[Publication Date: December 2020]
During last spring's lockdown, both emissions and air pollution along the A22 fell dramatically: two thirds less carbon dioxide (CO2) emissions and nitrogen dioxide (NO2) concentrations halved. This was confirmed in a study by the BrennerLEC project and the environmental agencies of the provinces of Bolzano and Trento. The lockdown period from March to April 2020 provided an opportunity to assess the air quality along the Brenner motorway in a situation of extremely low traffic compared to the same period in the previous three years. During this period, light and heavy vehicle transits on the A22 decreased by 92% and 42% respectively compared to other years.
The results of the study
The study showed that pollution fell significantly during the lockdown, despite the fact that heating-related emissions were even higher than in the previous three years. Estimates of nitrogen oxide (NOx) and carbon dioxide (CO2) emissions based on traffic reductions showed a 66% and 64% drop respectively when compared to the same period in the previous three years. These reductions in traffic volumes have thus led to a significant reduction in air pollution in the vicinity of the motorway, with a 50% decrease in nitrogen dioxide (NO2) concentrations. However, the benefits also extended to significant distances from the motorway, with a 37% decrease in NO2 in Cortina all'Adige (i.e. 230 metres from the motorway). This evidence confirms that a major source of emissions such as the motorway influences air quality not only in the immediate vicinity of the motorway, but also at locations hundreds of metres away.
Black carbon' traffic data
The sharp drop in traffic emissions and the persistence of emissions from wood-fuelled heating is also confirmed by an analysis of data on the pollutant "black carbon" (a component of fine particulate matter), which is formed through the combustion of fossil fuels (oil derivatives and methane gas) and biomass (mainly firewood), i.e. generated mainly by engines and wood-fuelled heating systems. Using an instrument (etalometer), it was possible to measure the black carbon component from traffic (which decreased by 57% during the lockdown), and to distinguish it from the heating component, which increased by 5% during the same period. Since these results are of great interest to the scientific and institutional community (black carbon is not yet considered in legislation), the study was included in the Report "Air quality in Italy" by SNPA (National System for Environmental Protection), which was recently presented at national level.
The full report on the evaluation of the impact of measures to counter the Covid-19 pandemic on air quality along the Brenner motorway can be downloaded here (in Italian language).