There are many, many substances which may be considered as a pollutant of local air, from chemical byproducts, to aerosols from dirty industry, to car exhaust fumes. Three of the main ones which significantly impact air quality are ozone, particulate matter (PM) and nitrogen dioxide (NO2). Concentration of the latter is the usual metric by which a city’s local pollution is measured, and mainly results from emissions of diesel fuelled vehicles. Limits on NO2 levels were set for EU countries in 2010, in accordance with recommendations of the World Health Organisation (WHO). NO2 is limited annually, such that only a certain number of breachings of the recommended maximal concentration are allowed per year.


A number of locations in the UK, including Brixton Road, London, exceeded the yearly recommended maximum within the first four days of this year. To raise awareness of this sorry state of affairs, a number of grey plaques have been put up in the most polluted parts of the capital, also including Putney High Street and Oxford Street. Like the blue heritage site plaques which they mimic, these signs indicate a hidden element to the location which the visitor finds themselves, which they may have otherwise been unaware of, only in this case the aspect is present, not past. Don’t be tricked into thinking that the problem is just localised to ‘hot spots’, and that living somewhere else in the city will save your health. As of 2012, 78% of London’s main roads exceeded EU imposed NO2 limits, with the City of London, Westminster, Kensington and Chelsea, Camden and Hammersmith and Fulham failing at 100% of measurement sites.

Levels of pollution in London are dangerously high, but at least some attention is being paid and some effort is being made to tackle it. Other mega-cities have it worse. For instance, the WHO guideline for seafront presence of PM2.5* is 25 micrograms (μg) per cubic metre, but readings in Beijing have reached as high as 671μg. Further, the US government has so far failed to recognise WHO recommendations, only considering 250μg or greater as a hazardous amount.

Cities such as Beijing are often singled out as far more polluted than European cities. Whilst this is true, the opinion may well be skewed further in this direction by the much more visible pollution there, sometimes called the ‘brown cloud’. I visited Beijing for over a week in 2010 and didn’t see the sun for the entire time, just a bright spot in the sky where it lurked behind the smog. Smog such as is common in Asian megacities is typically the result of dirty industry. Since the UK started on the road to de-industrialisation, and began importing goods made by dirty industry instead (mainly from China), air pollution has become much less visible and, arguably, trickier to deal with.

In the UK, the main problem is no longer brown smog from industry, but NO2 from diesel vehicles. In the first 11 years of the century, London saw the proportion of diesel cars registered increase from 6.9% to 21.7%, partly under encouragement from the governments of the time, with some sadly misinformed environmental recommendations.



Particulates of size PM10 and smaller are the big issue in terms of public health. They can get into our airways and from there settle in the lungs, causing potential complications. In 2010, a London Assembly report claimed up to 9% of deaths in London are caused by man-made airborne particles. Such statistics are understandably difficult to establish, since pronouncing a person as ‘dead by air pollution’ can never really be a clear judgement – there are too many other intervening factors. Analogously, a person could smoke their whole lives and never get lung cancer, whilst someone else could smoke a single cigarette which results in a chance mutation leading them to develop cancer. Nonetheless, recent estimates suggest that somewhere in the range of 4,000-10,000 Londoners and 23,500-40,000 UK citizens on the whole die every year from poor air quality. With statistics like these, there can be no reasonable argument that air pollution does not pose a very serious problem, despite the fact it often seems so invisible and intangible.

And it’s not just humans who are affected by air pollution. Paradoxically, British wildflowers actually thrive in poor quality soil, with few nutrients, such as nitrogen. However the large quantities of nitrogen finding its way into British roadsides via the compounds of NO2 emissions has enabled weeds such as Cows Parsley to thrive, outdoing the more attractive wildflowers.

Recent, horrific terrorist attacks in the UK have lead to the deaths of tens of people and have rightly been met with large displays of public solidarity. Whilst these were truly devastating events, the numbers of victims are minuscule compared with the thousands of early deaths due to air pollution every year. Why are discussions of air pollution so much less vocal? That there is no direct perpetrator cannot excuse air pollution. Modern life dictates that we all play a part, meaning it is up to us to choose how much of an effort we make to try and clean up our act.



Recent governments have made pretty poor attempts to tackle air pollution so far, although somewhat better ones than their approaches to the wider climate change problem. In the current short-termist political paradigm, whereby parties rarely make any plans that go beyond the 5 years to the next election, it makes sense that politicians do more to try and stop harm to citizens’ health in the immediate future, than to make efforts toward even tricker problems like tackling mega-polluting corporations or working towards worldwide emissions reductions.

Missed opportunities include George Osbourne blocking the creation of clean air zones during his time on the front benches. Following this, and upon his election as Mayor of London, Sadiq Khan labelled government plans as “woefully inadequate”. In February he released figures which showed NO2 limits breached near to 800 London schools, precisely where pollution should be cracked down on the most. It is often argued younger people are most at risk of health problems resulting from poor air quality, since their respiratory systems are not yet fully formed. Khan said on the matter,

“Toxic air causes more than 9,000 early deaths a year in London, as well as stunting the growth of children’s lungs, causing dementia and strokes.”

The problem is surely made worse by parents who drive their kids to school and wait in the car nearby with the engine on.

Finally, the government is beginning to establish some real policy on tackling air pollution, with a pledge to ban all new sales of petrol and diesel vehicles by 2040. However many environmentalists, including the Green Party’s Caroline Lucas, have said that these efforts go nowhere near far enough, and will come into place far too late. Hopefully more effective policies will be implemented soon.

A common theme running through this blog is that matters of climate change often need taking into public hands, at least initially, when governments and companies fail to act responsibly. There isn’t time to just sit around and hope things get changed from the top down.

The surest way to reduce your personal impact on local air quality involve commuting by bicycle, on foot or using public transport (although preferably not a mode of transport with heavy diesel fumes, such as older style buses). If you absolutely must have a car, either opt for an electric one or be aware of manufacturers such as Vauxhall, Renault and Fiat who find loopholes which enable them to make cars which emit ten times the legal limit. Whilst electric cars do a very good job of reducing local air pollution, there are still implicit C02 emissions, since the UK national grid relies heavily on fossil fuels. Additionally, there are small leaks of local air pollutants, such as from the wearing of brakes. However hopefully these issues will be addressed in the coming years and electric cars will creep closer to being zero carbon.

In the above, I have mentioned the impact of government and council policies on the air pollution problem. Whilst these are certainly important factors, today’s capitalist world dictates that businesses are arguably more impactful. Businesses have the power not to flout regulations. Businesses have the power to make greener lifestyles cheaper. Businesses have the power to reduce their emissions. But they will only do these things if the consumer has interest in them. By opting for responsibly sourced produce, by asking these things of companies and by choosing energy efficient technologies, steps are made towards them taking interest.


If you are worried about air pollution and happy to compromise on style a little, it is probably worth your wearing an air-filtering mask, such as those made by Totobobo. Doing so fulfils two purposes: cleaning the air which you breathe and raising awareness that others should consider doing so, too. A range of air pollution masks are available on the market, from flimsy paper ones to World War II gas mask style things. Reviews suggest the thin paper masks don’t actually do very much at all, only blocking the very largest particulates from being inhaled. On the other hand, the more heavy duty masks are very cumbersome and make a short cycle an unnecessarily difficult task.

I wear an intermediate type mask on my cycle commute which is light, but which claims to block out 96% of harmful particulates. I find that after just 2 weeks the filters become dark grey and are in need of changing, as shown in the photo above. Images like this shatter the invisibility nature of air pollution and can be quite shocking, when you think how much is being breathed in otherwise.



*: PMx refers to particulate matter of less than x micrometres in diameter.

[Image sources: header, plaque]

London’s choking

One thought on “London’s choking

  1. Pingback: Electric cars are not the answer | Cut waste, not trees (down)

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