Good Morning Britain's Dr Hilary Jones was challenged by presenter Susanna Reid after his comments on the effectiveness of face masks.
The health expert previously warned people that face masks won't completely protect them from contracting Covid-19.
Dr Hilary said that people may find some comfort in using masks when lockdown restrictions are gradually lifted, but added: "If you can breathe freely, the path of the air that you breathe in will take the path of the least resistance which will be between the nose and cheeks, and you're still inhaling the virus."
But Susanna, who has been making her own face masks, challenged Dr Hilary, saying: "Here, we're told there's no hard evidence that they have an impact, whereas in other countries you get fined if you're not wearing one. How can we be so out of step?"
He responded: "The science is divided. You can find as many people saying their next to useless as people saying they're worth wearing."
Piers then chipped in to the debate, saying: "If this science community can't work out if a mask is good or bad for you, why would the government follow anything they say?"
Dr Hilary added: "Masks are useful in certain situations, that's very clear. If you're working in ICU you absolutely need it. If you're a member of public and you're healthy and going down to the shop, the science is not there."
Susanna then argued that she thinks there will be a 'screeching U-turn' on the government's advice on face masks.
She said: "I think with social distancing having to last until the end of the year at least, the government needs to introduce measures which at least feel like they're reassuring."
Dr Hilary replied: "It's a changing situation, the situation is evolving all the time.
"I don't think there can be one rule from the start saying 'this is how we deal with coronavirus today, and it's the same a year down the line'.
"It's got to evolve and it's got to change."
Good Morning Britain continues weekdays on ITV at 6am.
