Imperial College London


Faculty of MedicineSchool of Public Health

Research Associate







Building E - Sir Michael UrenWhite City Campus





Publication Type

2 results found

Desouza CD, Marsh DJ, Beevers SD, Molden N, Green DCet al., 2021, A spatial and fleet disaggregated approach to calculating the NOX emissions inventory for non-road mobile machinery in London, Atmospheric Environment: X, Vol: 12, Pages: 1-8, ISSN: 2590-1621

The latest London atmospheric emissions inventory (2016), which is calculated using fuel consumption and construction employment, estimates that, the construction sector contributes 34% of the total PM10 emissions (the largest source), and 7% of the total NOX emissions (5th largest source). These contribute significantly to NO2 and PM2.5 pollution problems in London, which is a major concern for public health. Real-world emission factors from tail-pipe measurements were coupled to a register for construction machinery, to develop a novel ‘spatial and fleet disaggregated’ emissions inventory for the construction sector in London. This method estimated 1294 tonnes of NOX in 2018 and 1578 tonnes of NOX in 2019 from non-road mobile machinery in the construction sector, approximately 55% and 45% lower for 2018 and 2019 respectively, than the current (2016) London atmospheric emissions inventory (2850 tonnes). However, compared to the current London atmospheric emissions inventory, the new NOX emissions are higher in central London, under-estimating the importance of this source in central London. The fleet-disaggregated emissions inventory enables potential policy to be developed by focusing on high-emitters registered on the London database. As a demonstration, two emission abatement scenarios were modelled – first: by retrofitting older generators with a SCR-DPF system, a potential 53% reduction in overall NOX emissions was predicted from all NRMM; and second: by accelerating the excavator fleet-turnover – a more modest 2-tonne reduction in overall NOX emissions was predicted from all NRMM in London.

Journal article

Desouza CD, Marsh DJ, Beevers SD, Molden N, Green DCet al., 2020, Real-world emissions from non-road mobile machinery in London, Atmospheric Environment, Vol: 223, ISSN: 1352-2310

The 2016 London atmospheric emissions inventory estimates that, the construction sector contributes 34% of the total PM10 and 7% of the total NOX – the largest and 5th largest sources, respectively. Recent on-road light duty diesel vehicle emission tests have shown significant differences between real-world NOX emissions compared with results from laboratory based regulatory tests. The aim of this study was therefore to quantify the ‘real-world’ tail-pipe NOX, CO2, and particle emissions, for 30 of the most commonly used construction machines in London under normal working conditions. The highest NOX emissions (g/kWh) were from theolder engines (Stage III-A ~4.88 g/kWh and III-B ~4.61 g/kWh), these were reduced significantly (~78%) in the newer (Stage IV ~1.05 g/kWh) engines due to more advanced engine management systems and exhaust after treatment. One Stage IV machine emitted NOX similar to a Stage III-B machine, the failure of this SCR was only detectable using PEMS as no warning was given by the machine. Higher NOX conformity factors were observed for Stage IV machines, due to the lower NOX emission standards, which these machines must adhere to. On average, Stage III-B machines (~525 g/kWh) emitted the lowest levels of CO2 emissions, compared to Stage III-A (~875 g/kWh) and Stage IV (~575 g/kWh) machines. Overall, a statistically significant (~41%) decrease was observed in the CO2 emissions (g/kWh) between Stage III-A and III-B machines, while no statistically significant difference was found between Stage III-B and IV machines. Particle mass measurements, which were only measured from generators, showed that generators of all engine sizes were within their respective Stage III-A emission standards. A 95% reduction in NOX and 2 orders of magnitude reduction in particle number was observed for a SCR-DPF retrofitted generator, compared to the same generator prior to exhaust gas after-treatment strategy.

Journal article

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