Distance-based emission factors from vehicle emission remote sensing measurements

Abstract. Diesel-powered vehicles are intensively used in urban areas for transporting goods and people but can substantially contribute to high emissions of black carbon (BC), organic carbon (OC), and other gaseous pollutants. Strategies aimed at controlling mobile emissions sources thus have the potential to improve air quality as well as help mitigate impacts of air pollutants on climate, ecosystems, and human health. However, in developing countries there are limited data on the BC and OC emission characteristics of diesel-powered vehicles and thus there are large uncertainties in the estimation of the emission contributions from these sources. We measured BC, OC and other inorganic components of fine particulate matter (PM), as well as carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), ethane, acetylene, benzene, toluene, and C2-benzenes under real-world driving conditions of 20 diesel-powered vehicles encompassing multiple emission level technologies in Mexico City with the chasing technique using the Aerodyne mobile laboratory. Average BC emission factors ranged from 0.41–2.48 g/kg-fuel depending on vehicle type. The vehicles were also simultaneously measured using the cross-road remote sensing technique to obtain the emission factors of nitrogen oxide (NO), CO, total hydrocarbons, and fine PM, thus allowing the inter-comparison of the results from the two techniques. There is overall good agreement between the two techniques and both can identify high and low emitters but substantial differences were found in some of the vehicles, probably due to the ability of the chasing technique to capture a larger diversity of driving conditions in comparison to the remote sensing technique. A comparison of the results with the US-EPA MOVES-2014b model showed that the model underestimates CO, OC, and selected VOC species whereas there is better agreement for NOx and BC. Larger OC / BC ratios were found in comparison to ratios measured in California using the same technique, further demonstrating the need for using locally-obtained diesel-powered vehicle emission factors database in developing countries in order to reduce the uncertainty in the emissions estimates and to improve the evaluation of the effectiveness of emissions reduction measures.

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Fleet-based vehicle emission factors using low-cost sensors: Case study in parking garages

Transportation Research Part D Transport and Environment ◽

10.1016/j.trd.2020.102635 ◽

2020 ◽

pp. 102635

Author(s):

Bingqi Liu ◽

Naomi Zimmerman

Keyword(s):

Low Cost ◽

Emission Factors ◽

Vehicle Emission ◽

Parking Garages

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Erratum to “On-road remote sensing of petrol vehicle emissions measurement and emission factors estimation in Hong Kong”

Atmospheric Environment ◽

10.1016/j.atmosenv.2004.04.003 ◽

2004 ◽

Vol 38 (21) ◽

pp. 3541 ◽

Cited By ~ 2

Author(s):

T.L Chan ◽

Z Ning ◽

C.W Leung ◽

C.S Cheung ◽

W.T Hung ◽

...

Keyword(s):

Remote Sensing ◽

Hong Kong ◽

Vehicle Emissions ◽

Emission Factors

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On-road remote sensing of petrol vehicle emissions measurement and emission factors estimation in Hong Kong

Atmospheric Environment ◽

10.1016/j.atmosenv.2004.01.031 ◽

2004 ◽

Vol 38 (14) ◽

pp. 2055-2066 ◽

Cited By ~ 45

Author(s):

T.L. Chan ◽

Z. Ning ◽

C.W. Leung ◽

C.S. Cheung ◽

W.T. Hung ◽

...

Keyword(s):

Remote Sensing ◽

Hong Kong ◽

Vehicle Emissions ◽

Emission Factors

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Have vehicle emissions of primary NO2 peaked?

Faraday Discussions ◽

10.1039/c5fd00162e ◽

2016 ◽

Vol 189 ◽

pp. 439-454 ◽

Cited By ~ 36

Author(s):

David C. Carslaw ◽

Tim P. Murrells ◽

Jon Andersson ◽

Matthew Keenan

Keyword(s):

Remote Sensing ◽

Urban Areas ◽

Vehicle Emissions ◽

Remote Sensing Data ◽

Vehicle Emission ◽

Oxides Of Nitrogen ◽

Vehicle Exhaust ◽

Road Vehicles ◽

Limit Values ◽

Sensing Data

Reducing ambient concentrations of nitrogen dioxide (NO2) remains a key challenge across many European urban areas, particularly close to roads. This challenge mostly relates to the lack of reduction in emissions of oxides of nitrogen (NOx) from diesel road vehicles relative to the reductions expected through increasingly stringent vehicle emissions legislation. However, a key component of near-road concentrations of NO2 derives from directly emitted (primary) NO2 from diesel vehicles. It is well-established that the proportion of NO2 (i.e. the NO2/NOx ratio) in vehicle exhaust has increased over the past decade as a result of vehicle after-treatment technologies that oxidise carbon monoxide and hydrocarbons and generate NO2 to aid the emissions control of diesel particulate. In this work we bring together an analysis of ambient NOx and NO2 measurements with comprehensive vehicle emission remote sensing data obtained in London to better understand recent trends in the NO2/NOx ratio from road vehicles. We show that there is evidence that NO2 concentrations have decreased since around 2010 despite less evidence of a reduction in total NOx. The decrease is shown to be driven by relatively large reductions in the amount of NO2 directly emitted by vehicles; from around 25 vol% in 2010 to 15 vol% in 2014 in inner London, for example. The analysis of NOx and NO2 vehicle emission remote sensing data shows that these reductions have been mostly driven by reduced NO2/NOx emission ratios from heavy duty vehicles and buses rather than light duty vehicles. However, there is also evidence from the analysis of Euro 4 and 5 diesel passenger cars that as vehicles age the NO2/NOx ratio decreases. For example the NO2/NOx ratio decreased from 29.5 ± 2.0% in Euro 5 diesel cars up to one year old to 22.7 ± 2.5% for four-year old vehicles. At some roadside locations the reductions in primary NO2 have had a large effect on reducing both the annual mean and number of hourly exceedances of the European Limit Values of NO2.

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