Updating vehicle VOCs emissions characteristics under clean air actions in a tropical city of China

Sisi Huo; Xin Zhang; Wenshuai Xu; Juan Dang; Fei Xu; Wenjing Xie; Chenliang Tao; Yanan Han; Xinning Liu; Zhuochao Teng; Rongfu Xie; Xiaocong Cao; Qingzhu Zhang

doi:10.1016/j.scitotenv.2024.172733

Updating vehicle VOCs emissions characteristics under clean air actions in a tropical city of China

Sci Total Environ. 2024 Apr 23:930:172733. doi: 10.1016/j.scitotenv.2024.172733. Online ahead of print.

Authors

Sisi Huo¹, Xin Zhang², Wenshuai Xu³, Juan Dang¹, Fei Xu¹, Wenjing Xie⁴, Chenliang Tao¹, Yanan Han¹, Xinning Liu¹, Zhuochao Teng¹, Rongfu Xie⁴, Xiaocong Cao⁴, Qingzhu Zhang⁵

Affiliations

¹ Environmental Research Institute, Shandong University, Qingdao 266237, China.
² Environmental Research Institute, Shandong University, Qingdao 266237, China; State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China. Electronic address: zhangxin199307@pku.edu.cn.
³ Hainan Research Academy of Environmental Sciences, Haikou 571126, China; Hainan Provincial Ecological and Environmental Monitoring Center, Haikou 571126, China. Electronic address: xuwenshuai@hotmail.com.
⁴ Hainan Research Academy of Environmental Sciences, Haikou 571126, China.
⁵ Environmental Research Institute, Shandong University, Qingdao 266237, China. Electronic address: zqz@sdu.edu.cn.

PMID: 38663608
DOI: 10.1016/j.scitotenv.2024.172733

Abstract

In the context of clean air actions in China, vehicle emission limits have been continuously tightened, which has facilitated the reduction of volatile organic compounds (VOCs) emissions. However, the characteristics of VOC emissions from vehicles with strict emission limits are poorly understood. This study investigated the VOC emission characteristics from vehicles under the latest standards based on tunnel measurements, and identified future control strategies for vehicle emissions. The results showed that the highest percentage of VOCs from vehicle consisted of alkanes (80.9 %), followed by aromatics (15.8 %) and alkenes (3.1 %). Alkanes had the most significant ozone formation potential due to their high concentrations, in contrast to the aromatics that have been dominant in previous studies. The measured fleet-average VOC emission factor was 71.3 mg·km^-1, including tailpipe emissions of 39.6 mg·km^-1 and evaporative emissions of 31.7 mg·km^-1. The VOC emission factors of the subgroups were obtained. The emission of evaporated VOCs accounted for 44.5 % of the total vehicle VOC emissions, which have increased substantially from previous studies. In addition, the emission characteristics of vehicles that are under the latest emission threshold values have changed significantly, and the mixing ratio of toluene/benzene (T/B) has been updated to 3:1. This study updates the VOCs emission factors of vehicles under clean air actions and highlights the future mitigation policies should focus on reducing evaporative VOC emissions.

Keywords: Clean air actions; Emission factors; Tunnel experiments; VOCs; Vehicle emissions.