Parents are being warned not to buy face coverings for babies and young children, after health officials found retailers targeting the young.
Public Health England (PHE) warned that children under the age of three are at risk of choking and suffocating if their faces are covered.
From Friday, wearing face coverings will be mandatory in shops, supermarkets and takeaway restaurants as well as banks, post offices and a range of other public settings. Those who fail to observe the rules could face fines of £100.
However, it is not required for those under the age of 11, and PHE has warned that it is dangerous for the youngest children.
Latest data from the Office for National Statistics (ONS) shows 71 per cent of adults are now wearing a face covering when they leave home, up from 61 per cent in a week.
Amid confusion about new rules which come into force on Friday, making face coverings mandatory in shops, ministers on Thursday published detailed guidance setting out when they must be worn.
While face coverings must be worn in all shops, including sandwich shops, and for collection of takeaways, restaurants and pubs remain exempt.
Other exemptions include visitors to museums, cinemas, concert halls, theatres, hairdressers, gyms and leisure centres, dentists and opticians.
Nor is it compulsory for shop or supermarket staff to wear face coverings, although the guidance “strongly recommends” their use.
The new advice sets out situations in which shoppers will be expected to wear coverings – but to be ready to remove them if challenged.
Those buying alcohol, or visiting a bank or post office, could be asked to show their full face, in order to prove their identity, or age.