Most workers in France will soon have to wear masks in the workplace from Sept. 1 under proposals unveiled Tuesday by the country’s labor ministry.

The move is intended to encourage companies to resume their normal economic activities while keeping employees safe. It follows advice issued Friday by the country’s High Council of Public Health, which was reacting to the increasing scientific consensus that the novel coronavirus is spread through the air. Masks reduce the risk of infected people spreading the virus.

In a Tuesday statement, the labor ministry said masks would need to become de rigueur in companies’ enclosed and shared spaces, except where there is just one person working alone.

The ministry said remote working was still the recommended practice, because of how it limits the spread of infection in the workplace and on public transport.

“The protection of workers’ health and the continuity of our economic activity are at stake,” said Élisabeth Borne, the French labor minister, in a statement. Laurent Pietraszewski, her secretary of state, said the ministry would now work with stakeholders to figure out how to implement the new rules.

France is experiencing a growing wave of COVID-19 infections. Over the weekend, it recorded more than 3,000 new cases each day.

According to health authorities, workplaces were the source for a quarter of the infection clusters reported since the lifting of heavy lockdown. The government is now desperate to avoid needing to reimpose such strict measures as those that were lifted in May, following the initial lockdown period.

Last week, French Prime Minister Jean Castex warned the public: “If we don’t act collectively, we expose ourselves to the heightened risk that the rebound in the epidemic becomes hard to control.”

The recognition of COVID-19 as an airborne disease has led to a gradual increase in mask mandates. Many European countries have for months required people to wear masks in shops and on public transport, but Italy, for example, has just ordered people to wear masks at night in public areas where groups might form.

Still, it is unusual to see masks mandated in offices.

French labor unions have been pushing for such a move. Amazon’s French workers went on strike in May, and one complaint was the lack of masks in the workplace.

The unions have demanded better workplace protections in place by next month, when schools are scheduled to reopen and workers will be returning from their treasured summer vacations—another notable vector for the spread of the virus.

“The best thing we can do to prepare for the start of the school year is to reassure employees that, collectively, we are taking precautions to prevent the spread of the virus,” said Borne in her ministry’s statement.

Fortune has asked the ministry what enforcement measures there will be, but had not received a reply at the time of writing.

France’s General Confederation of Labour, one of the country’s largest unions, gave the ministry’s announcement a cautious welcome. “Wearing a mask is an individual protection solution,” it said in a statement, “but [it] cannot be the only one.”