Wednesday, 13 January 2016

Peter Henshaw - “Tox-ford Street”

This post was written by Peter Henshaw last summer to inform BuroHappold Engineering staff about the impact of poor air quality local to their offices. 
We have reproduced it here with their permission partly to respond to the news that London has broken European air-quality rules for the whole of 2016 — just 175 hours into the new year.

Many of you will have read articles in the press over the past few days about poor air quality in London, and specifically in Oxford Street – so called “Tox-ford Street”. 

The bold statement of leading air quality expert Dr David Carslaw that Oxford Street is one of the most polluted streets in the world is likely to be of concern for those of us here in the office each day, sitting just 150m from Oxford Street.

The claim is based on air quality monitoring data recorded opposite Selfridge’s (see figure below), as part of the London Air Quality Network ( Yearly average concentrations of nitrogen dioxide (NO2), were recorded at more than three times the legally binding EU limit value, whilst hourly NO2 readings (to reflect the short term health impacts) have exceeded limit values on more than 1500 occasions in the last year. 

The main causes of these high concentrations are the large volume of diesel buses and taxis passing through the area, the stop-start nature of urban driving, and also the street being canyonised (narrow with tall buildings either side) where pollution recirculates and accumulates. The health impacts are exacerbated by the popularity of the street, with very many people spending significant periods of time exposed to high pollution concentrations.

For ‘at risk people’ (children, elderly, those with asthma/respiratory problems) measures can be taken to avoid this exposure – even such simple steps as walking away from the kerbside can reduce exposure. However the best advice would be to use quieter streets with less traffic, and avoiding strenuous exercise along busy roads (cyclists/joggers in particular - the cityair app is useful for this On days when pollution is particularly high (due to weather conditions, for example) airtext alerts can be received via text or email and used to inform both those at risk and healthy individuals, giving advice on any precautions that should be taken (

For us on Newman Street, although there is no monitoring undertaken here, the London Air Quality Network has modelled average annual NO2 concentrations (see figure) for the whole of London.  Predicted concentrations on Newman Street indicate that even though pollutant levels are not as high as on Oxford Street, as with the majority of central London, concentrations are still above EU limits for NO2. The abundance of nearby construction sites and high HGV numbers along Newman Street do little to help the situation either. 

For new buildings in areas of poor air quality mechanical ventilation and unopenable roadside windows are often prerequisites from planning authorities in order to protect those inside. However instead of such energy intensive measures, perhaps the best method is for better education- understanding that there are certain days or even times of the day when windows next to a busy road may be best left closed. Better informing the public on air quality is something that will no doubt increase as the topic receives a higher profile from further research into effects of pollutants on human health.

So for us in Newman Street the advice is: 
  • Facilities management to sign up to airtext alerts and advise via email/on London Magellan page high pollution days;
  • On poor air quality days best to only open the windows on the less exposed building facades, so east facing in 17 and west facing in 71;
  • For cyclists/those taking exercise- although the benefits of exercise may outweigh potential health impacts, using the cityair app ( to plan a low pollution route on your cycle to work can only make things better;
  • Petition Boris to do something about it / get in touch with your MP if it is an issue that concerns you; and
  • Support campaign groups such as healthy air 

More detailed info here for those who are really interested!

As well as being recently declared carcinogenic by the WHO (, studies of particulate matter have shown a link between the number of particles in the air and ambulance calls and A&E admissions for heart attacks (

High short term NO2 concentrations can lead to inflammation of the respiratory system, and subsequent increased susceptibility to respiratory illness. Long term exposure is linked to bronchitis in asthmatic children and reduced lung function growth. To make things worse, on sunny days NO2 reacts photochemically to produce ground level ozone, which can cause breathing problems, trigger asthma and lead to lung disease. As the reaction can take some time, ground level ozone tends to build up away from roadside locations, for example in parks.

Although there has been great progress since the Great Smog of 1952, which killed 4,000 Londoners, there is a common misconception that air quality is no longer a problem. However in reality we are dealing with different pollutants; instead of smoky sulphur dioxide from coal burning (which is still an issue in places such as China), we now have NO2 and fine particulates from petrol, diesel and gas combustion, which are much more difficult to see with the naked eye and are potentially just as dangerous.

The main problem in London (as with most urban areas) is transport, and although long term measures have been introduced to try and combat traffic emissions (more stringent emission standards and the (ultra)low emission zone) certain emission technology has proved problematic  and actually lead to increases in pollutant emissions in some cases. Likewise the incentivisation of diesel vehicles to comply with carbon reduction targets has had a detrimental impact on local air quality.

A recent presentation highlights the benefits of actively improving air quality, whereby a US EPA representative highlighted the return of more than $30 in benefits for every dollar invested in pollution reduction. With increasing urbanisation, air pollution is a growing world health problem which needs to be dealt with by transforming existing cities through good design; reducing dependency on road transport and providing clean energy.

Peter Henshaw is an environmental consultant at BuroHappold, specialising in air quality research and consultancy. 

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