(KRON) — The East Bay Transit Riders Union called on the AC Transit Board of Directors to reinstate a mask mandate on their busses.

The union, according to its website, is an East Bay public transportation organization dedicated to the expansion and survival of public transit in the East Bay area.

The decision to challenge AC transit happened when the agency adopted a voluntary mask policy last Wednesday. Recent legislation that overruled mandatory masking policies caused transportation systems to change their mask requirements.

However, AC Transit still encourages the use of masks.

“AC Transit strongly recommends that our riders continue to wear facemasks when boarding, riding, and exiting the bus,” the agency said on their website regarding the new rules.

The East Bay Transit Riders Union asked AC transit to re-enact the mask rule in a letter. They believe making masking optional puts immunocompromised people at risk of COVID-19 infection. They say masks significantly reduce the transmission of the virus and will keep everyone safe.

“We of the East Bay Transit Riders Union call on AC Transit Board of Directors to reinstate a mask requirement on buses, undoing the recent right-wing politically-motivated judicial action against the federal rule,” the union said in a statement to AC Transit.

AC Transit is expected to meet virtually on Wednesday April 27 at 5 p.m. to discuss concerns about voluntary masking.