People are being urged to wear face coverings on public transport from today.
It is now compulsory to wear coverings as public transport capacity increases - although the rules are not enforceable until the required regulation comes into force in the coming weeks.
The National Transport Authority says making masks or other coverings compulsory is vital from a public health point of view, as capacity increases from around 20% to 50%.
Anne Graham, CEO of the NTA, told Newstalk Breakfast that this week they're working on encouraging to have their face covering while on public transport.
She said: "We haven't got the means to enforce it at this stage, but that is coming.
"That's why for this week and for the next week or so we will be encouraging our customers to wear face coverings - but we will be enforcing it at a later stage.
"It's likely it will be enforced through fines - so if you're wearing a face covering, there'll be a fine associated with that."
She explained that demand was increasing for public transport, so they're grateful to be able to allow more people travel.
However, she stressed: "It's still not 100% - we still do require people where they can to work from home, and if they do need to travel they might consider walking or cycling if their journey is short."
Her message to all commuters is: "Wear a face covering, please".
The new capacity translates to 36 or 37 people on a double-decker bus - up from 17 in recent weeks and months.