Face coverings are set to be mandatory on all public transport if Cabinet approves new rules this week.
The measure will make it an offence not to wear a mask on buses, train and Luas services.
Transport Minister Shane Ross is set to bring a memo to Cabinet tomorrow to implement the rule.
It comes as public transport operators plan to increase capacity to 50% as Covid-19 restrictions are eased.
The National Public Health Emergency Team will meet tomorrow to discuss Phase 3 of the roadmap for easing restrictions.
Six further deaths and five confirmed cases of Covid-19 were reported by the Department of Health yesterday.
Dr. Tony Holohan, Chief Medical Officer, Department of Health, said: “Through our collective action, we have moved in the right direction in our fight against widespread community transmission of COVID-19. As we go forward, the behaviour and progression of this disease is in all of our hands.
“Every single one of us today has the ability to reduce the impact the virus might have on our most vulnerable and those at risk. You can do this by keeping a physical distance from others or wearing a face covering when in busy public places like shops and public transport, and by continuing to keep your number of daily contacts as low as possible.”