Residents of Turkey’s largest city taking mass transit now must wear face masks to help stem the spread of the novel coronavirus, authorities said Friday.

“Passengers without a face mask will not be admitted on buses, metro, metrobus, or city line ferries as of tomorrow,” Murat Ongun, a spokesperson for the Istanbul Municipality, said on Twitter.

A total of 118 municipality staffers have tested positive for coronavirus, Ongun added.

Earlier today, Turkey’s Health Minister Fahrettin Koca said that an analysis found that on average, one person carrying COVID-19 in Istanbul infects 16 others.

Nationwide, the wearing of face masks

Read more: COVID-19: Istanbul mass transit riders must wear masks