Covid-19 pandemic forced many countries to impose nationwide lockdown to control the
infection rate, and as part of lockdown measures, people mobility and economic activities got
restricted. Amongst all the damage caused by lockdown measures, conversely, it improved the
air quality, and a major reduction was observed in NO2 concentration which was directly linked
to anthropogenic activities. This study aims to selectively assess the reduction of NO2
concentration around Europe and make a comparative analysis between satellite sensor data as
well as ground station measurements on a Spatio-temporal scale, between two sets of similar
periods from 2019 and 2020 (lockdown and post-lockdown phases). 15 regions that emerged
as hotspots in 2019 Sentinel-5P Tropospheric NO2 column number density imagery was
selected to investigate in 2020 if air quality has improved due to lockdown. The study results
confirmed that, in the Lockdown phase, the ITC4 region achieved 51% of NO2 reduction
followed by 39% in FR1, 37% in the ES30 region and 34% in the UKI region, whereas in the
Post-Lockdown Phase under lockdown easing measures the NO2 level began turning up again,
however, when compared to the NO2 concentration of 2019, UKI gained 33% reduction
followed by 22% in NL32, 18% in the UKD and 17% in BE2, overall the air quality improved
due to lockdown measures which may have linked to restricted traffic and economic practices.
Despite the considerable reduction in NO2 concentration, there is a need to look at associated
pollutants and other meteorological factors which could have influenced, the study concluded
that this air quality improvement is temporary and for an everlasting solution, policies towards
environmental protection need to be evaluated which requires sustainable approaches and strict
actions.