Credit: AEV

On Friday 19 August 2022, Luxembourg's Environment Agency (Administration de l'environnement) published the results of nitrogen dioxide (NO2) measurement campaign.

The NO2 measurement campaign, as part of the Climate Pact, was carried out by the Environment Agency between January and December 2021 in participating 24 municipalities across 72 locations. No NO2 meaurement were found to excee the limit of 40 µg/m3. Annual averages of NO2 fell further compared to the previous year. This is explained, among other things, by the maintenance of teleworking measures in 2021, but also by generally favourable weather conditions for the dispersion of atmospheric pollutants.

Results

Following the sharp drop in annual averages in 2020 linked to containment measures, it is significant that the annual averages fell further in 2021. The maintenance of telework measures and generally favourable weather for the dispersion of atmospheric pollutants in 2021 have certainly contributed to this decline beyond the first year of the pandemic. All hotspots observed in 2018 and 2019 have complied with the limit value since 2020.

In general, somewhat higher concentrations of nitrogen dioxide are observed during the winter months due to the additional contribution of emissions from heating installations. In addition, weather conditions in winter favuor periods of temperature inversion that prevent the evacuation of atmospheric pollutants. In summer, better mixing of the air as well as photochemical degradation reactions by ozone lead to a reduction in concentrations.

The low level observed during the period from the end of July to the end of August (cycles 16 and 17) can be explained by the fact that we were in the middle of the summer vacation period with a general drop in road traffic.

Method

The Environment Agency has added nine additional locations on the territory of the City of Luxembourg, the City of Esch-sur-Alzette, the City of Remich and the municipality of Beckerich. The municipalities of Lenningen, Rédange-sur-Attert, Steinfort and Weiler-la-Tour took part in the campaign for the first time in 2021.

Samples are collected every two weeks using simple equipment, passive diffusion tubes, to determine the concentration of nitrogen dioxide at specific locations.

Passive sampling consists of exposing adsorbent tubes to the open air for a fixed period at a height of about three metres. By simple diffusion of the pollutant present in the air, it will be trapped by the sampler. The samples are then analysed in the laboratory by spectrophotometry.

The full report is available on www.emwelt.lu.

Data by station can also be viewed on the geoportal, under the “environment” heading.