Advice also covers industrially made category 2 fabric masks with lesser filtering qualities

France has issued a decree banning certain homemade masks from being worn in public, saying they do not offer sufficient protection from the newer, more contagious Covid-19 variants.

Olivier Véran, the health minister, said a decree published on Friday came after recommendations from the country’s health experts.

“The high council for public health recommends, as do I, that the French do not wear masks they have made at home,” Véran said. He said the advice also covered industrially made fabric masks with lesser filtering qualities, listed as category 2.

On Monday, France’s junior minister responsible for health at work confirmed that official advice was to be changed to stop people wearing homemade masks in the workplace.

“The government is scrupulously following the recommendations of the High Council for Public Health and has done so since the beginning of this crisis,” Laurent Pietraszewski told Franceinfo radio.

He said the new health protocol in the workplace would be adapted “as usual, after discussions with the unions”.

Only three types of masks will be recommended: surgical, the FFP2 and fabric masks made to category 1 standards.

The recommendation has been criticised by the French Academy of Medicine that says there is a lack of scientific proof that homemade masks do not offer sufficient protection if worn properly.

The French authorities have admitted the new decree will be difficult to enforce.

“I don’t imagine the police are going to be asking people the protection level of their mask,” a spokesperson for the prime minister said.

Category 1 masks filter 95% of 3-micrometre particles, whereas category 2 devices only filter 70%. Surgical masks filter 95%. FFP2 masks filter 94% of even smaller 0.6-micrometer particles.

The government says the aim of the decree is to ensure “better individual protection, but above all to increase collective protection by ensuring a maximum of people are wearing a mask that filters enough”.

“We ask that this is the norm from now on … we have to get this clear message across to the French,” the PM’s office added.

Officials admit it is not always easy to know the filter properties of masks. The category is not marked on most masks, though it is supposed to be clearly printed on the packaging or accompanying customer notice.

Prof Jean-François Delfraissy, president of the government’s scientific committee, told BFMTV: “The coronavirus mutations and variants have completely changed the game over the last three weeks.” He said the new strains of Covid-19 were more contagious and therefore spread more quickly.

Last Friday, two associations – one of doctors and a second of victims of Covid-19 – lodged an official demand to the state council demanding the wearing of FFP2 masks be made obligatory in public transport, shops and universities. The council will consider the demand this week.

Véran said scientific committee had not – as yet – recommended the widespread use of FFP2 masks.

“Theoretically they provide better protection, but they have to be used correctly and must fit closer to the face,” Alexandre Bleibtreu, an infection specialist at the Pitié-Salpêtrière hospital in Paris told La Croix newspaper.