Air pollution halved in European cities during lockdown

Paris, Apr 16 (efe-epa).- Satellite images have revealed air pollution in some European cities has been halved over the last month during widespread coronavirus lockdowns, the European Space Agency said Thursday.

Aerial photographs taken by the European Sentinel-5P satellite show nitrogen dioxide (NO2) concentrations fell by up to 54 per cent in Paris, 49 per cent in Rome, 48 per cent in Madrid and 47 per cent in Milan between 13 March and 13 April compared to the same period in 2019.

NO2 is produced by power plants, vehicles and other industrial facilities and can have significant impacts on human health, increasing the likelihood of developing respiratory problems, the ESA said in a statement.

Scientists from the Royal Netherlands Meteorological Institute (KNMI) have spent months monitoring air pollution in Europe using data from the Tropospheric Monitoring Instrument, a device designed to measure several different pollutants, in the Copernicus Sentinel-5P satellite.

NO2 concentrations in the atmosphere vary substantially from day to day due to fluctuations in emissions and changes in meteorological conditions making it difficult to draw conclusions from daily or weekly measurements.

Analysing the data over a longer period has allowed scientists to rule out these possible anomalies.

Henk Eskes, from the KNMI, said in a statement: “There are considerable variations of weather in every country from one day to the next, creating a large impact on the dispersion of nitrogen dioxide.

“Averaging data over longer periods of time allows us to see clearer changes in concentrations owing to human activity.

“For this reason, the maps show concentrations over a monthly period and are provided with an uncertainty of 15 per cent which reflects weather variability not accounted for in the monthly averages used.”

His team intends to take advantage of the quarantine measures to continue working on more detailed analysis of other northern European countries in the coming weeks, where there was greater variability in the results due to weather changes.

Using air-quality models, such as the Copernicus Atmosphere Monitoring Service, and combining results from in situ data will narrow down the impact of changes in weather on air pollution estimates, the ESA said.

The Sentinels are part of a European Union fleet of satellites designed to supply information for the Copernicus environmental program. EFE-EPA


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