Satellite images released by NASA and the European Space Agency reveal the impact of China's coronavirus shutdown on pollution levels across the country.
Production in many factories was halted and transportation restricted to prevent the virus from spreading in the country.
Images taken from January 1-20 show higher levels of nitrogen dioxide in the air. But from February 10-25, traces of the gas are hardly visible.
“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center.