Nitrogen dioxide emissions have recently decreased in Romania, reveals an analysis of the evolution of this pollutant conducted by the Romanian company Terrasigna using satellite data. The decrease in NO2 pollution observed in Romania may be a consequence of the state of emergency, given that many other studies have documented an improvement in air quality in the same period in other countries as well, such as Italy and France. However, the measurement result reflects a complex combination of several factors, which is difficult to quantify.
Nitrogen oxides are a product of the combustion process and one of the consequences of traffic, industrial activities and electricity production. They are responsible for smog and can cause acid rain, reduce visibility and contribute to the greenhouse effect.
Nitrogen dioxide is very toxic to humans and animals, mainly causing respiratory problems, ranging from respiratory tract irritation to pulmonary emphysema.
The measurements based on data from the European Copernicus Sentinel-5P mission show the weekly evolution of nitrogen dioxide from the beginning of the year until 5 May 2020. Terrasigna processed the data regarding the concentration of this pollutant both for the entire territory of Romania and for the Bucharest and Ilfov area.
The maps are color-coded ranging from light blue, which denotes a low value of nitrogen dioxide, to reddish brown, which represents a high value.
“The graphical representations reveal a decrease in the concentration of carbon dioxide in March, April and early May, a period that coincided with the state of emergency in Romania,” said Florin Serban, General Manager of Terrasigna.
“A sharp decrease can be seen in the dynamics of nitrogen dioxide above the Bucharest-Ilfov region, a trend interrupted by a temporary spike in emissions recorded in the week of April 8-14, 2020, the same week when an extreme pollution phenomenon was widely reported by the capital’s inhabitants”.
The graphs at the bottom left detailing the nitrogen dioxide concentration values allow a better comparison of the weekly values.
The rectangles coloured in yellow (for Romania) and in blue (for Bucharest-Ilfov) represent the middle range of the analysed values during a week and the line in the middle of each rectangle is the median value of the concentrations observed in that week.
The horizontal dotted line was placed to serve as a reference value for the 18-week analysis and represents the median value of nitrogen dioxide concentration in week 11, when a widespread quarantine was declared nationwide. Before week 11, the median values tend to be above the dotted line, while after this week they tend to fall below the benchmark.
The vertically unfolded points represent exceptional values of concentrations.
The data was collected using the Tropomi instrument on the Copernicus Sentinel-5P satellite, which records various air pollutants in the world.