it is not easy to accurately measure emissions in real-world driving situations, or to evaluate the safety consequences of new infrastructure in complex systems where new road layouts change who is using roads, and how.  Adopting a medicalised approach to evidence, where the focus is one intervention (road humps, for instance) and one health outcome (road injury, or pollution), risks us ‘trading off’ one against the other.    In real environments – the messy and entangled worlds we live in – transport authorities have to juggle a number of constituencies (cyclists, delivery drivers, older citizens, local businesses) and think about health in rather broader terms than simply the outcomes of injury, or pollution.

NICE’s draft guidance on outdoor pollution is still open for consultation for stakeholder groups, and anyone can look at the evidence they have drawn on to come to their recommendations.  However, most of us won’t: we rely on the news media to summarise what bodies such as NICE have said.  Our interpretations of the strength and relevance of the evidence, and its implications, will be shaped by our political and social values – whether we think the role of government is to reduce road danger, or to protect the freedom to drive, for instance.  There is no neutral evidence on the big issues like pollution and city design, and we need debate on the smaller issues like how we balance the benefits and risks of road bumps (or other traffic calming measures) in our streets.  Recommendations need to be scrutinised, and we do need to debate the values that inform research.  But for a healthy public debate,  it would be useful, even in this ‘post-truth’ age, to be able to rely at least on accurate reporting of what bodies like NICE are actually recommending.