LOS ANGELES, Calif. (CNN) — Los Angeles had the cleanest air of any major city in the world on Monday, according to IQ Air’s live air quality city rankings.

It is followed by San Francisco, Portland, Oregon, Sydney in Australia and Moscow, Russia.

This is odd, so what is going on? The most likely explanation is with so many people sheltering in place, fewer cars are on the road, creating less pollution.

FILE – In this June 24, 2010 file photo, the Los Angeles skyline is seen above the Union Pacific Railroad East Los Angeles Intermodal facility in the City of in Commerce, Calif. A long-term plan for cleaning up the air in a huge swath of smoggy Southern California is due for consideration by regulators. Directors of the South Coast Air Quality Management District are expected to vote on the plan Friday, March 3, 2017. (AP Photo/Damian Dovarganes, File)

Human activity is also slowing down all around, with fewer airplanes in the sky and less commercial activity across the board.

Experts think this blip will reverse itself as soon as normal activity resumes.

The dirtiest air in the world right now can be found in Taiwan, China and India.