It's been more than a month since face coverings became mandatory inside the UK's supermarkets.
But of course not everyone has to wear them. There are exemptions for children under the age of 11 and people who have difficulty using one because of a disability or health condition are also exempt.
But many people who can and should wear a face mask are still going shopping without one.
While supermarkets are not making staff police the new rules, they are encouraging people to follow them in other ways.
And supermarket giant has a subtle trick to encourage people to wear them, the Liverpool Echo reports.
Customers will be met at the store's entrance with face masks for sale, so anyone without one - who should be wearing one - can buy one for their shopping trip.
Tesco has also confirmed via its Twitter account, some staff members may be spotted not wearing a mask due to medical reason after a one customer tweeted Tesco to ask why its staff were not wearing face masks during a recent visit.
Tesco said: "Morning Ben, we’ve asked all our customer-facing colleagues to wear face coverings."
The supermarket giant then continued: "There may be some colleagues, though, who are not wearing masks for medical or safety reasons. These reasons are set out by the government."
