Abstract
Particulate polycyclic aromatic hydrocarbons (p-PAHs) emitted from diesel vehicles are of concern because of their significant health impacts. Laboratory tests, road tunnel and roadside experiments have been conducted to measure p-PAH emissions. While providing valuable information, these methods have limited capabilities of characterizing p-PAH emissions either from individual vehicles or under real-world conditions. We employed a portable emissions measurement (PEMS) to measure real-world emission factors of priority p-PAHs for diesel vehicles representative of an array of emission control technologies. The results indicated over 80% reduction in p-PAH emission factors comparing the China V and China II emission standard groups (113 μg kg−1 vs. 733 μg kg−1). The toxicity abatement in terms of Benzo[a]pyrene equivalent emissions was substantial because of the large reductions in highly toxic components. By assessing real traffic conditions, the p-PAH emission factors on freeways were lower than on local roads by 52% ± 24%. A significant correlation (R2~0.85) between the p-PAH and black carbon emissions was identified with a mass ratio of approximately 1/2000. A literature review indicated that diesel p-PAH emission factors varied widely by engine technology, measurement methods and conditions, and the molecular diagnostic ratio method for source apportionment should be used with great caution.
Highlights
Increasing evidence has been reported showing strong associations between vehicle emissions and adverse health impacts[1,2,3,4,5,6,7]
Liang et al reported that the mass fraction of 3 and 4-ring Particulate polycyclic aromatic hydrocarbons (p-polycyclic aromatic hydrocarbons (PAHs)) was 91% of the total p-PAH emissions from a diesel generator[29], and Rogge et al reported that 3 and 4-ring p-PAHs were responsible for 82% of the total p-PAH emissions, on average, from two diesel trucks[10]
We employed a portable emissions measurement system (PEMS) to collect on-road particle samples from fourteen in-use heavy-duty diesel vehicles to address the concern about potential discrepancy between real-world p-PAH emissions and results measured in laboratory
Summary
Increasing evidence has been reported showing strong associations between vehicle emissions and adverse health impacts[1,2,3,4,5,6,7]. The representativeness of the testing location is often criticized, since these ambient sampling methods usually cover limited traffic circumstances (e.g., in terms of the location, slope, and traffic conditions)[20] Increasing attention from both researchers and policy-makers has been focused on the portable emissions measurement system (PEMS), which is an effective tool for evaluating off-cycle emissions (e.g., as in the Volkswagen diesel emission scandal), over the past decade[21,22,23]. Fourteen in-use heavy-duty diesel vehicles (HDDVs), a reasonable sample size for a PEMS testing study, were recruited to measure the species-resolved p-PAH emissions under real-world driving conditions. These HDDVs were declared to comply with China I to China V standards and supposed to use improved engine and after-treatment technologies to meet the increasingly stringent emission limits (see Supplementary Table S2). This study provides useful results for better characterizing real-world p-PAH emissions from diesel vehicles
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
