Session 2009-10
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Supplementary memorandum submitted by the Greater London Authority (AQ 32)

This letter responds to the request from the Committee for further information relating to the London Low Emission Zone (LEZ) and the study that has been commissioned by the GLA into the health impacts of poor air quality in London.

In summary, the GLA recommends that the Government should take the following actions:

· Establish a national oxides of nitrogen (NOx) standard for Low Emission Zones across the country.

· Carry out trials of NOx abatement equipment on a range of vehicle types.

· Introduce a testing and certification scheme for NOx abatement equipment.

· Include a nitrogen dioxide (NO2) limit as part of the standards for NOx abatement equipment.

· Introduce a NOx retrofit incentive programme to encourage widespread uptake of NOx abatement equipment and to mitigate the costs to operators of possible LEZ extensions to NOx.

London Low Emission Zone

The LEZ currently has standards for particulate matter (PM) for HGVs, buses and coaches. There are a number of ways in which operators with older vehicles that do not meet these standards can become compliant, including vehicle replacement and the retrofitting of PM abatement equipment. The retrofitting option is especially important as for many operators, particularly smaller organisations, it is more cost effective than vehicle replacement. To allow retrofitted vehicles to be classified as compliant with the LEZ standards, a thorough testing and certification scheme for abatement equipment is required. This provides reassurance to both operators and scheme administrators alike that a particular piece of equipment genuinely makes the emission reductions required.

The LEZ has been effective at reducing emissions of PM10 across London from the heaviest, most individually polluting diesel vehicles. Given that the problem of NO2 pollution in London is even more severe than that of PM10, and that concentrations of NO2 are high at a number of locations across the capital, ideally the LEZ would also include a NOx standard. However, without a national certification scheme for NOx abatement equipment, as there is for PM abatement equipment, it is not practical to introduce such a standard, as this would prevent vehicle retrofit from being a compliance option. The Mayor has proposed in his draft Air Quality Strategy to introduce a Euro IV NOx standard for HGVs, buses and coaches as part of the LEZ from 2015. This would be dependent on the Government delivering a national NOx standard for Low Emission Zones, with an associated NOx abatement equipment testing and certification regime for vehicle retrofit.

Central Government Support

A large number of towns and cities in the UK are exceeding the EU limit values for NO2. It is therefore in the Government’s interest to address this problem at a national level with a solution that will effect change across the whole country. A UK-wide approach would make it easier for local or regional authorities to implement control or incentive schemes in areas with high concentrations. It would also ensure that schemes are consistent with each other, minimising compliance costs for operators.

The Mayor cannot take effective action to address NOx emissions in London through the LEZ unless the Government establishes a national NOx standard with an associated testing and certification regime for abatement equipment. Such a regime would be necessary in order to be sure that retrofitted vehicles meet the standard. The GLA Group does not have the resources to develop such a certification scheme, which the Government is best placed to deliver, especially as it could then be applied to other potential future Low Emission Zone schemes in the country. Were the Government to do this, a grant scheme or incentive for vehicle retrofit would mitigate to some extent the compliance costs for vehicle operators as well as encouraging the widespread uptake of abatement equipment across the country. So far the Government has provided no indication that it endorses this approach. This may be due to concerns about the effectiveness of NOx abatement equipment, which the GLA does not share.


Based on TfL’s experience of developing standards and certification schemes for equipment and vehicles for the LEZ and the current development of NOx abatement technology, it is our judgement that developing a NOx standard would require a minimum of three years to complete. Therefore the earliest a NOx standard could be in place would be 2013.

In addition, the Mayor must consider the potential compliance costs for vehicle operators and the impacts these could have on the wider London economy. The Mayor has set out his desire to announce proposed alterations to the LEZ as early as possible to maximise compliance time. The Mayor feels that five years (from the launch of the Air Quality Strategy in 2010 to the possible introduction of a NOx standard to the LEZ in 2015) would be an appropriate compliance period for operators.

Developing a NOx Standard and Potential Barriers

TfL has identified distinct phases that would need to be undertaken to develop a NOx standard:

1. Research of NOx abatement solutions that could potentially bring HGVs, buses and coaches up to the Euro IV standard for NOx.

A 30% reduction in NOx emissions would be required to bring a Euro III vehicle to the Euro IV standard and a 60% reduction would be needed for a Euro I vehicle to meet the Euro IV standard. Abatement equipment would therefore need to be highly efficient to achieve these reductions consistently.

The Euro standards enforce a NOx cap with no reference to the split in emissions between NO and NO2. Vehicle manufacturers therefore seek to limit total NOx emissions irrespective of the ratio of NO2 to NO from a vehicle. Concerns have been expressed that the fitting of NOx abatement equipment sometimes increases emissions of NO2 as a proportion of NOx from a vehicle. NO2 adversely affects health and this is therefore a concern to air quality professionals, especially since national objectives and EU limit values are for NO2 rather than NO, which poses much less of a threat to human health.

However, the data giving rise to these concerns has been based on ‘drive by’ emission tests. These are remote measurements taken as a vehicle drives by, so they are recorded at only one speed and load condition. This means that they are not representative of all conditions and cannot be compared to legislated emissions (ie. Euro standards). It is true that some exhaust emission abatement technologies that contain platinum group metals can increase NO2 emissions. However, it cannot be stated that PM or NOx abatement equipment increase NO2 per se. The GLA would recommend that any national NOx standard should also include limits for NO2.

Abatement devices can deliver a large NOx reduction such that even where a higher percentage of total NOx emitted at the tailpipe is NO2, there is still a substantial reduction in overall NO2 emitted from that vehicle. It may be necessary to accept that to develop a commercially viable device, some increase in the NO2 ratio may be necessary within an envelope which nevertheless reduces the overall mass of NO2 emitted.

As well as establishing a retrofit standard, consideration would need to be given to in-use (ongoing) compliance of abatement equipment. For example, Selective Catalytic Reduction (SCR) systems need to be replenished with a reductant (typically urea solution) in order to reduce NOx emissions. In new vehicles, when the urea tank is empty, the engine’s power is reduced to indicate that the SCR system is not working. Retrofitting the engines of older vehicles in such a way is not likely to be feasible as a monitoring solution. Some other means of monitoring in-service performance, either via the technical standard developed or via the certification system, would need to be developed.

2. Pilot trials of technologies

Retrofit technologies such as SCR have been trialled by TfL in its bus fleet and have demonstrated a 65% NOx reduction over a 'real-world' London drive cycle. A further pilot of NOx abatement on the TfL bus fleet is to be undertaken towards the end of 2010. Data from this trial could contribute to developing a technical standard for national NOx abatement equipment. The GLA recommends that the Government should undertake further trials on a range of vehicle types.

3. Establishment of a national standard

Meeting the NO2 EU limit values is a problem across the UK which requires action at national level. The vehicles addressed by the LEZ (HGVs, buses and coaches) tend to be long-range vehicles that travel between cities. A single national LEZ standard would make compliance more straightforward for operators: vehicles compliant in one area would be compliant across the country. In addition, regional markets would not become distorted by different, local emission standards.

It is strongly recommended that detailed consultation with the abatement equipment industry should form a core part of the development of any standard to ensure that it can deliver commercially viable abatement devices that meet the standard. The abatement equipment industry would be required to invest significant amounts of money in advance of a NOx standard being implemented to develop market-ready solutions and put these forward for approval within the national framework. The Government should make its intentions clear so that the UK is seen as a potential market for abatement devices. This would provide confidence to the industry and would ultimately keep prices for vehicle operators competitive.

Establishment of a national approval mechanism for abatement devices would be critical. Devices would need to be tested against a rigorous approval system to ensure that they operated as required under the standard, thus providing assurance to authorities administering control schemes. The approval procedure would also need to provide operators with confidence that the systems fitted would be safe, effective and not damage their vehicles.

4. Establishment of a national certification system for abatement equipment

A control system such as the LEZ cannot operate without effective certification to ensure that standards are adhered to and to prevent fraud. There are three components to the current LEZ certification scheme for abatement equipment:

· Company (or supplier) approval

· Technology approval

· Vehicle certification.

The Vehicle Certification Agency (VCA) is involved in the company approval and technology approval, which requires the supplier to pay a one-off cost (currently between £3,000 and £5,000) followed by annual reassessment costs of around £1,000. the Vehicle and Operator Services Agency (VOSA) carries out the vehicle certification process, which can be combined with the vehicle’s annual test. VOSA charges a small fee to the operator for the certification process (£32), which is reduced to £19 if it is combined with the annual test.

NOx abatement for light duty vehicles

Unlike heavy duty vehicles, NOx exhaust after-treatment abatement technology (such as SCR) is not common in light duty vehicles. The different duty cycles and lower exhaust temperature of light duty vehicles mean that the technology is not as effective on these vehicles. In addition, the physical size of some systems means they may be difficult to retrofit to light duty vehicles. Economically, such NOx abatement systems are likely to cost more than the vehicle is worth in many cases.

Light duty vehicles generally employ exhaust gas recirculation (EGR) to control NOx, which is integrated into the engine’s control system and less suited for retrofit. EGR systems alone would not provide the NOx reduction required to bring early Euro standard vehicles up to a Euro 4 level for NOx.

Given that viable and affordable retrofit options are not currently available for light duty vehicles, it would be extremely difficult to introduce a NOx element to the LEZ for these vehicles in the short-term. This is because the compliance costs would be extremely high for non-compliant operators as they would have to replace their vehicle (rather than retrofit) to meet the NOx standard. Longer-term this could change if more viable and affordable retrofit options become available.

Health study into the impacts of poor air quality in London

The GLA has commissioned a study into the health impacts of poor air quality in London. This will provide estimates of the number of deaths per annum attributable to poor air quality in London and the total loss of life years implied by these numbers. The research will use the coefficients recommended by the Government’s advisory committee, the Committee on the Medical Effects of Air Pollutants (COMEAP) in its recently published report on mortality and long-term exposure to air pollution, as well as ‘uncertainty bounds’ to take into account the possible unknown factors that could also have an impact on health. We believe that this is the first piece of research into the health effects of poor air quality on London’s population as a whole for several years, and certainly the first since COMEAP published its new coefficients. The high-level results of the study will be included in the next draft of the Mayor’s Air Quality Strategy, which is due to be published for public consultation in the spring. The final report of the study will also be published on the GLA website.

The Strategy will include policies to raise awareness of air quality in London. For example, the GLA will develop a website that will provide information and advice about air quality in London and will seek to work with central government, boroughs and health professionals on awareness campaigns. We hope that the clear data on health impacts that the study will provide will help persuade Londoners to make changes to behaviour to reduce emissions. The data should also encourage policy makers in London to appreciate the urgent need for measures to reduce concentrations in the capital. We believe that policies could be more effective if developed and implemented jointly by air quality practitioners and the health sector. Unfortunately, in London, the public health sector is quite disparate and it is not always easy to take coordinated action. If the Government were to take a lead by involving the Department of Health more in air quality policy development, it is likely that this would encourage coordination at a local level as well.

The results of the study will be broken down to ward level. This will help the GLA and London boroughs apply particular measures where they will have most impact. TfL is currently developing packages of measures that will improve air quality at the small number of locations in central London that are at risk of exceeding EU limit values for PM10. The experiences gained in implementing these packages could allow a similar approach to be taken at other locations where concentrations may not be quite so high but where population exposure is a problem. The GLA will share information with the boroughs to identify such locations and will help them to develop packages of measures to improve local air quality.

22 February 2010

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Prepared 13:59 on 15th March 2010