Effects of short-duration vehicular traffic control on volatile organic compounds in roadside atmosphere

Traffic air pollution control is an important aspect of air quality management in urban areas. In this study, we investigated whether short-duration vehicular traffic control could be applied as a temporary tool to improve the roadside air quality based on concentrations of roadside volatile organic compounds (VOCs). Experiments were conducted targeting a 30-min no-vehicle event observed on 30th May 2019 (13:30-14:00) in Central Taiwan. Although the event was not imposed for air quality management, it provided an excellent opportunity to evaluate it as a potential tool of air quality management. Roadside air samples were collected before, during and after the no-vehicle event from two locations in Central Taiwan. Samples were analyzed for a total of 87 target VOCs. Results showed that alkanes, aromatics and oxygenated organics were the major contributors of roadside VOCs. Mean concentrations of the sum of detected VOCs (Sigma VOCs) were about 8%-24% lower during the novehicle event compared to those before or after the event. Correlation analysis showed that a total of 20 VOCs were related to traffic emissions. During-event concentrations of the sum of those traffic related VOCs were less than pre- or post-event concentrations by 40.77%-83.20%. Diagnostic ratios among VOCs revealed a notable impact of no-vehicle event on the composition and concentrations of the roadside VOCs. Although the shortduration vehicular traffic control had only a limited impact on Sigma VOCs due to the presence of multiple emission sources, it had significant impact on the traffic related VOCs.