A cyclist wearing face mask is seen in Berlin, capital of Germany, April 6, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)

A man wearing self-made face mask and scarf to cover his mouth and nose is seen in Berlin, capital of Germany, May 16, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)

A woman wearing a scarf as substitution of face mask is seen in Berlin, capital of Germany, April 6, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)

A man wearing a kerchief as substitution of face mask is seen in Berlin, capital of Germany, May 16, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)

A cyclist wearing face mask is seen near the Brandenburger Gate in Berlin, capital of Germany, March 28, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)

A woman wearing a neck gaiter as substitution of face mask is seen in Berlin, capital of Germany, May 16, 2020. Many citizens in Berlin choose variety of ways to cover their mouths and noses instead of wearing standard face masks. (Photo by Binh Truong/Xinhua)