The subjective experience of pollution in the city

Several responses to this debate have expressed a view that air pollution is ‘covered up’ and that the government is complacent. It is true that we are a nation largely addicted to motorised road traffic, and unwilling to pay for environmental improvements, even though most of us also like to complain about our smelly, dusty, congested city streets.

In this context it has been a privilege to have worked with Professor Pilling for DEFRA on the UK Air Quality Expert Group (AQEG). Some of the discussion at AQEG meetings has surprised me in its level of frankness and vigour, as the assembled experts discuss our differences of opinion and criticisms of how, for example, air pollution monitoring is done at the moment. The interaction between science and politics is there, even occasionally some inevitable conflict between impartiality and prejudice, but the overall impression is of a collective will to do the best possible within the resources available.

The most peculiar feature of modern urban air pollution in my opinion though, is the conundrum whereby the official statistics indicate a continually (or almost continually) improving picture from the 1950s to today, and yet the level of public dissatisfaction with air quality seems to be static or even worsening. Furthermore, London has better air quality than most cities of similar size, and yet has a reputation for being highly polluted.

What is causing this apparent contradiction?

Comparing London with many other cities, and London today with that of 50 years ago, the picture is of ever greater pressure to carry higher volumes of road traffic as efficiently as possible to make as much money as possible – but most of it forced through the same streets as a hundred years ago. The blanket of smoke that used to cover the city has disappeared, and the emissions per vehicle hugely reduced. But still people are forced into close proximity with hundreds of tonnes per hour of oil-powered metal thundering past less than a metre from their ears and nose at any one of the hundreds of locations where they have to cross one of central London’s arterial roads.

Even if the number of vehicles is unable to increase (simply because the roads have been full for years), the power, speed and weight, the capacity to accelerate when the lights go green, the aggression of the driver against the pedestrian or cyclist, seems to increase continually. As air quality in the city centre parks and suburbs has improved, the contrast between the more pleasant parts and these horrendous roadside locations becomes even more stark.

Next time you are in London, take a backstreet route on foot or by bicycle, or cut across one of the parks instead of waiting for the bus at some polluted stop, and make a conscious effort to notice how clean the air is as soon as you get away from the main roads. But if you have asthma, when you step out behind a 16-tonne bus into the cloud of dust, heat and smell that can be found even with the most modern exhaust control technology (especially if the heat of the engine is combined with heat from an air conditioning unit) and the chances are yes that you will take half a breath and then stop short, that choking sensation of the body trying to prevent any more of that stuff getting into your lungs.

The statistics show you are more likely to get run over than to die of the pollution exposure (at least if the traffic is managing to move, that is), but the bit you remember is the half breath of air you tried to take at that moment. It doesn’t matter that pollution levels in your suburban kitchen are a factor of five higher when you fry your favourite food, or a factor of fifty higher in an atmospheric pub or club – it’s that pollution exposure moment out on a London street that sticks in your memory as being typical of the big city, symptomatic of how the drivers of the vehicles don’t care about you, evidence that the government doesn’t dare do anything to protect you.

That’s why we are developing a major programme of research to study the causes of these pollution exposure ‘microepisodes’ (see DAPPLE (Dispersion of Air Pollution and Penetration into the Local Environment)). And yes, the vehicle slipstreams contain those nanoparticles people are getting so worried about (or ultrafines, as most atmospheric scientists still prefer to call them).
There is growing pressure on developers and planners to build ever higher density cities, to avoid urban sprawl and energy consumption and other problems associated with low-density urban development. But we are also aware that a city needs to provide space for people to breathe, enough volume of air for any pollutant to disperse away from people, especially for people who are not responsible for causing the emissions. Architects such as David Mackay are leading the debate on how we should use urban space, and how we should address the conflicts that arise where motorised and non-motorised means of transport have to share that space.

In air quality management we are currently restricted by a growing volume of European regulation, some of which is forcing us to take a step backwards and increasingly to ignore what people actually experience as they live and work and move around in our cities. My hope for the future is that we will be able to understand better the whole picture, especially what controls the exposure of individuals to pollution, stress, conflict, delay, and other undesirable features of urban life, and to develop cities that people love to visit because they are healthy and pleasant, as well as being efficient engines of commerce and centres of culture and society.

The simple question, ‘Does air pollution cause asthma?’, therefore sits somewhere at the beginning of the complex process of moving towards that goal. Thanks to spiked for initialising a good debate so far!

Roy Colville, Imperial College London, UK