Doctors have urged the government to make face coverings compulsory in all places where social distancing is not possible, not just on public transport.
All passengers on public transport in England must wear a covering from 15 June, the government said on Thursday.
But the British Medical Association, the doctors’ union, said masks “should not be restricted” to transport.
It also said the risk from coronavirus would be “much less” if the rule started now, not later in the month.
Face coverings – which can be homemade – must be worn on buses, trams, trains, coaches, aircraft and ferries.
Passengers will not be allowed to travel without one, and if they do not wear one they could be fined.
People in Scotland and Northern Ireland are currently recommended to wear coverings in places where social distancing is more difficult. The Welsh government says it is a matter of personal choice.
Transport Secretary Grant Shapps said the new measure comes as passenger numbers are expected to increase when lockdown measures are eased further.
From 15 June in England, secondary schools and colleges will open to some students, while shops can reopen if they put social distancing rules in place.
The BMA recommended that people consider wearing mask in places where they cannot socially distance back in April.
Speaking after the government made them compulsory, BMA council chair Dr Chaand Nagpaul said: “These important measures should not be restricted to public transport but to all areas where social distancing is not always possible – the risk will be much less if the public adopts this now – not mid-June.”
Dr Nagpaul also said the government should ensure the public are supplied with face coverings, as well as providing advice on how to wear them correctly.