Satellite images comparing air quality over China today and a month ago show a dramatic decline in pollution levels, according to NASA. The images show a decline in levels of nitrogen dioxide, which the U.S. space agency says is “at least partly” due to an economic slowdown prompted by the coronavirus. The decrease was first apparent over Wuhan, where the deadly outbreak started late last year. NASA says the restrictions on transportation and business activities contributed to the decrease. The agency also noted a less dramatic reduction in 2008 during the economic recession. Fei Liu, a researcher at Nasa’s Goddard Space Flight Center, said, “This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event.”