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Corresponding uncertainty

What the reports say


What this means in terms of ‘confidence’

tightening ‘Euro’ standards

will achieve certain ‘Euro’ standards for engines, including standards that have not yet been agreed (Euro VI for lorries and buses).  

reductions.  A German  study suggests that they have, in practice, led to no reductions; a DfT-sponsored study suggests that, for diesel LGVs, “the changes would lead to an overall increase of about 2.5% in the estimates of UK NOx emissions from road transport in 2010, with smaller overall increases in 2015 and 2020.” http://www.dft.gov.uk/pgr/roads/environment/research/cqvcf/emissionsfactors/emissionsfactorsforeuroiiand3825

to improvements in vehicle engines may thus not be achieved.   

NOx emissions from the Belvedere incinerator, Rochester power station, etc. are not included in the model

Background NOx levels assumed in the models might be too low.

Although the models take into account emissions from a new Colnbrook incinerator, they do not include emissions from:

the newly approved coal-fired power station in Rochester (approved by Medway Council on 2 January 2008);

the waste incinerator at Belvedere (LB Bexley); or

any growth in railway NOx sources after 2010, despite the fact that the Surface Access report notes that “Other rail network developments were assumed, for air passenger demand forecasting in and around London, including the Channel Tunnel Rail Link, London Underground upgrades in line with PPP commitments and extensions to the Docklands Light Railway”.

Atkins (2007) Demonstrating confidence in the PSDH air quality work,

BAA Heathrow (2007) Surface Access Report, para. 184

The new power station at Rochester, waste incinerator at Belvedere, growth in railway sources after 2010 etc. could all increase the assumed baseline levels of NOx, but have not been included in the models.  As such, the baseline air pollution level may be higher than predicted.

Traffic on the roads near Heathrow was boosted in the base year because of Terminal 5 construction and M25 widening.   

Demand on the road network around Heathrow is well above available capacity, so ‘back-casting’ may well lead to under-prediction of future baseline levels.  The model does not seem to include the

“Construction effects on road traffic should be discounted in base and future year scenarios by applying derived adjustments (and before backcasting)”.

However, given the amount of construction planned for the London and South East region over the next 20+ years, it would be more prudent to assume ongoing construction works on roads near Heathrow.

Atkins (2007) Demonstrating confidence in the PSDH air quality work, Table 2.4.

Assuming a ‘no construction’ scenario for the roads near Heathrow is probably unrealistic, given the development pressures on the area.  Such a scenario would lead to an unrealistically low

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