WASHINGTON, June 10 (Reuters) - The U.S. Centers for Disease Control and Prevention said on Thursday it will no longer require travelers to wear masks in outdoor transit hubs and in outdoor spaces on ferries, buses and trolleys, due to the lower risk of coronavirus transmission outdoors.

The change is the first in the CDC's transit mask policy announced in January and came after a lengthy review by the White House Office of Management and Budget's regulatory arm.

The CDC said it made the change "because of the lower risk of transmission outdoors ... Masks are still required indoors on all forms of transportation" regardless of vaccination status.

The change means people can take masks off outdoors while waiting for a train, in an outdoor courtyard of an airport or in open-air transit modes.

The change came after the Biden administration held extensive discussions with transit unions and other groups. The administration is considering other modest changes to its indoor transit mask policies, including potentially allowing vaccinated airline workers to remove their masks in rooms not accessible to the public.

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The CDC in May said fully vaccinated people do not need to wear masks outdoors and can avoid wearing them indoors in most places.

In April, the Biden administration extended face mask requirements across all U.S. transportation networks through Sept. 13 to address the spread of COVID-19.

The Federal Aviation Administration said this week it has received approximately 2,900 reports of unruly behavior by passengers since Jan. 1, including about 2,200 reports of passengers refusing to comply with the federal face mask mandate.

The CDC mask mandate issued in January requires masks in nearly all transportation modes, including on ride-share vehicles.

Many U.S. states have completely rescinded mask requirements and transit is the only remaining place where mask use is mandated.

President Joe Biden imposed the transit mask mandate after his predecessor, Donald Trump, rejected CDC recommendations to do so.

(Reporting by David Shepardson in Washington Editing by Chris Reese and Matthew Lewis)