A leading immunologist says wearing face coverings should be a condition of travel on public transport.
Professor Luke O'Neill told Pat Kenny: "It might be hard to make it compulsory - I would definitely make it a condition of travel on public transport, like the UK has done.
"It's just called a condition of travel: you can't get on the bus with a gun, nor can you get on a bus without a mask".
On the issue, he said: "It's a bit like climate change - you will get the odd climate change denier in debates, won't you?
"There's always a few mavericks... who go against it and don't like the evidence or whatever.
"The second problem has been there hasn't been a proper controlled trial and scientists love that.
"In other words you give masks to 1,000 people, you leave 1,000 people out and see what happens.
"You can't do that in a pandemic, it's unethical".
"But the evidence has got stronger and stronger and stronger - even a month ago in my opinion it was extremely strong.
"The reluctance is staggering - I suspect they haven't kept up with the science, our experts, sadly".
He said there has been a shift in recent days, with the Taoiseach Leo Varadkar 'advocating masks'.
"I think it's getting through in the end, and we're going to see more and more of this".
But he added: "The messaging has been all wrong on this one, especially this week tragically.
"The messaging has to be 100% crystal clear, signs up everywhere: 'Wear a mask'.
"There's ways of getting the public to sort of comply with health guidance...and this should be all put in place now.
"Otherwise people go 'I'm not going to bother wearing it'".
Meanwhile a new study has found COVID-19 was found on just 3% of household surfaces.
Some 21 houses studied with one infected person in each house.
Samples were taken from several surfaces over a number of weeks.
While 15% of samples from toilets were positive for the virus.
Prof O'Neill said: "Amazingly there wasn't that much virus detected on surfaces.
"There was some obviously, so we still need to wipe them down, but it means you need to be less worried about surfaces".
"It reiterates that the main source is other people - they cough at you or breathe at you - that's where you pick up the virus, much more than touching a surface that's been contaminated".