Dr Sarah Jarvis has issued a warning to Good Morning Britain viewers today, ahead of the new face mask rules coming into force on Friday.
As of Friday July 24 the public will have to wear face masks in shops and on public transport in England, as the government tries to tackle the Covid-19 pandemic.
If people refuse to wear a mask they could be slapped with a £100 fine.
Dr Jarvis, who is standing in for Dr Hilary while he's on holiday, warned viewers at home that wearing a mask alone will not protect them from coronavirus.
She said that masks have to be used effectively, and not become contaminated, suggesting people wear them at home to get used to it.
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If people don't wash their hands regularly they risk contaminating their mask and face - reports the Manchester Evening News.
Dr Jarvis said: "One of the big issues with face masks is that if you fiddle with them and you haven't washed your hands then you could contaminate your face.
"It's a really good idea to start wearing one when you are at home.
"That will mean you can get into the habit of putting it on only using the straps, not touching your face when taking it on or off.
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"Not putting it underneath your chin or dangling it on one ear - none of those things will work and could contaminate you.
"And not putting it under your nose."
Good Morning Britain airs weekdays at 6am on ITV.
