Employees of the Municipality of Athens disinfect a hallway at a primary school in Athens, Greece, May 31, 2020. Primary schools and kindergartens in Greece reopened on Monday. (Xinhua/Marios Lolos)

Employees of the Municipality of Athens disinfect a hallway at a primary school in Athens, Greece, May 31, 2020. Primary schools and kindergartens in Greece reopened on Monday. (Xinhua/Marios Lolos)

An employee of the Municipality of Athens disinfects a classroom at a primary school in Athens, Greece, May 31, 2020. Primary schools and kindergartens in Greece reopened on Monday. (Xinhua/Marios Lolos)

An employee of the Municipality of Athens disinfects stairs at a primary school in Athens, Greece, May 31, 2020. Primary schools and kindergartens in Greece reopened on Monday. (Xinhua/Marios Lolos)