London’s Air Quality Crisis: Steps Towards Cleaner Air
Eight Associates attended the 25th London Air Quality Network Conference in the summer of 2018, hosted by King’s College London (KCL). We joined representatives from local government, regulatory bodies and academia, across disciplines spanning environmental science and public health. The event included discussion on what has been achieved over the 25 years of the network, the current state of air quality, and what the future holds for air quality in London. It is clear that progress has been made in London, one need only look back as far as 1952 to the Great Smog of London, which directly led to up to 10,000 deaths and 100,000 illnesses, to see the effects of unregulated pollution.
Photograph of The Great Smog of London, 1952.
Yet we are still exceeding our legal pollutant limit values, set out in EU legislation (EU Directive 2008/50/EC Air Quality) for key pollutants, including most notably nitrogen dioxide (NO2). Within the circles of academics and policy makers, there appears to be a consensus that we are moving in the right direction, but we simply cannot afford to be complacent whilst Londoners continue to breathe air that is harmful to their health.
London Atmospheric Emissions Inventory (LAEI) Modelled 2013 and 2020 NO2 Annual Mean for Greater London.
London‘s Current Air Quality
The UK, as a member state of the EU (at the time of writing) is legally obliged to meet the pollutant limit values set out in EU Directive 2008/50/EC Air Quality, something that it has failed consistently to achieve for NO2 since 2010, resulting in the recent decision of the EU Environment Commissioner to refer the UK (alongside France and Germany) to the EU Court of Justice to face legal proceedings. Current mean annual NO2 concentrations recorded at monitoring stations across London are still reported to exceed the respective limit value (40µg/m3) by more than double this permitted value. The fact that as recently as 2015 we exceeded these NO2 limit values by more than three times does show that progress is being made, but provides no consolation to the fact that we are still dangerously exceeding these limit values.
What are Safe Levels of Pollutants?
Achieving the EU limit values should not be the end goal for UK and London-based air quality improvement, in fact the EU limit values were only ever intended as a ‘stepping stone’ towards cleaner and healthier air. The effects of pollutants on human health at, and even under, their respective limit values are known to be detrimental. The World Health Organisation (WHO) acknowledges that there may be no ‘safe’ threshold for pollutants including NO2, particulate matter (PM) and ozone (O3). Subsequent academic studies support this conclusion, one such study by Imperial College London, examined the relationship between air pollution concentrations (NO2, PM and O3), background noise and birth weight. The study concluded that birth weight was reduced by around 10-12g with each increase of 8.6ug/ m3 in mean NO2 annual concentration, regardless of compliance with respective limit values. The WHO maintains its own guidelines for air quality, in which NO2 is currently in-line with the EU, but other pollutants including particulate matter (PM) under 10µm (PM10) and PM under 2.5µm (PM2.5) are much lower (see table below).
|Pollutant||Directive 2008/50/EC Air Quality||WHO Air Quality Guidelines 2005|
|NO2||40µg/m3 as annual mean||40µg/m3 as annual mean|
|200µg/m3 as 1 hour mean not exceeded more than 18 times per year||200µg/m3 as 1 hour mean|
|PM10||40µg/m3 as annual mean||20µg/m3 as annual mean|
|50µg/m3 as 24 hour mean not exceeded more than 35 times per year||50µg/m3 as 24 hour mean|
|PM2.5||25µg/m3 as annual mean||10µg/m3 as annual mean|
|–||25µg/m3 as 1 hour mean|
Table showing EU limit values and WHO guidelines for annual mean concentrations of key pollutants.
Particulate Matter in London
London has been achieving the EU limit value for PM10 as an annual mean concentration since 2016. However, there are still two monitoring stations in London that exceed the EU limit value of 35 annual occurrences of 50µg/m3 as a 24-hour mean concentration. In addition to this, although there are only a handful of monitoring stations with the capability to monitor PM2.5, modelling of pollutant concentrations across London conclude that nearly 95% of Londoners live in areas of London that exceed the WHO guideline by 50% or more.
Not all PM pollution in London actually originates from within London. PM can be carried great distances by winds from within the UK, and from other countries. It is estimated that around 12-13µg/m3 of London’s background PM10 concentrations come from other European countries and, while it is expected that this figure will come down to around 10µg/m3 during the next few years, the effect of these transboundary emissions will nonetheless remain significant.
Graph showing mean annual NO2 concentrations at monitoring stations across London since 2010 (NAQO-compliant stations are shown in green, non-compliant stations in red) .
The Impact of Development in London
The population of Greater London is currently estimated at around 8.8 million and is set to grow to around 10.1 million by 2036. This growth will not be distributed evenly and areas that will see the largest increase are the East London Boroughs of Tower Hamlets, Newham, Redbridge and Barking & Dagenham, where the population is set to grow by 30 to 42%. We are already seeing a development boom in these parts of London, led by the growing population and associated housing demand, increasing land values and desirability as a location for business, and it looks increasingly likely that this will continue into the future.
With the demand to deliver new developments, comes the demand for construction and the associated emissions as a result of construction activities. In 2015, it was estimated that up to 12% of NO2 and 15% of total PM pollution in London came from construction activities (including demolition, earthworks and trackout of vehicles). Dust emissions as a result of construction activities contribute to PM concentrations, but are only thought to comprise around 1% of total PM concentrations, compared to PM from non-road mobile machinery (NRMM), predominantly on construction sites, which account for 8% of total PM concentrations. With the frequency and scale of major construction projects in London likely to increase, the proportion of emissions from construction is likely to increase.
Vehicle Emissions Standards
When examining the share of construction emissions from NRMM, it is clear that there are currently huge differences in the European Emission Standard ‘Euro’ standards between road vehicles and NRMM: NOx emissions from a Low Emissions Zone (LEZ)-compliant Euro Stage IV truck or bus are limited to 0.02 g/kWh. NOx emissions from a LEZ-compliant Euro Stage IIIA excavator are limited to 0.2 to 0.6 g/kWh and 0.025 g/kWh for a Euro Stage IV excavator. Furthermore, much in the same way as for road vehicles, the industry is reporting a gap between ‘laboratory tested’ emissions and ‘real-world’ emissions, meaning that even these less stringent emissions requirements are being exceeded.
We are encouraged by the work of the London Low Emissions Construction Partnership (LLECP); the partnership bringing together London’s Cleaner Air Boroughs (Camden, Hammersmith & Fulham, Islington, Lambeth, Lewisham and Wandsworth), Kings College London and partners across the construction and demolition sector. LLECP guides the industry towards achieving ‘best in class’ pollution reduction and provides a real-time pollution monitoring platform. To date, the partnership has worked on many different projects and developments across the capital, and has investigated the effectiveness of mitigation methods such as diesel fuel additives to reduce black carbon in NRMM exhaust emissions, and using calcium magnesium acetate to reduce dust around cement batching plants in Camden.
Recent Changes to Traffic in London
The overall distance travelled by road vehicles (vehicle-kilometres) has decreased in London since 2000. This is in contrast to the rest of Great Britain, where the overall vehicle-kilometres have increased (see graph below). The most significant decreases in vehicle-kilometres are observed in Central London, followed by Inner London. This trend can be attributed largely to the implementation of London’s Low Emissions Zone (LEZ), which was phased-in from 2008. The LEZ introduced a mechanism for driving up vehicle emissions standards and discouraging more polluting vehicles from driving through the City. In 2017, the LEZ was supplemented by the ‘T-Charge’, adding more stringent vehicle emissions standards requirements and penalty charges for Central London.
Graph showing change in modal transport journeys from 2000 to 2016
Upcoming Changes to Traffic in London
April 2019 will see the introduction of the first phase of the new Ultra Low Emission Zone (ULEZ) for all vehicles in Central London, before the second and third phases (introduced in 2020 and 2021 respectively) bring about the expansion of the ULEZ areas for a wider range of vehicles. The standards will mean that by 2021, all petrol cars, vans and minibuses must be of a European Emission Standard ‘Euro’ Stage IV or Euro Stage VI for diesel, all large buses, coaches and lorries must be Euro Stage V, and all motorcycles must be Euro Stage III. Non-compliance with these standards will mean that the offending vehicles will be required to pay a hefty £100.00 daily charge, compared to a £12.50 charge for compliant vehicles.
In the meantime, there is forecast to be a slow but steady growth in the UK electric vehicle market, meaning that an ever-increasing proportion of our road vehicles will be ‘zero tailpipe emissions vehicles’. We feel it is important to note at this point that there is no such thing as a ‘zero emissions vehicle’, as all vehicles, even electric or hydrogen vehicles, produce PM emissions from tyre wear, braking and re-suspension of PM from road surfaces. Indeed, research studies now exist that suggest that the increased weight of electric vehicles (approximately 24% greater than conventional vehicles) generate higher non-exhaust PM emissions, resulting in total PM emissions which are comparable to conventional vehicles.
The Greater London Authority (GLA) predicts that the combined impacts of the ULEZ and projected changes to traffic compositions on air quality will mean that London will comply with the annual mean EU limit value for NO2 by 2025, and PM2.5 just after 2025. There remains some scepticism as to whether this policy and regulatory-based approach will lead to the real-world emissions reductions that are required to achieve compliance with the EU Directive 2008/50/EC Air Quality. For instance, in the case of road vehicle and NRMM emissions, despite the gap between ‘laboratory tested’ emissions and ‘real-world’ emissions being well documented, an alternative approach, or integration of real-world testing into the European Emission Standard ‘Euro’ regulatory approach, has not yet been accepted.
A Refresh of London Planning Policy
The GLA is currently developing a new London Plan, within which will be refreshed policies on what can be built and where. A preliminary Air Quality Assessment (AQA) would need to be carried out on major developments prior to the design process, with the aim to assess:
- The most significant sources of pollution in the area.
- Constraints imposed on the site by poor air quality.
- Appropriate design measures that could be implemented to ensure that development reduces exposure and improves air quality.
- Appropriate land uses for the site.
Currently all major developments in London must achieve ‘air quality neutral’ status and must not ‘lead to any further deterioration of existing poor air quality’. The new draft London Plan introduces a requirement for all masterplans and large-scale development proposals to achieve ‘air quality positive’ status, by actively reducing air pollution. At the time of writing, the technical methodology for testing ‘air quality positive’ has not yet been released by the GLA, although it is anticipated that the methodology will recognise opportunities to improve air quality through operational energy and transport measures, along with site layout and building form.
Integrated into the new draft London Plan is also a suggestion for boroughs to develop an Urban Greening Factor (UGF), in which different types of green surface cover are each assigned a different score based on the level of benefit they are perceived to bring. For instance, according to these recommendations the inclusion of a woodland or flower-rich grassland on site ranks as twice as effective as an area of groundcover planting. The positive effects of urban greening are well documented (enhanced biodiversity, reduction in urban heat island effect, sustainable drainage, etc), although it is interesting to note that in terms of actual infrastructure it is the management of air movement that can have a much stronger mitigating effect against pollutants than the absorption of pollutants by leaves (which is relatively minimal).
Air Quality and Brexit
Until a final Brexit agreement is reached with the EU, the topic of air quality standards and enforcement following Brexit is the subject of speculation. The Government has indicated that it does not intend to change limit values and targets for air quality following Brexit, however, concerns remain from certain academics, environmental groups and legal professionals that standards could be changed, or not aligned with future EU targets. The general consensus appears to be that the future enforcement of air quality standards is unclear and more detailed planning is required urgently to ensure that Brexit does not become an opportunity to weaken laws and regulations.
Eight Associates would like to see the UK Government acknowledge that in the face of the uncertainty surrounding Brexit, the issue of air quality remains, with certainty, an international and transboundary issue, which must continue to be addressed at international, national and local policy level. We would also urge the Government to review progress on improving air quality, not only against the EU limit values, but by implementing the UK’s pollution reduction targets for 2020 and 2030 under the Gothenburg Protocol and the newly agreed EU National Emissions Ceiling Directive, to ensure that the WHO’s standards for safe level of air pollutants are ultimately met.
Our Contribution to Air Quality
As part of the UK’s Clean Air Day 2018, Eight Associates renewed our pledge to continue to develop our air quality consultancy services. Furthermore, following increased interest amongst our clients, we intend to deepen our knowledge of the issues caused by poor air quality and will keep developing effective and practical solutions for our clients to embed in their design and construction projects across the UK.
Eight Associates offers basic and detailed air quality assessment services – please get in touch to discuss your requirements.
T 020 7043 0418, firstname.lastname@example.org.
 Michelle L Bell, Devra L Davis, and Tony Fletcher (2004) A retrospective assessment of mortality from the London smog episode of 1952: the role of influenza and pollution. Study accessed at; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1241789/
 Image courtesy of Another Nickel in the Machine (2008). Accessed at; http://www.nickelinthemachine.com/2008/11/a-proper-pea-souper-the-terrible-london-smog-of-1952/london-smog-trafalgar-sq/
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 London Air – Monitoring Sites Visualisation: Objectives vs Time. Interactive graph accessed at; http://www.londonair.org.uk/LondonAir/Data-Visualisations/objectivevstime.aspx
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 Timmers & Achten, Atmospheric Environment (2016) Non-exhaust PM emissions from electric vehicles. Article accessed at; https://www.sciencedirect.com/science/article/pii/S135223101630187X
 Greater London Authority, Draft New London Plan (2018). Online version of the draft plan accessed at; https://www.london.gov.uk/what-we-do/planning/london-plan/new-london-plan/draft-new-london-plan/