Impact of automobile exhaust emissions on aerosol and gas concentrations during the SARS-COV-2 lockdown in central Tampere

Abstract

Traffic during the COVID-19 pandemic was affected by the lockdown measures taken to combat the spread of the disease. It was an opportunity to get unique measurements of parti-cle formation by traffic and, in the future, compare the results with the normalized traffic. For this purpose, the Aerosol Laboratory assembled instruments the Atmospheric and Trace gas Mobile Laboratory (ATMo-Lab) capable of analysing particle concentrations, particle distri-butions, and CO2 and NOx concentrations. Measurements were collected over the course of 24/04/2020 to 15/05/2020 during weekdays from approximately 8am to 5pm by driving in traffic and collecting particles through a front mounted inlet. Results show high concentrations of Black Carbon and LDSA in the closed areas and num-bers similar to the baseline urban background measurements. Considering the broad distribu-tion of concentration, we cannot draw further conclusions about emission factors since the background measurements are well within uncertainty. North and South Tunnel, however, showed promise in estimating the value of the emissions on average by the fleet of cars with a total particle mass of 4.88μg/mg of CO2 and 4.25μg/mg of CO2 respectively at PM1. The concentration of black carbon is also of note. The background value of 0.4864 μg/m3 is well below large cities like New York and São Paulo, but the values on the North and South tunnel of 6.83 μg/m3 and 4.35 μg/m3 respectively are comparable to the BC levels in those cit-ies, which might be a point of concern for public health.