Video report by ITV News Science Editor Tom Clarke
The wearing of face coverings will be compulsory on public transport in England from June 15, the transport secretary has announced.
Travellers could be fined or refused permission to board buses or trains if they refuse to comply with the order.
It follows weeks of deliberation following advice from Sage which said there is limited evidence to suggest face coverings "offer some, albeit limited protection" against the spread of the virus.
The evidence suggests face coverings do not protect the wearer, but could reduce the likelihood the wearer will pass on infection.
"A face covering helps protect out fellow passengers, it's something that we can each do to help each other," Grant Shapps said.
Staff who come into contact with passengers, such as police and ticket inspectors, will also need to wear face coverings.
The transport secretary said the government is working with unions, transport operators and the police to "ensure that they’ve the supplies they need to be safe and to provide reassurance to the public".
Mr Shapps said people should not be wearing "surgical masks, which we must keep for clinical settings".
"It means the kind of face covering you can easily make at home," he added.
There will be exemptions to the rules for very young children, for disabled people and those with breathing difficulties.
London Mayor Sadiq Khan said he was "pleased" the government had "finally seen sense" on the issue of face coverings.
“This is something I and others have been calling on ministers to do for some time, and is in line with a large body of evidence that they can help stop the spread of coronavirus," he said.
Mr Shapps said the rule change is being made to coincide with "easements" to lockdown which will see some non-essential retail shops and secondary schools reopen on June 15.
He said this, along with the "ramping up" of services on buses, trams and trains, will "keep us safe and reduce the risk of coronavirus particularly on public transport".
The transport secretary is speaking at the government's daily coronavirus press conference alongside Sir Peter Gerard Hendy, the chairman of Network Rail.
Mr Shapps said guidelines, such as social distancing and not using public transport during peak times, should still be followed.
He said “we need to ensure every precaution is taken on buses, trains, aircraft, and on ferries”.
Mr Shapps said he wants to use the recovery from the pandemic to ensure people travel by greener means.
Mr Shapps told the Downing Street briefing that there has been a 100% increase in weekday cycling going up to 200% at the weekend compared to pre-Covid-19.
“We want to use this recovery to permanently change the way we travel,” he said.
The UK's death toll now stands at, 39,904, the transport secretary announced at the press conference, an increase of 176 deaths since yesterday.
Some 220,057 coronavirus tests were "posted" yesterday, Mr Shapps said, but it does not mean that number of tests were carried out.
It comes as Boris Johnson awaits the results of Alok Sharma's coronavirus test, which he took after becoming ill in the House of Commons.
Mr Johnson, who held a 45-minute meeting with the business secretary shortly before Mr Sharma fell ill, would be forced to isolate for up to 14 days if the test result is positive - despite having already had the virus himself.
Mr Sharma is “doing fine”, his Cabinet colleague Grant Shapps said.
The transport secretary said he had spoken to Mr Sharma within the past hour and the business secretary was working from home while he awaited the result of his coronavirus test.
Earlier Prime Minister Johnson opened a conference aimed at raising funds for the global coronavirus vaccination effort.
He told the Gavi vaccine alliance meeting he hopes the it will be a “moment when the world comes together – uniting humanity in the fight against disease”.