Face masks became compulsory in tourist hotspots in Paris on Monday amid warnings of a resurgence of coronavirus cases, as infections in the world’s worst-hit country the United States topped five million.

The requirement came as France along with much of Western Europe sweltered in a heatwave, with temperatures soaring above 35 degrees Celsius (95 F).

The blistering heat sent crowds flocking to beaches at the weekend despite health warnings about the risk of infection.

In Berlin, thousands of children returned to school on Monday after the summer break, sporting masks which are compulsory in common areas like school courtyards. Schools in some other German regions also reopened, though with differing rules on masks.

“No child forgot their masks this morning, so we see everything is back to normal,” said Domenica Acri, headmistress of the Carl Orff primary school in Berlin.

In Pakistan, all restaurants and parks were allowed to reopen Monday, as well theatres, cinemas and public transport, after the country saw a drop in new cases for several weeks.

‘Anything but second lockdown’

People in Paris aged 11 and over are now required to wear the masks in crowded areas and tourists hotspots.

These include the banks of the Seine River and more than 100 streets in the French capital, including tourist destinations like Montmartre, where the Sacre Coeur basilica is located.