As millions of people around the world quarantine in their homes to prevent the spread of COVID-19, research and photos show that quarantines appear to have made a positive, if unintended, impact on the environment.

In February, air quality researches from NASA reported that there was a dramatic drop in nitrogen dioxide emissions coming from China, especially from Hubei province — the epicenter of the coronavirus pandemic.

“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” says Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center told CNN earlier this month. “I am not surprised because many cities nationwide have taken measures to minimize the spread of the virus.”

CNN also reports pollution in some of Hong Kong’s busiest areas have fallen dramatically as government officials have introduced measures requiring many to work from home.

China isn’t alone. Photos from Venice, Italy show that the water clarity has drastically improved as thousands of boats stay docked amid the country’s drastic quarantine measures. Video taken in recent days from Venice even shows dolphins swimming through the canals of the city.

In America, a search through the EPA’s AirNow air quality index archive shows a decrease in areas with moderate air pollution in recent months. Los Angeles is one of the most improved areas of air quality, given the fact that there is much less traffic on the roads currently.

Click here to view the EPA’s AirNow Air Quality Index Archive