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Fresh-air ideas to combat London's pollution

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By Ben Richardson, Senior Sustainability Consultant, Hilson Moran

Ben RDuring our daily commute, we breathe in all sorts of pollutants that adversely affect our health. A key and common offender in London is nitrogen dioxide, which is emitted by almost all vehicles on our busy city roads. Unfortunately, the concentrations of this pollutant are at their highest during the morning and afternoon rush-hours - the same time many of us are on our way to work.

There are some simple steps that individuals can take to minimise exposure and more significant actions the industry can and should take to ensure building, urban and public realm design mitigates the effects.

As individuals, we can reduce our exposure to pollutants by walking as close to the building and furthest from the road as possible. Better still, we could walk along a parallel backstreet where the concentrations of pollutants could be as much as 50% lower. It’s worth noting that under EU law, we should not be exposed to such high, short-term levels of nitrogen dioxide, >200 μg/m3, for more than 18 hours per year; if you only spend 5 minutes walking to and from work each day, that’s 42 hours per year (μg/m3 = micrograms per cubic metre of air).

Air Quality QuoteWe at Hilson Moran undertook some research into different routes and, taking an example of Liverpool Street Station to our London Bridge office location, we found that using the green route indicated in the map exposes the walker to an average of 50% fewer pollutants than the orange route (averaged over a year).

Most of us also use the tube as part of our daily commute. Concentrations of particles on the London Underground have been regularly recorded at levels higher than 1000 μg/m3 when averaged over 8 hours. By way of comparison, it is unusual for concentrations in the New Forest to exceed 20 μg/m3 over the same period. The short-term EU exposure limit for particles is 50 μg/m3 averaged over a day, so the daily tube commuter would benefit dramatically by walking some of their normal tube ride along a cleaner pedestrian highway. If we rolled out green routes, we could develop a series of north-south walking corridor’s through London. Transport for London (TfL) is proposing cycling ‘Quietways‘, to be completed by spring next year – why not have walking ’Quietways’ as well?

Whilst changing our commute routine would not solve the air quality issue in London, it would begin to have a positive impact on our health, benefitting our lungs and respiratory systems and possibly even relieving some of the pressure on our National Health Service.

Longer-term, the property and construction industry needs to be proactive, driving improvements in our cities and ensuring it takes proper account of air quality when masterplanning large developments, new cities or smaller schemes. 

Air Quality Map

Under European law, local authorities have a statutory duty to monitor and improve air quality. In many locations, Air Quality Management Areas (AQMAs) require planning applications for new development to be accompanied by an Air Quality Assessment (AQA) report.

AQA reports use the latest technology to determine the baseline air quality at the development site and atmospheric dispersion models such as ADMS predict the ambient concentrations of pollutants resulting from fixed plant and vehicles over time. Using this information, innovative ventilation options, low emissions technology and abatement solutions can be considered for proposed buildings to ensure high performance and overcome planning issues at an early stage in the design process.

Air Quality Quote 2These reports also help to inform the design or re-design of the pedestrian network. Footpaths are often located adjacent to roads due to convenience of design and construction, but to reduce exposure to pollutants these need their own design strategy, like bus routes or tube lines, and they need to make use of London’s less polluted backstreets. There is nothing to stop us retrospectively creating back street routes – all we would need is visible, simple signage.

Pedestrian highways are another consideration because pollutant concentrations reduce rapidly within the vertical plane. Although not always the best urban design option, where they are appropriate they could weave through, behind or around buildings, linked together to create networks of footpaths away from our busy roads.

There are many positive solutions already being incorporated in our city buildings. Natural ventilation is now commonplace, allowing for a building to use 60% less energy while drastically improving the air quality for occupants. Paint is now available that filters out nitrogen oxides from the air thanks to a chemical that reacts with sunlight and water vapours to absorb nitrogen dioxide at a rate of up to 20%. Taller buildings, while a hot debate, also help – the air is cleaner higher up.

All these solutions predominantly address the effects of London’s air quality problem. We could simultaneously address the causes, which is another subject entirely. Either way, at Hilson Moran, we propose that an even greater level of collaboration (and lateral thinking) on subjects like this, between engineers and sustainability consultants, planners, architects and urban designers, would open up discussion and provide intelligence and insight from all angles and ultimately might even help to quash London’s tarnished and clearly dire air quality image.


Very useful advice. We (the City of London Corporation) and King's College London have developed a Smartphone App called CityAir to help people find and use lower pollution routes. The app is free to download and is available for iphone/ ipad and android. It is also available on the web for those people without a smartphone:
Users can receive tailored messages on days of high pollution to help reduce exposure, as well as find low pollution routes in London.

For further information see and follow us on twitter @_CityAir .
See also for the excellent work done by King's College London on air quality.
Posted by: Ruth Calderwood ( City of London Corporation ) at 19/10/2014 10:34

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