Monday, April 22, 2013

London Fog

Historically, London has wrestled with poor air quality from point source polluters like homes and factories most often relying on coal to either heat or operate their facilities. As these emitters have evolved, updated and cleaned up their processes the source of pollutants has become more democratic, shifting away from single source to the many hundreds of thousands of vehicles on the roads each day instead.  The impact being that the problem continues but from a new source, says Joan Walley MP chair of the Environmental Audit Committee, ‘It’s a scandal that the same number of people are dying of air pollution in London now as back in the 1950’s.’

London Haze. Source: The Guardian

The irony behind much of this emissions pollution is that it is coming from ‘green’ vehicles.  Diesel vehicles that have been applauded as being good for global warming, ‘for emitting lower levels of hydrocarbons, carbon monoxide and lead pollution than petrol cars, have the negative impact of producing more noxious gases and significantly more minute particles’. (Vidal) The noxious gases and particles of chief concern: nitric oxide, nitrogen dioxide, oxides of nitrogen, ozone (ground level), carbon monoxide, sulfur dioxide and particles with a median diameter less than 10 microns, have been linked to increase respiratory illnesses and diseases believed to result in an estimated, 29,000 people dying prematurely in Britain every year (according to the Committee on the Medical Effects of Air Pollutants in the UK). To add insult to injury, the number of diesel vehicles has increased in Britain by 23% from 2002, due largely to cities and governments offering tax incentives for purchasing diesels.’ (Vidal)

As a way of addressing these concerns, in 2011 the House of Commons Environmental Audit Committee’s 2011 report on air quality concluded that, ‘A public awareness campaign would be the single most important tool in improving air quality. It should be used to inform people about the positive action they could take to reduce emissions and their exposure.’ (According to Air Quality in London) To this end a number of programs have been initiated to inform and educate the public.

Low-Emission Zones and Ultra-Low Emission Zones

In February 2008, Mayor Ken Livingstone introduced the London Low-Emission Zone (LEZ) with plans to reduce overall emissions by 16%. The LEZ is a pollution-charging scheme with an aim to reduce emissions from diesel-powered, large commercial vehicles. Based on European Emission Standards, the LEZ charge applied mainly to heavy trucks, etc. Cars and other smaller vehicles were omitted and was levied using Automatic Number Plate Reading Cameras. It was originally planned for phased introduction with increasingly stringent measures.

This scheme was adopted despite drawing a lot of criticism from various stakeholders in the planning stage, most notably from the Freight Transportation Association. Future phases that included smaller trucks, potentially affecting small business owners, were also bitterly resented. Moreover, as noted earlier, Electric Vehicles and diesel-operated cars became a large source of pollution, as they are unchecked and subsidized by the government. Eventually, the LEZ was cancelled in its third phase in 2009 by new Mayor Boris Johnson, due to severe criticism and lack of results from the first two phases.

Three years later, with no solution for the emission problem, Mayor Johnson revived and repackaged the LEZ. The latest proposal for Ultra Low Emission Zones, effective in 2015, aims to bring in hybrid buses, low-emission lorries and electric cars and taxis. The ULEZ applies to buses, in a bid to save local businesses from taking the blow. Nearly £20 million over the next ten years will be spent on 1600 hybrid buses, 600 Routemasters, new designs for electric taxis.

Pollution Maps

Another program that has emerged illustrating an amount of tech sophistication offering real-time information down to the street level of pollutants in a certain area are the ‘pollution maps’ available, as apps, provided by the London Air Quality Network.  What is remarkable about many of these images is that they both provide information terms of the amount of pollutants while also showing clearly where those pollutants are originating.

Image of pollutant rates (NO2) at time of writing: London Air Quality Network



  1. Do you think that more awareness around the negative air quality impacts of diesel is also needed in the US? In my experience, diesel is often touted as a "green" alternative, and many car companies jump on this perception in their marketing. I believe VW's Diesel Jetta was named the "Green Car of the Year Award" by Consumer Reports. Is this misinformation? Or do the C02 emissions reduction of diesel vehicles trump its air quality implications?

    1. That's a really good question Jamin and one that I'd be interested to hear the answer too. I know the last time I was involved in buying a car, questions of air quality implications were not even asked: I just assumed that if the car meets air quality regulations, they're all the same.

    2. I certainly believe that the negative air quality impacts of diesel are down-played or at most, ignored not just in the US, but world-over. Although, the damaging impacts of diesel are coming to light in more recent studies, according to which, diesel is in fact worse for air quality than petrol / gasoline.

      I recently spent several futile months arguing with my parents who were considering getting a diesel-fed car as diesel is cheaper than gas, at least in India. I was, at that time, ignorant of the air quality issues between diesel and gasoline. For some reason, I always assumed diesel was worse than gas.

      In London, as in India, with all the subsidies offered for diesel-powered vehicles in the past two decades, the transportation and air quality authorities are struggling to do damage control by repealing subsidies on the LEZs and congestion tax.

      That said, I think it won't be long before US markets become aware of the harmful effects of diesel.

      Check out for more information:


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