Mobile measurements of black carbon: Comparison of normal traffic with reduced traffic conditions during COVID-19 lock-down

• Published in: Atmospheric environment (1994) Vol. 297; p. 119594
• Main Authors: Van Poppel, Martine, Peters, Jan, Levei, Erika Andrea, Mărmureanu, Luminița, Moldovan, Ana, Hoaghia, Maria-Alexandra, Varaticeanu, Cerasel, Van Laer, Jo
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.03.2023; The Authors. Published by Elsevier Ltd
• Subjects: Black carbon; COVID-19; Mobile monitoring; Traffic emission; Traffic measures; COVID-19; Traffic measures; Mobile monitoring; Traffic emission; Black carbon
• ISSN: 1352-2310; 1873-2844; 1352-2310
• DOI: 10.1016/j.atmosenv.2023.119594

A mobile monitoring campaign was conducted (by bicycle) to assess the black carbon (BC) concentrations in Cluj-Napoca city, Romania, in 2020, before, during and after COVID-19 lock-down. Over the entire study period, the BC concentrations ranged between 1.0 and 25.9 μg/m³ (averaged per street section and period characterized by different traffic conditions). Marked spatial and temporal differences were observed. Observed differences in BC concentrations between locations are attributed to traffic intensities, with average BC concentrations, under normal circumstances, of 6.6–14.3 μg/m³ at roads with high to intense traffic, compared to 2.8–3.1 μg/m³ at areas with reduced traffic, such as residential areas, parks and pedestrian streets. The COVID-19 measures impacted traffic volumes, and hence average BC concentrations decreased from 5.9 μg/m³ to 3.0 μg/m³ during lock-down and in a lower extent to 3.4 μg/m³ and 4.4 μg/m³ in post-lockdown periods with reduced and more normalized traffic. Two approaches to account for variations in background concentrations when comparing different situations in time are assessed. Subtracting background concentrations that are measured at background sites along the monitoring route is an appropriate method to assess spatio-temporal differences in concentrations. A reduction of about 1–2 μg/m³ was observed for the streets with low to medium traffic, and up to 6 μg/m³ at high traffic locations under lockdown. The approach presented in this study, using mobile measurements, is useful to understand the personal exposure to BC along the roads in different seasons and the influence of traffic reduction on BC pollution during prolonged restrictions. All these will support policymakers to reduce pollution and achieve EU directives targets and WHO recommendations. [Display omitted] •Black Carbon (BC) concentration in Cluj-Napoca depend on the traffic intensity.•Traffic restriction due to COVID-19 pandemic reduced BC concentrations.•Mobile measurements can be used to assess spatial variability of BC.•Background corrections are needed to assess the impact of traffic measures on BC.•Traffic-free zones along the routes can be used for background corrections of BC.