Satellite imagery Monday showed air pollution in urban areas around
Europe during closings to combat the spread of the Coruna virus, but activists have warned that city dwellers remain the most vulnerable to the pandemic.

Satellite images "Sentinel-5" showed a decrease in the average levels of harmful nitrogen dioxide in cities including Brussels, Paris, Madrid, Milan and Frankfurt between the 5 and 25 of March this year compared to the same period last year.

This coincides with the closure in many European countries that have restricted road travel, which is the largest source of nitrogen oxide, and slowed plant gas emissions.

The new images released by the European Space Agency and analyzed by the European Public Health Alliance, a non-profit organization, show a change in the nitrogen dioxide density that can cause problems in
Respiratory system and cancer.

Data from the European Environment Agency showed a similar trend between 16 and 22 March. Madrid's average nitrogen dioxide levels have fallen by 56% on a weekly basis after the Spanish government banned unnecessary travel on March 14.

The European Public Health Alliance said that people living in polluted cities may be at greater risk of contracting the "Covid-19" virus because prolonged exposure to polluted air can weaken the immune system, making it more difficult to fight infection.

Air pollution may cause lung cancer, pulmonary diseases and strokes to occur.