Krüger et al. present observations of the effect of the COVID-19 lockdowns on black carbon emissions using a combination of airborne in situ observations and models. The impact of lockdowns on emissions from transport is by now well established, however the majority of studies to date have focused on NO2 as this is a regulated pollutant and high resolution observations are available in new satellite data products. This work instead uses a state-of-the-art airborne facility (DLR HALO) to report data on black carbon, which has established impacts both as a airborne pollutant damaging to human health, and as a highly potent short-lived climate forcing agent. Data from during the European lockdown period is compared with the prior EMeRGe campaign (https://acp.copernicus.org/articles/special_issue1074.html). The authors found a decrease in BC concentrations of 48% over Western and Southern Europe, of which 7% was likely due to meteorological differences during the two campaigns and 3-9% was due to a long-term downward trend, leading them to conclude that the lockdowns were overall responsible for a reduction in ambient concentrations of 32-38%. By seizing this unique opportunity, this study offers a new and unparalleled insight into the current nature of black carbon emissions from Europe. It also demonstrates how airborne in situ measurements and models can be used in combination to study the emission and transport of pollutants in the troposphere.