University of Leeds and King’s College London highlight knowledge gained from their research into real-world diesel driving emissions
The fall-out from the revelations that Volkswagen installed ‘defeat devices’ to manipulate diesel emissions tests highlights the importance of real-world monitoring of air pollution, academics from two UK institutions argue.
Teams at both King’s College London (KCL) and the University of Leeds have been studying the differences between laboratory-tested diesel vehicle emissions and the emission from these cars in the real world for a number of years, calling for both real-world monitoring and car emissions testing.
The University of Leeds’ Institute for Transport Studies (ITS) has highlighted some of its own research into diesel car emissions in the wake of the Volkswagen scandal, stating that it is “imperativeâ€? that the introduction of the EU’s planned real-world driving emissions test procedures in 2017 is not delayed any further.
According to the University’s Dr James Tate, ITS research suggests that in urban driving conditions Euro 5 petrol vehicles emit 7% less nitrogen oxide (NOx) per km than Euro 5 diesel cars. In addition, the latest generation of Euro 6 diesel on average emit five times the levels of NOx permitted by the Euro 6 standard, he claims.
Therefore, Dr Tate states: “If other manufacturers are not fitting ‘defeat devices’, they are still manufacturing and setting up cars to emit high amounts of the air quality pollutant NOX in real urban driving conditions.â€?
ITS has been compiling data on hundreds of cars for several years using a ‘remote sensing approach’, which can measure the emission performance of “thousands of vehicles a dayâ€?.
Dr Tate argues that this method differs from the “small numbersâ€? of vehicles officially tested in laboratories, or indeed through using on the road Portable Emission Measurement System (PEMs), which is used by the likes of Emissions Analytics.
He claims this research has demonstrated that NOx emissions from all types of diesel “have changed little in the past 15-20 yearsâ€?, and that the European Commission “has been debating the debating the discrepancy between Real Driving Emissions (RDE) and regulatory, laboratory testing since at least 2007â€?.
Dr Tate concludes: “It is imperative that the planned 2017 implementation date for RDE regulations is not delayed any longer. In the interim cities are left with the latest small city diesel cars emitting more NOx per kilometre driven than Euro VI compliant double-decker buses or fully-laden 40 tonne articulated Lorries.â€?
In London, meanwhile, KCL argues that the VW scandal has highlighted the importance of running its air quality monitoring network in the capital in collaboration with borough councils and Business Improvement Districts (BIDs).
KCL’s Environmental Research Group houses both an air quality monitoring and modelling team which works on research into pollution trends and sources in the UK capital, allowing checking of these models against real-world monitoring data from the London Air Quality Monitoring Network.
And, in a research note submitted to Defra in 2009, researchers at both KCL and the University of Leeds reported the discrepancy between expected emissions reductions and real-world monitoring data over the period 2003-2007.
According to this paper, NOx was expected to fall by around 20% in this period, but instead only fell by 8% in outer London and 7% in central and inner London. Subsequent investigations into traffic changes during this period led the researchers to conclude that “the rise in diesel vehicles in central London, not seen in outer-London, was a likely causeâ€?.
The report concludes: “The disparity between the emissions trends and those from the meteorologically-averaged measurements could not be clearer…â€?
And, according to the KCL Environmental Research Group, the recent events surrounding VW therefore “highlight the importance of maintaining a robust, real-world monitoring network such as the LAQN, to provide constant feedback to researchers and policy makers alikeâ€?.
KCL said: “The range of roadside, background and rural sites within the network allows researchers to tease out important trends and identify possible causes.â€?