Characteristics and health risks of parent, alkylated, and oxygenated PAHs and their contributions to reactive oxygen species from PM2.5 vehicular emissions in the longest tunnel in downtown Xi'an, China

Yali Lei; Zexuan Wang; Hongmei Xu; Rong Feng; Ningning Zhang; Yue Zhang; Wei Du; Qian Zhang; Qiyuan Wang; Lijuan Li; Linli Qu; Steven Sai Hang Ho; Zhenxing Shen; Junji Cao

doi:10.1016/j.envres.2022.113357

Characteristics and health risks of parent, alkylated, and oxygenated PAHs and their contributions to reactive oxygen species from PM_2.5 vehicular emissions in the longest tunnel in downtown Xi'an, China

Environ Res. 2022 Sep;212(Pt C):113357. doi: 10.1016/j.envres.2022.113357. Epub 2022 May 14.

Authors

Yali Lei¹, Zexuan Wang², Hongmei Xu³, Rong Feng², Ningning Zhang⁴, Yue Zhang⁵, Wei Du⁶, Qian Zhang⁷, Qiyuan Wang⁴, Lijuan Li⁴, Linli Qu⁸, Steven Sai Hang Ho⁹, Zhenxing Shen², Junji Cao⁴

Affiliations

¹ Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China; Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, China.
² Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
³ Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710049, China. Electronic address: xuhongmei@mail.xjtu.edu.cn.
⁴ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710049, China.
⁵ Henan Research Academy of Ecological and Environmental Sciences, Zhengzhou, 450003, China.
⁶ Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, China.
⁷ Key Laboratory of Northwest Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
⁸ Hong Kong Premium Services and Research Laboratory, Kowloon, Hong Kong SAR, China.
⁹ Division of Atmospheric Sciences, Desert Research Institute, Reno, NV, 89512, United States.

PMID: 35580669
DOI: 10.1016/j.envres.2022.113357

Abstract

A vehicular emission study was conducted in the longest inner-city tunnel in Xi'an, northwestern China in four time periods (I: 07:30-10:30, II: 11:00-14:00, III: 16:30-19:30, and IV: 20:00-23:00 LST). A sum of 40 PAHs, including parent (p-PAHs), alkylated (a-PAHs), and oxygenated (o-PAHs) in fine particulate matter (PM_2.5) were quantified. The relationships between the PAHs and the formation of reactive oxygen species (ROS) were also studied. The average total quantified PAHs concentration was 236.3 ± 48.3 ng m^-3. The p-PAHs were found to be the most dominated group, accounting for an average of 88.1% of the total quantified PAHs, followed by a-PAHs (6.1%) and o-PAHs (5.8%). On the base of the number of aromatic rings, the groups of ≤5 rings (92.5 ± 1.2%) had higher fractions than the high ones (≥6 rings, 7.5 ± 1.2%) for pPAHs. Diurnal variations of PAHs subgroups exhibited the highest levels in Period III, consistent with the largest traffic counts in evening rush hours. However, less reduction of few PAHs in the night period demonstrates that the emissions of compressed natural gas (CNG) and methanol-fueled vehicles cannot be ignored while their contribution increased. High ROS activity levels were observed in the traffic-dominated samples, implying the potential oxidative damages to humans. Additionally, diurnal variation of the ROS activity was consistent with the total quantified PAHs and toxic equivalency of benzo[a]pyrene. Good correlations (R > 0.6, p < 0.05) were seen between individual groups of PAHs (especially for 3-5 rings p-PAHs, 4 rings a-PAHs, and 2-3 rings o-PAHs) and ROS activity, supporting that the vehicular emitted PAHs possibly initiate oxidative stress. The multiple linear regression analysis further illustrated that chrysene contributed the highest (25.0%) to ROS activity. In addition to highlighting the potential hazards to the PAHs from the vehicular emission, their roles to mitigate the health effects by formations of ROS were firstly reported in northwestern China.

Keywords: Diurnal variations; Health risk assessment; Motor vehicle emissions; Oxidative stress; Polycyclic aromatic hydrocarbons.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / analysis
Air Pollutants* / toxicity
China
Environmental Monitoring
Humans
Particulate Matter / analysis
Particulate Matter / toxicity
Polycyclic Aromatic Hydrocarbons* / analysis
Polycyclic Aromatic Hydrocarbons* / toxicity
Reactive Oxygen Species / analysis
Vehicle Emissions / analysis
Vehicle Emissions / toxicity

Substances

Air Pollutants
Particulate Matter
Polycyclic Aromatic Hydrocarbons
Reactive Oxygen Species
Vehicle Emissions