A new method to compare vehicle emissions measured by remote sensing and laboratory testing: high-emitters and potential implications for emission inventories

Smit, Robin and Bluett, Jeff (2011) A new method to compare vehicle emissions measured by remote sensing and laboratory testing: high-emitters and potential implications for emission inventories. Science of the Total Environment, 409 13: 2626-2634. doi:10.1016/j.scitotenv.2011.03.026


Author Smit, Robin
Bluett, Jeff
Title A new method to compare vehicle emissions measured by remote sensing and laboratory testing: high-emitters and potential implications for emission inventories
Journal name Science of the Total Environment   Check publisher's open access policy
ISSN 0048-9697
1879-1026
Publication date 2011-06-01
Sub-type Article (original research)
DOI 10.1016/j.scitotenv.2011.03.026
Open Access Status Not yet assessed
Volume 409
Issue 13
Start page 2626
End page 2634
Total pages 9
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 2304 Environmental Chemistry
2305 Environmental Engineering
2310 Pollution
2311 Waste Management and Disposal
2700 Medicine
Abstract A new method is presented which is designed to investigate whether laboratory test data used in the development of vehicle emission models adequately reects emission distributions, and in particular the inuence of high-emitting vehicles. The method includes the computation of a 'high-emitter' or 'emission distribution' correction factor for use in emission inventories. In order to make a valid comparison we control for a number of factors such as vehicle technology, measurement technique and driving conditions and use a variable called 'Pollution Index' (g/kg). Our investigation into one vehicle class has shown that laboratory and remote sensing data are substantially different for CO, HC and NO emissions, both in terms of their distributions as well as in their mean and 99-percentile values. Given that the remote sensing data has larger mean values for these pollutants, the analysis suggests that high-emitting vehicles may not be adequately captured in the laboratory test data. The paper presents two different methods for the computation of weighted correction factors for use in emission inventories based on laboratory test data: one using mean values for six 'power bins' and one using multivariate regression functions. The computed correction factors are substantial leading to an increase for laboratory-based emission factors with a factor of 1.7-1.9 for CO, 1.3-1.6 for HC and 1.4-1.7 for NO (actual value depending on themethod). However, it also clear that there are points that require further examination before these correction factors should be applied. One important step will be to include a comparison with other types of validation studies such as tunnel studies and near-road air quality assessments to examine if these correction factors are conrmed. If so, we would recommend using the correction factors in emission inventories for motor vehicles.
Formatted abstract
A new method is presented which is designed to investigate whether laboratory test data used in the development of vehicle emission models adequately reflects emission distributions, and in particular the influence of high-emitting vehicles. The method includes the computation of a ‘high-emitter’ or ‘emission distribution’ correction factor for use in emission inventories. In order to make a valid comparison we control for a number of factors such as vehicle technology, measurement technique and driving conditions and use a variable called ‘Pollution Index’ (g/kg). Our investigation into one vehicle class has shown that laboratory and remote sensing data are substantially different for CO, HC and NOx emissions, both in terms of their distributions as well as in their mean and 99-percentile values. Given that the remote sensing data has larger mean values for these pollutants, the analysis suggests that high-emitting vehicles may not be adequately captured in the laboratory test data.

The paper presents two different methods for the computation of weighted correction factors for use in emission inventories based on laboratory test data: one using mean values for six ‘power bins’ and one using multivariate regression functions. The computed correction factors are substantial leading to an increase for laboratory-based emission factors with a factor of 1.7–1.9 for CO, 1.3–1.6 for HC and 1.4–1.7 for NOx (actual value depending on the method). However, it also clear that there are points that require further examination before these correction factors should be applied. One important step will be to include a comparison with other types of validation studies such as tunnel studies and near-road air quality assessments to examine if these correction factors are confirmed. If so, we would recommend using the correction factors in emission inventories for motor vehicles.

Research Highlights
► A new method to verify vehicle emissions test data. ► Compare remote sensing and laboratory test data. ► Assess if vehicle emission models adequately reflect high-emitting vehicles. ► Computation of a high-emitter correction factor for use in emission inventories.
Keyword High-emitter
Remote sensing
Vehicle emission inventory
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Civil Engineering Publications
 
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