Beyond lungs: traffic fumes an all-round killer

A long term study of degenerative neurological diseases in Ontario has found that living in proximity to a major road can increase likelihood of dementia by as much as 12% [1]. This alarming finding provides yet more motivation to critically re-evaluate our priorities for intervention in cities.

Published January 2017 in the medical journal The Lancet, the paper accounts for income, age, gender, pre-existing conditions and deprivation.  The authors posit a variety of mechanisms by which road traffic may be leading to higher rates of dementia such as brain inflammation but acknowledge that these processes are far from understood.  Nonetheless, other enquiries have shown a decline in cogitative ability due to exposure to air pollution and noise.

Dementia is only one of numerous devastating health and wellbeing impacts of relentless traffic in cites.  Unsurprisingly, respiratory diseases are commonly associated with the carcinogenic nitrous oxides, ozone and particulate matter excreted into residential streets from exhaust pipes and rubbing off brake pads [2].

Life expectancy benefits, comparing reducing fine particulate matter by 10 micrograms (equivalent to eliminating most man-made PM2.5) and other public policies.


Congested stop-start traffic is the worst, while constricted streets of inner city areas trap noxious fumes in a cloud of poison.  In the UK these fumes are killing at least 50000 [3] per year (that figure came about before the dementia study) bringing down life expectancy on average by eight months (although possibly as much as eight years in the most polluted neighbourhoods).  The situation is becoming most dangerous in the cramped megacities on the global south: the OECD calculate that in African cities ambient air pollution is now the primary cause of premature deaths in all but the poorest nations [4].  Ill health and short life expectancy impose a debilitating economic cost – particulate matter costing the continent an estimated $215bn.  Children born in African cities today face so many challenges; their urbanized upbringing should at least give them more educational and vocational opportunities than previous generations. It is devastating that this generation will be strangled by the scourge of air pollution (not to mention traffic accidents).

It’s not only physical health at stake. Traffic noise reduces cognitive ability and learning in schools [5] and these effects tend to hit the most vulnerable the hardest [6].  In London, a recent report found that schools with more children from low-income households are more likely to be found next to polluted roads [7].   Poor and minority communities in the US have been shown to bear the brunt of traffic pollution and accidents.  Unfairly, in many cases those suffering the ill health live in areas of low car ownership.  The situation is akin to passive smoking: the exhaust pipe pumps killer air into your street whether you like it or not.

Individual drivers themselves are not to blame – driving in many cities is rarely a choice – the alternatives just aren’t good enough.  And I don’t expect most drivers relish traffic queues.  Much of our car obsession today in the UK and USA is down to suburban sprawl development, which cannot sustain efficient public transport leading to car dependence.  These low density suburbs cannot sustain the transport flows required to operate a financially viable high frequency bus or rail route. These suburban residents are not exposed to pollution and noise in the same way – one of the major attractions of suburban living – creating the injustice of the benefits of driving accruing to different people in society from those who have to live with the pollution (this is a localised version of climate change, where the worst impacts seem to be happening in developing countries).  But even the residents of sprawl suffer its deleterious effects on their wellbeing: city centre workplaces are likely to be polluted and pollution levels inside cars are not much lower than outside.  Sprawling urban development is far less walkable in comparison to denser neighbourhoods where residents walk more on average per day.  Poorer residents of sprawl can struggle to access healthy foods – such as in the food deserts of Atlanta  [8]– one of the world’s most sprawling cities.  Most people enjoy walking to local shops, or community facilities – but too often we have decentralized services to the point that walking is impossible.  None of this gets enough attention when we plan cities, individual developments and the spatial distribution of vital services.  Our culture of short-termism stifles big-picture thinking: when hospitals are merged in the name of efficiency are the true costs of forcing people to travel across cities fully accounted for?

It doesn’t have to be this way.  Many cities around the world have considerably lowered their pollution levels.  The mayor of Paris Anne Hidalgo plans to halve the number of vehicles in a city that has suffered regular smog episodes, by large scale pedestrianisation [9]. This works: a no car day in Paris saw Nitrous Oxide levels fall by 40% and noise by a half [10] .  For Paris, with its dense and affordable metro, such action is feasible.  Elsewhere dealing with the local social impacts of traffic is not straightforward and there is no one-size-fits all solution.  The mayor of Ontario suggests more segregated road-space, to in effect move people away from toxic fumes.  I understand his viewpoint especially in Ontario, which is highly car dependent but in the long term this is disastrous thinking and new roads attract new traffic and the problems are shifted elsewhere.  New roads simply attract more road trips, and can decrease the use of public transport, making it less viable and forcing it into the death spiral of low passenger income/service cuts.  The solution is to get people out of cars, or if the spatial planning legacy doesn’t allow that in the medium term then at least ensure these vehicles are clean.

Longstanding issues of urban planning are impossible to change quickly but the technology already exists to eliminate these pollutants from inner cities.  There should be a phased ban on internal combustion engines in cities.  This could be achieved by not allowing vehicles bought after today being driven in cities.  This means people don’t need to pay to replace their car, but when they choose to they will need to buy electric or hire an electric vehicle for driving in cities.  If this is too hard to stomach then a proper congested road user charging scheme would be introduced so that polluters pay for the full impacts of their choices.  A high premium for driving on a busy congested road, in a residential area would send long run price signals through the transport and urban development planning processes to deliver better choices.  There are few places in the city where you can borrow valuable urban space for free and trash on the neighbours at the same time.  There are no longer technological barriers to road user charging, as GPS and road congestion monitoring are now ubiquitous in major cities.  There is clearly a major political barrier because an additional charge is levied – an answer to this might be to eliminate other road taxes and fuel duties. Fuel duty alone is not a sufficient means of road user charging because it fails to pay a premium for congested road-spaces in areas where driving is doing the most damage.  Over the longer term the development of cities needs to change to discourage sprawl.  In the UK this is easy, although clearly the challenge is much greater in developing cities.

It’s in our nature to struggle to fully conceptualise issues that are invisible or remote in space and time.  Climate change is the example for our times.  Sadly effects of traffic pollution on health are virtually invisible, and the impacts on health tend to be a long way in the future – especially dementia.  Dementia, like pollution is poorly understood and therefore neglected.  We know air pollution is unhealthy but we struggle to pin its effects definitively to poor wellbeing.  We know dementia is a devastating illness that is fast becoming a fact of life for every family, yet it remains poorly served by health and social services.

Air pollution due to traffic in cities is and disgusting and unfair as it is entirely avoidable.  The blockage now is the politics.  We have convinced most people that smoking is so harmful that it should be subject to massive taxation and regulation – that smokers should have to walk to miserable bike sheds and designated areas. This was unthinkable just a decade ago. Such an attitude needs to be adopted to stop the slow burn devastation of urban traffic pollution.



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